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M. Dittrich, O. Gabriel, C. Rutzen, R. Koschel:
"Lake restoration by hypolimnetic Ca(OH)2 treatment: Impact on phosphorus sedimentation and release from sediment";
Science of the Total Environment, 409 (2011), 8; 1504 - 1515.

Awhole-lake hypolimnetic Ca(OH)2 addition, that induced calciumcarbonate precipitation, combinedwith deep
water aeration has been applied to eutrophic Lake Luzin, Germany during 1996-1998. In this study we
investigated the dynamic of phosphorus and its binding forms in seston and sediment before and during the
treatment. The sedimentation rates of phosphorus increased within three years of induced calcite precipitation.
The phosphorus binding forms shifted to the calcite-bound phosphorus in the settling matter. The increase of
calcite-bound P in the settlingmaterial did not coincide with the maximuminduced CaCO3-precipitation caused
by the hypolimnetic addition of Ca(OH)2. An impact of chemicals additions and pH on phosphorus binding forms
in seston and surface sediments has been studied in laboratory experimentswith sediment core incubations and
slurry experiments.
Laboratory studies showed that the lowest phosphorus flux from sediment was related to the experiment with
pH=7 in overlaying water adjusted with Ca(OH)2. The adjusting of pH with Ca(OH)2 leads to a lower P flux of
2.3 mg Pm−2d−1, while the highest P-flux is attributed to the experiment with the pH whichwas adjusted with
NaOH. Phosphorus fraction which reflects phosphorus binding on carbonates in surface sediments increased
within one year of treatment, enhancing the phosphorus retention capacity of sediments.