Background Information

The most extensive chemical and radiochemical survey of the oceans carried out thus far has been the Geochemical Ocean Section Study (GEOSECS). GEOSECS, initiated in 1971, was designed to establish a baseline data base for assessing future chemical changes in the world's oceans and to provide a better understanding of large-scale oceanic transport and mixing processes. During the GEOSECS program, measurements of hydrographic parameters (salinity, temperature, and oxygen verses particularly the radioactive substances, radiocarbon, tritium, and radon were obtained. The logistics and handling of GEOSECS cruises and analyses were coordinated by Scripps Institution of Oceanography (SIO) and all fieldwork was directed by the late Arnold Bainbridge, of SIO.

The GEOSECS program involved cruises of the Atlantic, Pacific, and Indian Oceans, respectively. The number of stations occupied in each ocean was 121, 147, and 141, respectively. The Atlantic Ocean was the first surveyed (July 18, 1972 - April 1, 1973), followed by the Pacific Ocean (August 22, 1973 - June 10, 1974), and finally the Indian Ocean (December 4, 1977 - April 24, 1978). These expeditions have been outlined by Craig (1974), Craig and Turekian (1976), and Craig and Turekian (1980). Each cruise was followed by several years of analytical work in the laboratories ashore and all hydrographic data, sections, and profiles have been published in a series of GEOSECS atlases.

With respect to carbon dioxide research and the "greenhouse effect", the GEOSECS program generated a series of data sets from several ocean regions which are critical to the carbon cycle research. These data sets may provide direct evidence of carbon buildup in the oceans from increased atmospheric CO₂ (e.g., either from dissolved CO₂ or inorganic carbon). The ¹⁴C studies, which were an integral part of the GEOSECS program, provide the data necessary for gaining a better understanding of large scale oceanic mixing processes and for calculating the replacement times of deep ocean waters.

Stuiver and Ostlund (1980), Oslund and Stuiver (1980), and Stuiver and Ostlund (1983) detailed the general features of ¹⁴C distribution from data obtained during the GEOSECS cruises in the Atlantic, Pacific, and Indian Oceans, respectively. These publications preceded the publication of the finalized shipboard shore based data in volume 7 of the GEOSECS atlas series (GEOSECS, 1987). In this package the finalized delta ¹⁴C published in volume 7 of the GEOSECS atlas series are presented. These radiocarbon data were obtained from the STS/Oceanographic Data Facility at SIO and were extracted from the larger volume of GEOSECS data available.