scholarly journals Millennial-age glycerol dialkyl glycerol tetraethers (GDGTs) in forested mineral soils: <sup>14</sup>C-based evidence for stabilization of microbial necromass

2021 ◽  
Vol 18 (1) ◽  
pp. 189-205
Author(s):  
Hannah Gies ◽  
Frank Hagedorn ◽  
Maarten Lupker ◽  
Daniel Montluçon ◽  
Negar Haghipour ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Direct Evidence ◽  
Membrane Lipids ◽  
Soil Depth ◽  
Mineral Surfaces ◽  
Carbon Cycle Model ◽  
Model Predictions ◽  
Microbial Products ◽  
Mineral Soils ◽  
Glycerol Dialkyl Glycerol Tetraethers

Abstract. Understanding controls on the persistence of soil organic matter (SOM) is essential to constrain its role in the carbon cycle and inform climate–carbon cycle model predictions. Emerging concepts regarding the formation and turnover of SOM imply that it is mainly comprised of mineral-stabilized microbial products and residues; however, direct evidence in support of this concept remains limited. Here, we introduce and test a method for the isolation of isoprenoid and branched glycerol dialkyl glycerol tetraethers (GDGTs) – diagnostic membrane lipids of archaea and bacteria, respectively – for subsequent natural abundance radiocarbon analysis. The method is applied to depth profiles from two Swiss pre-Alpine forested soils. We find that the Δ14C values of these microbial markers markedly decrease with increasing soil depth, indicating turnover times of millennia in mineral subsoils. The contrasting metabolisms of the GDGT-producing microorganisms indicates it is unlikely that the low Δ14C values of these membrane lipids reflect heterotrophic acquisition of 14C-depleted carbon. We therefore attribute the 14C-depleted signatures of GDGTs to their physical protection through association with mineral surfaces. These findings thus provide strong evidence for the presence of stabilized microbial necromass in forested mineral soils.

scholarly journals Millennial-age GDGTs in forested mineral soils: <sup>14</sup>C-based evidence for stabilization of microbial necromass

2020 ◽  
Author(s):  
Hannah Gies ◽  
Frank Hagedorn ◽  
Maarten Lupker ◽  
Daniel Montluçon ◽  
Negar Haghipour ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Direct Evidence ◽  
Membrane Lipids ◽  
Soil Depth ◽  
Mineral Surfaces ◽  
Cycle Model ◽  
Carbon Cycle Model ◽  
Model Predictions ◽  
Microbial Products ◽  
Mineral Soils

Abstract. Understanding controls on the persistence of soil organic matter (SOM) is essential to constrain its role in the carbon cycle and inform climate-carbon cycle model predictions. Emerging concepts regarding formation and turnover of SOM imply that it is mainly comprised of mineral-stabilized microbial products and residues, however, direct evidence in support of this concept remains limited. Here, we introduce and test a method for isolation of isoprenoid and branched glycerol dialkyl glycerol tetraethers (GDGTs) – diagnostic membrane lipids of archaea and bacteria, respectively – for subsequent natural abundance radiocarbon analysis. The method is applied to depth profiles from two Swiss pre-alpine forested soils. We find that the ∆14C values of these microbial markers markedly decrease with increasing soil depth, indicating turnover times of millennia in mineral subsoils. The contrasting metabolisms of the GDGT-producing microorganisms indicates it is unlikely that the low ∆14C values of these membrane lipids reflect heterotrophic acquisition of 14C-depleted carbon. We therefore attribute the 14C-depleted signatures of GDGTs to their physical protection through association with mineral surfaces. These findings thus provide strong evidence for the presence of stabilized microbial necromass in forested mineral soils.

Sensitivity of a coupled climate-carbon cycle model to large volcanic eruptions during the last millennium

Tellus B ◽  
2010 ◽  
Vol 62 (5) ◽  
Author(s):  
Victor Brovkin ◽  
Stephan J. Lorenz ◽  
Johann Jungclaus ◽  
Thomas Raddatz ◽  
Claudia Timmreck ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Volcanic Eruptions ◽  
Last Millennium ◽  
Cycle Model ◽  
Carbon Cycle Model ◽  
Large Volcanic Eruptions

Designing and Implementing an Online Carbon Cycle Model Service Platform Based on OGC Web Processing Service

