红枫湖入库河流沉积物中重金属污染状况分析

采用综合污染指数法和Hakanson生态风险指数法,对红枫湖几条主要入湖河流入湖处以及原后五养殖区沉积物中8种重金属(Cd、Pb、Cu、Co、Ni、Cr、V、Zn)含量进行了分析。研究结果表明桃花源河污染最严重,达到了中等污染水平(P=2.70,RI=171.02);后六河尽管Zn污染较严重,但其生态危害性低;其余河流的污染程度都较低。几条入湖河流的潜在生态危害性由高到低的顺序为:桃花源河>后六河>羊昌河>麻线河。所研究的8种重金属中只有Cd(Eir均≥40)具有较高的潜在生态风险,桃花源河的Cd的Eir最高(Eir=82)。其余重金属由于毒性系数小,尽管部分重金属含量达到了背景值的许多倍,但都无显著的潜在生态风险。但是后六河的Zn含量高过了生态效应必然浓度值(PEL),需引起重视。通过对桃花源河沉积物重金属含量垂向变化的研究发现,在早期成岩过程中沉积物中Cd、Pb、Ni、Co、Cr、Cu、V的沉降主要受有机质的控制;Cr不仅受有机质的影响,还受氧化还原条件的影响;而Zn则明显受粒度的控制。

Analysis of Heavy metal Pollution in the Sediment of the Inflow-lake Rivers of the Hongfeng Lake

Based on the analysis of the contents of 8 heavy metals(Cd, Pb,Cu, Co, Ni, Cr, V, Zn)in the sediments of 4 main inflow-lake rivers of the Hongfeng Lake and Houwu fish-farm, the quality status of these sediments was evaluated by adopting comprehensive pollution index and Hakanson ecological risk index. The sediments of the Taohuayuan River are most seriously polluted, reaching a moderate level of pollution(P=2.70,RI=171.02). Although the concentrations of Zn in the sediments of the Houliu River are high,the ecological risk is slight. The sediments of the other rivers have low pollution levels. The potential ecological risks follow the order of Taohuayuan River > Houliu River > Yangchang River > Maxian River. Overall potential ecological risk is mainly attributed to Cd,whose potential ecological risks in all the sediments were identified to be moderate or severe,and the others only caused slight ecological risks. Aanalysis of the variations of the contents of the 8 heavy metals and TOC,Mo and Rb along with the depth profile shows that the deposition of Cd, Pb, Ni, Co, Cr, Cu, and V is controlled mainly by the variation of TOC during early diagenetic processes. Cr was determined in terms of redox conditions and diagenetic processes,and Zn was mainly governed by particle or grain size.