Recent studies have indicated that microplastics can travel long distances in the atmosphere and that they may be an important source of microplastics in the soil. We wanted to identify the type of microplastics circulating in the atmosphere and how much of an input to our souls could be coming from these atmospheric microplastics, so we have set up a network of samplers to do this, in all of the project partner countries.

Microplastics in the air are passively sampled using a rain gauge (NovaLynx Corporation, CA, USA), and will also be analysed from soils nearby. Vegetation will be allowed to develop naturally on these areas  (5 x 5 m), and this will enable us to evaluate the potential effects of vegetation cover in influencing deposition of microplastics from the atmosphere to the soil.

Left: Rainfall gauge (UK); right: exclusion field sub-plot (China)

The study began in summer 2023 with the aim of all countries collecting data for a minimum of 6 months. Rainfall and soil samples are collected every 2 weeks and the microplastic particles contained within the matrices are separated, counted and polymer type identified. Vegetation cover is assessed by plant height measurements and image analysis of photographs taken from above of four marked 80 x 80 cm sub-plots within the exclusion area, also at two-weekly intervals.

Initial results from the airborne sampling show that the atmosphere is loaded with a high amount of microplastics (ca. 15-20,000 particles/m2/day, in the UK), where rubber and polyamide were found to be the most abundant polymers identified. Additionally, preliminary results from the UK and China revealed that the smallest microplastics were found to be the most abundant, with amounts decreasing as particle size class increased. Data from the soil samples remain to be analysed.