Processes of the Long-Term Carbon Cycle: Organic Matter and Carbonate Burial and Weathering

2004 ◽  
Author(s):  
Robert A. Berner
Keyword(s):  
Organic Matter ◽  
Carbon Cycle ◽  
Atmospheric Oxygen ◽  
Marine Phytoplankton ◽  
Atmospheric Co2 ◽  
Carbonate Weathering ◽  
Major Question ◽  
Water Composition ◽  
Subsequent Exposure

The organic subcycle of the long-term carbon cycle, where organic matter burial and weathering are involved, constitutes the major control on the evolution of atmospheric oxygen. It is also important as a secondary factor affecting atmospheric CO2. Thus, it is important to better understand the processes whereby organic matter is buried in sediments and oxidized upon subsequent exposure to weathering during uplift onto the continents. This is especially true of the Paleozoic rise of land plants, which had a large effect on atmospheric CO2 because of increased global organic burial due to the addition of plant debris to sediments. The burial of organic matter in marine sediments is impacted strongly by the availability of the nutrient elements, phosphorus and nitrogen, so a complete discussion of the cycling of organic carbon should involve some discussion of the cycles of these elements. Carbonate burial is the ultimate sink for CO2 derived from the atmosphere via the weathering of Ca and Mg silicates. The location of this burial, shallow water shelves versus the deep sea floor, is important because it affects the probability that the carbonate will be eventually thermally recycled and the carbon returned to the atmosphere. Carbonate weathering is the dominant process affecting river water composition and is a key component of the cycling of carbon. Its importance to the long-term carbon cycle is that, in order to calculate the removal of CO2 from the atmosphere via Ca and Mg silicate weathering, it is necessary to correct total carbonate burial for that derived from carbonate weathering. At present, sedimentary organic matter burial occurs in swamps, lakes, reservoirs, estuaries, and in the open marine environment. The ultimate sources of the organics are land vegetation and marine phytoplankton. Also, soil organic matter, which is intimately associated with clay minerals, is eroded and transported to the sea by rivers (Hedges et al., 1994). A major question is how much of the total global burial is of marine or nonmarine origin. Recent work has shown that organic burial on land is much higher than previously recognized, especially as a result of human activities (Dean and Gorham, 1998; Stallard, 1998).

scholarly journals Three decades of simulated global terrestrial carbon fluxes from a data assimilation system confronted with different periods of observations

2019 ◽  
Vol 16 (15) ◽  
pp. 3009-3032 ◽  
Author(s):  
Karel Castro-Morales ◽  
Gregor Schürmann ◽  
Christoph Köstler ◽  
Christian Rödenbeck ◽  
Martin Heimann ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Carbon Cycle ◽  
Atmospheric Co2 ◽  
Term Trend ◽  
Atmospheric Co2 Concentrations ◽  
Long Term Trend ◽  
Global Carbon ◽  
Data Assimilation System ◽  
Assimilation System

Abstract. During the last decade, carbon cycle data assimilation systems (CCDAS) have focused on improving the simulation of seasonal and mean global carbon fluxes over a few years by simultaneous assimilation of multiple data streams. However, the ability of a CCDAS to predict longer-term trends and variability of the global carbon cycle and the constraint provided by the observations have not yet been assessed. Here, we evaluate two near-decade-long assimilation experiments of the Max Planck Institute – Carbon Cycle Data Assimilation System (MPI-CCDAS v1) using spaceborne estimates of the fraction of absorbed photosynthetic active radiation (FAPAR) and atmospheric CO2 concentrations from the global network of flask measurement sites from either 1982 to 1990 or 1990 to 2000. We contrast these simulations with independent observations from the period 1982–2010, as well as a third MPI-CCDAS assimilation run using data from the full 1982–2010 period, and an atmospheric inversion covering the same data and time. With 30 years of data, MPI-CCDAS is capable of representing land uptake to a sufficient degree to make it compatible with the atmospheric CO2 record. The long-term trend and seasonal amplitude of atmospheric CO2 concentrations at station level over the period 1982 to 2010 is considerably improved after assimilating only the first decade (1982–1990) of observations. After 15–19 years of prognostic simulation, the simulated CO2 mixing ratio in 2007–2010 diverges by only 2±1.3 ppm from the observations, the atmospheric inversion, and the MPI-CCDAS assimilation run using observations from the full period. The long-term trend, phenological seasonality, and interannual variability (IAV) of FAPAR in the Northern Hemisphere over the last 1 to 2 decades after the assimilation were also improved. Despite imperfections in the representation of the IAV in atmospheric CO2, model–data fusion for a decade of data can already contribute to the prognostic capacity of land carbon cycle models at relevant timescales.

scholarly journals Modelling the long-term carbon cycle, atmospheric CO2, and Earth surface temperature from late Neoproterozoic to present day

