Unearthing the leaf miners of ancient times: 312-million-year-old fossil sheds light on insect behavior and evolution

Peer-Reviewed Publication

HARVARD UNIVERSITY, DEPARTMENT OF ORGANISMIC AND EVOLUTIONARY BIOLOGY

 

IMAGE: 

ENDOPHYTIC TRACES ON MACRONEUROPTERIS SCHEUCHZERI; (A) MCZ 198877A (PART) AND MAGNIFIED DETAILS OF THE ENDOPHYTIC STRUCTURE (B)-(H).

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CREDIT: RICHARD J. KNECHT

Insects are fragile, soft-bodied animals whose remains are difficult to preserve. Wings are often fossilized, but insect bodies, if present, are usually bits and pieces of the original prehistoric animal, making it difficult for scientists to study them. One way paleontologists learn about prehistoric insects is by trace fossils, which are almost exclusively found as traces on fossil plants.

“We have a great fossil plant record,” said Richard J. Knecht, Ph.D. candidate in the Department of Organismic and Evolutionary Biology at Harvard. “Further back in time, it’s the trace fossils that tell us more about the evolution and behavior of insects than the body fossils because plants and the trace fossils on them preserve very well. And the trace, as opposed to a body, won’t move over time and is always found where it was made.”

In a new study, published in New Phytologist, researchers, led by Knecht, describe an endophytic trace fossil found on a Carboniferous seed-fern leaf that represents the earliest indication of internal feeding within a leaf. The 312-million-year-old Carboniferous fossil provides evidence of how internal feeding, known as leaf mining, may have originated and shows the age of this behavior was occurring approximately 70 million years earlier than believed.

“Of all of the ways that insects feed internally within plants—the mining of the insides of leaves, the tumor-like galls in which an insect takes control of the developmental machinery of a plant, the borings and galleries of insects in wood, and myriad ways that insects invade seeds to consume nutritious embryonic tissues—it is mining that has been the most mysterious,” said co-author, Conrad C. Labandeira, Senior Research Geologist and Curator of Fossil Arthropods at the Smithsonian National Museum of Natural History. “The earliest mines are recorded from the Early Triassic, soon after the great end-Permian extinction, and yet galls, borings, and seed predation extend considerably earlier into the Paleozoic. Why the delay in mining? I think we now have an answer!”

Internal feeding on plants is common among holometabolous insects – insects that undergo a full metamorphosis: Lepidoptera (moths), Coleoptera (beetles), Diptera (flies) and Hymenopterans (wasps and sawflies). A larva bores into the leaf and begins to feed on the internal tissues of the leaf, leaving a trail behind. As the larva tunnels within the leaf, it is also growing, going through different stages of molting and even leaving behind it’s droppings, known as frass.

“Frass is one of the things we look for when we’re identifying internal feeding. Frass can even have different traits that are useful when it comes to defining what animal is making it,” Knecht said. The larva will continue to make a trail within the leaf until it pupates, hatches, cuts itself out of the leaf, and flies away.

The trace fossil was found in the Carboniferous Rhode Island Formation. The Rhode Island Formation was originally a swampy, water-logged environment which provided an anoxic setting that preserved plant fossils very well; what paleontologists call a Lagerstätte, a site that produces extraordinary fossils with exceptional preservation.

“One thing that doesn’t fossilize is larvae,” said Knecht. “They are too delicate and small. So seeing something like this is really insightful because it tells us about larval behavior at a specific time, the late Paleozoic, in which we know very little about larvae.”

The exceptional preservation allowed the researchers to clearly see the endophytic trace which follows patterns paleontologists look for when defining this behavior, For example a meandering trail, the larva will avoid the leaf’s edges and major veins. This behavior is only known to be performed by holometabolous insects, including animals existing today.

“This finding pushes this behavior back by 70 million years,” said Knecht. “It’s showing us two things, one the behavior of larvae, something we don’t see in the fossil record because larvae typically don’t preserve. And two, that the evolution of full metamorphosis, holometabolism, existed at this time.”

The fossil is housed in the Museum of Comparative Zoology at Harvard among other fossils Knecht is also studying.

