Next-Generation Sensors for Tracking Calcium and Magnesium in Marine Ecosystems

Director of Studies: Dr Uwe Balthasar  

2nd Supervisor: Professor Simon Ussher  

Applications are invited for a 3.5 years PhD studentship. The studentship will start on 1 October 2026

Scientific background
Calcium (Ca²⁺) and magnesium (Mg²⁺) concentrations in seawater fundamentally impact marine ecosystems, as organisms have evolved physiologies and carbonate secretion mechanisms specifically adapted to these chemical conditions [1, 2]. Understanding the environmental variability of these ions will help to better predict the impact of ocean warming [1] and acidification on marine calcifying organisms. While historically considered globally stable over ecological time scales, recent global surveys reveal significant variability in coastal waters due to a range of possible factors such as river runoff, coastal upwelling or biological activity [3]. However, critical gaps remain in our understanding of how concentrations fluctuate across tidal to seasonal timescales, as existing data consists primarily of isolated measurements. 

Understanding coastal Ca²⁺ and Mg²⁺ dynamics across ecological timescales is crucial for advancing knowledge of global geochemical cycles and predicting impacts on marine calcifying organisms. Current knowledge remains limited due to inadequate real-time monitoring capabilities. 

This project addresses these limitations by developing innovative screen-printed ion-specific electrodes for continuous, real-time monitoring of Ca²⁺ and Mg²⁺ fluctuations in coastal seawater.

Research methodology
You will be joining our Sensor Technologies Research Group (STRG) to produce and validate screen-printed Ca2+ and Mg2+ electrodes using established protocols [3,4] and our in-house fabrication facilities for screen-printed electronics. Following rigorous laboratory validation, field testing will occur in Plymouth Sound to capture real-time ionic fluctuations over multiple tidal cycles.   

Comprehensive training will cover screen-printing techniques for conductive materials, chemical functionalization processes for electrode-to-sensor conversion, and electrochemical data analysis. Additional training includes electrode characterization using scanning electron microscopy and spectroscopic techniques, plus specialized instruction in Mg/Ca data interpretation and environmental applications.

We seek an engaging individual with strong laboratory and analytical skills and an enthusiasm for applying chemical knowledge to address environmental questions. Prior experience of programming is desirable.

Eichenseer, K., Balthasar, U., et al., 2025. Temperature Effects on the Distribution of Aragonitic and Calcite-Secreting Epifaunal Bivalves. Journal of Biogeography, 52, p. 313–322

Eichenseer, K., Balthasar, U., et al., 2019. Jurassic shift from abiotic to biotic control on marine ecological success. Nature Geoscience, 12, p. 638–642

Lebrato, M., et al., 2020. Global variability in seawater Mg:Ca and Sr:Ca ratios in the modern ocean. PNAS, 117 (36), p. 22281–22292

Yin, T., et al., 2019. An Integrated Screen-Printed Potentiometric Strip for Determination of Ca2+ in Seawater. Journal of The Electrochemical Society, 166 (8), p. B589-B593

Yu, Z., et al., 2023. Application of superhydrophobic Ti3C2 Mxene-based screen-printed ion-selective electrode for determination of Ca2+ concentration. Surfaces and Interfaces, 42 (Part B), article 103500

If your first language is not English, you will need to meet the minimum English requirements for the programme, IELTS Academic score of 6.5 (with no less than 5.5 in each component test area) or equivalent.  

Successful candidates who meet UKRI’s eligibility criteria will be awarded a fully-funded ARIES studentship of fees, maintenance stipend, £20,780 p.a. for 2025/26 (2026/27 rate TBC) and research costs. 

A limited number of ARIES studentships are available to International applicants. Please note however that ARIES funding does not cover additional costs associated with relocation to, and living in, the UK.

NB: The studentship is supported for 3.5 years of the four-year registration period. The subsequent 6 months of registration is a self-funded ‘writing-up’ period. 

ARIES is committed to equality, diversity, widening participation and inclusion in all areas of its operation. We encourage applications from all sections of the community regardless of gender, ethnicity, disability, age, sexual orientation, and transgender status. Projects have been developed with consideration of a safe, inclusive, and appropriate research and fieldwork environment. Academic qualifications are considered alongside non-academic experience, with equal weighting given to experience and potential. 

For further information, please visit www.aries-dtp.ac.uk.

If you wish to discuss this project further informally, please contact Dr Uwe Balthasar

Please see our apply for a postgraduate research programme page for a list of supporting documents to upload with your application. 

For more information on the admissions process generally, please visit our apply for a postgraduate research programme page or contact the Doctoral College .

Shortlisted candidates will be invited for interview after the deadline. We regret that we may not be able to respond to all applications. Applicants who have not received a response within six weeks of the closing date should consider their application has been unsuccessful on this occasion.