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The Passage of the Bomb Radiocarbon Pulse into the Pacific Ocean

Published online by Cambridge University Press:  18 July 2016

William J Jenkins ,
Kathryn L Elder ,
Ann P McNichol  and
Karl von Reden
William J Jenkins*
Affiliation:
National Ocean Sciences Accelerator Mass Spectrometer Facility, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA
Kathryn L Elder
Affiliation:
National Ocean Sciences Accelerator Mass Spectrometer Facility, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA
Ann P McNichol
Affiliation:
National Ocean Sciences Accelerator Mass Spectrometer Facility, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA
Karl von Reden
Affiliation:
National Ocean Sciences Accelerator Mass Spectrometer Facility, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA
*
Corresponding author. Email: [email protected]
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Abstract

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We report and compare radiocarbon observations made on 2 meridional oceanographic sections along 150°W in the South Pacific in 1991 and 2005. The distributions reflect the progressive penetration of nuclear weapons-produced 14C into the oceanic thermocline. The changes over the 14 yr between occupations are demonstrably large relative to any possible drift in our analytical standardization. The computed difference field based on the gridded data in the upper 1600 m of the section exhibits a significant decrease over time (approaching 40 to 50‰ in Δ14C) in the upper 200–300 m, consistent with the decadal post-bomb decline in atmospheric 14C levels. A strong positive anomaly (increase with time), centered on the low salinity core of the Antarctic Intermediate Water (AAIW), approaches 50–60‰ in Δ14C, a clear signature of the downstream evolution of the 14C transient in this water mass. We use this observation to estimate the transit time of AAIW from its “source region” in the southeast South Pacific and to compute the effective reservoir age of this water mass. The 2 sections show small but significant changes in the abyssal 14C distributions. Between 1991 and 2005, Δ14C has increased by 9‰ below 2000 m north of 55°S. This change is accompanied overall by a modest increase in salinity and dissolved oxygen, as well as a slight decrease in dissolved silica. Such changes are indicative of greater ventilation. Calculation of “phosphate star” also indicates that this may be due to a shift from the Southern Ocean toward North Atlantic Deep Water as the ventilation source of the abyssal South Pacific.

Type
Marine
Information
Radiocarbon , Volume 52 , Issue 3: 20th Int. Radiocarbon Conference Proceedings , 2010 , pp. 1182 - 1190
Copyright
Copyright © 2010 by the Arizona Board of Regents on behalf of the University of Arizona 

