metadata.txt

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Identification_Information:
  Citation:
    Citation_Information:
      Originator: Reheis, Marith C.
      Originator: Kihl, Rolf
      Publication_Date: 1995
      Title:
                  Dust Deposition in Southern Nevada and California, 1984-
                  1989: Relations to climate, source area, and lithology
      Edition: 1
      Series_Information:
        Series_Name: Journal of Geophysical Research
        Issue_Identification: volume 100(D5), pages 8893-8918
      Publication_Information:
        Publication_Place:
        Publisher:
      Online_Linkage: <URL:http://geochange.er.usgs.gov/pub/dust/Core/meta/report.html>
  Description:
    Abstract:
              Dust samples taken annually for five years from 55 sites in
              southern Nevada and California provide an unparalleled source
              of information on modern rates of dust deposition, grain size,
              and mineralogical and chemical composition.  The relations of
              modern dust to climatic factors, type and lithology of dust
              source, and regional wind patterns shed new light on the
              processes of dust entrainment and deposition.
              A project to study modern dust deposition relative to soils in
              southern Nevada and California was initiated in 1984 under the
              auspices of the Yucca Mountain Site Characterization Project
              (Interagency Agreement DE-AI08-78ET44802).  The primary purpose
              of the dust-deposition project was to provide data on modern
              dust composition and influx rates to a computer model relating
              soil carbonate to paleoclimate.  A secondary purpose was to
              provide data on dust influx rates at specific sites in the
              southern Great Basin and Mojave Desert where soil
              chronosequences were studied in support of tectonic and
              stratigraphic investigations for the Yucca Mountain Project.
              The initial 46 sampling sites, including one site with five
              traps, were established in 1984 and were supplemented by nine
              more sites in 1985 to provide dust data to soil studies by
              other investigators along the Elsinore Fault and in the
              Transverse Ranges of southern California.
    Purpose:
              The purpose of this research is to obtain data on the
              composition and deposition rate of eolian dust in southern
              Nevada and California from 1984 to 1989, and to relate these
              properties to controlling variables such as climate, lithology
              of local dust source, and type of source.  Further work will
              relate modern dust to soil properties and compare modern rates
              of dust influx with long-term rates estimated from soils at
              selected sites.
  Time_Period_of_Content:
    Time_Period_Information:
      Range_of_Dates/Times:
        Beginning_Date: 1984
        Ending_Date: 1989
    Currentness_Reference:
              1984 was the first year dust traps were deployed for this
              study; 1989 was the last year in which dust samples described
              in this report were collected.
  Status:
    Progress: Complete
    Maintenance_and_Update_Frequency: Irregular
  Spatial_Domain:
    Bounding_Coordinates:
      West_Bounding_Coordinate: -118.0
      East_Bounding_Coordinate: -114.0
      North_Bounding_Coordinate: 38.25
      South_Bounding_Coordinate: 32.50
  Keywords:
    Theme:
      Theme_Keyword_Thesaurus: None
      Theme_Keyword: Dust
      Theme_Keyword: Dust deposition rates
      Theme_Keyword: Chemistry
      Theme_Keyword: Mineralogy
    Place:
      Place_Keyword_Thesaurus: None
      Place_Keyword: CA
      Place_Keyword: California
      Place_Keyword: NV
      Place_Keyword: Nevada
  Access_Constraints: none
  Use_Constraints: none
  Point_of_Contact:
    Contact_Information:
      Contact_Person_Primary:
        Contact_Person: Marith Reheis
      Contact_Address:
        Address_Type: mailing address
        Address:
                      Box 25046, MS 913
                      U.S. Geological Survey
                      Denver Federal Center
        City: Denver
        State_or_Province: CO
        Postal_Code: 80225-0046
        Country: USA
      Contact_Voice_Telephone: [phone]
      Contact_Facsimile_Telephone: [phone]
Data_Quality_Information:
  Attribute_Accuracy:
    Attribute_Accuracy_Report:
              Samples were obtained from the dust traps by carefully washing
              the marbles, screen, and pan with distilled water into plastic
              liter bottles.  In the laboratory, the sample was gradually
              dried at about 35癈 in large evaporating dishes; coarse
              organic material is removed during this process.  Subsequent
              analyses on dust samples included, in the order they were
              performed:  (1) moisture, (2) organic matter, (3) soluble
              salts and gypsum, (4) total carbonate (calcite plus
              dolomite), (5) grain size, (6) major-oxide chemistry, and
              (7) mineralogy (sand, silt, and clay fractions).  The database
              for any given site commonly contains gaps depending on how far
              the sample for a particular year could be stretched through
              the analytical cascade.  In some cases, samples from different
              years at the same site or adjacent sites were combined to
              obtain enough material for measuring grain size.
              A sample was commonly retrieved and used in more than one
              analysis if the first analytical procedure used was non-
              destructive.  These sequential analytical techniques
              included: (1) Moisture and organic-matter content (Walkley-
              Black procedure in Black, 1965)  were measured on the same
              split using 0.05 g.  (2) The entire sample was used to extract
              the solution to measure soluble salts (Jackson, 1958) and was
              then dried and recovered; thus, subsequent analyses were
              performed on samples without soluble salts.  (3)  A 0.25-g
              split was used to analyze total carbonate (Chittick procedure
              in Singer and Janitzky, 1986).   This split, free of carbonate
              after the analysis, was recovered and used to analyze for
              major oxides and zirconium.  (4) When sufficient sample (0.4g)
              existed to obtain grain size using the Sedigraph rather
              than by pipette analysis, the clay and silt fractions were
              saved and used to analyze mineralogy by X-ray diffraction.
