Thorium complexes geochemistry

Thorium complexes, 3, 1131-1215 groundwaters geochemistry, 6. 852 polypyrazolylborates, 2. 255 Thorium(IV) complexes cupferron, 2, 512 peptides... 

Surface analytical techniques. A variety of spectroscopic methods have been used to characterize the nature of adsorbed species at the solid-water interface in natural and experimental systems (Brown et al, 1999). Surface spectroscopy techniques such as extended X-ray absorption fine structure spectroscopy (EXAFS) and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) have been used to characterize complexes of fission products, thorium, uranium, plutonium, and uranium sorbed onto silicates, goethite, clays, and microbes (Chisholm-Brause et al, 1992, 1994 Dent et al, 1992 Combes et al, 1992 Bargar et al, 2000 Brown and Sturchio, 2002). A recent overview of the theory and applications of synchrotron radiation to the analysis of the surfaces of soils, amorphous materials, rocks, and organic matter in low-temperature geochemistry and environmental science can be found in Fenter et al (2002). 

The extraction of dates from the uranium and thorium isotope ratios in speleothems depends on a quirk in the geochemistry of these two elements. Uranium is easily oxidized to the state where it usually appears as the U02 ion. The uranyl ion in addition to its intrinsic solubility also forms soluble carbonate complexes that further mobilize the element in karstic ground waters (Langmuir, 1978, 1997). Thorium is firmly locked into the insoluble Th" state and is immobile in ground water (Langmuir... 

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