The Experimental Flow to the Colorado River Delta: Effects on Carbon Mobilization in a Dry Watercourse

Authors

Thomas S. Bianchi, University of Florida
David Butman, University of Washington
Peter A. Raymond, Yale University
Nicholas D. Ward, University of Florida
Rory J. Kates, University of Florida
Karl W. Flessa, Marine Sciences Laboratory, Pacific Northwest National Laboratory, Sequim, Washington
Hector Zamora, Marine Sciences Laboratory, Pacific Northwest National Laboratory, Sequim, Washington
Ana Arellano, University of FloridaFollow
Jorge Ramirez, University of Arizona
Eliana Rodriguez, University of Arizona

Document Type

Article

Publication Date

3-2017

Keywords

dry watercourse, carbon cycling, mobilization, flooding, greenhouse gases, Colorado River

Digital Object Identifier (DOI)

https://doi.org/10.1002/2016JG003555

Abstract

Here we report on the effects of an experimental flood on the carbon cycling dynamics in the dry watercourse of the Colorado River in Mexico. We observed post-flood differences in the degree of decay, age, and concentration of dissolved organic carbon (DOC), as well as dissolved CH₄ and CO₂ concentrations throughout the study site. Our results indicate that this flooded waterway was a limited source of CH₄ and CO₂ to the atmosphere during the event and that DOC age increased with time of flooding. Based on our findings, we suggest that the interplay between storage and mobilization of carbon and greenhouse gases in arid and semiarid regions is potentially sensitive to changing climate conditions, particularly hydrologic variability. Changes in the radiocarbon age of DOC throughout the flooding event suggest that organic matter (OM) that had been stored for long periods (e.g., millennial) was mobilized by the flooding event along with CO₂. The OM residing in the dry riverbed that was mobilized into floodwaters had a signature reflective of degraded vascular plant OM and microbial biomass. Whether this microbial OM was living or dead, our findings support previous work in soils and natural waters showing that microbial OM can remain stable and stored in ecosystems for long time periods. As human appropriation of water resources continues to increase, the episodic drying and rewetting of once natural riverbeds and deltas may fundamentally alter the processing and storage of carbon in such systems.

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Terms of use for work posted in Scholar Commons.

Was this content written or created while at USF?

No

Citation / Publisher Attribution

Journal of Geophysical Research: Biogeosciences, v. 122, issue 3, p. 607-627

©2017. American Geophysical Union. All Rights Reserved.

Scholar Commons Citation

Bianchi, Thomas S.; Butman, David; Raymond, Peter A.; Ward, Nicholas D.; Kates, Rory J.; Flessa, Karl W.; Zamora, Hector; Arellano, Ana; Ramirez, Jorge; and Rodriguez, Eliana, "The Experimental Flow to the Colorado River Delta: Effects on Carbon Mobilization in a Dry Watercourse" (2017). Marine Science Faculty Publications. 1439.
https://digitalcommons.usf.edu/msc_facpub/1439