Science
Separating out signals recorded at the seafloor
Roger Bryant and David Fike’s research reveals that pyrite sulfur isotopes mainly reflect local conditions, shifting fundamental understanding of oceanic environmental studies.
Last Updated on November 1, 2024 by Daily News Staff
Roger Bryant studied ocean floor core samples at the Secondary Ion Mass Spectrometry (SIMS) facility at Washington University in St. Louis during his PhD studies. Bryant and David Fike have used this data to prove a discovery that will fundamentally change how scientists use pyrite sulfur isotopes to study oceanic conditions.
« Separating out signals recorded at the seafloor
Newswise — Blame it on plate tectonics. The deep ocean is never preserved, but instead is lost to time as the seafloor is subducted. Geologists are mostly left with shallower rocks from closer to the shoreline to inform their studies of Earth history.
Signals from the Sea
“We have only a good record of the deep ocean for the last ~180 million years,” said David Fike, the Glassberg/Greensfelder Distinguished University Professor of Earth, Environmental, and Planetary Sciences in Arts & Sciences at Washington University in St. Louis. “Everything else is just shallow-water deposits. So it’s really important to understand the bias that might be present when we look at shallow-water deposits.”
One of the ways that scientists like Fike use deposits from the seafloor is to reconstruct timelines of past ecological and environmental change. Researchers are keenly interested in how and when oxygen began to build up in the oceans and atmosphere, making Earth more hospitable to life as we know it.
For decades they have relied on pyrite, the iron-sulfide mineral known as “fool’s gold,” as a sensitive recorder of conditions in the marine environment where it is formed. By measuring the bulk isotopic composition of sulfur in pyrite samples — the relative abundance of sulfur atoms with slightly different mass — scientists have tried to better understand ancient microbial activity and interpret global chemical cycles.
But the outlook for pyrite is not so shiny anymore. In a pair of companion papers published Nov. 24 in the journal Science, Fike and his collaborators show that variations in pyrite sulfur isotopes may not represent the global processes that have made them such popular targets of analysis.
Instead, Fike’s research demonstrates that pyritte responds predominantly to local processes that should not be taken as representative of the whole ocean. A new microanalysis approach developed at Washington University helped the researchers to separate out signals in pyrite that reveal the relative influence of microbes and that of local climate.
For the first study, Fike worked with Roger Bryant, who completed his graduate studies at Washington University, to examine the grain-level distribution of pyrite sulfur isotope compositions in a sample of recent glacial-interglacial sediments. They developed and used a cutting-edge analytical technique with the secondary-ion mass spectrometer (SIMS) in Fike’s laboratory.
“We analyzed every individual pyrite crystal that we could find and got isotopic values for each one,” Fike said. By considering the distribution of results from individual grains, rather than the average (or bulk) results, the scientists showed that it is possible to tease apart the role of the physical properties of the depositional environment, like the sedimentation rate and the porosity of the sediments, from the microbial activity in the seabed.
“We found that even when bulk pyrite sulfur isotopes changed a lot between glacials and interglacials, the minima of our single grain pyrite distributions remained broadly constant,” Bryant said. “This told us that microbial activity did not drive the changes in bulk pyrite sulfur isotopes and refuted one of our major hypotheses.”
“Using this framework, we’re able to go in and look at the separate roles of microbes and sediments in driving the signals,” Fike said. “That to me represents a huge step forward in being able to interpret what is recorded in these signals.”
In the second paper, led by Itay Halevy of the Weizmann Institute of Science and co-authored by Fike and Bryant, the scientists developed and explored a computer model of marine sediments, complete with mathematical representations of the microorganisms that degrade organic matter and turn sulfate into sulfide and the processes that trap that sulfide in pyrite.
“We found that variations in the isotopic composition of pyrite are mostly a function of the depositional environment in which the pyrite formed,” Halevy said. The new model shows that a range of parameters of the sedimentary environment affect the balance between sulfate and sulfide consumption and resupply, and that this balance is the major determinant of the sulfur isotope composition of pyrite.
“The rate of sediment deposition on the seafloor, the proportion of organic matter in that sediment, the proportion of reactive iron particles, the density of packing of the sediment as it settles to the seafloor — all of these properties affect the isotopic composition of pyrite in ways that we can now understand,” he said.
