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Environmental fate & pathways

Phototransformation in water

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The quantum yield of direct photodegradation of the hydrolysis product 1,5-naphthylenediamine in water was determined according to the Test Guideline: Phototransformation of Chemicals in Water, Part A: Direct Phototransformation. UBA, , FRG (1992) in polychromatic light. From the UV absorption data and the kinetic results of two photodegradation experiments in a merry-go-round irradiation apparatus the quantum yield was calculated to be = 0.04 (Bayer AG). The resulting quantum yield and UV absorption data in water were used to estimate the environmental half-life of 1,5-naphthylenediamine concerning direct photodegradation in water. The arithmetic model developed by Frank and Klöpffer takes the conditions of cloudiness in Central Europe into consideration and is more geared for the conditions in Germany. Therefore, the environmental half-lives, estimated by this program are preferred to assess abiotic degradation due to photolysis. A mean half-life of 1.4 hours under environmental conditions was obtained.

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