Challenges in quantifying air-water carbon dioxide flux using estuarine water quality data: Case study for Chesapeake Bay

Maria Herrmann; Raymond G. Najjar; Fei Da; Jaclyn R. Friedman; Marjorie A. M. Friedrichs; Sreece Goldberger; Alana Menendez; Elizabeth H. Shadwick; Edward G. Stets; Pierre St-Laurent

doi:10.1029/2019JC015610

Challenges in quantifying air-water carbon dioxide flux using estuarine water quality data: Case study for Chesapeake Bay

JGR Oceans

By: Maria Herrmann, Raymond G. Najjar, Fei Da, Jaclyn R. Friedman, Marjorie A. M. Friedrichs, Sreece Goldberger, Alana Menendez, Elizabeth H. Shadwick, Edward G. Stets, and Pierre St-Laurent

https://doi.org/10.1029/2019JC015610

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Abstract

Estuaries play an uncertain but potentially important role in the global carbon cycle via CO₂ outgassing. The uncertainty mainly stems from the paucity of studies that document the full spatial and temporal variability of estuarine surface water partial pressure of carbon dioxide ( pCO₂). Here, we explore the potential of utilizing the abundance of pH data from historical water quality monitoring programs to fill the data void via a case study of the mainstem Chesapeake Bay (eastern United States). We calculate pCO₂ and the air-water CO₂ flux at monthly resolution from 1998 to 2018 from tidal fresh to polyhaline waters, paying special attention to the error estimation. The biggest error is due to the pH measurement error, and errors due to the gas transfer velocity, temporal sampling, the alkalinity mixing model, and the organic alkalinity estimation are 72%, 27%, 15%, and 5%, respectively, of the error due to pH. Seasonal, interannual, and spatial variability in the air-water flux and surface pCO₂ is high, and a correlation analysis with oxygen reveals that this variability is driven largely by biological processes. Averaged over 1998–2018, the mainstem bay is a weak net source of CO₂ to the atmosphere of 1.2 (1.1, 1.4) mol m⁻² yr⁻¹ (best estimate and 95% confidence interval). Our findings suggest that the abundance of historical pH measurements in estuaries around the globe should be mined in order to constrain the large spatial and temporal variability of the CO₂ exchange between estuaries and the atmosphere.

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Additional publication details
Publication type	Article
Publication Subtype	Journal Article
Title	Challenges in quantifying air-water carbon dioxide flux using estuarine water quality data: Case study for Chesapeake Bay
Series title	JGR Oceans
DOI	10.1029/2019JC015610
Volume	125
Issue	7
Year Published	2020
Language	English
Publisher	American Geophysical Union
Contributing office(s)	WMA - Earth System Processes Division
Description	e2019JC015610, 19 p.
Country	United States
State	Maryland, Virginia
Other Geospatial	Chesapeake Bay
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