Abstract: A method for assaying for loss of viability of a photosynthetic microorganism in aqueous liquid is described. The Nmethod comprises the step of correlating the photorepair index (PRI) for said microorganism in the aqueous liquid to survivorship of said microorganism after exposure to ultraviolet (UV) radiation.

Abstract: The is described a process for determining a validated Reduction Equivalent Dose for reducing the concentration of a target contaminant contained in a fluid in a radiation fluid treatment system. In one embodiment, the process comprises the steps of: (a) determining a short wavelength Reduction Equivalent Dose for the target contaminant or a challenge contaminant in a first region of the electromagnetic spectrum having a wavelength of less than or equal to about 240 nm; (b) determining a long wavelength Reduction Equivalent Dose for the target contaminant or a challenge contaminant in a second region of the electromagnetic spectrum having a wavelength of greater than about 240 nm; and (c) summing the short wavelength Reduction Equivalent Dose and the long wavelength Reduction Equivalent Dose to produce the validated Reduction Equivalent Dose for the target contaminant.