Nav: Home

Iron-silica particles unlock part of the mystery of Earth's oxygenation

August 07, 2018

The oxygenation of Earth's atmosphere was thanks, in part, to iron and silica particles in ancient seawater, according to a new study by geomicrobiologists at the University of Alberta. But these results solve only part of this ancient mystery.

Early organisms called cyanobacteria produced oxygen through oxygenic photosynthesis, resulting in the oxygenation of Earth's atmosphere. But cyanobacteria needed protection from the sun's UV radiation in order to evolve. That's where iron and silica particles in ancient seawater come in, according to Aleksandra Mloszewska, a former PhD student who conducted this research under the supervision of Kurt Konhauser, professor in the Department of Earth and Atmospheric Sciences, and George Owttrim, professor in the Department of Biological Sciences.

The research team characterized the effect of UV stress on cyanobacteria and the degree of radiation through the seawater medium through a combination of microbiological, spectroscopic, geochemical and modelling techniques. Their results show that the presence of high silica and iron concentrations in early sea water allowed for the formation of iron-silica precipitates that remained suspended in the ocean for extended periods of time.

"In effect, the iron-silica particles acted as an ancient 'sunscreen' for the cyanobacteria, protecting them from the lethal effects of direct UV exposure," said Konhauser, the senior author from UAlberta. "This was critical on the early Earth before a sufficiently thick ozone layer was established that could enable marine plankton to spread across the globe, as is the case today."

More missing pieces

But, the researchers explain, the iron-silica rich precipitates tell only part of the story.

"The accumulation of atmospheric oxygen from cyanobacterial facilitated the evolution of oxygen-based respiration and multicellular organisms," says Owttrim. But the reason for the large amount of time that it took for free oxygen to accumulate permanently in the atmosphere after the initial evolution of cyanobacteria remains a mystery.

While iron-silica precipitates would have allowed early cyanobacteria to survive, UV radiation would still have prevented their widespread growth.

"It is likely that early cyanobacteria would not have been as productive as they are today because of the effects of UV stress. Until the accumulation of sufficient cyanobacteria-derived oxygen allowed a more permanent means of protection to develop, such as an ozone layer, UV stress may have played an even more important role in shaping the structure of the earliest ecosystems," explained Mloszewska.

These new findings are helping researchers to understand not only how early cyanobacteria were affected by the high level of radiation on the early Earth but also the environmental dynamics that affected the oxygenation history of our atmosphere.

"These findings could also be used as a case study to help us understand the potential for the emergence of life on other planets that are affected by elevated UV radiation levels, for example Earth-sized rocky planets within the habitable zones of nearby M-dwarf star systems like TRAPPIST-1, Proxima Centauri, LHS 1140 and Ross 128 among others," said Mloszewska.

The research was conducted in collaboration with colleagues at the University of Tuebingen and Yale University and was supported by the National Science and Research Council of Canada, and by the NASA Alternative Earths Astrobiology Institute. The paper, "UV radiation limited the expansion of cyanobacteria in early marine photic environments" is published in Nature Communications.
-end-


University of Alberta

Related Radiation Articles:

Cloudy with a chance of radiation: NASA studies simulated radiation
NASA's Human Research Program (HRP) is simulating space radiation on Earth following upgrades to the NASA Space Radiation Laboratory (NSRL) at the US Department of Energy's Brookhaven National Laboratory.
Visualizing nuclear radiation
Extraordinary decontamination efforts are underway in areas affected by the 2011 nuclear accidents in Japan.
Measuring radiation damage on the fly
Researchers at MIT and elsewhere have found a new way to measure radiation damage in materials, quickly, cheaply and continuously, using transient grating spectroscopy.
Radiation that knocks electrons out and down, one after another
Researchers at Japan's Tohoku University are investigating novel ways by which electrons are knocked out of matter.
Novel advancements in radiation tolerance of HEMTs
When it comes to putting technology in space, size and mass are prime considerations.
Radiation-guided nanoparticles zero in on metastatic cancer
Zap a tumor with radiation to trigger expression of a molecule, then attack that molecule with a drug-loaded nanoparticle.
Graphene is both transparent and opaque to radiation
A microchip that filters out unwanted radiation with the help of graphene has been developed by scientists from the EPFL and tested by researchers of the University of Geneva (UNIGE).
Radiation causes blindness in wild animals in Chernobyl
This year marks 30 years since the Chernobyl nuclear accident.
No proof that radiation from X rays and CT scans causes cancer
The widespread belief that radiation from X rays, CT scans and other medical imaging can cause cancer is based on an unproven, decades-old theoretical model, according to a study published in the American Journal of Clinical Oncology.
Some radiation okay for expectant mother and fetus
During pregnancy, approximately 5 to 8 percent of women sustain traumatic injuries, including fractures and muscle tears.

Related Radiation Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Digital Manipulation
Technology has reshaped our lives in amazing ways. But at what cost? This hour, TED speakers reveal how what we see, read, believe — even how we vote — can be manipulated by the technology we use. Guests include journalist Carole Cadwalladr, consumer advocate Finn Myrstad, writer and marketing professor Scott Galloway, behavioral designer Nir Eyal, and computer graphics researcher Doug Roble.
Now Playing: Science for the People

#529 Do You Really Want to Find Out Who's Your Daddy?
At least some of you by now have probably spit into a tube and mailed it off to find out who your closest relatives are, where you might be from, and what terrible diseases might await you. But what exactly did you find out? And what did you give away? In this live panel at Awesome Con we bring in science writer Tina Saey to talk about all her DNA testing, and bioethicist Debra Mathews, to determine whether Tina should have done it at all. Related links: What FamilyTreeDNA sharing genetic data with police means for you Crime solvers embraced...