Fig. 2

Forest trapping function with micro- and nanoplastic turnover in forest soils. Micro- and nanoplastics (MNPs) can reach forest systems via atmospheric deposition. MNPs transported by the atmosphere are intercepted by the forest canopy. Natural processes like leaf litterfall, rainfall and stem flow transport MNPs to the soil surface and directly incorporate them into organic soil horizons. Direct anthropogenic sources like litter or forest management practices further contribute to plastic pollution in organic horizons. MNPs accumulate and age within organic soil layers, leaching or mixing into the mineral soil and are ultimately discharged into the groundwater. Within organic and mineral soil MNPs can be aged by biogeochemical processes. Once incorporated within the forest soils, MNPs are introduced into the natural turnover processes of biomass accumulation, disintegration and plant uptake. MNPs in forest soils likely negatively affect forest soil structure, organisms, and soil water movement and capacity. Plastic particles can release additives from their interior volumes, and can have combined effects with other soil pollutants (e.g., sorption processes) [4, 7]. Furthermore, MNPs can affect soil microbial activity and nutrient availability within organic horizons, causing potential ripple-on effects in the forest system [54]