 

(A) Major fossil evidence for insects and plant-insect associations are presented with labeled points, with special reference to holometabolous insect orders (Diptera, Hymenoptera, Lepidoptera and Coleoptera) and foliar endophytic damage. Genomic estimates of the origin of the major leaf mining orders are given in pink (Coleoptera), orange (Hymenoptera) and blue (Lepidoptera). (B) Fossil pinnule mines on Macroneuropteris scheuchzeri. (MCZ 198877a) from the Rhode Island Formation in Massachusetts, U.S.A.

CREDIT

Anshuman Swain

Backscatter and Energy dispersive spectrometry (EDS) results of SEM analysis using a JEOL 7900F SEM. (A) SEM backscatter microscopy image of portion of endophytic trace. Boxes (B-E) represent areas where element mapping was conducted. B1-E1 shows stacked images of all elements found within the relative focused areas. Individual element maps of areas B-E can be found in supplementary data. B2-E2 represent element maps of phosphorus (cyan color) found in boxes B-E.

CREDIT

Richard J. Knecht and Anshuman Swain

JOURNAL

New Phytologist

DOI

10.1111/nph.19266 

ARTICLE TITLE

Endophytic ancestors of modern leaf miners may have evolved in the Late Carboniferous

ARTICLE PUBLICATION DATE

6-Oct-2023

 

How the war in Ukraine is challenging two academic disciplines

Symposium on the relations between peace and conflict studies and East European studies

Meeting Announcement

BIELEFELD UNIVERSITY

 

IMAGE: 

THREE HISTORIANS FROM BIELEFELD UNIVERSITY (FROM LEFT), PROFESSOR DR. FRANK GRÜNER, PROFESSORIN DR. KORNELIA KOŃCZAL, AND DR. YAROSLAV ZHURAVLOV, ORGANISED THE SYMPOSIUM.

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CREDIT: PHOTOS (FROM LEFT): BIELEFELD UNIVERSITY, STEFAN SÄTTELE, SARAH JONEK

Since the beginning of Russia’s invasion of Ukraine, two academic disciplines have come to fore: peace and conflict studies and East European studies. Experts from both fields represent important voices in the public discourse. A symposium entitled ‘War and Peace in Ukraine: Reflecting, Studying and Engaging Across Disciplines” will be held from 12 until 13 October 2023 at Bielefeld University. It brings together experts from both fields in order to discuss the relationship between them and challenges of participating in a highly charged public debate revolving around the war. One of the guests will be the Nobel Peace Prize winner from Ukraine, Oleksandra Matviichuk.

For a good thirty years, peace and conflict studies and East European studies did not have much in common in Germany. ‘This changed dramatically with Russia’s attack on Ukraine,’ says Professor Dr Kornelia Kończal, a historian at Bielefeld University. She conceptualized the symposium in Bielefeld together with Dr Yaroslav Zhuravlov and Professor Dr Frank Grüner, two colleagues also from Bielefeld University. ‘Due to the increased public interest in Ukraine and its history, voices from both disciplines have become indispensable in the media,’ says Kończal. Ukrainian scholars, who have had to leave their country because of the war, are also shaping both fields of research and their interdisciplinary linkages.

Symposium participants will examine the shifting dynamics between peace and conflict studies and East European studies. Prominent figures in both disciplines will come together to discuss methodological approaches, controversies, intersections, and missed opportunities. A key question here is to what extent interest in Ukraine has changed in these academic fields over the past year and a half.
The symposium will also take a closer look at the public discourse on Ukraine in Germany. ‘The increasing scope of confrontation with the country’s issues – past and present – is not free of misconceptions and misunderstandings,’ says Yaroslav Zhuralov. The symposium will consider the challenges that arise when trying to bring academic expertise into a highly politicized debate – and the extent to which experts have succeeded in shaping the political and public discourse.

The symposium consists of two keynote lectures, four panel discussions, and a Q&A session. Historians of Ukraine, including Dr Fabian Baumann (University of Heidelberg), Professor Dr Guido Hausmann (Regensburg University), Professor Dr Ricarda Vulpius (University of Münster) and Dr Anna Veronika Wendland (Herder-Institute Marburg) will speak, along with Ukrainian authors and academics, including Jurko Prochasko (Ukrainian Academy of Sciences, Kyiv), Professor Dr Valeria Korablyova (Charles University, Prague, Czech Republic), Dr Viktoriya Sereda (Institute for Advanced Study, Berlin) and Dr Tatiana Zhurzhenko (Centre for East European and International Studies, Berlin).

