Dynamics of microplastics along landfill leachate pathways and treatment processes

BACKGROUND AND OBJECTIVES: Landfill leachate has been identified as a pathway for microplastic release into aquatic environments; however, its role as a dynamic transformation system remains poorly understood. The objectives of the study were to analyze the variations in microplastic abundance and polymer composition at various stages of a landfill leachate system, in addition to comparing the present conditions with prior observations.METHODS: Surface water samples were collected from four key points, including before effluent, leachate pond, leachate drain, and after effluent. The protocols previously established were followed for the sampling design, extraction, and identification procedures to maintain comparability. Microplastics were quantified in particles per cubic meter and characterized by polymer composition. These techniques were corroborated by Fourier transform infrared analysis, which revealed for approximately 32 percent of the particles were accounted for, achieved a recovery efficiency of 99.5 to 99.9 percent, and exhibited no contamination in procedural blanks.FINDINGS: Microplastic abundance increased across all stages, with moderate increments observed in upstream and downstream sections and higher increases within the leachate pond and drain. Relative to past observations, the current analysis demonstrates sustained amplification within the system. Polymer composition remained dominated by polyethylene and polypropylene, while additional polymer types emerged in the leachate pond and drain, indicating increased diversity. Multiple polymers remained following the discharge of effluent, indicating that removal was not fully achieved. These patterns are further supported by the dominance of fragment-type particles and shifts toward smaller size classes along the leachate pathway, suggesting progressive fragmentation inferred from size distribution. An evaluation grounded in relative concentration suggests that the system exhibits non-conservative behavior, characterized by negative removal efficiency in the transition from upstream and downstream sections.CONCLUSION: The landfill leachate system does not behave as a simple transport pathway but instead exhibits characteristics of a transformation-active environment, based on observed spatial patterns and polymer evidence. The rise in abundance and the diversification of polymers suggest that the existing leachate management systems are not very efficient. These results underscore the necessity for enhanced treatment strategies, which encompass targeted methods for microplastic removal approaches, and integration of microplastic monitoring into leachate management systems to mitigate environmental risks downstream.