Lost City pumps life-essential chemicals at rates unseen at typical black smokers

The carbonate structures at the Lost City Field include these spires stretching 90 feet tall. The white, sinuous spine is freshly deposited carbonate material. Added digitally to this image are the remotely operated vehicles Hercules and Argus that were used to explore the hydrothermal vent field during an expedition in 2005 funded by the National Oceanic and Atmospheric Administration. - Credit:  Kelley, U of Washington, IFE, URI-IAO, NOAA
The carbonate structures at the Lost City Field include these spires stretching 90 feet tall. The white, sinuous spine is freshly deposited carbonate material. Added digitally to this image are the remotely operated vehicles Hercules and Argus that were used to explore the hydrothermal vent field during an expedition in 2005 funded by the National Oceanic and Atmospheric Administration. – Credit: Kelley, U of Washington, IFE, URI-IAO, NOAA

Hydrocarbons — molecules critical to life — are being generated by the simple interaction of seawater with the rocks under the Lost City hydrothermal vent field in the mid-Atlantic Ocean.

Being able to produce building blocks of life makes Lost City-like vents even stronger contenders as places where life might have originated on Earth, according to Giora Proskurowski and Deborah Kelley, two authors of a paper in the Feb. 1 Science. Researchers have ruled out carbon from the biosphere as a component of the hydrocarbons in Lost City vent fluids.

Hydrocarbons, molecules with various combinations of hydrogen and carbon atoms, are key to cellular life. For instance, cell walls can be built from simple hydrocarbon chains and amino acids are short hydrocarbon chains hooked up with nitrogen, oxygen or sulfur atoms.

“The generation of hydrocarbons was the very first step, otherwise Earth would have remained lifeless,” says lead author Proskurowski, who conducted the research while earning his doctorate from the University of Washington and during post-doctoral work at Woods Hole Oceanographic Institution.

Some researchers believe the first building blocks of life made their way from outer space while others hypothesize that the right ingredients were generated by geological process on Earth, perhaps at hydrothermal vent systems where seawater seeps into the seabed and picks up heat and minerals until the water is so hot it vents back into the ocean.

The Lost City hydrothermal vents, discovered by Kelley and others during a National Science Foundation expedition in 2000, are formed in a very different way than the black smoker vents scientists have known about since the 1970s. Black smokers are so named because it can appear as if smoke is billowing from them. In fact the smoke is actually dark iron- and sulfur-rich minerals precipitating when scalding vent waters — as hot as 760 F –meet the icy cold depths. The spires and mounds that form are darkly mottled mixes of sulfide minerals.

In contrast, structures at the Lost City hydrothermal vent field are nearly pure carbonate, the same material as limestone in caves, and they range in color from white to cream to gray. The structures drape the cliffs at Lost City and range from the size of tiny toadstools to the 18-story column, named Poseidon, that dwarfs most known black smoker vents by at least 100 feet. The field was named Lost City in part because it is on top of a submerged mountain named Atlantis and was discovered by chance during an expedition on board the research vessel Atlantis.

Water venting at Lost City is generally 200 F. The fluids do not get as hot as the black smokers because the water is not heated by magma but rather by heat released during serpentinization, a chemical reaction between seawater and mantle rock.

That’s also the reason for all the hydrocarbons.

Lost City is located about 2,300 miles east of Florida on the Mid-Atlantic Ridge, one of the world's largest undersea mountain ranges. - Credit: University of Washington
Lost City is located about 2,300 miles east of Florida on the Mid-Atlantic Ridge, one of the world’s largest undersea mountain ranges. – Credit: University of Washington

Naturally occurring carbon dioxide is locked in mantle rock. At Lost City, the reaction between the rock and seawater produces 10 to 100 times more hydrogen and the hydrocarbon methane than a typical black smoker system found along mid-ocean ridges, the Science co-authors found.

The Lost City system forms hydrocarbons in higher concentrations and with more complexity than do typical black smoker systems on mid-ocean ridges, says Kelley, a University of Washington professor of oceanography who was the principal investigator for a 2005 National Oceanic and Atmospheric Administration’s expedition that gathered the samples analyzed for the Science paper.

The hydrocarbons being produced at Lost City are not formed from atmospheric carbon dioxide dissolved in seawater because none of the carbon carries the radioisotopic signature that would be present if they had been exposed to sunlight, Proskurowski says.

Analysis of rock from Lost City shows that the hydrocarbons are not coming from the living biosphere. Rock in contact with seawater has a very consistent ratio of carbon dioxide to helium. But the rock at Lost City had a strikingly different ratio. It turns out that the depleted amount of carbon dioxide in the rocks roughly equals the amount of hydrocarbons being produced in the fluids, he says.

“The detection of these organic building blocks from a non-biological source is possible evidence in our quest to understand the origin of life on this planet and other solar bodies,” Proskurowski says.

Lost City is exceptional, Kelley says, because chemical reactions in the seafloor produce acetate, formate, hydrogen and alkaline fluids. All these substances may have been key to the emergence of life, according to work published recently by Michael Russell and A.J. Hall of Glasgow and William Martin of Germany. In addition, acetate and formate found in Lost City fluids may have been an important energy source for the ancestors of methanogens, microorganisms that live off the methane at places like Lost City. It’s perhaps one more bit of evidence about where life may have originated, Kelley says.

