Development and application of new analytical approaches to understand the chemistry of the atmospheric condensed phase

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Progress in areas of environmental chemistry requiring urgent attention is limited by available analytical methods. My research group develops new techniques and uses them to examine sources, impacts, and fate of pollutants. Over the next five years, we will use this approach to target two critical areas of uncertainty: persistent pollutant transport and climate change. Both issues are at crucial junctures for international regulation.******Persistent pollutants can undergo long-range transport and impact areas far from their release. Short-chain perfluorocarboxylic acids (scPFCAs) are persistent and potentially toxic. We recently showed scPFCA accumulation in the Arctic was caused by the regulated replacement of ozone-depleting chlorofluorocarbons with alternatives. A 2016 policy amendment will dramatically change the sources of scPFCAs, impacting transport and fate. We will develop two techniques that will represent the first real-time methods for gas- and aerosol-phase scPFCAs. These will enable us to probe gas-surface interactions and physical properties in flowtube studies and make the first real-time measurements of gas- and aerosol-phase scPFCAs. Using a new offline method for scPFCAs, we will also collect and analyze atmospheric deposition samples. Proposed laboratory and field measurements are critical to inform chemical fate models and assess the environmental impacts of changing regulation. This work will involve 11 HQP (3 PhD, 3 MSc, 5 undergraduate).******Organic aerosols released from burning vegetation have climate-warming properties that are not well understood, impeding their accurate inclusion in climate models. Much of this uncertainty is derived from poorly-characterized water-soluble organic compounds, known as brown carbon (BrC). Our new method for offline analysis showed that BrC was composed of molecules much larger than previously believed and that it could not be detected using mass spectrometry (MS) with electrospray ionization. Building on this, we will explore MS ionization techniques to identify a more suitable method for BrC characterization. The new technique will be used to study impacts of atmospheric processing on BrC by characterizing samples chemically aged in a flowtube and samples collected from controlled burn studies. We will interface our method to a sampling system to create the first BrC online system coupled to chemical separation, which will be applied in fire-impacted areas. The improved understanding of chemical structure and fate of BrC provided by our measurements will be critical for improving climate models that underpin international regulation. This work will involve 4 HQP (2 PhD, 2 undergraduate).******Through development and application of innovative new analytical methods to laboratory and field measurements, my group will provide fundamental chemical understanding that is essential to effective environmental regulation.