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Allan Kolker (Former Employee)

Science and Products

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Energy Geochemistry Project Science Object Representation Thumb

Geochemistry of Energy Fuels Project

Since its establishment in 1879, USGS geoscientists have investigated the geochemistry of energy resources. Research conducted in the Geochemistry of Energy Fuels project continues this tradition. Goals include 1) understanding the geologic, geochemical, microbiological, and other factors that control production, quality, and composition of coal, petroleum, and nuclear fuels, and 2) predicting the...
By
Energy Resources Program, Geology, Energy & Minerals Science Center
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Geochemistry of Energy Fuels Project

Since its establishment in 1879, USGS geoscientists have investigated the geochemistry of energy resources. Research conducted in the Geochemistry of Energy Fuels project continues this tradition. Goals include 1) understanding the geologic, geochemical, microbiological, and other factors that control production, quality, and composition of coal, petroleum, and nuclear fuels, and 2) predicting the...
Learn More
link
Energy Geochemistry Byproducts Task 8 Representation Thumb

Byproducts of Energy Fuels

This task provides detailed information on the use and resource potential of energy by-products, as well as controls on the potential mobility of contaminants resulting from transport, storage, and disposal of these byproducts. Specific topics investigated include 1) transport and fate of organic and inorganic contaminants during storage and disposal of waste coal and coal combustion byproducts...
By
Energy Resources Program, Geology, Energy & Minerals Science Center
link

Byproducts of Energy Fuels

This task provides detailed information on the use and resource potential of energy by-products, as well as controls on the potential mobility of contaminants resulting from transport, storage, and disposal of these byproducts. Specific topics investigated include 1) transport and fate of organic and inorganic contaminants during storage and disposal of waste coal and coal combustion byproducts...
Learn More
link
Geochemistry Trace Science Object Representation Thumb

Trace Elements in Energy Fuels

In this task we conduct new interpretive studies of the concentration and distribution of trace metals and mercury in coal and other energy materials. Complementary studies of coal combustion products are conducted under Task 8. Together with use of existing USGS databases, we examine the potential for reducing emissions of potentially toxic substances by coal preparation, and by optimizing coal...
By
Energy Resources Program, Geology, Energy & Minerals Science Center
link

Trace Elements in Energy Fuels

In this task we conduct new interpretive studies of the concentration and distribution of trace metals and mercury in coal and other energy materials. Complementary studies of coal combustion products are conducted under Task 8. Together with use of existing USGS databases, we examine the potential for reducing emissions of potentially toxic substances by coal preparation, and by optimizing coal...
Learn More

Geochemical Data for Coal Wastes from Bituminous Coal Mining in Pennsylvania, 2022

Coal and coal byproducts may be economically important resources if enriched in critical minerals such as rare earth elements. The organic carbon they contain could be converted to gas using stimulated microbial methanogenesis. In this study, samples were collected from two underground mine sites in the bituminous region of southwest Pennsylvania to assess the potential for these uses from differe
By
Energy Resources Program, Environmental Health Program, Geology, Energy & Minerals Science Center, Pennsylvania Water Science Center, Eastern Energy and Environmental Laboratory (EEEL)

Geochemical Data for Illinois Basin Coal Samples, 2015-2018 (ver. 1.1, March 2021)

Researchers at the U.S. Geological Survey (USGS) and their collaborators conducted a study of the geochemical properties of coals currently produced for electric power generation in the Illinois Basin in Illinois and Indiana. The study follows from recommendations by an expert panel for the USGS to investigate the distribution and controls of trace constituents such as mercury (Hg) in Illinois Bas
By
Energy Resources Program, Geology, Energy & Minerals Science Center

Arsenic in stream sediments of northern Alabama

OVERVIEW OF ARSENIC IN STREAM SEDIMENTS The overall range of arsenic in the NURE stream sediments was from 0.3 to 44 mg/kg sediment (ppm) As in the sample data set. The mean value was 4.3 ppm with a standard deviation of 4.1 ppm. For comparison, the crustal abundance of arsenic is 1.8 ppm (Taylor, 1964). Shale is higher, with average values of 15 ppm. Coal samples from the entire USGS National Coa
Filter Total Items: 52

Rare Earth Elements in coal fly ash and their potential recovery

Coal fly ash is a potential resource of valuable elements, such as rare earth elements (REEs), which are retained and concentrated upon combustion. Understanding REE occurrence within fly ash is vital to developing recovery methods. Some of the highest REE contents occur in fly ash derived from U.S. Appalachian Basin coals, and coals influenced by input volcanic ash are especially enriched. Leachi
Authors
James Hower, Allan Kolker, Heileen Hsu-Kim, Desiree Platta
By
Energy Resources Program, Geology, Energy & Minerals Science Center

