Degradation of antimicrobials in soils and sediments

The potential for developing and spreading antimicrobial resistance in pathogens is the most important health risk associated with the widespread use of antimicrobials in human medication and in the livestock industry. Residual antimicrobials enter the environment through the discharge of contaminated effluent or through land application of contaminated livestock manure. Many studies have investigated the degradation of antimicrobials in water; however, soils and sediments are also an important environmental matrix as they can act as reservoirs for recalcitrant antimicrobials. This research examines the degradation kinetics of antimicrobials in soils and sediments for two processes, biodegradation and sorption. This paper makes three main research contributions. Firstly, we reviewed the literature to discuss the fate and potential adverse impacts of residual antimicrobials in the environment. Secondly, we examine the important processes governing the environmental fate and transport of residual antimicrobials to highlight trends and contributing factors. Lastly, we developed a multi-level experimental design to study the sorption and biodegradation of five priority antimicrobials (lincomycin, monensin, sulfamethazine, tetracycline, and triclosan) in soils and sediments. The results of this experimental study will be used to model the adsorption and biodegradation kinetics of the target antimicrobials. Soil and sediment samples have been collected from three pristine sites in a Southern Ontario watershed.