UC Santa Cruz

Mercury (Hg) is a highly toxic global environmental pollutant because of its ability to bioaccumulate in living organisms and persist in the environment. Hg has been historically mined because of its unique properties and ability to form a gold amalgam. Although direct Hg mining is not as prevalent today, legacy mine waste still remains in many of the historic mining areas and continues to be a source of contamination to the local environment. Mine waste emits gaseous Hg and, with subsequent deposition, contaminates the local environment. However, this atmospheric contamination pathway remains largely understudied in historic mine sites. Thus, this study aims to determine the atmospheric Hg impact on the local environment in the New Almaden Mining District (NAMD), using lichens as a bioindicator. To accomplish this, we first concluded some properties of using lichens as a bioindicator. Then, we determined the Hg emission sources and their spatial distribution. Furthermore, we gained insight into the overall biogeochemical cycling of Hg in NAMD and how lichens may contribute to the contamination through their litterfall. Our data suggest that atmospheric Hg significantly contributes to the contamination of the local environment and reservoirs in NAMD.