Importantly, none of these properties of the sedimentary environment are strongly linked to the global sulfur cycle, to the oxidation state of the global ocean, or essentially any other property that researchers have traditionally used pyrite sulfur isotopes to reconstruct, the scientists said.
“The really exciting aspect of this new work is that it gives us a predictive model for how we think other pyrite records should behave,” Fike said. “For example, if we can interpret other records — and better understand that they are driven by things like local changes in sedimentation, rather than global parameters about ocean oxygen state or microbial activity — then we can try to use this data to refine our understanding of sea level change in the past.”
Source: Washington University in St. Louis
The science section of our news blog STM Daily News provides readers with captivating and up-to-date information on the latest scientific discoveries, breakthroughs, and innovations across various fields. We offer engaging and accessible content, ensuring that readers with different levels of scientific knowledge can stay informed. Whether it’s exploring advancements in medicine, astronomy, technology, or environmental sciences, our science section strives to shed light on the intriguing world of scientific exploration and its profound impact on our daily lives. From thought-provoking articles to informative interviews with experts in the field, STM Daily News Science offers a harmonious blend of factual reporting, analysis, and exploration, making it a go-to source for science enthusiasts and curious minds alike. https://stmdailynews.com/category/science/
The Earth
Cement has a climate problem — here’s how geopolymers with add‑ins like cork could help fix it
Portland cement drives ~8% of global emissions. Learn how low-carbon geopolymers—enhanced with add-ins like cork—could cut concrete’s footprint.
Alcina Johnson Sudagar, Washington University in St. Louis
Concrete is all around you – in the foundation of your home, the bridges you drive over, the sidewalks and buildings of cities. It is often described as the second-most used material by volume on Earth after water.
But the way concrete is made today also makes it a major contributor to climate change.
Portland cement, the key component of concrete, is responsible for about 8% of global greenhouse gas emissions. That’s because it’s made by heating limestone to high temperatures, a process that burns a large amount of fossil fuels for energy and releases carbon dioxide from the limestone in the process.
The good news is that there are alternatives, and they are gaining attention.
Portland cement: A greenhouse gas problem
Cementlike substances have been used in construction for thousands of years. Architects have found evidence of their use in the pyramids of Egypt and the buildings and aqueducts of the Roman Empire.
The Portland cement commonly used in construction today was patented in 1824 by Joseph Aspdin, a British bricklayer.
Modern cement preparation starts with crushing the excavated raw materials limestone and clay and then heating them in a kiln at around 2,650 degrees Fahrenheit (about 1,450 degrees Celsius) to form clinker, a hard, rocklike residue. The clinker is then cooled and ground with gypsum into a fine powder, which is called cement.
About 40% of the carbon dioxide emissions from cement production come from burning fossil fuels to generate the high heat needed to run the kiln. The rest come as the heat converts limestone (calcium carbonate) to lime (calcium oxide), releasing carbon dioxide.
In all, between half a ton and 1 ton of greenhouse gas is released per ton of Portland cement. Cement is a binding agent that, mixed with water, holds aggregate together to create concrete. It makes up about 10% to 15% of the concrete mix by weight.
Alternative technologies can lower emissions
As populations, cities and the need for new infrastructure expand, the use of cement is growing, making it important to find alternatives with lower environmental costs.
Some techniques for reducing carbon dioxide emissions include substituting some of the clinker – the hard residue typically made from limestone – with supplementary materials such as clay, or fly ash and slag from industries. Other methods reduce the amount of cement by mixing in waste sawdust or recycled materials like plastics.
The long-term solution for reducing cement’s emissions, however, is to replace traditional cement completely with alternatives. One option is geopolymers made from earthen clay and industrial wastes.
Geopolymers: A more climate-friendly solution
Geopolymers can be made by mixing claylike materials that are rich in aluminum and silicon minerals with a chemical activator through a process called geopolymerization. The activator transforms the silicon and aluminum into a structure that will look like cement. All of this can happen at room temperature.
The major difference between cement and geopolymer is that cement is mainly made of calcium, whereas geopolymers are made of silicon and aluminum with some possible calcium in their structure.
