Microplastics ‘abundant’ in remote polar seas

There are similar concentrations of microplastic pollution on the seabed in Antarctica as in the North Atlantic and Mediterranean, scientists have found.

A study, led by Liverpool John Moores University (LJMU), Queen’s University Belfast and the British Antarctic Survey, took samples from depths up to 3.6km in remote parts of the Antarctic Peninsular, South Georgia and the Sandwich Islands.

At least one particle of microplastic for every gram of sediment was found to be residing on the Antarctic seabed, similar to pollution rates other oceanic regions much closer to human activity and habitation.  These are fragments, films, and fibres of the most commonly discarded polymers - polyester, polypropylene, and polystyrene – all often used in packaging.

“This is the first report globally of such a finding which we consider very important in our understanding of the global scale of microplastic pollution,” confirmed Dr Kostas Kiriakoulakis, senior lecturer in environmental science at LJMU.

The research is published today (October 23) in the journal Environmental Science & Technology.

Sediment cores

Samples of the seabed were collected up to 3.6 km in depth by British Antarctic Survey scientist Dr Katrin Linse, who travelled to the Southern Ocean and Antarctica as part of a wider research project.

Analysis of 30 deep-sea sediment cores collected from between 136m and 3633m in depth using infrared spectroscopy found microplastics (<5mm) in 28 of them. The mean quantity of microplastics per gram of sediment was 1.3, 1.09 and 1.04 for the Antarctic Peninsula, South Sandwich Islands, and South Georgia, respectively.

Dr Linse said: “I was interested in the amount of microplastics that Antarctica’s seafloor-inhabiting invertebrates, like clams, snails, worms, shrimps, or brittles stars, are exposed to in one of the Earth’ greatest wilderness.

“We believe this is the first analysis of microplastic pollution in Southern Ocean deep-sea sediments, and it will serve as a baseline for future studies from the surface to the bottom of the ocean.”

Dumping

PhD researcher Mánus Cunningham, at Queen's University, said: “Our research highlights that no matter how remote an ecosystem is, it will still show the artefacts of human influence. We have been dumping plastic into our oceans for roughly 70 years now, so in hindsight this may not be terribly surprising. What is surprising is that the levels of this type of pollution are comparable to what we consider moderately or highly polluted regions of the world’s oceans."

As to why the incidence of plastics is so high in such a remote location an open question. Theories range from ocean currents or the wind, to local activity (e.g. fishing) and possibly some internal biologically mediated mechanisms namely microplastics caught up by life forms and transported to depths.

Sonja Ehlers, of the Federal Institute of Hydrology, Germany, said: “It would be interesting to know the sources of the different microplastic types that we found, and the role that ship traffic or research stations may play in their accumulation.”

The findings, the team hopes, will help future efforts to measure the ecological and environmental damage that might be caused by these plastic fragments, by providing a more "robust measure" of its accumulation in remote parts of the ocean.

Plastics can take hundreds of years to degrade.

The paper - High abundances of microplastic pollution in deep-sea sediments: Evidence from Antarctica and the Southern Ocean is authored by Eoghan M. Cunningham (LJMU & Queen’s), Sonja M. Ehlers (Federal Institute of Hydrology, Koblenz) , Jaimie T. A. Dick, Julia D. Sigwart (both Queen’s), Katrin Linse (British Antarctic Survey), Jon J. Dick, Konstadinos Kiriakoulakis (both LJMU).

IMAGE: Collecting sediment cores in the Southern Ocean. BAS