Content
Strontium
Strontium is a chemical element with the symbol Sr and atomic number 38. It is a soft, silvery-white metal that is highly reactive and prone to corrosion in the presence of water. Strontium is found in small amounts in the earth’s crust and is present in a number of minerals, including celestine (SrSO4) and strontianite (SrCO3).
In the environment, strontium occurs primarily in the form of the stable isotope strontium-88 (88Sr). This isotope is not radioactive and does not pose a significant health risk to humans. However, strontium can also occur in the form of other isotopes, including strontium-90 (90Sr), which is a radioactive isotope that can be harmful to human health.
Strontium can enter the water supply through a number of sources, including natural deposits of strontium-containing minerals and discharges from industrial operations. It can also be present in water as a result of contamination from radioactive isotopes, such as 90Sr, which can be released into the environment through nuclear weapons testing and other activities.
In drinking water, strontium can be harmful to human health at high levels. The primary concern with strontium in drinking water is the potential for the absorption of 90Sr, which is a radionuclide that can accumulate in the body and expose the individual to ionizing radiation. High levels of strontium in drinking water can also cause adverse effects on the cardiovascular system and increase the risk of bone cancer.
Definition and Structure
Strontium is a chemical element with the symbol Sr and atomic number 38. It is an alkaline earth metal, located in group 2 of the periodic table. Strontium is a soft, silvery metal that becomes yellowish when exposed to air due to the formation of an oxide layer. It has a relatively high reactivity, similar to other group 2 elements like calcium and barium. Strontium has four stable isotopes: Sr-84, Sr-86, Sr-87, and Sr-88, with Sr-88 being the most abundant. It typically forms divalent cations (Sr²⁺) and compounds that are often colorless.
Historical Background
Strontium was discovered in 1790 by Adair Crawford, who identified it in the mineral strontianite (strontium carbonate) from the village of Strontian in Scotland. The element was named after this village. Crawford’s discovery was later confirmed by other chemists, including Thomas Charles Hope, who demonstrated that strontium was distinct from barium and other known elements. In 1808, Sir Humphry Davy isolated strontium by electrolysis of a mixture of strontium chloride and mercuric oxide. Since then, strontium and its compounds have found various applications in science and industry.
Chemical Properties
Strontium is chemically similar to calcium and barium, with which it shares many properties. It reacts readily with water to form strontium hydroxide and hydrogen gas. When exposed to air, strontium forms a thin layer of oxide, which protects the metal from further oxidation. Strontium compounds are generally soluble in water, with strontium chloride, strontium nitrate, and strontium hydroxide being the most common. Strontium salts impart a crimson color to flames, a property exploited in fireworks and flares. In nature, strontium often occurs in the minerals celestite (strontium sulfate) and strontianite.
Synthesis and Production
Strontium is typically produced by reducing strontium oxide with aluminum in a high-temperature process known as the aluminothermic reaction. This method yields metallic strontium and aluminum oxide as by-products. Another production method involves the electrolysis of molten strontium chloride. Strontium compounds, particularly strontium carbonate and strontium nitrate, are obtained from natural mineral sources like celestite and strontianite. These minerals are mined, crushed, and subjected to various chemical processes to extract and purify the desired strontium compounds.
Applications
Strontium has a range of applications across different industries. One of its most notable uses is in the production of fireworks and flares, where strontium salts produce a bright red flame. Strontium compounds are also used in glass manufacturing, particularly for cathode ray tubes (CRTs) in older television sets and computer monitors. Strontium titanate is used in optical materials and as a diamond simulant due to its high refractive index. Additionally, strontium ferrite is used in permanent magnets, and strontium chloride is utilized in toothpaste for sensitive teeth.
Agricultural Uses
In agriculture, strontium compounds have limited but specific uses. Strontium nitrate is sometimes employed as a source of nitrogen in fertilizers. Strontium can also play a role in enhancing plant growth and improving the quality of crops. Research has shown that strontium can positively affect the uptake of calcium in plants, promoting stronger cell walls and overall plant health. However, excessive strontium levels can be detrimental, so its use in agriculture is carefully monitored.
Non-Agricultural Uses
Beyond agriculture, strontium is used in several non-agricultural fields. Strontium-90, a radioactive isotope of strontium, is used in medical and industrial applications. In medicine, it is used for radiotherapy in treating bone cancer, as it preferentially targets bone tissues. Strontium isotopes are also used in research to trace geological processes and study ocean circulation patterns. Additionally, strontium is used in the production of ferrite magnets, which are employed in various electronic devices and motors.
Health Effects
Strontium plays a role in bone health, as it can mimic calcium due to its similar chemical properties. Strontium ranelate, a compound of strontium, is used in the treatment of osteoporosis to strengthen bones and reduce the risk of fractures. However, the impact of strontium on health is dose-dependent. At low levels, strontium is beneficial, but excessive intake, particularly of radioactive strontium isotopes, can be harmful. Strontium-90, for example, can replace calcium in bones, leading to radiation damage and increased cancer risk.
