Uranium Isotopic Disequilibrium in Ground Water as an Indicator of Anomalies

Osmond, J.K.; Cowart, James B.; Ivanovich, Μ.

doi:10.1016/b978-0-08-029158-1.50026-x

Cited by 27 publications

(38 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Such changes in groundwater composition, accompanied by increasing isotopic disequilibrium due to excess 234U, are well documented in the literature (e.g. Osmond and Cowart, 1976). However, the sampled groundwaters at Kamlunge contain significantly high amounts of dissolved U, even at a depth of 375 m. This indicates that true reducing conditions, which are normally reflected by extremely low U contents (usually less than 0.1 ppb), are therefore not present, and that the groundwaters at the deepest level sampled (Zone 3) are still marginally oxidizing.…”

Section: Resultsmentioning

confidence: 72%

“…According to secondary U accumulation processes as discussed by Osmond et al (1983), the present isotopic disequilibrium data from the fracture zones indicate a mixture of groundwater environments. For example, Km3F (Zone 2) suggests up-flow oxidizing conditions whereupon 23~ exceeds 2asU and 234U.…”

Section: Resultsmentioning

confidence: 99%

“…In the Kamlunge context, earlier U (and Th) enrichments are a characteristic feature of the fracture zones under investigation, and thus the fractures can be regarded as having been mineralized in a sub-economic sense. In contrast to Km3F, samples Km3G (Zone 2), Km3I and Km3J (Zone 3), and Km3L from the deepest sampled pegmatite, indicate a non-steady state system which, according to Osmond et al (1983), reflects an environment characterized by U mobilization events and relatively abrupt changes from precipitation to leaching processes. In such cases, 234U is in excess of 238U (reducing down-flow environment) and at the same time deficient in relation to 23~ (oxidizing up-flow environment).…”

Section: Resultsmentioning

confidence: 99%

“…1955Cherdynstev (e.g. , 1971) the methods have been subsequently improved and applied by many workers to a wide range of geological problems; see, for example, Rosholt (1959); Thurber (1962); Rosholt et al (1963); Koide and Goldberg (1965); Rosholt et al (1966); Kigoshi (1971); Kronfeld (1974); Osmond and Cowart (1976); Fleischer and Raabe (1978); Ivanovich and Harmon (1982);and Rosholt (1983).…”

Section: (~ Copyright the Mineralogical Societymentioning

confidence: 99%

See 3 more Smart Citations

Uranium-series disequilibrium studies of drillcore Km3 from the Kamlunge test-site, northern Sweden

Smellie¹

1985

Mineral. mag.

View full text Add to dashboard Cite

ABSTRACT. Studies of the U decay series (138U 234U 23~ have been carried out on samples from unaltered bedrock and highly altered fracture/crush zones from drillcore Km3 (Kamlunge test-site). The fracture zones are characterized by abundant iron oxide coatings (hematite and hydroxy iron oxides) resulting from the passage of hydrothermal solutions coeval with the Lina granite intrusion. Enrichments of U and Th, thought to be due to co-precipitation (or preferential sorption) processes together with the iron-oxides, are also present.The isotopic results show that out of a total of twelve rock samples measured, six indicate isotopic disequilibrium mostly due to unequal depletions of 234U and 238U; one near-surface sample indicated some minor assimilation of U. The major fracture zones generally indicate removal of total U. This has resulted from interaction with groundwaters which are still marginally oxidizing, even at depths of 375 m.Isotopic disequilibrium has occurred within recent geological times, i.e. during the last 0.5 Ma as imposed by the half-lives of 234U and 23~ In terms of radioactive disposal considerations, the results are important in that: (1) the investigated bedrock environment (100-500 m) is generally reducing; however (2) there is some evidence to indicate that rock/water interactions, leading to the removal of total U, have resulted from the presence of less reducing groundwaters within those large-scale fracture/ crush zones which intersect the bedrock surface.

show abstract

Section: Resultsmentioning

confidence: 72%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: (~ Copyright the Mineralogical Societymentioning

confidence: 99%

See 2 more Smart Citations

Uranium-series disequilibrium studies of drillcore Km3 from the Kamlunge test-site, northern Sweden

Smellie¹

1985

Mineral. mag.

View full text Add to dashboard Cite

show abstract

“…This isotopic fractionation of uranium isotopes was first discovered by Cherdyntsev (1955), and the mechanisms have been reviewed by Osmond and Cowart (1982). In addition, there may be chemical fractionation among the uranium daughter isotopes (protactinium, thorium, radium, radon, etc.)…”

Section: Introductionmentioning

confidence: 99%

Methods for obtaining sorption data from uranium-series disequilibria

Finnegan¹,

Bryant²

1987

View full text Add to dashboard Cite

Two possible methods have been identified for obtaining in situ retardation factors from measurements of uranium-series disequilibria at Yucca Mountain. The first method would make use of the enhanced 23< «u/ 238 U ratio in groundwater to derive a signature for exchangeable uranium sorbed on the rock; the exchangeable uranium would be leached and assayed. The second method would use the ratio of 222 Rn to 234 U in solution, corrected for weathering, to infer the retardation factor for uranium. Similar methods could be applied to thorium and radium.

show abstract

The importance of uranium isotope composition for gross alpha activity regulation

Scott¹,

Plechacek

Krinke³

2023

AWWA Water Science

View full text Add to dashboard Cite

Uranium is a regulated contaminant (maximum contaminant level [MCL] 30 μg/L) that contributes to the gross alpha activity of groundwater. The adjusted gross alpha activity (MCL 15 pCi/L) is determined by subtracting the total uranium activity from the measured gross alpha activity. U.S. water utilities can use mass-based and radiochemical analysis methods for compliance monitoring of uranium. Mass-based measurements use a conversion factor of 0.67 pCi/μg of uranium to calculate the adjusted gross alpha activity. This conversion factor assumes that the activity of 234 U equals 238 U. Here, we present two decades of uranium isotope data measured by alpha spectrometry that shows 234 U activity typically exceeds 238 U. Using mass-based measurements, the total uranium activity is biased low causing artificial exceedances of the adjusted gross alpha activity. Therefore, water utilities with gross alpha activities >15 pCi/L should utilize radiochemical analyses for uranium for the most accurate calculation of adjusted gross alpha activity.alpha spectrometry, gross alpha activity, groundwater, uranium isotope ratios | INTRODUCTIONUranium is regulated by the United States Environmental Protection Agency (EPA) due to its toxicological properties (Dinocourt et al., 2015;Selden et al., 2009;Zamora et al., 1998). The radionuclides rule was updated in 2000 to include a uranium maximum contaminant level (MCL) of 30 μg/L (US EPA, 2015). The radionuclides rule also addresses gross alpha activity. When the gross alpha activity is measured above 15 pCi/L, analysis of uranium is required to determine the adjusted gross alpha activity (gross alpha minus the uranium and radon activities). Establishing compliance with the MCL requires four consecutive quarterly samples, and initial compliance is based on the running average of these four initial samples. Any exceedance of the MCL during this period or in subsequent sampling efforts triggers additional quarterly monitoring. Ultimately, any entry point in a drinking water distribution system must demonstrate four consecutive quarterly samples below the MCL to comply with the radionuclides rule for adjusted gross alpha activity. Because total uranium activity is subtracted from the gross alpha activity for compliance monitoring, quantification of the total uranium activity is a critical factor for adhering to this regulation.Both radiochemical and mass-based measurements are approved for compliance monitoring of uranium under federal rule when this analysis is triggered by a

show abstract

Uranium Isotopic Disequilibrium in Ground Water as an Indicator of Anomalies

Cited by 27 publications

References 26 publications

Uranium-series disequilibrium studies of drillcore Km3 from the Kamlunge test-site, northern Sweden

Uranium-series disequilibrium studies of drillcore Km3 from the Kamlunge test-site, northern Sweden

Methods for obtaining sorption data from uranium-series disequilibria

The importance of uranium isotope composition for gross alpha activity regulation

Contact Info

Product

Resources

About