azoxystrobin and isoproturon

Pesticides residues in aquatic ecosystems are an environmental concern which requires efficient analytical methods. In this study, we proposed a generic method for the quantification of 13 pesticides (azoxystrobin, clomazone, diflufenican, dimethachlor, carbendazim, iprodion, isoproturon, mesosulfuron-methyl, metazachlor, napropamid, quizalofop and thifensulfuron-methyl) in three environmental matrices. Pesticides from water were extracted using a solid phase extraction system and a single solid-liquid extraction method was optimized for sediment and fish muscle, followed by a unique analysis by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Limits of quantification were below 5 ng L(-1) for water (except for fluroxypyr and iprodion) and ranged between 0.1 ng g(-1) and 57.7 ng g(-1) for sediments and regarding fish, were below 1 ng g(-1) for 8 molecules and were determined between 5 and 49 ng g(-1) for the 5 other compounds. This method was finally used as a new routine practice for environmental research.

Topics: Acetamides; Aminoimidazole Carboxamide; Animals; Benzimidazoles; Carbamates; Chemical Fractionation; Chromatography, Liquid; Environmental Monitoring; Fishes; Geologic Sediments; Hydantoins; Isoxazoles; Methacrylates; Muscles; Naphthalenes; Niacinamide; Oxazolidinones; Pesticide Residues; Pesticides; Phenylurea Compounds; Propionates; Pyrimidines; Quinoxalines; Reproducibility of Results; Solid Phase Extraction; Strobilurins; Sulfonylurea Compounds; Tandem Mass Spectrometry; Thiophenes; Water Pollutants, Chemical

The impacts of the fungicides azoxystrobin, tebuconazole and chlorothalonil on microbial properties were investigated in soils with identical mineralogical composition, but possessing contrasting microbial populations and organic matter contents arising from different management histories. Degradation of all pesticides was fastest in the high OM/biomass soil, with tebuconazole the most persistent compound, and chlorothalonil the most readily degraded. Pesticide sorption distribution coefficient (K(d)) did not differ significantly between the soils. Chlorothalonil had the highest K(d) (97.3) but K(d) for azoxystrobin and tebuconazole were similar (13.9 and 12.4, respectively). None of the fungicides affected microbial biomass in either soil. However, all fungicides significantly reduced dehydrogenase activity to varying extents in the low OM/biomass soil, but not in the high OM/biomass soil. The mineralization of subsequent applications of herbicides, which represents a narrow niche soil process was generally reduced in both soils by azoxystrobin and chlorothalonil. 16S rRNA-PCR denaturing gradient gel electrophoresis (DGGE) indicated that none of the fungicides affected bacterial community structure. 18S rRNA PCR-DGGE analysis revealed that a small number of eukaryote bands were absent in certain fungicide treatments, with each band being specific to a single fungicide-soil combination. Sequencing indicated these represented protozoa and fungi. Impacts on the specific eukaryote DGGE bands showed no relationship to the extent to which pesticides impacted dehydrogenase or catabolism of herbicides.

Topics: Animals; Bacteria; Benzothiadiazines; Biodegradation, Environmental; DNA; Eukaryota; Fungi; Fungicides, Industrial; Herbicides; Methacrylates; Nematoda; Nitriles; Oxidoreductases; Phenylurea Compounds; Pyrimidines; RNA, Ribosomal, 18S; Soil Microbiology; Soil Pollutants; Strobilurins; Triazoles

The extent of within field variability in the degradation rate of the pesticides isoproturon, azoxystrobin and diflufenican, and the role of intrinsic soil factors and technical errors in contributing to the variability, was investigated in sites on sandy-loam and clay-loam. At each site, 40 topsoil samples were taken from a 160 x 60 m area, and pesticides applied in the laboratory. Time to 25% dissipation (DT25) ranged between 13 and 61 weeks for diflufenican, 5.6 and 17.2 weeks for azoxystrobin, and 0.3 and 12.5 weeks for isoproturon. Variability in DT25 was higher in the sandy-loam in which there was also greatest variability in soil chemical and microbial properties. Technical error associated with pesticide extraction, analysis and lack of model fit during derivation of DT25 accounted for between 5.3 and 25.8% of the variability for isoproturon and azoxystrobin, but could account for almost all the variability for diflufenican. Azoxystrobin DT25, sorption and pH were significantly correlated.

Topics: Animals; Biodegradation, Environmental; England; Environmental Monitoring; Hydrogen-Ion Concentration; Methacrylates; Niacinamide; Pesticides; Phenylurea Compounds; Pyrimidines; Soil; Soil Microbiology; Soil Pollutants; Strobilurins; Time Factors; Water Movements