Sources, Pathways, and Environmental Risks of Microplastics in Inland Aquatic Ecosystems

Abstract

Microplastic (MP) pollution has emerged as an important environmental concern because small plastic particles can persist in aquatic ecosystems, occur in diverse forms, and interact with aquatic organisms and food webs. Although much of the early research focused on marine environments, inland aquatic systems are increasingly recognized as important reservoirs and pathways for microplastic transport. This article examines the major sources, environmental pathways, distribution patterns, and ecological risks associated with microplastics in inland aquatic ecosystems, with particular emphasis on freshwater systems. The analysis incorporates empirical observations from a previous investigation of inland water bodies in Tehsil Pattoki, Punjab, Pakistan. In that study, 12 water samples were collected from groundwater, canal water, surface water, swamp water, swimming-pool water, tap water, and filtration-plant sources and analyzed using sieving, density separation with sodium chloride, filtration, and stereomicroscopic observation. Microplastics were detected in four of the twelve samples, with concentrations ranging from 6 to 15 items/L. The overall mean concentration was 3.583 items/L. The highest concentration was recorded in standing swamp water (15 items/L), followed by standing surface water (12 items/L) and running canal water (10 items/L). The observations demonstrate that relatively stagnant and surface-associated inland waters may represent important accumulation environments. Potential pathways include wastewater and runoff, degradation of larger plastic materials, urban and agricultural activities, domestic sources, and transport through drainage and surface-water networks. Microplastics may subsequently be transferred to aquatic organisms through ingestion and may contribute to physical and toxicological stress. The findings support the need for improved plastic-waste management, systematic monitoring of inland waters, standardized analytical procedures, and further research on polymer composition and ecological effects.