Atmos. Chem. Phys. Discuss., 13, 12177-12211, 2013
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Atmospheric mercury concentration and chemical speciation at a rural site in Beijing, China: implication of mercury emission sources
L. Zhang1, S. X. Wang1,2, L. Wang1, and J. M. Hao1,2
1State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China
2State Environmental Protection Key Laboratory of Sources and Control of Air Pollution Complex, Beijing 100084, China

Abstract. Continuous measurements of atmospheric mercury concentration and speciation play a key role in identifying mercury sources and its behavior in the atmosphere. In this study, speciated atmospheric mercury including gaseous elemental mercury (GEM), reactive gaseous mercury (RGM) and particle-bound mercury (PBM) were continuously measured at Miyun, a rural site in Beijing, China from December 2008 to November 2009. The average GEM, RGM and PBM concentrations were found to be 3.22 ± 1.74 ng m−3, 10.1 ± 18.8 pg m−3 and 98.2 ± 112.7 pg m−3, respectively, about 2–20 times of the background concentration of Northern Hemisphere. The results indicated that atmospheric mercury concentrations in North China were highly affected by anthropogenic emissions. The atmospheric mercury showed obvious seasonal variations with the highest seasonal average GEM concentration in summer (3.48 ng m−3) and the lowest value in winter (2.66 ng m−3). In autumn and winter a diurnal variation of GEM was observed with peak levels in late afternoon till midnight. Most of the high RGM concentration values occurred in the afternoon of all seasons due to the higher oxidation. The PBM concentration was higher in early morning of all seasons because of the atmospheric stratification during nighttime against laminar fluxes during daytime. The ratio of GEM to CO indicates that residential boilers play an important role in the elevation of GEM in winter. The ratio of RGM to O3 could be an indicator of the contribution of local primary sources. The ratio of PBM to PM2.5 reveals that the air mass from east and southwest to the site in spring and summer carries more atmospheric mercury. The HYSPLIT back-trajectory analysis indicated that the monitoring site is affected by local, regional and interregional sources simultaneously during heavy pollution episodes. The results from the potential source contribution function (PSCF) model indicate that the atmospheric transport predominantly from the northwest contribute to the elevated atmospheric mercury in winter and autumn, while the North China Plain (NCP) Region and the north part of Yangtze River Delta (YRD) Region are the major source areas for mercury pollution in spring and summer.

Citation: Zhang, L., Wang, S. X., Wang, L., and Hao, J. M.: Atmospheric mercury concentration and chemical speciation at a rural site in Beijing, China: implication of mercury emission sources, Atmos. Chem. Phys. Discuss., 13, 12177-12211, doi:10.5194/acpd-13-12177-2013, 2013.
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