Todd Hoefen
Todd Hoefen is a Geophysicist with the Geology, Geophysics, and Geochemistry Science Center.
Science and Products
Hyperspectral surface materials map of quadrangle 3468, Chak-e Wardak-Siyahgird (509) and Kabul (510) quadrangles, Afghanistan, showing iron-bearing minerals and other materials
Hyperspectral surface materials map of quadrangle 3468, Chak-e Wardak-Siyahgird (509) and Kabul (510) quadrangles, Afghanistan, showing carbonates, phyllosilicates, sulfates, altered minerals, and other materials
Hyperspectral surface materials map of quadrangles 3668 and 3768, Baghlan (221), Taluqan (222), Imam Sahib (215), and Rustaq (216) quadrangles, Afghanistan, showing iron-bearing minerals and other materials
Hyperspectral surface materials map of quadrangles 3668 and 3768, Baghlan (221), Taluqan (222), Imam Sahib (215), and Rustaq (216) quadrangles, Afghanistan, showing carbonates, phyllosilicates, sulfates, altered minerals, and other materials
Preparation and characterization of "Libby Amphibole" toxicological testing material
Simultaneous speciation of arsenic, selenium, and chromium: species, stability, sample preservation, and analysis of ash and soil leachates
Shoreline surveys of oil-impacted marsh in southern Louisiana, July to August 2010
The dispersion of fibrous amphiboles by glacial processes in the area surrounding Libby, Montana, USA
Simultaneous speciation of arsenic, selenium, and chromium: Species stability, sample preservation, and analysis of ash and soil leachates
Mapping the distribution of materials in hyperspectral data using the USGS Material Identification and Characterization Algorithm (MICA)
Identifying materials by measuring and analyzing their reflectance spectra has been an important method in analytical chemistry for decades. Airborne and space-based imaging spectrometers allow scientists to detect materials and map their distributions across the landscape. With new satellite-borne hyperspectral sensors planned for the future, for example, HYSPIRI (HYPerspectral InfraRed Imager),
Speciation of arsenic, selenium, and chromium in wildfire impacted soils and ashes
Detection and mapping of hydrocarbon deposits on Titan
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Hyperspectral surface materials map of quadrangle 3468, Chak-e Wardak-Siyahgird (509) and Kabul (510) quadrangles, Afghanistan, showing iron-bearing minerals and other materials
This map shows the spatial distribution of selected iron-bearing minerals and other materials derived from analysis of airborne HyMap™ imaging spectrometer (hyperspectral) data of Afghanistan collected in late 2007. This map is one in a series of U.S. Geological Survey/Afghanistan Geological Survey quadrangle maps covering Afghanistan. Flown at an altitude of 50,000 feet (15,240 meters (m)), theAuthorsTrude V.V. King, Todd M. Hoefen, Raymond F. Kokaly, Keith E. Livo, Stuart A. Giles, Michaela R. JohnsonHyperspectral surface materials map of quadrangle 3468, Chak-e Wardak-Siyahgird (509) and Kabul (510) quadrangles, Afghanistan, showing carbonates, phyllosilicates, sulfates, altered minerals, and other materials
This map shows the spatial distribution of selected carbonates, phyllosilicates, sulfates, altered minerals, and other materials derived from analysis of airborne HyMap™ imaging spectrometer (hyperspectral) data of Afghanistan collected in late 2007. The map is one in a series of U.S. Geological Survey/Afghanistan Geological Survey quadrangle maps covering Afghanistan. Flown at an altitude of 50,AuthorsRaymond F. Kokaly, Trude V.V. King, Todd M. Hoefen, Keith E. Livo, Stuart A. Giles, Michaela R. JohnsonHyperspectral surface materials map of quadrangles 3668 and 3768, Baghlan (221), Taluqan (222), Imam Sahib (215), and Rustaq (216) quadrangles, Afghanistan, showing iron-bearing minerals and other materials
This map shows the spatial distribution of selected iron-bearing minerals and other materials derived from analysis of airborne HyMap™ imaging spectrometer (hyperspectral) data of Afghanistan collected in late 2007. This map is one in a series of U.S. Geological Survey/Afghanistan Geological Survey quadrangle maps covering Afghanistan. Flown at an altitude of 50,000 feet (15,240 meters (m)), theAuthorsTrude V.V. King, Todd M. Hoefen, Raymond F. Kokaly, Keith E. Livo, Michaela R. Johnson, Stuart A. GilesHyperspectral surface materials map of quadrangles 3668 and 3768, Baghlan (221), Taluqan (222), Imam Sahib (215), and Rustaq (216) quadrangles, Afghanistan, showing carbonates, phyllosilicates, sulfates, altered minerals, and other materials
This map shows the spatial distribution of selected carbonates, phyllosilicates, sulfates, altered minerals, and other materials derived from analysis of airborne HyMap™ imaging spectrometer (hyperspectral) data of Afghanistan collected in late 2007. The map is one in a series of U.S. Geological Survey/Afghanistan Geological Survey quadrangle maps covering Afghanistan. Flown at an altitude of 5AuthorsRaymond F. Kokaly, Trude V.V. King, Todd M. Hoefen, Keith E. Livo, Michaela R. Johnson, Stuart A. GilesPreparation and characterization of "Libby Amphibole" toxicological testing material
