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Regional Sources of Atmospheric Formaldehyde and Acetaldehyde, and Implications for Atmospheric Modeling
Citation:
LUECKEN, D. J., W. T. HUTZELL, M. STRUM, AND G. POULIOT. Regional Sources of Atmospheric Formaldehyde and Acetaldehyde, and Implications for Atmospheric Modeling. ATMOSPHERIC ENVIRONMENT. Elsevier Science Ltd, New York, NY, 47(February):477-490, (2012).
Impact/Purpose:
The National Exposure Research Laboratory′s (NERL′s) Atmospheric Modeling and Analysis Division (AMAD) conducts research in support of EPA′s mission to protect human health and the environment. AMAD′s research program is engaged in developing and evaluating predictive atmospheric models on all spatial and temporal scales for forecasting the Nation′s air quality and for assessing changes in air quality and air pollutant exposures, as affected by changes in ecosystem management and regulatory decisions. AMAD is responsible for providing a sound scientific and technical basis for regulatory policies based on air quality models to improve ambient air quality. The models developed by AMAD are being used by EPA, NOAA, and the air pollution community in understanding and forecasting not only the magnitude of the air pollution problem, but also in developing emission control policies and regulations for air quality improvements.
Description:
Formaldehyde and acetaldehyde concentrations over the Eastern half of the United States are simulated with a 3-D air quality model to identify the most important chemical precursors under January and July conditions. We find that both aldehydes primarily result from photochemical production, although 25% or more result from direct emissions in urban areas during winter. Isoprene is the major precursor of formaldehyde in most areas during summer, contributing 20 - 60% of total production, with the magnitude being spatially variable. Other alkenes from anthropogenic and/or biogenic emissions dominate formaldehyde production in winter, contributing 60 - 85% of total formation, and are prominent contributors in summer. Alkenes, including biogenic alkenes, dominate acetaldehyde production during both seasons. These conclusions are based on the degradation of emitted VOCs described by the SAPRC07TB chemical mechanism, but even this detailed model has difficulty reproducing observed values better than a factor of 2. The substantial role of isoprene and other alkenes in aldehyde formation emphasizes that we examine and improve emission estimates of these compounds. Until we can estimate the emissions and understand the chemistry of VOC precursors to aldehyde formation with greater certainty, it will be difficult to accurately predict atmospheric concentrations of aldehydes and develop strategies to reduce their concentrations.
URLs/Downloads:
Regional Sources of Atmospheric Formaldehyde and Acetaldehyde, and Implications for Atmospheric Modeling (PDF, NA pp, 11446 KB, about PDF)Atmospheric Environment
