The coordination and distribution of B in foraminiferal calcite
Branson, Oscar (University of Cambridge. Department of Earth Sciences)
Kaczmarek, Karina (Advance Light Source)
Redfern, Simon A.T. (University of Cambridge. Department of Earth Sciences)
Misra, Sambuddha (University of Cambridge. Department of Earth Sciences)
Langer, Gerald (University of Cambridge. Department of Earth Sciences)
Tyliszczak, Tolek (Advance Light Source)
Bijma, Jelle (Alfred Wegener Institute Foundation for Polar and Marine Research)
Elderfield, Henry (University of Cambridge. Department of Earth Sciences)

Data:	2015
Resum:	The isotopic ratio and concentration of B in foraminiferal calcite appear to reflect the pH and bicarbonate concentration of seawater. The use of B as a chemical proxy tracer has the potential to transform our understanding of the global carbon cycle, and ocean acidification processes. However, discrepancies between the theory underpinning the B proxies, and mineralogical observations of B coordination in biomineral carbonates call the basis of these proxies into question. Here, we use synchrotron X-ray spectromicroscopy to show that B is hosted solely as trigonal BO3 in the calcite test of Amphistegina lessonii, and that B concentration exhibits banding at the micron length scale. In contrast to previous results, our observation of trigonal B agrees with the predictions of the theoretical mechanism behind B palaeoproxies. These data strengthen the use of B for producing palaeo-pH records. The observation of systematic B heterogeneity, however, highlights the complexity of foraminiferal biomineralisation, implying that B incorporation is modulated by biological or crystal growth processes.
Ajuts:	European Commission 267931
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Matèria:	B/Ca ; Biomineralisation ; Boron ; Foraminifera ; Palaeoproxy ; δB ; δ11B ; SDG 14 - Life Below Water
Publicat a:	Earth and Planetary Science Letters, Vol. 416 (April 2015) , p. 67-72, ISSN 1385-013X

DOI: 10.1016/j.epsl.2015.02.006

6 p, 1.2 MB

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