Determination of thorium-234/uranium-238 disequilibrium in freshwater systems

The use of 234Th/238U disequilibrium measurements is well established in marine systems and is potentially very valuable in determining the settling velocity of particles in freshwater systems. However, the much lower uranium concentrations in fresh waters prevent established techniques from being used. An alternative approach, based on a combination of Cerenkov and liquid scintillation counting and α-spectrometry has improved the sensitivity of the technique so that freshwater samples can be measured.