【作者】 谢淑容；

【导师】 彭渤；

【作者基本信息】 湖南师范大学 ， 自然地理学， 2007， 硕士

【摘要】 金属矿床开采过程中排放出来的废石，因富含黄铁矿等多种金属硫化物矿物，在地表风化过程中氧化分解，产生酸性矿排水、释放重金属元素等而对环境产生严重影响。而随着人口的急剧增加和经济的高速发展，人类对矿产资源需求不断增加，(金属)矿山固体废弃物的环境污染问题也越来越突出，其有关的环境地球化学研究成为当前研究的热点之一。本文以湖南省桃江锰矿的响涛源废矿堆为研究对象，通过采集废矿堆废石、矿区周围土壤、水体等样品，借助稀土元素、微量和重金属元素地球化学分析资料，研究了元素在不同样品中的地球化学征。同时，运用质量平衡原理探讨了废矿堆废石中元素的富集和迁移转换机制。结合对矿区环境质量的评价，判定了废矿堆废石风化过程中元素的活动性与矿区环境质量的关系，得出了如下几点主要成果和认识：(1)野外调查和室内实验分析表明，组成废矿堆的废石主要是作为赋矿围岩的黑色页岩，次有少量的碳酸锰矿石。这些废石在表生条件下，正在遭受风化分解。(2)剖面废石与轻度风化废石稀土元素标准化后的分配模式都表现为相似的右倾型曲线，与矿区围岩也大致相同；而微量元素组成上，Sc、Ti、Cr、Ga、Ge、Rb、Y、Cs、Hf、Ta、Nb、Th、REE等元素在两类废石中的平均含量相当；而V、Mn、Co、Ni、Cu、Zn、Ba、Pb、U等重金属元素含量变化较大，且剖面废石中的平均含量大于轻度风化废石，表明了废石风化的时间越长，废石中重金属元素的含量相对富集。(3)风化锰矿石的稀土元素、微量元素和重金属元素地球化学特征与剖面废石、轻度风化废石都有明显区别。(4)剖面废石和轻度风化废石的质量平衡计算显示：剖面中都表现为迁出的元素有Sc、V、Cr，以V的迁移强度最为明显。剖面的第一层(0～60cm处)和第三层(70～95cm处)元素迁出较明显，而下两层(95cm以下)为显著富集层；轻度风化废石中，Sc、V、Cr、Co、Ni、Cu、Zn、Pb、Th、U、Cd等重金属发生了较为明显的迁出，且以V、Zn、U、Cd的迁移程度最强。(5)矿区土壤距废矿堆越近，土壤中重金属含量越高。运用地质累积指数和潜在生态危害指数法对矿区土壤重金属污染的评价结果都显示：废矿堆下垫土综合污染程度最高，Mn、Co、Cu、Pb、Cd是污染强度最大和生态风险最高的元素。(6)矿区地表水中以矿排水的综合污染最为明显，水体中Fe、Mn、Ni、Tl超过国家地表Ⅱ类水质标准；而地下水尚未受到废矿堆的影响。(7)从废矿堆废石中微量重金属元素的总量来看，废矿堆对周围环境已具有潜在的影响。废石中活动性较强的元素，如Co、Ni、Cu、Zn、Cd等在矿区土壤和水体中发生明显富集，有些元素已经构成不同程度的污染。随着废石的风化以及环境条件的改变等，这种影响程度还将日益加剧；另一方面，由于大部分微量重金属未从剖面废石中释放出来，因而对生态环境的影响主要局限在废矿堆周围。更多还原

【Abstract】 Waste rocks produced by mining, are always enriched with pyrite and other sulfides. The oxidation and decomposing of the sulfides may cause the production of acid mine drainage (AMD), and the dispersion of heavy metals. That may take impacts to the environments. With the rapid growth of population and economic development, mineral resources are of great necessarity for human beings. The pollution problems of solid wastes produced by mining are becoming more and more serious, and the relative environmental geochemistry study is being of a hot talk in recently years.Based on literatures and field investigation, the Xiangtaoyuan waste dumps at the Taojiang Mn-ore deposit in central Hunan was selected for this study. The waste rocks of different weathered degrees, the relative soils, and the waters distributed throughout the ming area were sampled during field work in July 2005. Major elements, heavy metals, trace elements and rare-earth elements (REE) of all the samples were analyzed in laboratory using ICP-MS technique. The results were geochemical studied using mass balance principles and other methods, and then the heavy metal contaminations developed on soils and surface waters were evoluted based on understanding the mobility and transformation of all the elements during waste rocks weathering. The quality of soils and surface water of the mining area was assessed based on data of ICP-MS analyzing. The possible relation of heavy metal contamination of soils and surface water to the waste rock pile was investigated. Based on our above investigation, research and discussion, we can offer some information about the study as follows:(1) Observing in the field and the analytic results indicate that: the black shales and rhodochrosite ores make up the main materials of the waste rock dump. The waste rocks were weathering and decomposing during supergene geochemical condition.(2) Waste rocks from selected profile and light weathered waste rocks show similar normalized REE pattern of right-inclined curve as same as wall-rock. The contents of Sc, Ti, Cr, Ga, Ge, Rb, Y, Cs, Hf, Ta, Nb, Th, and REE were considerable in the waste rocks. However, concentrations of V, Mn, Co, Ni, Cu, Zn, Ba, Pb, and U vary in a large range. The higher averaging contents in the waste rocks from selected profile, it indicated that the longer weathering period, the higher contents of heavy metals in the waste rocks.(3) The weathered rhodochrosite ores were differing from other waste rocks in the geochemistry of REE, trace elements and heavy metals.(4) Based on the mass-balance calculation of waste rocks, we conclude that: Sc, V, and Cr were released from waste rocks from selected profile, especially for V. In the profile, most of elements were more activity in the first and third layers but enriched in the downmost two layers. Heavy metals, such as Sc, V, Cr, Co, Ni, Cu, Zn, Pb, Th, U, and Cd were released distinctly in the light waste rocks, and V, Zn, U, Cd for the most.(5) The concentration of heavy metals in the soils increase gradually by getting closer to the mining area. Using the Igeo index and potential ecological risk index assess heavy metals contamination. Both of the results suggested that soils under waste dumps were suffered the most serious contamination, and Mn, Co, Cu, Pb, and Cd show the most heavy contamination and ecological risk.(6) The mine drainage samples show the most obvious contamination, Fe, Mn, Ni, T1 exceed the NationalⅡClass Groundwater Standard, and the underground water was uncontaminated.(7) According to the total contents of heavy metals containing in the waste rocks, we can conclude that waste rock pile have imposed potential harm on surrounding environment. Co, Ni, Cu, Zn, Cd and other heavy metals showing more mobility in the waste rocks, are apparently enriched in soils and water of the mining area. By the change of environmental condition and increasing effect of waste rocks weathering, all above mentioned contamination will become stronger. On the other hand, the negative impact on the ecosystem are mainly surrounding the waste dump, due to most of the heavy metal were not released from waste rocks from selected profile.更多还原