Contamination of organochlorine pesticides in sediments from the Arabian Sea along the west coast of India

The levels of contamination of various organochlorine pesticides such as HCHs, DDTs, aldrin, dieldrin and endrin were determined in marine and estuarine sediments along the west coast of India. The concentration of various pesticides in sediments from the mouth of different estuaries along the coast were in the range of 0.85–7.87 ng/g (t-HCH), 0.10–0.26 ng/g (aldrin), 0.70–3.33 ng/g (dieldrin), 0.42–0.95 ng/g (endrin) and 1.47–25.17 ng/g (t-DDT), whereas those in the offshore sediments in the range of 0.10–6.20 ng/g (t-HCH), 0.09–0.26 ng/g (aldrin), 0.20–1.41 ng/g (dieldrin), 0.39–0.78 ng/g (endrin) and 1.14–17.59 ng/g (t-DDT). Among the organochlorine pesticides, t-HCH and t-DDT were most dominant in both the estuarine and offshore sediments. The highest concentration of t-HCH was estimated at station 8 near the mouth of Netravati estuary (7.87 ng/g) while that of t-DDT at station 7 near the mouth of Kali estuary (21.16 ng/g). Among the cyclodiene compounds, aldrin was in abundance in most of the sediments whereas dieldrin and endrin could be detected at the mouth of Zuari, Damanganga, Diu, Cannanore and Ponnani estuaries along the west coast of India. The mean concentrations of t-HCH, aldrin, dieldrin, endrin and t-DDT increased in the estuarine sediments by factors of 2.95, 1.13, 3.60, 2.26 and 2.18, respectively, with respect to those in the offshore sediment. The most predominant metabolites of DDT and HCH in both the estuarine and the offshore sediments were found to be ppʹ-DDE and α-HCH respectively.