2012 ◽  
Vol 14 (3) ◽  
pp. 320-326
Author(s):  
Nan WU ◽  
Honglin HE ◽  
Li ZHANG ◽  
Xiaoli REN ◽  
Yuanchun ZHOU ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Cycle Model ◽  
Service Platform ◽  
Carbon Cycle Model ◽  
Processing Service

scholarly journals A record of Neogene seawater <i>δ</i><sup>11</sup>B reconstructed from paired <i>δ</i><sup>11</sup>B analyses on benthic and planktic foraminifera

2017 ◽  
Vol 13 (2) ◽  
pp. 149-170 ◽  
Author(s):  
Rosanna Greenop ◽  
Mathis P. Hain ◽  
Sindia M. Sosdian ◽  
Kevin I. C. Oliver ◽  
Philip Goodwin ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Middle Miocene ◽  
Isotope Composition ◽  
Boron Isotope ◽  
Mineral Formation ◽  
Secondary Mineral ◽  
Cycle Model ◽  
Planktic Foraminifera ◽  
Carbon Cycle Model ◽  
Secondary Mineral Formation

Abstract. The boron isotope composition (δ11B) of foraminiferal calcite reflects the pH and the boron isotope composition of the seawater the foraminifer grew in. For pH reconstructions, the δ11B of seawater must therefore be known, but information on this parameter is limited. Here we reconstruct Neogene seawater δ11B based on the δ11B difference between paired measurements of planktic and benthic foraminifera and an estimate of the coeval water column pH gradient from their δ13C values. Carbon cycle model simulations underscore that the ΔpH–Δδ13C relationship is relatively insensitive to ocean and carbon cycle changes, validating our approach. Our reconstructions suggest that δ11Bsw was  ∼  37.5 ‰ during the early and middle Miocene (roughly 23–12 Ma) and rapidly increased during the late Miocene (between 12 and 5 Ma) towards the modern value of 39.61 ‰. Strikingly, this pattern is similar to the evolution of the seawater isotope composition of Mg, Li and Ca, suggesting a common forcing mechanism. Based on the observed direction of change, we hypothesize that an increase in secondary mineral formation during continental weathering affected the isotope composition of riverine input to the ocean since 14 Ma.

scholarly journals Analytically tractable climate–carbon cycle feedbacks under 21st century anthropogenic forcing

2018 ◽  
Vol 9 (2) ◽  
pp. 507-523 ◽  
Author(s):  
Steven J. Lade ◽  
Jonathan F. Donges ◽  
Ingo Fetzer ◽  
John M. Anderies ◽  
Christian Beer ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Global Climate ◽  
Future Climate Change ◽  
Earth System ◽  
Co2 Solubility ◽  
Carbon Cycle Model ◽  
Ocean Climate ◽  
System Models ◽  
Analytical Expressions ◽  
Earth System Models

Abstract. Changes to climate–carbon cycle feedbacks may significantly affect the Earth system's response to greenhouse gas emissions. These feedbacks are usually analysed from numerical output of complex and arguably opaque Earth system models. Here, we construct a stylised global climate–carbon cycle model, test its output against comprehensive Earth system models, and investigate the strengths of its climate–carbon cycle feedbacks analytically. The analytical expressions we obtain aid understanding of carbon cycle feedbacks and the operation of the carbon cycle. Specific results include that different feedback formalisms measure fundamentally the same climate–carbon cycle processes; temperature dependence of the solubility pump, biological pump, and CO2 solubility all contribute approximately equally to the ocean climate–carbon feedback; and concentration–carbon feedbacks may be more sensitive to future climate change than climate–carbon feedbacks. Simple models such as that developed here also provide workbenches for simple but mechanistically based explorations of Earth system processes, such as interactions and feedbacks between the planetary boundaries, that are currently too uncertain to be included in comprehensive Earth system models.

scholarly journals Multicentury Changes to the Global Climate and Carbon Cycle: Results from a Coupled Climate and Carbon Cycle Model

2005 ◽  
Vol 18 (21) ◽  
pp. 4531-4544 ◽  
Author(s):  
G. Bala ◽  
K. Caldeira ◽  
A. Mirin ◽  
M. Wickett ◽  
C. Delire
Keyword(s):  
Carbon Cycle ◽  
Radiative Forcing ◽  
Fossil Fuel ◽  
Global Climate ◽  
Second Century ◽  
Cycle Model ◽  
Carbon Cycle Model ◽  
Living Biomass ◽  
Long Term Consequences

