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Dan Hammarlund

Dan Hammarlund

Professor

Dan Hammarlund

The lake as an iron sink - new insights on the role of iron speciation

Author

  • Caroline Björnerås
  • Per Persson
  • Gesa A. Weyhenmeyer
  • Dan Hammarlund
  • Emma S. Kritzberg

Summary, in English

The solubility and behavior of iron (Fe) in natural waters is tightly linked to Fe speciation, and Fe speciation likely influences how Fe distributes between the water column and sediments. In this study, the function of a lake as an Fe sink, with focus on the role of Fe speciation, was assessed for Lake Bolmen in southern Sweden. We found that a large fraction of the Fe flowing in to the lake was efficiently lost by sedimentation in the lake basin. Fe in inflowing water was a mix of organically complexed mononuclear Fe, Fe-(oxy)hydroxides and Fe-bearing clays, while surface sediments were composed of Fe-(oxy)hydroxides, Fe-bearing clays, Fe-bearing silicates and Fe sulfides. The absence of organically complexed Fe in the surface sediments indicates that the lake is mainly a sink for minerogenic fractions. Furthermore, while lakes are considered to be sinks of Fe, it has been suggested that this function may be impaired by increasing precipitation and consequently shorter water residence time. In this study there were large within- and between-year variations in precipitation and Fe concentrations. However, rather than smaller Fe losses to the sediments during wet years, within-lake losses tended to be larger due to higher loading of Fe from the catchment. Thus, forecasted increases in precipitation may result in enhanced catchment export and Fe loading to lakes, and subsequently enhanced Fe sequestration in sediments.

Department/s

  • Division aquatic ecology
  • Microbial Ecology
  • MEMEG
  • Centre for Environmental and Climate Science (CEC)
  • Quaternary Sciences
  • Aquatic Ecology

Publishing year

2021-12-05

Language

English

Publication/Series

Chemical Geology

Volume

584

Document type

Journal article

Publisher

Elsevier

Topic

  • Geochemistry
  • Water Engineering

Keywords

  • Browning
  • Iron biogeochemistry
  • Mass balance
  • Organic carbon
  • X-ray absorption spectroscopy

Status

Published

Research group

  • Microbial Ecology
  • Aquatic Ecology

ISBN/ISSN/Other

  • ISSN: 0009-2541