Investigating the stoichiometry and binding of trace elements to marine particulate matter


Investigating the stoichiometry and binding of trace elements to marine particulate matter


Project Description


Dr Angela Milne (University of Plymouth, School of Geography, Earth and Earth Sciences) – Contact me

Dr Simon Ussher, University of Plymouth

Dr Martha Gledhill, GEOMAR Helmholtz Centre for Ocean Research Kiel


Project background

Particulate matter (PM) is a key constituent involved in the cycling of elements that support marine life and control ocean productivity as part of the ocean’s ‘biological pump’.  This cycling can impact the distribution and availability of essential trace nutrients to marine organisms, including iron. The availability of iron limits primary production in a third of the world’s oceans, impacting the efficiency of the biological pump so influencing earth’s climate.

Ocean PM consists of organic (humics, exopolymeric-substances) and inorganic material (clays, silicates, hydroxides).  Important information about elemental cycling associated with PM can be garnered from elemental stoichiometry (their ratios) and factors that influence that stoichiometry. However, while there have been investigations relating to the stoichiometries of nitrogen and phosphorus associated with dissolved and particulate matter, the stoichiometries of trace elements are less studied.

The overall aim of this project is to assess trace elemental stoichiometry of PM from varied sources (e.g. open ocean, continental shelf) as well as the binding and/or release of those elements with any associated organic material. This project will provide in-depth understanding of element-particle dynamics for a deeper understanding of trace elemental cycling and spatial productivity.


Using clean-handling techniques, you will supplement existing PM samples by collecting PM from SW rivers and the Celtic Sea.  You will also have the opportunity to participate in a research cruise to the Southern Ocean.  You will subject collected PM to leach and digestion procedures. You will perform controlled incubations (e.g. changes in pH, ionic strength, element additions) to assess the binding and release of elements, and any subsequent element-complexation with organic matter.  Samples to assess impacts on microbial communities will also be gathered to aid interpretation for incubations.


You will receive comprehensive training in clean-handling, both in land-based laboratories and at sea, and advanced analytical techniques which will be required to undertake the experiments and respective analyses.  You will spend time in Germany developing skills to extract, analyse and interpret trace elements bound to organic matter.

Person specification

We are looking for an individual with a degree in Chemistry or Earth, Ocean, or Environmental Science.


  • Wyatt, N. J., Milne, A., Achterberg, E. P., Browning, T. J., Bouman, H. A., Woodward, E. M. S., & M. C. Lohan (2021). Seasonal cycling of zinc and cobalt in the south-eastern Atlantic along the GEOTRACES GA10 section. Biogeosciences 18(14):4265-4280.
  • White, C., Ussher, S. J., Fitzsimons, M. F., Atkinson, S., Woodward, E. M. S., Yang, M. & T. G. Bell (2021). Inorganic nitrogen and phosphorus in Western European aerosol and the significance of dry deposition flux into stratified shelf waters. Atmospheric Environment 261: 118391.
  • Schmidt, K., Birchill, A. J., Atkinson, A., Brewin, R. J. W., Clark, J. R., Hickman, A. E., Johns, D. G., Lohan, M. C., Milne, A., Pardo, S., Smyth, T. J., Tarran, G. A., Widdicombe, C. E., Woodward, E. M. S., & S. J. Ussher (2020). Increasing picocyanobacteria success in shelf waters contributes to long-term food web degradation. Global Change Biology 26 (10): 5574-5587.
  • Gledhill, M., Hollister, A., Seidel, M., Zhu, K., Achterberg, E.P., Dittmar, T., Koschinshy, A. (2022) Trace metal stoichiometry of dissolved organic matter in the Amazon plume. Sci. Adv. 8, eabm2249.
  • E. J. Zakem, N. M. Levine (2019) Systematic variation in marine dissolved organic matter stoichiometry and remineralization ratios as a function of lability. Global Biogeochem. Cycles 33, 1389–1407.

Key Information

  • This project has been shortlisted for funding by the ARIES NERC DTP and will start on 1st October 2023. The closing date for applications is 23:59 on 19th May 2023.
  • Successful candidates who meet UKRI’s eligibility criteria will be awarded a NERC studentship, which covers fees, stipend (£18,622 p.a. for 2023/24) and research funding. Please note that all international awards have been made for our programme for 2023 so we will not be accepting applications from international candidates,
  • ARIES students benefit from bespoke graduate training and ARIES provides £2,500 to every student for access to external training, travel and conferences, on top of all Research Costs associated with the project. Excellent applicants from quantitative disciplines with limited experience in environmental sciences may be considered for an additional 3-month stipend to take advanced-level courses.
  • ARIES is committed to equality, diversity, widening participation and inclusion in all areas of its operation. We encourage enquiries and applications from all sections of the community regardless of gender, ethnicity, disability, age, sexual orientation and transgender status. Academic qualifications are considered alongside non-academic experience, and our recruitment process considers potential with the same weighting as past experience.
  • All ARIES studentships may be undertaken on a part-time or full-time basis, visa requirements notwithstanding
  • For further information, please contact the supervisor. To apply for this Studentship follow the instructions at the bottom of the page or click the 'apply now' link.
  • ARIES is required by our funders to collect Equality and Diversity Information from all of our applicants. The information you provide will be used solely for monitoring and statistical purposes; it will remain confidential, and will be stored on the UEA sharepoint server. Data will not be shared with those involved in making decisions on the award of Studentships, and will have no influence on the success of your application. It will only be shared outside of this group in an anonymised and aggregated form. You will be ask to complete the form by the University to which you apply.

Applications are open

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