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Modelling of mercury emissions from background soils.
M T Scholtz1, B J Van Heyst, W H Schroeder
1Canadian ORTECH Environmental Inc., 2395 Speakman Drive, Mississauga, Ont., Canada L5K 1B3. tscholtz@ortech.ca
The Science of the Total Environment
|March 29, 2003
Summary
Natural soils significantly emit mercury, but estimates are rough. A new mercury emission model (MEM) accurately simulates soil mercury exchange, explaining temperature-driven emissions and improving atmospheric mercury flux predictions.
Area of Science:
- Environmental Science
- Atmospheric Chemistry
- Soil Science
Background:
- Soil mercury emissions are a major atmospheric mercury source, but current estimates lack precision.
- Understanding soil processes is crucial for accurate mercury flux scaling.
- Existing models struggle to represent the complex soil-atmosphere mercury exchange.
Purpose of the Study:
- Develop a mercury emission model (MEM) for air-surface exchange.
- Model inorganic mercury partitioning and movement in soils.
- Interpret published mercury emission data using MEM.
Main Methods:
- Developed a multi-layered, dynamic finite-element soil and atmospheric surface-layer model (MEM).
- Simulated heat, moisture, and mercury exchange between soil and atmosphere.
- Included a formulation for the reduction of inorganic Hg(II) to Hg(0).
Main Results:
- MEM accurately simulated meteorological influences on mercury emission fluxes.
- The model successfully explained the correlation between soil temperature and mercury flux.
- Attributed soil temperature-mercury flux correlation to Hg(0) Henry's Law coefficient and diffusion.
Conclusions:
- MEM effectively simulates soil and atmospheric processes governing mercury emission.
- The model provides a mechanistic explanation for temperature-dependent mercury fluxes.
- Findings suggest limitations of empirical flux chamber data in open atmospheric conditions.