Nonmethane volatile organic compounds

Hundreds of chemical species are present in urban atmospheres. The gaseous air pollutants most commonly monitored are CO, O3, NO2, SO2, and nonmethane volatile organic compounds (NMVOCs), Measurement of specific hydrocarbon compounds is becoming routine in the United States for two reasons (1) their potential role as air toxics and (2) the need for detailed hydrocarbon data for control of urban ozone concentrations. Hydrochloric acid (HCl), ammonia (NH3), and hydrogen fluoride (HF) are occasionally measured. Calibration standards and procedures are available for all of these analytic techniques, ensuring the quality of the analytical results... 

Historically, measurements have classified ambient hydrocarbons in two classes methane (CH4) and all other nonmethane volatile organic compounds (NMVOCs). Analyzing hydrocarbons in the atmosphere involves a three-step process collection, separation, and quantification. Collection involves obtaining an aliquot of air, e.g., with an evacuated canister. The principal separation process is gas chromatography (GC), and the principal quantification technique is wdth a calibrated flame ionization detector (FID). Mass spectroscopy (MS) is used along with GC to identify individual hydrocarbon compounds. 

Karbiwnyk, C. M., Mills, C. S., Helmig, D., and Birks, J. W., Use of chlorofluorocarbons as internal standards for the measurement of atmospheric nonmethane volatile organic compounds sampled onto solid adsorbent cartridges. Environ. Sci. TechnoL, 37, 1002-1007, 2003. 

TABLE 2.10 Estimated Global Anthropogenic Emissions of Nonmethane Volatile Organic Compounds... 

Inomata, S., Tanimoto, H., Kato, S. et al. (2010) PTR-MS measurements of nonmethane volatile organic compounds during an intensive field campaign at the summit of Mount Tai, China, in June 2006. Atmos. Chem. Phys. 10,7085. 

Table l-C-2. Inventory and speciation of the nonmethane, volatile organic compounds emitted from anthropogenic sources in the U.K. as calculated from data derived for the year 2000 (Dore et al., 2008)... 

Ketones are emitted directly to the atmosphere, and their sources were discussed in detail in chapter I. In the U.K. acetone and butanone comprise about 1% and 5%, respectively, of the total anthropogenic emissions of oxygenated compounds, and 1.6% and 1.1%, respectively, of the total anthropogenic emissions of nonmethane volatile organic compounds. Ketone emissions from solvents (both industrial and personal) are substantial emissions from both gasoline- and diesel-fueled vehicles also contribute. Ketones are also formed extensively in the atmosphere in the oxidation of other compounds. Acetone, for example is formed in the OH-initiated oxidation of propane, iio-butane, iso-pentane, and neopentane and from a number of higher hydrocarbons. It is also formed in the oxidation of terpenes. The distribution, sources, and sinks of acetone in the atmosphere have been analyzed by Simpson et al. (1994). Methyl vinyl ketone is an important first generation product in the OH-initiated oxidation of isoprene. 

Method 25 applies to the measurement of volatile organic compounds (VOC) as nonmethane organics (TGNMO), reported as carbon. Organic particulate matter will interfere with the analysis, and, therefore, in some cases, an in-stack particulate filter will be required. The method requires an emission sample to be withdrawn at a con-... 

Methane and the Nonmethane Hydrocarbons. It is traditional to distinguish CH4 from all other atmospheric hydrocarbons. Methane is by far the most abundant atmospheric hydrocarbon and has very large natural emissions. Its abundance in auto exhaust but low atmospheric reactivity has led air pollution scientists to enact controls on nonmethane hydrocarbons NMHC (also called VOC for volatile organic compounds, which include oxygenated hydrocarbons). 

K. Olszyna, T. Kleindienst, W. Lonneman, S. Bertman, P. Shep-son, and T. Starn, Observations of Nonmethane Hydrocarbons and Oxygenated Volatile Organic Compounds at a Rural Site in the Southeastern United States, J. Geophys. Res., 103, 28111-28128 (1998). 

CFC-ll, chlorofluorocarbon 1,4DCB, 1,4-dichlorobenzene NMVOC, nonmethane volatile organic carbon compound PM, particulate matters DALY, dis- ... 

---