Effect of dissolved organic compounds on the photodegradation of the herbicide MCPA in aqueous solution

WATER RESEARCH

卷:44

Article

Vione, Davide^1,2  Khanra, Swapan¹  Das, Radharani¹  Minero, Claudio¹  Maurino, Valter¹  Brigante, Marcello^3,4  Mailhot, Gilles^3,4 

[1] Univ Turin, Dipartimento Chim Analit, I-10125 Turin, Italy

[2] Univ Torino, Ctr Interdipartimentale NatRisk, I-10095 Grugliasco, TO, Italy

[3] Univ Blaise Pascal, Clermont Univ, Photochim Mol & Macromol Lab, F-63000 Clermont Ferrand, France

[4] CNRS, UMR 6505, Photochim Mol & Macromol Lab, F-63177 Aubiere, France

关键词: Pesticide photodegradation;    Direct and sensitised photolysis;    Dissolved organic matter;    Photochemistry modelling;    Radiation absorption;   

DOI  :  10.1016/j.watres.2010.07.079

来源: Elsevier

【 摘 要 】

This work shows that the addition of phenol and 2-propanol as model organic compounds significantly decreases the direct photolysis quantum yield of 4-chloro-2-methylphenoxy-acetic acid (MCPA) upon UVB irradiation in aqueous solution. Laser flash photolysis data suggest that 2-propanol is able to decrease the formation of the MCPA excited states under irradiation. A decrease from 0.54 to 0.34 of the photolysis quantum yield of the anionic form of MCPA (which prevails over the undissociated one in surface waters) could have a considerable impact on the MCPA lifetime in ecosystems where the direct photolysis is the main phototransformation pathway. In surface water bodies where the direct photolysis has comparable kinetics as the reaction with center dot OH, a decrease of the quantum yield would enhance the relative importance of the center dot OH pathway, which yields considerably less toxic intermediates than the direct photolysis. (C) 2010 Elsevier Ltd. All rights reserved.

【 授权许可】

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