闽江福州段沉积物中重金属的分布特征及其毒性和生态风险评价

研究了闽江福州段表层沉积物中Cr、Zn、As、Cd、Cu和Pb等6种有毒重金属的含量及其空间分布特征,并采用基于共识的沉积物质量基准(CBSQGs)和潜在生态风险指数法(RI)对沉积物中重金属的毒性和潜在生态风险进行了评价.结果表明,6种重金属平均含量大小顺序为Zn(195.57 mg·kg~(-1))Pb(79.41 mg·kg~(-1))Cr(66.62 mg·kg~(-1))Cu(42.33 mg·kg~(-1))As(10.02 mg·kg~(-1))Cd(0.90 mg·kg~(-1)).Zn、Cd、Pb含量从河段上游到下游呈递减趋势,Cr、As呈递增趋势,Cu含量分布均匀.平均可能效应浓度商Q值对沉积物中重金属毒性判定结果表明,有18%的沉积物样品具有毒性,说明闽江福州段沉积物整体毒性效应低.从RI值来看,闽江福州段沉积物的生态风险属于中低等级;风险等级为中的样品占55.3%,主要分布在河段上游和中游(福州市区的南港和北港段),风险主要来自Cd的污染.

Distribution characteristics, toxicity and risk assessment of heavy metals in sediments of Minjiang River in Fuzhou City

The contents and spatial distributions of heavy metals (Cr, Zn, As, Cd, Cu, and Pb) have been studied in surface sediments of Minjiang River in Fuzhou City. Toxicity and potential ecological risk of heavy metals in sediments were assessed using consensus-based sediment quality guidelines (CBSQGs)and the potential ecological risk index (RI). The average concentrations of heavy metals were found to decrease in the following order:Zn (195.57 mg·kg^-1)> Pb (79.41 mg·kg^-1)> Cr (66.62 mg·kg^-1)> Cu (42.33 mg·kg^-1)> As (10.02 mg·kg^-1)> Cd (0.90 mg·kg^-1). From upstream to downstream, the concentrations of Zn, Cd, and Pb declined, the concentrations of Cr and As increased, and the concentration of Cu was unchanged. The calculated values of mean probable effect concentration quotients indicated that only 18% of sediment samples were above the CBSQGs, which suggests the toxicity of Minjiang River sediment in Fuzhou City is low. Based on the RI values, the sediments of Minjiang River in Fuzhou City have a low to moderate potential ecological risk. About 55.3% of the samples studied have a moderate potential ecological risk due to the concentration of Cd, which is mainly distributed in the upstream and midstream (the north and south branch of Fuzhou City).