SLAVUTYCH, UKRAINE—Very few people understand the radioactive afterglow of Chernobyl as well as Canadian scientist Tim Mousseau, who has dedicated 15 years to unravelling the ecological and evolutionary consequences of the world’s worst nuclear catastrophe.

But for all the impacts he has seen in his more than 30 field trips to Ukraine since 1991, none was so eerie as his close-up encounter with the ghost forest of dead trees that lingers to this day inside the radioactive no-go zone north of Kyiv.

“We were trudging through the Red Forest, the area most heavily contaminated. And we noticed that many of these trees — trees that were killed in the initial blast in 1986 — were sitting there relatively intact,” says Mousseau.

“You squeezed them and they were hard. Trees that died that many years ago, they should be mostly sawdust. They shouldn’t exist. But they do.”

Something else struck him as strange — the leaf litter underfoot was thick. As much as three times thicker than in less-contaminated areas of Chernobyl’s 2,500-square-kilometre exclusion zone. “It was like walking on mattresses,” he says.

Mousseau and his team already had their hands full researching the fallout on birds, insects and people inhabiting the region.

But faced with anecdotal evidence of an abrupt halt in the natural cycle of decomposition — no ashes to ashes, dust to dust, no microbial breakdown, just organic material frozen in time — the zombie trees and piling leaves demanded serious scrutiny.

Seven years ago, the nature-testing work began. And only now do we have answers. The peer-reviewed findings, published in the science journal Oecologia in March, confirm a microbial dead zone at Chernobyl’s ground zero.

It took nearly 600 bags of test material — carefully placed bundles of leaves from the same species of Scotch pine, birch, maple and oak that grew majestically in the forest immediately downwind from the meltdown at reactor No. 4.

The test bags were spread far and wide to vary the radioactive dose. Some were wrapped in mesh, enabling insects to join the feast; others in pantyhose to measure breakdown by microbes and fungi alone.

After the first year, the leaves in areas with no radiation were 70 to 90 per cent gone. Those nearest the hot zone were still about 60 per cent intact by weight. Moreover, microbes and fungi appeared to make the difference. They, and not insects, played the bigger role in breaking down the leaves and returning nutrients to the soil — and radiation, the study shows, is interrupting the process.

“We were just overwhelmed by the magnitude of the (radiation) effect,” Mousseau said.

“We’re trained to be skeptics and so when you walk through these areas, in the back of your mind you tend to doubt what appears to be obvious but may or may not be the reality. And so we were very surprised at how strong a signal came through.

“When we did the analysis we said, ‘Oh my God. This is huge.’”

It might surprise some to know that the ghost trees of Chernobyl sat intact for 28 years without once falling under the gaze of science until Mousseau and his team came along.

But it is far less surprising as you travel the region, which remains a dead zone of another sort, its human periphery imprisoned still by the memories of April and May 1986.

Those memories are most acute in Slavutych, the city of radiation refugees built rapidly in the waning years of the Soviet era, 50 kilometres east of the meltdown. Launched with what was then modern highrise architecture and expansive parklands, Slavutych was held up as a model of resilience.

But when the last working reactor at Chernobyl was shut down in 2001, most of the jobs went with it. Today about a third of the former workforce — some 3,000 people — remain employed at the site, tasked with maintenance, monitoring and helping construct a replacement “sarcophagus” to re-enclose the still-vulnerable core of Reactor No. 4 for the next 100 years. The city of Slavutych, where most of them live, looks tired and shopworn. Sad, like its residents.

“There was nowhere else to work then and nowhere else to work now,” said Volodymry Kyrpel, 56, who received a “lifetime dose” of radiation as part of the cleanup team in 1986. He left for 10 years but later retrained and works today as an off-site health and safety instructor for the next-generation crews who venture inside the exclusion zone.

Kyrpel and others in the replacement town still consider themselves “deportees” of Pripyat, the city of 50,000 nearest the power plant that was evacuated on orders from the Kremlin the morning after Chernobyl blew.

“Everyone was told they could go home in three days. All they took were their personal papers. And then we learned we were homeless. We could never go back,” said Kyrpel. “We are emotional to this day. There are very hard feelings.”

News of Mousseau’s findings in the Red Forest had yet to reach Slavutych. But a group of three young Chernobyl workers expressed no surprise when apprised of the research showing a microbial dead zone.

“I have seen the heavy buildup of leaves in some of the places where people fish on the edge of the Chernobyl zone,” said Yuri, 31, who spoke on condition his last name not be published.

“It’s not normal. But nothing in our lives is normal. Everyone was bombarded with Soviet propaganda after the accident. We were moved here, Pripyat was left in the shadows. And even to this day nobody really understands what happened or how many of us it damaged.”

Yuri was a toddler of 3 when the evacuation was ordered. Now he’s a second-generation Chernobyl worker, following in the footsteps of his mother and father. His dad died of cancer five years ago, a fact he attributes to the meltdown. But the death toll is even now fiercely debated — some UN-sanctioned estimates place the figure at 5,000, others far higher — and unlikely, given the political crisis currently gripping Ukraine, to ever be reconciled.

Yuri proudly proclaims he has a son, now 6, who “has been analyzed by doctors and has no problems.” His friends, Dima, 28, and Yevgeni, 26, also work on-site. Both tell of thyroid cancer deaths in their immediate family.

Some Ukrainian social scientists have described a sustained depression among Chernobyl survivors, many of whom blame a wild variety of illnesses on the ruined reactor.

