Overlooked risk of microplastics from municipal solid waste–storage site

Abstract

Municipal solid waste (MSW) storage sites are potential and overlooked contributors to microplastic (MP) pollution. Herein, the distribution and dispersion characteristics of MPs at MSW storage sites were investigated through modeling, sampling analysis, and prediction methodologies. The results indicated a notable adsorption phenomenon of MPs on smooth surfaces within such sites, achieving high saturation levels and making MPs prone to re-release by airflow disturbance. Quantitative analysis revealed that the MP concentrations on these surfaces varied from 4.48 × 10⁵ to 1.90 × 10⁶ n/m² and that MPs predominantly accumulated in the corner areas. Notably, MP accumulation on wall surfaces can be reduced by 76.4% using washing procedures. The majority of MPs were under 50 µm in size and were primarily in fragment form. Operational activities such as ventilation and waste handling were identified to amplify the airborne spread of MPs. The atmospheric concentrations of MPs peaked seasonally, with concentrations of 28.25 n/m³ in summer and 3.90 n/m³ in winter, and the spatial dispersion ranged from 14.98 to 124.08 km² per station. This study highlights that MSW storage sites are substantial yet overlooked sources of MP pollution, where wall surfaces play a critical role in MP adsorption and dispersal. The implementation of robust management and cleaning protocols is essential to mitigate the environmental footprint of MPs emanating from these locations. This study also provides a typical case for the precise prevention and control of MPs in the environment.