Johanna-Iisebel Järvelill - Are Estonian Beaches Radioactive?
The term radioactivity usually brings to mind man-made sources of radiation, such as the X-ray or various catastrophes, for example Chernobyl. In reality, we are surrounded by natural radioactive background, such as the radiation that reaches us from Space, or radon that lies in the earth. Even the sand at the beach can be radioactive, says Johanna-Iisebel Järvelill, a PhD student at Tallinn University.
The term radioactivity usually brings to mind man-made sources of radiation, such as the X-ray or various catastrophes, for example Chernobyl. In reality, we are surrounded by natural radioactive background, such as the radiation that reaches us from Space, or radon that lies in the earth. Even the sand at the beach can be radioactive, says Johanna-Iisebel Järvelill, a PhD student at Tallinn University.
Sand is made up of minerals. Minerals are solid chemical compounds that have formed through natural physiochemical processes. Better known minerals are halite, or rock salt, and gold and silver. They are all characterised by a definite or minutely changing chemical composition and physical attributes.
The sand at a beach is usually bi-mineral, as it is mainly made up of two minerals – quartz and feldspars. Quartz is composed of silicon and oxygen; feldspars have the same two components, but also aluminium, potassium, sodium or calcium and other chemical elements.
In addition to quartz and feldspars, sand consists of other minerals, such as zircons. Zircon consists mainly of zirconium, silicon and oxygen, but oftentimes zirconium has been replaced with uranium or thorium, which are radioactive elements.
Such replacement is a natural process and has nothing to do with human activity. Such sediments have mostly arrived with icecaps from Finnish crystal basements and the glaciers that once made up the Gulf of Finland. Sediments from these areas contain uranium, thorium, and a radioactive isotope from potassium.
The radioactivity in these elements comes from the decomposing of unstable nuclei. Radioactive radiation is ionising, which means it breaks the chemical bonds between molecules.
Thus, sands with a high volume of zircon can have higher levels of radioactivity. For example, there is a beach called Lemme in the southwest of Estonia, which has a radioactivity level 14 times higher than the natural background. Thankfully, there is no settlement there, as it would be non-recommendable.
Such high levels of radioactivity are very rare, and the zircon in sand is not dangerous to people. We will get much higher doses of radioactivity when flying planes or letting the dentist take an X-ray.
Radioactivity surrounds us everywhere, even on the beach, but it is mostly part of the natural background, which causes no harm to the human health.