Rare earth elements mobility

Alderton, D.H.M., Pearce, J.A. and Potts, J. (1980) Rare earth element mobility during granite alteration evidence from southwest England. Earth Planet. Sci. Lett., 49, 149-165. 

Menzies, M., Seyfried, W. and Blanchard, D. (1979) Experimental evidence of rare earth element mobility in green-stones. Nature (London), 282, 398-399. 

Whitford, D.J., Korsch, M.J., Orritt, PM. and Craven, S.J. (1988) Rare-earth element mobility around the volcanogenic polymetallic massive sulfide deposit at Que River, Tasmania, Australia. Chem. Geol, 8, 105-112,... 

Fayek, M. Kyser, T.K. 1997. Characterization of multiple fluid-flow events and rare-earth-element mobility associated with formation of unconformity-type uranium deposits in the Athabasca Basin, Saskatchewan. Canadian Mineralogist, 35, 627-658. 

Pan Y. and Fleet M. E. (1996) Rare earth element mobility during prograde granulite facies metamorphism significance of fluorine. Petrol 123, 251-262. 

Cuney M. and Mathieu R. (2000) Extreme fight rare earth element mobilization by diagenetic fluids in the geological environment of the Oklo natural reactor zones, EranceviUe Basin, Gabon. Geology 28, 743—746. 

Pan Y, Fleet ME (1996b) Rare-earth element mobility during prograde granulite-facies metamorphism significance of fluorine. Contrib Mineral Petrol 123 251-262 Pan Y, Stauffer MR (2000) Cerium anomaly and Th/U fractionation in the 1.85-Ga Flin Flon paleosol Clues from accessory minerals and implications for paleoatmospheric reconstiuction. Am Mineral 85 898-911... 

Greaves MJ, Statham PJ, and Elderfield H (1994) Rare earth element mobilization from marine atmospheric dust into seawater. Marine Chemistry 46 255-260. 

Nesbit, H.W. 1979. Mobility and fractionation of rare earth elements during weathering of a granodiorite. Nature, 279, 206-210. 

Lithophile elements such as magnesium, potassium, calcium, rubidium, strontium, the rare earth elements, and uranium (9) are not expected to be mobilized during oil shale retorting. Many of these elements can be determined quite precisely at trace element levels. Thus, investigation of the values of ER and RI for these elements should help to establish the reliability of the ER and RI values. 

Conservative elements (C,) include zirconium (Harden, 1987), titanium (Johnsson et al., 1993), rare earth elements, and niobium (Brimhall and Dietrich, 1987). Considerable disagreement occurs in the literature as to the relative mobility of these elements under differing weathering conditions (Hodson, 2002). Also, these elements are concentrated in the heavy mineral fractions and are often not suitable for describing weathering ratios in depositional environments where selective concentration and winnowing occurs. For such conditions, relatively inert minerals such as quartz can be considered (Sverdrup, 1990 White, 1995). 

Section 4 is devoted to some aspects of the experimental investigation of polymers in solution by PL. The results of the studies on the intramolecular mobility (IMM) of various parts of the polymer chain and its relationship to the chemical structure of macromolecules and the effect of hydrogen bonds and hydrophobic interactions on the IMM are discussed. Special attention is devoted to the relationship between the IMM of polymers and the intramacromolecular structurization caused by various factors (various specific intramolecular interactions or the presence of surface-active substances and ions of rare earth elements). This section also deals with the results of the investigation by the PL method of such complex and multi-component polymer systems as block copolymers, aoss-linked polymer systems and intermacromolecular complexes. 

Rare earth elements have been enriched into a stationary phase composed of toluene including 2-ethyl-hexylphosphonic acid mono-2-ethyUiexyl ester (EHPA) from 1 L of aqueous solution and eluted with a stepwise pH gradient. As many elements remained in the column head because of their high partition coefficients to the stationary phase, they can be eluted with mobile phase and also separated mutually. 

A 1000-mL sample solution containing 5 x lO M of each rare earth element were effectively enriched onto the CCC column head using carboxylic acid-toluene including the EHPA system [2j. Then, each element concentrated on the column head was eluted chromatographicaUy by the mobile phase with a stepwise pH gradient. 

For both PAA and HA, the lability of rare earth element interactions is greater for the smaller molecular weight fractions of each poly electrolyte. Similar observations have been reported for Cu(II) dissociation from size fractionated HA (22). Interestingly, the smaller size fractions of HA have been shown to the most effective in transporting Am(III) and Cm(III) through sandy aquifers (25). Consequently, the influence and affect of polyelectrolyte size must be considered when predicting the mobility of these complexes in natural systems. 

ROLE OF THE ROOTS OF VITIS VINIFERA L. FOR THE MOBILIZING OF SELECTED RARE EARTH ELEMENTS IN SOIL... 

Humphries S.E., 1984, The mobility of the rare earth elements in die crust. In Henderson P. (cd,). Rare earth element geochemistry. Elsevier, Amsterdam, pp. 315-341. 

The UV-Visible detector is the universal detector used in analytical and preparative CCC. It does not destroy solutes. It is used to detect organic molecules with a chromophore moiety or mineral species after formation of a complex (for instance, the rare earth elements with Arsenazo III ). Several problems can occur in direct UV detection, as has already been described by Oka and Ito 1) carryover of the stationary phase due to improper choice of operating conditions, with appearance of stationary phase droplets in the effluent of the column 2) overloading of the sample, vibrations, or fluctuations of the revolution speed 3) turbidity of the mobile phase due to difference in temperature between the column and the detection cell or 4) gas bubbling after reduction of effluent pressure. Some of these problems can be solved by optimization of the operating conditions, better control of the temperature of the mobile phase, and addition of some length of capillary tubing or a narrow-bore tube at the outlet of the column before the detector to stabilize the effluent flow and to prevent bubble formation. The problem of stationary phase carryover (especially encountered with hydrodynamic mode CCC devices) can be solved by the addition between the column outlet and UV detector of a solvent that is miscible with both stationary and mobile phases and that allows one to obtain a monophasic liquid in the cell of the detector (a common example is isopropanol). 

In several cationic conductors, for example sodium-ion conductors based upon Na2S04 and perovskite-type lithium-ion conductors, rare-earth elements are important constituents, which directly or indirectly aid the ionic conduction in such solids. Somewhat unexpectedly, rare-earth elements in oxidation state (III), despite their large size and high charge, themselves may be the mobile component in solid electrolytes such as P-alumina, LaNb309 and Sc2(W04)3 oxides. 

Determination of ages by the Sm/Nd method entails analyzing either individual minerals or cogenetic rock suites in which the ratios between the two are sufficiently different to define the slope of an isochron in coordinates of [ Nd/ Nd] and ] Sm/ Nd]. The method is especially suitable for mafic and ultramafic rocks, c the Rb/Sr method, which is best suited for acidic and intermediate igneous rocks enriched in rubidium and depleted in strontium. Since the rare earth elements are less mobile than the alkali metals and the alkaline earths, phenomena such as regional metamorphism have less effect on them. Hence, suitable rocks can be dated by the Sm/Nd method even if they have lost or gained rubidium and strontium and this makes the Sm/Nd method a useful complement to the R/Sr method. 

---