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Periodic Table--Uranium

There are three naturally occurring isotopes of uranium: 234U (< 0.01%), 235U (0.72%), and 238U (99.27%). All three isotopes are radioactive. 238U (half- life 4.47 x 109 years) decays to 234U (half-life 247,000 years) and then to 206Pb by way of several intermediate daughter products. The ratio between 238U and 234U is highly variable. A number of hypotheses have been advanced to explain the disparity, including: recoil of the daughter isotope during alpha emission (Cherdyntsev et al., 1961); differential adsorption of isotopes by rocks (Clanet et al., 1976); and differential absorption of isotopes into solution (Fleischer, 1980). While this decay series has been used extensively for dating rocks, especially in conjunction with daughter isotopes in the same decay series, there has also been some use in hydrology (see, for example, Driscoll et al., 1993; Kraemer and Genereux, 1998).

235U (half-life 7.04 x 108 years) decays, through several steps, to form 207Pb. It is relatively uncommon in nature; the 235U/238U ratio is about 1:139. Consequently, while it has been used in dating in a manner similar to its sister isotopes of uranium, it has seen little use in hydrology.

Source of text: This review was assembled by Dan Snyder from the references below.

Bernat, M. and Church, T. M. (1989). "Uranium and thorium decay series in the modern marine environment." In: P. Fritz and J.-Ch. Fontes (Eds.), Handbook of Environmental Isotope Geochemistry, Volume 3, Amsterdam, Elsevier Science. pp. 357-384.
Cherdyntsev, V. V., Orlov, D. P., Isabaev, E. A., and Ivanov, V. I. (1961). "Isotopic composition of uranium minerals". Geochemistry, 10, 927-936.
Clanet, F., Leclerq, J., Remy, M. L., and Moroni, J. P. (1976). "Mise en evidence expérimental du role de l'adsorption différentielle du thorium et de l'uranium sur les roches silicatée dans l'état d'équilibre entre les activités des radioisotopes 234U et 238U dans la nature". C. R. Acad. Sci. Paris, Sér. D, 282, 807-810.
Driscoll, C. T., Otton, J. K., and Iverfeldt, Å. (1993). "Trace metals speciation and cycling." In:B. Moldan and J. Cerný (Eds.), Biogeochemistry of Small Catchments--A Tool for Environmental Research, Scientific Committee on Problems of the Environment, Wiley & Sons, New York. pp. 299-322.
Faure, G. (1986). Principles of Isotope Geology, Second Edition. John Wiley and Sons, New York. 589 pp.
Fleischer, R.L. (1980). "Isotopic disequilibrium of uranium: alpha- recoil damage and preferential solution effects", Science, 215, 667-671.
Gebauer, D., and Grünenfelder, M. (1979). "U-Th-Pb dating of materials", In: Lectures in Isotope Geology (Eds. E. Jäger and J.C. Hunziker), Springer-Verlag, New York. pp. 105-131.
Kraemer, T.F. and Genereux, D.P. (1998). "Applications of Uranium- and Thorium-Series Radionuclides in Catchment Hydrology Studies." In: C. Kendall and J.J. McDonnell (Eds.), Isotope Tracers in Catchment Hydrology, Elsevier, Amsterdam, pp. 679-722.
Related Links
Periodic Table
Fundamentals of Stable Isotope Geochemistry
General References
Isotope Publications
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