| Underground coal fire in China is ranked first in both magnitude and frequency.The mercury emission of underground coal fire has been a great geological disaster,seriously threatening the surrounding ecological environment.This project focuses on the sources and processes of mercury pollution in atmosphere-soil ecological system in the underground coal fire region of Wuda Coalfield,Inner Mongolia.Mercury concentrations in the atmosphere,soil and coal will be measured in order to ascertain the spatial-temporal distribution of mercury in different environmental media and assess the potential risks of regional coal fire mercury emission.In this paper,Lumex RA-915M was used to detect the total mercury in the flue gas from underground coal seam in Wuhushan mining area.The mean concentration of mercury was 49±44 ng/m~3,which was significantly higher than the background value and urban average in China,indicating that underground coal fire is one of the main sources of mercury pollution.In addition,we found a significant correlation between CO and Hg in the flue gas(R~2=0.70),indicating that it is possible to determine and analyze the degree of underground coal fire combustion by monitoring the mercury content in the flue gas in the future.It was found that the average mercury content in the raw coal in Wuda coalfield was 326±214 ng/g,through the analysis of the mercury content of the coal samples from the coal dump and the underground coal seam No.12 in Wuhushan mining area.It is much higher than average mercury content in coal in the world.Mercury concentration in burned coal is much lower than in raw coal,averaging 14.28±6.77ng/g.This suggests that most of the mercury in coal may have been released into the atmosphere in the process of burning coal.Mercury concentrations in soil samples in the study area ranged from 7 ng/g to207 ng/g.We found that the farther away from the coal-burning area,the lower the mercury content in the soil.Therefore,underground coal emissions are likely to be the main source of soil mercury pollution in the region. |
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