Rare 2.5-Billion-year-old Rocks Reveal Hot Spot of Sulfur-breathing Bacteria Sulfur-Dependent Life Forms Thrived in Oceans

Rare 2.5-Billion-year-old Rocks Reveal Hot Spot of Sulfur-breathing Bacteria Sulfur-Dependent Life Forms Thrived in Oceans
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  pdfcrowd.comopen in browserPRO version Are you a developer? Try out the HTML to PDF API Featured Research from universities, journals, and  other organizations Date:Source:Summary: November 6, 2014University of MarylandBiogeochemical signals in 2.5-billion-year-old carbonate rocks fromBrazil reveal that sulfur-consuming bacteria were active at a time whenocean sulfur levels were low. Geologists focused on sulfur isotopes inancient carbonate rocks. The study sheds light on Earth's earlyatmospheric chemistry. Share This  Rare 2.5-billion-year-old rocks reveal hot spot of sulfur-breathing bacteria: Sulfur-dependent life forms thrived in oceans Save/Print :                  Share : Breaking News: Comet Flyby Effects On Martian Atmosphere   Email to a friend   Facebook   Twitter    LinkedIn   Google+   Print this page  Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins Mobile :   iPhone    Android    Web Follow :   Facebook    Twitter     Google+ Subscribe :   RSS Feeds    Email Newsletters  HEALTHPHYSICAL/TECHENVIRONMENTSearch Enter keyword or phrase ... QUIRKYSOCIETY/EDUCATION  pdfcrowd.comopen in browserPRO version Are you a developer? Try out the HTML to PDF API Credit: Iadviga Zhelezinskaia [Click to enlarge image] W Related Articles Shown at 50X magnification, whitish pyrite -- iron sulfite or 'fool's gold' -- isembedded in gray carbonate rock, formed in a shallow sea some 2.5 billion yearsago. Stable isotopic analysis of this and other samples from the same coreproduced the first evidence of sulfur-respiring bacteria in rocks of this type and age. riggle your toes in a marsh's mucky bottom sediment and you'llprobably inhale a rotten egg smell, the distinctive odor of hydrogensulfide gas. That's the biochemical signature of sulfur-usingbacteria, one of Earth's most ancient and widespread life forms.  Among scientists who study the early history of our 4.5billion-year-old planet, there is a vigorous debate aboutthe evolution of sulfur-dependent bacteria. These simpleorganisms arose at a time when oxygen levels in theatmosphere were less than one-thousandth of whatthey are now. Living in ocean waters, they respired (or breathed in) sulfate, a sulfur and oxygen compound,instead of free oxygen molecules. But how did thatsulfate reach the ocean, and when did it becomeabundant enough for living things to use it?New research by University of Maryland geologydoctoral student Iadviga Zhelezinskaia offers asurprising answer. Zhelezinskaia is the first researcher to analyze the biochemical Related Topics Plants & AnimalsEarth & ClimateFossils & RuinsMore: Related Stories Life in Earth’s Primordial SeaWas Starved for Sulfate Nov. 7, 2014 — Earth’s ancientoceans held much lower concentrations of sulfate -- a keybiological nutrient -- than previously recognized,according to new research. The findings paint a newportrait of our ...    full story  Mars: Meteorites Yield Cluesto Red Planet's EarlyAtmosphere  Apr. 16, 2014 — Geologistsanalyzed 40 meteorites that fell toEarth from Mars to understand thehistory of the Martian atmosphere. 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Try out the HTML to PDF API signals of sulfur compounds found in 2.5 billion-year-old carbonate rocks from Brazil.The rocks were formed on the ocean floor in a geologic time known as theNeoarchaean Eon. They surfaced when prospectors drilling for gold in Brazil punched ahole into bedrock and pulled out a 590-foot-long core of ancient rocks.In research published Nov. 7, 2014 in the journal Science , Zhelezinskaia and three co-authors -- physicist John Cliff of the University of Western Australia and geologists Alan Kaufman and James Farquhar of UMD -- show that bacteria dependent on sulfatewere plentiful in some parts of the Neoarchaean ocean, even though sea water typically contained about 1,000 times less sulfate than it does today. The samples Iadviga measured carry a very strong signal that sulfur compounds wereconsumed and altered by living organisms, which was surprising, says Farquhar. She also used basic geochemical models to give an idea of how much sulfate was inthe oceans, and finds the sulfate concentrations are very low, much lower thanpreviously thought. Geologists study sulfur because it is abundant and combines readily with other elements, forming compounds stable enough to be preserved in the geologic record.Sulfur has four naturally occurring stable isotopes -- atomic signatures left in the rockrecord that scientists can use to identify the elements' different forms. Researchersmeasuring sulfur isotope ratios in a rock sample can learn whether the sulfur camefrom the atmosphere, weathering rocks or biological processes. From that informationabout the sulfur sources, they can deduce important information about the state of theatmosphere, oceans, continents and biosphere when those rocks formed.Farquhar and other