The Ukrainian Nobel Peace Prize Laureate Oleksandra Matviichuk, from the Center for Civil Liberties, Kyiv, will also speak at the conference.

CREDIT

Center for Civil Liberties, Kyiv

The Q&A with Oleksandra Matviichuk, who heads the Center for Civil Liberties (CCL) in Kyiv and won the Nobel Peace Prize in 2022, promises to be a highlight of the symposium program.
The event is being organised by Professor Dr Kornelia Kończal, Professor Dr Frank Grüner and Dr Yaroslav Zhuravlov (all historians at Bielefeld University), together with Dr Franziska Davies (Ludwig Maximilian University of Munich), Professor Dr Gelinada Grinchenko (University of Wuppertal) and Dr Nataliia Sinkevych (Leibniz Institute for the History and Culture of Eastern Europe (GWZO), Leipzig). They are holding the conference in cooperation with the German-Ukrainian Historical Commission, the German Foundation for Peace Research, the Institute for Interdisciplinary Research on Conflict and Violence at Bielefeld University, and the German Association for East European Studies.

The symposium will be held in English in Building X (Room X A2-103) on site at Bielefeld University, and will also be offered as a hybrid event, with the opportunity to participate via Livestream. To register for the event – both in person and online – please sign up by 10 October via email (war-and-peace@uni-bielefeld.de). 

Members of the press will have the opportunity to speak with Gelinada Grinchenko, Frank Grüner, Kornelia Kończal and Yaroslav Zhuravlov about the issues and topics to be addressed in the symposium right before the start of the event on Thursday, 12 October, beginning at 2:30 pm. Please sign up by 11 October at war-and-peace@uni-bielefeld.de.

 

Economic Development and Cultural Change announces new Editor in Chief

Business Announcement

UNIVERSITY OF CHICAGO PRESS JOURNALS

On November 1, 2023, Prashant Bhadarwaj will succeed Marcel Fafchamps as Editor in Chief of Economic Development and Cultural Change (EDCC). Bhadarwaj is Professor of Economics and Vice Chair of Graduate Studies at the University of California San Diego (UCSD).

“In addition to his economic expertise,” says Fafchamps, “Prashant brings to the journal considerable editorial expertise, having served as editor for several leading journals and, importantly, having been Associate Editor for EDCC in the past. This makes him perfectly well prepared for the job at hand.”

Bhadarwaj’s research affiliations include the Bureau for Research and Economic Analysis of Development, the Center for Effective Global Action, the Centre for Economic Research in Pakistan, and the National Bureau of Economic Research. He’s served as an editor at the Journal of Human Resources and as an associate editor for Economic Development and Cultural Change, the Journal of Development Economics, and the Journal of Health Economics. He is also Co-Director of the South Asian Studies minor program at UCSD. 

Marcel Fafchamps steps down after ten years at the helm of Economic Development and Cultural Change. During his tenure as Editor in Chief, the journal has nearly doubled the amount of content published in each volume while maintaining its quality and rankings. According to David McKenzie’s annual blog on development economics journals, EDCC offers faster reviews and publishes more articles by non-OECD authors than similar titles. Economic Development and Cultural Change is a quarterly journal published by the University of Chicago Press.

EDCC publishes studies that use modern theoretical and empirical approaches to examine both the determinants and the effects of various dimensions of economic development and cultural change.

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JOURNAL

Economic Development and Cultural Change

 

Study confirms age of oldest fossil human footprints in North America

Two new lines of evidence support the 21,000 to 23,000-year age estimate of the footprints first described and dated in 2021

Peer-Reviewed Publication

U.S. GEOLOGICAL SURVEY

 

IMAGE: 

FOSSILIZED FOOTPRINTS IN WHITE SANDS NATIONAL PARK.

