Tag Archives: hydrocarbon

New catalyst nanoparticle turns plastic waste into high-quality hydrocarbons for oils, waxes, cosmetics

New research is looking to give plastic waste a new lease on life as quality motor oil, lubricants, detergents, or even cosmetics.

Electron micrograph of the platinum nanoparticles distributed onto perovskite nanocubes.
Image credits Northwestern University / Argonne National Laboratory / Ames Laboratory.

Let’s not beat around the bush: humanity has a plastic problem. We’re making a lot of it and we’re throwing most away after a single use. Most recycling methods available today can take some of this waste out of the environment, but they also result in cheap, lower-quality plastics than the ones going into the process, which doesn’t make them very lucrative.

In an effort to find a better way of repurposing the mounds of plastic in the wild, a group of U.S. researchers has developed a new catalyst to turn them into high-quality liquid hydrocarbons. These materials can serve as the base for other products or can be useful as-is.

Liquidizing the assets

“Our team is delighted to have discovered this new technology that will help us get ahead of the mounting issue of plastic waste accumulation,” said Kenneth Poeppelmeier, a paper co-author from Northwestern University.

“Our findings have broad implications for developing a future in which we can continue to benefit from plastic materials, but do so in a way that is sustainable and less harmful to the environment and potentially human health.”

The upcycling method relies on a new catalyst the team developed. It is constructed from perovskite nanocubes studded with platinum nanoparticles. Perovskite was chosen because it remains stable under high temperatures and pressures, and is also a very good material for energy conversion (perovskite is the main material used for several types of solar panels). To deposit nanoparticles onto the nanocubes, the team used atomic layer deposition, a technique developed at Argonne National Laboratory that allows precise control of nanoparticles.

Under moderate pressure and temperature conditions, the catalyst breaks down plastics into high-quality liquid hydrocarbons. The team explains that these substances could be used in motor oil, lubricants, or waxes, or further processed to make ingredients for detergents and cosmetics.

It’s the first plastic recycling or upcycling method that is able to reach this end product. Commercially-available catalysts today generate lower quality products with many short hydrocarbons, which are of limited usefulness. Classic melt-and-reprocess recycling results lower-value plastic that is not as structurally strong as the original material.

Plastics are so resilient because on an atomic level, they have a lot of carbon atoms linked to other carbon atoms — and this chemical bond is very strong (has a lot of energy). As a rule of thumb, it takes a greater amount of energy than that contained in a bond to break it. There aren’t many things in nature that can completely break down plastic, but there are enough sources of energy to degrade it into microplastics. Given that we produce around 380 million tons of plastic yearly, and that over 75% is thrown away after one use (ending up in waterways and the ocean), it adds up to a lot of microplastics.

“There are certainly things we can do as a society to reduce consumption of plastics in some cases,” said Aaron D. Sadow, a scientist in the Division of Chemical and Biological Sciences at Ames Laboratory and the paper’s co-lead author. “But there will always be instances where plastics are difficult to replace, so we really want to see what we can do to find value in the waste.”

The team says that their approach produces far less waste than comparable processes, and virtually no emissions compared to recycling methods that involve melting plastic.

The paper “Upcycling Single-Use Polyethylene into High-Quality Liquid Products” has been published in the journal ACS Central Science.

Seafloor Alvin Image.

New deep-water microbes have the skills to help fight climate change

Newly-discovered deep-water microbes could help us clean CO2 out of the air.

Seafloor Alvin Image.

View of the seafloor.
Image credits Brett Baker / University of Texas at Austin.

A bunch of microbes collected at around 2,000 metres (6,562 feet) below the surface of the surface of the Gulf of California might have a strong appetite for pollutants — including CO2 and crude oil. The team describing these organisms hopes they can be used to lessen our environmental footprint.

Tiny helpers

“This [discovery] shows the deep oceans contain expansive unexplored biodiversity, and microscopic organisms there are capable of degrading oil and other harmful chemicals,” says lead researcher and marine scientist Brett Baker from the University of Texas at Austin.

