Simulating the biogeochemical effects of volcanic CO2 degassing on the oxygen-state of the deep ocean during the Cenomanian/Turonian Anoxic Event (OAE2)

Flögel, Sascha; Wallmann, Klaus; Poulsen, Christopher J.; Zhou, Jing; Oschlies, Andreas; Voigt, Silke; Kuhnt, Wolfgang

doi:10.1016/j.epsl.2011.03.018

Cited by 63 publications

(80 citation statements)

References 81 publications

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“…1), which relates the burial to a sigmoidal function of rain rate: F B = F R 0.013 + 0.53 F 2 R /(7 + F R ) 2 . At low rain rates Dunne's data set agrees quite well with the openocean estimate by Flögel et al (2011) and with the regression derived from our of our "open ocean" data compilation. At higher rain rates, the estimate by Dunne agrees with the shelf estimate by Flögel et al (2011).…”

Section: Parameterization Of Benthic Burialsupporting

confidence: 78%

“…At low rain rates Dunne's data set agrees quite well with the openocean estimate by Flögel et al (2011) and with the regression derived from our of our "open ocean" data compilation. At higher rain rates, the estimate by Dunne agrees with the shelf estimate by Flögel et al (2011). Few observations are available in the mid-range of the rain rates between ≈ 0.01-0.1 mmol P m −2 d −1 , where the function by Dunne deviates from the other parameterizations.…”

Section: Parameterization Of Benthic Burialsupporting

confidence: 78%

“…1). Restricting our regression to regions with F B < 250 mmol C m −2 yr −1 , i.e., placing more emphasis on the open ocean, results in a much weaker dependence of burial on rain rate (α = 0.0176 (mmol P m −2 d −1 ) 1−β ), β = 1.022, r 2 = 0.61) than the regression for the full domain, and is comparable to the open ocean estimate by Flögel et al (2011) with α = 0.024 (mmol P m −2 d −1 ) 1−β (converted with a C : P ratio of 106) and β = 1.05.…”

Section: Parameterization Of Benthic Burialsupporting

confidence: 57%

“…Dashed red line: regression for data compilation over regions with burial < 250 mmol C m −2 yr −1 (used in model scenario WBUR). Regressions from Flögel et al (2011) are shown as straight (open ocean) and dashed (coastal) blue line. The algorithm by Dunne et al (2007) is denoted as green line.…”

Section: Parameterization Of the Benthic Nepheloid Layermentioning

confidence: 99%

“…Figure 1 compares this relationship to other estimates of burial vs. rain rate. Flögel et al (2011) divided the ocean into two domains, namely the coastal and the open ocean, for which they derived two separate empirical relationships between F B and F R . The two descriptions by Flögel et al (2011) have very similar exponents β, but very different offsets α (see Fig.…”

Section: Parameterization Of Benthic Burialmentioning

confidence: 99%

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Swept under the carpet: organic matter burial decreases global ocean biogeochemical model sensitivity to remineralization length scale

Kriest

Oschlies

2013

Biogeosciences

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Abstract. Although of substantial importance for marine tracer distributions and eventually global carbon, oxygen, and nitrogen fluxes, the interaction between sinking and remineralization of organic matter, benthic fluxes and burial is not always represented consistently in global biogeochemical models. We here aim to investigate the relationships between these processes with a suite of global biogeochemical models, each simulated over millennia, and compared against observed distributions of pelagic tracers and benthic and pelagic fluxes.We concentrate on the representation of sediment-water interactions in common numerical models, and investigate their potential impact on simulated global sediment-water fluxes and nutrient and oxygen distributions. We find that model configurations with benthic burial simulate global oxygen well over a wide range of possible sinking flux parameterizations, making the model more robust with regard to uncertainties about the remineralization length scale. On a global scale, burial mostly affects oxygen in the meso-to bathypelagic zone. While all model types show an almost identical fit to observed pelagic particle flux, and the same sensitivity to particle sinking speed, comparison to observational estimates of benthic fluxes reveals a more complex pattern, but definite interpretation is not straightforward because of heterogeneous data distribution and methodology. Still, evaluating model results against observed pelagic and benthic fluxes of organic matter can complement model assessments based on more traditional tracers such as nutrients or oxygen. Based on a combined metric of dissolved tracers and biogeochemical fluxes, we here identify two model descriptions of burial as suitable candidates for further experiments and eventual model refinements.