2019 ◽  
Vol 67 ◽  
pp. 172-186 ◽  
Author(s):  
Benjamin J.W. Mills ◽  
Alexander J. Krause ◽  
Christopher R. Scotese ◽  
Daniel J. Hill ◽  
Graham A. Shields ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Surface Temperature ◽  
Atmospheric Co2 ◽  
Earth Surface ◽  
Late Neoproterozoic

Atmospheric Carbon Dioxide over Phanerozoic Time

2004 ◽  
Author(s):  
Robert A. Berner
Keyword(s):  
Organic Matter ◽  
Steady State ◽  
Carbon Cycle ◽  
Atmospheric Carbon Dioxide ◽  
Total Carbon ◽  
Atmospheric Composition ◽  
Burial Flux ◽  
State Models ◽  
Fundamental Equations

In this chapter the methods and results of modeling the long-term carbon cycle are presented in terms of predictions of past levels of atmospheric CO2. The modeling results are then compared with independent determinations of paleo-CO2 by means of a variety of different methods. Results indicate that there is reasonable agreement between methods as to the general trend of CO2 over Phanerozoic time. Values of fluxes in the long-term carbon cycle can be calculated from the fundamental equations for total carbon and 13C mass balance that are stated in the introduction and are repeated here: . . . dMc/dt = Fwc + Fwg + Fmc + Fmg – Fbc – Fbg (1.10) . . . . . . d(δcMc)/dt = δwcFwc + δwgFwg + δmcFmc + δmgFmg – δbcFbc – δbgFbg (1.11) . . . where Mc = mass of carbon in the surficial system consisting of the atmosphere, oceans, biosphere, and soils Fwc = flux from weathering of Ca and Mg carbonates Fwg = flux from weathering of sedimentary organic matter Fmc = degassing flux for carbonates from volcanism, metamorphism, and diagenesis Fmg = degassing flux for organic matter from volcanism, metamorphism, and diagenesis Fbc = burial flux of carbonates in sediments Fbg = burial flux of organic matter in sediments δ = [(13C/12C)/(13C/12C)stnd – 1]1000. Variants of equations (1.10) and (1.11) have been treated in terms of non–steady-state modeling (e.g., Berner et al., 1983; Wallmann, 2001; Hansen and Wallmann, 2003; Mackenzie et al., 2003; Bergman et al., 2003), where the evolution of both oceanic and atmospheric composition, including Ca, Mg, and other elements in seawater, is tracked over time. However, since the purpose of this book is to discuss the carbon cycle with respect to CO2 and O2, and so as not to overburden the reader with too many mathematical expressions, I discuss only those aspects of the non–steady-state models that directly impact carbon. These are combined with results from steady-state strictly carbon-cycle modeling (Garrels and Lerman, 1984; Berner, 1991, 1994; Kump and Arthur, 1997; Francois and Godderis, 1998; Tajika, 1998; Berner and Kothavala, 2001; Kashiwagi and Shikazono, 2002).

Regularity of formation of microbial communities in spontaneously renewabl meadows biogeocoenosis

2018 ◽  
Vol 2 (95) ◽  
pp. 42-48
Author(s):  
I.M. Malinovskaya
Keyword(s):  
Organic Matter ◽  
Biological Activity ◽  
Carbon Cycle ◽  
Microbial Communities ◽  
Functional Groups ◽  
Nitrogen Cycle ◽  
Forest Soils ◽  
Microbiological Processes ◽  
Number Of Microorganisms

Investigated direction and intensity of microbiological processes in gray forest soils of varying duration as compared to extensive and intensive ahrozemamy. It has been established that the number of microorganisms of certain ecological trophic and functional groups in the ground of the foreground changes with the time of its stay in the state of reflux. The largest number of microorganisms is characterized by microbial grouping of long-term overeating: it contains more microorganisms in the nitrogen cycle and less microorganisms in the carbon cycle compared with fewer periods of shorter duration. The soil of a long-term overgrowth is characterized by the highest total biological activity, which exceeds the activity of the soil of the perehlava from 2000 by 72.9%, and from 2007 - by 48.8%. With the increase in the duration of the flood, the intensity of the organic matter development of the soil is reduced to 3.26 and 2.59 times for the revisions from 2000 and 1987, respectively; the processes of humus destruction considerably slow down: the activity of mineralization of humus in the soil of a perennial flood is lower than the corresponding indexes of revisions from 2000 and 2007 by 50,0 and 60,0%; the phytotoxicity of the soil decreases by 9.47%.

scholarly journals Alaskan carbon-climate feedbacks will be weaker than inferred from short-term experiments

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Nicholas J. Bouskill ◽  
William J. Riley ◽  
Qing Zhu ◽  
Zelalem A. Mekonnen ◽  
Robert F. Grant
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Carbon Cycle ◽  
Field Experiments ◽  
Ecosystem Model ◽  
Climate Feedbacks ◽  
Short Term ◽  
Ecosystem Carbon ◽  
Tightly Coupled

