Effects of Nanoplastics on Freshwater Organisms:A Review
Plastic pollution is increasingly serious and has emerged as one of the most critical environmental problems in the world today.Plastic debris in the environment further degrades,forming particles smaller than 1 μm,known as nanoplastics.Currently,studies on the behavioral effects of nanoplastics are mainly focused on marine ecosystems,but less on freshwater ecosystems which are the hardest hit by plastic pollution.In view of this,this paper summarizes the literature on the toxic effects of nanoplastics on organisms in freshwater ecosystems and the main mechanisms of toxicity,providing an overview of their biological effects according to the order of trophic level(microalgae,zooplankton,fish)from low to high.Studies have shown that nanoplastics can affect microalgal cell growth through various pathways,such as the inhibition of photosynthesis,promotion of hetero-aggregation,disruption of cellular structure,and induction of oxidative stress.Nanoplastics can also cause abnormal behavior in zooplankton and fish,disrupting their energy balance,inducing oxidative stress and genotoxicity,and further inhibi-ting their growth,development and reproduction.However,existing studies still lack diversity in nanoplastics categories and test organisms.The concentration of experimental nanoplastics is not in line with the real environ-mental conditions.Moreover,the experimental media are mostly artificial,with a simple composition that cannot accurately reflect the complexity of the natural system.Furthermore,the experimental design does not sufficiently take into account the aging of nanoplastics,the interaction with the natural organic matter or other pollutants,and so on.Therefore,future research should focus on nanoplastics existing in environments with relatively notable concentrations,as well as biological populations with high abundance and sensitivity.Designing experimental conditions that are more closely related to the real environment so as to better assess the biological effects of nanoplastics.These efforts will provide theoretical support for the prevention and control of nanoplastics in freshwater ecosystems as well as the formulation of relevant standards.
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