Posts Tagged ‘Science’

Russia to abandon its Arctic drift stations

July 4, 2010
Russia  to abandon its Arctic drift stations  02.07.2010
Russia may abandon its polar drifting scientific stations in the Arctic region within five years and build a special permanent platform for replacement, the Interfax news agency reported on Friday.

The final decision on the replacement has not been made yet, but the idea “is being discussed actively,” head of high-latitude expedition of the Arctic and Antarctic Institute, Vladimir Sokolov, said, Xinhua reported.

The institute had spent all the money allocated for 2010 for the emergency evacuation of the SP-37 drift station after the ice floe it stands on had been broken, he said.

“So this year the next station, SP-38, will not likely be planted, we are just short of funds for that,” Sokolov added.

According to the scientist, service fees for the nuclear ice-breakers rose 10-fold during the last six years and the next polar station could be launched only if the extra state funds would be allocated.

Russia set up annual polar expedition before World War II and kept them going even during the Great Patriotic War.

The polar drift stations’ crews consist of meteorologists, oceanographists and other scientists.

Original article here

Archaeologists Unearth Neanderthal Tools In Britain

June 7, 2010

Wednesday, 2 June 2010, 13:15 CDT

Archaeologists reported on Tuesday that they have found the earliest evidence of Neanderthals living in Britain. Two pieces of flint dating back 110,000 years ago were found at a construction site in Dartford, Kent. Dr. Francis Wendan-Smith, from Southampton University, said the finds push back the presence of Neanderthals in Britain by 40,000 years or more. A majority of researchers believe Britain was uninhabited by humans during the time the flint tools date back too.

An absence of archaeological evidence suggests people abandoned this land between 200,000 years ago and 65,000 years ago. However, one researcher said the evidence presented so far did not convince him. Dr. Mark White from Durham University told BBC News he would like to assess the findings in detail before considering whether they posed a challenge to the majority view that humans were absent from Britain at this time.

The excavation that uncovered the flint hand tool and waste flake was funded by the U.K.’s Highways Agency. Wenban-Smith and colleagues from Oxford Archaeology have dated the sediments back 110,00 years, placing them within the “abandonment period.” The discovery comes from a time when sea levels were dropping after a period when they were high enough to make the English Channel impassable.

“We know that Neanderthals inhabited Northern France at this time, but this new evidence suggests that as soon as sea levels dropped, and a ‘land bridge’ appeared across the English Channel, they made the journey by foot to Kent,” Wenban-Smith told BBC. The dearth of evidence for human occupation in Britain between 200,000 and 65,000 years ago has perplexed the archaeologists.  The English Channel would have posed a physical barrier to humans trying to cross the continent. However, sea levels fluctuated during this period.  There were other times when hunters could walk from France to southern England.

About 200,000 – 130,000 years ago the sea level was predominantly low.  Humans should have been able to get there, but for some reason they did not show up. “It could be something subtle like the rapidity of changing climate, altering its state from warmer to colder conditions. That may have meant it was too hard for the Neanderthals to develop a sustainable adaptation,” Wenban-Smith told BBC. “Neanderthals were cold adapted and maybe it just took them that time to adapt to the cold environment of that period. Before 130,000, they had not really cracked it. But after 115,000, they had cracked it.”

About 130,000 years ago sea levels rose and Neanderthals would have been blocked from entering Britain by the English Channel.  However, about 115,000 years ago sea levels fell again. Wenban-Smith and his team said the flint tools from Dartford suggest that humans were able to take advantage of this opportunity. The discovery was dated back by using a method known as optically stimulated luminescence (OSL).  This exploits the presence of radioactive isotopes in the natural environment. Naturally occurring minerals like quartz and feldspars record the amount of radiation to which they have been exposed.

Some minerals store a proportion of energy radiation delivered and then release it at a later date in the form of light. The amount of light released by these minerals can be used to calculate the radiation dose a sample has received, helping to give an estimation of time that has elapsed since it was buried. White raised doubts over the reliability of OSL dating though, saying the technique was more or less “in constant development.” He added that assumptions about background radiation and average water content could significantly affect results.

