绿洲城市土壤及地下水重金属污染及源解析

Heavy Metal Contamination and Source Analysis of Soil and Groundwater in Oasis Cities

干旱区城市分布在绿洲区域,承载着大部分的人类活动,近年来随着社会经济的发展,绿洲的环境污染问题日益突出,但基础调查数据的缺少导致城市重金属污染现状尚不清楚。该研究以新疆和田绿洲为典型研究区,对城市不同功能区的土壤和地下水进行样品采集,结合内梅罗综合污染指数法、主成分分析法(PCA)、正矩阵因子分解法(PMF)等,对和田绿洲城市6种重金属(As、Zn、Cu、Cd、Ni、Pb)空间分布特征和来源进行了分析,并对土壤潜在风险进行评价。结果表明:(1)和田市土壤重金属含量均未超过国家风险筛选值,与新疆土壤背景值基本持平,污染较小。土壤重金属潜在生态风险程度较低,表现为轻微风险。(2)研究区地下水重金属含量均达到Ⅲ类水标准,为饮用水水质,各重金属含量分布均匀,联系较弱。(3)研究区土壤与地下水重金属均以自然源、工业源为主要来源,土壤重金属另有一个农业及交通混合源。其中土壤中自然源、农业交通混合源和工业源的贡献分别占43.06%、27.99%、28.95%。土壤与地下水重金属含量较低,污染较弱,两者重金属来源基本相同,主要受自然环境与人为活动影响。该研究以期为干旱区绿洲重金属污染研究提供参考和依据。

Arid zone cities are distributed in the oasis region,carrying most of the human activities,in recent years with the development of social and economic development,the environmental pollution problem of the oasis is becoming more and more prominent,but the lack of basic survey data leads to the current situation of urban heavy metal pollution is not yet clear.In this study,the spatial distribution characteristics and sources of six heavy metals(As,Zn,Cu,Cd,Ni,Pb)in the city of Hotan Oasis,Xinjiang,were analysed using the typical study area of Hotan Oasis in Xinjiang,where soil and groundwater samples from different functional areas of the city were collected,and combined with the Nemero comprehensive pollution index(NCPI)method,principal component analysis(PCA),and positive matrix factorizatio(PMF)to analyse the spatial distribution characteristics and sources of the six heavy metals in the city of Hotan Oasis,as well as the potential soil risks were evaluated.The results show that none of the soil heavy metal contents in Hotan City exceeded the national risk screen-ing value,which is basically the same as the background value of soil in Xinjiang,and the pollution is relatively small.The degree of potential ecological risk of soil heavy metals is low,showing a slight risk.The heavy metal contents of the ground-water in the study area have reached the standard of ClassⅢwater,which is drinking water quality,and the heavy metal con-tents are evenly distributed with weak connection.Both soil and groundwater heavy metals in the study area have natural and industrial sources as the main sources,and there is another mixed agricultural and transportation source of soil heavy metals.Among them,the contribution of natural sources,mixed agricultural and transportation sources and industrial sources in soil accounted for 43.06%,27.99%and 28.95%respectively.The heavy metal contents of soil and groundwater were low and the pollution was weak,and the sources of heavy metals in both were basically the same,which were mainly affected by the nat-ural environment and anthropogenic activities.This study is intended to provide reference and basis for the study of heavy met-al pollution in the oasis of arid zone.