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WATER RESOURCES RESEARCH, VOL. 44, W04418, doi:10.1029/2007WR006067, 2008

Phytotoxicity of salt and plant salt uptake: Modeling ecohydrological feedback mechanisms

Peter Bauer-Gottwein

Department of Environmental Engineering, Technical University of Denmark, Kongens Lyngby, Denmark


Nikolaj F. Rasmussen

Department of Environmental Engineering, Technical University of Denmark, Kongens Lyngby, Denmark


Dagmar Feificova

Institute of Chemical Technology, Prague, Czech Republic


Stefan Trapp

Department of Environmental Engineering, Technical University of Denmark, Kongens Lyngby, Denmark


Abstract

A new model of phytotoxicity of salt and plant salt uptake is presented and is coupled to an existing three-dimensional groundwater simulation model. The implementation of phytotoxicity and salt uptake relationships is based on experimental findings from willow trees grown in hydroponic solution. The data confirm an s-shaped phytotoxicity relationship as found in previous studies. Uptake data were explained assuming steady state salt concentration in plant roots, passive salt transport into the roots, and active enzymatic removal of salt from plant roots. On the one hand, transpiration strongly depends on groundwater salinity (phytotoxicity); on the other hand, transpiration significantly changes the groundwater salinity (uptake). This feedback loop generates interesting dynamic phenomena in hydrological systems that are dominated by transpiration and are influenced by significant salinity gradients. Generic simulations are performed for the Okavango island system and are shown to reproduce essential phenomena observed in nature.

Received 28 March 2007; accepted 14 December 2007; published 12 April 2008.

Keywords: groundwater; modeling; Okavango; salinization; toxicity; transpiration.

Index Terms: 1813 Hydrology: Eco-hydrology; 1818 Hydrology: Evapotranspiration; 1829 Hydrology: Groundwater hydrology; 1831 Hydrology: Groundwater quality.

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Citation: Bauer-Gottwein, P., N. F. Rasmussen, D. Feificova, and S. Trapp (2008), Phytotoxicity of salt and plant salt uptake: Modeling ecohydrological feedback mechanisms, Water Resour. Res., 44, W04418, doi:10.1029/2007WR006067.