Atmosphere aerosol

The existing variety of means and methods of micro-element analysis is used worldwide for the determination of element contents in atmospheric aerosols when they ai e collected at aspiration filters, sediment and natural surfaces and biota objects where toxic substances migration can be observed. 

Twomey, S., "Atmospheric Aerosols." Elsevier, North-Holland, New York, 1977. 

Haze (Hazy) an atmospheric aerosol of sufficient concentration to be visible. The particles are so small that they cannot be seen individually, but are still effective attenuating light and reducing visual range. 

LInknown broadband influences due to atmospheric aerosols, lamp fluctu ations, and dust on the mirrors are minimized by dividing the spectrum by a fitted fifth-order polynomial. The construction of the measuring instrumentation IS shown in Fig. 13.50. 

Table 7-4 Oxyacids, their salts, and ionized forms that could exist in atmospheric aerosol particles...

Fig. 7-12 Schematic of an atmospheric aerosol size distribution. This shows the three mass modes, the main sources of mass for each mode, and the principal processes involved in inserting mass into and removing mass from each mode (m = mass concentration. Dp = particle diameter). (Reproduced with permission from K. T. Whitby and G. M. Sverdrup (1983). California aerosols their physical and chemical characteristics. In "The Character and Origin of Smog Aerosols" (G. M. Hidy, P. K. Mueller, D. Grosjean, B. R. Appel, and J. J. Wesolowski, eds), p. 483, John Wiley, New York.)...

All of these species are very soluble in a rain or cloud drop and are an important source of atmospheric aerosols. For ammonia and ammonium, the condensed phases (I and s) represent approximately two-thirds of the total atmospheric burden, whereas for nitric acid and nitrates, about two-thirds is in the gas phase (Soderlund and Svensson, 1976). 

Most of the non-gaseous impurities in ice were once atmospheric aerosols. Atmospheric aerosols raining onto an ice sheet are of two types primary aerosols, which are incorporated directly into the atmosphere as aerosols (these include continental dust and sea spray), and secondary aerosols which form in the atmosphere from gases. In addition to aerosol-derived impurities, some soluble gases in the atmosphere (HNO3 HCl, H2O2, and NH3) adsorb directly onto ice, and so are measured in a core... 

Atmospheric aerosols have a direct impact on earth s radiation balance, fog formation and cloud physics, and visibility degradation as well as human health effect[l]. Both natural and anthropogenic sources contribute to the formation of ambient aerosol, which are composed mostly of sulfates, nitrates and ammoniums in either pure or mixed forms[2]. These inorganic salt aerosols are hygroscopic by nature and exhibit the properties of deliquescence and efflorescence in humid air. That is, relative humidity(RH) history and chemical composition determine whether atmospheric aerosols are liquid or solid. Aerosol physical state affects climate and environmental phenomena such as radiative transfer, visibility, and heterogeneous chemistry. Here we present a mathematical model that considers the relative humidity history and chemical composition dependence of deliquescence and efflorescence for describing the dynamic and transport behavior of ambient aerosols[3]. 

Andreae MO, Crutzen (1997) Atmospheric aerosols biogeochemical sources and role in atmospheric chemistry. Science 276 1052-1058. 

Jang M, SR McDow (1997) Products of benz/a/anthracene photodegradation in the presence of known organic constituents of atmospheric aerosols. Environ Sci Technol 31 1046-1053. 

Recently was estimated an expected impact on the global chemistry of the atmosphere of the indirect heterogeneous photocatalytic reactions under the much more abundant near ultraviolet, visible and near infrared solar light [2]. As photocatalysts may serve atmospheric aerosols, i.e. ultrasmall solid particles that sometimes are embedded into liquid droplets. Aerosols are known to contain Ti02, Fc203, ZnO and other natural oxides, as well as metal sulfides of volcanic or antropogenic origin, that may serve as semiconductor photocatalysts (see Fig.5). Aerosols are known to be concentrated mainly in the air layers near the surface of the Earth, i.e. in the troposphere, rather than stratosphere. 

The atmospheric aerosols were filtered by a two-stage sampler that classified them into fine (< 1.2 pm) and coarse (> 1.2 pm) fractions, which were then further classified into 13 size ranges between 0.01 to 30 pm. An example of a PIXE spectrum of a coarse particle is illustrated in Figure 4.21. 

The attachment rate to the atmospheric aerosol X=0 Z, is a linear function of the particle concentration Z. Values of 5 10 3 cm3h-l for the average attachment coefficient B measured in laboratory rooms were reported by Mohnen (1969) and Porstendorfer and Mercer (1978). 

In addition this investigation showed that the desorption probability by recoiling of Pb-214 atoms from particle surfaces of atmospheric aerosol is 0.50 0.15. 

Measurements on aerodynamic sizes of atmospheric aerosols and associated radionuclides were carried out with Anderson 2000, Inc., 1-ACFM Ambient Impactors with or without the Anderson low-pressure modification, as well as with Sierra model 236 (six-stage) high-volume impactors (HVI). The 1-ACFM design operated at 28... 

Porstendorfer, J. and T. Mercer, Diffusion Coefficient of Radon Decay Products and their Attachment Rate to the Atmosphere Aerosol, in Natural Radiation Environment III. (T. F. Gesell and W. M. Lowder, eds.), CONF-780422, Vol. 1, pp. 281-293, National Technical Information Service, Springfield, Virginia (1980). 

Photolysis calculated t,/2 = 22 h for direct sunlight photolysis of 50% conversion at 40°N latitude of midday in midsummer in near surface water, t,/2 = 180 d in 5-m deep inland water and t,/2 = 190 d in inland water with a suspended sediment concentration of 20 mg/L partitioning (Zepp Schlotzhauer 1979) t,/2 = 180 d under summer sunlight in surface water (Mill Mabey 1985) direct photolysis t,/2 = 11.14 h (predicted- QSPR) in atmospheric aerosol (Chen et al. 2001). 

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