Chernobyl: Portrait of a Catastrophe
It's easy to see where radioactive contaminants settled after the worst nuclear accident on earth: All you have to do is look for the statues of Lenin.
"You'll still find Lenin statues in this area because no one's around to pull them down," said Dr. Cham E. Dallas, who first visited the Chernobyl area in 1991. "The skilled workers leave, the industry breaks down, the towns look run down. But people start coming back to the evacuated villages because they don't see anything that appears unusual."
Towns contaminated by the Chernobyl disaster look like snapshots from another time. Few people live in the heavily contaminated areas so communities have changed little in the past six years.
Deadly remnants of nuclear contamination persist and exposure may cause genetic side effects, Dallas said. And those effects become more visible daily.
"They are suffering terrible side effects," he said. "Their hospitals are filling with children who have leukemia because the five- to six-year latent period has passed. You don't see lots of children in contaminated areas because their parents have sent them to live with relatives or in refugee camps."
And those are just the visible effects on humans.
"Of particular interest are the ecological consequences, which are more long term," said Dallas, a toxicologist at the UGA College of Pharmacy. "We don't know exactly what they are, but they may be more severe than the human ones we can see right now. My concern is what happens when radionuclides hit humans, animals and other segments of the ecological cycle. What does it cost to relocate and retool whole populations?"
In the next few years Dallas and his colleagues plan to examine the area where the world's largest and most widespread radionuclide release occurred -- "both in terms of radionuclide load and geographic dispersal," he said. "We hope to see what the short-term genotoxic consequences are, evaluate the environmental and ecological health problems, and formulate an integrated remedial action plan."
After struggling for more than 10 years to establish a research program with the former Soviet Union, Dallas finally succeeded last year with the independent republics. UGA and Eastern Bloc scientists now are working together to assess nuclear contamination levels and their environmental effects.
The unprecedented collaboration calls for the exchange of scientists and technology between UGA and Oranoe, the field research station closest to the Chernobyl disaster site. "They are very good scientists with good training and intuitive abilities" Dallas said, "but they are woefully deficient in Western equipment, technology and the most modern radionuclide measuring techniques. You are literally cut off from the world there; you're not only out in the sticks, you're out in the contaminated sticks."
Findings of the international team will help guide clean-up efforts at Chernobyl and may prove useful in other ways.
"Our research will provide a database for governments in the event of small- or large-scale nuclear disasters," Dallas said. "Nuclear disasters in the future could result from nuclear reactor accidents like Chernobyl, but more likely they will result from terrorist groups or irresponsible nations using tactical nuclear weapons."
So far, Dallas has made five trips to republics of the former Soviet Union to iron out agreements, validate the wealth of data already collected at the site, test his proposed research techniques and collect additional data. He plans to make several more trips during each of the next few years.
His most recent trip included six other UGA researchers, counting the four from the Savannah River Ecology Laboratory. At Oranoe they were joined by Eastern Bloc scientists and technicians; the group sampled fish, mollusks, water and sediments from 10 ponds within and outside the Chernobyl Exclusion Zone, a highly contaminated area blocked by military units.
Using sophisticated instruments and techniques that are used to monitor radiation levels at the Savannah River Site, UGA researchers are now determining radioactive cesium levels in Chernobyl samples. They also are evaluating possible genetic damage from contaminant exposure, and they plan to contrast their findings to similar research conducted at the Savannah River Site. Those comparisons may help predict radiation effects at known exposure levels.
Contamination levels obviously are much greater at Chernobyl than at the Savannah River Site, but the two share some similarities. For example, both have nutrient-poor soils, a factor that contributes to radiocesium concentration in food chains. People who live near Chernobyl fish and hunt to supplement their diet, and may run an increased risk of exposure to radiocesium, Dallas said.
"The problems in Eastern Europe are 10 times worse than anything we have here and they have 10 times fewer resources," he said. "We will provide data to help them prioritize where to use their resources.
"It sounds great about providing the information to solve these problems in the future, but these people are suffering now and I want to help them now. Whenever I look at a photograph of what we call the Chernobyl children, it gives me incentive to keep going," Dallas said. "And I believe the information we provide actually can be of service to them right now."
