CaltechAUTHORS
  A Caltech Library Service

Long-term storage and age‐biased export of fluvial organic carbon: field evidence from West Iceland

Torres, Mark A. and Kemeny, Preston C. and Lamb, Michael P. and Cole, Trevor L. and Fischer, Woodward W. (2020) Long-term storage and age‐biased export of fluvial organic carbon: field evidence from West Iceland. Geochemistry, Geophysics, Geosystems, 21 (4). Art. No. e2019GC008632. ISSN 1525-2027. https://resolver.caltech.edu/CaltechAUTHORS:20200317-150608382

[img] PDF - Published Version
See Usage Policy.

41Mb
[img] PDF - Supplemental Material
See Usage Policy.

59Mb
[img] Archive (ZIP) (Data Set SI) - Supplemental Material
See Usage Policy.

888Kb
[img] PDF (Figure S1) - Supplemental Material
See Usage Policy.

16Kb
[img] PDF (Figure S2) - Supplemental Material
See Usage Policy.

33Mb
[img] PDF (Figure S3) - Supplemental Material
See Usage Policy.

43Kb
[img] Image (PNG) (Figure S4) - Supplemental Material
See Usage Policy.

15Mb
[img] PDF (Figure S5) - Supplemental Material
See Usage Policy.

2724Kb

Use this Persistent URL to link to this item: https://resolver.caltech.edu/CaltechAUTHORS:20200317-150608382

Abstract

Terrestrial organic carbon (OC) plays an important role in the carbon cycle, but questions remain regarding the controls and timescale(s) over which atmospheric CO₂ remains sequestered as particulate OC (POC). Motivated by observations that terrestrial POC is physically stored within soils and other shallow sedimentary deposits, we examined the role that sediment storage plays in the terrestrial OC cycle. Specifically, we tested the hypothesis that sediment storage impacts the age of terrestrial POC. We focused on the Efri Haukadalsá River catchment in Iceland as it lacks ancient sedimentary bedrock that would otherwise bias radiocarbon‐based determinations of POC storage duration by supplying pre‐aged “petrogenic” POC. Our radiocarbon measurements of riverine suspended sediments and deposits implicated millennial‐scale storage times. Comparison between the sample types (suspended and deposits) suggested an age offset between transported (suspended sediments) and stored (deposits) POC at the time of sampling, which is predicted by theory for the sediment age distribution in floodplains. We also observed that POC in suspended sediments is younger than the predicted mean storage duration generated from independent geomorphological data, which suggested an additional role for OC cycling. Consistent with this, we observed interparticle heterogeneity in the composition of POC by imaging our samples at the microscale using X‐ray absorption spectroscopy. Specifically, we found that particles within individual samples differed in their sulfur oxidation state, which is indicative of multiple origins and/or diagenetic histories. Altogether, our results support recent coupled sediment storage and OC cycling models and indicate that the physical drivers of sediment storage are important factors controlling the cadence of carbon cycling.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1029/2019gc008632DOIArticle
https://doi.org/10.1594/PANGAEA.911027Related ItemData
https://doi.org/10.5281/zenodo.3688815Related ItemCode
ORCID:
AuthorORCID
Torres, Mark A.0000-0002-9599-2748
Kemeny, Preston C.0000-0003-1693-4142
Lamb, Michael P.0000-0002-5701-0504
Fischer, Woodward W.0000-0002-8836-3054
Additional Information:© 2020 American Geophysical Union. Received 23 AUG 2019; Accepted 14 DEC 2019; Accepted article online 15MAR 2020. This work was supported by a grant from the Caltech Discovery Fund to W. W. F. and M. P. L. and Caltech CEMI (W. W. F.). M. A. T. acknowledges support from the Caltech Texaco Postdoctoral Fellowship and the California Alliance for Graduate Education & The Professoriate. P. C. K. acknowledges support from the Fannie and John Hertz Foundation, Cohan/Jacobs and Stein Families Fellowship, and the DoD, Air Force Office of Scientific Research, National Defense Science and Engineering Graduate (NDSEG) Fellowship, 32 CFR 168a. Portions of this research were carried out at the Stanford Synchrotron Radiation Lightsource, a Directorate of SLAC National Accelerator Laboratory and an Office of Science User Facility operated for the US Department of Energy Office of Science by Stanford University. We acknowledge DEMs provided by the Polar Geospatial Center under NSF OPP Awards 1043681, 1559691, and 1542736. All authors thank Dr. A. Joshua West for the loaning of equipment, as well as Dr. S. Webb for assistance at SLAC beamline 14‐3. The use of the EPMA facility at the Department of Earth Science, Rice University, Houston, TX, is kindly acknowledged along with the assistance of Dr. Gelu Costin. The geochemical data produced as part of this study are available online (at doi.org/10.1594/PANGAEA.911027). The data analysis codes are available online (at github.com/torres-lab) and archived (at https://doi.org/10.5281/zenodo.3688815).
Group:Caltech Center for Environmental Microbial Interactions (CEMI)
Funders:
Funding AgencyGrant Number
Caltech Discovery FundUNSPECIFIED
Caltech Center for Environmental Microbial Interactions (CEMI)UNSPECIFIED
Caltech Texaco Postdoctoral FellowshipUNSPECIFIED
California Alliance for Graduate Education and the ProfessoriateUNSPECIFIED
Fannie and John Hertz FoundationUNSPECIFIED
Cohan/Jacobs and Stein Families FellowshipUNSPECIFIED
Air Force Office of Scientific Research (AFOSR)UNSPECIFIED
National Defense Science and Engineering Graduate (NDSEG) Fellowship32 CFR 168a
NSFOPP-1043681
NSFOPP-1559691
NSFOPP-1542736
Subject Keywords:organic carbon; floodplains; sediment transport; rivers; carbon cycle; geomorphology
Issue or Number:4
Record Number:CaltechAUTHORS:20200317-150608382
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20200317-150608382
Official Citation:Torres, M. A., Kemeny, P. C., Lamb, M. P., Cole, T. L., & Fischer, W. W. (2020). Long‐term storage and age‐biased export of fluvial organic carbon: Field evidence from West Iceland. Geochemistry, Geophysics, Geosystems, 21, e2019GC008632. https://doi.org/10.1029/2019GC008632
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:101949
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:17 Mar 2020 22:52
Last Modified:05 Oct 2020 16:19

Repository Staff Only: item control page