Herbivory and its effect on Phanerozoic oxygen concentrations

Geology ◽  
2020 ◽  
Vol 48 (4) ◽  
pp. 410-414
Author(s):  
T.A. Laakso ◽  
J.V. Strauss ◽  
K.J. Peterson
Keyword(s):  
Organic Compounds ◽  
Atmospheric Oxygen ◽  
Deep Ocean ◽  
Land Plant ◽  
Plant Colonization ◽  
Terrestrial Plants ◽  
Oxygen Levels ◽  
Carbon Burial ◽  
Organic Carbon Burial

Abstract The appearance of terrestrial land plants is thought to have accompanied an increase in atmospheric oxygen levels, producing the highest O2 concentrations estimated from the geological record, and marking the transition to a permanently oxygenated deep ocean. This Paleozoic oxygenation event, which likely peaked in the Carboniferous Period, was at least partially mediated by the development of recalcitrant, carbon-rich organic compounds in terrestrial plants. A number of studies have argued that shifts in coal formation and paleogeography led to declining preservation of these compounds on land, depressing oxygen levels in the terminal Paleozoic and early Mesozoic. In contrast, we propose that the evolution and diversification of terrestrial herbivores may have limited transport and long-term burial of terrestrial organic compounds in marine sediments, resulting in less organic carbon burial and attendant declines in atmospheric oxygen. This mechanism suggests that interactions among a triad of biological processes—marine photosynthesis, land plant colonization, and the advent of herbivory—may have dictated the long-term redox state of Earth’s surface environments over the Phanerozoic Eon.

scholarly journals Earliest land plants created modern levels of atmospheric oxygen

2016 ◽  
Vol 113 (35) ◽  
pp. 9704-9709 ◽  
Author(s):  
Timothy M. Lenton ◽  
Tais W. Dahl ◽  
Stuart J. Daines ◽  
Benjamin J. W. Mills ◽  
Kazumi Ozaki ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Land Surface ◽  
Atmospheric Oxygen ◽  
Geochemical Data ◽  
Regulatory Regime ◽  
Carbon Burial ◽  
C:P Ratio ◽  
Marine Biomass ◽  
Organic Carbon Burial

The progressive oxygenation of the Earth’s atmosphere was pivotal to the evolution of life, but the puzzle of when and how atmospheric oxygen (O2) first approached modern levels (∼21%) remains unresolved. Redox proxy data indicate the deep oceans were oxygenated during 435–392 Ma, and the appearance of fossil charcoal indicates O2 >15–17% by 420–400 Ma. However, existing models have failed to predict oxygenation at this time. Here we show that the earliest plants, which colonized the land surface from ∼470 Ma onward, were responsible for this mid-Paleozoic oxygenation event, through greatly increasing global organic carbon burial—the net long-term source of O2. We use a trait-based ecophysiological model to predict that cryptogamic vegetation cover could have achieved ∼30% of today’s global terrestrial net primary productivity by ∼445 Ma. Data from modern bryophytes suggests this plentiful early plant material had a much higher molar C:P ratio (∼2,000) than marine biomass (∼100), such that a given weathering flux of phosphorus could support more organic carbon burial. Furthermore, recent experiments suggest that early plants selectively increased the flux of phosphorus (relative to alkalinity) weathered from rocks. Combining these effects in a model of long-term biogeochemical cycling, we reproduce a sustained +2‰ increase in the carbonate carbon isotope (δ13C) record by ∼445 Ma, and predict a corresponding rise in O2 to present levels by 420–400 Ma, consistent with geochemical data. This oxygen rise represents a permanent shift in regulatory regime to one where fire-mediated negative feedbacks stabilize high O2 levels.

