Toxic Effect ofAluminum OxideNanoparticles on GreenMicro-Algae dunaliella salina

Abstract

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