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www.atmos-chem-phys-discuss.net/10/10077/2010/
doi:10.5194/acpd-10-10077-2010
© Author(s) 2010. This work is distributed
under the Creative Commons Attribution 3.0 License.
Chemical transformations of Hg° during Arctic mercury depletion events sampled from the NASA DC-8
1Climate Change Research Center, Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Morse Hall, Durham, NH 03824, USA
2Department of Chemistry, University of California – Irvine, Irvine, California 92697-2025, USA
3School of Earth & Atmospheric Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
4National Center for Atmospheric Research, Earth and Sun Systems Laboratory, P.O. Box 3000, Boulder, Colorado 80307-3000, USA
Abstract. Atmospheric Mercury Depletion Events (MDEs) in Arctic springtime were investigated utilizing a box model based on airborne measurements from the NASA DC-8 during the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) field campaign. Measurements showed that MDEs occurred near the surface and always over the Arctic Ocean accompanied by concurrent ozone (O3) depletion, enhancement in Br2 mixing ratios, and decreases in ethyne and light weight alkanes. Backward trajectories indicated that most air masses inside the MDEs originated at low altitude over the ocean presumably generating a halogen-rich environment. We developed a box model which considered only gas phase reactions of mercury, halogen species, and O3 chemistry. We conducted a series of sensitivity simulations to determine the factors that are of most importance to MDE formation. The box model results suggested that continuous enhancement of Br2 mixing ratios, a high intensity of solar radiation, or a relatively high NOx regime expedited Hg° depletion. These environments generated high concentrations of Br radical, and thus the model results indicated that the Br radical was very important for Hg° depletion. Utilizing different rate constants for reaction of Hg° + Br produced times to reach Hg° depletion ranging from 22 to 32 h.
Discussion Paper (PDF, 1499 KB) Supplement (106 KB) Interactive Discussion (Closed, 4 Comments) Publication in ACP not foreseen
Citation: Kim, S. Y., Talbot, R., Mao, H., Blake, D. R., Huey, G., and Weinheimer, A. J.: Chemical transformations of Hg° during Arctic mercury depletion events sampled from the NASA DC-8, Atmos. Chem. Phys. Discuss., 10, 10077-10112, doi:10.5194/acpd-10-10077-2010, 2010. Bibtex EndNote Reference Manager XML
