Seasonality in phosphorus release rates from the sediments of a hypereutrophic lake under a matrix of pH and redox conditions

Michael R. Penn, Martin T. Auer, Susan M. Doerr, Charles T. Driscoll, Carol M. Brooks, Steven W. Effler

Research output: Contribution to journalArticlepeer-review

91 Scopus citations


Phosphorus release rates were measured on intact sediment cores collected from the major depositional basin of Onondaga Lake, a dimictic, calcareous, hypereutrophic system in Syracuse, N.Y., U.S.A. Release experiments were conducted under a matrix of redox and pH conditions to investigate the importance of Ca- and Fe-related physicochemistry on sediment cores collected seasonally, i.e., during the spring, summer, fall, and winter periods. Strong seasonal variation in P release was observed, with rates ranging from ~3 to 38 mg P·m-2-day-1. This variation is attributed to changes in redox status and P concentration gradients at the sediment-water interface. An oxidized microlayer at the sediment-water interface partially inhibits sediment P release under isothermal, well-mixed conditions in the spring and fall. Phosphorus trapped in the oxic microlayer (sorption) is freed when the microlayer is chemically reduced at the onset of anoxia and high P release rates are observed. The oxidized microlayer serves to regulate seasonality in rates of sediment P release but does not influence long-term sediment-water exchange. It is proposed that the long-term P release process is best represented by a time-weighted annual average rate, calculated here to be ~10 mg P·m-2·day-1.

Original languageEnglish (US)
Pages (from-to)1033-1041
Number of pages9
JournalCanadian Journal of Fisheries and Aquatic Sciences
Issue number5
StatePublished - 2000

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Aquatic Science


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