石梁河水库沉积物中重金属的累积污染研究

沉积物中的重金属常被作为环境质量的重要指标之一. 通过对岩芯的137Cs测年及探讨石梁河水库表层沉积物重金属的分布特征和柱状岩芯中重金属的垂直沉积特征，分析了水库重金属的主要来源，并采用Hkanson潜在生态风险指数法对水库沉积物中As，Pb，Cu，Cr，Zn 5种重金属进行生态风险评价. 结果表明:石梁河水库表层和岩芯沉积物的粒度与重金属元素的变化规律遵从“粒控效应"，库区表层的重金属含量显示Cr含量最高，而As含量最低；20世纪80年代前岩芯重金属含量是升高的，之后逐渐降低，其中As，Pb和Zn的变化较为明显；用Al校正后发现水库重金属元素主要为自然来源，但同时受到人类活动影响. 生态风险评价结果显示，单一重金属生态风险系数均小于40，潜在生态风险指数均小于150，说明水库各重金属富集程度均处于轻微的生态风险等级，各重金属元素的生态风险顺序为As>Pb>Cu>Cr>Zn. 

Accumulation on Heavy Metals of Sediments in Shilianghe Reservoir

Sediment heavy metals are often regarded as important indicators in environmental quality. Based on analysis of 137Cs activities and metal elements concentrations in the surface and core sediments of Shilianghe Reservoir, the sources for heavy metals in the reservoir were investigated, and risk assessment of five heavy metals (As, Pb, Cu, Cr, Zn) conducted by using method of Hkanson potential ecological risk index. The results showed that relation between material size and heavy metals followed the regularity of “grain size control”. The concentration of Cr was the highest and that of As was the lowest. Before the 1980s, the concentrations of the five heavy metals gradually increased, then decreased,and the change of As, Pb and Zn was especially obvious. Aluminum-normalized values on heavy metal elements revealed the heavy metals were mainly from nature sources, and meanwhile influenced by human activities. The ecological risk factor was below 40 and potential ecological risk index under 150, which indicated thatthe risk of heavy metals was minor, and that ecological risk of the five heavy metals was in the descending order of As, Pb, Cu, Cr and Zn.