2-methylisoborneol and geosmin

Off-flavours in fish products generated from recirculating aquaculture systems (RAS) are a major problem in the fish farming industry affecting the market demand and prices. A particular concern is the muddy or musty odour and taste in fish due to the presence of secondary metabolites geosmin and 2-methylisoborneol (2-MIB), produced by actinobacteria (mainly Streptomyces), myxobacteria and cyanobacteria. Off-flavours have deteriorated the quality of fish, rendering their products unfit for human consumption. The process of odour removal requires purification for several days to weeks in clean water; thus this leads to additional production costs. Geosmin and 2-MIB, detected at extremely low odour thresholds, are the most widespread off-flavour metabolites in aquaculture, entering through fish gills and accumulating in the fish adipose tissues. In this review, we aimed to determine the diversity and identity of geosmin- and 2-MIB-producing bacteria in aquaculture and provide possible strategies for their elimination.

Topics: Animals; Camphanes; Cyanobacteria; Fishes; Naphthols; Odorants; Water

Taste and odor (T&O) are an important issue in drinking water, aquaculture, recreation and a few other associated industries, and cyanobacteria-relevant geosmin and 2-methylisoborneol (2-MIB) are the two most commonly detected T&O compounds worldwide. A rise in the cyanobacterial blooms and associated geosmin/2-MIB episodes due to anthropogenic activities as well as climate change has led to global concerns for drinking water quality. The increasing awareness for the safe drinking, aquaculture or recreational water systems has boost the demand for rapid, robust, on-site early detection and monitoring system for cyanobacterial geosmin/2-MIB events. In past years, research has indicated quantitative PCR (qPCR) as one of the promising tools for detection of geosmin/2-MIB episodes. It offers advantages of detecting the source organism even at very low concentrations, distinction of odor-producing cyanobacterial strains from non-producers and evaluation of odor producing potential of the cyanobacteria at much faster rates compared to conventional techniques.The present review aims at examining the current status of developed qPCR primers and probes in identifying and detecting the cyanobacterial blooms along with geosmin/2-MIB events. Among the more than 100 articles about cyanobacteria associated geosmin/2-MIB in drinking water systems published after 1990, limited reports (approx. 10 each for geosmin and 2-MIB) focused on qPCR detection and its application in the field. Based on the review of literature, a comprehensive open access global cyanobacterial geosmin/2-MIB events database (CyanoGM Explorer) is curated. It acts as a single platform to access updated information related to origin and geographical distribution of geosmin/2-MIB events, cyanobacterial producers, frequency, and techniques associated with the monitoring of the events. Although a total of 132 cyanobacterial strains from 21 genera and 72 cyanobacterial strains from 13 genera have been reported for geosmin and 2-MIB production, respectively, only 58 geosmin and 28 2-MIB synthesis regions have been assembled in the NCBI database. Based on the identity, geosmin sequences were found to be more diverse in the geosmin synthase conserved/primer design region, compared to 2-MIB synthesis region, hindering the design of universal primers/probes. Emerging technologies such as the bioelectronic nose, Surface Enhanced Raman Scattering (SERS), and nanopore sequencing are discussed for future applicatio

Topics: Camphanes; Cyanobacteria; Drinking Water; Naphthols; Odorants

The exposure to geosmin (GSM) and 2-methylisoborneol (2-MIB) in water has caused a negative impact on product reputation and customer distrust. The occurrence of these compounds and their metabolites during drinking water treatment processes has caused different health challenges. Conventional treatment techniques such as coagulation, sedimentation, filtration, and chlorination employed in removing these two commonest taste and odor compounds (GSM and 2-MIB) were found to be ineffective and inherent shortcomings. The removal of GSM and MIB were found to be effective using combination of activated carbon and ozonation; however, high treatment cost associated with ozonation technique and poor regeneration efficiency of activated carbon constitute serious setback to the combined system. Other shortcoming of the activated carbon adsorption and ozonation include low adsorption efficiency due to the presence of natural organic matter and humic acid. In light of this background, the review is focused on the sources, effects, environmental pathways, detection, and removal techniques of 2-MIB and GSM from aqueous media. Although advanced oxidation processes (AOPs) were found to be promising to remove the two compounds from water but accompanied with different challenges. Herein, to fill the knowledge gap analysis on these algal metabolites (GSM and 2-MIB), the integration of treatment processes vis-a-viz combination of one or more AOPs with other conventional methods are considered logical to remove these odorous compounds and hence could improve overall water quality.

Topics: Camphanes; Environmental Monitoring; Naphthols; Odorants; Water; Water Pollutants, Chemical; Water Purification

The treatment of cyanobacterial metabolites can consume many resources for water authorities which can be problematic especially with the recent shift away from chemical- and energy-intensive processes towards carbon and climate neutrality. In recent times, there has been a renaissance in biological treatment, in particular, biological filtration processes, for cyanobacteria metabolite removal. This in part, is due to the advances in molecular microbiology which has assisted in further understanding the biodegradation processes of specific cyanobacteria metabolites. However, there is currently no concise portfolio which captures all the pertinent information for the biological treatment of a range of cyanobacterial metabolites. This review encapsulates all the relevant information to date in one document and provides insights into how biological treatment options can be implemented in treatment plants for optimum cyanobacterial metabolite removal.

Topics: Alkaloids; Animals; Bacterial Toxins; Biodegradation, Environmental; Camphanes; Cyanobacteria; Cyanobacteria Toxins; Filtration; Humans; Microcystins; Naphthols; Peptides, Cyclic; Saxitoxin; Tropanes; Uracil; Water Purification

The occurrence of off-flavor problems caused by prokaryotes cyanobacteria and actinomycetes is a worldwide water and food quality issue. Based on literatures on two earthy-muddy-smelling metabolites, (i. e., geosmin and 2-methylisoborneol (2-MIB)), we reviewed their chemical characteristics, biosynthetic pathways, genes and enzymes that are involved in biosynthesis. Then we discussed current research questions related to off-flavor and future directions. Finally, we addressed the significance of probable key regulatory mechanism for the production and release of geosmin and 2-MIB, which could provide more scientific strategies to better control off-flavors outbreaks in drinking and aquaculture water.

Topics: Actinobacteria; Camphanes; Cyanobacteria; Naphthols

Problems due to the taste and odor in drinking water are common in treatment facilities around the world. Taste and odor are perceived by the public as the primary indicators of the safely and acceptability of drinking water and are mainly caused by the presence of two semi-volatile compounds--2-methyl isoborneol (MIB) and geosmin. A review of these two taste and odor causing compounds in drinking water is presented. The sources for the formation of these compounds in water are discussed along with the health and regulatory implications. The recent developments in the analysis of MIB/geosmin in water which have allowed for rapid measurements in the nanogram per liter concentrations are also discussed. This review focuses on the relevant treatment alternatives, that are described in detail with emphasis on their respective advantages and problems associated with their implementation in a full-scale facility. Conventional treatment processes in water treatment plants, such as coagulation, sedimentation and chlorination have been found to be ineffective for removal of MIB/geosmin. Studies have shown powdered activated carbon, ozonation and biofiltration to be effective in treatment of these two compounds. Although some of these technologies are more effective and show more promise than the others, much work remains to be done to optimize these technologies so that they can be retrofitted or installed with minimal impact on the overall operation and effectiveness of the treatment system.

Topics: Camphanes; Naphthols; Odorants; Taste; Water Purification; Water Supply

Tastes and odors problems (T&Os) in China and studies on T&Os are reviewed, especially on aspects of the present situation in China, sources of T&Os in water, T&Os qualitative & quantitative technology, odorant composing characters, removal technologies and processes on typical odorant in drinking water. This review aims to elucidate that besides microbial metabolism product such as geosmin and 2-MIB, organic anaerobic decomposition product such as thiol-thioether were also main odorant in drinking water of China. Thiol-thioether odorant which was found in drinking water of Dongguan in 2006 for the first time, was proved to be the main odorant in Taihu Lake drinking water risk in 2007 as well. Geosmin and 2-MIB were more easily removed by adsorption than oxidation, but thiol-thioether was easily removed by oxidation not by adsorption. In order to cope with T&Os in different water source, different season and different odorant,studies on odorant composing character, removal technology, mechanism and process of typical odorant should be carried out as soon as possible in China.

Topics: Camphanes; China; Naphthols; Odorants; Sulfhydryl Compounds; Taste; Water Pollutants, Chemical; Water Purification; Water Supply

Microbially derived off-flavors can adversely affect the beverage, food, water, and aquaculture industries. Off-flavor can temporarily be controlled by adopting best management practices such as proper aeration, liming, and dredging, and, more importantly, by avoidance of excessive nutrient use. Research studies focus on the effective means of control with the major emphasis on controlling the odor-causing algae populations and developing effective and selective algicides, which are not always available for use at the right time and can also have adverse impacts on the environment. Furthermore, selective application of synthetic algicides is not always recommended for reasons of inconsistency in the results and concerns regarding the frequent use of these chemicals, such as toxicity, accumulation of free copper, dissolved oxygen voids, increase in toxic ammonia and hydrogen sulfide, pH fluctuation, reduced photosynthetic activity, and reestablishment of algae in nutrient-rich water, thus requiring multiple treatments. Conversely, the plant-derived products appear to be environmentally safe and economical in view of their abundant availability and easy operational process. However, there needs to be more extensive work in this field. Precursors of sesquiterpene synthesis may selectively help to suppress off-flavor-producing species. Bioremedial measures by means of microbial degradation and gene bioaugmentation may be promising and are the subjects of much future research for effective controls.

Topics: Biodegradation, Environmental; Camphanes; Naphthols; Odorants; Water; Water Microbiology; Water Purification

Topics: Bacteria; Camphanes; Fresh Water; Naphthols; Odorants; Water Purification

Actinomycetes are a complex group of bacteria present in a wide variety of environments, either as dormant spores or actively growing. Some actinomycetes produce two potent terpenoids (geosmin and 2-methylisoborneol (MIB)) and pyrazines, common causes of drinking water off flavours, and have been implicated in taste and odour episodes. However, isolation from a water source is not evidence that actinomycetes caused a taste and odour event. Dormant spores of actinomycetes may be isolated from aquatic environments in high concentrations, despite production in the terrestrial environment. Similarly, odourous compounds produced by actinomycetes may be produced terrestrially and washed into aquatic environments, with or without the actinomycetes that produced them. Actinomycetes may exist as actively growing mycelium in small, specialized habitats within an aquatic system, but their odourous compounds may influence a wider area. This paper attempts to elucidate the types and activities of actinomycetes that may be found in, or interact with, drinking water supplies.

Topics: Actinobacteria; Camphanes; Colony Count, Microbial; Fresh Water; Naphthols; Odorants; Taste; Water Supply

A guide to confirmed geosmin- and MIB-producing cyanobacteria isolated in the United States is being prepared. This document will include 41 different species or morphologically distinct types from eight states and diverse aquatic sources isolated over a 22-year period. The organisms comprised by this guide demonstrate the importance of attached cyanobacteria as off-flavor agents, the strain specificity of MIB production, the existence of unicellular MIB producers, the occurrence of multiple geosmin and MIB producers in reservoirs, and the relationship of certain planktonic odor producers to species in other countries.

Topics: Camphanes; Classification; Cyanobacteria; Naphthols; Odorants; Plankton; Taste; Water Microbiology; Water Supply

Topics: Actinomycetales; Camphanes; Chemical Phenomena; Chemistry; Fresh Water; Naphthols; Nocardia; Odorants; Pyrazines; Pyrones; Species Specificity; Streptomyces; Water Microbiology; Water Pollution

Geosmin and 2-methylisoborneol (2-MIB) are amongst the most common earthy and musty taste and odour (T&O) compounds found in drinking water. With low odour threshold detection limits below 10 ng L

Topics: Drinking Water; Gas Chromatography-Mass Spectrometry; Solid Phase Extraction

Cyanobacterial blooms accompanied by taste and odor (T&O) compounds affect the recreational function and safe use of drinking water. Geosmin and 2-methylisoborneol (2-MIB) are the most common T&O compounds. In this study, we investigated the effect of temperature on geosmin and 2-MIB production in Dolichospermum smithii and Pseudanabaena foetida var. intermedia. More specifically, transcription of one geosmin synthase gene (geoA) and two 2-MIB synthase genes (mtf and mtc) was explored. Of the three temperatures (15, 25, and 35 °C) tested, the maximum Chl-a content was determined at 25 °C in both D. smithii and P. foetida var. intermedia. The maximum total geosmin concentration (19.82 μg/L) produced by D. smithii was detected at 25 °C. The total 2-MIB concentration (82.5 μg/L) produced by P. foetida var. intermedia was the highest at 35 °C. Besides, the lowest Chl-a content and minimum geosmin/2-MIB concentration were observed at 15 °C. There was a good positive correlation between geosmin/2-MIB concentration and Chl-a content. The expression levels of the geoA, mtf, and mtc genes at 15 °C were significantly higher than those at 25 and 35 °C. The transcription of the mtf and mtc genes in P. foetida var. intermedia was higher at 35 °C than at 25 °C. The results highlight unfavorable temperature can increase the potential of geosmin/2-MIB synthesis from the gene expression level in cyanobacteria. This study could provide basic knowledge of geosmin/2-MIB production by cyanobacteria for better understanding and management of T&O problems in drinking water.

Topics: Camphanes; Cyanobacteria; Gene Expression; Naphthols; Odorants; Temperature

The taste and odor (T&O) problem represented by 2-methylisoborneol (2-MIB) and geosmin (GSM) in water is the multiple undesirable substances in the drinking water and the aquatic industry. In this study, the UV-assisted photoelectrochemical, a prospective advanced oxidation process (AOP), was evaluated for the degradation of 2-MIB and GSM. In contrast to UV photochemical and electrochemical, the degradation ratio of GSM (2-MIB) increase to 96% (95%) in 25 min. The removal ratio and rate depended on reaction time, electrolyte concentration, current density, and water quality parameters (e.g. pH, HCO

Topics: Camphanes; Naphthols; Odorants; Prospective Studies; Water Pollutants, Chemical; Water Purification

This study investigated the relative contributions of adsorption vs. biodegradation towards 2-methylisoborneol (MIB) and geosmin removal in the granular activated carbon (GAC) harvested from six filter-adsorbers in three drinking water treatment plants in the Great Lakes region. Column tests using azide-treated (sterilized) and untreated GAC in parallel were used to isolate the two effects. It was identified that substantial MIB and geosmin biodegradation in the GAC was occurring in one location, and that GAC in some cases had significant adsorption capacity after as much as 9 years of operation. Four alternative biological parameters (adenosine triphosphate, esterase activity, phosphatase activity, and

Topics: Adsorption; Camphanes; Charcoal; Naphthols; Water Pollutants, Chemical; Water Purification

Traditional methodologies of conventional drinking water treatment are unable to remove some chemical compounds, such as those that cause odor and taste in drinking water. The present work aims to evaluate the efficiency of advanced oxidations processes, using UV radiation, O

Topics: Camphanes; Fresh Water; Gas Chromatography-Mass Spectrometry; Naphthols; Odorants; Water Pollutants, Chemical; Water Purification

Taste and odor episodes caused by off-flavor secondary metabolites, such as 2-methylisoborneol (MIB) and geosmin, pose one of the greatest challenges for drinking water utilities around the world. The prevalence of these compounds is predicted to increase in the future as a function of nutrient enrichment and elevated temperatures of surface drinking water sources. We conducted a manipulative field experiment in a drinking water reservoir to elucidate patterns for two taste and odor compounds, MIB and geosmin, as well as two taxa known to produce these compounds, phytoplankton (more specifically, cyanobacteria) and actinobacteria, across different depths in response to nutrient enrichment with two common dissolved nitrogen forms, organic urea or inorganic nitrate. In general, we found that MIB levels increased by greater than 250% with nutrient enrichment mediated by increased phytoplankton biomass. However, the effect of the fertilization treatments on MIB decreased with depth with a 35% reduction at 7 m versus 1.5 m. In contrast, geosmin levels reached a maximum at the lowest measured depth (7 m), were unaffected by the fertilization treatments, and followed a similar pattern to the abundance of actinobacteria. Thus, our data suggest that the positive response of phytoplankton (e.g., cyanobacteria, such as Oscillatoria species) to the fertilization treatments is likely responsible for increased MIB, while geosmin concentrations may be a function of actinobacteria-mediated decomposition in the hypolimnion in our study system.

Topics: Actinobacteria; Camphanes; Cyanobacteria; Drinking Water; Naphthols; Odorants

A method is described here for the concentration and determination of geosmin and 2-methylisoborneol (2-MIB) from the gaseous phase, with translation to field collection and quantification from soil disturbances in situ. The method is based on the use of solid-phase microextraction (SPME) fibers for adsorption of volatile chemicals from the vapor phase, followed by desorption into a gas chromatograph-mass spectrometer (GC-MS) for analysis. The use of a SPME fiber allows simple introduction to the GC-MS without further sample preparation. Several fiber sorbent types were studied and the 50/30 μm DVB/CAR/PDMS was the best performer to maximize the detected peak areas of both analytes combined. Factors such as extraction temperature and time along with desorption temperature and time were explored with respect to analyte recovery. An extraction temperature of 30 °C for 10 min, with a desorption temperature of 230 °C for 4 min was best for the simultaneous analysis of both geosmin and 2-MIB without complete loss of either one. The developed method was used successfully to measure geosmin and 2-MIB emission from just above disturbed and undisturbed soils, indicating that this method detects both compounds readily from atmospheric samples. Both geosmin and 2-MIB were present as background concentrations in the open air, while disturbed soils emitted much higher concentrations of both compounds. Surprisingly, 2-MIB was always detected at higher concentrations than geosmin, indicating that a focus on its detection may be more useful for soil emission monitoring and more sensitive to low levels of soil disturbance.

Topics: Camphanes; Gas Chromatography-Mass Spectrometry; Naphthols; Soil; Solid Phase Microextraction

As taste-and-odor outbreaks are common in surface waters worldwide, extensive studies have focused on the identification of microorganisms involved in the production of 2-methylisoborneol (MIB) and geosmin (GSM). However, fewer studies have tried to identify potential degraders in natural environments. Eagle Creek Reservoir, a temperate and eutrophic water body, experienced two major seasonal odorous outbreaks in 2013 with maximal concentrations of 99.1 (MIB) and 77.3 ng L

Topics: Camphanes; Flavobacterium; Naphthols; Odorants; Sphingomonadaceae; Sphingomonas; Water Pollutants, Chemical

The off-flavor compounds geosmin and 2-methylisoborneol (2-MIB) are well-known to impact the quality of farmed freshwater fish species, but little is known about off-flavors in marine aquaculture. To begin addressing this knowledge gap, a method for determining geosmin and 2-MIB using LC with atmospheric pressure chemical ionization (APCI) MS detection was developed. While 2-MIB was readily detected using LC-APCI/MS, geosmin exhibited on-column degradation that was independent of column chemistry and could not be eliminated. Optimized conditions were identified that balanced the separation and ionization efficiency of 2-MIB and geosmin while minimizing geosmin degradation, but the overall method sensitivity for geosmin was reduced by the on-column losses. The method was used with direct aqueous injections to determine the volatilization rates of geosmin and 2-MIB at ppb levels during aeration under laboratory conditions in both salt water and pure water to simulate marine and fresh water aquaculture, respectively. The volatilization rates of both compounds were 30% faster in salt water than in fresh water with or without aeration, but aeration was found to enhance the rate by a factor of 2.5 in both water types. The LC-APCI/MS method was combined with stir bar sorptive extraction (SBSE) to achieve greater sensitivity for determining off-flavors in recirculating aquaculture system (RAS) water. Using SBSE-LC-APCI/MS, the LODs for geosmin and 2-MIB were 70 ng/kg (part per trillion) and 6 ng/kg, respectively. The on-column losses resulted in a relatively high LOD for geosmin that renders this method unsuitable for determining geosmin at the low ng/kg levels expected in RAS. SBSE using both grab water samples and an in-situ diving unit were used to evaluate 2-MIB levels in the culture water of two separate marine RAS that were supporting the growth of European sea bass but had differing levels of water treatment. 2-MIB was readily detected using both SBSE approaches in the RAS with less sophisticated treatment when the animal stocking density was at its highest (50 kg/m

Topics: Animals; Aquaculture; Atmospheric Pressure; Camphanes; Chromatography, Liquid; Flavoring Agents; Fresh Water; Limit of Detection; Mass Spectrometry; Naphthols; Time Factors; Volatilization; Water; Water Pollutants, Chemical; Water Purification

The secondary metabolites geosmin and 2-methylisoborneol (MIB) are known to taint fish with an undesirable, earthy-muddy taste and odor. In an earlier study on a zero-discharge recirculating aquaculture system (RAS), it was found that geosmin and MIB were removed by microbial communities residing in sludge from the digestion basin of the system. In the present study, 16S amplicon sequencing was used to identify changes in relative abundances of bacterial taxa in geosmin and MIB-enriched crude sludge. The removal of geosmin and MIB by the sludge was accompanied by increased abundances of 12 operational taxonomic units (OTUs). The most prominent increase in abundances was recorded for OTUs affiliated with bacterial genera known to harbor denitrifiers. Among these were the Betaproteobacteria genera Thauera, which utilizes terpenes to fuel denitrification, and Comamonas, which was previously isolated from the digestion basin of the same system and is capable of growth on geosmin and MIB as sole carbon and energy sources. Thus far, denitrification has been associated with bacteria capable of utilizing terpenes other than geosmin and MIB. The significant increase in the abundance of denitrifying bacterial genera in sludge in which geosmin and MIB comprised only 0.06% of the total carbon content might indicate that such bacteria play a major role in the removal of these compounds in anoxic environments.

