Atmospheric transformations

Organophosphate Ester Hydraulic Fluids. No information concerning the atmospheric transformation and degradation of organophosphate ester hydraulic fluids was found in the available literature. 

Because of the dominance of distributed sources over local single sources in the production of photochemical oxidants, point-source models are not discussed here. Related research regarding the measurement of diffusion or the development of atmospheric chemical submodels are not emphasized. Giapter 2 is devoted to the chemical processes that govern atmospheric transformation and removal, and this aspect of the models is not repeated here. 

Baxley, J. S., and J. R. Wells, The Hydroxyl Radical Reaction Rate Constant and Atmospheric Transformation Products of 2-Butanol and 2-Pentanol, hit. J. Chem. Kinet., 30, 745-752 (1998). 

In 1997, Busby and co-workers reported that 2-nitrofluoranthene, an important product of atmospheric transformations (vide infra) was inactive in MCL-5 cells but a potent mutagen in hlAlv2 cells another important atmospheric reaction product, the nitrophenanthrene lactone 2-nitrodibenzopyranone (XI), was inactive in both hlAlv2 and MCL-5 cells. Furthermore, it was nonmutagenic in the forward mutation bacterial assay in the absence of rat liver postmi-tochondrial supernatant (-S9) but was mutagenic with the addition of S9 mix. 

Busby, W. F., Jr., H. Smith, C. L. Crespi, B. W. Penman, and A. L. Lafleur, Mutagenicity of the Atmospheric Transformation Products 2-Nitrofluoranthene and 2-Nitrodibenzopyranone in Salmonella and Human Cell Forward Mutation Assays, Mutat. Res., 389, 261-270 (1997). 

Trifluoroacetic acid is an atmospheric transformation product of freon substitutes. It enters surface waters by precipitation where it dissociates into its ionic form trifluoroacetate and then remains virtually inert. 

Figure 2. Schematic illustration showing the atmospheric transformation undergone by hydrocarbons.

Once in the atmosphere, OAs can also undergo a wide range of physical and chemical aging processes under atmospheric conditions. OA components can react with atmospheric photooxidants (e.g., OH, NO3, and 03), acids (e.g., H2S04 and HN03), water, and UV radiation, forming for instance more polar and hygroscopic products than the precursor material. These atmospheric transformation processes can also occur at the surface layers of BC or EC (Poschl, 2005). 

Aluminum-containing particulate matter in the atmosphere is mainly derived from soil and industrial processes where crustal material (e g., minerals) are processed. Aluminum is found as silicates, oxides, and hydroxides in these particles (Eisenreich 1980). Aluminum compounds cannot be oxidized and atmospheric transformations would not be expected to occur during transport. Should aluminum metal particles be released during metal processing, they would be rapidly oxidized. 

Atmospheric Transformations. S02 can be oxidized to form H2S0A in either the gas phase through photochemical reactions, or in the aqueous phase in cloud water (16). Clouds can then evaporate, leaving behind sulfate particles. The photochemical reactions are fairly slow, 1-3%/hr, but operate during all daylight hours. 

Simmons Zepp 1986 quoted, Howard et al. 1991) atmospheric transformation lifetime T 1-5 d (Kelly et al. 1994). 

Air photooxidation t,/2 = 284-2840 h, based on estimated rate constant for the reaction with hydroxyl radical in air (Atkinson 1987 quoted, Howard et al. 1991) atmospheric transformation lifetime t 1-5 d (Kelly et al. 1994). 

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