Category Archives: CONTAMINATED environment

East Coast Quake Rattled Nuclear Plants' Waste Casks

East Coast Quake Rattled Nuclear Plant’s Waste Casks: Scientific American.

WASHINGTON (Reuters) – The earthquake that shook the East Coast last week rattled casks holding radioactive nuclear waste at a Virginia plant, moving them as much as 4.5 inches from their original position, the plant’s operator said.

The 5.8-magnitude quake shifted 25 casks, each 16 feet tall and weighing 115 tons, on a concrete pad at Dominion Resources Inc?‘s North Anna nuclear plant.

“There was no damage to the casks and no damage to the fuel,” Dominion spokesman Rick Zuercher said.

“They were designed to withstand earthquakes.”

The movement of the casks will be part of a special review under way by the Nuclear Regulatory Commission?, an NRC spokesman said.

The plant, located about 10 miles from the earthquake’s epicenter near Mineral, Virginia, has been shut down since the August 23 quake as inspectors check for damage.

The NRC is conducting a special review because of preliminary data showing that shaking from the quake exceeded the plant’s design rating.

The regulator already was scrutinizing how well the U.S. fleet of 104 reactors could withstand earthquakes, floods and other disasters after a quake and tsunami wrecked Japan’s Fukushima Daiichi plant in March, the world’s worst nuclear disaster in 25 years.

The United States, which has the world’s largest nuclear power industry, has deliberated for decades over how to store waste permanently, and the U.S. government is considering a proposal for a network of centralized “dry cask” storage sites where plants could take their used fuel.

(Reporting by Roberta Rampton; Editing by Paul Simao and Dale Hudson)

Fukushima Reactor Damage Detected in California Winds

Fukushima Reactor Damage Picked Up in California Winds – ScienceNOW.

on 15 August 2011, 4:23 PM | 2 Comments
sn-fukushima.jpg

Dousing Fukushima’s reactors. Air laden with radioactive material that was formed after emergency teams soaked cores at an imperiled nuclear power plant in Japan (shown) blew into San Diego, California, about 2 weeks later.
Credit: Self Defence Force Nuclear Biological Chemical Weapon Defense Unit/Reuters TV

On 28 March, scientists got a whiff of something strange in the air off a pier in San Diego, California. The atmosphere had suddenly become flush with radioactive sulfur atoms. That sulfur, it turns out, had traveled across the Pacific from a nuclear power plant in Fukushima, Japan, that was shaken by the 11 March earthquake and the tsunami and aftershocks that followed. Now the same team has studied those radioactive winds to come up with the first estimate of damage to the plant’s cores at the height of the disaster.

To cool fuel rods and spent fuel while stanching a total meltdown, responders pumped several hundred tons of seawater into three reactors at the Fukushima Dai-ichi nuclear power plant. The white-hot rods fizzled off steam, which had to go somewhere. So workers vented it into the air.

Meanwhile, across the Pacific, atmospheric scientist Antra Priyadarshi of the University of California, San Diego (UCSD), remembered a study she had read a while back: Following underwater nuclear bomb tests in the 1950s and ’60s, physicists noticed that a heavy form of sulfur—sulfur-35—had mushroomed. Nuclear reactions spit out lots of fast and therefore “hot” particles called neutrons, which can then bang into abundant chloride ions in saltwater, converting them to sulfur-35. Priyadarshi and her colleagues were already tracking tiny traces of radioactive sulfur to study how layers of air mix in the atmosphere, so all they had to do was wait.

They didn’t have to wait long. The sulfur was already swirling over Fukushima, where it had combined with oxygen to form sulfur dioxide gases and fine particles of sulfates called aerosols. Soon, strong winds pushed them east. Sulfur-35 does occur naturally—cosmic rays zap argon atoms in the upper atmosphere, or stratosphere, to make radioactive sulfur. But little of it makes its way down to the lowest slice of atmosphere, called the marine boundary layer. On a normal day, Priyadarshi sees between 180 and 475 sulfur-35 atoms as sulfates per cubic meter of air, but on the 28th, her team recorded about 1500. “No one has ever seen such a high percentage of the stratospheric air coming into the marine-bound layer,” she says.

