小秦岭太峪水系沉积物重金属污染生态危害评价

Ecological hazard assessment of heavy metal pollution in sediments of Taiyu water system in Xiaoqinling

以金矿开发影响的黄河二级支流太峪水系沉积物为研究对象,沿河采集16个表层沉积物样品,分层采集垂向剖面10件水库沉积物样品,测定了样品中重金属元素Hg、Pb、Cd、Cr、As、Cu和Zn的含量,采用Hakanson潜在生态指数法和Tomlinson污染负荷指数法评价重金属元素污染程度和潜在生态风险。结果表明,矿业活动是太峪水系沉积物重金属元素污染的主要因素;变异系数、富集系数和最高污染系数均反映Hg、Pb、Cd是太峪水系沉积物的特征污染重金属元素,Cr和As的质量分数接近地区背景值;太峪水系表层沉积物受到重金属元素的极强污染,山区段污染较山外更严重;整个流域的Hg、Pb、Cd具有很强的潜在生态危害,Cr、As、Zn的潜在生态危害轻微;太峪水系沉积物垂向各层沉积物都受到重金属元素的极强污染,生态问题以Hg、Pb、Cd的潜在生态危害为主,其污染和生态危害程度都高于流向上的沉积物。潜在生态危害指数评价突出了不同元素的毒性和危害程度,而污染负荷指数法侧重于样本空间上的污染程度,二者互补使用有利于实际问题的全面评价。

On the basis of the sediments of Taiyu River,a secondary tributary of the Yellow River affected by the gold mine development,16surface sediment samples were collected along the river and10reservoir sediment samples in vertical section were collected in layers.The values of heavy metals Hg,Pb,Cd Cr,As,Cu and Zn in the Taiyu River sediments were determined.The Hakanson potential ecological index method and the Tomlinson pollution load index method were used to evaluate the degree of heavy metal pollution and potential ecological risk.The results show that the mining activities are the main factors of heavy metal pollution in the sediments of Taiyu River system The coefficient of variation,enrichment coefficient and maximum pollution coefficient all show that heavy metals are the characteristic elements of Hg,Pb and Cd in the sediments of Taiyu water system,and the mass fraction of Cr and As is close to the background value of the region.The surface sediments of Taiyu water system are affected by extremely heavy pollution of heavy metals,and are more seriously polluted in the mountain section than in other areas.Hg,Pb and Cd in the whole basin have strong potential ecological risk,and the potential ecological risk of Cr,As and Zn is slight.Sediments are extremely polluted by heavy metals.The ecological problems are mainly the potential ecological hazards of Hg,Pb and Cd,and their pollution and ecological damage are all higher than deposits along the flow.The evaluation of potential ecological risk index highlights the toxic and harmful levels of different elements,the Pollution Load Index focuses on the degree of contamination of the sample space,and the complementary use of both is conducive to a comprehensive evaluation of practical problems.