Location: Agroecosystems Management ResearchTitle: Sorption and photo degradation processes govern distribution of sulfamethazine in freshwater-sediment microcosms
|CARSTENS, KERI - Iowa State University|
|GROSS, AARON - Iowa State University|
|COATS, JOEL - Iowa State University|
Submitted to: Environmental Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/20/2013
Publication Date: 8/26/2013
Publication URL: https://handle.nal.usda.gov/10113/58915
Citation: Carstens, K.L., Gross, A.D., Moorman, T.B., Coats, J.R. 2013. Sorption and photo degradation processes govern distribution of sulfamethazine in freshwater-sediment microcosms. Environmental Science and Technology. 10877-10883.
Interpretive Summary: The antibiotic sulfamethazine can be transported from manured fields to surface water bodies. We conducted research showing that sulfamethazine concentrations in pond and stream waters are controlled by photodegradation and binding to the sediment. Two photoproducts were measured and one of these compounds is similar to photoproducts identified in previous studies. Sulfamethazine was also degraded by biological process, most likely microorganisms. The addition of diluted manure, such as that found in runoff, increased binding of sulfamethazine in sediments and reduced photodegradation. The accumulation of the photoproducts and sulfamethazine in sediment may have important implications for benthic organisms. This information will be useful to researchers and regulatory agencies concerned with water quality issues.
Technical Abstract: The antibiotic sulfamethazine can be transported from manured fields to surface water bodies. We investigated the degradation and fate of sulfamethazine in surface water using 14C-phenyl-sulfamethazine in small pond water microcosms containing intact sediment and pond water. We found a 2.7-d half-life in pond water and 4.2-d half-life when sulfamethazine was added to the water with swine manure diluted to simulate runoff. Sulfamethazine dissipated exponentially from the water column, with the majority of loss occurring via movement into the sediment phase. Sulfamethazine in sediment accounted for 10-15% of the applied antibiotic within 14 days, and then declined thereafter. Sulfamethazine was transformed mainly into non-extractable sediment-bound residue (40 to 60% of applied radioactivity) and smaller amounts of photoproducts. Biodegradation, as indicated by metabolite formation and 14CO2 evolution, was less significant than photodegradation. Two photoproducts accounted for 15-30% of radioactivity in the water column at the end of the 63-day study; the photoproducts were the major degradates in the aqueous and sediment phases. Other unidentified metabolites individually accounted for <7% of radioactivity in the water or sediment. Less than 3% of applied radioactivity was mineralized to 14CO2. Manure input significantly increased sorption and binding of sulfamethazine residues to the sediment. These results show concurrent processes of photodegradation and sorption to sediment control aqueous concentrations and establish that sediment is a sink for sulfamethazine and sulfamethazine-related residues. The accumulation of the photoproducts and sulfamethazine in sediment may have important implications for benthic organisms.