Measurement and Scaling of Mercury on Soil and Air in a Historical Artisanal Gold Mining Area in Northeastern China.

The Jiapigou gold mine area, located in the upper reaches of the Songhua River, was the first and largest artisanal gold mine once in China, and it used to be prominent in two marking years (1870 and 1974). Jiapigou area had a gold mining history of more than 190 years, which was first opened in 1820. Gold extraction with algamation was applied as the dominant method of excavation from 1940 to 2008, and a total of more than 100 t of gold were extracted from the mine using this method and it was estimated that 100-200 t Hg were released, thus causing severe mercury environmental pollution in the mining area. In the experimental campaigns of this study, in situ air and soil Hg concentrations and air-soil Hg fluxes were measured from April 2009 to December 2011. The results showed that in the study area the total gaseous mercury (TGM) concentration exhibited remarkable spatial and temporal distribution patterns, i.e. the TGM gradually decreased following the increase in distance to gold mining sites in space, and the values in spring, summer and autumn were elevated by 1-2 orders of magnitude in comparison with those in winter. Furthermore, at other sampling sites the total soil mercury (TSM) concentration in spring was higher than that in autumn, except for the contrary laws demonstrated at the Erdaogou mining site. However, in spring and winter the Hg flux between air and soil was under the control of different environmental factors, and the characteristics were clear and distinct. In spring the Hg flux between air and soil was directly under the control of solar irradiation, and the releasing process was predominant with a remarkable positive correlation to solar irradiation. Nevertheless, in winter the Hg fluxes were indirectly under the control of solar irradiation, which caused thermal inversion due to the thick snow cover. The depositing process was predominant and the correlations between Hg flux and air temperature was remarkably negative, and there was a positive correlation between Hg flux and solar irradiation. [ABSTRACT FROM AUTHOR]