FATE OF C-14 ATRAZINE IN A SILT LOAM SOIL

Formation of C-14-atrazine degradation products and their distribution in the top 90 cm of a silt loam soil was determined during 16 months in the field. After 16 months, 68% of the applied C-14 was still prese nt in the soil. By 12 months after treatment (MAT). C-14 leached to 70 -80 cm. Atrazine accounted for 24% of the applied C-14 remaining 16 MA T, and was the predominant C-14-compound below 10 cm through 16 MAT. H ydroxyatrazine (HA) was the major degradation product in the top 10 cm of soil comprising 13% of C-14 present 1 MAT and increasing to 24% by 12 MAT. Predominant degradation products at depths greater than 10 cm were HA and deethylatrazine (DEA). Deisopropylatrazine (DIA) accounte d for less than 6% of the radioactivity recovered at any soil depth. D eethyldeisopropylatrazine (DEDIA) was detected in soil extracts 2 MAT indicating further degradation of DIA and DEA. The proportion of DEA a nd DIA increased while the proportion of HA decreased at increasing so il depths indicating that DEA and DIA are more mobile in soil than HA. The large amount of C-14 remaining in the soil 16 MAT, and the depth within the soil profile at which it is found, suggest that atrazine an d its degradation products have the potential to persist and move deep er in the soil and possibly contaminate ground water supplies.