DETERMINATION OF TH-234 U-238 DISEQUILIBRIUM IN FRESH-WATER SYSTEMS

The use of Th-234/U-238 disequilibrium measurements is well establishe d in marine systems and is potentially very valuable in determining th e settling velocity of particles in freshwater systems. However, the m uch lower uranium concentrations in fresh waters prevent established t echniques from being used. An alternative approach, based on a combina tion of Cerenkov and liquid scintillation counting and a-spectrometry has improved the sensitivity of the technique so that freshwater sampl es can be measured.