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Nitrogen isotope evidence for oxygenated upper ocean during the Cryogenian interglacial period

Abstract.

"The Cryogenian interglacial period have witnessed dramatic changes in climate, oceanic environment and biological evolution. The nitrogen isotopic composition, as an important biogeochemical proxy, has the potential to track both the nutrient cycling and redox conditions in the past. However, nitrogen isotopic data during this interglacial time is rather limited. Here, we present integrated data for nitrogen isotopes (δ15N), as well as organic carbon isotopes (δ13Corg), iron (Fe) speciation, pyrite morphology and trace elements from the Cryogenian interglacial Datangpo Formation derived from a drill core from South China to figure out the nitrogen cycling and coeval redox states. [...]". 

 

Source: Science Direct 
Authors: Guangyou Zhu et al.
DOI: https://doi.org/10.1016/j.chemgeo.2022.120929

Read the full article here.


Isotopic evidence for changes in the mercury and zinc cycles during Oceanic Anoxic Event 2 in the northwestern Tethys, Austria

Abstract. 

"The Cenomanian-Turonian Oceanic Anoxic Event 2 (OAE 2, ca. 94 Ma) was one of the most extreme carbon cycle and climatic perturbations of the Phanerozoic Eon. Widespread deposition of organic-rich shales during OAE 2 has been attributed to a rapid rise in atmospheric CO2, global heating, and marine anoxia triggered by intense large igneous province (LIP) volcanism. Here, we present new Hg and Zn elemental and isotopic analyses from samples spanning OAE 2 in a hemipelagic section from Rehkogelgraben, Austria, which was part of the north-western Tethys. [...]".

 

Source: Science Direct 
Authors: Hanwei Yao et al.
DOI: https://doi.org/10.1016/j.gloplacha.2022.103881

Read the full article here.


Uranium isotope reconstruction of ocean deoxygenation during OAE 2 hampered by uncertainties in fractionation factors and local U-cycling

Abstract. 

"A δ238U record of changing ocean anoxia during OAE 2 is reconstructed using seawater derived U in pelagic marine sediments in the Portland #1 core in the south-central region of the Western Interior Seaway of North America. The peak negative excursion of 1.4‰ in authigenic sedimentary δ238U values is consistent with expansion of marine anoxia during the event, but the size of the shift is much larger than the negative excursions recorded in two other published records. [...]". 

 

Source: Science Direct 
Authors: Brayden S. McDonald et al.
DOI: https://doi.org/10.1016/j.gca.2022.05.010

Read the full article here.


Geochemical evidence from the Kioto Carbonate Platform (Tibet) reveals enhanced terrigenous input and deoxygenation during the early Toarcian

Abstract.

"The early Toarcian, as registered in a variety of sedimentary archives, was characterized by an abrupt negative carbon-isotope excursion (CIE) typically superimposed on a long-term positive trend, and was accompanied by significant climatic and environmental changes. However, the changes in continental weathering influx and oceanic deoxygenation in shallow waters and their possible role in causing carbonate-platform crises in low latitudes remains poorly constrained. [...]".

 

Source: Science Direct 
Authors: Zhong Han et al.
DOI: https://doi.org/10.1016/j.gloplacha.2022.103887

Read the full article here.


Quantifying the Contribution of Ocean Mesoscale Eddies to Low Oxygen Extreme Events

Abstract.

"Ocean mesoscale eddies have been identified as drivers of localized extremely low dissolved oxygen concentration ([O2]) conditions in the subsurface. We employ a global physical-biogeochemical ocean model at eddy-permitting resolution to conduct a census of open-ocean eddies near Eastern Boundary Upwelling Systems adjacent to tropical Oxygen Minimum Zones (OMZs). We track cyclonic and anticyclonic eddies with a surface signature over the period 1992–2018 and isolate their subsurface oxygen characteristics. We identify strongly deoxygenating eddies and quantify their contribution to low [O2] extreme events. [...]".

 

Source: Geophysical Research Letters
Authors: Jamie Atkins et al.
DOI: https://doi.org/10.1029/2022GL098672

Read the full article here.


Mercury stable isotopes suggest reduced foraging depth in oxygen minimum zones for blue sharks

Abstract. 

