Eco-glue can replace harmful adhesives in wood construction

A fast and energy-efficient manufacturing process results in a strong, non-toxic and fire-resistant adhesive—and a great opportunity for the bioeconomy

Peer-Reviewed Publication

AALTO UNIVERSITY

 

IMAGE: PLYWOOD WITH ECO-GLUE PRODUCED AT AALTO UNIVERSITY. view more 

CREDIT: AALTO UNIVERISTY

Researchers at Aalto University have developed a bio-based adhesive that can replace formaldehyde-containing adhesives in wood construction. The main raw material in the new adhesive is lignin, a structural component of wood and a by-product of the pulp industry that is usually burned after wood is processed. As an alternative to formaldehyde, lignin offers a healthier and more carbon-friendly way to use wood in construction.

The carbon footprint of timber construction is significantly lower than concrete construction, and timber construction has often been viewed as better for the health of human occupants as well. However, wood panels still use adhesives made from fossil raw materials. They contain formaldehyde, which can be harmful to health, especially for those working in the adhesive manufacturing process.  People living in or visiting buildings can also be exposed to toxic formaldehyde from wood panels. 

Lignin, on the other hand, comes from wood itself. It binds cellulose and hemicellulose together and gives wood its tough, strong structure. Lignin accounts for about a quarter of the weight of wood and is produced in huge quantities in the pulp and bioprocessing industry. Only two to five percent of the lignin produced is used, and the rest is burned in factories for energy.

Previously, lengthy and chemical-intensive pre-treatments have been necessary to use lignin in formaldehyde-free adhesives. The adhesive developed by Aalto University researchers can use purified kraft lignin and the chemical reaction to make the adhesive takes a few minutes instead of up to 10 hours. No additional heating of the raw material is needed, which reduces energy consumption. The only by-products of the process are salt and sodium hydroxide, or lye.

Monika Österberg, professor at the Aalto University School of Chemical Engineering, stresses that this is an important development for both the environment and industry. ‘Using lignin as a material can reduce carbon dioxide emissions and increase the processing value of forests. This is why research on lignin is an important priority for us at Aalto University.’

Doctoral researcher Alexander Henn explains that glued wood panels such as plywood and chipboard are increasingly used for walls, ceilings and flooring. ‘Therefore, it is important to overcome the disadvantages of wood-based panel adhesives and develop the new innovation into a commercial product. This would enable a shift towards more wood-based construction, as a strong and heat-resistant adhesive made from natural materials makes construction truly ecological and safe.’

The innovation is a major step forward for the forestry and glue industries, as the lignin content of previous adhesives has been relatively low (around 20-50 percent), while the new Aalto University innovation has a lignin content of over 90 percent. The adhesive is strong and non-toxic, and protects surfaces from fire, so it can even be used as a flame retardant.

According to the researchers, lignin can also be used as a raw material for applications such as coatings and composites. Research work will continue in the laboratory, and various commercialization opportunities are likely to be explored in collaboration with LignoSphere Oy, a spin-off from Aalto University.

This research was published in August 2022 in the journal Green Chemistry.

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DOI

10.1039/D2GC01637K 

A greener route to blue – a new method drastically reduces the amount of solvent needed to produce widely used organic dyes

Phthalocyanines are used in renewable energy production, sensing, nanomedicine and more. Researchers at Aalto University have demonstrated how the dye can be produced in a greener way that minimizes high-boiling organic solvents, by using solid-state syn

Peer-Reviewed Publication

AALTO UNIVERSITY

 

IMAGE: EVOLUTION OF DYE FORMATION OVER 48 HOURS OF REACTION TIME, AFTER DISSOLVING EQUAL AMOUNT OF SOLID INTO EQUAL AMOUNT OF SOLVENT. view more 

CREDIT: SANDRA KAABEL / AALTO UNIVERSITY

Organic, i.e. carbon-containing dyes have important roles in nature. For example, they are responsible for transporting oxygen and other gases in the body (as part of haemoglobin) and converting solar energy into chemical energy in photosynthesis (chlorophyll).

One class of artificial organic dyes is phthalocyanines, which are widely applied in industrial processes, sensing, nanomedicine, solar cells and other optoelectronics. However, the production of phthalocyanines is not without its issues, says Eduardo Anaya, Aalto University Academy Research Fellow. ‘Phthalocyanines are produced by using a lot of solvents such as dimethylaminoethanol (DMAE). It is corrosive, flammable, bioactive and harmful to the environment.’

