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Halogen Chemistry in the Troposphere

The first mid-latitude demonstration of reactive halogen chemistry in the troposphere was made downwind of salt pans in the Dead Sea area, where... [Pg.1936]

Saiz-Lopez, A., von Glasow, R. Reactive halogen chemistry in the troposphere. Chem. Soc. Rev. [Pg.382]

Barbara J. Finlayson-Pitts is Professor of Chemistry at the University of California, Irvine. Her research program focuses on laboratory studies of the kinetics and mechanisms of reactions in the atmosphere, especially those involving gases with liquids or solids of relevance in the troposphere. Reactions of sea salt particles to produce photochemically active halogen compounds and the subsequent fates of halogen atoms in the troposphere are particular areas of interest, as are reactions of oxides of nitrogen at aqueous and solid interfaces. Her research is currently supported by the National Science Foundation, the Department of Energy, the California Air Resources Board, the Dreyfus Foundation, and NATO. She has authored or coauthored more than 80 publications in this area, as well as a previous book, Atmospheric Chemistry Fundamentals and Experimental Techniques. [Pg.991]

Stutz J., Hebestreit K., Alicke B., and Platt U. (1999) Chemistry of halogen oxides in the troposphere comparison of model calculations with recent field data. J. Atmos. Chem. 34, 65-85. [Pg.1976]

A64. Vogt, R. Cmtzen, P.J., 1996 Modelling of Halogen Chemistry in the Remote Marine Boundary Layer , in BorreU, P.M. Cvitas, T. Kelly, K. Seiler, W., (Eds.) Proceedings of the EUROTRAC Symposium 96, Garmisch-Partenkirchen, Germany, 25—29 March 1996 on Transport and Transformation of Pollutants in the Troposphere, Vol. 1, Clouds, Aerosols, Modelling and Photo-oxidants (Southampton Computational Mechanics Publications) 445-449. [Pg.99]

Hanson, D.R., and Ravishankara, A.R. (1993) Reactions of halogen species on ice surfaces, in The Tropospheric Chemistry erf Ozone in the Polar Regions, Ed. H. Niki and K.-H. Becker, NATO ASI Series Vol. 1-17, Springer-Verlag Berlin, Heidelberg, 281-290. [Pg.283]

Ozone in the lower stratosphere may in principle be affected by iodine chemistry (Solomon et al, 1994). The abundance of total iodine in the troposphere is believed to be of the order of pptv, but the fractional partitioning of iodine free radicals (I and IO) is much higher than in the case of other halogens (chlorine and even of bromine see Section 5.6.3). [Pg.377]

The stratospheric ozone-depleting potential of a compound emitted at the Earth s surface depends on how much of it is destroyed in the troposphere before it gets to the stratosphere, the altitude at which it is broken down in the stratosphere, and chemistry subsequent to its dissociation. Halocarbons containing hydrogen in place of halogens or containing double bonds are susceptible to attack by OH in the troposphere. (We will consider the mechanisms of such reactions in Chapter 6.) The more effective the tropospheric removal processes, the less of the compound that will survive to reach the stratosphere. Once halocarbons reach the stratosphere their relative importance in ozone depletion depends on the altitude at which they are photolyzed and the distribution of halogen atoms, Cl, Br, and F, contained within the molecule. [Pg.193]

Platt, U. (1995) The chemistry of halogen compounds in the Arctic troposphere, in Tropospheric Oxidation Mechanisms, K. H. Becker, ed., European Commission, Report EUR 16171 EN, Luxembourg, pp. 9-20. [Pg.281]

