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Communication Dans Un Congrès Année : 2015

Phosphorus behaviour at the groundwater-river water redox boundary

Résumé

The importance of P-flux on aquatic ecosystems bears out the study of P dynamics in river catchments. Aqueous P geochemistry depends on biogeochemical processes and Fe geochemistry. Our study focused on P and Fe behaviour at the groundwater-river water boundary. We monitored the distribution of dissolved and particulate P and Fe in the Leyre river from order 0 streams to order 4 main-river. We also analysed porewaters from river bed sediments and from wells located in the two main land-use types (pine forest and corn field). We determined the particulate speciation of P using chemical extractions. The particulate-dissolved P exchange capacity was measured using in-vitro experiments and 32 P radioactivity. Results show that the studied catchment groundwaters supplied dissolved Fe and P with a high Fe/P ratio. Dissolved Fe was subjected to oxidative precipitation at the groundwater/river water interface. This oxidation was enhanced by aquatic plants. P was trapped on Fe(III) particles so much so that dissolved P remained at concentrations >0.2 µM. This means that the coastal river outlet receives particulate P, which can be solubilized after anoxic diagenetic processes.
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Dates et versions

hal-02792596 , version 1 (05-06-2020)

Identifiants

  • HAL Id : hal-02792596 , version 1
  • PRODINRA : 305656

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Pierre Anschutz, Anne Rapin, Loris Deirmendjian, Christian Morel, Gwenaël Abril. Phosphorus behaviour at the groundwater-river water redox boundary. 2015 Aquatic Sciences Meeting - Aquatic Sciences: Global and Regional Perspectives, Feb 2015, Granada, Spain. ⟨hal-02792596⟩

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