New Biogenic VOC Emissions ModelEPA Grant Number: R831453
Title: New Biogenic VOC Emissions Model
Investigators: Monson, Russell K. , Fall, Ray
Institution: University of Colorado at Boulder
EPA Project Officer: Chung, Serena
Project Period: January 1, 2004 through December 31, 2006 (Extended to December 31, 2007)
Project Amount: $644,044
RFA: Consequences of Global Change for Air Quality: Spatial Patterns in Air Pollution Emissions (2003) RFA Text | Recipients Lists
Research Category: Air Quality and Air Toxics , Global Climate Change , Climate Change , Air
We intend to develop new prognostic models for the prediction of biogenic volatile organic compound emissions from forest ecosystems in the face of possible future changes in the climate and the concentration of carbon dioxide in the atmosphere. These models will be based on actual biochemical mechanisms and will thus be more accurate than existing models which lack insight into the fundamental biochemical function of plants.
Many past studies have shown that the emission of volatile organic compounds from forest ecosystems cause an increase in air pollution, particularly that involving tropospheric ozone, nitrogen oxides and acid deposition, in near-urban and suburban areas. Current air pollution models used by the U.S.E.P.A. to predict these effects lack fundamental insight into the biochemical mechanisms in plants that produce these compounds. Consequently, it is not possible to accurately predict whether the emission of these compounds and their influence on air quality will change if the climate of the earth or the atmospheric concentration of carbon dioxide changes in the future. Both climate change and an increase in atmospheric carbon dioxide are predicted to occur in the next century. We intend to conduct experiments to elucidate the biochemical processes that cause the emission of these compounds and describe their response to temperature and carbon dioxide change. We will focus our studies on the emission of isoprene and acetaldehyde, two of the most commonly-emitted compounds from US forests. Our studies will bring modern techniques in biochemistry and molecular biology to the study of forests and their effects on regional air quality.
We will grow forest trees in artificial growth chambers with programmed regimes of temperature and carbon dioxide in order to test our hypotheses that changes in the activity of a few key enzymes (phosphoenolpyruvate carboxylase, isoprene synthase and pyruvate kinase) and the density of mitochondria in leaf cells, cause the greatest changes in isoprene emission and acetaldehyde emission from forest trees. We will conduct biochemical assays of these enzymes and make electron microscope observations of mitochondrial density in order to measure these effects. We will work with research groups at the University of Wisconsin, Texas A&M University, the Oak Ridge Laboratory in Tennessee, and the Smithsonian Institute in Washington to make measurements on trees already growing in experimental treatments of elevated carbon dioxide concentration and elevated temperature. These latter experiments are part of the Department of Energy's experiments on plants in Free Air Carbon Exchange (FACE) rings.
The proposed studies will lead to improved models capable of predicting how natural forests will affect air quality in near-urban areas in the next century. This, in turn, will allow for more efficient allocation of funds intended to mitigate air pollution in urban areas. It has been shown in past studies, for example, that the emission of volatile organic compounds from natural forests in the Atlanta area, render testing and mitigation of hydrocarbon emissions from automobiles as an ineffective strategy to mitigate regional ozone pollution. We hypothesize that in the presence of elevated atmospheric carbon dioxide concentration, the effect of these forests will be reduced, but in the presence of elevated temperature, the effect will be increased. The exact manner in which these conflicting effects unfold can only be predicted with accurate models that are based on true biochemical mechanisms in the forest trees. Our models will permit these predictions. Using the predictions, strategies for controlling ozone pollution, can be honed and made more efficient. Tropospheric ozone is one of the primary threats to public health in urban and near-urban areas, being responsible for respiratory damage in humans and other animals and for loss of productivity in crops and forests.