Zofia Sokołowska

Database of Polish arable mineral soils: a review

Abstract The database of Polish arable mineral soils is presented. The database includes a lot of information about the basic properties of soils and their dynamic characteristics. It was elaborated for about 1 000 representative profiles of soils in Poland The database concerns: particle size distribution, organic carbon content, acidity-pH, specific surface area, hydrophobicity - solidliquid contact angle, static and dynamic hydrophysical properties, oxidation-reduction properties and selected biological (microbiological) properties of soils. Knowledge about soil characteristics is indispensable for description, interpretation and prediction of the course of physical, chemical and biological processes, and modelling these processes requires representative data. The utility of simulation and prediction models describing phenomena which take place in the soil-plant-atmosphere system greatly depends on the precision of data concerning characteristics of soil. On the basis of this database, maps of chosen soil properties are constructed. The aim of maps is to provide specialists in agriculture, ecology, and environment protection with an opportunity to gain knowledge of soil properties and their spatial and seasonal variability.

Electric double layer capacitance of restricted primitive model for an ionic fluid in slit-like nanopores: A density functional approach.

We apply recently developed version of a density functional theory [Z. Wang, L. Liu, and I. Neretnieks, J. Phys.: Condens. Matter 23, 175002 (2011)] to study adsorption of a restricted primitive model for an ionic fluid in slit-like pores in the absence of interactions induced by electrostatic images. At present this approach is one of the most accurate theories for such model electric double layers. The dependencies of the differential double layer capacitance on the pore width, on the electrostatic potential at the wall, bulk fluid density, and temperature are obtained. We show that the differential capacitance can oscillate as a function of the pore width dependent on the values of the above parameters. The number of oscillations and their magnitude decrease for high values of the electrostatic potential. For very narrow pores, close to the ion diameter, the differential capacitance tends to a minimum. The dependence of differential capacitance on temperature exhibits maximum at different values of bulk fluid density and applied electrostatic potential.

Adsorption of nitrogen and water vapor by alluvial soils

Abstract We report on the results of investigations on the adsorption of nitrogen at 79 K and water vapor at 293 K on several Polish alluvial soils. The experimental adsorption data have been used to evaluate the surface fractal dimension from Frenkel–Halsey–Hill (FHH) equation and to evaluate the adsorption energy distribution function by using a modified numerical method that has been developed by Stanley and Guiochon [J. Phys. Chem. 97 (1993) 8098–8102] for non-fractal adsorbents. We have investigated the correlations between the surface fractal dimensions and the average values of the adsorption energy with several physico-chemical properties of soils. We have found that these quantities correlate with the content of the clay fraction and with the cation exchange capacity. We did not find any correlation between the geometric or energetic heterogeneity parameters and the content of the organic matter.

Interactions of Zn(II) Ions with Humic Acids Isolated from Various Type of Soils. Effect of pH, Zn Concentrations and Humic Acids Chemical Properties.

The main aim of this study was the analysis of the interaction between humic acids (HAs) from different soils and Zn(II) ions at wide concentration ranges and at two different pHs, 5 and 7, by using fluorescence and FTIR spectroscopy, as well as potentiometric measurements. The presence of a few areas of HAs structures responsible for Zn(II) complexing was revealed. Complexation at α-sites (low humified structures of low-molecular weight and aromatic polycondensation) and β-sites (weakly humified structures) was stronger at pH 7 than 5. This trend was not observed for γ-sites (structures with linearly-condensed aromatic rings, unsaturated bonds and large molecular weight). The amount of metal complexed at pH5 and 7 by α and γ-structures increased with a decrease in humification and aromaticity of HAs, contrary to β-areas where complexation increased with increasing content of carboxylic groups. The stability of complexes was higher at pH 7 and was the highest for γ-structures. At pH 5, stability decreased with C/N increase for α-areas and -COOH content increase for β-sites; stability increased with humification decrease for γ-structures. The stability of complexes at α and β-areas at pH 7 decreased with a drop in HAs humification. FTIR spectra at pH 5 revealed that the most-humified HAs tended to cause bidentate bridging coordination, while in the case of the least-humified HAs, Zn caused bidentate bridging coordination at low Zn additions and bidentate chelation at the highest Zn concentrations. Low Zn doses at pH 7 caused formation of unidentate complexes while higher Zn doses caused bidentate bridging. Such processes were noticed for HAs characterized by high oxidation degree and high oxygen functional group content; where these were low, HAs displayed bidentate bridging or even bidentate chelation. To summarize, the above studies have showed significant impact of Zn concentration, pH and some properties of HAs on complexation reactions of humic acids with zinc.

Water stability of aggregates in subtropical and tropical soils (Georgia and China) and its relationships with the mineralogy and chemical properties

Water-stable aggregates isolated from three subtropical and one tropical soil (Western Georgia and China) were studied for their organic carbon, cation exchange capacity (CEC), specific surface area, magnetic susceptibility, and total chemical elements. The soils were also studied for their particle-size distribution, mineralogy, and nonsilicate Fe and Al oxides. Describe the water stability, three indices have been used: the content of water-stable macroaggregates (>0.25 mm), the mean weighted diameter of the aggregates, and the numerical aggregation index. The yellow-cinnamonic soil (China) was neutral, and the three other soils were acid. The soils were degraded with a low content of organic matter. The yellow-cinnamonic soil was characterized by the lowest water stability due to the predominantly vermiculite composition of the clay. The high water stability of the Oxisol structure was determined by the kaolinites and high content of oxides. In three out of the four soils studied, the hierarchical levels of the soil structure organization were defined; they were identified by the content of organic matter and the Ca + Mg (in Oxisols). Iron oxides mainly participated in the formation of micro-aggregates; Al and Mn contributed to the formation of macroaggregates. The water-stable aggregates acted as sorption geochemical barriers and accumulated Pb, Zn, Cd, Cs, and other trace elements up to concentrations exceeding their levels in the soil by 5 times and more. The highest correlations were obtained with CEC, Mn, and P rather than with organic carbon and Fe.

