Biogenic silica in freshwater marsh sediments and vegetation (Schelde estuary, Belgium)
Struyf, E.; Van Damme, S.; Gribsholt, B.; Middelburg, J.J.; Meire, P. (2005). Biogenic silica in freshwater marsh sediments and vegetation (Schelde estuary, Belgium), in: Struyf, E. The role of freshwater marshes in estuarine silica cycling (Scheldt estuary) = De rol van zoetwaterschorren in de estuariene siliciumcyclus (Schelde-estuarium). pp. 33-58 In: Struyf, E. (2005). The role of freshwater marshes in estuarine silica cycling (Scheldt estuary) = De rol van zoetwaterschorren in de estuariene siliciumcyclus (Schelde-estuarium). PhD Thesis. Universiteit Antwerpen: Antwerpen. 162 pp., more |
| Keywords | Chemical compounds > Silicon compounds > Silica
Cycles > Chemical cycles > Geochemical cycle > Biogeochemical cycle > Nutrient cycles > Silicon cycle
Sedimentation
Sediments > Biogenic deposits
Tidal marshes
Water bodies > Inland waters > Wetlands > Marshes
Belgium, Schelde R. [Marine Regions]; Belgium, Zeeschelde [Marine Regions]
Marine/Coastal |
| Abstract | Up to this date, silicon cycling in freshwater intertidal marshes has mostly been neglected in estuarine ecosystem research. However, tidal marshes can store large amounts of biogenic silica (BSi) in vegetation and sediment. BSi content of the typical freshwater marsh plants Phragmites australis, Impatiens glandulifera, Urtica dioica, Epilobium hirsutum and Salixx sp. was analysed year round. All herbaceous species accumulated silica in their tissue during their life cycle. P. australis contained most BSi (accumulation from 6 to 55 mg g-l). Dead standing P. australis shoots had the largest BSi content (up to 72.2 mg g-l). U. dioica (< 11.1 mg g-l), I. glandulifera (< 1.1 mg g-l), E. hirsutum (< 1.2 mg g-l) and Salix sp. (< 1.9 mg g-l) had much lower BSi content. Underground biomass (<6 mg g-l), except for P. australis rhizomes (<15 mg g-l) contained low amounts of BSi. Sediment BSi decreased from the surface (9-10 mg g-l) towards deeper layers (5-7 mg g-l). There was no seasonal variation in sediment BSi. Porewater dissolved Si was highest in summer (ca. 600 µM) and lowest in winter (ca. 400 µM). P. australis vegetation (above ground and roots) contained up to 140 g m-2 BSi, while the sediment upper 30 cm accumulated up to 1500 g m-2 BSi, making sediment the largest BSi reservoir in the marsh. We can conclude that P. australis wetlands could be an essential, yet overlooked sink for BSi in the biogeochemical cycling of Si. |
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