Effects of nano-TiO2 in combination with ambient UV-irradiation on a leaf shredding amphipod

Production and use of engineered nanoparticles, such as titanium dioxide nanoparticles (nTiO2), is increasing worldwide, enhancing their probability to enter aquatic environments. However, direct effects of nTiO2 as well as ecotoxicological consequences due to the interactions of nTiO2 with environmental factors like ultraviolet (UV) irradiation on representatives of detrital food webs have not been assessed so far. Hence, the present study displayed for the first time adverse sublethal effects of nTiO2 at concentrations as low as 0.2 mg L−1 on the leaf shredding amphipod Gammarus fossarum both in presence and absence of ambient UV-irradiation following a 7-d exposure. In absence of UV-irradiation, however, the effects seemed to be driven by accumulation of nTiO2 at the bottom of the test vessels to which the gammarids were potentially exposed. The adverse sublethal and lethal effects on gammarids caused by the combined application of nTiO2 and ambient UV-irradiation are suggested to be driven by the formation of reactive oxygen species. In conclusion, both the accumulation of nTiO2 at the bottom of the test vessel and the UV induced formation of reactive oxygen species clearly affected its ecotoxicity, which is recommended for consideration in the environmental risk assessment of nanoparticles.

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► Effects of nTiO2 and ambient UV-irradiation affect representatives of detrital food webs.
► Accumulation of nTiO2 at the bottom of the test vessel seems to affect ecotoxicity.
► nTiO2 and ambient UV-irradiation increases ecotoxicity due to the formation of ROS.