The main sources of terrestrial natural radiation are primarily attributed to three components: cosmic radiation, terrestrial radionuclides, and external terrestrial radiation. Here's a brief explanation of each:
Cosmic Radiation: Cosmic radiation originates from outer space, primarily from the Sun and other celestial bodies. It consists of high-energy particles, such as protons, electrons, and alpha particles, that continuously bombard the Earth's atmosphere. Some of these particles reach the Earth's surface, contributing to natural radiation exposure.
Terrestrial Radionuclides: Naturally occurring radioactive elements are present in the Earth's crust, and their decay processes release radiation. The main contributors are uranium-238, thorium-232, and potassium-40. These radionuclides are present in varying concentrations in rocks, soil, and building materials. Radon, a radioactive gas formed during the decay of uranium-238, is also a significant source of terrestrial radiation.
External Terrestrial Radiation: External terrestrial radiation refers to the radiation emitted from radioactive materials present on or near the Earth's surface. This can include radioactive minerals, such as uranium and thorium ores, as well as radioactive isotopes in water bodies, such as rivers and lakes.
It's worth noting that the levels of natural radiation can vary depending on geographical location and geological characteristics. Additionally, human activities, such as mining and the use of certain building materials, can influence the levels of terrestrial radiation in specific areas. However, overall, these three sources—cosmic radiation, terrestrial radionuclides, and external terrestrial radiation—contribute to the natural background radiation that we are exposed to on Earth.