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CREDIT: USGS, NPS, BOURNEMOUTH UNIVERSITY

The 2021 results began a global conversation that sparked public imagination and incited dissenting commentary throughout the scientific community as to the accuracy of the ages. 

  

“The immediate reaction in some circles of the archeological community was that the accuracy of our dating was insufficient to make the extraordinary claim that humans were present in North America during the Last Glacial Maximum. But our targeted methodology in this current research really paid off,” said Jeff Pigati, USGS research geologist and co-lead author of a newly published study that confirms the age of the White Sands footprints. 

  

The controversy centered on the accuracy of the original ages, which were obtained by radiocarbon dating. The age of the White Sands footprints was initially determined by dating seeds of the common aquatic plant  Ruppia cirrhosa that were found in the fossilized impressions. But aquatic plants can acquire carbon from dissolved carbon atoms in the water rather than ambient air, which can potentially cause the measured ages to be too old. 

  

“Even as the original work was being published, we were forging ahead to test our results with multiple lines of evidence,” said Kathleen Springer, USGS research geologist and co-lead author on the current Science paper. “We were confident in our original ages, as well as the strong geologic, hydrologic, and stratigraphic evidence, but we knew that independent chronologic control was critical.” 

  

For their follow-up study, the researchers focused on radiocarbon dating of conifer pollen, because it comes from terrestrial plants and therefore avoids potential issues that arise when dating aquatic plants like Ruppia. The researchers used painstaking procedures to isolate approximately 75,000 pollen grains for each sample they dated. Importantly, the pollen samples were collected from the exact same layers as the original seeds, so a direct comparison could be made. In each case, the pollen age was statistically identical to the corresponding seed age. 

 

“Pollen samples also helped us understand the broader environmental context at the time the footprints were made,” said David Wahl, USGS research geographer and a co-author on the current Science article. “The pollen in the samples came from plants typically found in cold and wet glacial conditions, in stark contrast with pollen from the modern playa which reflects the desert vegetation found there today.” 

  

In addition to the pollen samples, the team used a different type of dating called optically stimulated luminescence, which dates the last time quartz grains were exposed to sunlight. Using this method, they found that quartz samples collected within the footprint-bearing layers had a minimum age of ~21,500 years, providing further support to the radiocarbon results. 

 

With three separate lines of evidence pointing to the same approximate age, it is highly unlikely that they are all incorrect or biased and, taken together, provide strong support for the 21,000 to 23,000-year age range for the footprints. 

  

The research team included scientists from the USGS, Lawrence Livermore National Laboratory, the National Park Service, and academic institutions. Their continued studies at White Sands focus on the environmental conditions that allowed people to thrive in southern New Mexico during the Last Glacial Maximum and are supported by the Climate Research and Development Program | U.S. Geological Survey (usgs.gov) and  USGS-NPS Natural Resources Protection Program. 

Footprints at the base of trench in White Sands National Park.

CREDIT

USGS

Prints at base of trench, White Sands National Park.

CREDIT

USGS

The USGS provides science for a changing world. Learn more at www.usgs.gov or follow us on Facebook @USGeologicalSurvey, YouTube @USGS, Instagram @USGS, or Twitter @USGS.  

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JOURNAL

Science

METHOD OF RESEARCH

Data/statistical analysis

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Independent age estimates resolve the controversy of ancient human footprints at White Sands

ARTICLE PUBLICATION DATE

6-Oct-2023

New, independent ages confirm antiquity of ancient human footprints at White Sands

Peer-Reviewed Publication

AMERICAN ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE (AAAS)

New radiocarbon (14C) and optically simulated luminescence ages have confirmed the controversial antiquity of the ancient human footprints discovered in White Sands National Park, and reported in a study in 2021. Addressing the widespread criticism of their previous study, researchers report that the independent ages from multiple resolved sources conclusively show that the footprints were left behind between roughly 23,000 and 20,000 years ago, demonstrating that humans were present in southern North America during the Last Glacial Maximum (LGM).

