Calcium isotopic

Isotope Methods. The isotopes of calcium have relatively short half-lives and are readily counted using liquid scintillation or gamma counters as appropriate to the nuclide. Calcium isotopes may be quantitated in the excreta, blood, tissues or in the whole body. This has made them useful for many nutritional metabolic studies. However, because of safety concerns, radioactive isotopes are cumbersome to work with and many researchers are unwilling to administer them to human beings. This has limited the use of isotopes to those studies in which alternate methods are not available or are imprecise. Methodologies for stable isotopes of calcium, which may be safely used in human being, are becoming available for use in metabolism studies. These will be practical alternatives to radioactive isotopes in the future. [Pg.27]

DePaolo DJ (2004) Calcium isotopic variations produced by biological, kinetic, radiogenic and nucleosynthetic processes. Rev Mineral Geochem 55 255-288... [Pg.22]

Lee T, Papanastassiou DA, Wasserburg GJ (1978) Calcium isotopic anomalies in the Allende meteorite. Astrophys J 220 L21-L25... [Pg.60]

Skulan JL, DePaolo DJ, Owens TL (1997) Biological control of calcium isotopic abundances in the global calcium cycle. Geochim Cosmochim Acta61 2505-2510... [Pg.101]

Miller YM, Ustinov VI, Artemov YM (1966) Mass spectrometric determination of calcium isotope variations. Geochem Inter 3 929-933... [Pg.149]

Calcium Isotopic Variations Produced by Biological, Kinetic, Radiogenic and Nucleosynthetic Processes... [Pg.255]

Table 1. Natural abundances, measured isotope ratios, and enrichment factors used for Calcium isotopes.

Table 2. Calcium isotopic compositions of terrestrial volcanic rocks, with other related isotopic parameters.

Figure 9. (a) Box model of Skulan and DePaolo (1999) used to explain the 6 Ca variations found in the hone and soft tissue of vertehrates. The 6 Ca values of bone and soft tissue are generally determined by the ratios of the dietary Ca flux (V ), to the Ca fluxes due to bone formation (Pi,), and bone dissolution or loss (Vi). It is hypothesized that only the step associated with bone grovrth involves isotopic fractionation (lOOOlna = = -1.5). (b) Calculated effects on calcium isotopic fractionation due to variations of the... [Pg.272]

The deduced average input 5 Ca is not identical to the average volcanic rock value, but is lower by about 0.4%o (Fig. 14). This suggests that weathering may discriminate between calcium isotopes. This inference is supported by the few available data on soils (Fig. 14 Skulan and DePaolo 1999 Skulan 1999 Schmitt et al. 2003b). The soils generally have 5 Ca values that are higher than the volcanic rocks. Data to allow direct comparison of soils to parent rock material are not available. [Pg.278]

Clementz MT, Holden P, Koch PL (2003) Are calcium isotopes a reliable monitor of trophic level in marine settings Int J Osteoarchaeology 13(l-2) 29-36... [Pg.285]

Gussone N, Eisenhauer A, Heuser A, Dietzel M, Bock B, Bohm E, Spero H, Lea D, Buma J, Nagler, TF (2003) Model for kinetic effects on calcium isotope fractionation (6 Ca) in inorganic aragonite and cultured planktonic foraminifera. Geochim Cosmochim Acta 67 1375-1382 Halicz L, Galy A, Belshaw NS, O Nions RK (1999) High precision measurement of calcium isotopes in carbonates and related materials by multiple collector inductively coupled plasma mass spectrometry (MC-ICP-MS). J Anal Atom Spectr 14 1835-1838... [Pg.286]

Ireland TR, Fahey AJ, Zinner EK (1991) Hibonite-bearing microspherules a new type of refractory inclusions with large isotopic anomalies. Geochim Cosmochim Acta 55 367-379 Johnson CM, Beard BL (1999) Correction of instrumentally produced mass fractionation during isotopic analysis of Fe by thermal ionization mass spectrometry. Int J Mass Spect 193 87-99 Jungck MHA, Shimamura T, Lugmair GW (1984) Calcium isotope variations in Allende. Geochim Cosmochim Acta 48 2651-2658... [Pg.286]

Lee T, Papanastassiou DA, Wasserburg GJ (1977) Mg and Ca isotopic study of individual microscopic crystals from the Allende meteorite by the direct loading technique. Geochim Cosmochim Acta 41 1473-1485 Lee T, Russell WA, Wasserburg GJ (1979) Calcium isotopic anomalies and the lack of aluminum-26 in an unusual Allende inclusion. Appl J Lett 228(L93-L98) 661-662 Marshall BD, DePaolo DJ (1982) Precise age determinations and petrogenetic studies using the K-Ca method. Geochim Cosmochim Acta 46 2537-2545... [Pg.286]

Platzner I, Degani N (1990) Fractionation of stable calcium isotopes in tissues of date palm trees. Biomed Environ Mass Spect 19 822-824... [Pg.287]

Russell WA, Papanastassiou DA (1978a) Calcium isotope fractionation in ion-exchange chromatography. Anal Chem 50 1151-1153... [Pg.287]

Schmitt AD, Bracke G, Stille P, Kiefel B (2001) The calcium isotope composition of modem seawater determined hy thermal ionisation mass spectrometry. Geostandard Newsletter 25 267-275 Schmitt A-D, Stille P, Venneman T (2003a) Variations of the " Ca/ Ca ratio in seawater during the past 24 million years evidence from 5 Ca and values of Miocene phosphates. Geochim Cosmochim Acta 67 2607-2614... [Pg.287]

Skulan J, DePaolo DJ, Owens TL (1997) Biological control of calcium isotopic abundances in the global calcium cycle. Geochim Cosmochim Acta 61 2505-2510 Skulan J, DePaolo DJ (1999) Calcium isotope fractionation between soft and mineralized tissues as a monitor of calcium use in vertebrates. Proc Nat Acad Sci 96 13,709-13,713... [Pg.287]

Zhu P, Macdougall JD (1998) Calcium isotopes in the marine environment and the oceanic calcium cycle. Geochim Cosmochim Acta 62 1691-1698... [Pg.288]

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