Fate of Fluometuron Dissolved in Natural Waters and Exposed to Solar Light

Year 2012, Volume: 2 Issue: 4, 24 - 29, 23.07.2016

Sabrina Halladja Abdelaziz Boulkamh Claire Rıchard

Abstract

To predict the fate of pollutants in the aquatic environment and to assess the risk they may pose, it is necessary to improve our knowledge on their chemical reactions under environmental conditions. Photochemical reactions are a route for the attenuation of organic pollutants present in surface waters. This work was devoted to herbicide fluometuron which is used to control weeds in cotton. Phototransformation of fluometuron (1 µM) in natural sunlight was investigated in synthetic waters containing either natural organic matter, nitrate ions or both in order to mimic reactions taking place in aquatic environments. Fluometuron underwent photolysis and its degradation was faster in the presence of fulvic acids (10 mg l-1, factor 2.5) or nitrates (25 mg l-1, factor 15) than in Milli-Q water showing the importance of natural waters constituents. Identification of major photoproducts was conducted under laboratory conditions. Hydroxylation of the aromatic ring with or without hydrolysis of CF into CO2H and oxidation of the urea chain leading to demethylation were observed

Keywords

photodegradation, phenylureas herbicides, solar light, naturel waters

References

• Boule, P., Bolte, M., Richard, C., (1999). Phototransformations induced in aquatic medium by FeIII, NO- 3, NO- 2 and humic substances. In: Boule, P. (Ed.), The Handbook of Environmental Chemistry. In: Editor in Chief: O. Hutzinger (Ed.), Environmental Photochemistry, vol. 2. Bayreuth (FRG), part L, pp. 181–215.
• Brezonik, P.L., Fulkerson-Brekken, J., (1998). Nitrate-induced photolysis in natural waters: controls on concentrations of hydroxyl radical photointermediates by natural scavenging agents. Environ. Sci. Technol. 32, 3004–3010.
• Buxton, G.V., Greenstock, C.L., Helman, W.P., Ross, A.B., (1988). Review of rate constants for reactions of hydrated electrons, hydrogen atoms and hydroxyl radicals in aqueous solution. J. Phys. Chem. Ref. Data 17, 513–886.
• Canonica, S., Jans, U., Stemmler, K., Hoigne´, J., (1995). Transformation kinetics of phenols in water: photosensitization by dissolved organic material and aromatic ketones. Environ. Sci. Technol. 29, 1822–1831.
• Halladja, S.; Ter Halle, A.; Aguer, J. - P.; Boulkamh, A.; Richard, C., (2007). Inhibition of humic substances mediated photooxygenation of furfuryl alcohol by 2,4,6-trimethylphenol. Evidence for reactivity of the phenol with humic triplet excited states. Environ.Sci. Technol. 41, 6066–6073.
• Lam, M.W., Young, C.J., Mabury, S.A., (2005). Aqueous photochemical reaction kinetics and transformations of fluoxetine. Environ. Sci.Technol. 39, 513–522.
• Muschal, M., Warne, M.S.J., (2003). Risk posed by pesticides to aquatic organisms in rivers of northern inland New South Wales, Australia. Hum. Ecol. Risk Assess. 9, 1765–1787.
• Stoeckel, D.M., Mudd, E.C., Entry, J.A., (1997). Degradation of persistent herbicides in Riparian wetlands. ACS Symp. Ser. 664, 114–132.
• ter Halle, A., Richard, C., (2006). Simulated solar light irradiation of mesotrione in natural waters. Environ. Sci. Technol. 40, 3842– 3847.
• Vaughan, P., Blough, N., (1998). Photochemical formation of hydroxyl radical by constituents of natural waters. Environ. Sci. Technol. 32, 2947–2953.
• Zepp, R.G., Cline, D.M., (1977). Rates of direct photolysis in aquatic environment. Environ. Sci. Technol. 11, 359–366