New studies revealed that the millions of metric tons of plastic debris that flow to the sea every year may come from just 10 rivers.
The study conducted by scientists from the Weihenstephan-Triesdorf University of Applied Science and the Helmholtz Centre for Environmental Research showed that just 10 rivers are to blame for the 88% to 95% of the estimated 4 million metric tons of plastic debris that float into the ocean every year.
6 of the rivers are found in East Asia – the Amur, Hai He, Mekong River, Pearl, Yangtze, and the Yellow River, 2 in South Asia – the Gange Delta and the Indus, and 2 in Africa – the Nile and the Niger.
The research analysed a global compilation of data on plastic debris found in the water column across rivers of a wide range of sizes. It looked into loads of plastic debris, both microplastic and macroplastics, which are generated in the river catchment.
The former refers to particles that are less than 5 mm in size, while the latter refers to particles that are greater than 5 mm in size.
According to research, the debris load is related to mismanaged plastic waste (MMPW) that was used as a predictor to calculate the global plastic debris input from rivers. Although there is limited amount of data due to high uncertainties, scientists were able to quantify plastic loads in rivers by adding other potential predictors, such as hydrological conditions.
In a previous research, 20 rivers were discovered to be the source of the global total of 67% or 1.15 to 2.41 million metric tons of plastic waste that go into the ocean by way of the rivers.
With plastic particles separated by sizes in the new study and larger data set used, a more horrific truth is revealed – only 10 rivers contribute to so much plastic wasted in the ocean.
Because MMPW is a problem, Cosmos Magazine’s Tim Wallace notes that better management of upstream systems is necessary to reduce the significant proportion of plastic debris that is transferred via rivers.
With an equivalent of one plastic-filled garbage truck being dumped into the ocean every minute, it is important to remedy the problem sooner than later. Plastic has a life expectancy of thousands of years and an estimated 700 species of marine wildlife have already ingested plastic.
By 2050, plastic will be present in 99% of seabirds as well.
There is one tangible bright side to the study, however.
Much of the pollution only comes from a few sources. This means proper plastic waste management will have a huge impact.
In fact, according to the authors of the study, a 50% reduction of plastic loads in the top 10-ranked rivers would reduce by 45% the total river-based load that enters the sea.
Knowing where to start in a mission to reduce plastic waste provides a good start. For years, different laws have already been passed to deal with plastic waste, including the Marine Plastic Pollution Research and Control Act (MARPOL) that took effect in the US in 1988. Still, better and more effective efforts are needed to save the oceans from the rivers’ wastes.
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