- Significant deposition of radiocesium including 134Cs and 137Cs occurred in March 2011 following the Fukushima nuclear accident across vast regions of Northeastern Japan. However, as most studies focused on fallout that took place in the Fukushima Prefecture, much less information is available on the situation that prevails further to the North, in other parts of the Tohoku Region of Japan. In this context, the current research investigated the occurrence of fallout radionuclides (including natural 210Pbxs as well as artificial 134Cs and 137Cs) in burned and unburned soil profiles as well as in a range of surface soil and sediment samples collected in the region of Kamaishi (Iwate Prefecture, Tohoku Region, Japan) affected by wildfires in 2017. Results show that 210Pbxs and 137Cs may be used as tracers of sediment sources across landscapes affected by wildfires in this region. Furthermore, the soil profile analysis demonstrated that all analysed fallout radionuclides were foundSignificant deposition of radiocesium including 134Cs and 137Cs occurred in March 2011 following the Fukushima nuclear accident across vast regions of Northeastern Japan. However, as most studies focused on fallout that took place in the Fukushima Prefecture, much less information is available on the situation that prevails further to the North, in other parts of the Tohoku Region of Japan. In this context, the current research investigated the occurrence of fallout radionuclides (including natural 210Pbxs as well as artificial 134Cs and 137Cs) in burned and unburned soil profiles as well as in a range of surface soil and sediment samples collected in the region of Kamaishi (Iwate Prefecture, Tohoku Region, Japan) affected by wildfires in 2017. Results show that 210Pbxs and 137Cs may be used as tracers of sediment sources across landscapes affected by wildfires in this region. Furthermore, the soil profile analysis demonstrated that all analysed fallout radionuclides were found enriched in the burned vs. unburned profiles, due to the incorporation of radionuclides trapped by vegetation into the ash after the fire. The detection of 134Cs in the uppermost 0–5 cm depth layer in all investigated soil profiles also allowed to demonstrate the occurrence of significant Fukushima fallout of 134Cs and 137Cs in this region (roughly of the same order of magnitude as the fallout associated with the nuclear atmospheric tests in the 1960s). In the future, both sources of fallout should be considered to provide relevant interpretations when examining radionuclide data found in environmental samples collected in vast regions of Northeastern Japan. The analysis of 134Cs should also be encouraged to document the sources of fallout in these regions as long as this short-lived radionuclide remains detectable (i.e., theoretically by 2031).…
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