Source and Scope of the Data

During the GEOSECS expeditions, over 2200 water samples were collected. Samples for ¹⁴C were collected at 124 stations, and approximately 18 samples were collected at each station from intervals throughout the water column.

The sampling technique and measurement procedure used in the radiocarbon determinations is described in a paper by Stuiver et al. (1974). On board the ship, the samples for radiocarbon determination were water drawn from 270-liter Gerard barrels and CO₂ was extracted following a method modified from Fonselius and Ostlund (1959). The CO₂ samples were absorbed in excess NaOH, kept in well-sealed bottles, and sent to laboratories for further processing.

The delta ¹⁴C scale used is basically the same as the one proposed by Broecker and Olson (1961) and follows the recommendations of Stuiver and Polach (1977). Specifically, these recommendations are that the delta ¹⁴C values are recalculated to a standardized state of isotopic fractionation equivalent to standard wood (delta¹³C = -25%) and that they relate to activities at the time of sampling (Stuiver and Ostlund, 1980).

In this package, GEOSECS radiocarbon data from the Atlantic, Pacific, and Indian Oceans are presented. All the radiocarbon, hydrographic, and position data presented in this package have been provided by the Oceanographic Data Facility at SIO. Only a small portion of the GEOSECS data available from SIO's Data Facility are presented here. These data include the following: position (degrees and minutes), sample number, depth (in meters as calculated from density and pressure), potential temperature (°Celsius), salinity (unit g/kg seawater), and delta ¹⁴C (on the scale defined above) determinations from the University of Miami and the University of Washington (Table 1).

Further details about the cruises, sampling methods, and radiocarbon determinations, along with the track maps showing station locations are provided in the pertinent literature section in the back of the printed version of this document.