Lost at Sea - where are all the tyre particles? (TYRE-LOSS)

In the UK 330 billion road miles are driven every year, generating particles of synthetic rubber as a consequence of friction between the tyre and the road surface. It has been estimated that tyre wear could account for 65% (18,000 tonnes annually) of all microplastics released to UK surface waters. However, these estimates are in stark disagreement with environmental data where polyethylene, polypropylene, polystyrene and PET are the main types of microplastics and on a global scale only around 1% of studies report finding any tyre particles at all. This contradiction is concerning because tyres contain a range of potentially hazardous chemicals which have been shown to cause harm to marine life.

Tyre particles are challenging to identify from environmental samples and this might explain the discrepancies between modelling estimates and actual field sampling. In this proposal, we will use an approach that has been recently trialled by the team and has shown that very substantial quantities of tyre particles are indeed entering the sea via storm water, waste water and from airborne dust.

This project will measure tyre particle concentrations at their points of entry to the marine environment and then describe their subsequent transport in the water column. We will measure concentrations in the water, sediment and marine life at increasing distances from the places where these particles enter the sea and construct and validate mathematical models to describe the dispersal of tyre particles in inshore waters. This information will then be used establish the potential for any associated risks to marine life at environmentally relevant concentrations.

The proposal brings together the Universities of Plymouth, Exeter and Newcastle, together with Plymouth Marine Laboratory and an Advisory Group comprising 14 organisations including policy makers, tyre, automobile, plastics and water industries as well as academia and environmental charities (see letters of support). Our research team includes world-leading experts in microplastics, marine litter, environmental chemistry, coastal dynamics and ecotoxicology who have pioneered the field with numerous collaborative projects, jointly authored papers and awards for their work. Their previous research has had significant, broad impact influencing policy and industry on a global scale to help reduce plastic contamination in the environment.

There has been considerable media attention on plastic pollution in recent years and this has translated into an urgent call for action by the public, policy makers and industry. However, current understanding of the most appropriate actions is less clear and reliable information on the relative importance and associated risks from various sources of microplastic, including tyre particles, is lacking. The outcomes of this research are therefore of critical importance to guide policy and industry intervention. The number of road vehicles is set to double by 2050 leading to increased particle emissions; however, there are interventions that could reduce the rate of tyre particle generation, hence the proposed research is both urgent and timely.

The outcomes of this project will be widely disseminated via a dedicated Work Package on communication and impact, facilitated by an Impact Champion and the Advisory Group that has been specifically assembled for the project.

Knowledge generated through this project will be of direct benefit to government regulators and policy makers as well as industry and the general public.

Current uncertainty and disagreement about the relative importance of various sources of microplastics, and especially the importance of tyre particles is hindering interventions to reduce microplastic pollution. Government members, regulators and policy makers charged with legislation and environmental protection will benefit directly from clear evidence on the sources, quantities and impacts of tyre particles in relation to other forms of microplastic pollution. The proposal is of direct relevance to NERC's Societal Challenges (managing environmental change), the UK Government's 25 year Environment Plan (see Letter of support from Defra CEO Gideon Henderson), the UK Industrial Strategy by linking two key grand challenges, Future of mobility and Clean growth, and Marine Strategy Framework Directive, Descriptor 10: requires that EU member states keep marine litter (including microplastics) at levels that will not cause harm. Our research will also contribute in support of UN Sustainable Development Goal 14 'Conserve and sustainably use the oceans, seas and marine resources for sustainable development', specifically Goal 14.1 that states 'By 2025, prevent and significantly reduce marine pollution of all kinds, in particular from land-based activities, including marine debris'. These goals cannot be reliably addressed without accurate information on the relative importance of microplastic sources, which this proposal seeks to address.

The project will be of direct relevance to industry across the automotive sector, including the design of vehicles, tyres and braking systems as well as those involved in traffic management. This automotive industry are currently challenged with being a major source of microplastic contamination - yet the evidence to underpin this is lacking. Hence the project outcomes will be of direct relevance across the automotive sector who are keen to minimise the impacts of vehicles. In addition the outcomes are of wider relevance to those in the food industry who are concerned about contamination of fish and shellfish by microplastics and those involved in monitoring air and water quality.

To maximise dissemination and interactions with these key stakeholders we have established an Advisory Group for the project comprising: DEFRA; UK Water Industries Research, South West and Wessex Water; Mott MacDonald, the British Tyre and Rubber Manufacturers Association, automotive manufacturers, and Plastics Europe; Eunomia Consulting; waste and circular economy experts, Ellen MacArthur Foundation and NGOs such as the Marine Conservation Society.

The general public includes those interested in conservation of marine life, and who enjoy the marine recreational activity and seafood. Our results will provide enhanced understanding of microplastics - where they go and what effects they have. This will help with subsequent assessment of how safe it is to eat seafood and the potential influence on marine ecosystems. Ultimately such information will help inform personal choices on tyre and vehicle purchase as well as driving style. For example, there are considerable synergies between vehicle wear, efficient fuel use and tyre wear. This is relevant to increasing use of electric vehicles which are considerably heavier and typically have faster acceleration than conventional vehicles.

PDRAs and early career researchers in our consortium will have the opportunity to develop their awareness of, and skills in, science communication and knowledge transfer by; a) participating in educational outreach events run by our organisations and long term collaborator Digital Explorer, such as their 'Oceans Academies' and Skype Classrooms; b) encouraging them to write articles for the popular press and social media; c) attending NERC training on science communication.