青海倒淌河末端沉积物中重金属含量及其指示意义

Concentration and implications of heavy metals in sediment in the lower reaches of Daotanghe,Qinghai Province

对青海湖流域倒淌河末端沉积物样品中As、Cd、Pb、V、Cr、Mn、Ni、Cu、Zn等9种重金属元素的含量进行了分析测定,并评估了其污染程度。结果表明:无论在横向还是纵向上,所分析重金属元素含量均低于青海湖土壤背景值、青海省土壤平均值和土壤环境质量一级标准值,潜在生态风险因子均低于40,多风险因子指数均低于65;样品中As、Cd、As富集系数基本为1~2,其它重金属元素富集系数基本小于1。倒淌河末端沉积物尚未出现重金属污染,但该流域确实存在重金属的人为排放,而且在近代排放更为显著。虽然经过沉积和植物吸收,倒淌河河水流至其末端时重金属元素依然未完全被净化干净,主要体现在As、Cd、Pb上。

Heavy metal(including As, Cd, Pb, V, Cr, Mn, Ni, Cu and Zn) concentration analysis and contamination evaluation for sediment in the lower reaches of Daotanghe in Qinghai Province have been carried out. These heavy metals concentration in both spatial and temporal sediments are lower than the background values of top soil within the Qinghai Lake area, the average soil content of Qinghai Province and Environmental Quality Standard for Soils in China(GB15168-1995). The potential ecological risk index of each heavy metal is lower than 40, and the ecological risk index of the nine heavy metals are lower than 65. Enrichment factor of As, Cd, and As in the sediment are almost 1 ~ 2, and enrichment factor of other heavy metal in the sediment are almost lower than 1. The results suggest that sediment in the Daotanghe lower reaches has not been polluted. However, anthropogenic contribution for heavy metals do exists in the drainage area, and it was significant in modern times. Although be absorbed by sediment and plant, heavy metals, especially As, Cr, Pb, are not yet cleared completely when current reach the lower reaches, and anthropogenic discharge with As, Cr, Pb into the drainage area should be restricted.