Effect of concentration and exposure time of ZnO-TiO2 nanocomposite on photosynthetic pigment contents, ROS production ability, and bioaccumulation of freshwater algae (Desmodesmus multivariabilis)

Abstract

In this study, the toxic effect of zinc oxide-titanium dioxide nanocomposite (ZnO-TiO2)(NCM) on the reactive oxygen species (ROS) production ability, bioaccumulation, and photosynthetic pigment contents was investigated on Desmodesmus multivariabilis which was exposed for 72 h to 0.1, 0.01 and 0.001 mg l(-1) of (ZnO-TiO2)(NCM). We found that the effect of the photosynthetic pigment contents of (ZnO-TiO2)(NCM) in varying concentrations indicated differences depending on the exposure duration and concentration. D. multivariabilis formed oxidative stress in (ZnO-TiO2)(NCM) within 72 h of exposure. There are important differences between the treatment and control groups in terms of ROS activity (p < 0.01). Due to the increase of the concentration of (ZnO-TiO2)(NCM), the accumulation amounts of zinc (Zn) and titanium (Ti) NP have increased. When the Zn NPs and Ti NPs accumulation amount is taken into consideration, it is observed that the Zn accumulated much more when compared with the Ti.