【作者】 李小虎；

【导师】 汤中立； 孙柏年；

【作者基本信息】 兰州大学 ， 古生物学与地层学， 2007， 博士

【摘要】 矿山环境问题具有区域性和特殊性，长期以来未受到人们重视，随着经济的快速发展和社会的不断进步，人们生活水平逐步提高，生态环境问题受到越来越多的关注，曾一度为边缘性的矿山环境也开始受到人们的重视。目前，矿山开采、选矿和冶炼等活动引起的环境污染和生态破坏已成为一个全球性的环境地质问题，也是环境地球化学研究的一个重要领域。甘肃省金昌市和白银市是分别以金川铜镍岩浆硫化物矿床和白银铜-多金属硫化物矿床为依托建立的典型矿业城市，是我国重要的有色金属生产基地。然而，近半个世纪以来，对金川和白银矿山开发和选冶造成的生态环境负效应问题缺乏相应的重视和研究。本文通过详细的资料收集、野外采样和室内分析测试，对金川和白银矿山开发所产生的环境问题进行了全面的研究，重点探讨了重金属元素在尾矿、废渣、土壤、水体、沉积物和植物等介质中的环境地球化学特征，揭示了重金属在不同环境介质中的存在形态、释放、迁移和转化规律以及重金属的活动性及其生态环境效应，评价了重金属在土壤、水体和沉积物中的潜在生态危害性，并建立了重金属在不同环境介质中及其之间释放、迁移和转化模式。通过研究取得以下几点认识：(1)金川和白银矿山环境污染问题十分突出，其中金川以大气二氧化硫污染和土壤重金属污染为主，而白银除这两类污染外，矿山酸性排水(AMD)问题尤为突出；污染主要来自废渣、尾矿氧化形成的AMD、冶炼烟尘扩散沉降和矿业废水排放及污灌。(2)尾矿及废渣中重金属含量较高，是重金属释放和AMD形成的主要来源。金川重金属污染物以Cu和Ni为主，白银以Cd、Cu、Pb、Zn为主。重金属化学形态的分析表明，金川尾矿砂中Ni具有很强的活动性，白银尾矿渣中Cd元素活动性最强，显示出对周围环境具有较大的潜在危害性。(3)矿山水体既是重金属污染的直接对象，也是重金属迁移的重要载体。金川水体中以Cu和Ni为主，水体总体呈现中度污染；白银水体总体而言，除Pb元素处于警戒等级之外，其余元素均为严重污染。(4)金川和白银水体沉积物中重金属含量与水体相比均呈现高度富集，金川尾矿坝排污沟中沉积物受尾矿砂淋滤影响，Cu、Ni含量是国家土壤三级标准的十几倍到几十倍，白银东大沟沉积物中Pb、Zn元素最高含量为国家土壤三级标准的20倍，表明水体中重金属大量累积到沉积物中，使其成为具有潜在危害的二次污染源。(5)金川周围土壤中Cu和Ni作为主要污染物，分布在东南和西北两个方向，且污染程度东南大于西北；白银土壤重金属污染主要分布在东和东南方向，整个区域土壤Cd严重超标，长期污灌是导致农田土壤重金属污染的重要原因。土壤重金属化学形态分析表明，金川土壤中元素活动性依次为Ni＞Cu＞Pb＞Zn＞Cr，白银土壤中不同元素的活动性依次为：Cd＞Pb＞Cu＞As＞Zn。(6)采用内梅罗综合污染指数法和潜在生态危害指数法对金川和白银土壤重金属污染进行评价，金川土壤重金属污染生态风险程度总体处于轻微状态，土壤重金属元素潜在危害性(E_r~i)大小依次为：Ni＞Cu＞Cd＞Cr＞Pb＞Zn；白银土壤重金属污染生态风险程度为强度危害，土壤重金属元素潜在危害性(E_r~i)大小依次为：Cd＞Cu＞Pb＞Zn，其中Cd污染处于极强危害程度。(7)通过探讨矿山开发利用过程中重金属的赋存、迁移、转化规律以及不同环境介质中重金属的循环过程、富集机理等，初步建立了大型金属矿山矿业活动引起的重金属释放迁移模式。(8)探讨了矿山生态修复的措施，根据金川和白银的自然条件和矿区污染现状，可以分为三类污染修复区，并将整个修复过程分为三个阶段。通过改善土壤环境质量，初步形成适合植物生长的基本生态条件和结构，进而建立动态平衡的矿区生态系统，实现矿区生态系统的可持续修复。更多还原

