Aerosol acidity

A portion of nitrogen dioxide in the atmosphere is converted to nitric acid (HNO3) and ammonium salts. Nitrate aerosol (acid aerosol) is removed from the atmosphere... 

Sulfur oxides (SO,) are compounds of sulfur and oxygen molecules. Sulfur dioxide (SO2) is the predominant form found in the lower atmosphere. It is a colorless gas that can be detected by taste and smell in the range of 1, (X)0 to 3,000 uglm. At concentrations of 10,000 uglm , it has a pungent, unpleasant odor. Sulfur dioxide dissolves readily in water present in the atmosphere to form sulfurous acid (H SOj). About 30% of the sulfur dioxide in the atmosphere is converted to sulfate aerosol (acid aerosol), which is removed through wet or dry deposition processes. Sulfur trioxide (SO3), another oxide of sulfur, is either emitted directly into the atmosphere or produced from sulfur dioxide and is readily converted to sulfuric acid (H2SO4). 

Add Aerosol acidic liquid or solid particles that are small enough to become airborne. High concentrations of acid aerosols can be irritating to the lungs and have been associated with some respiratory diseases, such as asthma. 

Airborne inorganic acids exist in the industrial environment in the form of both vapors and particulates. This study was undertaken to answer a need for a simple sampling and analytical method for monitoring both vaporous and aerosol acid contaminants quantitatively. 

Yue, G.K., L.R. Poole, P.-H. Wang, and E.W. Chiou (1994) Stratospheric aerosol acidity, density, and refractive index deduced from SAGE II and NMC temperature data, J. Geophys. Res. 99, 3727-3787. 

Keene W. C., Pszenny A. A. P., Maben J. R., and Sander R. (2002) Variation of marine aerosol acidity with particle size. Geophys. Res. Lett. 29, doi 10.1029/2001GL013881. 

Cadle SH. 1985. Seasonal variations in nitric acid, nitrate, strong aerosol acidity, and ammonia in an urban area. Atmos Environ 19(1) 181-188. 

Othman I, Yassine T, Bhat I (1994) Measurments of some radioanuclides in the marine coastal environment of Syria. Sd Total Environ 153 57-60 Pathak RK, Louie PKK, Chan CK (2004) Characteristics of aerosol acidity in Hong Kong. Atmos Environ 38 2965-2974... 

During natural weathering, plastics are exposed to solar radiation (primarily UV radiation), heat, moisture (dew, rain, humidity), pollutants (aerosols, acid rain, ozone), and wind. These climatic factors vary so widely over Earth s surface that weathering of plastics is not always exactly predictable. Therefore, plastic performance varies with changes in climatic conditions [6]. 

The major areas where ion chromatography is used are for the analysis of atmospheric particulates, aerosols, acid rain, sulfur dioxide flue gas, and automobile exhaust Ion chromatographic applications in the area of air hygiene include the determination of ... 

Although a reference method has yet to be defined in the U.S. for acid aerosols, acid aerosol measurement methods have evolved over the years into a complex technology. As is the case with most air pollution measurements, the interpretation of concentration levels must be keyed to the measurement techniques used. The methodology now in most common use involves the following steps ... 

In summary, these early determinations of aerosol acidity suggest that levels were in the range up to about 15% of total sulfur and strongly dependent on ambient oxidants. 

Figure 4. Aerosol acidity measurements from Los Angeles, 1961 (data from Thomas, 1962).

Figure 6. Aerosol acidity measurements from Whiteface Mtn., NY (1984). (data from Kelly, 1987).

Figure 11. Aerosol acidity as a function of ozone concentration level, for various urban and rural sites.

Figure 13. Comparison of ambient aerosol acidity and averaging times with levels used in human clinical exposures (Wyzga and Lipfert, 1990). Ambient data represent the maximum values reported in the United States at any location, for that averaging time. Clinical exposures represent levels used for testing asthmatics (EPA, 1988).

Waldman, J.M., P.J. Lioy, G. D. Thurston, and M. Lippmann (1990), Spatial and temporal patterns in summertime sulfate aerosol acidity and neutralization within a metropolitan area. Atm. Em. 246 115-126. 

Equilibria (3) and (4) were found to be established veiy rapidly [20], probably at a diffusion-controlled rate. After escape of Br2 to the gas phase, photolysis (5) and reactions (6), (7) and (1) an auto-catalytic cycle of bromine activation is closed. Thus, bromide oxidation is driven by HO2,03 and aerosol acidity in the presence of sunlight and is catalysed by HOBr and CF. 

Munger, J.W. Eisenreich, S.J. 1983. Continental-scale variation in precipitation chemistry. Environ. Sci. Technol. 17 32A-42A. s Ferek, R. 1982. A study of aerosol acidity over the Northeastern United States. Cooperative Thesis No. 68. Boulder, Colo Natl. Cent, for Atmos. Res. and Florida St. Univ. 

Koutrakis P, Wolfson JM, Spengler JD. An improved method for measuring aerosol acidity results from a nine-month study in St. Louis, MO and Kingston, TN. Atmos Environ 1988 22 157-163. 

Lippman (45) has suggested that the observed associations may be specifically associated with the acidity of the particulates. Indeed, several analyses have suggested that increased mortality in London in the 1960s was more strongly associated with the acidity of the particles than with the blackness measured as British Smoke (46,47). However, Schwartz et al. (33) failed to find any association between aerosol acidity and mortality in contemporary U.S. data. 

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