Zhou, BowenZhou, Bowen2023-05-022023-05-022023-02-23http://hdl.handle.net/10012/19397Bioretention cells (BRCs) have emerged as one of the Green Infrastructure and low impact development (LID) practices to reduce peak discharge and nutrient export in urban areas. Despite growing implementation globally, understanding of P cycling and retention mechanisms in BRC is limited. In this presentation, we present a novel numerical reactive transport model to simulate the fate and transport of P in a BRC system in the greater Toronto metropolitan area. Unlike existing BRC models, our model incorporates a detailed representation of the biogeochemical reaction network that control P cycling and retention within the BRC. We used this model as a diagnostic tool to determine the relative importance of different P removal processes and their contributions to the P accumulation trajectory within the BRC over 8 years of operation. Model results were validated against time series flow data, plus water chemistry and soil filter media P concentration depth profiles measured between 2012 and 2019. A sequential extraction analysis was also applied to soil cores collected in 2019 to validate the model-derived P pools profiles. The model simulations reproduce the total P (TP) and soluble reactive P (SRP) outflow loads with the TP accumulation rate in the soil filter media and the partitioning of P between different soil chemical pools. The simulation results indicate that groundwater recharge is the dominant mechanism responsible for decreasing the surface water discharge from the BRC (63% runoff reduction), which implies potential impact of infiltrated stormwater on groundwater quality. But that bioretention cell is still efficient at reducing P concentration of infiltrated stormwater since accumulation in the soil filter media is the predominant P removal mechanism (57% of TP influx), and the filter media was not saturated after 8 years of operation. Of P retained within the soil filter media, 48% is highly stable, 41% potentially remobilizable, and 11% easily remobilizable. In addition to elucidating P cycling, our model can help to assess the impact of BRC design choices on P retention efficiency and the stability of the retained P within the soil filter media and eventually to predict the P transport to groundwater aquifers.enAttribution-NonCommercial-NoDerivatives 4.0 InternationalbioretentionphosphorusmodellingConference Poster