One of the most pressing problems, both for the drainage basin of Lake Baikal and for the natural waters of the entire country, is pollution with biogenic elements (urea, ammonium, nitrates, phosphates, etc.), surfactants and detergents. Baikal water has a very weak mineralization. In this regard, an increase in the concentration of nutrients, surfactants and detergents can initiate the eutrophication of water bodies. The subsequent dying off of the phytomass, followed by rotting and a sharp decrease in oxygen, has a negative effect on biota organisms. In recent years, a very high hyperproduction of filamentous algae has been observed on Lake Baikal. This process, according to a number of researchers, is associated with the intensive development of the tourism business on the shores of Lake Baikal and, accordingly, an increase in anthropogenic pressure on the ecosystem of Lake Baikal. Every year Baikal is visited by about 1.5-2 million tourists, as a result of which about 780000 tons of waste are generated. Every year, the lake receives about 60 million tons of wastewater from settlements and from enterprises located on its banks. To predict the situation in a reservoir with the accumulation of nutrients, as well as in the development of phytoremediation measures, information is needed on the interaction of processes in the “plants-biogens-surfactants” system.
Based on the foregoing, the purpose was to study the ability of the macrophytes Elodea canadensis to absorb ammonium from the aquatic environment and the effect of the anionic surfactant sodium dodecyl sulfate (SDS) on this process.
E.canadensis was collected in the Angara River (Irkutsk) in the spring-autumn period of 2020. Before the experiments, elodea was incubated in laboratory conditions for three days at a temperature of 8°C under intense illumination.
In the experiments, a 20 g/l sample of E.canadensis was incubated in the tested solutions of NH4+ (2-4 mg/l) and SDS (1·10-5, 1·10-4, 2·10-5, 5·10-5 M) for 3 days. The change in the concentration of these substances under the influence of macrophytes was assessed by a photometric method: of the mass concentration of ammonium - to GD 52.24.486-2009 (with Nessler's reagent); the concentration of surfactants - to 14.1:2:3:4.10-04. The results were compared with the kinetics of the content of the studied compounds in the absence of plants, which could change in the natural processes of oxidation with atmospheric oxygen or microorganisms.
Statistical data processing was performed using the Microsoft Office software package. The experiments were carried out in 5 independent experiments, 3 replicates in each experiment. The conclusions were made with the probability of an error-free prediction P≥0.95.
When studying the effect of SDS on the dynamics of the elimination of ammonium in E.canadensis, it was shown that in 2 days of the experiment this plant absorbed up to 92% of ammonium (as a percentage of the initial).
Experiments have shown the negative effect of SDS on the elimination of ammonium by E.сanadensis at its content from 1·10-5 M. The absorption of ammonium in the presence of SDS in the indicated concentration was 51% (as a percentage of the initial), which is 40% less than without the effect of the pollutant. The rest of the surfactant concentrations were found to be inactive - the kinetics of the ammonium content was comparable to the intensity of absorption by elodea without the effect of SDS.
It was also shown that E. сanadensis reduced the content of SDS in water (at its initial concentration of 2 mg/L) by 90% compared to the initial one.
The experimental studies carried out are part of an extensive block of work on the study of the processes of interaction of aquatic plants with surfactants and nutrients in their joint presence in aquatic environments. The described preliminary materials demonstrate the promising nature of E.сanadensis as a possible object for use in phytoremediation technologies for purifying waters with complex pollution - biogenic elements and surfactants.
The work was carried out within the framework of the project "Development of an environmentally friendly, cheap, simple, highly effective technology for phytoremediation of aquatic environments in the Baikal region", implemented with the support of the grant competition for environmental projects En+Group. The studies were carried out using the Center for Collective Use of the Baikal Museum ISC (http://ckp-rf.ru/ckp/495988/).
|Affiliation of speaker||Irkutsk State University|
|Publication||IOP Conference Series: Earth and Environmental Science|