Inhaltszusammenfassung

Transport of organic and inorganic colloids is strongly affected by the pore size distribution within the porous medium. However, this distribution cannot be assumed to stay constant under field conditions. The upper soil layers are exposed to dynamics in moisture and temperature. During changes of soil moisture, soil organic matter (SOM) changes its water content and its state of swelling. We expected the soil pore size distribution to be affected by the process of...Transport of organic and inorganic colloids is strongly affected by the pore size distribution within the porous medium. However, this distribution cannot be assumed to stay constant under field conditions. The upper soil layers are exposed to dynamics in moisture and temperature. During changes of soil moisture, soil organic matter (SOM) changes its water content and its state of swelling. We expected the soil pore size distribution to be affected by the process of swelling of SOM. In order to validate this thesis, we carried out 1H-NMR Relaxation. Air dry soil samples (sandy Ah and peat) were filled with water. Swelling kinetics were observed by 1H-NMR studies for 3 to 4 weeks after moistening the soil. The results indicate slow swelling kinetics lasting for several days up to weeks and hint at a change in pore size distribution within the soil samples. The change of pore size distribution is not the only effect of SOM swelling. Additional physicochemical changes are observed during swelling, as SOM sorbent properties or the kinetics of release of organic colloids and DOM. In this contribution, the kinetics of swelling as observed by 1H-NMR Relaxation are presented and discussed.» weiterlesen» einklappen

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