清水河流域崇礼区河段沉积物重金属污染特征及风险评价

Characteristics and risk assessment of heavy metals pollution in sediments of Chongli District reaches of Qingshui River Basin

评价河流沉积物重金属污染特征及风险有助于识别河流生态环境健康.本文以清水河流域崇礼区河段6处沉积物重金属(As、Cd、Cr、Cu、Mn、Ni、Pb和Zn)为研究对象,采用地累积指数法、污染负荷指数法、富集系数法和潜在生态风险指数法对其分布特征、污染程度和潜在生态风险进行分析,并探讨重金属污染来源.研究结果表明,沉积物中重金属元素As、Cd、Cr、Cu、Mn、Ni、Pb和Zn的平均质量分数分别为37.85、0.52、82.28、16.04、403.75、19.77、24.40和50.03 mg/kg.地累积指数法与富集系数法显示,As和Cd重金属污染最为严重,各元素污染程度由低到高排序为Mn、Zn、Ni、Cu、Cr、Pb、Cd、As.污染负荷指数法显示,清水河上游到干流中部、由西到东的支沟重金属污染程度升高.主要重金属污染元素(As、Cd、Pb和Cu)潜在生态风险评价显示沉积物为中等生态风险.

Assessing on pollution characteristics and risks of heavy metals in river sediments are helpful to identify river ecosystem environment health.This study deals with the degree of heavy metals of As,Cd,Cr,Cu,Mn,Ni,Pb and Zn in Chongli District reaches of Qingshui River Basin sediments in six sites as the research sub⁃ject.The geo⁃accumulation index,pollution load index,enrichment factor and potential ecological risk index were used to assess distribution characteristics,contamination levels,potential ecological risk and possible sources of heavy metals.As the results indicate,the average contents in sediments of As,Cd,Cr,Cu,Mn,Ni,Pb and Zn heavy metals were 37.85,0.52,82.28,16.04,403.75,19.77,24.40 and 50.03 mg/kg.The analysis of geo⁃accu⁃mulation index and enrichment factor indicated that the heavy metals As and Cd were the main pollution factors and each element of the pollution degree from low to high followed the order:Mn,Zn,Ni,Cu,Cr,Pb,Cd,As.The pollution load index results indicated that overall heavy metals pollution in upstream was lighter than in the middle main stream,and the middle ditch was lighter than the east ditch.Based on the results of potential ecological risk index,for major heavy metal pollution elements As,Cd,Pb and Cu,the ecological risks were moderate risk levels.