兴凯湖沉积物重金属生态风险评价及污染特征分析

Ecological risk assessment and pollution characteristic analysis of heavy metals in sediments of Xingkai Lake

兴凯湖是中俄跨国境湖泊,开展兴凯湖沉积物重金属生态风险评价及来源解析,对区域生态环境保护和治理具有重要意义。通过采集兴凯湖中国湖区表层及柱状沉积物样品,测定重金属As、Cd、Cu、Pb、Hg、Ni、Cr和Zn浓度,运用地累积指数法、潜在风险指数法对重金属污染状况和潜在生态风险进行评价,并通过数理统计分析其潜在来源。结果显示:小兴凯湖表层沉积物中Cr、Ni、As、Cr、Hg浓度均值超过黑龙江省土壤背景参考值,大兴凯湖表层沉积物中仅Ni、Cd浓度均值超过黑龙江省土壤背景参考值。地累积指数评价显示小兴凯湖表层沉积物Hg的污染程度较高,主要为轻度污染和偏中度污染,As和Cd以无污染为主、轻度污染次之,大兴凯湖Cd主要为轻度污染,其余重金属主要为无污染。潜在生态风险指数评价显示,兴凯湖表层沉积物总体呈无污染到偏中度污染,Cd为最主要的生态风险因子。As、Hg和Cd是重金属污染的主要因子,受入湖河流上游农业生产活动及矿产开发冶炼的影响,位于小兴凯湖东侧及大兴凯湖西侧区域污染风险相对更高;此外,考虑到大兴凯湖Cd呈底部富集特征,其可能受到自然背景影响。

Xingkai Lake is a cross-border lake between China and Russia.It is of great practical significance to study the sources and ecological risks of heavy metals in the sediments of Xingkai Lake for the protection and treatment of the regional ecological environment.The surface and columnar sediment samples of Xingkai Lake in China were collected systematically,and the contents of heavy metals As,Cd,Cu,Pb,Hg,Ni,Cr and Zn were determined.The pollution status and potential ecological risk of heavy metals were evaluated by the geoaccumulation index method and potential risk index method,and their potential sources were analyzed by the mathematical statistics method.The mean values of Cr,Ni,As,Cr and Hg in the surface sediments of Small Xingkai Lake exceeded the reference values of Heilongjiang soil background,while only Ni and Cd in Great Xingkai Lake exceeded the reference values of Heilongjiang soil background.The soil accumulation index evaluation shows that Hg in the surface sediments of Small Xingkai Lake has a high degree of pollution,mainly light pollution and moderate pollution,As and Cd are mainly pollution-free,followed by light pollution,Cd in Great Xingkai Lake is mainly light pollution, and other heavy metals are mainly pollution-free. The evaluation results of the potentialecological risk index show that the surface sediments of Xingkai Lake are generally pollution-free to moderatelypolluted, and Cd is the most important ecological risk factor. As, Hg and Cd are the main factors of heavy metalpollution, and the areas in the west and east sides of Small Xingkai Lake and the west side of Great Xingkai Lakeare more seriously polluted. The pollution is affected by agricultural production activities and mineral exploitationand smelting in the upper reaches. In addition, considering that Cd is enriched at the bottom of Great Xingkai Lake,it may be affected by the natural background.