Observations of isoprene chemistry and its role in ozone production at a semirural site during the 1995 Southern Oxidants Study

Abstract

Abstract. Isoprene and its oxidation products, methyl vinyl ketone (MVK) and mcthacrolein (MACR), were measured in a semirural environment that was occasionally heavily impacted by urban emissions. At this site, isoprenc was the most important hydrocarbon in terms of koH' [hydrocarbon], but the aldehydes HCHO and CH3CHO also appear to be very important. The local isoprene photochemistry appears to be occasionally enhanced in NOx-rich urban plumes that are advected to the site over intermediate forested land. When 03 was being rapidly produced in urban plumes advected to this forested site, isoprene was found to contribute = 28% of the total ozone production. We observe that many of the peaks in isoprene oxidation products at this surface site arise from downward mixing of more photochemically processed air aloft, as the nocturnal inversion breaks up in the morning. We estimate that, in the daytime, t3pically 1-2% of the NOy at this NOx-rich site is composed of isoprene nitrates.

Characteristics of Surface Ozone Concentrations at Stations with Different Backgrounds in the Malaysian Peninsula

“…The movement of O 3 precursors to suburban areas leads to a high concentration of O 3 in these areas. Several previous studies e.g., by Trainer et al (1987), Chameides et al (1992), Roberts et al (1998), Starn et al (1998) and Wiedinmyer et al (2001) have indicated that the amount of biogenic VOC, such as isoprene, can contribute to the quantity of surface O 3 . Nevertheless a study by Von Schneidemesser et al (2011) indicated that the contribution of biogenic VOCs were quite low compared to the contribution of ozone from anthropogenic precursors such as NO x and VOCs which originated from motor vehicles and industrial processes.…”

Contribution of isoprene to formaldehyde and ozone formation based on its oxidation products measurement in Beijing, China

“…Its global emission was estimated to be 500-750 Tg yr À1 (Guenther et al, 2006), which is several times higher than the anthropogenic VOCs emissions (100-200 Tg yr À1 ) (Olivier and Berdowski, 2001), and typically more reactive than anthropogenic VOCs (Abelson, 1988). Researches conducted over the past decades have shown that isoprene contributes significantly to tropospheric ozone formation in rural (Trainer et al, 1987), suburban (Starn et al, 1998), and even urban areas (Chameides et al, 1988;Biesenthal and Shepson, 1997;Lee and Wang, 2006). Recently, ozone formation potentials (OFPs) based on the observed atmospheric VOCs in a typical region were widely utilized to evaluate the reaction activity of the individual species to local atmospheric ozone formation (Wiedinmyer et al, 2001;Duane et al, 2002;Duan et al, 2008).…”

A product study of the isoprene+NO<sub>3</sub> reaction

“…Isoprene emission occurs mostly during the daytime, increasing with temperature and radiation over the course of the morning and falling off in the afternoon (Fehsenfeld et al, 1992). Several studies have found reaction with NO 3 to be the dominant loss process for isoprene that remains during the early evening in moderately 4946 A. E. Perring et al: A product study of the isoprene+NO 3 reaction polluted environments (∼15% of the total) (Stroud et al, 2002;Warneke et al, 2004), and that this can result in substantial conversion of NO x to organic nitrates at night (Starn et al, 1998). Not only is NO 3 an important isoprene sink but, because of the high yield, INs formed by NO 3 -initiated oxidation may represent a large fraction of the total IN source (Horowitz et al, 2007).…”