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Environmental fate & pathways

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Diuron will rapidly disappear in air as evidenced by the calculated half-life of 2.9 to 3.1 hours. Diuron is hydrolytically stable at pH 5, 7 and 9 for 120 hours at 50 °C, in the dark. The hydrolytic degradation of Diuron is less than 10 % and the corresponding half life at ambient temperature (calculated using Arrhenuis equation) estimated to be longer than 1 y. Therefore, chemical hydrolysis can be excluded as a dissipation mechanism of Diuron in environmental systems.

In irradiated solution Diuron degraded with a calculated half-life of about 43 days under natural (latitude 30 -50 ºN) sunlight assuming 12 hours of daylight. The quantum yield (the number of photons destroyed/the number photons absorbed) of direct photodegradation of Diuron in pure water was calculated to be 0.0243. UV spectra and model assessments indicate that the elimination of Diuron from the aquatic environment via direct photodegradation is to be expected.