Category: 7. Science

The intriguing rules of quantum physics almost always fail when you move from atoms and molecules to much larger objects at high temperatures.

This is because the bigger an object gets and higher the temperature is, the harder it becomes to stop it from interacting with surroundings, a phenomenon that usually erases the delicate quantum behavior.

However, a new study has managed something that seriously pushes these limits. The research has shown that a tiny glass sphere—still over a thousand times smaller than a grain of sand but huge by quantum standards—can have its rotational motion cooled down to almost the quietest state allowed by quantum physics at about 92% purity, even while the particle itself is burning hot at several hundred degrees.

This is the first time scientists have reached such a pure quantum state without having to chill the entire object to near absolute zero, opening doors to experiments once thought impossible outside of deep-freeze labs.

“The purity reached by our room-temperature experiment exceeds the performance offered by mechanically clamped oscillators in a cryogenic environment, establishing a platform for high-purity quantum optomechanics at room temperature,” the study authors note.

A clever shortcut targeting object’s specific motion

Normally, to see quantum behavior in an object larger than a molecule, researchers have to go to extremes: levitating the particle in a vacuum to shield it from outside interference, and cooling its surroundings to near -273.15°C so its motion becomes as orderly as quantum rules allow.

Even then, it’s tricky. This is because motion in the quantum world is quantized—it can only happen in specific chunks called vibration quanta. There is a lowest-energy mode called the ground state, a first excited state with a little more energy, and so on.

Though the particle can exist in a mix of these states. Reaching the ground state for a large particle has been a milestone goal. Until now, it required cooling everything to frigid extremes.

The study authors took a clever shortcut. Instead of trying to chill the particle’s entire internal energy (which is massive compared to the energy of its motion), they targeted just one specific motion: its rotation.

Controlling laser light, mirror systems to drain rotational energy

The researchers used a nanoparticle shaped not as a perfect sphere, but as a slightly stretched ellipse. When trapped in an electromagnetic field, such a particle naturally rotates around a fixed alignment, like a compass needle wobbling around north.

By precisely controlling laser light and mirror systems, forming a high-finesse optical cavity, the team could influence this wobble. The trick here is that the laser can either feed energy into the rotation or take energy away from it.

By carefully adjusting the mirrors so that energy removal was far more likely than energy addition, scientists drained almost all the rotational energy away. While doing so, they also had to account for and control quantum noise from the lasers, random fluctuations that could otherwise ruin the delicate process.

This resulted in a rotational motion freezing into a state extremely close to the quantum ground state, with just 0.04 quanta of residual energy and about 92% quantum purity, even though the particle’s internal temperature was still hundreds of degrees Celsius.

The key to making quantum systems more practical

This result breaks a long-standing barrier in quantum research. It shows that one does not have to cool an entire object to ultra-low temperatures to study its quantum properties.

Instead, by treating different types of motion, like rotation, separately, one can selectively bring parts of a system into the quantum regime while the rest remains hot and messy.

This approach could make it much easier to explore quantum effects in bigger, more complex systems—from biological structures to engineered devices—without requiring massive cryogenic setups.

However, the work focused on one specific motion in a carefully chosen nanoparticle. Hence, it is not yet an universal recipe for every large object. Future research will likely explore whether the same principles can control other motions or work with different shapes and materials.

The study has been published in the journal Nature Physics.

IN A NUTSHELL

🔍 Scientists propose two new theories that may explain the origins of dark matter. 🌌 Theories include a potential “mirror world” and a cosmic horizon acting like a particle factory. 🧪 These theories offer testable predictions to challenge established dark matter models. 🔬 Researchers are shifting focus from particle detection to understanding creation processes.

Recent developments in theoretical physics are providing new avenues for understanding the mysterious substance known as dark matter, which makes up approximately 85% of the universe’s mass. Two novel approaches are gaining attention: one proposes a “mirror world” composed of twin particles, and the other suggests that the young universe’s expanding edge could have generated particles similar to a black hole horizon. Both theories offer testable predictions and challenge established models, enriching the ongoing quest to uncover the origins of dark matter.

The Puzzle of Dark Matter

For decades, scientists have been puzzled by evidence of dark matter. Galaxies rotate faster than their visible mass should allow, and galaxy clusters bend light more than expected. These anomalies suggest a hidden mass that does not emit, absorb, or reflect light, making it invisible and detectable only through gravitational effects. Current estimates indicate that around 85% of the universe’s matter is dark, cold, and slow-moving on cosmic scales.

Despite numerous experiments, the most popular dark matter candidates have remained elusive. This lack of detection has pushed theorists to explore new ideas. Physicist Stefano Profumo from the University of California, Santa Cruz, observes that the speculative nature of these new theories offers fresh perspectives that do not rely on conventional particle dark matter models, which face increasing pressure from null experimental results.

Chinese Scientist Claims “We Mapped 27 Million Cosmic Objects in One Shot” as AI Space Tool Sparks Tensions Over Tech Dominance and Data Secrecy

Two New Theories Emerge

The first theory, recently published in the journal arXiv, envisions a mirror sector—a duplicate realm of known particles and forces that interacts weakly with our own. In this hidden world, a version of the strong force could bind “dark quarks” into heavy “dark baryons.” During the early universe, these baryons might have collapsed into tiny, stable relics akin to miniature black holes. If formed in the right quantities, they could explain the universe’s missing mass while remaining undetectable by current instruments.

