Grantee Research Project Results
2005 Progress Report: Assessment of Natural Source (Geologic and Vegetation) Mercury Emissions: Speciation, Mechanisms and Significance
EPA Grant Number: R829800Title: Assessment of Natural Source (Geologic and Vegetation) Mercury Emissions: Speciation, Mechanisms and Significance
Investigators: Gustin, Mae Sexauer , Zehner, Richard E. , Rytuba, James J. , Johnson, Dale W. , Sedinger, Ben , Hanson, Brian , Zhang, Hong , Ericksen, Jody , Fay, Laura , Martindale, Lindsey , Engle, Mark , Xin, Mei , Markee, Melissa , Weisberg, Peter , Pillai, Rekha , Lyman, Seth , Lindberg, Steve , Kuiken, Todd , Ellis, Tyler
Current Investigators: Gustin, Mae Sexauer , Zehner, Richard E. , Rytuba, James J. , Johnson, Dale W. , Hatchett, Ben , Sedinger, Ben , Hanson, Brian , Peterson, Christianna , Weaver, Coty , Zhang, Hong , Stamenkovic, Jelena , Ericksen, Jody , Fay, Laura , Martindale, Lindsey , Engle, Mark , Xin, Mei , Markee, Melissa , Weisburg, Peter , Pillai, Rekha , Lyman, Seth , Lindberg, Steve , Kuiken, Todd , Ellis, Tyler
Institution: University of Nevada - Reno , United States Geological Survey , University of Tennessee , Tennessee Technological University
Current Institution: University of Nevada - Reno , Desert Research Institute , Tennessee Technological University , United States Geological Survey , University of Tennessee
EPA Project Officer: Chung, Serena
Project Period: January 1, 2003 through December 31, 2005 (Extended to December 31, 2007)
Project Period Covered by this Report: January 1, 2005 through December 31, 2006
Project Amount: $891,545
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
Objective:
The major objective of this research project is to develop datasets and process level information on mercury (Hg) fluxes between soil, vegetation, and air that will allow us to assess the significance of natural source Hg emissions relative to anthropogenic emissions for the United States. We are working towards this major objective by way of five sub-objectives: (1) quantify Hg emissions from representative sources that have significant terrestrial coverage including geologically naturally Hg enriched areas, background areas, and biotic sources (plants and forest fires); (2) develop process level information on gaps in our understanding of micrometeorological parameters and substrate characteristics controlling Hg emission and deposition to and from soils; (3) quantify the potential for re-emission of elemental and reactive Hg by substrates; (4) investigate the speciation of atmospheric Hg associated with naturally enriched sites; and (5) using a GIS framework, scale natural source Hg emissions for the United States.
Progress Summary:
Objective 1
Data have been collected and compiled for three geothermal areas in geologically distinct areas; and areas of background soils in Oklahoma, Wisconsin, Colorado, California, North Dakota, Nevada, and Tennessee. A long-term dataset of Hg flux measurements has been completed for a field site in Tennessee. Field sampling was done in five forested areas within state parks from South Carolina to Maine during a month-long field initiative in May to June 2005.
Mercury pools for three different ecosystems were quantified, and the Hg released as a result of fires in these ecosystems has been quantified.
Data were collected in controlled multiple-plant exposure chambers using tree species and examining the influence of three soil exposure concentrations and three air exposure concentrations on Hg uptake and assimilation by foliage and the whole plant. For this experiment, we used naturally Hg-enriched substrates. Data have been compiled for similar tree species using substrates with HgCl2. In addition, data have been compiled for experiments in which we conducted air-soil Hg exposures using tallgrass prairie species. Soil, plant, and litter Hg flux data also were collected from undisturbed tallgrass prairie ecosystems in Oklahoma. In addition, mercury flux was measured in wetland mesocosms with four experimental designs. For the two tree and tallgrass prairie Hg exposure experiments, measurement of foliar Hg concentrations over time, along with plant gas exchange, has provided a dataset that will allow us to better understand Hg air-plant-soil exchange.
