Abstract |
The increasing and widespread applications of TiO2 engineered nanoparticles (nTiO(2)) led to the release of these materials into aquatic environments and consequently a change on the assessment of the environmental risk of trace metals. In this work, the role of two commercial nTiO(2) with distinct crystalline phases and sizes (nTiO(2)-P25: 80\% anatase + 20\% rutile, d=20 nm; nTiO(2)-NA: 100\% anatase, d=5 nm; 0.1 and 1.0 mg L-1) on Cd (112 mu g L-1) speciation, biouptake and toxicity for the freshwater bivalve Corbicula fluminea was evaluated. The electroanalytical technique absence of gradients and Nernstian equilibrium stripping (AGNES) was used to quantify the free Cd concentrations in the exposure medium in presence of both particles. Despite ca. 30-40\% decrease of free Cd in the medium in presence of nTiO(2), Cd uptake by C fluminea was similar in the absence and presence of either of the particles. Superoxide dismutase and glutathione-S-transferase activities remained unchanged for Cd in absence and presence of nTiO(2), whereas a significant increase of the catalase activity was obtained at the third day for Cd in presence of both nTiO(2). Despite lipid peroxidation data shows that the presence of both nTiO(2) seems to exert cells damage, a more quantitative description is not possible with the obtained data. The lack of clear-cut responses by the studied biomarkers, even when only in presence of Cd, do not allow insights into the effect of the presence of nTiO(2) on the Cd toxicity to the bivalves. Notwithstanding, morphological changes in the digestive gland were clearly obtained in the presence of Cd, nTiO(2) and Cd + nTiO(2) indicating an inflammatory response. (C) 2014 Elsevier Inc. All rights reserved. |