In situ measurement of total gaseous mercury (TGM) and mercury exchange fluxes between soil with different utilization patterns and atmosphere was conducted at one typical agricultural region in Three Gorges Reservoir. The TGM concentration ranged from 2.67 to 75.5 ng·m-3 with the average of (6.26±8.11) ng·m-3, higher than the global background value. An obvious seasonal variation of TGM was observed, and the TGM values in spring and winter were significantly higher than those in summer and autumn. It was found that the mercury fluxes varied from different landscapes with the emission fluxes at three land use types following the trend:rainfed cropland >paddy field >forest land. Seasonal variations of mercury emission were obvious with highest fluxes in summer and lowest in winter, while the highest daily mercury emission fluxes appeared at midday. Mercury emission fluxes in our study region were mainly controlled by air and soil temperature, humidity, light and ultraviolet, and the air temperature and ultraviolet were regarded as the main factors. The influence of Hg level in soil on Hg emission was not obvious in the presence of environmental factors and agricultural activity.
Keywords: Three Gorges Reservoir; agricultural environment; mercury emission; total gaseous mercury.