Uranium isotopic composition

The question was, did these variations reflect changes in the marine uranium isotopic composition or represent the effects of diagenesis ... 

Peninsula, Papua New Guinea (after Edwards et al. 1993). Open elhpses are data for samples collected from outcrop closed elhpses are data for samples collected from drill core. All points plot along the initial 5234 j =150 contom, indicating that all samples have maintained a primary marine uranium isotopic composition, consistent with closed-system behavior. Relatively yonng samples such as these are more likely to satisfy the closed-system assumption whereas older corals snch as those depicted in Figure 13 are not as likely to satisfy this assnmption. 

Esat TM, Yokoyama Y (1999) Rapid fluctuations in the uranium isotope composition of the oceans (abstract). Eos Transactions AGU 80(46(Fall meeting supl)) 581 Fomes WL, DeMaster DJ, Smith CR (2001) A particle introduction experiment in Santa Catalina Basin sediments Testing the age-dependent mixing hypothesis. J Marine Res 59(1) 97-112 Francois R, Bacon MP (1994) Heimich events in the North Atlantic radiochemical evidence. Deep-Sea Res 141 315-334... 

Boulyga, S. F. and Becker, J. S. 2001. Determination of uranium isotopic composition and U-236 content of soil samples and hot particles using inductively coupled plasma mass spectrometry. Fresen J Anal Chem 319(5), 612-617. 

In the first set, diffusion theory calculations are performed if no thin regions, such as tank walls, are included. When such regions are considered, DTF calculations in the S approximation are done. In these calculations, the metal density is 18 g/cm, tite uranium isotopic composition is 93.19 wt% " U and 6.81 wt% and all regions are concentric spheres. The princlpu variables are the metal mass, the solution volume, and the concentration of uranium in solution. 

One important aspect, often overlooked, is the availability of suitable reference standards for testing the analytical methods. The recertification of a standard UO2 fuel pellet for uranium isotopic composition is helpful for validation of analytical methods (Kraiem et al. 2013). Exact isotope ratios were measured by TIMS and the 235U/238U ratio was recertified in six randomly selected CRM 125-A pellets. The minor isotope ratios and were also recertified and the absence of... 

One of the first studies that characterized fine differences in the uranium isotopic composition in ore samples from various locations used a quadrupole mass spectrometer with a gas inlet to measnre the 235u/238pj jj, TIMS... 

Herrmann, A.D., Wasylenki, L., and Anbar, A.D. (2010) Uranium isotopic composition of carbonate sediments as a potential redox proxy. Geol. Soc. Am. Abstr. Programs, 42 (5), 514. 

Paces, J.B., E.M. Taylor, and C.A. Bush. 1993. Late quaternary histoiy and uranium isotopic compositions of ground water discharge deposits. Crater Flat, Nevada, p. 1573-1580. In Proc. from the 4th Int. Conf. on High Level Radioactive Waste Management. Am. Nucl. Soc., La Grange Park, IL. 

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