Abstract

In a radiotracer study, assimilation efficiency and efflux rate of Ag and Zn in the fresh water bivalve (Corbicular fluminea) fed to the two types of Ag nanoparticles (coated with citrate or polyvinylpyrrolidone) or ZnO particles amended with algae or seston diets were determined. These were compared with those clams fed to the diets treated with dissolved Ag and Zn. Additionally, subcellular partitioning of Ag and Zn in tissues of the clam after 21d depuration of bioaccumulated metals were compared. The clams were capable of assimilating (AE) Ag and Zn from the ingested nanoparticles and assimilation efficiency was higher for Zn (22-47%) than Ag (15-27%). The AE in the clams fed the food treated with dissolved Zn (56-58%) was higher than those treated with dissolve Ag (7-25%). Ag and Zn release from the clams during 21-d depuration followed two compartment model, initial rapid loss (20-30%) in 3-4 d of depuration and followed by much slower rate for Ag (0.003-0.006 d-1) and Zn (0.002-0.006d-1). The subcellular partitioning of Ag in the clam tissue was mostly in cellular debris (45-60%) and heat sensitive protein (20-30%), while Zn was distributed mostly in cellular debris (50%) and organelles (30%).