title: Effective and ecological half-lives of90Sr and137Cs observed in wheat and rice in Japan.
abstract: Published pre-Fukushima food monitoring data from 1963 to 1995 were used to study the long-term presence of137Cs and90Sr in rice and wheat. Effective half-lives (Teff) were calculated for rice (137Cs: 5.6 years;90Sr: 6.7 years) and wheat (137Cs: 3.5 years;90Sr: 6.2 years), respectively. In rice,137Cs exhibits a longerTeffbecause putrefaction processes will lead to the formation of NH4+ions that are efficient ion exchangers for mineral-adsorbed cesium ions, hence making it more readily available to the plant. Knowledge on the long-term behavior of radiocesium and radiostrontium will be important for Japanese food-safety campaigns after the Fukushima nuclear accident.
authors.affiliation: Vienna University of Technology, Atominstitut, Stadionallee 2, 1020 Vienna, Austria.
authors.forename: Stefan
authors.initials: S
authors.lastname: Merz
authors.affiliation: Graduate School of Arts and Sciences, The University of Tokyo, Meguro-ku, Tokyo, Japan.
authors.forename: Katsumi
authors.initials: K
authors.lastname: Shozugawa
authors.affiliation: Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO 80523 USA ; Institute of Environmental Radioactivity, Fukushima University, Fukushima, 960-1296 Japan ; Leibniz Universität Hannover, Institut für Radioökologie und Strahlenschutz, 30419 Hannover, Germany.
authors.forename: Georg
authors.initials: G
authors.lastname: Steinhauser
keywords: 137Cs; 90Sr; Ecological half-life; Effective half-life; Food safety; Foodstuff; Fukushima