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Effect of dissolved oxygen and hydrogen on the stress corrosion cracking behavior of alloy 600 in high temperature water

Abstract.

"The stress corrosion cracking behavior of alloy 600 was studied in high temperature water at 288°C to 360°C. The effects of dissolved oxygen (DO) and dissolved hydrogen (DH) on crack growth rate (CGR) are discussed. Results show that the CGR of alloy 600 in hydrogenated water (at the Ni/NiO phase boundary) is about 2-200 times higher than in 2 ppm O2 oxygenated water at 325°C and 360°C, while the opposite behavior was observed at 288°C. Much more severe intergranular oxidation was observed[...]"

 

Source: Science Direct
Authors: Jiamei Wang et al.
DOI: https://doi.org/10.1016/j.jnucmat.2020.152603

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Variable coastal hypoxia exposure and drivers across the southern California Current

Abstract.

"Declining oxygen is one of the most drastic changes in the ocean, and this trend is expected to worsen under future climate change scenarios. Spatial variability in dissolved oxygen dynamics and hypoxia exposures can drive differences in vulnerabilities of coastal ecosystems and resources, but documentation of variability at regional scales is rare in open-coast systems. Using a regional collaborative network of dissolved oxygen and temperature sensors maintained by scientists and fishing cooperatives from California, USA, and Baja California, Mexico, we characterize spatial and temporal variability in dissolved oxygen[...]"

 

Source: Nature Scientific Reports
Authors: Natalie H. N. Low et al.
DOI: https://doi.org/10.1038/s41598-021-89928-4

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Increase of a hypoxia-tolerant fish, Harpadon nehereus (Synodontidae), as a result of ocean deoxygenation off southwestern China

Abstract.

"We report a sudden explosive rise in abundance off southeastern China of a fish species that is hypoxia-tolerant, Bombay duck (Harpadon nehereus, Family Synodontidae), belonging to an Order (the Aulopiformes) encompassing overwhelmingly deep-sea fishes, but which predominantly occurs in coastal water. We suggest that this is made possible by the very high water content of its muscle and other tissues (about 90%, vs 75–80% for other coastal fish), which reduces its oxygen requirements and allows it to outcompete other fish in low-oxygen[...]"

 

Source: Environmental Biology of Fishes
Authors: Bin Kang et al.
DOI: https://doi.org/10.1007/s10641-021-01130-7

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Temperature and dissolved oxygen concentration in the Pacific Ocean at the northern region of the oxygen minimum zone off Mexico between the last two

Abstract.

"The changes in temperature and dissolved oxygen concentration in the Pacific Ocean in the northern region of the shallow oxygen minimum zone (OMZ) off Mexico were analyzed on the basis of the Word Ocean Database and a series of oceanographic cruises (LEGOZ-Mex). In order to test the changes in both parameters between two similar oceanographic scenarios according to the Pacific Decadal Oscillation (PDO), a comparison was made between the last two cool PDO phases of 1962–1974 and 2002–2012 when conditions[...]"

 

Source: Science Direct
Authors: E.D.Sánchez-Pérez et al.
DOI: https://doi.org/10.1016/j.jmarsys.2021.103607

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Zooplankton grazing of microplastic can accelerate global loss of ocean oxygen

Abstract.

"Global warming has driven a loss of dissolved oxygen in the ocean in recent decades. We demonstrate the potential for an additional anthropogenic driver of deoxygenation, in which zooplankton consumption of microplastic reduces the grazing on primary producers. In regions where primary production is not limited by macronutrient availability, the reduction of grazing pressure on primary producers causes export production to increase. Consequently, organic particle remineralisation in these regions[...]"

 

Source: Nature Communications
Authors: K. Kvale et al.
DOI: https://doi.org/10.1038/s41467-021-22554-w

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Antioxidant responses of the mussel Mytilus coruscus co-exposed to ocean acidification, hypoxia and warming

Abstract.

"In the present study, the combined effects of pH, dissolved oxygen (DO) and temperature levels on the antioxidant responses of the mussel Mytilus coruscus were evaluated. Mussels were exposed to two pH (8.1, 7.7-acidification), two DO (6 mg L−1, 2 mg L−1-hypoxia) and two temperature levels[...]"

 

Source: Science Direct
Authors: Fahim Ullah Khan et al
DOI: https://doi.org/10.1016/j.marpolbul.2020.111869

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Redox control on the tungsten isotope composition of seawater

Abstract.

"Free oxygen represents an essential basis for the evolution of complex life forms on a habitable Earth. The isotope composition of redox-sensitive trace elements such as tungsten (W) can possibly trace the earliest rise of oceanic oxygen in Earth’s history. However, the impact of redox changes on the W isotope composition of seawater is still unknown. Here, we report highly variable W isotope compositions in the water column of a redox-stratified basin (δ186/184W between +0.347 and +0.810 ‰) that contrast with the homogenous W isotope composition of the open ocean[...]"

 

Source: PNAS- Proceedings of the National Academy of Sciences of the United States of America
Authors: Florian Kurzweil et al.
DOI: https://doi.org/10.1073/pnas.2023544118

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Seaweed farms provide refugia from ocean acidification

Abstract.

"Seaweed farming has been proposed as a strategy for adaptation to ocean acidification, but evidence is largely lacking. Changes of pH and carbon system parameters in surface waters of three seaweed farms along a latitudinal range in China were compared, on the weeks preceding harvesting, with those of the surrounding seawaters. Results confirmed that seaweed farming is efficient in buffering acidification, with Saccharina japonica showing the highest capacity of 0.10 pH increase within the aquaculture area[...]"

 

Source: Science Direct
Authors: Xi Xiao et al
DOI: https://doi.org/10.1016/j.scitotenv.2021.145192

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Dissolved Organic Matter in the Upwelling System off Peru: Imprints of Bacterial Activity and Water Mass Characteristics

Abstract.

"Microbial degradation of dissolved organic matter (DOM) contributes to the formation and preservation of oxygen minimum zones (OMZs) in the ocean, but information on the spatial distribution and molecular composition of DOM in OMZ regions is scarce. We quantified molecular components of DOM that is, dissolved amino acids (DAA) and dissolved combined carbohydrates (DCCHO), in the upwelling region off Peru. We found the highest concentrations of DCCHO in fully oxygenated[...]"

 

Source: Advancing Earth and Space Science
Authors: Anja Engel et al.
DOI: https://doi.org/10.1029/2020JG006048

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Photosensitized formation of sulfate and volatile sulfur gases from dissolved organic sulfur: Roles of pH, dissolved oxygen, and salinity

Abstract.

"The photodegradation of dissolved organic sulfur (DOS) is a potential source of aqueous sulfate and its chemical precursors in surface water. However, the photochemical fate of DOS and factors that control its fate still remain unclear. Herein, we employed a DOS model featuring a photosensitizer (humic acids, HA) to investigate the photochemical degradation pathways of DOS in various natural water sources, from which we observed the substantial photosensitized formation of sulfate, methanesulfonic acid (MSA), carbonyl [...]"

 

Source: Science Direct
Authors: Jian-Long Li et al.
DOI: https://doi.org/10.1016/j.scitotenv.2021.147449

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