“I haven’t seen the flints, but I’ve no doubt they are genuine. Currently, with what has leaked to the press, I have no idea of the context of these finds,” he told BBC News. “I suspect there is a possibility the OSL dating [technique] might not be giving us the true date. And that would be my only [reservation].” “I have similar dates from a site near Dover in Kent, which have come out between 90,000 and 100,000 years ago. But I don’t think OSL is giving us a correct date and I have disregarded them.”

Neanderthals split from our evolutionary line about 500,000 years ago.  A short, muscular physique, a barrel chest, large brain and prominent facial features characterized them. Wenban-Smith along with other researchers say that the “classic” Neanderthal features appeared about 200,000 years ago. However, other scientists describe much older fossils as Neanderthals.  These include the 400,000-year-old partial skull found in Kent and the 230,000-year-old human teeth discovered at Pontnewydd in Wales.

On the Net:

Original article here

Hornorkesteret comment: I wonder why the Oxford archeologists placed a tiny white, red-eyed rabbit in the foreground of the accompanying picture?

Cro Magnon skull shows that our brains have shrunk

April 20, 2010
Cro  Magnon brain

A 3D image of a Cro Magnon brain. Credit: Times Online.

March 15, 2010 by Lisa Zyga

(PhysOrg.com) — A new replica of an early modern human brain has provided further evidence for the theory that the human brain has been shrinking. The skull belonged to an elderly Cro Magnon man, whose skeleton is called Cro Magnon 1. The entire skeleton was discovered in 1868 in the Cro Magnon cave in Dordogne, France, and has since become one of the most famous Upper Palaeolithic skeletons. Using new technology, researchers have produced a replica of the 28,000-year-old brain and found that it is about 15-20% larger than our brains.

To produce the brain replica, called an endocast, the scientists first digitally scanned the interior of the empty skull. The images revealed the impression left by the brain on the neurocranium, which was then transformed into a 3D image. Software was then used to fabricate the brain endocast.

The researchers, including Antoine Balzeau of the French Museum of Natural History, said that an initial assessment of Cro Magnon 1’s skull supported the theory that brains have grown slightly smaller over the past tens of thousands of years, reversing an earlier trend toward larger brains.

The finding doesn’t suggest that humans today are less intelligent than earlier humans. Although previous studies have found a very small relationship between brain size and intelligence, many other factors affect brain intelligence.

For instance, different parts of the brain have different functions. The researchers found that the Cro Magnon brain appears to have had a smaller – the brain region linked to motor control and language – than our brains today. The researchers explain that this finding shows that some parts of the brain are more “compressible” than others, while other regions seem to provide a benefit by growing larger.

Although scientists don’t know for sure why our overall brains are shrinking, some researchers hypothesize that our brains are becoming more efficient as they grow smaller. Having a large comes at a cost, so smaller brains have an advantage since they enable the body to use the extra energy for other purposes. On the other hand, perhaps a large skull had certain advantages for earlier people. One idea is that Cro Magnons needed large skulls because of the difficulty in chewing their food, which included lots of meat such as rabbits, foxes, and horses. Since our food has become easier to eat, we don’t need such large skulls or jaws. Another theory is that the high infant mortality rate in earlier times meant that young humans had to be physically robust (with large heads) to survive their early years.

The researchers plan to show a mold of the later this week at the National Museum of Natural History in Washington, DC.

Pesticides in Svalbard snow

April 10, 2010

Scientists at the Norwegian Polar Institute and the University Centre in Svalbard (UNIS) have investigated the amount of pesticides in the snow in Svalbard. Read about their findings here.

Legacy and current use pesticides in Svalbard

Mark Hermanson (UNIS)
Elisabeth Isaksson (Norwegian Polar Institute)
November 2009

Ice core drilling tent on Lomonosovfonna, Svalbard

How much dursban have you used to kill termites at your home in Longyearbyen? How much methyl parathion has been used to kill boll weevils on cotton plants in Ny-Ålesund? And how much endosulfan has been used to kill insects in apple orchards in Svea? While all of these questions are silly, the reality is that all of these and other pesticides are found in Svalbard. Some of them are found in high enough concentrations to suggest that there could be 1000 kg of each of them on all of the land ice in Svalbard.

While insects are sometimes brought to Svalbard in cargo and, occasionally on strong winds from the south, the climate here is the most efficient pest killer that we have. So why are pesticides being found here?

