【摘要】 入江中小河流重金属污染状况对中小河流自身及其汇入的大江大河生态系统的健康发展均具有重要意义.通过采集襄阳入江6条河流的表层沉积物和上覆水,分析沉积物粒径、有机质、总氮、总磷及6种重金属含量.同时,采用沉积物质量基准系数和潜在生态危害指数法对重金属污染进行评价,并通过相关分析和冗余分析方法对沉积物中重金属来源进行解析.结果表明,襄阳入江中小河流水体中的重金属均处于较低水平,优于《地表水环境质量标准》（GB3838—2002）Ⅱ类水标准.表层沉积物中Hg、Cd、Cr、Pb、Zn和Cu的平均含量分别为0.23、1.75、48.4、135.8、173.2和44.7 mg·kg^-1,除Cr外,其他5种重金属含量远超湖北省土壤元素背景值.6种重金属元素的平均含量均处于临界效应浓度和可能效应浓度之间,为中等污染水平.襄阳入江中小河流表层沉积物重金属的综合潜在生态风险指数（RI）的平均值为461.2,整体处于高风险水平,其中,小清河处于很高生态风险水平,其他河流处于高生态风险水平.冗余分析表明,随着沉积物OM、TN和TP含量的增加、粒径的降低,表层沉积物中的各重金属含量相应增加;Hg、Cd、Pb和Zn的富集系数大于1.5,表明在一定程度上受到了人为活动的影响;Hg、Cd和Pb的污染源可能来自于汽车及其相关产业,Cu和Zn的污染源可能来自于农业生产和养殖业.更多还原

【Abstract】 Heavy metal pollution of sediments in small and medium rivers affects the healthy development of themselves and the mainstream which they flow into. Surface sediments and overlying water of six rivers in Xiangyang City were collected to analyze particle size, organic matter, total nitrogen, total phosphorus and six types of heavy metal contents, and the risk of these heavy metals were assessed by Consensus Based Sediment Quality Guidelines（CBSQGs） and Hakanson potential ecological risk index method. The identification of heavy metals in sediments were analyzed with correlation and redundancy analysis. The results show that the heavy metals in overlying water were at a low level, and better than class-Ⅱof Surface Water Environmental Quality Standard（GB3838—2002）. The average contents of Hg, Cd, Cr, Pb, Zn and Cu were 0.23, 1.75, 48.4, 135.8, 173.2 and 44.7 mg·kg^-1 respectively. Except for Cr, the other five types of heavy metals were far higher than those of background values in soil in Hubei Province. The average contents of six heavy metals were between threshold effect concentration（TEC） and probable effect concentration（PEC）, which were at moderate pollution level. The average comprehensive potential ecological risk index of heavy metals in surface sediments was 461.2, which was at high risk. The ecological risk of Xiaoqing River was considerable, while the other 5 rivers were high. Redundancy analysis showed that the contents of heavy metals in surface sediments increased with the increase of organic matter, total nitrogen and total phosphorus, and with the decrease of sediment particle size, correspondingly. The enrichment coefficients of Hg, Cd, Pb and Zn were more than 1.5, indicating that they were influenced by human activities. The possible pollution sources of Hg, Cd and Pb might come from automobiles and related industries; while Cu and Zn might come from farming and aquaculture.更多还原