Radiocesium concentration in seeds of Japanese fir (Abies firma Sieb. et Zucc.) growing in Fukushima forests 4.5 years after the Fukushima Daiichi Nuclear Power Plant accident

ABSTRACT

Seed soundness is of paramount importance for all plants. Seed soundness of forest trees might have been negatively affected after the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident in March 2011, when a massive amount of artificial radionuclides deposited on forest areas. However, information on seeds of forest tree species contaminated with radionuclides is limited because they are rarely encountered in forest ecosystems. Japanese fir (Abies firma Sieb. et Zucc.) is a predominant tree in natural secondary forests in the Abukuma Mountains in Fukushima, and this species shows masting; cone production occurs every 2 or 3 years, meaning that the contamination levels of A. firma seeds remain unknown. We investigated the contamination levels of ¹³⁷Cs in cone components (seeds, wings and cone scales) of A. firma approximately 4.5 years after the FDNPP accident. The ¹³⁷Cs concentration in seeds showed the lowest contamination level of the three cone components. In addition, there was a difference in ¹³⁷Cs concentration between seeds and cone scales, suggesting a difference in ¹³⁷Cs contamination levels between strict seed feeders and seed-cone feeders. Our results indicate that the combination of observed low contamination levels of seeds of A. firma and expected small root uptake of ¹³⁷Cs from soil might lead to low contamination levels of ¹³⁷Cs in recruits of this species.

KEYWORDS:

• ¹³⁷Cs
• translocation
• evergreen conifer
• cones
• food web

Acknowledgements

We thank Prof. K. Shizuma at the Graduate School of Engineering, Hiroshima University for his support in sample measurements and data analysis. We thank the Iwaki District Forest Office for supporting our field survey. The present research was supported through the Hiroshima University Phoenix Leader Education Program for the “Renaissance from Radiation Disaster”, funded by the Ministry of Education, Culture, Sports, Science and Technology.

Disclosure statement

No potential conflict of interest was reported by the authors.

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Funding

The present research was supported through the Hiroshima University Phoenix Leader Education Program for the “Renaissance from Radiation Disaster”, funded by the Ministry of Education, Culture, Sports, Science and Technology.