When and how humans first migrated into North America has long been debated and remains poorly understood. Current estimates for the timing of these first occupants range from ~13,000 years ago to more than 20,000 years ago. However, the earliest archaeological evidence for the region’s settlement is sparse and often controversial. In a Science study published in September 2021 (Bennett et al.), researchers reported the discovery of in situ human footprints preserved in an ancient lakebed dating to between ~23,000 and 21,000 years ago in what is now White Sands National Park – findings which suggest nearly 2,000 years of human occupation in North America during the height of the LGM. However, since the study’s publication, the accuracy of the radiocarbon dates has been debated. It’s argued that the ancient seeds from the aquatic plant (Ruppia cirrhosa) that were used to date the surfaces the footprints were embedded in have the potential to be affected by old carbon reservoir effects that could influence the reported radiocarbon ages and make them appear older than they truly are.

Here, Jeffery Pigati, Kathleen Springer, and colleagues report new evidence in the form of multiple independent age estimates of the White Sands footprints, which support their previous study’s claims. “We always knew that we would have to independently evaluate the accuracy of our ages to convince the archaeological community that the peopling of the Americas occurred far earlier than traditionally thought,” said Pigati.

In their new work, Pigati and Springer et al. present calibrated 14C ages of terrestrial pollen collected from the same stratigraphic contexts as the Ruppia seeds. Unlike the seeds, conifer pollen fixes atmospheric carbon and, therefore is not subject to potential old carbon reservoir effects. According to the findings, the resulting calibrated 14C ages range from 23.4 ± 2.5 – 22.6 ± 2.3 thousand years ago. In addition, the authors obtained optically simulated luminescence ages of the sediments from within the footprint-bearing strata, which produced a minimum age of 21.5 ± 1.9 thousand years ago. In both cases, Pigati and Springer et al. show that the resolved dates were statistically indistinguishable from the original calibrated 14C ages of the oldest Ruppia seeds reported previously. In a related Perspective, Bente Phillipson discusses the study and its findings in greater detail.  

“Even as the original work was being published, we were forging ahead to test our results with multiple lines of evidence and independent chronologic techniques,” said Kathleen Springer, co-lead author of the study. “Although we were confident in the original seed ages, we wanted to develop community confidence in them as well. Our new ages, combined with the strong geologic, hydrologic, and stratigraphic evidence, unequivocally support the conclusion that humans were present in North America during the last Glacial Maximum.”

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JOURNAL

Science

DOI

10.1126/science.adh5007 

ARTICLE TITLE

Independent age estimates resolve the controversy of ancient human footprints at White Sands

ARTICLE PUBLICATION DATE

6-Oct-2023

 

More than 10,000 pre-Columbian earthworks remain hidden throughout Amazonian forests

Peer-Reviewed Publication

AMERICAN ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE (AAAS)

More than 10,000 Pre-Columbian archaeological sites likely rest undiscovered throughout the Amazon basin, estimates a new study. The findings, derived from remote sensing data and predictive spatial modeling, address questions about the influence of pre-Columbian societies on the Amazon region. “The massive extent of archaeological sites and widespread human-modified forests across Amazonia is critically important for establishing an accurate understanding of interactions between human societies, Amazonian forests, and Earth’s climate,” write the authors. Indigenous societies have called the Amazon basin home for more than 12,000 years, creating ancient earthwork structures and domesticated landscapes that have had long-lasting effects on modern forest composition. However, the size and scale of Amazon settlement and landscape transformation are poorly understood – sites are remote and often obscured by dense vegetation. As such, there has never been a comprehensive survey of pre-Columbian sites across the Amazon basin. Airborne LIDAR (light detection and ranging), a remote sensing technique that can map small changes in topography on the ground surface beneath the forest canopy, has been used to discover many previously unknown pre-Columbian structures and earthworks in heavily forested sites throughout Central and South America. Here, Vinicius Peripato and colleagues searched 5,315 square kilometers of LIDAR survey data and discovered 24 unreported human-made earthworks, including fortified villages, defensive and ceremonial structures, mountaintop settlements, and other geoglyphs, in regions across the Amazon basin. However, the LIDAR survey data covered only 0.08% of the total area of Amazonia. To better understand where and how many undocumented pre-Columbian sites might occur, Peripato et al. combined the data from their small basin-wide survey, as well as data on other previously identified sites with a predictive spatial distribution model. According to the model, between 10,272 and 23,648 large-scale pre-Columbian structures remain to be discovered, particularly in southwestern Amazonia. What’s more, the authors identified relationships between the predicted probability of earthworks and the occurrence and abundance of domesticated tree species and found significant association between the two, suggesting that active pre-Columbian Indigenous forest management practices have long shaped the ecology of modern forests across Amazonia. “Amazonian forests clearly merit protection not only for their ecological and environmental value but also for their high archaeological, social, and biocultural value, which can teach modern society how to sustainably manage its natural resources,” write Peripato et al.

