Modelling Boom Clay organic matter interactions in pore water and with some RNs: Application of tipping’s model VII using GWB code

Tipping’s model VII and model parameters for Ca, Mg, Al, Eu, Th, and U(VI) are implemented in The Geochemist’s Workbench computer code and used for modelling (i) interactions between major cations in Boom Clay pore water and natural organic matter (NOM); (ii) past experiments performed at SCK CEN laboratories studying radionuclides and Boom Clay organic matter (BCOM) interactions. Modelling results indicated on the one hand that Tipping’s model seems a useful addition to a geochemical modelling toolbox accounting for the effect of NOM but on the other hand the applicability of its default parameters relevant for soil and surface water organic matter cannot be fully validated by the experiments involving the site specific BCOM. Model parameters specific for BCOM are needed and the underlying mechanisms controlling the colloidal behavior of BCOM are to be theoretically and experimentally investigated to a deeper extent.