The ecotoxicological implications and contamination profile of organochlorine pesticides (OCPs), organophosphorus pesticides (OPPs), and heavy metals, in Tuticorin, Southeast coast of India

This research work examined the sources, risks and seasonal variations in the concentrations of organochlorine pesticides (OCPs), organophosphorus pesticides (OPPs), pyrethroids, and heavy metals in the Tuticorin coast, Southeast Coast of India. The concentrations of pesticides and heavy metal residues were measured using GC/MS and AAS. Pesticide residue concentrations in water ranged from 0.001 to 0.067 ng/ml and in sediment from 0.001 to 31.43 ng/g, all falling under the regulatory limits set by WHO and USEPA. The analysis suggested the possibility of local lindane use as the origin for Hexachlorocyclohexane (HCH) residues and the recent introduction of dichloro-diphenyl-trichloroethane (DDT) residue. Metal concentrations were in the order Zn> Fe> Cu > Ni > Mn > Cr > Pb > Cd > Se > Hg for water, and Fe > Mn > Zn> Cr > Cu > Pb > Ni > Cd > Hg > Se for sediment. Metals had higher concentrations in sediments during the post-monsoon season and their concentration decreased with increasing offshore distance. The estuary exhibited severe enrichment of Zn and Hg, while Cd was highly concentrated in the port, reflecting pollution levels ranging from 'unpolluted' to 'moderately polluted'. In the estuary, sediment properties significantly impact the spatial distribution of pollutants, but the correlation is less pronounced in the port and harbor because of varying anthropogenic sources. The results of this study will aid local authorities in safeguarding significant water resources.