Anaya and colleagues at Aalto University have demonstrated how phthalocyanines can be produced in a more environmentally friendly way with solid-state synthesis. Their research, published in the journal Angewandte Chemie International Edition, was categorised as a “hot paper”.

Industry in the European Union alone uses 10,000 tonnes of DMAE per year for many different processes. In the new method introduced by Aalto researchers, the amount of solvent is reduced by over 99%, says postdoctoral researcher Sandra Kaabel, another of the main authors.

The research team used phthalonitrile as the starting material, an organic compound commonly used in the production of dyes. It was first processed with a few drops of DMAE and a zinc template by ball-milling, after which the solid reaction mixture was aged in an oven at 55 °C for a week, or at 100°C for 48 hours.

‘It was fascinating to see how the colour went from white, through green and changed into a deep blue in the oven – you could see with your own eyes how the method works,’ says Kaabel. ‘By solid-state methods we can produce chemicals without needing to dissolve the components of the reaction.’

In the traditional method, a solvent is heated in between 160 to 250°C and the overall yield is fairly low in relation to the materials and time spent. The environmentally-friendly method developed by Aalto researchers boosted the space-time yield four-fold by removing most of the solvent and carrying out the reactions at a lower temperature.

Example from nature, idea brewed over coffee

The molecular structure of phthalocyanine makes it adaptable to a wide range of applications.

‘Nature is an inspiration, having created organic colours for many different purposes over millions of years,’ says Anaya. ‘We can capture them as they are and use colours in artificial photosynthesis to produce energy, for example, or take ideas even further.’

Ideas for new biomaterial solutions are refined at FinnCERES, a competence centre shared by Aalto University and VTT Technical Research Centre of Finland. The research group is working within the FinnCERES project “SolarSafe” to develop cellulosic material that is self-sterilizing through a reaction initiated by a dye and light and could be applied in biomedicine.

Such new ideas are born through encounters, both inside and outside the lab. ‘The idea for our new way to produce dyes also came about from us brainstorming in the coffee room–and then we just started experimenting,’ says Daniel Langerreiter, the first author and a PhD student in the group.

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DOI

10.1002/anie.202209033 

CAPTION

As-obtained crude end-product after the solid-state synthesis.

CREDIT

Sandra Kaabel / Aalto University

New classification of the world’s coastlines to improve climate action

Business Announcement

COASTAL HAZARD WHEEL INITIATIVE

 

IMAGE: THE COASTAL HAZARD WHEEL 3.0 CONSISTING OF SIX COASTAL CLASSIFICATION CIRCLES, FIVE HAZARD CIRCLES AND THE COASTAL CLASSIFICATION CODES. IT IS USED BY STARTING IN THE WHEEL CENTRE MOVING OUTWARDS THROUGH THE COASTAL CLASSIFICATION. view more 

CREDIT: ROSENDAHL APPELQUIST 2016; 2013. HTTPS://WWW.COASTALHAZARDWHEEL.ORG/

Copenhagen, 31st August 2022

A new classification of the world’s coastlines has been released to improve coastal climate change adaptation at local, regional and national level and strengthen coordinated climate action worldwide. The classification builds on the Coastal Hazard Wheel that is a universal coastal management framework and is developed by the Coastal Hazard Wheel initiative involving Deltares, the UN Environment Programme-DHI Centre (UNEP-DHI Centre) and the UNEP Copenhagen Climate Centre, with contributions from University of Copenhagen, the Food and Agriculture Organization of the United Nations (FAO), the International Fund for Agricultural Development (IFAD) and the Novo Nordisk Foundation.

The new global coastal classification can be used by public authorities, planners and researchers to determine the key characteristics of a specific coastal location, identify relevant adaptation measures and map the full spectrum of coastal hazards, including ecosystem disruption, gradual inundation, salt water intrusion, erosion and flooding, from local to global level.

The classification makes use of the latest global geodata from remote sensing, on-site observations and modelling. It thereby provides coastal classification, hazard information and adaptation guidance for coastal stretches down to about 200 meters. The global coastal classification and adaptation guidance is made freely available as a web-application, the Coastal Hazard Wheel App, which is available via www.coastalhazardwheel.org through regular web browsers.

