Anaerobic degradation, trifluralin

Owing to its low water solubility and high octanol/water partition coefficients, dinitroaniline herbicides adsorb and bind to soil macromolecules and show minimal leaching potential. Dinitroanilines herbicides show good soil residue activities with soil half-lives ranging from 30 days for benfluralin and oryzalin to 6-7 months for trifluralin. Al-Dealkylation (aerobic conditions) and reduction of the nitro group to an amino moiety (anaerobic conditions) have been reported as major soil degradation pathways. 

Degradation of Trifluralin in Submerged Soil. The redox potential of the soil became negative after only 3 days and reached a low of -450 mv after 32 days (Table II). There was little difference in the measurements between the 1 and 3 cm soil depths. We therefore assume that all soil samples (except possibly at Day 2) were anaerobic. 

Figure 5. Postulated pathway of trifluralin degradation in an anaerobic soil from...

Several bench-scale degradation experiments were completed. The data from these studies of 2,4-D butoxyethanol ester, alachlor, trifluralin and atrazine under a variety of aerobic and anaerobic conditions were used for the following preliminary observations ... 

The herbicides 2,4-dichlorophenoxyacetic acid (2,4-D) and trifluralin are mineralized or degraded at slower rates under anaerobic conditions. Pronounced differences in degradation rates of added, labeled 2,4-D as affected by sediment redox potential were observed (DeLaune and Salinas, 1985). Degradation of 2,4-D was approximately six times faster under aerobic conditions (+500mV) as compared to anaerobic conditions (-200 mV) in sediments. The effect of redox... 

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