How does radiation affect the environment?

—Positive: Natural radiation showers down from the distant reaches of the cosmos and continuously radiates from the rocks, soil, and water on the Earth itself.

—Negative: can result in pollution to the environment, killing plants and nature.

—In conclusion: Most radiation originates from earthly sources, and the real effects of radiation pollution depend on the type of radiation and the amount of energy emitted. High doses of radiation can kill, but low doses can actually benefit both plants and animals.

Half- life

—Half-life is the period of time it takes for a substance undergoing decay to decrease by half. The name was originally used to describe a characteristic of unstable atoms (radioactive decay), but it may apply to any quantity which follows a set-rate decay.

Biological half- life

—Biological half- life or elimination half-life is the time it takes for a substance (drug, radioactive nuclide, or other) to lose half of its pharmacologic, physiologic, or radiological activity. In a medical context, half-life may also describe the time it takes for the blood plasma concentration of a substance to halve ("plasma half-life") its steady-state. The relationship between the biological and plasma half-lives of a substance can be complex, due to factors including accumulation in tissues, active metabolites, and receptor interactions.

Example of half- life

—For example, the biological half-life of water in a human is about 7 to 14 days, though this can be altered by behaviour. The biological half-life of cesium in humans is between one and four months. This can be shortened by feeding the person Prussian blue, which acts as a solid ion exchanger which absorbs the cesium while releasing potassium ions.

Why despite knowing that radiation is harmful, japan is still pumping water into the ocean

Low-level radioactive seawater

—Used to cool overheated fuel rods, back into the sea for the past five days due to a lack of storage capacity

Why does Japan say that the iodine would disappear(half- life) after a while?

—Only in the case where you have a high concentration of radioactive iodine in your surroundings will you have any effect at all.

—Radioactive iodine, or Iodine-131, has a half life of only about eight days, and would quickly disappear from the atmosphere.

Pictures to advice the public on radioactivity