Radiocarbon in Atmospheric Carbon Dioxide and Methane: Global Distribution and Trends

Levin, Ingeborg; Bösinger, Rainer; Bonani, Georges; Francey, R. J.; Kromer, Bernd; Münnich, K. O.; Suter, M.; Trivett, N. B. A.; Wölfli, W.

doi:10.1007/978-1-4757-4249-7_31

Cited by 77 publications

(74 citation statements)

References 14 publications

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“…The amplitudes of these activity fluctuations are usually < 2% [79], With the beginning of the nuclear age, anthropogenic l4 C was introduced into the atmosphere. In the years 1962/63 with maximum overground testing of thermonuclear weapons, the 14 C activity concentration in the northern hemisphere increased by nearly a factor of two [80]. In the southern hemisphere the increase was much smaller [81].…”

Section: Atmospheric Activity Concentration Of Tritiummentioning

confidence: 97%

Radioactivity in the Atmosphere

Gäggeler

1995

Radiochimica Acta

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A short review is made on atmospheric radionuclides with emphasis on their activity concentrations in the troposphere, mostly for surface air over Europe. Discussed are those species which have activity concentrations above about 1 mBq/m 3 . For this atmospheric layer highest average activity concentrations (> 1 Bq/m 3 ) have i) 222 Rn ("radon") and its short-lived decay products, (ii) 220 Rn ("thoron"), however, only for the lowest meter above ground, and iii) a5 Kr. In the range 1 mBq/m 1 to 1 Bq/m 3 are Τ(Ή), ,4 C, 37 Ar and 7 Be as well as the "thoron" decay product 212 Pb. Average activity concentrations slightly below 1 mBq/m 3 has 210 Pb, the only long-lived decay product of "radon". The sources of these radionuclides are discussed. Not included in this review are radionuclides contained in the atmosphere at very low activity concentrations or from single emissions such as e.g. from the Tschernobyl accident in 1986.

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Section: Atmospheric Activity Concentration Of Tritiummentioning

confidence: 97%

Radioactivity in the Atmosphere

Gäggeler

1995

Radiochimica Acta

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“…First, the ability to reliably disentangle and attribute fossil fuel (vs. natural) sources of CO 2 by limited quantities of 14 C-CO 2 (the even rarer 14 C-CH 4 can be used insofar only for a global constraint of fossil CH 4 emissions (Lassey et al, 2007), and 14 C-CH 4 is contaminated by nuclear power plants emissions (Levin et al, 1992)) atmospheric measurements and the lack of systematic application of combustion tracers (e.g. CO and NO 2 ) to separate fossil fuel CO 2 .…”

Section: Atmospheric Datamentioning

confidence: 99%

Current systematic carbon-cycle observations and the need for implementing a policy-relevant carbon observing system

Dolman²,

et al. 2014

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Abstract.A globally integrated carbon observation and analysis system is needed to improve the fundamental understanding of the global carbon cycle, to improve our ability to project future changes, and to verify the effectiveness of policies aiming to reduce greenhouse gas emissions and increase carbon sequestration. Building an integrated carbon observation system requires transformational advances from the existing sparse, exploratory framework towards a dense, robust, and sustained system in all components: anthropogenic emissions, the atmosphere, the ocean, and the terrestrial biosphere. The paper is addressed to scientists, policymakers, and funding agencies who need to have a global picture of the current state of the (diverse) carbon observations. We identify the current state of carbon observations, and the needs and notional requirements for a global integrated carbon observation system that can be built in the next decade. A key conclusion is the substantial expansion of the ground-based observation networks required to reach the high spatial resolution for CO 2 and CH 4 fluxes, and for carbon stocks for addressing policy-relevant objectives, and attributing flux changes to underlying processes in each region. In order to establish flux and stock diagnostics over areas such as the southern oceans, tropical forests, and the Arctic, in situ observations will have to be complemented with remote-sensing measurements. Remote sensing offers the advantage of dense spatial coverage and frequent revisit. A key challenge is to bring remote-sensing measurements to a level of long-term consistency and accuracy so that they can be efficiently combined in models to reduce uncertainties, in synergy with groundbased data. Bringing tight observational constraints on fossil fuel and land use change emissions will be the biggest challenge for deployment of a policy-relevant integrated carbon observation system. This will require in situ and remotely sensed data at much higher resolution and density than currently achieved for natural fluxes, although over a small land area (cities, industrial sites, power plants), as well as the inclusion of fossil fuel CO 2 proxy measurements such as radiocarbon in CO 2 and carbon-fuel combustion tracers. Additionally, a policy-relevant carbon monitoring system should also provide mechanisms for reconciling regional top-down (atmosphere-based) and bottom-up (surface-based) flux estimates across the range of spatial and temporal scales relevant to mitigation policies. In addition, uncertainties for each observation data-stream should be assessed. The success of the system will rely on long-term commitments to monitoring, on improved international collaboration to fill gaps in the current observations, on sustained efforts to improve access to the different data streams and make databases interoperable, and on the calibration of each component of the system to agreed-upon international scales.

