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Radioactivity levels

 
Date: 01-05-12
 
 
ChNPP68 μR/h
Pripyat66 μR/h
Chernobyl19 μR/h
CP Dityatki8 μR/h
Kiev10 μR/h
Moscow11 μR/h
Vienna10 μR/h
Detroit8 μR/h

Poll

Should the city of Pripyat be saved?
Yes, and leave everything as is.
64%
Yes, and turn it into a memorial complex.
28%
No, bear to the ground.
6%
I do not care
2%
Total votes: 19748

The mystery of Chernobyl

A bitter dispute is raging over whether the fallout zone is a wasteland or wonderland. Now, a team of scientists is heading back into the contaminated area to find out the truth.

'We walked out into a wasteland, grey and desolate. The buildings had deteriorated, windows had been smashed. Trees and weeds had grown over everything: it was a ghost town." It reads like a passage from a post-apocalyptic novel, such as Cormac McCarthy's The Road; in fact, it's how Tim Mousseau describes his first visit to Chernobyl.

In 1999, this Professor of Biological Sciences from the University of South Carolina travelled to the site of the world's most horrific nuclear accident, alongside Professor Anders Møller, an ornithologist and evolutionary biologist from the Pierre and Marie Curie University in Paris. Their on-site research has sparked an intense controversy over the effects of radiation on humans and animals – one which they hope their latest trip into the fallout zone, which sets out in two weeks, will help to resolve. The basic facts of Chernobyl are well known. At 1.23am on April 26, 1986, reactor number four at the Soviet nuclear power plant (sited in modern-day Ukraine) exploded, after an electrical test went horribly wrong. The radioactive material released was hundreds of times greater than the fallout over Hiroshima and Nagasaki, polluting about 80,000 square miles of land across Europe and spreading radioactive rain as far as north-west Ireland. In the wake of the accident, more than 300,000 people were evacuated and an 800 square mile exclusion zone created around the reactor. Yet recently it has been reported that the abandoned town of Pripyat has become a wildlife haven. There have been sightings of wolves, bears and moose wandering through the deserted streets, and swifts swoop round abandoned office blocks. The implication is that if wildlife can return so soon, nuclear radiation – and nuclear power – might be less dangerous than has been suggested. James Lovelock, the creator of the Gaia theory, has even written that the natural world "would welcome nuclear waste as the perfect guardian against greedy developers… the preference of wildlife for nuclear-waste sites suggests that the best sites for its disposal are the tropical forests and other habitats in need of a reliable guardian against their destruction by hungry farmers and developers".

According to a UN report in 2005, long-term cancers caused by Chernobyl will eventually kill about 4,000 people: an alarming total, but less than predicted. In fact, in an age of "dirty bombs" and nuclear proliferation, Chernobyl functions as a grim experiment into the consequences of extensive nuclear fallout. Although radiation levels have dropped significantly over the 23 years, there are still "hot" regions. Prof Mousseau says that the most contaminated areas measure 300 microSieverts per hour on the Geiger counter, the equivalent of 1,200 times normal radiation levels, or 15 times as much as a chest X-ray. "Long-term exposure would be deleterious," he adds drily. The real problem, however, is environmental contamination of radionucleotides, caesium, strontium, and plutonium, which have half-lives of 30,000, 29,000 and 24,000 years respectively. Since this means that over that time period, these chemicals will decay to half their previous concentrations, they will contaminate the land for years. "What you need to worry about is eating the food, because ingestion is the main way that one becomes exposed to radiation poisoning here," says Prof Mousseau. And despite the stories about nature thriving in the Chernobyl area, Prof Mousseau is not convinced. The first discovery that he and Prof Møller made was that birds in the fallout zone were suffering increased levels of genetic mutations. The pair examined 20,000 barn swallows and found crippled toes, deformed beaks, malformed tails, irregularly shaped eyes and tumours. Some birds had red plumage where it should have been blue, or blue where it should have been red. Thanks to the contamination of the food supply, bird species have declined by more than 50 per cent in high-radiation areas. Only a fraction of the swallows are reproducing, and of those that do lay eggs, only five per cent hatch. Fewer than a third of birds survive to become adults. Prof Mousseau and Prof Møller could confirm that these abnormalities were genetic by examining the swallows' sperm.

One of the pair's most interesting findings, outlined in a paper last year, is the connection between antioxidants, radiation and plumage colour: in other words, birds with the brightest plumage are more likely to die. The explanation is simple. In humans and birds, antioxidants help to quash the effects of radiation. "Birds that migrate long distances and have bright plumage, such as swallows, have a very high metabolic rate and produce a lot of free radicals as a by-product, which damage their tissues," says Prof Mousseau. "They then use stockpiles of antioxidants in their blood and liver to offset this potential damage. Females allocate large amounts of antioxidants to their eggs, which is the reason why the yolk is bright yellow." But at the end of the birds' migration route, their energy reserves need to be replenished. "What appears to be happening is that in highly contaminated areas, they simply can't do this." As a result, swallows and great tits are unable to maintain their bright plumage and channel sufficient antioxidants into their eggs, and few chicks hatch. The insects that they feed on are suffering, too. In the most contaminated areas, there are fewer butterflies, bumblebees, grasshoppers, dragonflies and spiders. "The fact that insects, including pollinators, are sensitive to elevated contaminants has a significant impact on the rest of the ecosystem," says Prof Mousseau. It seems like a portrait of an ecosystem in crisis – so how have other scientists reported the opposite? Dr Robert Baker and Dr Ronald Chesser, from Texas Tech University, conducted their own study, published in the journal American Scientist in 2006: "We were surprised by the diversity of mammals living in the shadow of the ruined reactor only eight years after meltdown." Their long-term studies contradicted those of Professors Mousseau and Møller, describing the region as "thriving", with a wild boar population 10 to 15 times higher in the exclusion zone than outside. They also failed to find any type of elevated mutation rate, or evidence that survival among animals living around Chernobyl differs from those in clean environments. "Chernobyl is not a lunar landscape," says Prof Mousseau. "You can hear birds and mammals, spot the occasional wolf and fox, there are trees and plants – so it's not a complete desert. The reason for this misunderstanding is because there is a quiltwork of contamination, so you could have lots of organisms in one area, and none in another. To a trained biologist, though, it's very obvious." Those are fighting words – particularly as both teams will shortly publish papers about mammals in the region that have diametrically opposed results. For his part, Dr Chesser says: "I think that the discrepancy between our work and that of Møller and Mousseau stems from their inattention to details. I will go no further than that. I have no doubt that our work is accurate." Prof Mousseau is equally forthright: "I'd rather avoid discussing specifics of their work, but no other folks apart from us have been rigorously counting organisms and measuring their distribution and the background contamination. Their work is based on anecdotes." Regardless of who is right or wrong, there is another tragedy here. Prof Mousseau has started working with the Hospital for Radiation Biology, in Kiev, on a long-term study of humans who live in the area: more than 11,000 adults and 2,000 children in the Narodichesky region, 50 miles from Chernobyl. Prof Mousseau says that the incidence among locals of cancer, birth defects and reduced lifespan is alarmingly high. "There is a growing mountain of information that all points to significant consequences to the human population of chronic radiation exposure," he warns. "What will be the consequences for the children of these children?

Автор: 
Telegraph.co.uk

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