【Abstract】 The environmental problems around mine have not been paid much attention for a long time due to its regionality. The living standard has been raised as a result of economic growth and social development, which make the people pay more and more attention to ecological and environmental problems and also to the environmental geologic problems of mine. The environmental pollution and ecological destruction caused by mining and smelting is a global event which has become an important research field for environmental geochemistry.Jinchang city and Baiyin city are the typical mining cities based on exploitation of Jinchuan Ni-Cu magmatic sulfide deposit and Baiyin Cu-multi-metals deposits. They are also the important manufacture bases of nonferrous multi-metals in China. However, in the past half century, eco-environmental problems caused by the mining and smelting of Jinchuan and Baiyin mines were devoid of corresponding recognition and comprehensive study. Through general data collection and the field studies and lab analyses, the study focused on the characteristics of environmental geochemistry of heavy metals in mine tailings, waste dump, soil, water system, sediments and plants.The research reveals that the forms, releasing, migration, transform and mobility in different mediums and their ecological effects. Furthermore, the potential environmental harm of heavy metals on soil, water system and sediments has been assessed. In the end, the releasing, migrating and transforming models of heavy metals among different mediums are constructed. In summary, the dissertation includes the following contents and conclusions:（1） Environmental pollution of Jinchuan and Baiyin is very serious. The SO₂ pollution in the atmosphere and heavy metals contamination are the main pollution problems in Jinchuan. Except for two kinds of pollution above, acid mine drainage （AMD） formed by sulfide minerals oxidation is particularly more serious in Baiyin. The contamination is original from AMD produced by waste slagheap and tailings oxidation, the weathering and atmospheric deposition and pollution irrigation.（2） The concentration of heavy metals in tailings and waste slagheap is very high, which is also the main source of contaminants for heavy metals releasing and AMD forming. Heavy metal contaminations are mainly from Cu and Ni in Jinchuan and Cd, Cu, Pb and Zn in Baiyin. Analyzed results of chemical forms of heavy metals show that Ni in tailings of Jinchuan and Pb in waste slagheap of Baiyin have strong mobility, which suggested that Ni and Pb have the great potential harm to the surroundings.（3） Water bodies in the mines are not only direct objects of heavy metal pollution, but also the important carriers of heavy metal transportation. The water bodies in Jinchuan, mainly containing Cu and Ni, were moderately polluted. While for the water bodies in Baiyin were heavily polluted by all the heavy metals except Pb which was in the alerting level.（4） In contrast to water bodies, the sediments in Jinchuang and Baiyin have more highly concentrated heavy metals. Because of effect of tailings, the concentration of Cu and Ni in Jinchuan is ten to tens times of the third class of National Soil Quality Standard values. The highest concentrations of Pb and Zn in Baiyin is 20 times of the third class of National Soil Quality Standard values, which indicate a great account of heavy metals have deposited from water to sediments which become the potential secondary source of pollution.（5） Cu and Ni as the main soil pollutants in Jinchuan are distributed in southeast and northwest, whose contamination level is greater in the southeast than in the northwest. The soil contamination in Baiyin is distributed in east and southeast, particularly, Cd is seriously contaminated in the whole region due to pollution irrigation. The analysis of chemical forms of soil heavy metals show the mobility of heavy metals in the descending order: Ni>Cu>Pb>Zn>Cr in Jinchuan and Cd>P b>Cu>As>Zn in Baiyin.（6） Ecological risk and heavy metals pollution evaluation using Nemerow index and potential Ecological Risk index show potential ecological risk is light in Jinchuan, but the most dangerous in Baiyin. The Ecological Risk factor in soil of the mine area is Ni, followed by Cu, Cd, Cr, Pb and Zn in Jinchuan and Cd, followed by Cu, Pb and Zn in Baiyin.（7） The releasing and transport models of AMD and heavy metals have been established through the studies of the storage, transport, transformation, and conditions of the mine exploration, as well as the recycling and accumulation of heavy metals in various environmental mediums.（8） The methods for ecological remediation of mines have been discussed. The mines have been classified into three remediation areas and the remediation process has been divided into three steps. By improving the soil environmental qualities, the suitable ecological conditions and structures for plants will be created, the dynamic balance for ecological system of mines will be established, to obtain the sustainable remediation of ecological systems for mine area.更多还原