Exploring the Impact of Biodegradable and Nonbiodegradable Microplastic Particles on Pb Absorption in Maize

Abstract

Purpose

The aim of this study was to explore the effects of the variations in biodegradable and nonbiodegradable microplastic particles (MPs) on the absorption of lead (Pb) in maize.

Materials and methods

Pot experiments were conducted using maize and two types of MPs, nonbiodegradable polyethylene (PE) and biodegradable polybutylene adipate/terephthalate (PBAT), at four different MP concentrations (0, 0.1, 1, and 10%). After one month of growth, the Pb content in aboveground and belowground parts of the maize seedlings, CaCl₂-extracted Pb content, the proportion of different speciation of Pb within the soil, and soil properties were determined. We determined Pb uptake by maize seedlings, soil physicochemical properties, and Pb speciation in soil.

Results

The addition of PE and PBAT particles led to the decrease in Pb content in maize root with the increase in concentration. The addition of 0.1% PBAT particles significantly increased the Pb content in the shoot of maize plants by 37.60% and Pb content in the root by 65.06% compared with 0.1% PE. The addition of PE and PBAT particles increased the proportion of residual Pb to 36.0% and 38.0%, respectively. The correlation analysis showed that the addition of MPs mainly affected the absorption of Pb by maize plants by affecting soil pH, dissolved organic carbon (DOC), cation exchange capacity (CEC), free crystalline Mn (MnDCB), and amorphous Fe (FeTamm).

Conclusions

This study demonstrates that biodegradable and nonbiodegradable MPs in soil inhibited Pb accumulation in maize seedling roots. FeDCB, MnDCB, and FeTamm may be the main control factors affecting the inhibition of lead uptake by PE in maize seedling roots. Additionally, FeTamm may be the main controlling factor influencing PBAT to reduce lead accumulation in maize seedling roots. The results of the present study could provide novel insights into the toxicity and bioavailability effects of MPs and Pb on maize, as well as a valuable reference for ongoing research on the ecological risk assessment of MPs and other pollutants in the soil environment.