The importance of volcanic emissions for the global atmospheric mercury cycle

Mercury is a highly volatile, bioaccumulating toxic trace metal with a long (∼1 yr) atmospheric residence time. Hg is strongly enriched in volcanic emanations, and volcanoes are the only natural sources of direct Hg emission to the free troposphere and stratosphere. However, there is considerable uncertainty over the annual emission rate of mercury from volcanoes. Previous estimates, based on limited measurements from volcanic plumes, span three...