A group of scientists has concluded that devices installed on the ocean surface to collect plastic waste can only play a ‘very modest’ part in solving the pollution problem. However, river barriers are seen as more effective technology.
A new study suggests high-publicity projects such as Ocean Cleanup would have to be implemented on a huge scale to make any impact on the ‘Pacific garbage patch’. The experts estimate that 200 such devices, running non-stop for 130 years would reduce floating plastic debris by 44 900 tonnes – just over 5% of the estimated global total during that period.
One Ocean Cleanup device has a length of 600 m and is deployed in an area that allows an average flow speed of 14 cm per second leading to a total clearance of 2649 km2 per year per device. ‘This yields a relative fraction of 0.07% of the global surface ocean that can be cleared by one device per year,’ the report concludes.
The authors say: ‘Private initiatives proposing to collect plastic from the sea and rivers have gained widespread attention, especially in the media. However, few of these methods are proven concepts and it remains unclear how effective they are.’
‘The important message of this paper is that we can’t keep polluting the oceans and hoping that technology will tidy up the mess,’ says Dr Jesse F. Abrams, of the University of Exeter. However, he and various fellow scientists believe river barriers could be more effective – although presenting practical difficulties.
As most plastic enters the oceans via rivers, the authors say preventing plastic entering the ocean from rivers, especially the key polluting river, could cut most of the waste predicted over the next three decades.
However, due to the importance of large rivers for global shipping, they say such barriers are unlikely to be installed on a large scale. The report also received input from scientists working at the Leibniz Centre for Tropical Marine Research, the Leibniz Institute for Zoo and Wildlife Research, Jacobs University and non-profit group Making Oceans Plastic Free.
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