Particle airborne pollutant

As an exercise, let s adapt this model of the analytical approach to a real problem. For our example, we will use the determination of the sources of airborne pollutant particles. A description of the problem can be found in the following article ... 

National Research Council, Committee on Medical and Biological Effects of Environmental Pollutants, Subcommittee on Airborne Particles. Airborne particles. Elniversity Park Press, Baltimore, 1979,... 

Smog Large cities with many automobiles may have another problem with airborne pollutants. It is called smog, which is a haze or fog that is made harmful by the chemical fumes and suspended particles it contains. 

Systems for sampling of airborne pollutants usually consists of three parts (a) a means of collecting the air sample (b) a device to trap the pollutant and (c) a means of measuring the amount of air sampled. The sampling methods frequently used for this purpose are sedimentation [21,22], centrifugation [23], impaction, filtration and thermal or electrostatic precipitation [24,25], the commonest of which are filtration, impaction and electrostatic precipitation. The size of the collected particles depends on the particular method used. 

Heavy metals such as cadmium, lead, iron, and zinc, in their metallic state, corrode and form salts and bases, which take up cationic sites on soil particles. In some cases, land is often contaminated from the spillage of heavy metal ions directly from aqueous plating shop wastes or airborne pollution from metal smelters. Soil has the capacity to immobilize signihcant quantities of heavy metal ions, to the 2%-3% level in some cases, such as the top soil around lead smelters. 

National Academy of Sciences (1991) Human exposure assessment for airborne pollutants advances and opportunities. National Academy Press, Washington, DC Nazaroff W, Weschler C (2004) Cleaning products and air fresheners exposure to primary and secondary air pollutants. Atmos Environ 38 2841-2865 Oberdorster G, Sharp Z, Atudorei V et al (2004) Translocation of inhaled ultrafine particles to the brain. Inhala Toxicol 16 437 145... 

Particle characterisation can be applied to both core samples and surface sediments to obtain information on the impacts of changes through time at a site or the impacts of contemporary emissions across a region, respectively. Such information is useful for policy formulation and in terms of targeted emission reductions, whether to protect a sensitive environment or the health of a population, source identification for airborne pollutants is vital. Supporting evidence can also be provided for long-range transport models as particulate sources may be identified from external sources (e.g. Davies et al., 1984). 

Manabe, S., Kurihara, N., Wada, O., Izumikawa, S., Asakuno, K., and Morita, M. 1993a. Detection of a carcinogen, 2-amino-1-methyl-6-phenylimidazo (4,5-B)pyridine, in airborne particles and diesel-exhaust particles. Environ. Pollut. 80 281-286. 

There are two portions of the soil that are important to the environmental investigator. The siuface layer (0-15 cm) reflects the deposition of airborne pollutants, especially recently deposited pollutants and also pollutants that do not move downward because of attachment to soil particles. On the other hand, pollutants which have been deposited by liquid spills, by long-term deposition of water soluble materials, or by burial may be found at considerable depth. The methods of sampling each of these are slightly different, but all make use of basic techniques [266]. 

The oceans of the world are an important natural source of pollutant material. The ocean is continually emitting aerosols to the atmosphere, in the form of salt particles, which are corrosive to metals and paints. The action of waves on rocks reduces them to sand, which may eventually become airborne. Even the shells washed up on the beach are eroded by wave and tidal action until they are reduced to such a small size that they too may become airborne. 

The chemical composition of particulate pollutants is determined in two forms specific elements, or specific compounds or ions. Knowledge of their chemical composition is useful in determining the sources of airborne particles and in understanding the fate of particles in the atmosphere. Elemental analysis yields results in terms of the individual elements present in a sample such as a given quantity of sulfur, S. From elemental analysis techniques we do not obtain direct information about the chemical form of S in a sample such as sulfate (SO/ ) or sulfide. Two nondestructive techniques used for direct elemental analysis of particulate samples are X-ray fluorescence spectroscopy (XRF) and neutron activation analysis (NAA). 

Other measurements important to visual air quality are pollutant related, i.e., the size distribution, mass concentration, and number concentration of airborne particles and their chemical composition. From the size distribution, the Mie theory of light scattering can be used to calculate the scattering coefficient (20). Table 14-2 summarizes the different types of visual monitoring methods (21). 

Aircraft can take vertical temperature soundings and can measure air pollutant and tracer concentrations and turbulence intensity. Airborne lidar can measure plume heights, and integrating nephelometers can determine particle size distributions. 

Finlayson-Pitts BJ, IN Pitts (1997) Tropospheric air pollution ozone, airborne toxics, polycyclic aromatic hydrocarbons, and particles. Science 276 1045-1052. 

Airborne particles collected with filters distributed across Vitoria, Brazil were analyzed by MB spectroscopy, whereby certain Fe-bearing minerals indicated different pollution sources. For example, hematite comes mostly from iron ore pellet plants, pyrite from handling and storing coal in the industrial area, and magnetite is related to steelwork plants (de Souza et al. 2001). 

Conventional studies generally involve the collection of an assemblage of airborne particles followed by determinations of the average or bulk concentrations of pollutant species present (12). However, the results often lack the analytical specificity required to identify particle sources, to determine particle speciation and reactivity, or to assess particle toxicity. 

Alpert, D. J.j Hopke, P. K. A Determination of the Sources of Airborne Particles Collected During the Regional Air Pollution Study, Atmospheric Environ., in press, I98I. 

Finlayson-Pitts, B. J., and J. N. Pitts, Jr., Tropospheric Air Pollution Ozone, Airborne Toxics, Polycyclic Aromatic Hydrocarbons, and Particles, Science, 27b, 1045-1052 (1997). 

Ozkaynak, H., A. D. Schatz, G. D. Thurston, R. G. Isaacs, and R. B. Husar, Relationships between Aerosol Extinction Coefficients Derived from Airport Visual Range Observations and Alternative Measures of Airborne Particle Mass, J. Air Pollut. Control Assoc., 35, 1176-1185 (1985). 

As we have seen, a great deal is known about emission sources and strengths, ambient levels, and mutagenic/carcinogenic properties of the particle-phase PAHs in airborne POM. However, because of the tremendous physical and chemical complexity of the aerosol surfaces on which photolysis, photooxidations, and gas-particle interactions take place in real polluted ambient air, much less is known about the structures, yields, and absolute rates and mechanisms of formation of PAH and PAC reaction products, especially for the more polar PACs. This is one area in which there exists a major gap in our knowledge of their atmospheric chemistry and toxicology. 

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