Ideas and perspectives : Mineralizing fluid control on foreign elements in biogenic CaCO3 : insights from otoliths
Kekelou, Athina Nkolista (Universitat Autònoma de Barcelona. Institut de Ciència i Tecnologia Ambientals)
Langer, Gerald (Universitat Autònoma de Barcelona. Institut de Ciència i Tecnologia Ambientals)
Ziveri, Patrizia (Universitat Autònoma de Barcelona. Departament de Biologia Animal, de Biologia Vegetal i d'Ecologia)

Date:	2026
Abstract:	The foreign element composition of calcium carbonate (CaCO3) biominerals from marine calcifying organisms leaving a sedimentary record has been used for decades to reconstruct various biogeochemical parameters. Advancing geochemical proxies and understanding their underlying mechanisms is essential for climate reconstructions, environmental research, and investigations of biomineralization processes. Despite considerable success of proxy applications, limited mechanistic understanding still restricts their full potential. The problem is often summarized by the term "vital effect", i. e. foreign element partitioning due to biological activity. The element partitioning from the calcifying fluid into the biomineral, however, is usually described in terms of inorganic precipitation of a mineral from an aqueous solution of inorganic ions. Although this assumption is central to many partitioning models it has not been tested because the calcifying fluid of classic proxy archives such as foraminifera, molluscs, and coccolithophores has not been successfully sampled for element analysis. The calcifying fluid of fish otolith formation (endolymph), by contrast, was sampled and chemically analysed accompanied by corresponding otolith data. However, previous datasets have not been compared to inorganic partitioning coefficients to test this assumption. In this study, we address this gap using published data from four fish species and six elements. Our results indicate that the final stage of otolith foreign element incorporation is influenced by organic matter in the endolymph fluid and therefore cannot be considered purely inorganic. Our conclusion questions a central assumption of many foreign element partitioning models. This does not imply that existing models are questionable, but that they share a common oversimplification. By removing this oversimplification all kinds of different models can be improved. Our study contributes broadly to the understanding of biogenic CaCO3 geochemistry, and it is relevant to the majority of existing models.
Grants:	Agencia Estatal de Investigación PRE2022-102298 Generalitat de Catalunya 2021/SGR-00640 Ministerio de Ciencia e Innovación CEX2019-000940-M Agencia Estatal de Investigación PID2020-113526RB-I00 Agencia Estatal de Investigación PCI2025-163190
Note:	Altres ajuts: AEI-DFG project BONITOS (541693727)
Note:	Unidad de excelencia María de Maeztu CEX2024-001506-M
Rights:	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.
Language:	Anglès
Document:	Article ; recerca ; Versió publicada
Published in:	Biogeosciences, Vol. 23, Num. 8 (April 2026) , p. 2831-2845, ISSN 1726-4189

DOI: 10.5194/bg-23-2831-2026

15 p, 1.6 MB

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Research literature > UAB research groups literature > Research Centres and Groups (research output) > Experimental sciences > Institut de Ciència i Tecnologia Ambientals (ICTA)
Articles > Research articles
Articles > Published articles