基于双模型的星云湖沉积物重金属溯源及风险评价

Risk Assessment and Pollution Source Analysis Based on Double Models for Heavy Metal Pollution in Xingyun Lake Sediment

为了解星云湖沉积物中重金属污染现状,并为湖区污染防治提供理论依据,通过分析湖区表层沉积物中Cu、Zn、Pb、Ni、Cr、Cd、As、Hg等重金属含量,研究了其风险特征及污染来源组成.结果表明:①仅Ni、Cu含量尚未超过星云湖的背景值,其余元素均出现累积,Hg含量是星云湖背景值的2.13倍,潜在生态风险最高.②星云湖沉积物中重金属的空间分布与入湖河流和湖盆地势相关,表现出由河流输送向湖心扩散的趋势,高浓度区均分布在湖心深水区和特定河口位置,Hg的分布异于其他元素,呈西北湾>南部>中部的特征.③西北湖湾潜在生态风险最高,Cd、As是主要贡献元素.④星云湖沉积物中重金属主要来自自然源(占比为43.32%)、工业源(占比为25.89%)、农业源(占比为20.52%)和交通源(占比为10.27%).研究显示,星云湖自然源重金属污染贡献最大,人为源相对较低,但湖区重金属污染处于较高水平.星云湖的重金属污染生态风险可能会持续加剧,其中Hg是污染防控的重点.

In order to analyze the current status of heavy metal pollution and quantitatively explain its source distribution,the data of heavy metals such as Cu,Zn,Pb,Ni,Cr,Cd,As and Hg in the sediments of Xingyun Lake were obtained by fixed-point sampling in April 2018.The spatial distribution and pollution status of the heavy metals were analyzed using inverse distance weighting,index of geoaccumulation and potential ecological risk assessment.After judging the relationship between the pollution source categories and the primary and secondary sources by the PCA model,the contribution rates of the sources were obtained by the PMF model.The results show that Ni and Cu do not exceed the local background value,Hg is the highest potential ecological risk element,reaching 2.13 times the background value,Cd is the largest index of geoaccumulation element and the highest comprehensive potential ecological risk point appears in the northwest Bay of Xingyun Lake.The spatial distribution of heavy metals in Xingyun Lake sediments is mainly related to inflowing rivers and topography of lake basin.It shows the trend of centripetal diffusion from river transportation,and the high concentration areas are located in the lake center and the specific estuary.Hg is a special element and its distribution is different from other elements,it is in the order of northwest bay>south>central part.Heavy metals in the sediments of Xingyun Lake mainly come from natural sources(43.32%),industrial sources(25.89%),agricultural sources(20.52%)and transportation sources(10.27%).The contribution of natural sources is the largest and the contribution of anthropogenic sources is relatively low.The contribution of anthropogenic pollution sources in Xingyun Lake is not high,but the pollution of heavy metals in the lake area is still at a high level.The distribution characteristics of Hg and its huge risk contribution indicate that the ecological risk of heavy metal pollution in Xingyun Lake may continue to increase.