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The results of the RiverWatch: Plastic Pollution pilot study

The pilot study results of RiverWatch: Plastic Pollution are in!

Through this project, volunteers count the number of plastic items they find in a sample area along a waterway. The data submitted can help us to identify the biggest sources of plastic pollution, and potential solutions for reducing it at a national and international level. 

You can join RiverWatch: Plastic Pollution, along with other exciting citizen science projects, by signing up to Earthwatchers.

The results of the pilot study

In 2020, volunteers from Hart Voluntary Action and Central Surrey Voluntary Action carried out 33 pollution surveys. They recorded 243 macroplastic items and 62 non-plastic items – this gives an average of seven plastic items and two non-plastic items per survey.

The most common type of plastic items found were food-related packaging (N=87), followed by smoking-related items (N=55), and plastic bags (N=43). This means that more than 50% of the plastic was related to food packaging (including carrier bags). This largely matches a recent review of EU and UK freshwaters (Winton et al. 2020).

Types of plastic waste found in pilot study transects

Surveys were carried out before and after the UK lockdown in March 2020. On average, pollution levels were similar, with 7.7 plastic items found per site before lockdown and 7.2 plastic items found per site after lockdown.

Of the non-plastic litter items found, most were made of metal, and were food-related waste (in particular drink cans and tin foil wrappings, N=37).

What can we deduce?

Our findings indicate that plastic pollution levels didn’t change significantly during the first COVID-19 lockdown. This contradicts what has been often reported in the press.

But that doesn't mean the lockdown had no impact. Plastic littering may have reduced in some areas as people were not out and about so much, and increased in outdoor recreational spaces because people haven’t been allowed elsewhere.

Indeed, footfall has increased significantly in certain outdoor spaces during lockdowns; a CPRE report in December stated that “…littering has occurred in new ways and different places. The level has fallen dramatically in some places, such as town centres, and rocketed in others, such as parks and the countryside.” (Litter in Lockdown Report, 2020).

The sites with the highest litter abundance were in areas near a busy road junction, downstream of a large park, and either side of a shopping centre. This highlights areas where we should focus efforts to reduce plastic pollution.

The groups who have collected this data now have evidence they can take to local councils to discuss how to tackle the specific problems identified.

Why your data is valuable

This small pilot study has shown that valuable conclusions can be drawn when enough people collect data. Data from your local area can help support you and your community to identify hotspots of plastic pollution, the biggest causes of that pollution, and to help you take action to reduce it.

Things are continually changing as countries move in and out of lockdowns, and this will again affect levels of plastic pollution in our natural environment. The data you send in as restrictions change could help us to quickly identify hotspots where litter is increasing.

Another factor influencing the levels of plastic on riverbanks is flooding and high water flow events.

Floods can transport plastic downstream and deposit it in certain places when flooding subsides. Plastic deposition can also occur when river flow drops and plastic can become entangled in vegetation.

If we can get data throughout the year, before and after such events, we will get vital information on the source of the plastic pollution. We can find out what plastic is transported by the river itself, versus what is littered directly at that location on the riverbank. This understanding of the source of the plastic (ie littering or other sources) can help us to work out solutions to reduce it.

Debbie, our lead researcher, has used the data from the pilot study to create an action planning toolkit to help you to stop plastic pollution in your community. Debbie will host a free webinar about this in the next few months.

Feeling inspired?

We hope that this has inspired you to do a plastic pollution survey. You can join RiverWatch: Plastic Pollution in the “my projects” section of the Earthwatchers website.


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