湖南东江湖表层沉积物重金属的空间分布、形态及生态风险

为全面了解东江湖重金属污染状况，于2021年9月对表层沉积物重金属含量和形态进行调查研究，对其污染程度和潜在生态风险进行评价.结果表明，ω（Cd）、ω（Pb）、ω（As）、ω（Cu）、ω（Zn）、ω（Ni）和ω（Cr）分别为：0.40~34.1、14.8~1688、6.99~1155、6.89~280、26.2~1739、6.29~55.4和23.3~44.8 mg ·kg^-1；空间分布极不均匀，Cd、Pb、As、Cu和Zn含量最大值均出现在毗邻瑶岗仙钨矿的站位.有效态金属所占比例较高，弱酸可提取态Cd占总量的46.7%~71.5%；可还原态Pb所占比例为46.8%~67.0%；虽然Cu、Zn、Ni和Cr均以残渣态为主要形态，但有效态占比分别为35%~68%、42%~72%、26%~51%和6%~30%.根据地累积指数I_geo，Cd普遍达到中度到重度污染程度，90%站位的Pb处于轻度及以上污染，30%站位的Zn、As和Cu处于轻度污染.潜在生态风险指数E_rⁱ显示，Cd存在较高及以上级别的潜在生态风险，其中80%调查站位的Cd具有极高的潜在生态风险；此外，毗邻瑶岗仙矿区的S7站位的As和Pb存在极高潜在生态风险，Cu存在中等潜在生态风险.综合潜在风险指数RI显示，所有调查站位均存在较高及以上程度的潜在生态风险，50%的调查站位存在极高的潜在生态风险.因此，东江湖表层沉积物存在严重的Cd、Pb、As、Cu和Zn等的复合重金属污染，生物有效性较高，存在很高的潜在生态风险.

Spatial Distribution, Speciation, and Ecological Risk Assessment of Heavy Metals in Surface Sediments of Dongjiang Lake, Hunan Province

To understand the heavy metal pollution status of Dongjiang Lake, the contents and species of heavy metals in the surface sediments were investigated during September 2021, and the heavy metal pollution level and potential ecological risk were evaluated. The results showed that Cd, Pb, As, Cu, Zn, Ni, and Cr contents were in the range of 0.40-34.1, 14.8-1688, 6.99-1155, 6.89-280, 26.2-1739, 6.29-55.4, and 23.3-44.8 mg·kg^-1, respectively, with extremely uneven spatial distributions. The highest contents of Cd, Pb, As, Zn, Cu, and Ni were found in the site adjacent to Yaogangxian tungsten ore. The proportion of metal species with bioavailability was high, in which Cd in acid-soluble species was 46.7%-71.5% and Pb in reducible species was 46.8%-67.0%. The bioavailable species of Cu, Zn, Ni, and Cr were 35%-68%, 42%-72%, 26%-51%, and 6%-30%, respectively, although they primarily existed in residual species. According to the geo-accumulation index (I_geo), there was a moderate or extreme pollution status of Cd in all sites, moderate or extreme pollution status of Pb in 90% of sites, and moderate pollution status of As, Cu, and Zn in 30% of sites. The ecological risk factor (E_rⁱ) of Cd showed high potential ecological risk in all sites with significantly high potential ecological risk in 80% of sites. Moreover, As and Pb had significantly high potential ecological risk, and Cu had moderate potential ecological risk in S7, which was adjacent to Yaogangxian tungsten ore. There was a high total potential ecological risk in all sites and significantly high potential ecological risk in 50% of sites. Therefore, the surface sediments of Dongjiang Lake were under the combined pollution of Cd, Pb, As, Zn, and Cu with high bioavailability and high total potential ecological risk.