Donald, Hannah K., Foster, Gavin L., Fröhberg, Nico, Swann, George E. A., Poulton, Alex J., Moore, C. Mark and Humphreys, Matthew P. (2020) The pH dependency of the boron isotopic composition of diatom opal (Thalassiosira weissflogii). Biogeosciences, 17 (10), 2825-2837. (doi:10.5194/bg-17-2825-2020).
Abstract
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∘ S in the Southern Ocean and north of 40∘ N in the North Pacific. As a result, proxies need to be developed for the opal-based organisms (e.g. diatoms) found at these high latitudes, which dominate the biogenic sediments recovered from these regions. Here we present a method for the analysis of the boron (B) content and isotopic composition (δ11B) of diatom opal. We apply it for the first time to evaluate the relationship between seawater pH, δ11B and B concentration ([B]) in the frustules of the diatom Thalassiosira weissflogii, cultured across a range of carbon dioxide partial pressure (pCO2) and pH values. In agreement with existing data, we find that the [B] of the cultured diatom frustules increases with increasing pH (Mejía et al., 2013). δ11B shows a relatively well defined negative trend with increasing pH, completely distinct 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-CO2 reconstruction in high-latitude marine sediments that have, up until now, eluded study due to the lack of suitable carbonate material.
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- Current Faculties > Faculty of Environmental and Life Sciences > School of Ocean and Earth Science > Geochemistry
School of Ocean and Earth Science > Geochemistry - Current Faculties > Faculty of Environmental and Life Sciences > School of Ocean and Earth Science > Marine Biogeochemistry
School of Ocean and Earth Science > Marine Biogeochemistry - Faculties (pre 2018 reorg) > Faculty of Engineering and the Environment (pre 2018 reorg) > Southampton Marine & Maritime Institute (pre 2018 reorg)
- Current Faculties > Faculty of Environmental and Life Sciences > School of Ocean and Earth Science
School of Ocean and Earth Science - Faculties (pre 2018 reorg) > Faculty of Natural and Environmental Sciences (pre 2018 reorg) > Institute for Life Sciences (pre 2018 reorg)
Current Faculties > Faculty of Environmental and Life Sciences > Institute for Life Sciences > Institute for Life Sciences (pre 2018 reorg)
Institute for Life Sciences > Institute for Life Sciences (pre 2018 reorg) - Faculties (pre 2018 reorg) > Faculty of Natural and Environmental Sciences (pre 2018 reorg) > Ocean and Earth Science (pre 2018 reorg)
Current Faculties > Faculty of Environmental and Life Sciences > School of Ocean and Earth Science > Ocean and Earth Science (pre 2018 reorg)
School of Ocean and Earth Science > Ocean and Earth Science (pre 2018 reorg) - Faculties (pre 2018 reorg) > Faculty of Natural and Environmental Sciences (pre 2018 reorg) > National Oceanography Centre (pre 2018 reorg)
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