Radioactive contamination of soils and its consequences

Active human activity is very commonadversely affects the surrounding world of animate and inanimate nature. The rapid development of industry, the intensive development of agriculture, the difficulties of recycling waste - all this seriously threatens the ecology of the planet. With the development of nuclear energy and the improvement of nuclear weapons, another problem arose-radioactive contamination of soils, reservoirs, and the atmosphere.

Identify the problem

Radioactive contamination of the soil is the excess of the concentration of radionuclides in it over the indices of the maximum permissible norm due to anthropogenic activity.

Contaminated areas are characterized bysignificant excess of external and internal radiation doses. To indicate the norm of ionizing cure, the International Radiation Protection Commission (ICRP) introduced an average annual dose of radiation, which for soil and rocks is 0.25-0.5 microsievert per year (mSv / g). This standard determines the amount of radiation safe for human health and many times below the value that can lead to the death of a living organism for a further 30 days.

Causes

How does the radioactive contamination of soils occur? Sources of pollution are two groups of radionuclides:

• technogenic;
• natural.

It is known that the soil contains naturalradionuclides. But their concentration is significantly increased due to the extraction, storage of natural raw materials, processing, fertilization, production, combustion of coal, use of ashes as fertilizing plants or for the production of building materials, etc.

Due to the rapid production andThe use of fertilizers every year increases the number of radioactively contaminated soils. For example, the issue of increasing the concentration in the soil of radionuclides due to the use of potassium and phosphorus fertilizers has not been adequately studied.

Artificial radionuclides massively fall into the components of the biosphere of the planet due to nuclear explosions.

Thus, the main causes of radioactive contamination of the soil cover are:

• intensive development of agricultural land;
• heavy industry;
• development of deposits of natural resources;
• radioactive waste disposal;
• radiation emissions of nuclear power plants;
• nuclear weapon test.

Radioactive contamination of soils: consequences of infection

There are many negative consequences of soil contamination:

• direct negative impact of radioactive substances on animals, vegetation and humans;
• significant limitation of the ability to usesoil resources for agricultural purposes. After all, all the products that are received from such a land plot have higher levels of concentration of radioactive substances due to contamination of open water bodies and groundwater, where harmful compounds are leached from the soil. Severe pollution can lead to the inability to use fresh water not only for drinking and cooking, but also for watering cattle or watering agricultural land.

Many scientists argue that the lesionsradiation substances of the environment lead to the complete death of biogeocenosis and populations. This occurs at a high level of contamination. Such areas are fixed mainly near the places where the radiation was released and, as a consequence, the radioactive contamination of the soil. Chernobyl is a zone of alienation after the Chernobyl disaster. Then hundreds of hectares received the strongest dose of radiation, as a result of which they were completely withdrawn from human life.

Deep processes

The soil absorbing complex sorts radioactive substances. In addition, he keeps them for a long time.

Radionuclides in soil are characterized by:

• properties of chemically active isotopes;
• properties and composition of the soil itself;
• properties of radionuclides in fallout;
• climatic indicators;
• features of the landscape.

Radionuclides on the soil surface come incomposition of aerosols, minerals, fuel particles, etc. The maximum part of their soluble fractions in the composition of global deposition is 30-90%. The highest in cesium and strontium. How will behave radionuclides in the future - no one knows. Dynamic equilibrium increases as the solubility of their deposition decreases. The introduction of soluble organic substances into the soil and the special acidification of the environment affect the increase in the migration of radionuclides, which is used to purify it.

The mobility of radiation contamination depends on:

• mineralogical composition;
• presence in the soil of geochemical barriers;
• granulometric composition;
• properties of humus;
• the reaction of the medium.

Horizontal redistribution of radionuclides

To predict the possible consequences of radioactive contamination of soil, it is very important to know the peculiarities of migration of radionuclides.

Redistribution of radionuclides in the soil occurs in a horizontal and vertical direction in a natural way and for reasons of anthropogenic activity.

Horizontal migration occurs due to:

• aeolian transfer (the name comes from the name of the wind god Eola);
• flood of flood waters, which is the reason for more intensive pollution of lowlands and wetlands;
• livelihoods of animals (earthworms, wild boars, moles and other "burrowing");
• traffic;
• preparation of green forage in contaminated meadows;
• forest fires, which are a very powerful factor in the transport of isotopes.

