Elemental and Organic Carbon

A variety of methods have been applied to the measurement of EC and OC in aerosol samples with the thermal, thermal optical reflectance (TOR), and thermal manganese oxidation (TMO) methods being the most popular. Understanding the operational principles of these methods is often necessary for the interpretation of reported EC and OC data. 

Simple thermal methods do not use the optical correction of the TOR method, but rather define as OC the carbon that evolves during heating in the helium atmosphere, and EC as the carbon that is produced during further heating in the oxidizing atmosphere. 

FIGURE 14.A.1 Example of a thermal/optical reflectance carbon analyzer thermogram for an ambient sample collected in Yellowstone National Park (Chow et al. 1993). Reflectance and FID output are in relative units. Reflectance is normalized to initial reflectance and FID output is normalized to the area of the reference peak. (Reprinted from Atmos. Environ. 27, Chow et al., 1185-1201. Copyright 1993, with kind permission from Elsevier Science Ltd., The Boulevard, Langford Lane, Kidlington 0X5 1GB, UK.) 

Partitioning of semivolatile organic compounds has been measured using a filter to collect particles followed by a solid adsorbent trap to collect the vapor fraction (Ligocki and Pankow 1989 Foreman and Bidleman 1990 Cotham and Bidleman 1992 Kaupp and Umlauf, 1992 Pankow 1992 Turpin et al. 1993). 

1A The ambient fine-particle concentration of cholesterol in West Los Angeles was found to be 14.6 ngm-3 (Rogge et al. 1991). The same authors reported that the mean OC concentration for the same area for the same period was 7.5 pg(C) m-3 and that the emission rates from meat cooking (charbroiling and frying) in the area were  

Palen et al., 1992). The few products that have been identified include nopinone, pinane-diol, pinonic acid, and 5-(l-hydroxy-l-methyIethyl)-2-methyl-2- cyclohexen-l-one. 

Comparisons among the results of these methods show that they agree within 5 to 15% on the total measured carbon from ambient aerosol and source samples (Kusko et al., 1989 Countess, 1990). However, the individual EC and OC values are often quite different (Countess, 1990 Hering et al., 1990). Finally, we should note that because these methods oxidize the organic compounds they measure organic carbon (OC) concentration (in 

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Shimp, N.F. Schlercher, J.S. Ruch, R.R. Heck, D.B. Leland, H.V. Trace Element and Organic Carbon Accumlation in the Most Recent Sediments of Southern Lake Michigan. Environ. Geo. 1971 Notes 41, 25. 

Particulate carbon in the atmosphere exists predominantly in three forms elemental carbon (soot) with attached hydrocarbons organic compounds and carbonates. Carbonaceous urban fine particles are composed mainly of elemental and organic carbon. These particles can be emitted into the air directly in the particulate state or condense rapidly after Introduction into the atmosphere from an emission source (primary aerosol). Alternatively, they can be formed in the atmosphere by chemical reactions involving gaseous pollutant precursors (secondary aerosol). The rates of formation of secondary carbonaceous aerosol and the details of the formation mechanisms are not well understood. However, an even more fundamental controversy exists regarding... 

More recently Cass, Boone and Macias constructed a very detailed carbon inventory for Metropolitan Los Angeles in order to estimate the amount of primary elemental and organic carbon in this urban area ( ). Over 50 source types were included in this emission Inventory. A particulate lead emission inventory was also constructed and used as a tracer for primary automotive exhaust. They compared the ratio of organic carbon to elemental carbon and lead from the emission estimates to that measured in the atmosphere during winter mornings. In that study the sampling time and location were chosen in order to measure... 

Urban aerosol 105 Three modes nuclei, accumulation, and coarse larger particles contain crustal elements (Fe, Si, etc.), smaller contain nitrate, sulfate, ammonium, and elemental and organic carbon and are formed by combustion processes and gas-to-particle conversion... 

The composition of fine particles varies from region to region, depending on the precursor emissions. In the northeastern USA, central Europe, and southeastern Asia, more than half of the composition is made up of sulphate particles, due to the combustion of high-sulphur coal and oil. The rest is made up of nitrate particles, carbonaceous material (elemental and organic carbon), and crustal matter (fugitive particles from soil, clay, and rock erosion). 

Grivas G, Cheristanidis S, Chaloulakou A (2012) Elemental and organic carbon in the urban environment of Athens. Seasonal and diurnal variations and estimates of secondary organic carbon. Sci Total Environ 414 535-545... 

Xu, B., T. Yao, X. Liu, and N. Wang. 2006. Elemental and organic carbon measurements with a two-step heating-gas chromatography system in snow samples from the Tibetan Plateau. Ann. Glaciol. 43 257-262. 

Total samples are weight-averaged for elemental and organic carbon content... 

Figure 1 shows a schematic of a typical atmospheric aerosol particle (if such an entity can be assumed to exist). The particle consists of sulfates, nitrates, water, ammonium, elemental and organic carbon, metals, and dust. After a primary particle is emitted, gas-phase reactions occur, converting oxides of nitrogen to nitric acid, sulfur dioxide to sulfuric acid, and hydrocarbons to oxidized, low-vapor-pressure condensable organics. 

Jaffe L. A., Peucker-Ehrenbrink B., and Petsch S. T. (2002) Mobility of rhenium, platinum group elements and organic carbon during black shale weathering. Earth Planet. Sci. Lett. 198(3-4), 339-353. 

Chemical weathering of crustal material can both add and withdraw carbon from the atmosphere. The oxidation of elemental and organic carbon releases CO2 to the atmosphere ... 

TABLE 14.2 Elemental and Organic Carbon Percentages in Emissions by Different Sources... 

TABLE 14.3 Measured Daily Average Elemental and Organic Carbon Concentration in a Series of U.S. Studies... 

This contribution comprehensively reviews the literature reported for particulate emissions of motor vehicles operated under real-world conditions. This article will mainly focus on the results published for size segregated emissions factors of particle mass, elemental and organic carbon, crustal components and selected trace metals, since information is important for health effects studies and source reconciliation modeling efforts. 

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