Pesticides are important for increased crop productivity, but their regular application onto agricultural lands makes them of particular interest to those studying the environmental fate of anthropogenic chemicals. Indeed, pesticides are ubiquitously detected in natural waters as well as in water supplies, which suggests we may have an incomplete understanding of some pesticides’ transport and degradation. In this research, the photochemical fate of fungicides, which account for approximately 50% of pesticide usage in Europe and 10% in the US, was investigated. Eighteen commonly used fungicides were selected and their susceptibility to both direct and indirect photolysis were quantified including reaction with photochemically produced reactive intermediates (e.g., triplet state dissolved organic matter, singlet oxygen, hydroxyl radical). The comprehensive photochemical half-lives of these chemicals were compared to the values reported in the registration literature. The results of this study show the importance of a complete characterization of the photolytic degradation of chemical if the environmental fate of these chemicals is to be understood. In particular, the fungicides fludioxonil and fenhexamid are highlighted as case studies to demonstrate the importance of understanding the photolytic fate of agrochemicals. Additionally, a protocol of photochemical experiments was devised in order to accurately and quickly assess both direct and indirect photolysis.<br/>

Accurately evaluating the photolytic fate of agrochemicals in natural waters

256th National Meeting (2018)

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