| Mercury is a global pollutant with persistent, toxic and bioaccumulative effect, and it’s a serious threat to environmental safety and human health. The mercury mining and smelting activities would result in serious environmental mercury pollution and problems in the mercury mines areabecause generates large quantities of solid waste, continuous discharges lots of waste water, and releases mercury to the surrounding environment Therefore, mercury pollution problems during mining and smelting have caused widespread concern at home and abroad.Mercury is a global pollutant with persistent, toxic and bioaccumulative effect, and it’s a serious threat to environmental safety and human health. In the production process, resulting in serious environmental mercury pollution in the mercury mines area, causing many environmental problems. Mainly reflected in the mining, dressing, smelting process, the mercury mines continuous discharges large numbers of the "three wastes "(solid waste, waste water, waste gas), and releases mercury pollution to the surrounding environment; solid waste destructs the ecological environment, Also seriously pollute the surrounding soil, water and air and other environmental media; Under natural conditions, different valence inorganic mercury in the environment will be converted to the more toxic methylmercury and constituted harm to humans. Therefore, the mercury mines mercury pollution problems, has caused widespread concern at home and abroad.This thesis selected Qingtonggou mercury mine in Xunyang Shaanxi Province as a research area, and made survey and sample collection on the the mine surrounding environment field, through data compilation and experimental measurements, analysis of mine mercury pollution, and make evaluation of environmental risks of the mining area, analysis of the potential ecological risk and the health of nearby residents risk of mining mercury pollution on the surrounding environment. Through careful study, the main conclusions are as follows:(1) The mining activity itself caused great mercury emission and release.The total mercury content in the mine waste rock is262.81mg/kg, the total mercury content in the tailings is341.86～379.41mg/kg. The mercury leaching toxic Identification of waste rock and tailings obtained the leaching toxic mercury of waste rock and tailings were lower than the maximum allowable concentration limit of0.1mg/L in the hazardous waste identification standard leaching toxic identify.Total mercury content in the wastewater generated in the production process changes in the range of146.60～5382.00ng/L, pH ranges from7.78to10.16, which showed alkaline. Wastewater generated by the production processes of the mine is basically recycling, but pit water efflux, the average of total mercury content is288ng/L. Under Integrated wastewater discharge standard(GB8978-1996), the maximum allowable emissions of mercury content in the wastewater is50000ng/L, shows that the mine waste water discharges meet the standards.Make conduct on-site monitoring of native mercury production process node shop air, on the whole, all the process node gaseous mercury concentration is much lower than the Ministry of Health workshop air mercury concentration limit (20μg/m3).(2) The surrounding environment was heavily polluted.Total mercury contents of soils in the mercury mine and control areas showed that the levels of total mercury contents in the mine soils is far higher than the control soils, far beyond our soil environmental quality standards (GB15168-1995)1.5mg/kg. The total mercury contents of mercury mine soils is1.53to2085.58mg/kg; the total mercury contents of undisturbed soils (control soils) is0.28-2.58mg/kg; analysis of different land use types of soil, the total mercury contents of vegetable soils is highest than maize soils and paddy soils, far higher than the natural uncultivated soils. That the mercury in the soils may be caused by the following reasons: First, due to higher mercury levels in the mine soils; Second, due to the the mercury mines in mining dressing and smelting process discharge a large number of mercury into the atmosphere, which part of the settlement to soils; Third, The mercury in soils along the zhutong river may also be from the mercury in the water for irrigation. The Zhutonghe river surface water samples collected show a higher total mercury content of29.61～484ng/L, with the average value of315.94ng/L, most of the water samples are more than our surface water environmental quality standards (GB3838-2002) Grade Ⅲ water quality in the mercury content of100ng/L, generally are belonging to Grade IV.Total mercury content in the sediments has a very large range, from24.87to1829.95mg/kg and show that the total mercury content in the sediment decreases with increasing distance from the mine.In the Qingtonggou mercury mine, the atmospheric mercury content range from1to642ng/m3, the most contaminated sites appeare at sites CW1with the values of642ng/m3, which is located at the smelter chimneys export. After analysis, the atmospheric mercury sources may be: First, the exhaust emissions of mercury smelter. Second, the mill crushing, grinding generated dust. Third, the waste rock piles released mercury. Fourth, the mine soils released mercury should also be a source of atmospheric mercury.(3)The total mercury contents in plants samples (mainly vegetables) collected from Qingtonggou mercury mining area ranged from0.33to47.62mg/kg, with an average value of1.92mg/kg. The total mercury contents in the leaves ranged from0.48～20.19mg/kg (dry weight), the total mercury contents in the roots is0.33～47.62mg/kg (dry weight). The total mercury contents of the edible parts of the vegetables samples exceeded the maximum allowable mercury contents(0.01mg/kg) recommended by the Chinese National Agency for vegetables and fruits sources; the total mercury contents in food is0.75to1.74mg/kg, over the maximum allowable mercury contents(0.02mg/kg) recommended by the China National Food Standards Agency of37.5to87times. After analysis the total mercury contents in the crops and the corresponding soils, we derived with the total mercury contents in the plants in addition to the roots to absorb mercury in the soils, another important source is the high atmospheric mercury in the mine area.(4) The potential risk is much higher in the mining area.In this study, make single factor evaluation measure for the mercury pollution of surface water with the National III water quality criteria, the total mercury content in the river water downstream at the0.5km and0.75km in the passing standard line. The zhutong river mercury pollution is serious, we should pay close attention, always pay attention to monitoring the environmental quality status of the river, and to take positive measures to prevent further deterioration of water quality(mercury contamination).We maked single factor evaluation method, potential ecological risk index method and geological cumulative index method of the mining soils and the river sediments. Drawn Regardless of the potential ecological risk assessment methods, most of the soils in the mining area of mercury pollution are heavy or highly contaminated(95%), there is a strong ecological harm; the mercury pollution is serious in zhutong river sediments, there is a strong ecological harm, you should always pay attention to the monitoring of the zhutong river environment quality status, and to take positive measures to prevent the release of mercury accumulated in the sediments into the water, leading to further deterioration of the water quality(mercury contamination).Mining area residents have suffered severe mercury exposure, the major route of exposure is by inhalation, dietary intake and skin contact. Risk assessment indicates, the residents in mercury mine area exposed the highest mercury exposed quantity through consumption of vegetables, it’s up to1.254μg/kg/d, showed a higher risk factor asl.766, the total of the risk factor is2.29. When the risk factor>1, it will likely lead to health risks. So local residents will likely faced the health risks. |
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