Rutherford (unit) unit for activity, the rutherford became obsolete, and it is no longer commonly used. The following table shows radiation quantities in SI and non-SI units: Rutherford (unit) The rutherford (symbol Rd) is a non-SI unit of radioactive decay. It is defined as the activity of a quantity of radioactive material in which one million nuclei decay per second. It is therefore equivalent to one megabecquerel, and one becquerel equals one microrutherford. One rutherford is equivalent to 2.703 × 10 curie. The unit was introduced in 1946. It was named after British/New Zealand physicist and Nobel laureate Lord Ernest Rutherford (Nobel
Environmental radioactivity Environmental radioactivity Environmental radioactivity is produced by radioactive materials in the human environment. While some radioisotopes, such as strontium-90 (Sr) and technetium-99 (Tc), are only found on Earth as a result of human activity, and some, like potassium-40 (K), are only present due to natural processes, a few isotopes, "e.g." tritium (H), result from both natural processes and human activities. The concentration and location of some natural isotopes, particularly uranium-238 (U), can be affected by human activity. Radioactivity is present everywhere, and has been since the formation of the earth. According to the IAEA, soil typically contains the following four