文摘
Aerosol samples were collected from Tsukuba, Japan, soon after the 2011 Fukushima nuclear accident and analyzed for speciation of radiocesium and radioiodine to explore their chemical behavior and isotopic ratios after the release. Most 134Cs and 137Cs were bound in organic matter (53鈥?1%) and some in water-soluble fractions (5鈥?5%), whereas a negligible proportion of radiocesium remained in minerals. This pattern suggests that sulfate salts and organic matter may be the main carrier of Cs-bearing particles. The 129I in aerosol samples is contained in various proportions as soluble inorganic iodine (I鈥?/sup> and IO3鈥?/sup>), soluble organic iodine, and unextractable iodine. The measured mean 129I/131I atomic ratio of 16.0 卤 2.2 is in good agreement with that measured from rainwater and consistent with ratios measured in surface soil samples. Together with other aerosols and seawater samples, an initial 129I/137Cs activity ratio of 鈭? 脳 10鈥? was obtained. In contrast to the effectively constant 134Cs/137Cs activity ratios (1.04 卤 0.04) and 129I/131I atomic ratios (16.0 卤 2.2), the 129I/137Cs activity ratios scattered from 3.5 脳 10鈥? to 5 脳 10鈥? and showed temporally and spatially different dispersion and deposition patterns between radiocesium and radioiodine. These findings confirm that 129I, instead of 137Cs, should be considered as a proxy for 131I reconstruction.
