NANOPLASTICS IN FRESHWATER ECOSYSTEMS: OCCURRENCE, DETECTION AND ECOTOXICOLOGICAL IMPACTS

Abstract

Freshwater ecosystems including rivers, lakes, reservoirs, wetlands and groundwater systems, play an important role in the global plastic cycle. These ecosystems act as important mediators by adsorbing pollutants from various terrestrial sources and transferring plastic pollutants, including Nanoplastics, to aquatic environments. Global plastic production exceeds 400 million tons per year, causing an unprecedented increase in environmental pollution. These pollutants originate from land and eventually reach the ocean via freshwater.  Among the different sizes of plastic found in aquatic environments, Nanoplastics are generally less than 1µm in diameter. Which are considered as the most toxic due to their very high surface size to volume ratio. This association allows them to cross biological membranes by phagocytosis and be transported into cell. Concentration of Nanoplastics in freshwater systems shows high variability. These variations range from less than 10-40 particles per liter in river. Particles smaller than 100 nm cannot be detected by traditional spectroscopic and microscopic methods, and there are currently no international standards for sampling or quantification. In addition, natural organic matter can introduce spectral interferences that can further complicate the analysis. Evidences suggests that Nanoplastics inhibit microalgae growth and disrupt photosynthesis and interfere with reproductive processes. This suggests that the accumulation of Nanoplastics in freshwater fish tissues can cause oxidative stress, endocrine disruption, liver toxicity, and neuropsychiatric disease. Effect of Nanoplastics also include adsorption and concentration of hydrophobic organic contaminants, heavy metals, antibiotics and endocrine disruptors in ambient waters, followed by their release in large quantities in biological tissues. This review highlights the importance of standardizing sampling and analysis, investing in advanced diagnostic methods and promoting multidisciplinary integration between environmental toxicology, environmental chemistry and risk management paradigms.