开封城市河流表层沉积物重金属分布、污染来源及风险评估

河流沉积物重金属污染状况对河流水生态系统健康发展具有重要意义.采集开封城市河流水系表层沉积物,分析了沉积物p H、粒度、有机质、总氮及6种重金属含量,使用相关性与主成分分析方法对沉积物中重金属来源进行解析,并采用污染负荷指数法和沉积物质量基准系数法进行了重金属的污染评价.结果表明,开封城市河流表层沉积物有机质平均含量为88.87 g·kg-1,全氮平均含量为2.48 g·kg-1,重金属Cd、Cr、Cu、Ni、Zn和Pb含量远超河南省土壤元素背景值.相关分析和主成分分析显示,沉积物有机质、全氮含量和重金属含量有一定相关关系,而沉积物p H及平均粒径对重金属含量影响较小;6种重金属可被辨识出2个主成分,其中Cd、Cr、Zn和Pb为人为复合源因子,Cu和Ni为工业与自然源因子.污染负荷指数分析表明,惠济河和化肥河为强度污染,黄汴河、东护城河、药厂河和马家河为中度污染.沉积物质量基准系数评价结果表明,惠济河存在中等生态风险,化肥河存在高等生态风险,且沉积物重金属存在较大潜在生物毒性效应.

Distribution characteristics, sources identification and risk assessment of heavy metals in surface sediments of urban rivers in Kaifeng

Heavy metal pollution in river sediments affects the healthy development of water ecosystem. The surface sediments from rivers in Kaifeng City were collected to analyze the pH, particles size, organic matter (OM), total nitrogen (TN) and heavy metal contents, and underlying sources identification of heavy metals in surface sediments were investigated by using principal component analysis and correlation analysis, then risks of these heavy metals were assessed by pollution load index (PLI) and sediment quality guideline quotient(SQG-Q). The results show that the average contents of OM and TN were 88.87 g·kg^-1 and 2.48 g·kg^-1 respectively, and the mean contents of Cd, Cr, Cu, Ni, Zn and Pb were higher than those of background in soil in Henan Province. The results of correlation analysis and PCA show that heavy metals had prominent with OM and TN, yet the correlations between these heavy metals and pH, average particle size were weak. Two principal components were identified from six heavy metals. Cd, Cr, Zn and Pb were influenced mainly by anthropogenic activities, and Cu and Ni were controlled by industrial and natural sources. The PLI of the six rivers reveals that heavy metals pollution in surface sediments from Huiji river and Huafei River were serious, and the pollution in Donghucheng River, Yaochang River, Huangbian River and Majia River were moderate. The results of ecological risk assessment by SQG-Q indicate that Huiji River was at the medium risk level,and Huafei River was generally at the higher risk level.Heavy metals had great potentials for biological toxicity.