1.Xi''an Center of Mineral Resources Survey,China Geological Survey;2.Institute of Mineral Resources, Chinese Academy of Geological Sciences
【研究目的】栾川县是我国典型钼矿集中开采区，查清钼矿区周边农田土壤重金属污染状况对区域环境污染防治、矿山生态修复以及矿业可持续发展具有重要意义。【研究方法】在典型钼矿区周边赤土店镇范围内农田采集表层土壤样品54件，分析其重金属Cd、Cu、Zn、Pb、Hg、As、Cr、Ni含量及空间分布特征，采用地累积指数法、潜在生态风险指数法、健康风险指数法开展重金属污染评价、生态风险及健康风险评估。【研究结果】研究区农田土壤中Cd、Cu、Zn、Pb含量平均值超过农用地土壤污染风险筛选值，是区域农田土壤主要污染重金属元素，As仅个别点位超标，Hg、Cr、Ni未超标；空间分布特征显示：钼矿开采集中区较近的A区是Cd、Cu、Zn、Pb含量高值的主要分布区，随着距离的增大，到B区和C区，含量呈逐渐降低趋势，元素超标率A区> B区> C区；以河南省表层土壤背景值为标准，Hg、As、Cr、Ni地累积指数平均值均小于1，表现为无污染至轻污染，Cd、Cu、Zn、Pb污染较为严重，Cd达到中污染至重污染，Cu、Zn、Pb主要为轻污染至重污染水平，污染程度Cd > Pb > Zn > Cu，其中A区污染程度最高，B区次之，C区相对较低；重金属潜在生态风险以轻微生态风险为主，少量为中等生态风险，其中A区潜在生态风险高于B区和C区，以Cd元素最为突出；研究区农田土壤中各元素非致癌健康风险指数均小于1，从大到小依次为Cr > As > Pb > Ni > Cd > Cu > Zn > Hg，致癌健康风险指数均小于1×10-4，从大到小依次为Ni > Cr >As > Cd，属于可接受风险水平，其中儿童的致癌和非致癌健康风险指数均高于成人。【结论】钼矿区周边农田土壤中Cd、Cu、Zn、Pb存在一定程度的污染，达到中污染至重污染水平，但整体生态风险较低，非致癌和致癌健康风险均在合理范围内，人群受土壤中重金属的影响患癌症和非致癌疾病的风险较低，其中儿童对重金属更为敏感，更容易受到重金属危害，因此需要加强保护。
This paper is the result of geological environment survey engineering. [Objective] Luanchuan County is a typical molybdenum mining area in China. It is of great significance to find out the heavy metals pollution of farmland soil around the molybdenum mining area for regional environmental pollution prevention, mine ecological restoration and sustainable development of mining industry. [Methods] This study systematically investigated and analyzed 54 topsoil samples from the farmland in Chitudian Town around the typical molybdenum mining area, obtained the contents and spatial distribution characteristics of Cd, Cu, Zn, Pb, Hg, As, Cr, Ni, and evaluated the heavy metal pollution, ecological risk and health risk by the geo-accumulation index method, potential ecological risk index method and health risk index method. [Results] Compared with the risk screening values for soil contamination of agricultural land, Cd, Cu, Zn and Pb are the main elements exceeding the standard, As exceeds the standard with a few of samples, and Hg, Cr, Ni are not exceeded; The spatial distribution characteristics show that: Area A where around the molybdenum mining area is the main distribution area with high content of Cd, Cu, Zn and Pb, which decreases gradually with the increase of distance, and the order of over-standard value is area A>area B>area C; According to the values of geo-accumulation index, Hg, As, Cr and Ni are generally pollution-free, and the pollution of Cd is moderate to heavy degree, while Cu, Zn , Pb are light to heavy degree, showing the order of pollution degree are Cd > Pb > Zn > Cu and area A>area B>area C; In terms of potential ecological risk, study area shows slight ecological risk, which area A is higher than that of other areas B and C, and Cd is the most prominent element; The non-carcinogenic health risk index is less than 1, with the order of Cr > As > Pb > Ni > Cd > Cu > Zn > Hg, and the carcinogenic health risk index is less than 1×10-4, with the order of Ni > Cr > As > Cd, which is an acceptable risk level. The carcinogenic and non-carcinogenic health risk indexes of children are higher than those of adults. [Conclusions] There is a certain degree of heavy metals pollution of Cd, Cu, Zn and Pb in the farmland soil around the molybdenum mining area, reaching the degree of medium pollution to heavy pollution, but the overall ecological risk is low, and the risks of non-carcinogenic and carcinogenic health are within a reasonable range. The risk of people suffering from cancer and non-carcinogenic diseases due to the influence of heavy metals in the soil is low. Children are more sensitive and vulnerable to heavy metals, so it is necessary to strengthen protection.