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Effects of water content and moist conditions on soil organic matter (SOM) behaviour are reported by several authors. The state of moisture affects e.g. the kinetics of DOM release, thermal characteristics of SOM, soil respiration and the transport of matter through humic horizons. Some studies hint on the formation of a gel-like structure in the water containing SOM. As hydration times of SOM can range up to 2 or 3 weeks, hydration, water uptake and swelling of SOM ...Effects of water content and moist conditions on soil organic matter (SOM) behaviour are reported by several authors. The state of moisture affects e.g. the kinetics of DOM release, thermal characteristics of SOM, soil respiration and the transport of matter through humic horizons. Some studies hint on the formation of a gel-like structure in the water containing SOM. As hydration times of SOM can range up to 2 or 3 weeks, hydration, water uptake and swelling of SOM are phenomena which have to be understood in order to adequately describe and model transport phenomena. Despite this relevance, very little is known about water uptake and swelling behaviour of SOM. One reason for this lack of knowledge may be the difficulty to find experimental methods to observe and quantify water uptake of SOM, and to distinguish SOM water uptake from effects due to capillary effects or swelling of mineral particles. In this study, several methods, which have been transferred from other physical chemical disciplines, were tested. Combining gravimetry, centrifugation and calorimetric methods, the water uptake behaviour can be observed and described. The results show that water uptake of SOM is a process which is significantly slower than water uptake by mineral components. In this presentation, SOM water uptake under different electrolyte conditions will be discussed considering energetic, kinetic and methodological aspects. Conclusions will be drawn on physical chemical properties of SOM and on consequences for describing sorption behaviour of organic contaminants» weiterlesen» einklappen

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