“But there is also disdain,” said sociologist Mychailo Wynnyckyj of the National University of Kyiv-Mohla Academy. “The last reliable survey of Ukrainian attitudes shows that everybody hates Chernobyl, for understandable reasons. We all love Crimea, on the other hand. But Chernobyl holds a singular, negative place in Ukrainian minds.”

Or, as Yevgeni explains: “When we tell Ukrainians we are from Chernobyl they pull away. It’s like they are expecting us to glow in the dark. Meanwhile, we have a war here, competing for the jobs inside. There are 10 of us for every position. Not because we want to be there. Because it is the only place for work.”

Nearer the exclusion zone, in the tiny hamlet of Papirna, a cluster of small-hold farmers like Valia Panchoshna, 41, continue to eke out a living as their parents did.

Panchoshna, a mother of two, remembers her sudden evacuation at age 12. “All of us children were placed on buses and taken to live in a school far away, separated from our parents. We didn’t know what was happening.

“Then, after a month, our parents got angry and came to get some of us. I was home again. But the Soviet authorities insisted and removed all of the children a second time, for another three months, because the radiation was too dangerous,” she said.

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“If people got sick within five years, the family was compensated. My grandfather died of cancer after six years. My father died of cancer after eight years. My mother died of cancer after 20 years. No compensation. But I’m still alive. Maybe going on the bus made the difference.”

In the nearby village of Nedanchychi — barely one kilometre from the border with Belarus, which suffered its own severe downwind impacts in 1986 — Alexei Doberjanski offers an almost gleeful counterpoint.

Welcoming a reporter into his compound, the 62-year-old Chernobyl retiree proudly displays the spoils of a site manager’s income — a tidy, handsome home, two-car garage, fishing boat, motorcycle and his own private banya, a pine-encased sauna complex the size of a small cottage.

“Chernobyl,” he says, beaming, “brought me all of this. I was recruited after the disaster to lead the water circulation maintenance team. It was dangerous but we were able to survive and prosper. We timed our exposure to radiation. Some got sick, but I made it to retirement. There are many parts of the zone still very dangerous. But here on the edge, where we stand, the background radiation is only two times normal. It is safe.”

Doberjanski has seen the Red Forest and nods knowingly about the Mousseau team’s findings. “We know those trees. But it was always something to avoid because the radioactivity has penetrated deep inside the wood. People were very afraid of rain, very afraid the contamination would wash into the watershed.”

Mousseau, raised in Canada as an “army brat — Toronto, Ottawa, Montreal, Winnipeg, but Vancouver Island feels most like home because his parents live in Courtenay, B.C. — earned his doctorate at McGill before heading south for post-doctoral studies at the University of California, Davis. He stayed in the U.S., “because I couldn’t find a job in Canada” and made an academic home at the University of South Carolina.

His almost singular focus on Chernobyl has yielded a serious and steady body of work, including dramatic findings on the varying impacts on many species of plants and animals involving both direct toxicity and consequences of mutation for reproduction.

But tallying the direct impact on humans at Chernobyl, he says, is largely a lost cause. So he and his team have added Japan’s Fukushima disaster to their area of study, to broaden their understanding.

“The problem with Chernobyl is that it happened so long ago that establishing the extent of a person’s exposure tends to be based on human memory and human memory is faulty. So the data is poor, in my view. You see for yourself the unique circumstances of working in Ukraine. It’s a difficult place to get anything done at the best of times. And these are not good times.

“With Fukushima, we have a much better chance of getting dynamic information we can rely upon, in terms of tracking human impacts.”

But the scientist is far from finished with Chernobyl, where the allure of scientific discovery remains powerful. Just last week, his team published new data showing that some species of birds at Chernobyl are “doing reasonably well” by marshalling antioxidants to defend against radiation.

“We figured out how they allocate antioxidants — and the birds that managed to do it actually show reduced levels of genetic damage,” he said.

Those findings — great news, on the face of it — come in stark contrast to the Mousseau team’s eerie ghost forest findings. What do those mean, when the cycle of life — and death — stops cold?

Mousseau and colleagues hesitate to draw sweeping conclusions. They have established what is happening, but the hows and whys remain unknown.

But taken together with the team’s extensive findings on direct impacts and genetic damage to animal, plant and insect populations at Chernobyl, the absence of microbial breakdown adds yet another disturbing dimension to a disaster whose true magnitude is still being measured.

It also has the team fretting about how much more radiation they should subject themselves to in service of science.

Mousseau and his teammates are careful to monitor their cumulative exposure. But at the same time, they place little faith in the widely accepted lifetime threshold of 100 millisieverts (mSv) as a safeguard against increased risk of cancer.

“The truth is that’s a completely arbitrary limit. Certainly the probability of disease increases as the exposure goes up. But, you know, lots of people see consequences to the exposure at much lower levels and many people see none,” said Mousseau.

“It’s kind of equivalent to smoking. You hear about your grandma, ‘Drunk a bottle of rye and smoked a pack of cigarettes a day till she died at 99.’ There’s that kind of variability.

“But we’re certainly worried about it — and more now than we used to be. When we first starting going to Chernobyl the prevailing dogma was, ‘This is a low-dose scenario and the plants and animals are thriving and really this wasn’t dangerous.’

“And then we started finding all these consequences for the birds. And then later, the same consequences in rodents — mice and voles. And we’re finding the same things we found in the birds — increased cataracts, smaller brains, genetic damage. So yes, we worry about it more now.”

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