Calibration-free Spectrophotometric Measurements of Carbonate Saturation States in Seawater
This work describes efforts to improve methodologies and instrumentation for investigation of the marine CO2 system. In the first section of my thesis, a method was developed that provides simple, calibration-free measurements of seawater carbonate saturation states (Ωspec) based solely on the use o...
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ftusouthflorida:oai:digitalcommons.usf.edu:etd-8208 2023-07-30T04:06:01+02:00 Calibration-free Spectrophotometric Measurements of Carbonate Saturation States in Seawater Cuyler, Erin E. 2017-11-01T07:00:00Z application/pdf https://digitalcommons.usf.edu/etd/7011 https://digitalcommons.usf.edu/context/etd/article/8208/viewcontent/Cuyler_usf_0206M_14396.pdf unknown Digital Commons @ University of South Florida https://digitalcommons.usf.edu/etd/7011 https://digitalcommons.usf.edu/context/etd/article/8208/viewcontent/Cuyler_usf_0206M_14396.pdf USF Tampa Graduate Theses and Dissertations Carbon Dioxide Ocean Acidification pH Coastal Monitoring Spectrophotometry Marine Chemistry Other Oceanography and Atmospheric Sciences and Meteorology thesis 2017 ftusouthflorida 2023-07-13T21:53:51Z This work describes efforts to improve methodologies and instrumentation for investigation of the marine CO2 system. In the first section of my thesis, a method was developed that provides simple, calibration-free measurements of seawater carbonate saturation states (Ωspec) based solely on the use of a laboratory spectrophotometer. Measurements of pH are made in paired optical cells, one with and one without added nitric acid. The amount of added nitric acid is determined through the direct proportionality between nitrate concentration and UV absorbance. After an initial calibration, the method is calibration-free and requires no volumetric or gravimetric analyses thereafter. Saturation state measurements can be obtained in twelve minutes and attain Global Ocean Acidification Observing Network accuracy goals over a wide range of conditions. This simple one-step measurement protocol is ideal for monitoring ocean acidification conditions in coastal areas, fish hatcheries and shellfish farms. The second section of my thesis outlines the development of a next-generation handheld photometer for field measurements of seawater pH. The hand-held instrument is simple to use, inexpensive, and has a pH measurement accuracy of ±0.01. Each photometer is calibrated by relating pH-indicator absorbance ratios (RB) obtained with the broadband photometer to indicator absorbance ratios (RN) obtained with a high quality, narrowband scanning spectrophotometer. The RB vs RN relationship for each photometer is entered into the instrument’s software, providing discrete, real-time pH observations from measurements of RB, salinity and temperature. Measurement accuracy is assessed through comparisons of photometer pH with pH observations obtained using standard measurement procedures and high-quality spectrophotometers. The targeted user-groups for these instruments include middle and high school students, citizen scientists, and resource managers Thesis Ocean acidification University of South Florida St. Petersburg: Digital USFSP |
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Open Polar |
collection |
University of South Florida St. Petersburg: Digital USFSP |
op_collection_id |
ftusouthflorida |
language |
unknown |
topic |
Carbon Dioxide Ocean Acidification pH Coastal Monitoring Spectrophotometry Marine Chemistry Other Oceanography and Atmospheric Sciences and Meteorology |
spellingShingle |
Carbon Dioxide Ocean Acidification pH Coastal Monitoring Spectrophotometry Marine Chemistry Other Oceanography and Atmospheric Sciences and Meteorology Cuyler, Erin E. Calibration-free Spectrophotometric Measurements of Carbonate Saturation States in Seawater |
topic_facet |
Carbon Dioxide Ocean Acidification pH Coastal Monitoring Spectrophotometry Marine Chemistry Other Oceanography and Atmospheric Sciences and Meteorology |
description |
This work describes efforts to improve methodologies and instrumentation for investigation of the marine CO2 system. In the first section of my thesis, a method was developed that provides simple, calibration-free measurements of seawater carbonate saturation states (Ωspec) based solely on the use of a laboratory spectrophotometer. Measurements of pH are made in paired optical cells, one with and one without added nitric acid. The amount of added nitric acid is determined through the direct proportionality between nitrate concentration and UV absorbance. After an initial calibration, the method is calibration-free and requires no volumetric or gravimetric analyses thereafter. Saturation state measurements can be obtained in twelve minutes and attain Global Ocean Acidification Observing Network accuracy goals over a wide range of conditions. This simple one-step measurement protocol is ideal for monitoring ocean acidification conditions in coastal areas, fish hatcheries and shellfish farms. The second section of my thesis outlines the development of a next-generation handheld photometer for field measurements of seawater pH. The hand-held instrument is simple to use, inexpensive, and has a pH measurement accuracy of ±0.01. Each photometer is calibrated by relating pH-indicator absorbance ratios (RB) obtained with the broadband photometer to indicator absorbance ratios (RN) obtained with a high quality, narrowband scanning spectrophotometer. The RB vs RN relationship for each photometer is entered into the instrument’s software, providing discrete, real-time pH observations from measurements of RB, salinity and temperature. Measurement accuracy is assessed through comparisons of photometer pH with pH observations obtained using standard measurement procedures and high-quality spectrophotometers. The targeted user-groups for these instruments include middle and high school students, citizen scientists, and resource managers |
format |
Thesis |
author |
Cuyler, Erin E. |
author_facet |
Cuyler, Erin E. |
author_sort |
Cuyler, Erin E. |
title |
Calibration-free Spectrophotometric Measurements of Carbonate Saturation States in Seawater |
title_short |
Calibration-free Spectrophotometric Measurements of Carbonate Saturation States in Seawater |
title_full |
Calibration-free Spectrophotometric Measurements of Carbonate Saturation States in Seawater |
title_fullStr |
Calibration-free Spectrophotometric Measurements of Carbonate Saturation States in Seawater |
title_full_unstemmed |
Calibration-free Spectrophotometric Measurements of Carbonate Saturation States in Seawater |
title_sort |
calibration-free spectrophotometric measurements of carbonate saturation states in seawater |
publisher |
Digital Commons @ University of South Florida |
publishDate |
2017 |
url |
https://digitalcommons.usf.edu/etd/7011 https://digitalcommons.usf.edu/context/etd/article/8208/viewcontent/Cuyler_usf_0206M_14396.pdf |
genre |
Ocean acidification |
genre_facet |
Ocean acidification |
op_source |
USF Tampa Graduate Theses and Dissertations |
op_relation |
https://digitalcommons.usf.edu/etd/7011 https://digitalcommons.usf.edu/context/etd/article/8208/viewcontent/Cuyler_usf_0206M_14396.pdf |
_version_ |
1772818376968634368 |