Topics: Aquaculture; Bacteria; Camphanes; Denitrification; Microbiota; Naphthols; Sewage; Water Purification

Volatile compounds emitted by bacteria are often sensed by other organisms as odours, but their ecological roles are poorly understood

Topics: Animals; Arthropods; Camphanes; Naphthols; Pheromones; Soil; Spores, Bacterial; Streptomyces

Topics: Animals; Arthropods; Camphanes; Naphthols; Soil; Spores, Bacterial; Streptomyces

Topics: Animals; Arthropods; Camphanes; Naphthols; Odorants; Soil; Spores, Bacterial; Streptomyces

Granular activated carbon (GAC) is widely used by drinking water treatment plants in the Great Lakes region to control 2-methylisoborneol (MIB) and geosmin associated with summertime algal blooms. Recently, however, taste and odour events are being detected in the winter, but there is limited information in the literature about the effect of temperature on GAC performance. In this study, batch isotherm experiments were conducted at 4 °C, 10 °C, and 20 °C to evaluate the temperature impact on adsorption thermodynamics. Pilot-scale column tests were then performed at the same temperatures to evaluate the temperature effect on overall removal, including both thermodynamics and kinetics. The pore and surface diffusion model (PSDM) was applied to fit the experimental data of the pilot-scale column tests, which allowed the kinetic parameters to be determined at each temperature. The isotherm results showed that water temperature did not have a significant effect on the equilibrium adsorption capacity (i.e., the thermodynamics) for MIB and geosmin under the conditions tested, but the pilot tests showed an increased removal of MIB and geosmin by 20-30% at 20 °C compared to the lower temperatures. This demonstrates that water temperature has more impact on kinetics than thermodynamics. Numerical simulations showed that the overall external mass transfer coefficient, K

Topics: Adsorption; Camphanes; Charcoal; Great Lakes Region; Naphthols; Temperature; Water; Water Pollutants, Chemical; Water Purification

Organic matter-induced black bloom frequently occurs in a number of large eutrophic shallow lakes; this can result in the release of malodorous compounds and has a negative impact on water quality. In the study, a microcosm system containing Zizania latifolia (Z. latifolia), a common aquatic plant, was established and the release of seven taste and odour compounds, dimethyl sulphide (DMS), dimethyl disulphide (DMDS), dimethyl trisulphide (DMTS), 2-methylisoborneol (MIB), geosmin (GSM), β-cyclocitral, and β-ionone, was investigated. The results showed that these compounds were all detected during Z. latifolia decay, and that volatile organic sulphur compounds (VOSCs), such as DMS, DMDS, and DMTS, were the main factors responsible for the strong foul odour (the maximum reached 5.0 μg L

Topics: Aldehydes; Biodegradation, Environmental; Camphanes; Diterpenes; Ecosystem; Lakes; Naphthols; Norisoprenoids; Odorants; Poaceae; Sulfides; Taste; Volatile Organic Compounds; Water Quality

Complaints caused by odors from the fermentation production of pharmaceuticals are common in China. The elimination of odor remains a challenge for the pharmaceutical industry to meet the increasingly strict environment regulations. Erythromycin is a representative antibiotic produced by microbial fermentation. The fermentation exhaust gas of erythromycin fermentation has an unpleasant odor, but the composition of the key odorants has not been identified. The major odorants from the fermentation production of erythromycin API were analyzed by electronic nose, olfactory measurements, gas chromatography-coupled ion mobility spectrometry (GC-IMS) and gas chromatography-mass spectrometry (GC-MS) analysis. Two compounds, 2-methylisoborneol (2-MIB) and geosmin, were identified as the major odorants of erythromycin fermentation. These had not been detected before using only GC-MS analysis of exhaust gas. Aldehydes, including hexanal, octanal, decanal, and benzaldehyde, also contribute to the odor. The composition analysis of odorants using the fermentation broth headspace was more efficient and reliable, considering the significant dilution effect of exhaust gas. The concentration of 2-MIB and geosmin in the fermentation broth greatly exceeded their odor thresholds. The production of major odorants started in the early fermentation stage and became significant in the middle stage (30-70 h). Due to the extremely low odor thresholds of 2-MIB and geosmin, advanced purification may require deodorization of erythromycin fermentation exhaust gas.

Topics: Aldehydes; Camphanes; China; Erythromycin; Fermentation; Gas Chromatography-Mass Spectrometry; Ion Mobility Spectrometry; Naphthols; Odorants; Volatile Organic Compounds

The odor problem caused by the decay of aquatic plants is widespread in many freshwater lakes. In this study, the spatial distributions of seven taste and odor (T&O) compounds (dimethyl sulfide, dimethyl disulfide, dimethyl trisulfide, 2-methylisoborneol, geosmin, β-cyclocitral, and β-ionone) in the sediments and overlying water of the east of Taihu Lake were investigated. The effects of plant and physico-chemical parameters on the release of T&O compounds were also analyzed. The results showed that high concentrations of T&O compounds were detected in the area where Eichhornia crassipes was flourishing. Volatile organic sulfur compounds were not found in the water source area, which was not covered by aquatic plants. High plant biomass and aquiculture activities might increase the release of the taste and odor compounds. The correlation between the concentrations of odorous compounds and nutrients in the sediment was also analyzed. The production of odorants was positively correlated with the nitrogen, and they may migrate from sediment to overlying water. The result suggested that controlling the plant density and aquaculture activities could reduce the release of odorous compounds.

Topics: Aldehydes; Aquatic Organisms; Camphanes; China; Diterpenes; Geologic Sediments; Lakes; Naphthols; Norisoprenoids; Odorants; Plants; Sulfides; Taste; Volatile Organic Compounds; Water Pollutants, Chemical

Adsorption was found to be an acceptable treatment option to remove geosmin (GSM) and 2-methylisoborneol (2-MIB). It is meaningful to investigate the adsorption capacity of granular activated carbon (GAC) for the two algal odorants in water, and the influences of natural organic material (NOM) and particle size. The adsorption process was studied with the four isotherm models (Langmuir, Freundlich, Temkin, and modified Freundlich), four kinetic models (pseudo first-order, pseudo second-order, Elovich, and intra-particle), and thermodynamics. The results showed that the adsorption of both compounds could be best described by the modified Freundlich isotherm and pseudo second-order model, and the obtained thermodynamic parameters (changes in heat of adsorption, entropy, and Gibbs free energy) revealed that the adsorption was endothermic and spontaneous. Downsizing the particle size of GAC was effective for improving the adsorption capacity and rate. The concentrations of the two odorants could be reduced from 500 ng L

Topics: Adsorption; Camphanes; Charcoal; Kinetics; Naphthols; Thermodynamics; Water; Water Pollutants, Chemical

Lake Taihu has been experiencing taste and odor (T&O) events recently. And for the purpose of seeking the environmental factors having great influences on T&O compounds and supplying theory information for preventing the occurrence of T&O problems, Redundance analysis (RDA) was conducted for the dissolved and particle-bound forms of T&O compounds. And the whole lake was divided into the blooming and non-blooming areas. Results indicated that environmental factors, including biotic and abiotic factors, made great contributions to the variation of T&O compounds in Lake Taihu. The key biotic factors included Microcystis, Oscillatoria and chlorophyll-a. Microcystis made great contribution of these compounds in the blooming area and had close relationship with those particulate forms of odorants in Taihu. Oscillatoria made great and absolute contribution to odorants in the non-blooming area. Chlorophyll-a influenced greatly the odorants in the blooming area and had significant relationship with the particle-bound fractions in the whole lake. Dissolved oxygen and water temperature were the dominant abiotic factors with large contributions.

Topics: Air Pollutants; Camphanes; China; Chlorophyll; Environmental Monitoring; Eutrophication; Lakes; Microcystis; Naphthols; Odorants; Oscillatoria; Oxygen; Taste; Temperature; Water Pollutants, Chemical

Topics: Camphanes; China; Cities; Drinking Water; Naphthols; Odorants; Propane; Rivers; Sulfides; Water Pollutants, Chemical; Water Purification

A visual, rapid, and sensitive method for the detection of two algal metabolites, geosmin (GSM) and 2-methylisoborneol (2-MIB) using a competitive displacement technique based on molecular imprinted polymers (MIPs) and fluorescent tags was developed. In this method, fluorescent tags that bind to synthetic receptor sites of MIPs were designed and synthesised. In the presence of target analytes (geosmin and 2-methylisoborneol respectively), the tags are displaced leading to fluorescence signals. The MIPs were derived from the polymerisation of functional monomers and crosslinkers in the presence of suitable templates. Good to high binding capacities and selectivities were obtained with the MIPs. The displacement of fluorescent-tagged substrates from the respective MIPs by the target analytes enabled the quantitative detection of geosmin at concentrations as low as 0.38 μM (69 μg L

Topics: Camphanes; Chlorophyta; Fluorescence; Kinetics; Molecular Imprinting; Molecular Structure; Naphthols; Particle Size; Polymers; Surface Properties

We investigated the adsorption characteristics of geosmin and 2-methylisoborneol (MIB) on graphene oxide (GO) in the absence and presence of natural organic matter (NOM). The graphene oxide had fast adsorption kinetics for both compounds because of its open-layered structure, with adsorption equilibrium being achieved within 15 min of contact. Although NOM did not affect the adsorption of geosmin on GO, it delayed that of MIB, probably because of competition for adsorption sites. The adsorption isotherms show that GO had a greater capacity for geosmin adsorption than for MIB because geosmin was more hydrophobic. Moreover, NOM interfered with the adsorption of MIB onto the GO, but increased the amount of adsorbed geosmin, which likely occurred because NOM increased the dispersibility of GO, which then increased the number of GO adsorption sites. The difference in the effects of NOM on GO adsorption of geosmin and MIB may be explained by their hydrophobicity. Although the adsorption of geosmin and MIB by GO was fast, its capacity to adsorb both compounds was substantially lower than that of activated carbon because of its higher hydrophilicity.

Topics: Adsorption; Camphanes; Charcoal; Graphite; Kinetics; Naphthols; Oxides; Water Pollutants, Chemical; Water Purification

While cyanobacteria have been widely recognised as the most common cause of geosmin and 2-methylisoborneol related taste and odour (T&O) episodes in drinking water supplies, many reported occurrences could not be attributed to these organisms. The Streptomyces genus of soil bacteria also includes producers of these compounds, however their potential role in such occurrences is poorly understood and often disregarded on the basis that they are terrestrial rather than aquatic organisms, with their detection in water samples assumed to reflect the presence of dormant spores rather than metabolically active vegetative cells. Using qPCR and a differential cell lysis technique for DNA extraction, allowing distinction of spores from vegetative cells, the aim of this study was to determine the distribution, abundance and potential activity of Streptomyces species across a range of aquatic and marginal habitat zones in two drinking water reservoirs, including: exposed soil, submerged sediments, plant debris and emergent macrophytes at the margins; marginal and offshore surface waters; deep offshore waters; and offshore benthic sediments. Marginal substrates including soil, sediment and plant debris were identified as the dominant habitat zones for Streptomyces, (concentrations up to 1.1 × 10

Topics: Camphanes; Drinking Water; Naphthols; Odorants; Streptomyces

Taste and odor (T&O) compounds are widespread in water environments and have attracted considerable public attention. Nowadays, the standard detections of these chemicals rely mainly on off-line methods such as GC-MS or evaluation by trained analysts' senses. In this study, we report a method for the rapid detection of T&O compounds in water by exploiting a newly invented chemi-ionization source, in combination with headspace vapor measurement at room temperature. The calibrated limits of detection (LODs) of 2-methylbutyraldehyde, methyl tert-butyl ether (MTBE), methyl methacrylate (MMA), 2-isobutyl-3-methyoxypyrazine (IBMP), and 2-isopropyl-3-methoxypyrazine (IPMP) are in the range of 3.5-50.2 ng L

Topics: Aldehydes; Camphanes; China; Diterpenes; Limit of Detection; Mass Spectrometry; Naphthols; Odorants; Pyrazines; Reproducibility of Results; Rivers; Taste; Water Pollutants, Chemical

In this study, the application of enhanced coagulation with persulfate/Fe(II), permanganate and ozone for Microcystis-laden water treatment was investigated. Two oxidant dosage strategies were compared in terms of the organic removal performance: a simultaneous dosing strategy (SiDS) and a successive dosing strategy (SuDS). To optimize the oxidant species, oxidant doses and oxidant dosage strategy, the zeta potential, floc size and dimension fraction, potassium release and organic removal efficiency during the coagulation of algae-laden water were systematically investigated and comprehensively discussed. Ozonation causes most severe cell lysis and reduces organic removal efficiency because it releases intracellular organics. Moreover, ozonation can cause the release of odor compounds such as 2-methylisoborneol (2-MIB) and geosmin (GSM). With increasing doses, the performance of pollutant removal by coagulation enhanced by persulfate/Fe(II) or permanganate did not noticeably improve, which suggests that a low dosage of persulfate/Fe(II) and permanganate is the optimal strategy to enhance coagulation of Microcystis-laden water. The SiDS performs better than the SuDS because more Microcystis cell lysis occurs and less DOC is removed when oxidants are added before the coagulants.

Topics: Camphanes; Ferrous Compounds; Manganese Compounds; Microcystis; Naphthols; Oxidants; Oxidation-Reduction; Oxides; Ozone; Water Microbiology; Water Purification

Geosmin and 2-methylisoborneol (MIB) outbreaks in tropical water bodies, such as Southeast Asia, by actinomycetes have not yet been elucidated in detail. Six Streptomyces isolates from lowland environments in Malaysia were selected and evaluated for their odor production under different temperatures. The gene responsible for the production of geosmin, geoA, was detected in all isolates, while only two isolates harbored tpc, which is responsible for 2-MIB production. This result suggested that geosmin and 2-MIB synthesis pathway genes already existed in the environment in the Tropics of Southeast Asia. Furthermore, our isolates produced musty odor compounds at 30°C, and differences were observed in musty odor production between various temperatures. This result indicated the potential for odor episodes in water bodies of the tropical countries of Southeast Asia throughout the year due to the mean annual ambient temperature of 27°C in the lowlands.

Topics: Camphanes; Malaysia; Naphthols; Odorants; Streptomyces; Temperature

In this study, the degradation of 2-methylisoborneol (2-MIB) and geosmin (GSM) was evaluated by electrochemical oxidation (EO) using boron-doped diamond (BDD) electrode. Both 2-MIB and GSM could be degraded efficiently in sulfate electrolyte compared to inert nitrate or perchlorate electrolytes, implying that in-situ generated persulfate may be responsible for contaminants degradation. The observed linear relationship between 2-MIB (GSM) degradation rates and persulfate generation rates further proved that the in-situ generated persulfate enhanced 2-MIB (GSM) degradation. Moreover, a divided electrolytic cell was employed to investigate the effect of cathodic reactions on contaminants degradation and persulfate generation, and results confirmed that both anodic and cathodic reactions participated in 2-MIB (GSM) degradation. High current density and low solution pH were found to be favorable for 2-MIB and GSM degradation. The degradation intermediates were identified and the possible pathways of 2-MIB and GSM degradation were proposed. This study indicated that the EO process with BDD anode could be considered as a potential alternative for the removal of 2-MIB and GSM.

Topics: Boron; Camphanes; Diamond; Electrochemical Techniques; Electrodes; Naphthols; Nitrates; Oxidation-Reduction; Sulfates; Water Pollutants, Chemical; Water Purification

Visible light (VIS) photocatalysis has large potential as a sustainable water treatment process, however the reaction pathways and degradation processes of organic pollutants are not yet clearly defined. The presence of cyanobacteria cause water quality problems since several genera can produce potent cyanotoxins, harmful to human health. In addition, cyanobacteria produce taste and odor compounds, which pose serious aesthetic problems in drinking water. Although photocatalytic degradation of cyanotoxins and taste and odor compounds have been reported under UV-A light in the presence of TiO2, limited studies have been reported on their degradation pathways by VIS photocatalysis of these problematic compounds. The main objectives of this work were to study the VIS photocatalytic degradation process, define the reactive oxygen species (ROS) involved and elucidate the reaction mechanisms. We report carbon doped TiO2 (C-TiO2) under VIS leads to the slow degradation of cyanotoxins, microcystin-LR (MC-LR) and cylindrospermopsin (CYN), while taste and odor compounds, geosmin and 2-methylisoborneol, were not appreciably degraded. Further studies were carried-out employing several specific radical scavengers (potassium bromide, isopropyl alcohol, sodium azide, superoxide dismutase and catalase) and probes (coumarin) to assess the role of different ROS (hydroxyl radical OH, singlet oxygen (1)O2, superoxide radical anion [Formula: see text] ) in the degradation processes. Reaction pathways of MC-LR and CYN were defined through identification and monitoring of intermediates using liquid chromatography tandem mass spectrometry (LC-MS/MS) for VIS in comparison with UV-A photocatalytic treatment. The effects of scavengers and probes on the degradation process under VIS, as well as the differences in product distributions under VIS and UV-A, suggested that the main species in VIS photocatalysis is [Formula: see text] , with OH and (1)O2 playing minor roles in the degradation.

Topics: Alkaloids; Bacterial Toxins; Camphanes; Catalysis; Cyanobacteria; Cyanobacteria Toxins; Free Radical Scavengers; Light; Marine Toxins; Microcystins; Naphthols; Odorants; Photolysis; Reactive Oxygen Species; Taste; Titanium; Ultraviolet Rays; Uracil; Water Pollutants, Chemical; Water Purification

Geosmin and 2-methylisoborneol (2-MIB) are two of the most common taint compounds that adversely affect the quality of aquacultural animals. In the present study, 94% of geosmin and 97% of 2-MIB in suspended growth reactors producing bioflocs (SGRs) with aquaculture waste were removed after inoculation with Bacillus subtilis, significantly higher than that of control SGRs (70% of geosmin and 86.4% of 2-MIB). The lowest concentrations of geosmin and 2-MIB achieved in the effluent of the SGRs were 2.43 ± 0.42 ng/l and 2.23 ± 0.15 ng/l, respectively. The crude protein content of the bioflocs produced in the SGRs was 35 ± 4%. The NH4(+)-N and NO2(-)-N concentrations in the effluent of the reactors were 1.13 ± 0.21 mg/l and 0.42 ± 0.04 mg/l, respectively. These results suggest that inoculated with Bacillus subtilis, SGRs have a better performance to reuse the nitrogen in fish waste and to remove geosmin and 2-MIB from the culture water efficiently.

Topics: Animals; Aquaculture; Bacillus subtilis; Biodegradation, Environmental; Camphanes; Fishes; Naphthols; Nitrogen; Waste Disposal, Fluid; Water; Water Purification

We conducted chlorination, UV photolysis, and UV/chlorin reactions to investigate the intermediate formation and degradation mechanisms of geosmin and 2-methylisoborneol (2-MIB) in water. Chlorination hardly removed geosmin and 2-MIB, while the UV/chlorine reaction at 254 nm completely removed geosmin and 2-MIB within 40 min and 1 h, respectively, with lesser removals of both compounds during UV photolysis. The kinetics during both UV photolysis and UV/chlorine reactions followed a pseudo first-order reaction. Chloroform was found as a chlorinated intermediate during the UV/chlorine reaction of both geosmin and 2-MIB. The pH affected both the degradation and chloroform production during the UV/chlorine reaction. The open ring and dehydration intermediates identified during UV/chlorine reactions were 1,4-dimethyl-adamantane, and 1,3-dimethyl-adamantane from geosmin, 2-methylenebornane, and 2-methyl-2-bornene from 2-MIB, respectively. Additionally, 2-methyl-3-pentanol, 2,4-dimethyl-1-heptene, 4-methyl-2-heptanone, and 1,1-dichloro-2,4-dimethyl-1-heptane were newly identified intermediates from UV/chlorine reactions of both geosmin and 2-MIB. These intermediates were degraded as the reaction progressed. We proposed possible degradation pathways during the UV photolysis and UV/chlorine reactions of both compounds using the identified intermediates.

Topics: Bridged Bicyclo Compounds; Camphanes; Chlorine; Chloroform; Halogenation; Ketones; Kinetics; Naphthols; Photolysis; Ultraviolet Rays; Water Pollutants, Chemical; Water Purification

Geosmin and 2-methylisoborneol (MIB) are muddy/earthy off-flavor metabolites produced by a range of bacteria. Cyanobacteria are the major producers of the volatile metabolites geosmin and MIB which produce taste and odor problems in drinking water and fish worldwide. Here we detected geosmin and MIB by studying 100 cyanobacteria strains using solid phase microextraction gas chromatography mass spectrometry (SPME GC-MS). A total of 21 geosmin producers were identified from six cyanobacteria genera. Two of the geosmin producers also produced MIB. A PCR protocol for the detection of geoA and MIB synthase genes involved in the biosynthesis of geosmin and MIB was developed. The geoA and MIB synthase genes were detected in all strains shown to produce geosmin and MIB, respectively. Cyanobacterial geoA and MIB synthase sequences showed homology to terpene synthases genes of actinobacteria and proteobacteria. Additional off-flavor compounds, nor-carotenoids β-ionone and β-cyclocitral, were found from 55 strains among the 100 cyanobacterial strains studied; β-ionone was present in 45 and β-cyclocitral in 10 strains. Six of the cyanobacteria which contain off-flavor compounds also produced toxins, anatoxin-a or microcystins. The molecular method developed is a useful tool in monitoring potential cyanobacterial producers of geosmin and MIB.

