抄録
To detect slight changes of oceanic carbon cycle in response to atmospheric
C02 increase, high precise measurements of oceanic C02-system properties are
necessary. For the purpose, we examined to improve a coulometer (model 5012,UIC),
which is generally used to detect a temporal increase of total dissolved inorganic
carbon (TC02) in the ocean. In addition, we produced in-house reference materials
(RM), which are traceable to certified reference materials (CRM), to monitor
performance of a TC02 measuring system.
For the coulometer improvement, we improved the photometric detection part
of a coulometer to minimize variations of light source intensity. The repeatability
was improved to be 0.03%(relative standard deviation), which was previously
0.08%. Measurements of RMs showed no statistically significant changes over
approx. 2 years. The RM was judged to be useful as a standard for monitoring
TC02, It is also useful for reducing systematic erros of TC02 values, which are