Other co-authors of the paper, “Abiogenic Hydrocarbon Production at Lost City Hydrothermal Field,” are Marvin Lilley and Erick Olson from the University of Washington, Jeffrey Seewald and Sean Sylva from Woods Hole Oceanograhic Institution, Gretchen Früh-Green from the Swiss Federal Institute of Technology and John Lupton with NOAA’s Pacific Marine Environmental Laboratory.

The Lost City hydrothermal vent field is about 2,300 miles east of Florida, on the Mid-Atlantic Ridge, at a depth of 2,600 feet. Microorganisms there thrive in alkaline vent fluids, some nearly as caustic as liquid drain cleaner. This contrasts to the previously studied black-smoker vents where organisms have adjusted to acidic water. Lost City microbes live off methane and hydrogen instead of the carbon dioxide that is the key energy source for life at black-smoker vents.

Although nobody has found another field like Lost City, Kelley says she’s sure others exist because there are so many other places where mantle rock has been thrust up through the seafloor, exposing it to seawater and serpentinization. It is likely that even more mantle rock was present in the oceans of early Earth, Kelley says.

Baffin Island Ice Caps Shrink By 50 Percent Since 1950s

Ice caps on the northern plateau of Baffin Island in the Canadian Arctic have shrunk by 50 percent in recent decades as a result of warming temperatures. Image courtesy Gifford Miller, University of Colorado at Boulder
Ice caps on the northern plateau of Baffin Island in the Canadian Arctic have shrunk by 50 percent in recent decades as a result of warming temperatures. Image courtesy Gifford Miller, University of Colorado at Boulder

A new University of Colorado at Boulder study has shown that ice caps on the northern plateau of Baffin Island in the Canadian Arctic have shrunk by more than 50 percent in the last half century as a result of warming, and are expected to disappear by the middle of the century.

Radiocarbon dating of dead plant material emerging from beneath the receding ice margins show the Baffin Island ice caps are now smaller in area than at any time in at least the last 1,600 years, said geological sciences Professor Gifford Miller of CU-Boulder’s Institute of Arctic and Alpine Research. “Even with no additional warming, our study indicates these ice caps will be gone in 50 years or less,” he said.

The study also showed two distinct bursts of Baffin Island ice-cap growth commencing about 1280 A.D. and 1450 A.D., each coinciding with ice-core records of increases in stratospheric aerosols tied to major tropical volcanic eruptions, Miller said. The unexpected findings “provide tantalizing evidence that the eruptions were the trigger for the Little Ice Age,” a period of Northern Hemisphere cooling that lasted from roughly 1250 to 1850, he said.

A paper on the subject was published online in Geophysical Research Letters and featured in the Jan. 28 edition of the American Geophysical Union journal highlights. Authors on the study included Miller, graduate students Rebecca Anderson and Stephen DeVogel of INSTAAR, Jason Briner of the State University of New York at Buffalo and Nathaniel Lifton of the University of Arizona.

Located just west of Greenland, the 196,000 square-mile Baffin Island is the fifth largest island in the world. Most of it lies above the Arctic Circle.

The researchers also used satellite data and aerial photos beginning in 1949 to document the shrinkage of more than 20 ice caps on the northern plateau of Baffin Island, which are up to 4 miles long, generally less than 100 yards thick and frozen to their beds. “The ice is so cold and thin that it doesn’t flow, so the ancient landscape on which they formed is preserved pretty much intact,” said Miller.

In addition to carbon-dating plant material from the ice edges, the researchers extracted and analyzed carbon 14 that formed inside the Baffin Island rocks as a result of ongoing cosmic radiation bombardment, revealing the amount of time the rocks have been exposed, he said. The analysis of carbon 14 in quartz crystals indicated that for several thousand years prior to the last century, there had been more ice cover on Baffin Island, Miller said.

The increase of ice extent across the Arctic in recent millennia is thought to be due in large part to decreasing summer solar radiation there as a result of a long-term, cyclic wobble in Earth’s axis, said Miller. “This makes the recent ice-cap reduction on Baffin Island even more striking,” he said.

Funded primarily by the National Science Foundation, the study is among the first to use radiocarbon samples from rocks for dating purposes, Miller said. The radiocarbon portion of the study was conducted at INSTAAR and the University of Arizona.

Temperatures across the Arctic have been rising substantially in recent decades as a result of the build up of greenhouse gases in Earth’s atmosphere. Studies by CU-Boulder researchers in Greenland indicate temperatures on the ice sheet have climbed 7 degrees Fahrenheit since 1991.

Rock Fracture Dynamics Lab Opens

Earthquakes, volcanoes, water, mining and radioactive waste can all impact rock strength and stability. Now, a cutting-edge facility at the University of Toronto will help researchers accurately understand and predict how rocks will react to these different types of stress. The new Rock Fracture Dynamics Laboratory is the only laboratory in the world where rock samples can be tested under true earth-like stress and temperature conditions while imaging deformation.

