Plastic Rivers: An overlooked but essential element of the global plastic problem
We are all familiar with the shocking plastic-related headlines and imagery that has filled our media channels over the past year: sea turtles with straws up their noses, the ‘Great Pacific Garbage Patch’ and fears about plastics in our seafood.
But our plastic problem begins upstream.
Plastic pollution is frequently described as an ‘ocean epidemic’. Although this is the truth, microplastics are much more than an ocean specific issue. Microplastics are everywhere; soil, air and our rivers - but for the most part these are overlooked.
80% of marine plastic comes from freshwater
Around 80% of marine microplastics come from freshwater run-off, meaning there is a whole period where microplastics persist in rivers before they are flushed into the ocean.
It is essential we stop seeing rivers simply as plastic ‘couriers’ and answer the big question: what impact are these plastic particles having on life in freshwater?
What impact is plastic having on freshwater life?
Evidence from the marine environment suggests microplastics may be considered contaminants of emerging concern in freshwater.
It is already known that there is an energetic cost associated with ingestion of microplastics by organisms. That is, plastic consumption effects the very survival of our freshwater wildlife because it changes their inate behaviour.
For example, when plastic particles are consumed, they mimic fullness, so animals stop eating and suffer from poor nutrition.
There is also potential for ecotoxicological harm, as plastics act like sponges, absorbing chemicals in the water. Once eaten, these chemicals can be released from the plastic into whatever has eaten it. And so forth, up the food chain.
How does river plastic affect wild fish?
For salmon and sea trout, we know chemicals in water have a directly negative effect on completion of their life cycles, particularly the phase where they transform to become ready for life at sea.
So it is logical to ask an important question: are these damaging chemicals becoming more available to these fish - and in higher doses - through the ingestion of plastic particles?
New research is being commissioned and investigations are being made into understanding and controlling the freshwater element of plastic pollution.
Wastewater treatment plants (a large input of microplastics that come from domestic and industrial sources) are currently not designed to remove microplastics effectively, but new filtration options are being discussed.
How can we plastic-proof our rivers?
There is huge scope for positive change, with people and businesses being more aware of their plastic footprints than ever before.
From paper straws to reusable cups, every change we make is a win for the water environment. We urge people to remember that this impact extends way beyond marine; in fact, most plastic pollution begins life in our rivers, where it will also be having an impact - one that often seems overlooked.
At S&TC HQ we have gone single-use-plastic free, and would urge others to do the same.
Moving forward, we would like to see action in the form of a monitoring protocol and standard for river microplastics, so watch this space!
Until we fully grasp and measure the problem, we will not be able to effectively control it.
Additionally, only by understanding the dynamics of microplastics in freshwater, will we be able to effectively measure and manage the contribution to our oceans, in turn protecting marine and freshwater life.
---> By Lauren Mattingley, S&TC's Science Office