Plastic particles adsorb to the roots of freshwater vascular plant Spirodela polyrhiza but do not impair growth

Here we investigated the impact of nano- and microplastics on the freshwater duckweed species Spirodela polyrhiza, a vascular plant. S. polyrhiza was exposed for 120h to concentrations ranging from 102 to 106 particles·mL-1. We assessed impacts on growth and chlorophyll production, and explored adsorption and absorption by way of confocal microscopy. For both nano- and micronized particles no concentration-dependent impacts on growth were found (expressed as fresh weight, frond and root sizes). In addition, chlorophyll contents were not significantly impacted. Confocal microscopy indicated that nano-sized plastic particles adsorbed externally to the duckweed, especially to the roots. Internalized plastic particles could not be detected. Nevertheless, given their important role in ecosystems as a food source for a range of organisms, the adsorption of plastic particles to S. polyrhiza roots as detected in this study can result in the transfer of plastic particles to diverse herbivorous s...