Abiotic Degradation of Trifluralin by Fe(II): Kinetics and Transformation Pathways

The herbicide trifluralin (2,6-dinitro- N, N -dipropyl-4-(trifluoromethyl)benzenamine) is widely used in agriculture and may pose toxic risks to some aquatic organisms. While its degradation has been investigated in field studies, this research is the first to elucidate the specific abiotic transformations that trifluralin may undergo in reducing environments such as flooded soils and wetland sediments. Kinetic data and product identities were determined for the degradation of trifluralin in Fe(II)/goethite suspensions at near-neutral pH values. Under these conditions, trifluralin is consumed rapidly through a surface-mediated process that includes three distinct reactions: reduction of nitro groups, dealkylation of propylamines, and cyclization to form benzimidazoles. All detected products are among those that have been reported in natural soils and sediments. Therefore, these transformation pathways may play a significant role in affecting the fate of trifluralin in the environment.