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Environmental fate & pathways

Phototransformation in water

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Description of key information

Photodegradation processes are capable of contributing significantly to the elimination of Diuron from the aquatic environment.

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Additional information

In irradiated solution Diuron degraded with a half-life of 9 days under the study conditions, equivalent to a calculated half-life of about 43 days under natural (latitude 30 -50 ºN) sunlight assuming 12 hours of daylight. Trapped volatile radioactivity, mainly14CO2, amounted to 16% AR by the end of the study. Thirteen minor photoproducts were formed, none of which accounted for more than 9% applied radioactivity at any time, and most of which were considerably more polar than Diuron. Diuron was not degraded in dark control solutions (Hawkins et al., 1989). The quantum yield (the number of photons destroyed/the number of photons absorbed) of direct photodegradation of Diuron in pure water was calculated to be 0.0243 (Hellpointner, 1991).