Toxic Effect ofAluminum OxideNanoparticles on GreenMicro-Algae dunaliella salina

Aluminum oxide nanoparticles are the most widely used nanoparticles in various industries.The
increasing use of nanoparticles in the past two decades and their entry into the industrial and non-industrial
waste water necessitates the assessment of potential effects of these substances in aquatic ecosystems. OECD
standard method was applied to determine the toxicity of this substance. After performing the detection range
testing, the cells of 7 treatments and 2 controls were counted every 24 hours for 72 hours in three replicates for
each concentration. After extraction, chlorophyll a and carotenoid were measured using spectrophotometry.
Scanning electron microscopy (SEM) was used to image the exposure of the algae cells to nanoparticles. The
72-hour levels of EC10, EC50, EC90, and NOEC, specific growth rate (μ), doubling time (G), and percent
inhibition (I%) were also calculated. The obtained 72-hour levels were EC10=1.6610-3, EC50=0.162, EC90=15.31,
and NOEC=16.2×10-2mg/L. The control and treatment algae had a significant difference in terms of cell density
and growth inhibition rate (p<0.05). Aluminum oxide nanoparticles had a significant impact on the shape and
topography of Dunaliella salina cells and resulted in their swelling and enlargement. A significant difference
existed in chlorophyll a and carotenoid concentrations between the treatment and control groups and the levels
of carotenoid decreased following increase in concentration of treatments (p<0.05). Aluminum oxide
nanoparticles have a significant toxic effect on Dunaliella salina. With increasing nanoparticles concentration,
Dunaliella salina chlorophyll and carotenoid concentration reduced significantly (p<0.05).