| 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. |
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