Composition of planktonic foraminifera test-bound organic material and implications for carbon cycle reconstructions

Introduction Foraminiferal shells are extensively used to reconstruct the marine environment in the geological past. The foraminifera test-bound organic material (FBOM), sheltered by the test from potential diagenetic alteration and contamination, has great feasibility to improve our understanding o...

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Bibliographic Details
Published in:Frontiers in Marine Science
Main Authors: Paoloni, Tommaso, Hoogakker, Babette, Navarro Rodriguez, Alba, Pereira, Ryan, McClymont, Erin L., Jovane, Luigi, Magill, Clayton
Format: Article in Journal/Newspaper
Language:unknown
Published: Frontiers Media SA 2023
Subjects:
Ocean Engineering
Water Science and Technology
Aquatic Science
Global and Planetary Change
Oceanography
Fid
Planktonic foraminifera
Online Access:http://dx.doi.org/10.3389/fmars.2023.1237440
https://www.frontiersin.org/articles/10.3389/fmars.2023.1237440/full
Description
Summary:Introduction Foraminiferal shells are extensively used to reconstruct the marine environment in the geological past. The foraminifera test-bound organic material (FBOM), sheltered by the test from potential diagenetic alteration and contamination, has great feasibility to improve our understanding of carbon and nitrogen cycling. The FBOM δ 13 C has been proposed as a proxy for reconstructing past environmental conditions. However, to fully exploit the proxy potential of FBOM, its molecular composition and the influence of the latter on the FBOM δ 13 C need to be assessed. Method Here we use a novel combination of gas chromatography-mass spectrometry, flame ionization detection (GC-MS/FID) and liquid chromatography organic carbon and nitrogen detection (LC-OCD/ OND) analyses to study the FBOM chemical composition. Results Our results indicate that polysaccharides and proteins dominate FBOM, as proposed by earlier studies, with no evidence of detectable lipids (alkyl lipids, trimethylsilyl ethers of fatty alcohols, trimethylsilyl esters of fatty acids and steranes derivatives were targeted). Discussion Previous studies suggested that FBOM δ 13 C may be used to reconstruct past atmospheric CO 2 concentrations. However, our results indicate that the use of FBOM δ 13 C to reconstruct CO 2 carries an approximate uncertainty of ±21 ppm for past atmospheric CO 2 abundance. We suggest that FBOM δ 13 C can be used as a novel proxy to reconstruct particulate organic material (POM) δ 13 C. This is also supported by the recently confirmed minor fractionation between POM and FBOM δ 13 C.

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