Open AccessInternal loading in stormwater ponds as a phosphorus source to downstream waters
Author(s) -
Taguchi Vinicius J.,
Olsen Tyler A.,
Natarajan Poornima,
Janke Ben D.,
Gulliver John S.,
Finlay Jacques C.,
Stefan Heinz G.
Publication year - 2020
Publication title -
limnology and oceanography letters
Language(s) - English
Resource type - Journals
ISSN - 2378-2242
DOI - 10.1002/lol2.10155
Subject(s) - stormwater , surface runoff , environmental science , eutrophication , phosphorus , sediment , sedimentation , hydrology (agriculture) , environmental chemistry , hypolimnion , nutrient , chemistry , ecology , geology , biology , paleontology , geotechnical engineering , organic chemistry
Abstract We assessed the prevalence and causes of sediment phosphorus (P) release within urban stormwater ponds, a process that may reduce P removal by sedimentation. Data collected from surface water of 98 urban stormwater ponds in Minnesota showed that nearly 40% had median summer total P concentrations in excess of average stormwater runoff (0.38 mg L −1 ), implying effects of internal loading. We sampled seven ponds more intensively and found four were strongly stratified with persistent hypolimnetic anoxia, despite mean depths <2 m. Sediment core incubations revealed that, unlike in most lakes, both labile organic P (NaOH minus persulfate extractions) and redox‐sensitive P (NH 4 Cl and Na 2 S 2 O 4 extractions) contribute to P release. Together, these analyses suggest P accumulated in stormwater ponds is highly susceptible to internal release and potentially contributes to downstream eutrophication. Understanding how frequently these conditions occur and how they affect different P forms is vital to improving pond design and management.