“With close to two billion people now living in coastal areas worldwide, timely and appropriate adaptation action is critical” says Dr Lars Rosendahl Appelquist, Head of the Coastal Hazard Wheel initiative. “The new global coastal classification and adaptation guidance can help public authorities and planners with identifying relevant management measures and can facilitate integrated coastal management and communication worldwide”.

Building proper resilience and reducing disaster risk in coastal areas is a major global challenge and particularly urgent for Small Island Developing States (SIDS). FAO and the Coastal Hazard Wheel initiative are therefore working together to test and further develop the new global coastal classification system in its efforts to support SIDS and other coastal countries with adaptation through healthy coastal ecosystems and resilient communities.

The new global coastal classification can improve and broaden the awareness and understanding of coastal challenges and the impacts of climate change. Moreover, the classification can support multi-stakeholder processes from local to global level as well as investment plans to address bottlenecks and needs. Furthermore, the classification and coastal coding system can be used as a common coastal language to facilitate communication between local, regional and national authorities, policy-makers, international organisations, researchers and practitioners.

 

NOTES TO EDITORS

About the Coastal Hazard Wheel initiative

The Coastal Hazard Wheel initiative is an international partnership with the aim of providing a detailed open access classification of the world’s coastlines and automated climate change adaptation guidance with increasing accuracy. More information can be found at www.coastalhazardwheel.org

 

About the Coastal Hazard Wheel

The Coastal Hazard Wheel methodology is a universal coastal classification and management framework to address all the main coastal challenges simultaneously. It can be used as a complete coastal language and aims to boost climate change adaptation and bridge the gap between scientists, policy-makers and the general public.

 

For more information, please contact the Coastal Hazard Wheel initiative at lra@coastalhazardwheel.org

DOE announces $70 million to improve supercomputer model of earth's climate system

National labs and university research aims to further scientists’ understanding of climate change

Grant and Award Announcement

DOE/US DEPARTMENT OF ENERGY

WASHINGTON, D.C. — The U.S. Department of Energy (DOE) today announced $70 million in funding for seven projects that will improve climate prediction and aid in the fight against climate change. The research will be used to accelerate development of DOE’s Energy Exascale Earth System Model (E3SM), enabling scientific discovery through collaborations between climate scientists, computer scientists, and applied mathematicians. Data from this model will enhance scientists’ understanding of climate change, which will be crucial to furthering President Biden’s commitment to tackling the climate crisis at home and abroad. 

“Being able to understand and predict what is happening in a system as complex as planet Earth is crucial to finding solutions to climate change,” said U.S. Secretary of Energy Jennifer M. Granholm. “The projects announced today will give university and National Lab researchers deep insight into our oceans, our air, and our climate and into how emissions are impacting the world around us right now and in the future.”

The projects will be led by researchers at DOE’s Los Alamos National Laboratory and Pacific Northwest National Laboratory as well as the University of New Mexico.

E3SM is an ultra-high-resolution model of Earth that is run on exascale supercomputers—digital computers like the Frontier at Oak Ridge National Laboratory that are millions of times more powerful than modern personal computers. The model is constantly being improved to provide the best simulation and prediction possible to researchers in Earth system science.

The projects announced today will improve the E3SM by, for example, advancing simulations of ocean circulation in the Atlantic and developing a framework for modeling Antarctic systems.

The projects were selected through competitive peer review process under the DOE Funding Opportunity Announcement for Scientific Discovery through Advanced Computing. Total funding is $70 million for projects lasting up to five years in duration, with $14 million in Fiscal Year 2022 dollars and outyear funding contingent on congressional appropriations.

The list of projects and more information can be found here.

New aquaculture technology can help ease the global food crisis: “Enriched seaweed” with extremely high nutritional value

Peer-Reviewed Publication

TEL-AVIV UNIVERSITY

 

IMAGE: LEFT TO RIGHT: PH.D. STUDENT DORON ASHKENAZI & PROF. AVIGDOR ABELSON. view more 

CREDIT: TEL AVIV UNIVERSITY

• Researchers from Tel Aviv University and the Israel Oceanographic and Limnological Research Institute have developed an innovative method for growing seaweed enriched with nutrients, proteins, dietary fiber, and minerals for human and animal needs. The seaweed has the potential to be a natural superfood, and to help secure food for the future of humanity.