The microbes live under water in very harsh conditions. Besides sheer pressure, they also have to endure temperatures of around 200 degrees Celsius (392 degrees Fahrenheit) generated by subterranean vulcanic activity.

With this in mind, the wealth of microbes the team recovered is really impressive. A total of 551 separate genomes were identified in the samples — including 22 that had never been recorded before. Better yet, the bugs were observed chowing down on hydrocarbons (such as methane and butane) for their meals.

“Beneath the ocean floor huge reservoirs of hydrocarbon gases – including methane, propane, butane and others – exist now, and these microbes prevent greenhouse gases from being released into the atmosphere,” Baker explains.

This makes their diet very unusual — and valuable. The microbes could help in cleaning up pollution in the future, if we can find a way to harness or copy their abilities. Another very surprising discovery is how genetically different these organisms are from anything we’ve ever seen before. The 22 newly-discovered species are so unique that they could require us ‘adding’ a new branch on the tree of life.

The findings are still new, and more work will be needed to determine where these lifeforms fit into the larger picture, as well as any of their potential uses.

“The tree of life is something that people have been trying to understand since Darwin came up with the concept over 150 years ago, and it’s still this moving target at the moment,” says Barker.

Recent improvements in DNA sequencing and computer software technology, however, are helping clear the picture. The microbes discovered in this study can improve our understanding of biology as well as – potentially – keep a lid on pollutants in the environment.

Also notable is the craft which collected the microbes — it was the Alvin submersible, the same vehicle that explored the wreck of the Titanic bank in 1986.

The paper “Expansive microbial metabolic versatility and biodiversity in dynamic Guaymas Basin hydrothermal sediments” has been published in the journal Nature Communications.

What is petroleum, and where does it come from?

If you’re reading something related to fossil fuels here on ZME Science, chances are it somehow ties into the issue of pollution or global warming. Both are really important topics of discussion, especially right now as people all over the world band together to fix the very real, very dangerous consequences our fossil-fuel-centric economies are having on the climate.

Oil barrels.

Image credits Flickr / Olle Svensson.

But it’s undeniable that fossil fuels allowed our societies to dramatically change in a very short span of time. Using them, people could bring much more energy to bear in shaping our environment than previously possible. Energy means tractors pull plows instead of oxen, cars instead of carriages, steel mills instead of blacksmiths, iPhones instead of carrier pigeons. More available energy makes everybody richer, better fed, and longer-living than ever before.

We’re now at a point where we can/should opt out of fossil fuels and into other, cleaner and more efficient sources of energy; but we’re not going to talk about that right now. Today we’re going to take a look at what fossil fuels are to understand why they had such an effect on society. And we’ll be starting with the one we’re probably most familiar with in our day-to-day life.

What is petroleum

Petroleum (from the old Greek petra, meaning stone and oleum meaning oil), also known as crude oil, is a fluid mix of liquid and gaseous hydrocarbons, inorganic chemical elements, and physical impurities. It usually comes laced with a hearty serving of bacteria to boot. While romantic images or old-timey movies about daring derrickmen show all crude oil to be pitch-black, it’s not uncommon to see dark brown oil or for it to take yellow, red, even green hues based on its chemical composition.

Green petroleum from McClintock Well 1, the oldest oil well still in production.
Image credits Drake Well Museum.

Oil composition actually varies so widely that one of the most used crude oil classification standards is by production area (e.g. Oman-Tapis oil, West Texas Intermediate oil, so on). Two other important classifications systems rely on density (light/heavy oil) or sulfur content (sweet/sour).

