Stormwater runoff driven phosphorus transport in an urban residential catchment: Implications for protecting water quality in urban watersheds

Abstract

Increased stormwater runoff in urban watersheds is a leading cause of nonpoint phosphorus (P) pollution. We investigated the concentrations, forms, and temporal trends of P in stormwater runoff from a residential catchment (31 low-density residential homes; 0.11 km2 drainage area) in Florida. Unfiltered runoff samples were collected at 5 min intervals over 29 storm events with an autosampler installed at the stormwater outflow pipe. Mean concentrations of orthophosphate (PO4–P) were 0.18 ± 0.065 mg/L and total P (TP) were 0.28 ± 0.062 mg/L in all runoff samples. The PO4–P was the dominant form in >90% of storm events and other–P (combination of organic P and particulate P) was dominant after a longer antecedent dry period. We hypothesize that in the stormwater runoff, PO4–P likely originated from soluble and desorbed pool of eroded soil and other–P likely originated from decomposing plant materials i.e. leaves and grass clippings and eroded soil. We found that the runoff was co-limited with nitrogen (N) and P in 34% of storm events and only N limited in 66% of storm events, implicating that management strategies focusing on curtailing both P and N transport would be more effective than focussing on only N or P in protecting water quality in residential catchments.

It Is Not Easy Being Green: Recognizing Unintended Consequences of Green Stormwater Infrastructure

“…The roofing and siding materials of buildings can leach metals to stormwater [51]. Lawns can contribute solids through grass clippings and other vegetative matter, and, when these decompose, they can release nutrients [53]. Fertilizer from urban turf areas also adds nutrients to runoff.…”

Reducing leaf litter contributions of phosphorus and nitrogen to urban stormwater through municipal leaf collection and street cleaning practices

“…A comparison of inputs, outputs, and retention of nitrogen in seven urban watersheds with street tree canopy ranging from 20 to 36 percent showed an area-weighted watershed mean of 80 percent retention of net nitrogen inputs, with primary losses via leaching to groundwater (Hobbie and others, 2017). Nitrogen has also been shown to be linked to dynamic microbial gutter processes and landscape practices that promote denitrification (Yang and Toor, 2018;Hobbie and others, 2014). In contrast, other studies recognize vegetation as an abundant source of nitrogen, although uncertainty in speciation tends to fluctuate between particulate and dissolved forms (Taylor and others, 2005).…”

“…The combined effect of phosphorus and nitrogen enrichment from accelerated expansion of urban land use has resulted in increased eutrophication, higher occurrence of harmful algal blooms, and loss in recreational value for receiving water bodies across the world (Moore and others, 2003;Yang and Toor, 2018;Wurtsbaugh and others, 2019) The most effective management actions to reduce these negative effects are continued efforts to reduce enriched phosphorus and nitrogen from entering our waters (Gilbert and Burford, 2017). Understanding the sources and abundance of nutrients in the urban landscape, and mobility to storm drains is an important step in developing management plans.…”

Increasing Sustainability of Residential Areas Using Rain Gardens to Improve Pollutant Capture, Biodiversity and Ecosystem Resilience

“…Low impact development (LID) has gained popularity as a tool to increase local sustainability, resiliency and improve ecosystem health [4][5][6][7][12][13][14]. LID uses an approach that mimics natural hydrology practices through small, site-scale, cost-effective landscape features that soak up, hold, convey, and filter stormwater onsite [7,12,15,16].…”

“…Rain gardens are known to filter around 90 percent of copper, lead and zinc; 50 percent of nitrogen; and 65 % of P, which could otherwise flow into storm drains and eventually bodies of water [29,30]. Nitrogen (N) and P (P) are of particular concern and interest in urban stormwater runoff due to their role in eutrophication of water bodies, onset of harmful algal blooms, and fish kills [13,31,32]. Traditionally, a rain garden is constructed as a shallow depression in the landscape that receives runoff during a storm event.…”