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Study shows plankton became more diverse during a time when oxygen levels spiked in Earth's earliest breathable atmosphere

Researchers from Ohio State University have found that plankton play a large part in understanding the origin of Earth's first breathable atmosphere.

Matthew Saltzman, study leader and associate professor of earth sciences at Ohio State University, and a team of researchers, have discovered that plankton are the key to understanding the gap between the atmosphere and 500 million-year-old chemical isotopes found in rocks. 

The Ohio State University team previously conducted a study that showed that upward displacements in the Earth's crust 500 million years ago lead to a reverse greenhouse effect, which cooled the oceans producing large plankton blooms, and sent oxygen into the atmosphere. 

Now, Saltzman and his team have discovered how oxygen disappeared from Earth's atmosphere during the Cambrian Period and then reappeared at higher levels. The team was able to quantify exactly how much oxygen was released during this period, and linked the amount of sulfur in oceans at that time with atmospheric carbon dioxide and oxygen. They also looked at how oxygen allowed a large amount of new life to thrive after it returned. 

"We know that oxygen levels in the ocean dropped dramatically [a condition called anoxia] during the Cambrian, and that coincides with the time of a global extinction," said Saltzman. "We still don't know why the anoxia spread all over the world. We may never know. But there have been many other extinction events in Earth's history, and with the exception of those caused by meteor impacts, others likely share elements of this one - changes in the balance of oxygen and carbon dioxide in the atmosphere and oceans."

When searching for what may have allowed oxygen back into the atmosphere and oceans 500 million years ago, researchers found that plankton played a huge role. During that time period, life didn't exist on land and life in the oceans was not as diverse as it is today, which made plankton a very big deal as far as ancient lifeforms go. 

Then a geologic event called the Steptoean Positive Carbon Isotope Excursion (SPICE) occurred, burying large amounts of organic matter in ocean sediments. This pulled carbon dioxide from the atmosphere and in turn, released oxygen. As plankton encounter oxygen, they become more selective for the "light isotope of carbon in carbon dioxide" and absorb it. 

Saltzman and his team looked at isotopes in fossilized plankton found in rocks located in the central United States, China and the Australian outback. They discovered that "plankton revolution," which is when plankton became more diverse, occurred around the same time as the SPICE event. 

"The amount of oxygen rebounded, and so did the diversity of life," said Saltzman. "We were able to bring together independent lines of evidence that showed that if the total oxygen was around 5-10 percent before the SPICE, then it rose to just above modern levels for the first time after the SPICE."

Information that the plankton have provided could be used to possibly deter climate change by changing the chemistry of the ocean to remove carbon dioxide. 

"When it comes to ancient life, they don't sound as exciting as dinosaurs, but the plankton are critical to this story," said Saltzman. 

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What does this mean for Carbon dating accuracy
By JediJeb on 2/23/2011 6:45:20 PM , Rating: 2
As plankton encounter oxygen, they become more selective for the "light isotope of carbon in carbon dioxide" and absorb it.

So there are events like this that can alter the isotope ratios of C12/C13/C14, what does that to do carbon dating accuracy each time it occurs and can we ever be sure we know the accurate age of things if those ratios do change?

Does it also occur for other elemental isotope ratios?

By DesertCat on 2/23/2011 7:35:03 PM , Rating: 4
C14 really isn't something that comes into play in a discussion of the Cambrian. After about ten half-lives there isn't enough C14 left to measure, which limits its use to things dating less than about 57,000 years old. The Cambrian period is 500,000,000 years old. In addition, C14 is generated by the bombardment of nitrogen in the atmosphere by cosmic rays. You will find a few references to some very old things like diamond and petroleum yielding C14 dates, but the C14 source in that case isn't due to atmospheric C14 but due to exposure to a radiogenic source like uranium. In those cases, the little bit of C14 is just above background radiation, so the erroneous dates always come in at around ~50,000 yrs old.

None of rock dating techniques (e.g. Uranium-Lead, Potassium-Argon, etc.) rely on a variable mechanism like C14 generation or variable selectivity by an organism. Scientists rely on the chemical knowledge of crystals like zircon that always exclude lead but can include uranium when they crystallize. Therefore any lead they do find in a zircon crystal is due to radiometric decay of uranium. So... the answer is essentially "no". This does not occur for other elemental isotope ratios.

