A comparison of PERALS® to alpha spectrometry and beta counting: a measure of the sedimentation rate in a coastal basin

PERALS method (Photon/Electron-Rejecting Alpha Liquid Scintillation) is given by its constructor as a quick and accurate method for alpha nuclide counting. With an adapted sample preparation, the separation and alpha counting efficiency would be close to 100%. In this study, we intend to assess its potential applied to recent geochronology. Using the 210Po210Pb method, we carried out the dating of two cores sampled in the Thau basin (southern France). In the aim to test the reproducibility and the accuracy, several types of standardized materials (artificial tracers and natural soil samples) were previously analyzed. The chemical preparation of solid samples, already described by Case and McDowell [1], has been slightly adapted for our sediments. An intercomparison with the standard techniques currently used (spontaneous deposition of 210Po onto silver disks measured by alpha spectrometry and beta counting of 210Bi) has allowed to confirm the potentialities of the method and the equipment. The precision of the analyses was ± 5%. Results obtained on two cores from the Thau basin allow us to measure sedimentation rates of 0.166 and 0.238 cm yr−1.