Fate Of Sulfamethazine And Its Metabolite In Sandy Loamy Soil

More recently, there has been growing concern about veterinary medicine contamination of environment. Residues of potentially harmful pharmaceutical antibiotics are found in soils and adjacent environmental compartments. Sulfonamides have been detected in the wastewater effluent and surface water. Occurrence and distribution of Sulfamethazine from the pharmaceutical industry had been described in water down-gradient from a contaminated landfill. Antimicrobials, such as Sulfamethazine, are excreted into the environment in an active form, which could potentially alter the population of bacteria in the environment or select for the development of drug-resistant bacteria, which could pose threats to human health. Moreover they could affect mollusk in soil and aquatic animals and plants. The amount of antibiotic excreted by the animal is estimated based upon the antibiotic dosage reported by the UCS and in the Feed Additive Compendium (2000), assuming up to 80 percent of the administered antibiotic is excreted unmetabolized. By combining information on environmental fate with the predicted concentrations, antibiotics of sulfonamides are likely the water contaminants. Sulfamethazine is a commonly antibiotic used extensively in food producing animals for therapeutic and prophylactic purposes. More recently, the residue of Sulfamethazine is very serious and many countries have established a higest tolerance for sulfamides residues in edible animals' tissues. Sulfamethazine and its main metabolite N⁴-acetyl-sulfamethazine can be excrete with manure in environment resulting in the latent threat to it. Laboratory studies were conducted to investigate Sulfamethazine and its metabolite N⁴-acetyl-sulfamethazine with regard to sorption, degradation and mobility in sandy loam Dong beiwangBeijing.A sensitive hige-performance liquid chromatographic methos was developed for the quantitative determination of sulfamthazine and N⁴-acetylsulfamethazine in tested soil samples. Sulfamethazine and N⁴-acetylsulfamethazine were extrated with alkaline sodium chloride aqueous solution followed a by SPE column clean-up procedure. The recoveries of analysts were at fotified level of 20μg·kg^-1, 100μg·kg^-1, 1000μg·kg^-1 from soil sample assay renge from 85.53 % ⁹1.93 % for Sulfamethazine and 90.09% ⁹5.74% for N⁴-acetylsulfamethazine. Detection limits of the assay ere caculated to be three times the baseline noise from drug free sample and the detection limits were 12μg·kg^-1 for sulfamthazine and 15μg·kg^-1 for N⁴ -acetylsulfamethazine. A simple and rapid high performance liquid chromatographic methos for them in water sample was improved. Sulfamethazine and N⁴-acetylsulfamethazine were extracted with ethyl acetate and evaporated to dryness followed with an alumina column clean-up procedure to remove the dye in the profile and other disturbing materials.Sorption was adopted by the batch equilibrium method and sorption isotherms were fitted to the Freundlich equation. The Sorption coefficients (K_f) were low (are respectively 1.0134 and 0.7236). The degradation studies of Sulfamethazine and N⁴-acetyl-sulfamethazine have been performed .The results have also suggested that their degradation were fast both in biodegradation and chemical degradation. The half-life (T_1/2) is short in biodegradation with 3.44 d for Sulfamethazine and 1.58 d forN⁴-acetyl-sulfamethazine, while it is little longer in chemical degradation with 8.93 d for Sulfamethazine and 7.12 d for N⁴-acetyl-sulfamethazine. Moreover, in this study, we have observed that N⁴-acetyI-sulfamethazine (the major metabolite of Sulfamethazine) had the tendency to transform into Sulfamethazine in test soil under the lab condition. Movement of Sulfamethazine and N⁴-acetyl-sulfamethazine using a bromide tracer was studied in packed soil columns in Pexiglas cylinders (about 5 cm internal diameter, 30 cm long) with test soil. Both of the BTCs for Sulfamethazine and N⁴-acetyl-sulfamethazine were asymmetrical with a tail compared with the bromide tracer's. The tim...