Dr Joseph Stewart
PhD (Soton.), MESc (Oxon.)
Current positions
Research Fellow
School of Earth Sciences
Contact
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Research interests
I am an isotope geochemist studying the chemistry of marine biogenic carbonates to better understand the chemistry of the seawater in which these organisms lived.
My previous research has involved the taxonomic classification and geochemical measurement of ancient calcified plankton (foraminifera) recovered from deep ocean sediment cores to reconstruct ancient seawater temperatures (e.g. Mg/Ca) and changing patterns of continental weathering (e.g. Nd isotopes)
More recently research efforts have been focused on the refinement and application of boron isotope proxy for seawater pH measured in corals and calcified algae. The aims of this research are (i) to identify suitable coral substrates for use as pH biosensors, (ii) document changes in past ocean pH and (iii) to further our understanding of coral bio-mineralization and the impact of ocean acidification on marine califiers.
Projects and supervisions
Thesis supervisions
Publications
Selected publications
01/10/2020NIST RM 8301 Boron Isotopes in Marine Carbonate (Simulated Coral and Foraminifera Solutions)
Geostandards and Geoanalytical Research
Refining trace metal temperature proxies in cold-water scleractinian and stylasterid corals
Earth and Planetary Science Letters
CO2 storage and release in the deep Southern Ocean on millennial to centennial timescales
Nature
Recent publications
16/12/2023Arctic and Antarctic forcing of ocean interior warming during the last deglaciation
Scientific Reports
Ba/Ca of stylasterid coral skeletons records dissolved seawater barium concentrations
Chemical Geology
Enhanced subglacial discharge from Antarctica during meltwater pulse 1A
Nature Communications
Iodine-to-calcium ratios in deep-sea scleractinian and bamboo corals
Frontiers in Marine Science
Radiocarbon evidence for the stability of polar ocean overturning during the Holocene
Nature Geoscience