Utilizing the allelopathic effect of plants to inhibit algae growth has gained significant attention from researchers in recent years. However, there are large amounts of microplastics in the aquatic environment, which may influence the inhibitory effects of allelochemicals on algae. Consequently, this research aimed to examine the individual and combined toxicity of gallic acid (GA) and polyethylene glycol terephthalate (PET) microplastics on Microcystis aeruginosa. At a concentration of 50 mg/L, PET significantly enhanced algal cell growth and chlorophyll a synthesis, while inducing oxidative stress without damaging the cell membrane. On the other hand, low concentrations of GA promote algal cell growth. However, high concentrations of GA not only inhibit growth and photosynthesis but also result in cellular abnormalities and severe oxidative damage, as well as membrane disruption. Moreover, it was observed that the exposure of PET diminished the toxicity of GA to M. aeruginosa . The combined exposure to GA and PET resulted in a slight increase in chlorophyll a content, as well as phycocyanin (PC), alloxyphycocyanin (APC), and phycoerythrin (PE) content, along with maximum photochemical efficiency (Fv/Fm), compared to GA exposure alone. In the combined system of GA and PET, the contents of superoxide dismutase (SOD) and malondialdehyde (MDA) were lower than those in the single GA system. Additionally, both systems showed a degree of improvement compared to the control group. Scanning electron microscopy (SEM) observed that the presence of PET resulted in reduced damage to algal cells compared to exposure to GA alone. This research establishes a foundation for understanding the synergistic impacts of allelochemicals and microplastics on M. aeruginosa , thereby providing a reference for managing cyanobacteria in water blooms.
Jin Xu,Xiuhong Liu,Yimai Zhou,Shiyong Zhang,Jiaxin Li,Qing Yang
NaClO, as a common membrane cleaning agent were introduced from the permeate side across membrane, which could diffuse into MBR membrane pool. Microplastics would also accumulate in MBR membrane pool during wastewater treatment, thus, NaClO and MPs are co-exposed to activated sludge. This study investigated the effects of PET-MPs (0, 50, 100 and 300 μg/g-ss) on activated sludge with or without NaClO stress. The presence of PET-MPs had no significant impact on nitrification and denitrification rates, but when exposed to NaClO, the increasing level of PET-MPs (i.e., from 0 to 300 μg/g-ss) inhibited the nitrification (94.85 % to 65.90 %) and denitrification (88.68 % to 60.09 %) rates. For microbial metabolism (key enzymes) evaluated, the key enzymes related to organic matter biodegradation, nitrification as well as denitrification were both inhibited with PET-MPs level rise under NaClO stress. The generation of reactive oxygen species (ROS) and the release of lactate dehydrogenase (LDH) increased significantly indicating NaClO caused the toxicity of MPs to activated sludge by enhancing the oxidative stress level. Correspondingly, a variation in abundance related to membrane pollution, nitrification, and denitrification after exposure to PET-MPs with NaClO stress accompanied these adverse effects.
危险品化学品经营许可证（带存储）