Fukushima nuclear accident environmental impacts

Seminar by Professor Yuichi Onda, University of Tsukuba
Fukushima Daini nuclear power plant
Fukushima Daini nuclear power plant. Credit: IAEA Imagebank, CC BY-SA 2.0, via Wikimedia Commons
This seminar was held at the Sustainability Hub on 6 February 2024.
Professor Yuichi Onda from the Center for Research in Radiation, Isotopes and Earth System Sciences, University of Tsukuba visited the University of Plymouth to give a seminar on the Fukushima nuclear accident environmental impacts.
Professor Onda led a major environmental monitoring research programme after the nuclear accident in 2011, studying fallout radionuclide distribution, behaviour and transfer in forests, soils, rivers and sediments across the region. 
The seminar discussed the crucial role and long-term impacts of government-led decontamination efforts in addressing radiation hazards and restoring soil contaminated with Cs-137 in Fukushima, utilising a unique combination of governmental data, advanced satellite imagery, and concurrent river monitoring. 
 

Fukushima Decontamination Affects Downstream Sediment and Cs-137 Discharge into the Ocean

Abstract
This study examines the crucial role and long-term impacts of government-led decontamination efforts in addressing radiation hazards and restoring soil contaminated with Cs-137 in Fukushima. Utilising a unique combination of governmental data, advanced satellite imagery, and concurrent river monitoring, we present the first thorough evaluation of decontamination impacts from 2013 to 2018. 
Our findings indicate a significant increase in soil erosion during the initial decontamination phase (2013–16), followed by a reduction in this trend as revegetation efforts took effect. This change in soil stability was mirrored by the dynamics of river suspended sediment (SS), which saw a notable increase of about 237% in the 2016 flood compared to 2013 levels. We observed a gradual rise in sediment contributions from areas undergoing decontamination, resulting in a marked decrease in Cs-137 particulate levels. Post-decontamination, both sediment yield and contributions from treated areas declined, due to rapid regrowth of vegetation. However, this did not significantly alter the normalised Cs-137 fluxes downstream. 
These findings shed light on the complex and potentially unsustainable downstream impacts of upstream decontamination efforts, underscoring the vital importance of vegetation restoration in mitigating these effects.

References

  • Onda, Y. et al. Radionuclides from the Fukushima Daiichi Nuclear Power Plant in terrestrial systems. Nat. Rev. Earth Environ. 1, 644–660 (2020). Free-to-Read
  • Feng, B., Onda, Y., Wakiyama, Y., Taniguchi, K., Hashimoto, A., Zhang, Y., Persistent impact of Fukushima decontamination on soil erosion and suspended sediment, Nature Sustainability, 5, 879-889  DOI: 10.1038/s41893-022-00924-6 (2022)
Professor Yuichi Onda