Influence of sulfur/chlorine-containing pesticides on the aging and heavy metal dynamics of PBAT and LDPE microplastics in soil

Abstract

Microplastics (MPs) pollution in soil has emerged as a significant environmental concern, particularly regarding the interactions between MPs and chemical contaminants such as pesticides. This study focused on the aging of biodegradable poly(butylene adipate-co-terephthalate) (PBAT) and low-density polyethylene (LDPE) films in the presence of five sulfur/chlorine (S/Cl)-containing pesticides (prothioconazole, myclobutanil, isazophos, harmony, and flumetsulam), selected for their common use in agricultural practices and potential environmental persistence. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and inductively coupled plasma mass spectrometry (ICP-MS) were employed to investigate the dynamics of heavy metal adsorption and release (specifically Ni, Cu, and Sn) during MPs aging, as indicated by changes in surface morphology and polymer functional groups. Results revealed that PBAT aged more rapidly than LDPE, irrespective of pesticide presence. All pesticides tested accelerated aging of MPs, with a notable enhancement in the adsorption of Ni and Cu and the release of Sn. Among the pesticides, prothioconazole and myclobutanil exhibited the most significant effects on aging of MPs and heavy metal interactions, while harmony and flumetsulam had minimal impact. These findings highlight the potential environmental risks associated with the combined exposure of MPs and pesticides, offering insights for future environmental risk assessments.