Temporal and Size Dependent Uptake of Micro- and Nano Plastics in an Edible Plant

Abstract

Micro- and nanoplastic (MNP) uptake in the edible plant basil (Ocimum basilicu) was investigated using poly(methyl methacrylate) (PMMA) MNPs with broad size distributions labeled with dibutyl phthalate (DBP), tantalum(V) ethoxide, or rhodamine 640 perchlorate. Basil plants were grown hydroponically in media containing one of the labeled MNPs types. DBP concentrations in roots and shoots were measured by GC–MS as a proxy for MNP uptake. MNP accumulation increased over time with plant growth, with root concentrations exceeding shoot concentrations by more than 2 orders of magnitude. After 8 weeks, DBP concentrations reached 2321 ± 308 μg/g in roots and 18 ± 8 μg/g in shoots. Fluorescence microscopy confirmed MNP uptake into root tissues using rhodamine-labeled particles. Single-particle inductively coupled plasma mass spectrometry (spICP-MS) with tantalum-labeled MNPs demonstrated preferential uptake and translocation of smaller particles from the growth solution to roots and from roots to shoots. These findings indicate that nanoplastics are more readily accumulated and transported within plants than larger microplastics. Facilitated transport of solution phase DBP as a result of adsorption to MNPs, accompanied by plant uptake was also observed. Together, these complementary MNP labeling strategies provide a robust approach for investigating MNP uptake dynamics and associated contaminant transport in plants.