Groundwater-Derived DIC and Carbonate Buffering Enhance Fluvial CO 2 Evasion in Two Australian Tropical Rivers

Clément Duvert, Mylène Bossa, Kyle J. Tyler, Jonathan G. Wynn, Niels C. Munksgaard, Michael I. Bird, Samantha A. Setterfield, Lindsay B. Hutley

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

Despite recent evidence suggesting that groundwater inputs of dissolved inorganic carbon (DIC) to rivers can contribute substantially to the fluvial evasion of carbon dioxide (CO 2 ), groundwater is seldom integrated into fluvial carbon budgets. Also, unclear is the way equilibria between CO 2 and ionic forms of carbonate will affect CO 2 evasion from rivers. We conducted longitudinal river surveys of radon and carbon along two rivers of tropical Australia and developed a mass balance framework to assess the influence of groundwater-derived inorganic carbon and carbonate buffering on CO 2 evasion rates. The mean CO 2 evasion flux totaled 8.5 and 2.3 g·C·m −2 ·day −1 for the two rivers, with considerable spatial variations that we attributed primarily to changes in groundwater inflow rates (minima and maxima per river reach 1.2–45.1 and 0.2–13.4 g·C·m −2 ·day −1 ). In the larger river system, inflowing groundwater delivered on average 6.7 g·C·m −2 ·day −1 as dissolved CO 2 —almost 10 times as much as the CO 2 produced via river metabolism—and 21.6 g·C·m −2 ·day −1 as ionic forms. In both rivers, these groundwater-derived inputs were a mixture of biogenic and geogenic carbon sources. Spatialized estimates of the carbonate buffering flux revealed that in reaches where CO 2 evasion was particularly high, the carbonate system was able to maintain high CO 2 concentrations by adjustment of carbonate equilibria. This process was likely triggered by high groundwater inflow rates. Our findings suggest that both groundwater inputs and carbonate equilibria need to be accounted for in fluvial carbon budgets, particularly in high-alkalinity rivers.

Original languageEnglish
Pages (from-to)312-327
Number of pages16
JournalJournal of Geophysical Research: Biogeosciences
Volume124
Issue number2
DOIs
Publication statusPublished - 1 Feb 2019

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Carbonates
dissolved inorganic carbon
Carbon Monoxide
ground water
buffering
rivers
carbonates
Groundwater
groundwater
Carbon
Rivers
carbonate
carbon
river
carbon budget
budgets
inflow
carbonate system
Fluxes
radon

Cite this

Duvert, C., Bossa, M., Tyler, K. J., Wynn, J. G., Munksgaard, N. C., Bird, M. I., ... Hutley, L. B. (2019). Groundwater-Derived DIC and Carbonate Buffering Enhance Fluvial CO 2 Evasion in Two Australian Tropical Rivers. Journal of Geophysical Research: Biogeosciences, 124(2), 312-327. https://doi.org/10.1029/2018JG004912
Duvert, Clément ; Bossa, Mylène ; Tyler, Kyle J. ; Wynn, Jonathan G. ; Munksgaard, Niels C. ; Bird, Michael I. ; Setterfield, Samantha A. ; Hutley, Lindsay B. / Groundwater-Derived DIC and Carbonate Buffering Enhance Fluvial CO 2 Evasion in Two Australian Tropical Rivers. In: Journal of Geophysical Research: Biogeosciences. 2019 ; Vol. 124, No. 2. pp. 312-327.
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Groundwater-Derived DIC and Carbonate Buffering Enhance Fluvial CO 2 Evasion in Two Australian Tropical Rivers. / Duvert, Clément; Bossa, Mylène; Tyler, Kyle J.; Wynn, Jonathan G.; Munksgaard, Niels C.; Bird, Michael I.; Setterfield, Samantha A.; Hutley, Lindsay B.

In: Journal of Geophysical Research: Biogeosciences, Vol. 124, No. 2, 01.02.2019, p. 312-327.

Research output: Contribution to journalArticle

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T1 - Groundwater-Derived DIC and Carbonate Buffering Enhance Fluvial CO 2 Evasion in Two Australian Tropical Rivers

AU - Duvert, Clément

AU - Bossa, Mylène

AU - Tyler, Kyle J.

AU - Wynn, Jonathan G.

AU - Munksgaard, Niels C.

AU - Bird, Michael I.

AU - Setterfield, Samantha A.

AU - Hutley, Lindsay B.

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AB - Despite recent evidence suggesting that groundwater inputs of dissolved inorganic carbon (DIC) to rivers can contribute substantially to the fluvial evasion of carbon dioxide (CO 2 ), groundwater is seldom integrated into fluvial carbon budgets. Also, unclear is the way equilibria between CO 2 and ionic forms of carbonate will affect CO 2 evasion from rivers. We conducted longitudinal river surveys of radon and carbon along two rivers of tropical Australia and developed a mass balance framework to assess the influence of groundwater-derived inorganic carbon and carbonate buffering on CO 2 evasion rates. The mean CO 2 evasion flux totaled 8.5 and 2.3 g·C·m −2 ·day −1 for the two rivers, with considerable spatial variations that we attributed primarily to changes in groundwater inflow rates (minima and maxima per river reach 1.2–45.1 and 0.2–13.4 g·C·m −2 ·day −1 ). In the larger river system, inflowing groundwater delivered on average 6.7 g·C·m −2 ·day −1 as dissolved CO 2 —almost 10 times as much as the CO 2 produced via river metabolism—and 21.6 g·C·m −2 ·day −1 as ionic forms. In both rivers, these groundwater-derived inputs were a mixture of biogenic and geogenic carbon sources. Spatialized estimates of the carbonate buffering flux revealed that in reaches where CO 2 evasion was particularly high, the carbonate system was able to maintain high CO 2 concentrations by adjustment of carbonate equilibria. This process was likely triggered by high groundwater inflow rates. Our findings suggest that both groundwater inputs and carbonate equilibria need to be accounted for in fluvial carbon budgets, particularly in high-alkalinity rivers.

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U2 - 10.1029/2018JG004912

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ER -