Boron incorporation in the foraminifer Amphistegina lessonii under a decoupled carbonate chemistry

verfasst von
K. Kaczmarek, G. Langer, G. Nehrke, I. Horn, S. Misra, M. Janse, J. Bijma
Abstract

A number of studies have shown that the boron isotopic composition (δ11B) and the B / Ca ratio of biogenic carbonates (mostly foraminifers) can serve as proxies for two parameters of the ocean's carbonate chemistry, rendering it possible to calculate the entire carbonate system. However, the B incorporation mechanism into marine carbonates is still not fully understood and analyses of field samples show species-specific and hydrographic effects on the B proxies complicating their application. Identifying the carbonate system parameter influencing boron incorporation is difficult due to the co-variation of pH, CO32- and B(OH)4-. To shed light on the question which parameter of the carbonate system is related to the boron incorporation, we performed culture experiments with the benthic symbiont-bearing foraminifer Amphistegina lessonii using a decoupled pH-CO32- chemistry. The determination of the δ11B and B / Ca ratios was performed simultaneously by means of a new in situ technique combining optical emission spectroscopy and laser ablation MC-ICP-MS. The boron isotopic composition in the tests gets heavier with increasing pH and B / Ca increases with increasing B(OH)4- / HCO3- of the culture media. The latter indicates that boron uptake of A. lessonii features a competition between B(OH)4- and HCO3-. Furthermore, the simultaneous determination of B / Ca and δ11B on single specimens allows for assessing the relative variability of these parameters. Among different treatments the B / Ca shows an increasing variability with increasing boron concentration in the test whereas the variability in the isotope distribution is constant.

Organisationseinheit(en)
Institut für Mineralogie
Externe Organisation(en)
Alfred-Wegener-Institut (AWI) Helmholtz-Zentrum für Polar- und Meeresforschung
University of Cambridge
Burgers’ Zoo
Typ
Artikel
Journal
BIOGEOSCIENCES
Band
12
Seiten
1753-1763
Anzahl der Seiten
11
ISSN
1726-4170
Publikationsdatum
18.03.2015
Publikationsstatus
Veröffentlicht
Peer-reviewed
Ja
ASJC Scopus Sachgebiete
Ökologie, Evolution, Verhaltenswissenschaften und Systematik, Erdoberflächenprozesse
Ziele für nachhaltige Entwicklung
SDG 14 – Lebensraum Wasser
Elektronische Version(en)
https://doi.org/10.5194/bg-12-1753-2015 (Zugang: Offen)
https://doi.org/10.5194/bg-12-2469-2015 (Zugang: Offen)