Trifluralin: Photolysis under sunlight conditions and reaction with HO radicals

The gas phase atmospheric degradation of trifluralin (a widely used herbicide) has been investigated at the EUPHORE facility. Its photolysis has been studied under sunlight conditions and its reaction rate constant with HO radicals was measured using the relative rate method. Using 1,3,5-trimethylbenzene as reference compound, the rate constant of HO reaction with trifluralin was obtained to be k HO = ( 1.7 ± 0.4 ) × 10 - 11 cm 3 molecule s −1 at (300 ± 5) K and atmospheric pressure. The mean photolysis rate measured under solar radiation was J trifluralin = (1.2 ± 0.5) × 10 −3 s −1 ( J NO 2 = 8 × 10 - 3 s - 1 ) . The photolysis of trifluralin was found to generate organic aerosols with a yield of (20 ± 10)%. The data obtained enabled us to discuss the atmospheric fate of trifluralin in the gas phase.