Microplastics found in the world's most remote oceans

In 2018, Curtin University’s Western Australian Organic & Isotope Geochemistry Centre (WA-OIGC) teamed up with legendary solo yachtsman Jon Sanders in a citizen science project to measure microplastics during his 11th solo circumnavigation of the globe. The results of Sanders’ 455-day voyage, which saw him collect seawater samples at 177 locations across 46,100 km, have now been released — and they make for intriguing reading.

As part of the project, approximately 115 L of sea water was pumped per day from an inlet in the hull of Sanders’ yacht, and filtered onto stainless steel woven filters. During stopovers in ports, these filters were couriered to the WA-OIGC laboratories for processing and analysed by Fourier-transform infrared spectroscopy (FTIR). Lead researcher Professor Kliti Grice said this analysis provided the first accurate measure of the presence of microplastics in unique ocean environments, the source of which may include vehicle tyre dust, pellet spills, textiles, building debris, cosmetics and packaging materials.

“The aim of the study was to target areas of the world’s oceans not previously sampled for microplastics and to produce a complete global snapshot of microplastic distribution,” Grice said.

“Our analysis found microplastics were present in the vast majority of the waters sampled by Jon, even in very remote ocean areas of the Southern Hemisphere.”

Grice acknowledged that some areas of ocean, particularly the Pacific, had several consecutive sampling locations not near any major islands where no microplastics were observed. That said, microplastics were found all along the eastern and southern seaboards of Australia, including the Southern Ocean in the Great Australian Bight.

Co-researcher Dr Alan Scarlett said although the analysis found several types of microplastic such as polycarbonate, polyethylene, polypropylene and synthetic rubber used in products such as drink bottles, packaging and tyres, no particular type of plastic dominated.

“The size of particles observed was typically close to the lower size limit defined as a microplastic and were mostly grey/black in colour,” Scarlett said.

“Many fibres collected were too small for us to properly analyse and therefore the numbers reported are likely to be an underestimate of the actual number of microplastics present in the oceans.”

On average, Scarlett said, water sampled during the voyage contained 33 particles per cubic metre of sea water, which is consistent with other studies of remote areas of ocean. Grice added that while there were no ‘hot spots’ of contamination, two sampling stations, approximately 600 km off the coast of Brazil, recorded relatively high numbers of microplastics at about 250 particles per cubic metre of sea water.

“Disturbingly, other studies also suggest there are far greater numbers of microplastics present at a greater depth than sampled during our study,” Scarlett said.

Image credit: ©stock.adobe.com/au/sidorovstock

Please follow us and share on Twitter and Facebook. You can also subscribe for FREE to our weekly newsletters and bimonthly magazine.