IN BRIEF

The latest news on our planet

800 000 years under the ice...

A recent core sample drilled 3 270 metres deep into the Antarctic ice as part of the European Project for Ice Coring in Antarctica (EPICA) shows variations in carbon dioxide (CO2) and methane (CH4) over the past 800 000 years. It is the first time that ice as old as this has ever been studied. A whole host of data has shown that at no time during the entire period covered by the core sample have atmospheric levels of these two potent greenhouse gases (GHG) been as high as they are today.

The sample revealed a new cycle of CO2 variation over several thousand years. It also uncovered a strong correlation between increases in atmospheric methane and greater monsoon activity in SouthEast Asia. More surprisingly, a rapid fluctuation in CO2 appears to have marked each glacial period, which the experts say stems from variations in thermohaline circulation - a phenomenon still poorly understood by climatologists.

All this valuable data is giving researchers additional clues concerning the impact of global warming.

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...and 6 000 years under the sand

According to the conclusions of a new study published by geologist Stephan Kropelin's research team from the University of Cologne (DE), the Sahara was formed over a period of 2 000 years rather than a few centuries, as claimed by the latest theory. It is hard to imagine that, only 6 000 years ago, there was an abundance of grassy plains, rivers and lakes in what is now a vast oven. When the monsoons diminished 4 800 years ago, the plant cover is thought to have gradually shrunk until, two millennia later, it had been replaced by huge swathes of sand.

These are the results of an analysis of numerous paleo-environmental indicators (including pollen, spores and micro-organisms) drawn from core samples of sediments from Lake Yoa in northern Chad. It is one of very few water points in the region and is supplied by an underground aquifer. This makes Lake Yoa an ideal place to study the Sahara's wet period because its sediment layers have not been swept away by erosion. The study comes at an opportune time to correct climate prediction models - essential tools for anticipating the effects of global warming.

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Low-cost soil remediation

The European Cleansoil project has recently developed a new method to reclaim polluted soil in situ and at lower cost. At present, soil remediation often requires polluted soil to be transported to another location for cleaning or storing. This is a very expensive solution that is not suited to every situation: for instance, it is impossible to excavate soil from under buildings.

Cleansoil's new process is based on a network of horizontal pipes laid in the ground containing pockets of sorbent. These capture the pollutants that filter down into the earth with surface water. Once the soil has been cleaned, the sorbent is recovered and regenerated for future use.

The technique has already proven its effectiveness in Russia and the Ukraine, where it has been used to remediate soil polluted with petrochemical residues and pesticides. This new process is the result of public/private collaboration and is certain to be a useful weapon in combating the pollution affecting nearly 1.5 million sites in Europe.


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Extreme geothermy

Can geothermal energy efficiency be increased tenfold by exploiting hitherto-unexplored geological areas? The Iceland Deep Drilling Project (IDDP) hopes that it can. The project, launched in 2004, aims to assess the feasibility of exploiting very high energypotential geothermal systems.

IDDP scientists plan to drill a 5-km-deep well on the site of the Krafla volcano in northern Iceland in order to reach a hydrothermal reservoir at a temperature of around 400°C containing fluids at supercritical conditions.

The chief objective is to analyse the precise composition of these fluids. Pre-drilling began in mid-June 2008 and the first 3-km well is expected to be completed by the end of the year. "Once we have determined the exact nature of the geothermal fluid, we will be able to develop suitable tools and techniques for exploiting its heat," says an enthusiastic Gudmundur Ómar Friðleifsson, the project's Head Geologist. It is the first time that work has ever been envisaged under such extreme conditions of temperature, as current geothermal sources are no hotter than 250 °C.

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Calcium: an ally against CO2?

A team of researchers from the University of Newcastle (UK) is studying a new process for exploiting the soil's role as a natural "carbon sink". The process relies on the fixation of atmospheric carbon dioxide (CO2) by plants: under certain conditions, plants release a portion of the CO2 that they have absorbed into the ground in the form of acid.

In most cases, this CO2 returns to the atmosphere or is dissolved in groundwater. However, in calcium-rich soil, the acid reacts with the calcium over very long periods to form calcium carbonate (a stable compound which we all know as limescale). The researchers believe it is possible to boost this fixation mechanism by enriching soil with large amounts of calcium.

They estimate that the method (which is currently being validated by laboratory tests) could help to reduce the UK's emissions by between 5% and 10%. If it proves effective, digital models will be developed to define the absorption speed and quantity of CO2 trapped in various types of soil. The results are expected to be announced in February 2009.

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Magnetic influence

The Earth's magnetic field might be invisible, but it has a profound impact on our lives. After analysing the activity of the geomagnetic field between 1948 and 1997, Oleg Shumilov, from the Institute of North Industrial Ecology Problems (RU) has identified three annual seasonal peaks that bear an eerie relation with the pattern of suicides in the Russian town of Kirovsk. The researcher also used 6 000 ultrasound scans performed between 1995 and 2003 to compare variations in foetal heart rate with the Earth's geomagnetic activity.

In 15 % of cases, disruptions to the foetal heart rate coincided with periods of great geomagnetic activity. These results, presented at the annual general assembly of the European Geosciences Union in April 2008, can be added to a long list of scientific studies that have found a link between magnetism and physical and mental health.

These results, presented at the annual general assembly of the European Geosciences Union in April 2008, can be added to a long list of scientific studies that have found a link between magnetism and physical and mental health.

The experts believe that geomagnetism may well play a part in regulating the human biological clock. Certain variations in the magnetic field, especially extreme phenomena like magnetic storms, could have a marked impact on some sectors of the population...


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Nuclear mantle

Are there really nuclear reactors lying deep within the bowels of the earth? In the 1970s, scientists picked up clues that such a naturally occurring slow fission reaction might indeed be happening at the Oklo uranium mine in Gabon, where they found a portion of the ore to be abnormally deficient in 235U, seemingly indicating the occurrence of spontaneous nuclear fission. The physicist, Marvin Herndon, was the first to posit the existence of such a "georeactor", although he believed it to be located in the Earth's core, making his theory highly implausible.

Rob de Meijer from the University of the Western Cape (ZA) and Wim van Westrenen from the Free University of Amsterdam (NL) have recently revisited Herndon's hypothesis, this time siting the reactor in the Earth's mantle, right alongside the core. The two researchers base their theory on a study pinpointing a difference in concentration of a neodymium isotope, 142Nd, within the Earth's rocks, and of chondrites, a type of meteorite. The researchers have inferred from these results that there was probably a strong concentration of uranium, thorium and potassium at the interface between the Earth's core and mantle. However, their theory is purely speculative pending the development of giant neutrino detectors - the only means of identifying the geological regions where major radioactive reactions occur.


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