Atmospheric aerosols particulate matter

Here we have restricted our attention to atmospheric aerosols (particulate matter) because of the crucial role these particles play in adverse health effects, visibility reduction, soiling, and acid rain—the most serious effects of air pollution. However, it should be noted that many of the techniques discussed in this book also can be applied to gas-phase species. 

Neutron activation analysis is one of the major techniques for the determination of many minor and trace elements in a large variety of solid environmental and pollution samples, such as atmospheric aerosols, particulate emissions, fly ash, coal, incineration ash, and sewage sludge. Instrumental neutron activation analysis of total, inhal-able, or respirable airborne particulate matter collected on a cellulose or membrane filter, or in a cascade impactor on some organic substrate, allows the determination of up to 45 elements by an irradiation - counting scheme similar to the one given in Figure 3. Radiochemical NAA is applied only when extremely low limits of determination are required. Instrumental photon activation analysis is also complementary to INAA. 

Donahue NM, Robinson AL, Pandis SN (2009) Atmospheric organic particulate matter from smoke to secondary mganic aerosol. Atmos Environ 43(1) 94—106. doi 10.1016/j. atmosenv.2008.09.055... 

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. 

Donahue, N.M., A.L. Robinson, and S.N. Pandis (2009), Atmospheric organic particulate matter from smoke to secondary organic aerosol, Atmos. Environ., 43, 94-106. 

When a liquid or solid substance is emitted to the air as particulate matter, its properties and effects may be changed. As a substance is broken up into smaller and smaller particles, more of its surface area is exposed to the air. Under these circumstances, the substance, whatever its chemical composition, tends to combine physically or chemically with other particles or gases in the atmosphere. The resulting combinations are frequently unpredictable. Very small aerosol particles (from 0.001 to 0.1 Im) can act as condensation nuclei to facilitate the condensation of water vapor, thus promoting the formation of fog and ground mist. Particles less than 2 or 3 [Lm in size (about half by weight of the particles suspended in urban air) can penetrate the mucous membrane and attract and convey harmful chemicals such as sulfur dioxide. In order to address the special concerns related to the effects of very fine, iuhalable particulates, EPA replaced its ambient air standards for total suspended particulates (TSP) with standards for particlute matter less than 10 [Lm in size (PM, ). 

ITie major component of atmospheric haze is sulfate particulate matter (particularly ammonium sulfate), along with varying amounts of nitrate particulate matter, which in some areas can equal the sulfate. Other components include graphitic material, fine fly ash, and organic aerosols. 

Health effects attributed to sulfur oxides are likely due to exposure to sulfur dioxide, sulfate aerosols, and sulfur dioxide adsorbed onto particulate matter. Alone, sulfur dioxide will dissolve in the watery fluids of the upper respiratory system and be absorbed into the bloodstream. Sulfur dioxide reacts with other substances in the atmosphere to form sulfate aerosols. Since most sulfate aerosols are part of PMj 5, they may have an important role in the health impacts associated with fine particulates. However, sulfate aerosols can be transported long distances through the atmosphere before deposition actually occurs. Average sulfate aerosol concentrations are about 40% of average fine particulate levels in regions where fuels with high sulfur content are commonly used. Sulfur dioxide adsorbed on particles can be carried deep into the pulmonary system. Therefore, reducing concentrations of particulate matter may also reduce the health impacts of sulfur dioxide. Acid aerosols affect respiratory and sensory functions. 

Alternatively, in the presence of particulate matter and aerosols, sulfur dioxide may react with atmospheric oxygen to form sulfur trioxide, which forms sulfuric acid, a strong acid, in water ... 

Dautreband L, Capps R Studies on aerosols. IX. Enhancement of irritating effects of various substances on the eye, nose, and throat by particulate matter and liquid aerosols in connection with pollution of the atmosphere. Arch hit Pharmacodyn Ther 82 505, 1950... 

Nickel releases to the atmosphere are mainly in the form of aerosols that cover a broad spectrum of sizes. Particulates from power plants tend to be associated with smaller particles than those from smelters (Cahill 1989 Schroeder et al. 1987). Atmospheric aerosols are removed by gravitational settling and dry and wet deposition. Submicron particles may have atmospheric half-lives as long as 30 days (Schroeder et al. 1987). Monitoring data confrrm that nickel can be transported far from its source (Pacyna and Ottar 1985). Nickel concentrations in air particulate matter in remote, rural, and U.S. urban areas are 0.01-60, 0.6-78, and 1-328 ng/m, respectively (Schroeder et al. 1987). 

Daisey, J. M., R. J. Hershman and T. J. Kneip. Seasonal variations in ambient levels of particulate organic matter in New York City. Paper presented at the Symposium on Atmospheric Aerosols, 178th National Meeting of the American Chemical Society, Washington, D.C., Sept. 9-14, 1979. 

The aqueous phase that serves as a reaction medium in the atmosphere is present in the form of clouds, fogs, rain, and particulate matter consisting of either an aqueous solution containing pollutants or a film of water surrounding an insoluble core (see Chapter 9). For example, at typical relative humidities, 30-50% of the aerosol mass is due to water (Graedel and Weschler, 1981). However, many of the species that are believed to react in such atmospheric solutions, for example, S02, 03, H202, and NO, are emitted or formed in the gas phase. Before reactions can occur in solution, then, several steps illustrated in Fig. 5.12 must first take place ... 

The reviews Toxicological Indications of the Organic Fraction of Aerosols A Chemist s View by Van Cauwenberghe and Van Vaeck (1983) and Atmospheric Reactions of PAH by Van Cauwenberghe (1985) provide critical assessments and extensive literature references of the status of research to 1985 in the complex area of heterogeneous photochemical reactions and of the interactions of PAHs on laboratory substrates, primary combustion particles, and ambient particulate matter with ozone and NOz in air. In the following sections, we briefly summarize results from this earlier era and address subsequent studies on heterogeneous atmospheric reactions of PAHs in simulated and real atmospheres. 

One of the most successful applications of PIXE has been in the analysis of air pollution particulate matter. Atmospheric particulate matter is typically collected by impaction on a filter paper, which provides an ideal thin sample for PIXE analysis. Another aspect of PIXE that is very important for the analysis of aerosol samples is the ability to analyze a large number of samples in a short time. PIXE analyses typically take less than a minute, and the entire irradiation, counting, sample changing, and analysis procedure can be automated. 

In order to improve our knowledge about the marine aerosol and its formation we established a land-based aerosol sampling station on the western coast of Terceira island (Azores). Here we present the first measurements of a project of sampling atmospheric particulate matter which started in Spring of 1999 and will be extended for one year. 

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