The pH dependency of the boron isotopic composition of diatom opal (Thalassiosira weissflogii)
The high latitude oceans are key areas of carbon and heat exchange between the atmosphere and the ocean. As such, they are a focus of both modern oceanographic and palaeoclimate research. However, most palaeoclimate proxies that could provide a long-term perspective are based on calcareous organisms...
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ftcopernicus:oai:publications.copernicus.org:bgd76446 2023-05-15T18:25:44+02:00 The pH dependency of the boron isotopic composition of diatom opal (Thalassiosira weissflogii) Donald, Hannah K. Foster, Gavin L. Fröhberg, Nico Swann, George E. A. Poulton, Alex Moore, C. Mark Humphreys, Matthew P. 2019-05-23 application/pdf https://doi.org/10.5194/bg-2019-180 https://www.biogeosciences-discuss.net/bg-2019-180/ eng eng doi:10.5194/bg-2019-180 https://www.biogeosciences-discuss.net/bg-2019-180/ eISSN: 1726-4189 Text 2019 ftcopernicus https://doi.org/10.5194/bg-2019-180 2019-12-24T09:49:11Z The high latitude oceans are key areas of carbon and heat exchange between the atmosphere and the ocean. As such, they are a focus of both modern oceanographic and palaeoclimate research. However, most palaeoclimate proxies that could provide a long-term perspective are based on calcareous organisms, such as foraminifera, that are scarce or entirely absent in deep-sea sediments south of 50° latitude in the Southern Ocean and north of 40° in the North Pacific. As a result, proxies need to be developed for the opal-based organisms (e.g. diatoms) that are found at these high latitudes, and which dominate the biogenic sediments that are recovered from these regions. Here we present a method for the analysis of the boron (B) content and isotopic composition (δ 11 B) of diatom opal. We also apply it for the first time to evaluate the relationship between seawater pH and δ 11 B and B concentration ([B]) in the frustules of the diatom Thalassiosira weissflogii , cultured at a range of p CO2/pH. In agreement with existing data, we find that the [B] of the cultured diatom frustules increases with increasing pH (Mejia et al., 2013). δ 11 B shows a relatively well-defined negative trend with increasing pH; a completely distinct relationship from any other biomineral previously measured. This relationship not only has implications for the magnitude of the isotopic fractionation that occurs during boron incorporation into opal, but also allows us to explore the potential of the boron-based proxies for palaeo-pH and palaeo-CO 2 reconstruction in high latitude marine sediments that have, up until now, eluded study due to the lack of suitable carbonate material. Text Southern Ocean Copernicus Publications: E-Journals Pacific Southern Ocean |
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Open Polar |
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Copernicus Publications: E-Journals |
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ftcopernicus |
language |
English |
description |
The high latitude oceans are key areas of carbon and heat exchange between the atmosphere and the ocean. As such, they are a focus of both modern oceanographic and palaeoclimate research. However, most palaeoclimate proxies that could provide a long-term perspective are based on calcareous organisms, such as foraminifera, that are scarce or entirely absent in deep-sea sediments south of 50° latitude in the Southern Ocean and north of 40° in the North Pacific. As a result, proxies need to be developed for the opal-based organisms (e.g. diatoms) that are found at these high latitudes, and which dominate the biogenic sediments that are recovered from these regions. Here we present a method for the analysis of the boron (B) content and isotopic composition (δ 11 B) of diatom opal. We also apply it for the first time to evaluate the relationship between seawater pH and δ 11 B and B concentration ([B]) in the frustules of the diatom Thalassiosira weissflogii , cultured at a range of p CO2/pH. In agreement with existing data, we find that the [B] of the cultured diatom frustules increases with increasing pH (Mejia et al., 2013). δ 11 B shows a relatively well-defined negative trend with increasing pH; a completely distinct relationship from any other biomineral previously measured. This relationship not only has implications for the magnitude of the isotopic fractionation that occurs during boron incorporation into opal, but also allows us to explore the potential of the boron-based proxies for palaeo-pH and palaeo-CO 2 reconstruction in high latitude marine sediments that have, up until now, eluded study due to the lack of suitable carbonate material. |
format |
Text |
author |
Donald, Hannah K. Foster, Gavin L. Fröhberg, Nico Swann, George E. A. Poulton, Alex Moore, C. Mark Humphreys, Matthew P. |
spellingShingle |
Donald, Hannah K. Foster, Gavin L. Fröhberg, Nico Swann, George E. A. Poulton, Alex Moore, C. Mark Humphreys, Matthew P. The pH dependency of the boron isotopic composition of diatom opal (Thalassiosira weissflogii) |
author_facet |
Donald, Hannah K. Foster, Gavin L. Fröhberg, Nico Swann, George E. A. Poulton, Alex Moore, C. Mark Humphreys, Matthew P. |
author_sort |
Donald, Hannah K. |
title |
The pH dependency of the boron isotopic composition of diatom opal (Thalassiosira weissflogii) |
title_short |
The pH dependency of the boron isotopic composition of diatom opal (Thalassiosira weissflogii) |
title_full |
The pH dependency of the boron isotopic composition of diatom opal (Thalassiosira weissflogii) |
title_fullStr |
The pH dependency of the boron isotopic composition of diatom opal (Thalassiosira weissflogii) |
title_full_unstemmed |
The pH dependency of the boron isotopic composition of diatom opal (Thalassiosira weissflogii) |
title_sort |
ph dependency of the boron isotopic composition of diatom opal (thalassiosira weissflogii) |
publishDate |
2019 |
url |
https://doi.org/10.5194/bg-2019-180 https://www.biogeosciences-discuss.net/bg-2019-180/ |
geographic |
Pacific Southern Ocean |
geographic_facet |
Pacific Southern Ocean |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_source |
eISSN: 1726-4189 |
op_relation |
doi:10.5194/bg-2019-180 https://www.biogeosciences-discuss.net/bg-2019-180/ |
op_doi |
https://doi.org/10.5194/bg-2019-180 |
_version_ |
1766207372154372096 |