LAUSR

Compared to traditional toxicological studies, which depict the dose-effect of contaminants themselves on organisms at the given time, the exposure and post-exposure impacts of antibiotic ceftazidime and its photoproducts are carried out to systematically evaluate the environmental risk fate of ceftazidime in aquatic environments. For the exposure process, the promotion effect of ceftazidime on the feeding behavior of the rotifers decreased when the target compound was irradiated by sunlight, and the promotion effect was converted into inhibition effect, which indicated that the highest toxicity of ceftazidime on the feeding behavior of the rotifers was found after UV-B irradiation. The overcompensation occurred in the post-exposure, indicating a short - term effect of the corresponding photoproducts on the rotifer. In order to better understand the mechanism of this change, the photodegradation pathways of the target compound was analyzed and compared. The degradation degree under the UV-B irradiation had intensified greatly than that under the nature light irradiation. The reactive oxygen species (ROS) of the rotifer in exposure and post-exposure was also detected. Ceftazidime and photoproducts induced generation of ROS, indicating that oxidative damage occurred, and the decreasing of ROS levels could be viewed as the recovery of the rotifers in the post-exposure.