Since 2000, researchers from Environment Canada, the University of Pennsylvania (USA), the Norwegian Polar Institute in Tromsø, and now UNIS, have been asking the same question.

Drilling ice cores

Since 2000, researchers from Environment Canada, the University of Pennsylvania (USA), the Norwegian Polar Institute in Tromsø, and now UNIS, have been asking the same question.

These groups have collaborated on investigating pesticides in ice cores and snow pits from sites on Austfonna, Lomonosovfonna, and Holtedahlfonna, three of the major high-elevation ice fields in Svalbard.

The most recent work, on an ice core drilled at Holtedahlfonna in 2005, included analysis of 64 different pesticides, some of them “legacy” pesticides that are no longer used, others “current-use” pesticides that are still being used somewhere in the world. [The legacy pesticides are no longer used because they are persistent in the environment and threaten non-pest organisms. The current-use pesticides are intended to have short lifetimes in the environment, often decomposing in air because of the energy effects of the sun. In darkness, however, that effect is nil.] Of these 64, there were insecticides, herbicides and fungicides. And of those 64, 21 were found in some part of the ice core. We should be happy that 43 pesticides were not found at all. But none of the other 21 were used in Svalbard, so, again, how did they get here? And why are they found in ice at high elevations?

Preparing ice cores

Our research is showing us that the atmosphere can deliver pesticides over long distances as gases or attached to particles suspended in air. Most of the pesticides are being transported to Svalbard by fast-moving winds from agricultural areas in

Europe and Asia or, in other words, from the south and east. They are deposited during snowfall or rain, or may change from gas to liquid in cold air. Fortunately, there is no indication that the amounts of pesticides being found are harmful to people or animals living on Svalbard. However, there is evidence that amounts of some pesticides in Svalbard are growing and need to be watched in the future.

We are also finding that there are differences in amounts and numbers of pesticides reaching different parts of Svalbard.

Austfonna, for example, received about twice as many different pesticides during the 1986 – 1998 period than found at Holtedahlfonna. Austfonna also had higher concentrations of most of the pesticides found at both sites. Analysis of air mass movements showed that air masses from Europe and northern Asia are more often flowing to Austfonna than to Holtedahlfonna, increasing the opportunities for pesticides to reach the northeastern part of Svalbard.

Taking snow samples

Some of these pesticides that appear in Svalbard, if found in food or water in high concentrations, can be extremely harmful to mammals, including seals, polar bears and humans. The chemical agents in these pesticides do not distinguish between “pests” and “non-pests”. The chemical in dursban, known as “chlorpyrifos”, has the same toxic mechanism as chemical warfare agents like Sarin or VX , although at a very high dose. In other words, it is a poison that interferes with control of the nervous system which is how it kills pests. Endosulfan is thought to act like hormones in the human body, causing disruptions of some body functions. Other pesticides are considered to be carcinogens.

The amounts of pesticides found in Svalbard can not possibly do any good. And the concentrations of some are increasing. So how can a Svalbard resident protect himself from the effects of pesticides? The best answer is the same used by people in other parts of the world, which is participation in a political process based on scientific facts. The “legacy” pesticides seen in Svalbard are nearly all declining in concentration because their use has been banned throughout the world by the Stockholm Convention (http://chm.pops.int/). This Convention is an on-going effort to eliminate contaminants, including pesticides, from the environment. The list of banned substances continues to grow, and with efforts from Svalbard citizens and scientists, could include more of the pesticides found in growing amounts in Svalbard.

All photographs: Gerit Rotschky / Norwegian Polar Institute

Original article here.

Neither Neanderthal nor sapiens: new human relative IDed

March 30, 2010
By John Timmer | Last updated 3 days ago

At a press conference yesterday, researchers announced the completely unexpected: a Siberian cave has yielded evidence of an entirely unknown human relative that appears to have shared Asia with both modern humans and Neanderthals less than 50,000 years ago. The find comes courtesy of a single bone from individual’s hand. Lest you think that paleontologists are overinterpreting a tiny fragment, it wasn’t the shape of the bone that indicates the presence of a new species—it was the DNA that it contained.

