Molecular features of uranium-binding natural organic matter in a riparian wetland determined by ultrahigh resolution mass spectrometry.

Autor: Xu C; Department of Marine and Coastal Environmental Science, Texas A & M University, Galveston Campus, Galveston, TX 77553, USA. Electronic address: xuc@tamug.edu., Goranov AI; Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, VA 23529, USA., Kaplan DI; Savannah River Ecology Laboratory, University of Georgia, Aiken, SC 29802, USA., Lin P; Savannah River Ecology Laboratory, University of Georgia, Aiken, SC 29802, USA., Yeager CM; Los Alamos National Laboratory, Los Alamos, NM 87545, USA., Patterson N; Department of Marine and Coastal Environmental Science, Texas A & M University, Galveston Campus, Galveston, TX 77553, USA., Jiang H; Department of Marine and Coastal Environmental Science, Texas A & M University, Galveston Campus, Galveston, TX 77553, USA., Hatcher PG; Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, VA 23529, USA., Santschi PH; Department of Marine and Coastal Environmental Science, Texas A & M University, Galveston Campus, Galveston, TX 77553, USA.
Jazyk: angličtina
Zdroj: The Science of the total environment [Sci Total Environ] 2024 Oct 20; Vol. 948, pp. 174867. Date of Electronic Publication: 2024 Jul 19.
DOI: 10.1016/j.scitotenv.2024.174867
Abstrakt: Tims Branch riparian wetland located in South Carolina, USA has immobilized 94 % of the U released >50 years ago from a nuclear fuel fabrication facility. Sediment organic matter (OM) has been shown to play an important role in immobilizing U. Yet, uranium-OM-mineral interactions at the molecular scale have never been investigated at ambient concentrations. The objectives of this study were to extract, purify, and concentrate U-bound sediment OM along the stream water pathway and perform molecular characterization using Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS). Out of 9614 identified formulas, 715 contained U. These U-containing formulas were enriched with Fe, N, and/or S compared to the total OM. Lignin-like and protein-like molecules accounted for 40 % and 19 % of the U-containing formulas, respectively. Phosphorus-containing formulas were found to exert an insignificant influence on complexing U. U-containing formulas in the 'mobile' (groundwater extractable) OM fraction had lower (reduced) nominal oxidation states of carbon (NOSC); and less aromatic moieties than OM recovered from the 'immobile' (sodium pyrophosphate extractable) OM fraction. U-containing formulas in the redox interfacial zones (stream banks) compared to those in nearby up-slope zones tended to have smaller molecular weights; lower NOSC; higher contents of COO and/or CONO functional groups; and higher abundance of Fe-containing formulas. Fe was present in 38 % of the U-containing formulas but only 20 % of the total OM formulas. It is postulated that Fe played an important role in stabilizing the structure of sedimentary OM, especially U-containing compounds. The identification for the first time of hundreds of Fe-U-OM formulas demonstrates the complexity of such system is much greater than commonly believed and numerically predicting U binding behavior in OM-rich systems may require greater use of statistical or artificial intelligence approaches rather than deterministic approaches limited to measuring metal complexation with well-defined individual analogue organic ligands.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(Copyright © 2024 Elsevier B.V. All rights reserved.)
Databáze: MEDLINE
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