HR: 1340h
AN: H33E-1691    [Abstracts]
TI: Systematics of Natural Perchlorate in Precipitation, Soils, and Plants at the Amargosa Desert Research Site, Nye County, Nevada
AU: * Andraski, B J
EM: andraski@usgs.gov
AF: U.S. Geological Survey, 2730 N. Deer Run Road, Carson City, NV 89701, United States
AU: Stonestrom, D A
EM: dastones@usgs.gov
AF: U.S. Geological Survey, 345 Middlefield Road, Menlo Park, CA 94025, United States
AU: Jackson, W A
EM: andrew.jackson@ttu.edu
AF: Texas Tech University, Mail Stop 41023, Lubbock, TX 79409, United States
AU: Rajagopalan, S
EM: srinath.rajagopalan@ttu.edu
AF: Texas Tech University, Mail Stop 41023, Lubbock, TX 79409, United States
AU: Taylor, E M
EM: emtaylor@usgs.gov
AF: U.S. Geological Survey, Denver Federal Center, P.O. Box 25046, Lakewood, CO 80225, United States
AB: Naturally occurring perchlorate is known to be associated with nitrate deposits of the hyperarid Atacama Desert in Chile, and recent large-scale sampling has identified a substantial reservoir (up to 1 kg/ha) of natural perchlorate in diverse unsaturated zones of the arid and semiarid Southwestern United States (Rao et al., 2007, ES&T, DOI: 10.1021/es062853i). The objective of the Amargosa Desert work is to develop a better understanding of the deposition, accumulation, and biological cycling of perchlorate in arid environments. Occurrence of perchlorate was evaluated by sampling shallow soil profiles up to 3 m in depth at four different locations and at two different time periods, and by sampling dominant plant species growing near the subsurface profiles. Deposition of perchlorate was evaluated by analyzing both bulk deposition (precipitation plus dry fall, collected under oil) collected on site and wet deposition samples collected by the National Atmospheric Deposition program at a nearby site. Soil samples and atmospheric-deposition samples were tested for both perchlorate (ClO₄^- ) and major anions. Perchlorate concentrations (0.2-20 µg/kg) were variable with depth in soil profiles and generally correlated most highly with chloride (Cl^-) and nitrate (NO₃^-), although the intensity of these relations differed among profiles. Plant concentrations were generally above 1 mg/kg, suggesting ClO₄^- accumulation. Concentrations of ClO₄^- were generally much greater in total deposition than wet deposition samples, indicating a substantial dryfall component of meteoric deposition. This presentation will present the mass distribution and variability of perchlorate in bulk deposition, soils, and plants. Reasons for observed relations between subsurface concentrations of perchlorate and other anions will be explored.
UR: http://nevada.usgs.gov/adrs/
DE: 1843 Land/atmosphere interactions (1218, 1631, 3322)
DE: 1852 Plant uptake
DE: 1875 Vadose zone
SC: Hydrology [H]
MN: 2007 Fall Meeting