Long-term Aptian marine osmium isotopic record of Ontong Java Nui activity

Geology ◽  
2021 ◽  
Author(s):  
Hironao Matsumoto ◽  
Rodolfo Coccioni ◽  
Fabrizio Frontalini ◽  
Kotaro Shirai ◽  
Luigi Jovane ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Volcanic Eruptions ◽  
Hydrothermal Activity ◽  
Published Data ◽  
Isotopic Data ◽  
Oceanic Plateaus ◽  
Carbon Burial ◽  
Organic Carbon Burial ◽  
Isotopic Records

The early to mid-Aptian was punctuated by episodic phases of organic-carbon burial in various oceanographic settings, which are possibly related to massive volcanism associated with the emplacement of the Ontong Java, Manihiki, and Hikurangi oceanic plateaus in the southwestern Pacific Ocean, inferred to have formed a single plateau called Ontong Java Nui. Sedimentary osmium (Os) isotopic compositions are one of the best proxies for determining the timing of voluminous submarine volcanic episodes. However, available Os isotopic records during the age are limited to a narrow interval in the earliest Aptian, which is insufficient for the reconstruction of long-term hydrothermal activity. We document the early to mid-Aptian Os isotopic record using pelagic Tethyan sediments deposited in the Poggio le Guaine (Umbria-Marche Basin, Italy) to precisely constrain the timing of massive volcanic episodes and to assess their impact on the marine environment. Our new Os isotopic data reveal three shifts to unradiogenic values, two of which correspond to black shale horizons in the lower to mid-Aptian, namely the Wezel (herein named) and Fallot Levels. These Os isotopic excursions are ascribed to massive inputs of unradiogenic Os to the ocean through hydrothermal activity. Combining the new Os isotopic record with published data from the lowermost Aptian organic-rich interval in the Gorgo a Cerbara section of the Umbria-Marche Basin, it can be inferred that Ontong Java Nui volcanic eruptions persisted for ~5 m.y. during the early to mid-Aptian.

Enhanced paleo-wildfire occurrences caused by marine organic carbon burial during the Late Devonian Frasnian–Famennian mass extinction

2021 ◽  
Author(s):  
Man Lu ◽  
YueHan Lu ◽  
Takehitio Ikejiri ◽  
Richard Carroll
Keyword(s):  
Organic Carbon ◽  
Mass Extinction ◽  
Atmospheric Oxygen ◽  
Burial Rate ◽  
Carbon Burial ◽  
Chattanooga Shale ◽  
Chemical Index ◽  
Organic Carbon Burial ◽  
Polycyclic Aromatic ◽  
Extinction Events

<p>The Frasnian–Famennian (F–F) boundary is characterized by worldwide depositions of organic-rich strata, a series of marine anoxia events and one of the biggest five mass extinction events of the Phanerozoic. Due to the enhanced burial of organic matter, a coeval positive carbon isotope (δ<sup>13</sup>C) excursion occurred around the F–F boundary, raising questions about carbon cycle feedbacks during the mass extinction. In this study, we test the hypothesis that enhanced burial organic carbon during the F–F mass extinction led to the rise of paleo-wildfire occurrences. Here, we reconstructed paleo-wildfire changes across the F–F boundary via analyzing fossil charcoal (inertinites) and pyrogenic polycyclic aromatic hydrocarbons (PAHs) from an Upper Devonian Chattanooga Shale in the southern Appalachian Basin. Our data show low abundances of inertinites and pyrogenic PAHs before the F–F transition and an increasing trend during the F–F transition, followed by a sustained enhancement through the entire Famennian interval. The changes in paleo-wildfire proxies suggest a rise of wildfires starting from the F–F transition. Furthermore, we quantified the amount of organic carbon burial required to drive the observed δ<sup>13</sup>C excursion using a forward box model. The modeling results show an increased carbon burial rate after the onset of the F–F transition and peaking during its termination. The comparison of the carbon burial rate and wildfire proxies indicates that widespread organic carbon burial during the F–F transition might cause elevated atmospheric oxygen levels and hence increased occurrences of wildfires. In addition, chemical index alteration index and plant biomarkers suggest a drying climate initiated during the F–F transition, implying that the enhanced carbon burial probably result in the climate change and amplify the wildfire occurrences.</p>

scholarly journals Reduced carbon cycle resilience across the Palaeocene–Eocene Thermal Maximum

2018 ◽  
Vol 14 (10) ◽  
pp. 1515-1527 ◽  
Author(s):  
David I. Armstrong McKay ◽  
Timothy M. Lenton
Keyword(s):  
Organic Carbon ◽  
Carbon Cycle ◽  
Deep Ocean ◽  
Tipping Point ◽  
Tipping Points ◽  
Carbon Burial ◽  
Thermal Maximum ◽  
Organic Carbon Burial ◽  
Carbon Release ◽  
Hyperthermal Events

