Browsing by Author "Finlay, Jacques C"

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    Combined UMN-MPCA 2014-2017 lake data on Secchi depth, CDOM, Chlorophyll and total suspended solids
    (2019-01-15) Brezonik, Patrick L; Hozalski, Raymond M.; Finlay, Jacques C; brezonik@umn.edu; Brezonik, Patrick L; University of Minnesota Water Quality by Remote Sensing Group
    This file contains approximately 1460 records on four water quality variables measured on near-surface water samples of lakes in Minnesota (primarily) and also in Wisconsin and Michigan collected by our research group from 2014 to 2017 and similar data collected by the Minnesota Pollution Control Agency in its annual lake water quality assessment program from 2015 to 2017. The variables are Secchi depth (SD), colored dissolved organic matter (CDOM) measured as the Napierian light absorption coefficient at 440 nm, chlorophyll-a, and total suspended solids concentrations. The database was used for a published paper to analyze the effects of CDOM on SD and show that high CDOM levels limit light penetration and thus SD in colored lakes.
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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.
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    Effect of dissolved iron on CDOM and other optical properties for dissolved organic matter in lakes and rivers of the Upper Great Lakes states
    (2019-01-23) Brezonik, Patrick L; Finlay, Jacques C; Hozalski, Raymond M; brezonik@umn.edu; Brezonik, Patrick L
    These files contain the raw field and lab data collected during sampling of lakes and a few rivers in 2014-2016 to evaluate the importance of dissolved iron concentrations in affecting apparent levels of colored dissolved organic matter (CDOM), as measured spectrophotometrically by light absorption coefficient at 440 nm, a(440), with additional sampling in 2018 for more specific purposes. Approximately 450 sets of measurements were made on 280 lakes/rivers during the field seasons of 2014-2016, with most of the sampling in two ecoregions of Minnesota -- the Northern Lakes and Forests (NLF) and the North Central Hardwood Forests (NCHF). Additional samples collected in these two ecoregions in neighboring Wisconsin and Michigan in 2016 and in the Northern Minnesota Wetlands (NMW) ecoregion of Minnesota also are in the database. Data collected in 2018 included depth profiles of a(440), iron, dissolved organic carbon (DOC), and basic water quality parameters on three NLF lakes and samples on about 20 colored lakes and rivers to evaluate the importance of particulate iron as a component of total iron. Experimental data for addition of dissolved iron (Fe(III)) to six lakes also is included.