Preventing Plastic Pollution

Iwan Jones, Amanda Arnold, John Murphy, Stuart Beckingham, Christelle Pereira.

Overview

Between January 2020 and March 2023, the River Communities group at Queen Mary University of London led the  Preventing Plastic Pollution (PPP)  project, bringing together 18 organisations - including universities, research centres, NGO's, local and national authorities - working across seven pilot catchments in the UK and France.

Funded by the EU INTERREG programme, the project objective was to enhance and protect the coastal and transitional water ecosystems in the Channel area from plastic pollution by utilising a catchment-based approach (CABA).

Partners collaborated across three areas:

  • Research to better understand sources, accumulations, and effects of plastic pollution, following a catchment based approach.
  • Trialling interventions to remove and reduce plastic pollution from the environment.
  • Developing and supporting transformational behaviour amongst communities, schools, businesses, and regulators, to prevent plastic pollution.

This storymap provides a summary of the actions delivered by the River Communities group for the PPP project in the Poole Harbour catchment.

01 / 06

Microplastic sampling

A study to quantify microplastic pollution was undertaken across the project area. In Dorset, the team sampled two main rivers - the Frome and the Piddle - together with tributaries that flow into Poole Harbour.

Samples were gathered twice a year in spring and autumn from 25 sites. The sites were selected based on a broad range of land uses in the river catchment, which included upstream rural sections, locations close to villages, towns, industrial areas, roads and sewage treatments facilities, and transitional waters (estuaries).

 

 

Microplastic sampling

To collect a sample we used a wide mouthed fine mesh net suspended from a rectangular frame supported by buoys on either side. Once positioned in the main flow, the net filters 30cm of surface water for  30 mins, and a propeller situated in the mouth of the net records  the speed of the water passing through. This information helps us to calculate the total volume of water filtered for each sample. The net is then carefully rinsed and any material collected is stored in a glass sample jar until processing in the laboratory is carried out.

Sample preparation:

Larger pieces of organic material such as leaves and algae are carefully rinsed and removed, before a chemical reagent is added to digest the organic matter.

The first stage digestion lasts two hours, then the samples are rinsed, and a different chemical is used for a 24-hour digestion.

Salt is then added to the sample to increase the density of the solution, causing the plastic particles to float and remaining organic and mineral material to sink.

This upper layer of the sample containing plastic particles is carefully poured through a filter resulting in the collection of a clean sample that can undergo analysis.

Sample analysis:

The filtered samples are then sent to the QMUL labs in London for further analysis using a Fourier Transform Infrared Spectroscopy (FTIR) machine to determine the composition of plastic particles in the sample e.g. polyethylene (PE), polypropylene (PP), polyethylene terephthalate (PET), polyvinyl chloride (PVC) and polystyrene (PS) .

Molecular structures of materials absorb different levels of radiation, and so by shining infrared light beams at a plastic particle and recording the spectra emitted, computer software can determine the molecular structure of a particle in a sample by comparing it with a reference library of spectra.

A separate image analysis software is used to determine the number and size of particles within each sample.

These data are then uploaded into a database and the results analysed according to location. By the end of the project (March 2023) the database held over 5000 particle size records of identified microplastic polymers from over 1000 field samples and controls taken at 141 sites across the seven pilot catchments.

Key findings:

The analysis showed that the Poole Harbour Catchment was relatively un-contaminated with microplastics (mean concentration: 0.1 particles per cubic meter).

The highest concentrations were in the three urban streams feeding into Holes Bay . 

Elsewhere in the catchment concentrations were relatively low, except at the headwater site on the River Hooke which is downstream of a small sewage treatment works. 

This map shows average particle concentrations (m -3 ) for each polymer at Poole Harbour catchment sites across sampling occasions.

Microplastic concentrations in the Poole Harbour Catchment tended to be lower than those recorded in the other pilot catchments investigated as part of the Preventing Plastic Pollution project. 

The PPP project facilitated the exchange of best practice knowledge between the different field and laboratory staff to ensure that data collected by the different partners would be comparable.  

Ecological impact

The PPP project conducted a number of detailed studies to better understand microplastic pollution and its effects on freshwater and marine environments.

Here, PhD student Danielle Marchant is using freshwater “mesocosms” at the River Laboratory, to study how microplastics combined with nutrient pollution, affect the structure and functioning of freshwater ecosystems.

Key findings:

  • Ecosystem structure and functioning were not affected after three months of exposure.
  • Conventional and biodegradable microplastics did not differ in their effects.
  • This effect was not modulated by nutrient enrichment nor plastic concentration.
  • Population-level effects of microplastics may not be readily realised at large scales.

