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

Denkenberger, Joseph S.; Driscoll, Charles T.; Branfireun, Brian A.; Eckley, Chris S.; Cohen, Mark; Selvendiran, Pranesh

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

2012

Rates of surface-air elemental mercury (Hg⁰) 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 Hg⁰ 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 greatest contributors to annual evasion for the basin are agricultural (∼55%) and forest (∼25%) land cover types, and the open water of the Great Lakes (∼15%). Areal evasion rates were similar across most land cover types (range: 7.0–21.0 μg/m²-yr), with higher rates associated with urban (12.6 μg/m²-yr) and agricultural (21.0 μg/m²-yr) lands. Uncertainty in these estimates could be partially remedied through a unified methodological approach to estimating Hg⁰ fluxes.

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