The relevance of the work is determined by the increasing pollution of aquatic environments by toxic substances (including surfactants, hydrocarbons and their mixtures). As a result, it becomes necessary to develop methods for biotesting the quality of natural and waste waters that contain the above-mentioned substances, as well as to clarify the mechanisms of the toxic effect of pollutants. An important addition to obtain a more complete and objective characterization and forecast of the effects of pollutants is the study of the mechanisms of action of toxic substances.
The study of the electrical properties of solutions in which test organisms are incubated makes it possible to determine the degree of membrane permeability, and the dynamics of changes in its parameters under the influence of damaging factors. A number of works have shown that when the permeability of the membranes of organisms in an aqueous medium is disturbed, the electrical conductivity of solutions begins to increase, and when the cell is completely killed, the electrical conductivity of the object differs little from the environment.
Based on the analysis of literature materials, it can be expected that under the influence of surfactants and oil hydrocarbons, the barrier functions of the cell cytoplasm will change. In turn, this will cause disruption of concentration gradients and release of electrolytes from the cell. As a result, changes in the electrical conductivity of solutions will be recorded.
Violation of the permeability of cell plasma membrane under the influence of unfavorable environmental factors, including pollutants and their mixtures, is one of the initial stages of the body's response to the action of damaging agents. Therefore, the conductometry method makes it possible to determine the toxic effect of pollutants in aquatic environments, their effect on the physiology of algae, and can be recommended as an express test for the detection of pollutants.
The purpose of this communication was to study changes in the electrical conductivity of solutions under the action of surfactants and hydrocarbons on aquatic plants.
Elodea canadensis was chosen as a test object. Tween-80 was taken from the surfactant, since it is used in the remediation of oil pollution. Hexane was taken as oil hydrocarbons.
The electrical conductivity of water was measured with a portable conductometer Expert-002 (Econix-Expert, Russia) equipped with a built-in temperature compensation sensor. The conductivity value was adjusted to a temperature of 25 ° C.
In the experiments, we used a weighed portion of E. canadensis 4 g per 200 ml of solution. Elodea was collected in the r. Angara in the region of the mountains. Irkutsk. The experiments were carried out in five biological replicates with three parallel ones. The materials have been statistically processed. The conclusions are made at a confidence level of 95%.
The experiments showed that hexane in the concentration range of 50, 100, 150, 250 ml / L led to an increase in the release of electrolytes from E. сanadensis cells. At the same time, the concentration dependence was well traced: as the concentration increased, the electrical conductivity, and, consequently, the yield of electrolytes, increased. The effect of hexane was suppressed by the addition of Tween-80 at various concentrations (10, 50, 100, 250 ml / L). Pretreatment of E. canadensis for 30 minutes in a mixture of hexane 50 ml / L and Tween-80 in a 50:50 ratio significantly reduced the conductivity values to the control level and below. A similar situation was observed during pretreatment in Tween-80 for 30 minutes and further measurements in a hexane solution. In this case, the conductivity values were higher than the control.
Other surfactants, depending on the chemical structure and concentration, showed similar effects in some cases, and in others, on the contrary, increased toxicity.
At present, it is difficult to unambiguously interpret the multidirectional actions of surfactants in the system of aquatic plants - hydrocarbon. In subsequent experiments, an answer should be obtained about the mechanism of the observed effects.
The reported study was funded by RFBR and MECSS, project 20-54-44012 «Study of the interaction of metals, phenolic compounds with hydrophytes in phytoremediation processes and waste recovery». The research was carried out using the Center for Collective Use of the Baikal Museum of ISC (http://ckp-rf.ru/ckp/495988/).
|Affiliation of speaker||1) Irkutsk State University; 2) Baikal Museum of the Irkutsk Scientific Center|
|Publication||IOP Conference Series: Earth and Environmental Science|