Sequestration of atmospheric CO2 in a weathering-derived, serpentinite-hosted magnesite deposit: 14C tracing of carbon sources and age constraints for a refined genetic model

2013 ◽  
Vol 122 ◽  
pp. 226-246 ◽  
Author(s):  
H.C. Oskierski ◽  
B.Z. Dlugogorski ◽  
G. Jacobsen
Keyword(s):  
Genetic Model ◽  
Carbon Sources ◽  
Atmospheric Co2 ◽  
Magnesite Deposit ◽  
Age Constraints

scholarly journals Contribution of Various Carbon Sources Toward Isoprene Biosynthesis in Poplar Leaves Mediated by Altered Atmospheric CO2 Concentrations

PLoS ONE ◽  
2012 ◽  
Vol 7 (2) ◽  
pp. e32387 ◽  
Author(s):  
Amy M. Trowbridge ◽  
Dolores Asensio ◽  
Allyson S. D. Eller ◽  
Danielle A. Way ◽  
Michael J. Wilkinson ◽  
...  
Keyword(s):  
Carbon Sources ◽  
Atmospheric Co2 ◽  
Co2 Concentrations ◽  
Atmospheric Co2 Concentrations ◽  
Poplar Leaves

scholarly journals What was the source of the atmospheric CO<sub>2</sub> increase during the Holocene?

2019 ◽  
Vol 16 (13) ◽  
pp. 2543-2555 ◽  
Author(s):  
Victor Brovkin ◽  
Stephan Lorenz ◽  
Thomas Raddatz ◽  
Tatiana Ilyina ◽  
Irene Stemmler ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Carbon Sink ◽  
Ice Core ◽  
Carbon Sources ◽  
Co2 Concentration ◽  
Atmospheric Co2 ◽  
Ion Concentration ◽  
Model Framework ◽  
Atmospheric Co2 Concentration ◽  
Transient Simulations

Abstract. The atmospheric CO2 concentration increased by about 20 ppm from 6000 BCE to the pre-industrial period (1850 CE). Several hypotheses have been proposed to explain mechanisms of this CO2 growth based on either ocean or land carbon sources. Here, we apply the Earth system model MPI-ESM-LR for two transient simulations of climate and carbon cycle dynamics during this period. In the first simulation, atmospheric CO2 is prescribed following ice-core CO2 data. In response to the growing atmospheric CO2 concentration, land carbon storage increases until 2000 BCE, stagnates afterwards, and decreases from 1 CE, while the ocean continuously takes CO2 out of the atmosphere after 4000 BCE. This leads to a missing source of 166 Pg of carbon in the ocean–land–atmosphere system by the end of the simulation. In the second experiment, we applied a CO2 nudging technique using surface alkalinity forcing to follow the reconstructed CO2 concentration while keeping the carbon cycle interactive. In that case the ocean is a source of CO2 from 6000 to 2000 BCE due to a decrease in the surface ocean alkalinity. In the prescribed CO2 simulation, surface alkalinity declines as well. However, it is not sufficient to turn the ocean into a CO2 source. The carbonate ion concentration in the deep Atlantic decreases in both the prescribed and the interactive CO2 simulations, while the magnitude of the decrease in the prescribed CO2 experiment is underestimated in comparison with available proxies. As the land serves as a carbon sink until 2000 BCE due to natural carbon cycle processes in both experiments, the missing source of carbon for land and atmosphere can only be attributed to the ocean. Within our model framework, an additional mechanism, such as surface alkalinity decrease, for example due to unaccounted for carbonate accumulation processes on shelves, is required for consistency with ice-core CO2 data. Consequently, our simulations support the hypothesis that the ocean was a source of CO2 until the late Holocene when anthropogenic CO2 sources started to affect atmospheric CO2.

scholarly journals Carbon cycling on the East Siberian Arctic Shelf – a change in air-sea CO<sub>2</sub> flux induced by mineralization of terrestrial organic carbon

2017 ◽  
Author(s):  
Erik Gustafsson ◽  
Christoph Humborg ◽  
Göran Björk ◽  
Christian Stranne ◽  
Leif G. Anderson ◽  
...  
Keyword(s):  
Stable Isotope ◽  
Organic Carbon ◽  
Carbon Cycling ◽  
Dissolved Inorganic Carbon ◽  
Carbon Sources ◽  
Atmospheric Co2 ◽  
Arctic Shelf ◽  
The Arctic ◽  
Biogeochemical Model ◽  
Siberian Arctic

