赣南桃江河表层沉积物钨赋存特征及风险分析

选择赣南桃江河表层沉积物为研究对象，采用改进的BCR提取法分析桃江上、中、下游及支流表层沉积物中钨的含量及赋存形态，并利用富集系数法（EF）和风险指数编码法（RAC）对桃江河表层沉积物中钨的富集程度与环境风险进行评价.结果表明，桃江河表层沉积物钨的总量范围为1.21~39.73mg/kg，均值为18.21mg/kg.研究区域58%的采样点沉积物中钨总量高于江西省土壤重金属背景值；桃江河沉积物中钨的主要赋存形态是残渣态（B4态），沉积物中各形态钨占总钨的比例大小顺序为残渣态 > 可氧化态 > 可还原态 > 弱酸提取态，空间上有效态钨占总钨的比例大小为支流 > 下游 > 上游 > 中游，平均比例分别为22.44%、21.03%、14.45%及10.91%.相关性分析显示，pH值和阳离子交换与钨的各形态及总量呈正相关.EF法分析表明桃江河上游与支流沉积物中钨富集严重；RAC法分析结果显示采样点沉积物中钨含量呈低、中、高生态风险占比分别为33.33%、46.67%、17.78%.上述结果表明，桃江河表层沉积物钨富集程度及环境风险较严重，应引起重视并开展深入研究.

Occurrence characteristics and risk assessment of tungsten in surface sediments of Taojiang River in Southern Jiangxi Province

Total concentrations and forms of tungsten in surface sediments from Taojiang river were determined and the methods of enrichment coefficient (EF) and risk index coding (RAC) were applied to assess the accumulative degree and environmental risks. The results showed that the tungsten concentrations ranged from 1.21 to 39.73mg/kg, with an average of 18.21mg/kg, while 58% of sampling sites were greater than the background values of the soil in Jiangxi Province. The species of tungsten were presented dominantly in the residual fraction, followed by the oxidizable, reducible and weak acid extraction fraction. Spatially, the effective tungsten in tributary is maximal with a mean value of 22.44%, followed by downstream (21.03%), upstream (14.45%) and midstream (10.91%). Correlation analysis showed that total concentrations and species of tungsten were positively correlated with the pH and cation exchange, respectively. The EF analysis suggested that the tungsten enrichment was seriously accumulated in the upper reaches and tributaries of the Taojiang River. The RAC analysis demonstrated the ecological risk in different sampling sites was low, medium and high, with a proportion of 33.33%, 46.67% and 17.78%, respectively. Altogether, this study indicated that the tungsten were accumulated in sediments of Taojiang River with seriously environmental risks, which deserve to be additional more extensive researches.