A team of researchers based at Osaka University's Research Center for Nuclear Physics is investigating the long-term effects of 2011's Fukushima Daiichi Nuclear Power Plant accident. By measuring the radioactivities absorbed into the trees in the mountains, the team hope to measure the environmental circulation of fall-out radioactivity. A team of researchers from Osaka University have embarked on a series of research projects that are concerned with trying to quantify the radioactive fallout and how it circulates within the environment. One of their projects has sought to provide a map of the fallout radioactivities from the F1-NPP disaster. 'Our group, together with many scientists in Japan, measured the fallout radioactivities in the wide area in the Fukushima prefecture covering about 80 km circle area from the F1-NPP, and made a detailed map of these fallout radioactivities,' explains Fujiwara. 'We discovered that the radioactivities fell widely around the city area and across the mountain site.' The team knew that the radioactivities from the F1-NPP were mainly 134CS and 137CS, which are both radioactive isotopes of Cesium. Cesium is an alkali material, like Lithium, Sodium and Potassium, which means it easily combines with organic matter and with soil. 'Thus, when the cesium fell down onto the leaves of evergreen trees on the mountains around F1-NPP, it became trapped on the leaves,' observes Fujiwara. To make matters worse, because of afforestation projects, almost 50 per cent of trees on mountains in Japan consist of Japanese cypress and cedar, which have a leaf fall cycle of between four and five years. One of their achievements has been to produce a 'soil map' of the area surrounding the site of the F1-NPP disaster. In a study entitled 'Detailed deposition density maps constructed by large-scale soil sampling for gamma-ray emitting radioactive nuclides', his colleagues decided to embark on comprehensive large-scale monitoring of the contaminated areas. 'The chief aim of this specific investigation was to produce precise distribution maps of dominant gamma-ray emitting radioactive nuclides that had been deposited on the ground,' says Fujiwara. It will likely take a significant amount of time before the exact impacts from the Fukushima accident are quantified and, even then, the long-term effects on the public and their exposure to radiation will still be difficult to measure. However, it is vital that teams such as that based at Osaka University perform the investigations they do. The findings are often far from desirable and one only has to look at what happened at Chernobyl to understand the potential ramifications of radioactivity to individuals and the environment.