Micro-XRF Studies of Sediment Cores: A Perspective on Capability and Application in the Environmental Sciences

Abstract

XRF core scanners represent a major innovation in the analysis of cored sediment sequences and have revolutionised palaeoenvironmental research over the last decade. Such scanners provide capability to rapidly and non-destructively record element proxy variations at decadal, annual and even sub-annual scales. Their use, initially by the marine science community, was soon taken up by lake core researchers, particularly after the advent of high-resolution models incorporating x-radiography, particularly suited for analysis of varved sequences. Their impact on the environmental sciences is seen in the exponential rise in research papers published since 2005 involving their use. Although their main application has been in the study of Quaternary marine and lake cores, they have also been used in the analysis of terrestrial hard rock cores in mining applications, analysis of loess cores, speleothems, cores from peat bogs and river banks and cores collected for environmental forensics and pollution studies. Further, an important cohort of papers has addressed interpretation and calibration issues, increasing the robustness of acquired datasets. In this paper we review marine and lacustrine applications of XRF core scanning, together with environmental forensics applications and research into data optimisation and calibration presented in the current volume. We provide synopses of the principal findings and a concise summary of the current work.

Late Oligocene obliquity-paced contourite sedimentation in the Wilkes Land margin of East Antarctica: implications for paleoceanographic and ice sheet configurations

“…feldspars and clays) and biogenic carbonates (e.g. Richter et al, 2006, Foubert and Henriet, 2009, Rothwell and Croudace, 2015. Based on these observations, we interpret that Ca in our sediments is mainly of biogenic origin (CaCO 3 ).…”

A high-resolution pigment and productivity record from the varved Ponte Tresa basin (Lake Lugano, Switzerland) since 1919: insight from an approach that combines hyperspectral imaging and high-performance liquid chromatography

“…The advantage of hyperspectral data is the very high spatial resolution; the disadvantage is that the speciation of the pigments is limited. Although the potential of hyperspectral imaging has been recognized (Croudace and Rothwell 2015), the method is still in its infancy and further applications in different sedimentary environments and for different scientific questions are needed to establish the method.…”

Annually Laminated Lake Sediments—Recent Progress

“…The fundamental advantage of varves is the possibility of establishing precise time scales along sediment cores, which provide a solid geochronological framework and builds an essential element of paleoenvironmental reconstruction. In addition to the calendar-year time control, another advantage of varves is the absence of bioturbation in these natural archives enabling the application of innovative sub-millimeter-scaled scanning techniques for the generation of high-resolution (annual, sub-annual or seasonal) proxy data series (e.g., [2][3][4]). However, the lacustrine environment is prone to influences from a variety of natural and human-related forcing factors, all of which influence lake systems directly (e.g., water temperature, mixing regime, water column oxygenation, biological productivity) and indirectly (e.g., vegetation cover in the catchment area, soil erosion with an influx of minerogenic particles, pollutants and nutrients) with different intensities and at different time intervals.…”