TY - JOUR
T1 - Origin of tungsten and geochemical controls on its occurrence and mobilization in shallow sediments from Fallon, Nevada, USA
AU - Hobson, Chad
AU - Kulkarni, Harshad V.
AU - Johannesson, Karen H.
AU - Bednar, Anthony
AU - Tappero, Ryan
AU - Mohajerin, T. Jade
AU - Sheppard, Paul R.
AU - Witten, Mark L.
AU - Hettiarachchi, Ganga M.
AU - Datta, Saugata
N1 - Publisher Copyright:
© 2020 Elsevier Ltd
PY - 2020/12
Y1 - 2020/12
N2 - 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.
AB - 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.
KW - Childhood leukemia
KW - Sediment-water interface
KW - Tungsten
KW - Water extractable tungsten
KW - μ-XRF mapping
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U2 - 10.1016/j.chemosphere.2020.127577
DO - 10.1016/j.chemosphere.2020.127577
M3 - Article
C2 - 32758784
AN - SCOPUS:85088363733
SN - 0045-6535
VL - 260
JO - Chemosphere
JF - Chemosphere
M1 - 127577
ER -