These geopolymers have been found to possess high strength and durability, including resilience in freeze-thaw cycles and resistance to heat and fire, which are important requirements in construction. Studies have found that some geopolymers can provide comparable if not better strength than traditional cement and, because they don’t require heat the way clinker does, they can be produced with significantly lower greenhouse gas emissions.
Geopolymers can also be produced from a variety of raw materials rich in aluminum and silicon, including earthen clays, fly ash, blast furnace slag, rice husk ash, iron ore wastes and recycled construction brick waste. Geopolymer technology can be adapted depending on the clay or industrial waste locally available in a region. https://www.youtube.com/embed/NOj3p6m9M7Q?wmode=transparent&start=0 A brief history of cement and geopolymers. Geopolymer International.
An added advantage of geopolymers is that changes to the mixture can produce a range of features.
For example, I and my co-researchers at the University of Aveiro in Portugal added a small amount of cork industry waste – the leftovers from creating bottle corks – to clay-based geopolymer and found it could improve the strength of the material by up to twofold. The cork particles filled the spaces in the geopolymer structure, making it denser, which increased the strength.
Similarly, additives such as sisal fibers from the agave plant, recycled plastic and steel fibers can change geopolymer properties. The additives do not participate in the geopolymerization process but act as fillers in the structure.
The structure of geopolymers can also be designed to act as adsorbents, attracting toxic metals in wastewater and capturing and storing radioactive wastes. Specifically, incorporating materials like zeolite that are natural adsorbents in the geopolymer structure can make them useful for such applications as well.
Where geopolymers are used now
Geopolymers have been used in many types of construction, including roads, coatings, 3D printing, coastal environmental protection, the steel and chemical industries, sewer rehabilitation and building radiation shielding and rocket launchpad and bunker infrastructure.
One of the earliest examples of a modern geopolymer concrete project was the Brisbane West Wellcamp airport in Australia.
It was built in 2014 with 70,000 metric tons of geopolymer concrete, which was estimated to have reduced the project’s carbon dioxide emissions by as much as 80%.
The geopolymer market is currently estimated to be between US$7 billion and $10 billion, with the largest growth in the Asia-Pacific region.
Analysts have estimated that the market could grow at a rate of 10% to 20% per year and reach about $62 billion by 2033.
In several countries, greenhouse gas regulations and green-building certifications are expected to support the continued growth of geopolymers in the construction industry.
Expanding the use of cement alternatives
The advantage of using industrial wastes in geopolymers is a double-edged sword, however. The composition of industrial wastes varies, so it can be difficult to standardize the processing methods. The geopolymer components need to be mixed in particular ratios to achieve desired properties.
Producing the activator for the geopolymer, typically done in chemical facilities, can raise the cost and contribute to the carbon footprint. And the long-term data about these materials’ stability is only now being developed given their newness. Also, these geopolymers can take longer to set than cement, though the setting time can be sped up by using raw materials that react quickly.
Developing cheaper, naturally available activators like agricultural waste rice husk with sustainable supply chains could help lower the costs and environmental impact. Also, printing the recipe on the raw material packaging could help simplify the job of determining the mixing ratio so geopolymers can be more widely used with confidence.
Even though geopolymer technology has some drawbacks, these low-carbon alternatives have great potential for reducing emissions from the construction sector.
Alcina Johnson Sudagar, Research Scientist in Chemistry, Washington University in St. Louis
This article is republished from The Conversation under a Creative Commons license. Read the original article.
📰 Enjoying STM Daily News? Join the conversation!
💬 Leave a comment, share your thoughts, and subscribe to our newsletter for the latest stories, updates, and “News You Can Use This Moment!” delivered to your inbox.
Stay connected with STM Daily News!
Science
Sonic booms from meteors can release the energy of hundreds of tons of TNT – here’s how they work
Shawn Laatsch, University of Maine
Sonic booms from meteors can release the energy of hundreds of tons of TNT – here’s how they work
As humans, we live out our lives on a planet that is constantly sweeping through a cosmic ocean littered with ancient debris from the formation of the solar system. For the most part, our world glides silently through space, shielded by Earth’s thin atmosphere.
Occasionally, however, the rest of the universe reminds us of its presence with stunning, visceral clarity.
