Discrete Water Column Measurements of COsub2/sub Fugacity and pHsubT/sub in Seawater: A Comparison of Direct Measurements and Thermodynamic Calculations

S. McElligott; R. H. Byrne; K. Lee; R. Wanninkhof; F. J. Millero; R. A. Feely

doi:10.1016/S0304-4203(97)00080-7

Discrete Water Column Measurements of COsub2/sub Fugacity and pHsubT/sub in Seawater: A Comparison of Direct Measurements and Thermodynamic Calculations

S. McElligott, R. H. Byrne, K. Lee, R. Wanninkhof, F. J. Millero, R. A. Feely

College of Marine Science

Research output: Contribution to journal › Article › peer-review

Abstract

The NOAA Eq. Pac. CO 2 system data set (&simeq;2500 water samples) has been evaluated to assess the internal consistency of measurements and calculations involving CO 2 fugacity and pH T . This assessment represents the first large scale field comparison of pH T and f CO 2 data. Comparisons of direct discrete CO 2 fugacity ( f CO 2 ) measurements with CO 2 fugacity calculated from total inorganic carbon ( C T ), total alkalinity ( A T ) and spectrophotometric pH (pH T =−log[H + ] T ) indicate that a variety of improvements are needed in the parameter measurements and thermodynamic relationships used to relate f CO 2 , C T , A T and pH T in seawater. CO 2 fugacity calculated from C T and pH T or A T and pH T agree with direct measurements to no better than 1%. Comparisons of measured fugacity, f CO 2 (measured), and CO 2 fugacity calculated from C T and pH T , f CO 2 ( C T , pH T ), indicate that the precision of f CO 2 calculations is good relative to direct measurements. In contrast, due to the extreme sensitivity of f CO 2 and [H + ] T calculations to relatively small errors in both C T and A T , CO 2 fugacity, as well as [H + ] T , calculated from C T and A T are very imprecise and render comparisons with direct measurements of little use. Consequently, precise calculations of f CO 2 require the use of direct pH T measurements.

Original language	American English
Journal	Marine Chemistry
Volume	60
DOIs	https://doi.org/10.1016/S0304-4203(97)00080-7
State	Published - Jan 1 1998

Keywords

Seawater
Carbon dioxide
Fugacity
Spectrophotometric pH
Measurements
Thermodynamic calculations

Disciplines

Life Sciences

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https://doi.org/10.1016/S0304-4203(97)00080-7

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@article{7e290d98f9a1426386c57fd71b540c30,

title = "Discrete Water Column Measurements of COsub2/sub Fugacity and pHsubT/sub in Seawater: A Comparison of Direct Measurements and Thermodynamic Calculations",

abstract = " The NOAA Eq. Pac. CO 2 system data set (&simeq;2500 water samples) has been evaluated to assess the internal consistency of measurements and calculations involving CO 2 fugacity and pH T . This assessment represents the first large scale field comparison of pH T and f CO 2 data. Comparisons of direct discrete CO 2 fugacity ( f CO 2 ) measurements with CO 2 fugacity calculated from total inorganic carbon ( C T ), total alkalinity ( A T ) and spectrophotometric pH (pH T =−log[H + ] T ) indicate that a variety of improvements are needed in the parameter measurements and thermodynamic relationships used to relate f CO 2 , C T , A T and pH T in seawater. CO 2 fugacity calculated from C T and pH T or A T and pH T agree with direct measurements to no better than 1%. Comparisons of measured fugacity, f CO 2 (measured), and CO 2 fugacity calculated from C T and pH T , f CO 2 ( C T , pH T ), indicate that the precision of f CO 2 calculations is good relative to direct measurements. In contrast, due to the extreme sensitivity of f CO 2 and [H + ] T calculations to relatively small errors in both C T and A T , CO 2 fugacity, as well as [H + ] T , calculated from C T and A T are very imprecise and render comparisons with direct measurements of little use. Consequently, precise calculations of f CO 2 require the use of direct pH T measurements.",

keywords = "Seawater, Carbon dioxide, Fugacity, Spectrophotometric pH, Measurements, Thermodynamic calculations",

author = "S. McElligott and Byrne, {R. H.} and K. Lee and R. Wanninkhof and Millero, {F. J.} and Feely, {R. A.}",

year = "1998",

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doi = "10.1016/S0304-4203(97)00080-7",

language = "American English",

volume = "60",

journal = "Marine Chemistry",

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TY - JOUR

T1 - Discrete Water Column Measurements of COsub2/sub Fugacity and pHsubT/sub in Seawater: A Comparison of Direct Measurements and Thermodynamic Calculations

AU - McElligott, S.

