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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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Coastal eutrophication drives acidification, oxygen loss, and ecosystem change in a major oceanic upwelling system

Abstract.

"Global change is leading to warming, acidification, and oxygen loss in the ocean. In the Southern California Bight, an eastern boundary upwelling system, these stressors are exacerbated by the localized discharge of anthropogenically enhanced nutrients from a coastal population of 23 million people. Here, we use simulations with a high-resolution, physical–biogeochemical model to quantify the link between terrestrial [...]"

 

Source: PNAS- Proceedings of the National Academy of Sciences of the United States of America
Authors: Faycal Kessouri et al.
DOI: https://doi.org/10.1073/pnas.2018856118

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The effects of historical ozone changes on Southern Ocean heat uptake and storage

Abstract.

"Atmospheric ozone concentrations have dramatically changed in the last five decades of past century. Herein we explore the effects of historical ozone changes that include stratospheric ozone depletion on Southern Ocean heat uptake and storage, by comparing CESM1 large ensemble simulations with fixed-ozone experiment. During 1958–2005, the ozone changes contribute to about 50% of poleward intensification of the Southern Hemisphere westerly winds in historical simulations, which intensifies the Deacon Cell and residual meridional overturning circulation, thus contributing to heat redistribution[...]"

 

Source: Climate Dynamics
Authors: Shouwei Li et al.
DOI: https://doi.org/10.1007/s00382-021-05803-y

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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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The poleward enhanced Arctic Ocean cooling machine in a warming climate

Abstract.

"As a cooling machine of the Arctic Ocean, the Barents Sea releases most of the incoming ocean heat originating from the North Atlantic. The related air-sea heat exchange plays a crucial role in both regulating the climate and determining the deep circulation in the Arctic Ocean and beyond. It was reported that the cooling efficiency of this cooling machine has decreased significantly. In this study, we find that the overall cooling efficiency did not really drop: When the cooling efficiency decreased in the southern Barents Sea[...]"

 

Source: Nature Communications
Authors: Qi Shu et al.
DOI: https://doi.org/10.1038/s41467-021-23321-7

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Rain-fed streams dilute inorganic nutrients but subsidise organic-matter-associated nutrients in coastal waters of the northeast Pacific Ocean

Abstract.

"In coastal regions, rivers and streams may be important sources of nutrients limiting to primary production in marine waters; however, sampling is still rarely conducted across the land-to-ocean aquatic continuum, precluding conclusions from being drawn about connectivity between freshwater and marine systems. Here we use a more-than-4-year dataset (2014–2018) of nutrients (nitrogen, phosphorus, silica, iron) and dissolved organic carbon spanning streams draining coastal watersheds and nearshore marine surface waters along the Central Coast of British Columbia, Canada, at the heart of the North Pacific coastal temperate[...]"

 

Source: Biogeosciences
Authors: Kyra A. St. Pierre et al.
DOI: https://doi.org/10.5194/bg-18-3029-2021

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