Impact of point-source pollution on phosphorus and nitrogen cycling in stream-bed sediments

Elizabeth J. Palmer-Felgate, Robert J.G. Mortimer, Michael D. Krom, Helen P. Jarvie

Research output: Contribution to journalArticlepeer-review

Abstract

Diffusive equilibration in thin films was used to study the cycling of phosphorus and nitrogen at the sediment - water interface in situ and with minimal disturbance to redox conditions. Soluble reactive phosphate (SRP), nitrate, nitrite, ammonium, sulfate, iron, and manganese profiles were measured in a rural stream, 12 m upstream, adjacent to, and 8 m downstream of aseptic tank discharge.Sewagefungus adjacent to the discharge resulted in anoxic conditions directly above the sediment. SRP and ammonium increased with depth through the fungus layer to environmentally significant concentrations (440 and 1800 μM, respectively) due to release at the sediment surface. This compared to only 0.8 μM of SRP and 2.0 μM of ammonium in the water column upstream of the discharge. Concomitant removal of ammonium, nitrite and nitrate within 0.5 cm below the fungus - water interface provided evidence for anaerobic ammonium oxidation (anammox). "Hotspots" of porewater SRP (up to 350 μM) at the downstream site demonstrated potential in-stream storage of the elevated P concentrations from the effluent. These results provide direct in situ evidence of phosphorus and nitrogen release from river-bed sediments under anoxic conditions created by sewage-fungus, and highlight the wider importance of redox conditions and rural point sources on in-stream nutrient cycling.

Original languageEnglish
Pages (from-to)908-914
Number of pages7
JournalEnvironmental Science and Technology
Volume44
Issue number3
DOIs
StatePublished - 1 Feb 2010
Externally publishedYes

ASJC Scopus subject areas

  • General Chemistry
  • Environmental Chemistry

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