The second theory, detailed in the journal Physical Review D, suggests that the expanding horizon of the early universe served as a particle factory. After inflation, the cosmos may have experienced a brief period of accelerated expansion. During this phase, the cosmic horizon would have had a temperature and emitted particles, much like a black hole. If stable particles were created this way, they could constitute dark matter across a wide range of masses.

Astrophysicist Says “We’re Trapped in a Black Hole” as James Webb Unleashes Panic Over Mind-Bending Discovery That Shakes All Known Physics

Testing the Mirror World Hypothesis

The mirror world theory has been around for years, but recent studies have sharpened its potential explanations for dark matter’s abundance. The theory posits two main possibilities: mirror electrons or mirror baryons as dark matter candidates. Both scenarios predict the existence of a “mirror photon” with a mass in the million-electron-volt range, which could explain the smoothness of small galaxies without conflicting with large-scale structures.

Future cosmic background surveys could potentially detect this model’s predicted small but measurable extra amount of early-universe radiation. Additionally, better mapping of stars in small galaxies could reveal self-interacting dark matter changes, supporting or refuting the mirror world hypothesis. Observations of the cosmic microwave background could also identify any extra radiation from the mirror world.

Galactic Horror Unleashed: The Star-Devouring Phenomenon That’s Splitting the Scientific Community and Defying Every Known Law

The Horizon of Creation Theory

Profumo’s second proposal offers a simpler setup. It imagines the universe just after inflation in a nearly steady expansion phase. In this state, the cosmic horizon acts like a hot surface, generating particles through quantum effects. If these particles are stable and interact only through gravity, they could persist as dark matter today. The final amount depends on conditions during this phase and the temperature when normal expansion resumed.

By measuring certain features of the early universe, scientists could narrow down the possible mass of this type of dark matter. Gravitational waves or small deviations in early expansion could indicate a brief accelerated phase, providing further evidence for this theory. Understanding the temperature at the end of this phase would help constrain the mass range for the dark matter particles.

As scientists continue to explore these bold theories, they open new pathways for discovering dark matter. Instead of solely focusing on particle detection in laboratories, researchers are now looking to galaxy surveys, cosmic background maps, and gravitational wave detectors for clues. These approaches reflect a broader shift in thinking, moving from identifying specific particles to understanding the processes that may have created them. Will these innovative theories lead to a breakthrough in our understanding of the universe’s hidden mass?

This article is based on verified sources and supported by editorial technologies.

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During the early days of our Solar System, giant impacts were common occurrences. Earth likely experienced such an impact that created our Moon, and Mars may have been struck by objects that created its asymmetrical surface features. But what about Venus?

Venus captured by the Magellan spacecraft (Credit : NASA/JPL-Caltech)

Researchers led by M. Bussmann from the University of Zurich, used advanced computer simulations called smoothed particle hydrodynamics (SPH) to model what would happen if Venus were struck by massive objects early in its formation. These simulations can track how materials behave during extreme collisions, making them perfect for studying planetary impacts.

The team modelled Venus as it likely existed after its initial formation: a differentiated planet with an iron core making up 30% of its mass and a forsterite mantle comprising the remaining 70%. They then simulated impacts with objects ranging from 0.01 to 0.1 Earth masses, gigantic asteroids by today’s standards.
The simulations explored various impact scenarios with specific parameters; collision speeds between 10 and 15 km/s, different impact geometries (from head-on to oblique collisions), various primordial thermal profiles, and different pre-impact rotation rates of Venus. By running these digital experiments, researchers could analyse how such collisions might affect Venus’s post impact rotation periods and debris disc formation.

Ceres, the most massive asteroid today is a mere 0.00016 Earth masses. (Credit : Justin Cowart)

The study’s findings reveal that a wide range of impact scenarios are consistent with Venus’s current rotation rate. These include head-on collisions on a non-rotating Venus and oblique, hit and run impacts by Mars sized bodies on a rotating Venus. Most importantly however, they found that collisions matching Venus’s present day rotation rate typically produce minimal debris discs that reside within Venus’s synchronous orbit. This means the material would likely reaccrete back onto the planet, preventing the formation of long lasting satellites, perfectly explaining Venus’s lack of a moon.

The researchers conclude definitively that a giant impact can be consistent with both Venus’s unusual rotation and lack of a moon, potentially setting the stage for its subsequent thermal evolution.

The study serves as a foundation for future research into Venus’s long term thermal evolution. Understanding the initial thermal state created by these potential impacts is essential for modelling how Venus developed its thick atmosphere, extreme greenhouse effect, and geological features over billions of years.
As space agencies plan new missions to Venus in the coming decades, this research provides valuable help for interpreting the geological and atmospheric data these missions will collect. The story of Venus’s violent early history may finally be coming into focus, revealing how our sister planet became the hellish world we observe today.

Source : The possibility of a giant impact on Venus

Scientists apparently underestimated the aggression of itty-bitty male fiddler crabs when they deployed a friendly robot version during mating season.