Crude oil is one of the most important hydrocarbons today, and it literally keeps our industries running both as an energy source and a critical raw material. It forms deep underground, and (generally) only rarely makes an appearance topside without our help. Its choice of neighborhood, chemical composition, and the fact that crude oil has a bit of a body odor issue, all come down to:

How it forms

[panel style=”panel-info” title=”The short of it:” footer=””]

    1. Deposition: a large quantity of organic matter winds up in a (geologically-speaking) confined area.
    2. Burial: this matter gets buried under sediment, and subsequently ‘sinks’ lower into the crust.
    3. Diagenesis: subjected to extreme pressure and high temperatures, this matter gets cooked into kerogen — a wax-like substance which is basically baby-crude-oil.
    4. Catagenesis / Cracking: if the right window of pressure and heat is maintained on the kerogen, it will be further cooked into fluid hydrocarbons (oil and gas).
    5. Reservoir formation: these new hydrocarbons, being fluid and less dense, are pumped up by the weight of rocks pressing down on them — until they hit a rock they can’t pass through and form a deposit.

[/panel]

Steps 1&2 — Deposition and Burial

Like all other fossil fuels, crude oil is formed from things which used to be alive a long time ago. In theory, any dead plant or animal can turn into petroleum over millions of years but it’s mostly algae, plankton, and zooplankton which formed the crude oil we use today. What those three have in common (and lends them well to oil-formation) is that they’re aquatic. Living in the ocean helps a lot with points 1. and 2.: on the one hand, marine environments are teeming with nutrients and usually support a lot of biomass. On the other hand, there’s more sediment in watery environments than on dry land (think of how much new soil the Nile deposits every time it floods).

Mississippi Delta Sediment Plume.

Or the Mississippi, even when it’s not flooding.
Image credits NASA Earth Observatory.

Making crude oil is kinda similar to making wine in that you need to let it sit but not breathe, or it will spoil — so both of these factors are critical for its formation. The process needs a lot of fresh (well, fresh-ish) organic matter. Since there are so many critters living in oceans, these environments can deliver the huge quantities of biomass needed (things die and sink to the bottom faster than bacteria can decompose them). Oceans can also muster the sediments required to cover biomass before it rots away in less-abundant areas. So overall, virtually all of the most important oil deposits formed on the bottom of ancient oceans and seas (which may be dry land today).

While there’s nothing explicitly prohibiting dry land environments from forming oil, the odds are stacked very highly against them. The main problem is that sediment mobility is severely limited on land compared to the ocean, so there’s nothing to insulate dead biomass from oxygen. For crude oil to form on land, you generally need a fast movement of sediments — think massive floods, landslides, mudflows, that sort of thing — or watery, muddy areas such as lakes and marshes. Plant resin can also kerogenize. However, deposits formed on dry land generally tend to form coal (from harder-to-decompose wood,) and their share in the global crude oil reserve is likely modest.

Step 3 — Diagenesis

As new sediments fall to the ocean’s floor over millions of years, their weight pushes down on our intrepid biomass deposit formed in steps 1&2. We’re talking pretty big pressures here — imagine holding a column of rock, gravel, sand a few kilometers/miles high on your shoulders, topped by an even higher column of water — which compress that matter hard enough for it to heat up. Under such conditions, the chemical bonds in the biomass start to break down and re-form into new, more heat-and-pressure-stable compounds.

Chlorophyll V-porphyrin.

Vanadium porphyrin in petroleum (left) and chlorophyll a (right).
Image via Wikimedia.

Long-chain biopolymers (such as those in proteins or carbohydrates) are the first ones to break down. The resulting bits then go on to mix with sediments to form rocks rich in organic carbon or shed water and simple hydrocarbon molecules (such as methanol), and condense into new polymers. As time passes, certain elements such as hydrogen, oxygen, nitrogen, and sulphur tend to be weeded out of the mix, and the polymers tend towards aromatization (they form rings). These are denser (same material in a smaller space,) so they can better withstand the pressure. Then, the rings stack onto each other in sheets, increasing density even more.

This early stage of transformation results in a waxy substance known as kerogen, and a tar-like material known as bitumen.

