Modelling Temporal and Spatial Transportation of Pharmaceuticals, Personal Care Products, and Endocrine Disrupting Compounds in a Canadian Watershed
Hosseini, Nasim Alsadat
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Temporal and spatial concentrations of several pharmaceuticals and personal care products (PPCPs), and endocrine disrupting compounds (EDCs) are predicted in the Grand River watershed using a novel version of the PhATE (Pharmaceutical Assessment and Transport Evaluation) model code, which is adapted to explicitly consider Canadian conditions. Specific PPCPs and EDCs previously measured in the Grand River watershed in Ontario, Canada, are selected as the target compounds for this study. Due to observed seasonal variability in climate, hydrology, and pharmaceutical loadings at the case study location, predicting seasonal concentrations of each chemical is expected to improve simulation results and the PhATE model is modified accordingly. In this regard, required seasonal hydrological parameters (i.e. flow rate and velocity) are estimated based on site data. Furthermore, chemical loss parameters (i.e. in-stream decay, human loss, and removal efficiency of treatment plants) are extracted from the literature and then calibrated to observed seasonal behaviour. Calibration parameters for the case study include in-stream decay, human loss, and removal efficiency of three different types of treatment plants. Simulated concentrations are validated by comparing them with measured data at two previously sampled locations in the Grand River. In general, the PhATE model, when modified to account for seasonal variability, accurately simulates pharmaceutical concentrations in the Grand River. The validated PhATE model is used in a predictive mode to identify streams and stream segments with high potential risk of being exposed to the selected PPCPs and EDCs in the watershed in different seasons. Results suggest that a portion of the Grand River extending from the effluent of Waterloo and Kitchener wastewater treatment plants down to the municipality of Brantford is likely to be at higher risk, relative to other portions of the watershed. Moreover, the potential for PPCP toxicity to aquatic species is assessed using the maximum simulated concentrations for the Grand River watershed. According to regulatory guidelines developed by the European Union (EU), most of PPCPs are predicted to be at concentrations that require further assessment and/or more stringent regulations and restrictions.