In a paper published in the journal Proceedings of the Royal Society B, animal behavior researchers from the UK’s University of Exeter detailed the embarrassing end to their experiment with “Wavy Dave,” a 3D-printed, Bluetooth-controlled crab-bot trained to wave at its fellow crustaceans.

Known for having one claw that’s much larger than the other, fiddler crabs not only wave their large pincers to attract mates, but actually hold diminutive competitions during their mating seasons in which females choose those whose claws are biggest — yes, seriously — and wave the fastest.

Though scientists already knew that male fiddler crabs will, as lead study author Joe Wilde said in a statement, “adjust their sexual displays if rivals are nearby,” less was known about what exactly those males do in response to the rivals themselves.

To test it out, Wilde — who is now at the Biomathematics and Statistics Scotland lab — and his Exeter colleagues took Wavy Dave out for a spin during fiddler crab mating season in the mudflats of Portugal’s Ria Formosa Natural Park.

Initially, the males left Dave alone, possibly because his larger claw was bigger — and therefore more likely to win the attention of females or pose a threat — than their own. At some point, however, “the females realized [the robot] was a bit odd,” Wilde said, which led some of the male fiddlers to confront him.

Unfortunately, things didn’t turn out so well for the little crab robot.

“One male broke Wavy Dave by pulling off his claw,” the lead author wrote. “We had to abandon that trial and reboot the robot.”

Despite their creation getting torn to pieces, however, Wilde and his team learned a lot from their short-lived experiment.

“If you own a shop and your rivals start selling things really cheaply, you might have to change how you run your business,” the researcher explained. “The same might be true for males signaling to attract females — and our study suggests males do indeed respond to competition.”

As with humans and other animals, the male fiddler crabs who took Dave down have “subtle ways” of adjusting how they act “to compete in a dynamic environment, investing more in [sexual] signaling when it is likely to be most profitable.”

Like so many drunk bros in bar fights, the male fiddlers only attacked Wavy Dave after assessing the situation and getting feedback from the females — and ultimately, nobody lost except for the robot.

More on responses to robots: As Waymo Debuts in Philadelphia, It May Want to Look Into the Time Furious Locals Tore Apart an Adorable Robot

Welcome back to the Abstract! Here are the studies this week that gave me hope, sent me back in time, and dragged me onto the dance-floor. 

First, what’s your favorite cockatoo dance move? To be fully informed in your response, you will need to review the latest literature on innovations in avian choreography. Then: salvation for sea stars, a tooth extraction you’ll actually like, ancient vortex planets, and what to expect when you’re an expecting cockroach. 

Everybody do the cockatoo

Lubke, Natasha et al. “Dance behaviour in cockatoos: Implications for cognitive processes and welfare.” PLOS One.

If you play your cards right as a scientist, you can spend all day watching cockatoos dance online and IRL. That’s what one team of researchers figured out, according to a new study that identified 17 cockatoo dance moves previously unknown to science.  

“Anecdotally, parrots (Psittaciformes) have been reported to show ‘dancing’ behaviour to music in captivity which has been supported by studies on a few individuals,” said researchers led by Natasha Lubke of Charles Sturt University. “However, to date it remains unclear why parrots show dance behavior in response to music in captivity when birds are not courting or in the absence of any potential sexual partner.” Cockatoos, by the way, are a type of parrot. 

It’s worth pursuing this mystery in part because parrots are popular pets and zoo attractions that require environmental enrichment for their welfare while in captivity. Listening to music and dancing could provide much-needed stimulation for these smart, social animals.

To that end, the authors watched dozens of videos of cockatoos on YouTube, TikTok, and Instagram, with search terms like “birds dancing Elvis,” “bird dancing to rap music” and “bird dancing to rock music.” They also played music and podcasts to a group of captive birds—two sulphur crested cockatoos (Cacatua galerita), two Major Mitchell cockatoos (Lophochroa leadbeateri) and two galahs (Eolophus roseicapilla)—housed at Wagga Wagga Zoo in Australia.

The results expanded the existing database of cockatoo dance moves from classics like headbang, foot-lift, and body roll to include new-wave choreography like jump turn, downward walk, and fluff (wherein “feathers are fluffed” in a “fluffing event” according to the study). 

All the birds that the team studied onsite at the zoo also danced at least once to audio playback of the song “The Nights” by Avicii. They even danced when music was not playing, bopping around to silence or to  tips from the financial podcast “She’s on the Money.”

“Dance behaviour is perhaps a more common behaviour in cockatoos than previously thought,” the team concluded. “Further research is required to determine the motivational basis for this behaviour in captivity.”

It will be interesting to see what forthcoming studies reveal, but my own prediction is that the motivational basis falls under Lady Gaga’s edict to “Just Dance.”

In other news…

Solving the mystery of what’s killing billions of sea stars

Prentice, Melanie et al. “Vibrio pectenicida strain FHCF-3 is a causative agent of sea star wasting disease.” Nature Ecology and Evolution.

Over the past decade, a devastating illness has killed off billions of sea stars in what is the largest marine epidemic on record. Scientists have finally identified the culprit that causes sea star wasting disease (SSWD) as the bacteria Vibrio pectenicida, which is from the same family that causes cholera in humans (Vibrio cholerae).

Sea stars infected with SSWD form lesions and rapidly disintegrate into goo in mass mortality events that have upended ecosystems on the Pacific coast from Alaska to Mexico. The isolation of the agent involved in these grotesque die-offs will hopefully help restore these vital keystone species.

