Leaching Behavior of Chlorpyrifos and its Main Metabolite TCP through 5 Types of Soil Columns in Laboratory Conditions

By applying the OECD soil column method, the leaching behavior of chlorpyrifos and it main metabolite, 3,5,6-trichloro-2-pyridino(l TCP), in five types of saturated soil was compared. The results show the following: (1) Chlorpyrifos can be retained in the five types of saturated soil, and the rate of chlorpyrifos residues in the five types of soil columns are 86.9% (Black soil), 80.3% (Red soil), 77.9% (Limestone soil), 74.7% (fluvo-aquic soil) and 68.9% (Purple soil) of the application amount; (2) No chlorpyrifos was found in the leachate; (3) TCP could fully migrate in the five types of 30-cm-long soil columns and the TCP residues in these columns are 34.4% (Black soil), 29.6% (Red soil), 24.8% (Limestone soil), 14.1% (fluvo-aquic soil) and 10.3% (Purple soil) of the application amount; (4) The average concentrations of TCP in the 400 mL leaching solution were from 0.31 mu g.mL(-1) to 0.23 mu g.mL(-1); and (5) The K-oc and GUS values of the TCP in the five types of soil showed that TCP has a great leaching risk compared with its parent compound of chlorpyrifos.