Topics: Camphanes; Cyanobacteria; Environmental Monitoring; Gas Chromatography-Mass Spectrometry; Genes, Bacterial; Molecular Sequence Data; Naphthols; Phylogeny; Polymerase Chain Reaction; Sequence Analysis, DNA; Solid Phase Microextraction; Water Pollutants, Chemical

2-methylisoborneol (2-MIB) and geosmin are two odor-causing compounds that are difficult to remove and the cause of many consumer complaints. In this study, we assessed the degradation of 2-MIB and geosmin using a UV/persulfate process for the first time. The results showed that both 2-MIB and geosmin could be degraded effectively using this process. The process was modeled based on steady-state assumption with respect to the odor-causing compounds and either hydroxyl or sulfate radicals. The second order rate constants for 2-MIB and geosmin reacting with the sulfate radical (SO4(-)) were estimated to be (4.2 ± 0.6) × 10(8) M(-1)s(-1) and (7.6 ± 0.6) × 10(8) M(-1)s(-1) respectively at a pH of 7.0. The contributions of the hydroxyl radical (OH) to 2-MIB and geosmin degradation were 3.5 times and 2.0 times higher, respectively, than the contribution from SO4(-) in Milli-Q water with 2 mM phosphate buffer at pH 7.0. The pseudo-first-order rate constants (ko(s)) of both 2-MIB and geosmin increased with increasing dosages of persulfate. Although pH did not affect the degradation of 2-MIB and geosmin directly, different scavenging effects of hydrogen phosphate and dihydrogen phosphate resulted in higher values of ko(s) for both 2-MIB and geosmin in acidic condition. Bicarbonate and natural organic matter (NOM) inhibited the degradation of both 2-MIB and geosmin dramatically through consuming OH and SO4(-) and were likely to be the main radical scavengers in natural waters when using UV/persulfate process to control 2-MIB and geosmin.

Topics: Alkalies; Camphanes; Hydrogen-Ion Concentration; Hydroxyl Radical; Kinetics; Methanol; Naphthols; Potassium Compounds; Sulfates; Ultraviolet Rays; Water Pollutants, Chemical

A mixture of defense compounds (benzaldehyde, benzoyl cyanide, benzoic acid, mandelonitrile, and mandelonitrile benzoate), found commonly in cyanogenic polydesmid millipedes, was identified in the non-cyanogenic millipede Niponia nodulosa. These compounds were major components in 1st-4th instars, but were absent in older instars and adults. Extracts of older instars and adults contained 1-octen-3-ol, 2-methyl-2-bornene, E-2-octen-1-ol, 2-methyl-isoborneol, and geosmin; these compounds were minor components in 1st-4th instars. This ontogenetic allomone shift may be explained by the high cost of biosynthesis of polydesmid compounds from L-phenylalanine being offset by their potency in protecting the insect during fragile and sensitive growth stages. However, as the cuticle hardens in older juveniles (5th, 6th, 7th instars) and adults, this allows for a switch in defense to using less effective and less costly volatile organic compounds (presumably microbial in origin) that are ubiquitous in the millipede's habitat or are produced by symbiotic microbes and may be readily available through food intake or aspiration.

Topics: Acetonitriles; Age Factors; Animals; Arthropods; Camphanes; Molecular Structure; Naphthols; Octanols; Phenylalanine; Pheromones

Isolates of Nocardia cummidelens, Nocard ia fluminea, Streptomyces albidoflavus, and Streptomyces luridiscabiei attributed as the cause of "earthy-musty" off-flavor in rainbow trout (Oncorhynchus mykiss) raised in recirculating aquaculture systems (RAS) were evaluated for the effect of temperature (10-30 °C) on biomass, geosmin, and 2-methylisoborneol (MIB) production and cellular activity. Cultures of these isolates were monitored over 7 days by measuring culture dry weight, geosmin, and MIB production using solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS), and ATP production via a luminometer. Compared to the other isolates, S. luridiscabiei had significantly (P < 0.05) higher biomass (8.17 ± 0.35 mg/mL) at 15 °C (water temperature in the RAS) after 7 days incubation. In addition, S. luridiscabiei produced significantly (P < 0.05) higher geosmin (69,976 ± 15,733 ng/L) at 15 °C. At 25 °C and 30 °C, S. albidoflavus produced significantly (P < 0.05) higher geosmin (182,074 ± 60,272 ng/L and 399,991 ± 102,262 ng/L, respectively). All isolates produced MIB at 15 °C, but S. luridiscabiei produced significantly (P < 0.05) higher MIB (97,143 ± 28,972 ng/L) and ATP after 7 days. Therefore, S. luridiscabiei appears to be a likely contributor of geosmin and MIB in the RAS.

Topics: Adenosine Triphosphate; Animals; Aquaculture; Biomass; Camphanes; Flavoring Agents; Gas Chromatography-Mass Spectrometry; Naphthols; Nocardia; Oncorhynchus mykiss; Solid Phase Microextraction; Streptomyces; Taste; Temperature; Water

The earthy-musty compounds geosmin and 2-methylisoborneol (MIB) produced by cyanobacteria are considered as the main biological causes of off-flavor events, especially in aquatic ecosystems. More than 50 filamentous cyanobacteria species have been documented as geosmin or MIB producers; however, little is known about the species coproducing these two metabolites. In this study, an epiphytic sample was collected from a river in Hubei, China. Three isolated strains (A2, B2, and B4) producing earthy odors were successfully isolated and identified as the cyanobacterium Leptolyngbya bijugata Anagnostidis et Komárek 1988 based on morphology and 16S rDNA sequences. Gas chromatography analysis confirmed that the isolated L. bijugata strains were geosmin and MIB coproducers, with accumulation ranging from 13.6 to 22.4 and 12.3 to 57.5 μg L(-1), respectively. The partial fragments of geosmin and MIB synthesis genes in the L. bijugata strains were cloned and sequenced. Further sequences and phylogenetic analysis indicated the high conservation and a common origin of these genes in cyanobacteria. This study is the first to report and characterize the coproduction of geosmin and MIB by L. bijugata, representing a new source for potential risk of off-flavor events.

Topics: Camphanes; China; Chromatography, Gas; Cyanobacteria; Naphthols; Odorants; Phylogeny; Rivers

Advanced oxidation processes (AOPs) can be used to destroy taste and odour-causing compounds in drinking water. This work investigated both pilot- and full-scale performance of the novel ultraviolet (UV)/chlorine AOP for the destruction of geosmin, 2-methylisoborneol (MIB) and caffeine (as a surrogate) in two different surface waters. The efficiency of the UV/chlorine process at pH 7.5 and 8.5 was comparable to that of the UV/hydrogen peroxide (UV/H2O2) process under parallel conditions, and was superior at pH 6.5. Caffeine was found to be a suitable surrogate for geosmin and MIB, and could be used as a more economical alternative to geosmin or MIB spiking for site-specific full-scale testing.

Topics: Camphanes; Chlorine; Drinking Water; Hydrogen Peroxide; Naphthols; Odorants; Oxidation-Reduction; Pilot Projects; Taste; Ultraviolet Rays; Water Purification

The increasing frequency and intensity of taste and odour (T&O) producing cyanobacteria in water sources is a growing global issue. Geosmin and 2-methylisoborneol (MIB) are the main cyanobacterial T&O compounds and can cause complaints from consumers at levels as low as 10 ng/L. However, literature concerning the performance of full-scale treatment processes for geosmin and MIB removal is rare. Hence, the objectives of this study were to: 1) estimate the accumulation and breakthrough of geosmin and MIB inside full-scale water treatment plants; 2) verify the potential impact of sludge recycling practice on performance of plants; and, 3) assess the effectiveness of aged GAC for the removal of these compounds. Sampling after full-scale treatment processes and GAC pilot assays were conducted to achieve these goals. Geosmin and MIB monitoring in full-scale plants provided the opportunity to rank the performance of studied treatment processes with filtration and granular activated carbon providing the best barriers for removal of total and extracellular compounds, correspondingly. Geosmin was removed to a greater extent than MIB using GAC. Geosmin and MIB residuals in water post GAC contactors after two years of operation was 20% and 40% of initial concentrations, correspondingly. Biological activity on the GAC surface enhanced the removal of T&O compounds. These observations demonstrated that a multi-barrier treatment approach is required to ensure cyanobacteria and their T&O compounds are effectively removed from drinking water.

Topics: Adsorption; Biodegradation, Environmental; Camphanes; Charcoal; Cyanobacteria; Naphthols; Recycling; Sewage; Water Pollutants, Chemical; Water Purification

A bioelectronic nose for the real-time assessment of water quality was constructed with human olfactory receptor (hOR) and single-walled carbon nanotube field-effect transistor (swCNT-FET). Geosmin (GSM) and 2-methylisoborneol (MIB), mainly produced by bacteria, are representative odor compounds and also indicators of contamination in the water supply system. For the screening of hORs which respond to these compounds, we performed CRE-luciferase assays of the two odorants in heterologous cell system. Human OR51S1 for GSM and OR3A4 for MIB were selected, and nanovesicles expressing the hORs on surface were produced from HEK-293 cell. Carbon nanotube field-effect transistor was functionalized with the nanovesicles. The bioelectronic nose was able to selectively detect GSM and MIB at concentrations as low as a 10 ng L(-1). Furthermore, detection of these compounds from the real samples such as tap water, bottled water and river water was available without any pretreatment processes.

Topics: Biosensing Techniques; Camphanes; Electronic Nose; Equipment Design; HEK293 Cells; Humans; Immobilized Proteins; Nanotubes, Carbon; Naphthols; Odorants; Receptors, Odorant; Water Pollution; Water Quality

The earthy and musty odor problem in aquaculture systems has been a worldwide problem, especially in freshwater aquaculture systems. Geosmin (GSM) and 2-methylisoborneol (2-MIB), the most common causative agents of the off-flavor in fish, are lipophilic secondary metabolites of cyanobacteria, actinomycetes, and other microorganisms. The odor threshold concentrations for 2-MIB and GSM are approximately 9-42 ng x L(-1) and 4-10 ng x L(-1), and 600 ng x kg(-1) and 900 ng x kg(-1) in the aquaculture water and fish, respectively. With such a low odor threshold concentration, the off-flavor compounds greatly reduce the quality and economic value of aquatic products. This renders the fish, especially some valuable fish produced in recirculating aquaculture systems (RAS), unmarketable. The study reported the kinetic characteristics of degradation of GSM and 2-MIB by Bacillus subtilis and discussed the impacts of the initial concentration of GSM and 2-MIB (T1, T2) and inoculation amount (T1, T3 ) on the biodegradation rate. The result demonstrated that these two compounds could be degraded by B. subtilis effectively and the biodegradation rate reached more than 90% in T1, T2 and T3 treatments. The biodegradation of these two compounds behaved as a pseudo-first-order kinetics with rate constants (K) in the range of 0.14-0.41. K values indicated that the degradation rate was dependent on the inoculation amount but the start concentration of GSM and MIB. The degradation kinetics showed the maximum specific rate value (u(max)) and the Monod constant (K(s)) were 0.311 and 1.73, however, 2-MIB degradation process did not meet the Monod microbial growth equation (R2 = 0.781).

Topics: Actinobacteria; Animals; Aquaculture; Bacillus subtilis; Biodegradation, Environmental; Camphanes; Cyanobacteria; Fishes; Fresh Water; Naphthols; Odorants; Water

The adsorption capacities of nine activated carbons for geosmin and 2-methylisoborneol (MIB) were evaluated. For some carbons, adsorption capacity substantially increased when carbon particle diameter was decreased from a few tens of micrometers to a few micrometers, whereas for other carbons, the increase of adsorption capacity was small for MIB and moderate for geosmin. An increase of adsorption capacity was observed for other hydrophobic adsorbates besides geosmin and MIB, but not for hydrophilic adsorbates. The parameter values of a shell adsorption model describing the increase of adsorption capacity were negatively correlated with the oxygen content of the carbon among other characteristics. Low oxygen content indicated low hydrophilicity. The increase of adsorption capacity was related to the hydrophobic properties of both adsorbates and activated carbons. For adsorptive removal of hydrophobic micropollutants such as geosmin, it is therefore recommended that less-hydrophilic activated carbons, such as coconut-shell-based carbons, be microground to a particle diameter of a few micrometers to enhance their equilibrium adsorption capacity. In contrast, adsorption by hydrophilic carbons or adsorption of hydrophilic adsorbates occur in the inner pores, and therefore adsorption capacity is unchanged by particle size reduction.

Topics: Adsorption; Camphanes; Charcoal; Models, Theoretical; Naphthols; Oxygen; Particle Size; Water Pollutants, Chemical; Water Purification

Toxic cyanobacterial blooms, which produce cyclic heptapeptide toxins known as microcystins, are worldwide environmental problems. On the other hand, the cyanobacteria protein (30-50%) has been recommended as substitute protein for aquaculture. The present laboratory study verified the feasibility of cyanobacteria protein substitution and risk assessment. Goldfish were fed diets supplemented lyophilised cyanobacteria powder for 16 weeks with the various doses: 0% (control), 10%, 20%, 30% and 40%. Low doses (10% and 20%) promoted growth whereas high doses (30% and 40%) inhibited growth. In cyanobacteria treated fish, the proximate composition of ash, crude fat content and crude protein content decreased in 16 weeks; the saturated fatty acid (SFA) content significantly increased; the n-3 polyunsaturated fatty acid content, collagen content and muscle pH significantly decreased; cooking loss percents increased significantly. Muscle fiber diameter and myofibril length were negatively correlation. Additionally, flavour compounds (e.g., amino acids, nucleotides, organic acids and carnosine) changed significantly in the treated fish, and odour compounds geosmin and 2-methylisoborneol increased significantly. The estimated daily intake (EDI) of microcystins in muscle was close to or exceeded the World Health Organization (WHO) tolerable daily intake (TDI), representing a great health risk. Cyanobacterie is not feasible for protein sources use in aquaculture.

Topics: Amino Acids; Animals; Aquaculture; Bacterial Proteins; Camphanes; Chromatography, High Pressure Liquid; Collagen; Cyanobacteria; Dietary Supplements; Enzyme-Linked Immunosorbent Assay; Fatty Acids; Fatty Acids, Omega-3; Feasibility Studies; Gas Chromatography-Mass Spectrometry; Goldfish; Meat; Microcystins; Muscle, Skeletal; Naphthols; Risk Assessment

The odorous compounds of 2-methylisoborneol (2-MIB) and geosmin (GSM) heavily produced and released in water source are one of the most important factors leading to off-flavor emergencies and resident water consumption panic in drinking water. A headspace solid phase micro-extraction ( HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS) method was established for the simultaneous determination of these two trace earthy and musty compounds in reservoir water, reservoir soil and tap water. The conditions of HS-SPME, such as salt amount, extraction time and extraction temperature, were optimized based on orthogonal analysis. The qualitative and quantitative analyses of 2-MIB and GSM were carried out in the electron impact (EI) -selective ion scanning mode. The results showed that the linear relationship between peak area and concentration of 2-MIB and GSM was good enough (r2 0.998) from 5 to 1 000 ng/L, the limits of detection were 0.72 ng/L for 2-MIB, 0.34 ng/L for GSM and the limits of quantification were 2.40 ng/L for 2-MIB, 1.13 ng/L for GSM. When the target samples spiked in the range of 10-600 ng/L, the average recoveries of the target compounds were 93.6% - 107.7% ( RSD ≤ 6.1%, n = 6). Based on the above method, the target compounds in reservoir water, reservoir soil and tap water in a certain region of Liaoning Province were analyzed. The results showed that the two target odors in reservoir water were 3.0 -3.6 ng/L. As for the extract of the soil around the reservoir, 2-MIB was 8.1 ng/L and GSM was 17.8 ng/L. The odorous substances were not detected in the tap water. This method is simple, accurate, reliable, highly sensitive and no need of organic solvents. And it is suitable for the detection of 2-MIB and GSM in drinking water.

Topics: Camphanes; Drinking Water; Gas Chromatography-Mass Spectrometry; Naphthols; Solid Phase Microextraction; Water Pollutants, Chemical

Chemical compositions and muddy compounds in dorsal and ventral muscles of Nile tilapia and broadhead catfish were comparatively studied. On a dry weight basis, Nile tilapia was rich in protein (93.1-93.8%), whilst broadhead catfish contained protein (55.2-59.5%) and lipid (36.6-42.4%) as the major constituents. Ventral portion had higher lipid or phospholipid contents with coincidentally higher geosmin and/or 2-methylisoborneol (2-MIB) contents. Geosmin was found in mince of Nile tilapia and broadhead catfish at levels of 1.5 and 3.2μg/kg, respectively. Broadhead catfish mince had 2-MIB at level of 0.8μg/kg, but no 2-MIB was detected in Nile tilapia counterpart. When pre-washing and alkaline solubilisation were applied for preparing protein isolate (PI), lipid and phospholipid contents were lowered with concomitant decrease in geosmin and 2-MIB contents. Protein hydrolysate produced from PI had a lighter colour and a lower amount of muddy compounds, compared with that prepared from mince. Therefore, PI from both Nile tilapia and broadhead catfish could serve as the promising proteinaceous material, yielding protein hydrolysate with the negligible muddy odour and flavour.

Topics: Animals; Camphanes; Catfishes; Cichlids; Fish Products; Fish Proteins; Food Handling; Humans; Naphthols; Odorants; Protein Hydrolysates; Taste

The release of intracellular microcystin-LR (MC-LR), 2-methylisoborneol (MIB), and geosmin was investigated after the oxidation of three cyanobacteria (Microcystis aeruginosa (MA), Oscillatoria sp. (OSC), and Lyngbya sp. (LYN)). During the oxidation of 200,000 cells/mL of MA, release of intracellular MC-LR exceeded the World Health Organization (WHO) guideline of 1 μg/L during the lowest oxidant exposures (CT) tested: ozone (0 mg-min/L, below the ozone demand), chlorine (<40 mg-min/L), chlorine dioxide (<560 mg-min/L), and chloramine (<640 mg-min/L). As the CT increased, ozone, chlorine, and chlorine dioxide were able to oxidize the released MC-LR. During the oxidation of OSC (2800 cells/mL) and LYN (1600 cells/mL), release of intracellular MIB and geosmin exceeded reported threshold odor values after exposure to chlorine, chlorine dioxide, and chloramine, which have low reactivity with these taste and odor compounds. Ozone oxidation of OSC yielded an increase in MIB concentration at lower exposures (≤2.9 mg-min/L), likely due to insufficient oxidation by hydroxyl radicals. The release of intracellular organic matter (IOM) was also measured to determine the potential of bulk measurements to act as a surrogate for cyanotoxins and metabolite release. In all cases, the dissolved organic carbon (DOC) release was less than 0.25 mgC/L, which lacked the sensitivity to indicate the release of MC-LR, MIB, or geosmin. The fluorescence index proved to be a more sensitive indicator of intracellular organic matter release than DOC for MA. These results illustrate that toxic or odorous compounds may be released from cyanobacteria cells during oxidation processes with minimal changes in the DOC concentration.

Topics: Camphanes; Chloramines; Chlorine; Chlorine Compounds; Cyanobacteria; Marine Toxins; Microcystins; Microcystis; Naphthols; Odorants; Oxidants; Oxides; Ozone; Water Purification

Considering the limited number of studies on the biological effects on human health of cyanobacterial compounds that cause taste and odor, the present study assessed the cytotoxic and genotoxic potentials of 2-methylisoborneol (2-MIB) and geosmin (GEO) using the MTT assay and the in vitro comet and cytokinesis-block micronucleus (CBMN-Cyt) assays in human HepG2 cells. The toxicogenomics of genes responsive to DNA damage and metabolization by the exposure of cells to 2-MIB and GEO were also investigated. The results showed that concentrations of 2-MIB and GEO above 100 and 75 μg/mL, respectively, were cytotoxic to HepG2 cells. Doses of 2-MIB (12.5, 25, 50, 75 and 100 μg/mL) and GEO (12.5, 25, 50, and 75 μg/mL) were unable to induce neither DNA damage nor events associated with chromosomal instability. Similarly, no concentration of each compound induced increments in the expression of CDKN1A, GADD45α, MDM2 and TP53 DNA damage responsive genes as well as in CYP1A1 and CYP1A2 metabolizing genes. Although cytotoxicity was observed, concentrations that caused it are much higher than those expected to occur in aquatic environments. Thus, environmentally relevant concentrations of both compounds are not expected to exhibit cytotoxicity or genotoxicity to humans.

Topics: Camphanes; Comet Assay; Cyanobacteria; DNA Damage; Drinking Water; Hep G2 Cells; Humans; Micronucleus Tests; Naphthols; Odorants; Taste; Toxicogenetics; Water Pollutants, Chemical

Decreasing the particle size of powdered activated carbon may enhance its equilibrium adsorption capacity for small molecules and micropollutants, such as 2-methylisoborneol (MIB) and geosmin, as well as for macromolecules and natural organic matter. Shell adsorption, in which adsorbates do not completely penetrate the adsorbent but instead preferentially adsorb near the outer surface of the adsorbent, may explain this enhancement in equilibrium adsorption capacity. Here, we used isotope microscopy and deuterium-doped MIB and geosmin to directly visualize the solid-phase adsorbate concentration profiles of MIB and geosmin in carbon particles. The deuterium/hydrogen ratio, which we used as an index of the solid-phase concentration of MIB and geosmin, was higher in the shell region than in the inner region of carbon particles. Solid-phase concentrations of MIB and geosmin obtained from the deuterium/hydrogen ratio roughly agreed with those predicted by shell adsorption model analyses of isotherm data. The direct visualization of the localization of micropollutant adsorbates in activated carbon particles provided direct evidence of shell adsorption.

