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Are benthic nutrient fluxes from intertidal mudflats driven by surfacesediment characteristics?

Abstract : A broad sampling program was carried out in the spring of 2019 on the Brittany coast to assess how the surface sediment characteristics drive the benthic effluxes of ammonium (NH + 4) and phosphate (PO 4) from intertidal mudflats. A total of 200 sediment samples were characterized by their porosity, grain-size, elemental composition and pigment contents, as well as the benthic fluxes of NH + 4 and PO 4 determined by core incubations. The results showed that (1) a high phaeopigment and iron-bound phosphorus content (Fe-P) and a low porosity were significantly related to the high PO 4 flux, and (2) a high porosity and the TN:Org-P ratio in the sediment organic matter (SOM) were related to the high NH + 4 flux. This indicated that PO 4 fluxes would be more driven by the redox status of the sediment through the desorption of Fe-P under specific anoxic conditions during the algal decomposition. NH + 4 fluxes would be more driven by high NH + 4 recycling rates from SOM mineralization and high sediment-water exchanges, enhancing the diffusion of NH + 4 to the overlying water. The present study allowed to highlight the large variability in the benthic nutrient fluxes at the regional scale, as a result of the connections between microbial (SOM mineralization), chemical (adsorption-desorption) and physical (diffusion) processes.
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Submitted on : Wednesday, May 19, 2021 - 10:59:07 AM
Last modification on : Thursday, June 2, 2022 - 2:48:17 PM
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Justine Louis, Laurent Jeanneau, Françoise Andrieux-Loyer, Gérard Gruau, Florian Caradec, et al.. Are benthic nutrient fluxes from intertidal mudflats driven by surfacesediment characteristics?. Comptes Rendus. Géoscience, Académie des sciences (Paris), 2021, 353 (1), pp.173-191. ⟨10.5802/crgeos.57⟩. ⟨insu-03229725⟩



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