The oceans and in particular coastal shelf seas are one of the main sinks of anthropogenic CO2, but the resulting acidification (pH decrease) has detrimental impacts on many marine biota. The development and implementation of affordable and accurate sensors on autonomous platforms to measure carbon-system related parameters such as pH, total alkalinity (ΑΤ), the total dissolved inorganic carbon concentration (Σ(DIC)) and the partial pressure of CO2 (p(CO2)) in shallow and deep waters are therefore a key requirement for future marine science.
This project combines expertise in the Ocean Technology and Engineering Group (OTE) at NOC with the track record of UEA's glider group in pioneering sensor integration into ocean gliders, supported by NEXUSS-partner Cefas as a major stakeholder and user of sustained observations in UK waters.
The contribution of the North Sea to CO2 uptake and export to the deep Atlantic (the shelf sea carbon pump) is a major uncertainty in the climate system and UK carbon budget. Transfer of carbon-enriched water across the northern boundary is recognised as a key factor, but is not well quantified. This project will develop sensors on gliders to provide high-resolution data to begin closing this gap and provide carbon flux estimates.
The student will integrate mature pH sensors developed by OTE into underwater gliders. This will be followed by total dissolved inorganic carbon and total alkalinity sensors as they move from prototype to mature technology with the assistance of the student. After bench-top calibrations and tank-based tests, the performance of the complete package will be characterised in deployments of increasing duration during regular Cefas cruises. Discrete bottle samples will be taken to validate the sensor data, and their temperature, salinity and pressure dependence. This will quantify stability, accuracy, precision, power consumption and the effects of biofouling.
During the latter part of the project, a longer deployment along the major North Sea inflow will measure patterns and variability of Atlantic inflows. Empirical relationships between pH, Σ(DIC), ΑΤ and other glider data (salinity, temperature, optical backscatter, O2, chlorophyll a and CDOM concentrations) will be used to characterise scales of variability in the carbon system. This will inform the design of future large-scale experiments to fully constrain carbon fluxes in a highly dynamic shelf-sea system.
The NEXUSS CDT provides state-of-the-art, highly experiential training in the application and development of cutting-edge Smart and Autonomous Observing Systems for the environmental sciences, alongside comprehensive personal and professional development. There will be extensive opportunities for students to expand their multi-disciplinary outlook through interactions with a wide network of academic, research and industrial / government / policy partners. The student will be registered at the University of East Anglia (UEA), and hosted at UEA and NOC, Southampton. Specific training will include:
Development and use of state-of-the-art chemical sensor techniques, electronics and mechanical engineering design, marine robotics, numerical and computing skills and analysis of large data sets ('Big Data', Unix, Matlab, time series analysis);
Specialist training in oceanographic fieldwork and instrument deployment, safe working practice, piloting and recovery of underwater gliders;
Analytical techniques for precise and accurate measurement of total alkalinity and dissolved inorganic carbon concentrations in seawater;
Theory of the ocean carbonate system;
Attendance of relevant summer schools (e.g. EGO network – Everyone's Gliding Observatories), presentations and international conference and postgraduate fora (e.g. DISCO – 'DISsertations in Chemical Oceanography').
(i) Biddle, L. C., Kaiser, J., Heywood, K. J., Thompson, A. F. and Jenkins, A. (2015) Ocean glider observations of iceberg-enhanced biological production in the northwestern Weddell Sea. Geophysical Research Letters 42: 459-465 10.1002/2014GL062850
(ii) Martz, T. R., Connery, J. G. and Johnson, K. S. (2010) Testing the Honeywell Durafet for seawater pH applications. Limnology and Oceanography: Methods 8: 172-184 10.4319/lom.2010.8.172
(iii) Rérolle, V. M. C., Floquet, C. F. A., Harris, A. J. K., Mowlem, M. C., Bellerby, R. R. G. J. and Achterberg, E. P. (2013) Development of a colorimetric microfluidic pH sensor for autonomous seawater measurements. Analytica Chimica Acta 786: 124-131 10.1016/j.aca.2013.05.008
First degree subjects: Chemistry, Engineering, Oceanography or Marine Science, Physics, Environmental Sciences; or similar.
Minimum entry requirement: Undergraduate degree with a classification of 2:1 (or international equivalent).
Start date: September 2016 Programme: PhD Mode of Study: Full-time Studentship Length: 3 years, 8 months