The temporal evolution of long-range atmospheric microplastic deposition

This study investigated the concentration of microplastics (MPs) > 2 µm in multiple ombrotrophic sphagnum peat archives, providing a quantitative analysis of the temporal evolution of global atmospheric MP deposition. From the 1990s to 2020, deposition rates have increased from hundreds or thousands to tens or hundreds of thousands of MPs/m²/day, depending on location. Polyethylene (PE) dominated the composition of identified synthetic polymers, comprising 93.5% of identified MPs (Fig. 1). Notably, 95% of particles measured less than 20 µm in diameter, emphasizing the prevalence of small-sized MPs in atmospheric transport and deposition. Projections estimated a daily terrestrial deposition of 34±23 g of MP per square kilometer in 2023 depending on location, totaling 1.9 million tonnes/year globally. The exponential growth trend aligned closely with the annual plastic production rate and suggest a doubling of today’s MP deposition rate by 2030 (Fig. 2). Even in the improbable scenario of a complete cease in plastic production, atmospheric MP deposition rates are likely to increase in the coming decades due to the large amount of mobile legacy plastics in the environment.