Argon’s days of having a fixed atomic weight are gone. For the first time since its discovery in 1894, the noble gas’s weight will be defined by an interval, reflecting how its isotope composition varies depending on the source. The International Union of Pure and Applied Chemistry (Iupac) also updated the atomic weights of another 13 elements.

Argon has three stable isotopes, but their ratio depends on where the gas comes from. On Earth, radioactive potassium-40 decays to argon-40 as the most common isotope. In stars, nucleosynthesis mostly creates the lighter argon-36 and argon-38. But even in terrestrial deposits, ‘isotopic abundance of argon-40 varies from around 94% to 100% depending on where it is from’, explains Juris Meija, who heads Iupac’s commission on isotopic abundances and atomic weights. In terrestrial samples the ratio of argon-36 to 38 to 40 is usually around 0.3:0.1:99.6, while in the sun it’s closer to 84:15:1. Read more.

IAEA will use stable isotope technique to assess body composition to tackle childhood obesity. The IAEA initiative will use the deuterium dilution technique in a sample of school children from the 10 countries to describe the relationship between BMI and body composition. The deuterium dilution technique is a state-of-the-art methodology to assess body composition and thus provides a tool to evaluate the effects of altered diet and physical activity on adiposity.

A person drinks a weighed amount of water, that is labeled with deuterium, a stable isotope of hydrogen. Read more.

For years, the standard way to date ancient organic items for history was to use radiocarbon dating. It has been an important dating tool available to scientists and archaeologists who deal with organic matter regularly and are often required to date these items accurately to place them within context and timelines.

Also called carbon dating or carbon-14 dating, this method involves isolating the radioactive carbon within organic matter to determine the age of it. By locating the radioactive isotope carbon-14 in organic matter, scientists could determine the age of an item. Every living thing continues to exchange carbon while it is alive. However, once something dies, be it flora or fauna, the collection of carbon ceases. Therefore, radiocarbon dating is used to measure when this occurred in order to date an item. Read more.

The Yellowstone supervolcano has been the focus of news stories, conversation, and speculation, as according to several experts, it’s overdue for the next mega-eruption.

The big question then is, when will Yellowstone erupt?

Unfortunately, geologists and volcanologists are not yet able to pinpoint exactly when the volcano will erupt, but a new study has provided a technique for measuring how quickly magma is building up beneath of the supervolcano.