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Earth System Science Data The Data Publishing Journal
https://doi.org/10.5194/essd-2018-29
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
 
19 Apr 2018
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Earth System Science Data (ESSD).
Radiocarbon Measurements of Ecosystem Respiration and Soil Pore-Space CO2 in Utqiaġvik (Barrow), Alaska
Lydia J. S. Vaughn1,2 and Margaret S. Torn2,3 1Integrative Biology, University of California, Berkeley, Berkeley, CA, 94720, USA
2Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
3Energy and Resources Group, University of California, Berkeley, Berkeley, CA, 94720, USA
Abstract. Radiocarbon measurements of ecosystem respiration and soil pore space CO2 are useful for determining the sources of ecosystem respiration, identifying environmental controls on soil carbon cycling rates, and parameterizing and evaluating models. We measured flux rates and radiocarbon contents of ecosystem respiration, as well as radiocarbon in soil profile CO2 in Utqiaġvik (Barrow), Alaska, during the summers of 2012, 2013, and 2014. We found that radiocarbon in ecosystem respiration ranged from +60.5 to −160 ‰ with a median value of +23.3 ‰. Ecosystem respiration became more depleted in radiocarbon from summer to autumn, indicating increased decomposition of old soil organic carbon and/or decreased CO2 production from fast-cycling carbon pools. Across permafrost features, ecosystem respiration from high-centered polygons was depleted in radiocarbon relative to other polygon types. Radiocarbon content in soil pore-space CO2 varied between −7.1 and −280 ‰, becoming more negative with depth in individual soil profiles. These pore-space radiocarbon values correspond to CO2 mean ages of 410 to 3350 years, based on a steady-state, one-pool model. Together, these data indicate that soil respiration is derived primarily from old, slow-cycling carbon pools, but that total CO2 fluxes depend largely on autotrophic respiration and heterotrophic decomposition of fast-cycling carbon within the shallowest soil layers. The relative contributions of these different CO2 sources are highly variable across microtopographic features and time in the sampling season. The highly negative Δ14C values in soil pore-space CO2 and autumn ecosystem respiration indicate that when it is not frozen, very old soil carbon is vulnerable to decomposition. Radiocarbon data and associated CO2 flux and temperature data are stored in the data repository of the Next Generation Ecosystem Experiments (NGEE-Arctic) at http://dx.doi.org/10.5440/1364062.
Citation: Vaughn, L. J. S. and Torn, M. S.: Radiocarbon Measurements of Ecosystem Respiration and Soil Pore-Space CO2 in Utqiaġvik (Barrow), Alaska, Earth Syst. Sci. Data Discuss., https://doi.org/10.5194/essd-2018-29, in review, 2018.
Lydia J. S. Vaughn and Margaret S. Torn
Lydia J. S. Vaughn and Margaret S. Torn

Data sets

Radiocarbon in Ecosystem Respiration and Soil Pore-Space CO2 with Surface Gas Flux, Air Temperature, and Soil Temperature and Moisture, Barrow, Alaska, 2012-2014 L. J. S. Vaughn, M. S. Torn, R. C. Porras, J. B. Curtis, and O. Chafe https://doi.org/10.5440/1364062
Lydia J. S. Vaughn and Margaret S. Torn

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This paper discusses radiocarbon in CO2 from Arctic Alaska. From soil chamber measurements, we observed strong seasonal and spatial patterns in 14C of ecosystem respiration, which declined throughout the summer and differed among permafrost features. Radiocarbon in pore-space CO2 indicated decomposition of carbon as old as 3,000 years near the permafrost table. Together, these data reveal different rates of old carbon decomposition from distinct permafrost features.
This paper discusses radiocarbon in CO2 from Arctic Alaska. From soil chamber measurements, we...
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