The press release from the Imperial College London repeated below is important from the point of view of the distribution of pollutants, however I feel the extent of the study could be broadened to include the original source of oceanic pollution. Plastics and other pollutants are not somehow taken to the coasts and thrown in the ocean, nor are they the result of jettisoning from ships. In fact commercial shipping is the least likely source of oceanic pollution because of the very strictly enforced MARPOL* regulations.
The main source of ocean plastics and pollution is rivers and harbours, particularly recreational harbours, so it would be beneficial for this study to be extended to river systems and to establish the source of the pollutants.
The problem with oceanic pollutants, and the great garbage gyres that have formed in all our oceans is that they are out of sight and therefore out of mind. The individual does not associate any personal responsibility to the problem, it is too far removed from their everyday lives.
So, extending the study to river systems is important from an individual and corporate responsibility perspective. If the source is, as I have stated, primarily rivers then the local authority jurisdictions through which the rivers and all their tributaries flow must bear responsibility for the oceanic pollution. Also the management of harbours, marinas and moorings must take responsibility as well.
There is much talk of enforcing litter laws on our streets so that they look tidy, but enforcement of coastal and river littering is hardly considered. I would like to see water borne waste collection systems placed in rivers and legislation put in place to make local authorities responsible for pollutants that originate within their jurisdiction, or pass through it. Let’s make local authorities, and by that the people that live there, responsible for water borne garbage that enters another jurisdiction. I can see garbage collectors being placed at the point where the local authority boundaries cross a river to minimise liability for pollutants carried downstream.
Let’s extend the studies, like those carried out by the Imperial College London, into the rivers and waterways and couple that with stakeholder contribution from local authorities and the government. The object being to develop effective legislation as well as implementation of systems and enforcement to completely clean up our river and harbour systems.
Do that and we help clean up the ocean.
“Modelling marine surface microplastic transport to assess optimal removal locations”
by Erik van Sebille and Peter Sherman, Imperial College London.
The most efficient way to clean up ocean plastics and avoid harming ecosystems is to place plastic collectors near coasts, according to a new study.
Plastic floating in the oceans is a widespread and increasing problem. Plastics including bags, bottle caps and plastic fibres from synthetic clothes wash out into the oceans from urban rivers, sewers and waste deposits.
Larger plastics are broken down into smaller fragments that can persist for hundreds or even thousands of years, and fragments of all sizes are swallowed by animals and enter the food web, disrupting ecosystems.
One area of open ocean in the North Pacific has an unusually large collection of microscopic plastics, or microplastics, and is known as the Great Pacific garbage patch. The patch is enclosed by ocean currents that concentrate the plastics into an area estimated to be larger than twice the size of the United Kingdom.
The patch has gained international attention, and there is now a project called The Ocean Cleanup that plans to deploy plastic collectors to clean up the region. However, a new analysis by Dr Erik van Sebille and undergraduate physics student Peter Sherman from Imperial College London suggests that targeting the patch is not the most efficient way to clean up the oceans.
Dr van Sebille, from Imperial’s Grantham Institute, and Sherman used a model of ocean plastic movements to determine the best places to deploy plastic collectors to remove the most amount of microplastics, and to prevent the most harm to wildlife and ecosystems. The study is published today in Environmental Research Letters.
They found that placing plastic collectors like those proposed by The Ocean Cleanup project around coasts was more beneficial than placing them all inside the patch. The project proposes a system of floating barriers and platforms to concentrate and collect plastics and remove them.
For a ten-year project between 2015 and 2025, the team found that placing collectors near coasts, particularly around China and the Indonesian islands, would remove 31 per cent of microplastics. With all the collectors in the patch, only 17 per cent would be removed.
“The Great Pacific garbage patch has a huge mass of microplastics, but the largest flow of plastics is actually off the coasts, where it enters the oceans,” said Sherman.
“It makes sense to remove plastics where they first enter the ocean around dense coastal economic and population centres,” added Dr van Sebille. “It also means you can remove the plastics before they have had a chance to do any harm. Plastics in the patch have travelled a long way and potentially already done a lot of harm.”
The pair’s model also looked at areas where microplastics overlapped with phytoplankton – microscopic floating plants that form the basic food of many ocean ecosystems. Many microplastics enter the food web in these areas as microscopic animals accidentally eat them.
Running the same model for areas rich in phytoplankton came up with a similar result: the overlap was reduced by 46 per cent by placing collectors near certain coasts, whereas the overlap was only reduced by 14 per cent by placing the collectors in the patch.
“There is a lot of plastic in the patch, but it’s a relative dead zone for life compared with the richness around the coasts,” said Sherman. A recent analysis by Dr van Sebille and colleagues in Australia showed that more than 90 per cent of seabirds have swallowed plastics, and these birds are also concentrated around coasts where their food is plentiful.
The pair will refine their analysis, but say the results are clear and hope that plastic collecting projects in the future will focus on the coastlines.
“We need to clean up ocean plastics, and ultimately this should be achieved by stopping the source of pollution,” said Sherman. “However, this will not happen overnight, so a temporary solution is needed, and clean-up projects could be it, if they are done well.”
*MARPOL International Convention for the Prevention of Pollution from Ships, 1973 as modified by the Protocol of 1978
Image from Mother Nature Network – Click HERE for information about the garbage gyre
Subscribers – Contact the Editor for more information.