Department of Zoology, University of Delhi, Delhi-110 007, India
Online published on 3 November, 2011.
Fate of parathion in soil was studied for two years under field conditions in sub-tropical climate of Delhi. Parathion dissipated rapidly within 3 days of treatment of the soil with C and unlabelled parathion. The residues were reduced to about l/3rd of the amount applied. The dissipation curve was biphasic with a very rapid dissipation of parathion during the first 7 days followed by a slow phase. About 84% of the total parathion was lost 50 days after treatment The half life of parathion was 64.5 days. The total residues at zero-time were almost all extractable and no bound residues (unextractable) were detected. The extractable residues of parathion consisted of parathion, 4-aminophenoi, p-nitrophenol and paraoxon. At 14 days, the bound residues are almost double of the extractable residues. Gradually the bound residues accounted for almost all the residues detected. One and half year later almost no residues of parathion were detected in the top 10 cm soil. About 1.5%parathion leached upto 20 cm depth in sandy loam soil in one year as compared to 0.66% after one and half year.
