Abstract:

Micro/nanoplastics (MNPs) and microalgae are widely distributed in water and MNPs that adhere to the surface of microalgae or enter their internal structures will enter the food chain in large quantities, posing a great threat to aquatic ecosystems. The physiological effects of MNPs on algae vary depending on their particle sizes. In this study, polystyrene micro/nanoplastics(PS-MNPs) particles were selected as target pollutants to investigate their toxicological effects on Microcystis aeruginosa (FACHB 905) at different concentrations (5, 10, 50 and 250 mg/L) and particle sizes (100 μm and 80 nm). Results showed that the inhibition effect of 80 nm PS-MNPs exerted a more potent inhibitory effect on the growth of algal, chlorophyll a and phycobiliprotein synthesis than 100 μm PS-MNPs, and the inhibitory effect was more obvious with the increase of PS concentration. In addition, the activities of catalase (CAT), malondialdehyde dehydrogenase (MDA) and glutathione (GSH) in microalgae cells were significantly increased under the stress of high concentration of PS-MNPs, indicating that high concentration of PS-MNPs caused oxidative damage to algal cells, and smaller PS-MNPs particles can lead to more severe oxidative damage. The toxicity of PS-MNPs with different particle sizes toward M. aeruviosa mainly led to cell destruction through surface adsorption, which affected photosynthesis and energy metabolism of algal cells, hindering normal physiological and biochemical reactions in algal cells. This study, by exploring the toxicity mechanism of PS-MNPs to microcystis aeruginosa, is of great significance for the risk assessment of PS-MNPs, and provides a theoretical basis for the prevention of M. aeruginosa bloom.

Key words: micro/nanoplastics, polystyrene, Microcystis aeruginosa, toxicological effects