Strontium release

Strontium released into the atmosphere from natural and anthropogenetic activities is transported and redeposited on the earth by dry or wet deposition. Dry deposition results from gravitational settling, impact, and sorption on surfaces (NCRP 1984). Experimental data on dry deposition of strontium, present in the ambient atmosphere, is limited. Rain, sleet, snow, or other forms of moisture can wash airborne particles containing strontium from the atmosphere by the process of wet deposition. Wet deposition depends on conditions such as particle solubility, air concentration, rain drop size distribution, and rain fall rate (NCRP 1984). Hirose et al. (1993) examined the mechanism of aerial deposition of 90Sr derived from the Chernobyl accident, and found that 96% of atmospheric 90Sr returned to earth as wet deposition. 

Holmuhamedov EL, Teplova VV, Chukhlova EA, et al. 1995. Strontium excitability of the inner mitochondrial membrane Regenerative strontium-induced strontium release. Biochem Mol Biol hit 36(l) 39-49. 

The direct Sr-90 release is negligibly small, as shown in Table 4.2-20. The dominant contribution to the strontium release is from the release and subsequent decay of its Kr-90 precursor, which accounts for 88 percent of total release the remaining contribution is from heavy-metal manufacturing contamination of the fuel element coolant hole surfaces (a minimum fractional release of 5 x 10 is assumed for all fission products to account for possible heavy metal contamination on the fuel element coolant hole surfaces). The predicted 40-year Sr-90 plateout inventory of 0.20 Ci is below the "Maximum Expected" criterion of 0.34 Ci. 

Coatings, Paints, and Pigments. Various slightly soluble molybdates, such as those of zinc, calcium, and strontium, provide long-term corrosion control as undercoatings on ferrous metals (90—92). The mechanism of action presumably involves the slow release of molybdate ion, which forms an insoluble ferric molybdate protective layer. This layer is insoluble in neutral or basic solution. A primary impetus for the use of molybdenum, generally in place of chromium, is the lower toxicity of the molybdenum compound. 

A primer On metal, the purposes of a primer are to enhance corrosion protection and to give excellent adhesion. The primer will contain anticorrosive pigments, such as strontium chromate or zinc phosphate, which will slowly release ions that can repair damage or faults in the underlying conversion coating. 

Strontium metal is responsible for the red color in fireworks. Fireworks manufacturers use strontium carbonate, which can be produced by combining strontium metal, graphite (C), and oxygen gas. The formation of one mole of SrC03 releases 1220 X 103 k) of energy. 

The determination of magnesium in potable water is very straightforward very few interferences are encountered when using an acetylene-air flame. The determination of calcium is however more complicated many chemical interferences are encountered in the acetylene-air flame and the use of releasing agents such as strontium chloride, lanthanum chloride, or EDTA is necessary. Using the hotter acetylene-nitrous oxide flame the only significant interference arises from the ionisation of calcium, and under these conditions an ionisation buffer such as potassium chloride is added to the test solutions. 

Preparation of the standard solutions. For procedure (i) it is necessary to incorporate a releasing agent in the standard solutions. Three different releasing agents may be used for calcium, (a) lanthanum chloride, (b) strontium chloride and (c) EDTA of these (a) is the preferred reagent, but (b) or (c) make satisfactory alternatives. 

Half-lives span a very wide range (Table 17.5). Consider strontium-90, for which the half-life is 28 a. This nuclide is present in nuclear fallout, the fine dust that settles from clouds of airborne particles after the explosion of a nuclear bomb, and may also be present in the accidental release of radioactive materials into the air. Because it is chemically very similar to calcium, strontium may accompany that element through the environment and become incorporated into bones once there, it continues to emit radiation for many years. About 10 half-lives (for strontium-90, 280 a) must pass before the activity of a sample has fallen to 1/1000 of its initial value. Iodine-131, which was released in the accidental fire at the Chernobyl nuclear power plant, has a half-life of only 8.05 d, but it accumulates in the thyroid gland. Several cases of thyroid cancer have been linked to iodine-131 exposure from the accident. Plutonium-239 has a half-life of 24 ka (24000 years). Consequently, very long term storage facilities are required for plutonium waste, and land contaminated with plutonium cannot be inhabited again for thousands of years without expensive remediation efforts. 

As with calcium and strontium oxides, barium oxide reacts very exothermically with water, forming hydrogen.The heat which is released is such that it can, like... 

