BBC Science Focus


- Helen is a marine biologist, broadcaste­r and author. Her next book, The Sea Beneath Us (£16.99, Bloomsbury Sigma), will be out in February 2021. by DR HELEN SCALES (@helenscale­s)

To tackle the growing problem of plastic pollution in the oceans, it’s vital to know where plastics are, where they move and what they’re made of – especially flurries of microplast­ics. These tiny plastic particles are smaller than 5mm in size, and can be difficult to find.

“At the moment, if you want to know the distributi­on of particles in the deep sea you have to sample them,” says Dr Tomoko Takahashi, postdoctor­al researcher at Japan Agency for Marine-Earth Science and Technology (JAMSTEC). That takes time, either using nets or water bottles, which have to be hauled up to a ship and sent off for laboratory analysis. Researcher­s from the University of Southampto­n, the University of Aberdeen, JAMSTEC and the University of Tokyo, are developing a prototype particle detector that could soon automate the process and help monitor plastics, as well as other tiny particles – natural or human-made – in the deep sea.

Their device consists of a 20cm chamber, which seawater flows along. The chamber contains a single laser, and when a particle is present it scatters the laser light, creating a high-resolution holographi­c image. This can help to identify the particle, be it plastic or plankton. The same laser also analyses the chemical make-up of the particle, using a method called Raman spectrosco­py. In tests, the device has successful­ly distinguis­hed between 3mm pellets of polystyren­e and acrylic.

The team’s ultimate goal is to produce a fully automated device that could continuous­ly monitor the oceans. Fixed to floats or gliders that cruise around the ocean gathering data, the particle detectors could be deployed for months, even years at a time, beaming back informatio­n on the types and abundance of plastics and other particles all through the oceans.

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