 

• The advanced technology promotes an environmentally-friendly approach of “sustainable integrated aquaculture.” As part the methodology, the seaweeds purify the water in which they grow and thus help maintain the ecological balance of the marine and coastal environment.

Researchers from Tel Aviv University and the Israel Oceanographic and Limnological Research Institute in Haifa have developed an innovative technology that enables the growth of “enriched seaweed” infused with nutrients, proteins, dietary fiber, and minerals for human and animal needs.

 

According to the researchers, the state-of-the-art technology significantly increases the growth rate, protein levels, healthy carbohydrates, and minerals in the seaweed’s tissues – making the “enriched seaweed” a natural superfood with extremely high nutritional value, which can be used in the future for the health food industry and to secure an unlimited food source.

 

The research was led by Ph.D. student Doron Ashkenazi, under the guidance of Prof. Avigdor Abelson from the School of Zoology, George S. Wise Faculty of Life Sciences at Tel Aviv University and Prof. Alvaro Israel of the Israel Oceanographic and Limnological Research Institute (IOLR) in Tel Shikmona, Haifa. The article was published in the scientific journal Innovative Food Science & Emerging Technologies.

 

Doron Ashkenazi explains that in the study, local species of the algae Ulva, Gracilaria and Hypnea were grown in close proximity to fish farming systems under different environmental conditions. The special conditions allowed the seaweed to flourish, and enabled a significant improvement in their nutritional value ​​to the point of their becoming “enriched seaweed,” which is a superfood. (The use of seaweed as a rich food source that meets all human nutritional needs is even reminiscent of the biblical manna that fed the Israelites in the desert). It will also be possible to use the enriched seaweed in an applied manner for other health industries, for example as nutritional supplements or as medicine, as well as in the cosmetics industry.

 

“Seaweed can be regarded as a natural superfood, more abundant in the necessary components of the human diet than other food sources,” Ashkenazi adds. “Through the technological approach we developed, a farm owner or entrepreneur will be able to plan in advance a production line of seaweed rich in the substances in which they are interested, which can be used as health foods or nutritional supplements; for example, seaweed with a particularly high level of protein, seaweed rich in minerals such as iron, iodine, calcium, magnesium, and zinc, or in special pigments or anti-oxidants. The enriched seaweed can be used to help populations suffering from malnutrition and nutritional deficiencies, for example disadvantaged populations around the world, as well as supplements to a vegetarian or vegan diet.”

 

Moreover, unlike terrestrial agriculture, aquaculture, and in particular our proposed seaweed farming approach, does not require extensive land, fresh water or large amounts of fertilizer. It is environmentally friendly, and preserves nature and the ecological balance by reducing environmental risks. The new methodology in fact offers an ideal situation, of sustainable and clean agriculture. Today, integrated aquaculture is beginning to receive support from governments around the world due to its environmental benefits, which include the reduction of nutrient loads to coastal waters and of the emission of gases and carbon footprints. In this way, it contributes to combatting the climate crisis and global warming.

 

Doron Ashkenazi concludes: “Technologies of this type are undoubtedly a model for a better future for humanity, a future where humans live in idyll and in health in their environment.” The research was conducted in collaboration with other leading researchers from around the country, including Guy Paz and Dr. Yael Segal of the Israel Oceanographic and Limnological Research Institute  (IOLR) in Haifa, Dr. Shoshana Ben-Valid, an expert in organic chemistry, Dr. Merav Nadav Tsubery of the Department of Chemistry in the Faculty of Exact Sciences at Bar-Ilan University, and Dr. Eitan Salomon from the National Center for Mariculture in Eilat.

 

Link to the article:

https://www.sciencedirect.com/science/article/pii/S1466856422001527

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DOI

10.1016/j.ifset.2022.103067 

ARTICLE TITLE

Enrichment of nutritional compounds in seaweeds via abiotic stressors in integrated aquaculture

CAPTION

Layout of the land-based, outdoor, aquaculture system as was stationed at the IOLR institute, Haifa, Israel.

CREDIT

Doron Ashkenazi.

CAPTION

Naturally growing intertidal seaweeds.

CREDIT

Doron Ashkenazi.

CAPTION

Underwater seaweed garden, Bat-Yam, Israel.

CREDIT

Doron Ashkenazi.