researchers have used sulfur isotope ratios in Neoarchaean rocksto show that soon after this period, Earth's atmosphere changed. Oxygen levelssoared from just a few parts per million to almost their current level, which is around 21percent of all the gases in the atmosphere. The Brazilian rocks Zhelezinskaia sampledshow only trace amounts of oxygen, a sign they were formed before this atmosphericchange.With very little oxygen, the Neoarchaean Earth was a forbidding place for most modernlife forms. The continents were probably much drier and dominated by volcanoes thatreleased sulfur dioxide, carbon dioxide, methane and other greenhouse gases.Temperatures probably ranged between 0 and 100 degrees Celsius (32 to 212 degreesFahrenheit), warm enough for liquid oceans to form and microbes to grow in them.Rocks 2.5 billion years old or older are extremely rare, so geologists' understanding of the Neoarchaean are based on a handful of samples from a few small areas, such asWestern Australia, South Africa and Brazil. Geologists theorize that Western Australiaand South Africa were once part of an ancient supercontinent called Vaalbara. TheBrazilian rock samples are comparable in age, but they may not be from the samesupercontinent, Zhelezinskaia says.Most of the Neoarchaean rocks studied are from Western Australia and South Africaand are black shale, which forms when fine dust settles on the sea floor. The Brazilianprospector's core contains plenty of black shale and a band of carbonate rock, formed Strange & Offbeat Stories Rich Ore Deposits Linked toAncient Atmosphere Nov. 19, 2009 — Much of our planet's mineral wealth wasdeposited billions of years ago whenEarth's chemical cycles weredifferent from today's. Usinggeochemical clues from rocks nearly3 billion ...    full story    Plants & Animals more related stories   A/C Came Standard on Armored Dinosaur Models  Genes Contribute to Behavior DifferencesBetween Fierce and Friendly Rats  New Zealand's Moa Were Exterminated by anExtremely Low-Density Human Population  Scientists Examine Mysterious Tar Mounds inthe West African Deep Ocean  The Tiger Beetle: Too Fast to See: BiologistLooks Into How the Speedy Predator Pursues   pdfcrowd.comopen in browserPRO version Are you a developer? Try out the HTML to PDF API MLAAPAChicago University of Maryland. Rare 2.5-billion-year-old rocks reveal hot spot of sulfur- below the surface of shallow seas, in a setting that probably resembled today'sBahama Islands. Black shale usually contains sulfur-bearing pyrite, but carbonate rocktypically does not, so geologists have not focused on sulfur signals in Neoarchaeancarbonate rocks until now.Zhelezinskaia chose to look at a type of rock that others generally avoided, and whatshe saw was spectacularly different, said Kaufman. It really opened our eyes to theimplications of this study. The Brazilian carbonate rocks' isotopic ratios showed they formed in ancient seabedcontaining sulfate from atmospheric sources, not continental rock. And the isotopicratios also showed that Neoarchaean bacteria were plentiful in the sediment, respiringsulfate and emitted hydrogen sulfide -- the same process that goes on today asbacteria recycle decaying organic matter into minerals and gases.How could the sulfur-dependent bacteria have thrived during a geologic time whensulfur levels were so low? It seems that they were in shallow water, where evaporationmay have been high enough to concentrate the sulfate, and that would make itabundant enough to support the bacteria, says Zhelezinskaia.Zhelezinskaia is now analyzing carbonate rocks of the same age from Western Australia and South Africa, to see if the pattern holds true for rocks formed in other shallow water environments. If it does, the results may change scientists'understanding of one of Earth's earliest biological processes. There is an ongoing debate about when sulfate-reducing bacteria arose and how thatfits into the evolution of life on our planet, says Farquhar. These rocks are telling usthe bacteria were there 2.5 billion years ago, and they were doing somethingsignificant enough that we can see them today. Story Source: The above story is based on materials provided by University of Maryland . Thesrcinal article was written by Heather Dewar. Note: Materials may be edited for content and length. Journal Reference :1. I. Zhelezinskaia, A. J. Kaufman, J. Farquhar, J. Cliff. Large sulfur isotopefractionations associated with Neoarchean microbial sulfate reduction . Science , 2014; 346 (6210): 742 DOI: 10.1126/science.1256211 Cite This Page : In Other News Earth & ClimateFossils & Ruins ... from Science NewsHealth News reyHungry Bats Compete for Prey by JammingSonar   Rare 2.5-Billion-Year-Old Rocks Reveal Hot Spotof Sulfur-Breathing Bacteria: Sulfur-DependentLife Forms Thrived in Oceans  Cockroach Cyborgs Use Microphones to Detect,Trace Sounds  Sustainability, Astrobiology Illuminate Future of Life in the Universe and Civilization on Earth  Mosquitofish Genitalia Change Rapidly Due toHuman Impacts  Tricky Take-Off Kept Pterodactyls Grounded  Genesis of Genitalia: We Have One. Lizards HaveTwo. 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