Abstract
X-ray fluorescence (XRF) core scanner elemental count data are useful for high-resolution paleoceanographic studies. However, because several factors, such as changes in physical core properties, significantly affect element count intensities, the appropriate calibration of the count data is required. Besides, the existing approaches for calibration were not widely employed and require rigorous testing based on sediment variety. In this study, we analyzed high-resolution element intensity (cps) using a wet muddy marine sediment piston core that was collected from the northeast Gulf of Alaska and tested several approaches with ratio and log-ratio methods, and the reliability was evaluated by comparison with the concentrations that were measured by WD-XRF and an elemental analyzer. The results show that the lighter elements (Ti and K) exhibited a significantly weak relationship between raw counts measured by ITRAX and concentrations that were measured by the WD-XRF, indicating that some factors artificially influence ITRAX intensity data. The Cl intensity that is expressed as the water content in marine sediment increased significantly in the upper 202 cm by 42% and the top 25 cm by 73% as compared to the down-core (below 202 cm), which deviates the X-ray scattering and element-counts. The calibration of raw data through coherent/incoherent X-ray scattering ratio (CIR) and additive- and centered-log ratio reduces the offsets. The calibration by CIR performed best for Sr, Fe, Mn, Ti, Ca, K, and Br (0.56 < R2 < 0.91), and the correlation with concentration significantly increased for Ti and K of 100% and 56%, respectively. Therefore, the study suggests that the correction of raw counts through CIR is an effective approach for wet marine sediment when core physical properties have greater variability.
Highlights
X-ray fluorescence (XRF) core scanner’s non-destructive, rapid, and automated multifunction technique provides useful, high-resolution geochemical records from sediment cores [1,2]
Because Br and Cl are not elements analyzed by using wavelength dispersive-XRF (WD-XRF), the Br and Cl intensities are, excluded for comparison with WD-XRF measured concentration
We ran the ITRAX X-ray fluorescence core scanner by using a Molybdenum (Mo) X-ray anode tube at a 30 kV voltage and 55 mA current with a 20-s exposure time for the scanning of a wet marine sediment piston core that was collected from the Northeastern Gulf of Alaska continental slope
Summary
X-ray fluorescence (XRF) core scanner’s non-destructive, rapid, and automated multifunction technique provides useful, high-resolution (sub-millimeter scale) geochemical records from sediment cores [1,2]. To correctly interpret the XRF core scanner data, destructive elemental data measurement by inductively coupled plasma mass spectrometry (ICP-MS), conventional wavelength dispersive-XRF (WD-XRF) spectrometer, or energy dispersive-XRF (ED-XRF) spectrometer is still needed. These conventional methods require homogenized dry powder samples that eliminate sample physical variations and heterogeneity. These conventional (ICP-MS, WD-/ED-XRF) techniques are well established and provide reliable datasets, they are low-resolution and discrete, time-consuming, and not cost-effective [1]. Conventional methods require a complex sample preparation technique and a variety of standard and/or standard reference materials for precision and accuracy
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