Uranium in natural waters and the environment: Distribution, speciation and impact

Smedley, Pauline; Kinniburgh, D.G.

doi:10.1016/j.apgeochem.2022.105534

Cited by 68 publications

(24 citation statements)

References 661 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

Section: ■ Introductionmentioning

confidence: 99%

“…2,3 Indeed, reduced, tetravalent U [U(IV)] is considerably less soluble than the oxidized, hexavalent state [U(VI)], and consequently, reduction of aqueous U(VI) to insoluble U(IV) species is known to decrease its aqueous concentration. 1,4,5 Reduction of U(VI) to U(IV) can happen through biotic (e.g., bacteria enzymatically reducing uranium) 6,7 and abiotic [e.g., through Fe(II) species, that can be produced via microbial metabolism] processes. 8−10 Thus, to initiate reduction, contaminated groundwater can be amended with abiotic reductants, such as sulfide reagents or hydrogen gas, or with an electron donor (acetate, lactate) that stimulates microbial growth.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Following the discovery of nuclear fission in the 1940s, its economic importance increased greatly and mining, energy, and military industries became anthropogenic sources of U in natural waters . Existing remediation strategies include physical barriers or covers, plant uptake of radioelements, constructed wetlands, and abiotic or biotic strategies based on U reduction. , Indeed, reduced, tetravalent U [U(IV)] is considerably less soluble than the oxidized, hexavalent state [U(VI)], and consequently, reduction of aqueous U(VI) to insoluble U(IV) species is known to decrease its aqueous concentration. ,, Reduction of U(VI) to U(IV) can happen through biotic (e.g., bacteria enzymatically reducing uranium) , and abiotic [e.g., through Fe(II) species, that can be produced via microbial metabolism] processes. − Thus, to initiate reduction, contaminated groundwater can be amended with abiotic reductants, such as sulfide reagents or hydrogen gas, or with an electron donor (acetate, lactate) that stimulates microbial growth. The objective is to reduce U directly, enzymatically by the native microbial communities, or indirectly, by the formation of reduced compounds that reduce U abiotically, such as Fe(II) or sulfide species .…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Reducing Conditions Influence U(IV) Accumulation in Sediments during In Situ Bioremediation

Janot,

Dunham-Cheatham,

Lezama Pacheco

et al. 2024

ACS Earth Space Chem.

View full text Add to dashboard Cite

This study presents field experiments conducted in a contaminated aquifer in Rifle, CO, to determine the speciation and accumulation of uranium in sediments during in situ bioreduction. We applied synchrotron-based X-ray spectroscopy and imaging techniques as well as aqueous chemistry measurements to identify changes in U speciation in water and sediment in the first days follwing electron donor amendment. Limited changes in U solid speciation were observed throughout the duration of this study, and non-crystalline U(IV) was identified in all samples obtained. However, U accumulation rates strongly increased during in situ bioreduction, when the dominant microbial regime transitioned from iron-to sulfate-reducing conditions. Results suggest that uranium is enzymatically reduced during Fe reduction, as expected. Mineral grain coatings newly formed during sulfate reduction act as reduction hotspots, where numerous reductants can act as electron donors [Fe(II), S(II), and microbial extracellular polymeric substances] that bind and reduce U. The results have implications for identifying how changes in the dominant reducing mechanism, such as Fe versus sulfate reduction, affect trace metal speciation and accumulation. The outcomes from this study provide additional insights into uranium accumulation mechanisms in sediments that could be useful for the refinement of quantitative models describing redox processes and contaminant dynamics in floodplain aquifers.

show abstract

Section: ■ Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Reducing Conditions Influence U(IV) Accumulation in Sediments during In Situ Bioremediation

Janot,

Dunham-Cheatham,

Lezama Pacheco

et al. 2024

ACS Earth Space Chem.

View full text Add to dashboard Cite

show abstract

“…This is because colloids moving in groundwater show complicated behaviors, such as moving in the aquifer and adsorbing into the soil. [3][4][5][6][7] The retained water generated in a nuclear reactor from the accident at Fukushima Daiichi Nuclear Power Station (referred to as FDiNPS) was analyzed and particulate solids containing alpha nuclides, such as U were reported. 8 The formation mechanism is not clear.…”

Section: Introductionmentioning

confidence: 99%

Uranium hydroxide/oxide deposits on uranyl reduction

et al. 2023

View full text Add to dashboard Cite

show abstract

“…Uranium and thorium, both being lithophile elements, are ubiquitous throughout the natural environment and found in igneous, metamorphic, and sedimentary rocks [1]. Uranium ( 235 U, 238 U) and thorium ( 232 Th) are responsible for three radioactive decay series that contain radiogenic radionuclides [2].…”

Section: Introductionmentioning

confidence: 99%

Time-frequency analysis of radon and thoron data using continuous wavelet transform

Rasheed,

Osama,

Rafique

et al. 2023

Phys. Scr.

View full text Add to dashboard Cite

Continuous exposure to environmental radiation, whether it derives from natural or artificial sources, is thought to pose a substantial risk to public health. In addition to the health effects associated with prolonged exposure to environmental radiations, long-term measurements of these radiations can be used for a variety of beneficial purposes, such as the forecasting of impending earthquakes. Signal processing is an important application used for the purpose of forecasting. Wavelets, being signal-processing tools, are helpful in many applications such as anomaly detection in time series data. However, selection of the best wavelet for a particular application is still a problem that hasn’t found a satisfactory solution. In this study, we used continuous wavelet transform (CWT) on environmental radiations, specifically radon time series (RTS) and thoron time series (TTS) data, for the investigation of time-frequency information (TFI). The distribution of energy in the output wavelet decomposition have been investigated by several wavelet families such COIF4, DB4, SYM4 to detect frequency composition of signal and its relation with anomalies hidden in the observed data. Using discrete wavelet transform (DWT), specifically SYM4, DB4, and COIF4, we transformed the radon and thoron time series into a time-dependent sum of frequency components. Using CWT scalograms, the anomalies in the both of time series datasets (TSD) have been identified, and these anomalies have been associated with the seismic events that occurred during the period of the study. The results show that DB4 and SYM4 wavelets are good at identifying anomalies in original radon and thoron TSD, but SYM4 performs better for DWT-decomposed radon and thoron TSD.

show abstract

Uranium in natural waters and the environment: Distribution, speciation and impact

Cited by 68 publications

References 661 publications

Reducing Conditions Influence U(IV) Accumulation in Sediments during In Situ Bioremediation

Reducing Conditions Influence U(IV) Accumulation in Sediments during In Situ Bioremediation

Uranium hydroxide/oxide deposits on uranyl reduction

Time-frequency analysis of radon and thoron data using continuous wavelet transform

Contact Info

Product

Resources

About