The paper that describes the finding comes courtesy of the Max Planck Institute’s Svante Pääbo, who has been actively pursuing the sequencing of the Neanderthal genome. It seems likely that this particular bone fragment was targeted due to suspicions that it might also provide an additional Neanderthal sequence. The site, called Denisova, is in the Altai Mountains of southern Siberia, an area that has had hominins present as early as 125,000 years ago. The sample itself came from a layer of material that dates from between 30,000 and 50,000 years ago. Neanderthal DNA was found in a sample from the same time period less than 100km away, while artifacts indicate that modern humans were also present in the region by 40,000 years ago.

So, there was no apparent reason to suspect that the bone would yield anything more than a familiar sequence. And in fact, most of the first half of the paper simply describes the methods used to construct a complete sequence of the mitochondrial DNA, including over 150-fold coverage of the genome, and an alignment program designed to account for the errors typical of ancient DNA sequences. About the only surprise here is that Pääbo’s group has switched from using 454 sequencing machines to those made by Illumina.

Various checks indicate that the sequence the authors obtained contains damage that’s typical of ancient DNA, and that it all comes from a single individual. So far, quite typical.

Things got quite unusual when they attempted to align the sequence to the mitochondrial DNA from the hominin species that were likely to be present at that time and place: human and Neanderthal. Instead of clustering with one or the other, the Denisova mitochondrial genome was a clear outlier, having about 385 differences with the typical human mitochondrial genome. In contrast, Neanderthals only differ from modern humans by an average of 202. The obvious interpretation is that the Denisova lineage split off before modern humans and Neanderthals did. If we accept that Neanderthals are a distinct species of hominin (and we do), then this sample clearly represents yet another one.

Building a tree with the chimpanzee genomes and assuming a divergence time of 6 million years, the data indicates that the Denisova lineage diverged about a million years ago. At that point, Homo Erectus was already a global species, but our human ancestors were still in Africa. That suggests that the Denisova variant probably originated in, or at least near, Africa as well, although there’s no way to tell whether it was a distinct species before it started migrating, or whether it became an isolated population because of a migration.

The paper is in the format of a Nature letter, which allows only a paragraph for discussion. The authors use that space primarily to note that, 40,000 years ago, southern Siberia was a very busy place as far as hominins are concerned, with at least three different species present within a very narrow time frame. If we accept that the Indonesian hobbits are yet another distinct species—and the relevant community seems to be leaning that way—then it appears that there were at least four distinct hominin species cohabiting the globe in the very recent past.

As surprising as that is, it’s only a small fraction of the implications of this work. For starters, there’s the whole idea that we can identify a new species without having any idea what it actually looked like—in fact, without having any idea of whether it would be physically distinct enough from any of the other hominin species around that we’d even have known it were a separate species based on the bones.

The authors also briefly touched on a separate issue: this ability will be unevenly distributed in space and time. DNA simply lasts longer in cool climates, as evidenced by the recent announcement that DNA had been obtained from a polar bear sample that was over 100,000 years old. So, any species that was stuck near the equator—like the hobbits—are unlikely to be in on the DNA revolution. This is especially unfortunate given the fact that, as noted above, a lot of the most interesting action in hominin origins seem to have been taking place in Africa.

Then there’s the whole question of what else we might be missing. Avoiding contamination issues with modern DNA is easiest if the entire excavation is designed around a sterile technique from the start, meaning bones that have been previously excavated aren’t ideal. At the moment, at least, sequencing from a single sample is also pretty labor intensive (this paper had seven authors), meaning we aren’t likely to be able to just start sequencing any bone fragments we stumble across. Figuring out how to prioritize what might be informative will be a real challenge.

If that seems like a lot of questions for a short and fairly technical paper (and it is), it’s a product of the fact that this paper seems truly exceptional. Because of the rich history of most fields of science, there aren’t a whole lot of truly unexpected results, since you typically know that there are people working in a given area. But this finding is truly a stunning one, and really seems to be a complete surprise.

Nature, 2010.

Original article here.

Body clock of arctic reindeer ticks differently

March 28, 2010

How many other body processes affected by development are uncertain
By Andrea Thompson

Arctic reindeer live in the near perpetual night and then endless daytime that seasonally occur at the top of the world. These extreme conditions seem to have led the reindeer to abandon the internal clocks that drive the daily biological rhythms of mammals at lower latitudes, a new study finds.