Abstract A coupled climate and carbon (CO2) cycle model is used to investigate the global climate and carbon cycle changes out to the year 2300 that would occur if CO2 emissions from all the currently estimated fossil fuel resources were released to the atmosphere. By the year 2300, the global climate warms by about 8 K and atmospheric CO2 reaches 1423 ppmv. The warming is higher than anticipated because the sensitivity to radiative forcing increases as the simulation progresses. In this simulation, the rate of emissions peaks at over 30 Pg C yr−1 early in the twenty-second century. Even at the year 2300, nearly 50% of cumulative emissions remain in the atmosphere. Both soils and living biomass are net carbon sinks throughout the simulation. Despite having relatively low climate sensitivity and strong carbon uptake by the land biosphere, these model projections suggest severe long-term consequences for global climate if all the fossil fuel carbon is ultimately released into the atmosphere.

scholarly journals Reviews and syntheses: Systematic Earth observations for use in terrestrial carbon cycle data assimilation systems

2017 ◽  
Author(s):  
Marko Scholze ◽  
Michael Buchwitz ◽  
Wouter Dorigo ◽  
Luis Guanter ◽  
Shaun Quegan
Keyword(s):  
Data Assimilation ◽  
Carbon Cycle ◽  
Global Carbon Cycle ◽  
Full Description ◽  
Model Data ◽  
Terrestrial Carbon ◽  
Carbon Cycle Model ◽  
Terrestrial Carbon Cycle ◽  
Uncertainty Estimates ◽  
Global Carbon

Abstract. The global carbon cycle is an important component of the Earth system and it interacts with the hydrological, energy and nutrient cycles as well as ecosystem dynamics. A better understanding of the global carbon cycle is required for improved projections of climate change including corresponding changes in water and food resources and for the verification 5 of measures to reduce anthropogenic greenhouse gas emissions. An improved understanding of the carbon cycle can be achieved by model-data fusion or data assimilation systems, which integrate observations relevant to the carbon cycle into coupled carbon, water, energy and nutrient models. Hence, the ingredients for such systems are a carbon cycle model, an algorithm for the assimilation, and systematic and 10 well error-characterized observations relevant to the carbon cycle. Relevant observations for assimilation include various in-situ measurements in the atmosphere (e.g. concentrations of CO2 and other gases) and on land (e.g. fluxes of carbon water and energy, carbon stocks) as well as remote sensing observations (e.g. atmospheric composition, vegetation and surface properties).We briefly review the different existing data assimilation techniques and contrast them to model 15 benchmarking and evaluation efforts (which also rely on observations). A common requirement for all assimilation techniques is a full description of the observational data properties. Uncertainty estimates of the observations are as important as the observations themselves because they similarly determine the outcome of such assimilation systems. Hence, this article reviews the requirements of data assimilation systems on observations and provides a non-exhaustive overview of current 20 observations and their uncertainties for use in terrestrial carbon cycle data assimilation. We report on progress since the review of model-data synthesis in terrestrial carbon observations by Raupach et al. (2005) emphasising the rapid advance in relevant space-based observations.

scholarly journals Role of volcanic forcing on future global carbon cycle

2011 ◽  
Vol 2 (1) ◽  
pp. 133-159
Author(s):  
J. F. Tjiputra ◽  
O. H. Otterå
Keyword(s):  
Climate Change ◽  
Carbon Cycle ◽  
21St Century ◽  
Volcanic Eruptions ◽  
Future Climate Change ◽  
Small Scale ◽  
Carbon Uptake ◽  
Carbon Cycle Model ◽  
Large Volcanic Eruptions

