Papers by Wibke Baumgarten
Characterization of Microstructural Stability of Northern German Marshland Soils by Rheological Measurements
한국토양비료학회 학술발표회 초록집, Jun 1, 2014
Contrasting Effect of Biochar and Clay Amendment of Coarse Textured Soil
한국토양비료학회 학술발표회 초록집, Jun 1, 2014
Biochar Induced Changes in Soil Stability Parameters
한국토양비료학회 학술발표회 초록집, Jun 1, 2014
Uber Messungen auf der Meso- und Mikroskala sollen Parameter bestimmt werden, die mittels einer P... more Uber Messungen auf der Meso- und Mikroskala sollen Parameter bestimmt werden, die mittels einer Pedotransfer-funktion die Bodenstabilitat an der Tideelbe vorherzusagen ermoglicht.
Biochar Induced Changes in Soil Stability Parameters
Characterization of Microstructural Stability of Northern German Marshland Soils by Rheological Measurements
Anhand rheologischer Untersuchungen soll die Uferstabilitat an der Tideelbe quantifiziert werden.... more Anhand rheologischer Untersuchungen soll die Uferstabilitat an der Tideelbe quantifiziert werden. Die durchgefuhrten Amplitudentests (AST) zeigen eine Zunahme der mikrostrukturellen Stabilitat mit abnehmendem Matrixpotential durch Meniskenkrafte. Dieser stabilisierende Effekt durch Menisken ist in feinkornigeren/tonigeren Substraten groser als in sandigem Material. Im Gegensatz dazu steigt die Erodierbarkeit bei Wassersattigung mit zunehmendem Tongehalt. Die Bodenmikrostruktur wird neben dem Wassergehalt zusatzlich von Textur und Gehalt an organischer Substanz beeinflusst.
Contrasting Effect of Biochar and Clay Amendment of Coarse Textured Soil
Rheological and zeta potential measurements were performed with South-Brazilian soils, a kaolinit... more Rheological and zeta potential measurements were performed with South-Brazilian soils, a kaolinitic, Fe-oxide-rich Oxisol, and a smectitic Vertisol, respectively. Hence, a low active clay and a high active clay system were compared. Furthermore, the phenomenon of pseudosand was investigated. Stiffness degradation was measured by conducting amplitude sweep tests with a rotational rheometer in oscillatory mode. By using loss factor tan δ(γ), elasticity and viscosity of substrates can be defined in detail and calculated. Zeta potential measurements show a clear trend of agglomeration for Oxisols, whilst Vertisol suspensions remain stable over a wide range of pH 10…2; the isoelectric point (IEP) is reached at pH 2 in case of the Oxisol. A synopsis of rheological and zeta potential results may explain both pseudosand effects due to Fe-oxides and microstructural stability deriving from physicochemical properties i.e. texture, clay mineralogy, and CEC.
Assessing soil degradation by using a scale-spanning soil mechanical approach: A review
Wechselwirkung zwischen mechanischer Auflast und mikrobiologischer Aktivität in Böden
Quantification of Microstructural Changes in Salorthidic Fluvaquents Using Rheological and Particle Charge Techniques
Vadose Zone Journal, 2012
Salorthidic Fluvaquents originating from Seville, Andalusia, were sampled and subjected to rheolo... more Salorthidic Fluvaquents originating from Seville, Andalusia, were sampled and subjected to rheological and particle charge investigations. Structural changes in a managed and a natural site under pasture were compared based on physicochemical laboratory analyses, scanning electron microscopy, particle charge density (PCD) measurements, and rheological tests. An uncultivated site located at the riparian zone of the Guadalquivir River showed a natural fluvio‐marine‐affected development. A regular influx and exchange of salts in the groundwater, especially in the form of NaCl and calcite, dominate soil genetic processes. In contrast, drainage of the saline‐sodic soils for cultivation, furrow irrigation, and phosphogypsum fertilization have led to a modification of the salinity gradients throughout the reclaimed soil profile. Sodium ions on the exchangers were released due to the Ca amendment, which led to a decreased exchangeable Na+ concentration (exchangeable Na percentage [ESP] <...
