Impacts of Sediment Particle Grain Size and Mercury Speciation on Mercury Bioavailability Potential

Jiang Xu, Garret D. Bland, Yuan Gu, Hasti Ziaei, Xiaoyue Xiao, Amrika Deonarine, Danny Reible, Paul Bireta, Thomas P. Hoelen, Gregory V. Lowry

Research output: Contribution to journalArticlepeer-review

Abstract

Particle-specific properties, including size and chemical speciation, affect the reactivity of mercury (Hg) in natural systems (e.g., dissolution or methylation). Here, terrestrial, river, and marine sediments were size-fractionated and characterized to correlate particle-specific properties of Hg-bearing solids with their bioavailability potential and measured biomethylation. Marine sediments contained ∼20-50% of the total Hg in the <0.5 μm size fraction, compared to only 0.5 and 3.0% in this size fraction for terrestrial and river sediments, respectively. X-ray absorption spectroscopy (XAS) analysis indicated that metacinnabar (β-HgS) was the main mercury species in a marine sediment, whereas organic Hg-thiol (Hg(SR)2) was the main mercury species in a terrestrial sediment. Single-particle inductively coupled plasma time-of-flight mass spectrometry analysis of the marine sediment suggests that half of the Hg in the <0.5 μm size fraction existed as individual nanoparticles, which were β-HgS based on XAS analyses. Glutathione-extractable mercury was higher for samples containing Hg(SR)2species than β-HgS species and correlated well with the amount of Hg biomethylation. This particle-scale understanding of how Hg speciation and particle size affect mercury bioavailability potential helps explain the heterogeneity in Hg methylation in natural sediments.

Original languageEnglish
Pages (from-to)12393-12402
Number of pages10
JournalEnvironmental Science and Technology
Volume55
Issue number18
DOIs
StatePublished - Sep 21 2021

Keywords

  • mercury association
  • mercury bioavailability proxy
  • mercury methylation
  • mercury methylation indicator
  • mercury nanoparticles
  • sediment contamination
  • spICP-TOF-MS

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