Using oxygen isotopes

There are three stable isotopes of oxygen which have the following abundances  

Oxygen is liberated from silicates and oxides through fluorination with F2 or BrF5 and then reduced to CO2 at high temperature for measurement in a mass spectrometer. In carbonates carbon dioxide is liberated with 103 % phosphoric add. When oxygen isotope ratios are determined in water the sample is equilibrated with a small amount of CO2 and the oxygen isotope ratio in the CO2 is measured. From the known water-C02 fractionation factor, the 0/ 0 ratio in the water is calculated. The predsion of 5 0 values is of the order of 0.1-0.2 /m. 

In this section we consider first the distribution of oxygen isotopes in nature and then the use of oxygen isotopes in thermometry. This Is followed by a discussion of correlation diagrams which combine both oxygen isotopes and radiogenic isotopes and the way in which such correlations may be used to infer geological processes. 

Andesites and rhyolites Granitoids. Metamdrphic rocks Decrital sediments rgillic sediments Limestone  

Meteoric water Magmatic water Metamorphic water 

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The finest particles composed of fine silt and clay are carried over much larger distances (Fig. 1.6). Using oxygen isotopes of aeolian quartz, it has been shown that significant quantities of dust with an average diameter of 1-10 microns are transported by jet streams from desert zones over the rest of the world. Eolian admixtures have been referred to explain the presence of Si02 in soils developed in non-quartz-containing volcanic rocks in Hawaii and Israel. 

Table 2.5 gives the 5 0-valnes of commonly used oxygen isotope standards on both scales (parenthesis denote calcnlated values). 

Dontsova, Ye.I., 1964. An attempt to use oxygen isotope ratios in geochemical investigations. In Khimiya zemnoy kory (Chemistry of the Earth s Crust). Izd. Nauka, Moscow, pp. 631-637 (in Russian). 

The most signihcant complication in using oxygen isotopes to determine both absolute temperatures as well as relative temperature changes is that the of carbonate solids... 

Baxter, J.M. and M.E. Hobbs Cigarette smoke studies using oxygen isotopes. Carbon dioxide and carbon monoxide produced by combustion 20th Tobacco Chemists Research Conference, Program Booklet and Abstracts, Vol. 20, Paper No. 23, 1966, p. 29. 

Baxter, J.E. and M.E. Hobbs Investigation of some physico-chemical aspects of cigarette smoke using oxygen isotopes. CO and COj from atmospheric oxidation Tob. Sci. 11 (1967) 65-71. 

Stable isotope ratios are measured relative to a standard and are expressed in parts per thousand, i.e, parts per mil ( /w). The isotope ratio is expressed as a 6 value, or del value as it is sometimes called. Using oxygen isotopes as an example, the 8 >value is calculated as follows ... 

Determining the surface kinetic parameters using oxygen isotopic exchange can be more complicated for oxide catalysts or catalysts with oxide supports. Oxygen exchange between the gas phase, the catalyst surface, and the catalyst bulk may result in the failure of the transient to relax... 

To further study the reaction between methane and the surface oxygen, we used oxygen isotope labeling to preferentially populate the surface state with Determining the isotope label of oxygen in carbon dioxide provides us with information on the reactions of methane with the lattice and the surface oxygen. The results at 973 K are shown in Fig. 7. 

By using oxygen isotope labels, the barium hydroxide catalyzed hydrolysis of the nucleotide cyclophosphate (40) to yield a 4 1 mixture of 3 - and 5 -monophosphates was shown by P-n.m.r. to occur with inversion at phosphorus. 

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