Differential Leaf-to-Root\nMovement, Trophic Transfer,\nand Tissue-Specific Biodistribution of Metal-Based and Polymer-Based\nNanoparticles When Present Singly and in Mixture

The transfer of nanoparticles (NPs) through the terrestrial\nfood\nchain via foliar uptake presents poorly understood risks, especially\nin scenarios involving copollution and plant translocation. Herein,\nwe exposed the radishes to single and mixed foliar doses of CeO<sub>2</sub> NPs and deuterated polystyrene (DPS), investigating the trophic\ntransfer of NPs from radish shoots/roots to snails. Compared to single\ntreatments, mixture treatments increased Ce uptake by plants but had\nno effect on DPS uptake. Additionally, mixture treatments did not\naffect the movement of Ce and DPS from shoots to roots. Under NP mixture\nexposure, trophic transfer efficiencies (TTF) for Ce (2.09 ×\n10<sup>–2</sup>) and DPS (2.54 × 10<sup>–2</sup>) significantly decreased in shoot-feeding snails. In root-feeding\nsnails, TTF for Ce (3.32 × 10<sup>–1</sup>) also showed\na significant decrease, while TTF for DPS remained unchanged. Mixture\ntreatments exhibited differential impacts on different snail body\nparts, particularly leading to biomagnification of DPS in the digestive\nglands and soft tissues (TTF > 1) of snails consuming roots exposed\nto mixtures. Both CeO<sub>2</sub> and DPS displayed a sudden increase\nin assimilation efficiency following translocation to the roots. This\nstudy provides insights into changes during trophic transfer due to\ncoexposure and plant translocation processes associated with nanoparticles,\nenhancing our comprehension regarding their environmental risks.