Speciation and Transport of Phosphorus in Source Area Rainfall–Runoff

Abstract

Phosphorus (P) delivered by urban rainfall-runoff partitions and speciates during the transport process. This study examines transport and speciation of P in rainfall and runoff across 15 wet weather events from a paved source area dominated by biogenic loads and to a lesser degree, anthropogenic loads. The mean and median event-based source area total phosphorus is 3.6 and 3.5 mg/l, respectively. The mean and median event-based source area dissolved fraction (f d ) are 0.31 and 0.32 illustrating that P is predominately bound to particulate matter fractions. The majority of events across the monitoring campaign produce a weak mass-limited transport of dissolved phosphorus (DP). With respect to the DP fraction in runoff (pH range of 6.4 to 8.6), the dominant species are orthophosphates (HPO 4 −2 and H 2 PO 4 − ) which account for more than 90% of DP mass. The order of species predominance is consistently HPO 4 −2 ≈H 2 PO 4 − >>CaHPO 4 >MgHPO 4 . With rainfall pH ranging from 4.2 to 4.9 and a f d ≈1.0, H 2 PO 4 − accounts for 95% to 99% of DP in rainfall.Despite the inherent variability of a large dataset (362 samples across 15 events) the speciation of DP is influenced primarily by pH, with a range from 4.2 (rainfall) up to 8.6 (runoff) that results in an order of magnitude change in P species concentration and determines the order between the dominant orthophosphate species. For this source area, the role of alkalinity, dissolved organic carbon and partitioning on DP speciation are minor compared to the influence of pH.

Phosphorus Speciation and Treatment Using Enhanced Phosphorus Removal Bioretention

“…The mean and median event-based dissolved fractions (f d = (DP/TP)) are 0.31 and 0.28, illustrating that PP is the dominant species in surface runoff, which is in accordance with research by Berretta and Sansalone 34 . After passage through the bioretention media, the mean and median f d in discharge increased to 0.67 and 0.68, indicating that PP removal is better than that of DP.…”

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

“…fertilizers, pet waste, automotive detergents), and biogenic materials (i.e. lawn clippings and leaves) 12 – 16 . Source tracking studies in urban waters have shown that atmospheric deposition 17 , 18 , lawn fertilizers 15 , 18 , landscape irrigation 19 , and sewage 20 can contribute significant N to waterways.…”

Water Quality Monitoring with Emphasis on Estimation of Point and Diffuse Pollution Sources

“…Also, it is indicated that phosphorus and suspended solids are highly correlated in agricultural watersheds (Wall et al, 1996). Other sources of phosphorus are detergents, biogenic materials, animal wastes, natural P-containing soils, human and animal excrements, food-processing wastes, atmospheric deposition and runoff from urban areas (Berretta and Sansalone, 2011;Coulter et al, 2004). Urban watersheds typically carry 5 to 20 times as much phosphorus per unit area per year, as compared to undeveloped watersheds in a given region (Walker, 1987).…”