Xenon concentration atmosphere

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. 

Photolytic. Atkinson (1985) reported a rate constant of 2.59 x 10 " cmVmolecule-sec at 298 K. Based on an atmospheric OH concentration of 1.0 x 10 molecule/cm , the reported half-life of allyl alcohol is 0.35 d. The reaction of allyl alcohol results in the OH addition to the C=C bond (Grosjean, 1997). In a similar study, Orlando et al. (2001) studied the reaction of allyl alcohol with OH radicals at 298 K. Photolysis was conducted using a xenon-arc lamp within the range of 240-400 nm in synthetic air at 700 mmHg. A rate constant of 4.5 x 10 " cm /molecule-sec was reported. Products identified were formaldehyde, glycolaldehyde, and acrolein. 

Xenon occurs in the atmosphere at trace concentrations. It also occurs in gases from certain mineral springs. Xenon also is a fission product of uranium, plutonium, and thorium isotopes induced by neutron bombardment. The radioactive fission product, xenon-135, has a very high thermal neutron cross-section. The element has been detected in Mars atmosphere. 

Xenon is an odourless, colourless, non-explosive gas present in the atmospheres of both Earth and Mars in concentrations of approximately 0.08 ppm. Its density is approximately three times and its viscosity twice that of nitrous oxide. Like other noble gases, such as helium and argon, its outer electron shell contains the maximum number of electrons (8) making the molecule highly stable chemically. Despite this, its anaesthetic activity indicates that xenon binds to cell proteins and cell membrane constituents. 

In contrast to the terrestrial planets, the giant planets are massive enough to have captured and retained nebular gases directly. However, concentrations of argon, krypton, and xenon measured in Jupiter s atmosphere by the Galileo spacecraft are 2.5 times solar, which may imply that its atmosphere preferentially lost hydrogen and helium over the age of the solar system. 

Neon concentrations are 144-172%. Thus excess atmospheric neon (recognized as atmospheric by its isotopic composition) is present. The other noble gases are also present in concentrations exceeding 100%, but the excess decreases towards xenon. In other words, the retention percentage pattern is Ne > Ar > Kr > Xe. 

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. 

The model is consistent with the isotopic evidence that upper mantle xenon does not have a simple direct relationship to atmospheric xenon. The radiogenic xenon presently seen in the atmosphere was degassed from the upper portion of the solid Earth prior to the establishment of the present upper mantle steady state xenon isotope compositions and concentrations. The lower mantle ratios are established early in Earth history by decay of I and Pu decay produces a relatively small fraction of fissiogenic nuclides (Porcelli and Wasserburg, 1995b). The xenon daughters (now in the upper mantle) of the shortlived parents are supplied from the lower mantle. The MORE Xe/ Xe ratio (when corrected for air contamination) has no radiogenic contributions... 

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... 

Xenon is used in the nuclear energy area in bubble chambers, probes, and other applications where a high atomic mass is desirable. Currently, the anesthetic properties of xenon are being explored. Xenon is found in the atmosphere with a concentration of about 0.087 ppm. 

Figure 9, Light-induced dissolution of hematite in the presence of oxalate under nitrogen atmosphere, Experimental conditions 0.5 gL-1 hematite initial oxalate concentration ImmolL-1 pH = 3 /0 = 4kWm"2 white light from a high-pressure xenon lamp after passing a Pyrex glass filter irradiated surface 50 cm2 reaction volume 250 mL (Siffert, 1989).

Most inhaled anesthetic agents are liquids that are vaporized in a device within the anesthesia delivery system. The exception is xenon that is a naturally occurring gas and worthy of mention because it is an almost perfect inhalational anesthetic—except for one thing, cost. While it can provide general anesthesia, it is prohibitively expensive to produce because its concentration in the atmosphere is only... 

---