Iodine in major Danish aquifers

  • Denitza Dimitrova VoutchkovaEmail author
  • Vibeke Ernstsen
  • Søren Munch Kristiansen
  • Birgitte Hansen
Original Article


Iodine in groundwater can have direct importance for human dietary iodine intake in areas where drinking water is of groundwater origin, as in Denmark. Knowledge on the sources and processes for the varying iodine concentrations in groundwater is of utmost importance for understanding the variation in iodine intake of the population via drinking water. The aim of this study was to characterize groundwater with elevated iodine concentrations and to investigate the sources and processes controlling natural iodine speciation and concentration at four study sites in Denmark with postglacial sandy, Quaternary sandy, and Cretaceous limestone aquifers. Analyses included iodide (I), iodate (IO3 ), total iodine (TI), major ions, and stable H and O isotopes. Dissolved organic iodine (DOI) was calculated by subtracting I and IO 3 from TI. A diagram of stable δ18O and δ2H isotopes in Danish groundwater was compiled in order to interpret the groundwater iodine geochemistry. Groundwater had TI concentrations from 5 to 14,500 µg/L. Iodine speciation reflected the prevailing neutral to alkaline and reduced conditions at the investigated sites with domination of I and DOI correlated with dissolved organic carbon. We found three different explanations for elevated TI concentrations at the four Danish sites: (1) leaching from soil enriched in iodine due to atmospheric deposition and proximity to the sea, (2) influence from the marine origin of the aquifer sediment due to desorption of iodine from iodine-enriched organic matter or minerals, and (3) influence from residual saline water due to upward advective or/and diffusive transport of iodine.


Denmark Hydrogeochemistry Iodide Iodine Groundwater Spatial heterogeneity 



This study is part of GEOCENTER (Denmark) project, funded by Geological Survey of Denmark and Greenland (GEUS) and Aarhus University (Denmark). We would like to thank Frederikshavn Vand A/S and Verdo Vand A/S for giving us access to their waterworks and well sites and to their staff for assisting us and providing valuable information, especially Rasmus Bærentzen and Børge Hylander. Acknowledgements are due also to the GEUS laboratory staff, especially Christina Rosenberg Lynge, Pernille Stockmarr, and Jørgen Kystol. Last but not least, coordinator Lasse Gudmundsson is thanked for the assistance with the groundwater sampling and the invaluable help with the organizing/logistics of the sampling campaign.

Supplementary material

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Supplementary material 1 (DOC 2786 kb)
12665_2017_6775_MOESM2_ESM.xlsx (20 kb)
Supplementary material 2 (XLSX 19 kb)


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Copyright information

© Springer-Verlag GmbH Germany 2017

Authors and Affiliations

  • Denitza Dimitrova Voutchkova
    • 1
    • 2
    • 4
    Email author
  • Vibeke Ernstsen
    • 3
  • Søren Munch Kristiansen
    • 4
  • Birgitte Hansen
    • 2
  1. 1.Department of GeographyNational University of SingaporeKent RidgeSingapore
  2. 2.Geological Survey of Denmark and Greenland (GEUS)HøjbjergDenmark
  3. 3.Geological Survey of Denmark and Greenland (GEUS)Copenhagen KDenmark
  4. 4.Department of GeoscienceAarhus UniversityAarhus CDenmark

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