The UCSD team ran a computer simulation to trace the path of the gases and aerosols from Fukushima to the West Coast. Most sulfur-35 atoms likely dispersed or rained down into the sea before hitting San Diego, but Priyadarshi estimates that about 0.7% completed the trip, too few to become harmful. Based on the simulation, about 365 times the normal levels of radioactive sulfates had gathered over Fukushima during the disaster, Priyadarshi and colleagues report online today in the Proceedings of the National Academy of Sciences (PNAS).

And because the researchers knew how many neutrons it would take to make that much sulfur, they could estimate how many were expelled during the disaster: For each square meter of reactor space doused by saltwater, the nuclear material ejected 400 billion neutrons before 20 March. And that, in turn, may give scientists a good look at the damage done to the cores during the disaster, says study co-author Mark Thiemens, an atmospheric scientist who is also at UCSD. If unchecked, these particles can heat up fuel rods and stores of spent fuel to the point of causing disastrous meltdowns like the one that rocked Chernobyl in 1986.

But Andreas Stohl, a scientist at the Norwegian Institute for Air Research in Kjeller, isn’t convinced. Trying to figure out what happened to Fukushima’s sulfur-35 as it was buffeted by haphazard winds on its nearly 10,000 kilometer journey to San Diego requires a lot of guesswork, he says: “The uncertainties must be huge.”

Karl Turekian, an atmospheric geochemist at Yale University who edited Priyadarshi’s paper for PNAS, agrees. But he adds the San Diego researchers did their best to account for that atmospheric chaos. And scientists haven’t yet come up with any other way to estimate neutron “leaks” from nuclear fuel. “Somebody didn’t have a neutron thermometer in Fukushima,” he says.

Now that Fukushima’s reactors have cooled back down, the biggest challenge facing scientists will be to contain radioactive elements that escaped during the disaster. Thiemens will be working with Japanese researchers to follow sulfur-35’s path through soil and streams near Fukushima to find where even more harmful elements may have hidden.

Correction: A previous version of this article stated that winds pushed sulfur over Fukushima west. It has been corrected to say east.

Japan struggles to rebuild

Insight: Japan struggles to rebuild, leaving lives in limbo | Reuters.

Severe storms hit the Midwest on Saturday and are expected later in the Northeast, where flash flooding killed at least four people in Pittsburgh on Friday.

Heavy rains submerged cars in flood water that was nine feet deep in places in Pittsburgh, authorities said.

A mother and her two daughters died when water engulfed their vehicle in a low-lying section of the city’s Washington Boulevard near the Allegheny River.

Kimberly Griffith, 45, and her daughters Brenna, 12, and Mikaela, 8, were pronounced dead at the scene, a spokeswoman for the Allegheny County medical examiner’s office said.

The water pinned their vehicle to a tree and they were unable to escape, authorities said.

Also recovered after the flood was the body of Mary Saflin, 72, who had been reported missing earlier, according to the Allegheny County medical examiner’s office.

The Philadelphia area was also soaked by heavy thunder showers Friday, bringing a record rainfall of 12.95 inches for August, close to the record for any month, according to NWS meteorologist Lee Robertson.

The previous record is from September 1999, set when a hurricane pushed rainfall to 13.07 inches.

As more storms were forecast for the region Sunday, the NWS warned in a flood advisory that nearly half of all flood fatalities are vehicle-related.

“As little as six inches of water will cause you to lose control of your vehicle,” the NWS stated.

MORE STORMS

The Weather Channel forecast more storms from the Great Lakes to the Central Plains into Saturday night.

One man died as storms and a tornado roared across northern Wisconsin Friday night, cutting an 8-mile-wide swath 65 miles north of Green Bay and taking out power to around 2,000 homes, officials said.

Douglas Brem, 43, was staying in a rented trailer at a recycling center in the path of the storm, which caused extensive damage to homes, Marinette County Coroner George Smith said.

A fierce thunderstorm in the Chicago area Saturday suspended the Chicago Air & Water Show until about 2 p.m., leaving time for a condensed show. The two-day free annual event was expected to attract around 2 million spectators.

