[MIS12-03] Quantitative micro-XRF scanning spectroscopy of freshwater lake sedimentary sequences based on the X-ray absorption and emission theories
★Invited Papers
Keywords:Transmitted X-ray intensities, Water content calibration, Micro-XRF intensity correction, Element concentration
Nondestructive micro-XRF scanning spectroscopy of marine and lake sedimentary sequences has been provided detailed paleoenvironmental records through element intensity proxy data. However, there are problems with the effects of interstitial pore water on micro-XRF intensities because the XRF intensities are measured directly at the surface of split wet sediment core samples. Several methods for solving this problem have been proposed, but these were limited to mathematical, statistical and empirical approaches except for Kido et al. (2006). Then, Katsuta et al. (2019) developed a new method for correcting XRF data to compensate for the effects of pore water using resin-embedded sediment samples with a scanning X-ray analytical microscope which allows to simultaneously measure the XRF and transmitted X-ray intensities. Simple linear regression between the linear absorption coefficients of the samples and their porosity, based on the Lambert-Beer law, allows calculation of the interstitial pore space and the amount of the pore water with high reproducibility. On the other hand, the micro-XRF intensities of resin-embedded samples were reduced compared with the dry samples. This is because (1) the XRF absorption of resin within sediment and (2) the sediment dilution effect by resin. A micro-XRF correction equation based on the XRF emission theory, which were improved from method of Kido et al. (2006), provides a reasonable explanation for two effects. This poster presentation shows the theory and methods, and its application to sedimentary sequence from freshwater lakes such as Lake Baikal, Lake Ohnuma, etc.