Uses of Stable Isotopes

I 2 0 moderator for natural uranium reactors 2. Fuel for thermonuclear reactors 

10 b 19.61 1. Neutron absorber in control rods and shielding 2. Neutron-capture medical therapy 

Of the three moderators that make possible a fission chain reaction in natural uranium, heavy water, graphite, or beryllium, heavy water has become the preferred material. It is used both as coolant and moderataor in heavy-water reactors, which are the exclusive source of nuclear power in Canada, Argentina, and Pakistan, are being used in India, and are being considered in other countries wishing to have a nuclear power system not dependent on a source of enriched uranium. 

Deuterium, either mixed with tritium or in the form of Li deuteride, LiD, is an essential ingredient in the fuel proposed for fusion power reactors. In the magnetically confined type of fusion power system, the working substance is a plasma mixture of fully ionized deuterium and tritium. In the laser or electron beam imploded type of system, the fuel form is a small sphere containing deuterium and tritium or LiD. Although power systems of these types have not yet been proved feasible, their successful development would create a market for deuterium and Li as great as the current market for eruiched uranium. 

In some types of thermonuclear power systems it is desirable to use a blanket of lithium enriched in Li to increase the volumetric rate of neutron capture to produce tritium. 

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Determination of degradation by measurement of loss may be ambiguous since this fails to take into account transformation to metabolites. At field sites, loss by other processes such as volatilization is difficult to assess, but may be inferred, for example, from low concentrations of the more volatile alkylnaphthalenes. The use of stable isotopes is discussed in Chapter 13. 

Montgomery S, Lucotte M, Coumoyer L. 2000. The use of stable isotopes to evaluate the importance of fine suspended particulate matter in the transfer of methyhnercury to biota in boreal flooded environments. Sci Total Environ 261 33 1. 

Nisbet I, Montoya J, Burger J, Hatch J. 2002. Use of stable isotopes to investigate individual differences in diets and mercury exposures among common terns Sterna hirundo in breeding and wintering grounds. Mar Ecol Progr Ser 242 267-274. 

Gray, J. (1985), The use of stable isotope data in climate reconstruction, in Wigley, T. M. L., M. J. Ingram, and G. Farmer (eds.), Climate and History Studies in Ancient Climates and Their Impact on Man, Cambridge Univ. Press, Cambridge, UK. 

Rabinowitz M, Wetherill GW, Kopple JD. 1974. Studies of human lead metabolism by use of stable isotope tracers. Environ Health Perspect 7 145-153. 

Wada, E., Mizutani, H. and Minagawa, M. (1991). The use of stable isotopes for food web analysis. Critical Reviews in Food Science and Nutrition 30 361-371. 

Two features in caves facilitate the use of stable isotopes as a palaeoarchive (1) cave air temperatures remain relatively constant throughout the year and are similar to the mean annual temperature above the cave. (2) In cool temperate climate regions, cave air is characterized by very high humidity that minimizes evaporation effects. Interest in speleothems as recorders of continental palaeoenvironments has increased considerably in recent years. The potential of speleothems as climate indicators was first discussed by Hendy and Wilson (1968) followed by Thompson et al. (1974). These early investigators already recognized the complexity of cave carbonate iso-... 

System (3) described the use of stable-isotope-dilution mass spectrometry for the simultaneous determination of cortisol, cortisone, prednisolone, and prednisone in plasma [177]. Cortisol, cortisone, prednisolone, and prednisone were simultaneously extracted from acidified plasma on a Sep-Pak Ci8 cartridge. The column was eluted with methanol, the eluent evaporated, and the residue compounds reacted to their bismethylenedioxy-3-heptafluoro-n-butyryl derivatives by treatment with formaldehyde and heptafluoro-n-butyric anhydride. The derivatives were... 

Liptay, K., J. Chanton, P. Czepiel, and B. Mosher, Use of Stable Isotopes to Determine Methane Oxidation in Landfill Cover Soils, J. Geophys. Res., 103, 8243-8250 (1998). 

Isotope ratio measurements are performed whenever the exact ratio, or abundance, of two or more isotopes of an element must be known. For example, the isotopic ratios of lead are known to vary around the world, so it is possible to determine the source of lead in paint, bullets and petrol by knowing the isotopic abundances of the four lead isotopes 204, 206, 207, 208. Another example is the use of stable isotopes as metabolic tracers, where an animal is both fed and injected with an element having artificially enriched isotopes and the fractional absorption of the element can be accurately determined. 

This chapter demonstrates the usefulness of stable isotopes in investigating groundwater-lake systems. The discussion emphasizes isotopic applications to groundwater-lake systems characteristic of the temperate glaciated regions of the north-central and northeastern United States. Thus, it is also applicable to similar systems in other glaciated parts of the world, such as the Scandinavian peninsula and northern Asia. The applications stem from our experience with lake systems in the lake district of north-central Wisconsin. As such, we restrict our discussion to shallow groundwater systems that are hydraulically connected to freshwater lakes. 

Value of Isotopic Labeling. The experiments described demonstrate the usefulness of stable-isotope additions in understanding trophic interactions and biogeochemical fluxes in whole ecosystems. Using stable isotopes as chemical tracers in natural, undisturbed systems is especially helpful in interpreting the results of perturbation experiments. 

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