Reconciling Negative Soil CO2 Fluxes: Insights from a Large-Scale Experimental Hillslope
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Final Published Version
Affiliation
Univ Arizona, Biosphere 2Univ Arizona, Honors Coll
Univ Arizona, Dept Hydrol & Atmospher Sci
Univ Arizona, Sch Nat Resources & Environm
Issue Date
2019-01-13Keywords
net soil exchangebiosphere 2
carbonate weathering
negative emission technology
microbial induced carbonate precipitation
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MDPICitation
Cueva, A.; Volkmann, T.H.M.; van Haren, J.; Troch, P.A.; Meredith, L.K. Reconciling Negative Soil CO2 Fluxes: Insights from a Large-Scale Experimental Hillslope. Soil Syst. 2019, 3, 10.Journal
SOIL SYSTEMSRights
Copyright © 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).Collection Information
This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.Abstract
Soil fluxes of CO2 (F-s) have long been considered unidirectional, reflecting the predominant roles of metabolic activity by microbes and roots in ecosystem carbon cycling. Nonetheless, there is a growing body of evidence that non-biological processes in soils can outcompete biological ones, pivoting soils from a net source to sink of CO2, as evident mainly in hot and cold deserts with alkaline soils. Widespread reporting of unidirectional fluxes may lead to misrepresentation of F-s in process-based models and lead to errors in estimates of local to global carbon balances. In this study, we investigate the variability and environmental controls of F-s in a large-scale, vegetation-free, and highly instrumented hillslope located within the Biosphere 2 facility, where the main carbon sink is driven by carbonate weathering. We found that the hillslope soils were persistent sinks of CO2 comparable to natural desert shrublands, with an average rate of -0.15 +/- 0.06 mu mol CO2 m(2) s(-1) and annual sink of -56.8 +/- 22.7 g C m(-2) y(-1). Furthermore, higher uptake rates (more negative F-s) were observed at night, coinciding with strong soil-air temperature gradients and [CO2] inversions in the soil profile, consistent with carbonate weathering. Our results confirm previous studies that reported negative values of F-s in hot and cold deserts around the globe and suggest that negative F-s are more common than previously assumed. This is particularly important as negative F-s may occur widely in arid and semiarid ecosystems, which play a dominant role in the interannual variability of the terrestrial carbon cycle. This study contributes to the growing recognition of the prevalence of negative F-s as an important yet, often overlooked component of ecosystem C cycling.Note
Open access journalISSN
2571-8789Version
Final published versionSponsors
Philecology Foundation of Fort Worth, Texas; Research, Development and Innovation office of the Vice President for Research at the University of Arizonaae974a485f413a2113503eed53cd6c53
10.3390/soilsystems3010010