EFFECTS OF TITANIUM DIOXIDE NANOPARTICLES ON POPULATION GROWTH RATE OF BRACHIONUS CALYCIFLORUS, Pallas, 1766.

Oluwagbemiga Areo,

ABSTRACT

This study was carried out to determine the toxicity of Titanium dioxide nanoparticles (TiO₂ NPs) to a freshwater planktonic rotifer, Brachionus calyciflorus. Reconstituted water was used as the medium for the toxicity tests for both acute and chronic exposures. Acute concentrations of 0.01, 0.05, 0.10, 0.50 and 1.00mg/l of TiO₂ NPs were used, from which the value of LC₅₀ was obtained to establish chronic concentrations of 0.0065, 0.008 and 0.016mg/l of TiO₂ NPs. The result of the acute toxicity test showed that TiO₂ NPs was toxic on Brachionus calyciflorus with 81.67% mortality recorded as the concentration of the toxicant increased from 0.01mg/l to 1.00mg/l and LC₅₀ of 0.065mg/l. For chronic exposure, population growth rate was determined. The exposure lasted 18 days, after which the population growth rate of the test organism significantly declined with increasing concentrations of TiO₂ NPs, with the best population growth rate of 0.304d^-1 at 0.0065mg/l concentration. This proves that TiO₂ NPs are toxic on Brachionus calyciflorus, which paves way for a potential inference in offsetting the entire freshwater habitat. However, for more efficiency, further studies should be directed towards measures of preventing and or controlling the accumulation of TiO₂ NPs in freshwater bodies and on aquatic organisms.