Translocation and chronic effects of microplastics on pea plants (Pisum sativum) in copper-contaminated soil

Microplastics (MPs) released into soil environments, along with the existing pollutants in soil, may have adverse effects on plants. However, the chronic effects of MPs in soils contaminated with heavy metals on crop plants remain unidentified. This study aimed to investigate the chronic effects of MPs (polystyrene, 20 nm) on the reproductive and nutritional status of pea crop plant (Pisum sativum) grown in Cu- (40 mg/kg) and MP-contaminated soils (40, 20 mg/kg). The crop yield reduced in all groups, with an evident decrease in the complex exposure group (comprising MPs and Cu). Moreover, significant changes in plants were identified regarding the weight, color, amino acids, and protein content of peas. Nutrient content in beans increased by MP exposure in single and complex exposure groups. Cu accumulation did not differ in the presence and absence of MPs. Additionally, MPs that infiltrated into incomplete casparian strips during root formation translocated into aerial parts via the apoplast pathway along the cell walls of the vascular bundle. Therefore, long-term exposure to MPs in soil can significantly affect plants while collective application of Cu and MPs imposed severe damage. The changes in the crop quality and nutrient contents may in turn affect human health through the food chain.