ABSTRACT
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Aluminum and iron oxides can cause sorptive stabilisation of dissolved
organic carbon (DOC) in soils. The purpose of this thesis is to determine the
quantitative influence of these pedogenic oxides on the sorption of DOC. For
this purpose a model in PHREEQC is developed which simulations sorption
and mineralisation of dissolved organic carbon. Unfortunately the model was
determined not valid because of the large RMSE and therefore the model
results are unreliable. This is due to a number of flaws in the model. The
main systematic error is caused by the fact that the sorption-compartment of
the model operates independent of the DOC in solution. This causes an
imbalance in mass; the model often generates DOC from nothing. Three
main model improvements are suggested. Firstly the manner in which
sorption is modeled needs to be reconstructed. Secondly modeling transport
will probably improve the model significantly. Lastly the time step needs to
be smaller and regular. This model is considered to be a step in the right
direction to a basic sorption and mineralisation model. It is expected that if
the suggested improvements will be executed the results are much more
accurate.