Marine Protected Areas in Antarctica should include young emperor penguins, scientists say

Peer-Reviewed Publication

WOODS HOLE OCEANOGRAPHIC INSTITUTION

 

IMAGE: TWO JUVENILE EMPEROR PENGUINS BEFORE THEIR FIRST SWIM IN ATKA BAY, ANTARCTICA. BOTH ARE EQUIPPED WITH AN ARGOS PLATFORM THAT WILL TRANSMIT THEIR LOCATIONS DAILY AND ALLOW SCIENTISTS TO TRACK THEIR MOVEMENT IN THE SOUTHERN OCEAN DURING THEIR FIRST YEAR AT SEA. view more 

CREDIT: CREDIT: AYMERIC HOUSTIN/© AWI-CSM-CNRS-FAU-WHOI

Woods Hole, MA (August 31, 2022) - Scientists at the Woods Hole Oceanographic Institution (WHOI) and European research institutions are calling for better protections for juvenile emperor penguins, as the U.S. Fish and Wildlife Service considers listing the species under the Endangered Species Act and the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) considers expanding the network of Marine Protected Areas (MPAs) in the Southern Ocean.

In one of the few long-term studies of juvenile emperor penguins–and the only study focused on a colony on the Weddell Sea–research published today in Royal Society Open Science found that the young birds spend about 90 percent of their time outside of current and proposed MPAs. The study, which tracked eight penguins with satellite tags over a year, also found that they commonly traveled over 1,200 kilometers (745 miles) beyond the species range defined by the International Union for Conservation of Nature (IUCN), which is based on studies of adult emperor penguins from a few other colonies. Considered immature until about 4 years of age, juvenile emperor penguins are more vulnerable than adults because they have not fully developed foraging and predator avoidance skills. As climate change reduces sea-ice habitat and opens up new areas of the Southern Ocean to commercial fishing, the researchers conclude that greatly expanded MPAs are crucial to protect this iconic, yet threatened, penguin species at every life stage.

“While everyone is looking at the adult population, the juvenile population – which leaves the relative safety of its parents at about five months - is neither monitored nor protected,” said Dan Zitterbart, a WHOI associate scientist. “The current and proposed MPAs in the Southern Ocean only include the range of adult emperor penguins, which do not travel as far as juveniles. From a conservation perspective, it’s important to know where these juveniles go. It’s one more piece of the puzzle to protect their marine habitat.”

“Emperor penguins have such low fecundity, if you do not protect juveniles, they may not ever become breeding adults,” he continued. 

Zitterbart and colleagues at the Centre Scientifique de Monaco (CSM), Centre National de la Recherche Scientifique (CNRS) and Université de Strasbourg in France, and the Alfred-Wegener Institute (AWI) in Germany are conducting a long-term monitoring study of the Atka Bay emperor penguin colony near Neumayer Station III, on the Weddell Sea. The Weddell Sea area is home to one-third of established emperor penguin colonies, and research shows that colonies in the region, including the Ross Sea, are less vulnerable to climate-induced melting than other areas of the Antarctic.

“Some of the Weddell Sea colonies are expected to still be present 50 to 100 years from now,” said Aymeric Houstin, a WHOI post-doctoral investigator and the lead author of the study. “It’s important to preserve colonies that will be able to endure climate change, as they could become a refuge for the entire population of emperor penguins.”

According to studies, 12 percent of the area under CCAMLR jurisdiction is currently protected as an MPA, and less than 5 percent is considered a “no-take” area. For several years, the 26 members of CCAMLR have been considering three new MPAs in the region, including the Weddell Sea MPA, first developed by Germany, and submitted by the European Union in 2013. While this MPA would cover an area of 2.2 million square kilometers (0.85 million square miles), preserving one of the most pristine ecosystems in the world and a critical zone for global ocean circulation, the authors say that the boundaries are inadequate to protect juvenile emperor penguins.

“The Weddell Sea MPA design, as the other MPAs around Antarctica, should include the distribution at sea of all age-classes of the emperor penguin population—not only the adults from a few study colonies,” said Céline Le Bohec, of CNRS/Université de Strasbourg France and the Centre Scientifique de Monaco. “Juveniles are currently clearly lacking protection and their presence in the Northern waters needs to be considered in the future, especially regarding the development of fisheries in those regions.”

