Mineralization of 14C-carbofuran in soil under aerobic and anaerobic conditions

ABSTRACT

The mineralization of 14C-carbofuran in clay loam soil was determined during a three months laboratory incubation period under anaerobic and aerobic conditions. 14C-activity in solution was directly determined by liquid scintillation counting. Unextractable soil residues were determined by combustion. Evolution of 14CO2 increased with time and reached to 7.5% and 12.0% of the initial 14C-concentration, within 90 days in case of anaerobic and aerobic conditions, respectively. At that time, soil contained about 58% of the applied dose as extractable residues under anaerobic conditions and 59% under aerobic conditions. The unextractable pesticide residues were gradually increased with time and the highest binding capacity of about 5.3% and 13% in case of anaerobic and aerobic conditions, respectively were observed after 90 days of incubation. Chromatographic analysis of methanolic extracts revealed the presence of labelled carbofuran, carbofuran phenol and 3-hydroxycarbofuran as main products. Radiorespirometiy was used to evaluate the effect of carbofuran on soil microbial activity for 14 days. Both 3 and 9 mg carbofuran/kg soil depressed 14CO2 evolution from 14C-glucose and microbial activity was significantly inhibited especially in case of the high dose