Microplastic contamination in different aged landfill mineralization

Domestic landfills function as both significant sinks and sources of microplastics (MPs). Inadequate management and re-excavation of landfill mineralized refuse can lead to the release of these emerging contaminants into the surrounding environment, resulting in secondary pollution. Therefore, systematic risk assessments of MPs in landfills are crucial for understanding their environmental impact and informing mitigation strategies. This research investigated three landfills in economically diverse regions of Southeast China, including two sanitary landfills and one informal dump site. A uniform sampling and analytical approach, including solvent extraction and pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS), was applied to quantify mixed MPs of polyethylene (PE), polypropylene (PP), and polystyrene (PS) across 68 mineralized refuse samples. The average MPs concentrations in the three landfills ranged from 0.44 to 1.56 g/ (kg mineralized refuse by mass), and 0.105 to 0.397 g/ (m³ mineralized refuse by volume). Sanitary landfills contained higher MPs levels due to prolonged degradation under harsh landfill conditions. However, despite its older landfill age, the dump site exhibited lower MPs concentrations but a higher diffusion threat due to the lack of effective preventive measures. This research demonstrated that MPs contamination risk was also driven by landfill age and regional economic status. These findings provide a quantitative basis for assessing MPs pollution in landfills and emphasize the need for targeted strategies to mitigate MPs release into the environment.