Topics: Adsorption; Camphanes; Carbon Isotopes; Charcoal; Microscopy; Naphthols; Particle Size; Powders; Temperature

The musty-odor compounds (MOCs) 2-methylisoborneol (2-MIB) and geosmin in water samples were determined by a purge-and-trap method using a needle-type extraction device followed by gas chromatography-mass spectrometry. For the extraction of these compounds, a triple-layer-type extraction needle containing divinylbenzene and activated carbon particles as the particulate extraction media was introduced. Several experimental parameters, including the sample temperature during extraction, the addition of sodium chloride, and desorption conditions, were thoroughly optimized in this study. The detection limits for 2-MIB and geosmin were 1.0 and 0.5 ng L(-1), respectively. The method was successfully applied to the simultaneous determination of MOCs and other volatile organic compounds in tap-water samples.

Topics: Camphanes; Gas Chromatography-Mass Spectrometry; Limit of Detection; Naphthols; Needles; Odorants; Water

The odor in raw water is one of the main sources of odor in drinking water. The occurrence of actinobacteria and their odor producing capacities in a reservoir in.Shanghai were investigated. Gauze's medium and membrane filtration were used for actinobacteria isolation. Through combined methods of 16S rRNA sequencing, colony and hyphae morphology, carbon source utilization, physiological and biochemical characteristics, 40 strains of actinobacteria were identified from the reservoir. Results showed that there were 38 Streptomyces, an Aeromicrobium and a Pseudonocardia. Liquid culture medium and the real reservoir water were used to test the odor producing capacity of these 40 strains of actinobacteria, and headspace solid phase microextraction (HS-SPME) and high resolution gas chromatography mass spectroscopy (GC/MS) were used to analyze the odor compounds 2-methylisoborneol (2-MIB) and geosmin (GSM) in the fermentation liquor. The test results showed that, the odor-producing capacities of these actinobacteria in different fermentation media showed different variation trends, even within the genera Streptomyces. The odor-producing capacity of actinobacteria in the liquid culture medium could not represent their states in the reservoir water or their actual odor contribution to the aquatic environment.

Topics: Actinobacteria; Camphanes; China; Drinking Water; Gas Chromatography-Mass Spectrometry; Naphthols; Odorants; RNA, Ribosomal, 16S; Solid Phase Microextraction; Water Microbiology; Water Pollutants, Chemical

2-Methylisoborneol (MIB) and geosmin are naturally occurring compounds responsible for musty-earthy taste and odor in public drinking-water supplies, a severe problem faced by many utilities throughout the world. In this study, we investigated adsorptive removal of these compounds by superfine powdered activation carbon (SPAC, particle size <1 μm) produced by novel micro-grinding of powdered activated carbon; we also discuss the optimization of carbon particle size to efficiently enhance the adsorptive removal. After grinding, the absorptive capacity remained unchanged for a 2007 carbon sample and was increased for a 2010 carbon sample; the capacity increase was quantitatively described by the shell adsorption model, in which MIB and geosmin adsorbed more in the exterior of a carbon particle than in the center. The extremely high uptake rates of MIB and geosmin by SPAC were simulated well by a combination of the branched-pore kinetic model and the shell adsorption model, in which intraparticle diffusion through macropores was followed by diffusion from macropore to micropore. Simulations suggested that D40 was on the whole the best characteristic diameter to represent a size-disperse group of adsorbent particles; D40 is the diameter through which 40% of the particles by volume pass. Therefore, D40 can be used as an index for evaluating the improvement of adsorptive removal that resulted from pulverization. The dose required for a certain percentage removal of MIB or geosmin decreased linearly with carbon particle size (D40), but the dose reduction became less effective as the activated carbon was ground down to smaller sizes around a critical value of D40. For a 60-min contact time, critical D40 was 2-2.5 μm for MIB and 0.4-0.5 μm for geosmin. The smaller critical D40 was when the shorter the carbon-water contact time was or the slower the intraparticle mass transfer rate of an adsorbate was.

Topics: Adsorption; Camphanes; Charcoal; Gas Chromatography-Mass Spectrometry; Japan; Kinetics; Models, Theoretical; Naphthols; Organic Chemicals; Particle Size; Particulate Matter; Time Factors; Water Pollutants, Chemical; Water Purification

The concentrations of earthy and musty odor compounds (2-methylisoborneol (2-MIB), geosmin and 2,4,6-trichloroanisole (TCA)) in treated wastewater were measured. Concentrations of 2,4,6-TCA (4.3-37.7 ng/L) and geosmin (3.7-42.2 ng/L) higher than their odor thresholds were detected for effluents from large-scale treatment plants. The effluent from a small-scale wastewater plant treating toilet and kitchen wastewater contained the target earthy and musty odor compounds below the odor thresholds. The ozonation applied as an advanced wastewater treatment process was considerably more effective for the removal of 2,4,6-TCA than for the removal of 2-MIB and geosmin. The measured concentrations of 2,4,6-TCA in river environments without the influence of large-scale wastewater effluents were less than the odor threshold.

Topics: Anisoles; Camphanes; Chromatography, Gas; Naphthols; Odorants; Rivers; Tokyo; Waste Disposal, Fluid; Wastewater; Water Pollutants, Chemical

A sensitive and solvent-less method for the determination of musty and earthy off-flavor compounds, 2-methylisoborneol (MIB) and geosmin (GSM), in salmon tissue was developed using stir bar sorptive extraction-thermal desorption coupled with gas chromatography-mass spectrometry (SBSE-TD-GCMS). MIB and GSM were solid phase extracted using polydimethylsiloxane (PDMS) coated stir bars, analyzed by gas chromatography, and detected in full scan mode of mass selective detector (MSD). Using this method, the calibration curves of MIB and GSM were linear in the range of 0.3-100ng/L, with a correlation coefficient above 0.999 and RSDs less than 4% (n=4). The limit of detection (LOD, S/N=3, n=6) and limit of quantification (LOQ, S/N=10, n=6) of MIB and GSM were both ∼0.3 and 1ng/L, respectively. The recoveries of MIB and GSM were 22% and 29% by spike in 30ng/L standard compounds, 23% and 30% by spike-in 100ng/L standard compounds in salmon tissue samples with good precision (<8% of RSDs, n=6), respectively. The recoveries of MIB and GSM were better than reported methodologies using SPME fibres (<10%) in fish tissue samples. This method was successfully applied to monitor and characterize depurated salmon fillet samples (0, 3, 6 and 10 days).

Topics: Animals; Camphanes; Gas Chromatography-Mass Spectrometry; Limit of Detection; Naphthols; Salmon; Seafood

A variety of factors affecting water quality in recirculating aquaculture systems (RAS) are associated with the occurrence of off-flavours. In this study, we report the impact of water quality on the bacterial diversity and the occurrence of the geosmin-synthesis gene (geoA) in two RAS units operated for 252 days. Unit 2 displayed a higher level of turbidity and phosphate, which affected the fresh water quality compared with unit 1. In the biofilter, nitrification is one of the major processes by which high water quality is maintained. The bacterial population observed in the unit 1 biofilter was more stable throughout the experiment, with a higher level of nitrifying bacteria compared with the unit 2 biofilter. Geosmin appeared in fish flesh after 84 days in unit 2, whereas it appeared in unit 1 after 168 days, but at a much lower level. The geoA gene was detected in both units, 28 days prior to the detection of geosmin in fish flesh. In addition, we detected sequences associated with Sorangium and Nannocystis (Myxococcales): members of these genera are known to produce geosmin. These sequences were observed at an earlier time in unit 2 and at a higher level than in unit 1. This study confirms the advantages of new molecular methods to understand the occurrence of geosmin production in RAS.

Topics: Animals; Aquaculture; Bacteria; Camphanes; Fresh Water; Naphthols; Nitrification; Oncorhynchus mykiss; Water Quality

The presence of off-flavor compounds in fish represents a significant economic problem encountered in aquaculture production. The off-flavor compounds are due to the absorption of substances produced by a range of microorganisms. Currently, a number of strategies have been used to prevent or limit the growth of these microorganisms. Therefore, it is important to evaluate the effectiveness of strategies via monitoring the concentrations of off-flavor compounds in the recirculating aquaculture system. In vivo solid-phase microextraction (SPME), a rapid and simple sample preparation method, will allow monitoring the concentration of off-flavor compounds in live fish. In this research, geosmin and 2-methylisoborneol (2-MIB) produced by cyanobacteria and actinomycetes, which are the major sources for "earthy" and "muddy" flavors in fish, were selected as representatives. In order to accurately quantify these compounds in fish muscle, two kinetic calibration methods, on-fiber standardization and measurement using predetermined sampling rate, were used as quantification methods, which were both validated by traditional methods. The detection limit of in vivo SPME in fish muscle was 0.12 ng/g for geosmin and 0.21 ng/g for 2-MIB, which are both below the human sensory thresholds.

Topics: Actinobacteria; Animals; Aquaculture; Calibration; Camphanes; Cyanobacteria; Fishes; Flavoring Agents; Microwaves; Muscles; Naphthols; Solid Phase Microextraction; Spectrometry, Mass, Electrospray Ionization

The goal of this study was to develop a robust method capable of quantifying taste and odor compounds (i.e., geosmin and 2-methylisoborneol) at very low aqueous concentrations in the presence of wastewater and algal derived contaminants. A polydimethylsiloxane/divinylbenzene (PDMS/DVB) fiber was used to perform headspace-solid phase microextraction (HS-SPME) to extract and analyze taste and odor compounds from model, source water, and finished drinking water samples. Gas chromatography coupled with mass spectrometery (GC/MS) in full scan mode was used to analyze the compounds desorbed from the fiber in the GC inlet. The following parameters were optimized in order to enhance analyte recovery: extraction temperature, extraction time, desorption time, sonication temperature, sonication time and GC/MS configuration/temperature program. After optimization, the method provided a linear response from 1 to 300 ng L(-1) and yielded limit of detections (LODs) of 1 ng L(-1) for both 2-MIB and geosmin. In MS full scan mode, wastewater contaminants and other algal derived volatile organic compounds (ADVOCs) relevant to cyanobacterial bloom dynamics were detected and monitored in real source water samples. In the presence of known interferents with similar mass/charge fragments and elution times, the optimized method yielded low detection limits as well as exact molecular confirmation for taste and odor compounds in impacted source water samples. This method could be used as a tool to aid in the development of source water protection plans by identifying potential sources of anthropogenic and algal derived contamination in drinking water sources.

Topics: Camphanes; Dimethylpolysiloxanes; Drinking Water; Environmental Monitoring; Gas Chromatography-Mass Spectrometry; Naphthols; Odorants; Ohio; Polyvinyls; Solid Phase Microextraction; Volatile Organic Compounds; Water Pollutants, Chemical

Rapid and direct, in situ headspace screening for odoriferous volatile organic compounds (VOCs) present in fresh grapes and in wines is a very promising method for quality control because the economic value of a wine is closely related to its aroma. Long used for the detection of VOCs in complex mixtures, miniature differential ion mobility spectrometry (DMS) seems therefore adequate for in situ trace detection of many kinds of VOCs of concern appearing in the headspace of selected foodstuffs. This work aims at a rapid detection, identification, and quantification of some natural and volatile contaminants of wine such as geosmin, 2-methylisoborneol (2-MIB), 1-octen-3-ol, 1-octen-3-one, and pyrazines (2-isopropyl-3-methoxypyrazine, IPMP, and 3-isobutyl-2-methoxypyrazine, IBMP). In the present study, these compounds were spiked at a known concentration in wine and analyzed with a hyphenated trap-GC-DMS device. The detection of all target compounds at concentrations below the human olfactory threshold was demonstrated.

Topics: Camphanes; Gas Chromatography-Mass Spectrometry; Humans; Ketones; Naphthols; Octanols; Olfactometry; Pyrazines; Smell; Vitis; Volatile Organic Compounds; Wine

Initial geosmin degradation was closely related to water temperature and natural geosmin concentration of sampling environment. Here, for the first time, we evaluated the biodegradation of geosmin by microorganisms in biofilm from biological treatment unit of actual potable water treatment plant.. At an initial geosmin concentration of 2,500 ng/l, efficient geosmin removal was confirmed throughout the year. Furthermore, in the presence of mixed musty odor compounds (geosmin and MIB) as carbon source, geosmin degradation was enhanced compared to sole carbon source (geosmin alone).. PCR-DGGE analysis revealed a rich community structure within the biofilm during rapid geosmin removal period, April. PCA revealed that the significant change in bacterial communities occurred from day 1 to day 2. Two novel geosmin-degrading bacteria were isolated from the biofilm of the biological treatment unit of Kasumigaura Water Purification, Waterworks Department, Japan. They belong to Methylobacterium sp. and Oxalobacteraceae bacterium, respectively.. These studies provide further insights into the unknown microbiological processes that occur during the biological removal of geosmin through water treatment and could facilitate the geosmin bioremediation in contaminated habitats.

Topics: Biofilms; Camphanes; Databases, Nucleic Acid; Denaturing Gradient Gel Electrophoresis; Japan; Lakes; Methylobacterium; Molecular Typing; Naphthols; Odorants; Oxalobacteraceae; Phylogeny; Polymerase Chain Reaction; Principal Component Analysis; Seasons; Temperature; Time Factors; Water Pollutants, Chemical; Water Purification

Using a relatively simple enrichment technique, geosmin and 2-methylisoborneol (MIB)-biodegrading bacteria were isolated from a digestion basin in an aquaculture unit. Comparison of 16S rRNA gene sequences affiliated one of the three isolates with the Gram-positive genus Rhodococcus, while the other two isolates were found to be closely related to the Gram-negative family Comamonadaceae (Variovorax and Comamonas). Growth rates and geosmin and MIB removal rates by the isolates were determined under aerated and nonaerated conditions in mineral medium containing either of the two compounds as the sole carbon and energy source. All isolates exhibited their fastest growth under aerobic conditions, with generation times ranging from 3.1 to 5.7 h, compared to generation times of up to 19.1 h in the nonaerated flasks. Incubation of the isolates with additional carbon sources caused a significant increase in their growth rates, while removal rates of geosmin and MIB were significantly lower than those for incubation with only geosmin or MIB. By fluorescence in situ hybridization, members of the genera Rhodococcus and Comamonas were detected in geosmin- and MIB-enriched sludge from the digestion basin.

Topics: Camphanes; Carbon; Cluster Analysis; Comamonadaceae; Comamonas; DNA, Bacterial; DNA, Ribosomal; Molecular Sequence Data; Naphthols; Phylogeny; Rhodococcus; RNA, Ribosomal, 16S; Sequence Analysis, DNA; Water Microbiology; Water Pollutants

Off-flavors are among the most troublesome compounds in the environment worldwide. The lack of a viable theory for studying the sources, distribution, and effect of odors has necessitated the accurate measurement of odors from environmental compartments. A rapid and flexible microwave-assisted purge-and-trap extraction device for simultaneously determining five predominant odors, namely, dimethyltrisulfide, 2-methylisoborneol, geosmin, β-cyclocitral and β-ionone, from the primary sources and sinks is demonstrated. This instrument facilitates the extraction and concentration of odors from quite different matrices simultaneously. This device is a solvent-free automated system that does not require cleaning and is timesaving. The calibration curves of the five odor compounds showed good linearity in the range of 1-500 ng/L, with correlation coefficients above 0.999 (levels=7) and with residuals ranging from approximately 77% to 104%. The limits of detection (S/N=3) were below 0.15 ng/L in algae sample and 0.07 ng/g in sediment and fish tissue samples. The relative standard deviations were between 2.65% and 7.29% (n=6). Thus the proposed design is ready for rapid translation into a standard analytical tool and is useful for multiple applications in the analysis of off-flavors.

Topics: Aldehydes; Animals; Camphanes; Chemical Fractionation; Chlorophyta; Diterpenes; Equipment Design; Fishes; Gas Chromatography-Mass Spectrometry; Geologic Sediments; Limit of Detection; Linear Models; Microwaves; Naphthols; Norisoprenoids; Odorants; Reproducibility of Results

A Penicillium polonicum, an Aspergillus ustus and a Periconia britannica strain were isolated from water-damaged environments and the production of microbial volatile organic compounds (MVOCs) was investigated by means of headspace solid-phase microextraction followed by GC-MS analysis. The most important MVOCs produced were 2-methylisoborneol, geosmin and daucane-type sesquiterpenes for P. polonicum, 1-octen-3-ol, 3-octanone, germacrene D, δ-cadinene and other sesquiterpenes for A. ustus and the volatile mycotoxin precursor aristolochene together with valencene, α-selinene and β-selinene for P. britannica. Different growth conditions (substrate, temperature, relative humidity) were selected, resembling indoor parameters, to investigate their influence on fungal metabolism in relation with the sick building syndrome and the results were compared with two other fungal strains previously analyzed under the same conditions. In general, the range of MVOCs and the emitted quantities were larger on malt extract agar than on wallpaper and plasterboard, but, overall, the main MVOC profile was conserved also on the two building materials tested. The influence of temperature and relative humidity on growth and metabolism is different for different fungal species, and two main patterns of behavior could be distinguished. Results show that, even at suboptimal conditions for growth, production of fungal volatiles can be significant.

Topics: Analysis of Variance; Camphanes; Gas Chromatography-Mass Spectrometry; Housing; Humans; Humidity; Ketones; Mitosporic Fungi; Naphthols; Octanols; Sesquiterpenes; Sesquiterpenes, Germacrane; Sick Building Syndrome; Solid Phase Extraction; Species Specificity; Temperature; Volatile Organic Compounds

Geosmin and 2-methylisoborneol (MIB) related odor events caused by cyanobacteria have been a very common problem to water supply. This paper investigated the effects of temperature (18 and 25 °C) and light intensity (10 and 100 μmol photons m(-2) s(-1)) on the production behaviors of earthy odor compounds by three odorous cyanobacteria, i.e., the geosmin-producing planktonic Anabaena circinalis (Ana 318), geosmin-producing benthic Phormidium amoenum (Pho 012) and MIB-producing benthic Phormidium sp. (Pho 689). At the same time, the effects of biodegradation and volatilization on the fates of the released odor compounds in water were also evaluated. The combination of high temperature (25 °C) and light intensity (100 μmol photons m(-2) s(-1)) favored the growth of the three cyanobacteria and the production of chl-a and odor compounds. However, higher chl-a and odor yields (average odor compounds per cell) were achieved for the two benthic cyanobacteria at the temperature of 18 °C. Most of geosmin was included within the cells for Ana 318 (95-99%) and Pho 012 (85-60%), while only 20-40% MIB was bound to the cells for Pho 689. The half-life times of MIB and geosmin due to volatilization varied between 18.8 and 35.4 days, while 8 out of 10 samples exhibited a half-life time (t(1/2)) for geosmin biodegradation shorter than 1 day (0.38-15.0 h), showing that biodegradation could affect the fate of geosmin significantly in aquatic environments. In comparison, biodegradation of MIB was much slower (t(1/2): 122-2166 h). Denaturing gradient gel electrophoresis (DGGE) analysis showed that Pseudomonas- and Sphingomonas-like bacteria coexisted with cyanobacteria in the cultures, and may have played an important role in geosmin/MIB biodegradation. The result of this study will be helpful for better understanding and managing the earthy odor problems caused by cyanobacteria in water supply.

Topics: Australia; Biodegradation, Environmental; California; Camphanes; Chlorophyll; Chlorophyll A; Cyanobacteria; Denaturing Gradient Gel Electrophoresis; Light; Naphthols; Odorants; Species Specificity; Temperature; Volatilization; Water Supply

The occurrence of the taste and odour compounds geosmin and 2-methyl isoborneol (2-MIB) affects the organoleptic quality of raw waters from drinking water reservoirs worldwide. UV-based oxidation processes for the removal of these substances are an alternative to adsorption and biological processes, since they additionally provide disinfection of the raw water. We could show that the concentration of geosmin and 2-MIB could be reduced by VUV irradiation and the combination of UV irradiation with ozone and hydrogen peroxide in pure water and water from a drinking water reservoir. The figure of merit EE/O is an appropriate tool to compare the AOPs and showed that VUV and UV/O(3) yielded the lowest treatment costs for the odour compounds in pure and raw water, respectively. Additionally, VUV irradiation with addition of ozone, generated by the VUV lamp, was evaluated. The generation of ozone and the irradiation were performed in a single reactor system using the same low-pressure mercury lamp, thereby reducing the energy consumption of the treatment process. The formation of the undesired by-products nitrite and bromate was investigated. The combination of VUV irradiation with ozone produced by a VUV lamp avoided the formation of relevant concentrations of the by-products. The internal generation of ozone is capable to produce ozone concentrations sufficient to reduce EE/O below 1 kWh m(-3) and without the risk of the formation of nitrite or bromate above the maximum contaminant level.

