Biogenic Ozone-Precursors: From Mechanism to AlgorithmEPA Grant Number: R825259
Title: Biogenic Ozone-Precursors: From Mechanism to Algorithm
Investigators: Fall, Ray
Institution: University of Colorado at Boulder
EPA Project Officer: Hahn, Intaek
Project Period: November 15, 1996 through November 14, 1999
Project Amount: $379,889
RFA: Air Quality (1996) RFA Text | Recipients Lists
Research Category: Air Quality and Air Toxics , Air
Description:Increasing tropospheric ozone is one of the most important environmental issues of our time, and it is now clear that forested regions of the United States emit volatile hydrocarbons, especially isoprene, that catalyze ozone formation. In order to model regional air quality and make decisions about ozone abatement, it is desirable to estimate natural isoprene emissions from U. S. forests. The primary goals of this proposed work are: a) to understand those biological factors that regulate isoprene emission from forest canopies to the troposphere, and b) use this information to develop a mechanistic isoprene emission algorithm. We argue that the regulation of isoprene emission to the atmosphere centers around the activity of the enzyme isoprene synthase in chloroplasts, and that molecular investigations of its regulation will lead to major progress on these two goals.
Specific objectives of the proposed work are the following: 1) to determine the regulation of isoprene synthase gene expression; 2) to determine the mechanism of regulation of leaf isoprene emission by light; 3) to devise and assess a new function-based, mechanistic isoprene emission algorithm, and test its ability to predict 232-MB emission from pine needles; 4) to test the feasibility of an immunochemical method for field assessment of isoprene emission potential; and, 5) to determine why isoprene emission rate is so variable in different plant species. As part of objective 3, we will also determine the effectivenesss of the isoprene emission algorithm to predict light-dependent emission of another volatile C5 isoprenoid, 2-methyl-3-buten-2-ol (232-MB), from ponderosa pine needles.
The information produced in this work will provide a basis for more accurately modeling biogenic isoprene emission, thus reducing uncertainties in the atmospheric isoprene budget, an increasingly critical component of regional air quality models. This work may also provide a mechanistic basis for prediction of emissions of ozone-forming 232-MB from U.S. pine forests.