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A committed fourfold increase in ocean oxygen loss

Abstract.

"Less than a quarter of ocean deoxygenation that will ultimately be caused by historical CO2 emissions is already realized, according to millennial-scale model simulations that assume zero CO2 emissions from year 2021 onwards. About 80% of the committed oxygen loss occurs below 2000 m depth, where a more sluggish overturning circulation will increase water residence times and accumulation of respiratory oxygen demand. According to the model results, the deep ocean will thereby lose more than 10% of its pre-industrial oxygen content even if CO2 emissions and thus global warming[...]"

 

Source: Nature Communications
Authors: Andreas Oschlies 
DOI: https://doi.org/10.1038/s41467-021-22584-4

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Pervasive distribution of polyester fibres in the Arctic Ocean is driven by Atlantic inputs

Abstract.

"Microplastics are increasingly recognized as ubiquitous global contaminants, but questions linger regarding their source, transport and fate. We document the widespread distribution of microplastics in near-surface seawater from 71 stations across the European and North American Arctic - including the North Pole. We also characterize samples to a depth of 1,015 m in the Beaufort Sea. Particle abundance correlated with longitude, with almost three times more particles in the eastern Arctic compared to the west. Polyester comprised[...]"

 

Source: Nature Communications
Authors: Peter S. Ross et al.
DOI: https://doi.org/10.1038/s41467-020-20347-1

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Status and trends of Arctic Ocean environmental change and its impacts on marine biogeochemistry: Findings from the ArCS project

Abstract.

"Ocean observation research theme under ArCS project, “Theme 4: Observational research on Arctic Ocean environmental changes”, aimed to elucidate the status and trends of ongoing Arctic Ocean environmental changes and to evaluate their impacts on Arctic marine ecosystem and the global climate system. For these purposes, we conducted field observations, mooring observations, laboratory experiments, numerical modeling, and international collaborative research focusing on the Pacific Arctic[...]"

 

Source: Science Direct
Authors: Takashi Kikuchi et al.
DOI: https://doi.org/10.1016/j.polar.2021.100639

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Glacial deep ocean deoxygenation driven by biologically mediated air–sea disequilibrium

Abstract.

"Deep ocean deoxygenation inferred from proxies has been used to support the hypothesis that a lower atmospheric carbon dioxide during glacial times was due to an increase in the strength of the ocean’s biological pump. This relies on the assumption that surface ocean oxygen (O2) is equilibrated with the atmosphere such that any O2 deficiency observed in deep waters is a result of organic matter respiration, which consumes O2 and produces dissolved inorganic carbon. However, this assumption has been shown to be imperfect because of disequilibrium. Here we used an Earth system[...]"

 

Source: Nature Geoscience 
Authors: Ellen Cliff et al.
DOI: https://doi.org/10.1038/s41561-020-00667-z

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Phosphorus-limited conditions in the early Neoproterozoic ocean maintained low levels of atmospheric oxygen

Abstract.

"The redox chemistry of anoxic continental margin settings evolved from widespread sulfide-containing (euxinic) conditions to a global ferruginous (iron-containing) state in the early Neoproterozoic era (from ~1 to 0.8 billion years ago). Ocean redox chemistry exerts a strong control on the biogeochemical cycling of phosphorus, a limiting nutrient, and hence on primary production, but the response of the phosphorus cycle to this major ocean redox transition has not been investigated. Here, we use a geochemical[...]"

 

Source: Nature Geoscience
Authors: Romain Guilbaud et al.
DOI: https://doi.org/10.1038/s41561-020-0548-7

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Subseafloor life and its biogeochemical impacts

Abstract.

"Subseafloor microbial activities are central to Earth’s biogeochemical cycles. They control Earth’s surface oxidation and major aspects of ocean chemistry. They affect climate on long timescales and play major roles in forming and destroying economic resources. In this review, we evaluate present understanding of subseafloor microbes and their activities, identify research gaps, and recommend approaches to filling those gaps. [...]"

Source: Nature Communications
Authors: Steven D’Hondt et al.
DOI: 10.1038/s41467-019-11450-z

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Stratifying ocean sampling globally and with depth to account for environmental variability

Abstract.

"With increasing depth, the ocean is less sampled for physical, chemical and biological variables. Using the Global Marine Environmental Datasets (GMED) and Ecological Marine Units (EMUs), we show that spatial variation in environmental variables decreases with depth. This is also the case over temporal scales because seasonal change, surface weather conditions, and biological activity are highest in shallow depths. [...]"

Source: Scientific Reports
Authors: Mark John Costello et al.
DOI: 10.1038/s41598-018-29419-1

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Climate and marine biogeochemistry during the Holocene from transient model simulations

Abstract.

"Climate and marine biogeochemistry changes over the Holocene are investigated based on transient global climate and biogeochemistry model simulations over the last 9500 years. The simulations are forced by accelerated and non-accelerated orbital parameters, respectively, and atmospheric pCO2, CH4, and N2O. The analysis focusses on key climatic parameters of relevance to the marine biogeochemistry, and on the physical and biogeochemical processes that drive atmosphere–ocean carbon fluxes and changes in the oxygen minimum zones (OMZs). [...]"

Source: Biogeosciences
Authors: Joachim Segschneider, Birgit Schneider, and Vyacheslav Khon
DOI: 10.5194/bg-15-3243-2018

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A Sixteen-year Decline in Dissolved Oxygen in the Central California Current

Abstract.

"A potential consequence of climate change is global decrease in dissolved oxygen at depth in the oceans due to changes in the balance of ventilation, mixing, respiration, and photosynthesis. We present hydrographic cruise observations of declining dissolved oxygen collected along CalCOFI Line 66.7 (Line 67) off of Monterey Bay, in the Central California Current region, and investigate likely mechanisms.  [...]"

Source: Scientific Reports
Authors: Alice S. Ren et al.
DOI: 10.1038/s41598-018-25341-8

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Coupling of oceanic carbon and nitrogen facilitates spatially resolved quantitative reconstruction of nitrate inventories

Abstract.

"Anthropogenic impacts are perturbing the global nitrogen cycle via warming effects and pollutant sources such as chemical fertilizers and burning of fossil fuels. Understanding controls on past nitrogen inventories might improve predictions for future global biogeochemical cycling. Here we show the quantitative reconstruction of deglacial bottom water nitrate concentrations from intermediate depths of the Peruvian upwelling region, using foraminiferal pore density. [...]"

Source: Nature Communications
Authors: Nicolaas Glock et al.
DOI: 10.1038/s41467-018-03647-5

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