Characteristics and potential sources of atmospheric mercury at a subtropical near-coastal site in East China

摘要

To evaluate the impact of regionalmercury (Hg) emissions and understand possible source regions of atmospheric Hg in Eastern China, 2 year observation for speciated atmospheric Hg was conducted at the Dameishan Atmospheric Observatory, amountain site near the east coast of China. The observed concentration of total gaseous Hg (TGM) was 3.3 ± 1.4 ngm~(-3). During the sampling period, gaseous oxidized Hg and particulate bound Hg were 6.7 ± 4.3 pgm~(-3) and 180 ± 110 pgm~(-3) in winter and 5.9 ± 3.4 pgm~(-3) and 130 ± 100 pgm~(-3) in spring, respectively. The relatively high mean concentration of TGM was mainly caused by regional anthropogenic emissions and occasional long-range transport from domestic source regions. Seasonal variation in the TGM concentration was observed with lower values in the wet monsoon season (from May to September) and higher values in the dry monsoon season (from October to April). Backward trajectories and potential source contribution function analysis suggested that anthropogenic Hg emission from coal combustion in the Yangtze River Delta region was the most likely cause for the elevated TGM concentrations. Relatively clean air originating from the East China Sea was the most possible cause for the observed low TGM concentrations. Positive correlation between TGM concentration and air quality index suggests that emissions that influenced regional air quality contributed to the elevated TGM concentrations.