LABORATORY STUDIES ON VOLATILIZATION AND MINERALIZATION OF C-14 P,P'-DDT IN SOIL, RELEASE OF BOUND RESIDUES AND DISSIPATION FROM SOLID-SURFACES

In support of field data, laboratory studies were conducted on volatil ization, mineralization and binding of C-14-p,p'-DDT in soils at Sao P aulo. Incubation of soil for 6 weeks did not result in volatilized org anics or mineralization; with > 95% extractable radiocarbon in the for m of p,p'-DDT. Small amounts of bound residues (1.8%) were detected in soil. These data confirm the very slow dissipation of DDT in the fiel d which presumably relates to the acidic pH of soil (4.5-4.8). Bound C -14-residues in soils treated with C-14-p,p'-DDT at Praia Grande and S ao Paulo could be released (5-21%) by sulphuric acid treatment. The re leased residue had the composition: 69-90% DDT, 7-32% DDD and 0-3% DDE . Incubation of soil bound C-14-residues with fresh inoculum for 3 mon ths did not result in release of C-14. Dissipation from wooden surface s was fairly slow. After 20 weeks, 74% of the applied radioactivity co uld be recovered; 44% hexane-non-extractable.