Grantee Research Project Results

Natural Mercury Isotopes as Tracers of Sources, Cycling, and Deposition of Atmospheric Mercury

EPA Grant Number: R830603
Title: Natural Mercury Isotopes as Tracers of Sources, Cycling, and Deposition of Atmospheric Mercury
Investigators: Odom, A. Leroy , Salters, Vincent , Landing, William
Institution: Florida State University , National High Magnetic Field Laboratory
Current Institution: Florida State University
EPA Project Officer: Chung, Serena
Project Period: October 2, 2002 through December 31, 2006
Project Amount: $827,147
RFA: Mercury: Transport, Transportation, and Fate in the Atmosphere (2001) RFA Text | Recipients Lists
Research Category: Heavy Metal Contamination of Soil/Water , Air Quality and Air Toxics , Safer Chemicals , Air

Description:

This research centers on the use of mercury isotope systematics as a new way of investigating natural and anthropogenic emissions of mercury into the atmosphere and of the atmospheric processes that affect transportation and deposition. Given the fact that isotope systematics of carbon and nitrogen constrain the cycling models of these elements in the environment, variations in mercury isotopic compositions hold the promise of being able to delimit sources, evaluate their contribution to the atmospheric burden, and to impose new constraints on models of mercury cycling. We now have the ability to make the high precision mercury isotope ratio measurements necessary to begin establishing the isotopic boundaries for mercury models.

Approach:

Atmospheric mercury contains components from far-field, regional, and local sources. We propose to determine the isotopic composition of atmospheric mercury (1) thought to be dominated by far-field sources (Olympic Peninsula WA, Barbados, New Zealand, (2) influenced by both far field and regional or local sources (Florida "Supersite"), and (3) influenced by known point sources (Southern Company's coal burning generators as well as waste incinerators). These studies will include both elemental and oxidized mercury, collected total gaseous mercury (TGM), and rain. These sites will be heavily instrumented for a variety of high-frequency measurements which can be used as a context for the interpretation of Hg-isotopes. Another important area of study will be the measurement of the isotopic ratios of Hg emissions from naturally enriched soils in collaboration with the flux chamber measurements of Dr. Mae Gustin of the University of Nevada Reno. Ore, soil, and plant will also be isotopically measured. We are joined in these efforts By Frontier Geosciences Inc. Collaborators include Southern Company, Florida DEP, Mae Gustin (U Nev-Reno), and Keith Hunter (U. Otago, NZ).

Expected Results:

Mass dependent variations in mercury isotopic composition readily can be induced in the laboratory by chemical and physical processes (including evaporation and diffusion). Isotopic variations are found between different mercury ores and between the ores and industrially processed mercury. Based on extrapolation, theory, and initial results, it is expected that isotopic differences exist in environmental mercury due to a combination of sources and fractionating processes. At the onset, it appears unlikely that mercury isotopes can be used to uniquely identify sources, or precisely trace the transport of atmospheric mercury. What mercury isotopic variations can promise, however, is the ability to delimit sources, evaluate their contribution to the atmospheric burden, and to impose new, perhaps most powerful, constraints on models. Models of mercury fluxes in and out of environmental compartments will also have to accurately serve as weighting factors of isotopically different sources and sinks in order to stand.

Publications and Presentations:

Publications have been submitted on this project: View all 2 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 1 journal articles for this project

Supplemental Keywords:

Mercury cycling, atmosperic mercury, modeling, isotopic measurements, deposition, environmental chemistry, Scientific Discipline, Air, INTERNATIONAL COOPERATION, Waste, Ecosystem Protection/Environmental Exposure & Risk, POLLUTANTS/TOXICS, Air Quality, air toxics, Environmental Chemistry, Chemicals, Fate & Transport, Environmental Monitoring, Chemistry and Materials Science, Atmospheric Sciences, fate and transport, air pollutants, Hg, mercury, mercury emissions, modeling, mercury cycling, chemical kinetics, mercury isotope systematics, atmospheric mercury chemistry, atmospheric chemistry, atmospheric mercury cycling, atmospheric deposition, contaminant transport models, heavy metals, mercury vapor, atmospheric mercury

Progress and Final Reports:

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.