Aerosols manganese

Hopke, et al. (4) and Gaarenstroom, Perone, and Moyers (7) used the common factor analysis approach in their analyses of the Boston and Tucson area aerosol composition, respectively. In the Boston data, for 90 samples at a variety of sites, six common factors were identified that were interpreted as soil, sea salt, oil-fired power plants, motor vehicles, refuse incineration and an unknown manganese-selenium source. The six factors accounted for about 78 of the system variance. There was also a high unique factor for bromine that was interpreted to be fresh automobile exhaust. Large unique factors for antimony and selenium were found. These factors may possibly represent emission of volatile species whose concentrations do not oovary with other elements emitted by the same source. 

Stable aerosols of fine particulates as well as vapors constitute the greatest health risk because of the likelihood of pulmonary absorption. Correlations between trace element pollution and their concentrations in biological fluids or tissue are not uncommon and have been documented for arsenic (62) and lead (63). Man can absorb 75-85% of inhaled mercury vapor at concentrations of 50-350 pg/M3 (64) and even more at lower concentrations (65). Certain aerosols like vanadium, iron, manganese, and lead may contribute to the formation of secondary atmospheric pollutants (52, 66). 

Figure 7.4 Effect of pH cycling on the dissolution of manganese from crustal aerosols under conditions likely both in the atmosphere and on mixing into seawater (Spokes and Jickells, 1996). Manganese shows high solubility at a typical cloud water pH of 2. Solubility decreases slightly at rainwater pH of 5.5 and rapidly at pH 8. Extensive solution phase removal is not seen at pH 8 under conditions designed to mimic seawater, perhaps due to the formation of soluble MnCI+ and MnSOl-. Low pH cycling and inorganic complexation under seawater conditions increase manganese solubility six times over that seen at pH 8 alone.

Guieu, C., Duce, R. and Arimoto, R. (1994) Dissolved input of manganese to the ocean aerosol source./. Geophys. Res., 99, 18789-18800. 

Fig. 1. Relative importance of various urban sulphate aerosol production mechanisms T = total sulfate A = H2SO4 condensation H = HjOj oxidation O = uncatalyzed oxygen oxidation Q = O3 oxidation F = iron catalyzed oxidation M = manganese catalyzed oxidation C = soot catalyzed oxidation.

There has been recent interest in a somewhat different aspect of adsorption and reaction on metal oxides photocatalysis. The interest stems partially from that role that some transition-metal oxides can play in photochemical reactions in the atmosphere. Atmospheric aerosol particles can act as substrates to catalyze heterogeneous photochemical reactions in the troposphere. Most tropospheric aerosols are silicates, aluminosilicates and salts whose bandgaps are larger than the cutoff of solar radiation in the troposphere (about 4.3 eV) they are thus unable to participate directly in photoexcited reactions. However, transition-metal oxides that have much smaller bandgaps also occur as aerosols — the most prevalent ones are the oxides of iron and manganese — and these materials may thus undergo charge-transfer excitations (discussed above) in the pres-... 

Other metal compounds that are capable of decomposing at end gas temperatures to produce oxide smokes also can act as anti-knocks. These include iron and nickel carbonyls, trimethyl bismuth and methyl cyclopen-tadienyl manganese tricarbonyl [6]. The last has been used commercially for some years in Canada. Its anti-knock properties also can be amplified by organic co-anti-knocks (diketones in this case) [47]. Concerns over the possible toxicity of fine aerosols which are emitted in the exhaust will limit the acceptability of these metal containing materials in the future. 

A contribution to UV-induced photocatalysis is also expected from the cations of transitions metals such as iron, copper, and manganese dissolved in water droplets or the water layer that may cover a solid aerosol. Probable photoreactions in this case would be water splitting, or redox processes involving atmospheric contaminants that are easily absorbed by the water layer [30]. The primary step in these reactions is expected to be redox transformations of the electronically excited metal compounds [8]. 

Ulrich CE, Rinehart W, Brandt M. 1979a. Evaluation of the chronic inhalation toxicity of a manganese oxide aerosol. Ill - Pulmonary function, electromyograms, limb tremor, and tissue manganese data. Am Ind Hyg Assoc J 40 349-353. 

A variety of methods have been applied to the measurement of EC and OC in aerosol samples with the thermal, thermal optical reflectance (TOR), and thermal manganese oxidation (TMO) methods being the most popular. Understanding the operational principles of these methods is often necessary for the interpretation of reported EC and OC data. 

The airborne aerosol is filtered and after the filter mineralization, manganese is determined in the solution by a spectrophotometric method following oxidation with periodate in acid medium to the red-violet MnO anion... 

Other light-absorbing compounds that may be present in marine aerosol particles and contribute to photochemistry include transition metals, nitrate anions, amines, polyaromatic hydrocarbons, and other organic molecules. Transition metal complexes (including iron, copper, manganese, nickel) are... 

Pellizzari ED, Clayton CA, Rodes CE, Mason RE, Piper LL, Fort B, Pfeifer G, Lynam D (1999) Particulate matter and manganese exposures in Toronto. Canada Atmos Environ 33 721-734 Pfeifer GD, Harrison RM, Lynam DR (1999) Personal exposures to airborne metals in London taxi drivers and office workers in 1995 and 1996. Sci Total Environ 235 253-260 Ro C-U, Osan J, Van Grieken R (1999) Determination of low-Z elements in individual environmental particles using windowless EPMA. Anal Chem 71 1521-1528 Ro C-U, Osan J, Szaloki I, Van Grieken R (2000) Determination of chemical species in individual aerosol particles using ultra-thin window EPMA. Environ Sci Technol 34 3023-3030... 

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