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Behaviour of chemical solutes during a storm in a rainforested headwater catchment

Abstract : The aim of this study is to identify, in a small catchment area located within a tropical forest, the pedological compartments in which the export of nutrients and chemical erosion of solutes occur during a stormflow event. The catchment area displays two types of lateral flow: (i) overland flow at the surface of the soil in the litter and root mat and (ii) groundwater flow in a macroporous subsurface horizon. We interpret the variations of stream-water chemistry during a storm-flow event using the separation of storm-flow hydrograph data between overland and groundwater flow, and (Cl as a chemical parameter characterizing the residence time of water in the soil. It appears that K+ especially was released into the throughfall, whereas Ca++, Mg++ and Na+ were clearly released from the litter. K+ disappeared rapidly from soil solution, whereas Ca++ and Mg++ were more progressively absorbed by the vegetation. The Ca++ and Mg++ contents in groundwater increased with increasing residence time owing to the transpiration of trees. The export of H4SiO4 in the overland flow was moderate, i.e. 24% of total H4SiO4 export in the stream flow, as overland flow represented 39% of total runoff. The subsurface horizon—where active groundwater flow occurs—was successively affected by chemical erosion during the storm-flow peak, and then by neoformation of kaolinite favoured by increasing water residence time.
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https://hal-bioemco.ccsd.cnrs.fr/bioemco-00169391
Contributor : Thierry Bariac <>
Submitted on : Monday, September 3, 2007 - 4:09:20 PM
Last modification on : Monday, July 6, 2020 - 3:38:32 PM

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Catherine Grimaldi, Michel Grimaldi, Antoine Millet, T. Bariac, Jacques Boulègue. Behaviour of chemical solutes during a storm in a rainforested headwater catchment. Hydrological Processes, Wiley, 2004, 18, pp.93-106. ⟨10.1002/hyp.1314⟩. ⟨bioemco-00169391⟩

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