Effects of Elevated Carbon Dioxide and Temperature on BVOC Emissions: Implications for Hydroxyl Radical Reactivity and Ozone ChemistryEPA Grant Number: FP917204
Title: Effects of Elevated Carbon Dioxide and Temperature on BVOC Emissions: Implications for Hydroxyl Radical Reactivity and Ozone Chemistry
Investigators: Swarthout, Robert Frank
Institution: University of New Hampshire - Main Campus
EPA Project Officer: Michaud, Jayne
Project Period: September 1, 2010 through August 31, 2013
Project Amount: $111,000
RFA: STAR Graduate Fellowships (2010) RFA Text | Recipients Lists
Research Category: Academic Fellowships , Fellowship - Global Change
Climate change has been demonstrated to alter emissions of biogenic volatile organic compounds (BVOCs) from plants. BVOCs, in turn, have an impact on climate through three primary feedback mechanisms: 1) reaction with hydroxyl radical, the primary atmospheric oxidant responsible for the removal of many pollutants and greenhouse gases (GHGs); 2) affecting rates of tropospheric ozone production and destruction; and 3) contributing to the formation of aerosols. This study will quantify the effects of plant BVOC emissions on atmospheric hydroxyl radical availability and ozone production under current and future climate conditions using a combination of measurements and modeling.
Climate change has been shown to affect plant emissions of biogenic volatile organic compounds (BVOCs). BVOCs, in turn, influence climate by affecting hydroxyl radical availability and greenhouse gas (GHG) lifetimes, and by altering tropospheric ozone chemistry. Using measurements of BVOC emissions from plants exposed to predicted future climate conditions, this study will quantify and model the impact of future BVOC production on the oxidative capacity of the atmosphere and ozone chemistry.
This study will employ a combination of laboratory and field measurements as well as modeling to address two fundamental scientific questions: 1) how will individual BVOC emissions and the total hydroxyl radical reactivity of BVOC emissions change as a result of climate change; and 2) how will changes in BVOC emissions affect future ozone production? In the laboratory, plant species will be exposed to a matrix of climate conditions. Exposing plants to current and predicted future levels of carbon dioxide and temperature in the presence or absence of light and ozone will elucidate the effects of each variable separately and any synergistic effects on BVOC emissions. Emissions of BVOCs from these plants will be monitored by several gas chromatographic techniques, proton transfer reaction mass spectrometry, and an integrative method of measuring total hydroxyl radical reactivity that will account for difficult-to-measure BVOCs. These laboratory measurements, in combination with field measurements of individual BVOCs and total hydroxyl radical reactivity made at Thompson Farm, a forested site in New Hampshire, will be used to develop quantitative relationships between climate variables and BVOC emissions. These data will ultimately be used to model future ozone chemistry and lifetimes of important GHGs in order to predict the effect that future BVOC emissions will have on radiative forcing.
Using an integrative approach of measurements and modeling, this study will determine the sensitivity of individual BVOCs to changes in climate and will directly measure the hydroxyl radical reactivity of BVOC emissions from plants exposed to elevated carbon dioxide and temperature. These measurements will quantify two of the climate feedback cycles associated with BVOC emissions (the effect on hydroxyl radical availability and the effect on ozone chemistry), and will provide a more solid empirical foundation for future climate modeling studies. Greater quantitative knowledge of future BVOC emissions will also facilitate modeling studies of secondary organic aerosol formation and the associated effects on radiative forcing. Most importantly, data generated by this work will lead to more informed climate policy decisions.
Potential to Further Environmental/Human Health Protection:
Data generated by this study will lead to more accurate predictions of the oxidative capacity of the atmosphere and GHG lifetimes in a changing climate. These data will also aid in predicting the contribution that BVOCs will make to future ozone levels, which could have important human health implications.