Step 4 — Catagenesis / Cracking

A structure rich in kerogen and bitumen is known as a ‘source rock’ because this is where the oil will come from. As it keeps sinking lower into the crust, the kerogen in our source rock gets subjected to even more pressure, but that’s OK because it’s so dense that it can take it. However, it also gets hotter, and that’s what will finally turn it into petroleum.

Crude oils.

Light and medium crude oils from the Caucasus, the Middle East, Arabia, and France.
Image credits Wikimedia / Glasbruch2007.

What we perceive as heat is a motion of particles — the hotter something is, the more its atoms will bounce around and into each other. Heat is, if you zoom in close enough, kinetic energy. So when you pump heat into the nicely-stacked sheets of polymers in our kerogen, you make their atoms want to move around.  Eventually, if you pump enough heat into them, the structures become too energetic to remain stable and break apart into progressively smaller bits — heat “cracks” them open.

Ambiental pressure and temperature during the cracking process determine what the kerogen does: if temperatures are too low, nothing cracks. If temperatures are too high, oil gets shredded into short polymers and you get natural gas. The sweet-spot, or “oil window” for geologists, is somewhere between 50-150°C (122-302°F) depending on things like pressure and how rapidly the rock is warmed up.

Step 5 — Reservoir formation

At this point, the oil and gas are both liquid and mixed together, like an unopened can of soda. Being fluid and much less dense than the rocks around them, this hydrocarbon cocktail resulted from cracking will try to work its way upwards above to the surface.

Surface oil seep Slovakia.

Natural petroleum spring in Slovakia.
Image credits Wikimedia / Branork.

There are rocks all around it, however, so the oil can’t form lakes or rivers per say but has to travel through the pores and cracks of surrounding rocks in its merry way to the surface. Some rocks, such as sandstone or limestone, are especially porous and lend themselves well to transporting crude oil.

What usually happens, however, is that oil gets trapped under a layer of rock it can’t pass through, and will wait there until a drill head comes a-knocking.

To sum it up

So, to go from a dinosaur (more likely from a bunch of plankton) all the way to petroleum, you need a lot of time and quite a fortunate series of events: first, you need a lot of stuff to die in just the right spot and get buried under sediment in a hurry. This stack of biomass needs to get squished and baked into a source rock full of juicy bitumen and kerogen and then heated up — but not too much — to form oil. All of this needs to take place under a porous and permeable (meaning the pores are connected to each other so they can act like tiny pipelines) rock for the oil to travel through and accumulate in. And everything has to be covered with a cap rock (a seal), or some other mechanism has to be in place to prevent this oil from spilling up to the surface.

The good and bad about petroleum

So you know how plants like to hang around and photosynthesize and all that? Well, think of burning fossil fuels as reverse photosynthesis and you’re not far off from the mark. That’s what makes fossil fuels both awesome and awful at the same time, and here’s why:

A burning oil well in the Rumaila oilfields, Kuwait.

It’s because this thing burns with a blaze.
Kuwaiti firefighters fight to secure a burning oil well in the Rumaila oilfields, set ablaze by Iraqi military forces, 2003.
Image credits United States Marine Corps.

Photosynthesis requires a lot of energy: since oxygen loves binding to stuff and carbon is pretty into being bound, too, it takes a lot of oomph to pull them apart. What plants do is use solar energy to break CO2, munch on the carbon atom, and throw out the oxygen. This creates an energy imbalance since that oxygen really wants to get back with his old spark, the carbon atom — so plant matter, in effect, acts like a battery for carbon and the energy used in photosynthesis.

Any decent-sized petroleum deposit is formed from immense quantities of biomass, totaling millions possibly even trillions hours’ worth of photosynthesis, and the sum energy imbalance generated through them. When we burn oil, we re-combine carbon with oxygen and take that energy back.

