INFLUENCE OF NANOCOMPOSITE Ag/AgCl ON THE CULTURE OF MICROALGAE SCENEDESMUS QUADRICAUDA AND PHAEODACTYLUM TRICORNUTUM

The toxicity of the Ag/AgCl nanocomposite was evaluated at different concentrations in chronic experiments for 41 days using standard freshwater and marine plant test organisms of Scenedesmus quadricauda (0.05, 0.1, 0.5 and 1.0 mg/l) and Phaeodactylum tricornutum (0.25, 0.5, 1.0, and 2.0 mg/L). Comparative sensitivity of test organisms in acute experiments (72 hours) in terms of LC50 was carried out. It was established that the green alga of S. quadricauda is more sensitive to the Ag/AgCl nanocomposite (LC50 = 0.02 mg/l) than the marine diatomea P. tricornutum (LC50 = 0.3 mg/l). The greatest algicidal effect on the growth of S. quadricauda culture was provided by the nanocomposite in concentrations of 1 and 0.5 mg/l, at which the culture did not grow during the experiment. And at concentrations of 0.1 and 0.05 mg/l the algostatic effect was observed for 10 and 1 days, respectively, after which the culture resumed growth. In the culture of P. tricornutum at concentrations of 1.0 and 2.0 mg/l there was a prolonged inhibition of growth, but after 25 days at 1.0 mg/l the number of cells began to increase. In the presence of 0.5 mg/l the culture resumed growth after 4 days of lag phase and overtook the number of control. At the concentration of 0.25 mg/l the growth of P. tricornutum was either at or above the control level. The difference in the response of the two species of algae can be explained both by the individual feature of the species and by the more complex composition of the marine nutrient medium, which reduces the toxicity of the nanocomposite. According to analytical electron microscopy silver from Ag/AgCl nanocomposites within a day falls inside the cells of S. quadricauda and P. tricornutum algae, passing unimpeded both through the cell wall and the cell membrane.

Scenedesmus quadricauda, Phaeodactylum tricornutum, nanocomposite Ag/AgCl, toxicity