Saturday’s thunderstorm threat will shift to the Northeast Sunday.

The Southeastern Virginia Hampton Roads region was spared from severe storm activity, but smoke from a 6,000-acre fire in the Great Dismal Swamp continues to plague the region down into North Carolina.

Virginia’s Environmental Quality Department downgraded Friday’s air quality red alert in some areas to orange, advising of possible health problems for sensitive individuals.

(Additional reporting by John Rondy in Milwaukee, Cynthia Johnston in Las Vegas, Matthew A. Ward in Chesapeake, Va., David Warner in Philadelphia; Writing by Molly O’Toole and Mary Wisniewski; Editing by Jerry Norton)

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ACTION PLAN NEEDED

<span class="articleLocation”>More than five months after a massive magnitude 9.0 earthquake and a deadly tsunami ravaged Japan’s northeast coast, the nation has yet to come up with a detailed action plan and the money needed to rebuild the devastated areas.

The following is a summary of where Japan’s rebuilding efforts stand.

DEATH TOLL, EVACUEES AND SHRINKING WORKING-AGE POPULATION

— About 15,690 were killed, 4,740 are missing, and 5,710 were injured.

— Many of about 5.6 million residents of the three prefectures worst hit by the March disaster have lost their homes and the number of evacuees peaked at more than 475,000 on March 14.

— Some 9,900 still live in evacuation shelters while 34,100 are staying in hotels or with relatives or friends and about 40,000 live in temporary housing.

— Japan’s northeast is aging faster than other area of a country whose population is already graying at a rapid pace. By 2030, 31.6 percent of the population is expected to be above 65 in Tohoku, whereas the country-wide estimate is 29.6 percent.

According to BNP Paribas estimates the region’s working population shrunk 8.4 percent over the past 15 years and is expected to decline by further 12.6 percent over the next decade.

RUBBLE

— The quake and tsunami left an estimated 22.6 million tonnes of rubble in the coastal towns. Out of that, nearly half has been moved to temporary storage destinations.

— By end-August, the government aims to remove debris from areas where people live and work and this goal is likely to be met. But removal of all rubble and dismantling of damaged buildings will take months, if not years, and the government aims to dispose the stored rubble by end of March, 2014.

ECONOMIC DAMAGE

— The quake and tsunami destroyed supply chains given that the northeast is home to many manufacturers. Japan’s gross domestic product fell 0.9 percent in the first quarter, tipping the economy into its second recession in three years. But in the second quarter, the economy shrank much less than foreseen as companies made strides in restoring output and is expected to bounce by 1.2 percent this quarter — probably the best performance among major industrialized nations.

— The government initially estimated the material damage from the March 11 disaster at 16-25 trillion yen ($190-$300 billion) but later lowered it to 16.9 trillion yen ($210 billion). The estimated damage is roughly double that from the 1995 Kobe earthquake.

EMERGENCY BUDGET FOR RELIEF

— The government enacted its first extra budget of 4 trillion ($50 billion) in May, and its second emergency budget of 2 trillion ($25 billion) in July.

— The government hopes to pass the third extra budget by the end of September under a new prime minister, though whether this can materialize so quickly is unclear.

DAMAGE TO FISHING AND FARMING

— Northeast Japan is known for fishing and farming. Damages in the fishing industry are estimated at 1.23 trillion yen. About 320 fishing ports, or 11 percent of all fishing ports in Japan, have been closed due to the March disaster and it would take at least another decade for full operations to resume at these ports.

— About 2.6 percent of the total farm area in Japan, or 23,600 Ha, has been washed away or submerged due to the disaster.

AID MONEY

— The Japanese Red Cross Society has so far collected 259 billion yen in relief money. Out of this, about 48 percent has been distributed to disaster victims, while the remaining amount is stuck at overburdened local governments.

