Occurrence and transport of microplastics in road runoff from a Swedish highway

Research Project, 2023 – 2024

The aim of the project is to increase understanding on the occurrence, characteristics and transport of microplastics in road runoff at highway E18 in Sweden. The objectives are to:
- Design a sampling campaign of stormwater and sediments at Testsite E18;
- Characterize microplastics in highway runoff with respect to occurrence and particle
attributes;
- Evaluate transport of MP particles from road surface to catch basin;
- Provided relevant experimental data will be used at a later stage to develop and validate a model describing the transport of MP from roads, through open stormwater systems and closed sewers, to receiving surface waters.

Characterisation of microplastics will enable source tracking and quantification, which will inform selection and prioritisation of mitigation measures, including preventative measures. Insight on the occurrence of microplastics in the stormwater system will identify the most efficient treatment solutions and where within the (storm)water system these should be incorporated. Both the experimental results and the numerical models are valuable to predict MP spread in similar
environments and to evaluate the efficiency of stormwater treatment and where to apply it.
The research will lead to the following societal benefits and practical implications:
1. Improved understanding of the contribution from road runoff to the MP load in receiving waters will drive changes in legislation, e.g. restrictions on the release of MP from tyres, litter control, and guideline values for acceptable concentrations in stormwater and receiving waters.
2. Improved understanding of the abundance and properties of MP in road runoff will provide recommendations on which analytical and modelling methods should be used to optimally describe MP in water environments.
The project contributes to achieving several national and international environmental objectives:the Swedish national environmental objectives; the UN Sustainable development goals, e.g. Goal 6, Goal
11 and Goal 14; the EU Marine Directive and Water Framework Directive; the WHO’s Guidelines for drinking-water quality and for safe recreational water environments.