珠江流域上游云贵地区农田土壤重金属污染状况及其风险性分析

为探明珠江流域上游云贵地区农田土壤重金属污染水平及其潜在生态风险，在珠江水系上游南盘江流域的云南省曲靖市沾益区废弃磷肥厂工业区（ZY）和陆良县历史铬渣堆放点及冶炼工业区（LL）、个旧市鸡街镇铅锌冶炼厂（JJ）和大屯镇松树脚矿区（DT）、北盘江流域的贵州省六盘水市杉树林铅锌矿区（SSL）、都柳江流域的贵州省黔南布依族苗族自治州乌龙沟铅锌矿区（WLG），采集不同工矿污染源及不同土地利用类型影响下的42个水田土样及63个旱地土样，运用单因子指数法及内梅罗综合指数法分析了土壤重金属富集特征，利用Hakanson潜在生态危害指数法进行了潜在生态风险评估。结果表明： 6个采样地区土壤均污染严重，含量超标率分别为Cd（95.24%） > As（53.33%） > Pb（42.86%） > Zn（30.48%） > Cu（26.67%） > Cr（12.38%） > Hg（6.67%） > Ni （5.71%）。综合污染指数结果表明6个采样区土壤均为重度污染水平，污染程度为JJ > SSL > DT > LL > ZY > WLG，以南盘江中游个旧地区最为严重。6个采样区土壤重金属潜在生态危害风险指数（RI）大小依次为JJ > DT > SSL > LL > ZY > WLG，其中JJ地区土壤达极高等潜在风险，SSL、LL、DT地区土壤存在高等潜在风险，ZY及WLG地区则为中高等潜在风险水平，重金属Cd对潜在生态风险评价贡献最大，其次为Hg。因此，对珠江上游地区矿区周边农田土壤进行管控时不仅要注意Cd污染，还应注意Hg、As等元素的富集程度及潜在污染风险。

Soil heavy metal pollution and risk assessment of agricultural soils in the Yunnan-Guizhou area, Upper Pearl River Basin

To obtain a better overview of the status and potential ecological risks of heavy metal pollution in agricultural soils in the YunnanGuizhou area in the upper reaches of the Pearl River Basin, 42 paddy soils and 63 dry land soils were collected from six industrial and mining sites in this area, including(1)an abandoned phosphate fertilizer plant industrial area in Zhanyi District(ZY), Qujing City, Yunnan Province;(2)a historical Cr slag storage area and smelting industrial area in Luliang County(LL), Qujing City, Yunnan Province;(3)a Pb and Zn smelter in Jijie Town(JJ), Gejiu City, Yunnan Province;(4)the Songshujiao mining area in Datun Town(DT), Gejiu City, Yunnan Province;(5)the Shanshulin Pb-Zn mining area(SSL)in Liupanshui City, Guizhou Province; and(6)the Wulonggou Pb-Zn mining area (WLG)in Qiannan Boeyi and Miao Autonomous Prefecture, Guizhou Province. The single factor pollution index, Nemero integrated pollution index, and Hakanson potential ecological risk index were used for the evaluation of potential environmental risks of heavy metals in these soils. The results showed that the soils from the six sites were mostly heavily contaminated. Compared with the national standard values, the rates of exceedance of the standards followed the order of Cd(95.24%) > As (53.33%) > Pb (42.86%) > Zn (30.48%) > Cu (26.67%) > Cr(12.38%) > Hg(6.67%) > Ni(5.71%). The integrated pollution indexes suggested that the six sites were all exposed to heavily integrated pollution with the order of JJ > SSL > DT > LL > ZY > WLG, and the sites from Gejiu in the middle reaches of the Nanpan River were the most severely contaminated. The potential ecological risk index of soil heavy metals in the six sites followed the sequence of JJ > DT > SSL > LL > ZY > WLG. These metals posed a very high potential risk in JJ, a high potential risk in SSL, LL, and DT, and a medium/high potential risk in ZY and WLG. Among the metals, Cd was the most important risk factor, followed by Hg. Therefore, in addition to Cd pollution, Hg, As, and other trace elements should be taken into consideration for the soil management and control in the upper reaches of the Pearl River Basin.