Tip of the iceberg: volunteer Nikki Trenholm’s seawater sample is one of thousands collected as part of our Global Microplastics Initiative. West Greenland. Photo: Matt Rutherford.

Even if you never make it to the Arctic, microfibers from your fleece clothing likely will. 

Researchers predict the Arctic Ocean will accumulate the highest concentration of plastic microfibers in the world, according to a new study led by Dr. André Lima and co-authored by Adventure Scientists. The insight came from water samples collected by the organization’s citizen-scientist volunteers around the globe. 

Every time someone launders a fleece jacket or other piece of synthetic-fiber clothing, microscopic fibers of plastic wash into sewer systems, down rivers, and out to sea. These invisible microfibers absorb toxic chemicals such as PCBs and metals that, when ingested by marine animals and carried up through the food web to larger wildlife and people, may cause immune deficiencies, reproductive problems, and other harm.  

Experts have documented microplastic fibers in all of the world’s oceans, yet they are still working to understand where the highest concentrations occur and how those concentrations impact plant and animal life. For this study, scientists turned to data from 1,373 seawater samples collected by Adventure Scientists volunteers. The researchers predicted where microfibers would accumulate based on ocean currents, salinity, temperature, and other metrics. Their results, published in the latest volume of the Journal of Hazardous Materials, point to several key hotspots.

Concentrations are predicted to be highest in waters near Greenland and in the wildlife-rich Hudson Bay, which may average 27,000 microplastic particles in a single cubic meter of water. A powerful ocean current that travels from the South Atlantic along North America’s East Coast is driving much of the flow of microfibers into Arctic seas. 


The Ocean Tramp pauses while volunteers take water samples. Pia Fjord, Tierra del Fuego, Chile. Photo: Laura KO Smith @quixoteexpeditions.

The Antarctic Ocean and Mediterranean Sea are also among waters expected to accumulate large amounts of microfibers, as are several mid-ocean vortexes called gyres. The latter have become known as “garbage patches” because they also accumulate larger pieces of waste circulating through the world’s oceans. 

Many of the hotspots identified are areas where ocean currents and cold, dense water form invisible barriers within the ocean. Once microfibers or other debris enter, they cannot escape and continue to circulate. Eventually, the fibers settle on the ocean floor where they  encounter deep-ocean species

“There was a big question when Adventure Scientists originally completed our microplastics project about why there were higher concentrations in places where there were fewer people and industry–where you’d expect to find the least,” said Michelle Toshack, a co-author on the study. Based on the modeling, the study shows that the global conveyor belt of ocean currents is driving microplastics into ‘dead ends’ in the polar oceans.”


Water samples collected worldwide by Adventure Scientists were used in the study. Tahania Atoll, French Polynesia. Photo: Chris Newley @ SVSilentSun.

Volunteers collected the samples between 2013 and 2017 across the world’s oceans and rivers. To date, Adventure Scientists’ Global Microplastics Initiative remains one of the largest-known microplastics pollution datasets. The open-source data, along with a citizen science toolkit for others seeking to understand microplastics in their own communities, are available here Microplastics.