Studies On Movement Of Organo-Chorine Pesticide In Soil-Water System In Taihu-Lake Region

Two different manners were carried out in order to assess the movement of Organo-Chorine Pesticide(OPC) in soil -water system. One was field survey, which was carried out in Taihu-Lake Region(TLR), the other was field test, which was carried out in Yangzhou City and Eco-system station of Chinese Academy of Sciences, Changshu, China.The resulted of field survey indicated that OPC residues very low or undectable in most soil sample, with concentration, DDT<5.3 μg/kg, HCH <4.5 μg/kg, respectively . the values reported here are far below the national environmental quality standard for agricultural soils.The concentrations of OPC in river water as the following: DDT<9.3 ug/L, HCH<36.1ug/L. The concentrations of DDT in 4 out of 13 and HCH in 2 out of 13 samples were higher than the national water quality standard for fisheries. OPC residues in sediment were higher than those in river water samples. DDT residues in fish body ranged from 0.1 to 8.8 μg/kg, while HCH ranged from 3.7 to 132 μg/kg, all the data for both DDT and HCH in fish body are well below than the state warning limit, indicating that the banning of OPC for 20 years has effectively created a safe environment for both crop and fishery production in TLR.The result of field test indicated that ten percent of pesticide or so was adsorbed in the plant, and the others were deposited in soil, water and air. It also indicated that the pesticide with high solvent has higher movement in soil, So the movement of HCH and butachlor are higher than that of DDT, They could pose pollution of ground water.The highest concentration of DDT, HCH and butachlor in rice seeds were 3320扬州大学硕士学位论文μg/kg, 551μg/kg and 1384 μg/kg, respectively. It means pesticide can accumulation much in seeds when sprayed in rice middle-growing period. The quantity of pesticide is high, the concentration higher. The concentration of pesticide in rice seed in Yangzhou is higher than those in Changshu, it can be conferred that different rice varieties are different on the capability of pesticide accumulation.The concentration of DDT in soil was higher than HCH and butachlor. It means DDT is degraded slowly in soil. One year after spray, DDT, with concentration of 1158.6 μg/kg ,was higher than the national environmental quality standard for soils, while HCH, with concentration of 17.7 μg/kg, lower than the national environment quality standard for soils, it will not lead to very serious soil pollution. The concentration of butachlor in soil was lower than the detection limit after one year, so it was safe in soil.The result of microbe incubation showed that pesticide had no impact on soil fungi, but actinomycetes were controlled by DDT and butachlor. HCH has no obvious influence on bacteria.