In 1787, near the Scottish settlement of Strontian, in the lead mine, an unknown mineral was found until that time. In honor of the village, it was named strontianite. And the scientists gave the name to the chemical element strontium in honor of this mineral. What are its properties, how can this substance be useful or dangerous?
The first studies of strontium
After the discovery of strontianite, scientists attributed this mineral to different categories. Some believed that it belongs to fluorites, others - to viteritis. However, a little later clarity on this substance was introduced by the Scottish chemist T. Hope. Then it was not yet known that the test substance may have a half-life. Strontium was also the object of study of the chemist A. Lavoisier, as well as Humphrey Davy. A significant contribution to the discovery of this substance was also made by the Russian scientist Toviy Lovits. He, regardless of Western colleagues, discovered the presence of this metal in heavy spar.
A bit of theory. What is the half-life?
Everyone knows that today it is customary to call a radionuclide radioactive isotopes. What is half-life? Radionuclides differ from other substances in that their nuclei are unstable. Over time, they decay - a process of radioactive decay occurs. During this process, the nuclei turn into other isotopes, and in this case the emission of radioactive rays occurs. Different radionuclides have different levels of instability. There are short-lived and long-lived isotopes. Short-living decay very quickly: it takes seconds, days or months. For long-lived, hundreds, thousands, and sometimes billions of years are needed. In whatever quantity the isotope is taken, in order for half of its substance to decay, a certain period of time is always required - it is called the half-life.
What is the half-life of strontium-90?
As you know, radionuclides and isotopes are very dangerous to health substances. As for strontium, its stable isotopes practically do not pose a danger to humans. But radioactive isotopes are capable of destroying all living things. The reason one of the dangerous forms of strontium - strontium-90 - is dangerous is its half-life. Strontium-90 decays in 29 years, and this process is always accompanied by the release of a large amount of radiation. This element has the ability to quickly incorporate into the systems of living organisms and metabolize.
Strontium properties
In air, strontium reacts very quickly with water, becoming covered with a yellow oxide film. In free form, this element does not occur in nature. Its largest deposits are located in Russia, Arizona, California (USA). Strontium is a very soft metal - it is easy to cut with a simple knife. But its melting point is 768 ° C. Alloys containing strontium are used in pyrotechnics. And also this element is used to reduce uranium.
The penetration of strontium into living organisms
In its chemical properties, strontium is very similar to ordinary calcium - this element is practically its analogue. Strontium-90 is deposited very quickly in bone tissues, teeth, and also in fluids. When this element decays, the daughter yttrium-90 isotope also forms, which has a very short half-life. According to this parameter, strontium cannot even be compared with yttrium-90, which decays in only 64 hours.
Yttrium-90 is capable of emitting beta particles. It also very quickly affects bone tissue and especially sensitive bone marrow. Under the influence of powerful radiation, serious physiological changes occur in any living organism. The cellular composition is changing, the cell structure is also seriously disrupted, which leads to a change in metabolism. Therefore, the question of what half-life of strontium-90 is not at all idle. Ultimately, this element leads to cancer of the blood (leukemia) and bone. And he is also able to exert a powerful influence on DNA structure and genetics.
Speed of propagation in nature
Infection with strontium-90 occurs in a short time, since it has a very short half-life. Strontium formed after man-made disasters is transmitted along food biological chains, since it infects the earth and water. The isotope also easily penetrates the respiratory tract of animals and people. From the earth, strontium-90 quickly enters the body of animals, plants, and then into the body of people who take infected products. In addition, the isotope is able not only to infect a specific organism, but also transmit deformities to its descendants. Strontium-90 is also transmitted from mother's milk to the baby.
This isotope is actively involved in the metabolism of plants. In them, the substance enters from the soil through the roots. A very large amount of strontium is accumulated by such plant species as legumes, root crops and tubers. In the human body, strontium accumulates mainly in the skeleton. With age, the amount of deposited strontium decreases. In men, the isotope accumulates more than in women.
The most dangerous isotopes
Along with cesium-137, strontium-90 is one of the most dangerous and powerful radioactive contaminants with a fast half-life. Strontium-90 very often gets into the environment as a result of accidents at nuclear power plants, as well as nuclear tests. The situation is complicated by the fact that the presence of this isotope is very difficult to determine even in soil samples. Unlike cesium, whose gamma radiation is very easy to detect, it takes at least a week to determine the strontium-90 content in the soil.
During such a study, scientists burn a sample of soil or agricultural products in a special way, and only after that we can talk about whether there is strontium in this sample. This method is absolutely not suitable when it is necessary to identify the amount of isotope absorbed by the human body. For such a diagnosis, Belarusian scientists have invented a special helmet that detects beta radiation.
Related Strontium-90 Element
The closest in their properties in this respect are the metals cesium-137 and strontium-90. The half-life of 30 years has cesium-137. In radiation disasters, it is these two elements that create the greatest number of problems. It is believed that gamma-active cesium is more to blame for the monstrous consequences of the Chernobyl accident than strontium. Given the half-lives of these substances, we can say that at least six hundred years must pass before these isotopes remain in the Chernobyl zone.
Features of the half-life of isotopes
For each isotope substance, the half-life is strictly defined. Strontium-90 has a period of 28 years. However, this does not mean that all its atoms will disappear after 56 years. Also, the initial amount of the isotope does not play a role. During decay, some of the strontium can change, turning into lighter elements. If the half-life of radioactive strontium is 28 years, then this means the following.
After this period of time, half of the initial amount of the isotope will remain. After 28 years, a quarter and so on. It turns out that strontium can pollute the environment for decades. Some scientists round this number, indicating that the half-life of strontium is 29 years. After this period of time, half of the substance remains, but this is enough for strontium to spread far beyond the accident.