Fate Of Representative Fluoroquinolone, Macrolide, Sulfonamide And Tetracycline Antibiotics In Subsurface Environments

Municipal wastewater treatment plant effluent and confined animal feeding operations represent important sources of antibiotics to the environment. The last two years have witnessed an increasing number of publications documenting the occurrence of antibiotics in surface waters and groundwater, heightening concern about their presence in the environment. Compared to conventional organic contaminants, little information is available on the environmental behavior of antibiotics. Our ability to predict mobility, fate and effects of antibiotics is hampered by a lack of information on fundamental processes governing their behavior in the environment. The overall goal of this project is to determine the extent to which association of antibiotics with particle-bound and dissolved natural organic matter influences their mobility in soils and subsurface environments. We intend to focus on representative antibiotics from four major classes: fluoroquinolones, macrolides, sulfonamides and tetracyclines. The selected antibiotics have been detected in wastewater influent and effluent in Wisconsin and in streams throughout the U.S. Our specific objectives are to: (1) quantify the extent of sorption of these antibiotics to humic substances associated with hydrous iron and aluminum oxides and smectitic clays; and (2) investigate antibiotic association with dissolved organic matter and how such association facilitates antibiotic transport under unsaturated flow conditions. Our research findings will help in assessing the ability of soils to act as potential sinks for these emerging organic contaminants and increase understanding of their environmental fate and transport characteristics as influenced by particle-bound and dissolved natural organic matter.