Ongoing experiments are investigating single plant responses to changing air Hg exposures, and CO2 exposures in highly controlled experiments are allowing us to better understand the role of plants in the biogeochemical cycle of Hg.
We are compiling data and preparing manuscripts describing research results.
Objective 2
Manuscripts describing the influence of soil moisture and atmospheric oxidants on soil Hg flux have been published. Both parameters have been found to exert as much influence as light on enhancing Hg emissions from soils. Additional field and laboratory studies were done to fine-tune our understanding of the factors controlling Hg emissions from soils and to develop algorithms for scaling.
Controlled laboratory studies assessing the influence of soil properties on elemental Hg flux—as well as the potential for re-emission driven by environmental factors such as ultraviolet radiation, relative humidity, and soil moisture—have been completed and data are being compiled into two manuscripts.
A paper summarizing our understanding of the factors controlling soil-air Hg exchange was written and submitted for publication.
Objective 3
Laboratory work assessing the potential for elemental Hg and reactive Hg deposition to pure substrates and soils and the importance of re-emission has been completed.
Ongoing experiments are examining Hg emissions from low-Hg soils collected from forested systems in the Southeastern United States.
A manuscript has been published describing application of a stable isotope spike of HgCl2 in water to desert soils to examine the potential for re-emission of Hg deposited in precipitation.
Objective 4
During Year 3 of the project, we have measured air Hg speciation and soil-air Hg exchange as well as the potential for dry deposition of Hg at two national Mercury Deposition Network sites in Nevada as well as at one location just north of Reno, Nevada. A manuscript describing the potential for dry deposition at these three sites is in progress, as is one describing air concentrations at the Reno site. Two detailed papers also will be written comparing the data collected at the three sites and describing the development of a method for characterizing reactive gaseous mercury in air.
Objective 5
Significant progress was made on this objective in Year 3. We had three meetings on scaling that were attended by all of the principal investigators (PIs) involved with the project. Data layers have been compiled that contain important information for scaling, and we have come up with a rough number for natural source emissions based on occurrences of geologically enriched substrates and geothermal areas. We will fine tune this work starting in August when a current Ph.D. student of the PI will take over this task. Databases that have been developed include: Hg mineralization maps, landuse/landcover, cloudiness, snow, monthly precipitation, monthly temperature, day length, solar radiation, evapotransporation, soil depth, soil moisture, geothermal areas, and geology.
An initial scaling using only naturally enriched areas with the locations based on maps of Hg naturally enriched areas and geothermal areas are on the order of 12 to 22 Mg/year.
The PI has been awarded a special session on “Air Surface Exchange of Mercury in Terrestrial Ecosystems” at the Eighth International Conference on Mercury as a Global Pollutant to be held August 2006. A brief synopsis of this session follows. The exchange of Hg between the air and terrestrial surfaces is an important component of the biogeochemical cycle of Hg. This session will focus on development of a hierarchy of factors controlling fluxes, address the limitations of the methods used to measure fluxes, and discuss application of this information for scaling and modeling.” Forty abstracts were submitted for this session.
Future Activities:
We have started an initiative to look at air Hg speciation and the potential for Hg deposition associated with Great Salt Lake. It has been suggested that playas and salt lakes may be sinks for atmospheric elemental Hg. We have identified field locations, made contacts with those in charge of the field sites, and plan to sample in June. Depending on the data developed we will establish a field sampling plan. A new graduate student, Christianna Peterson, will work on this project. We are continuing to monitor air Hg speciation northwest of Reno. We have a year-long dataset and will continue to collect data at this site. Manuscripts are being finished and compiled. Presentations are being prepared for the International Meeting on Mercury as a Global Pollutant. We hope to have one field initiative measuring Hg flux associated with plants growing in a Hg-contaminated area to compare with data collected in the laboratory. We will focus on scaling and comparing some of our assumptions with those applied in other mercury cycling models. Collaborations have already been established with Christian Seigneur and we will work with others with the U.S. Geological Survey and the National Oceanic and Atmospheric Administration.
