Aromatic hydrocarbons ambient concentrations

Our knowledge of the chemical and physical processes that govern aerosol formation in the atmosphere is limited, and further research in the field is badly needed. Attention should be focused on laboratory studies of aerosol formation from aromatic hydrocarbons. The concentrations of aerosol precursors in the atmosphere should be determined more data on organic compounds in ambient aerosols are needed to estimate the relative importance of olefinic and aromatic hydrocarbons as aerosol precursors. 

De Raat, W. K., and F. A. de Meijere, Polycyclic Aromatic Hydrocarbon (PAH) Concentrations in Ambient Airborne Particles... 

Reference methods for criteria (19) and hazardous (20) poUutants estabHshed by the US EPA include sulfur dioxide [7446-09-5] by the West-Gaeke method carbon monoxide [630-08-0] by nondispersive infrared analysis ozone [10028-15-6] and nitrogen dioxide [10102-44-0] by chemiluminescence (qv) and hydrocarbons by gas chromatography coupled with flame-ionization detection. Gas chromatography coupled with a suitable detector can also be used to measure ambient concentrations of vinyl chloride monomer [75-01-4], halogenated hydrocarbons and aromatics, and polyacrylonitrile [25014-41-9] (21-22) (see Chromatography Trace and residue analysis). 

Table 1 Concentrations of chlorinated polycyclic aromatic hydrocarbons (CIPAHs), polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), polybrominated biphenyls (PBBs), polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), and polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs) in ambient air, soil, and human samples collected from e-waste recycling and reference sites in China... 

Murphy, D.J., R.M. Buchan, and D.G. Fox. 1982. Ambient particulate and benzo[a]pyrene concentrations from residential wood combustion, in a mountain community. Pages 567-574 in M. Cooke, AJ. Dennis, and G.L. Fisher (eds.). Polynuclear Aromatic Hydrocarbons Physical and Biological Chemistry. Battelle Press, Columbus, OH. 

In 1978, the emission of benzo(a)pyrene (BaP) from an aluminum plant In the vicinity of Sundsvall, Sweden, was estimated to be about four times the total amount emitted from all the motor vehicles In that country. As might be expected, the result of this estimate caused considerable concern, and a survey of the air quality In the Sundsvall area was made In 1980-81. The program monitored concentrations of polycyclic aromatic hydrocarbons (PAH) and fluoride In ambient air, with samples being collected once each week. Concentrations of fluoride and meteorological data were measured by the aluminum company laboratory, while PAH concentrations were determined by the Norwegian Institute for Air Research (NILU). 

Arey, J., B. Zielinska, R. Atkinson, and A. M. Winer, Polycyclic Aromatic Hydrocarbon and Nitroarene Concentrations in Ambient Air during a Wintertime High-NO, Episode in the Los Angeles Basin, Atmos. Environ., 21, 1437-1444 (1987). 

Atkinson, R., J. Arey, A. M. Winer, B. Zielinska, T. Dinoff, W. Harger, and P. McElroy, A Survey of Ambient Concentrations of Selected Polycyclic Aromatic Hydrocarbons (PAH) at Various Locations in California, Final Report to the California Air Resources Board, Contract No. A5-185-32, May 1988a. 

Wilson, N. K., T. R. McCurdy, and J. C. Chuang, Concentrations and Phase Distributions of Nitrated and Oxygenated Polycyclic Aromatic Hydrocarbons in Ambient Air, Atmos. Environ., 29, 2575-2584 (1995). 

Wilson, N.K., T.R. McCurdy, and J.C. Chuang. 1995. Concentrations and phase distributions of nitrated and oxygenated polycyclic aromatic hydrocarbons in ambient air. Atmos. Environ. 29 2575-2584. 

Since electrode measurements involve low substrate concentrations, reactive impurities have to be held to a very low level. The physical data and purification methods for several organic solvents used in electrode measurements have been summarized (Mann, 1969). But even when careful procedures for solvent and electrolyte purification are employed, residual impurities can have profound effects upon the electrode response. For example, the voltam-metric observation of dications (Hammerich and Parker, 1973, 1976) and dianions (Jensen and Parker, 1974, 1975a) of aromatic hydrocarbons has only been achieved during the last ten years. The stability of radical anions (Peover, 1967) and radical cations (Peover and White, 1967 Phelps et al., 1967 Marcoux et al., 1967) of aromatic compounds was demonstrated by cyclic voltammetry much earlier but the corresponding doubly charged ions were believed to be inherently unstable because of facile reactions with the solvents and supporting electrolytes. However, the effective removal of impurities from the electrolyte solutions extended the life-times of the dianions and dications so that reversible cyclic voltammograms could be observed at ambient temperatures even at very low sweep rates. 

Workplace air concentration data are discussed in Section 6.5. Data on ambient atmospheric concentrations of PAHs derived from other sources can be found in the ATSDR Toxicological Profile for Polycyclic Aromatic Hydrocarbons (Agency for Toxic Substances and Disease Registry 1995). 

Silver cations form only rather labile -complexes with aromatic hydrocarbons. The nature of the complex formation may be described as solvation of silver salts in arene solution. Supramolecular framework structures can be isolated upon concentration, and the structure of many of these solvates has been determined2. The Ag(I) cations are found to be mostly r 2 or ry bound to the arene, but the coordination is weak and arene may be removed already at ambient temperature in a vacuum. This class of compounds for which no synthetic strategy is required, is no longer considered in this chapter which is orientated towards preparative methods. The adducts have not yet found any significant applications. 

Arey, J., Zielinska, B., Atkinson, R., and Winer, A. M. (1987) Polycyclic aromatic hydrocarbon and nitroarene concentrations in ambient air during a wintertime high NO, episode in the Los Angeles basin, Atmos. Environ. 21, 1437-1444. 

Albinet A, Leoz-Garziandia E, Budzinski H, Villenave E, Jaffrezo JL (2008) Nitrated and oxygenated derivatives of polycyclic aromatic hydrocarbons in the ambient air of two French alpine valleys—Part 1. Concentrations, sources and gas/particle partitioning. Atmos Environ 42 43-54... 

Ts aMs M, Stephanou EG (2005) Occurrence of gaseous and particulate polycyclic aromatic hydrocarbons in the urban atmosphere study of sources and ambient temperature effect on the gas/particle concentration and distribution. Environ Pollut 133 147—156 USEPA (2009a) Organics questions, http //www.epa.gov/waste/hazard/testinethods/faq/faqs org.htm. Accessed 16 July 2009... 

As shown by Gileadi et al. [123-125], it is possible to form solutions based on aromatic hydrocarbons such as ethyl benzene, toluene, benzene, and mesity-lene. The electrolyte comprises ATBr and KBr [126]. By using a nearly molar concentration of these species, it is possible to obtain specific conductivity of the same order of magnitude as that measured in polar aprotic solutions (around 5 mQ Cm" ) at ambient temperatures. It was found that these electrolytes do not dissolve in the above solvents to form ions or ion pairs, but rather form clusters which are charged aggregates of ALBrv K. The conductivity mechanism is thus... 

Obtaining a reliable measure of the number of unpaired electrons ( spin concentration ) in a sample is often extremely useful. Even reliable relative values measured across a series of samples can often provide useful information. There are various important applications, as may be illustrated by the following incomplete list ESR dating, the determination of oxidized polycyclic aromatic hydrocarbons and of environmental carbon in samples of ambient air, the influence of air pollution (e.g., SO2 and NO2) on plants and soils, quantification of NO2, RO2, and HOI radicals in air samples, radiation dosimetry, redox activities of zeolite catalysts, and the metabolism of spin probes in cells and tissues. 

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