The Atmospheric N Cycle: Biospheric Emissions and Chemical Transformations

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This research is focused on the atmosphere-biosphere exchange of nitrogen compounds in the environment. The emphasis is on nitrogen compounds in forests and areas with abundant plant material. Forests can emit volatile organic gases, known as biogenic emissions, that can react and condense to form very small particles, known as secondary organic aerosol. This project includes laboratory studies to identify the chemical reactions of the biogenic emissions that can occur in the presence of nitrogen compounds. The results will improve models that predict air quality and climate change.Laboratory flux measurements will focus on investigating the fate of nitrogen species as they are emitted from the plant/forest canopy to the free atmosphere and the chemical, physical, and/or biological mechanisms for the formation of oxidized compounds. Data from the SAS campaign, held in Alabama in the summer of 2013, will be analyzed with the use of chemical transport models and compared with data from other field campaigns. The resulting information will provide a comparison of the sources and sinks of nitrogen species, the observations of oxidation products and secondary organic aerosol, and the influence of anthropogenic emissions on the concentration and distribution of oxidized species. Finally, laboratory experiments will be conducted in the Caltech chamber to improve understanding of the production of organic nitrate from the oxidation of isoprene and other compounds produced from biogenic emissions.