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JOURNAL

Science

DOI

10.1126/science.ade2541 

ARTICLE TITLE

Over 10,000 Pre-Columbian earthworks are still hidden throughout Amazonia

ARTICLE PUBLICATION DATE

6-Oct-2023

 

Special Issue: Ancient DNA

Reports and Proceedings

AMERICAN ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE (AAAS)

In this Special Issue of Science, three Reviews highlight how recent advances in the field of ancient DNA have greatly advanced our understanding of the evolutionary history of many plants and animals, including our own species. “This special issue examines the changing landscape of how ancient DNA (aDNA) is studied today, including previously untapped sources, improvements in technology, and ethical challenges, and what we’ve learned about ourselves though ancient DNA,” write Corinne Simonti and Madeleine Seale, associate editors at Science.

In one Review, María Ávila-Arcos and colleagues discuss the significance of aDNA in addressing non-European regional questions. According to the authors, much of the early human aDNA research was focused on large-scale events, such as continental-scale population migrations or genetic admixture events, with an overrepresentation of European-focused studies. However, many regional questions, particularly those relevant to the Global South, remain underexplored. By reviewing several recent paleogenomics studies that have been successful in highlighting local histories and health in the Americas, Africa, Asia, and Oceana, particularly that of the Indigenous and Descendant communities that live there, Ávila-Arcos et al. underscore the importance of bringing a regional perspective to aDNA research. They further explore the ethical considerations as the field shifts towards answering finer-scale questions. When done correctly, finer-scale aDNA investigations can be a powerful tool with the potential to integrate neglected or oppressed communities and to uncover past histories that have been lost or erased from history.

Another Review, by Hernán Burbano and Rafal Gutaker, discusses the use of aDNA from herbarium specimens – historically collected and preserved plant samples – to provide glimpses into past plant communities. Such insight can provide a better understanding of the evolutionary and ecological processes that shape plants over time and could help inform new conservation efforts. In a third Review, Beth Shapiro and colleagues explore the state-of-the-art in paleogenomics techniques and discuss the key challenges that remain, including technical limitations that impede the ability to evaluate “deep-time” ancient DNA.

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JOURNAL

Science

DOI

10.1126/science.adk9651 

ARTICLE TITLE

Glimpses of genomes past

ARTICLE PUBLICATION DATE

6-Oct-2023

 

What are the risks of radioactive wastewater release – the next of which is October 5th – from Fukushima Daiichi nuclear plant?

Reports and Proceedings

AMERICAN ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE (AAAS)

Wastewater release from the Fukushima Daiichi nuclear plant in Japan is expected to have negligible effects on people and the ocean, Jim Smith and colleagues report in a Perspective. The planned releases of radioactive wastewater, 350 million gallons of which has been stored at the site since the 2011 earthquake and tsunami that triggered the Fukushima plant’s meltdown, began in August 2023 and are expected to continue for perhaps the next 30 years. The second release is scheduled to start on October 5th. While the scheduled releases have sparked international concern, Smith et al. discuss the science behind the risks and show that the amounts of radiation in the planned discharges are being kept well below radiation safety limits and are less than those in existing wastewater releases that are standard practice from other nuclear facilities worldwide. Moreover, the predicted annual radiation doses from the Fukushima releases to local seafood consumers are magnitudes smaller than exposure to natural radiation or other common radiation sources, like medical x-rays or long-distance commercial flights. Smith et al. also review research on the effect of radioactive pollution on marine ecosystems. Studies in lakes near Chernobyl – which host radiation dose rates more than 1000 times higher than those expected from Fukushima discharges – show that aquatic ecosystems are surprisingly resilient to radioactive pollution. “The radiation protection science is clear that the Fukushima wastewater release presents no real threat to the organisms of the Pacific Ocean or to Fukushima’s seafood consumers if carried out as planned,” write the authors.

