巢湖表层沉积物重金属生物有效性与生态风险评价

以巢湖表层沉积物为对象,对重金属(Cd、Cr、Cu、Zn、Ni和Pb)总量及形态进行分析并运用潜在风险指数法和风险评价编码两种方法对巢湖表层沉积物重金属的生态风险进行了评价.结果表明,巢湖表层沉积物中的重金属含量表现为西部湖区高,东部湖区低的特征,其中南淝河入湖区重金属含量是全湖的1.09~1.21倍.BCR形态分析表明,巢湖表层沉积物中Cr、Ni和Cu以残渣态为主(分别占总量82.99%、63.63%和54.25%),Cd和Zn以弱酸提取态为主(分别占总量55.96%和35.84%),Pb以可还原态和可氧化态为主(分别占总量39.66%和24.56%).潜在生态风险危害指数(RI)表明,南淝河入湖河口区域具有较大生态风险(RI值范围为351.54~381.17).风险评价编码方法(RAC)的结果显示,Cd处于极高风险水平,Zn基本处于高风险水平,Cu和Ni处于中低风险,Pb处于低风险水平,Cr各采样点均处于无风险.因此,对需着重考虑对南淝河入湖湖区的Cd和Zn元素的重点治理.

Bioavailability and ecological risk assessment of heavy metals in surface sediments of Lake Chaohu

Surface sediment samples were taken from Lake Chaohu, total and fractions of six heavy metals (Cd, Cr, Cu, Zn, Ni and Pb) were studied. The pollution of heavy metals were evaluated by the potential ecological risk index (RI) and risk assessment code (RAC). Heavy metal distribution of surface sediment indicated a higher degree of contamination in the west regions, and then the east regions, the content of heavy metals in Nanfei inflow river area are higher from 1.09to 1.21times than the whole lake. Fractions of heavy metals analysis showed that Cr, Ni and Cu existed mainly in residual fraction (82.99%, 63.63% and 54.25%) and the weak acid soluble fraction was the dominant for Cd and Zn (55.96% and 35.84%), while Pb was found mainly in the reducible fraction and oxidizable fraction (39.66% and 24.56%). Potential ecological risk assessment showed that High pollution level regions were distributed in Nanfei inflow river area (351.54~381.17). The risk assessment code showed that Cd had very high risk level, Zn had high risk level, Cu and Ti were between low risk and medium risk level, Pb was between no risk and low risk level, Cr posed no risk. Therefore, emergent management measures must be taken to control pollution of Cd and Zn in Nanfei inflow river area.