Morphological rather than abundance factors control microplastic accumulation in wheat grains: a field-based study

Abstract

Most microplastic (MP) uptake studies are lab-based, lacking field validation. This study analyzes MP accumulation in wheat grains under conventional farming, linking it to soil MP properties. Two wheat varieties showed consistent accumulation trends. Py-GC/MS identified polyethylene terephthalate (PET) as the most abundant grain MP (5.70 +/- 0.41 mg/kg), while polystyrene (PS) was least accumulated (0.82 +/- 0.12 mg/kg) despite higher soil PS levels, indicating selective uptake. Grain MP content did not correlate with soil MP abundance but negatively correlated with particle size (p < 0.001): PET and PE (20-40 mu m) accumulated more than polyvinyl chloride (PVC) (70-80 mu m). MP shape also influenced uptake (p < 0.05); fibrous PS likely hindered absorption. This study is the first to identify MP shape as a key factor in plant uptake, offering new mechanistic insights.