(Sources: The Cabinet Office’s Reconstruction Headquarters in response to the Great East Japan Earthquake, Environment Ministry, Fukushima Prefecture, Miyagi Prefecture, Statistics Bureau, Fisheries Agency, Farm Ministry, Japanese Red Cross Society, Cabinet Office, National Police Agency, Tohoku Trade department)

(Reporting by Yuko Takeo; Additional reporting by Yoko Kubota)

 

Zone Near Fukushima Daiichi May Be Off Limits for Decades

Zone Near Fukushima Daiichi May Be Off Limits for Decades – NYTimes.com.

 

TOKYO — Broad areas around the stricken Fukushima Daiichi nuclear plant could soon be declared uninhabitable, perhaps for decades, after a government survey found radioactive contamination that far exceeded safe levels, several major media outlets said Monday.

The formal announcement, expected from the government in coming days, would be the first official recognition that the March accident could force the long-term depopulation of communities near the plant, an eventuality that scientists and some officials have been warning about for months. Lawmakers said over the weekend — and major newspapers reported Monday — that Prime Minister Naoto Kan was planning to visit Fukushima Prefecture, where the plant is, as early as Saturday to break the news directly to residents. The affected communities are all within 12 miles of the plant, an area that was evacuated immediately after the accident.

The government is expected to tell many of these residents that they will not be permitted to return to their homes for an indefinite period. It will also begin drawing up plans for compensating them by, among other things, renting their now uninhabitable land. While it is unclear if the government would specify how long these living restrictions would remain in place, news reports indicated it could be decades. That has been the case for areas around the Chernobyl plant in Ukraine after its 1986 accident.

Since the Fukushima accident, evacuations have been a sensitive topic for the government, which has been criticized for being slow to admit the extent of the disaster and trying to limit the size of the areas affected, despite possible risks to public health. Until now, Tokyo had been saying it would lift the current evacuation orders for most areas around the plant early next year, when workers are expected to stabilize Fukushima Daiichi’s damaged nuclear reactors.

The government was apparently forced to alter its plans after the survey by the Ministry of Science and Education, released over the weekend, which showed even higher than expected radiation levels within the 12-mile evacuation zone around the plant. The most heavily contaminated spot was in the town of Okuma about two miles southwest of the plant, where someone living for a year would be exposed to 508.1 millisieverts of radiation — far above the level of 20 millesieverts per year that the government considers safe.

The survey found radiation above the safe level at three dozen spots up to 12 miles from the plant. That has called into question how many residents will actually be able to return to their homes even after the plant is stabilized.

Some 80,000 people were evacuated from communities around the plant, which was crippled by the magnitude 9.0 earthquake and towering tsunami on March 11. Many of those residents now live in temporary housing or makeshift refugee shelters, and are allowed back to their homes only for brief, tightly supervised visits in which they must wear protective clothing.

Nuclear worries for Japan as quake rocks south coast

Short Sharp Science: Nuclear worries for Japan as quake rocks south coast.

Wendy Zukerman, Asia-Pacific reporter

An earthquake shook Japan’s south coast on Monday, close to Hamaoka, which has the dubious status of hosting the nation’s most perilous nuclear plant.

No damage was reported – the plant had been shut down while a tsunami-proof seawall was built – but Japan is by no means free of nuclear worries. In Fukushima, the Tokyo Electric Power Company (Tepco) reported that radiation exceeding 10 sieverts (10,000 millisieverts) per hour was found at the bottom of a ventilation stack standing between two reactors.

 

The Japan Meteorological Agency recorded that a 6.1 magnitude earthquake jolted Shizuoka Prefecture and the surrounding areas. Hamaoka is 40 kilometres from the quake’s epicentre and is considered one of the world’s most dangerous because it straddles two major geological faults.

Shingo Tsumura, an engineer at Chubu Electric Power Company (CEPC), which runs Hamaoka, told New Scientist that it is unlikely that yesterday’s 6.1 magnitude quake would have caused any damage to the nuclear plant, had it been switched on.

According to Tsumura, the ground at the power plant accelerated only 40 to 50 Gal (centimetres per second). “It is very small,” he says. “The plant will automatically shut down at 120 Gal.”

Tests last month reported that the plant could withstand ground motion of 300 Gal, with a “low possibility of collapse or damage that would cause functional failure.”