Topics: Bromates; Camphanes; Drinking Water; Gas Chromatography-Mass Spectrometry; Naphthols; Nitrites; Odorants; Oxidation-Reduction; Ultraviolet Rays; Water Pollutants, Chemical; Water Purification

Muddy and/or musty off-flavors in farmed-raised catfish occur as a result of the absorption of geosmin (GEO) and 2-methylisoborneol (MIB), compounds produced by algae. Previous research suggests the acid pH-shift method may be able to reduce off-flavors to produce a consumer acceptable product. The objective of this research was to evaluate application of the acid pH-shift method using a shaker sieve for protein recovery and to evaluate consumer acceptability of a resultant batter-coated fried nugget-like catfish product. Farm-raised catfish were either allowed to depurate (control) or treated with 1 ppb GEO or MIB. Fillets from each replicate were collected and ground and treated by the acid pH-shift process. Samples from all treatments and replicates were evaluated for residual GEO and MIB. In addition, batter-coated fried catfish samples were prepared for a consumer sensory evaluation. Results demonstrated that the pH-shift process decreased moisture, ash, and collagen content of catfish fillet tissue (P < 0.05). Flavor of control samples was preferred (P < 0.05). Texture of catfish samples treated by the pH-shift process was preferred (P < 0.05). Results demonstrate the pH-shift process can be utilized to reduce off-flavors and increase the acceptability of a processed catfish product.. Use of a sieve as an economic alternative for the pH-shift process was evaluated for removing off-flavors from catfish. Difficulties were encountered with regard to protein recovery using the sieve and suggestions are made to, perhaps, make the process more applicable for a sieve-based recovery step. The process as described reduced off-flavors, but only 2-fold suggesting the process would work best on catfish near or just over off-flavor thresholds. Results also indicated the pH-shift process could be used to improve texture of a fried catfish product designed to be similar to chicken nuggets.

Topics: Adolescent; Adult; Animals; Camphanes; Catfishes; Consumer Behavior; Female; Humans; Hydrogen-Ion Concentration; Male; Middle Aged; Naphthols; Seafood; Surveys and Questionnaires; Taste; Young Adult

Municipal wastewater often contains trace amounts of organic compounds that can compromise aesthetics of drinking water and undermine public confidence if a small amount of effluent enters the raw water source of a potable water supply. To efficiently identify compounds responsible for odors in wastewater effluent, an analytical framework consisting of gas chromatography with mass spectrometry (GC-MS) and gas chromatography with olfactometry detection (GC-Olf) coupled with flavor profile analysis (FPA) was used to identify and monitor compounds that could affect the aesthetics of drinking water. After prioritizing odor peaks detected in wastewater effluent by GC-Olf, the odorous components were tentatively identified using retention indices, mass spectra and odor descriptors. Wastewater effluent samples were typically dominated by earthy-musty odors with additional odors in the amine, sulfidic and fragrant categories. 2,4,6-trichloroanisole (246TCA), geosmin and 2-methylisoborneol (2MIB) were the main sources of the earthy/musty odors in wastewater effluent. The other odors were attributable to a suite of compounds, which were detected in some but not all of the wastewater effluents at levels well in excess of their odor thresholds. In most cases, the identities of odorants were confirmed using authentic standards. The fate of these odorous compounds, including 2-pyrrolidone, methylnaphthalenes, vanillin and 5-hydroxyvanillin (5-OH-vanillin), should be considered in future studies of water systems that receive effluent from upstream sources.

Topics: Amines; Camphanes; Chromatography, Gas; Gas Chromatography-Mass Spectrometry; Naphthols; Odorants; Wastewater

A fast, simple and environmentally friendly ultrasound-assisted dispersive liquid-liquid microextraction (USADLLME) procedure has been developed to preconcentrate geosmin and 2-methylisoborneol (MIB) from water and wine samples prior to quantification by gas chromatography-mass spectrometry (GC-MS). A two-stage multivariate optimization approach was developed by means of a Plackett-Burman design for screening and selecting the significant variables involved in the USADLLME procedure, which was later optimized by means of a circumscribed central composite design. The optimum conditions were: solvent volume, 8μL; solvent type: tetrachloroethylene; sample volume, 12 mL; centrifugation speed, 2300 rpm; extraction temperature 20 °C; extraction time, 3 min; and centrifugation time, 3 min. Under the optimized experimental conditions the method gave good levels of repeatability with coefficient of variation under 11% (n=10). Limits of detection were 2 and 9 ng L⁻¹ for geosmin and MIB, respectively. Calculated calibration curves gave high levels of linearity with correlation coefficient values of 0.9988 and 0.9994 for geosmin and MIB, respectively. Finally, the proposed method was applied to the analysis of two water (reservoir and tap) samples and three wine (red, rose and white) samples. The samples were previously analyzed and confirmed free of target analytes. Recovery values ranged between 70 and 113% at two spiking levels (0.25 μg L⁻¹ and 30 ng L⁻¹) showing that the matrix had a negligible effect upon extraction. Only red wine showed a noticeable matrix effect (70-72% recovery). Similar conclusions have been obtained from an uncertainty budget evaluation study.

Topics: Analysis of Variance; Camphanes; Chemical Fractionation; Gas Chromatography-Mass Spectrometry; Naphthols; Ultrasonics; Water; Water Supply; Wine

Modeling of human exposure to aqueous algal odorants geosmin (earthy), 2-methylisoborneol (musty), and (trans,cis)-2,6-nonadienal (cucumber, fishy), and the solvent trichloroethylene (sweet chemical), was investigated to improve the understanding of water-air transfer by including humans as sensors to detect contaminants. A mass-transfer model was employed to determine indoor air concentrations when water was used for showering under varying conditions (shower stall volume, water and air flow rate, temperature, aqueous odorant concentration, shower duration). Statistical application of multiple linear regression and tree regression were employed to determine critical model parameters. The model predicted that concentrations detectable to the human senses were controlled by temperature, odor threshold, and aqueous concentration for the steady-state model, whereas shower volume, air flow, and water flow are also important for the dynamic model and initial detection of the odorant immediately after the showering is started. There was excellent agreement of model predictions with literature data for human perception of algal odorants in their homes and complaints to water utilities. TCE performed differently than the algal odorants due to its higher Henry's law constant, in spite of similar gas and liquid diffusivities. The use of nontoxic odorants offers an efficient tool to calibrate indoor air/water shower models.

Topics: Air Pollution, Indoor; Aldehydes; Baths; Camphanes; Environmental Exposure; Humans; Linear Models; Models, Biological; Naphthols; Odorants; Olfactory Perception; Smell; Trichloroethylene; Water Pollutants, Chemical

Advanced treatment technologies that control multiple contaminants are beneficial to drinking water treatment. This research applied UV/H(2)O(2) for the simultaneous degradation of geosmin, 2-methylisoborneol, four trihalomethanes and six haloacetic acids. Experiments were conducted in de-ionized water at 24 ± 1.0 °C with ng/L amounts of odorants and μg/L amounts of disinfection byproducts. UV was applied with and without 6 mg/L H(2)O(2.) The results demonstrated that brominated trihalomethanes and brominated haloacetic acids were degraded to a greater extent than geosmin and 2-methylisoborneol. Tribromomethane and dibromochloromethane were degraded by 99% and 80% respectively at the UV dose of 1200 mJ/cm(2) with 6 mg/L H(2)O(2), whereas 90% of the geosmin and 60% of the 2-methylisoborneol were removed. Tribromoacetic acid and dibromoacetic acid were degraded by 99% and 80% respectively under the same conditions. Concentrations of trichloromethane and chlorinated haloacetic acids were not substantially reduced under these conditions and were not effectively removed at doses designed to remove geosmin and 2-methylisoborneol. Brominated compounds were degraded primarily by direct photolysis and cleavage of the C-Br bond with pseudo first order rate constants ranging from 10(-3) to 10(-2) s(-1). Geosmin and 2-methylisoborneol were primarily degraded by reaction with hydroxyl radical with direct photolysis as a minor factor. Perchlorinated disinfection byproducts were degraded by reaction with hydroxyl radicals. These results indicate that the UV/H(2)O(2) can be applied to effectively control both odorants and brominated disinfection byproducts.

Topics: Acetates; Camphanes; Chloroacetates; Disinfectants; Hydrocarbons, Brominated; Hydrogen Peroxide; Naphthols; Odorants; Trichloroacetic Acid; Ultraviolet Rays; Water Purification

Migration and variation of odorous compounds as geosmin, 2-methylisoborneol (MIB) and residual chlorine in drinking water taken from Huangpu River were studied by using headspace solid phase microextraction procedure (HSPME) and gas chromatograph with mass spectrometry. The results showed that, raw water, processed water, pipe water (taken from pump station) and secondary-supply water all contained MIB and geosmin ranging from 2 ng/L to 18 ng/L and 2.68 ng/L to 5.06 ng/L respectively and decreased dramatically during the water processing and distribution system. MIB is proved to be a kind of the odorous compounds in drinking water of Shanghai by comparing the concentrations of MIB and GSM with their odor threshold. The concentration of residual chlorine declined greatly in the distribution system, but because of the high value at the outlet of waterworks, it still may exceeded the influence of MIB and cause the odour problems.

Topics: Camphanes; China; Naphthols; Odorants; Rivers; Water Pollutants, Chemical; Water Purification; Water Supply

Production and fate of taste and odor (T&O) compounds in natural waters are a pressing environmental issue. Simultaneous determination of these complex compounds (covering a wide range of boiling points) has been difficult. A simple and sensitive method for the determination of eight malodors products of cyanobacterial blooms was developed using automatic purge and trap (P&T) coupled with gas chromatography-mass spectrometry (GC-MS). This extraction and concentration technique is solvent-free. Dimethylsulfide (DMS), dimethyltrisulfide (DMTS), 2-isopropyl-3-methoxypyrazine (IPMP), 2-isobutyl-3-methoxypyrazine (IBMP), 2-methylisoborneol (MIB), β-cyclocitral, geosmin (GSM) and β-ionone were separated within 15.3 min. P&T uses trap #07 and high-purity nitrogen purge gas. The calibration curves of the eight odors show good linearity in the range of 1-500 ng/L with a correlation coefficient above 0.999 (levels=8) and with residuals ranging from approximately 83% to 124%. The limits of detection (LOD) (S/N=3) are all below 1.5 ng/L that of GSM is even lower at 0.08 ng/L. The relative standard deviations (RSD) are between 3.38% and 8.59% (n=5) and recoveries of the analytes from water samples of a eutrophic lake are between 80.54% and 114.91%. This method could be widely employed for monitoring these eight odors in natural waters.

Topics: Adsorption; Aldehydes; Camphanes; Diterpenes; Eutrophication; Fresh Water; Gas Chromatography-Mass Spectrometry; Naphthols; Norisoprenoids; Odorants; Pyrazines; Reproducibility of Results; Sensitivity and Specificity; Sulfides; Temperature

The adsorption of the taste and odour (T&O) compounds geosmin and 2-methylisoborneol (2-MIB) onto powdered activated carbon (PAC) has been studied under conditions which are typical for a drinking water treatment plant that uses reservoir water for drinking water production. The reservoir water as well as the pre-treated water (after flocculation) contains NOM that competes with the trace compounds for the adsorption sites on the carbon surface. Although the DOC concentrations in the reservoir water and in the pre-treated water were different, no differences in the competitive adsorption could be seen. By using two special characterisation methods for NOM (adsorption analysis, LC/OCD) it could be proved that flocculation removes only NOM fractions which are irrelevant for competitive adsorption. Different model approaches were applied to describe the competitive adsorption of the T&O compounds and NOM, the tracer model, the equivalent background compound model, and the simplified equivalent background compound model. All these models are equilibrium models but in practice the contact time in flow-through reactors is typically shorter than the time needed to establish the adsorption equilibrium. In this paper it is demonstrated that the established model approaches can be used to describe competitive adsorption of T&O compounds and NOM also under non-equilibrium conditions. The results of the model applications showed that in particular the simplified equivalent background compound model is a useful tool to determine the PAC dosage required to reduce the T&O compounds below the threshold concentration.

Topics: Adsorption; Camphanes; Charcoal; Flocculation; Models, Chemical; Naphthols; Water Pollutants, Chemical; Water Purification; Water Supply

An exploratory study on the management of undesirable cyanobacteria blooms with respect to off-flavor problems using an integrated vertical-flow constructed wetland (CW) was performed at a small commercial-scale channel catfish farm from 2004 to 2007. The results of the three-year experiment indicated that water treatment by the CW could reduce the possibility of dominance by undesirable cyanobacteria species that often cause off-flavor problems. A detailed investigation in 2007, showed that the concentrations of geosmin, MIB (2-methylisoborneol), and β-cyclocitral in the water of the recirculating pond (4.3ngL(-1), U.D. (undetected) and 0.2ngL(-1), respectively) treated by the CW were significantly lower than those in the control pond (152.6ngL(-1), 63.3ngL(-1) and 254.8ngL(-1), respectively). In addition, the relationships among the cyanobacteria species, the off-flavor compounds and ten environmental variables were explored by canonical correspondence analysis (CCA). The results showed that Oscillatoria sp., Oscillatoria kawamurae and Microcystis aeruginosa were the main sources of off-flavor compounds in the catfish ponds. The successful manipulation of undesirable cyanobacteria species potentially resulted in lower concentrations of odorous compounds in the water of the recirculating pond. An investigation of the concentrations of geosmin and MIB in catfish fillets showed that the levels of odorous compounds were below the OTC (odor threshold concentration) values in the recirculating pond but were above the OTC values from July to October in the control pond. Water recycling by the CW could potentially be one of the best management practices to control off-flavor occurrences in aquaculture.

Topics: Aldehydes; Animals; Aquaculture; Camphanes; Cyanobacteria; Diterpenes; Environmental Monitoring; Eutrophication; Feeding Behavior; Ictaluridae; Naphthols; Odorants; Phytoplankton; Ponds; Seasons; Survival Analysis; Waste Disposal, Fluid; Water Movements; Water Pollutants, Chemical; Water Quality; Wetlands

Globally, aquaculture systems with water recirculation experience increasing problems with microbial taste and odor compounds (TOCs) such as geosmin and 2-methylisoborneol (MIB). This study investigated the content of geosmin and MIB in water and the flesh of 200 rainbow trouts from eight recirculated aquaculture systems in Denmark. TOC content in the fish flesh was measured by a dynamic headspace extraction method and was evaluated by a sensory panel. The results showed significant correlations between TOC content in water and fish and between chemical analysis and sensory perception. When geosmin exceeded 20 ng/L in the water, 96% of the fish had an intense muddy flavor, but below 10 ng geosmin/L, 18% of the fish (only 3% in special depuration ponds) had an intense muddy flavor. The results indicate that TOC levels <10 ng/L will ensure that a negligible portion of the fish obtains an unpalatable taste and flavor due to TOCs.

Topics: Animals; Aquaculture; Camphanes; Denmark; Food Contamination; Humans; Meat; Naphthols; Odorants; Oncorhynchus mykiss; Sensation; Taste; Water

Nanofiltration (NF) has been shown to be an effective way of removing organic micropollutants from drinking water due to its size exclusion properties. A rapid bench scale membrane test unit was utilised to trial six NF membranes to remove the algal metabolites, microcystin, cylindrospermopsin, 2-methylisoborneol (MIB) and geosmin (GSM). Membrane fouling due to the algal metabolites was observed for both charged and neutral metabolites. MIB and GSM were removed effectively by low molecular weight cut-off (MWCO) membranes but less effectively by a higher MWCO membrane. Removal of MIB and GSM by the higher MWCO membrane was improved as the membrane fouled. Microcystin was initially removed to above 90% by tight NF membranes but fouling of several membranes caused decreased percent removals over time. Tight NF membranes afforded removals of 90-100% for cylindrospermopsin, while removal by the higher MWCO membrane was lower but improved with time due to fouling.

Topics: Alkaloids; Bacterial Toxins; Biofouling; Camphanes; Cyanobacteria Toxins; Equipment Design; Eukaryota; Filtration; Membranes, Artificial; Microcystins; Nanotechnology; Naphthols; Time Factors; Uracil; Water Microbiology; Water Pollutants; Water Purification

A simple technique was developed to make in situ measurements of emission rates of two common odorants, 2-MIB and geosmin, and was validated with different natural communities of benthic cyanobacterial mats in Hope Valley Reservoir (HVR), South Australia, and Kin-Men Water Treatment Plant (TLR-WTP), Taiwan. A pair of parallel columns was used to differentiate between emission and loss rates caused by biodegradation, volatilization, and other mechanisms. Experimental results indicated that the loss rates followed a first-order relationship for all cases tested, with biodegradation and volatilization being the key mechanisms. The loss rates were comparable to those reported in the literature for biodegradation and those calculated from two-film theory for volatilization. After accounting for the loss rates, the net emission of geosmin and 2-MIB was estimated from experimental data. Odorant emission rates on the basis of column surface area, cyanobacterial cell number, and chlorophyll a (chl-a) were 4.2-4.4 ng h(-1) cm(-2), 1.0-5.5 x 10(-6) ng h(-1) cell(-1), and 3.2-3.5 ng h(-1)microg-chl(-1), respectively for 2-MIB released from benthic mats in TLR-WTP, and, 18-190 ng h(-1) cm(-2), 0.053-1.8 x 10(-3) ng h(-1) cell(-1), and 48-435 ng h(-1)microg-chl(-1) respectively for geosmin from benthic mats in HVR. The method developed provides a simple means to estimate the emission rates of odorants and possibly other algal metabolites from benthic cyanobacterial mats.

Topics: Australia; Camphanes; Cyanobacteria; Environmental Monitoring; Naphthols; Odorants; Taiwan; Water Microbiology; Water Pollutants, Chemical

This study evaluated the biodegradation of MIB (2-methylisoborneol) and geosmin (trans-1,10-dimethyl-trans- 9-decalol) in simulated slow sand filtration (SSF) columns and in batch reactors. The results showed that both MIB and geosmin were biodegradable in the two systems. In batch experiments, the overall removals for MIB and geosmin were 50% and 78%, respectively, after 7 days of contact time. Volatilization loss plays an important role for geosmin in batch systems. Simulated SSF column studies also showed that more than 50% of geosmin and MIB were degraded by the microbial on the sand surface of a slow sand filter. With a filtration rate of 5 m/day, the simulated SSF degraded MIB from 48% to 69% and geosmin from 87% to 96%. The rapid biodegradation of MIB and geosmin in SSF column tests was attributed to the use of filter sands from the SSF unit in the Kinmen water treatment plant, where the microbial had been acclimated to both MIB and geosmin. The results also showed that more than 70% of the geosmin was removed in the top portion of the filter ( approximately 10 cm); while the removal of MIB occurred throughout the entire column depth. The results of this study demonstrated that slow flow through preacclimated sand was effective for control of MIB and geosmin in drinking water.

Topics: Biodegradation, Environmental; Camphanes; Filtration; Naphthols; Water Pollutants, Chemical; Water Purification

Geosmin and 2-methylisoborneol are off-flavour compounds related to poor organoleptics and a decrease in consumer satisfaction with drinking water. The relationship between these off-flavour compounds and 39 parameters of water quality (chemical, physical and biological) for three different surface waters from lotic systems that supply potable water to Quebec City and Lévis (Canada) was studied using principal component analysis. The objective of this study was to show that a multidimensional approach with principal component analysis using the component matrix serves to differentiate the processes involved in the appearance of the olfactory compounds from those not involved or little involved and to extract the most representative data of these processes. Our study shows that the presence of geosmin can be explained, in the case of the water studied, by a process associated primarily with the eutrophication of water and, to a lesser degree, by an allochthonous origin. However, the presence of 2-methylisoborneol may be linked to two processes with different origins, but of equal importance: a winter origin - most likely allochthonous - involving anthropic contributions and an autochthonous bacterial origin.

Topics: Camphanes; Naphthols; Principal Component Analysis; Water Pollutants, Chemical; Water Supply

A novel in-tube extraction device (ITEX 2) for headspace sampling was evaluated for GC/MS analysis of aqueous samples. Twenty compounds of regulatory and drinking water quality importance were analyzed, including halogenated hydrocarbons, BTEX compounds (benzene, toluene, ethylbenzene, xylenes), fuel oxygenates, geosmin, and 2-methylisoborneol. Five commercially available sorbent traps were compared for their compound specific extraction yield. On the basis of the results, a mixed bed trap was prepared and evaluated. The extraction parameters were optimized to yield maximum sensitivity within the time of a GC run, to avoid unnecessary downtime of the system. Method detection limits of 1-10 ng L(-1) were achieved for volatile organic compounds (VOCs), which is much lower than demands by regulatory limit values. The performance of the ITEX system is similar to that of purge and trap systems, but it requires lower sample volumes and is less prone to contamination, much simpler, more flexible, and affordable. Average relative standard deviations below 10% were achieved for all analytes, and recoveries from spiked tap water samples were between 90% and 103%, mostly. The extraction is nonexhaustive, removing a fraction of 7% to 55% of the target compounds, depending on the air-water partitioning coefficients. The method was also tested with nonsynthetic samples, including tap, pond, and reservoir water and different soft drinks.

