Challenges in Quantifying Air‐Water Carbon Dioxide Flux Using Estuarine Water Quality Data: Case Study for Chesapeake Bay

Authors

Marie Herrmann
Raymond G. Najjar
Fei Da, Virginia Institute of Marine ScienceFollow
Marjorie A.M. Friedrichs, Virginia Institute of Marine ScienceFollow
Sreece Goldberger
Alana Menendez
Elizabeth Shadwick
Pierre St-Laurent, Virginia Institute of Marine ScienceFollow

Document Type

Article

Department/Program

Virginia Institute of Marine Science

Publication Date

7-2020

Journal

Journal of Geophysical Research: Oceans

Volume

125

Issue

7

First Page

e2019JC015610

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 ( p CO₂). 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 p CO₂ 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 p CO₂ 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.

DOI

doi: 10.1029/2019JC015610

Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 International License.

Recommended Citation

Herrmann, Marie; Najjar, Raymond G.; Da, Fei; Friedrichs, Marjorie A.M.; Goldberger, Sreece; Menendez, Alana; Shadwick, Elizabeth; and St-Laurent, Pierre, Challenges in Quantifying Air‐Water Carbon Dioxide Flux Using Estuarine Water Quality Data: Case Study for Chesapeake Bay (2020). Journal of Geophysical Research: Oceans, 125(7), e2019JC015610.

doi: 10.1029/2019JC015610