Now that scientists have a better handle on how radionuclides travel through the environment, they've set their sights on ways to stop them from doing so.
Researchers at the Savannah River Ecology Laboratory are testing "remediation" methods that will restrict or limit the amount of radioactivity that enters the food chain from contaminated soil.
The conventional strategy for remediating contaminated soil has been to "muck it and truck it" -- scoop it up and haul it away.
But SREL scientists are exploring new options, like "lock it or block it" - - locking it under a protective shield of water or blocking it from being taken up by plants and animals.
Dr. F. Ward Whicker and Dr. Domy C. Adriano, a senior research ecologist and head of the SREL biogeochemical division, are conducting studies on plants grown on cesium-contaminated soils at the Savannah River Site.
Their research may help ameliorate problems at Chernobyl, which has soils similar to those at the Savannah River Site, and other nuclear-contaminated areas.
Like soils in many parts of the Southeast, soils at the Savannah River Site are sandy and nutrient poor; farming them is like trying to farm the beach.
Because of the soil's low levels of potassium and calcium, their chemical analogues -- cesium and strontium, respectively -- accumulate in the food chain.
For example, there is a higher probability of a plant root absorbing an analogous radioactive atom in fallout-contaminated soil at the Savannah River Site than there would be in the Midwest, where soils are rich in potassium and calcium, and fallout exposure is minimal.
Whicker is comparing cesium uptake in vegetable crops irrigated with well water to those irrigated with water from a contaminated pond. He has found that uptake varies with the crop.
For example, turnip greens contain higher levels of the radioactive cesium than turnip tubers, which contain about the same levels as lettuce leaves.
In similar studies, Adriano is looking at ways to eliminate or minimize cesium uptake by roots. This fall he planted vegetable crops in test plots located on cesium-contaminated mudflats. In one trial he applied high levels of potassium fertilizer to the soil. An abundance of potassium should reduce the amount of cesium that plant roots absorb. Data from a similar study conducted last summer showed the application of potassium reduced cesium uptake by two to three times.
Adriano spread another natural mineral, zeolite, in a second trial. Previous research has shown that zeolite binds cesium ions and prevents their uptake, Adriano said.
In another experiment he covered contaminated soil with a foot of clean topsoil. "The rationale is that roots of crops primarily will reside in the clean soil layer and few roots will protrude into the contaminated soil," he said. "This method is primarily effective for shallow-rooted plants, such as turnips, radishes, carrots and onions."
Adriano also has tried inserting a slow-releasing herbicide system, called Biobarrier, between the contaminated sediment and a layer of clean topsoil. "We are using this method to determine what the complete exclusion of roots from contaminated sediment will do in terms of cesium uptake," he said.
Biobarrier contains pellets of a specific herbicide embedded in a special, nonwoven fabric. The herbicide stops cell division in root tips up to two inches away, Adriano said.
Other factors, such as the amount of oxygen in the soil and the type of soil, also affect the movement and availability of radioisotopes through the soil, said Dr. Sue Clark, a research chemist.
"Exposure to oxygen can cause them to leach slower or faster," she said. "And that's the last thing you want them to do because leaching makes these isotopes more available to be transported and may even make them more available for uptake by plants or animals."
In the case of some contaminated areas, Whicker said he believes the environment may be best served by "locking" contaminants in place.
Par Pond -- a contaminated reservoir at the Savannah River Site which has been lowered because of a faulty dam-- currently is being assessed for several potential remediation strategies. Whicker expressed concern that certain methods could cause more damage and disruption than just rebuilding the dam, filling the pond again and waiting a century for cesium in the bottom to decay.
"Environmentally speaking, it would be pretty devastating to [remediate the soil around Par Pond]," Whicker said. "Bulldozers would cause even more dramatic environmental impacts, and it would never be anything like what it was originally."
And that kind of solution doesn't come cheap. To remediate the sediment could be very expensive; Whicker isn't convinced that such extensive remediation is even necessary or desirable.
"But the Environmental Protection Agency probably is not going to let the Energy Department walk away and say, 'We're not going to do anything out there,'" Whicker said. "We think that the EPA is going to force them to clean up or to refill it. It's possible that extensive soil remediations could be ordered.
"I think they ought to refill the thing as quickly as possible, but I'm one opinion of many," he said.