Contrasting nitrogen and phosphorus budgets in urban watersheds and implications for managing urban water pollution
Contrasting nitrogen and phosphorus budgets in urban watersheds and implications for managing urban water pollution
Urban waters remain widely impaired by excess nutrients, despite substantial management efforts. We present a comparison of urban watershed nitrogen (N) and phosphorus (P) budgets. Household actions of lawn fertilization and pet ownership were responsible for the majority of watershed N and P inputs, respectively. N and P exhibited contrasting dynamics within watersheds. Watersheds exported most or all P inputs via stormwater runoff, likely contributing to surface water degradation. High apparent N retention likely resulted from unmeasured watershed N losses to the atmosphere and groundwater. These contrasting dynamics suggest that N management should emphasize reducing watershed inputs, whereas P management should focus on reducing watershed P inputs and transport from vegetated landscapes to streets and storm drains.