Characterization of atmospheric mercury at a suburban site of central China from wintertime to springtime

Atmospheric mercury exits primarily as gaseous mercury and particulate mercury (PHg). Change in the species of atmospheric mercury will pose significant impact on the biogeochemical process of mercury. Here total gaseous mercury (TGM) and total particulate mercury (TPM) were measured from heating season in wintertime to springtime with frequent dust storm during February to May 2009 in the suburban of Hefei, central China, where atmospheric mercury measurements were completely absent. The average concentrations of TGM and TPM were 2.57 ± 1.37 ng/m3 and 0.32 ± 0.10 ng/m3, respectively. Variations in the TGM were affected by both emissions and meteorological parameters. In the heating period (February), due to coal combustion TGM concentrations were significantly higher than those in the spring (March, April and May). A clear different diurnal variation in TGM concentration was also observed both in late winter and in spring, accompanying with the advance of sunrise. The percentage of total particulate mercury (TPM) in total atmospheric Hg ranged from 5.8%–19.2%, with relatively high levels appeared in March and April. PHg was mainly derived from direct emissions by coal combustion in February and May, while it was dominated by transformation from gaseous Hg on particles in March and April due to dust storms, which may result in more deposition of mercury to ecosystem.