HR: 11:50h
AN: A52B-06    [Abstracts]
TI: Biogenic sources of formaldehyde and acetaldehyde during summer conditions.
AU: * Hutzell, W T
EM: hutzell.bill@epa.gov
AF: Atmospheric Modeling Division, US EPA MD E-243-03, RTP, NC 27711 United States
AB: Photochemical modeling estimated contributions to ambient concentrations of formaldehyde and acetaldehyde from biogenic emissions over the continental United States during January 2001 (Eos Trans. AGU, 83(47), Fall Meet. Suppl., Abstract A52B-0117). Results showed that maximum contributions occurred over states along the Pacific and southeastern Atlantic coasts. Biogenic contributions were between 10-50 percent and 20-90 percent over urban and rural areas, respectively. For formaldehyde, biogenic contributions were equally divided between direct emissions and photochemical production. Photochemistry accounted from 50 to 80 percent of acetaldehyde concentrations. Both compounds had highest production yields from Nonmethane Volatile Organic Compounds (NVOCs) that contain double bonds between carbon atoms. Ethene emissions were specifically identified to significantly contribute to formaldehyde concentrations. Acetaldehyde production also had large yields from NVOCs containing single bonds between carbon atoms. Isoprene emissions played a minor role compared to other biogenic NVOCs because winter temperatures and solar irradiances reduced its biogenic sources. We have conducted further modeling to assess biogenic contributions during July 2001. Results show that biogenic contributions dominated at most locations in the continental US. In the southern states, maximum contributions moved westward to Louisiana and Arkansas but the states along the Pacific coast remained as locations of maximum contributions. Photochemical production controled most concentrations but up to one third of acetaldehyde can be traced to direct emissions. Isoprene emissions generally produced over 50 percent of formaldehyde concentrations. Acetaldehyde retained the same patterns in production yields from biogenic NVOCs as January 2001. Terrain and its vegetation type affected how these contributions distributed among specific compounds in biogenic emissions. Disclaimer - This paper has been reviewed in accordance with the United States Environmental Protection Agency's peer and administrative review polices and approved for presentation and publication. Although it has been reviewed by EPA, the paper does not necessarily reflect EPA policies or views.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0317 Chemical kinetic and photochemical properties
DE: 0322 Constituent sources and sinks
DE: 0365 Troposphere--composition and chemistry
DE: 0394 Instruments and techniques
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting