Hypolimnion behavior of technetium in freshwater at various stages of eutrophicationстатья
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Дата последнего поиска статьи во внешних источниках: 6 октября 2021 г.
Аннотация:Highlights Both biotic and abiotic processes take part in Tc removal in freshwater. Tc uptake is significantly influenced by the lakes eutrophication stage. Both phototrophic and anaerobic organisms involved in Tc removal from fresh water. Tc reduction by biogenic sulfur and iron phases plays a role of antioxidation barrier. Stimulation of microbial processes can be used for in situ Tc bioremediation. Abstract The article presents a study of various mechanisms of hypolimnion technetium behavior which occur at different stages of waterbodies eutrophication. Eutrophication stage was found to be positively correlated with the rate of 99Tc removal from water phase. The study identified a complex biogeochemical mechanism of technetium behavior. Planktonic phototrophic community plays a pivotal role in such a mechanism by ensuring fast oxygen consumption in hypolimnion. This creates favorable conditions for the active development of anaerobic bottom bacteria of sulfur and iron cycles given nutrients inflow. Sulfates and nitrates were discovered to have inhibitory effect on 99Tc biosorption by bottom sediments due to oxidizing conditions. Apart from the shift of redox potential of the medium to reducing values, the 99Tc removal and partial immobilization are also promoted by the presence of inorganic mineral phases of reduced sulfur and iron. These phases form a reducing barrier in the silt, thus preventing the oxidation and migration of technetium. We suggest the ways of stimulating in situ waterbody remediation by means of various additives, which will allow irreversible immobilization of technetium in silt once several growth periods have passed.