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Section: Parameterization Of Benthic Burialsupporting

confidence: 78%

Section: Parameterization Of Benthic Burialsupporting

confidence: 78%

Section: Parameterization Of Benthic Burialsupporting

confidence: 57%

Section: Parameterization Of the Benthic Nepheloid Layermentioning

confidence: 99%

Section: Parameterization Of Benthic Burialmentioning

confidence: 99%

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Swept under the carpet: organic matter burial decreases global ocean biogeochemical model sensitivity to remineralization length scale

Kriest

Oschlies

2013

Biogeosciences

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Enhanced N₂-fixation and NH4+ recycling during oceanic anoxic event 2 in the proto-North Atlantic

Baroni

Tsandev

Slomp

2014

Geochem. Geophys. Geosyst.

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Evidence from sediment core records and model studies suggests that increased nutrient supply played a key role in the initiation of the Cenomanian-Turonian oceanic anoxic event 2 (OAE2; 94 Ma). However, the relative roles of nitrogen (N) and phosphorus (P) availability in controlling primary productivity during the event are not fully understood. Here we expand an existing multibox model of the coupled cycles of P, carbon, and oxygen in the proto-North Atlantic by adding the marine N cycle. With the updated version of the model, we test the hypothesis that enhanced availability of P can fuel N 2 -fixation, increase primary productivity and drive large parts of the proto-North Atlantic to anoxia during OAE2. In a sensitivity analysis, we demonstrate that N dynamics in the proto-North Atlantic respond strongly to variations in oxygen and P supply from the Pacific Ocean and to changes in circulation. The implemented N cycle weakly modifies the carbon cycle, implying that P was the major nutrient controlling primary productivity during OAE2. Our model suggests that both N 2 -fixation and upwelling of recycled NH 1 4 were enhanced during OAE2 and that N 2 -fixation was the major source of N in the proto-North Atlantic. Denitrification was more important in the water column than in sediments, with high rates in the open ocean and in the Western Interior. High P inputs in the proto-North Atlantic led to widespread N 2 -fixation, which more than compensated for the loss of N through denitrification. As a consequence, rates of primary productivity and organic carbon burial were high.

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Axial obliquity control on the greenhouse carbon budget through middle‐ to high‐latitude reservoirs

et al. 2015

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Carbon sources and sinks are key components of the climate feedback system, yet their response to external forcing remains poorly constrained, particularly for past greenhouse climates. Carbon-isotope data indicate systematic, million-year-scale transfers of carbon between surface reservoirs during and immediately after the Late Cretaceous thermal maximum (peaking in the Cenomanian-Turonian, circa 97-91 million years, Myr, ago). Here we calibrate Albian to Campanian (108-72 Myr ago) high-resolution carbon isotope records with a refined chronology and demonstrate how net transfers between reservoirs are plausibly controlled by~1 Myr changes in the amplitude of axial obliquity. The amplitude-modulating terms are absent from the frequency domain representation of insolation series and require a nonlinear, cumulative mechanism to become expressed in power spectra of isotope time series. Mass balance modeling suggests that the residence time of carbon in the ocean-atmosphere system is-by itself-insufficient to explain the Myr-scale variability. It is proposed that the astronomical control was imparted by a transient storage of organic matter or methane in quasi-stable reservoirs (wetlands, soils, marginal zones of marine euxinic strata, and potentially permafrost) that responded nonlinearly to obliquity-driven changes in high-latitude insolation and/or meridional insolation gradients. While these reservoirs are probably underrepresented in the geological record due to their quasi-stable character, they might have provided an important control on the dynamics and stability of the greenhouse climate.

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Simulating the biogeochemical effects of volcanic CO2 degassing on the oxygen-state of the deep ocean during the Cenomanian/Turonian Anoxic Event (OAE2)

Cited by 63 publications

References 81 publications

Swept under the carpet: organic matter burial decreases global ocean biogeochemical model sensitivity to remineralization length scale

Swept under the carpet: organic matter burial decreases global ocean biogeochemical model sensitivity to remineralization length scale

Enhanced N₂-fixation and NH4+ recycling during oceanic anoxic event 2 in the proto-North Atlantic

Axial obliquity control on the greenhouse carbon budget through middle‐ to high‐latitude reservoirs

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Simulating the biogeochemical effects of volcanic CO2 degassing on the oxygen-state of the deep ocean during the Cenomanian/Turonian Anoxic Event (OAE2)

Cited by 63 publications

References 81 publications

Swept under the carpet: organic matter burial decreases global ocean biogeochemical model sensitivity to remineralization length scale

Swept under the carpet: organic matter burial decreases global ocean biogeochemical model sensitivity to remineralization length scale

Enhanced N2-fixation and NH4+ recycling during oceanic anoxic event 2 in the proto-North Atlantic

Axial obliquity control on the greenhouse carbon budget through middle‐ to high‐latitude reservoirs

Contact Info

Product

Resources

About

Enhanced N₂-fixation and NH4+ recycling during oceanic anoxic event 2 in the proto-North Atlantic