Inhaltszusammenfassung

In soils, the water contents change permanently, which resultsin shrinkage and swelling processes of soil organic matter (SOM). Recent studies have shown that the grade of swelling influences the physico-chemical properties of SOM. Although these effects are important factors for sorption and transport processes in soils, the knowledge about the interrelations between soil swelling and the physico-chemical characteristics of SOM is still insufficient. In the study presented here...In soils, the water contents change permanently, which resultsin shrinkage and swelling processes of soil organic matter (SOM). Recent studies have shown that the grade of swelling influences the physico-chemical properties of SOM. Although these effects are important factors for sorption and transport processes in soils, the knowledge about the interrelations between soil swelling and the physico-chemical characteristics of SOM is still insufficient. In the study presented here, we investigated the process of drying and rewetting in selected soil samples containing organic matter. Wettable and hydrophobic samples were compared. We focussed on the properties of dissolved organic matter. The soil samples were observed before and after drying and during cycles of re- wetting. The state of moisture and the hydrohobicity affected the surface tension, the electrolyte release and the amount and quality of the dissolved organic matter, which was indicated by the molecular size distribution, by the UV absorption of the size fractions, and probably also by the particle size distribution itself. From these observations, we conclude that the state of moisture of humic soil samples strongly affects many colloidal characteristics of DOM.» weiterlesen» einklappen

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