Researchers also used the mesocosms to study the impact of biodegradable and conventional microplastics on macroinvertebrate communities.

 Key findings:

  • The effects of microplastic pollution on macroinvertebrate communities are very weak at large-scale settings under semi-natural conditions.
  • Nutrient enrichment can adjust the effect of microplastics pollution on freshwater macroinvertebrate communities.

We hope that this research in combination with research carried out by French partners on marine organisms can provide evidence to support effective interventions, informing future policy and legislation around plastic pollution in fresh and marine waters.

Transferrable catchment model

Project partners developed a catchment model using a Geographic Information System (GIS) with the ambition to create a transferrable, easy to use and effective way of predicting where macroplastic concentrations are likely to be highest.

Each hexagon represents a level of risk of plastic pollution, with the darker areas showing a higher level of risk.

The model relies on data inputs that are open source and available free of charge requiring a minimum of pre-processing and editing.

Litter surveys were conducted to provide "real-world" data that would test the accuracy of the model across the catchment area for each level of risk.

Thankfully, many of the rural areas matched their low-risk classification with only a handful of items of litter collected across the survey area.

We did get our gloves dirty counting and categorising bags of rubbish: these were a sample from a roadside clean conducted by Dorset Council on the A37 between Dorchester and Yeovil.

Around 70% of all waste was plastic and worryingly we found that a lot had weathered and was starting to break down into smaller pieces.

We also worked with  Ellipsis Earth  to trial an approach they utilise to automate litter identification across a survey area through image recognition and machine learning technology.

Image data were gathered by Ellipsis using drones; a potentially useful technique for surveying large, remote and/or inaccessible areas, such as the fringes of Poole Harbour.

An initial seven sites were surveyed around Poole Harbour, selected to represent the land use across the harbour which is a potential repository for litter transported from the rivers Frome, Piddle, Corfe, and Sherford. Each site comprised 1000m x 50m lateral coverage along the coastline adjacent to the water’s edge.

Analysis of the dataset provided a range of insights, for example:

  • Litter breakdowns by proportion, change, weight and environmental impact
  • Distance/density calculations
  • Geographic comparisons by region and land use
  • Performance of bins
  • Brand specific data

Removing and reducing plastic pollution

The team worked in partnership with local communities and organisations to deliver interventions that reduce and remove plastic pollution.

We aimed to trial novel approaches, add value to local initiatives, and maximise opportunities to support research and behavioural change actions within the project.

For example: by encouraging volunteers to complete litter surveys, participants would not only see the benefit of removing litter at clean up events, they would also contribute valuable data on plastic pollution and be able to visualise their contribution through an online citizen science hub.

This approach provides data on sources and accumulations of plastic pollution, creating a powerful evidence base to inform targeted action and support positive change.

Empowering individuals through a litter picking challenge

Litter Free Dorset (LFD) experienced a significant rise in enquiries from individuals wanting to litter pick in 2020, driven by increased awareness of littering following the COVID lockdowns. In response, LFD with the support of the River Communities group, designed a litter picking challenge to provide individuals with the ability to volunteer in their local area at a time that suited them.

Volunteers signed up and selected a challenge to complete within the course of a month, then were sent litter picking equipment, advice on litter picking safely, and PPP litter survey forms. Participants were encouraged to share their success to a virtual Facebook community. The challenge particularly appealed to young people and adults participating with children.

The challenge provided a range of benefits and interest to participants including the:

  • Potential to reduce litter in Dorset.
  • Save wildlife from plastic pollution.
  • Mental health benefits of spending time outdoors.
  • Creation of a sustainable scheme encouraging community cohesion and resilience.
  • Opportunity to engage in a citizen science project (collect data for Preventing Plastic Pollution).

Plastic tree guard reuse and recycling pilot

The UK government has set a target to plant 30,000 hectares of new trees per year across the UK by 2025 as part of its 25-year environment plan. This target was set in response to the urgent need to address climate change and protect and enhance the environment.

Tree planting is helping to offset carbon emmissions, restore habitats, and provide natural protection against flooding. Tree guards offer protection to saplings and can be reused and recycled, but if not removed, over time they will breakdown into microplastics and pollute the environment.

We identified the following challenges with respect to end-of-life disposal of plastic tree guards:

  • Lack of awareness regarding the possibilities to reuse and recycle into new products.
  • Collection facilities are not widely available and without a clear pathway to manage and facilitate removal, most are left in situ, buried or burned.
  • Tree guards are bulky and lightweight, so collection and recycling of small numbers are not worthwhile for a waste collector or manufacturer unless provided in large quantities.