In mammals, including humans, some hormone levels rise and ebb on a rhythmic daily cycle. This circadian rhythm influences various processes in the body, from the sleep/wake cycle to reproduction. The light-dark signals of day and night help drive these cycles, as does an internal body clock that works on a 24-hour cycle even in the absence of a light-dark switch.

But in reindeer, “it is this clock element that seems to be missing,” said study author Andrew Loudon of the University of Manchester in England, referring to the internal ticker.

The missing clock doesn’t have any effect on the sleep patterns of the reindeer, as they sleep after they eat, and tend to eat some 8 to 10 times a day, as is the case for all ruminant animals.

Loudon and his colleagues looked at levels of melatonin (a hormone that responds to the circadian cycle) in Arctic reindeer and found that they showed no natural internal rhythm of melatonin secretion. Instead, their hormone levels rise and fall in direct response to light and dark.

And studies of reindeer skin cells showed that two well-known clock genes don’t oscillate the way they do in other organisms as a way of keeping time.

“We suspect that they have the full range of normal clock genes, but these are regulated in a different way in reindeer,” Loudon said.

The findings of the study, detailed online on March 11 in the journal Current Biology, initially came as a surprise, but the researchers now suspect that similar patterns could be seen in other Arctic animals.

“Our findings imply that evolution has come up with a means of switching off the cellular clockwork,” Loudon said. “Such daily clocks may be positively a hindrance in environments where there is no reliable light-dark cycle for much of the year.”

Because the Earth is tilted on its axis, the Arctic is pointed toward the sun during the summer months, which keeps the sun perpetually above the horizon during this time. During the winter, the opposite is true, and the Arctic is plunged into months of darkness. The same is true of the Antarctic.

Instead, light and dark signals that come during the year’s two equinoxes (fall and spring) could be enough to jumpstart certain processes in the reindeer, such as the annual reproductive cycle, the researchers say.

Just how many body processes are affected by this unusual development isn’t certain.

“We do not know how extensive the loss of clockwork is in reindeer,” Loudon told LiveScience. “There may still be a clock in there ticking away, but we have not been able to find it. It looks like the molecular clock is switched off at least in skin cells (and frankly I suspect elsewhere as well).”
© 2010 LiveScience.com. All rights reserved.

Submerged Antarctic Lakes Within Reach

March 28, 2010

Three teams are drilling at separate locations

By Tudor Vieru, Science Editor March 24th, 2010, 08:04 GMT
Original article here

Millions of years ago, as Antarctica was covered by plains and mountains, not ice, lakes adorned its surface, as they do on all other continents. As the weather cooled, and ice began to form, the majority of these lakes solidified, and became a part of the thick ice sheet currently covering the Southern Continent. But a small part of these lakes endured. They were covered by a cap of ice, on which miles of other ice deposited itself. Now, researchers are drilling to get to them, for several different reasons, Nature News reports.

The most important is life. With millions of years gone since the microorganisms in these underground lakes had any contact with the outside world, biologists hypothesize that they changed considerably. Finding out how life can evolve within such tightly-closed ecosystems is of tremendous importance for space exploration, among others. If bacteria, microbes and viruses can endure in the freezing, oxygen-free conditions of submerged lakes, then it shouldn’t be too far-fetched to believe that the same can happen in the covered ocean of Enceladus, or in the liquid hydrocarbon lakes of Titan.

Using advanced observations methods, geologists and other experts were able to observe the contours of these lakes even through the miles of ice covering them, and have set up experiments to get to them. Three nations are currently engaged in this type of efforts. At a joint meeting they held last week, researchers from the United Kingdom, the United States, and the Russian Federations, described the progress they registered in their drills this far. They also exposed their plans on how to handle this delicate task. All experts involved underlined the fact that breaching the surface of these lakes would need to be conducted in an environment as sterile as an operating room.

Any small contaminants from the outside world could change the ecosystem in a matter of minutes, and so this needs to be avoided at all costs. Still the curiosity to explore the world’s last unknown ecosystem is very great. Experts say that these subglacial lakes will be reached next year, as the technology needed to avoid contamination will be produced, delivered to Antarctica, installed, and then operated. Though three groups are working on this type of exploration, there are at least 150 underground lakes under the ices, all of them identified as having various ages and sizes. They will most likely constitute a target for future investigations.

