US EPA

4546917 

Journal Article 

Sediment phosphorus cycling in a large shallow lake: Spatio-temporal variation in phosphorus pools and release 

Spears, BM; Carvalho, L; Perkins, R; Kirika, A; Paterson, DM 

2007 

Yes 

Hydrobiologia
ISSN: 0018-8158
EISSN: 1573-5117 

584 

37-48 

English 

10.1007/s10750-007-0610-0 

WOS:000246583500005 

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 (EPC0) 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 long-term 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 sediment-water interface, suggested that maximum gross internal release was similar to 12 mg SRP m(-2) lake surface area d(-1) with EPC0 values ranging between 180 and 270 mu g 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. 

sediment; phosphorus; mobility; bio-regulation; seasonality 

5th International Symposium on Shallow Lakes 

Dalfsen, Netherlands 

June 5-9, 2005