Sediment and water column phosphorus fractions were recorded monthly for one year (April 2004–April 2005) in a shallow lake recovering from nutrient pollution (Loch Leven, Scotland). Equilibrium phosphate concentration (EPCO) and gross sediment phosphorus (P) release rates were estimated from laboratory experiments. Pore water and organic P pools were lowest during warm water periods whereas bottom water P was lowest during cold water periods. Reductant-soluble, organic, metal oxide-adsorbed, residual and sediment total phosphorus pools all varied significantly with overlying water depth. Short-term, high magnitude, redox initiated P release events occurred in late summer and winter as a result of anoxic sediment conditions. Lower magnitude longterm release conditions were maintained for most of the year, most likely as a result of organic P cycling and maintenance of high concentration gradients between the pore and bottom water P pools. Estimates of summer P uptake/release rates, across an intact sedimentwater interface, suggested that maximum gross internal release was ~12 mg SRP m −2 lake surface area d −1 with EPCO values ranging between 180 and 270 μg P L −1 . This study highlights the biological mediation of internal loading in shallow eutrophic lakes, and in particular, the role of sediment algae in decreasing, and sediment bacteria in enhancing, sediment P release.
CITATION STYLE
Spears, B. M., Carvalho, L., Perkins, R., Kirika, A., & Paterson, D. M. (2007). Sediment phosphorus cycling in a large shallow lake: spatio-temporal variation in phosphorus pools and release. In Shallow Lakes in a Changing World (pp. 37–48). Springer Netherlands. https://doi.org/10.1007/978-1-4020-6399-2_4
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