page_title: Environmental radioactivity
section_title: Transfer to ground
hierarchical_section_title: Environmental radioactivity / Natural / Activation products from cosmic rays / Transfer to ground
caption_attribution_description: English: Graph of Be-7 deposited per month in Japan. The graph was drawn using data from a scientific paper.M. Yamamoto et al. Journal of Environmental Radioactivity, 2006, 86, 110-131
context_page_description: Environmental radioactivity is produced by radioactive materials in the human environment. While some radioisotopes, such as strontium-90 and technetium-99, are only found on Earth as a result of human activity, and some, like potassium-40, are only present due to natural processes, a few isotopes, e.g. tritium, result from both natural processes and human activities. The concentration and location of some natural isotopes, particularly uranium-238, can be affected by human activity.
context_section_description: The level of beryllium-7 in the air is related to the sun spot cycle, as radiation from the sun forms this radioisotope in the atmosphere.  The rate at which it is transferred from the air to the ground is controlled in part by the weather.
caption: The rate of delivery of Be-7 from the air to the ground in Japan (source M. Yamamoto et al., Journal of Environmental Radioactivity, 2006, 86, 110-131)
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