Radiation in the environment
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Gamma Radiation
Radioactive decay occurs when an unstable radioactive atom releases energy in order to stabilize itself. Most radioactive decay takes the form of beta or alpha decay with a small percentage of spontaneous fission. In most cases radioactive decay is accompanied by gamma radiation. Gamma radiation and x-rays have the highest energy of electromagnetic radiation (other examples of electromagnetic radiation are, in order of decreasing energy, ultraviolet light, visible light, infrared light, microwaves and radio waves).
The energy of gamma radiation emitted in radioactive decay can inform us what element it came from. This technique is known as gamma spectroscopy and is used to monitor radiation emissions in the environment.
Environmental monitoring
Samples of milk, lamb, fish or seawater are placed on a detector that measures the gamma ray emission from the sample. A typical environmental sample in Iceland is measured for 1 to 3 days in order to decrease the statistical uncertainty of the measurement. The number and energy of gamma rays are counted and form a gamma-ray spectrum, with energy along the x-axis and concentration (number of counts) along the y-axis.
The energy of the gamma radiation from each sample enables us to determine which radioactive substances are present in the sample. The concentration (counts) enables us to determine how much of a particular radioactive substance is present.
The radioactive content of Icelandic environmental samples is generally very low and measurements of man-made radioactive elements are often below detection limits in particular types of samples, e.g. fish and seaweed.
Monitoring of gamma radiation in Iceland
In addition to environmental monitoring, the Icelandic Radiation Safety Authority monitors gamma radiation at four sites in Iceland. The measurements are a collaboration between the Icelandic Radiation Safety Authority and the Icelandic Meteorological Office.
Gamma radiation dosimeters have been installed at four automatic measurement stations of the Meteorological Office:
in Reykjavík
in Bolungarvík
on Raufarhöfn
For a chart of the radiation intensity ("Geislunarstyrkur") across all gamma measurement stations, see the website of Veðurstofa Íslands.
The data is accessible to international partners and it is possible to view environmental gamma radiation measurements in Europe on the EURDEP project website.
Service provider
The Icelandic Radiation Safety Authority