Increasing lake water and sediment oxygen levels using slow release peroxide
2012
Nykänen, Anne | Kontio, Heidi | Klutas, Oskari | Penttinen, Olli-Pekka | Kostia, Silja | Mikola, Juha | Romantschuk, Martin
The sediment and hypolimnion of many Finnish lakes suffer from anoxia due to increasing nutrient loading. The aim of this research was to develop a method for increasing the oxygen level using granulated calcium peroxide (CaO₂) as a slow oxygen releasing compound. This compound releases oxygen (O₂) in a reaction with water during 5 to 7months. The method was tested in both laboratory and field conditions. In the field test granulated CaO₂ were then spread manually from a rowing boat over the whole surface of the test pond. The granules sink onto and into the sediment. No mixing was needed. The dissolved oxygen concentration increased significantly during a laboratory experiment with a CaO₂ amendment of 75gm⁻² and in a pond experiment with a CaO₂ amendment of 50gm⁻². In the pond experiment, the effect was visible for the entire 40-week experiment. In the laboratory, the abundance of aerobic bacteria increased in the sediment after CaO₂ addition, while the pond experiment gave more mixed results. The organic matter content of the sediment did not change during the experiment in the control pond, but decreased from 18% to 4% in the pond with the CaO₂ amendment. This was possibly due to enhanced microbial activity in the test pond. Although the results show improved oxygen concentrations and effects on the sediment organic matter following CaO₂ amendment, the usability of this method in larger lakes remains to be tested.
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