Dissolved organic matter (DOM) is a ubiquitous class of aquatic molecules; the photoreactivity of DOM varies with DOM composition, which varies spatially and temporally. Irradiation of DOM can lead to production of photochemically produced reactive intermediates (PPRIs), such as triplet-state DOM (*DOM3), singlet-state oxygen (1O2), and carbonate and hydroxyl radicals (CO3●-, ●OH). In sunlit surface waters, PPRIs can be essential to the degradation of persistent organic contaminants via indirect photolysis. In this study, water samples with variable DOM composition were collected from the St. Louis River in northern Minnesota and used to characterize the degradation of atorvastatin (a statin), carbamazepine (an anticonvulsant), venlafaxine (an antidepressant), and DEET (an insect repellent). Direct and indirect rate constants of each target molecule were quantified in specific water samples under simulated sunlight. The quenching molecules l-histidine and 1,4-Diazabicyclo[2.2.2]octane (1O2 quenchers), isopropanol (a radical quencher), and sorbic acid (a *DOM3 quencher), were utilized to determine the rate constants due to each PPRI and specific to each target molecule. In addition, *DOM3 reactivity was probed via anoxic photolysis experiments. Venlafaxine and carbamazepine primarily degrade via reaction with 1O2 and atorvastatin primarily degrades via reaction with *DOM3, while hydroxyl radical is important for DEET indirect photolysis.

Contaminant transformation in the St. Louis River: The role of indirect photolysis

2019 Spring National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.