April 24, 2018

expert reaction to research on microplastics in Arctic sea ice

A study in Nature Communications suggests that Arctic sea ice is an important temporal sink and means of transport for microplastic.

Dr Pennie Lindeque, lead plastics scientist at Plymouth Marine Laboratory, said:

“While we don’t yet know the full extent of the impact of microplastics on the health of the marine environment or humans, the growing body of evidence suggests microplastic pollution is a contaminant of environmental and economic concern.

“This study provides novel and important information on sea ice as a temporary sink and mode of transportation for microplastics, helping us to better understand the fate of this persistent contaminant. As climate change will accelerate sea ice melting, more microplastics will be released from the sea ice and will enter the marine environment.

“As microplastics can look like prey for marine animals and are small in size they may be eaten by a wide range of species from zooplankton – small animals at the base of the food web – to seabirds and whales, potentially impacting marine ecosystems and the food chain.”

Dr Jason Holt, National Oceanography Centre, Head of Marine Systems Modelling

“Circulation patterns of the NW European Seas and the North East Atlantic means we might expect a large proportion of plastic waste from NW European countries to eventually end up in the Arctic on time scales of a few years. It is therefore vital to understand the transport and fate of plastic waste in the arctic and how it impacts on the marine environment there, and what can be done to reduce this impact “.

Dr Sheldon Bacon, National Oceanography Centre, Head of Marine Physics & Ocean Climate

“Any contaminants entering surface ocean waters from European sources will travel northwards in the warm, north-going surface waters that head into the Nordic Seas and the Arctic Ocean, as part of the Atlantic Meridional Overturning Circulation”.

Dr Jeremy Wilkinson, sea ice physicist at the British Antarctic Survey, said:

“This is a benchmark study, as it is the first to describe the detailed mapping of microplastic particles throughout Arctic sea ice cores from a number of different locations within the Arctic Ocean.

“Microplastic particles were found throughout all cores sampled.  This is an important finding because it means that they were always present in the water under the ice as it was growing, and drifting, within the Arctic Ocean.  Sea ice grows from the freezing of seawater directly onto the bottom of the ice (i.e. it grows vertically downwards), thus it was incorporating microplastic particles as it grew.  It suggests that microplastics are now ubiquitous within the surface waters of the World’s ocean.  Nowhere is immune.

“Scientists can trace the origins of the particles by using models and observations to track the ice floes back in time to see where they originate from.  This could lead to a better understanding of the origins of microplastics in the Arctic, and hence help provide solutions.

“This new research suggests that the regions where sea ice predominantly melts may be a sink for microplastic particles, and hence may find higher concentrations of them in these regions.

“This is a small study, however, and did not look at many ice cores.  For the big picture we need a more comprehensive approach to understand the extent of the problem, but these initial findings are certainly worrying.”

Dr Simon Boxall, Senior Lecturer in Ocean and Earth Science at the University of Southampton, said:

“This study is an interesting reflection on the extent to which plastics (from micro to large scale particles) have covered our globe.

“It is by no means surprising that the sea ice in the Arctic is contaminated with microplastics.  Fifteen years ago we observed and collected extensive plastic debts from Muffin Island – a remote walrus sanctuary to the North of Svalbard – and it was possible to identify this material as having come from countries surrounding the North Atlantic.

“The ocean currents distribute contaminants throughout the ocean basins over time and the Pacific Garbage Patch is quite literally the tip of the iceberg.  Surface waters contain plastic particles as they enter the Arctic from the Atlantic and Pacific as well as rivers flowing into the area.  As the surface layer of the ocean freezes these particles become trapped into the sea ice.  The observations highlighted in the paper from the Alfred Wegener-Instutite show how this material goes from the water into the ice.  Much of the sea ice in the Arctic is, as a result of climate change, less than two years old and so as it remelts it returns the plastics to the surface layers of our oceans.

“The plastic observed in the sea ice is not a new form of contamination – it is contamination in a different format.  If the Arctic were to melt tomorrow the volume of plastic would still be at the same (worrying) level.”

Prof Ton van den Bremer, Royal Academy of Engineering Research Fellow at the University of Oxford, said:

“In this important new study, the authors show how sea ice can act as an important source and sink for micro-plastic. The implications are twofold.

“In addition to currents, waves and wind, floating sea ice must be considered as an important transport mechanism for micro-plastic pollution in the ocean and along the Transpolar drift.

“The study ties together two global environmental problems: plastic pollution of the ocean and climate change, as the melting of the arctic icecap will lead to the release of large additional quantities of micro-plastic. More importantly, the variability of plastic concentrations across ice at different locations and depth identified in the study illustrates how little we still know about the distribution and fate of plastic that ends up in the ocean.”

Dr Miguel Ángel Morales Maqueda, Senior Lecturer in Oceanography at Newcastle University, said:

“These observations are largely in agreement with model results from Alethea Mountford, one of our PhD students, who has shown that buoyant plastics with sources in populated areas of the north Pacific and North Atlantic are expected to accumulated in areas of the Central Arctic such as the Beaufort Sea, the East Siberian Sean and the Barents sea.

“Naturally, these plastics will be entrained in the ice fabric as seawater freezes. Multi-year sea ice (sea ice that survives more than one summer melt season) has residence times in the Arctic of 5-10 years, and so plastics are to be expected to remain trapped in sea ice on comparable timescales.

“The melting of multi-year sea ice exacerbated by climatic change could reasonable lead to the release into the water column of large amounts of plastics stored in the Arctic sea ice cover during the last decades, as pointed out by the authors.”

* ‘Arctic sea ice is an important temporal sink and means of transport for microplastic’ by Ilka Peeken et al. published in Nature Communications on Tuesday 24 April. 

Declared interests

None received.