Characterization and modeling of phosphorus cycling in an urban bioretention cell
Abstract
Phosphorus (P) concentrations in urban stormwater runoff are typically elevated compared to those associated with runoff from natural lands. Urban P export is a leading driver of eutrophication problems in downstream aquatic systems. Low impact development (LID) options such as bioretention cells (Bio-C) have emerged as a green solution for reducing peak discharge and nutrient export from urban areas. Despite the prevalent implementation of Bio-C worldwide, the mechanistic understanding of P cycling in these systems remains limited. This is especially true in cold climate regions where winter-associated processes can play a crucial role in the performance of Bio-C. We conducted data mining and numerical reactive transport modeling to simulate the fate and transport of P in a monitored Bio-C system in the Toronto metropolitan area, Ontario, Canada. Our aim is to utilize the model for predicting the export fluxes and speciation of P from the Bio-C following precipitation events of variable magnitude and duration. Our model development differs from existing models by the incorporation of a more detailed representation of the biogeochemical processes controlling the reactive transport and speciation of P in the Bio-c system. We employ our model to predict temporal variations in the Bio-Cs P retention, outflow and exfiltration. the modeling work is paired with the sequential chemical extraction of P from soil samples taken from the Bio-C to characterize different P pools in the cell media. We then use these data to verify the model predicted P accumulation rates. In ongoing work, we are using the improved predictive understanding of P cycling in the Bio-C to analyze how P retention and export may change under the more hydrologically extreme conditions projected for southern Ontario in the coming decades.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFMGC35L0826Z