Strontium 90: half-life. Strontium - radionuclide

In 1787, near the Scottish settlement of Strontian, in a lead mining mine, an unknown mineral had been found up to that time. In honor of the village, it was called strontianite. And the name of the chemical element of strontium was given by scientists in honor of this mineral. What are its properties, than this substance can be useful or dangerous?

The first studies of strontium

After the discovery of strontianite, scientists attributed this mineral to different categories. Some thought that it belonged to fluorites, others thought it to the Witherites. However, a little later clarity about this substance was introduced by the Scottish chemist T. Hop. At that time it was not yet known that the substance under study could have a half-life. Strontius was also the object of study of chemist A. Lavoisier, as well as Humphry Davy. A significant contribution to the discovery of this substance was also made by the Russian scientist Toby Lovitz. He, regardless of his Western colleagues, discovered the presence of this metal in heavy spar.

A bit of theory. What is the half-life?

Everyone knows that today a radionuclide is commonly called radioactive isotopes. What is the half-life? Radionuclides differ from other substances in that their nuclei are unstable. Over time, they decay - there is a process of radioactive decay. During this process, the nuclei are converted to other isotopes, and the emission of radioactive rays occurs. Different radionuclides have a different level of instability. There are short-lived and long-lived isotopes. The short-lived break up very quickly: it takes seconds, days or months. Long-living people need hundreds, thousands, and sometimes billions of years. No matter how many isotopes are taken, in order to break up half of its substance, it always takes a certain period of time - it is called the half-life.

What is the half-life of strontium-90?

As is known, radionuclides and isotopes are very dangerous substances for health. As for strontium, its stable isotopes are practically no danger to humans. But radioactive isotopes are capable of destroying all life. The reason why 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 emission of a large amount of radiation. This element has the ability to quickly join the systems of living organisms and be metabolized.

Properties of strontium

In air, strontium very quickly reacts with water, covered with a yellow oxide film. In its 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, which include strontium, are used in pyrotechnics. And also this element is used to restore uranium.

The penetration of strontium into living organisms

According to its chemical properties, strontium is very similar to normal calcium - this element is practically its analog. Strontium-90 is very quickly deposited in bone tissues, teeth, and also in liquids. Upon decay of this element, a daughter isotope yttrium-90 is also formed, which has a very short half-life. Strontium in this parameter can not even be compared with yttrium-90, which decays in just 64 hours.

Yttrium-90 is capable of emitting beta particles. He also very quickly affects bone tissue and bone marrow, which is especially sensitive to it. Under the influence of powerful irradiation in any living organism, serious physiological changes occur. The cellular composition changes, the cell structure is also seriously disturbed, which leads to a change in metabolism. Therefore, the question of which half-life of strontium-90 is not idle at all. Ultimately, this element leads to cancer of the blood (leukemia) and bones. And it is also able to exert a powerful influence on the structure of DNA and genetics.

Speed of spread in nature

Infection with strontium-90 occurs in a short time, since it has a very short half-life. Strontium, formed after anthropogenic disasters, is transmitted through food biological circuits, as it infects land and water. The isotope also easily penetrates the respiratory tract of animals and humans. From the ground, strontium-90 quickly enters the body of animals, plants, and then into the body of people who take contaminated foods. In addition, the isotope is able not only to hit a particular organism, but also transmit deformities to its offspring. Strontium-90 is also transmitted with mother's milk to a child.

This isotope takes an active part in the metabolism of plants. In them, the substance comes from the soil through the roots. A very large amount of strontium accumulates such plant species as legumes, root crops and tubers. In the human body, strontium accumulates mainly in the skeleton. With age, the amount of deferred 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 that have a fast half-life. Strontium-90 very often falls 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, the gamma radiation of which is very easy to detect, at least a week is required to determine the content of strontium-90 in the soil.

During such a study, scientists test the soil or agricultural products in a special way, and only then can one say whether there is strontium in this sample. This method is absolutely not suitable when it is necessary to reveal the amount of an isotope absorbed by a human body. For such a diagnosis Belarusian scientists invented a special helmet that records beta radiation.

A 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. With radiation accidents, these two elements create the greatest number of problems. It is believed that in the monstrous consequences of the Chernobyl accident, gamma-active cesium is more guilty than strontium. Considering the half-lives of these substances, we can say that it must take at least six hundred years before these isotopes do not remain in the Chernobyl zone.

Features of the isotope half-life

For each isotope substance, the half-life period is strictly defined. Strontium-90 has a period of 28 years. However, this does not mean that all of its atoms will disappear after 56 years. Also, the initial amount of the isotope does not play a role. During the decay, some of the strontium can change, turning into lighter elements. If the half-life of radioactive strontium is 28 years, this means the following.

After this period of time, half of the original quantity of the isotope will remain. Even after the lapse of 28 years - a quarter and so on. It turns out that strontium can pollute the environment for dozens of years. Some scientists round this number, indicating that the half-life of strontium is 29 years. Through this period of time, half of the substance remains, but this is enough to allow strontium to spread far beyond the accident.