Reconstruction of the temporal distribution of ²³⁶U/ ²³⁸U in the Northwest Pacific Ocean using a coral core sample from the Kuroshio Current area

Author(s)

Tomoya Nomura, Aya Sakaguchi, Peter Steier, Rosmarie Eigl, Akane Yamakawa, Takaaki Watanabe, Keiichi Sasaki, Tsuyoshi Watanabe, Robin Golser, Yoshio Takahashi, Hiroya Yamano

Abstract

The temporal distribution of

²³⁶U in the Northwest Pacific Ocean was reconstructed through measurements of the annual changes in

²³⁶U/

²³⁸U atom ratios in a coral core collected from Kume Island located within the Kuroshio Current region. In total, 74 years (1940–2014) of temporal trend of

²³⁶U/

²³⁸U atom ratios were reconstructed using Accelerator Mass Spectrometry (AMS). The annually resolved

²³⁶U/

²³⁸U ratios showed a strong increase from 1952, and two prominent peaks were found in the annual bands for 1954 (11.0 ± 1.2 × 10

^− 9) and 1958 (8.55 ± 1.17 × 10

^− 9); also an enhanced peak was observed for the band of 1963 (3.51 ± 0.20 × 10

^− 9). These peaks coincided with the occurrence of large nuclear tests in the Pacific Proving Grounds and/or the highest global fallout rate, suggesting a clear influence of these nuclear events on

²³⁶U/

²³⁸U atom ratios. Furthermore, the coral results showed some disagreement with the annual changes for

²³⁶U in East Asian corals collected at the entrance to the Sea of Japan. Based on these results, the mixing ratios of the surface seawater currents in the Northwest Pacific Ocean have been estimated.

Organisation(s)

Isotope Physics

External organisation(s)

Hiroshima University, University of Tsukuba, National Institute for Environmental Studies of Japan, Hokkaido University, Kanazawa Gakuin University, University of Tokyo

Journal

Marine Chemistry

Volume

190

Pages

28-34

No. of pages

7

ISSN

0304-4203

DOI

https://doi.org/10.1016/j.marchem.2016.12.008

Publication date

03-2017

Peer reviewed

Yes

Austrian Fields of Science 2012

103014 Nuclear physics, 105904 Environmental research, 105306 Oceanography

Keywords

ASJC Scopus subject areas

Water Science and Technology, General Chemistry, Oceanography, Environmental Chemistry

Portal url

https://ucrisportal.univie.ac.at/en/publications/f469b653-2d1f-4f74-8ebc-f349b667040b