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Revisiting groundwater carbon fluxes to the ocean with implications for the carbon cycle

Shuang Zhang and Noah J. Planavsky
Revisiting groundwater carbon fluxes to the ocean with implications for the carbon cycle
Geology (Boulder) (November 2019) 48 (1): 67-71


Compared with riverine systems, the influence of groundwater on the global carbon cycle has remained underexplored. Here, we provide a new estimate of the bicarbonate fluxes from fresh groundwater to the ocean by coupling a statistical and hydrological analysis of groundwater and river samples across the contiguous United States with a study of global groundwater characteristics. We find that the mean HCO (sub 3) (super -) concentration ([HCO (sub 3) (super -) ]) in groundwaters exceeds that in surface rivers by a factor of 2-3 throughout the contiguous United States. Based on estimates of fresh groundwater discharge to the ocean and scaling up our estimated mean [HCO (sub 3) (super -) ] in groundwaters from the United States and around the world, we arrived at a mean global HCO (sub 3) (super -) flux from groundwaters ranging from 7.4X10 (super 12) (25th percentile)-1.8X10 (super 13) mol/yr (75th percentile) to 2.8X10 (super 13) -8.3X10 (super 13) mol/yr, which is 22%-237% of the global HCO (sub 3) (super -) flux from river systems, respectively. We also estimated that the global carbon flux derived from subsurface silicate weathering could be comparable to 32%-351% that from surficial silicate weathering, depending on groundwater discharge rates. Despite large uncertainties due to data limitation, this study highlights that groundwater weathering could be an important carbon sink in both the short- and long-term carbon cycle. Therefore, additional work on groundwaters is needed to develop a well-constrained view of the global carbon cycle.

ISSN: 0091-7613
EISSN: 1943-2682
Serial Title: Geology (Boulder)
Serial Volume: 48
Serial Issue: 1
Title: Revisiting groundwater carbon fluxes to the ocean with implications for the carbon cycle
Affiliation: Yale University, Department of Geology and Geophysics, New Haven, CT, United States
Pages: 67-71
Published: 20191113
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 37
Accession Number: 2020-000545
Categories: HydrochemistryHydrogeology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: GSA Data Repository item 2020019
Illustration Description: illus.
Secondary Affiliation: Carnegie Institution for Science, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2022, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 202001
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