Paper No. 21
Presentation Time: 9:00 AM-6:00 PM

SOURCES OF ARSENIC IN DUST-GENERATING SOILS FROM THE NELLIS DUNES OFF-ROAD VEHICLES RECREATIONAL AREA, NEVADA, USA


HAGGARD, Sarah1, RIVAS, Cristina1, CAFFEE, Stephanie1, ARMENTA, Anyannete2, REYES, Jocelyn3, BUCK, Brenda4, GOOSSENS, Dirk4, SOUKUP, Debbie4, HORTON, Robert A.1 and BARON, Dirk1, (1)Department of Geological Sciences, California State University, Bakersfield, 62SCI, 9001 Stockdale Highway, Bakersfield, CA 93311, (2)Mira Monte High School, 1800 S. Fairfax Road, Bakersfield, CA 93307, (3)Golden Valley High School, 801 Hosking Avenue, Bakersfield, CA 93307, (4)Department of Geoscience, University of Nevada Las Vegas, 4505 South Maryland Parkway, Box 454010, Las Vegas, NV 89154-4010, dbaron@csub.edu

Dust from the Nellis Dunes Recreational Area in Nevada has been found to contain up to 312 µg g-1 of total arsenic and up to 14.7 µg g-1 of soluble arsenic (Soukup et al, 2012). This presents a potential health hazard not only to the over 300,000 annual visitors but also possibly to residents of nearby Las Vegas. In this study, soils that generate dust were examined with a scanning electron microscope (SEM) equipped with energy-dispersive and wavelength-dispersive spectrometers (EDS and WDS). Many grains are coated by several µm thick layers of microcrystalline alumino-silicates, most likely clays. Some of these coatings also contain thin (typically <1µm) layers and masses of iron-oxyhydroxides intermixed with the clays. SEM-EDS showed measurable concentrations of arsenic in the iron-oxyhydroxide layers. SEM-WDS shows significant arsenic concentrations of up to 3% weight percent associated with the iron-oxyhydroxides, but actual arsenic levels in oxyhydroxides are likely higher because the ~10µm electron-beam spot size resulted in a significant volume of silicates being included in the analyses. Our identification of the actual arsenic carrier will be useful for developing strategies to manage this hazard.