Abstract. Several past episodes of rapid carbon cycle and climate change are hypothesised to be the result of the Earth system reaching a tipping point beyond which an abrupt transition to a new state occurs. At the Palaeocene–Eocene Thermal Maximum (PETM) at ∼56 Ma and at subsequent hyperthermal events, hypothesised tipping points involve the abrupt transfer of carbon from surface reservoirs to the atmosphere. Theory suggests that tipping points in complex dynamical systems should be preceded by critical slowing down of their dynamics, including increasing temporal autocorrelation and variability. However, reliably detecting these indicators in palaeorecords is challenging, with issues of data quality, false positives, and parameter selection potentially affecting reliability. Here we show that in a sufficiently long, high-resolution palaeorecord there is consistent evidence of destabilisation of the carbon cycle in the ∼1.5 Myr prior to the PETM, elevated carbon cycle and climate instability following both the PETM and Eocene Thermal Maximum 2 (ETM2), and different drivers of carbon cycle dynamics preceding the PETM and ETM2 events. Our results indicate a loss of “resilience” (weakened stabilising negative feedbacks and greater sensitivity to small shocks) in the carbon cycle before the PETM and in the carbon–climate system following it. This pre-PETM carbon cycle destabilisation may reflect gradual forcing by the contemporaneous North Atlantic Volcanic Province eruptions, with volcanism-driven warming potentially weakening the organic carbon burial feedback. Our results are consistent with but cannot prove the existence of a tipping point for abrupt carbon release, e.g. from methane hydrate or terrestrial organic carbon reservoirs, whereas we find no support for a tipping point in deep ocean temperature.

Exploring the Growing Role of Terrestrial Carbon Across North Atlantic Fjords

2020 ◽  
Author(s):  
Craig Smeaton ◽  
William Austin
Keyword(s):  
Organic Carbon ◽  
Marine Environment ◽  
North Atlantic ◽  
Planetary Science ◽  
Terrestrial Environment ◽  
Carbon Burial ◽  
Organic Carbon Burial ◽  
Fjord Sediments

<p>Fjords are recognized as globally significant hotspots for the burial (Smith et al., 2015) and long-term storage (Smeaton et al., 2017) of marine and terrestrially derived organic carbon (OC). By trapping and locking away OC over geological timescales, fjord sediments provide a potentially important yet largely overlooked climate regulation service. The proximity of fjords to the terrestrial environment in combination with their geomorphology and hydrography results in the fjordic sediments being subsidized with organic carbon (OC) from the terrestrial environment. This terrestrial OC (OC<sub>terr</sub>) transferred to the marine environment has traditionally be considered lost to the atmosphere in the form of CO<sub>2</sub> in most carbon (C) accounting schemes yet globally it is estimated that 55% of OC trapped in fjord sediments is derived from terrestrial sources (Cui et al., 2016). So is this terrestrial OC truly lost? Here, we estimate the quantity of OC<sub>terr</sub> held within North Atlantic fjords with the aim of better understanding the recent and long-term role of the terrestrial environment in the evolution of these globally significant sedimentary OC stores. By understanding this subsidy of OC from the terrestrial to the marine environment we can take the first steps in quantifying the terrestrial OC stored in fjords and the wider coastal marine environment.</p><p>Cui, X., Bianchi, T.S., Savage, C. and Smith, R.W., 2016. Organic carbon burial in fjords: Terrestrial versus marine inputs. <em>Earth and Planetary Science Letters</em>, <em>451</em>, pp.41-50.</p><p>Smeaton, C., Austin, W.E., Davies, A., Baltzer, A., Howe, J.A. and Baxter, J.M., 2017. Scotland's forgotten carbon: a national assessment of mid-latitude fjord sedimentary stocks. <em>Biogeosciences</em>.</p><p>Smith, R.W., Bianchi, T.S., Allison, M., Savage, C. and Galy, V., 2015. High rates of organic carbon burial in fjord sediments globally. <em>Nature Geoscience</em>, <em>8</em>(6), p.450.</p><p> </p>

scholarly journals Continental erosion and the Cenozoic rise of marine diatoms

2015 ◽  
Vol 112 (14) ◽  
pp. 4239-4244 ◽  
Author(s):  
Pedro Cermeño ◽  
Paul G. Falkowski ◽  
Oscar E. Romero ◽  
Morgan F. Schaller ◽  
Sergio M. Vallina
Keyword(s):  
Silicic Acid ◽  
Lithium Isotope ◽  
Marine Diatoms ◽  
Carbon Burial ◽  
Input Flux ◽  
Organic Carbon Burial ◽  
Isotope Record ◽  
Cenozoic Era ◽  
Global Carbon

