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Phosphate defects and apatite inclusions in coral skeletal aragonite revealed by solid-state NMR spectroscopy

Harris E. Mason; Paolo Montagna; Laura Kubista; Malcolm McCulloch; Marco Taviani; Brian L. Phillips

Title:
Phosphate defects and apatite inclusions in coral skeletal aragonite revealed by solid-state NMR spectroscopy
Author(s):
Mason, Harris E.
Montagna, Paolo
Kubista, Laura
McCulloch, Malcolm
Taviani, Marco
Phillips, Brian L.
Date:
Type:
Articles
Department:
Lamont-Doherty Earth Observatory
Volume:
75
Permanent URL:
Book/Journal Title:
Geochimica et Cosmochimica Acta
Abstract:
Recent development of paleo-nutrient proxies based on the phosphorus/calcium (P/Ca) ratio in tropical- and deep-water corals (also known as cold-water corals) require an understanding of the processes by which P is incorporated into the coral skeletal aragonite. Here, we apply single- and double-resonance solid-state nuclear magnetic resonance (NMR) spectroscopy to determine the speciation of P in coral aragonite. The results show that the majority of P occurs as phosphate defects in the aragonite structure, but in many samples a significant fraction of the P occurs also in crystalline hydroxylapatite inclusions. Quantification of the amount of hydroxylapatite indicates that its presence is not related simply to external environmental factors and that it can occur at varying abundances in different parts of the same corallite. Since there is currently no model available to describe the relationship between dissolved inorganic phosphate and its incorporation as apatite inclusions into carbonates, careful screening of samples which contain only phosphate in the aragonite structure or selective microsampling could improve proxy development.
Subject(s):
Geochemistry
Publisher DOI:
http://dx.doi.org/10.1016/j.gca.2011.10.002
Item views:
111
Metadata:
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