Strontium isotopes in environmental

Determination of Radio-strontium Isotopes in Environmental Samples... 

McNutt R. H. (2000) Strontium isotopes. In Environmental Tracers in Subsurface Hydrology, (eds. P. Cook and A. L. Herczeg). Kluwer Academic, Boston, pp. 234-260. 

Methods for Determining Parent Compounds and Degradation Products in Environmental Media. Analytical methods with the required sensitivity and accuracy are available for quantification of strontium, both total and isotopic, in environmental matrices (Table 7-2). Knowledge of the levels of strontium in various environmental media, along with the appropriate modeling (see Chapters 3 and 5), can be used to evaluate potential human exposures through inhalation and ingestion pathways. 

The two fission-produced radio-strontium isotopes of interest in environmental samples are 90Sr and 89Sr. Sr-90 has a fission yield of 5.8 %, a half-life is 28.78 a, and the radioactive daughter 90Y with a half life of 2.67 d, to which it decays by beta-particle emission. Sr-89 has a fission yield of 4.7%, a half life of 50.52 d, and decays to the stable daughter89 Y. The decay schemes given in Figure 13.1 show that these two radio-strontium isotopes for practical purposes can only be measured by beta-particle counting. 

Quantifying the sources and rates of input of base cation nutrients (calcium, magnesium, potassium, and sodium) to forest ecosystems is an important goal in forest biogeochemistry, particularly when seeking to understand the recovery from environmental disturbances such as acid rain and forest clear-cutting. The earliest study to use isotopes as an indicator of atmospheric inputs to soils was by Dymond et al. (1974), who used strontium isotope measurements of micas in Hawaiian soils to determine that a significant proportion of the potassium input to Hawaiian soils was from deposition of dust transported... 

Aberg. G. 1995. The use of natural strontium isotopes as tracers in environmental studies. Water, Air, and Soil Pollution 79 309-322. 

Analytical methods for measuring strontium in environmental samples are summarized in Table 7-2. The available methods can be divided into two groups chemical methods to determine the total mass of strontium in a sample, and radiological methods to determine amounts of radioactive isotopes. Environmental media that have been tested for strontium include air filters, swipes, biota, water, soil, and others. A full range of laboratory analysis methods has been used to quantify the total strontium or its radioactive isotopes. 

Uniquely in the history of our planet, all these factors — the carbon isotopes, sulphur isotopes, strontium isotopes and rare-earth elements — simultaneously point to a rise in free oxygen. Indeed, the wild swings in environmental conditions during the 160-million-year snowball Earth period may have pushed atmospheric oxygen up to nearly modern levels. At the same time, however, there was a re-emergence of banded-iron... 

In other cases where the radioactive material is released, it can he deposited upon environmental surfaces or skin. It could also he inhaled or ingested. The radioactive material on skin and environmental surfaces can usually he washed away, but the close contact with skin may give high doses of radiation to the skin from those isotopes that emit alpha and beta radiation. When radioactive material is inhaled or ingested, it continues to emit radiation and gives the internal areas of the body exposure. If the radioactive material has a chemical affinity for a particular organ of the body, it may accumulate there and selectively irradiate that particular organ. Examples are radioactive iodine (accumulates in tlie thyroid), radioactive cesium (accumulates in the liver), or radioactive strontium (accumulates in bone). 

Strontium isotopes vary in different rocks, depending on the original content of radioactive elements in those rocks. The isotope ratio Sr/ Sr is used in environmental studies to determine sources of particles and solutes in water and ice. Materials originating from one source should have the same Sr/ Sr ratio. Materials from different sources could have different isotope ratios. Observations for Sr found in micro-... 

Samples of calcite and the associated coal from several locations in sonthern Victoria Land were analyzed by Fanre and Botoman (1984) for the isotope compositions of carbon, oxygen, and strontium. The objectives of this study were to derive information about the environmental conditions in which the calcite cleats formed and to determine the provenance of the carbon and strontium they contain. The results are listed in Table 11.4. 

Radioactive isotopes of an element have similar environmental and toxicological behavior to the non-radioactive isotopes. If they are introduced into the body by inhalation ingestion, the chemical properties of the element will determine its ultimate destination in the body. For example, it is well known that strontium and radium are chemically similar to Ca and tend to deposit on bone surfaces and bone marrow with that element tritium ( H) becomes incorporated into water molecules and is distributed throughout the body. The main difference between radioactive and nonradioactive isotopes is that the radionuclides emit one or more types of radiation as they decay to more stable forms. The type and energy level of the emitted radiation is nuclide-specific. 

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