北运河源头区沙河水库沉积物重金属污染特征研究

Characteristics of Heavy Metal Pollution in the Sediments from Shahe Reservoir,the Upper Reach of the North Canal River

选取北运河源头区沙河水库为研究对象,建立沙河水库沉积物年代学序列,分析其中6种重金属(Cr、Cu、Mn、Ni、Pb、Zn)的时空分布特征,并从重金属富集系数、与区域经济发展的关联分析等方面探讨其来源.研究表明,沉积物30 cm深度处对应年代为建坝时间1960年.库心区沉积物Pb和Mn的含量比较恒定,平均含量分别为30.6 mg.kg-1、735.1 mg.kg-1;重金属Cr、Cu、Ni、Zn则明显出现累积,与北京市土壤背景值相比均超过2倍以上.1960年至80年代中期,沉积中Cr、Cu、Ni和Zn含量随时间变化平缓,平均含量依次为51.2 mg.kg-1、36.0 mg.kg-1、31.5 mg.kg-1和121.6 mg.kg-1;而从80年代中期至2000年,其含量随时间呈明显增加趋势,该期间4种重金属平均含量分别是80年代中期之前含量1.4、2.1、2.8和4.3倍,累积现象严重.重金属含量的空间分布为水库中央含量及富集程度高于出、入水库口.对重金属的来源分析表明Cr、Cu、Ni和Zn主要是由人为源输入,而Mn和Pb是由自然源输入的.

Shahe Reservoir,in the upper reach of the North Canal River,was selected for researching on sediments heavy metals pollotion.History of the sediments was build and six heavy metals（Cr,Cu,Mn,Ni,Pb,Zn） were analyzed for distribution characteristics,the resoures of heavy metals were also studied by sediments enrichment factor and the relationship between heavy metal contents and socio-economic development in this region.The results showed that the 30 cm depth of the sediments represented the year of 1960,the time when Shahe Dam was built.The average contents of Pb and Mn from Shahe Reservoir central sediments were 30.6 mg·kg-1 and 735.1 mg·kg-1.While Cr,Cu,Ni and Zn had a centainy accumulation and their contents were all over 2 times higher respectively comparing to the background values of Beijing soil.From 1960 to mid-1980s,the contents of Cr,Cu,Ni and Zn had a sligtly change and their average contens were 51.2 mg·kg-1,36.0 mg·kg-1,31.5 mg·kg-1 and 121.6 mg·kg-1.However,during the period of next 20 years,the contents of these four heavy metals were elevated and their average contents were 1.4,2.1,2.8 and 4.3 times comparing to the foremost 20 years,which indicated that the enrichment of heavy metals was obvious during that time.While for spatial distribution,the sediments from the center of the reservoir had higher contents of heavy metals than the sediments from the estuary of the reservoir.In terms of the sources of heavy metals in the sediments from Shahe Reservoir,it was recognized that Cr,Cu,Ni and Zn were influenced by anthropogenic activities while Mn and Pb were mainly originated from natural soureces.