Periodic Table--Radium

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.