Abstract. Using a fully coupled global climate-carbon cycle model, we assess the potential role of volcanic eruptions on future projection of climate change and its associated carbon cycle feedback. The volcanic-like forcings are applied together with business-as-usual IPCC-A2 carbon emissions scenario. We show that very large volcanic eruptions similar to Tambora lead to short-term substantial global cooling. However, over a long period, smaller but more frequent eruptions, such as Pinatubo, would have a stronger impact on future climate change. In a scenario where the volcanic external forcings are prescribed with a five-year frequency, the induced cooling immediately lower the global temperature by more than one degree before return to the warming trend. Therefore, the climate change is approximately delayed by several decades and by the end of the 21st century, the warming is still below two degrees when compared to the present day period. The cooler climate reduces the terrestrial heterotrophic respiration in the northern high latitude and increases net primary production in the tropics, which contributes to more than 45% increase in accumulated carbon uptake over land. The increased solubility of CO2 gas in seawater associated with cooler SST is offset by reduced CO2 partial pressure gradient between ocean and atmosphere, which results in small changes in net ocean carbon uptake. Similarly, there is nearly no change in the seawater buffer capacity simulated between the different volcanic scenarios. Our study shows that even in the relatively extreme scenario where large volcanic eruptions occur every five-years period, the induced cooling only leads to a reduction of 46 ppmv atmospheric CO2 concentration as compared to the reference projection of 878 ppmv, at the end of the 21st century. With respect to sulphur injection geoengineering method, our study suggest that small scale but frequent mitigation is more efficient than the opposite. Moreover, the longer we delay, the more difficult it would be to counteract climate change.

scholarly journals Quantifying Carbon Cycle Feedbacks

2009 ◽  
Vol 22 (19) ◽  
pp. 5232-5250 ◽  
Author(s):  
J. M. Gregory ◽  
C. D. Jones ◽  
P. Cadule ◽  
P. Friedlingstein
Keyword(s):  
Carbon Cycle ◽  
Co2 Emissions ◽  
Co2 Concentration ◽  
Atmospheric Co2 ◽  
Climate Feedback ◽  
Climate Response ◽  
Carbon Cycle Model ◽  
Atmospheric Co2 Concentration ◽  
Intercomparison Project ◽  
Earth System Models

Abstract Perturbations to the carbon cycle could constitute large feedbacks on future changes in atmospheric CO2 concentration and climate. This paper demonstrates how carbon cycle feedback can be expressed in formally similar ways to climate feedback, and thus compares their magnitudes. The carbon cycle gives rise to two climate feedback terms: the concentration–carbon feedback, resulting from the uptake of carbon by land and ocean as a biogeochemical response to the atmospheric CO2 concentration, and the climate–carbon feedback, resulting from the effect of climate change on carbon fluxes. In the earth system models of the Coupled Climate–Carbon Cycle Model Intercomparison Project (C4MIP), climate–carbon feedback on warming is positive and of a similar size to the cloud feedback. The concentration–carbon feedback is negative; it has generally received less attention in the literature, but in magnitude it is 4 times larger than the climate–carbon feedback and more uncertain. The concentration–carbon feedback is the dominant uncertainty in the allowable CO2 emissions that are consistent with a given CO2 concentration scenario. In modeling the climate response to a scenario of CO2 emissions, the net carbon cycle feedback is of comparable size and uncertainty to the noncarbon–climate response. To quantify simulated carbon cycle feedbacks satisfactorily, a radiatively coupled experiment is needed, in addition to the fully coupled and biogeochemically coupled experiments, which are referred to as coupled and uncoupled in C4MIP. The concentration–carbon and climate–carbon feedbacks do not combine linearly, and the concentration–carbon feedback is dependent on scenario and time.

scholarly journals Roles of Toll-Like Receptors in Nitroxidative Stress in Mammals

Cells ◽  
2019 ◽  
Vol 8 (6) ◽  
pp. 576 ◽  
Author(s):  
Yao Li ◽  
Shou-Long Deng ◽  
Zheng-Xing Lian ◽  
Kun Yu
Keyword(s):  
Membrane Lipids ◽  
Tissue Injury ◽  
Reactive Oxygen ◽  
Innate Immune ◽  
Cellular Damage ◽  
Inflammatory Factors ◽  
Nitrogen Species ◽  
Toll Like Receptors ◽  
Pathogen Invasion ◽  
Microbial Products

Free radicals are important antimicrobial effectors that cause damage to DNA, membrane lipids, and proteins. Professional phagocytes produce reactive oxygen species (ROS) and reactive nitrogen species (RNS) that contribute towards the destruction of pathogens. Toll-like receptors (TLRs) play a fundamental role in the innate immune response and respond to conserved microbial products and endogenous molecules resulting from cellular damage to elicit an effective defense against invading pathogens, tissue injury, or cancer. In recent years, several studies have focused on how the TLR-mediated activation of innate immune cells leads to the production of pro-inflammatory factors upon pathogen invasion. Here, we review recent findings that indicate that TLRs trigger a signaling cascade that induces the production of reactive oxygen and nitrogen species.

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