The Impact of Environmental Perturbations on Biogenic Monoterpene Emissions and Their Implications to Secondary Organic Aerosol

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Forests are known to emit substantial amounts of reactive volatile organic compounds (VOC) that produce small particles called secondary organic aerosols (SOAs). These SOAs scatter sunlight and also seed clouds making them important for the earth's radiation and energy budget. However, these processes are highly uncertain and not captured in current climate models. Furthermore, climate change from increasing carbon dioxide is expected to alter temperatures and change precipitation patterns that will impact VOC and SOA production from forests. The responses to these changes can be distinct, non-additive and non-linear and there is conflicting evidence on whether these biogenic climate feedbacks will exacerbate or moderate anthropogenic climate forcing. The proposal addresses this important uncertainty with targeted laboratory studies of plants using state of the art measurements.This project implements control studies of plant chambers for measurement of VOC emissions and SOA formation from fast growing nicotine plants under abiotically stressed conditions. It will develop protocols to measure plant BVOC emissions under abiotic stress and also investigate the combined impact of elevated CO2 and temperature on plant emissions. The study will develop a set of 20 plant chambers for use with fast growing Nicotiana plants. It will then investigate the variance in VOC emission and SOA yield results for 20 identical (i.e. genetic clones) plants under identical conditions (ambient CO2 + elevated temperature) for at least one month. Finally it will perform a two-factor, short-term perturbation experiment, with CO2 and temperature perturbations ( +400 ppmv and +5 deg C) will be applied both separately and combined to test the hypothesis that combined abiotic stresses change VOC emissions in non-linear manners.