【作者】 康彧；

【导师】 刘桂建；

【作者基本信息】 中国科学技术大学 ， 环境科学， 2014， 博士

【摘要】 砷是一种广泛存在在自然界的,具有潜在的人体健康风险的元素。在世界大范围内有因饮水和燃煤造成的地方性砷中毒的报道,其中中国是唯一报道的因燃煤造成地方性砷中毒的国家。砷中毒可引起多种组织和器官病变和癌症,对人体有极大的危害。砷在地壳中丰度很低,其富集和赋存极大地依赖于地球化学和地质因素。但由于煤矿开采等活动可将地下煤层赋存的砷运移至地表,并通过煤炭和矸石的堆积过程、煤炭的洗选加工过程和煤炭的燃烧过程将砷释放进入地表环境。由于我国能源格局主要倚重于煤炭,自2011年起煤炭的消耗超过世界总消费一半以上。因此,由煤炭开采、加工和利用活动释放进入环境的砷总量巨大,对地表环境造成深远的影响。在诸多环境载体中,煤矿区受煤矿开采活动的影响最直接、最剧烈,因此研究煤矿区环境中砷的分布、赋存和富集具有重要的意义。本文旨在通过对煤矿区的大量野外采样和测试和对大量文献数据的分析总结,结合双道原子荧光光谱法、拉曼光谱法和显微镜镜下鉴定方法等元素测定方法和矿物鉴定手段,以及逐级提取实验分离测定元素赋存状态等多种直接和间接测定方法,以淮南矿区各煤层原煤、煤矸石、土壤、地表水样品和一系列生物样品,包括蚯蚓、鲫鱼、小麦和水稻中的砷为研究对象,对煤矿区中砷的地球化学分布、赋存和富集状况进行了总结。通过研究主要取得以下几个方面研究成果：(1)中国不同省份煤炭中砷的含量差异巨大,呈从北向南逐渐增加的趋势。总体范围内中国煤中砷的算术平均值为9.70mg/kg,而基于预期储量的加权平均值仅为3.18mg/kg,与其他国家相比处于较低水平。淮南矿区16个煤层中砷的平均含量和基于各煤层储量的加权平均含量为10.81mg/kg和11.12mg/kg,高于前人研究的安徽省煤中砷含量和全国煤中砷含量；(2)煤中砷含量受多种因素的影响,不同成煤时代中砷含量由高到低顺序为三叠纪>第三纪>侏罗纪>石炭纪>二叠纪,不同煤级煤中砷含量由高到低顺序为石煤>褐煤>烟煤>无烟煤；(3)砷在煤中主要以硫化物结合态赋存,但少部分样品中砷的有机态占主导；岩浆岩侵入形成的后生黄铁矿是造成砷富集和赋存的一个重要因素；(4)通过对燃煤电厂大气排放量的估算结果得出,近年来我国因燃煤造成的砷的大气排放持续增加,并且不同行业燃煤释放砷的增长趋势不同。其中工业燃煤造成的砷向大气的排放量自2004年起持续快速增长,生活用煤的砷排放量呈波动增长趋势而燃煤电厂的砷排放量存在持续增长和自2005年下降两种趋势。按照高值计算的总排放量自2004年至2011由570吨持续增长至1046.1吨,由此造成的环境影响是巨大的；(5)矸石在地表的堆积和对塌陷湖的堆砌可造成明显的污染,矸石附近土壤和与矸石接触的地表水体中砷含量明显高于其他土壤和水体。通过对地表环境的分区研究得出开采年限最长的老矿区各环境介质中砷的含量高于年轻矿区,最低的是新矿区,煤矿开采活动的持续对地表环境的影响具有时间累加效应；(6)矿区蚯蚓、鲫鱼、小麦和水稻等生物表现出不同程度的砷富集能力,采矿活动对生态环境的影响较为明显。通过健康风险评价表明,矿区地表水、自产的小麦、水稻和鲫鱼都可产生经口摄入砷产生的高致癌风险。该区的农、渔业应对该区砷的生态污染加以特别的关注。更多还原

【Abstract】 Arsenic is an ubiquitous in the nature with an enormous risk exposure to human beings. Endemic arsenisms caused by arsenic pollution of drinking water and coal combustion are well documented for many places in the world. China is the only country reported, where arsenism is caused by indoor coal burning. Arsenism is extreme hazardous to human health and leads to a variety of tissue and organ diseases as well as cancer. The abundances of As in earth’s crust and coal are very low. Its enrichment and occurrence in coal is dominated by specific geological and geochemical determinants such as mineral constituent, sedimentary environment, coal-forming age and geothermal activity. During coal mining activities As migrates with coal from underground coal seams to the surface. While being piled up, processed and combusted, the coal and coal gangue may release As into the surface environment. Due to the fact that coal is the primary energy source in China, which accounts for more than50%of the world’s coal consumption, the total amount of As released from coal to the environment is remarkably high. As a consequence, the negative impacts on the surface and subsurface environment deserve further concerns. The environments in mining areas are most affected by coal mining activities and environmental investigations on the distribution and accumulation of As in these areas are needed in order to assess the degree of As contamination and to guide later remediation strategies. The aim of this dissertation is to uncover As distribution, modes of occurrence and enrichment statues in coal mining areas by geochemical analyses of raw coal, gangue, soil, surface water samples and a series of bio-samples including earthworm, carp, wheat and paddy rice. Morden determination methods, such as dual channel atomic fluorescence spectrometry (AFS), Raman spectrometry, mineral identification, and sequential extraction experiments for As were carried out for this study. The major results can be summarized as follows,(1) The concentrations of As in coal from different provinces of China vary largely. The concentrations increase gradually from north to south. The average As concentration in Chinese coal and the weighted average based on coal reserves of each province are9.70mg/kg and3.18mg/kg, respectively. Average and weighted average concentration of As in coal of the Huainan coalfield are10.81mg/kg and11.12mg/kg, respectively.(2) The arsenic concentration in coal is influenced by coal-forming age and coal rank. In different coal-forming ages the As concentration follows the order Triassic> Tertiary> Jurassic> Carboniferous> Permian, while in the different coal ranks it follows the order stone coal> anthracite> bituminous> lignite.(3) Sulfide-bound form is the main occurence mode of As in coal, but in few samples the organic-bound form dominates. Epigenetic pyrite formed by magmatic intrusion is very important for As enrichment and occurrence.(4) Arsenic emissions of the whole country caused by coal combustion to the atmosphere increase continuously in the last nine years. The total emission in2011was104.601tons.(5) Gangue piles in the open air may result in As pollution of soil and surface water. Arsenic concentration in soils showed increasing contamination with increasing mining duration. Arsenic accumulation in the environment follows the order old mine area> young mine area> new developed mine area.(6) Bionts in the mining area showed different abilities to accumulate As’. Long-term As pollution of surface water as well as wheat, paddy rice and carp produced in the coal mining area results in a high level carcinogenic risk for the local population due to daily ingestion of local products.更多还原