Organochlorine insecticide residues in agricultural soils of the indo-gangetic plain

Multiple residues of organochlorine insecticides were monitored in the agricultural fields near Farrukhabad in the vicinity of the River Ganga in northern India for one year (1991–1992). Almost all soil samples were found to be contaminated with residues of hexachlorocylohexane (HCH) and dichlorodiphenyl-trichloroethane (DDT). Residues of aldrin and endosulfan were also detected in a large number of samples. Heptachlor residues were scarcely detected. Alpha-HCH, pp-DDT and alpha-endosulfan were found to dominate over the other isomers/metabolites of HCH, DDT and endosulfan, respectively. The average concentration of dieldrin was more than that of aldrin. The concentrations of residues progressively increased up to a depth of 1 m.