Photodegradation of sulcotrione in various aquatic environments and toxicity of its photoproducts for some marine micro-organisms.
Photochemical behaviour of sulcotrione, a triketone herbicide, was studied in a variety of aqueous solutions including natural waters (sea and river) under laboratory conditions. Photodegradation experiments were carried out under two irradiation systems (UV-B and simulated solar radiation) in order to evaluate kinetics of active ingredient. The degradation kinetics, more rapid under UV-B radiation than solar simulator, followed a first-order reaction (photolysis half-lives ranged between 3 and 50 h) and appeared strongly dependent on water origin, pH value and molecular structure of the herbicide. Dissolved organic matter showed a retarding effect while low concentrations of nitrate ions had no effect on photolysis rate. Identification of photoproducts indicated that hydrolysis, a pH-dependent process (no degradation at pH >6 but at pH=3, k=0.0344 h(-1)), could be photoassisted. These results were compared to those of mesotrione, another triketone herbicide, which appeared more stable under UV-B irradiation. Toxicological studies on two marine heterotrophic bacteria and one cyanobacterium showed absence of effects up to 100 microgL(-1) for both sulcotrione and its photoproducts.
Chaabane
Hanène
H
Laboratoire de Chimie des Biomolécules et de l'Environnement, Centre de Phytopharmacie, Université de Perpignan, 52 av. Paul Alduy, 66860 Perpignan, France. chaabane@univ-perp.fr
Vulliet
Emmanuelle
E
Joux
Fabien
F
Lantoine
François
F
Conan
Pascal
P
Cooper
Jean-François
JF
Coste
Camille-Michel
CM
D002244:Carbon / Q000032:analysis; D003512:Cyclohexanones / Q000528:radiation effects* / Q000633:toxicity; D020632:Halomonas / Q000187:drug effects / Q000254:growth & development; D006540:Herbicides / Q000528:radiation effects* / Q000633:toxicity; D006863:Hydrogen-Ion Concentration; D008698:Mesylates / Q000528:radiation effects* / Q000633:toxicity; D009566:Nitrates / Q000032:analysis; D009573:Nitrites / Q000032:analysis; D010710:Phosphates / Q000032:analysis; D010782:Photolysis; D045483:Rivers; D012623:Seawater; D046939:Synechocystis / Q000187:drug effects / Q000254:growth & development; D014466:Ultraviolet Rays; D014733:Vibrio / Q000187:drug effects / Q000254:growth & development; D014874:Water Pollutants, Chemical / Q000528:radiation effects* / Q000633:toxicity
D003512:Cyclohexanones; D006540:Herbicides; D008698:Mesylates; D009566:Nitrates; D009573:Nitrites; D010710:Phosphates; D014874:Water Pollutants, Chemical; C432907:mesotrione; C079906:sulcotrione; D002244:Carbon