Caesium estimation

A 20 g sample, prepared and stored in a dry box for several months, developed a thin crust of oxidation/hydrolysis products. When the crust was disturbed, a violent explosion occurred, later estimated as equivalent to 230 g TNT. A weaker explosion was observed with potassium tetrahydroaluminate. The effect was attributed to superoxidation of traces of metallic potassium, and subsequent interaction of the hexahydroaluminate and superoxide after frictional initiation. Precautions advised include use of freshly prepared material, minimal storage in a dry diluent under an inert atmosphere and destruction of solid residues. Potassium hydrides and caesium hexahydroaluminate may behave similarly, as caesium also superoxidises in air. 

Measurements of activity in grass and soil in areas where no rain fell at the relevant time have been used to estimate dry deposition after the Chernobyl accident. In Denmark and in southern England, vg for137Cs was about 0.5 mm s 1 (Roed, 1987 Clark Smith, 1988). In Stockholm, however, where the Chernobyl fallout arrived several days earlier, and the particle size was larger, the dry deposition velocity of caesium was 5 mm s 1 (Persson et al., 1987). Refractory elements such as 95Zr had dry deposition velocities about 20 mm s 1. 

C Complete the table on the next page to estimate the boiling point and atomic radius of caesium. Comment also on the reactivity of potassium and caesium with water. 

The salts of sodium react with a solution of potassium nitrite and the nitrates of bismuth and caesium, yielding a yellow, crystalline precipitate of the formula 5Bi(N02)3,9CsN02,6NaN02. This reaction is applicable to the detection and estimation of sodium.2... 

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... 

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. 

Other examples of conservative-type trace metals include caesium and rubidium. Caesi-um(l) exists at an average concentration of 2.2 nmol kg (Brewer et al., 1972) as the relatively unreactive monovalent cation Cs. Its oceanic residence time has been estimated to be 3 X 10 yr (Broecker and Peng, 1982). Rubidium exists as the monovalent cation Rb at a concentration of 1.4 pmol kg (Spencer et al., 1970) with an oceanic residence time estimated to be 3 Myr. 

Caesium-135 Cs-135 is a high yield FP. It was found to exceed the GQ level in IX resins and SPF media. It behaves in the same way as Cs-137 and can be estimated easily using FISPIN calculations. There is no need to produce an analytical method for this isotope. 

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