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| Titel |
Mobilisation of Amorphous and Dissolved Silica on Small Agricultural Plots |
| VerfasserIn |
W. Clymans, G. Govers, E. Struyf, S. Vandamme, B. van Wesemael, C. Langhans, A. Van den Putte, P. Meire |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250022514
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| Zusammenfassung |
| In recent years awareness has grown that biogeochemical cycles are strongly affected by
processes occurring in the critical zone. Global carbon dynamics, for instance, may be
affected by soil erosion and deposition processes that affect carbon dynamics within the
critical zone. Silica is another element of which the cycling may be strongly influenced:
weathering is a major source of dissolved silica (DSi) that may be transformed to amorphous
silica (ASi) through reprecipitation in the soil and/or in vegetation. As Si is a crucial nutrient
for diatoms, which are a base component for a well-balanced food-system in estuarine and
coastal zones, it is important to understand how anthropogenic modifications of critical-zone
processes, including agricultural erosion, may affect global Si cycling. According to our
knowledge, studies on the effects of erosion and deposition on Si cycling and mobilisation are
almost nonexistent.
In this paper we report the first results of a series of rainfall simulation experiments that
were set up to (i) quantify Si mobilisation through erosion at the small plot scale and (ii)
investigate to what extent Si mobilisation by erosion may be dependent on crop type and
tillage technique. We quantified ASi and Dsi fluxes during rainfall experiments on small
scale plots (~0.73m2). Experiments are conducted for various crop and tillage
types.
Our results indicate that soil erosion mobilises significant quantities of ASi and DSi.
Overall ASi mobilisation is more important: ca. 80% of total silica export is ASi, only 20% of
the Si is exported as dissolved silica. There is a near-linear relationship between ASi and
sediment concentration in the runoff: tillage technique and crop type have only a
secondary influence. Thus, in a first approximation, a good estimate of ASi mobilisation
through erosion can be made if total sediment mobilisation can be correctly assessed. |
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