Phosphorus release from sediments in hardwater eutrophic lakes: the effects of redox-sensitive and -insensitive chemical treatments |
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Authors: | Kim L Burley Ellie E Prepas & Patricia A Chambers |
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Institution: | Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada;National Water Research Institute, Saskatoon, Saskatchewan, Canada |
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Abstract: | 1. Phosphorus (P) release from bottom sediments is an important source of nutrient enrichment in many lakes in sedimentary basins, such as those in western Canada. On the Boreal Plain, sediment P release is particularly strong during periods of seasonal anoxia. 2. In this study, the effects of reduction–oxidation (redox)-sensitive and -insensitive chemicals on P release were examined in sediment cores collected from three eutrophic lakes. 3. Contrary to expectations, redox-sensitive treatments were no more effective at lowering total phosphorus (TP) in sediment cores than some redox-insensitive treatments. Redox-sensitive treatments with FeCl3 and FeCl3 + O2 reduced TP to 8 and 6%, respectively, of reference concentrations, whereas redox-insensitive treatments with alum or lime + alum reduced TP to 14% of reference concentrations. Lime and O2 treatments reduced TP concentrations to 35 and 52% of reference concentrations, respectively. 4. The fraction of P that adsorbed and co-precipitated with iron and aluminium in the sediment cores was low (non-apatite phosphorus fractions < 5%), suggesting that P release was controlled by apatite solubility and bacterial metabolism. |
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Keywords: | Boreal Plain eutrophic lakes phosphorus release redox mechanisms sediment cores |
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