Strontium

Notable characteristics

Due to its extreme reactivity to air, this element occurs naturally only in compounds with other elements, as in the minerals celestite.

Strontium is a bright silvery metal that is softer than isotopes.

Applications

As a pure metal strontium is being used in strontium 90%-aluminium 10% X-ray emission.

Other uses:

• calcium and is preferentially incorporated into bone at sites of increased osteogenesis. This localization focuses the radiation exposure on the cancerous lesion.
• ²³⁸Pu, another RTG fuel. The main advantage of ⁹⁰Sr is that it is cheaper than ²³⁸Pu and is found in nuclear waste.
• ⁹⁰Sr is also used in cancer therapy. Its beta emission and long half-life is ideal for superficial radiotherapy.
• Strontium is one of the constituents of AJ62 alloy, a durable magnesium alloy used in car and motorcycle engines by BMW.

⁸⁷Sr/⁸⁶Sr ratios are commonly used to determine the likely provenance areas of sediment in natural systems, especially in marine and fluvial environments. Dasch (1969) showed that surface sediments of the deep Atlantic displayed ⁸⁷Sr/⁸⁶Sr ratios that could be regarded as bulk averages of the ⁸⁷Sr/⁸⁶Sr ratios of geological terranes from adjacent landmasses. One good example of a fluvial system to which Sr isotope ratio studies have been frequently employed is the River Nile (Krom et al, 1999; Krom et al, 2002; Talbot et al. 2000). Due to the vastly differing ages of the rocks that constitute the majority of the Blue and White Nile catchment areas the changing provenance of sediment reaching the River Nile delta, and East Mediterranean Sea beyond, can be discerned through Sr isotopic studies. This information is useful as it can elicit information regarding climate change over geologic time scales.

More recently, ⁸⁷Sr/⁸⁶Sr ratios have also been used to determine the source of ancient archaeological materials such as timbers and corn in Chaco Canyon, New Mexico (English et al, 2001, Benson et al, 2003). ⁸⁷Sr/⁸⁶Sr ratios in teeth may also be used to track animal migrations (Porder et al., 2003) or in criminal forensics.

Compounds

• Ferrite magnets and refining zinc.
• diamond simulant. However, it is very soft and easily scratches so it is rarely used.
• Strontium carbonate, Strontium nitrate, and Strontium sulfate are commonly used in fireworks for red color.
• phosphorescence.
• Strontium chloride is sometimes used in toothpastes for sensitive teeth. One popular brand includes 10% total strontium chloride hexahydrate by weight.
• Strontium oxide is sometimes used to improve the quality of some pottery glazes.
• Strontium is also commonly used in aerosol paint, such as the Spanish Montana (Montana Hardcore). This is one of the most likely sources of exposure to the public.
• Strontium ranelate is used in the treatment of osteoporosis

History

The electrolysis.

Strontium was among the radioactive materials released by the 1957 Windscale fire.

Occurrence

  In 2005, China was the top producer of strontium with almost two-thirds world share followed by Spain and Mexico, reports the British Geological Survey.

Strontium commonly occurs in nature, the 15th most abundant element on earth, averaging 0.034% of all igneous rock and is found chiefly as the form of the potassium chloride:

Sr²⁺ + 2 e^- → Sr

2 Cl^- → Cl_{2 (g)} + 2 e^-

Alternatively it is made by reducing strontium transition points at 235 and 540 °C. The largest commercially exploited deposits are found in England.

See also strontium minerals.

Isotopes

Main article: Isotopes of strontium

The isotopes: ⁸⁴Sr (0.56%), ⁸⁶Sr (9.86%), ⁸⁷Sr (7.0%) and ⁸⁸Sr (82.58%). Only ⁸⁷Sr is minerals.

Sixteen unstable isotopes are known to exist. Of greatest importance is ⁹⁰Sr with a beta emitters known, and is used in SNAP (Systems for Nuclear Auxiliary Power) devices. These devices hold promise for use in spacecraft, remote weather stations, navigational buoys, etc, where a lightweight, long-lived, nuclear-electric power source is required. The 1986 Chernobyl nuclear accident contaminated a vast area with ⁹⁰Sr.

Precautions

In its pure form strontium is extremely reactive with air and spontaneously combusts. It is therefore considered to be a fire hazard.

