New Study Finds Most Common Plastic Items Found In Ocean Trash

Despite spending millennia exploring and traversing our planet’s oceans, they continue to hold secrets, both below and above water. While we’ve long known that discarded plastic ends up in large bodies of water, along with numerous studies on its origins, a new study adds insights to the composition and path of ocean garbage.

Published in the journal Nature Sustainability, the study, led by Marine Litter Lab at the University of Cádiz fellow Carmen Morales-Caselles, found that plastic comprises about 80 percent (±18%) of all ocean pollution.

Researchers also discovered that the type of plastic found depended on the type of environment, and for coastal plastic, on the surrounding socio-economic conditions. The prevalence of single-use items was found between the 50th and 30th longitude lines and included much of the continental US and Western Europe.

The study looked at seven distinct environments—riverways, shorelines, nearshore water, open water, riverbeds, nearshore ocean beds, and open water ocean beds—and though the composition and type of items varied by environment, they found that plastic shopping bags were in the top two positions of waste collected. 

The top items found across all environments studied included plastic bags, which made up 14% of all items observed, followed by plastic bottles at 12%. Food containers and cutlery accounted for 9%, as did wrappers, and plastic cups and lids accounted for 6%. In open waters, fishing line, netting, buoys, and other related items were more predominant, accounting for two-thirds of items due to a combination of lighter plastic losing buoyancy as it’s in the water and the predominance of commercial fishing farther away from land. Nonetheless, plastic items like plastic bottles and caps still make it out to open waters, but in smaller concentrations than in other observed environments.

Alarmingly, the study also observed that shorelines serve as generators of microplastic that get distributed beyond the shore. The temperatures and turbulent currents cause larger pieces otherwise unable to float out into the ocean to degrade and slough off smaller bits of plastic.

The researchers recommend focusing on shorelines as locations where micro-plastic can get intercepted and that most plastic pollution found in open waters is from commercial fishing.