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The University of Southampton
Ocean and Earth Science, National Oceanography Centre Southampton

Research project: Biogeochemical cycling of iron and chromium in the oceans: Insights from stable isotopes

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Many trace metals are essential for phytoplankton growth, but there is ongoing debate about the consequences of global warming on primary productivity because the processes that regulate the supply of these metals are poorly understood. This project is using the stable isotope compositions of iron (Fe) and chromium (Cr) to provide new insight as to the the provenance of metal inputs to the ocean, and the effects of biogeochemical cycling and redox processes.

Trace metals are important micronutrients that regulate primary productivity in some parts of the ocean. As the oceans warm, trace metal distributions are changing, but the effects of this on primary productivity are hard to predict because of ongoing debate on the supply of trace metals.

This project explores new ways of assessing the controls on trace metal distributions in the ocean through the analysis of stable isotopes of iron (Fe) and chromium (Cr). We are using these isotope tools to determine: (i) how metal fluxes from underwater volcanoes (hydrothermal vents) are modified as the vent fluids mix with overlying seawater; (ii) how metal supply from atmospheric dust varies within the North Atlantic Ocean; and (iii) the importance of metal supply from seabed sediments transported across the continental shelf.

We are one of only a handful of labs in the world able to make very precise measurements of metal stable isotopes in low concentration natural samples that are required for this work. This work makes an important contribution to the international GEOTRACES research programme (


Funding dates: Oct 2016 – Mar 2021

Funding provider: The PhD student is supported by a studentship jointly funded by the China Scholarship Council and the University of Southampton. This project is also funded by NERC Grant NE/N010396/1.



Biogeochemical cycling of iron and chromium in the oceans
Sampling of seawater for trace metal analysis from the RRS James Cook
Biogeochemical cycling of iron and chromium in the oceans
Isotope geochemistry facilities at the University of Southampton
Biogeochemical cycling of iron and chromium in the oceans
The RRS James Cook cruise JC156 scientific party

Related research groups

Marine Biogeochemistry
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