离子型稀土矿区及周边土壤中稀土、重金属元素的地球化学特征

20世纪60年代末中国离子型稀土矿在江西赣州首次发现并开采，在长期开采过程中对矿区及周边水土的生态环境问题产生了持续影响，本文选择赣南足洞离子型稀土矿及其周边地区进行了系统的土壤地球化学调查和风险评价。结果表明，土壤中重稀土含量明显高于轻稀土，其中Y含量是全国背景值（22.90 μg/g）的7.2倍，占比最高；地累积指数评价I_geo均值显示HREE和Sm分别有77.44%和99.55%为无污染至中等污染，95.92%的LREE为无污染；重金属除Pb处于轻度-中等污染水平外，As、Cd、Cr、Cu、Hg、Zn、Ni元素均为无污染，与农用地污染风险筛选值相比，样品中重金属的超标率为7.35%，区内土壤重金属生态风险低。统计结果显示稀土含量与重金属污染具有较好的相关性，花岗岩风化壳地质背景对稀土、重金属Pb的控制占主导地位，意味着重稀土含量越高，Pb污染可能越大，因此，在矿山土壤修复中需重视Pb元素的地球化学特征与分布，采用合理的修复技术和手段。 

Geochemical Characteristics of Rare Earth and Heavy Metal Elements in Ion-type Rare Earth Mining Area and Surrounding Soil

In the late 1960s, China's ion-type rare earth ore was first discovered and mined in Ganzhou, Jiangxi Province. In the long-term mining process, it has a continuous impact on the ecological environment of the mining area and the surrounding water and soil. In this paper, the soil geochemical survey and risk assessment of the ion-type rare earth ore in Southern Jiangxi Province and its surrounding areas were carried out.The results showed that the content of heavy rare earth in soil was significantly higher than that of light rare earth, and the content of Y was 7.2 times of the national background value (22.90 μg/g), accounting for the highest proportion.The I_geo mean of geo-accumulation index evaluation showed that 77.44% of HREE and 99.55% of Sm were non-pollution to medium pollution, and 95.92% of LREE was non-pollution.Except for Pb at mild to moderate pollution levels, As, Cd, Cr, Cu, Hg, Zn and Ni were all non-polluting. Compared with the pollution risk screening value of agricultural land, the exceeding rate of heavy metals in the samples was 7.35%, and the ecological risk of heavy metals in the soil was low.The statistical results show that there is a good correlation between rare earth content and heavy metal pollution. The geological background of granite weathering crust dominates the control of rare earth and heavy metal Pb, which means that the higher the content of heavy rare earth is, the greater the Pb pollution may be. Therefore, it is necessary to pay attention to the geochemical characteristics and distribution of Pb elements in mine soil remediation, and adopt reasonable remediation technologies and means.