“This discovery will enable recovery efforts for sea stars and the ecosystems affected by their decline,” said researchers led by Melanie Prentice of the Hakai Institute and the University of British Columbia.

Psst…you have some ancient atmosphere stuck in your teeth

Feng, Dingsu et al. “Mesozoic atmospheric CO2 concentrations reconstructed from dinosaur tooth enamel.” Proceedings of the National Academy of Sciences.

For the first time, scientists have reconstructed atmospheres that existed more than 100 million years ago by studying the teeth of dinosaurs that breathed in this bygone air.

A team analyzed oxygen remnants preserved in the dental enamel of roughly two dozen dinosaur teeth including sauropods (such as Camarasaurus), theropods (including Tyrannosaurus), and the ornithischian Edmontosaurus (go Oilers). This data enabled them to infer carbon dioxide concentrations of around 1,200 parts per million (ppm) and 750 ppm in the Jurassic and Cretaceous periods, respectively. 

This is in line with other findings that have found wild swings in CO2 levels during the dinosaur age, likely due to volcanic activity. Earth’s current atmosphere is about 430 ppm, and is rapidly rising due to human-driven greenhouse gas emissions.  

“Fossil tooth enamel can thus serve as a robust time capsule for ancient air [oxygen] isotope compositions,” said researchers led by Dingsu Feng of the University of Göttingen. “This novel form of analysis can “provide insights into past atmospheric greenhouse gas content and global primary productivity.”

Vortex planets from the dawn of light

Eriksson, Linn E J et al. “Planets and planetesimals at cosmic dawn: Vortices as planetary nurseries.” Monthly Notices of the Royal Astronomical Society

The first planets ever born in the universe may have formed in vortices around ancient stars more than 13.6 billion years ago. These stars were made of light elements, such as hydrogen and helium, but each new generation forged an itty-bit of heavier elements in their bellies that could potentially provide basic planetary building blocks.

By running simulations of this early epoch, known as cosmic dawn, researchers led by Linn E.J. Eriksson of the American Museum of Natural History found that small rocky worlds, on the scale of Mercury or Mars, could coalesce from dust and pebbles trapped in so-called “vortices,” which are like cosmic eddies that form in disks around newborn stars. 

As a consequence, this “suggests that vortices could trigger the formation of the first generation of planets and planetesimals in the universe,” the team said.

Congratulations to everyone who had “ancient vortex planets from cosmic dawn” on their bingo card this week.

Wash it all down with a glass of cockroach milk

Frigard, Ronja et al. “Daily activity rhythms, sleep and pregnancy are fundamentally related in the Pacific beetle mimic cockroach, Diploptera punctata.” Journal of Experimental Biology.

We began with cockatoos and we’ll close with cockroaches. Scientists have been bothering sleepy pregnant cockroaches, according to a new study on the Pacific beetle mimic cockroach, which is one of the few insects that produces milk and gives birth to live young.   

“To our knowledge, no study has investigated the direct relationship between sleep and pregnancy in invertebrates, which leaves open the questions: do pregnant individuals follow similar sleep and activity patterns to their non-pregnant counterparts, and how important is sleep for successful pregnancy?” said researchers led by Ronja Frigard of the University of Cincinnati.

As it turns out, it’s very important! The team disrupted pregnant cockroaches by shaking their containers four times during their sleeping period for weeks on end. While the well-rested control group averaged 70 days for its gestation period, the sleep-deprived group took over 90 days to deliver their young. In addition, “when chronic sleep disturbance occurs, milk protein levels decline, decreasing nutrients available to the embryos during development,” the team concluded.

For those of us who have been woken up at night by the scuttling of cockroaches, this study is our revenge. Enjoy it while you can, because the smart money is on cockroaches outliving us all.

Thanks for reading! See you next week.

Archaeologists have found primitive stone tools on the Island of Sulawesi, Indonesia that date back to 1.04 to 1.48 million years.

This marks the oldest human habitation in this region.

The study, published in Nature, is predicted to solve the mystery of Homo floresiensis.

They are diminutive “hobbit” humans who lived on nearby Flores Island until about 500,000 years ago.

The ancient discovered tools were used to cut and scrap due to their sharp edges.

This suggests that early humans may have inhabited Sulawesi around the same time or even earlier than Flores.

Dr. Adam Brumm, co-lead author of the study, said: “We have long suspected that the Homo floresiensis lineage came originally from Sulawesi. This discovery adds further weight to that possibility.”

More discoveries at the Calio site found seven stones alongside animal fossils, including a jawbone of an extinct giant pig.

While there were no human remains found in the fossils, researchers believe that  Homo erectus or an early relative may have made the tools. 

The study sparked speculations about how the ancient humans reached the isolated islands.

Brum noted “getting to Sulawesi would not have been easy.”

Experts suggest that the discovery highlights the gaps in the understanding of how early humans migrated.

Prof. John Shea of Stony Brook University stated: “If hominins reached these islands, they might have survived briefly before going extinct,” noting that only modern humans have clear evidence of successful ocean crossings.

To learn more about this mysterious chapter of human evolution, researchers continue to search Sulawesi for hominin fossils. Brumm said: “There’s a truly fascinating story waiting to be told on that island.”

