94180730 Fall Research conducted with earlier grants has resulted in the discovery of major fluxes of methanol and other volatile organic compounds (VOCs) from vegetation to the atmosphere. It is now proposed to use sensitive and specific enzyme/fluorescence methods to measure the emission of methanol and other oxygenated hydrocarbons containing one carbon from major forest tree species and crops, and establish the role of leaf bacteria as sinks for these compounds. The data obtained will be used to develop emission algorithms that will be validated in field experiments and in the future might be used as the basis of a US emissions inventory of biogenic C1-oxHCs. Plant C1-oxHC fluxes to the atmosphere may be very large, both regionally and globally, with long range transport of methanol and a variety of impacts on atmospheric chemistry. Currently there are large uncertainties in these flux estimates. This project will contribute to a more complete picture of the biogeochemical cycling of methanol, formaldehyde, and formic acid between the biosphere and atmosphere, and help establish knowledge of natural sources and sinks of these C1 compounds. The specific goals of the proposed work are: (1) to perfect enzymatic and fluorescence methods for analyzing methanol, formaldehyde, and formic acid emissions from vegetation; (2) to define the "drivers" of plant C1-oxHC emissions and collect a large data set of oxHC fluxes in laboratory and greenhouse experiments; (3) develop emission algorithms for biogenic C1-oxHCs; (4) to establish the role of leaf bacteria as sources and/or sinks of atmospheric C1-oxHCs; (5) and to validate laboratory emissions algorithms by appropriate field measurements of C1-oxHC fluxes.
