PMEL has led in development of tracer techniques
- Pioneered CFC observations in ocean (1980s and 1990s)
- Developed SF6, N2O methods in past 5 years
- Has designed and assembled analytical systems for other major laboratories (U. Washington, U. Texas)
- Developed water sampling bottles and sampling gear widely used on oceanographic expeditions
- Provides CFC and SF6 calibration standards for International CLIVAR groups
- Provides N2O and CH4 standards for Scientific Committee on Ocean Research (SCOR)
Standards are prepared in Aculife treated high pressure gas cylinders from the pure compounds and diluted with ultra-pure nitrogen. Typically, the gas standards are prepared in two concentration ranges to facilitate air and seawater calibration. The ‘air’ standards are prepared with the ratios of the gases of interest similar to modern atmospheric values. The ‘water ratio’ standards are prepared with the ratios of the gases in the standard similar to those in modern near surface seawater. After preparation, the standards are monitored for several months to check for stability. Concentrations are determined by comparison to primary standards calibrated at the Scripps Institution of Oceanography (SIO).