              Most of the laboratory analyses were performed in the
              Sedimentation Laboratory of the Institute of Arctic and Alpine
              Research in Boulder, Colorado, using standard laboratory
              techniques for soil samples (see Black, 1965, and Singer and
              Janitzky, 1986) that we adapted for use on very small samples
              (the non-organic content of a dust sample collected from one
              trap typically weighs less than 1 g/yr).  These adaptations
              generally result in larger standard errors than normal for the
              results of different techniques because the amount of sample
              used is smaller than the recommended amount.
  Logical_Consistency_Report:
          The sampling design for this study was not statistically based;
          rather, sites were chosen to provide data on dust influx at soil-
          study sites and to answer specific questions about the relations
          of dust to local source lithology and type, distance from source,
          and climate.   Some sites were chosen for their proximity to
          potential dust sources of different lithologic composition (for
          example, playas versus granitic, calcic, or mafic alluvial fans).
          Other sites were placed along transects crossing topographic
          barriers downwind from a dust source.  These transects include
          sites east of Tonopah (43-46) crossing the rhyolitic Kawich Range,
          sites downwind of northern (40, 35, 36) and central Death Valley (
          38, 39, 11-14) crossing the mixed-lithology Grapevine and Funeral
          Mountains, respectively, and sites downwind of Desert Dry Lake
          crossing the calcareous Sheep Range (47-50) north of Las Vegas.
          In addition, some sites were chosen for their proximity to weather
          stations.
          Specific locations for dust traps were chosen on the basis of the
          above criteria plus accessibility, absence of dirt roads or other
          artificially disturbed areas upwind, and inconspicuousness.  The
          last factor is important because the sites are not protected or
          monitored; hence, most sites are at least 0.5 mile from a road or
          trail.  Despite these precautions, dust traps are sometimes
          tampered with, often violently.  This is a particular problem in
          areas close to population centers, and most of these sites (52-55
          near Los Angeles and 17-19 and 22 near Las Vegas) have been
          abandoned.  A few other sites, mostly those that appeared to be
          greatly influenced by nearby farming (20, 21, and 41), were
          eliminated in 1989.  Dust traps were also generally placed in
          flat, relatively open areas to mitigate wind-eddy effects created
          by tall vegetation or topographic irregularities.
          See notes in the Attribute_Accuracy_Report regarding combination
          of samples too small for individual analyses.  Generally the data
          from ICP, oxides, and mineralogy are for combined samples.
  Completeness_Report:
          The 55 sites established in 1984 and 1985 were sampled annually
          through 1989 in order to establish an adequate statistical basis
          to calculate annual dust flux.  Sampling continues at 37 of these
          sites (many sites now have two or more dust traps) every two or
          three years as opportunity and funding permit.
          The most important factors that influenced dust-trap design in
          this study were:  (1) measuring the amount of dust added to
          soils; (2) sampling on an annual basis; (3) no protection other
          than being hard to find; and (4) the cost and ready availability
          of components that might have to be replaced from sources in small
          towns.  The original design consists of a single-piece Teflon-
          coated angel-food cake pan (see note 1) painted flat black on the
          outside to maximize water evaporation and mounted on a steel fence
          post about 2 m above the ground.  A circular piece of 1/4-inch-
          mesh galvanized hardware cloth is fitted into the pan so that it
          rests 3-4 cm below the rim, and glass marbles fill the upper part
          of the pan above the hardware cloth.  The Teflon coating is non-
          reactive and adds no mineral contamination to the dust sample
          should it flake.  The hardware cloth resists weathering under
          normal conditions.  The 2-m height eliminates most sand-sized
          particles that travel by saltation rather than by suspension in
          air; sand grains are not generally pertinent to soil genesis
          because they are too large to be translocated downward into soil
          profiles.  The marbles imitate the effect of a gravelly fan
          surface and prevent dust that has filtered or washed into the
          bottom of the pan from being blown away.  The empty space below
          the hardware cloth provides a reservoir that prevents water from
          overflowing the pan during large storms.  This basic design was
          modified in 1986 in two ways.  In many areas, the traps became
          favored perching sites for a wide variety of birds.  As a result,
          significant amounts of non-eolian sediment were locally added to
          the samples (as much as five times the normal amount of dust at
          some sites).   All dust traps were fitted with two metal straps
          looped in an inverted basket shape over the top and the top
          surfaces of the straps were coated with Tanglefoot1.  This sticky
          material never dries (although it eventually becomes saturated
          with dust and must be reapplied) and effectively discourages birds
          from roosting.  In addition, extra dust traps surrounded by alter-
          type wind baffles were constructed at four sites characterized by
          different plant communities.   These communities and sites are:
          blackbrush (Coleogyne ramosissima), creosote bush (Larrea
          divaricata), and other low brushy plants at sites 1-5 on Fortymile
          Wash; Joshua tree (Yucca brevifolia), other tall yucca species,
          and blackbrush at site 18 on the Kyle Canyon fan; pinyon-juniper
          (Pinus monophylla-Juniperus sp) at site 7 on Pahute Mesa; and
          acacia (acacia sp), creosote bush, and blackbrush at site 26 near
          the McCoy Mountains.  The wind baffles imitate the effect of