Photochemical transformation of anionic 2-nitro-4-chlorophenol in surface waters: Laboratory and model assessment of the degradation kinetics, and comparison with field data

Babita Sur, Elisa De Laurentiis, Marco Minella, Valter Maurino, Claudio Minero, Davide Vione, Babita Sur, Elisa De Laurentiis, Marco Minella, Valter Maurino, Claudio Minero, Davide Vione

Index: Sci. Total Environ. 426 , 296-303, (2012)

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Abstract

Anionic 2-nitro-4-chlorophenol (NCP) may occur in surface waters as a nitroderivative of 4-chlorophenol, which is a transformation intermediate of the herbicide dichlorprop. Here we show that NCP would undergo efficient photochemical transformation in environmental waters, mainly by direct photolysis and reaction with OH. NCP has a polychromatic photolysis quantum yield ΦNCP=(1.27±0.22)·10−5, a rate constant with OH kNCP,OH=(1.09±0.09)·1010M−1s−1, a rate constant with 1O2kNCP,1O2=(2.15±0.38)·107M−1s−1, a rate constant with the triplet state of anthraquinone-2-sulphonate kNCP,3AQ2S*=(5.90±0.43)·108M−1s−1, and is poorly reactive toward CO3−. The kNCP,3AQ2S* value is representative of reaction with the triplet states of chromophoric dissolved organic matter. The inclusion of photochemical reactivity data into a model of surface–water photochemistry allowed the NCP transformation kinetics to be predicted as a function of water chemical composition and column depth. Very good agreement between model predictions and field data was obtained for the shallow lagoons of the Rhône delta (Southern France).