New paper on urban stormwater nutrients control by bioretention cells

In a new paper published in Journal of Hydrology, Bowen Zhou and co-authors explore how efficient are bioretention cells (BRCs) in controlling phosphorus (P) and nitrogen (N) enrichment of urban stormwater by analyzing the data extracted from the International Stormwater BMP Database. They find that BRCs on average increase concentrations of P and reduce those of N. Inefficient reduction of P and N concentrations by BRCs implies that P and N load reductions are mostly driven by surface runoff volume reduction via downward exfiltration in these systems, which may deteriorate groundwater quality. Ensuing decreases of stormwater N:P ratios by BRCs due to the more efficient reduction on N concentrations may potentially alter nutrient limitation patterns in receiving aquatic ecosystems. Besides, impacts of BRCs on urban stormwater P and N export are found to be highly variable. Random forest modelling analysis shows that climate, watershed and BRC characteristics modulate variability of these impacts. Bowen Zhou is a former PhD student and postdoctoral researcher in ERG and now a postdoctoral fellow at Georgia Institute of Technology. Coauthors include Chris Parsons, Mahyar Shafii, Fereidoun Rezanezhad and Philippe Van Cappellen from ERG, and Elodie Passeport from Rutgers University.