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JOURNAL

Science

DOI

10.1126/science.adi5446 

ARTICLE TITLE

The risks of radioactive wastewater release

ARTICLE PUBLICATION DATE

6-Oct-2023

SYNGAS REDUX

Discovery made about Fischer Tropsch process could help improve fuel production

Peer-Reviewed Publication

WASHINGTON STATE UNIVERSITY

A fundamental discovery about the Fischer Tropsch process, a catalytic reaction used in industry to convert coal, natural gas or biomass to liquid fuels, could someday allow for more efficient fuel production.

Washington State University researchers discovered previously unknown self-sustained oscillations in the Fischer Tropsch process. They found that unlike many catalytic reactions which have one steady state, this reaction periodically moves back and forth from a high to a low activity state. The discovery, reported in Science, means that these well-controlled oscillatory states might be used in the future to enhance the reaction rate and the yields of desired products.

“Usually, rate oscillations with large variations in temperature are unwanted in chemical industry because of safety concerns,” said corresponding author Norbert Kruse, Voiland Distinguished Professor in WSU’s Gene and Linda Voiland School of Chemical Engineering and Bioengineering. “In the present case, oscillations are under control and mechanistically well understood. With such a basis of understanding, both experimentally and theoretically, the approach in research and development can be completely different – you really have a knowledge-based approach, and this will help us enormously.”

Although the Fischer Tropsch process is commonly used for fuel and chemical production, researchers have had little understanding of how the complex catalytic conversion process works. The process uses a catalyst to convert two simple molecules, hydrogen and carbon monoxide, into long chains of molecules – the hydrocarbons that are used widely in daily life.

While a trial-and-error approach has been used in research and development in the fuels and chemical industries for more than a century, researchers will now be able to design catalysts more intentionally and tune the reaction to provoke oscillatory states that could improve the catalytic performance.

The researchers first came upon the oscillations by accident after graduate student Rui Zhang approached Kruse with a problem: he wasn’t able to stabilize the temperature in his reaction. As they studied it together, they discovered the surprising oscillations.

“That was pretty funny,” Kruse said. “He showed it to me, and I said, ‘Rui, congratulations, you have oscillations! And then we developed this story more and more.”

The researchers not only discovered that the reaction develops oscillatory reaction states, but why it does so. That is, as the temperature of the reaction goes up due to its heat production, the reactant gases lose contact with the catalyst surface and their reaction slows down, which reduces the temperature. Once the temperature is sufficiently low, the concentration of the reactant gases on the catalyst surface increases and the reaction picks up speed again. Consequently, the temperature increases to close the cycle.

For the study, the researchers demonstrated the reaction in a lab employing a frequently used cobalt catalyst, conditioned by adding cerium oxide, and then modeled how it worked. Co-author Pierre Gaspard at the Université Libre de Bruxelles developed a reaction scheme and theoretically imposed periodically changing temperatures to replicate the experimental rates and selectivities of the reaction.

“It’s so beautiful that we were able to model that theoretically,” said corresponding author Yong Wang, Regents Professor in WSU’s Voiland School who also co-advised Zhang. “The theoretical and the experimental data nearly coincided.”

Kruse has been working on oscillatory reactions for more than 30 years. The discovery of the oscillatory behavior with the Fischer Tropsch reaction was very surprising because the reaction is mechanistically extremely complicated.

“We have a lot of frustration sometimes in our research because things are not going the way you think they should, but then there are moments that you cannot describe,’’ Kruse said. “It's so rewarding, but ‘rewarding’ is a weak expression for the excitement of having had this fantastic breakthrough.”

The work was supported by the Chambroad Chemical Industry Research Institute Co., Ltd., the National Science Foundation and the Department of Energy’s Basic Energy Sciences Catalysis Science program.

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JOURNAL

Science

DOI

10.1126/science.adh8463 

ARTICLE TITLE

The oscillating Fischer-Tropsch reaction

ARTICLE PUBLICATION DATE

5-Oct-2023