Energy-related rare earth element sources

Energy-related materials such as coal, coal-bearing wastes, and coal combustion products are traditionally thought of as sources or by-products of electric power generation. Increasingly, these materials are considered resources for their content of rare earth elements (REEs) and other useful constituents. In this chapter, we examine the distribution, modes of occurrence, and relative extractabili
Authors
Allan Kolker, Liliana Lefticariu, Steven T. Anderson
By
Energy Resources Program, Geology, Energy & Minerals Science Center

Geochemical data for Illinois Basin coal samples, 2015–2018

Researchers at the U.S. Geological Survey (USGS) and their collaborators conducted a study of the geochemical properties of coals currently produced for electric power generation in the Illinois Basin in Illinois and Indiana. The study follows from recommendations by an expert panel for the USGS to investigate the distribution and controls of trace constituents such as mercury (Hg) in Illinois Bas
Authors
Allan Kolker, Clint Scott, Liliana Lefticariu, Maria Mastalerz, Agnieszka Drobniak, Annie Scott
By
Energy and Minerals Mission Area, Energy Resources Program, Geology, Energy & Minerals Science Center

Rare earth elements in coal and coal fly ash

The rare earth elements (REEs) are a group of 17 elements sharing similar chemical properties. They include yttrium (Y, atomic number 39), scandium (Sc, atomic number 21), and the 15 elements of the lanthanide series, atomic numbers 57 (lanthanum, La) to 71 (lutetium, Lu). Because promethium (Pm, atomic number 61) does not occur in the Earth’s crust and scandium typically has different geological
Authors
Clint Scott, Allan Kolker
By
Energy and Minerals Mission Area, Energy Resources Program, Geology, Energy & Minerals Science Center, Reston Electron Microbeam Laboratory

Topics in coal geochemistry—Short course

This short course was prepared at the request of Servicio Geológico Colombiano (SGC) as a module for staff training. Prior to the short course, the SGC expressed interest in receiving training in (1) geochemistry and quality of coal; (2) geochemistry of trace elements in coal; (3) mercury and halogens in coal; (4) characterization and cycling of atmospheric mercury; (5) mercury, trace elements, an
Authors
Allan Kolker
By
Energy Resources Program, Geology, Energy & Minerals Science Center

Mercury in U.S. coal—Priorities for new U.S. Geological Survey studies

In 2011, the U.S. Environmental Protection Agency (EPA) introduced emissions standards, known as Mercury and Air Toxics Standards (MATS), for a range of toxic constituents from coal-fired utility power stations and other combustion sources. This report presents the findings of an expert panel convened in September 2014 to assess the role of the U.S. Geological Survey (USGS) in new coal investigati
Authors
Allan Kolker
By
Energy Resources Program, Geology, Energy & Minerals Science Center

Mercury and trace element distribution in density separates of a South African Highveld (#4) coal: Implications for mercury reduction and preparation of export coal

Eight density separates of Permian Highveld (#4) coal were investigated for partitioning of Hg and trace elements. The separates include float fractions obtained in heavy media having densities of 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, and 2.0 g/cm3, and the sink fraction for 2.0 g/cm3. Bulk analysis of the separates shows strong (R2 ≥ 0.80) positive correlations between pyritic sulfur and mercury, and bet
Authors
Allan Kolker, Connie L. Senior, Chris van Alphen, Alan E. Koenig, Nicholas J. Geboy
By
Energy Resources Program, Geology, Energy & Minerals Science Center

Collaborative Studies for Mercury Characterization in Coal and Coal Combustion Products, Republic of South Africa

Mercury (Hg) analyses were obtained for 42 samples of feed coal provided by Eskom, the national electric utility of South Africa, representing all 13 coal-fired power stations operated by Eskom in South Africa. This sampling includes results for three older power stations returned to service starting in the late 2000s. These stations were not sampled in the most recent previous study. Mercury conc
Authors
Allan Kolker, Constance L. Senior, Chris van Alphen
By
Energy Resources Program, Geology, Energy & Minerals Science Center

