A synthesis of rates and controls on elemental mercury evasion in the Great Lakes Basin

Abstract

Rates of surface-air elemental mercury (Hg o ) fluxes in the literature were synthesized for the Great Lakes Basin (GLB). For the majority of surfaces, fluxes were net positive (evasion).Digital land-cover data were combined with representative evasion rates and used to estimate annual Hg o evasion for the GLB (7.7 Mg/yr). This value is less than our estimate of total Hg deposition to the area (15.9 Mg/yr), suggesting the GLB is a net sink for atmospheric Hg. The

Using foliar and forest floor mercury concentrations to assess spatial patterns of mercury deposition

“…Several studies have suggested that atmospheric Hg 0 is the primary form of Hg that is incorporated into leaf tissue (Rea et al, 2002;Ericksen et al, 2003;Bushey et al, 2008), and Hg 0 is estimated to make up almost 60% of anthropogenic atmospheric emissions of Hg in the northeastern United States Denkenberger et al, 2012). Hg 0 is also relatively stable in the atmosphere and capable of being transported long distances from sources (Fitzgerald et al, 1998;Driscoll et al, 2013).…”

Soil mercury and its response to atmospheric mercury deposition across the northeastern United States

“…The considerable discrepancy between the current total pools of soil Hg and the possible atmospheric Hg inputs over the period of soil formation (e.g., for 15k years, 140 mg/m 2 ) might be explained by the different immobilization capacities of soil at different stages of formation. A large fraction of deposited Hg is currently evaded back to the atmosphere (Denkenberger et al 2011). Conditions that affect the dynamics of SOM, which include climate, land-use change, and landscape disturbance therefore are likely, to a large extent, drive the spatial patterns of concentrations and pools of soil Hg.…”

“…In forest ecosystems, overstory canopies substantially enhance atmospheric Hg deposition via litterfall and throughfall deposition (St. Louis et al 2001, Demers et al 2007, Risch et al 2011. Elemental Hg (Hg 0 ) can be volatilized from land and water into the atmosphere, thus the transfer of Hg between the atmosphere and Earth surfaces is bidirectional (Denkenberger et al 2011).…”

Soil–Air Mercury Flux near a Large Industrial Emission Source before and after Closure (Flin Flon, Manitoba, Canada)

“…29,42 Similarly, the magnitude of fluxes measured at this site were within the typical range of North American background forests (0 to 1.4 ng m −2 h −1 ). 43 In contrast, the daily average fluxes measured near the HBMS smelter during its operation showed net Hg 0 deposition: −3.8 ng m −2 h −1 ( Figure 4B). This is noteworthy because the soil had a much higher Hg concentration (75 μg g −1 ) compared to that of the background reference location (0.20 ± 0.05 μg g −1 ) where net emissions were measured.…”

“…Applying an average literature value for emissions from boreal forest waterbodies (0.9 ng m −2 h −1 ) 43 and adding this to the soil emissions results in a total landscape flux of 95 kg per year within the 50 km radius of the smelter. Applying a background waterbody flux value for this region is consistent with data showing that the water Hg concentrations in the Flin 49 The emissions from the high-Hg-content soils close to the smelter had much higher average fluxes compared to the fluxes over the entire impacted area (the mean flux within a 4 km radius of smelter was 29 ± 10 ng m −2 h −1 compared to the mean within 50 km of the smelter, 1.8 ± 0.6 ng m −2 h −1 ).…”