Marine diatoms are silica-precipitating microalgae that account for over half of organic carbon burial in marine sediments and thus they play a key role in the global carbon cycle. Their evolutionary expansion during the Cenozoic era (66 Ma to present) has been associated with a superior competitive ability for silicic acid relative to other siliceous plankton such as radiolarians, which evolved by reducing the weight of their silica test. Here we use a mathematical model in which diatoms and radiolarians compete for silicic acid to show that the observed reduction in the weight of radiolarian tests is insufficient to explain the rise of diatoms. Using the lithium isotope record of seawater as a proxy of silicate rock weathering and erosion, we calculate changes in the input flux of silicic acid to the oceans. Our results indicate that the long-term massive erosion of continental silicates was critical to the subsequent success of diatoms in marine ecosystems over the last 40 My and suggest an increase in the strength and efficiency of the oceanic biological pump over this period.

scholarly journals Possible link between Earth’s rotation rate and oxygenation

2021 ◽  
Author(s):  
J. M. Klatt ◽  
A. Chennu ◽  
B. K. Arbic ◽  
B. A. Biddanda ◽  
G. J. Dick
Keyword(s):  
Metabolic Regulation ◽  
Atmospheric Oxygen ◽  
Dynamic Modelling ◽  
Low Oxygen ◽  
Geological Time ◽  
Net Productivity ◽  
Carbon Burial ◽  
Organic Carbon Burial ◽  
Solute Fluxes ◽  
Benthic Ecosystems

AbstractThe biotic and abiotic controls on major shifts in atmospheric oxygen and the persistence of low-oxygen periods over a majority of Earth’s history remain under debate. Explanations of Earth’s stepwise pattern of oxygenation have mostly neglected the effect of changing diel illumination dynamics linked to daylength, which has increased through geological time due to Earth’s rotational deceleration caused by tidal friction. Here we used microsensor measurements and dynamic modelling of interfacial solute fluxes in cyanobacterial mats to investigate the effect of changing daylength on Precambrian benthic ecosystems. Simulated increases in daylength across Earth’s historical range boosted the diel benthic oxygen export, even when the gross photosynthetic production remained constant. This fundamental relationship between net productivity and daylength emerges from the interaction of diffusive mass transfer and diel illumination dynamics, and is amplified by metabolic regulation and microbial behaviour. We found that the resultant daylength-driven surplus organic carbon burial could have shaped the increase in atmospheric oxygen that occurred during the Great and Neoproterozoic Oxidation Events. Our suggested mechanism, which links the coinciding increases in daylength and atmospheric oxygen via enhanced net productivity, reveals a possible contribution of planetary mechanics to the evolution of Earth’s biology and geochemistry.

What Controls Atmospheric Oxygen Concentrations?

2017 ◽  
Author(s):  
Donald Eugene Canfield
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Black Sea ◽  
Atmospheric Oxygen ◽  
Fundamental Question ◽  
The Black Sea ◽  
Microbial Process ◽  
The Past ◽  
Carbon Burial ◽  
Organic Carbon Burial

This chapter deals with the fundamental question of why there is oxygen in the atmosphere at all. It seeks to identify the main processes controlling the oxygen concentration. Plants and cyanobacteria produce the oxygen, but it accumulates only because some of the original photosynthetically produced organic matter is buried and preserved in sediments. Another oxygen source is an anaerobic microbial process called sulfate reduction that respires organic matter using sulfate and produces sulfide. This process is quite common in nature but are most prominent in relatively isolated basins like the Black Sea, and in most marine sediments at depths where oxygen has been consumed by respiration. If there is iron around, the sulfide reacts with the iron, forming a mineral called pyrite. While organic carbon burial has been the main oxygen source to the atmosphere over the past several hundred million years, for some intervals further back in time, pyrite burial may well have dominated as an oxygen source.

scholarly journals The rise of angiosperms strengthened fire feedbacks and improved the regulation of atmospheric oxygen

