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Oceanic organic carbon as a possible first-order control on the carbon cycle during the Bathonian–Callovian

Abstract.

"Oceans are the largest, readily exchangeable, superficial carbon reservoir; a current challenge in investigating past and present environments and predict future evolution relates to the role of oceanic carbon in regulating Earths' carbon cycle and climate. At least one paired δ13Ccarb-TOC decoupling event is noted in the Late Bathonian–Early Callovian. [...]"

Source: Global and Planetary Change
Authors: Ricardo L.Silva et al.
DOI: 10.1016/j.gloplacha.2019.103058


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Constraining the Oceanic Uptake and Fluxes of Greenhouse Gases by Building an Ocean Network of Certified Stations:

The Ocean Component of the Integrated Carbon Observation System, ICOS-Oceans

Abstract.

"The European Research Infrastructure Consortium “Integrated Carbon Observation System” (ICOS) aims at delivering high quality greenhouse gas (GHG) observations and derived data products (e.g., regional GHG-flux maps) for constraining the GHG balance on a European level, on a sustained long-term basis. The marine domain (ICOS-Oceans) currently consists of 11 Ship of Opportunity lines (SOOP – Ship of Opportunity Program) and 10 Fixed Ocean Stations (FOSs) spread across European waters, including the North Atlantic and Arctic Oceans and the Barents, North, Baltic, and Mediterranean Seas. [...]"

Source: Frontiers in Marine Science
Authors: Tobias Steinhoff et al.
DOI: 10.3389/fmars.2019.00544

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Anoxygenic photosynthesis and the delayed oxygenation of Earth’s atmosphere

Abstract.

"The emergence of oxygenic photosynthesis created a new niche with dramatic potential to transform energy flow through Earth’s biosphere. However, more primitive forms of photosynthesis that fix CO2 into biomass using electrons from reduced species like Fe(II) and H2 instead of water would have competed with Earth’s early oxygenic biosphere for essential nutrients. [...]"

Source: Nature Communications
Authors: Kazumi Ozaki et al.
DOI: 10.1038/s41467-019-10872-z

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Multi-faceted particle pumps drive carbon sequestration in the ocean

Abstract.

"The ocean’s ability to sequester carbon away from the atmosphere exerts an important control on global climate. The biological pump drives carbon storage in the deep ocean and is thought to function via gravitational settling of organic particles from surface waters. However, the settling flux alone is often insufficient to balance mesopelagic carbon budgets or to meet the demands of subsurface biota. [...]"

Source: Nature
Authors: Philip W. Boyd et al.
DOI: 10.1038/s41586-019-1098-2

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Organic carbon recycling in Baltic Sea sediments – An integrated estimate on the system scale based on in situ measurements

Abstract.

"In situ measured benthic fluxes of dissolved inorganic carbon (DIC), a proxy for organic carbon (OC) oxidation or recycling rates, are used together with burial rates based on measured sediment accumulation rates (SAR) and vertical distribution of OC in the sediment solid phase to construct a benthic OC budget for the Baltic Sea system. [...]"

Source: Marine Chemistry
Authors: Madeleine M. Nilsson et al.
DOI: 10.1016/j.marchem.2018.11.004

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Carbon cycling in the North American coastal ocean: a synthesis

Abstract.

"A quantification of carbon fluxes in the coastal ocean and across its boundaries with the atmosphere, land, and the open ocean is important for assessing the current state and projecting future trends in ocean carbon uptake and coastal ocean acidification, but this is currently a missing component of global carbon budgeting. This synthesis reviews recent progress in characterizing these carbon fluxes for the North American coastal ocean. [...]"

Source: Biogeosciences
Authors: Katja Fennel et al.
DOI: 10.5194/bg-16-1281-2019

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Phytoplankton calcifiers control nitrate cycling and the pace of transition in warming icehouse and cooling greenhouse climates

Abstract.

"Phytoplankton calcifiers contribute to global carbon cycling through their dual formation of calcium carbonate and particulate organic carbon (POC). The carbonate might provide an efficient export pathway for the associated POC to the deep ocean, reducing the particles' exposure to biological degradation in the upper ocean and increasing the particle settling rate. Previous work has suggested ballasting of POC by carbonate might increase in a warming climate, in spite of increasing carbonate dissolution rates, because calcifiers benefit from the widespread nutrient limitation arising from stratification. [...]"

Source: Biogeosciences
Authors: Karin F. Kvale et al.
DOI: 10.5194/bg-16-1019-2019

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Bacterial fermentation and respiration processes are uncoupled in anoxic permeable sediments

Abstract.

"Permeable (sandy) sediments cover half of the continental margin and are major regulators of oceanic carbon cycling. The microbial communities within these highly dynamic sediments frequently shift between oxic and anoxic states, and hence are less stratified than those in cohesive (muddy) sediments. A major question is, therefore, how these communities maintain metabolism during oxic–anoxic transitions. [...]"

Source: Nature Microbiology
Authors: Adam J. Kessler et al.
DOI: 10.1038/s41564-019-0391-z

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Evolving paradigms in biological carbon cycling in the ocean

Abstract.

"Carbon is a keystone element in global biogeochemical cycles. It plays a fundamental role in biotic and abiotic processes in the ocean, which intertwine to mediate the chemistry and redox status of carbon in the ocean and the atmosphere. The interactions between abiotic and biogenic carbon (e.g. CO2, CaCO3, organic matter) in the ocean are complex, and there is a half-century-old enigma about the existence of a huge reservoir of recalcitrant dissolved organic carbon (RDOC) that equates to the magnitude of the pool of atmospheric CO2. The concepts of the biological carbon pump (BCP) and the microbial loop (ML) shaped our understanding of the marine carbon cycle.  [...]"

Source: National Science Review
Authors: Chuanlun Zhang et al.
DOI: 10.1093/nsr/nwy074

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Earth's oxygen increased in gradual steps rather than big bursts

"A carbon cycle anomaly discovered in carbonate rocks of the Neoproterozoic Hüttenberg Formation of north-eastern Namibia follows a pattern similar to that found right after the Great Oxygenation Event, hinting at new evidence for how Earth's atmosphere became fully oxygenated.

By using the Hüttenberg Formation, which formed between a billion and half a billion years ago, to study the time between Earth's change from an anoxic environment (i.e. one lacking oxygen) to a more hospitable environment that heralded the animal kingdom, a team of researchers led by Dr. Huan Cui of the NASA Astrobiology Institute at the University of Wisconsin–Madison discovered a sustained, high level of carbon. This influx of carbon, coupled with changes in other elements, indicates how changing levels of oceanic oxygen may have lent a helping hand to early animal evolution. [...]"

Source: Phys.org

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