“…Humic substances adsorb readily onto oxide minerals (Tipping, 1981;Davis, 1982;Murphy et al, 1992;Gu et al, 1994;Spark et al, 1997a;. Moreover, the presence of metal ions affects the adsorption of humic substances (Tipping, 1981;Liu and Gonzalez, 1999;Weng et al, 2002) and vice versa (Robertson and Leckie, 1994;Zachara et al, 1994;Murphy and Zachara, 1995;Vermeer et al, 1999;Christl and Kretzschmar, 2001). The final outcome with respect to both the humics adsorption to the oxides and the metal ion binding to the complex is the net result of various interactions, and depends on the nature of the surface and the humics, the type of metal ion and factors such as pH and ionic strength.…”