Mechanical devices are increasingly being considered as a potential way to tackle plastic pollution in marine environments.
But a new study suggests that while they remove plastic and other marine debris, the amounts of debris removed can be comparatively small, and they can also trap marine organisms.
The study was led by researchers from the International Marine Litter Research Unit at the University of Plymouth, who have been studying microplastics in the sea for more than two decades.
Their research was conducted in Plymouth (UK) and provides the first formal independent assessment of the performance of a Seabin device.
The units are designed to continuously suck water inside using a submersible pump, which is then filtered and the cleaned water is returned to the environment, leaving the litter in the collection bag.
Hundreds have been installed worldwide and are said to have captured over 2.5 million kg of waste from quiet, sheltered environments such as marinas, harbors and yacht clubs.
This study found that the Plymouth device retained a total of 1,828 items, 0.18 kg of waste, during 750 hours of operation between April and June 2021. This equated to 58 items per day and consisted primarily of plastic pellets and polystyrene balls and plastic splinters.
However, the Seabin also caught one marine organism for every 3.6 pieces of litter, about 13 organisms per day, including species such as sandeels, brown shrimp and crabs. About 60% of these organisms were dead upon collection, and the study shows that some organisms died after entering the device.
During the operation, five hand trawls were carried out with nets from pontoons or ships in the same marina. The manual cleaning collected an average of 19.3g of waste during a cleaning of up to five minutes. In comparison, the Seabin only captured the equivalent of 0.0059 g over a similar period of time.
In the study, the researchers write that, based on their findings, the device was of minimal use in terms of removing marine debris at that particular location.
They also warn that the presence of such devices could also spark techno-optimism, a reliance on technological innovation rather than systemic changes in how we produce, use and dispose of plastics.
Florence Parker-Jurd, Research Associate at the University of Plymouth and lead author of the study, said: “At its current stage of development, this study suggests that manual cleaning of ports, harbors and marinas is more efficient and less expensive. Manual cleanings are selective, and this could reduce any potential risk to marine life. Given the increasing reliance on technological innovation, formal assessments of their efficiency are required, as similar considerations may apply to other types of devices.”
Professor Richard Thompson OBE, Head of the International Marine Litter Research Unit, added: “The UN treaty to end plastic pollution presents an amazing opportunity to start using plastic more responsibly and stop its accumulation in the environment. Ultimately, the best way to achieve this is by preventing the problem at its source rather than eliminating it. However, the contract sets an urgent, ambitious timeline and this could result in investing more in elimination than into longer-term systemic change. This study and others on my team highlight the critical importance of evidence to inform decisions about what type of intervention to invest in as we address this global environmental challenge.”
The full study – Parker-Jurd et al., Evaluating the performance of the ‘Seabin’ – a fixed point Mechanical litter Removal device for protected waters – is published in Marine Pollution Bulletin.
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Florence N.F. Parker-Jurd et al, Evaluation of the Performance of the ‘Seabin’ – A Fixed-Point Mechanical Garbage Removal Device for Sheltered Waters, Marine Pollution Bulletin (2022). DOI: 10.1016/j.marpolbul.2022.114199
Provided by the University of Plymouth
Citation: Study Explores the Potential for Mechanical Devices to Clear the Ocean of Plastics (2022, October 12), retrieved October 12, 2022 from https://phys.org/news/2022-10-explores-potential-mechanical-devices -ocean.html
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