But Japanese prime minister Naoto Kan has said there is a high chance of a magnitude-8 quake in the region within 30 years – and in any case less powerful quakes have been known to affect the Hamoaka plant.

In August 2009, a magnitude-6.4 earthquake automatically shut down reactors 4 and 5 at the Hamaoka. According to the World Nuclear Association, of which CEPC is a member, some equipment was also damaged.

At Fukushima, a Tepco spokesman said that the potentially lethal doses of radiation were detected in areas that would not hamper recovery efforts. Tepco regulations state that workers at Fukushima not be exposed to more than 250 millisieverts of radiation a year.

Tepco said that the spots of high radiation could stem from debris left behind by emergency venting conducted after the March 11 earthquake and tsunami.

Meanwhile Iwate Prefecture became the third to ban the shipment of beef cattle following the detection in cows of caesium above safety limits.

Lethal radiation levels linger at Fukushima Daiichi

Short Sharp Science: Lethal radiation levels linger at Fukushima Daiichi.
gamma.jpg
(Image: Tepco)

As workers continue their efforts to secure the damaged reactors at Fukushima Daiichi, new sources of deadly doses of radiation have been uncovered at the plant.

This photo from a gamma ray camera at the plant shows radiation levels exceeding 10 sieverts per hour (in red) – the maximum level the camera can detect – at the base of a ventilation stack between reactors 1 and 2. Exposure to radiation at this level can lead to serious illness or death within seconds.

Debris leftover from emergency venting completed after the quake could be the source of these radiation hot spots, according to the Tokyo Electric Power Company. They claim the radiation is located in an area away from recovery efforts. Workers are busy removing radioactive water and installing a new cooling system so the damaged reactors can be shutdown. Company regulations prevent workers from being exposed to more than 250 millisieverts of radiation a year.

Japan endured yet another earthquake on Monday along the country’s south coast. The Hamaoka nuclear power plant, located 40 kilometres from the epicentre of the 6.1 magnitude quake, reported no damage.

The afterlife of our electronic waste

CultureLab: The afterlife of our electronic waste.

Is it real or wilful ignorance that permits us to foul our own planet with Styrofoam cups and rusted batteries? Would we curb our wasteful activities if only we knew the error of our ways? Technophiles from the Massachusetts Institute of Technology think so, and to equip the public with the knowledge we need to change our behaviour they’ve tagged our technological trash with GPS chips and tracked it across the globe. “Some trash is recycled, some is thrown away, some ends up where it shouldn’t end up,” says Carlo Ratti, director of the MIT Senseable City Lab in Cambridge, Massachusetts.

(In the past, New Scientist teamed up with the Senseable City Lab for a trash-tracking project and competition in which readers followed the trail of their own rubbish.)

The lab’s video project, Backtalk (as in trash that talks back) is currently on display at New York City’s Museum of Modern Art as part of a group show about our communication with technology. In the video, batteries, cell phones and other discarded electronic devices begin as dots in Seattle, which scatter across a map of the US, leaving a web of fluorescent trails in their wake. “In one case we saw printer cartridges go from Seattle, to the east coast, to southern California,” says Assaf Biderman, associate director at the Senseable lab. “To me, that poses a question on the benefit of recycling versus the cost of travel.”

 

Backtalk also includes photos taken from laptops that had been sent to developing countries by laptop-donation programmes in the US. New users of the “discarded” laptops consented to have their photo taken. These tracked devices reveal a life that extends far beyond the original owner’s sight. “If you can get feedback about how the end of life looks for an object, it can help you become more aware so you can rethink your actions, ” Biderman says.

The MIT lab isn’t the first to point out inefficiencies in how the US handles electronic waste, of course. Debates on how to best recycle electronics have been waged since the first televisions broke – and as they continue into the present day, these disagreements expose how complex solutions are. About 53 million tons of electronic waste was generated in 2009, according to the technology market research firm, ABI Research. With a dearth of electronic waste recycling plants in the US, many companies export their toxic products to harvesting and smelting operations in Africa and Asia. And what isn’t recycled ends up in landfills, where it poses significant health risks because of leaching lead and other metals. Watchdog groups have sought to improve electronic waste recycling for years, but companies need economic or regulatory incentives to alter their current modes of operation. In Backtalk, Biderman and Ratti reiterate how inefficient the electronic waste recycling system is, and hope their new display of data will encourage people to pause before tossing out a printer cartridge – or better yet, work to fix the system.

