Japan, however, is not yet resigned to either permanently banning residents or exposing them to drastically elevated levels of radiation as a consequence of its own nuclear disaster. Instead, it is attempting to carve a third path forward.Immediately following the meltdown at the Fukushima plant in March 2011, the Japanese government did evacuate nearby residents. The evacuated area was smaller than that around Chernobyl but far more densely populated, encompassing coastline, farms, and forests in 11 municipalities. At least 157,000 people were either ordered to leave this zone or voluntarily left their homes in other parts of Fukushima. But by the summer of 2011, the central government had already launched a recovery plan aimed at getting them back.The strategy centered on extensive decontamination. Isotopes of cesium and other radionuclides were to be removed by early 2014 from houses, roads, farms, public buildings, and wooded areas within 20 m of living areas in all but the most heavily contaminated parts of the exclusion zone (defined as those where the air dose rates for residents could exceed 50 mSv/yr). The government determined that in the long term this meant getting air dose rates from Fukushima fallout below 1 mSv/yr, although specific targets for 2014 were much more modest. Some of that reduction would happen through natural decay; Fukushima has a higher ratio of short-lived cesium-134 than areas surrounding Chernobyl. The rest required hands-on work.The Japanese Ministry of Environment was put in charge of the project, which has a budget of more than US$6 billion for 2013 alone. Inside the exclusion zone, the central government was directly responsible for overseeing the work; beyond it, local governments managed the process. Soon contractors and ordinary citizens were hosing down, wiping off, and vacuuming up invisible particles from the surfaces of houses, roads, and schools throughout eastern and central Fukushima, while backhoes scraped soil from fields and stripped grass from parks. In woodlands near houses, the people raked up leaves and removed lower branches from trees.Clockwise from top left: Bags of contaminated soil from Iitate; a tower for monitoring movement of radionuclides in Kawamata; forestry and construction workers join in forest decontamination training at Forest Park Adatara, Otama; trial decontamination behind a home in Kawauchi.All images: Winifred A. BirdThe work continues with mixed success. Radioactive cesium can in some cases be washed or wiped off smooth surfaces like tile, but it easily becomes stuck in the crevices of uneven materials and binds strongly to clay. Decontaminating large areas covered in vegetation, such as parks and gardens, usually means removing and disposing of whatever the cesium is stuck to. Grass and weeds, for instance, are cut, not washed, and dirt is usually removed or deep-plowed, according to Kathryn Higley, head of the Department of Nuclear Engineering and Radiation Health Physics at Oregon State University. The process is labor-intensive, expensive, and prone to corner-cutting. To make matters worse, rain, wind, animals, and people can move irradiated debris around, recontaminating areas that have already been treated. As the cleanup proceeded, many Fukushima residents interviewed for this story say they began to suspect that forested slopes were a key source of recontamination—although research has not yet proved this.For over a year, however, the government remained silent about what should be done in the mixed deciduous forests and evergreen timber plantations that cover the majority of the prefecture near the plant. Finally, in early July 2012, the Ministry of Environment established a committee to discuss forest management. By the end of the month the group had prepared its initial recommendations. These proposals will influence final guidelines that determine what happens to forests inside the exclusion zone, where the ministry is directly responsible for cleanup, and define what actions are eligible for subsidies outside the exclusion zone. (As of February 2013 these final guidelines still had not been issued.) The committee concluded there is little need to decontaminate entire forests. It went on to note that removing litter from broad swaths of forest could lead to erosion and undermine tree health, while thinning out trees is unnecessary because it would likely reduce air dose rates only slightly.The committee based these recommendations on a handful of Japanese government–sponsored studies that indicated only a small percentage of the radionuclides currently in forests is likely to migrate out via water or air. It also referenced an October 2011 report by an