Accumulation of organochlorine pesticide (OCP) residues in surface water and sediment from the İznik Lake in Turkey

This study was carried out to evaluate organochlorinated pesticide (OCPs) concentrations in the water column and sediments of İznik Lake. Water samples and sediment were collected in different regions (six sampling sites) of the lake between January and December 2019 and tested for OCPs by gas chromatography-mass spectrometry (GC–MS). The results revealed that OCP residues throughout the sites varied depending on the anthropogenic activities of the region. OCPs detected in surface waters ranged from 0.01 to 60.80 μg/L and sediments from 0.06 to 14.21 ng/g dw. Endrin ketone, endrin aldehyde, endosulfan II, endrin, heptachlor epoxy, beta-BHC, gamma-BHC, ppDDD, and ppDDT concentrations exceeded the maximum residue limits indicated by the World Health Organization (WHO) for surface waters. Of the 18 analyzed OCP components, 17 were detected in sediment samples, and it was noted that they reached the highest concentration in summer. The presence of relatively high OCP levels according to WHO regulations in the waters of İznik Lake, around which agricultural activities have been increasing rapidly in recent years, is a serious concern, and therefore, appropriate actions should be taken into consideration by the regulatory authorities.