Radioactive Cs transfer to vegetables after the FDNPP accident

To evaluate the effectiveness of potassium (K) application in mitigating¹³⁷Cs transfer from soil to plants, several vegetable species were cultivated under field and pot experiments. In the field experiment, squash, sweet potato, turnip, potato, and carrot were examined in 2020 and 2021 in two different areas of Hamadori (coastal region in Fukushima Prefecture). Transfer factor (TF) was calculated by dividing harvest radioactivity (Bq kg⁻¹ dry or fresh) to soil radioactivity (Bq kg⁻¹ dry) and was negatively correlated with the amount of exchangeable K (ExK) at harvest, regardless of the species, year, and location. In the pot experiment, edamame (immature soybean seed), spinach, turnip, and komatsuna were cultivated, and it was confirmed that ExK was the most powerful factor in regulating TF. Based on the relationship between ExK and TF for each vegetable species, the amount of ExK required to keep the ¹³⁷Cs concentration lower than a certain level (standard limitation value and one-quarter of that value) was calculated.