Atmospheric mercury in Changbai Mountain area, northeastern China Ⅱ. The distribution of reactive gaseous mercury and particulate mercury and mercury deposition fluxes

摘要

Reactive gaseous mercury (RGM) and particulate mercury (Hgp) concentrations in ambient air from a remote site at Changbai Mountain area in northeastern China were intermittently monitored from August 2005 to July 2006 totaling 93 days representing fall, winter-spring and summer season, respectively. Rainwater and snow samples were collected during a whole year, and total mercury (THg) in rain samples were used to calculate wet depositional flux. A throughfall method and a model method were used to estimate dry depositional flux. Results showed mean concentrations of RGM and Hgp are 65 and 77pgm~(-3). Compared to background concentrations of atmospheric mercury species in Northern Hemisphere, RGM and Hgp are significantly elevated in Changbai area. Large values for standard deviation indicated fast reactivity and a low residence time for these mercury species. Seasonal variability is also important, with lower mercury levels in summer compared to other seasons, which is attributed to scavenging by rainfall and low local mercury emissions in summer. THg concentrations ranged from 11.5 to 15.9ngL~(-1) in rainwater samples and 14.9-18.6ngL~(-1) in throughfall samples. Wet depositional flux in Changbai area is calculated to be 8.4 μgm~(-2) a~(-1), and dry deposition flux is estimated to be 16.5~(-2)a~(-1) according to a throughfall method and 20.2 μgrrr~(-2) a~(-1) using a model method.