Chronic impacts of TiO₂ nanoparticles on Populus nigra L. leaf decomposition in freshwater ecosystem

Titanium dioxide (TiO₂) nanoparticles have been applied in diverse commercial products, which could lead to toxic effects on aquatic microbes and would inhibit some important ecosystem processes. The study aimed to investigate the chronic impacts of TiO₂ nanoparticles with different concentrations (5, 50, and 500 mg L^-1) on Populus nigra L. leaf decomposition in the freshwater ecosystem. After 50 d of decomposing, a significant decrease in decomposition rates was observed with higher concentrations of TiO₂ nanoparticles. During the period of litter decomposition, exposure of TiO₂ nanoparticles led to decreases in extracellular enzyme activities, which was caused by the reduction of microbial especially fungal biomass. In addition, the diversity and composition of the fungal community associated with litter decomposition were strongly affected by the concentrations of TiO₂ nanoparticles. The diversity and composition of the fungal community associated with litter decomposition was strongly affected. The abundance of Tricladium chaetocladium decreased with the increasing concentrations of TiO₂ nanoparticles, indicating the little contribution of the species to the litter decomposition. In conclusion, this study provided the evidence for the chronic exposure effects of TiO₂ nanoparticles on the litter decomposition and further the functions of freshwater ecosystems.