Research Of Organochlorine Pesticides In The Sediments Of Gan River Basin

As the biggest river, Gan River is the main source of drinking water along theresidents in Jiangxi Provice. A mass of Organochlorine pesticides(OCPs) were appliedsurrounding Gan River in the past, which were so difficult to degradate that manyresidues remained in the environment.The residues flowing into Gan River with variouschannels caused threat to human health and ecological environment.It is very importantand meaningful to do research on the residues of organochlorine pesticide in sedimentsof Gan River.Based on “Adjacent water vertical spile method”，the samples of sediment and soilwere collected from Gan River and pretreated by Soxhlet Extraction. Concentrations of10kinds’ organochlorine pesticide residues (such as DDTs, HCHs and so on) in thesamples were determined by Gas Chromatography (GC) with Electron Capture Detector(ECD). From the cut-in point of OCPs concentration, based on ArcGIS9.3, SPSS11.5,Minitab15, Excel2003software, their compostion distribution and sources werediscussed, and ecological toxicity was also analyzed. The purpose of research is toprovide scientific basis for the database establishment of Persistent OrganicPollutants(POPs) and for pollution control of Gan River. The conclusions were asfollows:The total OCPs concentrations of sediment samples were11.81~39.20μg/kg, themean concentration was21.68μg/kg. The concentration (10.40μg/kg) of DDTs was thehighest among them presenting mainly as p,p’-DDT isomer. The concentration of HCHswas8.24μg/kg presenting mainly as β-HCH isomer. By contrast, the concentrations ofHCB and Heptachlor were comparatively lower,1.87μg/kg and1.18μg/kg respectively.Analysis of distribution characteristics of components showed that they were related notonly to the earlier residues in the environment, but also to fresh input of components.The total OCPs concentration in sediments was higher than those in soils,the meanconcentration was18.65μg/kg.The concentrations of DDTs and HCHs were11.93μg/kgand4.01μg/kg respectively. In contrast to Xiu River and Fu River in Jiangxi Provice,the total OCPs concentration of sediments in the Gan River was relatively higher.Compared the OCPs residue levels of sediments of home and abroad with that of GanRiver, the total OCPs concentration of Gan River was at a moderate level of overall pollution.The Spatial trend analysis indicated that organochlorine pesticide residues insediments of Gan River had trend effect. Based on the contour maps of organochlorinepesticide residues obtained on the basis of the Kriging Method, the spatial distributionof organochlorine pesticide residues was analyzed. The results indicated that there was agreat difference in distribution of organochlorine pesticide residues, the higherconcentrations distribution district of HCHs was located in the middle and lowerreaches of Gan River, the higher concentrations distribution district of DDTs waslocated in the upper and middle reaches of Gan River, the higher concentrationsdistribution district of HCB and Heptachlor was located in the lower reaches of GanRiver.The residues of DDTs in ecological risk of Gan River was evaluated with thestandard risk assessment Ingersoll. The DDT isomers concentrations level was greaterthan Effects Range-Median(ERM),so there were some ecological risks in the upper andmiddle reaches of Gan River, OCPs of sediments in the region may cause harm to theecological environment. The concentrations level of DDTs were between EffectsRange-Low(ERL)and Effects Range-Median(ERM), which indicated that the sedimentscontaining toxic pesticides had been less than75%risk. The ecological risk of HCHs insoils from Gan River is relatively low.