The Scottish Government selected us to undertake a study to assess the sources, pathways, fate and environmental impact of microplastics in Scotland, in three environmental contexts: the terrestrial environment including agricultural land, the freshwater environment, and the marine environment. Our findings were recently released in a report.
Initially, we prioritised sources of microplastics for investigation based on the likely scale of their emissions and relevance to Scotland; these included:
- Artificial turf and equestrian surfaces
- Automotive tyre wear
- Synthetic clothing fibres
- Road markings
- Agricultural fertilisers and treated seeds
- Fishing/aquaculture gear (excluding further breakdown of lost or discarded gear)
Modelling the emissions related to each source of microplastic revealed that the highest emissions resulted from wear of automotive tyres, at around 6,000 tonnes per year. This was followed by releases from agricultural products (such as fertiliser additives, seed coatings and controlled-release pesticides), artificial turf and road markings, and the washing of clothing.
A pathways assessment of the microplastic flows from each source, through the environment, identified that the largest accumulations were anticipated to be in soils, with a midpoint estimate of around 6,400 tonnes per year in Scotland. The next largest accumulations were, respectively, in residual waste, surface water and, finally, the air.
Having identified the scale of the problem, we analysed the emission drivers for each source so we could design mitigation measures for implementation, or implementation support, by the Scottish Government and its agencies.
The project allowed us to build on similar work both for the European Commission, on mitigating microplastic risks posed at EU level, and assessing actions that UK businesses could take.
