GEOC 68 |
| Veterinary antibiotics such as oxytetracycline and ciprofloxacin represent organic compounds with multiple functional groups (amine, carboxylic, hydroxyl), each with a distinct pH dependant speciation. Using 30 soils from the eastern U.S, several pure phase metal oxides and aluminosilicates, and combination of batch experiments and infrared spectroscopy, we identify the contribution of each functional group to antibiotic retention in soils, while emphasizing likely mechanisms. Whereas a functional group interacts with soil minerals via one or more mechanisms of interaction (cation exchange, cation bridging, surface complex and electrostatic attraction), a single functional group may define the overall extent of sorption to soil. Additionally, we are able to establish steric and electronic criteria that differentiate the extent of sorption of antibiotics possessing the same dominant functional group. Our studies contribute to an improved understanding of the mechanisms by which complex polar ionogenic organic compounds interact with soil minerals. |
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Physical Chemistry of Soil and Aquifer Systems: A Symposium in Honor of Garrison Sposito
8:15 AM-11:55 AM, Monday, 11 September 2006 Moscone Center -- Room 256, Oral
Division of Geochemistry |