NDP-057A

Carbon-14 Measurements in Surface Water CO₂ from the Atlantic, Indian, and Pacific Oceans, 1965-1994

Reidar Nydal, Department of Physics, The Norwegian University of Science and Technology, Trondheim, Norway
Prepared by: Antoinette Brenkert and Tom Boden, CDIAC

NDP-057A (1998)

A total of 950 ocean surface water observations were made from 1965 through 1994 by the Radiological Dating Laboratory (RDL) at the Norwegian Institute of Technology. The measurements were taken at 30 stations in the Atlantic Ocean, 14 stations in the Indian Ocean, and 38 stations in the Pacific Ocean. Thirty-two of the 950 samples were taken in the Atlantic Ocean during the R/V Andenes research cruise. Carbon-14 was measured in 871 of the 950 samples, and those measurements have been corrected (¹⁴C) for isotopic fractionation and radioactive decay. The ¹⁴C values range between 113.3 and 280.9 per mille (‰) and have a mean value of 101.3 ‰. The highest yearly mean (146.5 ‰) was calculated for 1969, and the lowest yearly mean value was calculated for 1990 (67.9 ‰), illustrating a decrease over time. This decrease was to be expected as a result of the ban on atmospheric thermonuclear tests and the slow mixing of the ocean surface waters with the deeper layers. The ¹⁴C values varied widely depending on where and when the sample was taken (i.e., upwelling areas, far northern or southern latitudes, near freshwater influxes, temperature, salinity). In addition to the corrected ¹⁴C data, ¹³C data used in correcting the ¹⁴C data for fractionation are provided, as are the temperature, salinity, and depth measurements and information on where and when the samples were taken.

These data, coupled with other ¹⁴C data sets, can lead to a greater understanding of the dynamic carbon reservoir and lead to a crude picture of anomalous sources and sinks at different geographical latitudes. The database is outstanding for its inclusion of early ¹⁴C measurements, broad spatial coverage of sampling, relative consistency of sampling methods, and ¹⁴C calculation results corrected for isotopic fractionation and radioactive decay. This database replaces previous versions published by Reidar Nydal and the RDL. WDC-A database

Corrected ¹⁴C measurements over time.

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