Oxygenated volatile organic compounds OVOCs

Many of the volatiles from plants are oxygenated volatile organic compounds (OVOCs). Measurement of OVOCs is difficult (e.g., methanol easily partitions with water) and, in many cases, time-consuming (up to 1 h per sample). This is too slow to measure fast emissions/ changes (e.g., when a plant is wounded), and in this case, PTR-MS can be useful. PTR-MS can measure a wide range of compounds (including OVOCs and sulfur compounds among others) fast and on-line, which makes it a suitable method to study on-line plant emissions and uptake. 

The oxidation reactions of alkanes, alkenes and aromatic hydrocarbons treated in this section are described in detail in monographs by Calvert et al. (2000, 2002, 2008), and reaction mechanisms for air quality models are summarized by StockweU et al. (2012). Also, Calvert et al. (2011) and Mellouki et al. (2003) reviewed the oxidation reactions of oxygenated volatile organic compounds (OVOCs) which are not treated in this book. Detailed models for the photolysis... 

Miyakawa, Y., Kato, S., Kajii, Y. (2005) Calibration of the proton transfer reaction mass spectrometry (PTR-MS) instrument for oxygenated volatile organic compounds (OVOCs) and the measurement of ambient air in Tokyo. Taiki Kankyo Gakkaishi (Journal of Japan Society for Atmospheric Environment) 40,209. 

S. Reimann (2007), Oxygenated volatile organic compounds (OVOCs) at an urban background site in Zurich (Europe) Seasonal variation and source allocation, Atmo . Envimn., 41, 8409-8423. 

Urban Polluted Air Urban polluted air contains a few hundred species of hydrocarbons and oxygen containing volatile organic compounds (OVOCs) (Lewis et al. 2000), and the observation of OH and HO2 concentrations there validates the reaction model with the whole set of these VOCs. Comparisons between the model calculation and observation of OH and HO2 concentrations in urban air are also interesting from the point of checking the dependence of O3 formation rate on NOx and VOC in the polluted atmosphere, and are important as validation of a reaction model for the discussirai of the oxidant control strategy as described in the previous section. From these viewpoints, many measurements of and the comparison with model calculations have been made in urban air, and the values of (3-20) X 10 molecules cm for OH, and (1-12) x 10 molecules cm (4-50 pptv) for HO2 concentration, which are similar or higher than in the marine boundary layer, have been reported (Stone et al. 2012). 

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