The Effect and Mechanism of UV Disinfection on the Inactivation of a Planktonic Freshwater Copepods (Limnoithona sinensis)

Abstract

Research ArticleThe Effect and Mechanism of UV Disinfection on the Inactivation of a Planktonic Freshwater Copepods (Limnoithona sinensis)Bench-scale experiments were conducted to evaluate effects of UV radiation (UVR) on Limnoithona sinensis (Copepoda, Crustacea). Results showed that water depth, wavelength, and irradiation time significantly reduced the swimming activity of L. sinensis. The inactivation rate increased with irradiation time, and there was an inverse relation between inactivation rate and water depth. Positive phototaxis was observed in copepods exposed to visible light with wavelengths of 480 or 500 nm, which caused a substantial increase in the inactivation rate when UVR was combined with visible light. Scanning electron microscopy showed that the skin of L. sinensis inactivated by UVR appeared dry and wrinkled, which was possibly due to induction of osmotic changes across cell membranes. As indicated by threedimensional fluorescence spectra showing leakage of protoplasm to the external environment.