Electrochemical sensing of the sea surface microlayer

Dr Phil Warwick, Associate Professor Guy Denuault, UoS; Dr Peter Birkin, UoS

The sea surface microlayer (SML) is the key interface between the oceans and the atmosphere. This is where atmospheric gases enter the ocean, where atmospheric particles deposit, where byproducts of biological activity accumulate, where pollutants concentrate (e.g., microplastics), where radioactive particles deposit and where oil slicks reside etc…. Despite its importance, its physical and chemical properties remain poorly known because it is very difficult to probe and sample accurately. Its thickness is ill defined with reported figures ranging from tens of nm to mm; its viscosity, conductivity, chemical composition, and biological make up are virtually unknown. Even sampling the SML is challenging, let alone monitoring the composition continuously. Hence, there is a strong need to develop new physical methods and instrumentation to probe the SML. The project proposes to develop individually addressable microelectrode arrays to perform in situ measurements at the air-sea water interface. These microelectrodes will be used to perform amperometric measurements (e.g., to assess the local concentration of heavy metals or dissolved oxygen), impedance measurements to determine the local conductivity and potentiometric measurements (e.g., to probe the local pH, for example). 


The work will require the development of arrays of individually addressable microelectrodes. The arrays will be integrated within a floating platform to undertake measurements across the SML. The electrodes will be controlled to perform different analytical methods to assess specific properties of the SML. For example, they will be driven to record voltammograms (i-V curves) and determine the local concentration of heavy metals. Similarly, they will be driven to acquire chronoamperograms (i-t curves) to probe variations in local mass transport properties from which the local viscosity will be investigated. The same electrode arrays will also be subjected to periodic perturbations of their potential.  These frequency sweeps allow dynamic electrochemical impedance spectroscopy to be obtained. This will be undertaken to assess variations in the local conductivity across the SML. 

University of Southampton, Highfield Campus

The INSPIRE DTP programme provides comprehensive personal and professional development training alongside extensive opportunities for students to expand their multi-disciplinary outlook through interactions with a wide network of academic, research and industrial/policy partners. The student will be registered at the University of Southampton and hosted at the School of Chemistry. Specific training will include:


The Southampton Electrochemistry Summer School (a one week intensive CPD course on Electroanalytical methods) organised by GD. https://www.southampton.ac.uk/chemistry/business_partnership/summer_school.page


CHEM6022:    Introduction to Electrochemistry I

CHEM6134:    Introduction to Electrochemistry II

CHEM6135:    Practical Techniques in Electrochemistry

SOES6014:     Introduction to Physical Oceanography

SOES6015:     Introduction to Chemical Oceanography

SOES6073:     Global Ocean Carbon Cycle, Ocean Acidification and Climate


Other modules will be available depending on the first degree of the candidate. For example

SOES6007:     Biogeochemical Cycles in the Earth System

SOES6001:     Contemporary Topics in Ocean and Earth Science

Eligibility & Funding Details: 

Please see https://inspire-dtp.ac.uk/how-apply for details.


Background Reading: 
  1. Sosna, M.; Denuault, G.; Pascal, R. W.; Prien, R. D.; Mowlem, M., Development of a reliable microelectrode dissolved oxygen sensor. Sensors and Actuators B: Chemical 2007, 123 (1), 344-351.
  2. Perdomo Marin, A. C. Applications of Microelectrodes and Scanning Electrochemical Microscopy (SECM) to Complex Environmental Interfaces. PhD, University of Southampton, Southampton, 2019.