Distribution of 14C-atrazine residues in humus fractions of a Brazilian soil

The fate of atrazine in a Typic Hapludox Brazilian Soil was studied in different horizons and under different incubation conditions. The non-extractable atrazine residues tend to increase during the incubation period of 64 and 120 days. The distribution of 1°C-atrazine non-extractable residues among traditionally isolated humic materials revealed that the greatest amount of radioactivity was found in the humin fraction (6% to 24% of total radioactivity applied), the fulvic acids contained 6% to 15% of the total radioactivity applied, whereas the humic acids contained the least amount of radioactive residues, 0.4% to 3%. The amount of bound radioactivity decreased with depth in the soil.