AU - Byrne, R. H.

AU - Lee, K.

AU - Wanninkhof, R.

AU - Millero, F. J.

AU - Feely, R. A.

PY - 1998/1/1

Y1 - 1998/1/1

N2 - The NOAA Eq. Pac. CO 2 system data set (&simeq;2500 water samples) has been evaluated to assess the internal consistency of measurements and calculations involving CO 2 fugacity and pH T . This assessment represents the first large scale field comparison of pH T and f CO 2 data. Comparisons of direct discrete CO 2 fugacity ( f CO 2 ) measurements with CO 2 fugacity calculated from total inorganic carbon ( C T ), total alkalinity ( A T ) and spectrophotometric pH (pH T =−log[H + ] T ) indicate that a variety of improvements are needed in the parameter measurements and thermodynamic relationships used to relate f CO 2 , C T , A T and pH T in seawater. CO 2 fugacity calculated from C T and pH T or A T and pH T agree with direct measurements to no better than 1%. Comparisons of measured fugacity, f CO 2 (measured), and CO 2 fugacity calculated from C T and pH T , f CO 2 ( C T , pH T ), indicate that the precision of f CO 2 calculations is good relative to direct measurements. In contrast, due to the extreme sensitivity of f CO 2 and [H + ] T calculations to relatively small errors in both C T and A T , CO 2 fugacity, as well as [H + ] T , calculated from C T and A T are very imprecise and render comparisons with direct measurements of little use. Consequently, precise calculations of f CO 2 require the use of direct pH T measurements.

AB - The NOAA Eq. Pac. CO 2 system data set (&simeq;2500 water samples) has been evaluated to assess the internal consistency of measurements and calculations involving CO 2 fugacity and pH T . This assessment represents the first large scale field comparison of pH T and f CO 2 data. Comparisons of direct discrete CO 2 fugacity ( f CO 2 ) measurements with CO 2 fugacity calculated from total inorganic carbon ( C T ), total alkalinity ( A T ) and spectrophotometric pH (pH T =−log[H + ] T ) indicate that a variety of improvements are needed in the parameter measurements and thermodynamic relationships used to relate f CO 2 , C T , A T and pH T in seawater. CO 2 fugacity calculated from C T and pH T or A T and pH T agree with direct measurements to no better than 1%. Comparisons of measured fugacity, f CO 2 (measured), and CO 2 fugacity calculated from C T and pH T , f CO 2 ( C T , pH T ), indicate that the precision of f CO 2 calculations is good relative to direct measurements. In contrast, due to the extreme sensitivity of f CO 2 and [H + ] T calculations to relatively small errors in both C T and A T , CO 2 fugacity, as well as [H + ] T , calculated from C T and A T are very imprecise and render comparisons with direct measurements of little use. Consequently, precise calculations of f CO 2 require the use of direct pH T measurements.

KW - Seawater

KW - Carbon dioxide

KW - Fugacity

KW - Spectrophotometric pH

KW - Measurements

KW - Thermodynamic calculations

UR - https://digitalcommons.usf.edu/msc_facpub/1717

UR - https://doi.org/10.1016/S0304-4203(97)00080-7

U2 - 10.1016/S0304-4203(97)00080-7

DO - 10.1016/S0304-4203(97)00080-7

M3 - Article

VL - 60

JO - Marine Chemistry

JF - Marine Chemistry

ER -

Discrete Water Column Measurements of COsub2/sub Fugacity and pHsubT/sub in Seawater: A Comparison of Direct Measurements and Thermodynamic Calculations

Abstract

Keywords

Disciplines

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