Sulfate scaling poses a special problem in oil fields of the North Sea (e.g., Todd and Yuan, 1990, 1992 Yuan et al., 1994), where formation fluids are notably rich in barium and strontium. The scale can reduce permeability in the formation, clog the wellbore and production tubing, and cause safety equipment (such as pressure release valves) to malfunction. To try to prevent scale from forming, reservoir engineers use chemical inhibitors such as phosphonate (a family of organic phosphorus compounds) in squeeze treatments, as described in the introduction to this chapter. 

Somlyo AV, Somlyo AP 1971 Strontium accumulation by sarcoplasmic reticulum and mitochondria in vascular smooth muscle. Science 174 955-958 Somlyo AV, Bond M, Somlyo AP, Scarpa A 1985 Inositol-trisphosphate induced calcium release and contraction in vascular smooth muscle. Proc Natl Acad Sci 82 5231-5235 Somlyo AV, Horiuti K, Trentham DR, Kitazawa T, Somlyo AP 1992 Kinetics of Ca2+ release and contraction induced by photolysis of caged D-myo-inositol 1,4,5-trisphosphate in smooth muscle the effects of heparin, procaine, and adenine nucleotides. J Biol Chem 267 22316-22322... 

Nishita, H., Steen, A.J., and Larson, K.H., 1958, Release of strontium-90 and cesium-137 from vina loam upon prolonged cropping. Soil Sci. 86 195-201. 

Certain chemicals can be stored in the body, as depicted in Figure 2.1. A major site of storage is bone, which can bind metals such as lead and strontium and non-metallic inorganic elements such as fluoride. While bound in this form the chemicals are relatively inert, but under certain conditions, they can be slowly released from storage and re-enter the bloodstream where they are more available to cause biological effects. 

When strontium metal is exposed to water, it releases hydrogen, as do the other earth metals (Sr + 2HjO —> Sr(OH)2 + H T). Strontium can ignite when heated above its melting point. When in a fine powder form, it will burn spontaneously in air. It must be stored in an inert atmosphere or in naphtha. Several of its salts burn with a bright red flame, making it useful in signal flares and fireworks. 

Strontium metal is not found in its elemental state in nature. Its salts and oxide compounds constitute only 0.025% of the Earths crust. Strontium is found in Mexico and Spain in the mineral ores of strontianite (SrCO ) and celestite (SrSO ). As these ores are treated with hydrochloric acid (HCl), they produce strontium chloride (SrCy that is then used, along with potassium chloride (KCl), to form a eutectic mixture to reduce the melting point of the SrCl, as a molten electrolyte in a graphite dish-shaped electrolysis apparatus. This process produces Sr cations collected at the cathode, where they acquire electrons to form strontium metal. At the same time, Cl anions give up electrons at the anode and are released as chlorine gas Cl T. 

Both the metal and some compounds will react with water to produce strontium hydroxide [Sr(OH)j] and release hydrogen gas. The heat from the exothermic reaction may cause the hydrogen to either burn or explode [Sr + —> SrfOH) + H T]. 

Bone. Although bone is a relatively inert tissue, it can accumulate such substances as tetracyclines, lead, strontium, and the antitumor agent cisplatin. These substances may accumulate in bone by absorption onto the bone crystal surface and eventually be incorporated into the crystal lattice. Tetracycline deposition during odontogenesis may lead to a permanent yellow-brown discoloration of teeth, dysplasia, and poor bone development. Lead can substitute for calcium in the bone crystal lattice, resulting in bone brittleness. Bone may become a reservoir for the slow release of toxic substances, such as lead and cisplatin. 

The availability of a chemical to the cells is affected by where it is stored. First, lipophilic chemicals tend to get absorbed by and retained in fat cells, from which they are released slowly back into the bloodstream. Second, some chemicals are strongly bound to plasma proteins and are released to the cells more slowly over time. For example, acetaminophen (Tylenol ) does not bind strongly to plasma proteins, while diazepam (Valium ) does. Thus, diazepam will persist in the body for longer periods of time than will acetaminophen. Finally, some elements, such as fluorine, lead, and strontium, are bound up in bone for long periods of time. As bone slowly renews itself or is broken down under special circumstances such as pregnancy, the chemicals are released and can affect the mother and fetus. 

Strontium-90 behaves much hke calcium in the biological environment. In birds, °Sr is expected to occur in bone and in the calcium-rich eggshell. In one case, a positive relation was demonstrated between reactor releases of °Sr to the Columbia River and °Sr concentrations in reed canary grass Phalaris arundinacea) and eggshells of the Canada goose (Branta canadensis moffitti) (Rickard and Price 1990). 

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