By kattanna on 2/24/2011 10:29:55 AM , Rating: 3

thats a good short primer on carbon dating and its limitations.

its interesting to see how due to fluctuations in cosmic rays can produce periods where its really hard to date something.

it also talks about the various proxy methods they use to calibrate the historic record for cosmic rays.

its a good read

By JamieH on 2/24/2011 2:23:38 PM , Rating: 2
When measuring lengths, we use different tools for different scales (ruler, micrometer). Each tool works well for a given scale and has an accuracy relative to the scale.

Isotopes used for very long scales might have an accuracy of +/- a few million years, which is ok for these scales. Others will be more usable for short time scales. What is important is picking the right tool for the job and being aware of the degree of error under different circumstances.

Carbon Isotope as a measuring tool is just the one more people have heard. Not surprising as people are usually more interested in what is closest to them in both distance and time. There are exceptions such as celebrities and dinosaurs.

By kattanna on 2/23/2011 4:53:26 PM , Rating: 2
well.. i guess its time to queue the SPICE jokes and DUNE references

Sounds familiar ...
By drycrust3 on 2/23/11, Rating: -1
RE: Sounds familiar ...
By Joz on 2/23/11, Rating: 0
RE: Sounds familiar ...
By drycrust3 on 2/24/2011 3:18:39 PM , Rating: 1
But cute try, trying to tomfoolery some religion into explaining for science...oh wait a sec...I see what you did there...

Do you really see what I did? It seems to me most people don't, because if they did there wouldn't be just 6 comments left here after this length of time, there would be hundreds.
This article contains a very important fact that is easily overlooked: a world wide flood. Like so many other bits of science that confirm what is written in the Bible, this one gets almost no press at all. In fact, it seems to me this fact was mentioned only because it was relevant to another fact: the loss of oxygen in the oceans. What happens if there was a series of massive fissures that leaked water from earth's interior to the surface? The amount of oxygen in the ocean remains the same, but the amount of water has gone up, meaning the concentration of oxygen in the oceans drops!
Since a comet consists of ice, and since comets have a tail, one thought is that if a comet hit earth such that it caused massive fissures and expelled water from the interior, followed by the ice in the comet tail hitting the earth's atmosphere and melting, the result would have appeared to Noah huge geysers appearing around him and as rain, which is exactly what he recorded in the Bible.

I don't expect science to go do research to support my religious views, but so often we are fed this line that there never was a world wide flood and there is nothing in science that supports the claims written in the Bible.
What's wrong with that? What is wrong is the foundation you are building science on is wrong. Why is it that time and time again some evidence turns up that seems to confirm what is written in the Bible, and not seem to support the Theory of Evolution? The most obvious explanation is that the writers of the Bible recorded the facts correctly.
If there was a worldwide flood, why are there land animals alive now that were alive before the flood? Well, obviously they survived the flood. Ok, but how?
Ignoring the answer, because that takes us away from the really important argument: What if what the Bible says is actually correct? Science has adopted the approach of "Evolution = yes, Bible = no", but time and time again the facts tell us "Bible = yes, Evolution = no". Why?

I'm sorry, but this is taking up to much of my time. I'm sure people can fill in the rest of what I would say if they wanted.

RE: Sounds familiar ...
By yxalitis on 2/28/2011 11:01:43 PM , Rating: 2
OK, I'll type slowly for you...
"What happens if there was a series of massive fissures that leaked water from earth's interior to the surface? The amount of oxygen in the ocean remains the same, but the amount of water has gone up, meaning the concentration of oxygen in the oceans drops!"
1. The Earth's interior is molten rock
2. The biblical flood is supposed to have taken place a few thousand years ago, not a few 100,000 years ago.
3. Why would this additional water, wherever it came from, have a different level of oxygen?
Comets are small, much much much smaller then the Earth, any Ice would make no difference to the Earth's ocean levels at all, or produce any noticeable or tangible rain.
4. Oh my, why am I bothering, you are clearly in logic-denial, as are all believers in the true word of the Bible.
Have you read Leviticus?

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