Browsing by Author "University of Minnesota - St. Anthony Falls Laboratory - Stormwater Research Group"

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    Data for: Internal Loading in Stormwater Ponds as a Phosphorus Source to Downstream Waters
    (2019-04-15) Taguchi, Vinicius J; Olsen, Tyler A; Natarajan, Poornima; Janke, Benjamin D; Gulliver, John S; Finlay, Jacques C; Stefan, Heinz G; ; taguc006@umn.edu; Taguchi, Vinicius J; University of Minnesota - St. Anthony Falls Laboratory - Stormwater Research Group
    Stormwater ponds remove phosphorus through sedimentation before releasing captured water downstream. Internal loading can impair net phosphorus removal but is understudied in these highly modified systems. Using a combination of methods, we assessed the prevalence and potential causes of sediment phosphorus release in urban ponds. In a three-year, 98-pond dataset, nearly 40% of ponds had median water column total phosphorus concentrations exceeding the 95% confidence interval for runoff values (0.38 mg/L), suggesting widespread internal loading. In a subsequent intensive monitoring study of four ponds, strong stratification prevented spring and summer diurnal mixing, resulting in persistent hypolimnion anoxia (<1 mg/L dissolved oxygen). Incubated sediment cores from seven ponds demonstrated high anoxic phosphorus release. Sediment analysis revealed high labile organic and redox-sensitive phosphorus fractions with release potential at anoxia onset. Our analyses suggest phosphorus accumulated in stormwater ponds is highly sensitive to internal loading, reducing net removal and contributing to downstream eutrophication.
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    Detecting phosphorus release from stormwater ponds to guide management and design
    (2021-02-23) Finlay, Jacques C; Gulliver, John S; Janke, Benjamin D; Natarajan, Poornima; Taguchi, Vinicius; Shrestha, Paliza; janke024@umn.edu; Janke, Ben D; University of Minnesota - St. Anthony Falls Laboratory - Stormwater Research Group
    There is growing concern that aging stormwater retention ponds may become net sources of phosphorus (P) to receiving waters. Release of P previously deposited in sediments (i.e. internal loading) is a major contributor to eutrophication in lakes. Stormwater ponds often have high external P loading, and other characteristics that may increase the likelihood of internal loading as ponds age. However, stormwater ponds have received comparatively little research attention, even though they are widely used with the intended goal of permanent immobilization of phosphorus. The ability of these systems to retain phosphorus over their lifespan is essentially unknown. The proposed research will build understanding necessary to assess the capacity of stormwater ponds to retain or release phosphorus in Minnesota’s stormwater pond infrastructure. The projects aim to develop methods for rapid and efficient identification of pond phosphorus release, to guide management of existing ponds, and to reveal factors that underlie poor performance for P removal. The results of this project will be used to inform and improve pond maintenance, pond design and decision making around construction of new ponds, and to ultimately improve the water quality of our lakes, rivers and wetlands.