PREDICTING THE ENVIRONMENTAL FATE OF PHOTOLYTIC COMPOUNDS THROUGH SITE-SPECIFIC CHARACTERIZATION

Despite decades of field, laboratory, and computational efforts, the ability to accurately predict the fate and transport of contaminants in the environment remains limited due to complexities of spatial variability interacting with reactive and biological processes. Our current approach for characterizing environmental fate attempts to understand individual compounds in every probable environmental setting after a release has occurred. The feasibility of this framework is hindered by the presence of thousands of contaminants of emerging concern (CEC) already in the environment and the continuous production of new chemicals being released.

We propose a framework that proactively predicts how any CEC will be transported through a specific environmental setting of critical concern (e.g., a drinking water intake, habitat for endangered species), based on categorization of known chemo-physical properties. To test the validity of this approach, we chose to focus on an individual reactive process (photolysis), and a stream reach upstream of a wastewater effluent. We used a series of conservative and reactive tracers to characterize the stream reach’s potential to limit or exacerbate the transport of photolytic compounds. Tracer experiments were then used to constrain a numerical model of the study reach and estimate the transport of photolytic pharmaceuticals commonly found in wastewater effluent. The model was validated by co-releasing conservative tracers, reactive tracers, and non-regulated photolytic pharmaceuticals. Ultimately, our goal is to apply the results of this preliminary study to more removal mechanisms (sorption/biodegradation) to develop a framework that is more broadly applicable than our current paradigm.