The good news is that you extract the lion’s share of that initial energy (stored over the plants’ entire lifetimes) in a few moments — so fossil fuels are a very dense source of energy, an order of magnitude more powerful than what firewood or muscle can generate. The bad news is that you also release all those carbon atoms (stored over the plants’ entire lifetimes) in a few moments — so fossil fuels are a very dense source of greenhouse gasses.

Apart from use as fuel, petroleum is a cornerstone in industry. The pharmaceutical, chemical, and material industries, in particular, rely heavily on crude oil as the main source of a wide range of organic compounds. So even if we decouple our energy sector from oil, we’re sure to see it around for a long time to come.

NASA plans to send an autonomous submarine into space — for a very good reason

NASA plans to explore Saturn’s moon Tian with an unlikely type of vehicle: a submarine. The agency is working on the design of an autonomous submersible that will explore the liquid hydrocarbon oceans of the moon.

The current design of the craft.
Image credits NASA.

The vehicle will have to endure bone-shattering cold as it will peer through the liquid methane and ethane oceans that cover the moon’s surface, relaying valuable data back to Earth, announced Jason Hartwig at the NASA Innovative Advanced Concepts (NIAC) Symposium last week. Its blueprints include a huge communications “fin” on the back of the sub that will allow it to cover the 1,492 million kilometer (886 million miles) span of space to communicate directly with Earth.

The submarine will be 6 meters (20 feet) long and will use Titan’s liquid methane instead of water in its ballast system. Its array of instruments will include meteorological tools, a sonar and radar, and an array of other sensors including cameras to take snapshots of what’s going on on the frigid moon.

The vehicle will be optimized to be as fuel efficient as possible, as chances of re-fueling are slim on Titan.

Ten thousand leagues over the ocean

Titan’s hydrocarbon oceans may be incredibly cold and seem strange to us, but scientists are interested in learning all they can about it as it resembles the conditions we think shaped an early Earth. It’s the only other known body in the Solar System that has stable, liquid seas on its surface. Titan’s atmosphere also functions similarly to our own, having its own hydrological (hydrocarbon?) cycles that dictate how liquids move from fresh to salt or from a gas, to a liquid, or a solid.

Artist rendering of a possible submersible bot exploring one the floor of one of Titan’s methane lakes. Image: NASA JPL

Artist rendering of a possible submersible bot exploring one the floor of one of Titan’s methane lakes. Image: NASA JPL

NASA wants to send a sub there because of its versatility. It can be used to measure waves, atmospheric composition and wind speeds on the surface, but can also analyze the composition of its seas or take sea floor samples after it submerges.

“If you can get below the surface of the sea, and get all the way down to the bottom in certain areas, and actually touch the silt that’s at the bottom, and sample it and learn what that’s made of, it’ll tell you so much about the environment that you’re in,” said Michael Paul from Penn State University, one of the researchers working on the project.

The submersible will also look very any signs of extraterrestrial life, as some experts believe the hydrocarbon soup can act as a replacing solvent for water to foster life.

“Think about life on Earth—we’re all either in water or we’re fancy bags of water,” says astrobiologist Kevin Hand of the Jet Propulsion Laboratory. “On Titan, life in the lakes would be ‘bags’ of liquid methane and/or ethane. That 90[Kelvin] liquid would be the solvent and then whatever is dissolved into the lakes would be the material that’s used to build the other components needed for life, and to power metabolism.”

The design efforts for the craft are on hold for now, as the agency awaits for more information on the moon’s oceans from the Cassini probe. New information about the depths, pressures, and temperatures of Titan’s oceans will be used to better tailor the sub to the environment it will function in. NASA hopes to reassess the project by March 2017.

But after the design is finalized and the sub built, that’s when the real waiting begins — its first mission has been tentatively scheduled for 2038.

That’s quite a wait.To help us pass the time, the guys and gals from NASA put together this teaser for the submarine. Enjoy!

