PERSISTENCE AND BINDING OF P,P'-DDE IN SOIL

Soil was treated with C-14-p,p'-DDE and left under field conditions fo r 545 days. The dissipation of the chemical was apparently biphasic; h alflife of dissipation 271 days. After one year, 61% of the initially applied radiocarbon was lost from soil. Methanol-extractable residues declined to about 29% after one year and were shown by TLC and HPLC, t o contain mainly p,p', DDE and a small amount of DDMU. Initially, the proportion of bound (unextractable) residues was very small but increa sed gradually to 8.7% after one year and declined thereafter to 7% aft er 1.5 years. These soil-bound residues, released by treatment with su lfuric acid consisted exclusively of p,p'-DDE. Volatilization and to a lesser extent mineralization were the main mechanisms for the loss of DDE residues from the soil.