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Synchrotron X-ray Microdiffraction and Fluorescence Imaging of Mineral and Rock Samples
Published on: June 19, 2018
Manganese speciation in Diplodon chilensis patagonicus shells: a XANES study
A L Soldati1, J Goettlicher, D E Jacob
1Department of Geosciences, and Earth System Science Research Centre, Johannes Gutenberg-University, Mainz, Germany. soldatia@uni-mainz.de
Journal of Synchrotron Radiation
|February 17, 2010
Summary
Manganese speciation in Diplodon chilensis patagonicus shells was investigated using X-ray absorption near-edge spectroscopy (XANES). Results indicate manganese primarily exists as Mn(II), regardless of environmental or biological factors.
Area of Science:
- Geochemistry
- Biogeochemistry
- Spectroscopy
Background:
- Bivalve shells are archives of environmental conditions.
- Understanding metal speciation in shells is crucial for paleoclimate and paleoenvironmental reconstructions.
- Manganese (Mn) incorporation in shells can provide insights into aquatic ecosystems.
Purpose of the Study:
- To determine the oxidation state and speciation of Mn in freshwater bivalve (Diplodon chilensis patagonicus) shells.
- To investigate potential influences of environmental and biological factors on Mn speciation.
- To establish Mn speciation as a reliable proxy in bivalve shells.
Main Methods:
- X-ray absorption near-edge spectroscopy (XANES) at the Mn K-edge.
- In situ analysis of Mn speciation within shell growth increments.
- High-resolution mapping of Mn Kalpha fluorescence distributions.
- Comparison with Mn-bearing reference compounds.
Main Results:
- XANES spectra indicate Mn exists predominantly as Mn(II) in the bivalve shells.
- The pre-edge feature position and intensity align with Mn(II) reference compounds.
- Mn speciation remained consistent across different shell regions and depositional conditions.
- Factors like provenance, age, Mn concentration, and seasonality did not alter Mn speciation.
Conclusions:
- Manganese speciation in Diplodon chilensis patagonicus shells is consistently Mn(II).
- Mn speciation in this species is robust and not significantly affected by environmental or ontogenetic variations.
- This finding supports the potential use of Mn speciation in bivalve shells as a reliable environmental proxy.
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