Peroxidizing herbicides formation

The treatment of s-triazine herbicides constitutes a clear application of the combined use of ozone and hydrogen peroxide. At the end of the eighties, this system was investigated to remove triazines in several pilot plants in France and the United Kingdom [228], The successful results obtained led to the implementation of this system in some water-treatment plants, such as those owned by the Compagnie Generale des Eaux in Paris [228], Since then, the 03/H202system has been used in many waterworks to improve the removal of. v-triazines. It should be noted, however, that ozone processes may not be appropriate for the removal of herbicides from water because of the potential formation of very low concentrations of harmful intermediates. 

The formation of hydrogen peroxide has been demonstrated by Davenport (1963) and Davenport and Dodge (1969) in a chloroplast suspension treated with diquat. Reduction and oxidation of bipyridylium herbicides are cyclically repeated in the plant, so that catalytic quantities are sufficient to kill the plant. 

Besides the bleaching cause by either carotene inhibition or peroxidation more targets for "bleaching herbicides" are conceivable, e.g., interference with chlorophyll formation itself. DTP, a substituted pyrazole, was reported to induce chlorosis by blocking... 

The peroxidative reactions were mediated and sustained by Cu(II) ions in the light. Table IV shows that fatty acids with at least 2 double bonds are necessary for hydrocarbon formation. As Anacystis lacks those fatty acids, no peroxidative volatile hydrocarbons were produced. Spirulina exclusively contains CO-6 fatty acids as endogenous polyunsaturated fatty acids and evolved Cs hydrocarbons only. The third species, Anabaena, whose thylakoids contain co-3 and Co-6 polyunsaturated fatty acids formed C2 and C5 hydrocarbons simultaneously. We conclude that co-3 polyunsaturated fatty acids are the source of ethane and ethylene and that the CO-6 polyunsaturated fatty acids are the source of pentane and pentene in herbicide-induced peroxidation reactions. Furthermore, we obtained evidence that the propane measured with Bumilleriopsis after an 18-h treatment with either 10 >iM oxyfluorfen or 50 jxM Cu(II) originates from a CO-4 polyunsaturated fatty acid. We have recently isolated and identified this acid as 16 3CO4 (Sandmann, Lambert, B5ger in preparation). 

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