Mercury Rising and Falling: Exploring Mercury Cycling through Atmosphere and Biosphere

EPA Grant Number: F5B10209
Title: Mercury Rising and Falling: Exploring Mercury Cycling through Atmosphere and Biosphere
Investigators: Selin, Noelle Eckley
Institution: Harvard University
EPA Project Officer: Zambrana, Jose
Project Period: September 1, 2005 through September 1, 2008
Project Amount: $92,118
RFA: STAR Graduate Fellowships (2005) RFA Text |  Recipients Lists
Research Category: Academic Fellowships


Despite increasing attention to mercury as an environmental problem, mercury's behavior and chemistry in the atmosphere are not well-understood, and recent scientific work has questioned understanding about its behavior in the atmosphere. Open questions remain about its cycling in the atmosphere and biosphere, its pathways and fate on a regional level, and the potential changes that might occur in the mercury cycle due to a changing global climate. This work will address selected questions about mercury's transport and fate in the global atmosphere using the GEOS-CHEM atmospheric chemistry and transport model.

This work has three complementary objectives. First, it aims to contribute to improved understanding of the global sources, sinks, and cycling of mercury species in the atmosphere and biosphere. This includes improving understanding of the major oxidation and reduction reactions that control mercury speciation and how they contribute to the global mercury cycle, as well as the accuracy of natural source inventories and estimates for mercury. A second objective is to gain insight into the pathways by which mercury reaches the Arctic, the United States, and other regions. Third, this research will explore and illustrate the projected potential changes in the mercury cycle due to climatic and other changes in the 21st century.


This project will use GEOS-CHEM global atmospheric chemistry and transport model to simulate mercury in the atmosphere and its exchange with the biosphere. Global modeling can help to improve our understanding of the global mercury cycle by testing our current knowledge of processes against the constraints offered by observed atmospheric concentrations. It also provides the tool for quantifying source-receptor relationships and thus enabling well-informed mercury policy decisions.

Expected Results:

This work will help to provide a better understanding of mercury's behavior in the global atmosphere, its cycling between the land and atmosphere, its legacy of accumulation in surface reservoirs over the past century, source-receptor relationships for the present day, and the possible impacts of future climate change. Major scientific benefits include helping to constrain uncertainties on the atmospheric chemistry of mercury, and developing a new biogeochemical perspective on the cycling of mercury between the atmosphere, land, and ocean reservoirs. This work will also have significant policy-relevant applications. Directly policy-relevant will be the provision of improved boundary conditions for the regional CMAQ mercury model, which is used in regulatory applications. Better understanding of the contributions of various natural and regional sources to deposition, and of the importance of "legacy" mercury from historical emissions, will be helpful to policy makers interested in addressing mercury pollution problems.

Supplemental Keywords:

RFA, Scientific Discipline, Air, Water, Environmental Chemistry, climate change, Air Pollution Effects, Analytical Chemistry, Environmental Monitoring, Atmosphere, Mercury, fate and transport, mercury measurement, atmospheric transformation, mercury cycling, air-water interface

Relevant Websites:

mercury, atmosphere, biosphere, GEOS-CHEM, Arctic, land-atmosphere interactions, climate change,

Progress and Final Reports:

  • 2006
  • 2007
  • Final