A temporal study on fate of Al2O3 nanoparticles in a fresh water microcosm at environmentally relevant low concentrations.

This study on a microcosm, brings out the temporal changes in physico-chemical behavior of aluminum oxide nanoparticles (for a period of 210 days), at environmentally relevant concentrations (1000 μg/L and below). The dynamics of particle behavior in terms of mean hydrodynamic diameter, specific surface area and dissolution of soluble aluminum and, their possible ecological implications have been presented in this study. A thorough statistical analysis brings out nanoparticle behavior, where a rapid aggregation of particles (79±13 nm at 0 h to 1464±80 nm at 48 h), with a decrease in specific surface area (32 m2/g at 0 h to 1.7 m2/g at 48 h) was observed. Ion release profile indicated a significant increase in soluble aluminum concentration only after 36 h (277±15 μg/L at 0 h to 462±3 μg/L at 36 h) which reduced over a period of 60 days (279±20 μg/L). A differential response at 1000 μg/L concentration was observed, short term exposure (5 days) showed an immediate effect on the resident algal population (∼25% decreased viability) and the long term (7 months/210 days) exposure showed a gradual recovery. Thus, nanomaterials may not have the stipulated toxic response, at low concentration and longer standing period, presumably owing to the complexity of the natural systems.