In November 2015, a mining dam failure dumped approximately 32 million m3 of very fine iron-rich tailing material into the Doce River watershed and the adjacent continental shelf, Southeast Brazil. Previous settling column experiments demonstrated different properties and behavior of flocs between natural sediment samples and those contaminated by the iron ore tailing, in which the presence of smaller and more porous flocs in the last was explained by a very fine fraction of clay and or a metallic coating (Grilo et al., 2018). As nanoparticles possess unique physical and chemical properties due to their high specific area and nanoscale size, their transport, persistence and bioavailability in the environment are essential aspects to be considered in risk assessment and management (Wiesner et al., 2009). Nanoparticles such as iron oxyhydroxide hold high reactivity with different ions (Antelo et al., 2005), where adsorption may increase or decrease the charge on the surface of nanoparticles and affect their stability (Breeuwsma and Lyklema, 1973).