Effects of sulfide concentration and dissolved organic matter characteristics on the structure of nanocolloidal metacinnabar

Environmental Science & Technology
By: , and 

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Abstract

Understanding the speciation of divalent mercury (Hg(II)) in aquatic systems containing dissolved organic matter (DOM) and sulfide is necessary to predict the conversion of Hg(II) to bioavailable methylmercury. We used X-ray absorption spectroscopy to characterize the structural order of mercury in Hg(II)–DOM–sulfide systems for a range of sulfide concentration (1–100 μM), DOM aromaticity (specific ultraviolet absorbance (SUVA254)), and Hg(II)–DOM and Hg(II)–DOM–sulfide equilibration times (4–142 h). In all systems, Hg(II) was present as structurally disordered nanocolloidal metacinnabar (β-HgS). β-HgS nanocolloids were significantly smaller or less ordered at lower sulfide concentration, as indicated by under-coordination of Hg(II) in β-HgS. The size or structural order of β-HgS nanocolloids increased with increasing sulfide abundance and decreased with increasing SUVA254 of the DOM. The Hg(II)–DOM or Hg(II)–DOM–sulfide equilibration times did not significantly influence the extent of structural order in nanocolloidal β-HgS. Geochemical factors that control the structural order of nanocolloidal β-HgS, which are expected to influence nanocolloid surface reactivity and solubility, should be considered in the context of mercury bioavailability.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Effects of sulfide concentration and dissolved organic matter characteristics on the structure of nanocolloidal metacinnabar
Series title Environmental Science & Technology
DOI 10.1021/acs.est.7b02687
Volume 51
Issue 22
Year Published 2017
Language English
Publisher ACS
Contributing office(s) National Research Program - Central Branch
Description 10 p.
First page 13133
Last page 13142