采矿活动对煤矿区土壤中重金属污染研究

HEAVY METALS IN SOIL CONTAMINATED BY COAL MINING ACTIVITY

以国家亿吨煤建设基地、已有百年开采历史的淮南矿区为例 ,研究长期采矿活动 (尤其是煤矸石堆积 )造成的矿区土壤重金属污染。从不同开采历史的 3个矿井区 (大约分别为 10 0、5 0、2 5年 )选择 4条土壤采样线 ,系统采集煤矸石堆附近的土壤样品 ,使用美国IRISIntrepid电感耦合等离子体全谱直读光谱仪对土壤中主要有害元素 (Cu、Ni、Pb、Zn、Sn、Cr、Co)进行分析 ,用土壤标样 (GBW0 74 0 3)控制分析质量。采用元素富集系数法 (Al为参比元素 )来评价重金属的富集水平。研究结果表明 :矿区土壤已表现来自采矿活动的重金属污染贡献 ,且具有累积性。不同矿井区土壤中重金属含量呈现随开采历史及堆积煤矸石风化时间长而递减的趋势 ,且Co、Cu、Zn、Ni、Pb表现相对较强的迁移性 ,其含量在部分矿井区土壤中超过国家土壤一级污染标准。但矿区土壤中分析的重金属元素均未超过国家土壤二级污染标准 。

Huainan with a 100-year coal-mining history is an important coal-production base of the country in East China, turning out 100 million tons of coal annually. A case study on heavy metals in soil contaminated by mining activity was conducted through the investigation of four soil sampling routes through 3 coal-mining areas different in mining history (about 100, 50 and 25 years, respectively). Soil samples were taken systematically from the lands nearby the gangue dumps. Heavy metals (Cu, Ni, Pb, Zn, Sn, Cr, Co) in the soils were analyzed by IRIS Intrepid Inductively coupled plasma-atomic emission spectrometry (ICP-AES) in the Institute of Soil Science, CAS, and certified soil samples (GBW07403) from the China Geological Survey were used for analytical quality control. The results were validated with respect to accuracy and precision. The heavy metals in the soil nearby gangue dumps were mainly attributed to weathering and leaching of the coal-gangues. The results show that coal mining activities contribute greatly to heavy metal pollution of the soil and the metals accumulate. Moreover, the concentration of heavy metals decreases with the history of mining and weathering of the gangue, showing their high mobility, especially with. Co, Cu, Zn, Ni, and Pb. Their contents in some soil were higher above the first-grade criteria for soil pollution established by the SEPA. However, none of them surpass the second-grade criteria, indicating that the translocation of the heavy metals from the gangue damps to their surrounding soils is a slow process.