Abstract

In this study, the levels of organochlorine (OC) pesticide residues in Lake Tashk have been investigated using water, sediment and fish (carp) samples as a case study to find out the extent of pesticide contamination and accumulation in the lake. Six OC pesticides namely DDT, DDE, lindane, endosulfan, heptachlor and chlordane were analyzed in four sites at four seasons. Water samples were processed using a liquid–liquid extraction technique and gas chromatograph equipped with electron capture detector (GC-ECD). Soxhlet extraction was used for fish and sediment samples followed by clean up and gas chromatograph. DDE was the predominant residue in all the samples analyzed, at the mean concentrations of 0.075 ppb, 8.750 ppb and 4.446 ppb in water, sediment and fish samples, respectively. The lowest levels of OC pesticides were related to heptachlor and chlordane which none of them were found in water samples. Gonban and Midstream sites had the highest and the lowest concentrations of OC pesticides, respectively.

Abstract

Sample preparation can be used in biology and ecology for gas chromatographic determination of organochlorine pesticides (OCP), namely, α-, β- and γ-isomers of hexachlorocyclohexane (HCH), dichlorodiphenyltrichloroethane (DDT) and its metabolites dichlorodiphenyldichloroethane (DDD) and dichlorodiphenyldichloroethylene (DDE) in various aquatic organisms (molluscs, fish, birds and mammals) containing lipids (because organochlorine pesticides are lipophilic) in the internal organs and tissues, fat, skin and feather cover. The method is easy to implement and economically profitable, it can be used in laboratories without special extraction equipment, as well as in the field, with a minimum set of glassware and reagents. The result of this process is an increase of efficiency and precision of research through a more complete extraction of pesticides chemically bonded with lipids using n -hexane and a reduction of the number of steps needed for the extraction and purification of co-extrusive substances with concentrated sulphuric acid.

Abstract

Organochlorine pesticides are persistent toxic substances of anthropogenic origin that affect biota. Hexachlorocyclohexane (HCH) isomers (α-, β-, and γ-), DDT and its metabolites (DDD and DDE) were detected in five individuals of fulmars Fulmarus glacialis Linnaeus, 1761 from the coast of Eastern Kamchatka and the Kuril Islands. The average amount of HCH isomers in the organs of fulmars ranged from 608 ± 177 ng/g lipids in the total homogenate of the organs to 2093 ± 264 ng/g lipids in the feathers with skin. The average range of the amounts of DDT and its metabolites was from 3606 ± 333 ng/g lipids in the feathers with skin to 4076 ± 1624 ng/g lipids in the feathers. The results are discussed.