International Atomic Energy Association (IAEA) mission to Fukushima cautioning that overly aggressive decontamination could be extremely costly and generate huge amounts of waste without significantly reducing exposure. The IAEA report recommended that Japan instead restrict forest and forest product use. It has done so in the case of mushrooms, wild game, and vegetables; soil amendments and sawdust substrate for mushroom cultivation; and firewood and charcoal—although, notably, not in the case of timber. Japan’s own guidelines for dealing with the contamination called for prioritizing cleanup in places that would most impact human health. It was in this context that the ministry committee declared extensive forest decontamination unnecessary.The backlash from Fukushima was immediate and harsh. One after another, local and prefectural officials and forestry industry representatives attacked the proposal as a city-centric, top-down decision that ignored the deep connections between rural residents and their forested environment as well as the differences between Fukushima and Chernobyl—in northeast Japan, the topography is steep and complex rather than flat; rain is abundant; and forests are closely entwined with densely populated farmland. Although forests have contained the bulk of the contamination around Chernobyl, many doubted they could—or should—play the same role around Fukushima.Kazuhiro Yoshida, chairman of the Namie town assembly, was among those who traveled to Tokyo to hand-deliver a petition to then–Environment Minister Goshi Hosono calling for extensive forest cleanup. Namie, which is largely forested, lies just northwest of the devastated plant, inside the exclusion zone, and includes some of Japan’s most heavily contaminated land.“Country life is appealing because we can drink good water and eat wild foods from the mountains. If you put limits on that, you’re not living; you’re surviving,” Yoshida says. He opposes the concept of simply limiting access to contaminated forests. He also fears that contaminant-laden dirt will flow from wooded hillsides into Namie’s rice paddies and reservoirs. Residents won’t be safe unless something is done to reduce the amount of radionuclides in forested areas as well as on farm fields and homes, Yoshida says.Soil profiles show that within five months after the disaster, between 44% and 84% of radioactive cesium in forest environments was already on the forest floor, most in the litter and top 5 cm of soil. Anything that causes soil to erode—road building, heavy rains, even decontamination work itself—could carry those contaminants down to the valley floors where human life is centered. Government research has suggested that forests are providing only a small fraction of the radionuclides that are showing up—sometimes at high concentrations—on the bottoms of lakes, in the bodies of river fish, and in rice fields fed by springs in wooded hills.,43 In one of the few peer-reviewed studies of this issue to be published so far, investigators compared levels of radiocesium in the water of two small Fukushima rivers to the total estimated radiocesium in the rivers’ watersheds. The authors estimated that during 2011 0.5% of contaminants in one watershed and 0.3% in the other flowed into these rivers, with movement occurring during precipitation and flooding.Scientists at Japan’s government-funded Forestry and Forest Products Research Institute say they plan to study those long-term patterns. In general, though, Japan has high forest cover and comparatively low erosion rates, says Shinji Kaneko, a soil scientist at the organization, which is closely associated with the Forestry Agency and has become a major research center for irradiated forests. In the long term, the clay soils common in eastern Fukushima may trap more radioactive cesium than the sandy and peat soils around Chernobyl. Kaneko predicts this will lower the rate of transfer to groundwater and wild plants.Such predictions do not reassure many who live near contaminated forests or are engaged in managing them. Shigeru Watanabe, a prefectural official who oversees forest maintenance in Fukushima, believes that if forests are left alone “people won’t feel safe living in these areas.” He says the prefecture is pushing strongly for extensive decontamination.Removing litter, branches, or whole trees, however, generates huge quantities of low-level radioactive waste. Fukushima is already struggling to handle millions of cubic meters of contaminated debris from the cleanup. Stripping the top 5 cm of soil and everything above—litter, fallen branches, trees, and brush—from just the most heavily contaminated forests would yield another 21 billion kg of