Atmospheric gaseous elemental mercury (GEM) concentrations and mercury depositions at a high-altitude mountain peak in south China
China is regarded as the largest contributor of mercury (Hg) to the global atmospheric Hg budget. How- ever, concentration levels and depositions of atmospheric Hg in China are poorly known. Continuous measurements of atmospheric gaseous elemental mercury (GEM) were car- ried out from May 2008 to May 2009 at the summit of Mt. Leigong in south China. Simultaneously, deposition fluxes of THg and MeHg in precipitation, throughfall and litter- fall were also studied. Atmospheric GEM concentrations av- eraged 2.801.51 ngm3, which was highly elevated com- pared to global background values but much lower than semi- rural and industrial/urban areas in China. Sources identifi- cation indicates that both regional industrial emissions and long range transport of Hg from central, south and southwest China were corresponded to the elevated GEM level. Sea- sonal and diurnal variations of GEM were observed, which reflected variations in source intensity, deposition processes and meteorological factors. Precipitation and throughfall de- position fluxes of THg and MeHg in Mt. Leigong were com- parable or lower compared to those reported in Europe and North America, whereas litterfall deposition fluxes of THg andMeHgwere higher compared to Europe and North Amer- ica. This highlights the importance of vegetation to Hg atmo- spheric cycling. In th remote forest ecosystem of China, de- position of GEM via uptake of foliage followed by litterfall was very important for the depletion of atmospheric Hg. Elevated GEM level in ambient air may accelerate the foliar up- take of Hg through air which may partly explain the elevated litterfall deposition fluxes of Hg observed in Mt. Leigong.