Abstract
The present study investigated the presence and potent source of pesticides and specific pesticide bearing effluent release points on the River Ravi, between the Shahdara and Balloki Headworks. Pakistan has banned the use of organochlorine and nitrogen containing pesticides, yet no attention has been paid to the continuous monitoring and assessment of these banned pesticides to make sure that they are not being used in practice. Levels of selected organochlorine and nitrogen containing pesticide residues were assessed in water collected from 18 sampling sites on the River Ravi and its tributaries using a gas chromatograph equipped with an electron capture detector (GC-ECD). All water samples were found to be contaminated with varying concentrations of pesticide residues. However, levels of pesticides were below the tolerance limits suggested in national and international standards. Pesticide concentrations in the water of river sites ranged from 0.034 to 0.045 mu g/L for DDT, 0.033 to 0.046 mu g/L for DDE, 0.108 to 0.123 mu g/L for endosulfan and 0.028 to 0.040 mu g/L for carbofuran. In tributaries, pesticide concentrations ranged from 0.0468 to 0.0685 mu g/L for DDT, 0.0390 to 0.0637 mu g/L for DDE, 0.111 to 0.147 mu g/L for endosulfan and 0.0396 to 0.0631 mu g/L for carbofuran. The results show pesticide concentrations in river water in the order: endosulfan > DDE > DDT > carbofuran. Pesticide concentrations in tributary waters decreased in the order: endosulfan > DDT> DDE > carbofuran. After Degh Fall and After Hudiara Nulla Fall river sampling sites were severely contaminated while, among the tributaries, Degh Fall and Hudiara Drain were severely contaminated with DDT, DDE, endosulfan and carbofuran. Constant monitoring programs should to be initiated to reform the present situation.