关键词：
SPECTROPHOTOMETRY
IN situ microanalysis
HYDROGEN-ion concentration
SEAWATER -- Carbon content
SIMULATION methods & models
摘要：
A new, in situ sensing system, Channelized Optical System (CHANOS), was recently developed to make high-resolution, simultaneous measurements of total dissolved inorganic carbon (DIC) and pH in seawater. Measurements made by this single, compact sensor can fully characterize the marine carbonate system. The system has a modular design to accommodate two independent, but similar measurement channels for DIC and pH. Both are based on spectrophotometric detection of hydrogen ion concentrations. The pH channel uses a flow-through, sample-indicator mixing design to achieve near instantaneous measurements. The DIC channel adapts a recently developed spectrophotometric method to achieve flow-through CO2 equilibration between an acidified sample and an indicator solution with a response time of only similar to 90 s. During laboratory and in situ testing, CHANOS achieved a precision of +/- 0.0010 and +/- 2.5 mu mol kg(-1) for pH and DIC, respectively. In situ comparison tests indicated that the accuracies of the pH and DIC channels over a three-week time-series deployment were +/- 0.0024 and +/- 4.1 mu mol kg(-1), respectively. This study demonstrates that CHANOS can make in situ, climatology-quality measurements by measuring two desirable CO2 parameters, and is capable of resolving the CO2 system in dynamic marine environments.
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