安庆沿江湖泊湿地湖滨带土壤重金属含量特征及潜在生态风险评价

为了解安庆沿江湿地湖滨带土壤重金属污染状况，保障区域水生态安全，采集了破罡湖、菜子湖和武昌湖等3个湖滨带的 75个土壤样品，利用电感耦合等离子体原子发射光谱法分析测定了土壤样品7种重金属As、Cd、Cr、Cu、Ni、Pb和Zn的总量和形态特征，并利用地累积指数法和Hankson潜在生态风险指数法评价3个湖泊湖滨带土壤重金属的污染状况和生态风险。结果表明：武昌湖湖滨带土壤的As、Cd、Cr、Ni、Zn的总量均显著高于菜子湖和破罡湖；7种重金属的形态特征差异较大，武昌湖湖滨带土壤中的Cd和As的可交换态含量分别为0.19 mg/Kg和10.68 mg/Kg，其占比分别为35.59%和46.28%，其他元素都以残渣态为主；地累积指数法和潜在生态风险指数法表明Cd的污染程度和潜在生态风险系数显著高于其他6种元素；研究区湖滨带土壤整体重金属风险等级较低，破罡湖、菜子湖和武昌湖的重金属潜在生态风险指数RI分别为102.03、95.72和190.65，破罡湖和菜子湖属于重金属轻度风险区域，武昌湖属于重金属中度风险区域。研究区土壤Cd受人类活动影响较大，湖滨带土壤中重金属主要受农业面源污染。

Characterization of Heavy Metals and Assessment of Potential Ecological Risk in the Shoreline Buffer Zone Soils of Anqing Lake Wetland

Shoreline buffer zones protect lake water quality and serve other important ecological functions. Anqing is a prefecture-level city in southwest Anhui Province and the Anqing Lake wetland is comprised of the shorelines of three lakes (Pogang Lake, Caizi Lake and Wuchang Lake) running along the Yangtze River. The aim of this study was to better understand the pollution status of heavy metals in the wetland soils and support efforts to protect and conserve aquatic ecology in the region. The soil levels and geochemical speciation of heavy metals in the shoreline buffer zones were determined and the results were used to assess the pollution status and ecological risk. In July and August 2019, 75 soil samples were collected from the shoreline wetlands of the three lakes. The total concentrations of seven heavy metals (As, Cd, Cr, Cu, Ni, Pb and Zn) were measured by inductively coupled plasma-atomic emission spectrometry and their geochemical speciation was determined using the Tessier sequential extraction procedure (exchangeable, bound to carbonate, bound to iron and manganese oxide, bound to organic matter, residual). The pollution status and ecological risk were assessed based on the geoaccumulation index and Hankson potential ecological risk index. The total concentrations of As, Cd, Cr, Ni and Zn in the lakeshore soils of Wuchang Lake was significantly higher than in those of Caizi Lake and Pogang Lake and the speciation of the seven heavy metals varied significantly. The concentrations of exchangeable Cd and As in Wuchang shoreline soils were 0.19 mg Kg-1 and 10.68 mg Kg-1 (35.59% and 46.28% of the total), while the residual fraction was the dominant form for the other six heavy metals, particularly Cr and Ni (>80%). Both the geoaccumulation index and potential ecological risk index of Cd were significantly higher than those of other six heavy metals, and are dramatically influenced by human activities. The potential ecological risk indices for Pogang, Caizi and Wuchang Lakes were generally low, with respective values of 102.03, 95.72 and 190.65, indicating a slight risk in Pogang and Caizi Lakes and a moderate risk in Wuchang Lake. Heavy metals in the lakeside belt were attributed primarily to agricultural non-point source pollution. Our study provides a scientific reference and technical support for the scientific management, environmental protection and security assessment of aquatic products in lakes and wetlands along the Yangtze river in Anqing City.