Variation in Uranium Isotopic Ratios ²³⁸U/²³⁵U and ²³⁴U/²³⁸U and ²³⁶U/²³⁸U in Water Samples Collected from Private Wells in the Española Basin, Santa Fe, New Mexico

Technical Report · Mon Jul 29 04:00:00 EDT 2013

DOI:https://doi.org/10.2172/1088898· OSTI ID:1088898

Boukhalfa, Hakim ^[1]; Ware, Stuart D. ^[1]; Murrell, Michael T. ^[1]; Amato, Ronald S. ^[1]; Longmire, Patrick ^[2]

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1. Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
2. Environmental Geochemistry, Santa Fe, NM (United States)

This report presents uranium concentration and variation in uranium isotopic ratios ²³⁸U/²³⁵U and ²³⁴U/²³⁸U and ²³⁶U/²³⁸U in water samples collected from private wells in the Española basin in New Mexico. The document focuses specifically on analyzing variations in the uranium isotopic composition of the different water samples. The data presented in this report were obtained from water samples collected during the fall of 2012. A list of the different sampling locations as identified by their GPS coordinates is presented in Table 1 and represented on a map shown in Figure 1. Water temperature, conductivity, pH, and redox conditions (ORP) were also measured at the time of sampling and are also presented in Table 1. The pH of the samples ranged between 7.10 and 8.49, the temperature between 11.30 and 16.58 ˚C, and the ORP between -182 and 202 mV. The conductivity of the samples was between 454 µS·cm^-1 and 1066 µS·cm^-1. The concentration of uranium in the samples varied widely and ranged between 11.5 and 776 µg/L. Uranium isotopic ratios conducted by Thermal Ionization Mass Spectrometry (TIMS) showed natural ²³⁸U/²³⁵U within analytical uncertainty. The water samples showed some variations in the isotopic ratios of ²³⁴U/²³⁸U, varying from atom ratios of 54.9×10^-6 to 226×10^-6 (activity ratios of 1.00 to 4.11), and indicating enrichment of ²³⁴U in many of the water samples. These isotopic ratios are within the range observed in natural water. Such enrichments in ²³⁴U in natural waters are common and typically attributed to natural processes. There was no detectable ²³⁶U in any of the samples analyzed.

• Research Organization: Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• DOE Contract Number: AC52-06NA25396
• OSTI ID: 1088898
• Report Number(s): LA-UR--13-25923
• Country of Publication: United States
• Language: English

Related Subjects

07 ISOTOPE AND RADIATION SOURCES
54 ENVIRONMENTAL SCIENCES
58 GEOSCIENCES