Chemical Lake Restoration Products: Sediment Stability and Phosphorus Dynamics

Laboratory experiments with sediments from three shallow Danish lakes were conducted to evaluate the effects of chemical lake restoration products during resuspension. Phosphorus (P) removal, sediment stability, sediment consolidation and color reduction were studied over time. The investigated prod...

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Bibliographic Details
Published in:Environmental science & technology 2010-02, Vol.44 (3), p.985-991
Main Authors: Egemose, Sara, Reitzel, Kasper, Andersen, Frede Ø, Flindt, Mogens R
Format: Article
Language:English
Subjects:
Applied sciences
Conservation of Natural Resources
Continental surface waters
Denmark
Environmental Processes
Eutrophication
Exact sciences and technology
Fresh Water - chemistry
Geologic Sediments - chemistry
Lakes
Natural water pollution
Nutrient removal
Organic contaminants
Phosphorus
Phosphorus - chemistry
Phosphorus removal
Pollution
Sediments
Water Pollutants, Chemical - chemistry
Water treatment
Water treatment and pollution
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Summary:Laboratory experiments with sediments from three shallow Danish lakes were conducted to evaluate the effects of chemical lake restoration products during resuspension. Phosphorus (P) removal, sediment stability, sediment consolidation and color reduction were studied over time. The investigated products were aluminum (Al), Phoslock (a commercial bentonite product coated with lanthanum) and a combination of Al covered with bentonite (Al/Ben). All treatments effectively reduced the P concentration in the water. However, the treatments containing Al reduced the P concentration immediately after resuspension, whereas Phoslock required several days after resuspension to reduce the P concentration. Especially Phoslock, but also Al/Ben, increased the sediment stability threshold by 265% and 101%, respectively, whereas Al had no stabilizing effect. The fresh Al floc was resuspended 5× easier than untreated sediment. The largest consolidation of the sediment occurred with addition of Phoslock, followed by Al/Ben, while Al alone had no effect. Enhanced consolidation may be of importance for macrophyte colonisation of organic sediment. Phoslock improved the light climate moderately by removing color, whereas Al was very effective in removing color. Ben/Al showed intermediate effects on color reduction. These findings are important when decisions are made on restoration method for a specific lake, which may be more or less wind exposed.
ISSN:0013-936X
1520-5851
DOI:10.1021/es903260y