debris, according to a study by Forestry and Forest Products Research Institute scientists. The authors argue that removing just litter is the most efficient approach to decontamination, although it must be done before radioactive particles migrate further into the soil. Litter made up just 3% by weight of the forest components in each sample plot the team analyzed, but as of summer 2011 it contained 22–66% of the radioactive particles in the sample plots.Prefectural officials want more to be done. A survey by Japan’s Forestry Agency showed that radioactive cesium was split roughly in half between soil and leaf litter on the one hand, and leaves, trunks, and branches on the other. (In deciduous forests still leafless when the meltdowns occurred, the balance was tilted heavily toward the forest floor.) Watanabe says separate trials conducted by Fukushima Prefecture, which are not publicly available, showed that thinning one-third of the trees reduced radiation by up to 23%, and adding in reductions from removing litter “gets you to about half.” The prefecture plans to begin thinning trees in privately owned forests in 2013 using central government funding, according to Forest Management Department official Norio Ueno.But the Forestry Agency has found thinning to be about half as effective as the unpublished prefectural trials Watanabe cites. As time passes, tree removal will likely become even less effective: In Chernobyl, the above-soil portion of trees now holds less than 20% of total forest contaminants, and that percentage is decreasing steadily.Many of the Fukushima residents interviewed for this article doubt forest decontamination will work; some see the enterprise as a public-relations stunt. Extensive decontamination will, indeed, likely be hard to achieve. Others in Fukushima suggest that the immense sums being funneled to construction companies managing the cleanup would be better spent on permanently relocating people, including those who live outside the exclusion zone but no longer feel safe in their contaminated neighborhoods. In August 2012 the Ministry of Environment responded to pressure from Fukushima by announcing it would rethink its proposed forest policy. Two months later it announced plans for a working group to consider thinning and clearcutting.
Two Approaches
Proponents of extensive decontamination see many benefits beyond public safety, according to Ueno: more productive timber plantations (thousands of hectares were in desperate need of thinning even before the disaster), jobs, and, if debris can be burned in biomass power plants, a sustainable energy source. One town actively looking into biomass power generation is Kawauchi, a village deep in the mountains west of the Fukushima Daiichi Nuclear Power Plant. The population of 3,000 has dwindled to 750 since the disaster, according to Kawauchi city hall employee Morie Sanpei. Sanpei, who is in charge of researching the biomass plant, says the town hopes to thin out 50–70% of the trees in the lush forests that loom over small clusters of homes and burn them in a proposed 5,000-kw power plant. In February 2013 Fukushima’s prefectural government also announced plans to build a 12,000-kw biomass power plant that will burn wood from trees thinned in the prefecture’s proposed forest decontamination program.The Ministry of Environment claims standard filters can keep between 99.44% and 99.99% of radioactive cesium from leaving smokestacks. These figures are supported by trials at a biomass incinerator in Belarus, conducted as part of the Chernobyl Bio-energy Project, a multiyear international initiative aimed at forest remediation. The researchers involved with that project concluded the health risk from the smoke is “so low that it does not constitute a problem.”They also predicted workers in a biomass plant would receive very little exposure from wood or ash, provided the plant was well designed and work practices well planned.But Kyoto University nuclear engineer and antinuclear activist Hiroaki Koide believes a proliferation of small biomass plants in Fukushima would be risky; if local officials who lack specialized knowledge are pushed to economize, they might cut corners on critical safety precautions. Indeed, Sanpei notes that cost is a major consideration for Kawauchi. He says that while highly mechanized processing lines reduce plant worker exposure to contaminated materials, they also raise construction costs—possibly beyond what the town can afford.Using incinerators as a tool to concentrate and contain the Fukushima fallout has the apparent advantage of moving radionuclides out of neighborhoods. But Chernobyl scientists warn that uncontrolled burning of irradiated