Results 1 to 1 of 1
05-04-2011, 01:26 AM #1
25 Years After the Nuclear Disaster!25 Years After the Nuclear Disaster!
Returning to Abandoned Land...
On the 25th anniversary of the explosion of the number four reactor at Chernobyl, the exclusion zone is not a dead zone.
Yes, a huge swath of what is now Ukraine, Belarus, and Russia was blanketed by dangerous radiation. And hundreds of thousands of people—entire towns—were relocated.
But within a 1,100-square-mile (2,850-square-kilometer) area that remains cleared of most people and agriculture, the wildlife have moved in. A surprising variety of animals actually appear to be thriving in a landscape that is devoid of human activity. Scientists have observed that other species show signs of troubling genetic changes, evidence of the continuing long-term aftermath of what is still seen as the world's worst nuclear disaster.
Even though authorities now reckon Japan's *** ushima Daiichi crisis in Japan to be on par with the April 26, 1986 accident in the northern Ukraine in terms of potential consequences, Chernobyl's immediate impact was far greater, because the reactor was built with no containment vessel. As a result, some 30 workers were killed and as many as 4,000 people are expected to die eventually as a result of radiation exposure from the Chernobyl plant, according to the World Health Organization.
Despite the questions about the long-term health effects of exposure to the continuing radiation hazards, some people, like this 73-year-old woman in the mostly abandoned village of Paryshiv, have returned to the site.
Though radiation is no longer raining down on the land, levels of dangerous cesium-137, a radioactive isotope that is among the most dangerous to humans, are still elevated throughout the immediate area and as far away as Norway and Germany. Because cesium-137 can accumulate as it passes up the food chain, these chickens could be carrying elevated levels of radiation, absorbed by their food, which then would be passed on to their human consumers.
Appearance Versus Reality...
A worker on the Belarusian side of the Chernobyl exclusion zone measures radiation in 2006, shortly before the 20th anniversary of the disaster. Both Belarus and the Ukraine have turned their shares of the most heavily contaminated 11.5 square miles (30 square km) into nature preserves, where previously rare animals at least appear to flourish: There are accounts of verdant forests bursting with endangered birds and large game, defying the perception that the land is a dead place.
Yet some scientists believe the area is recovered only in appearance. "It's not at all what people are claiming it to be," said Tim Mousseau, a biologist at the University of South Carolina, Columbia, and a National Geographic Society grantee who has been studying animals in the Ukrainian Chernobyl exclusion zone since 2000. "I think this has to do with the fact that people are so surprised to see anything there. People have this expectation that it's a lunar landscape."
Impact on Agricultural Animals...
A pig walks in front of a ruined house in the near-abandoned village of Tulgovichi, Belarus, which before the Chernobyl disaster was home to 1,000 people. Now there are just eight residents.
Swiftly after the disaster, some 50,000 cattle and 13,000 pigs were relocated along with human inhabitants rom the Chernobyl exclusion zone. Due to the difficulties in caring for the animals and finding food in the areas to which they had been moved, most of the relocated animals were slaughtered. According to a 2006 report by the International Atomic Energy Agency (IAEA), a UN body that seeks to promote peaceful use of nuclear technology, though, that may have been Chernobyl’s most lasting effect on agricultural animals. No higher incidence of birth defects was observed in cows or pigs from nearby contaminated areas, even just a few years after the accident.
Abnormalities in Birds...
Timothy Mousseau, a biological scientist, has been studying bird populations in Chernobyl along with collaborator Anders Mřller of Paris-Sud University in Orsay, France, for more than a decade. In one study, Mousseau found that barn swallows living in heavily contaminated areas had much higher rates of abnormalities--ranging from partial albinism (b, c, d), deformed beaks (e, f), and bent or asymmetrical tail feathers (h, i). Later studies found that the contaminated areas also had lower biodiversity, with half the species of birds found in "clean" areas, lower populations (reduced by as much as 60 percent), and that birds living in the Chernobyl area had smaller brains.
"We really weren't expecting to find anything," Mousseau said of his and Mřller's first formal trip to Chernobyl in 2000. "The conventional wisdom had been, until recently, that there were very few consequences."