Effect on the human body

The human body absorbs strontium as if it were strontium unit is used in measuring radioactivity from absorbed ⁹⁰Sr.

An innovative drug made by combining strontium with ranelic acid has aided in bone growth, boosted bone density and lessened vertebral, peripheral and hip fractures.^{[4] [5]} Women receiving the drug showed a 12.7% increase in bone density. Women receiving a placebo had a 1.6% decrease. Half the increase in bone density (measured by x-ray densitometry) is attributed to the higher atomic weight of Sr compared with calcium, whereas the other half a true increase in bone mass. It means that strontium ranelate creates new and strong bone. Strontium ranelate (marketed under the trade names Protelos, Osseor, Protos, Bivalos, Protaxos, Ossum) is registered for treatment of osteoporosis in many countries all over the world. Strontium ranelate has been shown to strengthen bones, according presentations given the IOF World Congress on Osteoporosis, in June of 2006. It also reduced bone resorbtion.

Strontium ranelate is registered as a prescription drug in Europe and many countries worldwide. It needs to be prescribed by a doctor, delivered by a pharmacist and requires a strict medical supervision. Currently, (early 2007) it is not available in Canada or the United States.

Several other salts of strontium such as strontium citrate or strontium carbonate are often presented as natural therapies and sold at a dose that is several hundred times higher than the usual strontium intake. Despite the lack of strontium deficit referenced in the medical literature and the lack of information about possible toxicity of strontium supplementation, such compounds can still be sold in the United States under the Dietary Supplements Health and Education Act of 1994.

However, their long-term safety and efficacy have never been evaluated on humans using large-scale medical trials. Such compounds should not be administered to humans before further studies are conducted.

Allegedly, an attempt was made in 1968 to poison Alexander Dubček with Sr-90, but it failed.

See also

• Strontium compounds

References

1. ^ Strontium: strontium(I) fluoride compound data. Bernath.UWaterloo.ca. Retrieved on 2007-12-10.
2. ^ http://www.qrg.northwestern.edu/projects/vss/docs/Power/3-what-are-the-fuels-for-rtgs.html
3. ^ Murray, W.H. (1977) The Companion Guide to the West Highlands of Scotland. London. Collins
4. ^ Meunier PJ, Roux C, Seeman E et al. (2004). "effects of strontium ranelate on the risk of vertebral fracture in women with postmenopausal osteoporosis.". New England Journal of Medicine 350: 459-468. PMID 14749454.
5. ^ Reginster JY, Seeman E, De Vernejoul MC et al. (2005). "Strontium ranelate reduces the risk of nonvertebral fractures in postmenopausal women with osteoporosis: treatment of peripheral osteoporosis (TROPOS) study". J Clin Metab. 90: 2816-2822. PMID 15728210.

• Los Alamos National Laboratory – Strontium. Retrieved on August 5, 2005.
• Dasch, J. (1969). Strontium isotopes in weathering profiles, deep-sea sediments, and sedimentary rocks. Geochimica et Cosmochimica Acta, Vol. 33, pp. 1521-1552.
• Krom et al. (1999). The characterisation of Saharan Dusts and Nile particulate matter in surface sediments from the Levantine basin using Sr isotopes. Marine Geology, Vol. 155, pp. 319-330.
• Krom et al. (2002). Nile River sediment fluctuations over the past 7000 yr and their key role in sapropel development. Geology, Vol. 30, pp. 71-74.
• Talbot et al., (2000). Strontium isotope evidence for late Pleistocene reestablishment of an integrated Nile drainage network. Geology, Vol. 28, pp. 343-346.
• Benson, L., Cordell, L., Vincent, K., Taylor, H., Stein, J., Farmer, G., and Kiyoto, F. (2003) Ancient maize from Chacoan great houses: where was it grown?: Proceedings of the National Academy of Sciences , v. 22, p. 13111-13115.
• English, N.B., Betancourt, J.L., Dean, J.S. and J. Quade (2001) Strontium Isotopes Reveal Distant Sources of Architectural Timber in Chaco Canyon, New Mexico. Proceedings of the National Academy of Sciences of the United States of America, Vol. 98, pp. 11891-11896
• Porder, S., Paytan, A., and E.A. Hadly (2003) Mapping the origin of faunal assemblages using strontium isotopes. Paleobiology, 29: 197 - 204.