菏泽市水系沉积物重金属特征及风险评估

Characteristics and risk assessment of the heavy metals in stream sediments of Heze City

为探讨南水北调东线重要汇水区菏泽市水系沉积物重金属特征、污染来源及环境风险,采集了菏泽市3个主要流域25个点位的水系沉积物进行6种重金属(Cu、Zn、Ni、Cr、Cd、Pb)含量分析,并利用污染负荷指数法、潜在生态风险指数法和对数回归模型法进行风险评估,利用相关性和主成分分析判别重金属污染来源。结果表明,研究区各流域水系沉积物重金属含量普遍高于背景值,所有点位Ni、Cd含量均超背景值,其中Cd有40%点位超3倍背景值。各流域水系沉积物重金属含量分布不均,6种重金属极大值均出现在洙赵新河流域,其污染负荷指数(PLI)、潜在生态风险指数(RI)、毒性比值(Y)分别为1.62、123和0.367,均高于其余两流域,属于中度污染,具有较强生态风险,可能对水生生物造成危害。主成分分析表明造成研究区内6种重金属富集的主要来源是工业园区内石油炼制及相关化工企业。

This study aims to investigate the characteristics,pollution sources,and ecological risks of heavy metals in the stream sediments in Heze City,which is an important catchment area in the east route of the South-to-North Water Diversion Project.To this end,stream sediment samples were collected from 25 sites of three major river basins in Heze City,and the contents of Cu,Zn,Ni,Cr,Cd,and Pb in the samples were analyzed.Moreover,this study assessed the ecological risks of these heavy metal elements using the pollution load index(PLI),potential ecological risk index(RI),and logarithmic regression model and determined the pollution sources of these heavy metal elements through correlation and principal component analysis.The results are as follows.The contents of the six heavy metal elements in the stream sediment samples were generally higher than their background values.The Ni and Cd contents at all investigated sites exceeded their background values,especially the Cd content at 40%of the investigated sites,which was more than three times the background value.The heavy metals in the stream sediments of the three river basins are unevenly distributed.The maximum values of the six heavy metals all originated from the samples of the Zhuzhaoxin River basin,of which the PLI,RI,and toxicity ratio Y were 1.67,123 and 0.367,respectively.These values were higher than those of the other two basins,indicating that the heavy metals in sediments of the Zhuzhaoxin River basin reach moderate pollution and have high ecological risks and potential harm to aquatic organisms.The principal component analysis shows that the petroleum refining and related chemical enterprises in industrial parks are the main contributors to the enrichment of the six heavy metal elements.