DOAS measurement of glyoxal as an indicator for fast VOC chemistry in urban air

Abstract

[1] We present the first direct measurements of glyoxal (CHOCHO) in the atmosphere, and demonstrate that glyoxal measurements are possible by differential optical absorption spectroscopy (DOAS). Glyoxal was routinely detected during the daytime in Mexico City, where mixing ratios ranged from <0.15 ppbv (detection limit) to 1.82 ppbv. These time-resolved measurements resolve the rapid diurnal variation of glyoxal, and indicate the onset of volatile organic compound (VOC) oxidation about 1hr after sunrise. The atmospheric lifetime of glyoxal is determined to be 1.3 hr for overhead sun conditions. Then elevated glyoxal levels indicate a persistently active VOC chemistry during most of the day. Glyoxal forms from the oxidation of numerous VOCs, which foster the formation of 'photochemical smog' including ozone and aerosol particles; atmospheric levels are essentially unaffected by direct vehicle emissions in Mexico City. Satellite measurements of glyoxal seem feasible, making possible the better identification of photochemical hot spots in the Earth's atmosphere. Citation: Volkamer, R., L. T. Molina, M. J. Molina, T. Shirley, and W. H. Brune (2005), DOAS measurement of glyoxal as an indicator for fast VOC chemistry in urban air, Geophys. Res. Lett., 32, L08806,

Nitrogen dioxide measurement by cavity attenuated phase shift spectroscopy (CAPS) and implications in ozone production efficiency and nitrate formation in Beijing, China

“…Such interferences might be significant when the ratio of glyoxal to NO 2 is high. However, based on previous measurements of glyoxal and NO 2 at both urban and rural sites [Volkamer et al, 2005;Li et al, 2013], the interferences of glyoxal on the measurement of ambient NO 2 are generally less than 10%.…”

Comparison of aromatic hydrocarbon measurements made by PTR-MS, DOAS and GC-FID during the MCMA 2003 Field Experiment

“…During the daytime, the intense and continuous anthropogenic emissions of NO and VOCs, in combination with the high OH reactivity, generate ozone at rates exceeding 50 ppbv h −1 as early as one hour after sunrise (Shirley et al, 2006). The rapid formation of glyoxal observed after sunrise by Volkamer et al (2005) during the MCMA-2003 experiment indicates an efficient VOC oxidation process during morning hours, and the high glyoxal level observed until early afternoon reveals a persistently active VOC chemistry during most of the day. Hydrocarbon oxidation products, resulting from these VOC oxidation processes, contribute significantly to the formation of secondary organic aerosols much faster and an order of magnitude larger than expected previously Kleinman et al, 2007;Dzepina et al, 2009).…”

“…In brief, light from a broadband UV/vis lightsource (Xe-short arc lamp) is projected into the open atmosphere onto a distant array of retro reflectors, which folds the lightpath back into the instrument where spectra are recorded using a Czerny-Turner type spectrometer coupled to a 1024-element PDA detector. Only data from DOAS#1 will be presented here; DOAS#2 is described elsewhere (Volkamer et al, 2005). Both instruments were operated by the CU Boulder/MIT team.…”

Technical note: Evaluation of standard ultraviolet absorption ozone monitors in a polluted urban environment

“…The DOAS-2 lightpath was directed towards a local hill side of Cerro de la Estrella in a south-westerly direction with a 2.21 km path length (total 4.42 km). Both LP-DOAS instruments measured O 3 among other species (Volkamer et al, 1998(Volkamer et al, , 2005b) using ozone's unique specific narrow-band (<5 nm) absorption structures between 252-262 nm (DOAS-1) and 325-358 nm (DOAS-2). Temperature dependent absorption cross-sections (Bass and Paur, 1981) for 293 K and 313 K were convoluted to match the spectral resolution of the instruments, and fitted simultaneously with other trace-gas reference spectra and a fifth order polynomial high-pass filter to account for broadband molecule and aerosol extinction using non-linear least squares fitting routines (Fayt and van Roozendael, 2001;Stutz and Platt, 1996).…”