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Claire M. Belcher ◽  
Benjamin J. W. Mills ◽  
Rayanne Vitali ◽  
Sarah J. Baker ◽  
Timothy M. Lenton ◽  
...  
Keyword(s):  
Atmospheric Oxygen ◽  
Feedback Mechanism ◽  
Biogeochemical Model ◽  
Fossil Carbon ◽  
Biogeochemical Models ◽  
Carbon Burial ◽  
Plant Groups ◽  
Organic Carbon Burial ◽  
Closed Canopy ◽  
Fire Feedbacks

AbstractThe source of oxygen to Earth’s atmosphere is organic carbon burial, whilst the main sink is oxidative weathering of fossil carbon. However, this sink is to insensitive to counteract oxygen rising above its current level of about 21%. Biogeochemical models suggest that wildfires provide an additional regulatory feedback mechanism. However, none have considered how the evolution of different plant groups through time have interacted with this feedback. The Cretaceous Period saw not only super-ambient levels of atmospheric oxygen but also the evolution of the angiosperms, that then rose to dominate Earth’s ecosystems. Here we show, using the COPSE biogeochemical model, that angiosperm-driven alteration of fire feedbacks likely lowered atmospheric oxygen levels from ~30% to 25% by the end of the Cretaceous. This likely set the stage for the emergence of closed-canopy angiosperm tropical rainforests that we suggest would not have been possible without angiosperm enhancement of fire feedbacks.

A tentative attempt to better trace the late Pleistocene oxygen cycle

2021 ◽  
Author(s):  
Ji-Woong Yang ◽  
Thomas Extier ◽  
Martin Kölling ◽  
Amaëlle Landais ◽  
Gaëlle Leloup ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Late Pleistocene ◽  
Global Ocean ◽  
Geological Time Scale ◽  
Sources And Sinks ◽  
The Earth ◽  
Carbon Burial ◽  
Organic Carbon Burial ◽  
Burial Flux

<p>Atmospheric abundance of oxygen (O<sub>2</sub>) has been co-evolved with different aspects of the Earth system since appearance of oxygenic photosynthesis by cyanobacteria around 2.4 10<sup>9</sup> years before present (Ga). Therefore, much attention has been paid to understand the changes in O<sub>2</sub> and the underlying mechanisms over the Earth’s history. The pioneering work by Stolper et al. (2016) revealed the long-term decreasing trend of O<sub>2</sub> mixing ratios over the last 800,000 years using the ice-core composite record of molar ratios of O<sub>2</sub> and nitrogen (δ(O<sub>2</sub>/N<sub>2</sub>)), implying a slight imbalance between sources and sinks. Over geological time scale, O<sub>2</sub> is mainly controlled by burial and oxidation of organic carbon and pyrite, but also by oxidation of volcanic gases and sedimentary rocks. Nevertheless, the O<sub>2</sub> cycle of the late Pleistocene has not been well understood, partly due to the lack of knowledge about the individual sources and sinks. Since then, Kölling et al. (2019) proposed a simple model to estimate the O<sub>2</sub> release/uptake fluxes due to the pyrite burial/oxidation that predicts up to ~70% of the O<sub>2</sub> decrease of the last 800,000 years could be explained by pyrite burial/oxidation.</p><p>Building on this, we present here our preliminary, tentative attempt for reconstruction of the net organic carbon burial flux over the last 800,000 years by combining available information (including new δ(O<sub>2</sub>/N<sub>2</sub>) data) and assuming constant O<sub>2</sub> fluxes associated with volcanic outgassing and rock weathering. The long-term organic carbon burial flux trend obtained with our new calculations is similar to the global ocean δ<sup>13</sup>C records but also to simulations using a conceptual carbon cycle model (Paillard, 2017). These results partly support the geomorphological hypothesis that the major sea-level drops during the earlier period of the last 800,000 years lead to enhanced organic carbon burial, and that significant changes in the net organic carbon happen around Marine Isotopic Stage (MIS) 13. In addition, we present the long-term decreasing trend of the global biosphere productivity, or gross photosynthetic O<sub>2</sub> flux, reconstructed from new measurements of triple-isotope composition of atmospheric O<sub>2</sub> trapped in ice cores. As the largest O<sub>2</sub> flux, the observed decrease in gross photosynthesis requires to be compensated by parallel reduction of global ecosystem respiration.</p>

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