Spatiotemporal distribution and ecological hazards of microplastic pollution in soil water resources around a wastewater treatment plant and municipal solid waste site

Abstract

Research into the relative contributions of microplastic (MP) sources to aquatic and terrestrial environments is essential for understanding their fate and transport which is a prerequisite for designing effective pollution management strategies. This study explores the spatial distribution, seasonal variations, and ecological hazards of MPs in surface water, groundwater, soil, sediment, and leachate matrices adjacent to municipal solid waste (MSW) and sewage treatment plant (STP) sites in Northern India. Elevated MP concentrations were observed in leachate (283.22 ± 15.78 particles/L; pre-monsoon), whereas groundwater exhibited significantly reduced levels (10.75 ± 2.04 particles/L; pre-monsoon), indicating the attenuation efficiency and filtration potential of the subsurface zone. Seasonal variations revealed a dilution effect from monsoonal runoff, reducing MP concentrations. The identified MP shapes were predominantly fibers, followed by fragments, with transparent particles being the most common. The size distribution was dominated by smaller MPs (<0.3 mm), which exhibited a positive correlation with overall MP concentrations. The polymer types of MPs identified in the samples categorise the polymer hazard index (PHI) as a hazard level V (>1000) in all the samples indicating a high chemical risk in both the seasons. Similarly, the principal component analysis (PCA) revealed MP hotspots, particularly in soils near the MSW site, with concentrations reaching 53,580 ± 720 particles/kg emphasizing the vulnerability of terrestrial systems. This research highlights the importance of implementing effective waste management practices and provides valuable insights into the fate and transport of MPs by presenting strong evidence of MP movement from typical MSW/STP sites into adjacent land and water resources.