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Harvard Forest REU Symposium Abstract 2015
- Title: Isoprene and other Biogenic Volatile Organic Compounds: Sources, Sinks, and Mechanisms for Plant Uptake and Emission at the Harvard Forest
- Author: Marissa A Saenger (Harvard University)
- Abstract:
All plants emit biogenic volatile organic compounds (BVOCs), hydrocarbons that interact with atmospheric compounds to form products such as ozone and aerosol particles. Isoprene comprises roughly half of BVOC emissions worldwide, and its reactions affect tropospheric ozone levels, which influences climate and air quality. BVOCs are emitted in varying levels by different plant species: grapes (vinis vinifera) are known to lack isoprene emissions, while red maple (acer rubrum) and red oak (quercus rubra) exhibit low and high isoprene emission levels, respectively. The goals of this project were to determine isoprene and other BVOC emission levels among these species along with photosynthesis and transpiration rates and to determine methods of emission and uptake. The experiments used a proton-transfer-reaction mass spectrometer (PTR-MS) to detect levels of isoprene and other BVOCs (including acetone, monoterpenes, acetaldehyde, and oxygenated terpenes), sampled from bag chambers enclosing plant leaves. Each species was tested individually for 24 hours, repeated several times using different leaves or specimens. CO2 and water concentrations, measured simultaneously using a Li-840A instrument, were used to calculate transpiration and photosynthesis rates of the enclosed leaves and test for correlations between these processes and BVOC emissions. Stomatal conductance was calculated from transpiration rates and used to assess the role of stomata on BVOC emissions. Findings were consistent with expectations regarding relative isoprene emission levels among the three species. The data collected indicated peaks in most BVOC emissions during daylight hours, along with transpiration and photosynthesis rates, indicating correlation between BVOC emissions and leaf transpiration and photosynthesis.
- Research Category: Forest-Atmosphere Exchange
