Microplastic Contamination in Freshwater Ecosystems and Its Potential Effects on Aquatic Organisms

Abstract

Microplastic (MP) pollution has emerged as an important environmental concern because Microplastic contamination has become an increasingly important environmental concern because plastic particles smaller than 5 mm can persist in aquatic environments and interact with aquatic organisms. Although early research concentrated largely on marine environments, freshwater ecosystems are now recognized as important reservoirs and transport pathways for microplastics. This article examines the occurrence, sources, distribution, and potential effects of microplastics on aquatic organisms, with particular emphasis on freshwater ecosystems. The article incorporates primary observations from a previous investigation of inland water bodies in Tehsil Pattoki, Punjab, Pakistan. In that study, twelve water samples were collected from different freshwater sources, including groundwater, canal water, surface water, swamp water, tap water, filtration plants, and swimming-pool water. Samples were processed through sieving, filtration, sodium-chloride density separation, and stereomicroscopic examination. Microplastics were detected in four of the twelve samples. Concentrations ranged from 6 to 15 items/L in positive samples, while the overall mean concentration was 3.583 items/L with a standard deviation of 5.407. The highest concentration was recorded in standing swamp water at 15 items/L, followed by standing surface water at 12 items/L and running canal water at 10 items/L. Three principal forms of microplastics—microfibers, microbeads, and microfragments—were identified in the investigation. Statistical analysis showed a weak negative correlation between the rural and urban groups (r = −0.399), while one-way ANOVA indicated no statistically significant difference between the groups (F = 0.93, p = 0.35). The findings demonstrate that freshwater environments can contain measurable microplastic contamination and that stagnant and surface-associated waters may represent important accumulation sites. Microplastics may affect aquatic organisms through ingestion, physical interaction, trophic transfer, oxidative stress, immune responses, and interactions with associated chemical contaminants. Strengthened plastic-waste management, standardized freshwater monitoring, seasonal sampling, and polymer-specific identification are recommended for future research.