Bound residues of 14C-carbofuran in soil

Abstract

Mineralization of 14C-carbofuran (2,3 dihydro-2,2-dimethyl-7-benzofuranyl-methylcarbamate) to 14CO2 as well as the formation of extractable and bound 14C-residues in clay loam soil were investigated under laboratory conditions. The 14C-carbofuran rapidly mineralized to 14CO2 and, after 20 days of incubation, 35.6% of the applied 14C was lost as 14CO2. The steady decrease of extractable 14C-residues was accomplished by a corresponding increase of bound 14C-residues over a 20-day incubation period. At the end of the experiment, the extractable and bound 14C-residues amounted to 7% and 59%, respectively, of applied radiocarbon. The soil containing bound 14C-residues was fractionated into humic substances. The humic acid, fulvic acid and humin fractions contained 22.39%, 26.04% and 17.56%, respectively, of the applied radiocarbon. The amount of 14C in microbial biomass was 15%. (author)