News

Can microplastics pose a threat to ocean carbon sequestration?

Abstract.

"Global climate change has attracted worldwide attention. The ocean is the largest active carbon pool on the planet and plays an important role in global climate change. However, marine plastic pollution is getting increasingly serious due to the large consumption and mismanagement of global plastics. The impact of marine plastics on ecosystem responsible for the gas exchange and circulation of marine CO2 may cause more greenhouse gas emissions. Consequently, in this paper, threats of marine microplastics to ocean carbon sequestration are discussed. Marine microplastics[...]"

 

Source: Science Direct
Authors: Maocai Shen et al.
DOI: https://doi.org/10.1016/j.marpolbul.2019.110712

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Observing the Global Ocean with Biogeochemical-Argo

Abstract.

"Biogeochemical-Argo (BGC-Argo) is a network of profiling floats carrying sensors that enable observation of as many as six essential biogeochemical and bio-optical variables: oxygen, nitrate, pH, chlorophyll a, suspended particles, and downwelling irradiance. This sensor network represents today's most promising strategy for collecting temporally and vertically resolved observations of biogeochemical properties throughout the ocean. All data are freely available within 24 hours of transmission. These data fill large gaps in ocean-observing systems and support three ambitions: gaining a better understanding of biogeochemical processes (e.g., the biological[...]"

 

Source: Annual Review of Marine Science
Authors: Hervé Claustre et al.
DOI: https://doi.org/10.1146/annurev-marine-010419-010956

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The regulation of oxygen to low concentrations in marineoxygen-minimum zones

Abstract.

"The Bay of Bengal hosts persistent, measurable, but sub-micromolar, concentrations of oxygenin its oxygen-minimum zone (OMZ). Such low-oxygen conditions are not necessarily rare in theglobal ocean and seem also to characterize the OMZ of the Pescadero Basin in the Gulf of California,as well as the outer edges of otherwise anoxic OMZs, such as can be found, for example, in theEastern Tropical North Pacific. We show here that biological controls on oxygen consumption arerequired to allow the semistable persistence of low-oxygen conditions in OMZ settings; otherwise,only small changes in physical mixing or rates of primary production would drive the OMZ betweenanoxic and oxic states with potentially large swings in oxygen concentration. [...]"

Source: Journal of Marine Research
Authors: Donald E. Canfield et al.
 

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Variability of dissolved oxygen in the Arabian Sea Oxygen Minimum Zone and its driving mechanisms

Abstract.

"The Arabian Sea hosts one of the most intense, perennial Oxygen Minimum Zones (OMZ) in the world ocean. Observations along a meridional transect at 68°E extending from 8 to 21°N showed large seasonal as well as interannual changes in the dissolved oxygen and nitrite concentrations. Unlike previous studies that used observations from the periphery of the OMZ, our observations are from its core and also allow us demarcating the southern extent of the OMZ. [...]"

Source: Journal of Marine Systems
Authors: Damodar M.Shenoy et al.
DOI: 10.1016/j.jmarsys.2020.103310 

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When microbiologists plunge into the ocean

Microbiologists stake their claim: assessing climate change involves new ways of studying the ocean’s microbes.

"Microbiology wants in. No longer should microbes and microbial processes be left out of climate change assessments, state 33 researchers from nine countries in their consensus statement1, “Scientists’ warning to humanity: microorganisms and climate change.” There’s a “need to act,” the authors write. By underappreciating the importance of microbial processes both on land and in the oceans, “we fundamentally limit our understanding of Earth’s biosphere and response to climate change and thus jeopardize efforts to create an environmentally sustainable future.” [...]"

Source: Nature Methods 
Authors: Vivien Marx
DOI: 10.1038/s41592-020-0736-9

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The regulation of oxygen to low concentrations in marine oxygen-minimum zones

Abstract.

"The Bay of Bengal hosts persistent, measurable, but sub-micromolar, concentrations of oxygen in its oxygen-minimum zone (OMZ). Such low-oxygen conditions are not necessarily rare in the global ocean and seem also to characterize the OMZ of the Pescadero Basin in the Gulf of California, as well as the outer edges of otherwise anoxic OMZs, such as can be found, for example, in the Eastern Tropical North Pacific. We show here that biological controls on oxygen consumption are required to allow the semistable persistence of low-oxygen conditions in OMZ settings; otherwise, only small changes in physical mixing or rates of primary production would drive the OMZ between anoxic and oxic states with potentially large swings in oxygen concentration. [...]"

Source: Journal of Marine Research 
Authors: Don E. Canfield et al.

Read the full article here.


No detectable Weddell Sea Antarctic Bottom Water export during the Last and Penultimate Glacial Maximum

Abstract.

"Weddell Sea-derived Antarctic Bottom Water (AABW) is one of the most important deep water masses in the Southern Hemisphere occupying large portions of the deep Southern Ocean (SO) today. While substantial changes in SO-overturning circulation were previously suggested, the state of Weddell Sea AABW export during glacial climates remains poorly understood. [...]"

Source: Nature Communications
Authors: Huang Huang et al.
DOI: 10.1038/s41467-020-14302-3

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Physical and biogeochemical impacts of RCP8.5 scenario in the Peru upwelling system

Abstract.

"The northern Humboldt current system (NHCS or Peru upwelling system) sustains the world's largest small pelagic fishery. While a nearshore surface cooling has been observed off southern Peru in recent decades, there is still considerable debate on the impact of climate change on the regional ecosystem. This calls for more accurate regional climate projections of the 21st century, using adapted tools such as regional eddy-resolving coupled biophysical models. [...]"

Source: Biogeosciences (preprint)
Authors: Vincent Echevin et al.
DOI: 10.5194/bg-2020-4

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Anaerobic Activity Is a Big Contributor in Marine “Dead Zones”

Climate models that do not account for anaerobic microbial activity may underestimate future expansion of oxygen-depleted waters.

"Certain parts of Earth’s oceans are so oxygen depleted that they can hardly sustain life. Climate models predict that these “dead zones” will expand as global warming progresses, affecting ecosystems, fisheries, and the climate itself. Now Lengger et al. provide new evidence that such predictions do not adequately account for the activity of anaerobic microbes that consume inorganic carbon within dead zones. [...]"

Source: EOS.org

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Modulation of the North Atlantic deoxygenation by the slowdown of the nutrient stream

Abstract.

"Western boundary currents act as transport pathways for nutrient-rich waters from low to high latitudes (nutrient streams) and are responsible for maintaining midlatitude and high-latitude productivity in the North Atlantic and North Pacific. This study investigates the centennial oxygen (O2) and nutrient changes over the Northern Hemisphere in the context of the projected warming and general weakening of the Atlantic Meridional Overturning Circulation (AMOC) in a subset of Earth system models included in the CMIP5 catalogue. In all models examined, the Atlantic warms faster than the Pacific Ocean, resulting in a greater basin-scale solubility decrease. [...]"

Source: Biogeosciences
Authors: Filippos Tagklis et al.
DOI: 10.5194/bg-17-231-2020

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