wood can do the opposite—spread contaminants far beyond their current location. As time progresses in the Chernobyl Exclusion Zone, the natural way trees and other groundcover are trapping radionuclides has developed an ominous downside. The stands that now grow on approximately 1,800 km2 are largely unmanaged, according to Zibtsev, the forestry professor. Nikolay Ossienko, part of a forest and fire crew working in the exclusion zone, says he and his coworkers can remove only a few of the dead and dying trees, accomplishing a bare minimum of the thinning required to reduce fire danger and maintain roads for fire vehicle access.As trees mature and die and more sunlight penetrates the canopy, brush and other undergrowth species are starting to grow in the spaces. The Chernobyl forests are thus developing “fuel ladders” of vegetation that would enable a fire to climb into the tree canopy and jump from treetop to treetop in what’s known as a crown fire. Without effective forest management, and combined with a general drying trend he attributes to climate change, Zibtsev believes Chernobyl could experience catastrophic fires rivaling those that are being seen with increased frequency in the western United States. In a low-key conclusion to a 2009 study of vegetation fires in the exclusion zone, Wei Min Hao, an atmospheric chemist with the U.S. Forest Service, and fellow authors said conditions there are “favorable for catastrophic fires.”The critical difference between those U.S. fires and the potential fires in Chernobyl is that these forests are laden with radionuclides. When they burn, they emit radioactive cesium, strontium, and plutonium in respirable fine particles, Zibtsev says. Scientists at the Ukrainian Institute of Agricultural Radiology conducted an experimental surface burn on 9,000 m2 near the power plant to assess the behavior of the plume and the concentration of radionuclides released in the smoke. The low-intensity ground fire blazed for around 90 minutes, releasing as much as 4% of the cesium-137 and strontium-90 in the aboveground biomass, says Yoschenko. A high-intensity crown fire would release much higher amounts from burning needles, he says. Separate studies have predicted that crown fires in Chernobyl could transport these emissions “hundreds to thousands of kilometers” to human population centers and, in a worst-case scenario, trigger ongoing government restrictions on contaminated milk, meat, and vegetables.This is the Chernobyl paradox. “Forests are our friend in health, our enemy when they burn,” says Zibtsev.Tatsuhiro Ohkubo, a professor of forest ecology at Utsunomiya University, says the risk of forest fires in Japan, especially catastrophic ones, is relatively low compared with Ukraine and limited to a short dry season in spring. Nevertheless, these data present yet another dilemma for Japanese officials and forest residents.As the sites of the world’s worst nuclear power plant accidents, Japan and Ukraine share the challenge of protecting their citizens even as they hope to return residents to the rural communities where forests sheltered them and provided clean water, food, firewood, and livelihoods. Whether Japan opts for the Chernobyl model, leaving forests to their slow but natural recovery, or chooses to decontaminate them, local residents will inevitably pay a price.Mizue Nakano, a mother of two who lives in Fukushima City, has seen her teenaged daughters’ health decline. Worried about their exhaustion, bloody noses, and diarrhea, she sent her younger daughter to live with a relative six hours away by car. While stress is a likely cause of these conditions, Nakano, who remained in Fukushima with her older daughter, is careful to limit her time outside. Bereft of the connection with the forests that surround her city, Nakano is profoundly saddened. “I can’t believe we’ll have to raise our children without taking them out into nature,” she says. Yet decontamination hardly offers a better option: “Even if it were possible to decontaminate the forests, I wouldn’t want to live in the sort of place you’d end up with.”
Authors: Vasyl I Yoschenko; Valery A Kashparov; Maxim D Melnychuk; Svjatoslav E Levchuk; Yulia O Bondar; Mykola Lazarev; Maria I Yoschenko; Eduardo B Farfán; G Timothy Jannik Journal: Health Phys Date: 2011-10 Impact factor: 1.316
Authors: Wei Min Hao; Stephen Baker; Emily Lincoln; Scott Hudson; Sang Don Lee; Paul Lemieux Journal: J Air Waste Manag Assoc Date: 2018-09-07 Impact factor: 2.235
Authors: Ali Khaji; Bagher Larijani; Seyed Mohammad Ghodsi; Mohammad A Mohagheghi; Hammid R Khankeh; Soheil Saadat; Seyed Mahmoud Tabatabaei; Davoud Khorasani-Zavareh Journal: Arch Bone Jt Surg Date: 2018-07