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Title: Effects of alum treatment on phosphorus dynamics and phytoplankton response in Eau Galle Reservoir, Wisconsin
Authors: Water Operations Technical Support Program (U.S.)
Environmental and Water Quality Operational Studies (U.S.)
Barko, John W.
James, William F.
Taylor, William D.
McFarland, Dwilette G.
Keywords: Alum
Nutrient cycling
Water quality
Water Quality
Eau Galle Reservoir
Publisher: Environmental Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Description: Technical Report
Abstract: The hypolimnion of Eau Galle Reservoir, Wisconsin, was treated with aluminum sulfate (alum) in 1986 to reduce excessive phytoplankton production associated with high phosphorus loading from anoxic, profundal sediments. Prior to treatment, internal total phosphorus (TP) loading was 3 to 6 times greater than external TP loading during summer stratification. Periodic increases in epilimnetic TP mass and chlorophyll α concentrations closely corresponded with elevated internal TP. For 1 year following treatment, internal TP loading and concentrations of soluble reactive phosphorus in the hypolimnion were substantially reduced. Abnormally high external TP loading during the stratified period of 1986 sustained high TP mass and chlorophyll in the epilimnion. During the summer of 1987, effects of alum treatment on internal TP loading were essentially negated, as epilimnetic TP mass and chlorophyll remained unchanged from pretreatment years. Sedimentation of external TP inputs, with subsequent alum burial, is believed to have been primarily responsible for reducing the effectiveness of alum in controlling internal TP loading in this reservoir. Following alum treatment in 1986, phytoplankton biomass was less than half that occurring during the previous year; however, it was not significantly different from other years. Subsequent to several years of codominance with blue-green algae, the dinoflagellate Ceratium hirundinella assumed singular dominance in 1985. With the exception of this change in relative dominance (maintained through 1988), the phytoplankton community of Eau Galle Reservoir has been remarkably stable, despite effects of a winter drawdown in 1984, alum treatment in 1986, and climatic (wet versus dry) extremes over the 8-year study period. Without a decrease in phosphorus availability, Ceratium and bluegreen algae are likely to persist as codominants during the summer in this system for many years.
Rights: Approved for public release; distribution is unlimited.
Appears in Collections:Technical Report

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