本文研究了我国最大的内陆高原咸水湖泊——青海湖不同环境介质之中 Cd 的分布特 征以及污染水平。本研究于 2016 年 9 月采集了青海湖湖水、湖底表层沉积物、环湖土壤及 布哈河河水样品， 处理并获取沉积物孔隙水样品。 测定各类样品的理化性质及元素含量， 从而分析青海湖不同环境介质中 Cd 的分布特征。 采用相关性分析（Correlation Analysis） 及主成分分析法（PCA）分析 Cd 含量的影响因素。提取青海湖沉积物中不同化学形态的 Cd 并测定其含量。 采用单因子污染指数法及地积累指数法评价了湖底沉积物及环湖表层 土壤中 Cd 的污染水平。 主要研究结果如下： （1）青海湖不同环境介质中 Cd 的含量分布 青海湖湖水、布哈河河水、沉积物孔隙水中溶解态 Cd 含量的均值分别为 0.014、0.007、 0.320 μg/L； 湖水中溶解态 Cd 的含量不随水体深度变化而改变。 湖底表层沉积物中 Cd 含 量的均值为 0.284 mg/kg， 而环湖表层土壤中 Cd 含量的均值为 0.281 mg/kg。环湖表层土壤 中 Cd 的富集水平低于湖底表层沉积物。 （2）青海湖不同环境介质中 Cd 含量的影响因素 相关性分析结果表明，湖水中溶解态 Cd 含量与溶解态 K、 Na、 Ca、 Mg、 S、 Cl 含量 呈显著正相关；河水中溶解态 Cd 含量则与 pH 值及溶解态 Ca、 Mg 含量呈显著正相关；沉 积物孔隙水中溶解态 Cd 含量与溶解态 Ca、 Cl 含量呈显著正相关。 湖底表层沉积物中 Cd 含量与 pH 值及 K、 Ca、 Na、 Mg、 S、 Al 等元素含量无显著相关性。 环湖表层土壤中 Cd 的含量与 Sc、 S、 Mn、 Al、 Fe、 K 含量呈显著正相关， 而与 Na 含量呈显著负相关。主成 分分析法结果表明，湖水中溶解态 Cd 含量受湖水盐度控制；河水中溶解态 Cd 含量主要受 碱度和 pH 值控制； 沉积物孔隙水中溶解态 Cd 含量主要受沉积物中碳酸钙和硫化物矿物 含量的影响； 环湖表层土壤中的 Cd 主要源于自然源。 （3）青海湖沉积物中 Cd 的赋存形态 形态提取结果表明，青海湖湖底表层沉积物中， 铁锰氧化物结合态是 Cd 的主要赋存 形态，占总 Cd 含量的 51.22%；其次为残渣态 Cd，占总 Cd 含量的 24.12%；碳酸盐结合态 Cd、有机物结合态 Cd 及可交换态 Cd 分别占总 Cd 含量的 15.34%、 4.74%和 4.58%。 生物可用性高的可交换态 Cd 及碳酸盐结合态 Cd 占总 Cd 含量的 19.91%。 （4）青海湖沉积物及环湖土壤中 Cd 的污染水平 单因子污染指数法评价结果表明，青海湖湖底表层沉积物中 Cd 的污染水平为轻度污 染，呈现中度污染水平的采样点占全部采样点的 45.45%；环湖表层土壤中 Cd 的污染水平 为中度污染，呈现此污染水平的采样点占全部采样点的 51.11%。 地积累指数法评价结果表 明，青海湖湖底表层沉积物中 Cd 的污染水平为无污染~中度污染，呈现此污染水平的采样 点占全部采样点的 95.46%；环湖表层土壤中 Cd 的污染水平同为无污染~中度污染，呈现 此污染水平的采样点占全部采样点的 86.67%。

This study reported the distribution characteristics and the pollution level of Cd in the water, sediment and topsoil in/around the lake from Lake Qinghai, which is the largest lake located in the Qinghai Tibet plateau in China. Water samples were collected from Lake Qinghai and Buha River in 9th, 2016, while sediment and topsoil samples were collected from the lake and around the lake area, respectively. Pore water samples were separated from sediment samples. Chemical properties and elements concentrations were measured, and distribution characteristics of Cd in different media were analyzed. Correlation Analysis and principle component analysis (PCA) were taken to identify factors that influence the distribution characteristics of Cd in different media. Tessier five-step sequential extraction method was taken to analyze the concentration of different chemical forms of Cd in the lake sediment. Single factor pollution index and index of geoaccumulation were taken to assess the pollution level of Cd in the sediment and the topsoil in/around the lake. Main conclusions are as follows: (1) Distribution of concentrations of Cd in multimedia of Lake Qinghai Average concentrations of Cd in the lake water, river water and sediment pore water were 0.014, 0.007 and 0.320 μg/L, respectively. The concentration of Cd did not change with water depth. Average concentration of Cd in the lake sediment was 0.284 mg/kg. Average concentration of Cd in the topsoil around the lake was 0.281 mg/kg. The enrichment level of Cd in the lake sediment was significantly higher than that in the topsoil around the lake. (2) Factors influencing concentrations of Cd in multimedia of Lake Qinghai Correlation analysis indicated that dissolved Cd concentration in the lake water was positivelycorrelated with concentrations of dissolved K, Na, Ca, Mg, S and Cl; dissolved Cd concentration in the river water was positively correlated with pH and concentrations of dissolved Ca and Mg; while dissolved Cd concentration in the pore water was positively correlated with concentrations of Ca and Cl. Cd concentration in the lake sediment was not correlated with pH and concentrations of K, Ca, Na, Mg, S, Al; while Cd concentration in the topsoil around the lake was positively correlated with concentrations of Sc, S, Mn, Al, Fe, K and negatively correlated with the concentration of Na. PCA result showed that dissolved Cd in the lake water might be controlled by salinity, while dissolved Cd in the river water might be controlled by pH and alkalinity; dissolved Cd in the pore water might be controlled by calcium carbonate minerals, while Cd in the topsoil might be originated from natural source. (3) Chemical forms of Cd in the sediment of Lake Qinghai Sequential extraction results showed that Cd bound to Fe-Mn oxides was the main form which accounted for 51.22% of the total content. Residual Cd accounted for 24.12% of the total content. Cd bound to carbonates, organic matter and exchangeable Cd accounted for 15.34%, 4.74% and 4.58% of the total content, respectively. Exchangeable Cd and Cd bound to carbonates which could be used by biota accounted for 19.91% of the total content. (4) Pollution levels of Cd in the sediment and topsoil in/around Lake Qinghai Single factor pollution indexes indicated low risk of Cd in the lake sediment and moderate risk in the topsoil around the lake. Sampling sites with moderate risk accounted for 45.45% and 51.11% of lake sediment sampling sites and topsoil sampling sites, respectively. Indexes of geoaccumulation showed none to moderate risk of Cd in the lake sediment and the topsoil around the lake. Sampling sites with none to low risk accounted for 95.46% and 86.67% of lake sediment sampling sites and topsoil sampling sites, respectively