Abstract. Measurements from the SWERUS-C3 and ISSS-08 Arctic expeditions were used to calibrate and validate a new physical-biogeochemical model developed to quantify key carbon cycling processes on the East Siberian Arctic Shelf (ESAS). The model was used in a series of experimental simulations with the specific aim to investigate the pathways of terrestrial dissolved and particulate organic carbon (DOCter and POCter) supplied to the shelf. Rivers supply on average 8.5 Tg C yr−1 dissolved inorganic carbon (DIC), and further 8.5 and 1.1 Tg C yr−1 DOCter and POCter respectively. Based on observed and simulated DOC concentrations and stable isotope values (δ13CDOC) in shelf waters, we estimate that only some 20 % of the riverine DOCter is labile. According to our model results, an additional supply of approximately 14 Tg C yr−1 eroded labile POCter is however required to describe the observed stable isotope values of DIC (δ13CDIC). Degradation of riverine DOCter and POCter results in a 1.8 Tg C yr−1 reduction in the uptake of atmospheric CO2, while degradation of eroded POCter results in an additional 10 Tg C yr−1 reduction. Our calculations indicate nevertheless that the ESAS is an overall small net sink for atmospheric CO2 (1.7 Tg C yr−1). The external carbon sources are largely compensated by a net export from the shelf to the Arctic Ocean (31 Tg C yr−1), and to a smaller degree by a permanent burial in the sediments (2.7 Tg C yr−1).

scholarly journals Forest stand age information improves an inverse North American carbon flux estimate

2013 ◽  
Vol 10 (3) ◽  
pp. 4781-4817 ◽  
Author(s):  
F. Deng ◽  
J. M. Chen ◽  
Y. Pan ◽  
W. Peters ◽  
R. Birdsey ◽  
...  
Keyword(s):  
Carbon Flux ◽  
Age Factors ◽  
Carbon Sources ◽  
Co2 Flux ◽  
Forest Stand ◽  
Atmospheric Co2 ◽  
Stand Age ◽  
Ecosystem Carbon ◽  
Net Ecosystem Carbon Exchange ◽  
Carbon Dioxide Co2

Abstract. Atmospheric inversions have become an important tool in quantifying carbon dioxide (CO2) sinks and sources at a variety of spatiotemporal scales, but associated large uncertainties restrain the inversion research community from reaching agreements on many important subjects. We enhanced an atmospheric inversion of the CO2 flux for North America by introducing spatially-explicit information on forest stand age for US and Canada as an additional constraint, since forest carbon dynamics are closely related to time since disturbance. To use stand age information in the inversion, we converted stand age into an age factor, and included the covariances between sub-continental regions in the inversion based on the similarity of the age factors. Our inversion results show that, considering age factors, regions with recently-disturbed or old forests are often nudged towards carbon sources, while regions with middle-aged productive forests are shifted towards sinks. This conforms to stand age effects observed in flux networks. At the sub-continental level, our inverted carbon fluxes agree well with continuous estimates of net ecosystem carbon exchange (NEE) upscaled from eddy covariance flux data (EC) based on MODIS data. Inverted fluxes with the age constraint exhibit stronger correlation to these upscaled NEE estimates than those inverted without the age constraint. While the carbon flux at the continental and sub-continental scales is predominantly determined by atmospheric CO2 observations, the age constraint is shown to have potential to improve the inversion of the carbon flux distribution among sub-continental regions, especially for regions lacking atmospheric CO2 observations.

scholarly journals Data-based estimates of interannual sea–air CO<sub>2</sub> flux variations 1957–2020 and their relation to environmental drivers

2021 ◽  
Author(s):  
Christian Rödenbeck ◽  
Tim DeVries ◽  
Judith Hauck ◽  
Corinne Le Quéré ◽  
Ralph Keeling
Keyword(s):  
Wind Speed ◽  
Linear Regression ◽  
Mixed Layer ◽  
Carbon Sources ◽  
Co2 Flux ◽  
Mapping Method ◽  
Atmospheric Co2 ◽  
Environmental Drivers ◽  
Multi Linear Regression ◽  
Secular Increase

