Data from: Fire evolution in the radioactive forests of Ukraine and Belarus: future risks for the population and the environment

This paper analyzes the current and future status of forests in Ukraine and Belarus that were contaminated after the nuclear disaster in 1986. Using several models, together with remote sensing data and observations, we studied how climate change in these forests may affect fire regimes. We investigated the possibility of 137Cs displacement over Europe by studying previous fire events, and examined three fire scenarios that depended on different emission altitudes of 137Cs, assuming that 10% of the forests were affected by fires. Field measurements and modeling simulations confirmed that numerous radioactive contaminants are still present at these sites in extremely large quantities. Forests in Eastern Europe are characterized by large, highly fire-prone patches that are conducive to the development of extreme crown fires. Since 1986, there has been a positive correlation between extreme fire events and drought in the two contaminated regions. Litter carbon storage in the area has doubled since 1986 due to increased tree mortality and decreased decomposition rates; dead trees and accumulating litter in turn can provide fuel for wildfires that pose a high risk of redistributing radioactivity in future years. Intense fires in 2002, 2008 and 2010 resulted in the displacement of 137Cs to the south; the cumulative amount of 137Cs re-deposited over Europe was equivalent to 8% of that deposited following the initial Chernobyl disaster. However, a large amount of 137Cs still remains in these forests, which could be remobilized along with a large number of other dangerous, long-lived, refractory radionuclides. We predict that an expanding flammable area associated with climate change will lead to a high risk of radioactive contamination with characteristic fire peaks in the future. Current fire-fighting infrastructure in the region is inadequate due to understaffing and lack of funding. Our data yield the first cogent predictions for future fire incidents and provide scientific insights that could inform and spur evidence-based policy decisions concerning highly contaminated regions around the world, such as those of Chernobyl.

本研究分析了1986年切尔诺贝利（Chernobyl）核灾难后受污染的乌克兰与白俄罗斯森林的当前及未来态势。研究团队借助多模型、遥感数据与实地观测资料，探究了上述林区的气候变化对火灾制度的潜在影响。通过剖析既往火灾事件，我们研究了铯-137（137Cs）在欧洲范围内迁移的可能性，并基于铯-137的三种不同排放高度设定了火灾情景，同时假设10%的林区受到火灾影响。实地测量与模型模拟结果证实，该区域目前仍留存有数量极其庞大的各类放射性污染物。东欧林区以连片且高火险的斑块为典型特征，这类斑块极易催生极端冠层火灾。自1986年以来，这两个受污染区域的极端火灾事件与干旱之间始终呈现显著正相关关系。受树木死亡率上升与分解速率降低的影响，该区域的枯落物碳储量自1986年以来已翻倍；枯死林木与持续堆积的枯落物反过来为野火提供了充足燃料，进而在未来年份带来放射性物质重新扩散的高风险。2002年、2008年及2010年发生的高强度火灾导致铯-137向南迁移；在欧洲范围内重新沉积的铯-137累计总量相当于切尔诺贝利核灾难初始沉降量的8%。然而，大量铯-137仍留存于这些林区中，其可与诸多其他危险的长寿命难溶性放射性核素一同被重新活化。我们预测，伴随气候变化而来的易燃区域扩张，将在未来引发放射性污染的高风险，并伴随典型的火灾峰值。该区域当前的消防基础设施因人员短缺与资金匮乏而难以满足实际需求。本研究数据首次针对未来火灾事件提出了具有说服力的预测，并提供了科学见解，可为全球范围内高污染区域（如切尔诺贝利周边区域）的循证政策制定提供参考与推动。