Biogeochemical Modelling of Uranium Immobilization and Aquifer Remediation Strategies Near NCCP Sludge Storage Facilities

Nitrate is a substance which influences the prevailing redox conditions in groundwater, and in turn the behaviour of U. The study of groundwater in an area with low-level radioactive sludge storage facilities has shown their contamination with sulphate and nitrate anions, uranium, and some associate...

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Bibliographic Details
Published in:Applied sciences 2021-03, Vol.11 (6), p.2875
Main Authors: Safonov, Alexey V., Boguslavsky, Anatoly E., Gaskova, Olga L., Boldyrev, Kirill A., Shvartseva, Olga S., Khvashchevskaya, Albina A., Popova, Nadezhda M.
Format: Article
Language:English
Subjects:
16S rRNA analysis
Anions
Aquifers
Bacteria
Biofilms
Biogeochemistry
Biological activity
bioremediation
Boreholes
Contamination
denitrification
Denitrifying bacteria
Genetic testing
Groundwater
Heavy metals
Immobilization
Iron
Microbial activity
Microorganisms
Modelling
Nitrates
Permeability
Radioisotopes
Rhodococcus
rRNA 16S
Sandy loam
Sludge
sludge pond
Stability analysis
Storage facilities
Sulfate reduction
Sulfate-reducing bacteria
Sulfates
Sulfides
Surface water
Uranium
uranyl ion
Whey
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Summary:Nitrate is a substance which influences the prevailing redox conditions in groundwater, and in turn the behaviour of U. The study of groundwater in an area with low-level radioactive sludge storage facilities has shown their contamination with sulphate and nitrate anions, uranium, and some associated metals. The uranyl ion content in the most contaminated NO3–Cl–SO4–Na borehole is 2000 times higher (1.58 mg/L) than that in the background water. At the same time, assessment of the main physiological groups of microorganisms showed a maximum number of denitrifying and sulphate-reducing bacteria (e.g., Sulfurimonas) in the water from the same borehole. Biogenic factors of radionuclide immobilization on sandy rocks of upper aquifers have been experimentally investigated. Different reduction rates of NO3−, SO42−, Fe(III) and U(VI) with stimulated microbial activity were dependent on the pollution degree. Moreover, 16S rRNA gene analysis of the microbial community after whey addition revealed a significant decrease in microbial diversity and the activation of nonspecific nitrate-reducing bacteria (genera Rhodococcus and Rhodobacter). The second influential factor can be identified as the formation of microbial biofilms on the sandy loam samples, which has a positive effect on U sorption (an increase in Kd value is up to 35%). As PHREEQC physicochemical modelling numerically confirmed, the third most influential factor that drives U mobility is the biogenic-mediated formation of a sulphide redox buffer. This study brings important information, which helps to assess the long-term stability of U in the environment of radioactive sludge storage facilities.
ISSN:2076-3417
2076-3417
DOI:10.3390/app11062875