Inhaltszusammenfassung

Since the characteristics of the soil-water interface are not static but continuously changing, the relevant processes and mechanisms have a high impact on habitat, filter, buffer, storage and transformation functions. Linking the individual results and conclusions of recent studies regarding the dynamics of wetting characteristics under changing environmental conditions as water content (WC), pH and drying and wetting temperature of two contrasting anthropogenic sit...Since the characteristics of the soil-water interface are not static but continuously changing, the relevant processes and mechanisms have a high impact on habitat, filter, buffer, storage and transformation functions. Linking the individual results and conclusions of recent studies regarding the dynamics of wetting characteristics under changing environmental conditions as water content (WC), pH and drying and wetting temperature of two contrasting anthropogenic sites in Berlin (Germany), lead to two hypothetical models explaining differences in the nature of repellency between the sites and between wettable and repellent samples within each site. The chemical nature of repellency found at the one site can be best explained by hydrolysis-condensation reactions. The hysicochemical nature of repellency on the other site seems to be controlled by the arrangement of amphiphilic molecules as micelles or reverse micelles during the drying process. The surface characteristics of the so formed layers on the soil particle surfaces depend on number and size of amphiphilic molecules, pH and ionic strength in the soil solution. Probably, specific local soil characteristics determine which mechanism dominates and controls the nature of repellency. Thus, critical conditions which may favour SWR may be identified. A challenge for the further research is the development of methods which may verify the suggested mechanisms with model substances as well as with complex natural soil samples and to verify the relevance of the suggested mechanisms for soils of differing soil-type, climate, and land-use.» weiterlesen» einklappen

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