Wildlife in an animal sanctuary in Belarus, close to the site of the Chernobyl nuclear disaster in 1986, continue to show high levels of accumulated radioactive cesium, researchers say.
Wildlife in an animal sanctuary in Belarus, close to the site of the Chernobyl nuclear disaster in 1986, continue to show high levels of accumulated radioactive cesium, researchers say.
A similar pattern has emerged in Japan's Fukushima Prefecture, where a meltdown occurred at the Fukushima No. 1 nuclear power plant following the March 11, 2011, Great East Japan Earthquake. There, surveys show that wild boar and other animals are displaying cesium levels in excess of what is deemed safe for human consumption.
The sanctuary in Belarus, called the Polessie State Radiation and Ecological Reserve, covers 2,165 square kilometers. It was established north of the Chernobyl Nuclear Power Plant in 1988.
To this day, the area remains highly contaminated. Of the total amount of cesium-137 that fell on Belarus, 30 percent, or 4,810 terabecquerels (1 terabecquerel is a trillion becquerels), fell on the area where the preserve is located, while 70 percent, (or 444 terabecquerels) of the strontium-90 fallout landed there.
Most of the plutonium fallout, 14.8 terabecquerels, ended up on the area.
The area has been declared off-limits to human habitation. The absence of people gives the impression that the area is an animal kingdom.
Researchers have spent years studying radioactive substances in the muscle tissue of the sanctuary's wildlife.
"Although the amount of cesium-137, which has a half-life of about 30 years, in mammals and other wildlife seemed to be declining between 2001 and 2005, it underwent a resurgence from 2006 to 2010," said an official in charge of research on the area's ecology and fauna at the preserve.
For example, the amount of cesium-137 accumulated in each kilogram of flesh extracted from wolves--which sit at the top of the food chain--was measured at 40.8 kilobecquerels, based on 96 samples, between 1998 and 2000. The figure dropped to 23.9 kilobecquerels, based on 79 samples, from 2001 to 2005.
However, the level rose to 30.7 kilobecquerels, based on 19 samples, from 2006 to 2010.
Researchers don't really understand the reasons for the spike. The same change has also been observed in wild boar and other animals.
Thus, the overall level in Belarus wildlife continues to be high.
There are also large discrepancies between individual animals. When researchers extracted samples from 100 raccoon dogs from 2006 to 2010, they found levels ranging from as high as 1,417.5 kilobecquerels to as low as 0.3 kilobecquerel.
In Fukushima Prefecture, where the nuclear disaster occurred last March, accumulated levels of cesium-137 and cesium-134 (the latter has a half-life of about two years) in wild game have been surveyed since October 2011.
The species being studied are wild boar, Asian black bears, Japanese pheasants, copper pheasants, a variety of duck species and Japanese deer. Results are released every two weeks or so.
The highest level recorded thus far was in a wild boar captured in Nihonmatsu. The animal recorded a level of 14.6 kilobecquerels per kilogram.
"Samples vary even between wildlife captured in the same area," said an official at the prefecture's natural preservation office. "(In these areas), the levels are neither all low nor all high."
No conclusions have been drawn yet as research into the effects of radioactive substances on wildlife is continuing.
"We haven't seen any changes in animal lifespans," the official at Polessie State Radiation and Ecological Reserve, said.
But as a caveat, he said the study concerns only wildlife.
"So we can't say that the effect on humans is necessarily the same."