Dissertation Research: "Environmental Controls over Methyl Halide Emissions from Agricultural Rice Paddy Ecosystems"

University Of California-Irvine, Irvine CA

Investigators

Abstract

Methyl halides are important trace gases in atmospheric chemistry. Methyl bromide and methyl chloride supply a significant amount of inorganic chlorine and bromine to the stratosphere where they catalyze ozone loss. Methyl chloride, methyl bromide and methyl iodide are also active in lower atmosphere chemistry and may impact the cleansing rate of the troposphere. Consequently, methyl bromide, a widely used agricultural fumigant, is being regulated in the U.S. and abroad. As anthropogenic sources of these gases decline with time due to regulation natural halogen sources will dominate. Agricultural emissions of these gases must be quantified and understood. Recent field research has shown that globally significant amounts of methyl bromide and methyl iodide are produced by worldwide rice agriculture. We propose to determine the effects of certain abiotic factors (including soil halide amounts and light levels) on methyl halide production in rice and to examine the underlying physiology and biochemistry of the plant response. These studies will incorporate in-situ (seasonal greenhouse measurements) and in-vivo (leaf-disk enzyme assays) studies