"A dye is not a good tracer if the water is heavily colored, so we were asked to find a good alternative," said Professor Silvia Jurisson. "Technetium-99m is very easy to track since there's not a lot of background radiation that could create problems, and it has a six-hour half life. After 24 hours, this isotope is virtually gone."
Following several tests of various radioactive molecules, Jurisson discovered that technetium-99m in the form of pertechnetate was the best. (Pertechnetate is used in the medical imaging of organs in the human body.)
"The molecule is great because it emits a very low energy gamma ray, and water is a great natural shield against radiation," Jurisson said. "In addition, you only need to use a very small amount as a tracer for the pollution."
(Source: Environment News Service)