[Dynamics of DDMS and DDMU in soils under rice and ryegrass planting].

Dynamics of DDMS and DDMU in soils with DDT application under rice and ryegrass planting by pot experiment in greenhouse was conducted. Results show that DDE/DDD is slightly increased, and only about 20 ng x g(-1) DDMU or DDMS could be found in ryegrass soil at the end of the experiment. However, the DDD, DDMS and DDMU are formed very rapidly in rice soil. By the 84th day of the experiment of rice planting, DDT residue is 70-80 ng x g(-1), about 2% of the concentration added at the first of the experiment, meanwhile, concentrations of DDD, DDMS and DDMU are increased to the highest level. Concentration of DDMS and DDMU is detected at 28 and 115 ng x g(-1) respectively. On the other hand, above phenomena are not observed in the aged DDT of soils, which implies that submerging could increase degradation of DDT added newly to DDD and DDMS/DDMU, but not for the aged DDT of soils.