Soil, water and metals are being exploited by agricultural practices, mining and human consumption faster than ever before. To better manage our use of these precious resources, we need to understand how they are made and destroyed at molecular level. On a mission to join the dots and help us use the Earth's resources more sustainably, the EU-funded IsoNose project is using isotopic techniques to measure geochemical processes.
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“The Earth’s surface is a huge chemical reactor,” explains IsoNose project coordinator Friedhelm von Blanckenburg. Surface matter moves around the Earth’s surface: rivers flow, moving sediment across the Earth; weathering transforms soil into rock; and growing plants move trace elements, transforming the content of soil.
Enormous transfer cycles of matter are continuously taking place. But how do our metal resources, such as nickel, zinc, chrome and copper, form and dissolve in this big chemical reactor, called the Earth’s surface? To answer these and other questions,
the IsoNose project offers researchers a new way to look at the Earth’s surface.
The nitty-gritty isotopes and geochemical fingerprints
Using advanced techniques and tools, the IsoNose project is exploring isotopes, which are small sub-particles of chemical elements. Each element consists of several isotopes, which differ in atomic mass. “When one of these isotopes moves, others move or change too, and these shifts create unique geochemical fingerprints,” says von Blanckenburg.
“From these fingerprints,” he explains, “we can make deductions to help us in metal ore exploration, agricultural food production, forensic science and environmental science, including measuring pollution levels in soil and water.”
That’s why the project recruited and trained 13 PhD students and two post doctorate fellows across Europe. They are using these isotopes as underlying principles for geoscience, and measuring these geochemical transformations using high-tech mass spectrometry an analytical instrument.
During the first year of the project, the students learned the methods of mass spectrometry as part of an intensive training programme. During the second year, they came to grips with specific research questions of their choice. “We are now in the third and fourth year of researching and writing up the research findings,” says von Blanckenburg.
Fungi and plants as geo-actors
IsoNose researchers have been investigating the interaction between geological processes and fungi, and they found that when placed in a test tube, black fungi dissolve olivine, a glassy-green mineral.
“Invisible to the naked eye, these micro-organisms ‘eat rock’ by extracting nutrients from it. This fungus is even a picky eater, preferring to break down rocks with heavier magnesium isotopes,” he says.
In Ireland, an IsoNose researcher has joined forces with a mining company to find new ways of learning more about the minerals below the Earth’s surface. “This researcher has measured zinc and other metals in the leaves of trees. With knowledge of the isotopes in the leaves, we can determine the minerals in the ground,” reports von Blanckenburg.
These findings are extremely interesting for the mining industry. “The researcher and the mining company are looking at using this knowledge and the measuring tools involved for mapping and prospecting for elements, such as lead and zinc. This would avoid the need for digging or drilling when looking for minerals,” he points out.
Laser technology for quick analysis
The IsoNose project is continuing to develop the analytical methods used to measure these isotopes, and one of the project’s post doctorate researchers has teamed up with a large mass spectrometry company to refine them.
They are working on a method that casts a laser onto a flat slice of rock placed in a chamber beneath a glass window containing helium. In the chamber, the tiny sample vaporises, and after steaming the sample vapour into the detector, a mass spectrometer, scientists are able to identify the material, including its chemical composition and the distribution of its isotopes, on a microscopic scale. Scientists thus put this information together with that on the texture of the mineral.
This method the laser ablation technique differs to more traditional methods that involve breaking down the mineral in an acidic substance to determine its isotopic composition. von Blanckenburg hopes that this technique will be widely taken up in the future.
“Geoscientists the pioneers of the method need to transfer their knowledge and their tools for use in other fields, such as environmental science, mining and forensic science,” says von Blanckenburg. The geochemistry conference Goldschmidt2017, in Paris in August, will serve as a springboard for the transfer of IsoNose findings and innovations across the global scientific community.