Radium has 25 different isotopes, four of which are found in nature.
223Ra, 224Ra, 226Ra and 228Ra
are all generated in the decay of either U or Th. 226Ra is a
product of 238U decay, and is the longest-lived isotope of Ra
with a half-life of 1602 years; next longest is 228Ra, a product
of 232Th breakdown, with a half-life of 6.7 years. Since Ra
is closely related to Ca, it has the potential for causing great harm by
substituting for the latter element in bone.
Like radon, radium has been used in hydrologic studies as a chemical
tracer in environments where mixing water masses have distinct radium concentrations.
Because radium has several naturally occurring isotopes, differences in
the isotopic ratios of radium can be used even where no difference in absolute
amount of radium exists between water masses, or non-conservative behavior
occurs. An additional advantage of radium over radon is its nonvolatile
behavior, although it does tend to sorb onto particulate material more
readily than does radon.
Studies using radium to solve hydrologic problems in catchment-size
basins have been few compared to those in which radon was used to determine
water from various ground water sources, but show great potential for further
development. Several examples showing how radium has been used in catchment
hydrology studies are provided by Kraemer and Genereux (1998) and Michel
et al. (1982).
Source of text: This review was assembled by Eric Caldwell and
Dan Snyder from the following references.
||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
3, Amsterdam, Elsevier Science. pp. 357-384.
||Bowen, R. (1988). Isotopes in the Earth Sciences. Elsevier Applied
Science, New York, 647 pp.
||Faure, G. (1986). Principles of Isotope Geology, Second Edition.
John Wiley and Sons, New York. 589 pp.
||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.
||Michel, J., King, P.T., and Moore, W.S. (1982). "228Ra
and 226Ra in drinking water: a new technique using gamma-ray
spectroscopy and results from South Carolina", in Isotope Studies
of Hydrologic Processes (Eds. E.C. Perry, Jr. and C.W. Montgomery),
Northern Illinois University Press, DeKalb, Illinois. pp.83-90.
||Miller, R.L., Kraemer, T.F. and McPherson, B.F. (1990). "Radium
and radon in Charlotte Harbor estuary, Florida Est." Coast and
Shelf Sci., 31: 439-457.
||Volpe, A.M., Olivares, J.A. and Murrell, M.T. (1991). "Determination
of radium isotopes ratios and abundances in geologic samples by thermal
ionization mass spectrometry." Anal. Chem., 63: 913-916.