Measurements of formaldehyde at the US-Mexico border during the Cal-Mex 2010 air quality study
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Ambient formaldehyde (HCHO), along with other volatile organic compounds (VOCs), was measured using proton-transfer reaction mass spectrometry (PTR-MS) at a ground site along the U.S.-Mexico border during the Cal-Mex 2010 air quality study. During the observation period, the HCHO mixing ratio varied between 1.0 ppbv and 13.7 ppbv. On average, a daily maximum of 6.3 2.6 ppbv occurred around 10 AM and a minimum of 2.8 1.3 ppbv was observed around midnight. The early onset of the HCHO daily maximum (~ 3 h before the solar noon) indicated the presence of primary HCHO sources and a fast photolysis loss of HCHO, consistent with a measured low ratio of HCHO to acetaldehyde of (2.5 0.8). Using the simulated photolysis rates, we estimated the contribution of OH radical production from HCHO photolysis relative to that from O 3 photolysis, with a ratio from 0.8 to 18 and the highest values around traffic rush hours. Hence, our results indicate that HCHO plays a dominant role in regulating the OH radical budget in the area. 2012 Elsevier Ltd.
author list (cited authors)
Zheng, J., Zhang, R., Garzon, J. P., Huertas, M. E., Levy, M., Ma, Y., ... Molina, L. T.
complete list of authors
Zheng, Jun||Zhang, Renyi||Garzón, Jessica P||Huertas, María E||Levy, Misti||Ma, Yan||Torres-Jardón, Ricardo||Ruiz-Suárez, Luis G||Russell, Lynn||Takahama, Satoshi||Tan, Haobo||Li, Guohui||Molina, LT