Monitoring of water and sediment for pesticide residues and their bioaccumulation in fish of East Kolkata Wetland

Water, sediment and fish samples of East Kolkata wetland were monitored using GC-ECD for residues of organochlorinated (OC) and synthetic pyrethroid (SP) pesticides. Among the OCs, HCH (α, β,  and ) were detected in water (0.02 – 0.1 μg/L) and in Cyprinus carpio (1.23-8.9 μg/kg) but none in sediments or in Oreochromis mossambicus. In Cirrhinus mrigala only α-HCH was recorded. In case of DDTs, pp DDE was commonly detected in sediments and fish species but not in water. Prevalence of pp DDE over pp DDT might be indicative of less fresh use of the pesticide and degradation of previously used material to the stable metabolite. Average concentration of DDT in three fish species ranged between 11.1413.35 μg/kg. Endosulfan residues were detected as either α or β isomer and metabolite endosulfan sulfate except in C. carpio where all these three were present. Endosulfan in fish flesh varied from 1.91-23.72 μg/kg. Dicofol was found in water and also in fish (38.35 to 80.47 μg/kg). SPs were absent except in one sample of C. mrigala which contained cyfluthrin. Though residues of certain pesticides were detected in fish, but their concentrations were much below the tolerance limit and the hazard index was very low.