In situ sensor technology for simultaneous spectrophotometric measurements of seawater total dissolved inorganic carbon and pH
Wang, Z.A.; Sonnichsen, F.N.; Bradley, A.M.; Hoering, K.A.; Lanagan, T.M.; Chu, S.N.; Hammar, T.R.; Camilli, R. (2015). In situ sensor technology for simultaneous spectrophotometric measurements of seawater total dissolved inorganic carbon and pH. Environ. Sci. Technol. 49(7): 4441-4449. https://dx.doi.org/10.1021/es504893n
In: Environmental Science and Technology. American Chemical Society: Easton. ISSN 0013-936X; e-ISSN 1520-5851, more
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| Authors | | Top |
- Wang, Z.A.
- Sonnichsen, F.N.
- Bradley, A.M.
- Hoering, K.A.
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- Lanagan, T.M.
- Chu, S.N.
- Hammar, T.R.
- Camilli, R.
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| Abstract |
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 ∼90 s. During laboratory and in situ testing, CHANOS achieved a precision of ±0.0010 and ±2.5 μmol 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 μmol 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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