Teams set for first taste of Antarctic lakes
Samples could reveal unique life forms from beneath the ice.

Quirin Schiermeier

The pitch-black lakes hidden beneath Antarctica’s ice sheet will finally start to release their secrets next year. At a meeting last week, scientists from Russia, the United Kingdom and the United States described their plans to explore the planet’s last uncharted ecosystems by drilling into three very different examples of these subglacial lakes.

Over the past 40 years, radar imagery has revealed around 150 freshwater lakes of various sizes and ages beneath the massive Antarctic ice sheet. Some have been isolated from the outside world for millions of years, raising the possibility that they hold unique life forms. The dark, nutrient-deprived environment of the lakes could resemble conditions on Jupiter’s moon Europa, which is assumed to hold a large ocean beneath its frozen surface.

Scientists have longed to draw samples from the lakes, but technical problems and environmental concerns have slowed their progress. Now, the Russian team expects to reach its quarry, Lake Vostok, by February 2011. The Americans and British will follow several years later with forays into lakes with different hydrological and geological characteristics (see graphic).

“Over the next few years we’ll be able to explore a continental-scale ecosystem that has never before been sampled,” says Robin Bell, a senior researcher at Columbia University’s Lamont-Doherty Earth Observatory in Palisades, New York. “This is a madly exciting endeavour.”

Lake Vostok is the best known and largest of the subglacial lakes, measuring roughly the size of Lake Ontario. Buried beneath almost 4,000 metres of ice in eastern Antarctica, the lake is thought to be 35 million years old and could host ancient microbial life.

Russian drillers had planned to penetrate the lake in the 2008–09 Antarctic field season, but their drill got stuck 80 metres above the lake surface. All technical problems have been resolved during the past field season, says Valery Lukin, director of the Russian Antarctic programme, who spoke at the meeting, held by the American Geophysical Union in Baltimore, Maryland.

Some researchers worry that a Russian success could come at the cost of biological and chemical contamination of the pristine waters. “Let’s hope they don’t spoil the lake,” says Robert Bindschadler, a glaciologist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

Lukin says that his country’s team has come up with plans to safeguard Lake Vostok. The team will cut through the ice using a heated drill, with non-toxic silicone oil serving as the lubricating fluid. It will also explore the lake in stages; at first it will only suck up a water sample before allowing the bottom of the hole to refreeze. Plans for lowering instruments into the lake to explore the bottom sediment will be postponed until an extra environmental assessment has been completed.

The Antarctic Treaty’s committee for environmental protection is expected to approve the Russian plans in October, although there is no official requirement for the team to wait until then. “The Russians are trying very hard to do it right, and that means a lot,” says Bell.

At the meeting, US and British researchers described their longer-term plans for exploring subglacial lakes on the opposite side of the pole. Lake Ellsworth, a relatively small lake in western Antarctica, is the target for researchers from the British Antarctic Survey. And over the next two field seasons, US researchers will conduct radar surveys from the surface to study Lake Whillans near Antarctica’s Ross Ice Shelf, says Ross Powell, a geologist at Northern Illinois University in DeKalb. The US$20-million Whillans Ice Stream Subglacial Access Research Drilling (WISSARD) project, which Powell oversees, plans to drill into the lake during the 2012–13 field season.

Lake Whillans has a subsurface connection with the ocean beneath the ice shelf, making it more dynamic than isolated lakes such as Vostok. “We know that the lake surface is constantly falling and rising, and we assume the lake is occasionally draining and refilling completely,” says Powell.

The ebb and flow of lakes such as Whillans are thought to influence
the movement of the overlying ice sheet. The WISSARD team will study
processes at the interface of ice and water that affect the movement.

With so many drilling projects, “it’s like going fishing in the
Everglades, in the Rocky Mountains and in Northern Canada”, says Bell.
“The catch will be very different and we’re going to learn a lot.”

Arctic Glacial Dust May Affect Climate and Health in North America and Europe

February 20, 2010

ScienceDaily (Feb. 20, 2010)

Residents of the southern United States and the Caribbean have seen it many times during the summer months — a whitish haze in the sky that seems to hang around for days. The resulting thin film of dust on their homes and cars actually is soil from the deserts of Africa, blown across the Atlantic Ocean.