Over the next decades, the researchers plan to continue tagging both adult and juvenile penguins from the Atka Bay colony to track their movements and behavior as the environment changes. With more long-term data, Houstin suggests that a “dynamic MPA” could be developed with shifting boundaries, based on predictions of penguins’ movements throughout the year.

“This notion of a dynamic network of MPAs is really essential,” Le Bohec said. “It’s certainly the way to continue the dialogue with the fishing industry to ensure the resource is used in a sustainable manner, to ultimately preserve the unique biodiversity of these sensitive polar regions.”

CAPTION

A group of Juvenile emperor penguins at Atka Bay on the sea ice edge ready for their first swim. In four years, they will return to breed, spending much of their time in unprotected areas of the Southern Ocean.

CREDIT

Credit: Daniel P. Zitterbart/©Woods Hole Oceanographic Institution

About Woods Hole Oceanographic Institution

Woods Hole Oceanographic Institution is a private, non-profit organization on Cape Cod, Mass., dedicated to marine research, engineering, and higher education. Established in 1930 on a recommendation from the National Academy of Sciences, its primary mission is to understand the oceans and their interaction with the Earth as a whole, and to communicate a basic understanding of the oceans’ role in the changing global environment. For more information, please visit www.whoi.edu.

This study was funded by the Centre Scientifique de Monaco with additional support from CNRS-University of Strasbourg, by The Penzance Endowed Fund and The Grayce B. Kerr Fund in Support of Assistant Scientists, and the Deutsche Forschungsgemeinschaft (DFG), with logistical support from Alfred-Wegener-Institut Helmholtz-Zentrum für Polar-und Meeresforschung (AWI).

'Diamond Factory' Discovered at Boundary of Earth's Core

A Quadrillion Tons Of Diamonds May Lie In Earth

The intense heat and pressure at the Earth's core, deep beneath the surface, is enough to make diamonds out of carbon, scientists say.

Researchers from Arizona State University's School of Earth and Space Exploration investigated the conditions at the boundary between the Earth's metal core and the magma in the mantle, and according to their paper published in the journal Geophysical Research Letters, have found that the carbon in the core's liquid iron metal alloy can form diamonds.

"The stable form of carbon at the pressure-temperature conditions of the Earth's core-mantle boundary is diamond," Dan Shim, a professor at Arizona State University and a co-author on the paper, said in a statement.

Stock image of the layers inside the Earth. Scientists have found that diamonds are created at the core-mantle boundary.

ISTOCK / GETTY IMAGES PLUS

The find was dubbed a "diamond factory" by Arizona State University.

The interior of the Earth is divided into several segments, all composed of different ingredients and states of matter. Underneath the thin rocky crust comes the mantle, a slow-moving layer of molten rocks making up 84% of the planet's total volume, according to National Geographic. It sits at between 1,832 degrees F and 6,692 degrees F. Further in comes the Earth's outer and inner core: the outer core is liquid iron and nickel, among other elements, and is around 9,000 degrees F, while the inner core is mostly made of solid iron, due to the intense pressures, and is about as hot as the surface of the sun.

The authors of the paper have measured how carbon in the liquid outer core comes out of the liquid iron metal alloy, reacts with water, and forms diamonds.

"Temperature at the boundary between the silicate mantle and the metallic core at [around 1,800 miles] depth reaches to [about 7,000 degrees Fahrenheit], which is sufficiently high for most minerals to lose H2O captured in their atomic-scale structures," Shim said.

"At the pressures expected for the Earth's core-mantle boundary, hydrogen alloying with iron metal liquid appears to reduce solubility of other light elements in the core. Therefore, solubility of carbon, which likely exists in the Earth's core, decreases locally where hydrogen enters into the core from the mantle (through dehydration)."

"So the carbon escaping from the liquid outer core would become diamond when it enters into the mantle."

Diamonds are made entirely from carbon atoms in a uniquely strong arrangement of chemical bonds. They can be found in the crust across the planet, but are incredibly rare and therefore expensive. Diamonds are thought to have been transported from their origins in the mantle to the Earth's surface via deep-source volcanic eruptions.

Stock image of a diamond. Diamonds have been found to be created at the boundary between the Earth's core and the mantle.

ISTOCK / GETTY IMAGES PLUS

The hardest known substance, the diamond, is used in industry for cutting and abrasion, as well as being a revered and symbolic jewelry gemstone.

