Automated stations to collect rain and snow have been used for several years to quantify the weekly amount of mercury in rain and snow, and the weekly amount of precipitation, over much of the United States. Data from the Virginia collection sites in central and west-central Virginia are compiled and may be compared constantly to the on-line data reported from all the collection sites. While the sources for mercury in the atmosphere are numerous, most comes from coal-burning electrical power plants. Other locally significant sources of mercury exist, but none are known in central Virginia. Data show that the atmospheric content of mercury increases during prolonged intervals without precipitation (for example, several weeks without any rain or snow), and that the atmospheric content of mercury is exceptionally low following unusually prolonged precipitation events (several days or rain or snow). The regional variations of atmospheric mercury precipitation do not serve to identify any particular source of mercury (i.e., any particular coal-burning power plant), but instead indicate significant mixing of atmospheric mercury.
Mose, Douglas and Metcalf, James
"Mercury Deposition from Rain and Snow in Virginia,"
Proceedings of the Annual International Conference on Soils, Sediments, Water and Energy:
Vol. 15, Article 8.
Available at: http://scholarworks.umass.edu/soilsproceedings/vol15/iss1/8