中文摘要：

为探讨小埠东橡胶坝对沂河临沂城区蓄水段沉积物重金属分布和富集的影响,利用柱状沉积物采样器在橡胶坝前2km处（对照）和坝前50m处分别获取原位柱状沉积物,在比较分析典型重金属Cu、Pb、Cd、Cr、Hg和As分布特征的基础上,对重金属污染程度及潜在生态风险进行评价。结果表明,橡胶坝前50m处采样点表层沉积物（0-4cm）Cu、Pb、Cd、Cr、Hg和As的平均含量均显著高于对照点,垂向分布上,橡胶坝前50m采样点同对照点相比,重金属含量均具有随深度增加而逐步减小的趋势,说明橡胶坝的建成改变沉积物重金属的分布与富集状况,促进坝前沉积物中重金属的富集,建坝后水动力条件的改变是其富集的主要原因。地积累指数评价法和潜在风险评价法一致表明,临沂城区蓄水段表层沉积物As、Cr和Pb污染较轻,污染程度为无或无-中,具有轻微的生态危害;Cu和Cd的污染程度分别为中和中-强,具有轻微和很强的生态危害;Hg处于极强污染,具有极强的生态危害。潜在风险评价法表明,橡胶坝前50m采样点和对照点重金属的风险水平分别为Hg〉Cd〉Cu〉Pb〉As〉Cr和Hg〉Cd〉Cu〉As〉Pb〉Cr,Hg为最主要生态风险贡献因子。

英文摘要：

In order to study the effects of Xiaobudong Rubber Dam on the distribution and accumulation of heavy metals in sediment of Yihe River at Linyi City, cylindrical sediment sampler was used to obtain the situ columnar sediment at sampling site of 2 km （the control site） and 50 m before the rubber dam, respectively. On the basis of comparative analysis in the distribution characteristics of sediment Cu, Pb, Cd, Cr, Hg and As, their pollution level and potential ecological risk were evaluated. Results showed that the average contents of Cu, Pb, Cd, Cr, Hg and As in 0--4 cm surface sediment at the site of 50 ra before the dam were sig- nificantly higher than those of the control site. In vertical direction, the contents of heavy metals at the site of 50 m before the dam showed a declining tendency with depth, reflecting the Xiaobudong Rubber Dam in- fluencing the distribution and promoting the enrichment of sediment heavy metals, and the hydraulic conditions＇ changing after building dam was the main cause. The results from the geoaccumulation index and the potential ecological risk index both indicated that the sediment As, Cr and Pb in Yihe River at Linyi presen- ted low risk, while Cu and Cd presented moderate risk, and Hg presented very high risk. The average risk levels of the sediment heavy metals at the site of 50 m and 2 km before dam were ranked in the order of Hg〉 Cd〉Cu〉Pb〉As〉Cr and Hg〉Cd〉Cu〉As〉Pb〉Cr, respectively, and Hg was as the most significant ecological risk contribution factor.