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The three-isotope system of oxygen (16O, 17O, 18O) is a powerful tool to study environmental oxidation chemistry and cycling of oxygen-bearing species (e.g., sulfates, nitrates, carbonates, etc.). Despite its evident utility, little work has focused onextending the triple oxygen isotope (Δ’17O) tool to oxygen contained in organic matter (OM). This is largely due to methodological challenges with isolating OM-bound oxygen and preparing it for isotopic analysis. Herein, we report on a newly developed method for high-precision Δ’17O measurements of OM (Δ’17O precision of 0.020‰) and apply this technique to investigate partial photochemical oxidation of Suwannee River natural OM in air-equilibrated aquatic samples. Through this, we reveal that the oxygen isotope evolution of the Suwannee OM supports a model whereby OM partial photo-oxidation proceeds via one or more reactive oxygen intermediates. Our measurements further highlight the potential of triple oxygen isotope analyses on OM-bound oxygen to fingerprint OM oxidation pathways, redox chemistry, and source and synthesis reactions.
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An efficient method for high-precision potassium isotope analysis in carbonate materials
High-precision potassium (K) isotope measurements in marine carbonates allow using this novel geochemical proxy to constrain seawater chemistry through geologic time. However, these measurements are still scarce due to the challenges of low-K contents in carbonates during K ion chromatography, such as insufficient sample purification, non-quantitative yield, and high accumulative blank. Here we optimize a dual-column K purification method that addresses these challenges, achieving a satisfactory K separation using 100–150 mg carbonates for routine high-precision K isotope analysis on the Sapphire™ MC-ICP-MS. We then report K isotope compositions in multiple certified reference materials, including limestone, dolostone, coral, and basalt for future inter-laboratory comparisons. The optimized K purification method provides great potential for future K isotope studies of marine carbonates.
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- Award ID(s):
- 1848153
- PAR ID:
- 10389594
- Date Published:
- Journal Name:
- Journal of Analytical Atomic Spectrometry
- Volume:
- 37
- Issue:
- 11
- ISSN:
- 0267-9477
- Page Range / eLocation ID:
- 2410 to 2419
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1039/d2ja00170e