Other secondary chlorine species (atomic Cl, CIO, ClOOCl etc.) have been made responsible for Arctic ozone depletion, whereas the sources of the chlorine atoms are poorly understood (Keil and Shepson 2006). The Cl atom reacts similarly to OH (e. g. in oxidation of volatile organic compounds Cai and Griffin 2006). However, the photolysis of HCl is too slow (even in the stratosphere) to provide atomic Cl. Thus, the only direct Cl source from HCl is due to its reaction with OH, but with a fairly low reaction rate constant (Rossi 2003). There are several chemical means of production of elemental Cl (and other halogens) from heterogeneous chemistry (see Chapter 5.8.2) in the troposphere the photolysis of chloroorganic is not very important, with a few exceptions (see Chapter 5.8.1). [Pg.139]

As was discussed earlier, ozone plays an important part in the chemistry of the troposphere, where its excess is harmful, and in stratospheric chemistry, where its shortage is also detrimental. Ozone can decompose by several mechanisms thermal, photochemical, homogeneous catalysis reactions and under the action of solid surfaces. In the laboratory, the latter effect can be controlled by a suitable treatment of the reactor walls, as well as by a study of the rate of reaction as a function of the surface/volume ratio. In order to eliminate photochemical and homogeneous catalysis reactions, the chemical reaction must be carried out in the absence of radiations and catalytic additives, such as halogenated substances. The mechanism put forward to interpret the thermal reaction, can be written as follows ... [Pg.169]

In this section, among the chemical species that are photodecomposed in the troposphere, important molecules in atmospheric chemistry are discussed, with the exception of inorganic halogens, which are described in Sect. 4.4. [Pg.73]

The reactions of halogen atoms and radicals are of fundamental importance in stratospheric chemistry (see Sects. 4.4 and 8.2, 8.3, and 8.4), and the halogen cycle is also of interest in the marine boundary layer in the troposphere (see Sect. 7.5). In this section, among the atmospheric reactions of halogen atoms and radicals, fundamental homogeneous reactions of Cl atoms and CIO radicals are described, and the reactions of bromine and iodine atoms and radicals are discussed in the more phenomenological discussions in Chaps. 7 and 8. [Pg.216]

In the tropospheric halogen chemistry, CIONO2 is a quasi-stable compound formed in the chain termination reaction of CIO in the urban coastal area where NO concentration is relatively high. The reaction of CIONO2 with sea salt results in photochemically active CI2 as in the process. [Pg.253]

Oxides of nitrogen play a central role in essentially all facets of atmospheric chemistry. As we have seen, N02 is key to the formation of tropospheric ozone, contributing to acid deposition (some are toxic to humans and plants), and forming other atmospheric oxidants such as the nitrate radical. In addition, in the stratosphere their chemistry and that of halogens interact closely to control the chain length of ozone-destroying reactions. [Pg.264]

Case Study VI - The potential effect of tropospheric halogen chemistry on ozone - An example of the potential effect of the ozone depletion cycles (Cycles I and II) can be assessed using data from the MBL. Table 7 lists the rates of ozone depletion (from Cycles I and II) in the first hour after sunrise at Mace Head in Ireland. Measurements of... [Pg.57]

While the sulfuric acid is key nucleation precursor in the low troposphere, its contribution to the polar stratospheric chemistry is a lot more modest. Another strong acid-nitric-plays a major role as the dominant reservoir for ozone destroying odd nitrogen radicals (NOj) in the lower and middle polar stratosphere. Nitric acid is an extremely detrimental component in the polar stratosphere clouds (PSCs), where nitric acid and water are the main constituents, whose presence significantly increases the rate of the ozone depletion by halogen radicals. Gas-phase hydrates of the nitric acid that condense and crystallize in the stratosphere play an important role in the physics and chemistry of polar stratospheric clouds (PSCs) related directly to the ozone depletion in Arctic and Antarctic. [Pg.453]

The potentially strong involvement of halogens in tropospheric chemistry was first observed in the Arctic, where strong ozone depletion events were found to coincide with high levels of bromine (Barrie et al., 1988). [Pg.1936]


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Halogen chemistry

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In the halogenation

The Halogens

Troposphere

Troposphere chemistry

Troposphere halogens

Troposphere tropospheric chemistry

Tropospheric

Tropospheric halogen chemistry

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