三峡库区重金属含量空间分布及污染状况

Spatial Distribution and Pollution Characteristics of Heavy Metal Contents in Three Gorges Reservoir Area

[目的]对三峡库区坡面土壤与消落带沉积泥沙中重金属含量特征开展研究,为该区重金属污染评价提供理论与数据支持。[方法]在三峡库区选取53个采样点,分析区域内坡面土壤与消落带沉积泥沙中Cr,Cu,Pb,Zn,Mn 5种重金属元素的含量,利用单因子污染指数法、内梅罗综合指数法、地累积指数法和潜在生态风险指数法开展污染状况评价。[结果]研究区域内重金属含量平均值大小依次为:Mn>Zn>Cr>Cu>Pb,仅Cu,Zn和Mn存在污染。Zn和Mn在消落带沉积泥沙与坡面土壤中皆富集,而Cu仅在坡面土壤中富集。研究区域内重金属在空间分布上呈上、下游高,中游低分布。单因子污染指数法表明,研究区内仅存在Zn(P_(ia)=1.07)的轻度污染与Mn(P_(ia)=2.65)的中度污染。研究区域内梅罗综合指数为2.93,为中度污染。根据地累积指数法,研究区域内仅存在Mn轻度污染,其余重金属皆为无污染。Cr,Cu,Pb,Zn,Mn的潜在生态危害皆为轻微生态危害;研究区域的综合生态危害指数为14.09,为轻微生态危害。[结论]研究区域内Cr含量主要受到研究区地质背景影响,而Cu,Pb,Zn和Mn含量同时受到地质背景与人类活动的影响。研究区内存在Mn和Zn污染,且有轻微生态危害。

[Objective]The content characteristics of heavy metals in slope soil and sediment in fluctuating zone in the Three Gorges reservoir area were studied,in order to provide theoretical and data support for heavy metal pollution assessment in this area.[Methods]Three Gorges reservoir area was selected as the study area.Fifty-three sample points were selected to analyze the contents of heavy metals(Cr,Cu,Pb,Zn and Mn)in slope soil and fluvial zone sediments.The pollution situation was assessed by the methods of the single factor pollution index,Nemero pollution index,geo-accumulation index and potential ecological risk index,and the map of heavy metals content was formed by combining the geographic information system.[Results]The average contents of heavy metals were Mn>Zn>Cr>Cu>Pb,and only Cu,Zn,and Zn had pollution.Zn and Mn enriched in both sediment in water level fluctuating zone and slop soil,while Cu only enriched in slop soil.The spatial distribution of heavy metals showed a pattern as high in upper and lower reaches while low in the middle reach.The singe factor pollution index method show that there were only light pollution of Zn and moderate pollution of Mn in study area.The Nemerow composite index of the study area was 2.93,which was moderate.According to the geo-accumulation index,there was only slight pollution of Mn,the other heavy metals were pollution-free.The potential ecological risk of Cr,Cu,Pb,Zn,and Mn were slight ecological hazard.The comprehensive ecological risk index of the study area was 14.09,which was slight ecological risk.[Conclusion]The content of Cr in the study area is mainly affected by the geological background contents of the study area,while the content of Cu,Pb,Zn,and Mn are affected by both geological background contents of the study area and human activities.There are Mn and Zn pollution in the study area,and there is slight ecological harm.