Journal Articles on this Report : 9 Displayed | Download in RIS Format
Other project views: | All 78 publications | 31 publications in selected types | All 29 journal articles |
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Engle MA, Gustin MS, Lindberg SE, Gertler AW, Ariya PA. The influence of ozone on atmospheric emissions of gaseous elemental mercury and reactive gaseous mercury from substrates. Atmospheric Environment 2005;39(39):7506-7517. |
R829800 (2004) R829800 (2005) R829800 (Final) |
Exit Exit Exit |
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Engle MA, Gustin MS, Johnson DW, Murphy JF, Miller WW, Walker RF, Wright J, Markee M. Mercury distribution in two Sierran forest and one desert sagebrush steppe ecosystems and the effects of fire. Science of the Total Environment 2006;367(1):222-233. |
R829800 (2005) R829800 (2006) R829800 (Final) |
Exit Exit Exit |
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Ericksen JA, Gustin MS, Lindberg SE, Olund SD, Krabbenhoft DP. Assessing the potential for re-emission of mercury deposited in precipitation from arid soils using a stable isotope. Environmental Science & Technology 2005;39(20):8001-8007. |
R829800 (2004) R829800 (2005) R829800 (Final) |
Exit |
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Ericksen JA, Gustin MS, Xin M, Weisberg PJ, Fernandez GCJ. Air-soil exchange of mercury from background soils in the United States. Science of the Total Environment 2006;366(2-3):851-863. |
R829800 (2004) R829800 (2005) R829800 (2006) R829800 (Final) |
Exit Exit Exit |
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Gustin MS, Stamenkovic J. Effect of watering and soil moisture on mercury emissions from soils. Biogeochemistry 2005;76(2):215-232. |
R829800 (2004) R829800 (2005) R829800 (Final) |
Exit |
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Gustin MS, Engle M, Ericksen J, Lyman S, Stamenkovic J, Xin M. Mercury exchange between the atmosphere and low mercury containing substrates. Applied Geochemistry 2006;21(11):1913-1923. |
R829800 (2005) R829800 (2006) R829800 (Final) |
Exit Exit Exit |
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Millhollen AG, Gustin MS, Obrist D. Foliar mercury accumulation and exchange for three tree species. Environmental Science & Technology 2006;40(19):6001-6006. |
R829800 (2005) R829800 (2006) R829800 (Final) |
Exit |
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Millhollen AG, Obrist D, Gustin MS. Mercury accumulation in grass and forb species as a function of atmospheric carbon dioxide concentrations and mercury exposures in air and soil. Chemosphere 2006;65(5):889-897. |
R829800 (2005) R829800 (2006) R829800 (Final) |
Exit Exit Exit |
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Obrist D, Gustin MS, Arnone III JA, Johnson DW, Schorran DE, Verburg PSJ. Measurements of gaseous elemental mercury fluxes over intact tallgrass prairie monoliths during one full year. Atmospheric Environment 2005;39(5):957-965. |
R829800 (2004) R829800 (2005) R829800 (Final) |
Exit Exit Exit |
Supplemental Keywords:
mercury, natural Hg sources, geothermal Hg sources, natural Hg biogeochemical cycling, vegetation-air-soil Hg exchange,, Scientific Discipline, Air, INTERNATIONAL COOPERATION, Waste, TREATMENT/CONTROL, Ecosystem Protection/Environmental Exposure & Risk, POLLUTANTS/TOXICS, Air Quality, air toxics, Treatment Technologies, Environmental Chemistry, Chemicals, Fate & Transport, Environmental Monitoring, Bioremediation, Chemistry and Materials Science, fate and transport, contaminated sediments, air pollutants, Hg, mercury, mercury emissions, modeling, mercury cycling, hazardous waste, chemical kinetics, contaminants in soil, bioremediation of soils, atmospheric mercury chemistry, mercury chemistry, phytoremediation, atmospheric chemistry, atmospheric mercury cycling, atmospheric deposition, contaminant transport models, heavy metals, mercury vapor, atmospheric mercuryProgress 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.