Mark F. Coolbaugh

Assessing the contribution of natural sources to regional atmospheric mercury budgets

Naturally mercury-enriched substrate is a long-lived source of mercury to the global atmospheric mercury cycle. Field flux chambers, laboratory gas exchange chambers and micrometeorological methods may be applied to estimate emissions from these sources. However, field chamber experimental design may affect the magnitude of the fluxes measured, and the laboratory chamber only provides a minimum estimate of flux. Many factors, such as mercury concentration and speciation in substrate, light, precipitation, and temperature, influence the emission of mercury from the substrate. Mercury concentration in the substrate is a dominant factor controlling emissions and may be used to predict emissions from regions of mercury enrichment. Mercury fluxes measured from three areas of natural enrichment and three areas with low levels of mercury enrichment are 1-5 orders of magnitude greater than the value applied to global belts of natural enrichment. Preliminary scaling of emissions from one of these areas and for western North America indicates that mercury enriched areas may be significant sources of mercury to the atmosphere, and that their contribution to regional and global atmospheric budgets needs to be reassessed.

Effect of Reduced Spatial Resolution on Mineral Mapping Using Imaging Spectrometry—Examples Using Hyperspectral Infrared Imager (HyspIRI)-Simulated Data

The Hyperspectral Infrared Imager (HyspIRI) is a proposed NASA satellite remote sensing system combining a visible to shortwave infrared (VSWIR) imaging spectrometer with over 200 spectral bands between 0.38 and 2.5 μm and an 8-band thermal infrared (TIR) multispectral imager, both at 60 m spatial resolution. Short Wave Infrared (SWIR) (2.0-2.5 μm) simulation results are described here using Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data in preparation for the future launch. The simulated data were used to assess the effect of the HyspIRI 60 m spatial resolution on the ability to identify and map minerals at hydrothermally altered and geothermal areas. Mineral maps produced using these data successfully detected and mapped a wide variety of characteristic minerals, including jarosite, alunite, kaolinite, dickite, muscovite-illite, montmorillonite, pyrophyllite, calcite, buddingtonite, and hydrothermal silica. Confusion matrix analysis of the datasets showed overall classification accuracy ranging from 70 to 92% for the 60 m HyspIRI simulated data relative to 15 m spatial resolution data. Classification accuracy was lower for similar minerals and smaller areas, which were not

Characterization of hydrothermal systems using simulated HyspIRI data

The Hyperspectral Infrared Imager (HyspIRI) is a proposed NASA satellite remote sensing system combining a visible to shortwave infrared (VSWIR) imaging spectrometer with over 200 spectral bands between 0.38 – 2.5 micrometers and an 8-band thermal infrared (TIR) multispectral imager. ©± We have begun data and analysis simulations using airborne data in preparation for the future launch. Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data with 224 spectral bands and multispectral TIR data from the MODIS/ASTER Airborne Simulator (MASTER) and the MODIS Airborne Simulator (MAS) sensors are being used to simulate the spectral and spatial HyspIRI response. The combined datasets, applied to measurement of geothermal and hydrothermal systems, successfully identify and map minerals such as goethite, hematite, jarosite, kaolinite, dickite, alunite, buddingtonite, montmorillonite, muscovite-illite, calcite, and hydrothermal silica. The TIR data were also used to extract elevated surface temperatures at active hot springs areas. The simulations demonstrate that HyspIRI data, while limited by their relatively coarse (60m) spatial resolution should still be useful for many geologic applications.

Geothermal exploration with hyperspectral data in the Carson Sink, Nevada

Hyperspectral data was acquired over two geothermally active study areas in west-central Nevada. Carbonate and opaline sinter deposits associated with upwelling geothermal fluids were remotely mapped. Our results identified previously unmapped sinter outcrops and structurally controlled tufa, which both indicate fault traces acting as geothermal fluid pathways.

Characterizing controls of geothermal systems through integrated geologic and geophysical studies: Developing recipes for successful exploration of conventional and unconventional geothermal systems

Although conventional geothermal systems have been successfully exploited for electrical production and district heating in many parts of the world, exploration and development of new systems is commonly stymied by the risk of unsuccessful drilling. Problems include drilling of hot, relatively dry wells with low flow rates, decreasing temperatures with depth as wells penetrate relatively thin and shallow geothermal aquifers (overturn), and wells with reasonable flow rates but relatively low temperatures. Due to the high cost of drilling, such problems can effectively preclude geothermal exploration. Proposals to generate enhanced geothermal systems (EGS) by artificially stimulating hot dry wells, commonly through mechanical hydro-fracturing of rocks, have therefore gained in popularity.