LA-ICP-MS-derived U-concentrations and microstructural domains within biogenic aragonite of Arctica islandica shell

• Published in: Environmental monitoring and assessment Vol. 187; no. 5; pp. 260 - 10
• Main Authors: Helama, Samuli, Heikkilä, Pasi, Rinne, Katja, Nielsen, Jan Kresten, Nielsen, Jesper Kresten
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.05.2015; Springer Nature B.V
• Subjects: Ablation; Acidification; Animals; Aragonite; Arctica islandica; Atmospheric Protection/Air Quality Control/Air Pollution; Bivalvia; Bivalvia - chemistry; Calcium Carbonate - chemistry; Carbon dioxide; Chemistry; Earth and Environmental Science; Ecology; Ecotoxicology; Emissions; Environment; Environmental Management; Environmental Monitoring; Fossil fuels; Geochronology; Laboratories; Lasers; Marine; Mass spectrometry; Mass spectroscopy; Microstructure; Mollusks; Monitoring/Environmental Analysis; Ocean acidification; Oceans; Scanning electron microscopy; Scientific imaging; Shellfish; Shells; spectroscopy; Spectrum Analysis; Uranium; Uranium - analysis; Variation; Water Pollutants, Radioactive - analysis; Ocean quahog; Aragonite; Shell growth; Uranium; U-series dating
• ISSN: 0167-6369; 1573-2959; 1573-2959
• DOI: 10.1007/s10661-015-4495-5

Understanding of the uranium uptake processes (both in vivo and post-mortem) into the skeletal structures of marine calcifiers is a subject of multi-disciplinary interest. U-concentration changes within the molluscan shell may serve as a paleoceanographic proxy of the pH history. A proxy of this type is needed to track the effects of fossil fuel emissions to ocean acidification. Moreover, attaining reliable U-series dates using shell materials would be a geochronological breakthrough. Picturing the high-resolution changes of U-concentrations in shell profiles is now possible by laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS). Here, we analyzed in situ U-concentration variations in sub-fossilized shells of ocean quahog ( Arctica islandica ), a commonly studied bivalve species in Quaternary geoscience, using LA-ICP-MS. Microstructural details of the shell profiles were achieved by the scanning electron microscopy (SEM). Comparison of the shell aragonite microstructure with the changes in U-concentration revealed that uranium of possibly secondary origin is concentrated into the porous granular layers of the shell. Our results reinforce the hypothesis that U-concentration variations can be linked with microstructural differences within the shell. A combination of LA-ICP-MS and SEM analyses is recommended as an interesting approach for understanding the U-concentration variations in similar materials.