CAREER: Molecular Mechanism of Atmospheric Mercury through Speciation-Resolved Experiments

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This CAREER project is focused on developing a better understanding of atmospheric mercury. Mercury is a highly toxic pollutant released by fossil fuel combustion and waste incineration, primarily in the form of gaseous elemental mercury (GEM). GEM is involved in long-range transport that can result in the transfer of mercury to the oceans. This project will investigate the kinetics of mercury reactions in the atmosphere. The improved knowledge of mercury chemistry obtained by this project will be critical for assessing the environmental impacts of mercury.The science objectives of the proposed research are to: (1) Elucidate the kinetics and mechanism of gas-phase reactions of mercury bromide (HgBr) to evaluate the lifetime of GEM and the molecular speciation of gaseous oxidized mercury (GOM); (2) Investigate the heterogeneous uptake of GOM on surfaces to improve understanding of the processes that form particle-bound mercury; and (3) Investigate ion-molecule reactions of GOM to identify reagent ions that can be utilized for direct detection of GOM in the atmosphere by chemical ionization mass spectrometry (CIMS). Questions that motivate this research include: (a) what atmospheric chemicals are responsible for the conversion of HgBr to stable gas-phase products? (b) What is the chemical nature of those products? (c) What are the rate coefficients of associated reaction pathways? (d) Which of the gas-phase products can bind effectively with atmospheric particulate matter? (e) Can these gas-phase and particle-bound products be detected and quantified directly?