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Manganous water column in the Tethys Ocean during the Permian-Triassic transition
Abstract.
"Ocean anoxia was one of the key killing mechanisms responsible for the end-Permian mass extinction (∼252 Ma). However, the temporal evolution and the triggering mechanisms of the end-Permian anoxia are controversial, with the current view being that the water column deoxygenation was a spatially and temporally heterogeneous event. Here, we use cerium-anomalies, uranium contents and rare earth element and yttrium (REY) compositions measured on the carbonate fraction of samples from two marine sections in Armenia and South China to constrain the evolution of end-Permian marine anoxia. [...]".
Source: Science Direct
Authors: Johann Müller et al.
DOI: https://doi.org/10.1016/j.gloplacha.2023.104067
Increasing hypoxia on global coral reefs under ocean warming
Abstract.
"Ocean deoxygenation is predicted to threaten marine ecosystems globally. However, current and future oxygen concentrations and the occurrence of hypoxic events on coral reefs remain underexplored. Here, using autonomous sensor data to explore oxygen variability and hypoxia exposure at 32 representative reef sites, we reveal that hypoxia is already pervasive on many reefs. Eighty-four percent of reefs experienced weak to moderate (≤153 µmol O2 kg−1to ≤92 µmol O2 kg−1) hypoxia and 13% experienced severe (≤61 µmol O2 kg−1) hypoxia. Under different climate change scenarios based on four Shared Socioeconomic Pathways (SSPs) [...]".
Source: Nature
Authors: Ariel K. Pezner et al.
DOI: https://doi.org/10.1038/s41558-023-01619-2
Persistent eutrophication and hypoxia in the coastal ocean
Abstract.
"Coastal eutrophication and hypoxia remain a persistent environmental crisis despite the great efforts to reduce nutrient loading and mitigate associated environmental damages. Symptoms of this crisis have appeared to spread rapidly, reaching developing countries in Asia with emergences in Southern America and Africa. The pace of changes and the underlying drivers remain not so clear. To address the gap, we review the up-to-date status and mechanisms of eutrophication and hypoxia in global coastal oceans, upon which we examine the trajectories of changes over the 40 years or longer in six model coastal systems [...]".
Source: Cambridge University Press
Authors: Minhan Dai et al.
DOI: https://doi.org/10.1017/cft.2023.7
Oxygenation of the Earth aided by mineral–organic carbon preservation
Abstract.
"Photosynthesis produces molecular oxygen, but it is the burial of organic carbon in sediments that has allowed this O2 to accumulate in Earth’s atmosphere. Yet many direct controls on the preservation and burial of organic carbon have not been explored in detail. For modern Earth, it is known that reactive iron phases are important for organic carbon preservation, suggesting that the availability of particulate iron could be an important factor for the oxygenation of the oceans and atmosphere over Earth history. Here we develop a theoretical model to investigate the effect of mineral–organic preservation on the oxygenation of the Earth, supported by a proxy [...]".
Source: Nature
Authors: Mingyu Zhao et al.
DOI: https://doi.org/10.1038/s41561-023-01133-2
Frontiers in Marine Science special issue on ocean deoxygenation: Call for papers closing tomorrow
Call for paper manuscripts closing tomorrow
This is a quick reminder that the call for paper manuscripts for a special issue on "Constraining Uncertainties in Hindcasts and Future Projections of Marine Deoxygenation" in Frontiers in Marine Science ends tomorrow, 7 April 2023.
Further information: https://www.frontiersin.org/research-topics/24190/constraining-uncertainties-in-hindcasts-and-future-projections-of-marine-deoxygenation.
A study of hypoxia and ocean acidification related physico-chemical parameters in selected coastal waters around Mauritius
Abstract.
"Sea water samples were collected at five stations around Mauritius namely Flic-en-Flac, Albion, Mont Choisy, Trou-d’Eau-Douce and La Cambuse over 12 months from July 2021 to June 2022 for the analysis of dissolved oxygen (D.O), pH and Total alkalinity (). Albion was the only open water system whereas the others were lagoons. Summer was from November 2021 to April 2022 while the period from July 2021 to October 2021, May 2022 and June 2022 were considered to be winter. The summer mean values of sea surface temperature (SST) [...]".
Source: Science Direct
Authors: Yadhav Abhilesh Imrit et al.
DOI: https://doi.org/10.1016/j.rsma.2023.102815
Basin-scale reconstruction of euxinia and Late Devonian mass extinctions
Abstract.
"The Devonian–Carboniferous transition marks a fundamental shift in the surface environment primarily related to changes in ocean–atmosphere oxidation states, resulting from the continued proliferation of vascular land plants that stimulated the hydrological cycle and continental weathering, glacioeustasy, eutrophication and anoxic expansion in epicontinental seas, and mass extinction events. Here we present a comprehensive spatial and temporal compilation of geochemical data from 90 cores across the entire Bakken Shale (Williston Basin, North America). [...]".
Source: Nature
Authors: Swapan K. Sahoo et al.
DOI: https://doi.org/10.1038/s41586-023-05716-2
Rare earth element signatures of Doushantuo cap dolostones capture an increase in oxygen in the anoxic Ediacaran ocean
Abstract.
"The Rare Earth Element (REE) systematics of the post-Marinoan cap dolostones reflect the marine redox conditions and chemistry in the immediate aftermath of the snowball Earth. Rare earth elements and yttrium (REY) compositions in the Doushantuo cap dolostones that directly overlie Nantuo glacial diamictites in south China are determined from the inner shelf to the slope. In general, shale-normalized REY patterns (REYSN) of the cap dolostones show significant fractionations that are characterized by light REE depletion, slight middle REE enrichment relative to the light and heavy REEs, positive Eu anomalies, and slightly super-chondritic Y/Ho ratios. [...]".
Source: Science Direct
Authors: Min Ren & Ruifan Li
DOI: https://doi.org/10.1016/j.sedgeo.2023.106343
A hydrogenotrophic Sulfurimonas is globally abundant in deep-sea oxygen-saturated hydrothermal plumes
Abstract.
"Members of the bacterial genus Sulfurimonas (phylum Campylobacterota) dominate microbial communities in marine redoxclines and are important for sulfur and nitrogen cycling. Here we used metagenomics and metabolic analyses to characterize a Sulfurimonasfrom the Gakkel Ridge in the Central Arctic Ocean and Southwest Indian Ridge, showing that this species is ubiquitous in non-buoyant hydrothermal plumes at Mid Ocean Ridges across the global ocean. One Sulfurimonas species, USulfurimonas pluma, was found to be globally abundant and active in cold (<0−4 °C), oxygen-saturated and hydrogen-rich hydrothermal plumes. [...]".
Source: Nature
Authors: Massimiliano Molari et al.
DOI: https://doi.org/10.1038/s41564-023-01342-w
A molecular perspective on the invasibility of the southern ocean benthos: The impact of hypoxia and temperature on gene expression
Abstract.
"When an organism makes a long-distance transition to a new habitat, the associated environmental change is often marked and requires physiological plasticity of larvae, juveniles, or other migrant stages. Exposing shallow-water marine bivalves (Aequiyoldia cf. eightsii) from southern South America (SSA) and the West Antarctic Peninsula (WAP) to changes in temperature and oxygen availability, we investigated changes in gene expression in a simulated colonization experiment of the shores of a new continent after crossing of the Drake Passage, and in a warming scenario in the WAP. [...]".
Source: Frontiers
Authors: Mariano Martínez et al.
DOI: https://doi.org/10.3389/fphys.2023.1083240
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