Morphological and chemical characteristics of airborne tungsten particles of Fallon, Nevada

Paul R. Sheppard, Paul Toepfer, Elaine Schumacher, Kent Rhodes, Gary Ridenour, Mark L. Witten

Research output: Contribution to journalArticle

10 Scopus citations

Abstract

Morphological and chemical characteristics were determined for airborne tungsten particles in Fallon, Nevada, a town that is distinguishable environmentally by elevated airborne tungsten and cobalt. From samples of airborne dust collected previously at six different places in Fallon, tungsten-rich dust particles were isolated and analyzed with automated electron microprobe and wavelength-dispersive spectrometry. Representative W particles were further analyzed using transmission electron microscopy. Morphologically, Fallon W particles are angular and small, with minimum and maximum sizes of ≤1 μm and 5.9 μm in diameter, respectively. The number and size of tungsten-rich particles decrease in Fallon with distance from a hard-metal facility located near the center of town. Chemically, Fallon airborne W particles include mixtures of tungsten with cobalt plus other metals such as chromium, iron, and copper. No W-rich particles were identifiable as CaWO 4 (scheelite) or MnWO4 (huebnerite). From d-spacings, Fallon particles are most consistent with identification as tungsten carbide. Based on these multiple lines of evidence, airborne W particles in Fallon are anthropogenic in origin, not natural. The hard-metal facility in Fallon processes finely powdered W and W-Co, and further investigation using tracer particles is recommended to definitively identify the source of Fallon's airborne tungsten.

Original languageEnglish (US)
Pages (from-to)296-303
Number of pages8
JournalMicroscopy and Microanalysis
Volume13
Issue number4
DOIs
StatePublished - Aug 1 2007

Keywords

  • Airborne particles
  • Automated electron microprobe analysis
  • Cobalt
  • Fallon
  • Nevada
  • Transmission electron microscopy
  • Tungsten

ASJC Scopus subject areas

  • Instrumentation

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