References

Bainbridge, AE, Ostlund, HG, Craig, H, Broecker, WS, Spencer, DW. 1987. GEOSECS Atlantic, Pacific, and Indian Ocean expeditions: shore-based data and graphics. GEOSECS ATLAS, 7. 200 p.Google Scholar
Broecker, WS, Peng, T-H. 1980. The distribution of bomb-produced tritium and radiocarbon at GEOSECS station 347 in the eastern North Pacific. Earth and Planetary Science Letters 49(2):453–62.CrossRefGoogle Scholar
Broecker, WS, Peng, T-H, Ostlund, HG, Stuiver, M. 1985. The distribution of bomb radiocarbon in the ocean. Journal of Geophysical Research 90(C90):6953–70.Google Scholar
Broecker, WS, Sutherland, S, Peng, T-H. 1999. A possible 20th-century slowdown of Southern Ocean deep water formation. Science 286(5442):1132–5.Google Scholar
Broecker, WS, Sutherland, SC, Smethie, WM, Peng, T-H, Ostlund, HG. 1995. Oceanic radiocarbon: separation of the natural and bomb components. Global Biogeochemical Cycles 9(2):263–88.Google Scholar
Butzin, M, Prange, M, Lohmann, G. 2005. Radiocarbon simulations for the glacial ocean: the effects of wind stress, Southern Ocean sea ice and Heinrich events. Earth and Planetary Science Letters 235(1–2):45–61.Google Scholar
Craig, H. 1969. Abyssal carbon and radiocarbon in the Pacific. Journal of Geophysical Research 74(23):5491–506.Google Scholar
Doney, S, Hecht, MW. 2002. Antarctic Bottom Water formation and deep-water chlorofluorocarbon distributions in a global ocean climate model. Journal of Physical Oceanography 329(6):1642–66.Google Scholar
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(C2):1271–80.CrossRefGoogle Scholar
Elder, KL, McNichol, AP, Gagnon, AR. 1998. Evaluating reproducibility of seawater, inorganic and organic carbon 14C results at the National Ocean Sciences AMS Facility (NOSAMS). Radiocarbon 40(1):223–30.Google Scholar
England, MH, Maier-Reimer, E. 2001. Using chemical tracers to assess ocean models. Reviews of Geophysics 39(1):29–70.Google Scholar
Georgi, DT. 1979. Modal properties of Antarctic Intermediate Water in the Southeast Pacific and the South Atlantic. Journal of Physical Oceanography 9(3):456–8.Google Scholar
Hua, Q, Barbetti, M. 2004. Review of tropospheric bomb 14C data for carbon cycle modeling and age calibration purposes. Radiocarbon 46(3):1273–98.Google Scholar
Iudicone, D, Rodgers, KB, Schopp, R, Madec, G. 2007. An exchange window for the injection of Antarctic Intermediate Water into the South Pacific. Journal of Physical Oceanography 37(1):31–49.Google Scholar
Jenkins, WJ, Rhines, PB. 1980. Tritium in the deep North Atlantic Ocean. Nature 286(5776):877–80.Google Scholar
Key, RM. 1996. WOCE Pacific Ocean radiocarbon program. Radiocarbon 38(3):415–23.Google Scholar
Key, RM, Quay, P, Jones, GA, McNichol, AP, von Reden, K, Schneider, RJ. 1996. WOCE AMS radiocarbon I: Pacific Ocean results (P6, P16 and P17). Radiocarbon 38(3):425–518.Google Scholar
Key, RM, Quay, P, Schlosser, P, McNichol, AP, von Reden, K, Schneider, B, Elder, KL, Stuiver, M, Ostlund, HG. 2002. WOCE Radiocarbon IV: Pacific results; P10, P13N, P14C, P18, P19 & S4P. Radiocarbon 44(1):239–392.Google Scholar
Kuhlbrodt, T, Griesel, A, Montoya, M, Levemann, A, Hofmann, M, Rahmstorf, S. 2007. On the driving processes of the Atlantic meridional overturning circulation. Reviews of Geophysics 45: RG2001, doi:10.1029/2004RG000166.Google Scholar
Liu, Z, Alexander, M. 2007. Atmospheric bridge, oceanic tunnel, and global climate teleconnections. Reviews of Geophysics 45: RG2005, doi:10.1029/2005RG000172.Google Scholar
Mahadevan, A. 2001. An analysis of bomb radiocarbon trends in the Pacific. Marine Chemistry 73(3–4):273–90.Google Scholar
McCartney, MS. 1977. Subantarctic mode water. In: Angel, M, editor. A Voyage of Discovery. Oxford: Pergammon Press. p 103–19.Google Scholar
McCreary, JP, Lu, P. 1994. Interaction between the subtropical and equatorial ocean circulations: the subtropical cell. Journal of Physical Oceanography 24(2):466–97.Google Scholar
McNeil, BI, Matear, RJ, Key, RM, Bullister, JL, Sarmiento, JL. 2003. Anthropogenic CO2 uptake by the ocean based on the global chlorofluorocarbon data set. Science 229(5604):235–9.Google Scholar
McNichol, AP, Gagnon, AR, Jones, GA, Osborne, EA. 1992. Illumination of a black box: analysis of gas composition during graphite target preparation. Radiocarbon 34(3):321–9.Google Scholar
McNichol, AP, Jones, GA, Hutton, DL, Gagnon, AR. 1994. The rapid preparation of seawater ΣCO2 for radiocarbon analysis at the National Ocean Sciences AMS Facility. Radiocarbon 36(2):237–46.CrossRefGoogle Scholar
Munk, WH. 1966. Abyssal recipes. Deep-Sea Research 13:707–30.Google Scholar
Ostlund, HG, Dorsey, HG, Rooth, CG. 1974. GEOSECS North Atlantic radiocarbon and tritium results. Earth and Planetary Science Letters 23(1):69–86.CrossRefGoogle Scholar
Reid, JL. 1986. On the total geostrophic circulation of the South Pacific Ocean: flow patterns, tracers and transports. Progress in Oceanography 16(1):1–61.Google Scholar
Reimer, PJ, Reimer, RW. 2001. A marine reservoir correction database and on-line interface. Radiocarbon 43(2A):461–3.Google Scholar
Rodgers, KB, Aumont, O, Madec, G, Menkes, C, Blanke, B, Monfray, P, Orr, JC, Schrag, D. 2004. Radiocarbon as a thermocline proxy for the eastern equatorial Pacific. Geophysical Research Letters 31: L14314, doi:10.1029/2004GL019764.Google Scholar
Rubin, SI, Key, RM. 2002. Separating natural and bomb-produced radiocarbon in the ocean: the potential alkalinity method. Global Biogeochemical Cycles 16(4):1105, doi:10.1029/2001GB001432.Google Scholar
Schlosser, P, Bullister, JL, Fine, RA, Jenkins, WJ, Key, RM, Lupton, JE, Roether, W, Smethie, WM. 2001. Transformation and age of water masses. In: Siedler, G, Church, J, Gould, J, editors. Ocean Circulation and Climate: Observing and Modelling the Global Ocean. International Geophysics Series. San Diego: Academic Press. p 431–52.Google Scholar
Scott, EM, Bryant, C, Cook, GT, Naysmith, P. 2003. Is there a Fifth International Radicarbon Comparison (VIRI)? Radiocarbon 45(3):493–5.Google Scholar
Smith, WHF, Wessel, P. 1990. Gridding with continuous curvature splines in tension. Geophysics 55(3):293–305.Google Scholar
Stuiver, M, Polach, HA. 1977. Discussion: reporting of 14C data. Radiocarbon 19(3):355–63.CrossRefGoogle Scholar
Vogel, JS, Southon, JR, Nelson, DE. 1987. Catalyst and binder effects in the sues of filamentous graphite for AMS. Nuclear Instruments and Methods in Physics Research B 29(1):50–6.Google Scholar
Waugh, DW, Hall, TM, McNeil, BI, Key, RM, Matear, RJ. 2006. Anthropogenic CO2 in the oceans estimated using transit time distributions. Tellus B 58(5):376–89.Google Scholar