THE AQUEOUS PHOTOLYSIS OF TRICLOPYR

Abstract

The aqueous photolysis of triclopyr was examined in both pH 7-buffered water and natural river water under artificial lights and midsummer sunlight (40°N latitude). The pseudo-first-order half-lives in pH 7-buffered water and natural river water averaged 0.5 and 1.3 d, respectively, at 25°C. Diffuse mercury lamps and midsummer sunlight produced similar rates of triclopyr decay and photoproduct distribution for a given solution. The photolysis of untreated river water produced a significantly different distribution of photoproducts compared to sterile, pH 7-buffered water. The photolysis of triclopyr in river water generated oxamic acid as the major photoproduct and a number of other low-molecular-weight carboxylic acids as minor products. Photolysis in sterile, pH 7-buffered water produced 5-chloro-3,6-dihydroxy-2-pyridinyloxyacetic acid as the major photoproduct, with minor amounts of oxamic acid and other low-molecular-weight acids.