Urban aerosols molecular

In a similar study, Allen and co-workers (1996) determined the particle size distribution for 15 PAHs with molecular weights ranging from 178 (e.g., phenan-threne) to 300 (coronene) and associated with urban aerosols in Boston, Massachusetts. As for BaP in the winter (Venkataraman and Friedlander, 1994b), PAHs with MW >228 were primarily present in the fine aerosol fraction (Dp < 2 /Am). A study of 6-ring, MW 302 PAH at the same site showed bimodal distributions, with most of the mass in the 0.3- to 1.0-/zm particle size size range a smaller fraction was in the ultrafine mode particles (0.09-0.14 /xm) (Allen et al., 1998). For PAHs with MW 178—202, the compounds were approximately evenly distributed between the fine and coarse (D > 2 /am) fractions. Polycyclic aromatic hydrocarbons in size-segregated aerosols col-... 

Didyk, B. M., Simoneit, B. R. T., Pezoa, L. A., Riveros, M. L., and Flores, A. A., Urban aerosol particles of Santiago, Chile organic content and molecular characterization, Atmos. Environ., 34,... 

Rogge, W. F., M. A. Mazurek, L. M. Hildemann, G. R. Cass, and B. R. T. Simoneit, Quantification of Urban Organic Aerosols at a Molecular Level Identification, Abundance and Seasonal Variation, Atmos. Environ., 27A, 1309-1330 (1993d). 

Simoneit, B. R. T., G. Sheng, X. Chen, J. Fu, J. Zhang, and Y. Xu, Molecular Marker Study of Extractable Organic Matter in Aerosols from Urban Areas of China, Atmos. Environ., 25A, 2111-2129 (1991a). 

Samburova, V., Zenobi, R., and Kalberer, M. (2005). Characterization of high molecular weight compounds in urban atmospheric particles. Atmos. Chem. Phys. 5, 2163-2170. Sannigrahi, P., Sullivan, A. P, Weber, R. I, and Ingall, E. D. (2006). Characterization of water-soluble organic carbon in urban atmospheric aerosols using solid-state 13C NMR spectroscopy. Environ. Sci. Technol. 40, 666-672. 

Simoneit, B.R.T., Sheng, G, Chen, X., Fu, J., Zhang, J., and Xu, Y. (1991) Molecular marker study of extractable organic matter in aerosols from urban areas of China. Atmos. Environ. 25A, 2111-2129. 

Molecular scattering coefficients for air have been tabulated (Table 5.2). For k = 0.5 fim, the visibility calculated from (5.58) is about 220 km or 130 mi. Hence the visibilities of a few miles or less, often observed in urban areas when the humidity is low, are due primarily to aerosol extinction. In sonte cases, however, there may be a contribution by NOi absorption,... 

Rogge WF, Mazurek MA, Hildemann LM, Cass GR, Simoneit BRT (1993) Quantification of urban organic aerosols at a molecular-level - identification, abundance and seasonal-variation. Atmos Environ Part A 27 1309-1330... 

Concentrations of Pb(CH3)4 and other tetraalkyllead compounds in atmospheric samples, which have been measured at different locations with species specific analytical methods, are listed in Table 11. Tetraalkyllead concentrations in indoors air were found to correspond closely with those in outdoors air [24]. More data on concentrations of alkyllead compounds in ambient air have been obtained with analytical methods which measure volatile organolead compounds or total organolead [28 to 55,173]. However, these data, being based on different sampling and analytical procedures, are difficult to compare see also [56 to 64]. According to [5], the results given in [28, 29, 32, 33] are probably unreliable. In this context it has to be considered that the majority of the nonfilterable (molecular) lead seems not to be organic in nature [58, 59] recently also tri- and/or dialkyllead compounds have been determined besides Pb(CH3)4 and other tetraalkyllead compounds in both urban and rural air in the vapor phase and in atmospheric aerosols [27,174] see also [182]. For analytical procedures to determine Pb(CH3)4 in atmospheric samples, see Section 1.1.1.1.1 on p. 75. 

Particles in the atmosphere, which range in size from about one-half millimeter (the size of sand or drizzle) down to molecular dimensions, are made up of an amazing variety of materials and discrete objects that may consist of either solids or liquid droplets (Table 15.1). Particulates is a term that has come to stand for particles in the atmosphere, although particulate matter or simply particles, is preferred usage. Particulate matter makes up the most visible and obvious form of air pollution. Atmospheric aerosols are solid or liquid particles smaller than 100 pm in diameter. Pollutant particles in the 0.001 to 10 pm range are commonly suspended in the air near sources of pollution, such as the urban atmosphere, industrial plants, highways, and power plants. 

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