Human Health Effects
For human health, stable strontium at low concentrations is not considered harmful and can even be beneficial for bone health. Strontium ranelate has been used in Europe for the treatment of osteoporosis, improving bone density and reducing fracture rates. However, it is not approved in the United States due to concerns over cardiovascular risks. Strontium supplements should be used with caution and under medical supervision. The primary health concern with strontium is its radioactive isotope, strontium-90, which can cause serious health problems if ingested or inhaled due to its ability to replace calcium in bones and emit harmful beta radiation.
Environmental Impact
Strontium occurs naturally in the environment and is commonly found in soil and water. Natural levels of strontium are generally not harmful. However, anthropogenic activities, such as nuclear testing and accidents, can release radioactive strontium-90 into the environment, posing significant health risks to humans and wildlife. Strontium-90 has a half-life of about 29 years and can persist in the environment, contaminating soil and water sources. Efforts to monitor and mitigate strontium-90 contamination are crucial for protecting environmental and public health.
Regulation and Guidelines
Regulations concerning strontium focus on both its beneficial uses and potential hazards. Health agencies provide guidelines for safe strontium levels in drinking water and food to protect public health. The World Health Organization (WHO) and Environmental Protection Agency (EPA) have set limits on strontium-90 concentrations due to its radioactive nature. In the medical field, the use of strontium-containing treatments is regulated to ensure safety and efficacy. Industrial and agricultural use of strontium compounds is also monitored to prevent excessive environmental contamination.
Controversies and Issues
Controversies surrounding strontium often involve its radioactive isotope, strontium-90. The release of strontium-90 during nuclear testing and accidents, such as the Chernobyl disaster, has raised significant health and environmental concerns. The long-term persistence of strontium-90 in the environment and its accumulation in the food chain remain contentious issues. Additionally, the use of strontium ranelate for osteoporosis treatment has been debated due to potential cardiovascular risks, leading to its restricted use in some countries.
Treatment Methods
Treatment methods for strontium exposure depend on the type and level of exposure. For stable strontium, reducing dietary intake through water and food is generally sufficient. In cases of exposure to radioactive strontium-90, chelation therapy may be used to enhance excretion from the body. Calcium supplements can also help reduce strontium absorption by competing for the same biological pathways. Environmental cleanup of strontium-90 contamination involves removing contaminated soil and water treatment to reduce strontium levels.
Monitoring and Testing
Monitoring and testing for strontium involve various techniques to ensure safety and compliance with regulations. Environmental monitoring includes testing soil, water, and air for strontium levels, particularly in areas near nuclear facilities or where strontium-containing products are used. Biological monitoring involves measuring strontium levels in human tissues and fluids to assess exposure and health risks. Analytical methods such as atomic absorption spectroscopy (AAS) and inductively coupled plasma mass spectrometry (ICP-MS) are commonly used to detect and quantify strontium in environmental and biological samples.
References
- U.S. Environmental Protection Agency. (n.d.). Strontium in drinking water. Retrieved from https://www.epa.gov/
- World Health Organization. (2004). Strontium. Retrieved from https://www.who.int/
- National Institutes of Health. (n.d.). Strontium. Retrieved from https://www.nlm.nih.gov/
- ATSDR. (2017). Strontium. Retrieved from https://www.atsdr.cdc.gov/
- U.S. Geological Survey. (n.d.). Strontium. Retrieved from https://www.usgs.gov/
- European Chemicals Agency. (n.d.). Strontium. Retrieved from https://echa.europa.eu/
- Agency for Toxic Substances and Disease Registry. (2012). Toxicological profile for strontium. Retrieved from https://www.atsdr.cdc.gov/
Strontium
( Strontium, 38Sr )
| Parameter | Details |
|---|---|
| Source | Natural deposits, industrial processes, fallout from nuclear tests |
| MCL | No specific MCL; US EPA lifetime health advisory level at 4 mg/L |
| Health Effects | Bone growth interference, increased risk of bone cancer |
| Detection | ICP-MS, atomic absorption spectroscopy |
| Treatment | Ion exchange, reverse osmosis, lime softening |
| Regulations | US EPA health advisory, WHO guidelines |
| Monitoring | Regular testing in areas with known deposits or contamination |
| Environmental Impact | Can affect soil and water quality, bioaccumulation in plants |
| Prevention | Proper waste management, minimize industrial discharges |
| Case Studies | Contamination near industrial sites and fallout areas |
| Research | Health impacts, improved detection and treatment methods |
Other Chemicals in Water
Strontium In Drinking Water
| Property | Value |
|---|---|
| Preferred IUPAC Name | Strontium |
| Other Names | None |
| CAS Number | 7440-24-6 |
| Chemical Formula | Sr |
| Molar Mass | 87.62 g/mol |
| Appearance | Soft, silvery metal |
| Melting Point | 777 °C (1431 °F) |
| Boiling Point | 1,382 °C (2,520 °F) |
| Solubility in Water | Insoluble (as elemental strontium) |
Videos
