东江湖表层沉积物重金属污染特征与潜在生态风险评价

Analysis of Heavy Metal Pollution Characteristics and Potential Ecological Risks of Surface Sediments in Dongjiang Lake

为了解东江湖表层沉积物重金属的污染特征、空间分布特征以及潜在生态风险和来源,采集了东江湖12个点位的表层沉积物,对其中20种重金属(Li、Be、V、Cr、Mn、Co、Ni、Cu、Zn、Ga、As、Se、Rb、Sr、Ag、Cd、Cs、Ba、Pb和U)的含量进行分析.采用地累积指数法和潜在风险指数法评估了沉积物重金属的污染程度和潜在风险,并利用相关性分析和主成分分析对主要重金属进行了溯源分析.结果表明,东江湖沉积物重金属中ω(Cd)(2.25 mg·kg^(-1))和ω(As)(80.80 mg·kg^(-1))的平均值分别是湖南省背景值(0.11 mg·kg^(-1)和14.7 mg·kg^(-1))的21.2倍和5.5倍,污染相对严重,重金属空间分布整体呈现:南部>北部>中部.地累积指数法评价显示Cd为偏重度污染,As和Se为偏中度污染水平,Ag和Ga为轻度污染.潜在生态风险指数评价表明东江湖表层沉积物整体表现为高风险水平,主要环境风险因子分别为Cd和As,分别表现为极高风险和中等风险.

To understand the pollution characteristics,spatial distribution characteristics,potential ecological risks,and sources of heavy metals in surface sediments of Dongjiang Lake,12 surface sediment samples were collected from Dongjiang Lake.The contents of 20 heavy metals including Li,Be,V,Cr,Mn,Co,Ni,Cu,Zn,Ga,As,Se,Rb,Sr,Ag,Cd,Cs,Ba,Pb,and U were analyzed in this study.The geo-accumulation index method and potential risk index method were used to evaluate the pollution degree and potential risks of heavy metals in sediments,and the correlation analysis and principal component analysis were used to trace the source of the primary heavy metals.The results showed that the average contents ofω(Cd)(2.25 mg·kg^(-1))andω(As)(80.80 mg·kg^(-1))in heavy metals of Dongjiang Lake sediments were 21.2 times and 5.5 times the background value(0.11 mg·kg^(-1)and 14.7 mg·kg^(-1))of Hunan province.The overall spatial distribution of heavy metals was in the order of South>North>Central.The evaluation by the geo-accumulation index method showed that Cd was at the heavy pollution level,As and Se were at the moderate pollution level,Ag and Ga were at the light pollution level,and the other heavy metals were below the pollution standard.The evaluation by the potential risk index showed that all the surface sediments of Dongjiang Lake were at the high-risk level.The main environmental risk factor was Cd,which had an extremely high risk;the second was As,which had a medium risk;and the remaining heavy metals had no ecological risk.