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A survey of denitrifying communities in a wetland

Abstract : A hydrological and geochemical survey of a wetland (Normandy, France) highlighted the presence of a major spatiotemporal variability of sulphates and nitrates concentrations related to a distinct hydrologic regime represented by the stream proximity. An experimental approach was carried out to determine the factors influencing the dynamic of nitrate and sulphate concentrations observed in field; and the denitrifiers' community structuration related to different environmental stresses. We investigated the effects of stream proximity and associated nutrients fluxes, on microbial activity. Experiments were performed with peat sampled from different plots along a hydrologic flow gradient to characterize the biogeochemical processes and estimate the potential reactivity. We used bioreactors containing the peat-soils and a synthetic solution (similar to the field stream composition) to understand biogeochemical fluxes related to different nitrate availability and redox conditions. The evolution of nitrates and sulphates concentrations was analysed over time. The results demonstrated a spatial variability of the potential reactivity and a biological activity reacting unevenly to experimental conditions. We highlighted the control of the temporal evolution of nitrate and sulphate concentration by redox conditions and nitrate availability (nitrates, P<0.001; sulphates, P<0.001) and by distinct hydrologic regime (nitrates, P <0,001; sulphates, P<0,001). We established the reduction of nitrate is a heterotrophic denitrification and the sulphate production is related to bio-geochemical processes. The fate of microbial activity seems to be regulated by hydrogeological fluxes especially at the stream-soil, soil-water interface. Spatial and temporal dynamic of denitrifying community composition is currently investigated by a narG gene analysis and t-RFLP.
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https://hal-insu.archives-ouvertes.fr/insu-00165196
Contributor : Isabelle Dubigeon <>
Submitted on : Wednesday, July 25, 2007 - 11:09:25 AM
Last modification on : Monday, April 29, 2019 - 2:30:44 PM

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  • HAL Id : insu-00165196, version 1

Citation

Nolwenn Bougon, Philippe Vandenkoornhuyse, Marie-Paule Briand, Luc Aquilina. A survey of denitrifying communities in a wetland. International Symposium on Microbial Ecology (ISME-11), the hidden powers microbial communities in action, Aug 2006, Vienne, Austria. ⟨insu-00165196⟩

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