Hydrogen in the atmosphere

G. Herzberg. Spectroscopic evidence of molecular hydrogen in the atmospheres of uranus and neptune. Astrophys. J., 115 337, 1952. 

Increased fossil fuel combustion has presmnably increased atmospheric hydrogen concentrations significantly in the last century, but there has been no detectable increase since 1990. If hydrogen uptake in the soil were becoming saturated, we would expect the concentration of hydrogen in the atmosphere to have increased, even if hydroxyl radical concentrations were increasing as well. 

Our knowledge about the distribution of molecular hydrogen in the atmosphere is incomplete. The first reliable analyses were made in 1923 by Schuftan, who found 0.50 0.10 ppmv (parts per million by volume) for hydrogen in air samples from different liquid air plants. This concentration has since been considered constant and representative for atmospheric air. 

K. L., and Aiello J. J. (1997) Galileo ultraviolet spectrometer observations of atomic hydrogen in the atmosphere of Ganymede. Geophys. Res. Lett. 24, 2147-2150. 

Therefore, hydrogen v/i)l leak out through the shell of the container by diffusion at a rate of 2.46 x 10 kg/s or 7.8 g ear. Note that the concentration of hydrogen in the nickel at the inner surface depends on the temperature and pressure of the hydrogen In the tank and can be determined as explained in Example 14-4. Also, the assumption of zero hydrogen concentration in nickel at the outer surface is reasonable since there is only a trace amount of hydrogen in the atmosphere (0,5 part per million by mole numbers). 

A leaky infrastructure could affect the atmosphere. Researchers from the California Institute of Technology and the Jet Propulsion Laboratory in Pasadena, CA, compared statistics for accidental industrial hydrogen and natural gas leakage. These were estimated at 10 to 20% of total volume. Extending these estimates to an economy that runs on hydrogen could result in four to eight times as much hydrogen in the atmosphere. 

Table 5.6 summarizes the components of the global hydrogen budget. The total amount of hydrogen in the atmosphere is about 200 Tg (170 Tg... 

The presence of hydrogen in the atmosphere appears to have been discovered as a by-product of the liquefaction of air. An early report by Paneth (1937) indicated an H2 mixing ratio of about 0.5 ppmv as derived from liquefied air in 1923. Schmidt (1974) has summarized a variety of measurements made during the period 1950-1970 that led to similar mixing... 

The present concentration of hydrogen in the atmosphere is 510 ppb which translates into a total mass of approx. 200 million tons, and the annual increase rate is 3 ppb. The average lifetime is two years before chemically bound or lost into space. The H2 emissions from the industrial use are with < 1 million t/yr small compared with other natural and anthropogenic sources. In case of the hydrogen economy based on a 80 % CO2 reduction scenario, H2 emissions are predicted to be 1.1 - 1,4 million t/yr [108]. 

From Equation (11.10b), the ratio of water vapour to hydrogen in the atmosphere may be calculated for any oxygen partial pressure and temperature. 

TPB, partial pressure of hydrogen in the atmosphere, oxygen vacancy concentration in the electrolyte, oxygen vacancy mobility, and temperature)... 

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