Study on carbonized temperature estimation of charcoal remained in burnt area in Namie Town, Fukushima

Nomura, Naoki*; Arai, Hirotsugu*; Kuramoto, Takayuki*; Niizato, Tadafumi  ; Hayashi, Seiji*

In 2017, a wildfire occurred in mountainous forest of Namie Town, Fukushima Prefecture, where is designated as a difficult-to-return zone due to high radiation dose after TEPCO's Fukushima Daiichi Nuclear Power Plant accident. With the wildfire, changes of dynamics of radionuclide, especially Cs-137 was concerned. In this study, we focused residual charcoal to estimate burning temperature of surface soil and litter because it affects the dissolution behavior of nutrients and radiocesium in soil and litter on the forest floor of the burnt area. As a result of the wildfire, Japanese cedar forest and mixed forest with predominance of Japanese red pine and Japanese oak were burned, so we set up three control sites at each forest and collected the residual charcoals from burnt sites nearby unburnt locations. To clarify the carbonized temperature of residual charcoal, thermal analysis by TG-DTA and infrared adsorption spectrum analysis by micro-FTIR were conducted for litters, artificially burnt litters, and residual charcoals.