|Moorman, Thomas - Tom|
Submitted to: USDA-CSREES National Water Quality Conference
Publication Type: Abstract Only
Publication Acceptance Date: 11/2/2007
Publication Date: 2/3/2008
Citation: Coats, J.R., Henderson, K.L., Bidwell, J.R., Cooper, N.L., Seery, C.R., Aga, D.S., Moorman, T.B. 2008. Fate and Ecotoxicology of Veterinary Macrolide and Sulfonamide Antibiotics in Surface Water. USDA-CSREES National Water Quality Conference. Available: http://www.soil.ncsu.edu/swetc/waterconf/2008/home08.htm
Technical Abstract: Antibiotics are carried from manured lands and production sites in runoff to surface waters. Our objectives were to assess the environmental fate and ecotoxicology of two macrolide antibiotics (tylosin and erythromycin) and sulfamethazine. Experiments were designed to simulate Midwestern farm pond conditions. Acute and chronic bioassays were conducted to determine the effects of single, binary and tertiary mixtures of sulfamethazine, tylosin and erythromycin on two species of cladocerans, Daphnia magna and Ceriodaphnia dubia. Acute bioassays (48-h) with binary and tertiary mixtures showed effects in both species at concentrations significantly lower than with each chemical alone, but the effects are less than additive. Preliminary studies of each chemical on 10-d survival and reproduction of Daphnia spp. show effects levels falling significantly below those found in the acute bioassays. In microcosms containing pond water and sediment, [14C-phenyl]-sulfamethazine has a 2.7-d half-life in pond water and 4.7-d half-life when added to the water with a dilute manure solution. Sulfamethazine concentrations in sediment accounted for 10 to 15% of the applied antibiotic within 14 days, then declined thereafter. Sulfamethazine is transformed mainly into sediment-bound residue (40 to 60%) and smaller amounts of photoproducts, metabolites, and 14CO2. Results from the studies investigating sorption of tylosin on the sediments collected from the same ponds used in the microcosm study showed that while the Kd of tylosin did not change significantly with pH in the Iowa pond sediment (log Kd=2.52 at pH 9 to log Kd=2.82 at pH 3), the Kd values increased (log Kd=2.14 at pH 9 to log Kd-3.26 at pH 3) in the Oklahoma pond sediment as the pH is decreased. Future experiments will address longer-term toxicology testing, adsorption and desorption to soils and sediments, and the use of the aquatic worm Lumbriculus to assess bioavailability of antibiotics.