Redox changes of iron caused by erosion, resuspension and sedimentation in littoral sediment of a freshwater lake

Gerhardt, Simone; Schink, Bernhard

Redox changes of iron caused by erosion, resuspension and sedimentation in littoral sediment of a freshwater lake

Dateien

Gerhardt_and_Schink_2005.pdfGröße: 346.77 KBDownloads: 637

Datum

2005

Autor:innen

Gerhardt, Simone

Schink, Bernhard

Open Access-Veröffentlichung

Open Access Green

Sammlungen

Biologie

Publikationstyp

Zeitschriftenartikel

Publikationsstatus

Published

Erschienen in

Biogeochemistry. 2005, 74(3), pp. 341-356, 2005. ISSN 0168-2563. eISSN 1573-515X. Available under: doi: 10.1007/s10533-004-4725-3

Zusammenfassung

Depth profiles of oxygen concentration and the redox status of acid-extractable iron were measured in littoral sediment cores of Lake Constance after mechanical removal of surface sediment, mixing, and re-deposition. In undisturbed sediment cores, oxygen penetrated down to 2.9±0.4 mm or 4.6±0.4 mm depth, respectively, after 12 h of incubation in the dark or light; causing a net diffusive flux of 108±20 nmol cm2 h1 oxygen into or 152±35 nmol cm2 h1 out of the sediment. The uppermost 20 mm layer of the undisturbed sediment cores contained 10.2± 0.7 lmol cm3 ferrous and 3.8±1.1 lmol cm3 ferric iron. After erosion, the oxic anoxic interface in the newly exposed sediment was shifted to about 2 mm depth within 30 min, causing an oxygen flow into the sediment. During the following 12 h, oxygen penetrated deeper into the sediment, and in the light oxygen was produced photosynthetically. Ferrous iron was largely oxidized within two days after erosion. The oxidation rates were higher in oxic than in anoxic sediment layers, and decreased with time. This oxidation process took the longer and was confined closer to the surface the more reduced the exposed sediment had been before. Resuspension of eroded sediment in aerated lake water did not cause a significant oxidation or reduction of iron. After re-deposition, the oxic anoxic interface in the re-sedimented material shifted to about 2 mm depth within 30 min, causing an oxygen flow into the sediment. During the following 12 h, the oxygen penetration depth and the oxygen flow rate into the re-deposited sediment did not change any further, and no oxygen was produced in the light. Ferric iron was reduced during the first day after re-deposition, and partly re-oxidized during the second day. The extent of reduction was stronger and the extent of oxidation weaker the more reduced the resuspended sediment was before. Oxic conditions in the sediment surface were established faster and ferrous iron was oxidized to a larger extent after erosion of sediment than after resuspension and sedimentation.

Fachgebiet (DDC)

570 Biowissenschaften, Biologie

Schlagwörter

Erosion, Freshwater sediment, Iron cycle, Oxygen, Resuspension, Sedimentation

Zitieren

ISO 690

GERHARDT, Simone, Bernhard SCHINK, 2005. Redox changes of iron caused by erosion, resuspension and sedimentation in littoral sediment of a freshwater lake. In: Biogeochemistry. 2005, 74(3), pp. 341-356, 2005. ISSN 0168-2563. eISSN 1573-515X. Available under: doi: 10.1007/s10533-004-4725-3

BibTex

@article{Gerhardt2005Redox-8654,
  year={2005},
  doi={10.1007/s10533-004-4725-3},
  title={Redox changes of iron caused by erosion, resuspension and sedimentation in littoral sediment of a freshwater lake},
  number={3},
  volume={74},
  issn={0168-2563},
  journal={Biogeochemistry},
  pages={341--356, 2005},
  author={Gerhardt, Simone and Schink, Bernhard}
}

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Universitätsbibliographie

Ja