On the role of energetic and geometric heterogeneity in sorption of water vapour by soils: Application of a fractal approach

Abstract A new theory is proposed for describing adsorption of gases on geometrically and energetically nonuniform surfaces of soils. According to the proposed approach, the geometric nonuniformity is described by the fractal dimension of a surface and the energetic heterogeneity of adsorbing centres by an energy distribution function. The well-known Freundlich and Dubinin-Raduskevich adsorption isotherms are special cases of the proposed theory. The theory is then applied to a description of water vapour adsorption on samples of an Orthic Luvisol, taken from four horizons. The soil adsorbents were first analysed in order to obtain information concerning their mechanical composition, distribution of organic matter among particular mechanical fractions, as well as their mineralogical composition. The presented method of analysis of adsorption data leads to evaluation of the fractal dimensions of external and total surfaces, as well as to the energy distribution functions, thus characterizing the energetic heterogeneity of the investigated samples.

Density functional approach to the description of fluids in contact with bilayers

We discuss an application of a density functional approach to describe a bilayer, or a simplified model of a membrane, that is built of tethered chain molecules. The bilayer integrity is maintained by tethering chain particles to two common sheets. We study the structure of a two-component mixture in contact with the bilayer, as well as the solvation force acting between two bilayers, immersed in a fluid. The fluid is a binary mixture involving the component that can cross freely the bilayer and the second impenetrable component. All the calculations are carried out for athermal system, in which only hard-core interactions are present.

Comparison of fractal dimensions of soils estimated from adsorption isotherms, mercury intrusion, and particle size distribution

The values of the surface fractal dimensions were determined for several samples of Cambisols and Luvisols from analysis of nitrogen and water vapor adsorption isotherms and from mercury intrusion data. Moreover, the values of fractal dimension characterizing the particle size distributions of soil samples were calculated by using a number-based method. For almost all investigated soils the values of the surface fractal dimension, obtained from water vapor isotherms were lower than those obtained from nitrogen isotherms. Largest were the surface fractal dimensions evaluated form mercury intrusion data. No significant correlations between different kinds of surface fractal dimensions were found, and the reasons of this finding are discussed. However, the values of the surface fractal dimensions calculated from mercury intrusion data correlate with those characterizing the texture of soils. The paper also reports on correlations between of the values of surface area, fractal dimensions and some selected physico-chemical characteristics of soils. Vergleich der fraktalen Dimensionen von Boden auf Basis von Adsorptionsisothermen, Quecksilberporosimetrie und der Korngrosenverteilung An verschiedenen Proben von Braunerden aus Geschiebelehm und Sand wurden die fraktalen Oberflacheneigenschaften mittels Stickstoff- und Wasserdampfadsorption sowie Quecksilberporosimetrie bestimmt. Auserdem wurden charakteristische Werte fur die fraktalen Eigenschaften mit numerischen Methoden aus Texturanalysen abgeleitet. Es wurde nachgewiesen, dass fur fast alle untersuchten Boden die aus Wasserdampf-Adsorptionsisothermen abgeleiteten fraktalen Oberflachendimensionen niedriger sind als die Werte, die aus Stickstoff-Adsorptionsisothermen abgeleitet wurden. Die fraktalen Dimensionen, die auf Grund der porosimetrischen Daten berechnet wurden, waren am hochsten. Es wurde keine Korrelation zwischen verschiedenen Arten der fraktalen Oberflachendimensionen gefunden, und die Grunde dafur werden diskutiert. In der vorliegenden Arbeit werden auserdem Untersuchungsergebnisse uber die vorkommende Korrelation zwischen den Werten der Oberflache und der fraktalen Dimension und ausgewahlten physiko-chemischen Bodencharakteristiken besprochen.

Fractal dimension of peat soils from adsorption and from water retention experiments

Samples of peat soils characterized by different degree of the secondary transformation are studied by means of nitrogen and water vapor sorption. Moreover, we have also determined the water retention curves and the dependence of the hydraulic conductivity on water potential. The experimental data are interpreted in terms of fractal theories of adsorption and retention, yielding the values of the corresponding fractal dimensions. We discuss the relation between surface fractal dimensions obtained from nitrogen and water sorption data, as well as between the mass fractal dimension resulting from retention data. We have also tried to correlate the fractal dimensions to other physico-chemical properties of investigated soils.

Adsorption of ions on surfaces modified with brushes of polyampholytes

We apply density functional theory to study adsorption of ions, treated in the framework of the restricted primitive model (RPM), on surfaces modified by tethered polyampholytes. The residual electrostatic contribution to the free energy functional is approximated by using the approach proposed by Wang et al. [J. Phys.: Condens. Matter 23, 175002 (2011)] for simple nonuniform RPMs systems. Our research concentrates on the problems how the distribution of the charges within chains of polyampholytes changes the selectivity of adsorption of ions species, the structure of the surface layer, and its electric properties.