Combined effects of titanium dioxide and humic acid on the bioaccumulation of cadmium in Zebrafish

The combined effects of titanium dioxide (TiO(2)) nanoparticles and humic acid (HA) on the bioaccumulation of cadmium (Cd) in Zebrafish were investigated. Experimental data on the equilibrium Cd bioaccumulation suggest that only the dissolved Cd effectively contributed to Cd bioaccumulation in HA solutions whereas both the dissolved and TiO(2) associated Cd were accumulated in TiO(2) or the mixture of HA and TiO(2) solutions, due likely to the additional intestine uptake of the TiO(2)-bound Cd. The equilibrium Cd bioaccumulation in the mixed system was comparable to that in the corresponding HA solutions, and significantly lower than that in the corresponding TiO(2) solutions (n = 3, p < 0.05). The presence of either HA or TiO(2) (5-20 mg L(-1)) in water slightly increased the uptake rate constants of Cd bioaccumulation whereas combining HA and TiO(2) reduced the uptake rate constants. (C) 2011 Elsevier Ltd. All rights reserved.