"Oxygen minimum zones (OMZs) are currently expanding across the global ocean due to climate change, leading to a compression of usable habitat for several marine species. Mercury stable isotope compositions provide a spatially and temporally integrated view of marine predator foraging habitat and its variability with environmental conditions. Here, we analyzed mercury isotopes in blue sharks Prionace glauca from normoxic waters in the northeastern Atlantic and from the world's largest and shallowest OMZ, located in the northeastern Pacific (NEP). [...]".

 

Source: Science Direct 
Authors: Gaël Le Croizier et al.
DOI: https://doi.org/10.1016/j.marpolbul.2022.113892

Read the full article here.


Decoupled oxygenation of the Ediacaran ocean and atmosphere during the rise of early animals

Abstract. 

"The Ediacaran Period (∼635 to 541 Ma) witnessed the early diversification and radiation of metazoans, in the form of the Ediacaran Biota. This biological revolution, beginning at ∼575 Ma, has been widely attributed to a temporally restricted episode of deeper ocean oxygenation, potentially caused by a contemporaneous rise in atmospheric oxygen levels. However, quantitative geochemical-record-driven estimates of Ediacaran atmospheric and oceanic redox evolution are lacking, and hence possible links between oceanic and atmospheric oxygenation remain speculative. [...]". 

 

Source: Science Direct 
Authors: Wei Shi et al.
DOI: https://doi.org/10.1016/j.epsl.2022.117619

Read the full article here.


EBUS Conference 2022 - Registration

Registration is now open 

EBUS Conference: September 19 - 23, 2022 in Lima, Peru

"The Open Science Conference on Eastern Boundary Upwelling Systems (EBUS): Past, Present and Future and the Second International Conference on the Humboldt Current System are planned for September 19 - 23 in Lima, Peru. Although the conference aims to be in-person, options for virtual participation will be provided.

The meeting will bring together PhD students, early career scientists and world experts to understand, review, and synthesize what is known about dynamics, sensitivity, vulnerability and resilience of Eastern Boundary Upwelling Systems and their living resources to climate variability, change and extreme events."

Registration ("early bird" deadline: August 30, 2022).

For further information please visit the event's homepage.


Oxygen minimum zone copepods in the Arabian Sea and the Bay of Bengal: Their adaptations and status

Abstract.

"The Arabian Sea and the Bay of Bengal are cul-de-sacs of the northern Indian Ocean, and they contain more than half of the world's Oxygen Minimum Zones (OMZs). The current study reviews the vast and advancing literature on the oceanographic settings that lead to distinct OMZs in the Arabian Sea and the Bay of Bengal and links them with the copepods thriving there, their status, and likely adaptations. The Arabian Sea has a thicker perennial subsurface OMZ (∼1000 m) than the Bay of Bengal (∼500 m), which is linked to high plankton production via upwelling and winter convection in the former and river influx and mesoscale eddies in the latter. [...]."

 

Source: Science Direct 
Authors: Vidhya Vijayasenan et al.
DOI: https://doi.org/10.1016/j.pocean.2022.102839

Read the full article here.


GO2NE Webinar on Ocean Deoxygenation

GO2NE Webinar on Ocean Deoxygenation. 

"Do you want to know more about deoxygenation in the ocean?
Join us for the upcoming webinar!

Tuesday, 23 August 2022, 23:00 h – 24:00 CEST

Registration link

Please join the Global Ocean Oxygen Network (IOC Expert Working Group GO2NE) for a new session of its webinar series on ocean deoxygenation. The 15th webinar will take place 23 August 2022, 23:00 h CEST. The webinar will feature presentations by a more senior and an early-career scientist, 20 minutes each followed by 10 minutes moderated discussion sessions. 

If you are interested to present at one of the upcoming webinars please submit a short abstract here.

Moderation
Jodie Rummer
James Cook University, Australia

Speakers:
Ariel Pezner
Scripps Institution of Oceanography, University of California San Diego, USA
"Coral reef hypoxia: Present-day exposure and projections under warming"

David Suggett
University of Technology Sydney, Australia
"Unlocking the vulnerability of reef-forming corals to deoxygenation"

If you want to receive further information about upcoming webinars please register here." 


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