Marine Science Faculty Publications

An Automated Procedure for Laboratory and Shipboard Spectrophotometric Measurements of Seawater Alkalinity: Continuously Monitored Single-step Acid Additions

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Alkalinity, Seawater, Spectrophotometry, Indicator, CO2 system, Ocean acidification

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Building on the spectrophotometric procedure of Yao and Byrne (1998), an automated analysis system has been developed for laboratory and shipboard measurements of total alkalinity at a rate of 6 samples per hour. The system is based on single-point hydrochloric acid (HCl) titrations of seawater samples of a known volume with bromocresol purple as an indicator. The titration is continuously monitored using visible spectroscopy to guide the titration rate according to the real-time pH of the samples. Each titration is terminated just below the equivalence point to achieve a precision and accuracy near 1 μmol kg−1.

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Citation / Publisher Attribution

Marine Chemistry, v. 174, p. 141-146