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Precipitation of nanoscale mercuric sulfides in the presence of natural organic matter: Structural properties, aggregation, and biotransformation

Publication ,  Journal Article
Pham, ALT; Morris, A; Zhang, T; Ticknor, J; Levard, C; Hsu-Kim, H
Published in: Geochimica et Cosmochimica Acta
May 15, 2014

Mercuric sulfide species are likely the predominant forms of mercury (Hg) in anoxic environments where the bioavailability of Hg is a key factor for the production of methylmercury (MeHg) by microorganisms. Dissolved organic matter (DOM) is known to affect the formation, aggregation, and dissolution of HgS particles; however the connection of these processes to Hg bioavailability is not well understood. The objectives of this study were to gain insights into the molecular structure and aggregation properties of nanoscale HgS particles that were formed and aged in the presence of DOM and to link this information to bioavailability for methylating bacteria. Characterization of nanoscale HgS was performed with a series of techniques including transmission electron microscopy, photon scattering, X-ray diffraction, and X-ray absorption spectroscopy. The characterization results indicated that the HgS precipitates formed were metacinnabar-like spherical nanoparticles that were 3-5. nm in diameter. Over the course of the aging process, HgS nanoparticles (nano-HgS) agglomerated to form mass-fractal aggregates, although the size of each primary particle within the aggregates remained unchanged. Furthermore, the crystallinity of nano-HgS increased as the particles aged. The methylation potential of nano-HgS by sulfate-reducing bacteria decreased during the aging process. No clear correlation was observed between the net productions of MeHg and the concentrations of dissolved Hg(II) in the culture media, suggesting that the decrease in the methylation potential of aged nano-HgS was not simply because of the slower supply of dissolved Hg(II) by nano-HgS. While the link between the aging of nano-HgS and decrease of methylation potential is not fully understood, the results of our study indicate that freshly formed HgS particles in DOM-rich water will include a variety of nanoscale structures that have a wide range of methylation potentials. This knowledge provides a basis for better prediction of mercury bioavailability and MeHg production in contaminated environments. © 2014 Elsevier Ltd.

Duke Scholars

Published In

Geochimica et Cosmochimica Acta

DOI

ISSN

0016-7037

Publication Date

May 15, 2014

Volume

133

Start / End Page

204 / 215

Related Subject Headings

  • Geochemistry & Geophysics
  • 3705 Geology
  • 3703 Geochemistry
  • 0406 Physical Geography and Environmental Geoscience
  • 0403 Geology
  • 0402 Geochemistry
 

Citation

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Pham, A. L. T., Morris, A., Zhang, T., Ticknor, J., Levard, C., & Hsu-Kim, H. (2014). Precipitation of nanoscale mercuric sulfides in the presence of natural organic matter: Structural properties, aggregation, and biotransformation. Geochimica et Cosmochimica Acta, 133, 204–215. https://doi.org/10.1016/j.gca.2014.02.027
Pham, A. L. T., A. Morris, T. Zhang, J. Ticknor, C. Levard, and H. Hsu-Kim. “Precipitation of nanoscale mercuric sulfides in the presence of natural organic matter: Structural properties, aggregation, and biotransformation.” Geochimica et Cosmochimica Acta 133 (May 15, 2014): 204–15. https://doi.org/10.1016/j.gca.2014.02.027.
Pham ALT, Morris A, Zhang T, Ticknor J, Levard C, Hsu-Kim H. Precipitation of nanoscale mercuric sulfides in the presence of natural organic matter: Structural properties, aggregation, and biotransformation. Geochimica et Cosmochimica Acta. 2014 May 15;133:204–15.
Pham, A. L. T., et al. “Precipitation of nanoscale mercuric sulfides in the presence of natural organic matter: Structural properties, aggregation, and biotransformation.” Geochimica et Cosmochimica Acta, vol. 133, May 2014, pp. 204–15. Scopus, doi:10.1016/j.gca.2014.02.027.
Pham ALT, Morris A, Zhang T, Ticknor J, Levard C, Hsu-Kim H. Precipitation of nanoscale mercuric sulfides in the presence of natural organic matter: Structural properties, aggregation, and biotransformation. Geochimica et Cosmochimica Acta. 2014 May 15;133:204–215.
Journal cover image

Published In

Geochimica et Cosmochimica Acta

DOI

ISSN

0016-7037

Publication Date

May 15, 2014

Volume

133

Start / End Page

204 / 215

Related Subject Headings

  • Geochemistry & Geophysics
  • 3705 Geology
  • 3703 Geochemistry
  • 0406 Physical Geography and Environmental Geoscience
  • 0403 Geology
  • 0402 Geochemistry