The combined contamination of nano-polystyrene and nanoAg: Uptake, translocation and ecotoxicity effects on willow saplings

Nanoplastics (NPLs) and nanoAg (AgNPs) are emerging contaminants commonly detected in aquatic and terrestrial environments due to their widespread use in various domains. However, their uptake, translocation, and toxic effects on plants in cooccurrence environments remain largely unexplored. Therefore, a hydroponic experiment was conducted using 100 nm NPLs (1 mg/L and 10 mg/L), AgNPs (100 μg/L and 1000 μg/L) and saplings of willow (Salix matsudana 'J172') to investigate absorption, translocation and the physio-biochemical responses of the plants. The results indicated that NPLs and AgNPs were agglomerated with each other in solutions. NPLs not only penetrated the roots of the saplings but also translocated to the branches and leaves through xylem ducts. However, AgNPs was only detected in the roots, suggesting that the internalization of nanoparticles in plants depends on the properties and types of particles themselves. The combined exposure to NPLs and AgNPs selectively affected the absorption and distribution of K, Ca, Mg and Fe, resulting in inhibited saplings growth and photosynthesis. Furthermore, the presence of NPLs and AgNPs induced oxidative damage and stimulated the antioxidant stress system in the plants. This study provides novel insights into the internalization and ecotoxicological mechanisms of NPLs and AgNPs in woody vascular plants.