Photochemical transformation of atrazine and formation of photointermediates under conditions relevant to sunlit surface waters: Laboratory measures and modelling
Articolo
Data di Pubblicazione:
2013
Abstract:
By combination of laboratory experiments and modelling, we show here that the main
photochemical pathways leading to the transformation of atrazine (ATZ, 2-chloro-4-
ethylamino-6-isopropylamino-1,3,5-triazine) in surface waters would be direct photolysis,
reaction with OH and with the triplet states of chromophoric dissolved organic
matter (3CDOM*). Reaction with 3CDOM* would be favoured by elevated water depth and
dissolved organic carbon content, while opposite conditions would favour direct photolysis
and OH reaction. Desethylatrazine (DEA, 4-amino-2-chloro-6-isopropylamino-1,3,5-
triazine) was the main detected intermediate of ATZ phototransformation. Its formation
yield from ATZ (ratio of DEA formation to ATZ transformation rate) would be 0.93 0.14 for
OH, 0.55 0.05 for 3CDOM*, and 0.20 0.02 for direct photolysis. Direct photolysis and OH
reaction also yielded 4-amino-2-hydroxy-6-isopropylamino-1,3,5-triazine (DEAOH) and 6-
amino-2-chloro-4-ethylamino-1,3,5-triazine (DIA). Reaction with excited triplet states
also produced 2-hydroxy-4,6-diamino-1,3,5-triazine (AN) and 2-chloro-4,6-diamino-1,3,5-
triazine (CAAT). Therefore, if biological processes can be neglected and if the low formation
yields do not prevent detection, DEAOH and DIA could be used as markers of ATZ
direct photolysis and OH reaction, while AN and CAAT could be markers of ATZ reaction
with 3CDOM*. Model predictions concerning ATZ phototransformation were compared
with available field data from the literature. When sufficiently detailed field information
was provided, good agreement was found with the model.
Tipologia CRIS:
03A-Articolo su Rivista
Elenco autori:
Giulia Marchetti; Marco Minella; Valter Maurino; Claudio Minero;
Davide Vione
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