Trace elements in coal ash

Coal ash is a residual waste product primarily produced by coal combustion for electric power generation. Coal ash includes fly ash, bottom ash, and flue-gas desulfurization products (at powerplants equipped with flue-gas desulfurization systems). Fly ash, the most common form of coal ash, is used in a range of products, especially construction materials. A new Environmental Protection Agency ruli
Authors
Amrika Deonarine, Allan Kolker, Michael W. Doughten
By
Energy Resources Program, Geology, Energy & Minerals Science Center

Size distribution of rare earth elements in coal ash

Rare earth elements (REEs) are utilized in various applications that are vital to the automotive, petrochemical, medical, and information technology industries. As world demand for REEs increases, critical shortages are expected. Due to the retention of REEs during coal combustion, coal fly ash is increasingly considered a potential resource. Previous studies have demonstrated that coal fly ash is
Authors
Clint Scott, Amrika Deonarine, Allan Kolker, Monique Adams, James F. Holland
By
Energy Resources Program, Geology, Energy & Minerals Science Center

Atmospheric particulate matter in proximity to mountaintop coal mines: Sources and potential environmental and human health impacts

Mountaintop removal mining (MTM) is a widely used approach to surface coal mining in the US Appalachian region whereby large volumes of coal overburden are excavated using explosives, removed, and transferred to nearby drainages below MTM operations. To investigate the air quality impact of MTM, the geochemical characteristics of atmospheric particulate matter (PM) from five surface mining sites i
Authors
Laura Kurth, Allan Kolker, Mark A. Engle, Nicholas J. Geboy, Michael Hendryx, William H. Orem, Michael McCawley, Lynn M. Crosby, Calin A. Tatu, Matthew S. Varonka, Christina A. DeVera
By
Energy Resources Program, Geology, Energy & Minerals Science Center

Mercury and halogens in coal

Apart from mercury itself, coal rank and halogen content are among the most important factors inherent in coal that determine the proportion of mercury captured by conventional controls during coal combustion. This chapter reviews how mercury in coal occurs, gives available concentration data for mercury in U.S. and international commercial coals, and provides an overview of the natural variation
Authors
Allan Kolker, Jeffrey C. Quick
By
Energy Resources Program, Geology, Energy & Minerals Science Center

Non-USGS Publications**

Huggins, F. E., Huffman, G. P., Kolker, Allan, Mroczkowski, S. J., Palmer, C. A., and Finkelman, R. B., 2002, Combined application of XAFS spectroscopy and sequential leaching for determination of arsenic speciation in coal: Energy and Fuels, v. 16, no. 5, p. 1167-1172.
Bunnell, J. E., Garcia, L. V., Furst, J. M., Lerch, Harry, Olea, R.A., Suitt, S.E., and Kolker, Allan, 2010, Navajo coal combustion and respiratory health near Shiprock, New Mexico: Journal of Environmental and Public Health, v. 2010, #260525, 14 p.
Engle, Mark A., Radke, Lawrence F., Heffern, Edward L., O’Keefe, Jennifer M.K., Hower, James C., Smeltzer, Charles D., Hower, Judith M, Olea, Ricardo A., Eatwell, Robert J., Blake, Donald R., Emsbo-Mattingly, Stephen D., Stout, Scott A., Queen, Gerald, Aggen, Kerry L., Kolker, Allan, Prakash, Anupma, Henke, Kevin R., Stracher, Glenn B., Schroeder, Paul A., Román-Colón, Yomayra, and ter Schure, Arnout, 2012, Gas emissions, minerals, and tars associated with three coal fires, Powder River Basin, USA: Science of the Total Environment, v. 420, p. 146-159.
Kolker, Allan, Engle, Mark A., Peuker-Ehrenbrink, Bernhard, Geboy, N. J., Krabbenhoft, D.P., Bothner, M.H., and Tate, M.T., Atmospheric mercury and fine particulate matter at Woods Hole, Cape Cod, MA: Implications for mercury and trace element sources in the northeastern U.S.: Atmospheric Environment, v. 79, p. 760-768.
Kolker, Allan, and Quick, Jeffrey C., 2015, Mercury and halogens in coal, in, Granite, E., Senior, C., and Pennline, H., eds., Mercury control for coal-derived gas steams, Wiley-VCH, p. 13-44.
Kolker, Allan, 2016, Mercury in U.S. Coal- Priorities for New USGS Studies: U.S. Geological Survey Open File Report, in press.
Deonarine, A., Kolker, A., Doughten, M., Bailoo, J.D., and Holland, J.T., Arsenic speciation in bituminous coal fly ash and transformations in response to redox conditions: Submitted to Environmental Science and Technology.

