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Mercury Wet Scavenging and Deposition Differences by Precipitation Type
Aaron S Kaulfus1, Udaysankar Nair1, Christopher D Holmes2
1Department of Atmospheric Science, University of Alabama in Huntsville , Huntsville, Alabama 35806, United States.
Environmental Science & Technology
|January 18, 2017
Summary
Supercell thunderstorms significantly increase mercury wet deposition, especially in summer and at high elevations. Convective precipitation types enhance mercury deposition more than nonconvective types.
Area of Science:
- Environmental Science
- Atmospheric Chemistry
- Mercury Cycling
Background:
- Mercury is a persistent environmental pollutant with significant human health implications.
- Understanding mercury's transport and deposition is crucial for environmental risk assessment.
- Precipitation is a major pathway for mercury removal from the atmosphere.
Purpose of the Study:
- To investigate the influence of different precipitation types on mercury wet deposition across the contiguous United States.
- To quantify the relationship between precipitation characteristics and mercury deposition rates.
- To identify key meteorological and geographical factors affecting mercury wet deposition.
Main Methods:
- Utilized a novel database of individual rainfall events from the Mercury Deposition Network (MDN).
- Classified precipitation events into six distinct types (supercell thunderstorms, disorganized thunderstorms, quasi-linear convective systems, extratropical cyclones, light rain, land-falling tropical cyclones).
- Analyzed mercury concentrations and precipitation depth, controlling for system morphology, geographic region, and season.
Main Results:
- Mercury deposition follows a power law with precipitation depth, modulated by system morphology.
- Supercell thunderstorms exhibited the highest mercury deposition, followed by disorganized thunderstorms and QLCS.
- Convective precipitation morphologies enhanced mercury wet deposition by at least 1.6 times compared to nonconvective types.
- Higher deposition rates were observed at high-elevation sites, during summer, and in convective precipitation events.
Conclusions:
- Precipitation system morphology is a critical factor controlling mercury wet deposition.
- Convective storm systems play a significant role in atmospheric mercury removal.
- Seasonal and regional variations, particularly elevated deposition in summer and at high altitudes, highlight the complexity of mercury's environmental fate.
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