In troposphere

Cmtzen, P. J. (1988). Tropospheric ozone an overview. In "Tropospheric Ozone-Regional and Global Scale Interactions" (I. S. A. Isaksen, ed.). NATO ASI Series C, Vol. 227. D. Reidel Publ. Co., Boston, MA. 

Marenco, A., Gouget H., Nedelec P., Pages, J.-P. and Karcher, F. (1994). Evidence of a long-term trend in tropospheric ozone from Pic du Midi data series consequences positive radiative forcing. /. Geophys. Res. 99,16617-16632. 

Etheridge, D. M., Pearman, G. I., and Fraser, P. J. (1992). Changes in tropospheric methane between 1841 and 1978 from a high accumulation rate Antarctic ice core. Tellus 44B, 282-294. 

Hydrogen sulfide occurs in natural gas. It also is found in many sewer gases. It is a by-product of many industrial processes. Trace amounts of dissolved H2S are found in wastewaters in equilibrium with dissolved sulfides and hydrosulfides. It also is found in volcanic eruptions, hot springs and in troposphere. The average concentration of H2S in the air is about 0.05 ppb. 

Waggoner, A.P., Vanderpol, A.J., Charlson, R.J., Larsen, S., Granat, L., and Tragardh, C., Sulphate-Light Scattering Ratio as an Index of the Role of Sulphur in Tropospheric Optics. Nature, Lond., 261 120, 1976. 

Marenco, A., H. Gouget, P. Nedelec, J.-P. Pages, and F. Karcher, Evidence of a Long-Term Increase in Tropospheric Ozone from Pic du Midi Data Series Consequences Positive Radiative Forcing, J. Geophys. Res., 99, 16617-16632(1994). 

Collisional deactivation and energy transfer play important roles in tropospheric chemistry. For example, electronically excited S02 in the 3B, state can be deactivated by 02 (as well as by N2 and H20) to the ground ( A,) state, with part of this process occurring via triplet-triplet energy transfer to generate singlet electronically excited states of 02 ... 

To illustrate the application of Eqs. (OO) and (PP), let us calculate the rate of photolysis of acetaldehyde. Aldehydes such as CH3CHO play an important role in tropospheric chemistry because they photodissociate to produce free radicals. In the case of acetaldehyde, there are four possible sets of products ... 

As discussed in Chapter 1, nitrous acid is important in tropospheric chemistry because it photolyzes to form OH ... 

In this chapter we briefly review the fundamental kinetics needed for application to atmospheric systems and discuss some of the most common methods for determining rate constants in the laboratory. This includes so-called heterogeneous reactions, whose importance in the stratosphere is now well established and which are increasingly being recognized as important in tropospheric systems. For a review of these areas, see Molina et al. (1996). 

For many reactions, the temperature dependence of A is small (e.g., varies with Tl/2) compared to the exponential term so that Eq. (F) is a good approximation, at least over a limited temperature range. For some reactions encountered in tropospheric chemistry, however, this is not the case. For example, for reactions in which the activation energy is small or zero, the temperature dependence of A can become significant. As a result, the Arrhenius expression (F) is not appropriate to describe the temperature dependence, and the form... 

Although the photolysis of N02 is the major source of O-, ozone is sufficiently long-lived that it can be transported downwind and survive into the nighttime hours. Hence it is a player in tropospheric chemistry throughout the day and night. 

The carbon-centered hydroxy-containing radical CH2OH formed in reactions (37) and (39) is encountered frequently as an intermediate in tropospheric organic oxidations. It is commonly referred to as an a-hydroxy radical. These types of radicals react in a... 

In short, the mechanism of OH-aromatic reactions remains today one of the least understood areas in tropospheric chemistry. 

PAN is known to play an important role in tropospheric chemistry. As discussed in this section, its thermal decomposition releases both N02 and an organic free radical, so that it can act as an NOx reservoir and ultimately as a source of OH in the dark. In addition, PAN is a strong lachrymator (eye irritant), is mutagenic in certain bacterial assays, and is phytotoxic to plants. Because of these broad effects on a variety of systems, its formation and reactions have been studied in some detail. 

Ciccioli, P., E. Brancaleoni, M. Frattoni, A. Cecinato, and A. Bra-chetti, Ubiquitous Occurrence of Semi-Volatile Carbonyl Compounds in Tropospheric Samples and Their Possible Sources, Atmos. Environ., 27A, 1891-1901 (1993a). 

Rockmann, T C. A. M. Brenninkmeijer, P. Neeb, and P. J. Crutzen, Ozonolysis of Nonmethane Hydrocarbons as a Source of the Observed Mass Independent Oxygen Isotope Enrichment in Tropospheric CO, J. Geophys. Res., 103, 1463-1470 (1998). 

It is interesting that while N2Os is believed to play a significant role in tropospheric chemistry, it has never been directly measured in the troposphere. However, using the measured concentrations of N02 and N03 and the equilibrium constant for the reaction in which it is formed,... 

Clearly, such real-time, single-particle techniques have great promise in terms of elucidating the chemical nature of different species in tropospheric particles and determining whether they exist as internal or external mixtures. 

In short, while there are many common elements and size distributions in tropospheric particles found in many areas around the world, it is important to recognize that in some circumstances, the particle composition and size distributions may be unique. 

Figure 9.45 shows the structures of a few of the other organics found in tropospheric aerosols and be-... 

FIGURE 9.45 Some naturally occurring organics found in tropospheric particles (adapted from Simoneit el at.. 1988, 1989). 

Hastie, D. R., G. I. Mackay, T. Iguchi, B. A. Ridley, and H. I. Schiff, Tunable Diode Laser Systems for Measuring Trace Gases in Tropospheric Air, Environ. Sci. Technol., 17, 352A-364A (1983). 

Figure 12.1 shows typical average vertical ozone profiles measured at Edmonton, Alberta, Canada, in the January-April period in 1980-1982 and in 1993, respectively. The high concentrations of ozone in the stratosphere are evident, demonstrating why this region is often referred to colloquially as the ozone layer. (The significant decrease in stratospheric ozone from the period 1980-1982 to 1993 will be discussed below. While a small decrease in tropospheric ozone is seen in these particular data, ozone levels have generally increased in the troposphere see Chapter 14.)... 

Krankowsky, D., F. Bartecki, G. G. Klees, K. Mauersberger, and K. Schellenbach, Measurement of Heavy Isotope Enrichment in Tropospheric Ozone, Geophys. Res. Lett, 22, 1713-1716 (1995). 

Livingston, F. E., and B. J. Finlayson-Pitts, The Reaction of Gaseous N205 with Solid NaCI at 298 K Estimated Lower Limit to the Reaction Probability and Its Potential Role in Tropospheric and Stratospheric Chemistry, Geophys. Res. Lett., 18, 17-20(1991). 

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