Atmospheric mercury emissions from substrates and fumaroles associated with three hydrothermal systems in the western United States

This paper quantifies atmospheric mercury (Hg) emissions from substrates and fumaroles associated with three hydrothermal systems: Lassen Volcanic Center, California (LVC); Yellowstone Caldera, Wyoming (YC); and Dixie Valley, Nevada (DV). Substrate Hg fluxes were measured using field chamber methods at thermal and nonthermal sites. The highest Hg fluxes (up to 541 ng m−2 h−1) were measured at thermal active areas. Fluxes from altered and unaltered nonthermal sites were <10 ng m−2 h−1 and were comparable to those measured in natural low-Hg background regions for YC and DV, and at LVC they were slightly elevated. Similarly, reactive gaseous mercury concentrations were higher in thermal active areas. Using a Geographic Information System [...]