Ecological Systems and Devices Annotation << Back COMBINED EFFECT OF TOXIC SUBSTANCES OF DIFFERENT NATURE ON A PLANT TEST OBJECT V.I. Ipatova The combined effect of the maximum permissible non-toxic and toxic concentrations of heavy metal molybdenum, light metal aluminum and non-metal fluorine on the culture of green chlorococcal microalgae Scenedesmus quadricauda (Turp.) Breb. with their joint presence in the medium according to the plan of a full-factor experiment was studied. Various mathematical approaches and criteria were used to assess the combined effects of the studied toxicants. The synergistic, additive and antagonistic effects of pair combinations of aluminum, molybdenum and fluorine on the culture of S. quadricauda are shown depending on their concentrations and duration of action. The combined action of non-toxic concentrations corresponding to the maximum allowable concentration for aluminum and the maximum allowable concentration of molybdenum for the growth of this culture leads to the toxic effect, in contrast to a similar combination of aluminum and fluorine, in which the toxic effect was not manifested. The paper discusses in detail the possible reasons for the change (increase or decrease) in the toxicity of the medium under the combined or separate effects of toxicants on the studied plant test object during its growth in long-term experiments. Keywords: Scenedesmus quadricauda, bioassay, combined effect, molybdenum, aluminum, fluorine. DOI: 10.25791/esip.4.2023.1364 Pp. 46-57.