A comparison of dissolved chlorofluorocarbons in seawater measured by MRI and JMA CFCs Systems.

Abstract

In 2002, a new system for measuring dissolved chlorofluorocarbons (CFC-11, CFC-12, and CFC-113: CFCs) in seawater was developed by the Climate and Marine Department, Japan Meteorological Agency (JMA). During the Ryofu Maru RF03-04 cruise in the western North Pacific in April and May 2003, CFCs concentrations measured by this system were compared with those measured by the Meteorological Research Institute's (MRI's) system that had been used for CFCs measurements in this region since 2000, using a common calibration scale and the same sampling protocol.  The precisions of analysis by the MRI system, as determined from analysis of replicate samples, were 0.037 pmol/kg seawater (1.4%) for CFC-12, 0.049 pmol/kg (1.0%) for CFC-11 and 0.012 pmol/kg (2.3%) for CFC-113. The precisions of analysis by the JMA system were 0.008 pmol/kg seawater (0.4%) for CFC-12, 0.011 pmol/kg (0.2%) for CFC-11 and 0.012 pmol/kg (3.0%) for CFC-113.  The no discrepancy in the concentrations of CFCs measured by the MRI and JMA systems was found at the 95% of significance level for these CFCs. These results suggest that if only the calibration scale were inter-compared, we could obtain comparable CFCs data in seawater.