Sampling and measurement of chlorofluorocarbons and sulfur hexafluoride in seawater.

Abstract

A number of laboratories throughout the world have developed analytical systems for measuring dissolved chlorofluorocarbons (CFCs) in seawater and have active programs to study the distribution of these substances in the ocean. New groups will likely become involved in making these measurements in the future. To maximize the scientific value of these studies, there is a clear need to insure that the measurements made by all groups are intercomparable and of the highest possible accuracy and precision. This is especially critical for ongoing programs such as the CLIVAR Repeat Hydrography Program, where global geochemical tracer data sets will be obtained by the combined efforts of a number of groups collecting and analyzing samples at different locations and times. The results from these efforts will be compared to earlier studies to detect changes in water mass ventilation rates, carbon uptake, oxygen utilization rates and other ocean processes, and serve as a baseline for future time-series studies utilizing these tracers.