Abstract
The effect of silver salts (macroform) and colloidal silver nanoparticles (AgNP) (nanoform) on microalgae Scenedesmus quadricauda (Turp.) Breb. (= Desmodesmus communis (E. Hegew.) E. Hegew.) was studied. The change in the cells number was taken as the culture growth main indicator. Based on results of chronic tests, the magnitude of LC50 and threshold limit values TLV (LC20 ) were estimated and follow-up toxicity index, hazard index and hazard indicator of investigated substances were calculated .It was shown that silver salts in macro form are more toxic to the population of S. quadricauda, than nano form of silver. The tested substances can be ranged in the following order: AgNO3>Ag2SO4>AgNP according to their toxic effects on the change in the S. quadricauda number of cells, LC50 values, threshold concentrations (TLV) and calculated toxicity and hazard indexes in a long-term experiment. Toxicity of colloidal silver to Scenedesmus quadricauda occurred within 20 days after application of the preparation and the subsequent restoration of the cells number was due to the presence of resistant cells in the population.