Residents along the Massachusetts–New Hampshire border were startled by a sudden sonic boom on the afternoon of May 30, 2026. A large number of people up and down the Eastern Seaboard witnessed it.
After NASA analyzed imagery from weather satellites, they identified the culprit as a small meteor measuring roughly 3 to 5 feet (1 to 2 meters) across. It was screaming through space at an astonishing 42,000 miles per hour (68,000 kilometers per hour) when it plunged into Earth’s upper atmosphere.
Friction between the meteor and the increasingly dense air quickly turned the kinetic energy of the rock shooting through the sky into blistering heat. At an altitude of roughly 40 miles (60 kilometers), the immense heat and pressure overcame the structural integrity of the meteor, causing it to fragment in a brilliant flash.
The breakup released a staggering burst of energy equivalent to 300 tons of TNT. When an object travels through the air at speeds faster than sound, which is 761 mph (1,225 kph), it creates a shock wave creating a thunderous clap, or sonic boom. While the majority of the rock vaporized, the remaining fragments rained down harmlessly into the waters of Cape Cod Bay.
In the past, such an event might have passed as an unverified sighting in the daytime sky. Today, however, our planet is wired with an accidental network of planetary defense sensors: dashboard cameras, security systems and digital doorbells.
Because meteor entries like this one last only a few fleeting seconds, they were easily missed in the past. Now, our collective digital eyes capture these spontaneous cosmic intrusions almost instantly, bringing the universe directly into our daily news feeds. While dramatic, these events are more common than most people imagine.
As someone who has worked as a planetarium director and astronomy educator for over four decades, I often get emails, social media messages and phone calls about such objects and sightings. While hearing a sonic boom can be a bit unsettling or even shocking, it reminds us we live in an active universe and may want to occasionally look up instead of down at our devices.
A meteoric spring
The Cape Cod fireball was the latest sighting in an active season of meteoritic arrivals. Just months earlier, the solar system seemed to be sending a parade of rocky objects down to Earth.
From March 8-11, observers in Northern Europe witnessed large, slow-moving fireballs in their skies. Enthusiasts and scientists successfully recovered several fragments. Lab analysis of these specimens revealed their place in a fascinating lineage – scientists determined that they had originated from Vesta, a massive, pristine asteroid orbiting between Mars and Jupiter.
On March 17, a 7-ton asteroid measuring roughly 6 feet across entered the atmosphere directly over Lake Erie. Traveling at 45,000 mph (72,400 kph), it generated a brilliant daytime flash and a powerful sonic boom, unloading an energy equivalent to 250 tons of TNT. NASA scientists published data about its trajectory, allowing meteorite hunters to recover pristine fragments in Valley City, just a short drive from Cleveland, Ohio.
Only four days later, on March 21, another cosmic fragment blazed across the skies of Texas. This object was about 3 feet wide, and it traveled at 35,000 mph (56,300 kph), releasing the energy of roughly 26 tons of TNT.
Outside of Houston, homeowner Sherri James was startled by a sudden crash, only to discover a 6-inch (15-cm) hole in her roof and a small piece of the solar system resting on her floor.
Thank goodness for Earth’s atmospheric shield
The benchmark for modern atmospheric impacts is the Chelyabinsk meteor, which exploded over Russia on Feb. 15, 2013.
That object was significantly larger than any of the meteors researchers have observed in 2026, measuring 60 feet (18 m) across and weighing roughly 10,000 tons. When it shattered 18 miles (29 km) above the ground, it produced an airburst with an explosive force 30 times greater than the Hiroshima atomic bomb.
The resulting shock wave shattered glass across hundreds of square miles, injuring nearly 1,500 people and registering as a seismic event between 2.7 and 3.7 on the Richter scale. The incident was a stark reminder that while Earth’s atmosphere is an incredibly effective shield, absorbing the lion’s share of cosmic impacts, a large enough kinetic punch can still reach the surface below.
Despite the dramatic stories around these meteor impacts, history shows that the cosmic lottery rarely targets humans directly. In all of recorded history, there is only one universally confirmed case of a person being directly struck by a space rock.
In 1954, an 8.5-pound (3.8 kg) meteorite crashed through the roof of a house in Sylacauga, Alabama, ricocheted off a heavy wooden radio and struck a sleeping woman named Ann Hodges. Though it left a severe bruise on her hip, the radio absorbed the brunt of the impact. Had it not been for the radio, there is a chance she could have been seriously injured or killed by this object.
