• DOI:10.1002/etc.5620200305
• Corpus ID: 21575699

Fate and kinetics of carfentrazone‐ethyl herbicide in California, USA, flooded rice fields

@article{Ngim2001FateAK,
  title={Fate and kinetics of carfentrazone‐ethyl herbicide in California, USA, flooded rice fields},
  author={Kenley K. Ngim and Donald G. Crosby},
  journal={Environmental Toxicology and Chemistry},
  year={2001},
  volume={20}
}

• K. Ngim, D. Crosby
• Published 1 March 2001
• Medicine, Chemistry
• Environmental Toxicology and Chemistry

Little is known of the environmental fate of the aryltriazolinone herbicide carfentrazone‐ethyl (compound I). Rice field applications of Shark® 40D commercial formulation to duplicate 5.7 m2 rings (119 g a.i./ha) and 464 m2 commercial basins (224 g a.i./ha) produced pseudo–first‐order half‐lives (t½) of 6.5 to 11.1 h in water and 37.9 to 174 h in sediment. The rapid dissipation from water was due to its hydrolysis to the chloropropionic acid (compound II), which further degraded to its propionic, cinnamic, and benzoic acids. Compound I degraded similarly in soil, but propionic and cinnamic acid levels were higher. Compound I was only weakly adsorbed, but lateral movement of compound II through soil occurred. Laboratory hydrolysis produced quantitative yields of compound II, t½ values of 131 h at pH 7 and 3.36 h at pH 9, and slow dissipation at pH 5 (43% at 830 h). Ultraviolet (UV) irradiation of compound I in pH 7 buffer gave dissipation rates similar to those in dark controls (t½ 113 h vs 128 h), while compound II was comparatively stable to photolysis (t½ 765 h) and also did not volatilize from water. Ester hydrolysis followed by off‐site movement of the acid (compound II) account for the dissipation of compound I.