Intercomparison of XRF Core Scanning Results From Seven Labs and Approaches to Practical Calibration

Abstract

X‐ray fluorescence (XRF) scanning of marine sediment has the potential to yield near‐continuous and high‐resolution records of elemental abundances, which are often interpreted as proxies for paleoceanographic processes over different time scales. However, many other variables also affect scanning XRF measurements and convolute the quantitative calibrations of element abundances and comparisons of data from different labs. Extensive interlab comparisons of XRF scanning results and calibrations are essential to resolve ambiguities and to understand the best way to interpret the data produced. For this study, we sent a set of seven marine sediment sections (1.5 m each) to be scanned by seven XRF facilities around the world to compare the outcomes amidst a myriad of factors influencing the results. Results of raw element counts per second (cps) were different between labs, but element ratios were more comparable. Four of the labs also scanned a set of homogenized sediment pellets with compositions determined by inductively coupled plasma‐optical emission spectrometry (ICP‐OES) and ICP‐mass spectrometry (MS) to convert the raw XRF element cps to concentrations in two ways: a linear calibration and a log‐ratio calibration. Although both calibration curves are well fit, the results show that the log‐ratio calibrated data are significantly more comparable between labs than the linearly calibrated data. Smaller‐scale (higher‐resolution) features are often not reproducible between the different scans and should be interpreted with caution. Along with guidance on practical calibrations, our study recommends best practices to increase the quality of information that can be derived from scanning XRF to benefit the field of paleoceanography.

Evaluating Zr/Rb Ratio From XRF Scanning as an Indicator of Grain‐Size Variations of Glaciomarine Sediments in the Southern Ocean

“…In the Zr/Rb ratio records (Figure 2c), the glacial‐interglacial variation is even clearer than in the Rb and Zr records, with higher values during interglacial periods and lower values during glacial periods (including glacial MIS 12). The XRF scanning derived and ICP‐MS derived Zr/Rb records display better consistency than the individual Rb and Zr records, consistent with previous observations of major element counts and count ratios by XRF scanning (Dunlea et al., 2020).…”

“…In recent decades, X‐ray fluorescence (XRF) scanning technology has enabled rapid, nondestructive, and near‐continuous measurements to be made of many chemical elements in sediment cores, not only in the laboratory but also on board ships and in the field (Jansen et al., 1998; Richter et al., 2006; Ziegler et al., 2008). Although results from XRF core scanning (“element counts”) are semi‐quantitative (Q. Chen et al., 2016; Dunlea et al., 2020; Lyle et al., 2012; G. J. Weltje and Tjallingii, 2008; G. Weltje et al., 2015), the technique has been successfully applied to provide high‐resolution geological tracers for multiple sediment components and processes, including siliceous (Jaccard et al., 2010, 2013; Wu et al., 2017) and calcareous productivity (S. Jaccard et al., 2010; Lyle & Backman, 2013), marine organic carbon content (Ziegler et al., 2008), and silicate rock weathering intensity (Tian et al., 2011). In light of the ”grain‐size effect,” this technique also holds the potential to provide useful information on sediment grain‐size composition (Cuven et al., 2010; D. Liu et al., 2019).…”

“…Although results from XRF core scanning ("element counts") are semi-quantitative (Q. Chen et al, 2016;Dunlea et al, 2020;Lyle et al, 2012; G. J. Weltje and Tjallingii, 2008;G.…”

Quaternary environmental changes in tropical Lake Towuti, Indonesia, inferred from end‐member modelling of X‐ray fluorescence core‐scanning data

“…Several approaches to correct for these effects have been suggested (Weltje & Tjallingii, 2008; Löwemark et al ., 2011; Lyle et al ., 2012; Hennekam & de Lange, 2012; Ohlendorf et al ., 2015; Weltje et al , 2015; Chen et al ., 2016). With these corrections, XRF core‐scanning provides a reliable and consistent record of high‐resolution semi‐quantitative geochemical information, which can, for example, be used for palaeoenvironmental reconstructions (Rothwell & Croudace, 2015; Dunlea et al , 2020).…”

Investigation of Adequate Calibration Methods for X-ray Fluorescence Core Scanning Element Count Data: A Case Study of a Marine Sediment Piston Core from the Gulf of Alaska

“…In this study, we used coherent and incoherent X-ray scattering for the calibration of raw ITRAX-XRF CS elements intensities together with other calibration approaches. Although, some calibration methods have been developed in order to improve the accuracy of XRF CS data [4,8,9,12,[17][18][19][20][21]. The accuracy of these methods requires comprehensive evaluation based on sample types and/or sample location or instrument types (Avaatech, ITRAX, Geotek).…”