The interaction of mercury and methylmercury with chalcogenide nanoparticles

Xudong Wang; Emily A Seelen; Nashaat M Mazrui; Peter Kerns; Steven L Suib; Jing Zhao; Robert P Mason

doi:10.1016/j.envpol.2019.113346

The interaction of mercury and methylmercury with chalcogenide nanoparticles

Environ Pollut. 2019 Dec;255(Pt 3):113346. doi: 10.1016/j.envpol.2019.113346. Epub 2019 Oct 4.

Authors

Xudong Wang¹, Emily A Seelen², Nashaat M Mazrui³, Peter Kerns¹, Steven L Suib⁴, Jing Zhao⁴, Robert P Mason⁵

Affiliations

¹ Department of Chemistry, University of Connecticut, 55 North Eagleville Rd., Storrs, USA.
² Department of Marine Sciences, University of Connecticut, Groton, CT, USA.
³ Department of Chemistry, University of Connecticut, 55 North Eagleville Rd., Storrs, USA; Department of Marine Sciences, University of Connecticut, Groton, CT, USA.
⁴ Department of Chemistry, University of Connecticut, 55 North Eagleville Rd., Storrs, USA; Institute of Materials Science, University of Connecticut, 97 North Eagleville Rd., Storrs, USA.
⁵ Department of Marine Sciences, University of Connecticut, Groton, CT, USA. Electronic address: robert.mason@uconn.edu.

PMID: 31627051
DOI: 10.1016/j.envpol.2019.113346

Abstract

Mercury (Hg) and methylmercury (CH₃Hg) bind strongly to micro and nano (NP) particles and this partitioning impacts their fate and bioaccumulation into food webs, and, as a result, potential human exposure. This partitioning has been shown to influence the bioavailability of inorganic Hg to methylating bacteria, with NP-bound Hg being more bioavailable than particulate HgS, or organic particulate-bound Hg. In this study we set out to investigate whether the potential interactions between dissolved ionic Hg (Hg^II) and CH₃Hg and NPs was due to incorporation of Hg into the core of the cadmium selenide and sulfide (CdSe; CdS) nanoparticles (metal exchange or surface precipitation), or due purely to surface interactions. The interaction was assessed based on the quenching of the fluorescence intensity and lifetime observed during Hg^II or CH₃Hg titration experiments of these NP solutions. Additional analysis using inductively coupled plasma mass spectrometry of CdSe NPs and the separated solution, obtained after Hg^II additions, showed that there was no metal exchange, and X-ray photoelectron spectroscopy confirmed this and further indicated that the Hg was bound to cysteine, the NP capping agent. Our study suggests that Hg and CH₃Hg adsorbed to the surfaces of NPs would have different bioavailability for release into water or to (de)methylating organisms or for bioaccumulation, and provides insights into the behavior of Hg in the environment in the presence of natural or manufactured NPs.

Keywords: Cadmium selenide; Cadmium sulfide; Mercury; Methylmercury; Nanoparticles.

MeSH terms

Biological Availability
Cadmium Compounds
Humans
Mercury / analysis
Mercury / chemistry*
Methylmercury Compounds / analysis
Methylmercury Compounds / chemistry*
Models, Chemical*
Nanoparticles / chemistry*
Sulfides
Water Pollutants, Chemical / analysis

Substances

Cadmium Compounds
Methylmercury Compounds
Sulfides
Water Pollutants, Chemical
cadmium sulfide
Mercury