Persistence, metabolism and binding of p,p'-DDT in soil in Delhi, India
Abstract The persistence, metabolism and binding of 14C‐p,p'‐DDT in soil were studied for two years under field sub‐tropical conditions in Delhi, India. Two experiments were conducted at initial concentrations of 3.7 and 12.8 ppm and it was shown that about 80% of the DDT was lost from the soil in two years. The half life of DDT was 319 and 343 days in the two experiments. At zero‐time p,p'‐DDT accounted for 93–95% of the extractable residues. Gradually, the proportion of p,p'‐DDT declined with time to 58–71% of the extractable residues after two years. In addition to DDT, the extractable residues contained DDE and DDD. DDE was the major metabolite of DDT in soil and accounted for about 22% of the extractable residue after 245 days and 37% after 18 months. DDD accounted for only 5% of the extractable residues after 18 months. Initially, the amount of bound residues was very small, but it gradually increased reaching a maximum of about 8% after one year. However, the bound residues declined thereafter to 4...