PARLEY AIR: FROM RIVERS TO THE OCEANS
Rivers are roads for plastic pollution
Nearly half of all plastic that’s ever been made was created in the past 20 years, and at least 8 million metric tons makes its way to the oceans annually. We know where most plastic waste comes from (more on that here), but less about how exactly it reaches the seas from the land. New research looks more closely at the complex pathways and distribution of waste in the environment. Understanding how plastic gets into the oceans is crucial to preventing the harm plastic does to marine life, people and Earth’s climate. Below, we unpack plastic-polluted rivers.
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THE PLASTIC PIPELINE
Scientists are still trying to identify the biggest sources of marine plastic pollution, but it’s clear that rivers play a central role.
A 2017 study estimated that more than a quarter of plastic waste enters the oceans via rivers. And until very recently, scientists believed just a few rivers were responsible for carrying nearly all of the river-borne plastic pollution that ends up in oceans. This was supported by two studies published in 2017 that determined 90 percent of such marine plastic pollution came from 10 to 20 large, long rivers including the planet’s three biggest: the Nile, Amazon and Yangtze.
But in April 2021, European researchers published a new study on the topic. This time, they accounted for terrain, climate and landscape factors that impact the amount of plastic waste that leaks into rivers, and how much is typically filtered out before a river reaches its delta.
The team looked at more than 100,000 rivers and streams from around the world and found that about 32,000 emit plastic waste into the sea. Of these, they estimate that 1,000 rivers, not 10 or 20, carry around 80 percent of riverine macro plastic pollution that ends up in the oceans (though the study didn’t account for microplastics which, by some estimates, make up 11 percent of all marine plastic pollution).
Based on this new data, the world’s largest riverways are still notable polluters, but aren’t the top sources. Small and medium-size rivers that flow through urban areas — like the Klang River that courses through two Malasian cities, Kuala Lumpur and Selangor — were the biggest plastic pathways.
Maybe the starkest example of this was that data showed the Pasig River, which extends just 15.7 miles (25.2 kilometers) across the Philippines, including through the capital city of Manila, is the largest carrier of plastic pollution. This relatively small river bumped China’s 3,915-mile-long (6,300 kilometers) Yangtze River from its previous estimate of the biggest plastic carrier. By the new study’s calculations, the Yangtze ranks 64th.
The probability a river will carry plastic pollution into the ocean depends a lot on the type of land it crosses. Surprisingly, the amount of plastic waste a country contained was not as relevant as its size, coastline, climate and the landscape its rivers flowed through.
Countries with a relatively small surface area compared to the amount of coastline they border are more likely to emit ocean-bound plastics than larger countries with less coastline. The same is true for countries that log a lot of rainfall. That’s because rainfall increases the size, speed and power of a river, meaning it can more easily sweep up and carry waste. So, in equatorial areas like the Caribbean and tropical archipelagos like Indonesia and the Philippines, it’s common that a disproportionate amount of plastic ends up in the oceans compared to landlocked, drier places.
Also, the closer a river is to the coast when plastic bottles, diapers and takeout containers get swept up in waters, the more likely that pollution will end up in the ocean. And urban areas typically generate more plastic pollution and have drainage systems that easily wash this pollution into nearby waterways, so rivers that cut through big cities are also more likely to carry plastic.
Finally, removing fauna, especially mangroves, to make way for real estate removes important natural filters that trap pieces of plastic before it reaches the ocean. By taking all of these factors into account, the scientists reinforced a solution that other experts have long said is the best approach: To stop plastic from polluting oceans, we have to get it out of rivers.
And while 1,000 key rivers might seem less manageable than 20, this number is still equal to just 1 percent of all the world’s rivers. Targeting pollution in a very small portion of the planet’s waterways will make a huge difference — and thanks to this list, we now have a pretty good idea of where we should start.
