Wittke, A, Gussone, N, März, C orcid.org/0000-0003-2558-4711 et al. (1 more author) (2020) The effect of extraction techniques on calcium concentrations and isotope ratios of marine pore water. Isotopes in Environmental and Health Studies, 56 (1). pp. 51-68. ISSN 1025-6016
Abstract
Comparing two different techniques applied for the extraction of marine pore water samples from sediments, the well-established whole round (WR) method and the more recent Rhizon method, in terms of their effects on stable calcium isotope ratios in extracted pore waters, we recognize a systematic offset between the two sampling methods. Higher δ44/40Ca values are associated with lower Ca concentrations for the Rhizon sampling technique and lower δ44/40Ca values are associated with higher Ca concentrations for the corresponding WR-derived pore water samples. Models involving Rayleigh fractionation and mixing calculation suggest that the observed offset is most likely caused by a combined process of CaCO3 precipitation and ion exchange taking place during Rhizon sampling-induced CO2 degassing. Changing pressure, extraction time or extraction yield during WR pressing does not lead to a variation in δ44/40Ca, indicating that no Ca isotope fractionation takes place during the sampling of pore water. On the basis of analytical and modelling results, WR samples appear to provide δ44/40Ca values that are more representative of the ‘true’ pore water isotopic composition. While the difference between the sampling techniques is close to the present-day analytical precision of Ca isotope analysis, it may become more relevant with increasing analytical precision in the future.
Metadata
Item Type: | Article |
---|---|
Authors/Creators: |
|
Copyright, Publisher and Additional Information: | © 2019 Informa UK Ltd. trading as Taylor & Francis Group. This is an author produced version of a paper published in Isotopes in Environmental and Health Studies. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | Calcium-40, calcium-44, IODP, isotope fractionation, isotope geochemistry, pore water, Rhizon, whole round |
Dates: |
|
Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Earth Surface Science Institute (ESSI) (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 22 Nov 2019 12:28 |
Last Modified: | 23 Dec 2020 01:38 |
Status: | Published |
Publisher: | Taylor & Francis |
Identification Number: | 10.1080/10256016.2019.1702038 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:153778 |