Atmospheric Mercury Emissions and Speciation at the Sulphur Bank Mercury Mine Superfund Site, Northern California

Abstract

One pathway for release of mercury (Hg) from naturally enriched sites is emission to the atmosphere. Elemental Hg, when emitted, will enter the global atmospheric pool. In contrast, if reactive gaseous Hg or Hg2+ (as HgCl2, HgBr2, or HgOH2) is formed, it will most likely be deposited locally. This study focused on the measurement of elemental Hg flux and reactive gaseous Hg concentrations at the Sulphur Bank Superfund Site, an area of natural Hg enrichment with anthropogenic disturbance and ongoing geothermal activity. Mean Hg emissions ranged from 14 to 11000 ng m(-2) h(-1), with the highest emissions from anthropogenically disturbed materials. Reactive gaseous Hg concentrations were the highest ever reported for a natural setting (0.3-76 ng m(-3)). Measured Hg fluxes were used within a Geographic Information System to estimate mercury releases to the atmosphere from the site. Results indicated approximately 17 kg of Hg y(-1) of is emitted to the atmosphere from the 3.8 km2 area, with half from mine waste, ore, and tailing piles and half from relatively undisturbed naturally enriched substrate.

A laboratory based experimental study of mercury emission from contaminated soils in the River Idrijca catchment

“…During sample processing by regulating various parameters, a wide range of MEFs was measured from less than 2 to 530 ng m −2 h −1 . These MEF values significantly exceed those reported for unaltered or background sites Nacht and Gustin, 2004) and are comparable to those measured worldwide in areas of Hg mine waste and …”

“…In recent years, considerable progress in understanding mercury geochemistry at such sites has been made with the development of interfacial mercury flux measurement technology (Ferrara et al, 1998a;Ferrara et al, 1998b;Gustin et al, 1996;Nacht et al, 2004;Gustin, 2003;Engle et al, 2001). Mercury emission rates from these Hg-enriched areas were found to be greater than previously estimated, indicating that these sources may be more significant contributors of mercury to the atmosphere than previously realized (Gustin et al, 2000;Gustin, 2003;Engle et al, 2001;Wang et al, 2005, Wang et al, 2007a, Wang et al, 2007bCoolbaugh et al, 2002;Feng et al, 2005).…”

Global observations and modeling of atmosphere–surface exchange of elemental mercury: a critical review

“…Overall, the MM fluxes showed highly dynamic temporal variability while the DFCs followed a grad- ual diel cycle similar to those for temperature and solar irradiance. REA observed a broader flux distribution similar to NH 3 and CH 4 fluxes observed by MM techniques (Beverland et al, 1996;Moncrieff et al, 1998;Nemitz et al, 2001). The median fluxes obtained by REA, AGM and MBR were not significantly different (Friedman two-way analysis, χ 2 = 1.29 < χ 2 p=0.05 = 5.99).…”

Aqueous phase methylation as a potential source of methylmercury in wet deposition

“…Hg R in precipitation, largely ionic Hg(II) (Mason et al, 1992), is emitted from natural and anthropogenic sources (Nacht et al, 2004;Lee et al, 2006) and produced by atmospheric oxidation of Hg 0 (Fogg and Fitzgerald, 1979), the rate of which varies spatially depending on the strength and abundance of atmospheric oxidants (Fitzgerald and Lamborg, 2003). Hg(II) is scavenged by particles (Lamborg et al, 2000), and as noted, levels of Hg R in precipitation are highly dependent on the concentration and nature of particulate material.…”