microcystin and beta-cyclocitral

The distributions of cyanobacterial bioactive and odorous metabolites were investigated in the fifth largest lake in China in the fishing season 2012. The highest microcystins (MCs) concentration in water reached 3.4 µg L(-1). A high β-ionone concentration reached 35.6 ng L(-1) in water. Mean MCs concentration in muscle was highest in omnivorous Carassius auratus (20.9 ng g(-1) dry weight), followed by phytoplanktivorous Hypophthalmichthys molitrix (7.4 ng g(-1) DW) and carnivorous Coilia ectenes (3.0 ng g(-1) DW). The maximum off-flavor concentrations kept 9.5 µg kg(-1) wet weight for geosmin (C. auratus), 5.5 µg kg(-1) WW for β-cyclocitral (C. ectenes) and 25.5 µg kg(-1) WW for β-ionone (C. ectenes). Positive correlation was found between the off-flavor and fat contents in C. ectenes. To be different with MCs, β-cyclocitral content was highest in fore-gut contents (87.6 µg kg(-1) WW) in H. molitrix. It should not be reliable to predict odorous compounds level in fish muscle by only measuring the off-flavor in lake water only.

Topics: Aldehydes; Animals; China; Cyanobacteria; Diterpenes; Environmental Monitoring; Feeding Behavior; Fishes; Lakes; Microcystins; Norisoprenoids; Odorants; Risk Adjustment; Seasons

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