Atmospheric mercury in Changbai Mountain area, northeastern China I. The seasonal distribution pattern of total gaseous mercury and its potential sources

An intensive field campaign for the measurement of total gaseous mercury (TGM) concentrations in ambient air was conducted in Changbai Mountain area from 5 August 2005 to 5 July 2006 using an automatic atmospheric mercury analyzer (Tekran 2537A), which was the first time TGM was monitored at a remote area in northeastern China. 99% of the hourly TGM concentrations fell between 1.28 and 9.49 ng m−3 with an annual arithmetic mean of 3.58±1.78 ng m−3, which was significantly elevated compared to values obtained in remote areas of Europe and North America. Seasonal mean TGM concentrations displayed a descending trend as follows: winter, spring, fall, and summer. Compared to spring/winter, TGM concentrations were lower in the summer/fall but the standard deviation (SD) of TGM levels was higher and indicated a correlation with anthropogenic emissions. TGM concentrations showed seasonal differences with respect to meteorological parameters: TGM levels in spring/winter were most correlated with wind speed, and correlated with solar radiation only in the winter, while TGM levels in summer/fall periods were most correlated with air temperature. There was a strong diurnal variation of seasonal TGM with significantly higher concentrations in daytime/nighttime compared to the early morning. The seasonal diel TGM pattern indicated regional biofuel and coal combustion were the primary mercury sources.