Nitrogen transformations at the sediment-water interface across redox gradients in the Laurentian Great Lakes

Gaston E. Small, James B Cotner, Jacques C Finlay, Rebecca A. Stark, Robert W Sterner

Research output: Contribution to journalArticle

37 Citations (Scopus)

Abstract

The capacity of a lake to remove reactive nitrogen (N) through denitrification has important implications both for the lake and for downstream ecosystems. In large oligotropic lakes such as Lake Superior, where nitrate (NO3 -) concentrations have increased steadily over the past century, deep oxygen penetration into sediments may limit the denitrification rates. We tested the hypothesis that the position of the redox gradient in lake sediments affects denitrification by measuring net N-fluxes across the sediment-water interface for intact sediment cores collected across a range of sediment oxycline values from nearshore and offshore sites in Lake Superior, as well as sites in Lake Huron and Lake Erie. Across this redox gradient, as the thickness of the oxygenated sediment layer increased from Lake Erie to Lake Superior, fluxes of NH4 + and N2 out of the sediment decreased, and sediments shifted from a net sink to a net source of NO3 -. Denitrification of NO3 - from overlying water decreased with thickness of the oxygenated sediment layer. Our results indicate that, unlike sediments from Lake Erie and Lake Huron, Lake Superior sediments do not remove significant amounts of water column NO3 - through denitrification, likely as a result of the thick oxygenated sediment layer.

Original languageEnglish (US)
Pages (from-to)95-108
Number of pages14
JournalHydrobiologia
Volume731
Issue number1
DOIs
StatePublished - Jan 1 2014

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sediment-water interface
Great Lakes
sediments
nitrogen
lake
Lake Superior
denitrification
water
sediment
Lake Erie
lakes
Lake Huron
lacustrine deposit
sediment core
penetration
water column
nitrate
nitrates
oxygen

Keywords

  • Denitrification
  • Laurentian Great Lakes
  • Nitrogen
  • Sediment

Cite this

Nitrogen transformations at the sediment-water interface across redox gradients in the Laurentian Great Lakes. / Small, Gaston E.; Cotner, James B; Finlay, Jacques C; Stark, Rebecca A.; Sterner, Robert W.

In: Hydrobiologia, Vol. 731, No. 1, 01.01.2014, p. 95-108.

Research output: Contribution to journalArticle

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