Abstract
This study aims at preliminary analysis of pesticide pollution of western backwater at Karachi coast. Karachi coastal area is known for its ecological importance. The coastal area receives >350 MGD of wastewater through Lyari and Malir rivers. The effluent of Lyari and Malir Rivers often carries agriculture runoff from the nearby agriculture fields of these Rivers. Samples were collected from 12 different sites at the western backwater of Karachi coast for the occurrence and distribution of commercially available pesticides. The pesticides used in the present study were OCPs (organochlorine pesticides) including aldrin, dieldrin, endrin, endosulfan, Hexachlorobezene (HCB), HCH (Hexachlorocyclohexane), heptachlor, Methoxychlor, p,p′-DDT and tanschlordane. Pesticides were determined through gas chromatographic technique. The highest mean concentration was that of Endosulfan (0.63 µg/l) while lowest concentration was of Endrin (0.046 µg/l). The residual pesticide concentrations were in the order Endosulfan>Heptachlor> DDT> HCH> Dieldrin> Aldrin> Transchlordane> Methoxychlor> Endrin. HCB was not detected in any sample. It noteworthy that DDT was also found in the samples that remains persistent in the environment for decades. The continuous accumulation of pesticide residues at Karachi coast may lead to serious health and environmental implications that cannot be ruled out. The bacterial load of total coliform and faecal coliform was also markedly high. Therefore, it is suggested that strict policy guidelines be enforced to restrict the pollution of this water body that is so closed to human settlements.
