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Trace metal analysis of sediment cores using a novel X-ray fluorescence core scanning method
- Source :
- Quaternary International, Quaternary International, 514, 55. Elsevier Limited
- Publication Year :
- 2019
-
Abstract
- The trace-metal composition of sediments provides important information on (past) environmental conditions, such as bottom water oxygenation, marine productivity, sediment provenance, and pollution. Whereas major and minor elements are often routinely analyzed using X-Ray Fluorescence (XRF) core scanning, analysis of trace metals with the same method is not yet established as a routine procedure. Here, we used a recently developed state-of-the-art XRF detector with a core scanner (Avaatech) to examine the optimal settings for analyzing a suite of trace metals (V, Cr, Ni, Cu, Zn, Mo, and U). Settings were optimized for fast analyses of sediment cores by extensive testing of primary energy settings, filters, and exposure times on two eastern Mediterranean Sea sapropel layers that archive episodes of past sea-floor anoxia. We reveal the following most advantageous (i.e., optimized for analytical accuracy and time efficiency) settings: (1) V, Cr, Ni at 20 kV with aluminum primary beam filter, (2) Cu, Zn, and U at 30 kV with ‘thick’ (125 μm) palladium primary beam filter, and (3) Mo at 50 kV with copper primary beam filter. For these trace elements, generally, ≥30 s of measurement are required for obtaining reliable data. Synthetic mixtures show that matrix effects, which are inherent to XRF analyses, are of particular importance for V. A correction for these matrix effects on V (e.g., using Compton scattering) may be necessary for samples with a large variability in carbonate content. XRF core-scanning measurements on synthetically, laminated sediments show that trace metals with contrasting atomic weights and related XRF penetration depths (V and Mo) can be determined at sub-mm resolution. We show that intensity results from the new XRF detector can be converted into concentrations using multivariate log-ratio calibration, allowing a fast quantitative prediction of sedimentary trace metal content using XRF core scanning.
- Subjects :
- 010506 paleontology
High-resolution geochemistry
Materials science
Paleoclimate
Compton scattering
Mineralogy
chemistry.chemical_element
X-ray fluorescence
Sediment
Sapropel
010502 geochemistry & geophysics
01 natural sciences
Copper
Paleoenvironment
chemistry.chemical_compound
chemistry
Trace metals
Aluminium
Carbonate
Trace metal
XRF core scanning
0105 earth and related environmental sciences
Earth-Surface Processes
Subjects
Details
- ISSN :
- 10406182
- Database :
- OpenAIRE
- Journal :
- Quaternary International, Quaternary International, 514, 55. Elsevier Limited
- Accession number :
- edsair.doi.dedup.....7c72cb8c95c1813facebcfdf24890626