The presence of mercury in the environment is of global concern due to its toxicity. The atmosphere is an important transient reservoir for mercury released by human activities and natural sources. The knowledge of atmospheric mercury chemistry is critical for understanding the global biogeochemical cycle. In the atmosphere, mercury primarily exists in three forms: gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM), and particulate-bound mercury (PBM). Over the last decade, the existing knowledge of mercury cycle has dramatically changed: (1) There has been increasing evidence that current detection methods do not accurately quantify gaseous oxidized mercury and a technique which could do both quantitative measurements and molecular speciation of atmospheric oxidized mercury is needed. (2) The gas-phase oxidation of elemental mercury initiated by bromine radical has been proposed as the major oxidation pathway, however, the experimental confirmation for the fate of HgBr radical is limited. (3) Heterogeneous reactions of gaseous oxidized mercury on environmental surfaces are poorly understood.
Accordingly, the goal of this work is (a) to develop a new mass spectrometry-based detection technique, which can be employed for both laboratory and field measurements of gaseous oxidized mercury and use this technique to investigate the (b) heterogeneous reactions of gaseous oxidized mercury with environmental surfaces; and (c) the kinetics and mechanism of gas-phase reactions of elemental mercury to form gaseous oxidized mercury. This work has broad implications, it provides a better understanding of mercury chemistry in mechanisms and kinetics, which helps to model the atmospheric mercury cycle, enhance our current knowledge concerning the biogeochemical cycling of mercury, broaden our understanding of the mercury chemistry in the atmosphere, and provide a direct detection technique of atmospheric mercury which can be applied in future field and laboratory studies
