鄱阳湖沉积物重金属生态风险评价:SQGs和AVS-SEM 模型法

Ecological Risk Assessment of Heavy Metals in Sediments of Poyang Lake:SQGs and AVS-SEM Models

鄱阳湖是我国最大的淡水湖,对我国长江中下游平原的水体环境有着重大影响。2018年测定了鄱阳湖表层沉积物中Cd、Zn、Cu、Pb的含量,并采用沉积物质量基准法(SQGs)和酸可挥发性硫化物(AVS)-同步可提取态金属(SEM)模型法评价了其生态风险。研究发现:鄱阳湖沉积物中4种重金属Cu、Pb、Zn、Cd的平均值分别是其背景值的1.58、1.18、1.30、8.87倍;AVS浓度范围为0.101~0.887μmol g-1,平均值为0.278μmol g-1;而SEM浓度范围为0.281~2.170μmol g-1,平均值为0.803μmol g-1。依据沉积物基准法计算,重金属风险值为0.15~0.23,表明具有一定的风险毒性;[SEM-AVS]模型法评价结果表明也具有一定的潜在生态风险,但若用考虑有机碳的修正模型[SEM-AVS]/foc评价结果则其无生态风险;相对而言,整个湖区风险较高的地点为三江口(S11、S12)和饶河口(S16、S17)。

Poyang Lake is the largest freshwater lake in China,which has a significant impact on the water environment in the middle and lower reaches of the Yangtze River.The contents of Cd,Zn,Cu and Pb in the surface sediments of Poyang Lake were measured in 2018,and their ecological risk was evaluated through SQGs and AVS-SEM methods.The mean values of the four heavy metals Cu,Pb,Zn,Cd in the Poyang Lake sediments are 1.58,1.18,1.30,8.87 times of their background values.The AVS concentration ranged from 0.101 to 0.887μmol g-1 with an average of 0.278μmol g-1.The SEM concentration ranged from 0.281 to 2.170μmol g-1,with an average value of 0.803μmol g-1.The risk of heavy metals in the sediments of Poyang Lake was calculated by sediment reference method and ranged from 0.15 to 0.23,which indicated that heavy metals had a certain risk toxicity.The[SEM-AVS]model indicated that heavy metals in sediments had certain potential ecological risks.However,the modified model of organic carbon[SEM-AVS]/foc indicated that heavy metals had no ecological risk.The higher risk points in the whole lake area were Sanjiangkou(S11,S12)and Raohekou(S16,S17).