Food web effects of titanium dioxide nanoparticles in an outdoor freshwater mesocosm experiment

AbstractOver the course of 78 days, nine outdoor mesocosms, each with 1350 L capacity, were situated on a pontoon platform in the middle of a lake and exposed to 0 μg L−1 TiO2, 25 μg L−1 TiO2 or 250 μg L−1 TiO2 nanoparticles in the form of E171 TiO2 human food additive five times a week. Mesocosms were inoculated with sediment, phytoplankton, zooplankton, macroinvertebrates, macrophytes and fish before exposure, ensuring a complete food web. Physicochemical parameters of the water, nutrient concentrations, and biomass of the taxa were monitored. Concentrations of 25 μg L−1 TiO2 and 250 μg L−1 TiO2 caused a reduction in available soluble reactive phosphorus in the mesocosms by 15 and 23%, respectively, but not in the amount of total phosphorus. The biomass of Rotifera was significantly reduced by 32 and 57% in the TiO2 25 μg L−1 and TiO2 250 μg L−1 treatments, respectively, when compared to the control; however, the biomass of the other monitored groups—Cladocera, Copepoda, phytoplankton, macrophytes, chir...