A Multiphase Study of the Nature, Sources, and Fate of Atmospheric Organic Nitrogen

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This project addresses the sources, fate, and importance of atmospheric organic nitrates, and the role of biogenic volatile organic compounds (BVOCs) in sequestering atmospheric nitrogen in forest environments. This research is important in the broader context of understanding forest uptake of carbon dioxide, including future changes as climate and anthropogenic inputs of atmospheric nitrogen change. The project includes field studies aimed at identification of the important pathways for organic nitrate formation in both the gas phase, and in cloud water. The field studies will be conducted at the University of Michigan Biological Station (UMBS) Program for Research on Oxidants: Photochemistry, Emissions, and Transport (PROPHET) laboratory. The cloud water studies will make use of the Airborne Laboratory for Atmospheric Research (ALAR), a small, instrumented aircraft operated by Purdue University.The main objectives of the project are: (1) Measurements of the vertical profile of atmospheric organic nitrates, using a tethered balloon with sampling equipment to examine the role of isoprene and other BVOCs in sequestering atmospheric nitrogen; (2) Investigation of the role of very reactive biogenic volatile organic compounds in the atmosphere above the UMBS forest, using a newly developed Proton Transfer Reaction Linear Ion Trap (PTRLIT); also laboratory studies of the kinetics and mechanisms for the formation of atmospheric organic nitrates from BVOCs; (3) A study of the ability of microorganisms to process cloud water nitrogen (using a cloud water collector), including an investigation of the potential production of light alkyl nitrates in cloud water; (4) Laboratory photochemical reactor studies of aqueous phase production of alkyl nitrates to improve our ability to predict the fate of atmospheric nitrogen.The project will provide opportunities for undergraduate and graduate student development and training, and also involve significant outreach and education activities through the Purdue Climate Change Research Center (PCCRC). Specifically, an exhibit will be created about the relationships between human activities, agricultural practices, atmospheric nitrogen, and climate change. The exhibit will involve hands-on interactive computer simulations of the relationships between land use change and climate, and will be produced with the intention of making it available to science and technology museums around the country.