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Caesium abundance

Rubidium (78 ppm, similar to Ni, Cu, Zn) and caesium (2.6 ppm, similar to Br, Hf, U) are much less abundant than Na and K and have only recently become available in quantity. No purely Rb-containing mineral is known and much of the commercially available material is obtained as a byproduct of lepidolite processing for Li. Caesium occurs as the hydrated aluminosilicate pollucite, Cs4ALiSi9026.H20, but the world s only commercial source is at Bemic Lake,... [Pg.70]

In solution culture experiments both strontium and caesium show hyperbolic absorption isotherms with respect to the external concentration of the element. Figure 7-15 (a) shows an example of a typical uptake isotherm for Sr while Shaw and Bell (1989) have demonstrated a similar isotherm for Cs. Baker (1981) has referred to such plant uptake responses as accumulator functions and has identified these as being typical of the absorption of elements over which plants can exert some degree of physiological control. Typically, the nutrient elements, including K and Ca, exhibit such isotherms and it can be postulated from the similarity in the uptake patterns of K and Cs on the one hand and Ca and Sr on the other that the radioions share, to some extent, the same uptake mechanisms as the nutrient ions. This has several important implications. Firstly, the direct competition for uptake sites between radioions and nutrient ions means that the external (soil) concentration of one is increased at the expense of the uptake of the other as the nutrient ions in question are vastly more abundant in soils than radioions it is K and Ca which will be effective in competitively excluding Cs and Sr, respectively. Secondly, the kinetics of this competition are concentration-dependent, so the assumption of first order kinetic movements of... [Pg.210]

Abundances of nonrefractory incompatible lithophile elements (potassium, rubidium, caesium, etc.) or partly siderophile/chalcophile elements (tungsten, antimony, tin, etc.) are calculated from correlations with RLE of similar compatibility. This approach was first used by Wanke et al. (1973) to estimate abundances of volatile and siderophile elements such as potassium or tungsten in the moon. The potassium abundance was used to calculate the depletion of volatile elements in the bulk moon, whereas the conditions of core formation and the size of the lunar core may be estimated from the tungsten abundance, as described by Rammensee and Wanke (1977). This powerful method has been subsequently applied to Earth, Mars, Vesta, and the parent body of HED meteorites. The procedure is, however, only applicable if an incompatible refractory element and a volatile or siderophile element have the same degree of incompatibility, i.e., do not fractionate from each other during igneous processes. In other words, a good correlation of the two elements over a wide... [Pg.721]

In order to use geochemical anomalies for tracing particular source compositions, it is necessary to establish normal behavior first. Throughout the 1980s, Hofmann, Jochum, and co-workers noticed a series of trace-element ratios that are globally more or less uniform in both MORBs and OIBs. For example, the elements barium, rubidium, and caesium, which vary by about three orders of magnitude in absolute abundances, have remarkably uniform relative abundances in many MORBs and OIBs (Hofmann and White, 1983). This became clear only when sufficiently high analytical precision (isotope dilution at the time) was applied to fresh... [Pg.790]

Rehnements of the Taylor and McLennan (1985) model are provided by McLennan and Taylor (1996) and McLennan (2001b). The latter is a modihcation of several trace-element abundances in the upper crust and as such, should not affect their compositional model for the bulk crust, which does not rely on their upper crustal composition. Nevertheless, McLennan (2001b) does provide modihed bulk-crust estimates for niobium, rubidium, caesium, and tantalum (and these are dealt with in the footnotes of Table 9). McLennan and Taylor (1996) revisited the heat-flow constraints on the proportions of mahc and felsic rocks in the Archean crust and revised the proportion of Archean-aged crust to propose a more evolved bulk crust composition. This revised composition is derived from a mixture of 60% Archean cmst (which is a 50 50 mixture of mahc and felsic end-member lithologies), and 40% average-andesite cmst of Taylor (1977). McLennan and Taylor (1996) focused on potassium, thorium, and uranium, and did not provide amended values for other elements, although other incompatible elements will be higher (e.g., rubidium, barium, LREEs) and compatible elements lower in a cmst composition so revised. [Pg.1313]

Seafloor hydrothermal alteration processes are important for the global geochemical cycles of many elements, and the record of these processes in the oceanic crust reveals much information about these cycles. Rather robust flux information can be obtained from a variety of elements that have rather low initial abundances in basalt (H2O, CO2, K2O, rubidium, caesium, uranium) or that are rather sensitive to alteration ( Sr/ Sr) and 5 0. Fluxes of many other elements are rather poorly constrained because of substantial primary magmatic variation. [Pg.1791]

Cs is a spin I = h nucleus of 100% natural abundance and a very small quadrupole moment of — 3.4 X 10 m. Cs in inorganic caesium compounds (Table 10.7) shows a moderate chemical shift range (about 300 ppm). The chemical shifts are normally referenced to aqueous CsCl solution. [Pg.665]

Rubidium, cesium (spelled caesium in England), and francium are soft, silvery gray metals. The abundances of these three elements are far less than the abundances of lithium, sodium, and potassium. The following is a list of three notable characteristics of these elements ... [Pg.78]


See other pages where Caesium abundance is mentioned: [Pg.466]    [Pg.168]    [Pg.184]    [Pg.168]    [Pg.55]    [Pg.311]    [Pg.709]    [Pg.828]    [Pg.1156]    [Pg.1278]    [Pg.1284]    [Pg.1309]    [Pg.1356]    [Pg.1564]    [Pg.1774]    [Pg.1837]    [Pg.2503]    [Pg.2756]    [Pg.247]    [Pg.191]    [Pg.218]    [Pg.2]    [Pg.5]    [Pg.126]    [Pg.457]   
See also in sourсe #XX -- [ Pg.70 ]

See also in sourсe #XX -- [ Pg.70 ]




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Caesium

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