Zobrazit v EDS

Spectrophotometric high-precision seawater pH determination for use in underway measuring systems.

Uloženo v:
Podrobná bibliografie
Název: Spectrophotometric high-precision seawater pH determination for use in underway measuring systems.
Autoři: Aßmann, S., Frank, C., Kötzinger, A.
Zdroj: Ocean Science Discussions; 2011, Vol. 8 Issue 3, p1339-1367, 29p
Témata: SPECTROPHOTOMETRY, SPECTROPHOTOMETERS, PH effect, SEAWATER, ASTRONOMICAL instruments
Abstrakt: Autonomous sensors are required for a comprehensive documentation of the changes in the marine carbon system and thus to differentiate between its natural variability and anthropogenic impacts. Spectrophotometric determination of pH -- a key variable of the seawater carbon system -- is particularly suited to achieve precise and drift-free measurements. However, available spectrophotometric instruments are not suitable for integration into automated measurement systems (e.g. FerryBox) since they do not meet the major requirements of reliability, stability, robustness and moderate cost. Here we report on the development and testing of a new indicator-based pH sensor that meets all of these requirements. This sensor can withstand the rough conditions during long-term deployments on ships of opportunities and is applicable on the open ocean as well as in coastal waters with complex background and highly variable conditions. The sensor uses a high resolution CCD spectrometer as detector connected via optical fibers to a custom-made cuvette designed to reduce the impact of air bubbles. The sample temperature can be precisely adjusted (25 °C±0.006 °C) using computer- controlled power supplies and Peltier elements thus avoiding the widely used water bath. The overall setup achieves a measurement frequency of 1 min-1 with a precision of ±0.0007 pH units and an average offset of +0.0018 pH units to a pH reference during shipboard operation. Application of this sensor allows monitoring of seawater pH in autonomous underway systems, providing a key variable for characterization and understanding the marine carbon system. [ABSTRACT FROM AUTHOR]
Copyright of Ocean Science Discussions is the property of Copernicus Gesellschaft mbH and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
Databáze: Complementary Index
Popis
Abstrakt:Autonomous sensors are required for a comprehensive documentation of the changes in the marine carbon system and thus to differentiate between its natural variability and anthropogenic impacts. Spectrophotometric determination of pH -- a key variable of the seawater carbon system -- is particularly suited to achieve precise and drift-free measurements. However, available spectrophotometric instruments are not suitable for integration into automated measurement systems (e.g. FerryBox) since they do not meet the major requirements of reliability, stability, robustness and moderate cost. Here we report on the development and testing of a new indicator-based pH sensor that meets all of these requirements. This sensor can withstand the rough conditions during long-term deployments on ships of opportunities and is applicable on the open ocean as well as in coastal waters with complex background and highly variable conditions. The sensor uses a high resolution CCD spectrometer as detector connected via optical fibers to a custom-made cuvette designed to reduce the impact of air bubbles. The sample temperature can be precisely adjusted (25 °C±0.006 °C) using computer- controlled power supplies and Peltier elements thus avoiding the widely used water bath. The overall setup achieves a measurement frequency of 1 min<sup>-1</sup> with a precision of ±0.0007 pH units and an average offset of +0.0018 pH units to a pH reference during shipboard operation. Application of this sensor allows monitoring of seawater pH in autonomous underway systems, providing a key variable for characterization and understanding the marine carbon system. [ABSTRACT FROM AUTHOR]
ISSN:18120806
DOI:10.5194/osd-8-1339-2011