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Geochemical and paleontological evidence of early Cambrian dynamic ocean oxygenation and its implications for organic matter accumulation in mudrocks

Abstract. 

"The evolution of global ocean oxygenation during the early Cambrian remains highly controversial, making it difficult to evaluate how environmental triggers play a role in controlling the organic matter (OM) accumulation in black shales. In this study, an integrated approach, including total organic carbon (TOC) content, major and trace element geochemistry, and microscope images, was systematically conducted in a continuous core well that penetrated through the Lower Cambrian Yanjiahe (YJH)–Shuijingtuo (SJT, subdivided into SM Ⅰ, SM Ⅱ, SM Ⅲ, and SM Ⅳ members) successions (∼541-514Ma) at the Three Gorges area [...]".

 

Source: Science Direct 
Authors: Yu Zhang et al.
DOI: https://doi.org/10.1016/j.marpetgeo.2022.105958

Read the full article here.


Volcanic trigger of ocean deoxygenation during Cordilleran ice sheet retreat

Abstract. 

"North Pacific deoxygenation events during the last deglaciation were sustained over millennia by high export productivity, but the triggering mechanisms and their links to deglacial warming remain uncertain. Here we find that initial deoxygenation in the North Pacific immediately after the Cordilleran ice sheet (CIS) retreat was associated with increased volcanic ash in seafloor sediments. Timing of volcanic inputs relative to CIS retreat suggests that regional explosive volcanism was initiated by ice unloading. […]".

 

Source: Nature
Authors: Jianghui Du et al.
DOI: https://doi.org/10.1038/s41586-022-05267-y

Read the full article here.


Progressive expansion of seafloor anoxia in the Middle to Late Ordovician Yangtze Sea: Implications for concurrent decline of invertebrate diversity

Abstract. 

"The Great Ordovician Biodiversification Event (GOBE) achieved its peak during the Middle Ordovician, likely in association with climatic cooling and a rise of atmospheric O2. However, unstable redox states developed widely in contemporaneous epeiric seas, challenging previous assumptions about sustained oceanic oxygenation driven by deep-ocean ventilation in the aftermath of Ordovician cooling. Here, we investigate two Middle-Upper Ordovician shale-dominated successions from intra-shelf basin and slope settings of the Yangtze Sea, South China. […]".

 

Source: Science Direct 
Authors: Junpeng Zhang et al.
DOI: https://doi.org/10.1016/j.epsl.2022.117858

Read the full article here.


Two deep marine oxygenation events during the Permian-Triassic boundary interval in South China

Abstract. 

"Marine redox conditions through the Permian-Triassic (P-T) boundary interval have been intensively studied in South China with different redox proxies and from different sections. However, the resultant interpretations are inconsistent and sometimes even controversial, thereby impeding an overall understanding of global environmental changes and of causes for the P-T mass extinction events. This study summarizes and reevaluates these previous studies. [...]".

 

Source: Science Direct
Authors: Yuzhu Ge & David P.G. Bond
DOI: https://doi.org/10.1016/j.earscirev.2022.104220

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!

Thursday, 8th December 2022, 14:00 h – 15:00 CET

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 17th webinar will take place 8  December 2022, 14:00 h CET. 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
Gil Jacinto
Marine Science Institute, University of the Philippines Diliman, Philippines
(retired)

Speakers:
Lara Sotto
Marine Science Institute, University of the Philippines Diliman, Philippines
"Hypoxia in Manila Bay: Insights from Fieldwork, Nutrient Load and Hydrodynamic Modeling"

Aileen Tan Shau Hwai
Centre For Marine & Coastal Studies, Universiti Sains Malaysia, Malaysia
"Fish Kills in Malaysia" 

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


../common/calendar Start Date: 12/8/22

Investigating ocean deoxygenation and the oxygen minimum zone in the Central Indo Pacific region based on the hindcast datasets

Abstract. 

