Inhaltszusammenfassung

Under field conditions, soil is subjected to continuous moisture variations. This affects the state of swelling of soil organic matter. Although it is expected that the state of swelling of SOM alters other soil parameters and such effects have recently been published, very little is known about the process of swelling of soil organic matter itself. In this contribution, results from a study on the swelling of soil organic matter by several methods are presented w...Under field conditions, soil is subjected to continuous moisture variations. This affects the state of swelling of soil organic matter. Although it is expected that the state of swelling of SOM alters other soil parameters and such effects have recently been published, very little is known about the process of swelling of soil organic matter itself. In this contribution, results from a study on the swelling of soil organic matter by several methods are presented with a special emphasis on 1H-NMR Relaxation. We investigated peat samples and soil samples from Ah horizons and observed a gradual change in the pore size distribution and the amount of absorbed water during swelling, which went on for at least two to three weeks. The change could be described by a first order process with time constants up to 6 days. We also found an effect of the initial state before moistening, of the final water content and of the hydration time on the extractibility of PAH. These observations are supplemented by other studies showing an effect of the state of moisture on binding and sorption of organic compounds to soil. The results show that swelling of soil organic matter is a slow process and lasts for at least two to three weeks. It influences at least the pore size distribution and the state of binding of organic chemicals in soil. Thus, swelling has to be taken into consideration when sorption and transport phenomena under field conditions are a central point of interest. The method of 1H-NMR Relaxation is an important and powerful method for the investigation of swelling of soil organic matter in whole soil samples.» weiterlesen» einklappen

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