POLLUTION POTENTIAL OF SELECTED PESTICIDES IN SOILS

Pollution potential and profile distribution of pesticide residues of atrazine, metolachlor, and cyanazine and atrazine metabolites namely d eethylatrazine, deisopropylatrazine and hydroxyatrazine, were studied in a clay loam soil. The field (70 ha) was treated with atraxine for t hree years (1985-1987) at the rate of 2.22 kg/ha and with metolachlor (dual) and cyanaxine (bladex) at the rate of 1.24 and 2.47 kg/ha, resp ectively in 1987 and 1988. Soil samples were collected, four years aft er application of the herbicides, at each intersection of a grid (100 m X 100 m) and analyzed for pesticide residues. The results showed tha t the soil contained the pesticides residues and metabolites in suffic ient quantities which potentially contaminate the surface and ground w aters with these residues. Atrazine and metolachlor were detected in a lmost all surface samples, whereas cyanaxine was present in only 50 % of the samples. Metolachlor residues were found to be highest among th e herbicides studied with an average 103 mug/kg of soil. Atrazine and cyanazine residues concentrations averaged 16 and 10 mug/kg of soil re spectively. The concentration of deethylatrazine residues averaged 3.7 0 mug/kg of soil and that of deisopropylatrazine averaged 0.74 mug/kg. Hydroxyatrazine residues averaged . 5.41 mug/kg of soil and were high est among the metabolites studied. The distribution down the soil prof ile was found to be irregular for all the three herbicides and the met abolites investigated.