Concentrations and adsorption performance of heavy metals of microplastics from plastic sports fields

Plastic sports fields represent a significant source of microplastics (MPs) pollution, yet their heavy metal adsorption characteristics and associated ecological and human health risks remain poorly elucidated. This study investigated the MP release characteristics, heavy metal concentration, and adsorption performance of polyurethane MPs collected from campus plastic sports fields. Results revealed that a standard-sized stadium releases up to 5.96×10⁶ MPs per aging cycle, with heavy metal concentrations in MPs following the order: Zn > Mn > Cr > Ni > Pb > Cu > Co > Cd. Total carcinogenic risks (CR) of arsenic (As) and cobalt (Co) across all sampling plots exceeded the acceptable threshold of 1×10⁻⁶. Derived risk control values of As (1.85 mg/kg) and Co (7.67 mg/kg) were calculated to provide preliminary reference for pollution management. PU MPs exhibited high saturated adsorption capacity of metals, such as of Cu²⁺ and Zn²⁺. Cu²⁺ displayed a distinct competitive adsorption advantage, especially at high temperatures. These findings highlight the urgent need for enhanced management and regulation of plastic sports facilities to mitigate the combined pollution risks of MPs and heavy metals.