Mechanical methods to clean up plastic in water bodies may harm aquatic life, study says

Seabin study photo
Items caught by a Seabin cleanup device deployed in the U.K. Photo Credit: University of Plymouth

An international group of scientists warn in a new study that relying on mechanical cleanup devices to clear plastic pollution from oceans and waterways can not only be a distraction from more effective cleanup solutions, but also cause harm to aquatic life.

The new study examines plastic removal technologies (PRTs) such as Seabins, which skim floating debris from the sea surface by pumping water into a bin device, as well as other raking or sieving vehicles. The researchers suggest that PRTs, such as bins that automatically capture sea waste, collect “trivial amounts” of plastic (0.0059 kg per day) but substantial quantities of seaweeds.

“Generally, unselective collection methods like sieving, raking, netting, or conveyors can alter habitats and trap organisms along with plastics, causing injury and bycatch mortality,” the new study states. 

Additionally, regular grooming of areas such as beaches, “can alter these habitats at landscape scale and cause mortality or injury to dune plants and invertebrates,” the study continues.

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The PRT study states that for every four pieces of plastic caught in bin skimming devices, one organism was also captured, 73% of which were dead after two days. 

The study also refers to another research paper that specifically evaluated the performance of Seabin technology. It found that high maintenance costs of the equipment led half of users to abandon the technology.  

The study also suggests that skimming devices miss much of the deeper plastics polluting oceans and waterways.

University of Plymouth professor, Richard Thompson, announced in a statement on the study that countries should not focus on cleanup as a solution to plastic pollution, and that the most cost-effective and efficient way to prevent further pollution is to reduce plastic production and consumption.

“The UN Treaty on Plastic Pollution needs systemic upstream solutions focused on prevention, not symptom management,” says Thompson, who is also the head of the International Marine Litter Research Unit.

The study’s authors warn that plastic production is projected to triple by 2060, while the UN Environment Programme says some eight million tonnes of plastic waste ends up in oceans each year, and forecasts suggest this could double by 2025.

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