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| Titel |
Evaluating sensitivity of silicate mineral dissolution rates to physical weathering using a soil evolution model (SoilGen2.25) |
| VerfasserIn |
E. Opolot, P. A. Finke |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 12, no. 22 ; Nr. 12, no. 22 (2015-11-27), S.6791-6808 |
| Datensatznummer |
250118182
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| Publikation (Nr.) |
 copernicus.org/bg-12-6791-2015.pdf |
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| Zusammenfassung |
| Silicate mineral dissolution rates depend on the interaction of a number of
factors categorized either as intrinsic (e.g. mineral surface area, mineral
composition) or extrinsic (e.g. climate, hydrology, biological factors,
physical weathering). Estimating the integrated effect of these factors on
the silicate mineral dissolution rates therefore necessitates the use of
fully mechanistic soil evolution models. This study applies a mechanistic
soil evolution model (SoilGen) to explore the sensitivity of silicate
mineral dissolution rates to the integrated effect of other soil-forming
processes and factors. The SoilGen soil evolution model is a 1-D model
developed to simulate the time-depth evolution of soil properties as a
function of various soil-forming processes (e.g. water, heat and solute
transport, chemical and physical weathering, clay migration, nutrient
cycling, and bioturbation) driven by soil-forming factors (i.e., climate,
organisms, relief, parent material). Results from this study show that
although soil solution chemistry (pH) plays a dominant role in determining
the silicate mineral dissolution rates, all processes that directly or
indirectly influence the soil solution composition play an equally important
role in driving silicate mineral dissolution rates. Model results
demonstrated a decrease of silicate mineral dissolution rates with time, an
obvious effect of texture and an indirect but substantial effect of physical
weathering on silicate mineral dissolution rates. Results further indicated
that clay migration and plant nutrient recycling processes influence the pH
and thus the silicate mineral dissolution rates. Our silicate mineral
dissolution rates results fall between field and laboratory rates but were
rather high and more close to the laboratory rates possibly due to the assumption
of far from equilibrium reaction used in our dissolution rate mechanism.
There is therefore a need to include secondary mineral precipitation mechanism
in our formulation. In addition, there is a need for a more detailed study
that is specific to field sites with detailed measurements of silicate
mineral dissolution rates, climate, hydrology, and mineralogy to enable the
calibration and validation of the model. Nevertheless, this study is another
important step to demonstrate the critical need to couple different soil-forming processes with chemical weathering in order to explain differences
observed between laboratory and field measured silicate mineral dissolution
rates. |
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