Title |
In Situ Spectrophotometric Measurement of Dissolved Inorganic Carbon in Seawater
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Published in |
Environmental Science & Technology, September 2013
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DOI | 10.1021/es4014807 |
Pubmed ID | |
Authors |
Xuewu Liu, Robert H. Byrne, Lori Adornato, Kimberly K. Yates, Eric Kaltenbacher, Xiaoling Ding, Bo Yang |
Abstract |
Autonomous in situ sensors are needed to document the effects of today's rapid ocean uptake of atmospheric carbon dioxide (e.g., ocean acidification). General environmental conditions (e.g., biofouling, turbidity) and carbon-specific conditions (e.g., wide diel variations) present significant challenges to acquiring long-term measurements of dissolved inorganic carbon (DIC) with satisfactory accuracy and resolution. SEAS-DIC is a new in situ instrument designed to provide calibrated, high-frequency, long-term measurements of DIC in marine and fresh waters. Sample water is first acidified to convert all DIC to carbon dioxide (CO2). The sample and a known reagent solution are then equilibrated across a gas-permeable membrane. Spectrophotometric measurement of reagent pH can thereby determine the sample DIC over a wide dynamic range, with inherent calibration provided by the pH indicator's molecular characteristics. Field trials indicate that SEAS-DIC performs well in biofouling and turbid waters, with a DIC accuracy and precision of ∼2 μmol kg(-1) and a measurement rate of approximately once per minute. The acidic reagent protects the sensor cell from biofouling, and the gas-permeable membrane excludes particulates from the optical path. This instrument, the first spectrophotometric system capable of automated in situ DIC measurements, positions DIC to become a key parameter for in situ CO2-system characterizations. |
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Geographical breakdown
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Japan | 1 | 1% |
United States | 1 | 1% |
Canada | 1 | 1% |
Unknown | 78 | 96% |
Demographic breakdown
Readers by professional status | Count | As % |
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Researcher | 19 | 23% |
Student > Master | 16 | 20% |
Student > Bachelor | 6 | 7% |
Other | 5 | 6% |
Other | 5 | 6% |
Unknown | 11 | 14% |
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Other | 9 | 11% |
Unknown | 15 | 19% |