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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*
Graduate School of Environmental Studies, Nagoya University, Nagoya 464-8601, Japan
Hiroyuki Kitagawa
Graduate School of Environmental Studies, Nagoya University, Nagoya 464-8601, Japan
Yasuyuki Shibata
National Institute for Environmental Studies, Tsukuba 305-8506, Japan
Hajime Kayanne
Department of Earth and Planetary Science, University of Tokyo, Tokyo 113-0033, Japan
Corresponding author. Email:
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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.

Part II
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Druffel, ERM. 1989. Decade timescale variability of ventilation in the North Atlantic: high-precision measurements of bomb radiocarbon in banded corals. Journal of Geophysical Research 94(C3):3271–85.CrossRefGoogle Scholar
Druffel, EM, Linick, TW. 1978. Radiocarbon in annual coral rings from Florida. Geophysical Research Letters 5(11):913–6.CrossRefGoogle Scholar
Guilderson, TP, Schrag, DP. 1998. Abrupt shift in subsurface temperature in the tropical Pacific associated with changes in El Niño. Science 281:240–3.CrossRefGoogle ScholarPubMed
Guilderson, TP, Schrag, DP, Kashgarian, M, Southon, J. 1998. Radiocarbon variability in the western equatorial Pacific inferred from a high-resolution coral record from Nauru Island. Journal of Geophysical Research 103(C11):24,64150.CrossRefGoogle Scholar
Levin, I, Kromer, B. 1997. Twenty years of atmospheric 14CO2 observations at Schauinsland station, Germany. Radiocarbon 39(2):205–18.CrossRefGoogle Scholar
Levin, I, Schuchard, J, Kromer, B, Münnich, KO. 1989. The continental European Suess effect. Radiocarbon 31(3):431–40.CrossRefGoogle Scholar
Meijer, HA, van der Plicht, J, Gislefoss, JS, Nydal, R. 1995. Comparing long-term atmospheric 14C and 3H records near Groningen, the Netherlands with Fruholmen, Norway and Izaña, Canary Islands 14C stations. Radiocarbon 37(1):3950.CrossRefGoogle Scholar
Moore, MD, Schrag, DP, Kashgarian, M. 1997. Coral radiocarbon constraints on the source of the Indonesian throughflow. Journal of Geophysical Research 102(C6):12,35965.CrossRefGoogle Scholar
Morimoto, M. 2002. A high time-resolution calibration of coral oxygen isotope records and mid-Holocene climate in the northwestern Pacific from corals [PhD dissertation]. Tokyo: University of Tokyo. 209 p.Google Scholar
Nozaki, Y, Rye, DM, Turekian, KK, Dodge, RE. 1978. A 200-year record of carbon-13 and carbon-14 variations in a Bermuda coral. Geophysical Research Letters 5(10):825–8.CrossRefGoogle Scholar
Ota, Y, Omura, A. 1992. Constructing styles and rates of tectonic uplift of coral reef terraces in the Ryukyu and Daito Islands, southwestern Japan. Quaternary International 15/16:1729.CrossRefGoogle Scholar
Rodgers, KB, Cane, MA, Schrag, DP. 1997. Seasonal variability of sea surface Δ14C in the equatorial Pacific in an ocean circulation model. Journal of Geophysical Research 102(C8):18,62739.CrossRefGoogle Scholar
Stuiver, M, Polach, HA. 1977. Discussion: reporting of 14C data. Radiocarbon 19(3):355–63.Google Scholar
Weber, JN, Woodhead, PMJ. 1972. Temperature dependence of oxygen-18 concentration in reef coral carbonates. Journal of Geophysical Research 77:463–73.CrossRefGoogle Scholar
Webster, JM, Davies, PJ, Konishi, K. 1998. Model of fringing reef development in response to progressive sea level fall over the last 7000 years—(Kikai-jima, Ryukyu Islands, Japan). Coral Reefs 17:289308.CrossRefGoogle Scholar