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Glacial weathering, sulfide oxidation, and global carbon cycle feedbacks

Torres, Mark A. and Moosdorf, Nils and Hartmann, Jens and Adkins, Jess F. and West, A. Joshua (2017) Glacial weathering, sulfide oxidation, and global carbon cycle feedbacks. Proceedings of the National Academy of Sciences of the United States of America, 114 (33). pp. 8716-8721. ISSN 0027-8424. PMCID PMC5565423. https://resolver.caltech.edu/CaltechAUTHORS:20170807-091321702

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Abstract

Connections between glaciation, chemical weathering, and the global carbon cycle could steer the evolution of global climate over geologic time, but even the directionality of feedbacks in this system remain to be resolved. Here, we assemble a compilation of hydrochemical data from glacierized catchments, use this data to evaluate the dominant chemical reactions associated with glacial weathering, and explore the implications for long-term geochemical cycles. Weathering yields from catchments in our compilation are higher than the global average, which results, in part, from higher runoff in glaciated catchments. Our analysis supports the theory that glacial weathering is characterized predominantly by weathering of trace sulfide and carbonate minerals. To evaluate the effects of glacial weathering on atmospheric pCO_2, we use a solute mixing model to predict the ratio of alkalinity to dissolved inorganic carbon (DIC) generated by weathering reactions. Compared with nonglacial weathering, glacial weathering is more likely to yield alkalinity/DIC ratios less than 1, suggesting that enhanced sulfide oxidation as a result of glaciation may act as a source of CO_2 to the atmosphere. Back-of-the-envelope calculations indicate that oxidative fluxes could change ocean–atmosphere CO_2 equilibrium by 25 ppm or more over 10 ky. Over longer timescales, CO_2 release could act as a negative feedback, limiting progress of glaciation, dependent on lithology and the concentration of atmospheric O_2. Future work on glaciation–weathering–carbon cycle feedbacks should consider weathering of trace sulfide minerals in addition to silicate minerals.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1073/pnas.1702953114DOIArticle
http://www.pnas.org/content/114/33/8716PublisherArticle
http://www.pnas.org/lookup/suppl/doi:10.1073/pnas.1702953114/-/DCSupplementalPublisherSupporting Information
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5565423/PubMed CentralArticle
ORCID:
AuthorORCID
Torres, Mark A.0000-0002-9599-2748
West, A. Joshua0000-0001-6909-1471
Additional Information:© 2017 National Academy of Sciences. Edited by Thure E. Cerling, University of Utah, Salt Lake City, UT, and approved July 5, 2017 (received for review February 21, 2017). Published online before print July 31, 2017. We thank three reviewers for constructive comments. M.A.T. was supported by a University of Southern California College Merit Fellowship and a Caltech Texaco Postdoctoral Fellowship, N.M. by a Deutscher Akademischer Austauschdienst exchange fellowship, J.H. by the German Science Foundation (DFG-project HA4472/6-1 and the Cluster of Excellence “CliSAP,” EXC177, Universität Hamburg) and Bundesministerium für Bildung und Forschung Project PALMOD (Ref 01LP1506C), and A.J.W. by National Science Foundation Grant EAR-1455352. Requests for access to the GloRiCh database should be addressed to J. Hartmann at geo@hattes.de. Author contributions: N.M., J.H., and A.J.W. designed research; M.A.T., N.M., and J.H. performed research; M.A.T. and J.F.A. contributed new reagents/analytic tools; M.A.T., N.M., J.H., J.F.A., and A.J.W. analyzed data; and M.A.T. and A.J.W. wrote the paper. The authors declare no conflict of interest. This article is a PNAS Direct Submission. This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1702953114/-/DCSupplemental.
Funders:
Funding AgencyGrant Number
University of Southern CaliforniaUNSPECIFIED
Caltech Texaco Postdoctoral FellowshipUNSPECIFIED
Deutscher Akademischer Austauschdienst (DAAD)UNSPECIFIED
Deutsche Forschungsgemeinschaft (DFG)HA4472/6-1
Universität HamburgEXC177
Bundesministerium für Bildung und Forschung (BMBF)01LP1506C
NSFEAR-1455352
Subject Keywords:weathering; carbon cycle; glaciation; oxidation; sulfide
Issue or Number:33
PubMed Central ID:PMC5565423
Record Number:CaltechAUTHORS:20170807-091321702
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20170807-091321702
Official Citation:Mark A. Torres, Nils Moosdorf, Jens Hartmann, Jess F. Adkins, and A. Joshua West Glacial weathering, sulfide oxidation, and global carbon cycle feedbacks PNAS 2017 114 (33) 8716-8721; published ahead of print July 31, 2017, doi:10.1073/pnas.1702953114
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:79839
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:07 Aug 2017 17:02
Last Modified:03 Oct 2019 18:24

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