Effects of silver nanoparticles on the growth, mortality rate and morphology of Chlorella vulgaris and Thalassiosira weissflogii algae

In this paper, we study the effects of silver nanoparticles (AgNPs) on the growth of two species of algae, Chlorella vulgaris and Thalassiosira weissflogii. The AgNPs used in this experiment were chemically synthesised from a AgNO3 salt, with an average particle size of 7 nm in diameter. The test was conducted with five concentrations of AgNPs including 0 (control), 0.01, 0.1, 1 and 10 ppm. The results show that T. weissflogii is more sensitive to the solution of AgNPs than C. vulgaris. In particular when AgNPs solution is added to Erlenmeyer flask microalgae cultures from the start, the concentrations of 0.01 ppm and 0.1 ppm AgNPs do not affect the growth of C. vulgaris. They reach a stationary phase from the eighth to the tenth day of the experiment; the maximum algae density is not different from that of the control. At a concentration of 1 ppm AgNPs, C. vulgaris is completely dead after 96 h of exposure, and at a 10 ppm concentration, the algae is completely dead after 48 h of exposure. However, for T. weissflogii, AgNPs at a concentration of 0.01 ppm do not affect growth. From a concentration of 0.1 ppm, AgNPs alter the growth curve of algae, the maximum density of algae is lower than that of the control, and from a concentration of 1 ppm AgNPs, the algae are totally dead after 24 h of exposure.