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This article in JEQ

  1. Vol. 43 No. 3, p. 980-994
    Received: Nov 15, 2013
    Published: March 21, 2014

    * Corresponding author(s): andraski@usgs.gov


Soil, Plant, and Terrain Effects on Natural Perchlorate Distribution in a Desert Landscape

  1. B. J. Andraski *a,
  2. W. A. Jacksonb,
  3. T. L. Welborna,
  4. J. K. Böhlkec,
  5. Ritesh Sevanthib and
  6. D.A. Stonestromd
  1. a U.S. Geological Survey, 2730 N. Deer Run Rd., Carson City, NV 89701
    b Texas Tech Univ., MS 41023, Lubbock, TX 79409
    c U.S. Geological Survey, 12201 Sunrise Valley Dr., MS 431, Reston, VA 20192
    d U.S. Geological Survey, 345 Middlefield Rd., MS 420, Menlo Park, CA 94025


Perchlorate (ClO4) is a contaminant that occurs naturally throughout the world, but little is known about its distribution and interactions in terrestrial ecosystems. The objectives of this Amargosa Desert, Nevada study were to determine (i) the local-scale distribution of shallow-soil (0–30 cm) ClO4 with respect to shrub proximity (far and near) in three geomorphic settings (shoulder slope, footslope, and valley floor); (ii) the importance of soil, plant, and terrain variables on the hillslope-distribution of shallow-soil and creosote bush [Larrea tridentata (Sessé & Moc. ex DC.) Coville] ClO4; and (iii) atmospheric (wet plus dry, including dust) deposition of ClO4 in relation to soil and plant reservoirs and cycling. Soil ClO4 ranged from 0.3 to 5.0 μg kg−1. Within settings, valley floor ClO4 was 17× less near shrubs due in part to enhanced leaching, whereas shoulder and footslope values were ∼2× greater near shrubs. Hillslope regression models (soil, R2 = 0.42; leaf, R2 = 0.74) identified topographic and soil effects on ClO4 deposition, transport, and cycling. Selective plant uptake, bioaccumulation, and soil enrichment were evidenced by leaf ClO4 concentrations and Cl/ClO4 molar ratios that were ∼8000× greater and 40× less, respectively, than soil values. Atmospheric deposition ClO4 flux was 343 mg ha−1 yr−1, ∼10× that for published southwestern wet-deposition fluxes. Creosote bush canopy ClO4 (1310 mg ha−1) was identified as a previously unrecognized but important and active reservoir. Nitrate δ18O analyses of atmospheric deposition and soil supported the leaf-cycled–ClO4 input hypothesis. This study provides basic data on ClO4 distribution and cycling that are pertinent to the assessment of environmental impacts in desert ecosystems and broadly transferable to anthropogenically contaminated systems.

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Copyright © 2014. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.