Photodegradation of Antibiotics on Soil Surfaces:  Laboratory Studies on Sulfadiazine in an Ozone-Controlled Environment

Abstract

Among the processes affecting transport and degradation of antibiotics released to the environment during application of manure and slurry to agricultural land, photochemical transformations are of particular interest. Drying-out of the top soil layer under field conditions enables sorption of surface-applied antibiotics to soil dust, thus facilitating direct, indirect, and sensitized photodegradation at the soil/atmosphere interface. For studying various photochemical transformation processes of sulfadiazine, a photovolatility chamber designed in accordance with the requirements of the USEPA Guideline and 161-3 was used. Application of 14C-labeled sulfadiazine enabled complete mass balances and allowed for investigating the impact of various surfaces (glass and soil dust) and environmental factors, i.e., irradiation and atmospheric ozone, on photodegradation and volatilization. Volatilization was shown to be a negligible process. Even after increasing the air temperature up to 35 degrees C only minor amounts of sulfadiazine and transformation products (0.01-0.28% of applied radioactivity) volatilized. Due to direct and indirect photodegradation, the highest extent of mineralization to 14CO2 (3.9%), the formation of degradation products and of nonextractable soil residues was measured in irradiated soil dust experiments using ozone concentrations of 200 ppb. However, even in the dark significant mineralization was observed when ozone was present, indicating ozone-controlled transformation of sulfadiazine to occur at the soil surface.

Influence of pH, inorganic anions, and dissolved organic matter on the photolysis of antimicrobial triclocarban in aqueous systems under simulated sunlight irradiation

“…The degradation rate constants were 0.0365 and 0.0309 h −1 with the addition of 10 and 50 mg/L of NaNO 3 , respectively. This result is different from those of most previous reports that nitrate mainly promoted the photolysis rate of organic pollutants (Wolters and Steffens 2005;Ji et al 2012;Niu et al 2013). In this work, a high amount of acetonitrile was used as solvent in the irradiated solutions.…”

Evaluation of the aquatic toxic effect varied during the degradation of capecitabine under the environmental abiotic and biotic processes

“…Generally, most of the organic pollutants could be disintegrated structurally and even completely mineralized under UV irradiation. 31 Our present results, however, showed that despite the removal rate of CAP reaching up to 50%, there was no signicant change in the TOC content. The high removal rate with low degree of mineralization demonstrated that the target anticancer drug was decomposed into smaller organic molecules rather than carbon dioxide, water, or inorganic salts directly.…”

Depth Distribution of Sulfonamide Antibiotics in Pore Water of an Undisturbed Loamy Grassland Soil

“…The results clearly indicate a fast, not identified transformation process at the soil surface. Other transformation processes like photodegradation have been reported in the literature (Wolters and Steffens, 2005) as well. Under our experimental condition with plots covered by plastic sheets and partially by wood panels just after the application and due to the strong light absorption in manure we consider this process to be negligible.…”

“…Besides the acetylated transformation products, other metabolites are known to be formed from SA (Kreuzig and Höltge, 2005; Wolters and Steffens, 2005; Wehrhan, 2006). These were not covered with our analytical method.…”