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Hydrogen, tropospheric residence time

Harteck (1954) measured the amount of T in the lower atmosphere before H-bomb tests had added significantly to natural activity, and found 4000 and 3 TU in hydrogen and water vapour respectively. The amount of H2 in the atmosphere has increased in recent years due to industrial production (Schmidt, 1974). Circa 1950 there were about 1.5 x 1011 kg of H as H2, compared with 1.4 x 1015 kg as H20. Thus Harteck s values for natural T correspond to tropospheric inventories of 1.8 g as HT and 13 g as HTO. Because HTO is deposited in rain and by vapour transfer to the sea, its residence time in the troposphere is only about a week, similar to that of 137Cs (Fig. 2.8), and more than 90% of the atmospheric inventory is in the stratosphere. By contrast, the residence time of HT in the troposphere is several years (Mason Ostlund, 1979), and most of the atmospheric inventory of HT is in the troposphere. It is only necessary for a small fraction of naturally produced T to form HT to account for the high specific activity of hydrogen gas. [Pg.154]

A fairly general treatment of trace gases in the troposphere is based on the concept of the tropospheric reservoir introduced in Section 1.6. The abundance of most trace gases in the troposphere is determined by a balance between the supply of material to the atmosphere (sources) and its removal via chemical and biochemical transformation processes (sinks). The concept of a tropospheric reservoir with well-delineated boundaries then defines the mass content of any specific substance in, its mass flux through, and its residence time in the reservoir. For quantitative considerations it is necessary to identify the most important production and removal processes, to determine the associated yields, and to set up a detailed account of sources versus sinks. In the present chapter, these concepts are applied to the trace gases methane, carbon monoxide, and hydrogen. Initially, it will be useful to discuss a steady-state reservoir model and the importance of tropospheric OH radicals in the oxidation of methane and many other trace gases. [Pg.131]


See other pages where Hydrogen, tropospheric residence time is mentioned: [Pg.275]    [Pg.151]    [Pg.164]    [Pg.396]    [Pg.295]    [Pg.174]    [Pg.23]    [Pg.237]    [Pg.96]   
See also in sourсe #XX -- [ Pg.409 , Pg.501 ]




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