Topics: Camphanes; Chemical Fractionation; Cyanobacteria; Gas Chromatography-Mass Spectrometry; Limit of Detection; Linear Models; Naphthols; Organic Chemicals; Volatilization; Water; Water Pollutants, Chemical

A systematic study was conducted on seasonal and spatial patterns of taste and odor (T&O) compounds with relation to biotic and abiotic parameters at fifteen sites in Gonghu Bay of Lake Taihu in 2008. We developed a sensitive and automated method to simultaneously analyze eight T&O compounds (boiling points ranging from 38°C to 239°C) by using Purge-and-Trap (P&T) coupled with GC/MS. Maximum particulate dimethyl trisulfide (DMTS, 69.6 ng/L) exceeded its odor threshold concentrations (OTC, 10 ng/L) and maximum dissolved DMTS was 6.1 ng/L, but still far below concentration in the drinking water pollution incident of Wuxi City in 2007 when DMTS reached 1768-11,399 ng/L. Geosmin (GEO), 2-methylisoborneol (MIB), β-cyclocitral, β-ionone and 2-isobutyl-3-methoxypyrazine (IBMP) occasionally or frequently exceeded their OTCs, whereas 2-isopropyl-3-methoxypyrazine (IPMP) and dimethyl sulfide (DMS) did not. We found for the first time significant correlations between particulate β-cyclocitral and β-ionon concentrations and intracellular and extracellular microcystin concentrations. Spatially, Nanquan Waterworks faced more risk by T&O contamination than Xidong Waterworks. High concentrations of NO(3)-N, TDN and TN could be risky signs of taste and odor events by DMS, DMTS, IPMP, IBMP and GEO.

Topics: Aldehydes; Camphanes; China; Diterpenes; Environmental Monitoring; Fresh Water; Microcystins; Naphthols; Norisoprenoids; Odorants; Phytoplankton; Pyrazines; Seasons; Sulfides; Taste; Water Pollutants, Chemical; Water Supply

Geosmin and 2-methylisoborneol (2-MIB) are naturally occurring compounds responsible for musty-earthy-odors in surface water supplies. They are a severe problem confronting utilities worldwide. Adsorption by powdered activated carbon (PAC) is a widely used process to control this problem, but it has low efficiency, which engenders large budget spending for utilities services. Super-powdered activated carbon (S-PAC) is activated carbon with much finer particles than those of PAC. Experiments on geosmin and 2-MIB adsorptions on S-PAC and PAC were conducted. Geosmin and 2-MIB adsorption capacities on S-PAC were not smaller than those on PAC although natural organic matter, which adversely impacted the adsorption capacity of geosmin and 2-MIB, was more adsorbed on S-PAC than on PAC, meaning that the adsorption competition is less severe for S-PAC than for PAC.

Topics: Adsorption; Camphanes; Cyclohexanes; Humic Substances; Naphthols; Water Pollutants, Chemical; Water Purification

Topics: Bacterial Toxins; Camphanes; Cyanobacteria; Cyanobacteria Toxins; Environmental Monitoring; Fresh Water; Harmful Algal Bloom; Marine Toxins; Microcystins; Naphthols; Odorants; Water Pollutants, Chemical

In a previous study on a recirculating fish culture system, levels of geosmin and 2-methylisoborneol were found to decrease when culture water was recirculated through the anaerobic sludge digestion treatment stage of the system. This finding led us to the present study in which the geosmin and 2-methylisoborneol removal capacity of the sludge derived from this treatment stage was examined in vitro. It was found that reduction of off-flavor compounds by the sludge was mediated by both chemical/physical sorption and biological degradation. At geosmin and 2-methylisoborneol concentrations within the range of those experienced in fish culture systems, chemical/physical sorption by the sludge was found to account for a 93% reduction in geosmin and a 79% reduction in 2-methylisoborneol from the overlying water within 48h of incubation. Combined with the biological degradation taking place in the sludge, a complete removal of these compounds from the water phase occurred within 9 days of incubation. By means of repeated washing of the geosmin and 2-methylisoborneol contaminate sludge with clean water, relatively small amounts of these compounds were released from the sludge, a possible indication for the fact that absorption, rather than adsorption, underlies the chemical/physical removal process.

Topics: Aquaculture; Camphanes; Naphthols; Sewage; Time Factors; Waste Disposal, Fluid; Water Purification

The degradation of geosmin and 2-methylisoborneol (2-MIB) by UV irradiation at different wavelengths was investigated under varying boundary conditions. The results showed that conventional UV radiation (254 nm) is ineffective in removing these compounds from water. In contrast to the usual UV radiation UV/VUV radiation (254+185 nm) was more effective in the removal of the taste and odour compounds. The degradation could be described by a simple pseudo first-order rate law with rate constants of about 1.2 x 10(-3) m(2)J(-1) for geosmin and 2-MIB in ultrapure water. In natural water used for drinking water abstraction the rate constants decreased to 2.7 x 10(-4) m(2)J(-1) for geosmin and 2.5 x 10(-4) m(2)J(-1) for 2-MIB due to the presence of NOM. Additionally, the formation of the by-product nitrite was studied. In the UV/VUV irradiation process up to 0.6 mg L(-1) nitrite was formed during the complete photoinitiated oxidation of the odour compounds. However, the addition of low ozone doses could prevent the formation of nitrite in the UV/VUV irradiation experiments.

Topics: Bicarbonates; Camphanes; Hydrogen-Ion Concentration; Hydroxyl Radical; Kinetics; Naphthols; Nitrites; Organic Chemicals; Oxidation-Reduction; Spectrum Analysis; Ultraviolet Rays; Water

The cytotoxicity of musty odor-emitting substances, geosmin (GM) and 2-methylisoborneol, at a concentration of 10 ng/L - 300 mg/L was investigated using cultured mammalian cells. These two compounds exhibited no cytotoxicity in either the colony-formation of human KB cells or WST-1 assays of human-, monkey-, and dog-derived cells. These results suggest that the maximum concentration (700 ng/L) of GM found in the water of Lake Shinji is not toxic.

Topics: Animals; Camphanes; Cell Culture Techniques; Cell Line; Cell Survival; Chlorocebus aethiops; Dogs; Dose-Response Relationship, Drug; Humans; Naphthols; Odorants

This study assessed the impact of MIEX pre-treatment, followed by either coagulation or microfiltration (MF), on the effectiveness of pilot granular activated carbon (GAC) filters for the removal of the taste and odour compounds, 2-methylisoborneol (MIB) and geosmin, from a surface drinking water source over a 2-year period. Complete removal of MIB and geosmin was achieved by all GAC filters for the first 10 months, suggesting that the available adsorption capacity was sufficient to compensate for differences in dissolved organic carbon (DOC) entering the GAC filters. Reduction of empty bed contact time (EBCT), in all but one GAC filter, resulted in breakthrough of spiked MIB and geosmin, with initial results inconclusive regarding the impact of MIEX pre-treatment. MIB and geosmin removal increased over the ensuing 12 months until complete removal of both MIB and geosmin was again achieved in all but one GAC filter, which had been pre-chlorinated. Autoclaving and washing the GAC filters had minimal impact on geosmin removal but reduced MIB removal by 30% in all but the pre-chlorinated filter, confirming that biodegradation impacted MIB removal. The impact of biodegradation was greater than any impact on GAC adsorption arising from DOC differences due to MIEX pre-treatment. It is not clear whether, at a lower initial EBCT, MIEX pre-treatment may have impacted on the adsorption capacity of the virgin GAC. The GAC filter maintained at the longer EBCT, which was also pre-chlorinated, completely removed MIB and geosmin for the period of the study, suggesting that the greater adsorption capacity was compensating for any decrease in biological degradation.

Topics: Biodegradation, Environmental; Camphanes; Charcoal; Ion Exchange; Naphthols; Ultrafiltration; Water Pollutants, Chemical; Water Purification; Water Supply

Geosmin and 2-methylisoborneol are secondary metabolites expressed by a variety of organisms that are responsible for off-flavors in public water supplies, aquaculture, and a host of other important products. Hence, there is continuing research into the causes for their expression and methods to mitigate it, which require sensitive and accurate detection methods. In recent years, several new techniques for collecting and concentrating volatile and semi-volatile compounds have been automated and commercialized, making them available for use in most laboratories. In this study, we compared solid-phase microextraction (SPME) and membrane-assisted solvent extraction (MASE) for the detection of 2-methylisoborneol and geosmin in aqueous samples. SPME is the most sensitive of these techniques with a limit of detection of 25 parts-per-trillion for 2-methylisoborneol and 10 parts-per-trillion for geosmin but with a large relative standard deviation. MASE is less sensitive, but provides a greater level of precision, as well as the ability for multiple injections from the same sample.

Topics: Camphanes; Eukaryota; Gas Chromatography-Mass Spectrometry; Naphthols; Reproducibility of Results; Solid Phase Microextraction

Liquid-liquid microextraction/GC/MS analysis method was employed in detecting trace odorants in drinking water. A-year-long investigation on odor chemicals was carried out in source water and drinking water in a certain waterworks of Shanghai. The results showed that 2-MIB was the main contaminant which induce disgusting odor to drinking water of Shanghai in July, August, September and October in a year with the peak concentration of 2-MIB 152.82 ng/L in raw water and 97.94 ng/L in finished water from waterworks. Oscillatoria was suspected as the resource of 2-MIB.

Topics: Camphanes; China; Environmental Monitoring; Naphthols; Water Pollutants, Chemical; Water Supply

Two common drinking water earthy/musty odorants, 2-methyl-isoborneol (2-MIB) and trans-1,10-dimethyl-trans-9-decalol (geosmin), were monitored and analyzed for their correlation with environmental conditions in Feng-Shen Reservoir (FSR), Taiwan. Long-term monitoring results, from December 2000 to July 2003, indicated that 2-MIB was present in the reservoir at concentrations between 10 and 200 ng L(-1), and those of geosmin were always smaller than 10 ng L(-1). The 2-MIB concentrations followed a trend of higher concentrations during the warm seasons. After being analyzed with 10 water quality and three meteorological parameters, 2-MIB concentration was found to correlate with corresponding air and water temperatures. An analysis of air temperature history versus 2-MIB concentration in FSR suggested that 2-MIB concentration was best correlated with the mean of average daily temperature from 1 to 9 days before sampling, with R (2) = 0.90. This correlation was further employed to predict the 2-MIB concentration observed during another sampling period in FSR. A similar degree of fit was observed between predictions and experimental data, suggesting the potential applicability of the approach. In addition to the effect of temperature, heavy rainfalls that occurred before the sampling time may also reduce the 2-MIB concentration in the reservoir. A short-term continuous monitoring of the odorants for 32 h showed that both geosmin and 2-MIB concentrations in the reservoir remained almost constant, with only about a 10% difference during the sampling period. This may suggest that the odorants were uniformly distributed in the water near the sampling location in the reservoir.

Topics: Camphanes; Environmental Monitoring; Naphthols; Seasons; Taiwan; Water Pollutants, Chemical

One of bacteria collected from Lake Sagami, Japan, Brevibacillus sp., was found to have a lytic activity of cyanobacteria, but did not produce active compounds. Instead, the co-culturing of Microcystis with the Brevibacillus sp. enhanced the production of two volatile compounds, beta-cyclocitral and 3-methyl-1-butanol, and the former had a characteristic lytic activity. It was confirmed that these volatile compounds were derived from the cyanobacteria themselves. beta-Ionone, geosmin and 2-methylisoborneol derived from cyanobacteria and similar volatile compounds, terpenoids, produced by plants also had a lytic activity. The minimum inhibitory concentration values of the cyanobacterial metabolites were estimated to be higher than those of compounds from plants except for a few compounds. Among them, beta-cyclocitral only produced a characteristic color change of culture broth from green to blue. This color change is similar to the phenomenon observed when a sudden decline in growth of cyanobacteria begins in a natural environment.

Topics: Aldehydes; Bacteriolysis; Camphanes; Cyanobacteria; Diterpenes; Japan; Molecular Structure; Naphthols; Norisoprenoids; Organic Chemicals; Pentanols; Terpenes; Volatilization

A simple and sensitive method for the determination of musty odorants, 2-methylisoborneol (MIB) and geosmin (GSM), in environmental water was developed by headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry. MIB and GSM were separated within 10 min using a DB-1 capillary column and detected in the selective ion monitoring mode. HS-SPME using a polydimethylsiloxane/divinylbenzene fiber provided effective sample enrichment, and was carried out by fiber exposition at 70 degrees C for 30 min. Using this method, the calibration curves of MIB and GSM were linear in the range of 0-500 pg/mL, with a correlation coefficient above 0.9977 (n=24). The detection limits (S/N=3) of MIB and GSM were 0.9 and 0.6 pg/mL, respectively. This method was successfully applied to the analysis of environmental water samples without interference peaks.

Topics: Calibration; Camphanes; Environment; Gas Chromatography-Mass Spectrometry; Naphthols; Odorants; Reference Standards; Solid Phase Microextraction; Solutions; Temperature; Time Factors; Water

Taste and odour (T&O) causing compounds, in particular, 2-methylisoborneol (MIB) and geosmin, are a problem for water authorities as they are recalcitrant to conventional water treatment. In this study, biological sand filtration was shown to be an effective process for the complete removal of MIB and geosmin, with removal shown to be predominantly through biodegradation. In addition, MIB and geosmin were also effectively degraded in batch bioreactor experiments using biofilm sourced from one of the sand filters as the microbial inoculum. The biodegradation of MIB and geosmin was determined to be a pseudo-first-order reaction with rate constants ranging between 0.10 and 0.58 d(-1) in the bioreactor experiments. Rate constants were shown to be dependent upon the initial concentration of the microbial inoculum but not the initial concentration of MIB and geosmin when target concentrations of 200 and 50 ng l(-1) were used. Furthermore, rate constants were shown to increase upon re-exposure of the biofilm to both T&O compounds. Enrichment cultures with subsequent community profile analysis using 16S rRNA-directed PCR-DGGE identified four bacteria most likely involved in the biodegradation of geosmin within the sand filters and bioreactors. These included a Pseudomonas sp., Alphaproteobacterium, Sphingomonas sp. and an Acidobacteriaceae member.

Topics: Bacteria; Biodegradation, Environmental; Biofilms; Bioreactors; Camphanes; Electrophoresis; Naphthols; Odorants; RNA, Ribosomal, 16S; Silicon Dioxide; Water Pollutants, Chemical; Water Purification; Water Supply

Geosmin and 2-methylisoborneol (MIB) are two substances causing earthy/musty odours that are difficult to remove by conventional chemical drinking water treatment. In this study removal of geosmin and MIB by biofiltration of untreated surface water was investigated using granular activated carbon (GAC) and crushed expanded clay (EC) as filter media. Biofiltration through both GAC and EC removed geosmin and MIB present at low (20 ng l(-1)) concentrations by at least 97% at an empty bed contact time of 30 minutes and a temperature of 15 degrees C. At lower temperature (6-12 degrees C) and simultaneously lower biomass concentrations, removal efficiency was similar in the GAC but considerably lower in the EC biofilter, pointing to a second mechanism different from biodegradation. Consequently, microbial activity was suppressed with azide to enable discrimination between biodegradation and adsorption. During azide dosage, the GAC biofilters still removed geosmin and MIB nearly unaffectedly. In the EC biofilter, however, removal of both odorants ceased completely. Methylene blue adsorption confirmed that the GAC, even after almost four years of operation receiving surface water, had capacity to remove geosmin and MIB by adsorption. Since odour episodes commonly occur during the warm season when microbiological activity is high, EC constitutes a viable option as carrier medium for direct biological filtration of surface water. The additional GAC adsorption capacity however adds robustness to the removal process.

Topics: Adsorption; Biodegradation, Environmental; Camphanes; Filtration; Naphthols; Water Purification

The algal extracellular products (ECPs) in three cultures of cyanobacteria species (Anabaena, Microcystis, and Oscillatoria) dominating the eutrophic reservoir populations and their toxins have been investigated in the present work. Using gas chromatography coupled with high-resolution electron-impact mass spectrometry (GC/EI-MS) and high performance anion-exchange chromatography (HPAEC) techniques, more than 20 compounds were found in the algal culture (including cells and filtrates) extracts. The main identified ECPs were classified to polysaccharides, hydrocarbons, and aldehydes. Odor causing substances such as trans-1,10-dimethyl-trans-9-decalol (geosmin) and 2-methylisoborneol (2-MIB)were also found in the algal cultures. The potential mutagenicity of the algal suspensions was also studied with the Ames test. The organic extracts of the algal suspension from the axenic cultures were mutagenicity in TA98 without S9 mix and in TA100 with and without S9 mix. The results indicate that the ECPs of three algae species dominating the eutrophic reservoir were mutagenic clearly in the bacterial test.

Topics: Camphanes; Carbon; Carboxylic Acids; Chlorophyll; Chlorophyll A; Complex Mixtures; Cyanobacteria; Eutrophication; Hydrocarbons; Marine Toxins; Microcystins; Mutagenicity Tests; Naphthols; Polysaccharides; Salmonella typhimurium; Taiwan; Water Supply

2-Methylisoborneol (MIB) and geosmin (GSM) are taste and odor compounds produced by cyanobacteria in surface waters. While the strong odors and musty flavors of MIB and GSM are generally associated with poor water quality, the removal of these semi-volatile compounds presents a significant challenge to drinking water providers. Likewise in aquaculture, accumulation of these compounds in fish meat leads to quality problems and reduces marketability. Conventional water treatments are ineffective at removing low concentration of odor compounds. We report herein ultrasonic irradiation at 640 kHz leads to rapid degradation of MIB and GSM. While radical processes generally dominate during ultrasonic-induced degradation, pyrolysis appears to be responsible for a significant fraction of the observed degradation. Several pyrolytic products from MIB and GSM have been identified and degradation pathways are elucidated. The degradation of MIB and GSM follows the first-order kinetics and the rate constants are 0.07 and 0.12 min(-1), respectively. These results suggest ultrasonic irradiation maybe applicable as an effective method for removal of taint compounds from potable water supplies and fish farms.

Topics: Camphanes; Naphthols; Phthalic Acids; tert-Butyl Alcohol; Ultrasonics; Water Pollutants, Chemical; Water Purification

Diamond Valley Lake is a large drinking water reservoir in western Riverside County, California near the city of Hemet. In almost 6 years since filling began in 1999, this reservoir has experienced five episodes involving either geosmin or 2-methylisoborneol (MIB). The first one was a short-lived but intense geosmin event in May 2000, associated with a planktonic cyanobacterium, Anabaena circinalis. Geosmin levels reached 750 ng/L at the surface. All the other episodes involved benthic proliferations in the littoral zone. In September 2002, an MIB-producing growth developed in a shallow area near the outlet tower, dominated by Oscillatoria cf. curviceps and O. limosa. A similar event occurred in October 2003. In March 2004, an extensive growth of cyanobacteria that included two geosmin producers developed at the east dam, but had minimal effect on geosmin levels in the water. Finally, there was a major MIB episode in October 2004, in which the primary causative organism was again Oscillatoria cf. curviceps. A band of benthic cyanobacteria developed all around the shoreline from 3-9 m deep, and surface MIB levels reached 63 ng/L. These events showed that a new reservoir in a mild climate can be colonised by benthic cyanobacteria that produce MIB and geosmin, within a relatively short time.

Topics: Biochemistry; Biodegradation, Environmental; California; Camphanes; Cyanobacteria; Ecosystem; Environmental Monitoring; Filtration; Naphthols; Water; Water Microbiology; Water Pollutants, Chemical; Water Pollution; Water Purification; Water Supply

Given their widespread and prolific annual development in the St. Lawrence River (SLR), macrophytes (i.e. submerged aquatic plants) represent large surface areas for biofilm growth and potentially important sites for associated production of taste and odour (T&O) compounds. We therefore evaluated the importance of submerged macrophytes and their associated biofilms for production of T&O compounds, 2-methylisoborneol (MIB) and geosmin (GM), compared with biofilms from adjacent rocks. We also tested the hypothesis that production of these compounds would differ between macrophyte species, based on the premise that they are not inert substrates but directly influence the communities that colonise their surfaces. Samples collected from transects across the SLR between Kingston and Cornwall, ON were dominated by the flat-bladed Vallisneria spp., and the leafed Myriophyllum spicatum, Elodea canadensis, Chara spp., Potamgeton spp., and Ceratophyllum spp. Overall, MIB and GM levels in biofilms ranged widely between samples. Expressed per g dry weight of biofilm, median levels from macrophyte were 50 (range 1-5000) ng MIB g(-1) and 10 (<1 to 580) ng GM g(-1) compared with 50 (range 5-970) ng MIB g(-1) and 160 (1-1600) ng GM g(-1) from rocks. Based on non-parametric statistical analysis, levels of GM were higher on a g dry weight basis in biofilms from rocks than macrophytes (P = 0.02), but MIB levels were similar (P = 0.94). However, when normalised for differences in substrate surface area (i.e. ng cm(-2)), levels of both MIB and GM were higher in biofilms from rocks than from macrophytes (P < 0.01). There were no discernable differences in MIB and GM concentrations from biofilms of different macrophytes based on either g dry weight sample or surface area (P > 0.05). Overlying water (OLW) concentrations ranged between 2-45 ng L(-1) for MIB and 5-30 ng L(-1) for GM and were not correlated with levels in adjacent biofilms. However, OLW concentrations peaked in shallow, low energy embayments consistent with enhanced production and release of MIB and GM in nearshore areas. The results support our previous work showing the importance of biofilms on various surfaces (rocks, macrophytes and zebra mussels) for MIB and GM production in the SLR, but suggest that inert surfaces like rocks are more productive sites per unit surface area than macrophytes.

