Aquatic photochemistry of the sulfonamide antibiotic sulfapyridine

- Photolysis is a major removal mechanism of sulfapyridine in aquatic systems.
- Direct photolysis rates were highly dependent on pH; increasing with degree of deprotonation.
- Indirect photolysis, assessed using natural waters, contributed significantly to degradation.
- Two photoproducts of sulfapyridine were identified; SO2-extrusion and OH-addition products.