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Historical record of nuclear activities from 129I in corals from the northern hemisphere (Philippines).

Abstract：

:Iodine-129 is a long-lived fission product that is majorly released in human nuclear activities (HNA) such as nuclear bomb testing, nuclear fuel reprocessing, and nuclear accidents. It is a good environmental tracer and former measurements of 129I in corals from the southern hemisphere show the increasing trend of 129I concentrations in the marine environment caused by HNA. Here we show time series of 129I/127(stable)I isotopic ratios in two coral cores from the northern hemisphere (Philippines) and how these record 129I released from HNA in even greater, unprecedented detail. Corals were taken from the Pacific Ocean (Baler) and South China Sea (Parola) sides of the Philippines. We observed nearly identical peaks (129I/127I ∼ 31.5 × 10-12) in both the Baler and Parola records, each attributed to the year 1962 - the year with the highest recorded amount of 129I release from nuclear bomb testing. This 1962 129I bomb signal offers a new time marker that can be used to establish or confirm age models of corals, comparable to or possibly better than the well-known coral 14C bomb peak. We also observed nuclear fuel reprocessing and Chernobyl accident 129I signals in years 1977, 1980, and 1986, concurrently in Parola and with 9 to 11-year lags in Baler. This discrepancy in timing suggests that 129I was transported to the South China Sea and Pacific Ocean sides of the Philippines directly from the atmosphere and through prevailing ocean currents, respectively. Lastly, we observed surprisingly high 129I/127I isotopic ratios (i.e., 22.8 to 38.9 × 10-12) in the Parola record after the year 1996, which is in contrast to the decreasing trend observed in the Baler record and in published 129I releases of different HNA. These results possibly indicate the presence of unknown sources of 129I in the South China Sea region.

journal_name

J Environ Radioact

journal_title

Journal of environmental radioactivity

authors

Bautista AT Vii,Matsuzaki H,Siringan FP

doi

10.1016/j.jenvrad.2016.07.022

subject

Has Abstract

pub_date

2016-11-01 00:00:00

pages

174-181

eissn

0265-931X

issn

1879-1700

pii

S0265-931X(16)30252-1

journal_volume

164

pub_type

杂志文章

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Historical record of nuclear activities from 129I in corals from the northern hemisphere (Philippines).