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Moriceau B., Laruelle G. G., Passow U., Van Cappellen P., Ragueneau Olivier. (2014). Biogenic silica dissolution in diatom aggregates : insights from reactive transport modelling. Marine Ecology Progress Series, 517, 35-49. ISSN 0171-8630

Lien direct chez l'éditeur doi:10.3354/meps11028

Titre
Biogenic silica dissolution in diatom aggregates : insights from reactive transport modelling
Année de publication2014
Type de documentArticle référencé dans le Web of Science WOS:000346421400003
AuteursMoriceau B., Laruelle G. G., Passow U., Van Cappellen P., Ragueneau Olivier.
SourceMarine Ecology Progress Series, 2014, 517, p. 35-49. ISSN 0171-8630
RésuméDiatom aggregates contribute significantly to the vertical sinking flux of particulate matter in the ocean. These fragile structures form a specific microhabitat for the aggregated cells, but their internal chemical and physical characteristics remain largely unknown. Studies on the impact of aggregation on the Si cycle led to apparent inconsistency. Despite a lower biogenic silica (bSiO(2)) dissolution rate and diffusion of the silicic acid (dSi) being similar in aggregates and in sea-water, dSi surprisingly accumulates in aggregates. A reaction-diffusion model helps to clarify this incoherence by reconstructing dSi accumulation measured during batch experiments with aggregated and non-aggregated Skeletonema marinoi and Chaetoceros decipiens. The model calculates the effective bSiO(2) dissolution rate as opposed to the experimental apparent bSiO(2) dissolution rate, which is the results of the effective dissolution of bSiO(2) and transport of dSi out of the aggregate. In the model, dSi transport out of the aggregate is modulated by alternatively considering retention (decrease of the dSi diffusion constant) and adsorption (reversible chemical bonds between dSi and the aggregate matrix) processes. Modelled bSiO(2) dissolution is modulated by the impact of dSi concentration inside aggregates and diatom viability, as enhanced persistence of metabolically active diatoms has been observed in aggregates. Adsorption better explains dSi accumulation within and outside aggregates, raising the possible importance of dSi travelling within aggregates to the deep sea (potentially representing 20% of the total silica flux). The model indicates that bSiO(2) dissolution is effectively decreased in aggregates mainly due to higher diatom viability but also to other para meters discussed herein.
Plan de classementEcologie, systèmes aquatiques [036] ; Sciences fondamentales / Techniques d'analyse et de recherche [020]
LocalisationFonds IRD
Identifiant IRDPAR00012576
Lien permanenthttp://www.documentation.ird.fr/hor/PAR00012576

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