In 2018, NASA launched the Parker Solar Probe on a trajectory that would eventually have it dive into the Sun’s atmosphere (corona), getting seven times closer to our host star than any other spacecraft so far. In June 2025, the probe completed its 24th close approach to the Sun, whilst equaling its record for the fastest a human-made object has ever traveled, at a zippy 692,000 kilometers per hour (430,000 miles per hour).

The probe is aimed at studying the Sun’s atmosphere and will hopefully shed light on a few long-standing mysteries, such as how the solar wind is accelerated. One puzzle, first discovered in 1939, is that the Sun’s corona is far hotter than the solar surface. And not just by a little.

“The hottest part of the Sun is its core, where temperatures top 27 million °F (15 million °C). The part of the Sun we call its surface – the photosphere – is a relatively cool 10,000 °F (5,500 °C),” NASA explains. “In one of the Sun’s biggest mysteries, the Sun’s outer atmosphere, the corona, gets hotter the farther it stretches from the surface. The corona reaches up to 3.5 million °F (2 million °C) – much, much hotter than the photosphere.”

This is known as the “coronal heating problem”. The basic problem is this: why is the atmosphere far hotter than the surface, when the surface is much closer to the core, where energy is generated through the fusion of hydrogen into helium? 

There have been suggestions that the extra heat in the corona is caused by turbulence, or a type of magnetic wave known as “ion cyclotron waves”.

“Both, however, have some problem—turbulence struggles to explain why hydrogen, helium and oxygen in the gas become as hot as they do, while electrons remain surprisingly cold; while the magnetic waves theory could explain this feature, there doesn’t seem to be enough of the waves coming off the sun’s surface to heat up the gas,” Dr Romain Meyrand, author on the new paper, explained in a previous statement.

While both ideas have problems, together with a “helicity barrier”, they show some promise for explaining the coronal heating problem.

“If we imagine plasma heating as occurring a bit like water flowing down a hill, with electrons heated right at the bottom, then the helicity barrier acts like a dam, stopping the flow and diverting its energy into ion cyclotron waves,” Meyrand added. “In this way, the helicity barrier links the two theories and resolves each of their individual problems.”

Essentially, the helicity “barrier” alters turbulent dissipation, changing how fluctuations dissipate and how the plasma is heated. The team has now analyzed data from the Parker Solar Probe, and it appears to show evidence for the helicity barrier.

“The barrier can form only under certain conditions, such as when thermal energy is relatively low compared to magnetic energy. Since fluctuations in the magnetic field are expected to behave differently when the barrier is active versus when it is not, measuring how these fluctuations vary with solar wind conditions relevant to the barrier’s formation—including the thermal-to-magnetic energy ratio—provides a way to test for the barrier’s presence,” the team explains in their paper. 

“By analyzing solar wind magnetic field measurements, we find that the fluctuations behave exactly as predicted with changes in solar wind parameters that characterize these conditions. This analysis also allows us to identify specific values for these parameters that are needed for the barrier to form, and we find that these values are common near the Sun.”

Further analysis is necessary, but the approach looks fairly promising for explaining the problem.

“This paper is important as it provides clear evidence for the presence of the helicity barrier, which answers some long-standing questions about coronal heating and solar wind acceleration, such as the temperature signatures seen in the solar atmosphere, and the variability of different solar wind streams,” Dr Christopher Chen, study author and Reader in Space Plasma Physics at Queen Mary University of London, said in a statement.

“This allows us to better understand the fundamental physics of turbulent dissipation, the connection between small-scale physics and the global properties of the heliosphere, and make better predictions for space weather.”

While conducted on our own Sun (we are far from ready to plunge spacecraft into the atmosphere of other stars), the study has implications for other stars, and other parts of the universe, in other collisionless plasmas.

“This result is exciting because, by confirming the presence of the ‘helicity barrier’, we can account for properties of the solar wind that were previously unexplained, including that its protons are typically hotter than its electrons,” said Jack McIntyre, lead author and PhD student from Queen Mary University of London.

“By improving our understanding of turbulent dissipation, it could also have important implications for other systems in astrophysics.”

The study was published in Physical Review X.

An earlier version of this story was published in July 2025.

The air can look clear and still carry a problem. Across the United States, ozone has been linked to lower chances of survival for some trees, and a new analysis finally shows how much risk different species face.

Researchers paired long term forest records with measured exposure to tropospheric ozone to set species specific thresholds for harm. The study spans 88 species and roughly 1.5 million trees, a scale that moves the conversation beyond seedlings and lab chambers.

Study on ozone pollution

Nathan Pavlovic of Sonoma Technology Inc. and Charles Driscoll of Syracuse University brought together forest inventory data and air quality archives to estimate how exposure links to slower growth and lower survival. Their team focused on mature trees observed in place, not seedlings in controlled settings.

Earlier work in the United States leaned heavily on seedling experiments, including a 16 species synthesis that set response curves for biomass loss. That seedling paper became a touchstone, but it could not tell us how older trees respond after decades in the field.

Ozone effects on tree survival

The team used the concept of a critical level to summarize risk, the exposure at which a defined drop in growth or survival appears.

