Anthropogenic nexus on organochlorine pesticide pollution: a case study with Tamiraparani river basin, South India.

The levels of 17 organochlorine pesticides residues (OCPs) in surface water and sediments from Tamiraparani river basin, South India were investigated to evaluate their potential pollution and risk impacts. A total of 96 surface water and sediment samples at 12 sampling stations were collected along the river in four seasons during 2008-2009. The ΣOCP concentrations in surface water and sediments were in the range of 0.1 to 79.9 ng l(-1) and 0.12 to 3,938.7 ng g(-1) dry weight (dw), respectively. Among the OCPs, the levels of dichlorodiphenyltrichloroethanes (DDTs), aldrin, dieldrin, cis-chlordane, trans-chlordane, and mirex were dominant in the sediments. The dominant OCPs in water samples are heptachlor, o,p'-DDE, dieldrin, o,p'-DDD, and mirex, which show different source of contamination pattern among sampling seasons. The distribution pattern of DDTs, hexachlorocyclohexane, and other OCPs in the present study shows heterogenic nature of nonpoint source of pollution. Notable contamination of water and sediment sample that was observed in upstream (S2) 58 ng l(-1) and downstream (S11) 1,693 ng g(-1) dw explains agricultural and municipal outfalls, whereas frequent damming effect reduces the concentration level in the midstream. The overall spatial-temporal distribution pattern of ΣOCP residues are illustrated by GIS package.