Radionuclides in Environment

 

Radioactive elements are part of our ecosystem, part of the air we breathe, the water we drink and the food we eat.

·    Radionuclides can occur naturally, or can be man-made.

·   Over half of the average annual radiation exposure of people comes from natural sources.

About Radionuclides in Environment

An ecosystem is a place with a one-of-a-kind combination of air, water and land. An ecosystem has habitats that support plant and animal life. Ecosystem science focuses on all parts of the system, including the interaction among the water, air, land, plants, humans and other animals. Ecosystem science can tell us how minerals and other chemicals in nature (including radionuclides) move through Earth’s different natural systems.

Radionuclides enter an ecosystem in three ways:

·         As minerals present in Earth’s original crust.

·         As radionuclides created by cosmic rays hitting atoms in Earth’s atmosphere.

·         From human activity.

 

Radionuclides in Earth‘s Crust

Some radionuclides have been present in rocks since the formation of Earth. Others are their decay products. Examples of these natural radionuclides include potassium-40, rubidium-87, uranium and thorium and decay products, such as radium and radon.

These radionuclides end up naturally in soil, water and air. Rocks containing them are broken down into soil by the weather, bacteria and fungi. When radionuclides are in soil particles, they can be blown around by wind. Some will dissolve in water and end up in surface or ground water. Some radionuclides dissolve more easily than others. Also, the makeup of the water affects how much of the radionuclide will dissolve.

More half of the average annual radiation exposure of people comes from natural sources. The natural radionuclide, radon, is the single biggest natural source of exposure. It comes from the breakdown of radium. Breathing indoor air containing radon is the most common exposure route.

Radon is one radionuclide that dissolves easily in water. Radon concentration in water is usually low enough that they are not a serious health threat.

Radiation from Space

Cosmic rays come from stars, our sun, other stars and exploding stars. The rays continuously strike atoms in Earth’s atmosphere. The atmosphere stops most of the cosmic rays, however, the collisions leave some atoms unstable (radioactive). These radioactive atoms are called cosmogenic radionuclides. They are rare, but some of them do reach Earth’s surface and settle on the soil and water.

Radionuclides from Human Uses of Radioactive Material

Nature is the major source or of radionuclides in an ecosystem. Much smaller amounts of radionuclides come from sources developed by humans. Examples include uranium mines, nuclear power plants and research facilities that use radionuclides. However, for most people the annual exposure from these sources is very low. Only in certain areas where there are open uranium and other mineral mines and mining wastes present is there a serious health hazard.

·    Nuclear Weapons Testing:  Nuclear weapons tests released large amounts of radionuclides that spread and remained in ecosystems until the radionuclides decayed away. Today, nuclear events include nuclear accidents and potentially terrorist acts.

 

·  Nuclear Facility Releases: The small amounts of airborne radionuclides released from facilities that handle and process radioactive materials can get into the soil, water or air. The facilities operating permits allow only very small releases because they result in very small exposures.

 

·      Radioactive Waste: Improper disposal of radioactive waste is another way radionuclides can enter an ecosystem. For example, water seeping thorough mining wastes can dissolve some radionuclides and carry them into the water system. Public water systems are monitored carefully to make sure the drinking water is safe. This kind of waste accounts for less than a tenth of one percent of the average annual radiation exposure.