Guerard, J. J., The Ohio State University, Columbus, USA,
Chin, Y. P., The Ohio State University, Columbus, USA,
Mash, H. ., US EPA, Cincinatti, USA,


Sulfadimethoxine (SDM) and ormetoprim (OMP) comprise Romet 30®, a common antibiotic used in farming channel catfish, and there are concerns regarding their effect on microbial ecosystems. To date the fate of these compounds released into surface waters from aquaculture operations is relatively unknown. The photochemical transformation of SDM and OMP were studied in the presence of dissolved organic matter (DOM) derived from an aquaculture pond and an adjacent stream. We observed differences in the major pathways of analyte photodegradation depending on DOM source. SDM showed a much greater photosensitization in the presence aquaculture DOM samples relative to the stream DOM. The hydroxyl radical production was only partially responsible for the photodegradation of SDM based upon scavenging studies. Further photoreactions in the absence of oxygen resulted in higher reactivity, which we attribute to excited triplet state DOM. The photofate of ormetoprim was also enhanced by the presence of DOM. Indirect OMP photodegradation is shown to be dependent on hydroxyl radical, and possibly singlet oxygen.

Oral presentation

Presentation is given by student: Yes
Session #:SS01
Date: Friday, June 13, 2008
Time: 3:30 PM

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