Abstract. This study considers year-to-year and decadal variations as well as secular trends of the sea–air CO2 flux over the 1957–2020 period, as constrained by the pCO2 measurements from the SOCAT data base. In a first step, we relate interannual anomalies in ocean-internal carbon sources and sinks to local interannual anomalies in sea surface temperature (SST), the temporal changes of SST (dSST/dt), and squared wind speed (u2), employing a multi-linear regression. In the tropical Pacific, we find interannual variability to be dominated by dSST/dt, as arising from variations in the upwelling of colder and more carbon-rich waters into the mixed layer. In the eastern upwelling zones as well as in circumpolar bands in the high latitudes of both hemispheres, we find sensitivity to wind speed, compatible with the entrainment of carbon-rich water during wind-driven deepening of the mixed layer and wind-driven upwelling. In the Southern Ocean, the secular increase in wind speed leads to a secular increase in the carbon source into the mixed layer, with an estimated reduction of the sink trend in the range 17 to 42 %. In a second step, we combined the result of the multi-linear regression and an explicitly interannual pCO2-based additive correction into a “hybrid” estimate of the sea–air CO2 flux over the period 1957–2020. As a pCO2 mapping method, it combines (a) the ability of a regression to bridge data gaps and extrapolate into the early decades almost void of pCO2 data based on process-related observables and (b) the ability of an autoregressive interpolation to follow signals even if not represented in the chosen set of explanatory variables. The “hybrid” estimate can be applied as ocean flux prior for atmospheric CO2 inversions covering the whole period of atmospheric CO2 data since 1957.

scholarly journals The use of forest stand age information in an atmospheric CO<sub>2</sub> inversion applied to North America

2013 ◽  
Vol 10 (8) ◽  
pp. 5335-5348 ◽  
Author(s):  
F. Deng ◽  
J. M. Chen ◽  
Y. Pan ◽  
W. Peters ◽  
R. Birdsey ◽  
...  
Keyword(s):  
North America ◽  
Carbon Flux ◽  
Age Factors ◽  
Carbon Sources ◽  
Co2 Flux ◽  
Forest Stand ◽  
Atmospheric Co2 ◽  
Stand Age ◽  
Net Ecosystem Carbon Exchange ◽  
Carbon Dioxide Co2

Abstract. Atmospheric inversions have become an important tool in quantifying carbon dioxide (CO2) sinks and sources at a variety of spatiotemporal scales, but associated large uncertainties restrain the inversion research community from reaching agreement on many important subjects. We enhanced an atmospheric inversion of the CO2 flux for North America by introducing spatially explicit information on forest stand age for US and Canada as an additional constraint, since forest carbon dynamics are closely related to time since disturbance. To use stand age information in the inversion, we converted stand age into an age factor, and included the covariances between subcontinental regions in the inversion based on the similarity of the age factors. Our inversion results show that, considering age factors, regions with recently disturbed or old forests are often nudged towards carbon sources, while regions with middle-aged productive forests are shifted towards sinks. This conforms to stand age effects observed in flux networks. At the subcontinental level, our inverted carbon fluxes agree well with continuous estimates of net ecosystem carbon exchange (NEE) upscaled from eddy covariance flux data based on MODIS data. Inverted fluxes with the age constraint exhibit stronger correlation to these upscaled NEE estimates than those inverted without the age constraint. While the carbon flux at the continental and subcontinental scales is predominantly determined by atmospheric CO2 observations, the age constraint is shown to have potential to improve the inversion of the carbon flux distribution among subcontinental regions, especially for regions lacking atmospheric CO2 observations.

scholarly journals Sea-air CO<sub>2</sub> flux estimated from SOCAT surface-ocean CO<sub>2</sub> partial pressure data and atmospheric CO<sub>2</sub> mixing ratio data

2012 ◽  
Vol 9 (3) ◽  
pp. 2273-2326 ◽  
Author(s):  
C. Rödenbeck ◽  
R. F. Keeling ◽  
D. C. E. Bakker ◽  
N. Metzl ◽  
A. Olsen ◽  
...  
Keyword(s):  
Partial Pressure ◽  
Carbon Sources ◽  
Co2 Flux ◽  
Atmospheric Co2 ◽  
Diagnostic Model ◽  
Pressure Data ◽  
Co2 Partial Pressure ◽  
Sources And Sinks ◽  
Surface Ocean ◽  
Spatio Temporal