Living with the cosmos
So, are you in any imminent danger from meteors? The mathematics of the cosmos provide profound reassurance. The statistical odds of being struck by a meteorite are vanishingly small. You stand a better chance of winning a multimillion-dollar lottery jackpot 10 times in a row than ever being hit by a meteorite.
The vast majority of the tons of space debris that bombard Earth daily arrive as harmless dust grains, burning up as elegant meteors or shooting stars. But when the larger pieces do break through and land on our planet, they offer a rare, tangible connection to the beginning of the solar system.
If you ever happen to witness one of these magnificent fireballs ripping open the sky, consider reporting your observation to the American Meteor Society. The organization keeps track of sightings and falls from around the globe. Recovered fragments provide a way for scientists to gain valuable information about the origin of our solar system, and of our home planet.
Shawn Laatsch, Director of the Versant Power Astronomy Center, University of Maine
This article is republished from The Conversation under a Creative Commons license. Read the original article.
📰 Thanks for reading STM Daily News – your source for News You Can Use This Moment!
We love hearing from our readers. Share your thoughts in the comments section and join the conversation with our growing community. Your feedback helps us create the stories and features that matter most to you.
Don’t miss the latest news, inspiring stories, lifestyle tips, food and drink features, and exclusive updates. Subscribe to the STM Daily News newsletter and get our top stories delivered directly to your inbox.
💬 Leave a comment.
📧 Subscribe to our newsletter.
📢 Share your favorite stories with friends and family.
Stay informed, stay connected, and be part of the STM Daily News community at STMDailyNews.com.
Last Updated on June 12, 2026 by Rod Washington
Valerie Thomas is a true pioneer in the world of science and technology. A NASA engineer and physicist, she is best known for inventing the illusion transmitter, a groundbreaking device that creates 3D images using concave mirrors. This invention laid the foundation for modern 3D imaging and virtual reality technologies.
Beyond her inventions, Thomas broke barriers as an African American woman in STEM, mentoring countless young scientists and advocating for diversity in science and engineering. Her work at NASA’s Goddard Space Flight Center helped advance satellite technology and data visualization, making her contributions both innovative and enduring.
In our latest short video, we highlight Valerie Thomas’ remarkable journey—from her early passion for science to her groundbreaking work at NASA. Watch and be inspired by a true STEM pioneer whose legacy continues to shape the future of space and technology.
🎥 Watch the video here: https://youtu.be/P5XTgpcAoHw
Dive into “The Knowledge,” where curiosity meets clarity. This playlist, in collaboration with STMDailyNews.com, is designed for viewers who value historical accuracy and insightful learning. Our short videos, ranging from 30 seconds to a minute and a half, make complex subjects easy to grasp in no time. Covering everything from historical events to contemporary processes and entertainment, “The Knowledge” bridges the past with the present. In a world where information is abundant yet often misused, our series aims to guide you through the noise, preserving vital knowledge and truths that shape our lives today. Perfect for curious minds eager to discover the ‘why’ and ‘how’ of everything around us. Subscribe and join in as we explore the facts that matter. https://stmdailynews.com/the-knowledge/
Forgotten Genius Fridays
https://stmdailynews.com/the-knowledge-2/forgotten-genius-fridays/
🧠 Forgotten Genius Fridays
A Short-Form Series from The Knowledge by STM Daily News
Every Friday, STM Daily News shines a light on brilliant minds history overlooked.
Forgotten Genius Fridays is a weekly collection of short videos and articles dedicated to inventors, innovators, scientists, and creators whose impact changed the world—but whose names were often left out of the textbooks.
From life-saving inventions and cultural breakthroughs to game-changing ideas buried by bias, our series digs up the truth behind the minds that mattered.
Each episode of The Knowledge runs 30–90 seconds, designed for curious minds on the go—perfect for YouTube Shorts, TikTok, Reels, and quick reads.
Because remembering these stories isn’t just about the past—it’s about restoring credit where it’s long overdue.
🔔 New episodes every Friday
📺 Watch now at: stmdailynews.com/the-knowledge
🧠 Now you know.