Now, there is new evidence that similar dust storms in the arctic, possibly caused by receding glaciers, may be making similar deposits in northern Europe and North America, according to Joseph Prospero from the University of Miami in a February 19 presentation to the American Association for the Advancement of Science.

“Our recent work in Iceland has shown that most of the dust events there are associated with dust emitted from glacial outwash deposits, which may be carried into the northern latitudes and into Europe by synoptic weather events,” says Prospero, professor of marine and atmospheric chemistry at the University of Miami Rosenstiel School of Marine and Atmospheric Science, in his talk “Intercontinental Dust Transport: The Linkage to Climate and its Environmental Impact.”

Satellite data have shown large dust plumes in the arctic, but persistent cloud cover has made finding the origins difficult. The glaciers have been retreating in Iceland for decades, and the trend is expected to continue with the changing climate. Prospero predicts that dust activity from the newly exposed glacial deposits will most likely increase in the future in Iceland and possibly from other glacial terrains in the Arctic.

Prospero’s lifelong work has been to measure the effects of airborne dust. Since 1965, he and his colleagues have been measuring dust particles in Barbados, West Indies, thus creating the longest dust measurement data set in science. They found that dust transport increased greatly during the late 1960s and early 1970s at the same time as a severe drought in Northern Africa.

“The first 30 years of the dust record showed a strong relationship between dust transport across the ocean to rainfall amounts in the Sahel and Soudan regions of Africa,” says Prospero. “It’s important to note that the level of dust transport is not necessarily related directly to rainfall but possibly to other climate factors associated with the variability of rainfall.”

Some of the most intense periods dust transport are associated with strong El Nino events, which may affect such factors as wind speeds and variability as well as rainfall — the same factors that affect dust mobilization and transport. However, since the late 1990s, the pattern of drought and dust transport has been disrupted — dust transport rates were actually greater than what Prospero’s earlier model would indicate.

“We still have work to do to understand the fundamental processes and relationship between climate, rainfall, and dust transport,” says Prospero. “Predicting the long-term effects of climate and dust transport is exacerbated by the fact that many of the climate prediction models for lower latitude Africa are not consistent.”

Also needing more study is whether the dust particles pose any health threat to the people below. More than half of the particles in the dust mass transported over the Atlantic to the Americas is smaller than 2.5 microns, defined as “respirable particles” by the United States Environmental Protection Agency. Over the Caribbean region, the atmospheric concentration of fine dust particles frequently is within the range of and sometimes exceeds the US EPA’s standards for respirable particles.

“Although to date there is no strong evidence that African dust constitutes a health hazard, this possible impact would seem to warrant study especially since some climate change projections show increased dust transport in the future,” concludes Prospero.

Prospero is a panelist in a symposium called “Dust in the Earth System,” which will examine dust and its effects in the Earth system while considering societal impact at the local and global levels by exchanging information, ideas, and perspectives across diverse disciplines.

Story Source:
Adapted from materials provided by University of Miami Rosenstiel School of Marine & Atmospheric Science, viaEurekAlert!, a service of AAAS.

Original article here

Interactive map of the Antarctic: browse and download recent satellite images

February 15, 2010


British Antarctic Survey

As the Antarctic field season continues with the usual mix of exciting research programmes new enhancements to the online satellite image system that improves ship safety and efficiency are launched.
The Polar View sea ice service, coordinated by the British Antarctic Survey, has greatly improved the service for the 2009/2010 Antarctic season. A combination of easier access through the new website and a significant increase in the number of images available means more real time sea ice information. The range of users of this service continues to expand, encompassing everything from science vessels to tour ships to those coordinating rescue efforts.

The new website (www.polarview.aq) now provides an interactive map displaying the latest imagery and sea ice information. Simple tools allow users to zoom into their area of interest and see recent cloud free satellite imagery from the European Space Agency. In combination with other information provided by partners in Denmark and Germany, anyone can access an up to date picture of current sea ice conditions, even on ships with limited internet access.

