Inhaltszusammenfassung

The macromolecular structure of soil organic matter is an important factor for the sorption of organic pollutants, which is especially true for the distribution of glassy and rubbery regions within SOM and their stability during changing environmental conditions: Which factors affect the position and / or the proportion of glassy and rubbery domains? Glass transitions have been verified in cleaned humic substances. An increasing number of experimental evidences show that glass tran...The macromolecular structure of soil organic matter is an important factor for the sorption of organic pollutants, which is especially true for the distribution of glassy and rubbery regions within SOM and their stability during changing environmental conditions: Which factors affect the position and / or the proportion of glassy and rubbery domains? Glass transitions have been verified in cleaned humic substances. An increasing number of experimental evidences show that glass transitions can also be observed in soil samples. However, our experiments reveal some enigmatic phenomena. The apparent glass transition behaviour is affected strongly by the water status in the soil sample. Water content, residence time of water, drying and the method of drying give strong influence on the glass transition behaviour measured by Differential Scanning Calorimetry (DSC). The effects are only partly reversible and reveal slow relaxation. Glass-transition-like behaviour was also found in biofilms, showing partly similarity to the glass transitions in soil samples. In this contribution, the glass transitions in soil samples and biologic materials and their dependence on the water status are presented and the nature of the transitions is discussed: Do we observe glass transitions? Which other processes could be taken into consideration? Does microbiology affect these transitions and thus the physicochemical properties of soil organic matter?» weiterlesen» einklappen

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