Soil and Tillage Research, 2013
Microstructural development in volcanic ash soils from South Chile
Soil and Tillage Research, 2013
ABSTRACT Streaming potential measurements and amplitude sweep tests were performed on a range of ... more ABSTRACT Streaming potential measurements and amplitude sweep tests were performed on a range of Andosols from South Chile to find out about aggregation strength and mechanisms, as well as thixotropy and microstructural stability. Different stages in soil development and types of land use (pasture vs. natural forest) were considered and compared. Younger, alu-andic Andosols along with Al-humus-complexes contained higher levels of volcanic glass, indicated by their low pH values (pHH2O&lt;5pHH2O&lt;5), and high ratios of sodium pyrophosphate extractable Al (Alp) to acid ammonium oxalate extractable Al (Alo) (Alp/Alo &gt; 0.5). Alu-andic Andosols were also found to have (super)hydrophobicity in addition to typically high contents of amorphous iron (ferrihydrite). On the contrary, in well-developed, sil-andic Andosols (Alp/Alo &lt; 0.5), allophane contents increased, accompanied by higher pH values (pHH2O&gt;5pHH2O&gt;5 and &lt;7). Based on rheological data, the gel–sol–gel transformation (thixotropy) was better defined in sil-andic Andosols. Integral z, a dimensionless rheological parameter that represents quasi-elasticity was used to quantify stiffness degradation, and to identify single stages of thixotropy in allophanic Andosols. Scanning electron micrographs revealed that mineralogical components were predominated by volcanic glass (e.g. vesicular) and amorphous iron oxides in addition to fungal hyphae in younger acidic Andosols, while these characteristics were absent in well-developed Andosols. Here weathered minerals e.g. biotite, as well as halloysite, (proto)imogolite and allophanes were identified, indicating desilication and a shift from alu-andic to sil-andic Andosols. Zeta potentials derived from conducted particle charge density (PCD) measurements supported the assumptions that (i) Al-humus-complexes promoted aggregation in partially superhydrophobic topsoils of alu-andic Andosols, especially at ungrazed sites (or 1 year under pasture), and that (ii) thixotropic behaviour is related to allophanic, sil-andic Andosols, and better pronounced at sites which had been under pasture for 50 years.
Structural stability of Marshland soils of the riparian zone of the Tidal Elbe River
Soil and Tillage Research, 2012
ABSTRACT
Development of soil structure and functions: How can mechanical and hydraulic approaches contribute to quantify soil structure dynamics?
Soil and Tillage Research, 2012
(Bio-)remediation of VCHC contaminants in a Technosol under unsaturated conditions
Biodegradation, 2012
The remediation of dense non-aqueous phase liquids has always been a concern of both public and s... more The remediation of dense non-aqueous phase liquids has always been a concern of both public and scientific interest groups. In this research work a modified physical concept of (bio)remediation of a volatile chlorinated hydrocarbon (VCHC) contamination was elaborated under laboratory conditions and modeled with HYDRUS-2D. In field dechlorination is influenced by both physicochemical and hydraulic properties of the substrate, e.g. texture, pore size distribution, pore liquid characteristics, e.g. viscosity, pH, surface tension, and dependent on the degree of saturation of the vadose zone. Undisturbed soil cores (100 cm³) were sampled from a Spolic Technosol. Considering hydraulic properties and functions, unsaturated percolation was performed with vertically and horizontally structured samples. VCHC concentrations were calculated prior, during, and after each percolation cycle. According to laboratory findings, microemulsion showed the most efficient results with regard to flow behavior in the unsaturated porous media and its accessibility for bacteria as nutrient. The efficiency of VCHC remediation could be increased by the application of a modified pump-and-treat system: the injection of bacteria Dehalococcoides ethanogenes with microemulsion, and extraction at a constant matric potential level of -6 kPa. Achieved data was used for HYDRUS-2D simulations, modeling in situ conditions, demonstrating the practical relevance (field scale) of performed unsaturated percolation (core scale), and in order to exclude capillary barrier effects.
Rheometry in Soil Mechanics: Microstructural Changes in a Calcaric Gleysol and a Dystric Planosol
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Papers by Wibke Baumgarten