Sources and Impacts of Water-Soluble Iron in Atmospheric Aerosol

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Despite the importance of water-soluble (WS) Fe-containing aerosol climate, air quality, and human health, the sources and chemistry governing its atmospheric concentrations are not well understood. In particular, a scarce number of ambient observations have characterized WS-Fe-containing aerosol over land on which most human populations reside. Thus, the potential human exposure of WS-Fe is poorly characterized. While atmospheric models have suggested that the chemistry of combustion aerosol may reconcile the global WS-Fe budget, a fundamental understanding of this chemistry is necessary for accurate assessments and predictions of the environmental impacts of WS-Fe. The goal of the proposed research program is to develop a comprehensive understanding of the sources and impacts of WS-Fe and other toxic metals in outdoor and indoor aerosol. This will be achieved through a combination of mechanistic laboratory experiments and ambient observations. Initial projects will: 1) characterize the WS-Fe concentrations in aerosol emitted from both outdoor and indoor combustion activities; 2) determine the production rates of WS-Fe from the chemical processing of outdoor combustion aerosol caused by various reactions (such as acid-catalyzed and complexation) that can promote iron dissolution; 3) establish an air quality monitoring site in Sackville, New Brunswick; and 4) identify the major sources and chemical production mechanisms governing the ambient concentrations of WS-Fe nation-wide. This research program will not only result in retroactive evaluation of previously implemented air quality regulations in Canada (such as phase out of coal-fired power plants), but also support the design of more efficient mitigation strategies and more accurate predictions of future impacts due to changes in emission. This is very important given that combustion activities, such as wildfires in Canadian forests, are expected to increase. Another critical impact of the work is the evaluation of potential exposure to toxic components in indoor aerosol emitted by heating- and cooking-related combustion activities. The results from this work are of direct relevance to Canadians living in rural communities where wood combustion remains a predominant residential energy source. The research program will also provide an interdisciplinary training ground for emerging young scientists. Students will develop not only a diverse analytical skill set, but also broaden their research experience through exposure to both laboratory experiments and field observations. They will also have the opportunity to collaborate with members from other departments, institutions, and government agencies.