Earth scientist Laurence Yeung wins Clarke Award

Biological creatures produce molecules that serve as tracers, bits of evidence that say something about their environment. Rice University geochemist Laurence Yeung, the winner of this year’s F.W. Clarke Award, sees it as his mission to hear them.

Yeung, an assistant professor of Earth science who joined Rice in 2015, will accept the prestigious award in July at the Geochemical Society‘s conference in Yokohama, Japan. The Clarke Medal is given annually by the society to an early career scientist for a single outstanding contribution to geochemistry or cosmochemistry.

Laurence Yeung

Laurence Yeung

Yeung is the third Rice researcher to win the Clarke Medal in recent years, joining Cin-Ty Lee and Rajdeep Dasgupta, both professors of Earth science. The medal is named for Frank Wigglesworth Clarke, who is considered the father of geochemistry for having determined the composition of Earth’s crust.

The 2016 award recognizes Yeung’s efforts to develop, through experimentation and theory, a new set of tracers based on how often rare isotopes are found “clumped” together in the same molecule. He was lead author of a Science paper last year that revealed the unique chemical signatures of photosynthesis as found in oxygen isotopes and suggested how they could help monitor the health of oceans.

Photosynthesis tends to pair up oxygen atoms to make oxygen molecules, and sometimes the atoms are rare heavy isotopes that contain one or two extra neutrons. Photosynthesis or other biological processes that take place under particular environmental conditions determine how often these rare isotopes clump together.

These clumps can be detected by advanced mass spectrometers. While there may only be a few clumps among millions of molecules, they are measurable, and the arrangement of their isotopes can serve as a molecular record of their physical and chemical histories.

Sophisticated tools and new concepts by Yeung and his colleagues are opening a path for researchers to study ever-finer details of the mechanisms involved in biogeochemical processes, including atmospheric mixing and ocean-atmosphere exchange.

“I utilize the imprint the chemistry has on these rare, stable isotopes to learn something about how much of this chemistry is happening on a larger spatial scale,” Yeung said.

Yeung studied chemistry as an undergraduate at Oberlin College with thoughts of attending medical school. His career plans took a turn after he heard a professor describe how chemists solved the puzzle of the ozone hole in Earth’s atmosphere.

“I said, ‘This is how I can fit in,'” he recalled. “This is how I can take how my brain works and apply it to something useful.”

His timing was impeccable. “In the mid-1900s, people were focused on looking at the abundance of molecules that had single rare isotopes in them. Early in the 2000s, one of my graduate advisers at CalTech, John Eiler, realized the technology had gotten so good that he could start looking at things containing more than one isotope. He started this whole field.”

Primary among these tools is the mass spectrometer. Advanced versions can find differences of parts per trillion in samples of oxygen, carbon and nitrogen, all topics of ongoing study for the clues they offer about Earth’s geologic history.

Yeung’s interests extend to effective scientific communications with the public. To that end, he partnered with the creator of the popular PHD Comics in 2012 on a Web-based science outreach venture and also produced an animated video explaining his work on using molecular tracers to analyze carbon cycling at the edges of the Amazon River plume in the Atlantic Ocean. It was seen by more than 30,000 middle-school students around the world as part of the Ocean180 video contest, he said.

He’s also interested in using the new generation of tools to eventually help analyze data from planets other than Earth. That will be the topic of his Science Café presentation at 6:30 p.m. March 1 at the Black Labrador Pub in Houston.

“Depending on the path of some of the tracers we’re working on, there is the possibility that we can use these types of correlations between isotopes to look for evidence of life on other planets,” he said. “It’s very interesting to think about how we would do this.”





About Mike Williams

Mike Williams is a senior media relations specialist in Rice University's Office of Public Affairs.