Rural aerosol

Table VI. Sources of Elements, Anions and Cations in Urban and Rural Aerosols ...

Examples of GC-MS data for typical total extracts from rural and urban aerosol particle samples (analyzed as silylated derivatives) (a) total ion current (TIC) trace for Oakridge, OR, rural aerosol (Jan/Feb. 1985) and (b) TIC trace for Pasadena, CA, aerosol (Feb. 1989), DEHP = diethylhexyl phthalate, lA = carbon chain length of -alkanoic acids. 

FIGURE 9.28 Size distribution of particle geometric cross section (A) as a function of geometric diameter for a typical rural aerosol (adapted from Hegg et at., f993). 

Liu, L., and M. H. Smith, Urban and Rural Aerosol Particle Optical Properties, Atmos. Environ., 29, 3293-3301 (1995). 

Lodge, J. P., Jr., A Comparison of Urban and Rural Aerosol Composition Using Dichotomous Samplers, Atmos. Environ., 19, 840 (1985). 

The common assumption the ai = a2 = a can lead to errors for the urban, maritime, and rural aerosol profiles. The Angstrom exponents are determined as a function of aerosol type and relative humidity (cf. Appendix B of Gueymard.)7... 

S F RURAL Aerosol profde to use AEROS (one of 10 choices, including user specified)... 

Even A., ten Brink H., Blatter A., Neftel A., and Gaggeler H. W. (2002) Urban and rural aerosol characterization of summer smog events during the PIPAPO field campaign in Milan, Italy. J. Geophys. Res. 107, 10.1029/2001JD001292. 

Shown are the reactions, the rate coefficients k (at 298 K, in units of cm3/molecule s), and the relative rates (in units of s l) for two atmospheric conditions (A) low and (B) medium number densities of NO, N02, and S02. The last line gives collision frequencies for CH3Oz radicals interacting with marine and rural aerosol particles (see Table 7-5), assuming a scavanging efficient of unity (maximum rate). Numbers in parentheses indicate powers of 10. 

Apart from the n-alkanes discussed above, epicuticular wax hydrocarbons contain sesqui- and diterpenoids. These compounds are based on the structural skeletons of cadinane and abietane, respectively, which are shown in Fig. 7-24. The sesquiterpenoids recovered by Simoneit and Mazurek (1982) in the rural aerosol were calamenene, tetrahydrocadalane, and cadalene. These compounds presumably are degradation products of cadinane derivatives (various isomers of cadinenes and cadinols), which are ubiquitous in essential oils of many higher plants (Simonsen and Barton, 1961). The major diterpenoid hydrocarbons observed in the aerosol samples were dehy-droabietane, dehydroabietin, and retene. The main source of abietane derivatives are coniferous resins. The parent compounds dehydrate fairly rapidly to yield the more stable hydrocarbons found in the aerosols. These may then serve as markers for hydrocarbons arising from vegetation, in addition to the odd-to-even carbon number preference in the n-alkanes. 

Fig. 2,2 Collection efficiency (fraction deposited) of various parts of the human respiratory system and a normalized volume-size distribution of the rural aerosol. The ordinate is given as a linear scale. (From Jaenicke 1986.)...

The mass distribution of continental aerosol not influenced by local sources has a small accumulation mode and no nuclei mode. The PM10 concentration of rural aerosols is around 20 pg m-3. 

Aerosols in rural areas are mainly of natural origin but with a moderate influence of anthropogenic sources (Hobbs et al., 1985). The number distribution is characterized by two modes at diameters about 0.02 and 0.08 /xm, respectively (Jaenicke, 1993), while the mass distribution is dominated by the coarse mode centered at around 7 /xm (Figure 7.17). The mass distribution of continental aerosol not influenced by local sources has a small accumulation mode and no nuclei mode. The PM lo concentration of rural aerosols is around 20 /xg m . 

Rural aerosols SVOCs, VOCs SLE HP-5 (20x0.25x0.25)x Semi-rot. HD ToF MS [32]... 

Figure 6 Comparison of GC-MS and GCxGC-ToF MS in the characterisation of rural aerosols. Spectral quality improvement of alloaromadendrene extracted ion chromatogram and mass spectrum obtained by (a) GC-MS and (b) GCxGC-ToF MS and from (c) NIST library spectrum [32].

Kallio et al. developed an automated procedure for the identification of individual compounds in atmospheric samples and used it for the data analysis of rural aerosol samples [32]. In this procedure, retention indexes, quality parameters (minimum required similarity, S/N value, allowed I difference between experimental and library values), modulation parameters, library files, and retention times of reference compounds were utilized to construct a program for data analysis. As output, the program listed compounds that fulfilled the required criteria. The automated procedure was compared with manual identification, and it was concluded that the automated procedure worked satisfactorily if the concentrations were sufficiently high (above ca. 10 ng/m ), but for very low concentrations (low ng/m ) manual search was more accurate. 

Rural aerosols, which are continental aerosols that are influenced to some degree by anthropogenic activities. 

Figure 4 A typical bimodal number-size distribution of a rural aerosol (24-hr average) measured on Hoher Peifienberg, Germany. The measurements were performed by the Institute for Tropospheric Research in April 1994. The solid squares represent the measurement, and the solid line the sum of log-normal distributions (dotted lines) of the Aitken and the accumulation mode.

Clarke AG, Willison MJ, Zeki EM. A comparison of urban and rural aerosol eompo-sition using diehotomous sampler. Atmos Environ 1984 18 1767-1775. 

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