Adsorptive retention of copper on olivine is predominantly governed by the pH of the system (Kleiv,
2001; Kleiv and Sandvik, 2002). As is apparent from the obtained results, the post-maxima decrease (i.e. the desorption phase) displayed in Fig. 4 is in agreement with the corresponding neutralisation isotherms of Fig. 2, even though there is a slight off set between the pH peaks and the retention peaks. The _10:250’ neutralization isotherm peaks at pH 5.45 after approximately 5 min, whereas the corresponding retention peak occurs some 5 min later. The fact that the observed retention continues to increase although the pH of the system is decreasing must be contributed to kinetic factors.