The researchers expressed exposure with “W126,” a cumulative, summertime-weighted metric for ozone exposure that emphasizes higher concentrations during daylight hours, reflecting their greater potential to damage vegetation.

They modeled growth and 10 year survival separately, which matters because a small shift in survival compounds over a century long rotation. The paper reports species specific W126 levels for a 5 percent drop in growth and a 1 percent drop in survival, allowing managers to see which trees blink first.

The numbers they put forth sit in a wider policy context. The EPA has long evaluated vegetation protection using W126 in its welfare reviews, and its advisory panel, CASAC, has considered thresholds associated with 1 to 2 percent biomass loss in trees when weighing secondary standards.

Ozone impact in west vs east

“Recently (2016-2018), portions of the western United States exceeded O3 CLs (or ozone critical levels, are the exposure thresholds at which a specific percentage decline in tree growth or survival is expected to occur) for nearly all tree species for both growth and survival,” wrote Pavlovic and colleagues.The clearest pattern appears west of the Rockies. 

In the East, the analysis found little evidence of widespread growth impacts at current levels, with survival effects limited to sensitive species and pockets with higher exposure.

That picture is consistent with national monitoring records showing strong declines in extreme ozone across the eastern United States since the 2000s.

Seedlings versus mature trees

Seedling studies provide clean experiments, but they cannot fully replicate heat, drought, soil variation, and competition in mature stands. The earlier 16 species seedling synthesis captured broad sensitivity classes, yet some species that look tolerant in chambers can be more vulnerable in place when ozone stacks with water stress and heat.

The new analysis, by design, keeps those mediating factors in the model to produce field relevant exposure thresholds.

That makes the species list more useful for foresters weighing which coniferous evergreens to plant and where deciduous hardwoods may hold up better under ozone.

What this means for forests and policy

A practical use case is simple. If a county’s summertime W126 sits above a species’ survival threshold, managers can alter planting mixes, accelerate thinning, or shift regeneration toward less sensitive species that still meet ecological goals.

Policy makers face a different question. Secondary ozone standards under the Clean Air Act are meant to protect crops, materials, and ecosystems, but the current form, built around an eight-hour human health metric, does not map neatly to vegetation outcomes that depend on seasonal accumulation.

Internationally, Europe often reports AOT40 exceedance while the United States leans on W126, and scientific bodies favor flux based vegetation metrics that track uptake. That split underscores why an ecosystem specific exposure metric remains important in any standard that intends to protect living landscapes.

Ozone pollution and tree survival

No single metric captures every pathway to damage, and W126 emphasizes summertime peaks that matter a great deal for crops. The longer growing seasons of evergreen conifers can raise cumulative uptake, which may help explain why western forests emerge as more sensitive in the new maps.

Uncertainty also comes from interpolation in places with sparse rural monitors, from wildfire smoke chemistry, and from how drought changes stomatal behavior. Even so, the thresholds offer a practical yardstick that can be updated as monitoring improves and as exposure models evolve.

The broader science keeps moving, including new Earth system model schemes that better represent ozone injury to photosynthesis and water use.

Better process representation should make regional carbon and climate projections more realistic, and helps translate exposure reductions into real ecological gains.

The study is published in Journal of Geophysical Research: Atmospheres.

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Relationship between diamondoid content and thermal maturity

A substantial amount of research has confirmed that the formation of diamondoids is closely related to the thermal maturation of organic matter. Fang et al.³⁴ proposed that the evolution of diamondoids in petroleum was divided into three main stages, i.e., early generation stage (Ro at 0.8% − 1.0%), high-temperature cracking stage (Ro > 1.0%), and cracking stage. Wei et al.⁵ suggested that diamondoid compounds underwent stages of generation, enrichment, and destruction with increasing thermal maturity, where they suggested that the generation stage was at Ro < 1.1%, the enrichment stage at Ro ranging 1.1% − 4.0%, and the destruction stage at Ro > 4.0%. Although there are some differences in the criteria for dividing the evolutionary stages in these studies, it is evident that thermal maturity plays a decisive role in the formation and destruction of diamondoids.

The Gulong shale oil is characterized by in-situ accumulation^19,22, which means that the burial depth of shale or the thermal maturity of organic matter controls the content and distribution characteristics of diamondoids in the shale oil. As shown in Fig. 6, the total diamondoid content and adamantane content are closely related to Ro, with correlation coefficients R² greater than 0.84, indicating that the formation of diamondoids and adamantanes is mainly controlled by thermal maturity. The relationship between the content of diamantanes and Ro is weaker, with a correlation coefficient R² greater than 0.56, suggesting that the content of diamantanes is not only affected by thermal maturity, but also by other factors.