AbstractClimate warming is occurring fastest at high latitudes. Based on short-term field experiments, this warming is projected to stimulate soil organic matter decomposition, and promote a positive feedback to climate change. We show here that the tightly coupled, nonlinear nature of high-latitude ecosystems implies that short-term (<10 year) warming experiments produce emergent ecosystem carbon stock temperature sensitivities inconsistent with emergent multi-decadal responses. We first demonstrate that a well-tested mechanistic ecosystem model accurately represents observed carbon cycle and active layer depth responses to short-term summer warming in four diverse Alaskan sites. We then show that short-term warming manipulations do not capture the non-linear, long-term dynamics of vegetation, and thereby soil organic matter, that occur in response to thermal, hydrological, and nutrient transformations belowground. Our results demonstrate significant spatial heterogeneity in multi-decadal Arctic carbon cycle trajectories and argue for more mechanistic models to improve predictive capabilities.

scholarly journals Reconciling atmospheric CO2, weathering, and calcite compensation depth across the Cenozoic

2021 ◽  
Vol 7 (4) ◽  
pp. eabd4876
Author(s):  
Nemanja Komar ◽  
Richard E. Zeebe
Keyword(s):  
Carbon Cycle ◽  
Critical Role ◽  
Carbonate Weathering ◽  
Weathering Rates ◽  
Marine Organic Matter ◽  
Novel Approach ◽  
Compensation Depth ◽  
Long Term Trends ◽  
Cenozoic Era

The Cenozoic era (66 to 0 million years) is marked by long-term aberrations in carbon cycling and large climatic shifts, some of which challenge the current understanding of carbon cycle dynamics. Here, we investigate possible mechanisms responsible for the observed long-term trends by using a novel approach that features a full-fledged ocean carbonate chemistry model. Using a compilation of pCO2, pH, and calcite compensation depth (CCD) observational evidence and a suite of simulations, we reconcile long-term Cenozoic climate and CCD trends. We show that the CCD response was decoupled from changes in silicate and carbonate weathering rates, challenging the continental uplift hypothesis. The two dominant mechanisms for decoupling are shelf-basin carbonate burial fractionation combined with proliferation of pelagic calcifiers. The temperature effect on remineralization rates of marine organic matter also plays a critical role in controlling the carbon cycle dynamics, especially during the warmer periods of the Cenozoic.

Global stability of atmospheric oxygen

1993 ◽  
Vol 1 (3) ◽  
pp. 217-229
Author(s):  
Egbert K. Duursma ◽  
Michel P. R. M. Boisson
Keyword(s):  
Organic Matter ◽  
Atmospheric Oxygen ◽  
Living Organism ◽  
Optimum Level ◽  
Short Term ◽  
Fossil Carbon ◽  
Fossil Fuel Burning ◽  
Short Time ◽  
Photosynthesis And Respiration

The atmospheric oxygen reserve is so huge that, in the short term of hundreds or thousands of years, only minor changes can be expected due to fossil fuel burning and deforestation. Each oxygen molecule passes through a living organism, on average, only once in 9000 years. As a consequence, the fastest regulating system must take of the order of hundreds of years. Nevertheless, it is possible that the actual oxygen level is not necessarily at the optimum level for life, but is just an accidental one in the course of the earth's history. Tropical forests are not the ‘lungs’ of the earth in terms of hundreds of years, but only on a much longer time scale, likewise for all other vegetation which produce humus and the long-term fossil carbon. The driving force is related to the slight differences caused by external factors between photosynthesis and respiration, with subsequent organic matter deposition or consumption for short time regulation of hundreds of years; while, for periods of millions of years, the regulation depends on changes of weathering or burial of fossil sedimentary organic matter.

Earth’s Middle Ages: What Came after the GOE

2017 ◽  
Author(s):  
Donald Eugene Canfield
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Middle Ages ◽  
Atmospheric Oxygen ◽  
Iron Formation ◽  
Banded Iron Formation ◽  
Dissolved Iron ◽  
Great Oxidation Event ◽  
Low Levels ◽  
Substantial Rise

This chapter considers the aftermath of the great oxidation event (GOE). It suggests that there was a substantial rise in oxygen defining the GOE, which may, in turn have led to the Lomagundi isotope excursion, which was associated with high rates of organic matter burial and perhaps even higher concentrations of oxygen. This excursion was soon followed by a crash in oxygen to very low levels and a return to banded iron formation deposition. When the massive amounts of organic carbon buried during the excursion were brought into the weathering environment, they would have represented a huge oxygen sink, drawing down levels of atmospheric oxygen. There appeared to be a veritable seesaw in oxygen concentrations, apparently triggered initially by the GOE. The GOE did not produce enough oxygen to oxygenate the oceans. Dissolved iron was removed from the oceans not by reaction with oxygen but rather by reaction with sulfide. Thus, the deep oceans remained anoxic and became rich in sulfide, instead of becoming well oxygenated.

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