Variability in chemistry of surface and soil waters of an evapotranspiration-dominated flood-pulsed wetland : Solute processing in the okavango delta, Botswana
Variability in chemistry of surface and soil waters of an evapotranspiration-dominated flood-pulsed wetland : Solute processing in the okavango delta, Botswana
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以蒸散为主的洪水脉冲湿地地表水和土壤水的化学变化：博茨瓦纳奥卡万戈三角洲的溶质处理
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发表时间：
2017
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通讯作者：
Michael Murray
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作者：
Keotshephile Mosimane;E. Struyf;M. Gondwe;P. Frings;D. Pelt;P. Wolski;J. Schoelynck;J. Schaller;D. Conley;Michael Murray
水化学对湿地结构和功能的维持具有重要意义。因此，解释湿地系统中的生态模式需要深入了解该系统的水化学。我们研究了博茨瓦纳奥卡万戈三角洲主要区域之间季节性和永久性淹没生境中，沿岛屿-泛滥平原-水道水文梯度的土壤孔隙水和地表水中化学溶质的空间分布。结果表明，在p≤0.05时，主要阳离子(钙、钠、镁、钾)、溶解二氧化硅、溶解硼、溶解有机质和电导率从三角洲入口(狭长柄)到下游远端显著增加，这表明蒸散浓度的影响。在p≤0.05时，从三角洲流入到远岸河段，溶解态Fe、Al、Zn、Cu和Mn的浓度显著降低。在p≤为0.05时，只有Na、Mn、Fe、Al和DOC值在局部滩地-河道水文梯度上存在显著差异，且滩地的溶质浓度高于河道。土壤水中溶质浓度与地表水中溶质浓度分布规律相似，但土壤水中溶质浓度高于地表水。基于这些结果，我们假设泛滥平原的新兴植被和狭长地带(三角洲断裂带入口槽)的河道边缘植被和永久淹没的生态区共同影响通过吸收进入三角洲的溶质循环。关键词：湿地植被、水化学、孔隙水、地表水、浮游植物
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. Keywords : wetland vegetation, water chemistry, pore water, surface water, emergent macrophytes