Approaches to Water Content Correction and Calibration for µXRF Core Scanning: Comparing X-ray Scattering with Simple Regression of Elemental Concentrations

Abstract

Geochemical evaluation of sediment records traditionally exploits dry mass concentration data; the new generation of scanning XRF devices, however, are generally presented with wet sediment cores. Therefore, conversion of wet core measured XRF data to dry mass concentrations will aid the palaeoenvironmental interpretation, provided the method used is reliable and avoids loss of data quality. Here, using data from a GEOTEK/Olympus DELTA scanning µXRF device (approximately 5 mm resolution), we compare two methods: (1) correction by simple regression, calibrated using dry sediment elemental concentration data measured for a ‘training set’ of subsamples, and (2) a novel technique that corrects for water content estimated using X-ray scattering data obtained during scanning. We show that where sediment water contents are highly variable the regression method fails while water content correction methods can be highly effective. Where water sediment water contents are relatively constant, the elemental regression is as effective and introduces less noise.