Temporal and spatial distributions of total gaseous mercury concentrations in ambient air in a mountainous area in southwestern China: Implications for industrial and domestic mercury emissions in remote areas in China

Spatial and temporal distributions of total gaseous mercury (TGM) concentrations in ambient air were investigated in the Mt. Gongga area (Sichuan province, PR China) from April 2006 to June 2007. The annual geometric mean TGM concentration at the Moxi baseline station was 3.90 ± 1.20 ng m^− 3. Geometric mean TGM concentrations at 14 representative sampling sites during the warm season ranged from 1.60 to 20.1 ng m^− 3 and varied spatially, with levels decreasing between urbanized areas and more remote regions: urban area (U1-U3: 7.76 ± 4.57 to 20.1 ± 15.1 ng m^− 3), town (T1: 4.61 ± 1.15 ng m^− 3) and village (V1-V4: 3.26 ± 0.63 to 8.45 ± 3.06 ng m^− 3), and remote area (R1-R6: 1.60 ± 0.43 to 3.41 ± 1.26 ng m^− 3). Our study suggested that industrial activities, especially non-ferrous smelting activities, were an important source of atmospheric Hg and played a vital role in the regional distribution of TGM. In addition, domestic coal and biomass combustion to heat residential homes were important sources of TGM in densely populated areas during the winter months.