This project is a collaborative effort among colleagues at four different institutions, each of whom has expertise in different aspects of field measurements of BVOC compounds. The work will be conducted at the PROPHET site at the University of Michigan Biological Station (UMBS) and entails measurements of the full suite of biogenic volatile organic compounds (BVOCs) and their oxidation products, especially organic nitrates, to investigate the role of BVOCs in ozone and aerosol production and nitrogen sequestration in forest-impacted environments. Recent work has indicated that significant chemistry is occurring inside the forest canopy that can affect these aspects of atmospheric chemistry, all of which ultimately influence the future of global and regional scale climate change. Central to this chemistry are the emission rates and resultant distributions and vertical profiles of the BVOC compounds emitted into the below- and above-canopy air. While much has been learned about the importance of BVOCs to atmospheric chemistry in general, there is a paucity of information on the concentrations of the speciated BVOCs and their oxidation products, in large part due to analytical measurement challenges. Recent theoretical studies indicate that our understanding of BVOC chemistry, especially in low-NOx environments, is quite weak. Thus, the ability to conduct BVOC measurements at trace levels, reliably and routinely, for a full suite of compounds is very important. We are currently funded to show proof-of-principle that we can make high-frequency measurements of a broad range of BVOC compounds within and above the forest canopy at the UMBS PROPHET lab. Upon satisfactory completion of proof, we will resubmit for funding to cover two full years of measurements with intensive coverage during the growing seasons. This will enable us to examine the seasonal variation and relative importance of specific BVOCs in this type of mixed-forest environment, to identify and quantify different classes of organic nitrate compounds and their contribution as a nitrogen source to the forest, and to inform us of the impact of forest disturbance/succession on BVOC fluxes and hence how forest photochemistry will change as a result of changing land cover.