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Journal articles
Manganese, iron and phosphorus cycling in an estuarine mudflat sediment, Loire, France
Abstract : The sampling of surface sediment fromtwo sites of amudflat of the Loire Estuary during four contrasting seasons
has led to new information about geochemical cycling under transient diagenesis fuelled by flood deposition.
Based on stocks of reactive iron-oxides andmanganese-oxides (ascorbate-extracted) and pore water concentrations,
the progressive evolution of flood deposits is described. Three major steps are observed: at first, there is no
manganese, iron and phosphorus release into pore waterwithin the flood-deposited layer. Then, during a period
of approximately 1 month, Mn oxides are consumed while the dissolved Mn concentration increases. Simultaneously,
the Fe oxide-rich layer from flood deposition prevents (or at least limits) phosphorus release into
porewater as shown by the increasing P/Fe ratio of the ascorbate extractions. During spring and summer, Fe oxides
are reductively dissolved until complete depletion results. This period also corresponds to the saturation of
Fe oxides by phosphorus and probably maximum P release to the water column. The site located closer to the
shore showed higher density of benthic faunas leading to more intense bioirrigation. The importance of bioturbation
on the year scale for biogeochemical processes is discussed according to both bioirrigation and biomixing
processes.
http://hal.in2p3.fr/in2p3-01409964
Contributor : Olivier Péron <>
Submitted on : Tuesday, December 6, 2016 - 11:54:33 AM
Last modification on : Thursday, February 6, 2020 - 9:56:05 AM
Contributor : Olivier Péron <>
Submitted on : Tuesday, December 6, 2016 - 11:54:33 AM
Last modification on : Thursday, February 6, 2020 - 9:56:05 AM
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