Hydrolysis, aqueous photolysis and soil degradation of fluroxypyr

The fate of fluroxypyr in the aqueous buffer solutions, natural water and three types of soil was examined under laboratory conditions. The hydrolysis of fluroxypyr was studied in aqueous buffer solutions of pH 4.5 ± 0.1, 7.4 ± 0.1 and 9.0 ± 0.1 at different temperatures (25 ± 2 and 50 ± 2 °C). Fluroxypyr was stable under pH 4.5 ± 0.1 acid condition and its half-lives in pH 7.4 ± 0.1 and 9.0 ± 0.1 buffer solutions at 25 ± 2 °C were 14.9 and 12.7 days, respectively. The chemical hydrolysis of fluroxypyr was both pH and temperature-dependent and accelerated by alkaline conditions and higher temperatures. The photodecomposition rate of fluroxypyr under UV light in aqueous buffer solutions and natural water was much higher than that under sunlight with the half-lives of 0.102–0.705 hour. The half-lives of direct photolysis in pH 7.4 ± 0.1 and 9.0 ± 0.1 buffer solutions were 7.14 and 5.34 days respectively and no significant variations of concentrations could be observed in natural water, distilled water and p...