Lyatt Jaeglé’s / research
Atmospheric Chemistry Modeling GROUP
 

Modeling studies of the global mercury cycle


Human activities such as coal combustion, and metal extraction, and waste incineration, have profoundly impacted the biogeochemical cycling of mercury (Hg).  Once released in the atmosphere, Hg is transported globally before being deposited to the Earth’s surface, where it can bioaccumulate in aquatic food chains. Exposure to Hg through fish consumption can severely affect human health. After deposition to land and aquatic surfaces, Hg can be re-emitted to the atmosphere. Thus, anthropogenic Hg cycles on multiple timescales in the environment, ranging from years to centuries.


We have developed a new global simulation of Hg with the GEOS-Chem model, in collaboration with Daniel Jacob’s group at Harvard University. We have coupled our the atmospheric Hg simulation (Selin et al., 2007) with an interactive slab ocean model (Strode et al., 2007) to constrain estimates of ocean emissions, simulate their spatiotemporal variability, and examine the role of the ocean in Hg cycling. The GEOS-Chem model was used to interpret Hg observations at Mt. Bachelor, Oregon , Oregon (Swartzendruber et al., 2006, 2008). We constrained quantified Asian sources of Hg and their trans-Pacific transport , finding that Asian emissions of 1200-1500 Mg/yr are consistent with observations (Strode et al., 2008). The GEOS-Chem ocean-atmosphere-land mercury simulation was applied to examine the Hg budget of Hg during preindustrial times (Selin et al., 2008) as well as during the 19th century North American gold and silver mining rush period (Strode et al., 2009). We have calculated global source-receptor relationships for mercury Hg deposition with the GEOS-Chem model (Jaeglé et al., 2009). Finally, we have explored how the penetration of anthropogenic mercury Hg in the ocean is affected by vertical diffusion and sinking organic settling on particulate organic matter (Strode et al., 2010).


We have developed a new high-resolution (1/2° latitude by 2/3° longitude) nested-grid Hg simulation over North America employing the GEOS-Chem global chemical transport model (Zhang et al., 2012). Emissions, chemistry, deposition, and meteorology are self-consistent between the global and nested domains. We found that in order to reproduce observations of wet deposition from the Mercury Deposition Network and surface observations of reactive mercury we need to modify anthropogenic emission speciation profiles in the U.S. EPA National Emission Inventory to account for the rapid in-plume reduction of reactive to elemental Hg (IPR simulation).



This figure illustrates a comparison of observed mercury wet deposition over the U.S. (circles) to three GEOS-Chem simulations: global standard model (top), nested standard simulation (middle), nested IPR simulation (bottom). For more information, please contact Yanxu Zhang.



Yanxu Zhang, Graduate Student

Viral Shah, Graduate Student

Lyatt Jaeglé, Professor


Funding


This work is currently being funded by

> NSF (2012-2015)

> Electric Power Research Institute (PI: Lyatt Jaeglé)


We also gratefully acknowledge past funding from:

> Alaska Department of Environmental Conservation, 2009-2010 (PI: Lyatt Jaeglé).

> NSF, Faculty Early Career Development (CAREER), ATM-0238520, 2003-2008 (PI: Lyatt Jaeglé). 


Publications


Please follow this link: PUB_Hg