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| Titel |
Modification of the functionality of soil biogeochemical interfaces: Impact of sorbed cation and temperature |
| VerfasserIn |
Jörg Bachmann, Susanne K. Woche |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250040057
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| Zusammenfassung |
| Soil as a porous 3-phase system is characterized by a tremendously high surface
area to volume ratio. Complex interactions of physical, chemical and biological
processes occur at biogeochemical interfaces generally formed in living media
like soil. Along with electrostatic interactions, the interfacial properties (surface
free energies) control wetting kinetics, physical status of adsorbed water films,
flocculation, adsorption, and they are also a major contributor to the rheological
properties of dispersions. To describe the surface properties in a mechanistic way it is
crucial to understand complex biological, physical and hydraulical processes within a
general mechanistic framework. Biogeochemical interfaces, on one hand, signicantly
determine the relationship between the surface geochemistry of a pore domain and the
micoorganism or plant life in that specific region. On the other hand, they determine
additionally with the pore geometry (local pore diameter, turtuosity and connectivity)
the hydraulic properties of the pore domain. However, until now no physically
measurable surface property has been established to determine all aspects mentioned
above with one set of parameters. One of the key physicochemical parameters for
describing the interaction of water and colloids is the interfacial free energy which is
basically measured through contact angle measurements. With respect to water
repellency we will present approaches and problems related to the evaluation of soil
wettability for a sandy topsoil and a peat soil. Hence, the first part of the study
emphasizes a framework to determine the mixed hydrophilic-hydrophobic behavior
of particle surfaces. Furthermore, the sensitivity of physical impact of frequently
changing conditions in soil like cation composition of soil solution and temperature is
analyzed. We conclude that the wettability of OM, quantified by the contact angle,
links specifically the chemical structure of SOM with a bundle of physical soil
properties which are important for biological as well as for physical processes in soil. |
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