Minimum horizontal migration is observed inforest cenoses, and the maximum - in agrocenoses with light soils. Horizontal redistribution, on the one hand, reduces the level of soil contamination with radioactive nuclides, on the other, it expands the range of their distribution.

Vertical Migration

As for vertical redistribution,in all types of soil it occurs slowly. The linear speed of this process ranges from tenths to two centimeters per year. The soil in this case acts as a biogeochemical barrier. Studies conducted in the Chernobyl zone have shown that the main part of radionuclides remains within the upper soil layer (about 10 cm) for a long time. And in the forest part of this zone, radioactive substances accumulated in the litter (foliage, needles) and the lower soil layer (about 1-2 cm).

Vertical migration of radionuclides depends on such factors:

• volcanic eruptions;
• Rains, the transfer of moisture by runoff and evaporation;
• transfer by root systems of plants;
• human activity - plowing, irrigation.

The most polluted territories on the planet

On the planet there are hundreds of radioactivecontaminated areas. Serious danger is the territory of Henford in the state of Washington, USA. Here in the middle of the last century a giant complex was built, which was engaged in the world's first nuclear development. As a result of his activities, an area of ​​518 sq. M. km.

Soils in Somalia were used for illegaldisposal of nuclear waste. The Semipalatinsk test site in Kazakhstan, where nuclear tests were conducted, is one of the most radiation-dangerous territories in the world. In the city of Mailuu-Suu, Kyrgyzstan, uranium mining was established on an all-Union scale, which led to an extremely high concentration of radioactive isotopes in the area of ​​the mines.

The well-known Chernobyl zone is a dead zone,where radioactive contamination of soils has happened for many hundreds of kilometers. ChNPP is not the only nuclear power plant in the world where a nuclear catastrophe of a global scale has occurred. This happened in Fukushima, Japan. Here, the earthquake and tsunami in March 2011 caused an accident at the nuclear power plant, as a result of which a huge area was damaged.

Industrial complex "Mayak" in Russia in a secretcity ​​"Chelyabinsk-40" near the city of Kyshtym suffered from the accident in 1957. Its consequences were the radiation pollution of 25 thousand hectares of arable land. Such a catastrophic situation has developed around OAO Siberian Chemical Combine in the Tomsk region, Russia.

Features of the use of contaminated areas

In the soil, radionuclides witha long period of decay: promethium-147, cerium-144, cesium-137, ruthenium-106 and 103, strontium-90. The most dangerous for living organisms is strontium-90. Therefore, on fields contaminated by radiation, agrochemical, agrotechnical and other measures are carried out, which can reduce the transfer of hazardous compounds from soil to plants. For this purpose, the top layer of the soil is also cut off, followed by burial.

An effective measure is the planting of plantsSome varieties and species that are characterized by a minimum level of accumulation of radionuclides. Everyone knows that in animal husbandry for fattening, only clean feed should be used. Use also special additives of sorbents, which suppress the transfer of radioactive substances into the composition of milk.

Reclamation works are aimed at reducingradionuclide intake into plants. For this, sorbents are introduced into the soil, such as: vermiculite, zeolite, mineral and organic additives, lime. In agriculture, the reduction of accumulation in the plant of radionuclides occurs through agrotechnical methods. Carry out plantation plowing, with the rotation of the formation. This technique of soil cultivation leads to a deepening of radioactive contamination. Thanks to this, the accumulation of substances in plants decreases by a factor of 24. In agriculture, the structure of the crop rotation should be changed. It is better to start growing technical crops that are not used in food.

An alternative method of using contaminatedterritory is the cancellation of any specific impact. For example, you can create special reserves. With a pronounced radiation background, a forest is planted at the site of infection, mostly pine.

Security measures

Security measures in the territories where there is radiation contamination of the soil are directed to reduce the negative impact of radiation. The following actions are carried out:

• develop a strategy for the use of products and territories at the national or international level, depending on the extent of pollution and the potential risk of contamination of surrounding areas;
• meliorative, agrotechnical measures;
• chemical disinfection;
• use of sorbents;
• restriction of human activity;
• informing the population about possible danger;
• Restricting the export of any products from a hazardous area.

The period of validity of these restrictions depends on the firstturn from the density of pollution. In addition, pay attention to the exposure dose of radiation. This period can last from several weeks to many decades. Thus, environmentalists reduce radioactive contamination of soils and its consequences.