**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.

Science and Products

link
Energy Geochemistry Project Science Object Representation Thumb

Geochemistry of Energy Fuels Project

Since its establishment in 1879, USGS geoscientists have investigated the geochemistry of energy resources. Research conducted in the Geochemistry of Energy Fuels project continues this tradition. Goals include 1) understanding the geologic, geochemical, microbiological, and other factors that control production, quality, and composition of coal, petroleum, and nuclear fuels, and 2) predicting the...
By
Energy Resources Program, Geology, Energy & Minerals Science Center
link

Geochemistry of Energy Fuels Project

Since its establishment in 1879, USGS geoscientists have investigated the geochemistry of energy resources. Research conducted in the Geochemistry of Energy Fuels project continues this tradition. Goals include 1) understanding the geologic, geochemical, microbiological, and other factors that control production, quality, and composition of coal, petroleum, and nuclear fuels, and 2) predicting the...
Learn More
link
Energy Geochemistry Byproducts Task 8 Representation Thumb

Byproducts of Energy Fuels

This task provides detailed information on the use and resource potential of energy by-products, as well as controls on the potential mobility of contaminants resulting from transport, storage, and disposal of these byproducts. Specific topics investigated include 1) transport and fate of organic and inorganic contaminants during storage and disposal of waste coal and coal combustion byproducts...
By
Energy Resources Program, Geology, Energy & Minerals Science Center
link

Byproducts of Energy Fuels

This task provides detailed information on the use and resource potential of energy by-products, as well as controls on the potential mobility of contaminants resulting from transport, storage, and disposal of these byproducts. Specific topics investigated include 1) transport and fate of organic and inorganic contaminants during storage and disposal of waste coal and coal combustion byproducts...
Learn More
link
Geochemistry Trace Science Object Representation Thumb

Trace Elements in Energy Fuels

In this task we conduct new interpretive studies of the concentration and distribution of trace metals and mercury in coal and other energy materials. Complementary studies of coal combustion products are conducted under Task 8. Together with use of existing USGS databases, we examine the potential for reducing emissions of potentially toxic substances by coal preparation, and by optimizing coal...
By
Energy Resources Program, Geology, Energy & Minerals Science Center
link

Trace Elements in Energy Fuels

In this task we conduct new interpretive studies of the concentration and distribution of trace metals and mercury in coal and other energy materials. Complementary studies of coal combustion products are conducted under Task 8. Together with use of existing USGS databases, we examine the potential for reducing emissions of potentially toxic substances by coal preparation, and by optimizing coal...
Learn More

Geochemical Data for Coal Wastes from Bituminous Coal Mining in Pennsylvania, 2022

Coal and coal byproducts may be economically important resources if enriched in critical minerals such as rare earth elements. The organic carbon they contain could be converted to gas using stimulated microbial methanogenesis. In this study, samples were collected from two underground mine sites in the bituminous region of southwest Pennsylvania to assess the potential for these uses from differe
By
Energy Resources Program, Environmental Health Program, Geology, Energy & Minerals Science Center, Pennsylvania Water Science Center, Eastern Energy and Environmental Laboratory (EEEL)

Geochemical Data for Illinois Basin Coal Samples, 2015-2018 (ver. 1.1, March 2021)

Researchers at the U.S. Geological Survey (USGS) and their collaborators conducted a study of the geochemical properties of coals currently produced for electric power generation in the Illinois Basin in Illinois and Indiana. The study follows from recommendations by an expert panel for the USGS to investigate the distribution and controls of trace constituents such as mercury (Hg) in Illinois Bas
By
Energy Resources Program, Geology, Energy & Minerals Science Center

Arsenic in stream sediments of northern Alabama

OVERVIEW OF ARSENIC IN STREAM SEDIMENTS The overall range of arsenic in the NURE stream sediments was from 0.3 to 44 mg/kg sediment (ppm) As in the sample data set. The mean value was 4.3 ppm with a standard deviation of 4.1 ppm. For comparison, the crustal abundance of arsenic is 1.8 ppm (Taylor, 1964). Shale is higher, with average values of 15 ppm. Coal samples from the entire USGS National Coa
Filter Total Items: 52

Rare Earth Elements in coal fly ash and their potential recovery

Coal fly ash is a potential resource of valuable elements, such as rare earth elements (REEs), which are retained and concentrated upon combustion. Understanding REE occurrence within fly ash is vital to developing recovery methods. Some of the highest REE contents occur in fly ash derived from U.S. Appalachian Basin coals, and coals influenced by input volcanic ash are especially enriched. Leachi
Authors
James Hower, Allan Kolker, Heileen Hsu-Kim, Desiree Platta
By
Energy Resources Program, Geology, Energy & Minerals Science Center

