Up to 95 per cent of plastic polluting the world’s oceans pours in from just ten rivers, according to new research.
The top 10 rivers – eight of which are in Asia – accounted for so much plastic because of the mismanagement of waste.
About five trillion pounds is floating in the sea, and targeting the major sources – such as the Yangtze and the Ganges – could almost halve it, scientists claim.
Massive amounts of plastic bits that imperil aquatic life are washing into the oceans and even the most pristine waters.
But how it all gets there from inland cities has not been fully understood.
Now a study shows the top 10 rivers – eight of which are in Asia – accounted for 88 to 95 per cent of the total global load because of the mismanagement of waste.
The team calculated halving plastic pollution in these waterways could potentially reduce the total contribution by all rivers by 45 per cent.
Dr Christian Schmidt, a hydrogeologist at Helmholtz-Centre for Environmental Research (UFZ) in Leipzig, Germany, said: ‘A substantial fraction of marine plastic debris originates from land-based sources and rivers potentially act as a major transport pathway for all sizes of plastic debris.’
THE 10 MOST POLLUTING RIVERS
Yangtze East China Sea Asia
Indus Arabian Sea Asia
Yellow River Yellow Sea Asia
Hai He Yellow Sea Asia
Nile Mediterranean Africa
Ganges Bay of Bengal Asia
Pearl River South China Sea Asia
Amur Sea of Okhotsk Asia
Niger Gulf of Guinea Africa
Mekong South China Sea Asia
His team analysed data on debris from 79 sampling sites along 57 rivers – both microplastic particles measuring less than 5 mm and macroplastic above this size.
They said microplastics in particular can damage the health of marine life but cleaning it all up would be impossible. However stemming the tide could help reduce the potential harm.
Dr Schmidt said to do this, researchers need a better understanding of how plastic makes its way into the oceans in the first place.
Rivers which flow from inland areas to the seas are major transporters of plastic debris but the concentration patterns aren’t well known.
The findings could help fill in this knowledge gap.
Dr Schmidt pooled data from dozens of research articles and calculated the amount in rivers was linked to the ‘mismanagement of plastic waste in their watersheds.’
He said: ‘The 10 top-ranked rivers transport 88-95 per cent of the global load into the sea.’
The study follows a recent report that pointed the finger at China, Indonesia, the Philippines, Thailand and Vietnam for spewing out most of the plastic waste that enters the seas.
The Yangtze has been estimated in previous research to dump some 727 million pounds of plastic into the sea each year. The Ganges River in India is responsible for even more – about 1.2 billion pounds.
A combination of the Xi, Dong and Zhujiang Rivers (233 million lbs per year) in China as well as four Indonesian rivers: the Brantas (85 million lbs annually), Solo (71 million pounds per year), Serayu (37 million lbs per year) and Progo (28 million lbs per year), are all large contributors.
Previous research has also suggested two-thirds of plastic comes from the 20 most contaminated rivers. But Dr Schmidt reckons this can be narrowed down even further.
‘The rivers with the highest estimated plastic loads are characterised by high population – for instance the Yangtze with over half a billion people.
‘These rivers are also in countries with a high rate of mismanaged plastic waste (MMPW) production per capita as a result of a not fully implemented municipal waste management including waste collection, dumping and recycling.
‘The data shows large rivers are particular efficient in transporting plastic debris. Large rivers like the Yangtze transport a higher fraction of the MMPW that is generated in their catchments than smaller rivers.
‘These three factors lead to the estimated concentration of most of the plastic load to large rivers with a large population living in their catchment.
‘Countries with high MMPW generation such as China or India could greatly reduce the plastic pollution of rivers by implementing proper waste management.
‘In industrial countries, although they have a well developed waste management infrastrcuture, one way for plastic waste entering the environment is littering.’
Pollution costs more than £6 billion ($7.9 billion) in damage to marine ecosystems and kills an estimated one million sea birds, 100,000 sea mammals and untold numbers of fish.
Dr Schmidt said:
‘Pollution of the marine environment with plastic debris is widely recognised and is of increasing ecological concern because of the chemical persistence of plastics and their mechanical fragmentation to so-called microplastics which can be ingested by even small organisms such as zooplankton.
‘Beyond the long recognised occurrence of plastic debris in the marine environment plastic debris has been more recently detected in freshwater environments and can be found even in pristine, remote locations.’
He added: ‘The high fraction of a few river catchments contributing the vast majority of the total load implies that potential mitigation measures would be highly efficient when applied in the high-load rivers.
‘Reducing plastic loads by 50 per cent in the 10 top-ranked rivers would reduce the total river-based load to the sea by 45 per cent.
‘Our analysis reveals that plastic loads of large rivers disproportionately increase in relationship to the increase of plastic debris available for transport.’
WHO DUMPS THE MOST PLASTIC?
So much plastic is dumped into the sea each year that it would fill five carrier bags for every foot of coastline on the planet, scientists have warned.
More than half of the plastic waste that flows into the oceans comes from just five countries: China, Indonesia, Philippines, Vietnam and Sri Lanka.
The only industrialized western country on the list of top 20 plastic polluters is the United States at No. 20.
The U.S. and Europe are not mismanaging their collected waste, so the plastic trash coming from those countries is due to litter, researchers said.
While China is responsible for 2.4 million tons of plastic that makes its way into the ocean, nearly 28 percent of the world total, the United States contributes just 77,000 tons, which is less than one percent, according to the study published in the journal Science.
James E Windsor, Overpasses News Desk
August 6th, 2018