“The facility enables us to perform geophysical imaging on samples of rocks so we can now visualize what’s going on inside the rock as it is happening,” says Professor Paul Young, Keck Chair of Seismology and Rock Mechanics and vice president (research) at the University of Toronto. “It will also boost partnerships and be a strong catalyst for collaboration with the top international researchers in the fields of rock mechanics and geophysics.”

A key part of the facility is the advanced computer system called the high performance computing cluster consisting of 64 quad-core 64-bit processors and 4-8GB RAM per processor. In near-real time, the computing cluster processes and displays results from 400 megabytes of data being collected from geophysical acquisition computers. As well as experimental data processing for imaging, it will allow much larger and higher resolution models to be produced then ever before.

The laboratory was made possible through $5 million funding from the Canadian Foundation for Innovation (CFI), Ontario Innovation Trust, Ontario Ministry of Research and innovation and the U.S. Keck Foundation as well as industry contributions including MTS Systems Corporation, Dell Canada Inc, and Microsoft.

New ice core shows more evidence of Antarctic Peninsula change

Dr Liz Thomas conducts initial analysis of the Gomez ice core
Dr Liz Thomas conducts initial analysis of the Gomez ice core

More evidence of changing weather patterns around the Antarctic Peninsula – a region where climate has changed rapidly over the last 50 years – is published this month in Geophysical Research Letters (online).

Scientists from British Antarctic Survey (BAS) and the Desert Research Institute, USA, report a doubling of snowfall in the western Antarctic Peninsula since the 1850s, with a particularly rapid increase each decade since the 1970s. Although the findings are consistent with predictions of increased snowfall as the Antarctic Peninsula gets warmer, the magnitude of the change is surprising. Records of snowfall across the rest of Antarctica appear to have changed very little during this time.

Scientists have used various instruments and technologies to make direct observations and measurements of climate since the first permanent Antarctic research stations were established over 50 years ago.

Lead author, Liz Thomas of BAS said, “To understand our changing climate we need go back in time. This is where ice cores come in. Our climate models suggested that a location known as Gomez* would be a good place to extract an ice core to find out about the impact of changing weather patterns on snowfall. Evidence from the core is consistent with our direct observations of temperature over the last 50 or so years.

“The marked and increasingly rapid rise in snow accumulation on the western Antarctic Peninsula is yet more evidence of dramatic climate change in the region. The rapidity is significant because it shows that large scale changes in weather patterns can happen very quickly – even within our lifetime – and if these shifts in snowfall can happen in the Antarctic Peninsula, they could happen elsewhere.”

This new finding contributes to an ongoing series of investigations on the West Antarctic Ice Sheet that aims to improve our forecasts of future climate change.

A doubling in snow accumulation in the Western Antarctic Peninsula by Elizabeth R. Thomas, Gareth J. Marshall and Joseph R. McConnell will be published in the February issue of Geophysical Research Letters. It is available online, doi: 10.1029/2007GL032529, 2008

*The new core – dubbed “Gomez” after a hill top poking out of the ice sheet near the drill site – plugs a major gap in information about climate change in the area.

The increase in snowfall in the Gomez core is linked to changes in a large-scale weather pattern known as the Southern Hemisphere Annular Mode (SAM) – changes due predominantly to the ozone hole and increasing greenhouse gases. Over the past decade westerly winds around Antarctica have become stronger, bringing warmer, wetter air down to the Antarctic Peninsula.

Analysis of the Gomez ice core reveals a relatively stable annual snowfall of around half a metre per year between the 1850s and 1930s, which was followed by a steady increase until the 1970s when the rise accelerated. In the last decade the amount of annual snowfall is around 1 metre – double the 1930s average.

The Antarctic Peninsula is an area of rapid climate change and has warmed faster than anywhere else in the Southern Hemisphere over the past half century. Climate records from the west coast of the Antarctic Peninsula show that temperatures in this region have risen by nearly 3°C during the last 50 years – several times the global average and only matched in Alaska.

In 2006, scientists from BAS published the first direct evidence linking human activity to the collapse of Antarctic ice shelves. Their research – published in the Journal of Climate – showed that stronger westerly winds in the northern Antarctic Peninsula, driven principally by human-induced climate change, caused the marked regional summer warming that led to the collapse of the 3250 km2 Larsen B Ice Shelf in 2002.

Scientists know that the Antarctic ice sheet has grown and shrunk over geological history. Recent analysis of Antarctic ice cores reveal that during the last 800,000 years the Earth experienced eight glacial cycles (each with an ice age and warm period). Understanding this natural rhythm helps scientists get a better picture of what’s happening to the Earth’s climate today and what might happen in the future.

Ice cores – cylinders of ice drilled from glaciers and polar ice caps – have played a vital part in our understanding of climate change. When snow falls in regions where temperatures above freezing are rare, each year’s snowfall is preserved. As the snow compacts to form ice, air bubbles become trapped, archiving atmospheres hundreds of thousands of years old. By analyzing the chemical composition and physical properties of the snow and the trapped air, scientists can discover not only how levels of greenhouse gases such as CO2 and methane have changed over time, but also how temperatures varied in the past.