Limited Influence of Sediment Grain Size on Elemental XRF Core Scanner Measurements

Abstract

X-ray fluorescence (XRF) scanning of sediment cores allows the rapid acquisition of bulk geochemical data at high resolution. The XRF core scanner data, which are expressed as elemental counts or peak areas, are mainly related to elemental concentrations, but they are also influenced by a series of sediment physical properties that vary with depth, such as bulk density, water content, organic matter content, and grain size. Here, we investigate the influence of grain size on elemental XRF peak areas by comparing ITRAX XRF core scanner measurements to ICP-AES elemental concentration for two sediment cores with variable grain size. Results provide evidence for a limited influence of sediment grain size on XRF peak areas. This influence is negligible for sediment cores with grain-size variations of 10 μm or less. Our data also demonstrate that for cores with large grain-size variations, correcting the peak areas for water content improves the precision of the XRF measurements by a factor of three. This study therefore demonstrates that, for most sediment cores, the precision of data obtained by XRF core scanning is not significantly altered by grain-size variations.