赣南典型矿区河流上覆水与表层沉积物重金属分布特征及风险评价

Distribution characteristics and risk assessment of heavy metals in overlying water and surface sediments in rivers in typical mining areas of southern Jiangxi Province

为揭示赣南典型矿区河流重金属含量、赋存形态及生态风险,本文选取桃江为研究对象,采集10个监测点位的上覆水和沉积物.运用电感耦合等离子体质谱法对上覆水和沉积物重金属铜(Cu)、锌(Zn)、砷(As)和钨(W)的含量和形态进行分析.采用内梅罗综合污染指数法与风险评估编码法对桃江沉积物中4种重金属的污染状况进行评价.结果表明,上覆水中Cu、Zn、As和W的含量平均值分别为53.12、38.92、1.71、0.15μg·L-1,沉积物中Cu、Zn、As和W的含量平均值分别为43.09、135.55、16.4、17.23 mg·kg-1;4种重金属的各形态占比由高到低为残渣态>可氧化态>可还原态>酸溶态;内梅罗综合污染指数法评价结果显示50%的采样点都属于中污染级别,40%的采样点处于重污染级别;风险评估编码法评价结果中只有10%采样点处于低生态风险,90%的采样点均处于中等生态风险.

In order to reveal the heavy metal content,occurrence form and ecological risk of the rivers in the typical mining area of southern Jiangxi province,this paper selects Taojiang as the research object and collects the overlying water and sediments from 10 monitored points.The contents and morphology of heavy metals Cu,Zn,As and W in overlying water and sediment were analyzed by inductively coupled plasma mass spectrometry.The pollution status of four heavy metals in Taojiang sediments was evaluated by Nemero comprehensive pollution index method and risk assessment coding method.The results show that the average contents of Cu,Zn,As and W in the overlying water are 53.12,38.92,1.71 and 0.15μg·L-1,respectively.The average values of Cu,Zn,As and W in sediments are respectively 43.09,135.55,16.43 and 17.23 mg·kg-1;The comparison of the proportion of the four heavy metals is residue state>oxidizable state>reducible state>acid soluble state from high to low;the evaluation results of Nemero comprehensive pollution index method show that 50%of the sampling points belong to the middle pollution level,and 40%of the sampling points are at the level of heavy pollution;Only 10%of the sampling points in the risk assessment coding method are at low ecological risk,and 90%of the sampling points are at medium ecological risk.