Fate and biological uptake of polystyrene nanoparticles in freshwater wetland ecosystems

Abstract

Little is known about the fate and uptake of nanoplastics (NPs) in natural ecosystems, mainly due to analytical limitations in measuring NPs in complex environmental matrices. Our aim was to quantitatively assess the transport, fate and biological uptake of NPs in freshwater ecosystems by using replicated wetland mesocosms and gold-doped polystyrene nanoparticles. We showed that 97% of the NPs were retained in the wetlands, with most of them found in the sediment of the mesocosm's lake compartment. A small fraction (3%) of the NPs left the system through the outlet. After 10 weeks of exposure, both filter feeders (Daphnia magna) and detritivores (Asellus aquaticus) had taken up NPs, with D. magna showing a 5 times higher uptake than A. aquaticus. Moreover, NPs were detected in macrophyte roots and their leaves, with significantly higher values in the roots. NP distribution was negatively related with distance from the point of addition, a relation observed both for sediments and macrophytes. Both with respect to the experimental set-up and NP concentrations, our study provides novel insights to the understanding of the fate and uptake of NPs, a contaminant of emerging concern, in natural scenarios. In a broader context, our study also provides crucial knowledge for risk assessment and support for decision-makers and ongoing legislative work regarding nanoplastics.