Clays and Clay Minerals

, Volume 44, Issue 5, pp 599–608 | Cite as

Reduction of Nitrate By Fe2+ in Clay Minerals

  • Vibeke Ernstsen


In the 12 km2 catchment area of Syv creek, Denmark, moderate to high concentrations of nitrate (NO3) occurred in the upper part of the oxidized zone (oxic-I), but dropped within the lower suboxic part (oxic-II), to below the detection limit in the unoxidized zone. Structural Fe2+ in the clay minerals made up 10 to 12% of the Fe in the oxidized zone and increased to approximately 50% in the unoxidized zone. Concurrent with changes in the distribution of structural Fe2+ the clay mineral constituents changed. Vermiculite was typically found in the oxidized zone whereas chlorite was found in the unoxidized zone only. A conversion of illite and chlorite into vermiculite seems to take place. A significant correlation between NO3 and the amount of reduced Fe2+ in the suboxic (oxic-II) zone, indicates that primary structural Fe2+ in the clay minerals is the reductant in a NO3 reduction process.

Key Words

Chlorite Clayey till Exchangeable ferrous iron Illite Mössbauer Nitrate Oxidized Structural ferrous iron Unoxidized Vermiculite Weichselian X-ray 


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Copyright information

© The Clay Minerals Society 1996

Authors and Affiliations

  • Vibeke Ernstsen
    • 1
  1. 1.Geological Survey of Denmark and GreenlandCopenhagen NVDenmark

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