“A moral argument is a hard one to make,” says Adam Williams, a doctoral student at the University of Colorado, Boulder, who is studying recycling markets in China. “Successful recycling systems in China and Brazil happen when people realise they can profit off of trash,” he explains. “‘Save Mother Earth’ fails in terms of creating a system of global responsibility. Recycling needs to put money into someone’s pockets in order to work effectively.”

Yet Biderman maintains people can also be reached by driving home the concept of our interconnectedness. “After the Civil War, people realised there was a benefit to pooling their money to contribute to the common good, so they created the income tax,” he explains. “If we could create an environment where people were aware of the impact of waste or the impact of traffic, by sharing data obtained through sensors, there would be an incentive to participate in order to improve communal spaces.” Backtalk is a proof of concept that a technologically driven bottom-up approach can engage the public, he says. But if getting the message across to the broader public is anything like trying to get through to the to the over-stimulated visitors milling through the MoMA’s buzzing exhibit on communicative technologies, I’m afraid the message may be lost in digital noise.

Warming Arctic releases frozen organic air pollutants

Warming Arctic releases frozen organic air pollutants – environment – 28 July 2011 – New Scientist.

  • 28 July 2011

Air pollutants emitted decades ago are coming back to haunt us. As the Arctic warms, persistent organic pollutants, or POPs, trapped in snow and ice are being re-released. This unwelcome return has been suspected for some time but is now confirmed by 16 years’ worth of data.

POPs travel around the globe on winds, build up in food and water supplies, and accumulate in animal body fat. They have also been linked to serious human health problems, including cancer, and can be passed from mother to fetus. They have been banned under the Stockholm convention since 2004.

The new study looked at air concentrations of POPs up to 2009 in Svalbard, Norway, and in Canada’s Nunavut province, and found an increase since 2000 (Nature Climate Change, DOI: 10.1038/nclimate1167).

Earth's time bombs may have killed the dinosaurs

Earth’s time bombs may have killed the dinosaurs – environment – 27 July 2011 – New Scientist.

THE fate of the dinosaurs may have been sealed half a billion years before life even appeared, by two geological time bombs that still lurk near our planet’s core.

A controversial new hypothesis links massive eruptions of lava that coincided with many of Earth’s largest extinctions to two unusually hot blobs of mantle 2800 kilometres beneath the crust. The blobs formed just after the Earth itself, 4.5 billion years ago. If the hypothesis is correct, they have sporadically burst through the planet’s crust, creating enormous oceans of lava which poisoned the atmosphere and wiped out entire branches of the tree of life.

Debates still rage over what caused different mass extinctions, including the one that wiped out the dinosaurs. An asteroid that smashed into Earth 65 million years ago is no doubt partially to blame for the Cretaceous giants’ demise. But a less-known school of thought has it that this and other extinctions occurred when cracks in the crust let huge amounts of lava gush from the bowels of the Earth. Each event flooded at least 100,000 square kilometres, leaving behind distinct geological regions known as large igneous provinces (LIPs), such as India’s Deccan traps, formed when the dinosaurs went extinct (see map). “There is an amazing correlation between mass extinctions and LIPs,” says Andrew Kerr at the University of Cardiff, UK.

Now Matthew Jackson at Boston University, and colleagues, claim to have found evidence that LIPs are fed by 4.5-billion-year-old stores of mantle.

Most of the mantle has been modified by plate tectonics since then (see “Diamonds and the birth of plate tectonics”). But last year Jackson’s team found that 62-million-year-old basalts from the North Atlantic LIP contain isotopes of helium, hafnium and lead in ratios that reflect the chemistry of early Earth’s mantle.

