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dc.contributor.author
Lupker, Maarten
dc.contributor.author
France-Lanord, Christian
dc.contributor.author
Lartiges, Bruno
dc.date.accessioned
2019-05-16T13:45:36Z
dc.date.available
2017-06-12T11:14:56Z
dc.date.available
2019-05-16T13:45:36Z
dc.date.issued
2016-08-12
dc.identifier.other
10.5194/esurf-4-675-2016
en_US
dc.identifier.uri
http://hdl.handle.net/20.500.11850/119685
dc.identifier.doi
10.3929/ethz-b-000119685
dc.description.abstract
Continental-scale chemical weathering budgets are commonly assessed based on the flux of dissolved elements carried by large rivers to the oceans. However, the interaction between sediments and seawater in estuaries can lead to additional cation exchange fluxes that have been very poorly constrained so far. We constrained the magnitude of cation exchange fluxes from the Ganga–Brahmaputra river system based on cation exchange capacity (CEC) measurements of riverine sediments. CEC values of sediments are variable throughout the river water column as a result of hydrological sorting of minerals with depth that control grain sizes and surface area. The average CEC of the integrated sediment load of the Ganga–Brahmaputra is estimated ca. 6.5meq100g−1. The cationic charge of sediments in the river is dominated by bivalent ions Ca2+ (76%) and Mg2+ (16%) followed by monovalent K+ (6%) and Na+ (2%), and the relative proportion of these ions is constant among all samples and both rivers. Assuming a total exchange of exchangeable Ca2+ for marine Na+ yields a maximal additional Ca2+ flux of 28 × 109molyr−1 of calcium to the ocean, which represents an increase of ca. 6% of the actual river dissolved Ca2+ flux. In the more likely event that only a fraction of the adsorbed riverine Ca2+ is exchanged, not only for marine Na+ but also Mg2+ and K+, estuarine cation exchange for the Ganga–Brahmaputra is responsible for an additional Ca2+ flux of 23 × 109molyr−1, while ca. 27 × 109molyr−1 of Na+, 8 × 109molyr−1 of Mg2+ and 4 × 109molyr−1 of K+ are re-absorbed in the estuaries. This represents an additional riverine Ca2+ flux to the ocean of 5% compared to the measured dissolved flux. About 15% of the dissolved Na+ flux, 8% of the dissolved K+ flux and 4% of the Mg2+ are reabsorbed by the sediments in the estuaries. The impact of estuarine sediment–seawater cation exchange appears to be limited when evaluated in the context of the long-term carbon cycle and its main effect is the sequestration of a significant fraction of the riverine Na flux to the oceans. The limited exchange fluxes of the Ganga–Brahmaputra relate to the lower than average CEC of its sediment load that do not counterbalance the high sediment flux to the oceans. This can be attributed to the nature of Himalayan river sediment such as low proportion of clays and organic matter.
en_US
dc.format
application/pdf
en_US
dc.language.iso
en
en_US
dc.publisher
Copernicus
en_US
dc.rights.uri
http://creativecommons.org/licenses/by/3.0/
dc.title
Impact of sediment–seawater cation exchange on Himalayan chemical weathering fluxes
en_US
dc.type
Journal Article
dc.rights.license
Creative Commons Attribution 3.0 Unported
ethz.journal.title
Earth Surface Dynamics
ethz.journal.volume
4
en_US
ethz.journal.issue
3
en_US
ethz.pages.start
675
en_US
ethz.pages.end
684
en_US
ethz.size
10 p.
en_US
ethz.version.deposit
publishedVersion
en_US
ethz.identifier.wos
ethz.identifier.scopus
ethz.publication.place
Göttingen
en_US
ethz.publication.status
published
en_US
ethz.leitzahl
ETH Zürich::00002 - ETH Zürich::00012 - Lehre und Forschung::00007 - Departemente::02330 - Dep. Erdwissenschaften / Dep. of Earth Sciences::02704 - Geologisches Institut / Geological Institute::03868 - Eglinton, Timothy I. / Eglinton, Timothy I.
en_US
ethz.leitzahl.certified
ETH Zürich::00002 - ETH Zürich::00012 - Lehre und Forschung::00007 - Departemente::02330 - Dep. Erdwissenschaften / Dep. of Earth Sciences::02704 - Geologisches Institut / Geological Institute::03868 - Eglinton, Timothy I. / Eglinton, Timothy I.
ethz.date.deposited
2017-06-12T11:15:32Z
ethz.source
ECIT
ethz.identifier.importid
imp593654a641e9127071
ethz.ecitpid
pub:181710
ethz.eth
yes
en_US
ethz.availability
Open access
en_US
ethz.rosetta.installDate
2017-07-12T10:55:43Z
ethz.rosetta.lastUpdated
2019-05-16T13:45:46Z
ethz.rosetta.exportRequired
true
ethz.rosetta.versionExported
true
ethz.COinS
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