赣江流域底泥中有机氯农药残留特征及空间分布

Residues and spatial distribution of OCPs in the sediments of Gan River Basin

基于"临水垂直插管法"采集赣江流域32个采样点的底泥样品,经索氏提取方法(Soxhlet Extraction,SE)前处理及气相色谱法(GC-ECD)检测样品中有机氯农药(OCPs)含量。结合多元统计学和ArcGIS9.3,研究了8种有机氯农药的残留状况及空间分布情况。结果表明,所检测8种OCPs中,除β-HCH有2个点未检出,其它7种OCPs检出率为100%。以DDTs残留含量最高,DDTs平均值为10.40μg/kg,其异构体以p,p'-DDT为主;HCHs的平均值为8.24μg/kg,其异构体以β-HCH为主。它们除了来自环境中的早期残留外,仍然具有新的外源HCHs和DDTs的输入。不同OCPs在研究区分布存在很大差异,HCHs总量分布较高的地区位于流域的中下游,DDTs总量分布较高的地区位于流域的中上游。

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 80CPs 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 70CPs 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 theearly 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. EHCHs 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 EDDTs 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.