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Variation of Surface Radiocarbon in the North Pacific During Summer Season 2004–2016

  • T Aramaki (a1), S Nakaoka (a1), Y Terao (a1), S Kushibashi (a1), T Kobayashi (a1), Y Osonoi (a1), H Mukai (a1) and Y Tohjima (a1)...

Abstract

Surface radiocarbon (Δ14C) in the North Pacific has been monitored using a commercial volunteer observation ship since the early 2000s. Here we report the temporal and spatial variations in Δ14C in the summer surface water when the surface ocean is vertically stratified over a 13-yr period, 2004–2016. The long-term Δ14C decreasing trend after the late 1970s in the subtropical region has continued to the present and the rate of decrease of the Kuroshio and Kuroshio Extension, North Pacific and California current areas is calculated to be –3.3, –5.2 and –3.3 ‰/yr, respectively. After 2012 the Δ14C of the Kuroshio and Kuroshio Extension area, however, has remained at an approximately constant value of around 50‰. The result may indicate that subtropical surface Δ14C in the western North Pacific has reached an equilibrium with atmospheric Δ14CO2. The Δ14C in the subarctic region is markedly lower than values in the subtropical region and it seems that the decreasing tendency of surface Δ14C has changed to an increasing tendency after 2010. The results may indicate that bomb-produced 14C, which has accumulated below the mixed layer in the past few decades, has been entrained into the surface layer by deep convection.

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*Corresponding author. Email: ara@nies.go.jp.

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Selected Papers from the 23rd International Radiocarbon Conference, Trondheim, Norway, 17–22 June, 2018

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References

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Aramaki, T, Mizushima, T, Mizutani, Y, Yamatoto, T, Togawa, O, Kabuto, S, Kuji, T, Gottdang, A, Klein, M, Mous, DJW. 2000. The AMS facility at the Japan Atomic Energy Research Institute (JAERI). Nuclear Instruments and Methods in Physics Research B 172:1823.
Aramaki, T, Nojiri, Y, Mukai, H, Kushibashi, S, Uchida, M, Shibata, Y. 2010. Preliminary results of radiocarbon monitoring in the surface waters of the North Pacific. Nuclear Instruments and Methods in Physics Research B 268:10981101.
Broecker, WS, Gerard, R, Ewing, M, Heezen, B. 1960. Natural radiocarbon in the Atlantic Ocean. Journal of Geophysical Research 65:29032931.
Broecker, WS, Peng, T-H, Östlund, G, Stuiver, M. 1985. The distribution of bomb radiocarbon in the ocean. Journal of Geophysical Research 90:69536970.
Druffel, ERM. 1987. Bomb radiocarbon in the Pacific: Annual and seasonal timescale variations. Journal of Marine Research 45:667698.
Druffel, ERM. 1989. Decade time scale variability of ventilation in the North Atlantic determined from high precision measurements of bomb radiocarbon in banded corals. Journal of Geophysical Research 94:32713285.
Druffel, ERM, Griffin, S. 2008. Daily variability of dissolved inorganic radiocarbon at three sites in the surface ocean. Marine Chemistry 110:185189.
Druffel, EM, Linick, TW. 1978. Radiocarbon in annual coral rings of Florida. Geophysical Research Letters 5:913916.
Druffel, EM, Suess, HE. 1983. On the radiocarbon record in banded corals: exchange parameters and net transport of 14CO2 between atmosphere and surface ocean. Journal of Geophysical Research 88:12711280.
Key, RM, Quay, PD, Schlosser, P, McNichol, AP, von Reden, KF, Schneider, RJ, Elder, KL, Stuiver, M, Östlund, HG. 2002. WOCE radiocarbon IV: Pacific Ocean results; P10, P13N, P14C, P18, P19 & S4P. Radiocarbon 44(1):239392.
Kitagawa, H, Masuzawa, T, Nakamura, T, Matsumoto, E. 1993. A batch preparation method of graphite targets with low background for AMS 14C measurements. Radiocarbon 35(2):295300.
Kume, H, Shibata, Y, Tanaka, A, Yoneda, M, Kumamoto, Y, Uehiro, T, Morita, M. 1997. The AMS facility at the National Institute for Environmental Studies (NIES), Japan. Nuclear Instruments and Methods in Physics Research B 123:3133.
Levin, I, Kromer, B. 2004. The tropospheric 14CO2 level in mid latitudes of the Northern Hemisphere (1959–2003). Radiocarbon 46(3):12611271.
Levin, I, Hammer, S, Kromer, B, Meinhardt, F. 2008. Radiocarbon observations in atmospheric CO2: determining fossil fuel CO2 over Europe using Jungfraujoch observations as background. Science of the Total Environment 391(2–3):211216.
NOAA (National Oceanic and Atmospheric Administration). 2019. https://www.ospo.noaa.gov/Products/ocean/sst/anomaly/.
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 5:825828.
Nydal, R, Lovseth, K. 1983. Tracing bomb 14C in the atmosphere 1962–1980. Journal of Geophysical Research 88:36213642.
McDuffee, K, Druffel, ERM. 2007. Daily variability of dissolved inorganic radiocarbon in Sargasso Sea surface water. Marine Chemistry 106:510515.
Morimoto, M, Kitagawa, H, Shibata, Y, Kayanne, H. 2004. Seasonal radiocarbon variation of surface seawater recorded in a coral from Kikai Island, subtropical northwestern Pacific. Radiocarbon 46(2):643648.
Murphy, PP, Nojiri, Y, Fujinuma, Y, Wong, CS, Zeng, J, Kimoto, T, Kimoto, H. 2001. Measurements of surface seawater fCO2 from volunteer commercial ships: techniques and experiences from Skaugran. Journal of Atmospheric and Oceanic Technology 18:17191734.
Östlund, HG, Stuiver, M. 1980. GEOSECS Pacific radiocarbon. Radiocarbon 22(1):2553.
Peng, T-H, Key, RM, Östlund, HG. 1998. Temporal variations of bomb radiocarbon inventory in the Pacific Ocean. Marine Chemistry 60:313.
Stuiver, M, Östlund, HG. 1980. GEOSECS Atlantic radiocarbon. Radiocarbon 22(1):124.
Stuiver, M, Östlund, HG. 1983. GEOSECS Indian Ocean and Mediterranean radiocarbon. Radiocarbon 25(1):129.
Stuiver, M, Polach, HA. 1977. Discussion: reporting of 14C data. Radiocarbon 19(3):355363.
Zeng, J, Nojiri, Y, Murphy, PP, Wong, CS, Fujinuma, Y. 2002. A comparison of ΔpCO2 distributions in the northern North Pacific using results from a commercial vessel in 1995–1999. Deep-Sea Research 49:53035315.

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Variation of Surface Radiocarbon in the North Pacific During Summer Season 2004–2016

  • T Aramaki (a1), S Nakaoka (a1), Y Terao (a1), S Kushibashi (a1), T Kobayashi (a1), Y Osonoi (a1), H Mukai (a1) and Y Tohjima (a1)...

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