Investigation of contamination in spinach collected immediately following the Fukushima Daiichi nuclear disaster

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  The contamination of spinach collected immediately following the Fukushima Daiichi nuclear disaster was investigated. The radionuclides deposited in the spinach were ¹³²Te, ¹³¹I, ¹³²I, ¹³⁴Cs, ¹³⁶Cs and ¹³⁷Cs. Only 40% of these radionuclides were removed when the spinach was washed with water or detergent. The two outside leaves of each spinach stump were contaminated with the radionuclides, but the three inside leaves were nearly uncontaminated. The most significant contamination was observed on the concavities, creases, veins and leaf or stem injuries of the spinach. Most of the radionuclides deposited on the surface, leading to a radioactivity concentration of the epidermal tissue 9 times that of the mesophyll tissue.