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| Titel |
Exploring the heterogeneity of the soil pore system using multifractal analysis from Mercury injection and Nitrogen sorption |
| VerfasserIn |
Eva Vidal Vazquez, Rosario García Moreno, Jorge Paz-Ferreiro |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250053182
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| Zusammenfassung |
| The soil pore space is composed of a continuum of pores extremely variable in size, which
range from equivalent diameters smaller than nanometres to an upper limit that may reach the
order of centimetres. Thus, the soil pore space commonly displays a size range of more than a
factor of 106 in scale. Because of the big array of pore sizes, there is not a unique
method to record the pore size distribution (PSD) across the entire size range of
soil pores. PSDs over a range of lineal scales larger than 104 (about 150 μm to
50 nm) can be determined indirectly by mercury injection porosimetry. Nitrogen
sorption (adsorption and desorption) isotherms provide additional information for
equivalent diameters in the order of one magnitude smaller (about 2-100 nm), partially
overlapping mercury injection curves. This study follows previous work, which found that
multifractal analysis was a suitable tool to characterize nitrogen adsorption and desorption
isotherms (Paz-Ferreiro et al., 2010a), as well as mercury intrusion porosimetry
(Paz-Ferreiro et al., 2010b). The goal was to compare PSDs obtained by mercury injection,
nitrogen adsorption and nitrogen desorption. Soil samples were collected in two
series of a Typic Argiudoll located in the north of Buenos Aires and in the south of
Santa Fe provinces, Argentina. Two treatments and three sampling depths have been
considered. The box counting method was used to carry out multifractal analysis of
Nitrogen sorption and Mercury intrusion. Mercury intrusion curves as well as Nitrogen
adsorption and desorption isotherms exhibited a well defined scaling and behave like a
multifractal system. On average, the entropy dimension, D1, ranged as follows:
Mercury porosimetry > Nitrogen desorption > Nitrogen adsorption. The width of the
singularity spectra, f(α) also followed the former rank. In general, our results showed
different averaged values of the entropy dimension and other fractal parameters
depending on the technique used and the corresponding pore size range appraised.
Such differences could be the result of nonuniform probability distributions of
soil porosity for specific size ranges. We conclude that parameters derived from
multifractal analysis are useful to characterize the heterogeneity of the pore system at
successive scales within primary soil aggregates, allowing distinction between different
patterns of PSDs with various degrees of clustering. Also multifractal spectra are a
powerful tool to differentiate between the local scaling properties of each experimental
PSD.
Acknowledgements. This work was supported by Xunta de Galicia (Project:
INCITE08PXIB162169PR).
References
Paz-Ferreiro J., Miranda, J.G.V. and Vidal Vázquez, E. 2010a. Characterizing Nitrogen
adsorption and desorption isotherms in soils using multifractal analysis. Geophysical
Research Abstracts, Vol 12, EGU 2010-2710.
Paz-Ferreiro, J., Miranda, J.G.V. and Vidal Vázquez, E. 2010b. Multifractal analysis of
soil porosity based on Mercury injection and Nitrogen adsorption. Vadose Zone Journal, 9:
325-335. |
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