Grantee Research Project Results
2005 Progress Report: Pathways of Mercury Evasion from Contaminated Wetlands: A Globally Important Source of Atmospheric Mercury?
EPA Grant Number: GR832214Title: Pathways of Mercury Evasion from Contaminated Wetlands: A Globally Important Source of Atmospheric Mercury?
Investigators: Peters, Stephen , Morris, Donald P. , Windham, Lisamarie
Institution: Lehigh University
EPA Project Officer: Hahn, Intaek
Project Period: January 15, 2005 through January 14, 2008
Project Period Covered by this Report: January 15, 2005 through January 14, 2006
Project Amount: $298,907
RFA: Greater Research Opportunities: Persistent, Bioaccumulative Chemicals (2004) RFA Text | Recipients Lists
Research Category: Hazardous Waste/Remediation , Human Health , Safer Chemicals , Land and Waste Management
Objective:
The objectives of this research project are to: (1) determine the relative importance of these two different evasion pathways; (2) investigate the fundamental processes governing chemical interactions within each pathway; and (3) evaluate the net contribution of evasion from mercury (Hg) contaminated wetlands to the global Hg budget. These objectives will be studied by experimentally and empirically testing hypothesized relationships between measured environmental parameters and Hg behavior in a wetland.
Two pathways exert primary control over the release of Hg0 from estuarine environments: the abiotic reduction of Hg(II) to Hg0(aq) as moderated by complex interactions of UV radiation, dissolved organic carbon (DOC), salinity, and pH in the water column; and the diffusive release of bacterially reduced Hg0 from plant leaf surfaces during transpiration.
Progress Summary:
In Year 1, we made progress on the first two of the three objectives. Most of our effort has centered on method development, field site refinement, and data collection.
Our first task was to develop the methodology to measure directly mercury fluxes from water and plant surfaces using field-portable equipment. This development involved constructing and testing various flux chamber designs and is still in progress. Water column flux chamber design has been described in the literature and was fairly straightforward to replicate. Initial tests with plant flux chambers were more complicated, and modifications are underway to improve the design.
Field sites were scouted and selected, and three sampling rounds were conducted during the summer months in both the Meadowlands, New Jersey, and in the Pocono Mountains, Pennsylvania. Preliminary data from this first sampling round was presented in the form of three abstracts at various meetings. The data will be combined with new data being collected this summer to form the basis of several manuscripts to be submitted this fall.
Our preliminary data indicate covariance between emission of Hg0 and incident UV light with occasional large pulses coincident with tidal stage and light/dark periods. Plant transpired Hg0 seems to vary with conductance, but more data are needed with appropriately designed flux chambers.
Funds were used to support a Ph.D. student during the 2005-2006 academic year and, additionally one M.S. student during the summer. The Ph.D. student has passed her qualifying examination, has successfully defended her thesis proposal, and has presented an abstract on her first project.
Future Activities:
Our future activities will focus on collection of field data of mercury evasion, particularly across a gradient of DOC quality and quantity and from a variety of plant types. We plan on disseminating our results through several peer-reviewed manuscripts currently in preparation, as well as through a variety of conferences, including the International Conference on Mercury as a Global Pollutant, American Geophysical Union, and the Science To Achieve Results (STAR) Grantees Conference.
Journal Articles:
No journal articles submitted with this report: View all 7 publications for this projectSupplemental Keywords:
estuary, integrated assessment, environmental chemistry, ecology, geology, bioavailability, air quality, atmospheric sciences, ecosystem protection/environmental exposure & risk, aquatic ecosystems, environmental monitoring, Terrestrial Ecosystems, air-water interface, aquatic plants, atmospheric deposition, bioaccumulation, biogenic plant releases, dissolved organic carbon, fate and transport, heavy metals, mercury emissions, wetland,, RFA, Scientific Discipline, Ecosystem Protection/Environmental Exposure & Risk, Water, ECOSYSTEMS, POLLUTANTS/TOXICS, Aquatic Ecosystem, Aquatic Ecosystems & Estuarine Research, Mercury, Terrestrial Ecosystems, Environmental Chemistry, Aquatic Ecosystems, Chemicals, Environmental Monitoring, wetland, aquatic plants, heavy metals, air-water interface, estuaries, atmospheric deposition, bioaccumulation, fate and transport, wetlands, biogenic plant releases, mercury emissionsProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.