Elucidating the Role of Photons and Atmospheric Aerosols in the Reduction of Oxidized Mercury Species

Toxic mercury species are released to the atmosphere through both natural and anthropogenic emission sources, where coal-fired power plant emissions plumes constitute a primary source of anthropogenic mercury emissions.¹ The release of mercury to the atmosphere presents large concerns for both the environment and human health (e.g., bioaccumulation of mercury in aquatic organisms). The ultimate fate of mercury in the atmosphere is deposition to the Earth’s surface, but the deposition rate of mercury is largely dependent on redox chemistry involving reactive mercury species (Hg(II)), due to high relative deposition rates of Hg(II) species as compared to elemental mercury (Hg⁰).² Recent experimental and field studies have noted the reduction of Hg(II) to Hg⁰, and that this chemistry involves interactions with photons and atmospheric aerosols; however, the mechanism for this reduction chemistry has remained elusive.^1,3

In our work, we have employed first-principles density functional theory (DFT) calculations to probe the reduction of Hg(II) species on atmospheric aerosol surfaces.⁴ Through this work, we will elucidate both the reduction mechanism for Hg(II) species over a range of aerosol surfaces and the combined role of atmospheric aerosols and photons in the reduction of Hg(II) species. We will also show the usefulness of DFT as a novel approach to study atmospheric aerosol chemistry.

References

1. Y. Tong el al. Environ. Sci.: Processes Impacts, 2013, 15, 1883–1888.

2. A.P. Rutter and J.J. Schauer. Environ. Sci. Technol., 2007, 41, 3934–3939.

3. B. de Foy et al. Atmos. Environ., 2016, 134, 27–39.

4. S.A. Tacey, L. Xu, M. Mavrikakis, and J.J. Schauer. J. Phys. Chem. A, 2016, 120, 2106–2113.