Atmos. Chem. Phys. Discuss., 11, 14583-14605, 2011
www.atmos-chem-phys-discuss.net/11/14583/2011/
doi:10.5194/acpd-11-14583-2011
© Author(s) 2011. This work is distributed
under the Creative Commons Attribution 3.0 License.
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Continental-scale enrichment of atmospheric 14CO2 from the nuclear power industry: potential impact on the estimation of fossil fuel-derived CO2
H. D. Graven1,* and N. Gruber1
1Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich, Universitätstrasse 16, 8092 Zurich, Switzerland
*now at: Scripps Institution of Oceanography, University of California-San Diego,\newline 9500 Gilman Dr., La Jolla, CA 92093-0244, USA

Abstract. Since aged carbon in fossil fuel contains no 14C, 14C/C ratios (Δ14C) measured in atmospheric CO2 can be used to estimate CO2 added by combustion and, potentially, provide verification of fossil CO2 emissions calculated using economic inventories. Sources of 14C from nuclear power generation and spent fuel reprocessing can counteract dilution by fossil CO2. Therefore, these nuclear sources can bias observation-based estimates of fossil fuel-derived CO2 if they are not correctly accounted for or included as a source of uncertainty. We estimate annual 14C emissions from each nuclear site in the world and conduct an Eulerian transport modeling study to investigate the continental-scale, steady-state gradients of Δ14C caused by nuclear activities and fossil fuel combustion. Over Europe, North America and East Asia, nuclear enrichment may offset 0–260 % of the fossil fuel dilution in Δ14C, corresponding to potential biases of 0 to −8 ppm in the CO2 attributed to fossil fuel emissions, larger than the bias from respiration in some areas. Growth of 14C emissions increased the potential nuclear bias over 1985–2005. The magnitude of this potential bias is largely independent of the choice of reference station in the context of Eulerian transport and inversion studies, but could potentially be reduced by an appropriate choice of reference station in the context of local-scale assessments.

Citation: Graven, H. D. and Gruber, N.: Continental-scale enrichment of atmospheric 14CO2 from the nuclear power industry: potential impact on the estimation of fossil fuel-derived CO2, Atmos. Chem. Phys. Discuss., 11, 14583-14605, doi:10.5194/acpd-11-14583-2011, 2011.
 
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