Thanks to the frequent satellite images being acquired for the European MyOcean project, users of the Polar View service benefit from refreshed sea ice information at least every three days. Keep an eye on the website for updates about new services in the pipeline. As well as easier access to sea ice drift information and iceberg locations, the Norwegian Meteorological Institute will shortly begin delivery of interpreted ice charts. All of which make for a more comprehensive sea ice service.

http://www.antarctica.ac.uk/by British Antarctic Survey   5:26 AM Wed 10 Feb 2010 GMT

Original article here

Ancient Man in Greenland Has Genome Decoded

February 14, 2010

New York Times/NICHOLAS WADE February 10, 2010
The genome of a man who lived on the western coast of Greenland some 4,000 years ago has been decoded, thanks to the surprisingly good preservation of DNA in a swatch of his hair so thick it was originally thought to be from a bear.

An artist’s impression of “Inuk.” Nuka Godfredsen.

This is the first time the whole genome of an ancient human has been analyzed, and it joins the list of just eight whole genomes of living people that have been decoded so far. It also sheds new light on the settlement of North America by showing there was a hitherto unsuspected migration of people across the continent, from Siberia to Greenland, some 5,500 years ago.

The Greenlander belonged to a Paleo-Eskimo culture called the Saqqaq by archaeologists. Using his genome as a basis, a team of researchers from the University of Copenhagen determined that the Saqqaq man’s closest living relatives were the Chukchis, people who live at the easternmost tip of Siberia. His ancestors split apart from Chukchis some 5,500 years ago, according to genetic calculations, implying that the Saqqaq people’s ancestors must have traveled across the northern edges of North America until they reached Greenland.

The team, led by Morten Rasmussen and Eske Willerslev of the University of Copenhagen, decoded the genome from four tufts of hair dug out of the permafrost at Qeqertasussuk, on the west coast of Greenland. The hair was excavated in 1986 and kept in a plastic bag in the National Museum of Denmark. It was found with other waste, and the scientists speculate that it was the result of a haircut.

There it moldered, unfrozen, until discovered by Dr. Willerslev, an expert on ancient DNA. Having spent two months digging for ancient human DNA in Greenland without finding any human remains, he concluded that ancient Greenlanders must have disposed of their dead by laying them on the sea ice. Only on complaining of his bad luck to a friend did he learn that the friend’s father had found the hair sample 20 years earlier.

No traces of the Saqqaq people have been found in North America, said Michael H. Crawford, an expert on circumpolar populations at the University of Kansas and a co-author of the report. Because the land bridge that once connected Siberia and Alaska had long since foundered, the Saqqaq people might have crossed to Alaska on the winter ice or could have used the boats on which they hunted fish and seals. They evidently kept to Arctic latitudes, perhaps because more southerly regions were already occupied by the Inuit, or because they were better adapted to life in the Arctic, Dr. Rasmussen said.

The Saqqaq man’s genome is so complete that the Danish researchers have been able to reconstruct his probable appearance and susceptibility to disease from the genetic information in his genome. They conclude that he would have had brown eyes because of variations, at four positions along his DNA, that are associated with brown eye color in East Asians.

He has the East Asian version of a gene known as EDAR, which endows people with hair that is thicker than that of most Europeans and Africans. Another gene suggests that he would have had dry earwax, as do Asians and Native Americans, not the wet earwax of other ethnic groups.

Perhaps reflecting the so far somewhat limited reach of personal genomics, the researchers note that the ancient Greenlander was at risk for baldness, a surprising assessment given that all that remains of him is his hair. Dr. Rasmussen said he assumed the man died young.

Biologists used to think that DNA would be found only in the cells at the roots of the hair, not in the keratin of which the hair shaft is made. But it now seems that the cells become incorporated into the growing shaft and their DNA is sealed in by the keratin, protecting it from attack by bacteria and fungi.

The Danish researchers, using an advanced DNA sequencing technology developed by Illumina of San Diego, reported that they were able to decode 80 percent of the ancient Greenlander’s genome to a high degree of accuracy. Their findings appear in the journal Nature.

An ever present danger in analyzing ancient human DNA is contamination, particularly from modern human DNA from all the archeologists and curators who have touched the samples. The Danish researchers said they took precautions to exclude this and other contaminants, and they seem to have succeeded.

Original article here