 

titan saturn dune

Saturn’s Moon Titan has Strong Winds and Hydrocarbon Dunes

New experimental research found that Saturn’s largest Moon, Titan, has much stronger winds than previously believed. These rogue winds actually shape the hydrocarbon dunes observed on its surface.

titan saturn dune

Cassini radar sees sand dunes on Saturn’s giant moon Titan (upper photo) that are sculpted like Namibian sand dunes on Earth (lower photo). The bright features in the upper radar photo are not clouds but topographic features among the dunes.
Credit: NASA

Titan is, along with Earth, one of the few places in the solar system known to have fields of wind-blown dunes on its surface. The only other ones are Mars and Venus. Now, researchers led by Devon Burr, an associate professor in Earth and Planetary Sciences Department at the University of Tennessee, Knoxvillehas haves hown that previous estimates regarding the strength of these winds are about 40% too low. In other words, Titan has much stronger winds than previously believed.

Titan is the only known moon with a significant atmosphere, and just like Earth’s atmosphere, it is rich in nitrogen. The geological surface of the moon is also very interesting, with active geological processes shaping it. The Cassini spacecraft captured spectacular images of seas on Titan, but before you get your hopes up, you should know that the seas are not made of water, but of liquid hydrocarbons. However, many astronomers believe that Titan actually harbors an ocean of liquid water, but below its frozen surface – the surface temperature is –290° F (–180° C). It’s actually so cold, that even the sand on Titan is not like the sand on Earth – the sand is also made from solid hydrocarbons. But the thing is, we don’t really know where those grains come from.

“It was surprising that Titan had particles the size of grains of sand — we still don’t understand their source — and that it had winds strong enough to move them,” said Burr. “Before seeing the images, we thought the winds were likely too light to accomplish this movement.”

But the biggest mystery was the shape of the dunes. The Cassini data showed that the predominant winds that shaped the dunes blew from east to west. However, the streamlined appearance of the dunes around obstacles like mountains and craters  suggested that the winds blow from the opposite direction.

In order to figure this out, Burr and his team spent six years refurbishing a defunct NASA high-pressure wind tunnel to recreate Titan’s surface conditions. After the restauration was complete, they used 23 different varieties of sand in the wind tunnel to compensate for the fact that we don’t know exactly what the sand on Titan is made from. The first thing they found is that for all the likely varieties of sand, the winds have to be much stronger than believed.

“Our models started with previous wind speed models but we had to keep tweaking them to match the wind tunnel data,” said Burr. “We discovered that movement of sand on Titan’s surface needed a wind speed that was higher than what previous models suggested.”

They also found an explanation for the shape of the dunes.

“If the predominant winds are light and blow east to west, then they are not strong enough to move sand,” said Burr. “But a rare event may cause the winds to reverse momentarily and strengthen.”

According to the models, this wind reversal takes place every Saturn year – which is 30 Earth years. This also explains why Cassini missed this reversal.

“The high wind speed might have gone undetected by Cassini because it happens so infrequently.”

Journal Reference:

  1. Devon M. Burr, Nathan T. Bridges, John R. Marshall, James K. Smith, Bruce R. White, Joshua P. Emery. Higher-than-predicted saltation threshold wind speeds on Titan. Nature, 2014; DOI: 10.1038/nature14088

Ingredient of Household Plastic Found on Saturn Moon

NASA’s Cassini spacecraft has detected propylene, a chemical used greatly in everyday life, in things like food-storage containers, car bumpers and other consumer products, on Saturn’s Moon Titan. I really recommend watching the video below, as it explains the situation in great detail:

A small amount of propylene was identified in Titan’s lower atmosphere by Cassini’s Composite Infrared Spectrometer (CIRS); the device measures infrared emissions given away by Saturn and Saturn’s moons in a similar way to the way our hands feel a fire’s warmth. Every gas has a unique thermal fingerprint, and based on that, CIRS can identify pretty much every gas. The only problem is isolating the signal from other, interfering signals.

