Residues and spatial distribution of OCPs in the sediments of Gan River Basin
赣江流域底泥中有机氯农药残留特征及空间分布

Gan River basin area accounts for half the total area of Jiangxi province.As the biggest river,Gan River is the main source of drinking water for the residents in Jiangxi Province.A mass of Organochlorine pesticides(OCPs),which are persistent,toxicity,and easy to accumulated in biological bodys,were applied in the Gan River basin in the past.These OCPs were so persistent and can stay in the environment for a long time.The OCPs have entered into Gan River,caused a serious threat to health of environment and humans.Therefore it is neccessary to investigate residues of OCPs in the sediments of Gan River. Sediment samples were collected from 32 sampling sites from Gan River Basin.The samples were pretreated by Soxhlet Extraction and determined by Gas Chromatography(GC) with electron capture detector(ECD).The spatial distribution of concentrations for 8 OCPs were analyzed based on multivariate statistics and ArcGIS 9.3.By means of ordinary Kriging interpolation,spatial distribution of OCPs residual quantity was studied. The results indicated that detection rate was 100% in 7 OCPs except β-HCH.The concentrations of DDTs were 7.15—13.29μg/kg,the average value of which was 10.40μg/kg among them presenting mainly as p,p′-DDT isomer.The concentrations of HCHs were 1.63—20.88μg/kg(average value,8.24μg/kg) presenting mainly as β-HCH isomer.Sources of HCHs and DDTs contamination were from the early stage residues in the environment,along with the recent input of HCHs and DDTs components.Based on their component residues concentrations,the sequence was p,p′-DDT>β-HCH>o,p′-DDT>γ-HCH>α-HCH>p,p′-DDD>p,p′-DDE>δ-HCH.Sources of HCHs and DDTs contamination were from the early stage residues in the environment,along with the recent input of HCHs and DDTs components.And there was a great difference in spatial distribution of OCPs residues,the HCHs distribution district of higher concentration was located in the middle and lower reaches of Gan River,however the DDTs distribution district of higher concentration was located in the upper and middle reaches of Gan River.ΣHCHs in an east-west direction was a slight U distribution,in the north and south direction from south to north in a linear increase trend,but change range was not too much.p,p ′-DDE in an east-west direction & north and south direction were in a slight U distribution.o,p ′-DDT in an east-west direction & north and south direction were in parabolic trend.p,p ′-DDD,p,p ′-DDT and ΣDDTs in the distribution of an east-west direction was degressive tendency from west to east.In the distribution of north and south direction by the north to the south was linear increase trend.