Groundwater‐Derived DIC and Carbonate Buffering Enhance Fluvial CO2 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 journalArticleResearchpeer-review

12 Downloads (Pure)

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 (CO2), groundwater is seldom integrated into fluvial carbon budgets. Also, unclear is the way equilibria between CO2 and ionic forms of carbonate will affect CO2 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 CO2 evasion rates. The mean CO2 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 CO2—almost 10 times as much as the CO2 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 CO2 evasion was particularly high, the carbonate system was able to maintain high CO2 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
Early online date29 Jan 2019
DOIs
Publication statusPublished - Feb 2019

Fingerprint

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

Cite this

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 CO2 Evasion in Two Australian Tropical Rivers. In: Journal of Geophysical Research: Biogeosciences. 2019 ; Vol. 124, No. 2. pp. 312-327.
@article{a884a640b6b84689b6934ea6ad4764e3,
title = "Groundwater‐Derived DIC and Carbonate Buffering Enhance Fluvial CO2 Evasion in Two Australian Tropical Rivers",
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 (CO2), groundwater is seldom integrated into fluvial carbon budgets. Also, unclear is the way equilibria between CO2 and ionic forms of carbonate will affect CO2 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 CO2 evasion rates. The mean CO2 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 CO2—almost 10 times as much as the CO2 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 CO2 evasion was particularly high, the carbonate system was able to maintain high CO2 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.",
author = "Cl{\'e}ment Duvert and Myl{\`e}ne Bossa and Tyler, {Kyle J.} and Wynn, {Jonathan G.} and Munksgaard, {Niels C.} and Bird, {Michael I.} and Setterfield, {Samantha A.} and Hutley, {Lindsay B.}",
year = "2019",
month = "2",
doi = "10.1029/2018JG004912",
language = "English",
volume = "124",
pages = "312--327",
journal = "Journal of Geophysical Research: Biogeosciences",
issn = "2169-8961",
publisher = "Wiley-Blackwell",
number = "2",

}

Groundwater‐Derived DIC and Carbonate Buffering Enhance Fluvial CO2 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, 02.2019, p. 312-327.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Groundwater‐Derived DIC and Carbonate Buffering Enhance Fluvial CO2 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.

PY - 2019/2

Y1 - 2019/2

N2 - Despite recent evidence suggesting that groundwater inputs of dissolved inorganic carbon (DIC) to rivers can contribute substantially to the fluvial evasion of carbon dioxide (CO2), groundwater is seldom integrated into fluvial carbon budgets. Also, unclear is the way equilibria between CO2 and ionic forms of carbonate will affect CO2 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 CO2 evasion rates. The mean CO2 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 CO2—almost 10 times as much as the CO2 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 CO2 evasion was particularly high, the carbonate system was able to maintain high CO2 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.

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 (CO2), groundwater is seldom integrated into fluvial carbon budgets. Also, unclear is the way equilibria between CO2 and ionic forms of carbonate will affect CO2 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 CO2 evasion rates. The mean CO2 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 CO2—almost 10 times as much as the CO2 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 CO2 evasion was particularly high, the carbonate system was able to maintain high CO2 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.

UR - http://www.scopus.com/inward/record.url?scp=85061909993&partnerID=8YFLogxK

U2 - 10.1029/2018JG004912

DO - 10.1029/2018JG004912

M3 - Article

VL - 124

SP - 312

EP - 327

JO - Journal of Geophysical Research: Biogeosciences

JF - Journal of Geophysical Research: Biogeosciences

SN - 2169-8961

IS - 2

ER -