万山汞矿区地表与大气界面间汞交换通量研究

Mercury Exchange Fluxes Between Air and Soil Interface over Different Type of Land in Wanshan Hg Mine Area

采用动力学通量箱与高时间分辨率大气自动测汞仪联用技术对万山汞矿区不同季节、不同地表与大气界面间汞交换通量和大气汞含量进行了测定．结果显示，受人为活动和地表强烈释汞的影响，万山地区大气汞含量高出背景区1～3个数量级，在冶炼厂附近平均值可达1101．8ng／m^3，最低平均值达17．8ng／m^3，显示万山汞矿区已遭受较严重的大气汞污染．万山汞矿区土壤与大气界面汞交换非常强烈，土壤向大气的释汞通量最高可达27827ng／（m^2·h），大气汞干沉降通量最高可达9434ng／（m^2·h）．万山汞矿区土壤与大气汞交换通量主要受光照强度、大气汞含量影响，光照在土壤释汞过程中起促进作用，而较高的大气汞含量则抑制了土壤向大气的释放，并导致大气汞强烈的干沉降，不同的地表类型对地表释汞影响较大，植被覆盖土壤释汞通量显著低于无植被覆盖地区，而冶炼后的矿渣堆则成为大气汞的净源。

Air/soil Hg exchange fluxes were measured using field chamber-automated air mercury analyzer method over different land in Wanshan Hg mine area in two seasons. The results showed that the air/soil Hg exchange fluxes were very strong. The highest Hg emission flux from soil was 27 827 ng/（m^2· h）, the highest Hg deposition flux from the atmosphere was 9 434 ng/（m^2· h）. Because of Hg emission from anthropogenic activities and natural lands, the Hg concentrations in air in Wanshan Hg mine area are 1 -3 orders of magnitude greater than background area. The highest average Hg concentration in air reached 1 101.8 ng/m^3, and the lowest average Hg concentration in air still reached 17.8 ng/m^3. These indicated that the atmosphere was polluted seriously in Wanshan Hg mine area. The Hg exchange fluxes are influenced by solar irradiation and the Hg concentrations in air. The solar irradiation accelerates the Hg emission from soil. Conversely, the Hg concentration in air restrained the Hg emission from soil, and even leads the Hg concentration depositing to soil surface. The Hg emission fluxes from uncovered soil are higher than that from covered soil by vegetations significantly. And the slag becomes net atmospheric Hg source.