Probing the Influence of Veterinary Antibiotics on Boron Retention/ Release Mechanism at the Mineral / Water Interface
Boron (B) is an essential micronutrient required by plants and has a narrow range between its toxicity and deficiency. The fate and mobility of B in the environment is largely controlled by adsorption reactions with various soil constituents and clay minerals forming surface complexes. Biogeochemical cycling of B in the environment is affected by different soil factors like pH, soil texture, organic matter, and presence of competing ions. There is intensive use of antibiotics as veterinary medicines and growth promoters. They may appear in the environment from land applications of manure, sewage, and wastewater effluents. Raising concern on the effect of their residual concentrations as they have been frequently detected in the environment and they may pose a serious threat to the ecosystem. Antibiotic retention in soil may affect the availability of micronutrients such as B, therefore an evaluation of B sorption mechanisms in single ion and in competitive sorption situation is important for predicating its availability in the environment. This study evaluates B competitive sorption with oxytetracycline (OTC) one of the widely used antibiotic in livestock production on clay mineral (kaolinite) and an Al oxide (gibbsite) as a function of pH, and concentrations using in situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and macroscopic study to understand their mechanisms of interaction. Interactions of B on both kaolinite and gibbsite was through inner and outer sphere complexation with stronger adsorption with the trigonal B(OH)3. From the IR spectra there was negligible competition between OTC and B for the adsorption sites. B was seen to have specific adsorption sites on the mineral surfaces. OTC showed stronger competitive effect on both gibbsite and kaolinite surfaces than B. Sorption of OTC on the mineral surfaces showed that OTC forms strong complexes through the -CONH2, phenol group OH, and -N(CH3)2 functional groups. The macroscopic study showed that OTC had little effect on the adsorption of B on gibbsite. With increased organic farming that involves animal manure applications the results from this study are useful in providing fundamental knowledge on the management of micronutrients in the environment in the presence of antibiotics.
Environmental science|Plant sciences|Soil sciences
"Probing the Influence of Veterinary Antibiotics on Boron Retention/ Release Mechanism at the Mineral / Water Interface"
ETD Collection for Tennessee State University.