Degradation of the anilide fungicide inpyrfluxam in illuminated water-sediment systems

The degradation behavior of inpyrfluxam (1) was investigated in aerobic aquatic water-sediment systems exposed to continuous artificial sunlight (λ>290 nm). Under irradiation in the presence of sediment, 1 preferentially underwent oxidation at the 1'- and 3'-positions of the indane ring, followed by cleavage of the amide linkage with the half-life of 16-18 days, and finally mineralized to carbon dioxide or exhibited extremely strong adsorption to sediment. Especially, as compared to systems kept in darkness, carboxylation at the 1'-position of the indane ring was remarkably accelerated in illuminated water-sediment systems and the aqueous photodegradation study due to the presence of photosynthetic microorganisms in the sediment soil. No significant degradation products were observed in the water-sediment in darkness and in the sterilized water-sediment under irradiation throughout the study. The fate of 1 and its degradation products in illuminated water-sediment systems was considered to better reflect realistic conditions, as it accounts for various effects attributed to sunlight, such as the presence of photosynthetic microorganisms.