STOPPING PLASTIC POLLUTION BEFORE IT HITS OCEANS
When it comes to natural filters, mangroves are particularly good at trapping debris like floating plastic pollution. But it comes at a cost. Mangroves adapt to withstand some plastic pollution, which collects in the shrubs’ extensive root systems. But too much of it kills both the coastal swamps and the crabs, molluscs and microbes that live there. A study on mangroves in Java published earlier this year determined that plastic covers as much as half of the mangrove floor in Demak, a town on the country’s northern coast. And how much plastic the swamp was tasked with filtering makes a huge difference. If a tree’s root system was completely buried in plastic, the tree dropped its leaves and suffocated to death. But mangroves that were partially covered in plastic were relatively resilient, the researchers found. To preserve and restore plastic-trapping habitats like mangroves, humans need to create new ways of catching plastic waste in rivers.
Collaborative Parley initiative The Litterboom Project does just that in major rivers across South Africa. The team installs booms that intercept plastic pollution from rivers, creating scalable, replicable, realistic ways of stopping pollution from reaching the oceans.
To start, a pilot Litterboom Project program zeroed-in on five river systems near Durban, a coastal town in eastern South Africa. A video had surfaced showing waves of plastic bottles, styrofoam containers and straws that washed down the Umgeni River and into the Indian Ocean near Durban after days of upstream rain — it was something The Litterboom Project co-founders Bart Fokkens and Cameron Service had witnessed on a regular basis.
The team also took note of how a floating bridge constructed for an event happened to be really good at catching ocean-bound plastic pollution. They later played with the idea of installing a series of pipes that stretch across riverbeds, collecting floating plastic.
At the end of a year-long pilot phase in 2017, the booms had intercepted 30,000lbs of plastic pollution that was headed for the ocean. By 2020, the number had grown to 33,000lbs of plastic every month (read more here).
Eco-innovations like the Litterboom Project are being trialed and implemented around the world to better stem the pathways of pollution, and a first-of-its-kind, intergovernmental regional cooperation is now underway in South Asia, too. The region is now the third largest contributor to plastic waste globally, and that amount is expected to double in the next three decades. But that doesn’t mean it has to.
Last year, eight South Asian nations announced they will adopt the Parley AIR Strategy to fight plastic pollution reaching rivers and seas across South Asia. In a five-year partnership, Parley, the World Bank and The South Asia Cooperative Environment Programme (SACEP) are launching the largest initiative focused on keeping plastic pollution from ending up in South Asian rivers and seas. Working with officials, universities, policy makers and communities in Afghanistan, Bangladesh, Bhutan, India, Maldives, Nepal, Pakistan and Sri Lanka, the Plastic Free Rivers and Seas for South Asia Project aims to reduce plastic waste and develop solutions that prevent it from entering transboundary waterways. The project works by coordinating education, policies, standards, data collection and funding small local grants that support circular plastic economy solutions and harmonize international efforts to mitigate plastic pollution. Follow the progress.
TAKE ACTION
It should go without saying that reducing the amount of plastic in circulation, especially products that are designed to be used only once, is ultimately the best way to keep the pollution out of rivers and oceans. But we can’t do this on our own. Pushing for legislation that reduces plastic waste on a grand scale and pressuring the world’s biggest single-use plastic polluters to change course will eliminate huge amounts of plastic from ever entering the planet in the first place. It’ll also make it easier for consumers to make plastic-free choices. What happens in one part of the world affects the whole planet. Make noise. Spread the word. Hold those in power accountable. Here’s a place to start:
Step 1
Spread the word, let us help. Download the Parley AIR social toolkits here:
Step 2
Fundraise for the Oceans. To end marine plastic pollution for good, solutions are needed at the sources of pollution. Parley works with local partners to implement various infrastructure solutions, such as River Interception projects that provide both technology and education to intercept plastic before it enters the ocean. Learn how to support Parley projects here.
Step 3
Push for change. Look up local ordinances and support legislation in your area that aims to limit the amount of plastic in circulation (like single-use plastic bans or taxes like those in the Maldives, Canada, the U.K., India, China, Zimbabwe, Kenya, Chile, etc.). If you’re based in the U.S, the country that generates more plastic trash than any other nation in the world, you can join the #PlasticFreePresidency movement. There are key ways President Joe Biden can cut back on the amount of plastic pollution the nation generates — and he doesn’t need Congress’ permission to do so. Learn more and take action here.
TAKE ACTION
There’s strength in numbers but it starts with one. Read up, make noise, spread the word and give others the tools to do the same. This is the best way to drive world leaders to adopt policies that will slow climate change and help the oceans stay healthy so they can play their role.
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