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Separating out signals recorded at the seafloor



Credit: Clive Jones, Washington University in St. Louis
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.

“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

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The Unseen Power of Nature: Los Angeles River’s Dramatic Display

“Los Angeles River’s recent surge reminds us of nature’s might and the remarkable bravery of those who protect and serve.”



Los Angeles, known for its bustling urban landscape and iconic landmarks, is also home to a hidden natural wonder—the Los Angeles River. While often overlooked, this river, meandering through concrete channels, reveals its formidable force during the rainy season, as recently witnessed in a remarkable turn of events.

By User2004 – Own work by the original uploader, Public Domain, https://commons.wikimedia.org/w/index.php?curid=855785

In a city where the river’s presence can be overshadowed by the urban sprawl, the recent events served as a powerful reminder of nature’s might. Fueled by an atmospheric river, the usually tranquil waterway transformed into a raging torrent, posing a threat to the flood-control infrastructure and prompting a dramatic rescue.

Amidst this dramatic transformation, a heartwarming yet perilous river rescue unfolded. A man, driven by instinctive bravery, leaped into the churning waters to save his beloved pet. Fortunately, the LA Fire Department swiftly intervened, showcasing the courage and skill of their helicopter crew as they executed a daring rescue, ultimately saving both the man and his loyal companion.

As the river surged, concerns mounted for the vulnerable homeless population residing along its banks. With encampments nestled among its shores, the deluge raised urgent alarms for their safety. First responders and swift-water rescue teams stood ready, highlighting the unwavering commitment to safeguarding every individual impacted by the river’s unpredictable temperament.

This recent episode serves as a poignant reminder of the intricate relationship between urban life and the forces of nature. It underscores the need for continued vigilance and preparedness, especially in a city where the convergence of urban living and natural elements can yield unexpected challenges.

The Los Angeles River’s surge, though brief, illuminates the significance of acknowledging and respecting the inherent power of nature. It also underscores the remarkable bravery and dedication of those who stand ready to protect and serve, even amidst the most formidable circumstances.

In the heart of a bustling metropolis, the Los Angeles River quietly flows, reminding us of the unseen forces that shape our world and the resilience of the human spirit in the face of nature’s awesome power.

Source: Associated Press


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Unveiling the Mysteries of Ancient Tree Fossils: A Dr. Seuss-like Discovery

Unearthed 350 million-year-old tree fossils reveal a Dr. Seuss-like world, offering insights into Earth’s ancient forests and evolutionary experiments.



Unearthed by paleontologists Robert Gastaldo, Olivia King, and Matthew Stimson, these 350 million-year-old tree fossils, named “Sanfordiacaulis,” offer a rare insight into the architecture of ancient trees. Unlike typical tree fossils, these specimens retain their branches and crown leaves, painting a vivid picture of a bygone era.

Cheeck out the story on CNN: https://www.cnn.com/2024/02/02/world/sanfordiacaulis-ancient-tree-fossils-discovery-scn/index.html

Trees, the ancient sentinels of our planet, have long held secrets of Earth’s past. Recently, a groundbreaking discovery of uniquely preserved 3D tree fossils in a Canadian quarry has provided a glimpse into the evolution of Earth’s early forests, shedding light on a period of history shrouded in mystery.

The discovery of these fossil trees, with a size and completeness rarely seen in ancient plant fossils, challenges existing knowledge and fills gaps in the fossil record. The preservation of over 250 leaves around one trunk, each extending 5.7 feet, hints at a diverse ecosystem vastly different from what we know today.

The unique fossilization of these trees, believed to be a result of a catastrophic earthquake-induced landslide in an ancient rift lake, offers a snapshot of a moment frozen in time. This extraordinary find has captured the attention of experts like Peter Wilf, a paleobotanist, who emphasizes the significance of these fossils in understanding the evolution of early forest structures.

Described as reminiscent of a Dr. Seuss illustration, the Sanfordiacaulis stands as a testament to the experimental nature of evolution. Though short-lived in the Earth’s history, these peculiar trees represent a “failed experiment of science and evolution,” showcasing the diversity and adaptability of ancient plant life.

Looking ahead, these fossil trees not only provide insights into Earth’s past but also offer clues about the future. By understanding how ancient trees diversified and occupied different ecological niches, scientists can gain valuable knowledge about the potential trajectory of life on our planet.

In conclusion, the discovery of the Sanfordiacaulis fossils opens a window into a world long gone, sparking curiosity about the mysteries of Earth’s early forests and the lessons they hold for the future. As we unravel the secrets of these ancient tree sentinels, we continue to paint a richer picture of life 350 million years ago and the remarkable journey of evolution on our planet.

Source: CNN

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The Ocean Sunfish: A Gentle Giant of the Sea

The ocean sunfish, or Mola mola, is a gentle giant of the sea, known for its enormous size, unique habits, and peaceful nature.



If you’ve never heard of the ocean sunfish, also known as Mola mola, get ready to be amazed. These gentle giants of the sea are truly one of the most unique and fascinating creatures you’ll encounter in the ocean. With their enormous size and peculiar appearance, ocean sunfish have captivated the curiosity of scientists and ocean enthusiasts alike.

Lifeform of the Week: Ocean Sunfish – EarthSky

At first glance, it’s hard to believe that these fish can reach up to 12 feet (3.6 m) in height, making them the heaviest bony fish in the world. Their sheer size often leaves people in awe, as it’s not every day you come across a fish that resembles a drifting island. However, what’s even more intriguing is the fact that they appear to be newcomers to the planet, with scientists believing them to be one of the most recent fish species to populate the sea.

One of the most fascinating aspects of the ocean sunfish is their behavior. These gentle creatures have a penchant for sunbathing, often seen floating near the water’s surface, basking in the warm sunlight. This behavior has led to the misconception that they derive energy directly from the sun, which, in turn, inspired their name. In Spanish, they are aptly called “peces luna” or moonfish, a nod to a legend where fishermen mistook them for the reflection of the moon in the water, especially at night.

To truly appreciate the ocean sunfish, it’s best to witness them in action. Watching a video or observing them in their natural habitat can provide an unparalleled experience, offering a glimpse into the grace and beauty of these enormous, unique creatures. Their slow, serene movements through the water are a sight to behold, prompting a sense of wonder and admiration for the mysteries of the ocean.

Despite their imposing size, ocean sunfish are known for their gentle nature. They pose no threat to humans and are often regarded as peaceful inhabitants of the sea. Their sheer presence serves as a reminder of the diverse and wondrous life forms that call the ocean home.

In conclusion, the ocean sunfish, with its extraordinary size, peculiar habits, and gentle demeanor, stands as a testament to the awe-inspiring diversity of marine life. As we continue to explore and learn about the mysteries of the ocean, encountering creatures like the ocean sunfish serves as a reminder of the importance of preserving and protecting our marine ecosystems for generations to come. Whether you’re an avid marine enthusiast or simply curious about the wonders of the natural world, the ocean sunfish is an undeniable marvel worth celebrating and protecting.

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