Index of /ftp/oceans/Historical_C14_obs
Please cite this data set as:
Graven, H., A. Kozyr, and R. M. Key. 2012. Historical observations of oceanic radiocarbon conducted prior to GEOSECS.
http://cdiac.ornl.gov/ftp/oceans/Historical_C14_obs/. Carbon Dioxide Information Analysis Center,
Oak Ridge National Laboratory, US Department of Energy, Oak Ridge, Tennessee. doi: 10.3334/CDIAC/OTG.HIST_C14_OBS
Historical observations of oceanic radiocarbon conducted prior to GEOSECS.
Prepared by Heather Graven (firstname.lastname@example.org), Alex Kozyr (email@example.com), amd Robert Key (firstname.lastname@example.org>), July 2012.
This dataset contains historical measurements of radiocarbon in oceanic dissolved inorganic carbon. The measurements were
compiled and digitized from published articles (Bien et al. 1960, 1965; Broecker et al. 1960; Fairhall and Young 1985; and Linick 1978).
The data compilation contains roughly 1500 observations over the period 1955-1974. Samples were collected at the ocean surface and at
various depths in the ocean interior. All of the major ocean basins are represented. The methodology involved large-volume sampling of
seawater that was acidified to release CO2. The collected CO2 was analyzed for the 14C/C ratio by counting techniques at the La Jolla,
Lamont or University of Washington laboratories. The measurements are reported as D14C, which includes a correction for mass dependent
fractionation using measurements of d13C in the CO2 samples. When measurements of d13C were not available, estimates of d13C were used
to calculate D14C. Further details are available in the original publications.
In some samples from Broecker et al. (1960), isotopic fractionation occurred while sampling. D14C is not affected by fractionation, due
to the d13C correction, but the reported d13C in these cases is not representative of oceanic d13C. We omit d13C measurements on samples
assumed to have experienced fractionatation (d13C less than -2.8 permil or greater than +2.8 permil), though we caution that some of the
retained d13C data from Broecker et al. (1960) may not be reliable.
In some samples from Fairhall and Young (1985), a date range rather than a single date was given for the sample date. We use the midpoint
of the date range for these samples.
Linick (1978) updates D14C measurements previously reported by Bien et al. (1960; 1965), among others. We use the D14C data of Linick (1978)
for these samples, filling in temperature and salinity data from Bien et al. (1960; 1965) that was missing in Linick (1978).
Observations of dissolved inorganic carbon concentration from Fairhall and Young (1985) were converted from mM to umol/kg by assuming constant
density of 1.025 kg/l
The datafile contains 14 columns: Cruise Name, Sample Identification Number, Latitude, Longitude, Date, Depth (m), Temperature (degrees C),
Salinity, D14C (permil), D14C uncertainty (permil), d13C (permil), d13C uncertainty (permil), Dissolved Inorganic Carbon concentration (umol/kg), ,
Source. Missing data is denoted with values of -999.
Bien, G. S., N. W. Rakestraw and H. E. Suess. 1960). Radiocarbon Concentration in Pacific Ocean Water. Tellus, 12(4), 436-443.
Bien, G. S., N. W. Rakestraw and H. E. Suess. 1965. Radiocarbon in the Pacific and Indian Oceans and its relation to deep water movements.
Limnol. Oceanogr., 10 (Suppl 5): R25-R37. http://www.jstor.org/stable/2833537
Broecker, W. S., R. Gerard, M. Ewing, and B. C. Heezen. 1960. Natural Radiocarbon in the Atlantic Ocean. J. Geophys. Res., 65(9), 2903-2931,
Fairhall, A. W., and J. A. Young. 1985. Historical 14C measurements from the Atlantic, Pacific, and Indian Oceans, Radiocarbon, 27(3), 473-507.
Linick, T.W. 1978. La Jolla measurements of radiocarbon in the oceans. Radiocarbon, 20, 333-359.