Topics: Biodegradation, Environmental; Biofilms; Camphanes; Canada; Environmental Monitoring; Eukaryota; Filtration; Naphthols; Odorants; Rivers; Water Microbiology; Water Pollutants; Water Purification; Water Supply

Lake Dianchi is the sixth largest freshwater lake in China. The pilot experimental area (6 km2) in Lake Dianchi is one of the most severely polluted areas in the lake with heavy cyanobacteria blooms. During June 2002 to May 2003, the algal composition and number, and odorous compounds were identified monthly and monitored in the area. Meanwhile, physicochemical parameters such as total phosphorus (TP), total nitrogen (TN), 5-day biochemical oxygen demand (BOD5), chemical oxygen demand (COD(Mn)), dissolved oxygen (DO), pH, transparency, temperature and chlorophyll a (chla) were determined. Four odorous compounds: 2-methylisoborneol (MIB), geosmin, beta-cyclocitral and beta-ionone were found in the lake water. Both the concentration of particulate beta-cyclocitral and that of beta-ionone correlated significantly with the annual variation of Chla, biomass of total phytoplankton, cyanobacteria and Microcystis. The concentration of particulate MIB correlated significantly with the biomass of Oscillatoria, while the concentration of particulate geosmin correlated significantly with the biomass of Anabaena. Off-flavour in the pilot area was found to be caused by a combination of beta-cyclocitral- and beta-ionone-producing Microcystis, MIB-producing Oscillatoria and geosmin-producing Anabaena. beta-ionone, MIB and geosmin contributed collectively to the odour intensity in the lake water.

Topics: Aldehydes; Camphanes; China; Chlorophyll; Chlorophyll A; Diterpenes; Environmental Monitoring; Eutrophication; Fresh Water; Naphthols; Nitrogen; Norisoprenoids; Oxygen; Phosphorus; Phytoplankton; Water Pollutants, Chemical; Water Purification

The presence of unpleasant taste and odour in drinking water is an ongoing aesthetic concern for water providers worldwide. The need for a sensitive and robust method capable of analysis in both natural and treated waters is essential for early detection of taste and odour events. The purpose of this study was to develop and optimise a fast stir bar sorptive extraction (SBSE) method for the analysis of geosmin and 2-methylisoborneol (MIB) in both natural water and drinking water. Limits of detection with the optimised fast method (45 min extraction time at 60 degrees C using 24 microL stir bars) were 1.1 ng/L for geosmin and 4.2 ng/L for MIB. Relative standard deviations at the detection limits were under 17% for both compounds. Use of multiple stir bars can be used to decrease the detection limits further. The use of 25% NaCl and 5% methanol sample modifiers decreased the experimental recoveries. Likewise, addition of 1 mg/L and 1.5 mg/L NaOCI decreased the recoveries and this effect was not reversed by addition of 10% thiosulphate. The optimised method was used to measure geosmin concentrations in treated and untreated drinking water. MIB concentrations were below the detection limits in these waters.

Topics: Absorption; Camphanes; Chlorine; Environmental Monitoring; Gas Chromatography-Mass Spectrometry; Models, Statistical; Naphthols; Odorants; Reproducibility of Results; Sensitivity and Specificity; Temperature; Time Factors; Water Pollutants, Chemical; Water Purification; Water Supply

Seven major water treatment plants in Seoul Metropolitan Area, which are under Korea Water Resources Corporation (KOWACO)'s management, take water from the Paldang Reservoir in the Han River System for drinking water supply. There are taste and odour (T&O) problems in the finished water because the conventional treatment processes do not efficiently remove the T&O compounds. This study evaluated T&O removal by ozonation, granular activated carbon (GAC) treatment, powder activated carbon (PAC) and an advanced oxidation process in a pilot-scale treatment plant and bench-scale laboratory experiments. During T&O episodes, PAC alone was not adequate, but as a pretreatment together with GAC it could be a useful option. The optimal range of ozone dose was 1 to 2 mg/L at a contact time of 10 min. However, with ozone alone it was difficult to meet the T&O target of 3 TON and 15 ng/L of MIB or geosmin. The GAC adsorption capacity for DOC in the three GAC systems (F/A, GAC and O3 + GAC) at an EBCT of 14 min is mostly exhausted after 9 months. However, substantial TON removal continued for more than 2 years (>90,000 bed volumes). GAC was found to be effective for T&O control and the main removal mechanisms were adsorption capacity and biodegradation.

Topics: Adsorption; Biodegradation, Environmental; Camphanes; Carbon; Korea; Naphthols; Odorants; Oxygen; Ozone; Rivers; Time Factors; Water Pollutants, Chemical; Water Purification; Water Supply

Taste and odour problems of tap water in Seoul are attributed to 2-methylisoborneol (2-MIB) and trans-1,10-dimethyl-trans-9-decalol (geosmin), which are the result of metabolism of algae and chlorine for disinfection. This study was carried out to measure 2-MIB and geosmin in the raw water from the Han River, to investigate removal efficiency of GAC and BAC integrated with post-ozonation, and to minimise and quantify the required chlorine concentration as a final disinfectant through the candidate process.

Topics: Camphanes; Chlorine; Eukaryota; Korea; Naphthols; Odorants; Ozone; Pilot Projects; Seasons; Time Factors; Water Microbiology; Water Purification; Water Supply

Among the chemicals causing taste and odour (T&O) in drinking water, the most commonly identified and problematic ones are geosmin and 2-MIB (2-methylisoborneol). Since the reported odour thresholds of geosmin and 2-MIB are as low as 4 and 8.5 ng/L, respectively, they are not readily removed by conventional water treatment processes. In this study, ozone (O3) and ferrate (Fe(VI)) were applied to oxidise geosmin and 2-MIB. Their performances were compared in terms of removal efficiency of geosmin and 2-MIB. In the case of O3, removal efficiency of geosmin and 2-MIB ozonation at different initial O3 doses, H2O2/O3 ratios and water temperatures were evaluated. The oxidation rates of geosmin and 2-MIB by Fe(VI) were measured within pH 6-8. The effect of H2O2 addition was also evaluated. In summary, O3, especially with H2O2, could almost completely oxidise geosmin and 2-MIB, while Fe(VI) could not oxidise them more than 25% at any pH that was considered in this study. This was attributed to the structure of the organics and high reaction selectivity of Fe(VI). Further study should be conducted to find the reason of inhibition of oxidation by Fe(VI).

Topics: Camphanes; Chemistry Techniques, Analytical; Environmental Monitoring; Hydrogen Peroxide; Hydrogen-Ion Concentration; Iron; Naphthols; Odorants; Oxygen; Ozone; Spectrophotometry, Ultraviolet; Temperature; Water; Water Purification

The study is focussed on the conditions that would provide the best ozone oxidation to decrease the taste and odour of the water from Eagle Gorge Reservoir. This study incorporated advanced analytical methods, such as solid phase microextraction (SPME) and flavour profile analyses (FPA), to evaluate the best method for improving taste and odour. The study developed first-order relationships between ozone dose and the oxidation of several taste and odour compounds. The results focussed on the importance and interactions between ozone dose, pH, hydrogen peroxide and contact time.

Topics: Camphanes; Chemistry Techniques, Analytical; Environmental Monitoring; Hydrogen Peroxide; Hydrogen-Ion Concentration; Naphthols; Odorants; Oxygen; Ozone; Solid Phase Extraction; Washington; Water; Water Purification; Water Supply

With an historical onus on reactive water treatment in North America, most taste and odour (T&O) outbreaks and other water quality issues have been unanticipated and difficult to control. Recent severe outbreaks of these drinking water issues have prompted wider advocacy of a more proactive "source-to-tap" approach, with greater focus on multidisciplinary partnerships among utilities, scientists and management/policy-makers. However, the practical application of this management model is faced with fragmented drainage basins, waterbodies and jurisdictions, and often requires a common issue such as T&O to initiate its development. This paper presents an example of a successful cooperative approach to drinking water management, the Ontario Water Works Research Consortium (OWWRC), consisting of the six major water utilities drawing water from Western Lake Ontario, scientists from the Canadian and Ontario governments and universities, and several other agencies. Established in 1999 following severe T&O outbreaks, the OWWRC has since operated as a highly effective model, employing a science-based approach to T&O management, supporting research on source-water and treatment issues, public outreach and utility surveys. The paper describes this partnership and summarises the results of an OWWRC T&O survey as one of the significant steps towards source-water characterisation undertaken by this cooperative.

Topics: Camphanes; Environmental Monitoring; Fresh Water; Naphthols; Odorants; Ontario; Water; Water Pollutants, Chemical; Water Pollution; Water Purification; Water Supply

The Hinze Dam is located in the Gold Coast hinterland and is the primary source of water supply for the Gold Coast region. Sporadic and unpredictable taste and odour events caused by geosmin and 2-methylisoborneol (MIB) are an ongoing problem in the Hinze Dam. To investigate potential ecological and physiological triggers of these events, a 12-month surface-sampling regime was undertaken. Concentrations of geosmin, MIB, nitrogen and phosphorus were measured. Algal and cyanobacterial counts were performed. Water temperature, rainfall and dam capacity were also recorded. The occurrence of geosmin was found to correlate significantly with Anabaena numbers, water temperature and dam capacity. The occurrence of MIB correlated with increasing ammonia. No significant correlations were observed with the other nutrients or physical parameters measured. Overall, this study demonstrated that high concentrations of geosmin detected in dam surface waters was strongly correlated with an increase in numbers of Anabaena spp. These events were most likely triggered by significant rainfall causing a pulse in nutrients into the dam, in conjunction with warmer water temperatures.

Topics: Australia; Camphanes; Cyanobacteria; Environmental Monitoring; Eukaryota; Naphthols; Nitrogen; Odorants; Phosphorus; Temperature; Time Factors; Water; Water Microbiology; Water Pollutants, Chemical

The most common compounds responsible for off flavours are geosmin, 2-MIB, and nonadienal which are poorly removed by conventional water treatment operations and hence result in customer complaints. Because these odourants are moderately volatile and have very low odour threshold values, it is necessary to determine their concentrations in air when water is used indoors. If the detectable aqueous concentrations for these odourants are known, the utilities may take action to treat their water at times when the concentration of the raw water exceeds the threshold concentration. To predict the concentration in the shower stall and bathroom air after showering, recently published Henry's law constants for the selected odourants and a model developed to determine the volatilization of the odourous compounds by applying two-resistance theory were used. Then the results were compared with the odour threshold concentration data to determine under which conditions the odourants become detectable. For parameters representing a typical bathroom and shower stall setting, the results showed that the odourants become detectable when the aqueous concentration of geosmin and nonadienal exceed 10 ng/L at 42 degrees C. As the aqueous concentration increases, geosmin and nonadienal become detectable at lower temperatures, however 2-MIB is only detectable above 20 ng/L and at 42 degrees C.

Topics: Camphanes; Facility Design and Construction; Humans; Naphthols; Odorants; Smell; Temperature; Thermodynamics; Water Pollutants, Chemical; Water Purification; Water Supply

The objective of our study was to survey the accumulated 2-methylisoborneol (MIB) and geosmin (GSM) in fillets of five important farmed fish species in Hungarian aquaculture in relation to MIB and GSM concentrations in water and sediment in the aquatic systems where they were raised: (the planktivorous silver carp (Hypophthalmichthys molitrix), the herbivorous grass carp (Ctenopharyngodon idella), the bottom-feeding omnivorous common carp (Cyprinus carpio), the omnivorous tilapia (Oreochromis niloticus) and the carnivorous African catfish (Clarias gariepinus)). Water, sediment and fish samples were collected from different experimental aquatic systems which included a combined aquaculture-algae (CAA) system, effluent-fed fishponds, a pond recycling system and a traditional fishpond. MIB and GSM contents were extracted with distillation-headspace solid-phase-microextraction (SPME) and extracts analysed by GC-MS. Results showed that off-flavour contents in fish fillets were related to the feeding habits of the studied fish species. Higher GSM concentrations were found in the fillet of bottom-feeding common carp than in the silver carp or African catfish in all studied aquatic systems. Usually, low GSM concentrations were detected in the water of fishponds but sometimes the levels of this odour compound in carp fillet were well above the limits of human detection. This suggests that the off-flavour tainting of common carp may originate from the sediment or benthic algallactinomycete sources. Negligible MIB levels were found in all samples in all of the studied aquatic systems.

Topics: Animals; Camphanes; Catfishes; Environmental Monitoring; Fishes; Food Contamination; Fresh Water; Naphthols; Taste; Tilapia; Water Pollutants, Chemical

Over more than four decades odour research in the aquatic sciences has increasingly focused on cyanobacteria and the common odour-causing compounds, geosmin and 2-methylisoborneol. Success in future research requires a long-term perspective. Key areas for investigation are secondary metabolites and cyanobacteria, regulatory mechanisms for geosmin and other compounds' synthesis; understanding their spatial and temporal distribution (particularly relating to the food web in a habitat); and molecular mechanisms for liberation of geosmin by microorganisms.

Topics: Camphanes; Cyanobacteria; Naphthols; Odorants; Streptomyces; Water Microbiology; Water Pollutants, Chemical; Water Purification; Water Supply

A new sample preparation and enrichment technique, headspace liquid-phase microextraction (HS-LPME) linked to gas chromatography-mass spectrometry (GC-MS), was developed for the determination of the off-flavor odorants, 2-methylisoborneol and geosmin, produced by Streptomyces sp. and Anabaena PCC7120. Some of the factors that influence the extraction efficiency of HS-LPME, such as the type of extraction solvent, ionic strength of sample solution, and sample agitation rate, were studied and optimized by a single factor test. Other factors, including extraction temperature, extraction time, microdrop volume, and headspace volume were optimized by orthogonal array design. Extraction of 2-methylisoborneol and geosmin was conducted by exposing 2.5 microL of 1-hexanol for 9 min at 50 degrees C in the headspace of a 20 mL vial with a 10 mL of sample solution saturated by NaCl and stirred at 800 rpm. The developed protocol demonstrated good repeatability (relative standard deviations (RSDs) < 5%), wide linear ranges (10-5000 ng/L, r2 > 0.999), and low limits of detection (LODs) for 2-methylisoborneol and geosmin (0.05 ng/L for both analytes). Subsequently, the method was successfully applied to extract the analytes in bacterial cultures with high recoveries (from 94% to 98%). Compared with headspace solid-phase microextraction (HS-SPME), HS-LPME demonstrates better linearity, precision, and recovery. Importantly, the sensitivity is about 1 order of magnitude higher than that of most HS-SPME. The results showed that HS-LPME coupled with GC-MS is a simple, convenient, rapid, sensitive, and effective method for the qualitative and quantitative analysis of 2-methylisoborneol and geosmin.

Topics: Anabaena; Camphanes; Gas Chromatography-Mass Spectrometry; Naphthols; Sensitivity and Specificity; Streptomyces

Consumers generally concern taste and odor in drinking water. In the Southern Taiwan, more than 5,000,000 people are suffered from earth/musty odor in drinking water, especially in the summer. Thus, ozonation of geosmin (GSM), 2-methylisoborneol (2-MIB), and 2-furfural (2-FF) in eutrophic surface waters has been studied in the present work. Experimentally, it was found that the water contained high dissolved organic carbon (DOC), humic substances, and specific ultraviolet absorbance (SUVA) resulting the highly ozone (O3) demand. The natural organic matters (NOM) in the waters had a significant effect on the ozonation of GSM, 2-MIB and 2-FF. Their destruction rates were increased with high contents of aromatics, phenolics, and SUVAs. In addition, during ozonation of raw waters, O3 and OH. played an important role in destruction of algae cells and caused excretion of extracellular organic matter (EOM) to the bulk phase.

Topics: Camphanes; Eukaryota; Eutrophication; Fresh Water; Furaldehyde; Naphthols; Odorants; Ozone; Taiwan; Water Pollutants, Chemical; Water Purification; Water Supply

An automated technique based on purge-and-trap coupled to gas chromatography with mass spectrometric detection has been developed and optimized for the trace determination of five of the most important water odorants; 2-isopropyl-3-methoxypyrazine, 2-isobutyl-3-methoxypyrazine, 2-methylisoborneol, 2,4,6-trichloroanisole and geosmin. The extraction method was absolutely solvent-free. Analytes were purged from 20 ml of water sample containing sodium chloride at room temperature by a flow of He and trapped on a Tenax sorbent. The desorption step was performed with helium and temperature programming and desorbed analytes were directly transferred to a gas chromatograph coupled to a mass spectrometer for separation and determination. The method was reproducible (RSD<8%) and linear over the calibration range (10-200 ngl(-1)). The relative recoveries of the analytes from ground water sample were calculated and were between 80 and 103% and limits of detection (LOD) below odor thresholds were achieved for most of the compounds.

Topics: Anisoles; Automation; Camphanes; Gas Chromatography-Mass Spectrometry; Naphthols; Odorants; Online Systems; Pyrazines; Sensitivity and Specificity; Water

A new method was developed to measure Henry's law constants at varying temperatures and from these data determine enthalpies of reactions for volatilization of aqueous compounds. The method was applied to 2-methylisoborneol (2-MIB), geosmin, and trans-2,cis-6-nonadienal, which are three of the major odorous compounds found in natural and drinking water. The method used static headspace equilibrium in standard odor analysis flasks and SPME-GC/MS. Dimensionless Henry's law constants were determined at 20, 25, 32, and 39 degrees C in distilled water. Their values ranged from 0.002 to 0.02 and increased with increasing temperature. The study was continued by determining the effects of different concentrations of fulvic acid added to the aqueous media. Decreases of 5-40% in Henry's law constants were observed when fulvic acid was present; however the decrease was not correlated with the fulvic acid concentration. Fulvic acid at any concentration caused a small decrease in constants for geosmin and 2-MIB, yet a more substantial decrease was obtained for nonadienal. Finally, the gas-phase concentrations were predicted using measured Henry's law constants for known aqueous concentrations of 2-MIB, geosmin, and nonadienal at 25 and 45 degrees C. An increase in the gas-phase concentration was not correlated to an increase in human perception as determined by a trained human panel. It is concluded that, after some point, panelists were not able to perceive an increase in the odorant concentration. This has important implications for controlling nuisance odors in the environment.

Topics: Air Pollution; Aldehydes; Benzopyrans; Camphanes; Chemical Phenomena; Chemistry, Physical; Gas Chromatography-Mass Spectrometry; Humans; Naphthols; Odorants; Olfactory Nerve; Perception; Temperature; Volatilization

The compounds responsible for earthy and musty "off-flavors" in farm-raised channel catfish (Ictalurus punctatus) in the southeastern United States of America are geosmin and 2-methylisoborneol (MIB), respectively. These compounds are produced by certain species of cyanobacteria (blue-green algae) that grow in the aquaculture ponds. Previous research has focused on the species of cyanobacteria found in catfish ponds in west Mississippi (the leading region of catfish production in the USA), while the species responsible for earthy/musty off-flavors in catfish produced in the Mississippi-Alabama Blackland Prairie (MABP) region (second greatest region of catfish production) have not been described. We examined water samples from commercial catfish ponds in both regions to contrast the different types of cyanobacteria and assess the prevalence of geosmin and MIB. Results established that filamentous cyanobacteria are more common in west Mississippi compared to the MABP region. Also, the MIB-producing cyanobacterium Oscillatoria perornata is present in catfish ponds in both geographic locations, and geosmin is more prevalent in catfish ponds in the MABP region than in west Mississippi.

Topics: Alabama; Animals; Camphanes; Cyanobacteria; Food Contamination; Fresh Water; Ictaluridae; Mississippi; Naphthols; Taste; Water Microbiology; Water Pollutants, Chemical

Methylisoborneol (MIB) and geosmin are cyanobacterial metabolites that occur at nanograms per liter levels in surface water supplies and are responsible for many taste and odor complaints about the aesthetics of drinking water. This study evaluated three water supply reservoirs with bottom-release (hypolimnion) outlet structures in Arizona. MIB concentrations were always higher than geosmin concentrations, but both followed similar seasonal trends. MIB concentrations increased from spring to late summer, and stratified vertically with depth in the water column; the highest concentrations were always in the upper 10 m of the water column. Thermal destratification in the autumn increased MIB concentrations released from the outlet of reservoirs and impacted downstream utilities for several months. By winter of each year MIB concentrations were non-detectable. Mass balance analyses on MIB indicated that in-reservoir reactions were more important in changing MIB concentrations than conservative hydraulic "flushing" of the reservoir. Maximum net loss rates for MIB in the field (R(F,max)) were on the order of 0.23-1.7 ng/L-day, and biodegradation appeared more important than volatilization, photolysis or adsorption. Using lake water in laboratory experiments, bacterial biodegradation rates (R(L)) ranged from 0.5-1 ng/L-day and were comparable to R(F,max) values. Based upon these rates, MIB concentrations in a reservoir would decrease by approximately 30 ng/L over a period of 1 month. This was the magnitude change in MIB concentrations commonly observed after autumn thermal destratification of the reservoirs.

