Risk CDT – In-situ Speciation of Trace Metals in Marine Systems

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This is a project within the multi-disciplinary EPSRC and ESRC Centre for Doctoral Training (CDT) on Quantification and Management of Risk & Uncertainty in Complex Systems & Environments, within the Institute for Risk and Uncertainty. The studentship is granted for 4 years and includes, in the first year, a Master in Decision Making under Risk & Uncertainty. The project includes extensive collaboration with prime industry to build an optimal basis for employability.

Introduction:
Trace metals are present at relatively low levels in aqueous media, especially when compared to major elements, but they can still be toxic. The standard monitoring procedure of trace metals in aqueous system largely consists of sampling, storage and laboratory analysis. This is inadequate [1] for continuous monitoring because of: 1) a low sampling frequency which cannot assess the natural variability; 2) contamination problems; 3) high sampling costs. The ideal alternative is the development of cost effective sensors that can perform unattended, real-time, fully automated monitoring and can be deployed in situ in watercourses, water treatment plants or on self-powered analytical platforms.

With the latest development in communications, robotics, microtechnology and/or computers, monitoring of our waters is undergoing a fundamental change with the availability of both fixed monitoring stations and movable platforms. There are only a few companies selling on-line monitoring systems for on-site analysis and only two for in-situ (i.e. directly in the water column) systems [2]. These systems are expensive, therefore widespread use for most purposes remains out of reach.

Project Summary:
This project will develop an autonomous sensor system for monitoring the concentration of trace metals for on-site and in-situ application. Copper will be used as the initial target, then development achieved here should be transferable to other elements. The sensor will be electrochemical, placed into a specifically designed flow-through voltammetric cell including a gold wire electrode. A preliminary study has shown that this type of electrode has remarkable analytical capabilities well suited for in-situ analysis [3]. This voltammetric cell will be integrated into an on-line fluidic system for sample treatment (e.g. acidification) allowing measurement of reactive and total concentration as well as self-calibration and self-cleaning procedures. This type of system would be suitable both for in-situ and on-site applications.

On-site and in-situ testing (i.e. directly in the water column) will first take place in large tanks, then in fish tanks (present on-site at the University) for future applications of trace metal monitoring in land-based fish farms and water treatment facilities. In-situ testing of coastal seawater in Liverpool Bay will be attempted by placing the analytical platform on a fixed buoy to measure reactive and total copper. If long term monitoring of copper is successful, results will lead to: 1- better assessment of the natural variations of its concentration on a daily and monthly basis; 2- understanding of the prime drivers of these variations.

The student will benefit for the full support of the mechanical and electronic engineering teams (e.g. fabrication of systems and components) at the Ocean Technology and Engineering Group (OTEG) at NOC Liverpool. Financial support from OTEG Liverpool will be provided to purchase components and materials for the construction of the system. The technology developed during this project is expected to be at technology readiness level 7 (TRL7) by the end of the studentship. Developments achieved in this project will be transferable to a number of other trace metals (e.g. Hg, As), other environments (lakes, groundwater) and onto other platforms (e.g. autonomous underwater vehicles such as a gliders or wave gliders or drifting profilers such as APEX float). The intellectual property developed throughout the course of this project has significant commercial potential and will be exploited to its fullest extent under the guidance of the NOC Enterprise and Research Impact team.

This project is in collaboration with Dr. Kenny in NOC (National Oceanographic Centre) who has strong technological experience in the development of sensors for marine systems. Dr. Salaun is an expert in the use of gold electrodes and Cu detection while Prof. Young and Cossins have strong research interests in sensor development for biological applications. We are looking for a highly motivated PhD student with relevant chemical and/or engineering background who is at ease with experimental work. She/He will be working and trained in the area of marine biogeochemistry, marine technology and analytical chemistry.