“This measurement was very difficult to make because propylene’s weak signature is crowded by related chemicals with much stronger signals,” said Michael Flasar, Goddard scientist and principal investigator for CIRS. “This success boosts our confidence that we will find still more chemicals long hidden in Titan’s atmosphere.”

This detection brings a valuable piece of the puzzle, a piece which was sought after since the Voyager 1 spacecraft and the first-ever close flyby of this moon in 1980. Voyager identified many of the gases in Titan’s hazy brownish atmosphere as hydrocarbons, a class of organic chemical compounds composed only of the elements carbon (C) and hydrogen (H) which compose most of the petroleum and natural gas.

False-color images, made from data obtained by NASA's Cassini spacecraft, shows clouds covering parts of Saturn's moon Titan in yellow.

False-color images, made from data obtained by NASA’s Cassini spacecraft, shows clouds covering parts of Saturn’s moon Titan in yellow.

In Titan’s atmosphere, hydrocarbons form after sunlight breaks apart methane, the second-most plentiful gas in that atmosphere. The new fragments can bond together, forming chains of 2, 3, or even more carbons – ethane and propane for example, can be created this way.

As Cassini continued to discover more and more hydrocarbons on Titan, propylene remained elusive until the CIRS analysis.

“I am always excited when scientists discover a molecule that has never been observed before in an atmosphere,” said Scott Edgington, Cassini’s deputy project scientist at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, Calif. “This new piece of the puzzle will provide an additional test of how well we understand the chemical zoo that makes up Titan’s atmosphere.”

For more information on the Cassini mission, visit NASA’s page.

Via NASA.

titan methane haze

Earth’s prehistoric atmosphere was covered in a haze similar to Saturn’s moon, Titan

titan methane haze If you think today’s urban air, thickened with noxious smog, is terrible, just imagine how the Earth was filled in a shroud of hydrocarbons some 2.5 billion years ago. Back then, a haze dominated by methane engulfed the atmosphere such that light could barely reach the ground, similarly to what can be seen today on Titan, Saturn’s moon. A team of researchers modeled Earth’s atmosphere from its early history and found there was a period in which the planet’s atmosphere regularly switched between  “organic haze” (methane dominant) and “haze-free” (oxygen dominant), before finally stabilizing in an oxygenated atmosphere, allowing complex life to form.

Researchers at Newcastle University dissected Earth’s ancient atmosphere by analyzing the chemical make-up of a core of ocean sediment deposited on a region of South Africa, flooded between 2.65 and 2.5 billion years ago.  During this time the only life on Earth was formed by microbes, trapped from further evolving in complexity by a methane bond. These tiny microbes, however, were the ones which finally turned the atmosphere around, as they steadily released oxygen through photosynthesis. It was a full-out war actually, with victories and defeats on both sides.

During this 150 million year time frame, researchers found that the atmosphere shifted steadily between methane-rich and methane-poor composition, the latter most likely causing the dissipation of the haze, little by little.

“Models have previously suggested that the Earth’s early atmosphere could have been warmed by a layer of organic haze. Our geochemical analyses of marine sediments from this time period provide the first evidence for such an atmosphere.”

“However, instead of evidence for a continuously ‘hazy’ period we found the signal flipped on and off, in response to microbial activity.”, said Dr. Aubrey Zerkle from the School of Civil Engineering and Geosciences at Newcastle University.

Thus, every few million years or so, the atmosphere altered between states, due to irregular methane dumps by organisms, most likely triggered by different amounts of nutrients available in the ocean.The researchers back up the evidence presented in the study with NASA models of Earth’s ancient atmosphere, which demonstrate the effect of early methane levels.

“What is most surprising about this study is that our data seems to indicate the atmospheric events were discrete in nature, flip-flopping between one stable state into another,” explains co-author Dr Farquhar.

“This type of response is not all that different from the way scientists think climate operates today, and reminds us how delicate the balance between states can be.”

The findings were published in the journal Nature Geosciences.