Topics: Arizona; Bacteria; Biodegradation, Environmental; Camphanes; Fresh Water; Naphthols; Odorants; Seasons; Taste; Water Pollutants, Chemical; Water Supply

Occurrence of the odours geosmin and 2-methylisoborneol (MIB) in freshwater environments indicates that odour-producing organisms are commonly occurring. In the present study, we assumed actinomycetes to be a major source of the odours. Seasonal concentrations of odours and abundance of Actinobacteria, which includes actinomycetes and other G+ and high GC bacteria, were determined in one oligotrophic and two eutrophic freshwater streams, as well as in aquacultures connected to these streams, in Denmark. Concentrations of geosmin and MIB ranged from 2 to 9 ng l(-1) and were lowest in the winter. Passage of stream water in the aquacultures increased the amount of geosmin and MIB by up to 55% and 110%, respectively. Densities of actinobacteria were determined by fluorescence in situ hybridization with catalyzed reporter deposition (CARD-FISH) technique and were found to make up from 4 to 38 x 10(7) cells l(-1), corresponding to 3-9% of the total bacterial populations. The lowest densities of actinobacteria occurred in the winter. Filamentous bacteria targeted by the FISH probe made up about 2.7-38% (average was 22%) of the actinobacteria and were expected to be actinomycetes. Combined microautoradiography and CARD-FISH demonstrated that 10-38% (incorporation of 3H-thymidine) and 41-65% (incorporation of 3H-leucine) of the actinobacteria were metabolically active. The proportion of active actinobacteria increased up to 2-fold during passage of stream water in the aquacultures, and up to 98% of the cells became active. Sequencing of 16S rRNA genes in 8 bacterial isolates with typical actinomycete morphology from the streams and ponds demonstrated that most of them belonged to the genus Streptomyces. The isolated actinomycetes produced geosmin at rates from 0.1 to 35 aggeosmin bacterium(-1)h(-1). MIB was produced at similar rates in 5 isolates, whereas no MIB was produced by three of the isolates. Addition of the odours to stream water demonstrated that indigenous stream bacteria were capable of reducing the odours, and that enrichment with LB medium stimulated the degradation. Our study shows that bacterial communities in freshwater include geosmin- and MIB-producing actinobacteria. However, the mechanisms controlling production as well as degradation of the odours in natural waters appear complex and require further research.

Topics: Actinobacteria; Animals; Aquaculture; Camphanes; Denmark; Fishes; Fresh Water; Naphthols; Nitrogen; Seasons

In this study, the advanced oxidation with ozone and UV radiation (with two low pressure UV lamps, at 254 and 185 nm wavelength) were experimented on a surface water in order to study the removal of two odorous compounds (geosmin and 2-methylisoborneol) and a pesticide (metolachlor), the influence on organic compounds (UV absorbance and THM precursors) and bromate formation. Different batch tests were performed with ozone concentration up to 10 mg/L, UV dose up to 14,000 J/m2 and a maximum contact time of 10 minutes. The main results show that metolachlor can be efficiently removed with ozone alone while for geosmin and MIB a complete removal can be obtained with the advanced oxidation of ozone (with concentration of 1.5-3 mg/L and contact time of 2-3 minutes) with UV radiation (with doses of 5,000-6,000 J/m2). As concerns the influence on the organic precursors, all the experimented processes show a medium removal of about 20-40% for UV absorbance and 15-30% for THMFP (trihalomethanes formation potential). As concerns bromate formation, the advanced oxidation of ozone/UV 254 nm shows a bromate formation that is about 40% lower with respect to conventional oxidation with ozone.

Topics: Acetamides; Camphanes; Disinfection; Herbicides; Naphthols; Odorants; Oxidants, Photochemical; Oxidation-Reduction; Ozone; Ultraviolet Rays; Waste Disposal, Fluid; Water Purification

Extractions for the analysis of geosmin and 2-methylisoborneol (MIB) were carried out on board a research vessel by extracting water samples in the collection bottles with dichloromethane. The extracts are stable and can be stored for up to two months with no apparent loss of analytes. Workup and analysis could be done at the rate 15-20 samples per week. Approximately 150 samples from Lake Ontario were analyzed in 2000 and 120 samples in 2001. Concentrations as low as 1 ng/L could be detected, but reliable determination was only attained above 5 ng/L (> 80% qualifier ion match within +/- 50%). Reproducibility between duplicates was generally better than 10%, and recovery of surrogate standards from reagent water averaged ca. 80% and from lake water ca. 60%. In early September, 2000, geosmin concentrations in Lake Ontario ranged from 1-13 ng/L and MIB from 1-31 ng/L. In 2001, the ranges were 1-47 and 1-56 ng/L for geosmin and MIB, respectively. Lowest concentrations occurred in the western and central regions and highest concentrations in the eastern region and St Lawrence River.

Topics: Camphanes; Chemistry Techniques, Analytical; Environmental Monitoring; Naphthols; Odorants; Sensitivity and Specificity; Ships; Water Supply

Water treatment plants in the US may operate under the assumption that chlorine masks earthy and musty odors from geosmin and 2-methylisoborneol (MIB) in drinking water. To test this hypothesis, we evaluated the effects of chlorine and chloramines on geosmin and MIB by two sensory analysis approaches--a statistical Pairwise Comparison Test, and Flavor Profile Analysis (FPA). All Pairwise Ranking test statistics were significant (p<0.05); we conclude that panelists can differentiate minor differences in geosmin and MIB concentrations in a Pairwise Comparison Test even in the presence of chlorine. FPA appeared to be more challenging in discerning subtle differences in concentrations of geosmin or MIB than did the Pairwise Comparison Test, and the presence of chlorine (0.5-20 mg/L) and chloramines (3-24 mg/L) confused the panelists (i.e showed a larger error in the intensity of response reported by the panel), but did not necessarily mask geosmin or MIB.

Topics: Camphanes; Chloramines; Chlorine; Humans; Naphthols; Odorants; Random Allocation; Sensitivity and Specificity; Taste; Water Purification; Water Supply

The ozonation of MIB and geosmin was studied in synthetic waters containing two natural organic material (NOM) fractions and sodium bicarbonate. The ozonation of both compounds was found to be affected by the character of the NOM fractions, with higher apparent rate constants observed in the fraction containing higher UV/visible absorbing properties. As the concentration of bicarbonate was increased, the destruction of both compounds decreased. MIB was found to be more resistant to ozonation than geosmin.

Topics: Camphanes; Environmental Monitoring; Naphthols; Oxidants, Photochemical; Ozone; Water Supply

The quality of drinking water is sometimes diminished by the presence of certain compounds that can impart particular tastes or odours. One of the most common and problematic types of taste and odour is the earthy/musty odour produced by geosmin (trans-1, 10-dimethyl-trans-9-decalol) and MIB (2-methylisoborneol). Taste and odour treatment processes including powdered activated carbon, and oxidation using chlorine, chloramines, potassium permanganate, and sometimes even ozone are largely ineffective for reducing these compounds to below their odour threshold concentration levels. Ozonation followed by biological filtration, however, has the potential to provide effective treatment. Ozone provides partial removal of geosmin and MIB but also creates other compounds more amenable to biodegradation and potentially undesirable biological instability. Subsequent biofiltration can remove residual geosmin and MIB in addition to removing these other biodegradable compounds. Bench scale experiments were conducted using two parallel filter columns containing fresh and exhausted granular activated carbon (GAC) media and sand. Source water consisted of dechlorinated tap water to which geosmin and MIB were added, as well as, a cocktail of easily biodegradable organic matter (i.e. typical ozonation by-products) in order to simulate water that had been subjected to ozonation prior to filtration. Using fresh GAC, total removals of geosmin ranged from 76 to 100% and total MIB removals ranged from 47% to 100%. The exhausted GAC initially removed less geosmin and MIB but removals increased over time. Overall the results of these experiments are encouraging for the use of biofiltration following ozonation as a means of geosmin and MIB removal. These results provide important information with respect to the role biofilters play during their startup phase in the reduction of these particular compounds. In addition, the results demonstrate the potential biofilters have in responding to transient geosmin and MIB episodes.

Topics: Biodegradation, Environmental; Camphanes; Carbon; Filtration; Naphthols; Odorants; Particle Size; Quality Control; Water Purification

Massive blooms of blue-green algae in reservoirs produce the musty-earthy taste and odor, which are caused by compounds such as 2-MIB and geosmin. 2-MIB and geosmin are rarely removed by conventional water treatment. Their presence in the drinking water, even at low levels (ng/L), can be detected and it creates consumer complaints. So those concentrations have to be controlled as low as possible in the drinking water. The removals by oxidation (O3, Cl2, ClO2) and adsorption (PAC, filter/adsorber) were studied at laboratory and pilot plant (50 m3/d) to select suitable 2-MIB and geosmin treatment processes. The following conclusions were derived from the study. Both of the threshold odor levels for 2-MIB and geosmin appeared to be 30 ng/L as a consequence of a lab test. For any given PAC dosage in a jar-test, removal efficiencies of 2-MIB and geosmin were increased in proportion to PAC dosage and were independent of their initial concentration in raw water for the tested PAC dosages. In comparison of geosmin with 2-MIB, the adsorption efficiency of geosmin by PAC was superior to that of 2-MIB. The required PAC dosages to control below the threshold odor level were 30 mg/L for geosmin and 50 mg/L for 2-MIB at 100 ng/L of initial concentration. Removal efficiencies of odor materials by Cl2, ClO2, and O3 were very weak under the limited dosage (1.5 mg/L), however increased ozone dosage (3.8 mg O3/L) showed high removal efficiency (84.8% for 2-MIB) at contact time 6.4 minutes. According to the initial concentrations of 2-MIB and geosmin, their removal efficiencies by filter/adsorber differed from 25.7% to 88.4%. For all those, however, remaining concentrations of target materials in finished waters were maintained below 30 ng/L. The longer run-time given for the filter/adsorber, the higher the effluent concentration generated. So it is necessary that the run-time of the filter/adsorber be decreased, when 2-MIB or geosmin occurs in raw water.

Topics: Adsorption; Camphanes; Cyanobacteria; Eutrophication; Filtration; Naphthols; Odorants; Oxidation-Reduction; Taste; Water Purification

The effect of chlorine on the analysis of three organic compounds (geosmin, 2-methylisoborneol (2-MIB) and methyl tert-butyl ether (MTBE)) in drinking water is elucidated. Three fibers for solid-phase microextraction (SPME) were employed for the extraction of the organic compounds from drinking water samples with and without free residual chlorine present. A gas chromatograph coupled with a mass spectrometer was used to analyze the compounds trapped by the fibers. The presence of chlorine substantially reduces the observed geosmin, 2-MIB, and MTBE concentrations. Depending on the analyte and chlorine concentrations, an experimental error of 10-70% may be observed due to the presence of free residual chlorine. The impact is larger for lower organic compound concentrations, and under higher residual chlorine conditions. To counteract the effect from residual chlorine, sodium thiosulfate was used to dechlorinate the water. After dechlorination the experimental error was less than 10%, suggesting that dechlorination is necessary when applying SPME for the extraction of organic compounds from chlorinated drinking water.

Topics: Camphanes; Carcinogens; Chlorine Compounds; Disinfectants; Environmental Monitoring; Naphthols; Odorants; Reproducibility of Results; Solvents; Water Pollutants, Chemical; Water Purification; Water Supply

Pulp and paper mills are well known for their sharp, sulphurous stack emissions, but the secondary treatment units also can be significant contributors to local odour. This study investigated the source(s) of earthy/musty emissions from a mixed hardwood pulp mill in response to a high local odour. Samples from five sites in the mill over five months were analyzed for earthy/musty volatile organic compounds (VOCs), examined microscopically, and plated for bacteria and moulds. In all cases, activated sludge showed substantial geosmin levels and to a lesser extent 2-methylisoborneol (MIB) at 2000-9000 times their odour threshold concentrations (OTCs). These VOCs were lower or absent upstream and downstream, suggesting that they were produced within the bioreactor. Geosmin and MIB were highest in late summer and declined over winter, and correlated with different operating parameters. Geosmin was most closely coupled with temperature and MIB with nitrogen uptake. Cyanobacteria were present in all sludge samples, but actinomycetes were not found. Gram-negative bacteria and one fungal species isolated from the bioreactor and secondary outfall tested negative for geosmin or MIB. We conclude: (i) geosmin and MIB contribute significantly to airborne odours from this mill, but are diluted below OTC levels at the river; (ii) these VOCs are generated by biota in the activated sludge; and (iii) cyanobacteria are likely primary source(s). The growth of cyanobacteria in activated sludge represents a loss of energy to the heterotrophic population; thus earthy/musty odours may represent a diagnostic for less than optimal conditions.

Topics: Actinobacteria; Bioreactors; Camphanes; Cyanobacteria; Environmental Monitoring; Industrial Waste; Naphthols; Odorants; Paper; Seasons; Waste Disposal, Fluid

The off-flavor compounds 2-methylisoborneol (MIB), geosmin, 2,4,6-trichloroanisole, 2,3,6-trichloroanisole, 2,3,4-trichloroanisole, and 2,4,6-tribromoanisole were analyzed in water samples by stir bar sorptive extraction (SBSE) followed by on-line thermal desorption (TD) capillary GC/MS. Quantification was performed using the MS in the single-ion-monitoring mode (SIM) with 2,4,6-trichloroanisole-D(5 )as internal standard. Quantification limits are 0.1-0.2 ng L(-1) for the haloanisoles, 0.5 ng L(-1) for geosmin, and 1 ng L(-1) for MIB. The relative standard deviations at the quantification limit ranged from 7 to 14.6%. SBSE recovery was evaluated by spiking real water samples and varied from 87 to 117%. More than twenty samples per day can be analyzed by SBSE-TD-capillary GC-MS. The same technique in combination with olfactometry was used to elucidate unknown odorous compounds in water samples.

Topics: Anisoles; Calibration; Camphanes; Gas Chromatography-Mass Spectrometry; Naphthols; Odorants; Reproducibility of Results; Sensitivity and Specificity; Taste; Water Pollutants, Chemical; Water Supply

Geosmin and 2-methylisoborneol-compounds responsible for the musty-earthy off-odor of wheat grain, were isolated by SPME and analyzed by GC-MS. Carboxen/PDMS/DVB fiber coating was selected because of its highest extraction efficiency. Concentrations of geosmin and 2-methylisoborneol as low as 0.001 microg/kg were detected in SIM mode using ion trap mass spectrometer. Apart from GC-MS determination of geosmin and 2-methylisoborneol, various methods for evaluating the musty-earthy off-odor caused by these compounds in wheat grain are presented. Sensory profile analysis differentiated wheat grain into sound and off-flavored, but the method was tedious. Similar groupings, however, were obtained using more rapid methods such as comparison of volatile profiles using SPME-fast GC with PCA projection of data and metal oxide (MOS) based electronic nose.

Topics: Camphanes; Gas Chromatography-Mass Spectrometry; Humans; Naphthols; Odorants; Seeds; Smell; Triticum; Volatilization

Tastes and odours (T&Os) are a major concern in drinking water as they are not efficiently removed by conventional water treatment. Ozonation has been effective for their destruction in some studies. However, the natural organic matter (NOM) in waters can affect the ozonation process and subsequently affect the destruction of T&Os. Five NOM fractions were isolated and ozonated in synthetic waters. The fraction containing the more highly coloured, higher molecular weight compounds exhibited the highest ozone (O3) demand, whereas the low aromatic fraction exhibited the lowest O3 demand. The character of the NOM fractions influenced the ozonation of MIB and geosmin. The destruction of MIB and geosmin was significantly higher in the fraction with the highest colour and UV/visible absorbance at all O3 doses. The destruction of the compounds in the other fractions showed the same trends, increasing MIB and geosmin destruction with increasing UV/visible absorbing character of the NOM. MIB was also ozonated in two real waters. with results showing a competing effect between NOM concentration and NOM character. The O3 reaction time was shown to be important for the destruction of both compounds.

Topics: Camphanes; Naphthols; Odorants; Organic Chemicals; Oxidants, Photochemical; Ozone; Taste; Water Supply

Blooms of blue-green algae in reservoirs often produce the musty-earthy taste and odour algal metabolites 2-methylisoborneol (MIB) and geosmin. MIB and geosmin are not removed by conventional water treatment and their presence in the distribution system, even at low ng L-1 levels, can result in consumer complaints. Powdered activated carbon (PAC) can effectively remove MIB and geosmin when the correct dose is applied. The homogeneous surface diffusion model (HSDM) was used to predict PAC doses required to reduce MIB and geosmin concentrations to below 10 ng L-1 at four water treatment plants in Adelaide, South Australia. In jar tests, undertaken under treatment plant conditions, the predicted doses were found to produce water of the desired quality in three of the four waters. The poor predictions found in the fourth water, which had a considerably higher turbidity, were attributed to the incorporation of PAC in a larger, denser floc, leading to a reduced effective contact time of the adsorbent. It was found that higher doses of PAC were required for both compounds to produce acceptable quality water when turbidities rose above 26 NTU.

Topics: Adsorption; Camphanes; Charcoal; Diffusion; Gas Chromatography-Mass Spectrometry; Naphthols; Odorants; South Australia; Spectrophotometry; Surface Properties; Water Purification

Topics: Animals; Camphanes; Cell Separation; Cell Survival; Cells, Cultured; Cytochrome P-450 CYP1A1; DNA; DNA Damage; Fresh Water; Hydrogen Peroxide; Liver; Naphthols; No-Observed-Adverse-Effect Level; Oncorhynchus mykiss; Toxicity Tests; Vitellogenins; Water Pollutants, Chemical

An alternative technique for the isolation and concentration of odorous compounds found in potable water is described. The method currently employed by water authorities is closed-loop stripping with the collection of these substances on a small activated carbon filter. The compounds of interest are then extracted from the carbon using a suitable solvent. The authors offer a multichannel silicone rubber trap as an alternative to the carbon filter. The absorbed compounds are thermally desorbed from the trap, directly on to the gas chromatographic column for analysis by GC-MS, thereby eliminating the solvent extraction step required by the carbon filter. The multichannel silicone rubber trap, producing equivalent results, offers a number of advantages over the carbon filter.

Topics: Camphanes; Gas Chromatography-Mass Spectrometry; Naphthols; Odorants; Water

The semivolatile cyclic alcohols 2-methylisoborneol (MIB) and geosmin (GSM) impart muddy or musty flavors to water and food products. A rapid quantitative analytical technique has been developed whereby microwave distillation is used to remove the volatile organic compounds from a lipophilic matrix into an aqueous matrix. Solid-phase microextraction (MD-SPME) is then used to extract and concentrate the analytes, which are then desorbed in the injection port of a gas chromatograph/mass spectrometer (GC/MS) for analysis. Limits of detection are 0.01 microg/kg and limits of quantification are 0.1 microg/kg. MD-SPME is comparable in precision, requires no solvents, and is faster than current methods of analysis. This methodology allows detection of MIB and GSM at concentrations below human sensory thresholds in fish tissue.

Topics: Animals; Camphanes; Catfishes; Fish Products; Gas Chromatography-Mass Spectrometry; Naphthols

A method for the determination of geosmin and 2-methylisoborneol (MIB) in water by solid-phase microextraction (SPME) is presented. Various SPME fibre chemistries have been compared for their efficiency in extracting MIB from water. Extraction conditions including the extraction time and temperature have been optimised. A 30 ml water sample is extracted for 20 min at 60 degrees C using a divinylbenzene fibre, and the extract analysed by gas chromatography with ion-trap mass spectrometry detection. d5-Geosmin and d3-MIB are added as internal standards to compensate for any variability in the SPME process which is not carried out to equilibrium. Chemical ionisation, using acetonitrile as the reagent gas, was found to give superior sensitivity to electron impact ionisation (EI) for the detection of MIB. EI was used as the ionisation mode for detection of geosmin. The method shows good linearity over the concentration range 5-40 ng l-1 and gives detection limits of 1 ng l-1 for both geosmin and MIB. Recovery (93-110%) and precision (3-12%) over this concentration range, for both raw and treated drinking waters, are comparable to currently employed methods such as closed-loop stripping analysis (CLSA). The method offers the advantage of being simple to use, with much shorter analysis times in comparison to CLSA.

Topics: Camphanes; Gas Chromatography-Mass Spectrometry; Naphthols; Odorants; Water; Water Pollutants

Many reservoirs for water supply have been troubled with earthy-musty odour compounds--2-metylisoborneol (2-MIB) and geosmin. Both of these compounds are terpenoid and related to the metabolite of L-methionine. An experiment using [CD3]methionine and [14CH3]methionine showed that the C-2 methyl group in 2-MIB originate from L-methionine. In the incubation experiment with 10-1000 mg/l of L-methionine, 2-MIB and geosmin appeared in the earlier stages, in greater amounts than in the control. The maximum production of 2-MIB and geosmin increased considerably in the experiments with 10 and 100 mg/l of L-methionine. The effective time for L-methionine addition was after 1 d. Additions after 3 and 5 d were similar to the control. In the incubation experiment with 10-1000 mg/l of folic acid, 2-MIB and geosmin increased only during the 1000 mg/l addition. There seems to be little doubt that L-methionine takes part in the metabolism of 2-MIB and geosmin.

Topics: Camphanes; Folic Acid; Methionine; Naphthols; Odorants; Streptomyces; Water Microbiology

A simple and rapid method for the extraction and quantification of geosmin and 2-methylisoborneol is described. Using methylene chloride extraction and gas chromatography, the procedure eliminates costly stripping devices. Recovery efficiency of the procedure is approximately 65% with a sensitivity equal to the human threshold for these two important off-flavor compounds.

Topics: Actinomyces; Bacteria; Camphanes; Culture Media; Drug Stability; Eukaryota; Fresh Water; Gas Chromatography-Mass Spectrometry; Naphthols; Streptomyces; Water

Topics: Camphanes; Cyanobacteria; Hydrocarbons; Naphthols; Odorants

Topics: Acetates; Camphanes; Naphthols; Odorants; Streptomyces