Two-Thirds Of River Trash Is Plastic (Research)
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The following information is somewhat difficult on an emotional level, but important to consider. It might be difficult because pesky, toxic fossil fuel pollution seems to get into almost everything: air, oceans, soil, food, etc. Plastics typically are made from fossil fuels.
If you read CleanTechnica with any regularity, you may also be familiar with the Great Pacific Garbage Patch, which has something like 1.8 trillion pieces of trash in it. Most of that trash, according to various sources, is plastic. Where does it all come from? From us humans, of course. A lot is moved by precipitation from the sky, which washes it into creeks, streams, rivers, streets, roads, storm drains, and underground systems carrying it into larger bodies of water. The Pacific Garbage Patch is massive, but I wasn’t as aware that our rivers have a great deal of plastic trash as well.
Recent research conducted at the University of California–Santa Barbara found that rivers have far too much plastic in them.
Chase Brewster, a project scientist in UCSB’s Benioff Ocean Science Laboratory and lead author on the paper, answered some questions about the research.
1.95 million metric tons of plastic — the weight of 5.3 Empire State buildings — travels down rivers worldwide every year. How does all this trash enter the rivers?
Trash enters rivers in many ways. Usually, we call trash that ends up in rivers “mismanaged waste.” Littering and illegal dumping create mismanaged waste, as well as leakage from unsanitary landfills — or landfills that do not have proper pollution control. Some river-bound mismanaged waste may originate great distances from rivers and is mobilized across landscapes, through urban drainages, and into waterways by wind and rains. Unofficial dumpsites form when places lack access to waste management services, often adjacent to rivers.
Is all plastic made from petroleum products?
Essentially all plastic products that we interact with on a daily basis are made from fossil fuels.
How could the trash be prevented from entering the rivers?
First, the less plastic we produce, the less plastic there will be to enter rivers. Second, of the plastic we do use, we need to manage it properly so that it does not have the chance to find a river. Waste management infrastructure and access to services is still severely lacking around the world. And, roughly only 10% of plastic is recycled. If we recycle more plastic, we can make less plastic, and there is less to waste to become plastic pollution.
Does most of it wind up in oceans?
That depends. The closer to the ocean it enters the river, the more likely it will get there. Also, some plastic moves differently than others. A floating beverage bottle is more likely to be mobilized a further distance than a tire that sinks. But we don’t actually know exactly how much plastic enters rivers in the first place. But a massive amount — we predicted 1.95 million metric tons every year — enters the oceans from rivers. So it must be more than that, which is a scary thought.
What harm does plastic cause in rivers?
For one, plastic in rivers harms humans, given the adjacency of our communities to and dependence upon rivers. Microplastic in rivers accumulates in food sources, and direct exposure via inhalation and consumption of water leads to direct accumulation in our bodies. Macroplastic in rivers affects our infrastructure and communities by blocking drainages, exacerbating flood risk and damage, and negatively affecting tourism, fisheries, and shipping. And plastic also impacts the river ecosystem and biodiversity via wildlife entanglement, ingestion, and smothering, leakage of chemical additives, and transport of non-native species and pathogens.
What harm does it do in the oceans?
In the ocean, plastic smothers important ecosystems like coral reefs and mangroves. Wildlife is affected via entanglement, ingestion, and smothering. It can transport non-native species and leak chemical additives. As it breaks down into microplastic, it is ingested into the food chain, transporting microplastics to human bodies through seafood. And now, there are quantifiable negative impacts of plastic pollution on tourism industries.
Does the plastic ever decompose completely or does it simply become micro plastic particles?
Plastic continues to break down into smaller and smaller pieces. As microplastic breaks down, it becomes nanoplastic.

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