Studies on Residues of Organochloride Pesticides(OCPs) in the Soils of Xiangjiang River Valley

51 samples were collected from Xiangjiang River valley in May 2004.The samples were analyzed for Hexachlorobenzene(HCB),DDTs(DDT,DDE and DDD),Chlordane,Aldrin,Dieldrin,Endrin,Heptachlor and Mire by gas chromatography with mass selective detection(GC-MS).The results were as follows: the detection rates of HCB and DDTs were 100%,the detection rates of Chlordane and Mirex were lower,Aldrin,Dieldrin,Endrin,Heptachlor were undetected.It was shown that HCB and DDTs were used widely in Xiangjiang River valley.The mass fraction average of OCPs was 145.49(μg/kg,) and DDTs were the primary compounds in soil samples,accounting for 90.9% of OCPs.The high ratio of(w(DDT))/(w(DDE+DDD)) in some region possibly indicated that DDTs were mostly used as insecticide and there were still fresh DDTs emitted into Xiangjiang River valley.The pesticide residue is also in direct proportion to the use level of pesticides.For an example,the pesticide residue level is highest in soil samples in Hengyang area where the use of pesticides was higher.The pesticide residue of OCPs was different in soils of different functions.It was shown that the pesticide residue in dry land was higher than in paddy land and the highest pesticide residue of OCPs was found in pepper land among vegetable lands.