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A CHAMBER AND MODELING STUDY TO ASSESS THE PHOTOCHEMISTRY OF FORMALDEHYDE
Citation:
Jeffries, H., K. Sexton, J. Arnold, AND Y. Bai. A CHAMBER AND MODELING STUDY TO ASSESS THE PHOTOCHEMISTRY OF FORMALDEHYDE. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/3-90/052.
Description:
A new analytical method for formaldehyde (HCHO) was implemented for use in the UNC outdoor smog chamber. CHO measurements obtained with this method were compared with those obtained using other analytical techniques. ix different calibration standards for HCHO were found to agree within +/- 2%, and the different HCHO analytical methods had precisions of +/- 10%. New experiments in which HCHO was produced chemically were performed. n explicit chemical reaction mechanism for ethene and propene was formulated to explain the chamber observations. The ethene mechanism showed excellent agreement with the observed data; the propene mechanism, however, did not perform as satisfactory. A comparison of these explicit mechanisms with the Carbon Bond IV (CB4) mechanism showed excellent agreement for ozone (<10% error), nitrogen oxides, and hydrocarbon oxidation rates; the CB4, however, consistently under predicted the HCHO maximum by about 13%. n analysis of a simulation of an urban scenario showed that chemical production of HCHO was the dominant factor governing afternoon HCHO concentrations. thene and other olefins were the source of 58-62% of the HCHO produced and aromatics were responsible for 10-12%. t was concluded that the CB4 mechanism can be used to predict ambient HCHO levels with an error of about 20%.