Abstract: Biodegradation of ¹⁴C-aldicarb in five soils is studied.Simulation test carried out in a closed microcosm with 22% of soil moisture content at 20-30℃.Among the soils tested,that from Xiaojiahe, Beijing, has the highest degradation rate of ¹⁴C-aldicarb. After a four-weeks incubation,51.3% of applied radiocarbon are released from it in the form of ¹⁴CO₂,26.0%are bound and only 21.6 % are extractable.In soil from Yiwu, Zhejinag,a decreased degradation of ¹⁴C-aldicarb is observed.The amount of ¹⁴CO₂,collected from it occupies 23.3% of total ¹⁴C applied.The degradation of aldicarb is significantly retarded when sterilizing chemical chloramphenicol or captafol is applied to the soil.Aldicarb sulfoxids and aldicarb sulfoxide oxime are identified as the major metabolites, and trace amounts of aldicarb sulfone,nitrile sulfoxide and nitrile sulfone are also found in soils.

Key words: ¹⁴C-aldicarb, Degradation, Soils