Just 10 rivers – eight of them in Asia – may be responsible for dumping almost four million tonnes of plastic into the seas every year.
Calculating with the precision the source and amount of plastic trash in the oceans is difficult; estimates tend to cover wide ranges.
Previous research has found about one-fifth of total ocean plastic trash comes from marine activities – plastic tossed from fishing boats, ships, drilling platforms and so on – with four-fifths from land.
A paper published in the journal Environmental Science and Technology, by scientists from the Helmholtz Centre for Environmental Research and the Weihenstephan-Triesdorf University of Applied Science, both in Germany, calculates that rivers contribute between 410,000 and four million tonnes a year to oceanic plastic debris, with 88 to 95% coming from only 10.
This study calculated 1.15 to 2.41 million tonnes of plastic waste is now entering the ocean every year from rivers; 67% of the global total, they suggested, came from the top 20 polluting rivers.