In spring of 2021, QMUL were approached by the Farming & Wildlife Advisory Group SouthWest (FWAG SW) for partnership in running a tree guard recycling pilot. FWAG SW had received partial funding under Network Rail by the Tree Council to offset plastic tree guard use in conjunction with a tree and hedge planting initiative in the Devil’s Brook catchment in Dorset

Our objectives were to provide a drop off point for tree guards to be reused or recycled, and share learnings to support those wishing to offer a similar service.

A pilot recycling scheme with  FWAG SW  was concieved and run over two days in the spring of 2023:

  • 1.2 tonnes were removed from 40.4 hectares (0.4 km2)
  • Of 6 participants, one donated 55% of the tree guards.
  • 90% of tree guards were sent for recycling.

Preparation was time consuming, however the infrastructure and resources can be reused year on year, as well as shared with others, thus significantly reducing operational or start-up costs in the future.

Participants ability to estimate the number and condition of tree guards was a challenge, with some delivering significantly more tree guards than estimated in the registration form.

Key findings:

  • Engage participants with a high turnover of tree guards to ensure sufficient quantities for waste contractor.
  • Operate regularly (e.g. yearly event) to build a network of participants.

Retention nets at stormwater outfalls

We also evaluated the potential to install a retention net over a stormwater outfall drain, situated at Holes Bay in Poole.

The aim was to collect and then categorise waste over a period of time, and then evaluate the effectiveness according to amount of plastic removed and the resources required to install and service the net.

Local stakeholders were consulted on the proposed installation, and feedback provided to address the following scenarios:

  • Flooding caused by a blockage of the net in extreme rainfall events.
  • Entanglement of wildlife (Holes Bay is a designated nature reserve).
  • Lifting and emptying the net in an emergeny or when at capacity.

Ultimately, the installation of a net was not feasible for the following reasons:

  • Permission to install net was not granted from the local authority highways team within a suitable timeframe to allow data gathering within the project delivery period.
  • Accesssing the nets for removal would need heavy machinery (e.g. telehandler), requiring forward planning with an external contractor.
  • The overall cost and on-going resource requirements did not represent good value for money to stakeholders who would be responsible for monitoring and servicing a net in the long term.
01 / 05

Enabling Change

During the course of the project there was a strong emphasis on delivering interventions that influenced behavioural change amongst target groups:

  • Community groups
  • Tourism and leisure service providers
  • Businesses (SME)
  • Educational institutions
  • Regulators and governing bodies

Evaluation surveys designed by environmental psycologists at the University of Plymouth were used to record participants attitudes in relation to plastic pollution: level of awareness; level of concern; willingness to change (through reducing avoidable plastic consumption).

Community engagement activities focussed on opportunities to create a dialogue about plastic pollution and the catchment-based approach used by PPP.

During the first half of the project, presentations and resources were adapted for online delivery. When social distancing restrictions were eased, we participated in a number of public events in the local area.

Example engagement activities:

  • Catchment model demonstration, showing sources and pathways of plastic pollution.
  • Litter survey as part of clean up events.
  • Viewing freshwater macro-invertebrates that come into contact with plastic pollution.

Engagement with businesses was delivered by  Litter Free Dorset  (LFD) following a tender process. LFD encouraged business to be part of a "sustainable business network" and complete a number of actions to achieve an award.

LFD produced several useful resources and video case studies, hosted a business network event, and created an online communications campaign to promote participation in the scheme.

The team worked with schools to inspire the next generation to change behaviour by delivering online presentations (e.g. PiXEL, 11th Young Environmental Scientists  (YES) virtual conference ) and classroom workshops; and funding places for schools in Dorset on the  Rethink Periods  teacher training programme.

Classroom workshops were based around a catchment model demonstration, exploration of freshwater macro-invertebrates, and an open discussion of actions that everyone can take to reduce plastic pollution.

13 schools in the Poole Harbour catchment area completed the Rethink Periods training course, an accredited programme that trains HSE teachers to educate and empower students about plastic free period products.

We sought opportunities to encourage "top-down" change by engaging with regulators and governing bodies on the issue of plastic pollution.

Report for the Environment Agency Chief Scientist Group on  knowledge gaps hindering regulation of microplastic pollution .

Participation in the Forest Plastics Research Group, delivering a stakeholder survey and compiling a report on  current disposal and future recycling opportunities  for plastic tree guards.

Summary report on PPP project findings for the United Nations Association Climate and Oceans Group. 

Visit the  Preventing Plastic Pollution  project website for further information including project guidance documents and resources, or contact  Professor Iwan Jones  at the River Communities Group, Queen Mary University of London.