Tritium age dating
In contrast, the application of environmental tracers to ground water hydrology has tended to be driven in large part by the introduction of analytical technologies developed by workers in other fields. Although in some cases the systematics of the tracer behavior have been worked out during investigations of ground water systems, more commonly the systematics have been previously well understood from independent investigations and the focus has mainly been on what the tracers can reveal about ground water flow and transport. How can the scientific research establishment promote the transfer of basic research results into applications? Many recent writers on this topic have attempted to generalize answers to these questions. The recharge rates are calculated from the slope of the line and the total chloride accumulation times (in parentheses) from the chloride inventory. Chloride inventories with depth are commonly used to estimate net infiltration rates (see Figure 1), and increases in concentration are used to estimate evapotranspiration (Allison et al., 1994). Based on the geological history of the site, the actual accumulation time is known to be between 13,000 and 15,000 years. Ancillary tracers include tritium (Scanlon, 1992), Cl (Tyler et al., 1996), and the stable isotopes of hydrogen and oxygen (Liu et al., 1995). Instead of attempting to trace development of the field over the past few years, which might result in a relatively unenlightening catalog of methodologies, a few of the most innovative applications will be highlighted here. Some of the questions raised by will then be addressed.
This setting is currently of great interest because the preponderance of ground water contamination problems are found there. However, the inexorable radio decay of the pulse of tritium released into the environment by the atmospheric nuclear weapons test of the early 1960s has reduced tritium concentrations in most ground water to the point where they are of little use. One reaction to the new circumstances was to call for increased emphasis on research that had relatively immediate societal applications.