The U.S. Environmental Protection Agency (USEPA) began work in Libby, Mont. in 1999 when an Emergency Response Team was sent to investigate local concern and media reports regarding asbestos-contaminated vermiculite. Since that time, the site has been granted Superfund status and site remediation to a safe level of asbestos has been ongoing. The amphibole asbestos from the Vermiculite Mountain verAuthorsHeather Lowers, Stephen A. Wilson, Todd M. Hoefen, William Benzel, Gregory P. MeekerSimultaneous speciation of arsenic, selenium, and chromium: species, stability, sample preservation, and analysis of ash and soil leachates
An analytical method using high-performance liquid chromatography separation with inductively coupled plasma mass spectrometry (ICP-MS) detection previously developed for the determination of Cr(III) and Cr(VI) has been adapted to allow the determination of As(III), As(V), Se(IV), Se(VI), Cr(III), and Cr(VI) under the same chromatographic conditions. Using this method, all six inorganic species caAuthorsRuth E. Wolf, Suzette A. Morman, Philip L. Hageman, Todd M. Hoefen, Geoffrey S. PlumleeShoreline surveys of oil-impacted marsh in southern Louisiana, July to August 2010
This report describes shoreline surveys conducted in the marshes of Louisiana in areas impacted by oil spilled from the Deepwater Horizon offshore oil drilling platform in the Gulf of Mexico. Three field expeditions were conducted on July 7-10, August 12-14, and August 24-26, 2010, in central Barataria Bay and the Bird's Foot area at the terminus of the Mississippi River delta. This preliminary reAuthorsRaymond F. Kokaly, David Heckman, JoAnn Holloway, Sarai C. Piazza, Brady R. Couvillion, Gregory D. Steyer, Christopher T. Mills, Todd M. HoefenThe dispersion of fibrous amphiboles by glacial processes in the area surrounding Libby, Montana, USA
Mining operations began at a world-class vermiculite deposit at Vermiculite Mountain near Libby, Montana, circa 1920 and ended in 1990. Fibrous and asbestiform amphiboles intergrown with vermiculite ore are suspected to be a causative factor in an abnormally high number of cases of respiratory diseases in former mine and mill workers, and in residents of Libby. The question addressed in this reporAuthorsWilliam H. Langer, Bradley S. Van Gosen, Gregory P. Meeker, David T. Adams, Todd M. HoefenSimultaneous speciation of arsenic, selenium, and chromium: Species stability, sample preservation, and analysis of ash and soil leachates
An analytical method using high-performance liquid chromatography separation with inductively coupled plasma mass spectrometry (ICP-MS) detection previously developed for the determination of Cr(III) and Cr(VI) has been adapted to allow the determination of As(III), As(V), Se(IV), Se(VI), Cr(III), and Cr(VI) under the same chromatographic conditions. Using this method, all six inorganic species caAuthorsR.E. Wolf, S.A. Morman, P. L. Hageman, T.M. Hoefen, G.S. PlumleeMapping the distribution of materials in hyperspectral data using the USGS Material Identification and Characterization Algorithm (MICA)
Identifying materials by measuring and analyzing their reflectance spectra has been an important method in analytical chemistry for decades. Airborne and space-based imaging spectrometers allow scientists to detect materials and map their distributions across the landscape. With new satellite-borne hyperspectral sensors planned for the future, for example, HYSPIRI (HYPerspectral InfraRed Imager),
AuthorsRaymond F. Kokaly, T. V. V. King, Todd M. HoefenSpeciation of arsenic, selenium, and chromium in wildfire impacted soils and ashes
In 2007-09, California experienced several large wildfires that damaged large areas of forest and destroyed many homes and buildings. The U.S. Geological Survey collected samples from the Harris, Witch, Grass Valley, Ammo, Santiago, Canyon, Jesusita, and Station fires for testing to identify any possible characteristics of the ashes and soils from burned areas that may be of concern for their impaAuthorsRuth E. Wolf, Todd M. Hoefen, Philip L. Hageman, Suzette A. Morman, Geoffrey S. PlumleeDetection and mapping of hydrocarbon deposits on Titan
We report the identification of compounds on Titan's surface by spatially resolved imaging spectroscopy methods through Titan's atmosphere, and set upper limits to other organic compounds. We present evidence for surface deposits of solid benzene (C6H6), solid and/or liquid ethane (C2H6), or methane (CH4), and clouds of hydrogen cyanide (HCN) aerosols using diagnostic spectral features in data froAuthorsRoger N. Clark, J. M. Curchin, Jason W. Barnes, Ralf Jaumann, Laurence A. Soderblom, Dale P. Cruikshank, Robert H. Brown, Sebastien Rodriguez, Jonathan Lunine, Katrin Stephan, Todd M. Hoefen, Stephane Le Mouelic, Christophe Sotin, Kevin H. Baines, Bonnie J. Buratti, Philip D. Nicholson - Web Tools
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