Energy-related rare earth element sources

Energy-related materials such as coal, coal-bearing wastes, and coal combustion products are traditionally thought of as sources or by-products of electric power generation. Increasingly, these materials are considered resources for their content of rare earth elements (REEs) and other useful constituents. In this chapter, we examine the distribution, modes of occurrence, and relative extractabili
Authors
Allan Kolker, Liliana Lefticariu, Steven T. Anderson
By
Energy Resources Program, Geology, Energy & Minerals Science Center

Geochemical data for Illinois Basin coal samples, 2015–2018

Researchers at the U.S. Geological Survey (USGS) and their collaborators conducted a study of the geochemical properties of coals currently produced for electric power generation in the Illinois Basin in Illinois and Indiana. The study follows from recommendations by an expert panel for the USGS to investigate the distribution and controls of trace constituents such as mercury (Hg) in Illinois Bas
Authors
Allan Kolker, Clint Scott, Liliana Lefticariu, Maria Mastalerz, Agnieszka Drobniak, Annie Scott
By
Energy and Minerals Mission Area, Energy Resources Program, Geology, Energy & Minerals Science Center

Rare earth elements in coal and coal fly ash

The rare earth elements (REEs) are a group of 17 elements sharing similar chemical properties. They include yttrium (Y, atomic number 39), scandium (Sc, atomic number 21), and the 15 elements of the lanthanide series, atomic numbers 57 (lanthanum, La) to 71 (lutetium, Lu). Because promethium (Pm, atomic number 61) does not occur in the Earth’s crust and scandium typically has different geological
Authors
Clint Scott, Allan Kolker
By
Energy and Minerals Mission Area, Energy Resources Program, Geology, Energy & Minerals Science Center, Reston Electron Microbeam Laboratory

Topics in coal geochemistry—Short course

This short course was prepared at the request of Servicio Geológico Colombiano (SGC) as a module for staff training. Prior to the short course, the SGC expressed interest in receiving training in (1) geochemistry and quality of coal; (2) geochemistry of trace elements in coal; (3) mercury and halogens in coal; (4) characterization and cycling of atmospheric mercury; (5) mercury, trace elements, an
Authors
Allan Kolker
By
Energy Resources Program, Geology, Energy & Minerals Science Center

Mercury in U.S. coal—Priorities for new U.S. Geological Survey studies

In 2011, the U.S. Environmental Protection Agency (EPA) introduced emissions standards, known as Mercury and Air Toxics Standards (MATS), for a range of toxic constituents from coal-fired utility power stations and other combustion sources. This report presents the findings of an expert panel convened in September 2014 to assess the role of the U.S. Geological Survey (USGS) in new coal investigati
Authors
Allan Kolker
By
Energy Resources Program, Geology, Energy & Minerals Science Center

Mercury and trace element distribution in density separates of a South African Highveld (#4) coal: Implications for mercury reduction and preparation of export coal

Eight density separates of Permian Highveld (#4) coal were investigated for partitioning of Hg and trace elements. The separates include float fractions obtained in heavy media having densities of 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, and 2.0 g/cm3, and the sink fraction for 2.0 g/cm3. Bulk analysis of the separates shows strong (R2 ≥ 0.80) positive correlations between pyritic sulfur and mercury, and bet
Authors
Allan Kolker, Connie L. Senior, Chris van Alphen, Alan E. Koenig, Nicholas J. Geboy
By
Energy Resources Program, Geology, Energy & Minerals Science Center

Collaborative Studies for Mercury Characterization in Coal and Coal Combustion Products, Republic of South Africa

Mercury (Hg) analyses were obtained for 42 samples of feed coal provided by Eskom, the national electric utility of South Africa, representing all 13 coal-fired power stations operated by Eskom in South Africa. This sampling includes results for three older power stations returned to service starting in the late 2000s. These stations were not sampled in the most recent previous study. Mercury conc
Authors
Allan Kolker, Constance L. Senior, Chris van Alphen
By
Energy Resources Program, Geology, Energy & Minerals Science Center

