Using isotope fingerprints to solve a methane mystery

Atmospheric methane levels are rising, and isotopic ratios within the greenhouse gas suggest that the tropics may be to blame.

Although methane decays more quickly in the atmosphere than carbon dioxide does, it rapidly absorbs heat and is a potent greenhouse gas. In 2007, after nearly 2 decades of slowed growth in atmospheric methane levels, the amount of this gas in the air began to rapidly rise.

Historically, rises in methane levels have been driven by fossil fuel leaks. However, earlier this year, researchers at the National Institute of Water and Atmospheric Research in New Zealand found that biogenic sources, which they thought were from agriculture, were the primary cause of the uptick. Read more.

40 Under 40: ORNL’s Brian Egle

Thanks to Brian Egle’s work at Oak Ridge National Laboratory, scientists from a variety of disciplines will have the materials they need to solve some of the world’s most pressing problems. Egle, a Weinberg Fellow and senior research engineer at the lab, has been working to reestablish a domestic source of stable isotopes that are in short supply. Read more.

Infographic: Advancing Forensics Science

Forensic scientists have been using rudimentary molecular techniques for decades. But advanced forensic anthropology technologies and methods are just now coming to the fore in some investigations.

Currently approved and accepted forensic anthropology methods include creating a so-called biological profile of a crime victim or set of remains. This involves taking several measurements, especially of skeletal and cranial features, that can indicate age, gender, stature, and even ancestry ...

Over the last decade, forensic scientists have begun to adapt the mass spectrometry used by ecologists, archaeologists, and paleoclimatologists to uncover hidden dynamics or origins using isotopic ratios. Comparing the relative levels of different isotopes of certain elements—for example, strontium, carbon, oxygen, hydrogen, and nitrogen—in hair, teeth, or bones with abundances of these isotopes in soils or drinking water can suggest a geographic origin, diet, time of death, or travel history for an individual. For example, levels of 18O—a heavier stable isotope of oxygen than normal 16O—in hair can indicate how closely someone lived to a coastline, because drinking water in those regions is typically more 18O rich than inland areas. Read more.

Forensics 2.0

Meet the researchers working to untangle the mystery of a Missouri home filled with bones by bringing cutting-edge technologies into the crime lab.

Forensic anthropologist Lindsay Trammell had only just received the human remains and she already knew that she’d need help with this case. It was the summer of 2014, and 15 skeletons had arrived at the St. Louis Medical Examiner’s Office as a jumble of bones inside four wooden coffins. Some of the bones looked ancient; they were “falling apart,” Trammell recalls. But others were in relatively good shape. “There were different levels of preservation throughout the remains.”

She photographed, inventoried, and measured the skeletal elements employing the standard biological techniques typically used by forensic anthropologists, who are still by and large not regular fixtures in crime labs. Those analyses indicated that some of the skulls bore characteristics of people with African ancestry while others did not. “Just by looking at them, my inclination was that they were from different ancestral groups,” Trammell says.

Something wasn’t adding up. Read more.

Moon is proto-Earth’s mantle, relocated

Measurements of an element in Earth and moon rocks have just disproved the leading hypotheses for the origin of the moon.

Tiny differences in the segregation of the isotopes of potassium between the moon and Earth were hidden below the detection limits of analytical techniques until recently. But in 2015, Washington University in St. Louis geochemist Kun Wang, then the Harvard Origins of Life Initiative Prize postdoctoral fellow, and Stein Jacobsen, professor of geochemistry at Harvard University, developed a technique for analyzing these isotopes that can hit precisions 10 times better than the best previous method. Read more.