TiO2 nanoparticles (NPs) could adversely impact aquatic ecosystems. However, the aggregation of these NPs could attenuate this effect. In this work, the biological effects of TiO2 NPs on a marine microalgae Isochrysis galbana were investigated. The aggregation kinetics of TiO2 NPs under different conditions was also investigated to determine and understand these effects. Results showed that, though TiO2 NPs had no obvious impact on the size and reproducibility of algal cells under testing conditions, they caused a negative effect on algal chlorophyll, which led to a reduction in photosynthesis. Furthermore, fast aggregation of TiO2 NPs occurred under all conditions, especially at the pH close to the pHzpc. Increasing ionic strength and NP concentration also enhanced the aggregation rate. The aggregation and the following sedimentation of TiO2 NPs reduced their adverse effects on I. galbana.
Keywords: Aggregation; Ecotoxicity; Marine microalgae; Nanoparticles; Titanium dioxide.
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