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Determining the Role of Plants and Soils in the Biogeochemical Cycling of Mercury on an Ecosystem Level

EPA Grant Number: R827622E02
Title: Determining the Role of Plants and Soils in the Biogeochemical Cycling of Mercury on an Ecosystem Level
Investigators: Gustin, Mae Sexauer , Coleman, James , Johnson, Dale W. , Lindberg, Steve , Meager, Richard
Current Investigators: Alden, Ray , Coleman, James , Gustin, Mae Sexauer , Johnson, Dale W. , Lindberg, Steve
Institution: University of Nevada - Reno , Desert Research Institute , Oak Ridge National Laboratory , University of Georgia
Current Institution: University of Nevada - Reno , Desert Research Institute
EPA Project Officer: Winner, Darrell
Project Period: August 9, 1999 through August 8, 2003
Project Amount: $253,798
RFA: EPSCoR (Experimental Program to Stimulate Competitive Research) (1998)
Research Category: EPSCoR (The Experimental Program to Stimulate Competitive Research)

Description:

Mercury (Hg) occurs as volatile phases promoting the cycling of this contaminant between environmental compartments. Mercury is a global pollutant for via the atmospheric pathway. It is transported across regional and international boundaries and contaminates aquatic and terrestrial ecosystems. Recent studies have begun to develop a database on Hg emission and deposition to and from aquatic and terrestrial surfaces; however, our understanding of the mechanisms controlling these processes is only beginning to be developed. Several recent studies have indicated that Hg is exchanged between foliar surfaces and the atmosphere, but the significance of this exchange with respect to the overall biogeochemical cycling of Hg remains unknown. Understanding the mechanisms controlling the exchange of Hg between the atmosphere and abiotic and biotic ecosystem compartments is necessary for development of regulatory controls as well as for assessment of ecological and human health impacts of Hg in the environment.

Objective:

The goal of this project is to determine the role of plants and soils in controlling the fate and transport of Hg in the environment at the ecosystem level. Much of our mechanistic knowledge for understanding the responses of ecosystems to environmental contaminants is limited to studies of single species or individual samples. Due to natural variability and environmental complexity, the use of field studies to understand mechanisms controlling contaminant flux is extremely difficult.

Approach:

This project will utilize a large mesocosm (EcoCELL), an experimental setting in which whole system contaminant flux may be monitored under precisely controlled environmental conditions to identify key processes controlling the flux of Hg between ecosystem compartments. Investigation of the fate and transport of Hg at the ecosystem level will allow for development of an understanding of antagonistic and synergistic effects of mechanisms known to control Hg flux on the individual sample scale. Ancillary experiments investigating uptake, storage and emission associated with ecosystem components, using a single pass gas exchange system, Ecopods and a field flux chamber, will provide additional data for understanding mechanisms controlling Hg fate and transport at the ecosystem level.

Expected Results:

An understanding of the Hg flux and the mechanisms controlling flux from unvegetated soil surfaces will be developed. A plant community will be established in the EcoCELLs and whole system fluxes as well as individual plant mass balances will be developed as leaf area and rooting volume increases. The working hypothesis is that mercury available as soil gas is readily bioavailable and plants act as a conduit for mercury to be transported from contaminated substrate to the air. One component of this project will assess the potential for phytoremediation of Hg contaminated soils using genetically engineered plants. These plants are known to uptake Hg from soils at very high rates; however, the degree to which they remove mercury from the soil is not known.

Publications and Presentations:

Publications have been submitted on this project: View all 24 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 6 journal articles for this project

Supplemental Keywords:

Ecosystem Protection/Environmental Exposure & Risk, Water, INTERNATIONAL COOPERATION, TREATMENT/CONTROL, Scientific Discipline, Waste, RFA, Molecular Biology/Genetics, Air Quality, Analytical Chemistry, Ecological Risk Assessment, Hazardous Waste, Fate & Transport, Contaminated Sediments, Hazardous, Treatment Technologies, Bioremediation, bioavailability, biodegradation, fate and transport, phytoremediation, degradation, atmospheric mercury, atmospheric deposition, emissions, contaminated sediment, transgenic plants, contaminants in soil, contaminated soils, microbiology, contaminated soil, bioremediation of soils, biochemistry, natural recovery
Relevant Websites:

Synthesis Report of Research from EPA’s Science to Achieve Results (STAR) Grant Program: Mercury Transport and Fate Through a Watershed (PDF) (42 pp, 760 K)

Progress and Final Reports:
Final Report

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The 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.

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