Long-Term Orthophosphate Removal in a Field-Scale Storm-Water Bioinfiltration Rain Garden

AbstractUnabated runoff from impervious surfaces after rain events is considered a major source of impairment of receiving water bodies. Bioinfiltration storm-water control measures (SCM) have been shown to be effective in reducing runoff and pollutants from urban areas and thus provide a mechanism for protecting downstream sources from erosion and contamination from suspended solids, metals, and nutrients. However, less is known about the loss mechanisms responsible for contaminant removal and the long-term performance of such SCMs. Even less is known of the performance from a vadose zone perspective. The research presented herein examines the long-term (9 year) performance of a bioinfiltration rain garden with specific emphasis on the removal of orthophosphate. Field data indicated clear removal trends for orthophosphate (PO43−P), the bioavailable form of phosphorus, as the storm water infiltrated into the infiltration bed of the rain garden. The median PO43−P concentration decreased from 0.21–0.25  mg/...