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Variability in chemistry of surface and soil waters of an evapotranspiration-dominated flood-pulsed wetland : Solute processing in the okavango delta, Botswana

Mosimane, Keotshephile; Struyf, Eric LU ; Gondwe, Mangaliso J.; Frings, Patrick LU ; van Pelt, Dimitri; Wolski, Piotr; Schoelynck, Jonas; Schaller, Jörg; Conley, Daniel J. LU and Murray-Hudson, Mike (2017) In Water S.A. 43(1). p.104-115
Abstract

Water chemistry is important for the maintenance of wetland structure and function. Interpreting ecological patterns in a wetland system therefore requires an in-depth understanding of the water chemistry of that system. We investigated the spatial distribution of chemical solutes both in soil pore water and surface water, along island-floodplain-channel hydrological gradients in seasonally and permanently inundated habitats between major regions in the Okavango Delta, Botswana. Our results show that major cations (Ca, Na, Mg, and K), dissolved silica (DSi), dissolved boron (B), dissolved organic matter (DOC) and electrical conductivity increased significantly, at p ≤ 0.05, from the inlet of the Delta (the Panhandle) to the distal... (More)

Water chemistry is important for the maintenance of wetland structure and function. Interpreting ecological patterns in a wetland system therefore requires an in-depth understanding of the water chemistry of that system. We investigated the spatial distribution of chemical solutes both in soil pore water and surface water, along island-floodplain-channel hydrological gradients in seasonally and permanently inundated habitats between major regions in the Okavango Delta, Botswana. Our results show that major cations (Ca, Na, Mg, and K), dissolved silica (DSi), dissolved boron (B), dissolved organic matter (DOC) and electrical conductivity increased significantly, at p ≤ 0.05, from the inlet of the Delta (the Panhandle) to the distal downstream reaches, suggesting the influence of evapoconcentration. Concentrations of dissolved Fe, Al, Zn, Cu, and Mn significantly decreased, at p ≤ 0.05, from the inflow of the Delta to the distal reaches. Only Na, Mn, Fe, Al, and DOC showed significant differences, at p ≤ 0.05, along the local floodplain-channel hydrological gradients, with higher solute concentrations in the floodplains than the channels. Solute concentrations in soil water exhibited similar distribution patterns to those in surface water, but concentrations were higher in soil water. Based on the results, we hypothesise that floodplain emergent vegetation and the channel-fringing vegetation in the Panhandle (a fault-bounded entry trough to the Delta) and the permanently inundated eco-region together influence the cycling of solutes that enter the Delta through uptake.

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Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Emergent macrophytes, Pore water, Surface water, Water chemistry, Wetland vegetation
in
Water S.A.
volume
43
issue
1
pages
12 pages
publisher
Water Research Commission
external identifiers
  • scopus:85011961247
  • wos:000396502100013
ISSN
0378-4738
DOI
10.4314/wsa.v43i1.13
language
English
LU publication?
yes
id
6fc1a0a7-72b0-4078-a73e-ac1850057d88
date added to LUP
2017-02-23 12:07:45
date last changed
2018-01-07 11:52:23
@article{6fc1a0a7-72b0-4078-a73e-ac1850057d88,
  abstract     = {<p>Water chemistry is important for the maintenance of wetland structure and function. Interpreting ecological patterns in a wetland system therefore requires an in-depth understanding of the water chemistry of that system. We investigated the spatial distribution of chemical solutes both in soil pore water and surface water, along island-floodplain-channel hydrological gradients in seasonally and permanently inundated habitats between major regions in the Okavango Delta, Botswana. Our results show that major cations (Ca, Na, Mg, and K), dissolved silica (DSi), dissolved boron (B), dissolved organic matter (DOC) and electrical conductivity increased significantly, at p ≤ 0.05, from the inlet of the Delta (the Panhandle) to the distal downstream reaches, suggesting the influence of evapoconcentration. Concentrations of dissolved Fe, Al, Zn, Cu, and Mn significantly decreased, at p ≤ 0.05, from the inflow of the Delta to the distal reaches. Only Na, Mn, Fe, Al, and DOC showed significant differences, at p ≤ 0.05, along the local floodplain-channel hydrological gradients, with higher solute concentrations in the floodplains than the channels. Solute concentrations in soil water exhibited similar distribution patterns to those in surface water, but concentrations were higher in soil water. Based on the results, we hypothesise that floodplain emergent vegetation and the channel-fringing vegetation in the Panhandle (a fault-bounded entry trough to the Delta) and the permanently inundated eco-region together influence the cycling of solutes that enter the Delta through uptake.</p>},
  author       = {Mosimane, Keotshephile and Struyf, Eric and Gondwe, Mangaliso J. and Frings, Patrick and van Pelt, Dimitri and Wolski, Piotr and Schoelynck, Jonas and Schaller, Jörg and Conley, Daniel J. and Murray-Hudson, Mike},
  issn         = {0378-4738},
  keyword      = {Emergent macrophytes,Pore water,Surface water,Water chemistry,Wetland vegetation},
  language     = {eng},
  number       = {1},
  pages        = {104--115},
  publisher    = {Water Research Commission},
  series       = {Water S.A.},
  title        = {Variability in chemistry of surface and soil waters of an evapotranspiration-dominated flood-pulsed wetland : Solute processing in the okavango delta, Botswana},
  url          = {http://dx.doi.org/10.4314/wsa.v43i1.13},
  volume       = {43},
  year         = {2017},
}