On the other hand, Mousseau admits that some birds have thrived: drab, non-migratory birds seem to be doing very well, "possibly because they have no competitors," he said. These birds don't use up their carotenoids, which are powerful antioxidants, to create colorful plumage, and they don't need to spend extra energy on long migrations, so their immune systems may be stronger, Mousseau theorized.
Beneficial Effects for Some Fish...
The possibility of radioactive particles (and the chance of big fines) didn't deter Belarusian fishing poachers on the Pripyats river from pulling out these fish, just 18 miles (30km) from the center of the disaster zone.
Jim Smith, an aquatic environmental scientist at the University of Portsmouth, measured contamination levels in fish in lakes in Ukraine, Belarus, and Russia. While he said he wouldn't advocate eating fish from the more contaminated lakes, studies showed no "obvious deformities, though they did find some impacts on the reproductive system," he said.
Overall, he said, fish have mostly benefited from the disaster. "We've caught thousands of fish in lakes in Belarus and Ukraine. The catfish are huge," he said. In particular, the cooling pond, which was heavily contaminated after the reactor exploded, was found to contain 36 species of fish, including some endangered ones. That's partly because the water in the pond was warmer than in the nearby lakes, Smith said.
But the fish living near areas where agriculture continues have been found to be less contaminated than those in the exclusion zone, Smith said. That's because potassium runoff from fertilizers blocks the absorption of cesium-137.
Growing Population of Wolves...
While wolves, moose, deer, and other large animals can be found within the exclusion zone, Mousseau says "they're not overwhelming the place."
But the IAEA report found "significant" numbers of wolves shortly after the disaster, and Mary Mycio, author of the 2005 book "Wormwood Forest" about the nuclear disaster, reported that the wolf population had grown so large that hunters bagged 100 during the 2003-2004 hunting season. Hunting continues today, as seen in this 2011 photo of a wolf kill near the exclusion zone.
Mixed Outcome on Mammals...
While populations of hoofed animals have bounced back with few to no visible mutations, grazing animals like these elk (seen within the exclusion zone last month) do contain higher levels of radiation in their bodies, and not just within the zone.
Because these animals graze on lichens and mushrooms, which act as sponges for radiation, animals slaughtered shortly after the accident as far away as Norway contained nearly 14,000 becquerels per kilogram, more than twice the legal limit for human consumption in Norway and 46 times the limit in neighboring Sweden. Even today, reindeer in Norway are showing elevated levels of radioactive cesium in their meat, though not at a level that would cause authorities concern.
Inside the exclusion zone, the animals aren't hunted for their meat. Regardless, they are hit with background radiation (and consuming it through contaminated grasses and lichens) at a dose rate that shouldn't—in theory—hurt them. The dose is "lower than we would expect to see effects on a population level," Smith said.
Yet other scientists say the radiation levels are harming even large animals like these: Mousseau and colleagues counted animal tracks after a fresh snow, "and lo and behold, our data shows very clearly there are many fewer mammals in these most contaminated areas."
Mice 'Immune' to the Radiation?
Since 1992, American and Ukrainian scientists have been studying mice from the most contaminated regions of the Chernobyl disaster.
The mice, as well as other small rodents like voles, appear to be thriving. One 1996 study, by Texas Tech University's Robert Baker and University of Georgia’s Ron Chesser, seemed to find large numbers of mutation rates in otherwise healthy voles in Chernobyl; the authors retracted the paper a year later, saying they could no longer find evidence of mutations.
The same authors also transplanted healthy wild mice into cages in the Red Forest, the most severely contaminated area, then examined their chromosomes. "The mice seemed to have a natural 'immunity' to harm from radiation," Chesser and Baker wrote in a 2006 article published by Sigma Xi, the Scientific Research Society.
Threatened, but Not by Radiation...
Przewalski horses, extinct in the wild, are found in just a few nature reserves, including the Chernobyl exclusion zone.
In 1998, 31 Przewalski horses were transferred to the zone; eight died during transport or soon after, but the remaining 23 horses began breeding.
According to Tatjana Zharkikh, recently of Ukraine’s Askania Nova Zoo, which also houses a population of Przewalski horses, the population peaked at 65 animals but many have since been shot by poachers.
"Przewalski horses adapted quite well to the climate and environment of Kiev Region; there are no data about negative influence of radiation on the animal yet," she said via email.
...being a human...