"Deoxygenation is increasingly recognized as a significant environmental threat to the ocean following sea temperature rises due to global warming and climate change. Considering the cruciality of the deoxygenation impacts, it is important to assess the current status and predict the future possibility of ocean deoxygenation, for instance, within the Central Indo Pacific (CIP) regions represent climate-regulated marine areas. This study divided CIP into five regions then investigated the deoxygenation parameters (dissolved oxygen, temperature, salinity, and pH) collected from 1993 to 2021 sourced from in situ measurement and long-term hindcast data. [...]".

 

Source: Environmental Monitoring and Assessment
Authors: Karlina Triana et al.
DOI: https://doi.org/10.1007/s10661-022-10615-6

Read the full article here.


Seasonal nearshore ocean acidification and deoxygenation in the Southern California Bight

Abstract. 

"The California Current System experiences seasonal ocean acidification and hypoxia (OAH) owing to wind-driven upwelling, but little is known about the intensity, frequency, and depth distribution of OAH in the shallow nearshore environment. Here we present observations of OAH and dissolved inorganic carbon and nutrient parameters based on monthly transects from March 2017 to September 2018 extending from the surf zone to the ~ 40 m depth contour in La Jolla, California. Biologically concerning OAH conditions were observed at depths as shallow as 10 m and as close as 700 m to the shoreline. [...]".

 

Source: Scientific Reports
Authors: Samuel A. H. Kekuewa et al. 
DOI: https://doi.org/10.1038/s41598-022-21831-y

Read the full article here.


The Ocean's Biological Pump: In Situ Oxygen Measurements in the Subtropical Oceans

Abstract. 

"The magnitude and distribution of the ocean's biological pump (the downward flux of organic carbon (OC) from the ocean surface) influences the pCO2 of the atmosphere and the O2 content of the deep sea, but has not been well quantified. We determine this flux in the ocean's five subtropical gyres using upper-ocean oxygen mass balance and measurements of T, S, and pO2 by autonomous profiling floats. Our results suggest that the biological OC pump is not globally uniform among the subtropical gyres: values in the North Pacific and Atlantic indicate distinct autotrophy (1–2 mol C m−2 yr−1) while near zero values in the S. [...]".

 

Source: Geophysical Research Letters
Authors: Steven Emerson & Bo Yang
DOI: https://doi.org/10.1029/2022GL099834

Read the full article here.


Intensive ocean anoxia and large δ13Ccarb perturbations during the Carnian Humid Episode (Late Triassic) in Southwest China

Abstract. 

"The Carnian Humid Episode (CHE) represents a dramatic dry to wet climate transition in the Late Triassic. Manifestations of this climate shift and its associated biological and environmental responses are not fully understood. Here, we carried out carbonate carbon isotope, trace metal, and pyrite framboid analyses at Wolonggang in southwest China to trace palaeoenvironmental changes during this critical interval. The CHE at Wolonggang is marked by the development of fine laminated carbonaceous siltstones and black shales overlying the intensely bioturbated Zhuganpo limestone deposited in the latest Julian 1. [...]". 

 

Source: Science Direct 
Authors: Zaitian Zhang et al.
DOI: https://doi.org/10.1016/j.gloplacha.2022.103942

Read the full article here.


Physical-chemical factors influencing the vertical distribution of phototrophic pico-nanoplankton in the Oxygen Minimum Zone (OMZ) off Northern Chile

Abstract. 

"The vertical distribution of phytoplankton is of fundamental importance in the structure, dynamic, and biogeochemical pathways in marine ecosystems. Nevertheless, what are the main factors determining this distribution remains as an open question. Here, we evaluated the relative influence of environmental factors that might control the coexistence and vertical distribution of pico-nanoplankton associated with the OMZ off northern Chile. Our results showed that in the upper layer Synechococcus-like cells were numerically important at all sampling stations. [...]". 

 

Source: Science Direct 
Authors: Edson Piscoya et al.
DOI: https://doi.org/10.1016/j.marenvres.2022.105710

Read the full article here.


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