Unlocking the secrets of the greenhouse gases in the worlds oceans

Three postgraduate research students at the University of Southampton’s Optoelectronics Research Centre (ORC) are embarking on research that could revolutionise our understanding of the impact of greenhouses gases on the world’s oceans.

Kalen Barnfather, George Ong and Sam McQuillan are investigating how to improve the way scientists monitor levels of ocean hydrocarbons, including methane, thousands of metres beneath the waves by using small sensors to be taken to test sites by underwater autonomous vehicles.

Their supervisor is Dr Rand Ismaeel, who holds a research fellowship from the Royal Academy of Engineering. Her interdisciplinary work uses silicon photonics at the nanoscale at ORC and maritime technologies pioneered at the National Oceanography Centre (NOC). The aim is to develop sophisticated marine sensors and send them to inaccessible areas within the deepest oceans to measure the impact of greenhouse gases.

At present marine scientists collect this data with large sensors on oceangoing ships in operations that can cost up to £50,000 per day. As Rand explains, that is completely unsustainable: “As we strive for carbon net-zero by 2030, the impractical nature of these missions is apparent. We need a more practical way to monitor pollutants at various depths, in diverse locations and in different seasons, to obtain a comprehensive view of the ocean's carbon cycle.”

Each of the three PhD researchers is working on different elements of marine gas sensing.

Kalen is developing microfibres and protecting them with a membrane to make them tough enough to survive the most challenging environments: “We build the optical fibres at ORC in our state-of-the-art cleanrooms and test them at NOC to cope with the tremendous pressures they will face at the bottom of the oceans. They have already been successfully tested on pressures equivalent to 3,000 meters.”

Sam is using silicon photonics to increase the sensitivity of the sensor so it can replace the larger versions now in use: “We are developing spectrometers on the sensitive polymer membrane of a sensor that could spot unique identifiers in biological and chemical molecules.”

George is looking at how to use the fastest lasers to turn optical fibres into complex sensors by using mid-infrared wavelengths, while making sure the equipment can cope with extreme conditions underwater.

These diverse projects, spanning microfibres, Silicon Photonics and laser applications, showcase the breadth of research undertaken at the ORC. Rand and her students play a pivotal role, bridging the gap between the ORC and the NOC, leveraging the capabilities of both institutes. Rand explains: “The synergy between the ORC’s cutting-edge facilities and the NOC’s expertise in ocean environments has enabled a powerful collaboration at the intersection of photonics and marine technology.”