Humic substances adsorbed on mineral particles
promote the sorption of both hydrophobic organic
compounds (Murphy et al., 1990) and metallic cations
(Zachara et al., 1994; Spark et al., 1997). Mineral-bound
humic substances modify inorganic surfaces, changing
the nature and number of complexation sites for contaminants
and provide, therefore, a major sink for the
removal of contaminants in liquid media and to prevent
groundwater contamination