Plutonium in the environment

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Plutonium in the environment mostly comes from human activities that began in the mid-20th century. The first big producers were the Hanford site in Washington, USA, and the Mayak plant in Russia. For about four decades, these facilities released substantial amounts of radioactive material into the surrounding environment. In places, these releases were large enough to be compared with major nuclear accidents. Today, tiny traces of plutonium are still found in air, soil, water, and sediments, and some long-lived isotopes have been detected in nature, such as Pu-244 in very small amounts in lunar soil, meteorites, and the Oklo natural reactor.

Where plutonium in the environment comes from
- Nuclear weapons tests released about 3.5 tons of plutonium into the environment. Most of this exposure has caused only small doses to people.
- Plutonium from bomb fuel forms a form called PuO2 (plutonium oxide) that is not very soluble and tends to settle into soils and sediments.
- Some plutonium created by neutron capture during explosions can be more soluble and more easily transported as fallout.
- Reprocessing and uranium enrichment plants have released plutonium as well, especially Pu-238 and Pu-241 into the oceans.

Space power and safety
- Plutonium-238 is used in some space power sources (radioisotope thermoelectric generators, or RTGs). Its half-life is about 88 years.
- A notable accident, SNAP-9A in 1964, dispersed about 1 kilogram of Pu-238 around the world, but RTG designs are heavily shielded and considered extremely safe. They are built to prevent release even in accidents, using ceramic fuel, graphite blocks, and protective casings.
- If a release did occur, the most likely concern would be environmental contamination, but current designs aim to keep this very unlikely.

How plutonium behaves in the environment
- Plutonium tends to bind strongly to soil particles, so it often stays put in soils and sediments. However, its chemical form can affect how mobile it is.
- Some forms of plutonium can travel with water in the environment, while others stay attached to particles.
- In the body, plutonium is transported by the iron system and tends to accumulate in the liver. Inhaled plutonium can lodge in the lungs and has been linked to cancer in animal studies.
- Treatments exist to help after exposure, such as chelating agents that grab the plutonium and help remove it from the body.

Notable points
- Plutonium released by weapons testing has contributed to the radioactive landscape, but the overall health impact depends on the form and exposure.
- Plutonium in the environment remains a long-term concern because of its long-lasting radioactivity, so monitoring and careful handling continue to be important.