Interaction of Zirconium and Tin with Boom Clay Dissolved Organic Matter

Boom Clay contains substantial amounts of organic matter (TOC content of 1-5 wt%) of low maturity with a significant watersoluble fraction (De Craen et al., 2004; Durce et al., 2015). The presence of Dissolved Organic Matter (DOM) was shown to influence the transport properties of several elements in present day Boom Clay conditions found at the Mol site (Bruggeman and De Craen, 2012). By analogy a series of radionuclides was defined as NOM-related transport elements (Bruggeman and Maes, 2017). However, up to this day, the binding with BC DOM of several of these elements and its influence on their mobility was never evidenced nor quantified. The current report deals with evidencing and quantifying the interaction of BC DOM with two of the less studied elements: Zirconium and Tin. The interaction were investigated relying on dialysis (solid and liquid) and ultrafiltration techniques. Two conditions, representative of repository scenarios were applied. On the one hand, experiments were performed in conditions representative of present day BC conditions found at the Mol site. On the other hand, a scenario of seawater intrusion was considered and experiments were performed in synthetic seawater. The extent and strength of binding was characterised by the calculation of binding constants conditional to each scenario.