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This article in JEQ

  1. Vol. 41 No. 4, p. 1324-1336
    Received: Dec 23, 2011

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


Volatile Organic Compounds in the Unsaturated Zone from Radioactive Wastes

  1. Ronald J. Baker *a,
  2. Brian J. Andraskib,
  3. David A. Stonestromc and
  4. Wentai Luod
  1. a R.J. Baker, U.S. Geological Survey, 810 Bear Tavern Rd., W. Trenton, NJ 08628
    b U.S. Geological Survey, 2730 N. Deer Run Rd., Carson City, NV 89701
    c U.S. Geological Survey, 345 Middlefield Rd., mail stop 420, Menlo Park, CA 94025-3591
    d Portland State Univ., P.O. Box 751, Portland, OR 97207.Assigned to Associate Editor Kurt Spokas. Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government


Volatile organic compounds (VOCs) are often comingled with low-level radioactive wastes (LLRW), but little is known about subsurface VOC emanations from LLRW landfills. The current study systematically quantified VOCs associated with LLRW over an 11-yr period at the USGS Amargosa Desert Research Site (ADRS) in southwestern Nevada. Unsaturated-zone gas samples of VOCs were collected by adsorption on resin cartridges and analyzed by thermal desorption and GC/MS. Sixty of 87 VOC method analytes were detected in the 110-m-thick unsaturated zone surrounding a LLRW disposal facility. Chlorofluorocarbons (CFCs) were detected in 100% of samples collected. Chlorofluorocarbons are powerful greenhouse gases, deplete stratospheric ozone, and are likely released from LLRW facilities worldwide. Soil-gas samples collected from a depth of 24 m and a horizontal distance 100 m south of the nearest waste-disposal trench contained >60,000 ppbv total VOCs, including >37,000 ppbv CFCs. Extensive sampling in the shallow unsaturated zone (0–2 m deep) identified areas where total VOC concentrations exceeded 5000 ppbv at the 1.5-m depth. Volatile organic compound concentrations exceeded background levels up to 300 m from the facility. Maximum vertical diffusive fluxes of total VOCs were estimated to be 1 g m−2 yr−1. Volatile organic compound distributions were similar but not identical to those previously determined for tritium and elemental mercury. To our knowledge, this study is the first to characterize the unsaturated zone distribution of VOCs emanating from a LLRW landfill. Our results may help explain anomalous transport of radionuclides at the ADRS and elsewhere.

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