Grant: Discovery Grants Program - Individual

Canadians produce approximately 660,000 metric tons of dry sewage biosolids each year. With the application of these biosolids in sustainable agriculture comes the risk of environmental contamination from residual contaminants remaining in the sewage sludge. Pharmaceuticals consumed by humans are not always completely metabolized, with up to 70% of the excreted molecules unchanged and therefore chemically and biologically active. While wastewater treatment plants ensure sufficient removal of pathogens, they may not treat therapeutic and recreational drugs or other organic contaminants from domestic and industrial sources. Recycling sewage sludge to agricultural land releases those pharmaceuticals to the environment with subsequent risks to soil and aquatic ecosystems and the potential to enter drinking water sources with subsequent risks to human health. Even extremely low concentrations of pharmaceuticals in aqueous environments have proven detrimental to sensitive ecosystems, therefore understanding their mobility could aid us in mitigating these micro-pollutants as well as informing policy at wastewater treatment plants and in agricultural use of biosolids in sustainable farming. The overall goal of my research program is to develop a better understanding of the mobility of pharmaceuticals in the environment, including how they interact with environmental surfaces and colloids (i.e. minerals, organic matter, bacteria) and the pathways and nature of breakdown products that may be released to or formed in the environment. To understand these interactions, pharmaceutical sorption experiments will be conducted on single component systems (minerals, bacteria, organic materials) as a function of time, pH, and pharmaceutical concentration. Pharmaceuticals remaining in solution, as well as any breakdown products, will be quantified using high-performance liquid chromatography mass spectroscopy. The binding environment of the pharmaceuticals at solid surfaces will be investigated using Fourier transform infrared spectroscopy. Further, Raman spectroscopic imaging will be used to develop a better understanding of the spatial distribution of pharmaceuticals in complex, multi-component systems, such as natural soils. This would be one of the first research programs to quantify the sorptive behaviour of pharmaceuticals and their breakdown products in the environment, critical to the development of predictive models of pharmaceutical contaminant mobility. This work would greatly improve our understanding of how pharmaceuticals interact with bacteria, minerals, and organic matter, crucial to predicting their fate if released from biosolids applied to agricultural land.