They have now found similar lead isotope ratios in other LIP rocks, and say that LIPs in general may have an ancient source. Their analysis suggests this mantle contains an abundance of radioactive, heat-producing elements, making it unusually hot and potentially more likely to form the large quantities of lava needed to create LIPs (Nature, DOI: 10.1038/nature10326).

The ancient stores might still exist. Studies to probe the mantle’s structure with seismic waves have revealed two unusual areas some 2800 kilometres down, beneath Africa and the Pacific Ocean. Trond Torsvik of the University of Oslo, Norway, and colleagues recently showed that most LIPs formed while one of these two areas lay directly beneath them.

“It’s an interesting idea – that a giant blob of hot magma might burp from near Earth’s core every now and then, causing havoc for life,” says Gerta Keller at Princeton University, but adds more work is needed to support the hypothesis.

Kerr agrees: “This will be controversial – it flies in the face of much of the research from the last 30 years.” Conventional wisdom, he points out, suggests LIPs have a more prosaic source – young mantle formed when oceanic crust returns to the mantle through subduction.

But Torsvik is enthused. Having spent 10 years collecting evidence that his two mantle blobs have been stable for at least 540 million years, the idea that they contain primordial mantle is “like music to my ears”, he says.

Diamonds and the birth of plate tectonics

The inside of our planet is a magma-churning power house. As a result, very little remains from the millennia just after Earth formed. The two blobs of ancient magma that may be responsible for several mass extinctions are an exception.

Some diamonds, it turns out, may also serve as time capsules. A new study suggests that locked inside them is the secret of when the continents formed.

We knew that plate tectonics have been pushing new bits of crust into existence and engulfing old chunks back into the mantle for hundreds of millions of years. What we didn’t know is when it all started. Stephen Richardson at the University of Cape Town, South Africa, and Steven Shirey of the Carnegie Institution for Science in Washington DC collected thousands of ancient diamonds from around the world. Gems considered to be flawed by the jewellery industry can contain tiny clumps of minerals from the rocks in which they formed. Some clumps are made of peridotite, others of the rarer eclogite, which is only formed when volcanic rocks from the surface are forced deep into the mantle and crushed in the immense pressure and heat there. To get eclogite, you need plate tectonics.

When Richardson and Shirey dated the mineral clumps, they found that the peridotite ranged from 2 to 3.5 billion years old, but the oldest eclogite was 3 billion years old (Science, DOI: 10.1126/science.1206275). This, say the researchers, proves that plate tectonics cannot have been active before then. Michael Marshall

Where did the Gulf's spilt oil and gas go?

Where did the Gulf’s spilt oil and gas go? – environment – 18 July 2011 – New Scientist.

The puzzle over what happened to the oil and gas released during the Deepwater Horizon oil spill in the Gulf of Mexico last year has been partially solved.

Oil is composed of many thousands of different chemicals but the plume that stretched through the Gulf contained relatively few. Now chemists have worked out what happened to the rest.

Christopher Reddy, an environmental chemist at the Woods Hole Oceanographic Institution in Massachusetts, and colleagues, used a remotely operated submarine to collect samples directly from the leaking well in June 2010 and compared these with samples taken from elsewhere in the oil plume.

Reddy likens the oil and gas molecules gushing out of the wellhead to passengers on an elevator. “We wanted to know which compounds got off the elevator instead of going up,” he says.

The team found that water-soluble compounds dissolved in neutrally buoyant seawater about 400 metres above the wellhead. These included benzene, toluene, ethylbenzene and xylene – a toxic suite collectively referred to as BTEX. And in this layer they stayed. By contrast, the compounds that reached the surface were mainly insoluble.

Deep difference

Reddy’s work helps to answer one of the major questions from the oil spill – what happened to all that oil and gas, says David Valentine, a microbial geochemist at the University of California, Santa Barbara.

The results show how deep oil spills differ from surface spills, where many toxic compounds quickly evaporate rather than contaminating the water.

The team’s measurements also show that BTEX concentrations reached up to 78 micrograms per litre. That level is several orders of magnitude higher than known toxicity levels for marine organisms, according to Judith McDowell, a zoologist also at Woods Hole.

Journal reference: Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.1101242108

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