Origin of tungsten and geochemical controls on its occurrence and mobilization in shallow sediments from Fallon, Nevada, USA

Chad Hobson, Harshad V. Kulkarni, Karen H. Johannesson, Anthony Bednar, Ryan Tappero, T. Jade Mohajerin, Paul R. Sheppard, Mark L. Witten, Ganga M. Hettiarachchi, Saugata Datta

Research output: Contribution to journalArticle

Abstract

Tungsten (W) occurrence and speciation was investigated in sediments collected from Fallon, Nevada where previous studies have linked elevated W levels in human body fluids to an unusual cluster of childhood leukemia cases. The speciation of sedimentary W was determined by μ-XRF mapping and μ-XANES. The W content of the analyzed surface sediments ranged between 81 and 25,908 mg/kg, which is significantly higher than the W content in deeper sediments which ranged from 37 to 373 mg/kg at 30 cm depth. The μ-XANES findings reveal that approximately 20–50% of the total W in the shallow sediment occurs in the metallic form (W0); the rest occurs in the oxide form (WVIO3). Because W0 does not occur naturally, its elevated concentrations in surface sediments point toward a possible local anthropogenic origin. The oxidation of metallic W0 with meteoric waters likely leads to the formation of WVIO3. The chief water-soluble W species was identified as WO42− by chromatographic separation and speciation modeling. These results led us to postulate that W0 particles from a currently unknown but local source(s) is (are) deposited onto the soils and/or surface sediments. The W0 in interaction with meteoric water is oxidized to WVIO3, and as these sediment-water interactions progress, WO42− is formed in the water at pH ∼7. Under pH < 7, and sufficient W concentrations, tungstate tends to polymerize, and polymerized species are less likely to adsorb onto sediments. Polymerized species have lower affinity than monomers, which leads to enhanced mobility of W.

Original languageEnglish (US)
Article number127577
JournalChemosphere
Volume260
DOIs
StatePublished - Dec 2020

Keywords

  • Childhood leukemia
  • Sediment-water interface
  • Tungsten
  • Water extractable tungsten
  • μ-XRF mapping

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Chemistry(all)
  • Pollution
  • Health, Toxicology and Mutagenesis

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    Hobson, C., Kulkarni, H. V., Johannesson, K. H., Bednar, A., Tappero, R., Mohajerin, T. J., Sheppard, P. R., Witten, M. L., Hettiarachchi, G. M., & Datta, S. (2020). Origin of tungsten and geochemical controls on its occurrence and mobilization in shallow sediments from Fallon, Nevada, USA. Chemosphere, 260, [127577]. https://doi.org/10.1016/j.chemosphere.2020.127577