会泽某铅锌矿周边农田土壤重金属生态风险评价

为了了解云南会泽某铅锌矿废周边农田土壤中重金属含量及潜在的生态危害程度，利用野外采样与实验室分析相结合的方法，以会泽某铅锌矿周边农田土壤（0-20 cm）为研究对象，分析其中7种的重金属（Cd、As、Pb、Cr、Cu、Zn和Hg）含量，并采用风险评价代码法和Hankanson潜在生态风险指数法评价对重金属污染程度与潜在生态风险进行评价。结果表明：7种重金属都存在超标或污染，其中Pb、As、Cd等的污染较为严重。统计学分析结果表明，Pb、As、Hg、Zn、Cd来源相同，铅锌矿冶炼污染物的排放可能是导致研究区域农田土壤重金属含量升高的主要原因。7种重金属化学形态也不尽相同：在重金属有效态中，Cd的水溶态和可提取态较高（平均值达到31.2%）；Pb、Cu和Zn可还原态、可氧化态这两部分含量较高，两部分之和的平均值分别可达到27.9%、30%和27.2%；Hg、As和Cr的残渣态含量较高，平均值分别为90.4%、72.9%和76.8%。风险评价代码评价结果表明，54.4%的样点Cd为高生态风险，45.6%的样点Cd为中度生态风险；100%的样点Zn为中度生态风险；Cu有41.2%的点位属于低生态风险，58.8%的点位属于中度生态风险；As和Pb主要以低生态风险为主（所占比例分别为92.6%和91.8%）；Hg主要以无生态风险为主（所占97.1%）。Hakanson潜在生态风险指数法结果表明，7种重金属潜在生态危害大小顺序为：Cd（331）〉Hg（127.5）〉Pb（43.6）〉As（14.9）〉Cu（9.3）〉Zn（2.3）〉Cr（2.1）。7种重金属的综合潜在生态风险指数（RI）的范围为58.2-1839.3。11%的采样点处于轻微生态风险程度，27.1%的采样点处于中等生态风险程度，46.3%的的采样点处于强生态风险程度，15.6%的采样点处于很强的生态风险程度。综上所述，该矿区周边农田土壤受到了严重的重金属污染，由此引起的重金属生态风险不容忽视?

Heavy Metal Pollution and Ecological Risk Assessment of the Paddy Soils around A Pb-Zn Mine in Huize Country

In order to investigated the metals concentrations and their potential ecological risks of heavy metals in soil, the concentrations of Cd, Hg, As, Pb ,Cr ,Cu and Zn in the topsoil of paddy fields near a smelting area located in the Hunan province were analyzed by field sampling and laboratory analysis. The experimental data indicate that the soil was seriously polluted by heavy metals, especially by Pb, As, Cd. Additionally, cluster analyses suggested that the study area is influenced by anthropogenic contributions. The chemical speciation analysis of heavy metal showed the available content of Cd mainly existed in exchangeable form （31.2%）. The available content of Pb, Cu and Zn were distributed mainly in acid extractable fractions and Fe/Mn oxide fractions （27.9%, 30% and 27.2%）, and Hg, As, Cr was mainly associated with residual fraction （90.4%, 72.9%and 76.8%）. The results of risk assessment code showed Cd was medium and high risk （45.6%and 54.4%）, Zn was medium risk （100%）, Cu was low and medium risk （41.2% and 58.8%）, Hg was mainly no risk （97.1%）, As and Pb was mainly low risk （92.6% and 91.8%）. The consequence of the average irE for heavy metals is Cd （331）〉Hg （127.5）〉Pb （43.6）〉As （14.9）〉Cu （9.3）〉Zn （2.3）〉Cr （2.1）. The range of the potential ecological risk of soil is 58.2-1 839.3. There are 11%of sites classified as low risk, 27.1%classified as medium risk, 46.3%classified as high risk and 15.6%posed an extremely high risk. The above results indices the research area is presented with an important ecological risk.