title: Photodegradation behaviour of sethoxydim and its comercial formulation Poast®under environmentally-relevant conditions in aqueous media. Study of photoproducts and their toxicity.
abstract: Photolysis is an important route for the abiotic degradation of many pesticides. However, the knowledge of the photolytic behaviour of these compounds and their commercial formulations under environmentally-relevant conditions are limited. The present study investigated the importance of photochemical processes on the persistence and fate of the herbicide sethoxydim and its commercial formulation Poast®in aqueous media. Moreover, the effect of important natural water substances (nitrate, calcium, and ferric ions) on the photolysis of the herbicide was also studied. The results showed that additives existing in the commercial formulation Poast®accelerated the rate of photolysis of sethoxydim by a factor of 3. On the contrary, the presence of nitrate and calcium ions had no effect on the photodegradation rate while ferric ions resulted in an important decrease in the half-life of sethoxydim possibly due to the formation of a complex. Different transformation products were identified in the course of sethoxydim irradiation and the effect of experimental conditions on their concentrations was investigated. Finally, Microtox®test revealed that aqueous solutions of sethoxydim photoproducts increased the toxicity to the bacteria Vibrio fischeri.
authors.affiliation: Unit of Plant Protection Products, INIA, Ctra. de La Coruña, Km. 7.5, 28040 Madrid, Spain.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Sevilla-Morán
authors.affiliation: Ingeniería Química, Facultad de Ciencias, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain.
authors.forename: Luisa
authors.initials: L
authors.lastname: Calvo
authors.affiliation: Unit of Plant Protection Products, INIA, Ctra. de La Coruña, Km. 7.5, 28040 Madrid, Spain.
authors.forename: Carmen
authors.initials: C
authors.lastname: López-Goti
authors.affiliation: Unit of Plant Protection Products, INIA, Ctra. de La Coruña, Km. 7.5, 28040 Madrid, Spain.
authors.forename: José L
authors.initials: JL
authors.lastname: Alonso-Prados
authors.affiliation: Unit of Plant Protection Products, INIA, Ctra. de La Coruña, Km. 7.5, 28040 Madrid, Spain. Electronic address: sandin@inia.es.
authors.forename: Pilar
authors.initials: P
authors.lastname: Sandín-España
mesh_terms: D048908:Aliivibrio fischeri / Q000187:drug effects; D003512:Cyclohexanones / Q000737:chemistry* / Q000633:toxicity; D004784:Environmental Monitoring; D006540:Herbicides / Q000737:chemistry* / Q000633:toxicity; D010782:Photolysis; D013472:Sunlight; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000633:toxicity
chemical_list: D003512:Cyclohexanones; D006540:Herbicides; D014874:Water Pollutants, Chemical; C049437:sethoxydim
keywords: Degradation products; Indirect photolysis; Poast(®) formulation; Sethoxydim herbicide; Toxicity