Presentation Distributions of 137Cs and 40K in fruit tissues of persimmon and loquat

Uchida, Shigeo  ,  Tagami, Keiko

Large amounts of radionuclides were discharged from Fukushima Daiichi Nuclear Power Plant (FDNPP) to the environment mainly in March and April 2011. Several months later, 134Cs (T1/2=2.06 y) and 137Cs (30.17 y) were the only major radioactive contaminants remained in the environment. Thus, removal of radiocesium from food by processing is of great concern following the accident. To provide radiocesium removal rates by peeling of fruits, we studied distributions of 137Cs and 40K in fruits of persimmon (Diospyros kaki) and loquat (Eriobotrya japonica) that are common as garden trees in Chiba Prefecture in Japan. Fruit samples were collected in 2011-2014 from the campus of the National Institute of Radiological Sciences in Chiba, Japan located about 220 km south of the FDNPP. The NIRS had received radioactive fallout deposited mainly as wet deposition and the inventory of 137Cs in this area was ca. 15 kBq m-2. Loquat fruits harvested in June every year; only the first year samples were directly contaminated with the radioactive fallout because their flowering time is generally in November. For persimmon fruits, they were harvested in September to October; their flowering time is generally in May so that there was no direct deposition on the fruits in the first year.After collection, a whole fruit was washed with running tap water and rinsed with RO water. Then the water was removed with paper towels from the fruits, and each tissue part (flesh, skin and seeds) was separated and weighed. Except for the loquat fruits collected in 2011, all the other tissue part samples were dried to a constant weight at 80˚C in an electric oven for at least 2 d. Each dried sample was pulverized, and then, the powder sample was transferred to a 100 mL polystyrene container. The 137Cs radioactivity was then determined with a germanium detecting system (Seiko EG&G). Distribution ratios of 137Cs, 40K and fruit wet weight were described as total content in each tissue part divided by total content.
13th International Conference on the Biogeochemistry of Trace Elements (ICOBTE 2015)

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