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“…Radiocarbon data are reported as the permil (‰) deviation from a standard of fixed isotopic composition: (Stuiver and Quay 1981, Burcholadze et al 1989, Manning and Melhuish 1995, Nydal and Lö vseth 1995. A ⌬ 14 C value of ϩ1000‰ represents a doubling of the amount of 14 C in atmospheric CO 2 .…”

Section: The Radiocarbon Tracermentioning

confidence: 99%

“…With the cessation of most atmospheric tests in 1964, radiocarbon levels decreased as the excess 14 C in the atmosphere began to be transferred into ocean and terrestrial C reservoirs. The radiocarbon signature of atmospheric CO 2 in the 1980s and 1990s continues to decline at a rate of about 8‰ per year (Levin et al 1992) due to continued uptake by the oceans and dilution as CO 2 derived from 14 C-free fossil fuel is added to the atmosphere. The ⌬ 14 C of CO 2 during the northern hemisphere growing season in 1996 was ϩ97 Ϯ 5‰ (Gaudinski et al, in press).…”

Section: The Radiocarbon Tracermentioning

confidence: 99%

Age of Soil Organic Matter and Soil Respiration: Radiocarbon Constraints on Belowground C Dynamics

Trumbore¹

2000

Ecological Applications

391

522

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Abstract. Radiocarbon data from soil organic matter and soil respiration provide powerful constraints for determining carbon dynamics and thereby the magnitude and timing of soil carbon response to global change. In this paper, data from three sites representing well-drained soils in boreal, temperate, and tropical forests are used to illustrate the methods for using radiocarbon to determine the turnover times of soil organic matter and to partition soil respiration. For these sites, the average age of bulk carbon in detrital and Oh/A-horizon organic carbon ranges from 200 to 1200 yr. In each case, this mass-weighted average includes components such as relatively undecomposed leaf, root, and moss litter with much shorter turnover times, and humified or mineral-associated organic matter with much longer turnover times. The average age of carbon in organic matter is greater than the average age predicted for CO 2 produced by its decomposition (30, 8, and 3 yr for boreal, temperate, and tropical soil), or measured in total soil respiration (16, 3, and 1 yr). Most of the CO 2 produced during decomposition is derived from relatively short-lived soil organic matter (SOM) components that do not represent a large component of the standing stock of soil organic matter. Estimates of soil carbon turnover obtained by dividing C stocks by heterotrophic respiration fluxes, or from radiocarbon measurements of bulk SOM, are biased to longer time scales of C cycling. Failure to account for the heterogeneity of soil organic matter will result in underestimation of the short-term response and overestimation of the long-term response of soil C storage to future changes in inputs or decomposition.Comparison of the 14 C in soil respiration with soil organic matter in temperate and boreal forest sites indicates a significant contribution from decomposition of organic matter fixed Ͼ2 yr but Ͻ30 yr ago. Tropical soil respiration is dominated by C fixed Ͻ1 yr ago. Monitoring the 14 C signature of CO 2 emitted from soils give clues as to the causes of seasonal and interannual variability in soil respiration in these systems.

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Radiocarbon in Atmospheric Carbon Dioxide and Methane: Global Distribution and Trends

Cited by 77 publications

References 14 publications

Radioactivity in the Atmosphere

Radioactivity in the Atmosphere

Current systematic carbon-cycle observations and the need for implementing a policy-relevant carbon observing system

Age of Soil Organic Matter and Soil Respiration: Radiocarbon Constraints on Belowground C Dynamics

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