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Mechanical Devices Inefficient at Removing Ocean Plastic

Diagram of process to remove plastic from ocean

A new study led by researchers from the International Marine Litter Research Unit at the UK University of Plymouth suggests that while mechanical devices like Seabin do remove plastics and other items of marine litter, the quantities can be comparatively low and they may trap marine organisms. Scientists have been studying the issue of marine microplastics for more than 20 years.

The Seabin device continuously takes in water via a submersible pump that is then filtered, returning clean water to the area while leaving the litter in a catch bag. Hundreds around the world are said to have captured more that 2.5 million kilograms of litter from calm, sheltered environments like marinas, ports and yacht clubs. 

The study found that the equivalent to 58 items a day were collected, mainly comprised of plastic pellets, polystyrene balls and plastic fragments. The Seabin also captured one marine organism for every 3.6 items of litter, or around 13 a day, including sand eels, brown shrimp and crabs. Around 60 percent were found dead.

During the study, five manual trawls were conducted at the same marina using nets from pontoons or vessels which collected an average of 19.3 grams of litter during cleaning periods of up to five minutes. The Seabin only captured the equivalent of 0.0059 grams in the same time. The researchers say that based on their findings, the device was of minimal benefit at this location.

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