Abstract. Surface-ocean CO2 partial pressure data have been assimilated into a simple diagnostic model of surface-ocean biogeochemistry to estimate the spatio-temporal CO2 partial pressure field and ultimately the sea-air CO2 fluxes. Results compare well with the widely used monthly climatology by Takahashi et al. (2009) but also contain some short-term and interannual variations. Fitting the same model to atmospheric CO2 data yields less robust but consistent estimates, confirming that using the partial pressure based estimates as ocean prior in atmospheric CO2 inversions may improve land CO2 flux estimates. Estimated seasonality of ocean-internal carbon sources and sinks is discussed in the light of observed nutrient variations.

scholarly journals Genesis of magnesite deposits in the view of isotope geochemistry

2002 ◽  
Vol 50 ◽  
Author(s):  
ERICH SCHROLL
Keyword(s):  
Carbon Isotope ◽  
Genetic Model ◽  
Isotope Geochemistry ◽  
Isotopic Signature ◽  
Economic Importance ◽  
Geochemical Data ◽  
Carbonate Sediments ◽  
Isotopic Data ◽  
Magnesite Deposit ◽  
Vein Type

Isotopic data, i.e. δ 13 C and δ 18 O including 86 Sr/87 Sr, are the fundamental data to characterize geochemically magnesite mineralizations. Other geochemical data, e.g. chemical data, REE and fluid chemistry, are supplementary characteristics for genetic models. The geological setting and the origin of magnesium are relevant to classify magnesites genetically. The δ 13 C - δ 18 O - diagrams of magnesite and siderite are significantly different. Stratabound magnesite is dominated by the isotopic signature of carbonate sediments, while siderites from occurrences with economic importance preferably show light carbon isotope like the ultramafic-hosted vein type mineralization. The δ 18 O original values of sparry magnesites are strongly influenced by burial and grade of metasomatism. Thus, the origin of sparry magnesite hosted by metasediments is to be considered as a sedimentary enrichment influenced by diagenetic and metamorphic processes. An approach to the best genetic model of each magnesite deposit needs the synopsis of all geological facts and geochemical data.

scholarly journals What was the source of the atmospheric CO<sub>2</sub> increase during the Holocene?

2019 ◽  
Author(s):  
Victor Brovkin ◽  
Stephan Lorenz ◽  
Thomas Raddatz ◽  
Tatiana Ilyina ◽  
Irene Stemmler ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Carbon Sink ◽  
Ice Core ◽  
Carbon Sources ◽  
Co2 Concentration ◽  
Atmospheric Co2 ◽  
Ion Concentration ◽  
Model Framework ◽  
Atmospheric Co2 Concentration ◽  
Transient Simulations

Abstract. The atmospheric CO2 concentration increased by about 20 ppm from 6000 BCE to pre-industrial (1850 CE). Several hypotheses have been proposed to explain mechanisms of this CO2 growth based on either ocean or land carbon sources. Here, we apply the Earth System model MPI-ESM-LR for two transient simulations of climate and carbon cycle dynamics during this period. In the 1st simulation, atmospheric CO2 is prescribed following ice-core CO2 data. In response to the growing atmospheric CO2 concentration, land carbon storage increases until 2000 BCE, stagnates afterwards, and decreases from 1 CE, while the ocean continuously takes CO2 out of atmosphere after 4000 BCE. This leads to a missing source of 166 Pg of carbon in the ocean-land-atmosphere system by the end of the simulation. In the 2nd experiment, we applied a CO2-nudging technique using surface alkalinity forcing to follow the reconstructed CO2 concentration while keeping the carbon cycle interactive. In that case the ocean is a source of CO2 from 6000 to 2000 BCE due to a decrease in the surface ocean alkalinity. In the prescribed CO2 simulation, surface alkalinity declines as well. However, it is not sufficient to turn the ocean into a CO2 source. The carbonate ion concentration in the deep Atlantic decreases in both the prescribed and the interactive CO2 simulations, while the magnitude of the decrease in the prescribed CO2 experiment is underestimated in comparison with available proxies. As the land serves as a carbon sink until 2000 BCE due to natural carbon cycle processes in both experiments, the missing source of carbon for land and atmosphere can only be attributed to the ocean. Within our model framework, an additional mechanism, such as surface alkalinity decrease, for example due to unaccounted carbonate accumulation processes on shelves, is required for consistency with ice-core CO2 data. Consequently, our simulations support the hypothesis that the ocean was a source of CO2 until the late Holocene when anthropogenic CO2 sources started to affect atmospheric CO2.

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