According to the relationship between diamondoid content and Ro shown in Fig. 6, four stages can be distinguished. (1) Immature to low-mature stage with Ro < 0.8%; diamondoid components are mainly adamantanes with low content, generally less than 60 µg/g, and diamantanes are not detected. We suspect that the initial formation of diamondoids may have occurred during early diagenesis or as a result of biogenic processes. (2) Mature stage with Ro from 0.8 to 1.2%; diamondoid content remains at a low level, still dominated by adamantanes with content less than 100 µg/g, and diamantanes are not detected. This indicates that the maturation process has little effect on the formation of diamondoids. (3) Mature to high-mature stage with Ro from 1.2 to 1.4%; diamondoid content shows a slow increasing trend. The total diamondoid content ranges from 100 to 300 µg/g, adamantane content ranges from 100 to 280 µg/g, and diamantanes appear with content around 15 to 25 µg/g. This implies the beginning of rearrangement and cracking reactions in the shale oil. (4) High-mature stage with Ro > 1.4%; diamondoid content increases rapidly. The total diamondoid content ranges from 300 to 1000 µg/g, adamantane content ranges from 280 to 1000 µg/g, and diamantanes are present with content around 25 to 55 µg/g. This indicates significant rearrangement and cracking reactions in the shale oil.

Relationship between diamondoid content and clay mineral catalysis

Multiple studies have confirmed that diamondoid compounds can be formed from polycyclic hydrocarbons under high-temperature conditions, catalyzed by Lewis acid in clay minerals^6,15,35,36. Smectite and other clay minerals play an important role in the formation of diamondoids. Chao³⁷ demonstrated through pyrolysis experiments that the Lewis acidity decreases gradually during the transformation of smectite to illite. Research on the diagenetic evolution of clay minerals in the Gulong shale shows that in the stage with Ro < 1.0%, clay minerals are mainly composed of smectite and illite-smectite mixed layers³⁸. After Ro > 1.0%, clay minerals are dominated by illite-smectite mixed layers and illite, with the mixed layers progressively transforming into illite with increasing thermal maturity. Although the catalytic activity of clay minerals is strong in the early stages of diagenesis and weakens in later stages, their catalytic role remains significant as organic matter begins to undergo rearrangement and cracking reactions³⁷.

At a similar higher thermal mature stage, tight oil often contains a higher concentration of diamondoids than the shale oil (Fig. 6). For example, in the Qijia-Gulong Sag, the tight oil from Well HT1H in the Fuyu oil layer has a Ro of approximately 1.45%, with a total diamondoid content of 270 µg/g, adamantane content of 251 µg/g, and diamantane content of 19 µg/g. In contrast, the shale oil from the adjacent Well GY8HC, which is sourced from the overlying source rock, has a total diamondoid content of 362 µg/g, adamantane content of 339 µg/g, and diamantane content of 24 µg/g. Since tight oil originates from early-generated crude oil in the overlying Qingshankou Formation shale¹⁸, it has experienced higher temperatures than its overlying source rock after entering the reservoir. However, the content of all types of diamondoids in shale oil is 1.26 to 1.35 times higher than that in tight oil. This indicates that under the same thermal evolution conditions, the cracking degree of crude oil in non-clay reservoirs, of which the clay mineral content is between 4.7% − 13.8%, is significantly lower than that in clay-rich shale, whose clay mineral content is 32.4% − 56.1%. This suggests that the catalytic action of clay minerals in shale promotes the cracking of shale oil and the formation of diamondoids. In contrast, tight sandstone reservoirs, which contain fewer clay minerals and have weaker catalytic activity, have lower diamondoid content.

Relationship between diamondoid content and overpressure in oil reservoirs

Song et al.¹⁶ argued that under overpressure conditions, the acidic catalytic activity of clay minerals was enhanced. Under high-temperature and high-pressure conditions, the acidic sites on the surface of clay minerals can adsorb and activate lower-grade diamondoids with alkyl substitution in crude oil, making them more susceptible to rearrangement and homologation reactions, thereby generating higher-grade diamondoids. Additionally, the overpressure state increases the intensity of molecular motion in crude oil, leading to more frequent collisions between molecules and accelerating the rate of diamondoid formation. Lin and Wilk⁶ also proposed a similar argument, suggesting that higher grade diamondoids in crude oils were generated from lower grade diamondoids with alkyl substitution through homologation reactions under higher subsurface temperatures and pressures.

In this case, comparing the diamondoid content of shale oil with similar maturity but different pressure environments during the high-maturity stage also suggests the impact of overpressure on diamondoid formation. For example, a shale oil (Ro 1.31%) from Well SYY1 in the Qijia-Gulong Sag, located 20 m horizontally from a fault, has a lower reservoir pressure coefficient (1.3) due to the oil expulsion through the fault; the total diamondoid content is 119 µg/g, adamantane content is 119 µg/g, and diamantanes are absent. In contrast, shale oil from Well GY7 in the area has close thermal maturity (Ro 1.35%), but is far away from the fault, with horizontal distance at 1004 m; it shows no significant vertical hydrocarbon expulsion, and the reservoir pressure coefficient is 1.5. The shale oil from this well has a total diamondoid content of 281 µg/g, adamantane content of 247 µg/g, and diamantane content of 7 µg/g. The total diamondoid content and adamantane content in the Well GY7 are 2.4 and 1.9 times those in the Well SYY1, respectively; particularly, the presence of diamantane in Well GY7 strongly suggests that overpressure significantly enhances the formation of higher-grade diamondoids. Measured reservoir pressure coefficients in the Gulong shale indicate that they are closely related to the thermal maturity. The pressure coefficient is 1.0 for Ro < 1.0%, 1.0 to 1.2 for Ro between 1.0% and 1.2%, and 1.2 to 1.6 for Ro > 1.2%. Therefore, it can be expected that overpressure exerts a more significant influence on diamondoid formation when Ro exceeds 1.2%. Notably, the correlation between diamantane content and maturity in shale oil (Fig. 6) is weaker than that observed for adamantanes, implying that the diamantane content may be more influenced by reservoir pressure. In shale oils with close thermal maturity from different areas, variations in through-going faults and formation pressure coefficients lead to significant differences in diamantane content. The reason may be that the increase in pressure changes the structure of clay minerals and enhances their catalytic activity³⁹.

