This week (19th Oct–24th October) is Real Time Chem Week (if that means nothing to you, check out their FAQ page here!). As part of this week, I thought it’d be fun to get chemists working in research to communicate some of what their research involves, and why it matters to non-chemists, here on the CI site. The incentive? They’d also get a graphic made, based on their research, for their trouble.

There were actually a great range of entries to this competition, and on the one hand it’s a shame that I couldn’t make a graphic for all of them. On the other hand, it would have been an impossibility to do so in just a week! There will be five graphics appearing here in total, accompanied by a sub-500 word explanation from the researchers themselves. As such, the posting schedule will be a little more busy than usual, with a graphic appearing each day this week until Friday!

Dr. Chelsea Sutcliffe is currently researching how isotope ratios can help to detect life in environments where life can’t be detected by other means. Here, she explains what her research entails, and how it could have relevance for discovering life on other planets.

“Isotope geochemists study the behaviour of isotopes, atoms of the same element with different masses, in natural systems and earth processes. Using machines called mass spectrometers that can detect the relative abundances of different isotopes in samples such as rock, water, and gas, we deduce what has happened in the geological past.

My current research focuses on stable isotope geochemistry. Stable isotopes are not affected by radioactive decay and are stable over geological time. Isotopes can behave differently in the same reaction due to their varying masses, so we analyse rocks, water (e.g. sea, lakes, rivers) and gas (e.g. the atmosphere) and measure the relative proportions of heavier and light isotopes to deduce what processes have occurred in the sample material.

An example of this is that living organisms take up lighter isotopes preferentially over heavier isotopes (as it uses up less energy), so organisms typically have higher concentrations of lighter isotopes than of heavier isotopes. We use this trait to detect the imprint of life in materials, called biosignatures.

One of the current aspects of my research focuses on detecting these biosignatures to identify where life is, or has been, present in environments in which life can’t be detected using other means. One such environment is within salty water found trapped within the oldest rocks on Earth, located up to 3km deep in the Canadian Shield. These fluids are prevalent in old rocks billions of years in age in places like South Africa, where life has been detected 2.8km deep in the surface, and Canada.

In Canada, our research team has detected high concentrations of dissolved gases such as hydrogen (H 2 ) and methane (CH 4 ) in these fluids, and these compounds can be consumed by or produced by organisms known as chemolithotrophs or methanogens. I analyse these gases using a combination of gas chromatography to separate the gases, and mass spectrometry and measure the isotopic ratios of hydrogen (2H/1H) and carbon (13C/12C) to detect biological signatures.

Using radiogenic isotope dating techniques, our research team has estimated an age of at least a billion years for these salty fluids, and given their prevalence we are interested in whether they have the potential to host life following NASAs “follow the water” mantra for detecting life on other planets. As the Martian surface is hostile to life forms (due to sub-zero temperatures and intense UV ray bombardment), past or present life on Mars could be located within analogous salty fluids located within the subsurface. This is especially relevant given the recent discoveries of salty flowing water and methane on Mars. The more we discover where and how these life forms exist on Earth, the greater the potential to reveal whether life is, or has been, present on Mars and on other planets!”

Further Reading:

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