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Seasonal Radiocarbon Variation of Surface Seawater Recorded in A Coral from Kikai Island, Subtropical Northwestern Pacific

Published online by Cambridge University Press:  18 July 2016

Maki Morimoto*
Affiliation:
Graduate School of Environmental Studies, Nagoya University, Nagoya 464-8601, Japan
Hiroyuki Kitagawa
Affiliation:
Graduate School of Environmental Studies, Nagoya University, Nagoya 464-8601, Japan
Yasuyuki Shibata
Affiliation:
National Institute for Environmental Studies, Tsukuba 305-8506, Japan
Hajime Kayanne
Affiliation:
Department of Earth and Planetary Science, University of Tokyo, Tokyo 113-0033, Japan
*
Corresponding author. Email: morimoto@ihas.nagoya-u.ac.jp.
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Abstract

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A coral radiocarbon (Δ14C) investigation with a high time-resolution is crucial for reconstructing secular and seasonal Δ14C changes in the surface seawater which potentially reflect ocean circulations and dynamic ocean-atmosphere interactions. The Δ14C values of a modern coral (Porites sp.) from Kikai Island, southern Japan, in the subtropical northwestern Pacific, were determined for the period of 1991-1998 at a monthly resolution. A coral Δ14C time series for the 8 yr indicated seasonal cycles superimposed on a secular decreasing trend of 3.8 per yr. The seasonal amplitude of the coral Δ14C was about 18 on the average, and the minimum Δ14C was observed in late spring and summer. The Δ14C changes were tentatively explained by horizontal oceanic advections around Kikai Island or over the wide range of the equatorial and sub-equatorial Pacific.

Type
Part II
Copyright
Copyright © The Arizona Board of Regents on behalf of the University of Arizona 

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