Trace elements in coal ash

Coal ash is a residual waste product primarily produced by coal combustion for electric power generation. Coal ash includes fly ash, bottom ash, and flue-gas desulfurization products (at powerplants equipped with flue-gas desulfurization systems). Fly ash, the most common form of coal ash, is used in a range of products, especially construction materials. A new Environmental Protection Agency ruli
Authors
Amrika Deonarine, Allan Kolker, Michael W. Doughten
By
Energy Resources Program, Geology, Energy & Minerals Science Center

Size distribution of rare earth elements in coal ash

Rare earth elements (REEs) are utilized in various applications that are vital to the automotive, petrochemical, medical, and information technology industries. As world demand for REEs increases, critical shortages are expected. Due to the retention of REEs during coal combustion, coal fly ash is increasingly considered a potential resource. Previous studies have demonstrated that coal fly ash is
Authors
Clint Scott, Amrika Deonarine, Allan Kolker, Monique Adams, James F. Holland
By
Energy Resources Program, Geology, Energy & Minerals Science Center

Atmospheric particulate matter in proximity to mountaintop coal mines: Sources and potential environmental and human health impacts

Mountaintop removal mining (MTM) is a widely used approach to surface coal mining in the US Appalachian region whereby large volumes of coal overburden are excavated using explosives, removed, and transferred to nearby drainages below MTM operations. To investigate the air quality impact of MTM, the geochemical characteristics of atmospheric particulate matter (PM) from five surface mining sites i
Authors
Laura Kurth, Allan Kolker, Mark A. Engle, Nicholas J. Geboy, Michael Hendryx, William H. Orem, Michael McCawley, Lynn M. Crosby, Calin A. Tatu, Matthew S. Varonka, Christina A. DeVera
By
Energy Resources Program, Geology, Energy & Minerals Science Center

Mercury and halogens in coal

Apart from mercury itself, coal rank and halogen content are among the most important factors inherent in coal that determine the proportion of mercury captured by conventional controls during coal combustion. This chapter reviews how mercury in coal occurs, gives available concentration data for mercury in U.S. and international commercial coals, and provides an overview of the natural variation
Authors
Allan Kolker, Jeffrey C. Quick
By
Energy Resources Program, Geology, Energy & Minerals Science Center

Non-USGS Publications**

Huggins, F. E., Huffman, G. P., Kolker, Allan, Mroczkowski, S. J., Palmer, C. A., and Finkelman, R. B., 2002, Combined application of XAFS spectroscopy and sequential leaching for determination of arsenic speciation in coal: Energy and Fuels, v. 16, no. 5, p. 1167-1172.
Bunnell, J. E., Garcia, L. V., Furst, J. M., Lerch, Harry, Olea, R.A., Suitt, S.E., and Kolker, Allan, 2010, Navajo coal combustion and respiratory health near Shiprock, New Mexico: Journal of Environmental and Public Health, v. 2010, #260525, 14 p.
Engle, Mark A., Radke, Lawrence F., Heffern, Edward L., O’Keefe, Jennifer M.K., Hower, James C., Smeltzer, Charles D., Hower, Judith M, Olea, Ricardo A., Eatwell, Robert J., Blake, Donald R., Emsbo-Mattingly, Stephen D., Stout, Scott A., Queen, Gerald, Aggen, Kerry L., Kolker, Allan, Prakash, Anupma, Henke, Kevin R., Stracher, Glenn B., Schroeder, Paul A., Román-Colón, Yomayra, and ter Schure, Arnout, 2012, Gas emissions, minerals, and tars associated with three coal fires, Powder River Basin, USA: Science of the Total Environment, v. 420, p. 146-159.
Kolker, Allan, Engle, Mark A., Peuker-Ehrenbrink, Bernhard, Geboy, N. J., Krabbenhoft, D.P., Bothner, M.H., and Tate, M.T., Atmospheric mercury and fine particulate matter at Woods Hole, Cape Cod, MA: Implications for mercury and trace element sources in the northeastern U.S.: Atmospheric Environment, v. 79, p. 760-768.
Kolker, Allan, and Quick, Jeffrey C., 2015, Mercury and halogens in coal, in, Granite, E., Senior, C., and Pennline, H., eds., Mercury control for coal-derived gas steams, Wiley-VCH, p. 13-44.
Kolker, Allan, 2016, Mercury in U.S. Coal- Priorities for New USGS Studies: U.S. Geological Survey Open File Report, in press.
Deonarine, A., Kolker, A., Doughten, M., Bailoo, J.D., and Holland, J.T., Arsenic speciation in bituminous coal fly ash and transformations in response to redox conditions: Submitted to Environmental Science and Technology.

**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.

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