Xenon atmospheric abundance

Bogard D. D. and Garrison D. H. (1998). Relative abundances of argon, krypton, and xenon in the Martian atmosphere as measured in Martian meteorites. Geochimica et Cosmochimica Acta, 62(10) 1829-1835. 

Noble gases may provide a constraint on the source of water and other volatiles. The abundance pattern of noble gases in planetary atmospheres resembles that of chondrites, perhaps arguing against comets. However, there are some differences, especially in the abundance of xenon. Relative to solar system abundances, krypton is more depleted than xenon in chondrites, but in the planets, krypton and xenon are present in essentially solar relative abundances (Fig. 10.11). This observation has been used to support comets as the preferred source of volatiles (even though measurements of xenon and krypton in comets are lacking). A counter-argument is that the Ar/H20 ratio in comets (if the few available measurements are accurate and representative) limits the cometary addition of volatiles to the Earth to only about 1%. 

Xenon occurs in the atmosphere to the extent of approximately 0.00087%, making it the least abundant of the rare of noble gases in the atmosphere. In terms of abundance, xenon does not appear on lists of elements in the earth s crust because it does not exist in stable compounds under normal conditions. However, xenon because of its limited solubility in HjO. is found in seawater to the extent of approximately 950 pounds per cubic mile (103 kilograms per cubic kilometer). Commercial xenon is derived from air by liquefaction and fractional distillation. There are nine... 

Helium is the second most abundant element in the universe. In the Earth, it is continuously formed by radioactive decay, mostly of uranium and thorium. Its present concentration in the atmosphere is probably the equilibrium concentration between the amount being released from the Earth s crust and the amount of hehum escaping from the atmosphere into space. The atmosphere represents the major source for neon, argon, krypton, and xenon. They are produced as by-products during flactional distillation of liquid air. Radon is obtained from the radioactive decay of radium. 

For most of the chemical elements, the relative abundances of their stable isotopes in the Sun and solar nebula are well known, so that any departures from those values that may be found in meteorites and planetary materials can then be interpreted in terms of planet-forming processes. This is best illustrated for the noble gases neon, argon, krypton, and xenon. The solar isotopic abundances are known through laboratory mass-spectrometric analysis of solar wind extracted from lunar soils (Eberhardt et al., 1970) and gas-rich meteorites. Noble gases in other meteorites and in the atmospheres of Earth and Mars show many substantial differences from the solar composition, due to a variety of nonsolar processes, e.g., excesses of " Ar and... 

Besides their presence due to in situ radioactive decay within a given solid sample, radiogenic " He, " Ar, Xe, Pu-fission xenon (and krypton), and likely also U-fission xenon, are also prominent or observable constituents of planetary atmospheres, and their abundance is important in constraining models for planetary atmosphere evolution (see Chapter 4.12). 

Noble gases and nitrogen in martian meteorites reveal several interior components having isotopic compositions different from those of the atmosphere. Xenon, krypton, and probably argon in the mantle components have solar isotopic compositions, rather than those measured in chondrites. However, ratios of these noble gas abundances are strongly fractionated relative to solar abundances. This decoupling of elemental and isotopic fractionation is not understood. The interior ratio in martian meteorites is similar to chondrites. 

Hagee et al., 1990) calculated values of (4-7) X 10 2, with the higher number considered more likely to represent the solar value, although a lower value remains a possibility. The amount produced by U in the bulk silicate Earth (7.5 X 10 2 atoms Xe) is much less, and so bulk silicate Earth (and atmospheric) 2 Xe is dominantly plutonium-derived even if xenon was lost over the first 10 a of Earth history (see Chapter 4.12) so that half of the plutonium-derived xenon was lost, plutonium-derived Xe is still 13 times more abundant in the Earth. 

The greatest difficulty in constraining the global xenon budget has been in calculating the abundances of radiogenic xenon in the atmosphere (see Chapter 4.12). The composition for nonradio-genic atmospheric xenon (Section 4.11.2.5) provides ratios of 5 053... 

Nonradiogenic argon and xenon isotope concentrations of such a lower-mantle reservoir cannot be directly calculated without assuming either specific lower-mantle Ar/Ne and Xe/Ne ratios or argon and xenon isotopic compositions. Since modification of the noble gases in the atmosphere has occurred, the relative abundances of the interior of the Earth are unlikely to match those now observed in the atmosphere. For example, a closed-system lower mantle with "Xr/ Ar 3,000 (see Section 4.11.2.4) and 270 ppm K has " Ar= 5.7 X lO atoms g and so... 

The martian mantle has high xenon concentrations and distinct abundance patterns. Martian meteorites contain components other than those derived directly from the atmosphere (see detailed discussion by Swindle, 2002). In particular, noble gases in the dunite meteorite Chassigny appear to represent a distinct interior reservoir. The " Kr/i Xe ratio of 1.2 (Ott, 1988) is lower than both the martian atmosphere (20) and solar (16.9) values, but is similar to that of Cl chondrites. If this is truly a source feature, it indicates that heavy noble gases trapped within the planet suffered substantially different elemental fractionation than the atmosphere. The interior " Kr/ Ar ratio of 0.06 is much higher than the solar value of 2.8 X 10 ", but it is close to the atmospheric value of 0.02 and so does not display the same contrast as the Kr/Xe ratio. Unfortunately, it is not possible to determine if the measured elemental abundance ratios were modified by planetary processing or transport and incorporation into the samples. 

The isotopic composition of the martian interior is only available for xenon. Data for the dunite Chassigny indicate that there is a mantle reservoir with nonradiogenic isotope ratios that appear to be indistinguishable from solar values (Ott, 1988 Mathew and Marti, 2001), and so does not exhibit the strong isotopic fractionation seen in the atmosphere. The relative abundances of Xe and Xe are also close to solar, indicating that this reservoir had a high Xe/Pu and Xe/I ratios, at least during the lifetime of " Pu. Data from other meteorites indicate that there are other interior martian reservoirs that contain solar xenon but with... 

Xenon is very rare in the atmosphere. Its abundance is estimated to be about 0.1 parts per million. Xenon does not have many practical applications. One of its primary uses is to fill specialized lamps. 

The escape velocity necessary for objects to leave the gravitational field of the Earth is 11.2 km Calculate the ratio of the escape velocity to the root-mean-square speed of helium, argon, and xenon atoms at 2000 K. Does your result help explain the low abundance of the light gas helium in the atmosphere Explain. 

Oxygen is the most abundant substance in the universe. Krypton and xenon are so rare as almost to leave doubts as to their existence. Methane is practically insoluble in water. Ammonia is absorbed to the extent of 1,000 times the volume of water. Chlorine may be liquefied and solidified with very meager pressures, and at atmospheric temperature. It is doubtful if hydrogen or methane have ever been even liquified, certainly not without the most extreme conditions of pressure and refrigeration. 

The Group 8A(18) elements are helium (He, the second most abundant element in the universe), neon (Ne), argon (Ar, which makes up about 0.93% of Earth s atmosphere), krypton (Kr), xenon (Xe), and radioactive radon (Rn). Only the last three form compounds [Group 8A(18) Family Portrait]. 

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