流域底泥重金属分布特征及其生态风险评价

Distribution Characteristics and Ecological Risk Assessment of Heavy Metals in Watershed Sediment

为了研究流域底泥重金属分布特征及成因,以潇河流域为研究区,利用原子吸收分光光度法测定底泥中6种重金属(Cu,Zn,Cd,Cr,Pb,Ni)的含量,分析了重金属污染特征及其成因,并采用潜在生态风险指数法评价了潇河流域底泥中重金属的潜在生态危害系数和危害指数。结果表明,正常淤积下,流域底泥重金属含量呈中上游流域高,下游流域低的趋势;非正常淤积下,如河道起伏不定,河流有新的污染物注入等,便会表现出下游高于上游的分布特征。就其成因来讲,流域底泥重金属含量受河流水质的影响较大,运用主成分分析(PCA)得出水质参数与重金属分布的关系。对潇河流域表层底泥中重金属的复合污染状况评价结果为:Cd>Pb>Ni>Cu>Cr>Zn。

In order to study the distribution characteristics and causes of heavy metals（HMs）in river sediment,six kinds of HMs（Cu,Zn,Cd,Cr,Pb and Ni）in sediment of the Xiaohe River were measured with atomic absorption spectrophotometer（AAS）.The characteristics and causes of HMs pollution were analyzed and the potential ecological risk index method was used to assess the potential ecological risk coefficient and harm index of HMs in the river sediment.Results indicated that the content of HMs in sediment of the Xiaohe River was higher in the upper and middle basin,and lower in the lower basin under normal accumulation conditions.Under the non-normal accumulation conditions,such as channel fluctuation and new pollution sources,the content of HMs was higher in the lower basin than in the upper basin.The content of HMs in the river sediment was easily affected by water quality,and their relationship was analyzed by principal component analysis（PCA）.Besides,the content of HMs in the river sediment was also affected by sediment size composition.Result from composite pollution evaluation for heavy metals in surface sediment of the Xiaohe River showed the order of CdPbNiCuCrZn.