MOE Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China.
State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
Sci Total Environ. 2019 Dec 10;695:133893. doi: 10.1016/j.scitotenv.2019.133893. Epub 2019 Aug 12.
Abandoned tailings are one of the most important sources of heavy metal pollution in the areas surrounding mining districts, and significant leaching of heavy metals could be brought by precipitation. This study investigated the leaching of heavy metals from the tailings of a small-scale abandoned polymetallic mine in south China by rainwater with batch and column tests and evaluated the associated environmental impact. The mean contents of Cr, Ni, Cu, Zn, As, Cd, and Pb in the un-weathered mine tailings were 1.46×10, 3.11×10, 4.10×10, 2.18×10, 2.82×10, 5.65×10, and 8.74×10mg/kg, respectively, and appreciable fractions of Cd, Zn, Cu, and Cr in the tailings were present in the acid soluble form. Batch and column leaching tests consistently showed that significant quantities of heavy metals could be released from the mine tailings. Based on the results of column leaching tests, it was estimated that the average fluxes of Cr, Ni, Cu, Zn, As, Cd, and Pb from the mine tailings at the studied mining district leached by precipitation were 3.20, 38.3, 12.5, 1.52×10, 104, 1.08, and 9.26g/ha/yr, respectively. The metal-rich tailing leachate would impact the quality of surface water and soils downhill of the mining district, and pose significant potential ecological risk to the farmland soils, which are irrigated by local surface water. These findings indicate the importance of tailings as a source of heavy metals in the mining districts of south China with heavy precipitation, as well as the need for mitigating the releases of heavy metals and the associated environmental impact from abandoned mine tailings.
废弃尾矿是矿区周边重金属污染的最重要来源之一，降水会引发大量重金属浸出。本研究采用批量和柱浸试验，调查了中国南方小型废弃多金属尾矿在雨水作用下重金属的浸出情况，并评估了相关的环境影响。未风化尾矿中 Cr、Ni、Cu、Zn、As、Cd 和 Pb 的平均含量分别为 1.46×10、3.11×10、4.10×10、2.18×10、2.82×10、5.65×10 和 8.74×10mg/kg，尾矿中相当一部分 Cd、Zn、Cu 和 Cr 以酸可溶形式存在。批量和柱浸试验均表明，大量重金属可从尾矿中释放。根据柱浸试验结果估算，研究矿区受降水淋滤的尾矿中 Cr、Ni、Cu、Zn、As、Cd 和 Pb 的平均通量分别为 3.20、38.3、12.5、1.52×10、104、1.08 和 9.26g/ha/yr。富含金属的尾矿浸出液会影响矿区下游地表水和土壤的质量，对当地地表水灌溉的农田土壤造成重大的潜在生态风险。这些发现表明，在中国南方多雨矿区，尾矿作为重金属的来源十分重要，需要减轻废弃尾矿中重金属的释放及其相关的环境影响。
