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Input, behaviour and distribution of multiple elements in abiotic matrices along a transect within the Okavango Delta, northern Botswana

  • Jörg Schaller
  • Jonas Schoelynck
  • Mike Murray-Hudson
  • Patrick J. Frings
  • Dimitri van Pelt
  • Tilo Hegewald
  • Keotshephile Mosimane
  • Mangaliso Gondwe
  • Piotr Wolski
  • Patrick Meire
  • Eric Struyf
Article
  • 159 Downloads

Abstract

Wetlands fed by rivers can be a sink for elements depending on elemental concentrations, wetland hydrology, geochemistry, vegetation and climate. In the case of the Okavango Delta, northern Botswana, the outflow discharge is a small fraction (2–5%) of the inflow. This has strong potential consequences for the Delta, as it strongly affects element cycling and storage within the Delta. We estimated the inputs, behaviour and distribution of multiple elements along a longitudinal transect within the Okavango Delta, to show potential effects of retention mechanisms of different elements. High annual element input is rather attributed to discharge than to the concentration within the water, which is generally extremely low. We observed minimal enrichment of the elements within the water pathway along the transect from inflow to outlets, implying that element output is negligible. For most elements, we observed a high correlation between storage and sediment organic matter content. The organic matter content within the sediments was higher in the vegetated sediments than in non-vegetated sediments (factor ∼ 10), and a similar trend was found for most elements. In conclusion, organic matter dominated in sediments from vegetated plots and thus plays an important role in retaining the elements within the sediments of the Delta. This finding has major implications for e.g. planning constructed wetlands for water purification or element retention especially in areas with high evapotranspiration.

Keywords

Aquatic ecosystem Carbon pools Element accumulation Organic rich sediments Wetland Macrophytes 

Notes

Acknowledgements

We would like to thank several funding agencies for their funding contributions: University of Botswana Office of Research and Development, EU Marie Curie Program (Hobits), National Geographic Explorer Grant, the Swedish National Science Foundation (VR) and the Knut and Alice Wallenberg Foundation. This research was carried out under Permit EWT 8/36/4 XVI(6) from the Government of Botswana. We would like to thank BELSPO for funding the project SOGLO. J.S. is a postdoctoral fellow of FWO (project no. 12H8616N) and thanks the FWO for a travel grant.

Supplementary material

10661_2016_5696_MOESM1_ESM.doc (7.2 mb)
ESM 1 (DOC 7385 kb)

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Copyright information

© Springer International Publishing Switzerland 2016

Authors and Affiliations

  • Jörg Schaller
    • 1
    • 2
  • Jonas Schoelynck
    • 3
  • Mike Murray-Hudson
    • 4
  • Patrick J. Frings
    • 5
  • Dimitri van Pelt
    • 3
  • Tilo Hegewald
    • 6
  • Keotshephile Mosimane
    • 4
  • Mangaliso Gondwe
    • 4
  • Piotr Wolski
    • 4
    • 7
  • Patrick Meire
    • 3
  • Eric Struyf
    • 3
  1. 1.Institute of General Ecology and Environmental ProtectionTechnische Universität DresdenDresdenGermany
  2. 2.Environmental Geochemistry, Bayreuth Center for Ecology and Environmental Research (BayCEER)University BayreuthBayreuthGermany
  3. 3.Department of BiologyUniversity of AntwerpWilrijkBelgium
  4. 4.Okavango Research InstituteUniversity of BotswanaMaunBotswana
  5. 5.Department of GeologyLund UniversityLundSweden
  6. 6.State Reservoir Administration of Saxony, Research Laboratory PaulsdorfDippoldiswaldeGermany
  7. 7.Climate Systems Analysis GroupUniversity of Cape TownCape TownSouth Africa

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