"Carbon is an essential element for life and plays an important role in many geological processes. The new discovery of a carbon transfer mechanism from the core to the mantle will shed light on the understanding of the carbon cycle in the Earth's deep interior," Byeongkwan Ko, a recent Arizona State University PhD graduate and co-author of the paper, said in a statement. "This is even more exciting given that the diamond formation at the core-mantle boundary might have been going on for billions of years since the initiation of subduction on the planet."

BY JESS THOMSON - NEWSWEEK- 8/31/22 

Diamonds and rust at the Earth's core-mantle boundary

Scientists in ASU’s School of Earth and Space Exploration help discover that a potential “diamond factory” may have existed at Earth’s core-mantle boundary for billions of years

Peer-Reviewed Publication

ARIZONA STATE UNIVERSITY

Steel rusts by water and air on the Earth’s surface. But what about deep inside the Earth’s interior? 

The Earth’s core is the largest carbon storage on Earth – roughly 90% is buried there. Scientists have shown that the oceanic crust that sits on top of tectonic plates and falls into the interior, through subduction, contains hydrous minerals and can sometimes descend all the way to the core-mantle boundary. The temperature at the core-mantle boundary is at least twice as hot as lava, and high enough that water can be released from the hydrous minerals. Therefore, a chemical reaction similar to rusting steel could occur at Earth’s core-mantle boundary.

Byeongkwan Ko, a recent Arizona State University PhD graduate, and his collaborators published their findings on the core-mantle boundary in Geophysical Research Letters. They conducted experiments at the Advanced Photon Source at Argonne National Laboratory, where they compressed iron-carbon alloy and water together to the pressure and temperature expected at the Earth’s core-mantle boundary, melting the iron-carbon alloy. 

The researchers found that water and metal react and make iron oxides and iron hydroxides, just like what happens with rusting at Earth’s surface. However, they found that for the conditions of the core-mantle boundary carbon comes out of the liquid iron-metal alloy and forms diamond.

“Temperature at the boundary between the silicate mantle and the metallic core at 3,000 km depth reaches to roughly 7,000 F, which is sufficiently high for most minerals to lose H2O captured in their atomic scale structures,” said Dan Shim, professor at ASU’s School of Earth and Space Exploration. “In fact, the temperature is high enough that some minerals should melt at such conditions.”

Because carbon is an iron loving element, significant carbon is expected to exist in the core, while the mantle is thought to have relatively low carbon. However, scientists have found that much more carbon exists in the mantle than expected. 

“At the pressures expected for the Earth's core-mantle boundary, hydrogen alloying with iron metal liquid appears to reduce solubility of other light elements in the core,” said Shim. “Therefore, solubility of carbon, which likely exists in the Earth's core, decreases locally where hydrogen enters into the core from the mantle (through dehydration). The stable form of carbon at the pressure-temperature conditions of Earth's core-mantle boundary is diamond. So the carbon escaping from the liquid outer core would become diamond when it enters into the mantle.”

“Carbon is an essential element for life and plays an important role in many geological processes,” said Ko. “The new discovery of a carbon transfer mechanism from the core to the mantle will shed light on the understanding of the carbon cycle in the Earth’s deep interior. This is even more exciting given that the diamond formation at the core-mantle boundary might have been going on for billions of years since the initiation of subduction on the planet.”

Ko's new study shows that carbon leaking from the core into the mantle by this diamond formation process may supply enough carbon to explain the elevated carbon amounts in the mantle. Ko and his collaborators also predicted that diamond rich structures can exist at the core-mantle boundary and that seismic studies might detect the structures because seismic waves should travel unusually fast for the structures.

“The reason that seismic waves should propagate exceptionally fast through diamond-rich structures at the core-mantle boundary is because diamond is extremely incompressible and less dense than other materials at the core-mantle boundary,” said Shim.

Ko and team will continue investigating how the reaction can also change the concentration of other light elements in the core, such as silicon, sulfur and oxygen, and how such changes can impact the mineralogy of the deep mantle.

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Author: Andrea Chatwood, Communications Specialist, ASU The College of Liberal Arts and Sciences

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JOURNAL

Geophysical Research Letters

DOI

10.1029/2022GL098271 

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Water-induced diamond formation at Earth's core-mantle boundary