Relationship between diamondoid composition and crude oil maturity

The compositional distribution of diamondoids in shale oil is closely related to their thermal maturity. Chen¹³ established a relationship between Ro and MDI (Methyl Diamantane Index: 4-MD/ (1-MD + 3-MD + 4-MD)) for conventional oil in the Tarim Basin; as shown in Fig. 7, the Ro ranges from 0.9% to 2.2%, while MDI ranges from 20% to 75%. In contrast, as for the Gulong shale oil, Ro ranges from 1.1% to 1.6%, while the MDI mainly ranges between 15% and 70% (Fig. 7). Compared to the conventional oil in the Tarim Basin, the rapid increase of the MDI with increasing thermal maturity may be attributed to the enhanced clay mineral catalytic effect under high-temperature and high-pressure conditions present in Gulong shale oil reservoirs, as discussed before.

DAHL et al.¹ proposed a calculation formula for evaluating the degree of oil cracking using the absolute content of 4-MD + 3-MD:

Where: C₀ is the concentration of (4-+3-) MD in the uncracked sample (µg/g), which is the baseline value of (4-+3-) MD; C_c is the concentration of (4-+3-) MD in samples of any maturity (µg/g); C_R represents the degree of oil cracking.

The basis for evaluation lies in determining the baseline value of 4-MD + 3-MD in a basin. In this study, the baseline value of (4-+3-) MD of conventional oil, which is 4.6 µg/g, is used as the reference. This value is comparable to the global baseline level of 4 to 5 µg/g for crude oil. For the Gulong shale oil, the concentration of 4-MD + 3-MD is generally in the range of 4 to 9 µg/g. The cracking degree of the Gulong shale oil is estimated to be between 0% and 50% (Fig. 8). Specifically, for the shale oil with Ro between 1.2% and 1.4%, the cracking degree ranges from 0% to 35%, while for the shale oil with Ro > 1.4%, the cracking degree ranges from 8 to 51%.

As shown in Fig. 8, shale oil samples with close maturity show a significant difference in the cracking degree, implying that the shale oil cracking may be impacted by shale reservoir fluid pressure and clay mineral content, as discussed above. As discussed in 4.3, shale oil reservoirs close to a fault tend to have less fluid pressure; as a result, corresponding shale oils may have less diamondoids and thus oil cracking degree.

Notably, in contrast to hydrocarbon reservoirs in other basins, which may have experienced migration or secondary alteration, the Gulong shale oil is characterized by in-situ accumulation. The oil has not undergone large-scale migration, gas washing, or biodegradation, and its high diamondoid content indicates the characteristics of in-situ cracking and rearrangement to form diamondoids. In contrast, conventional oils in the Daqing Placanticline have relatively low total diamondoid content, but the content of diamantanes is significantly higher than that in shale oil with the same maturity (Table 3), indicating that the diamondoid content is mainly contributed by early oil generation, with some diamantanes originating from late-stage oil generation.

Formation and evolution pattern of diamondoids

Based on the analysis of diamondoid formation processes and the relationship between their relative abundance and key controlling factors, the formation of diamondoids in the Gulong shale oil is divided into four distinct stages (Table 5).

Primary stage (Ro < 0.8%): Thermal degradation of organic matter is weak. Due to no significant oil cracking occurring in this stage, we suspect that the source of diamondoids may be transformed from some biomarkers preserved in kerogen^40,41,42. The diamondoids are mainly adamantanes, and the content is generally less than 60 µg/g.

Inheritance stage (Ro = 0.8%−1.2%): The thermal degradation of organic matter is enhanced; as a result, diamondoids increase slightly. However, diamondoids remain predominantly adamantanes, with the content less than 100 µg/g.

Generation stage (Ro = 1.2%−1.4%): Oil starts to crack, with the maximum cracking degree reaching up to 35%. The cracking of shale oil positively impacts the formation of diamondoids. Additionally, the catalytic effect of clay minerals combined with overpressure accelerates the formation of diamondoids. This is characterized by a marked increase in the quantity of adamantanes, with the highest content reaching up to 300 µg/g. Diamantanes also begin to appear, but are present in small amounts, with the content less than 25 µg/g.

Enrichment stage (Ro > 1.4%): Oil undergoes significant thermal cracking at this stage, indicated by a rapid rise in diamondoids. For example, the shale oil in the Qijia-Gulong Sag shows a maximum cracking degree of 51% and a minimum density of 0.77 g/cm³ (Table 1). Additionally, the catalytic effect of clay minerals can increase diamondoids by 1.3 times, while overpressure in reservoirs can further boost diamondoids by approximately 2 times. This results in adamantane compounds reaching a maximum content of up to 1000 µg/g and diamantanes reaching a maximum of up to 55 µg/g. The combined influence of these factors promotes the enrichment of diamondoids.