News

Decadal variability of oxygen uptake, export, and storage in the Labrador Sea from observations and CMIP6 models

Abstract.

"The uptake of dissolved oxygen from the atmosphere via air-sea gas exchange and its physical transport away from the region of uptake are crucial for supplying oxygen to the deep ocean. This process takes place in a few key regions that feature intense oxygen uptake, deep water formation, and physical oxygen export. In this study we analyze one such region, the Labrador Sea, utilizing the World Ocean Database (WOD) to construct a 65–year oxygen content time series in the Labrador Sea Water (LSW) layer (0–2200 m). [...]".

 

Source: Frontiers in Marine Science 
Authors: Jannes Koelling et al.
DOI: https://doi.org/10.3389/fmars.2023.1202299

Read the full article here.


Ideas and perspectives: The fluctuating nature of oxygen shapes the ecology of aquatic habitats and their biogeochemical cycles – the aquatic oxyscape

Abstract.

"Oxygen availability is a pivotal factor for ecosystem functioning and the resistance of organisms to the effect of climate change in aquatic habitats. Although extensive work has been done to assess the effect of oxygen on marine and freshwater biota, many studies have not captured the ecological importance of oxygen variations. Overlooking the fluctuating nature of oxygen may cause potential biases in the design and implementation of management policies for aquatic habitats. Conceptual perspectives on the dynamic nature of oxygen fluctuations have been raised in the scientific community in order to enhance [...]".

 

Source: Biogeosciences
Authors: Marco Fusi et al.
DOI: https://doi.org/10.5194/bg-20-3509-2023

Read the full article here.


Intermediate water circulation drives distribution of Pliocene Oxygen Minimum Zones

Abstract. 

"Oxygen minimum zones (OMZs) play a critical role in global biogeochemical cycling and act as barriers to dispersal for marine organisms. OMZs are currently expanding and intensifying with climate change, however past distributions of OMZs are relatively unknown. Here we present evidence for widespread pelagic OMZs during the Pliocene (5.3-2.6 Ma), the most recent epoch with atmospheric CO2 analogous to modern (~400-450 ppm). The global distribution of OMZ-affiliated planktic foraminifer, Globorotaloides hexagonus, and Earth System and Species Distribution Models show [...]". 

 

Source: Nature
Authors: Catherine V. Davis et al.
DOI: https://doi.org/10.1038/s41467-022-35083-x

Read the full article here. 


Oceanic and atmospheric methane cycling in the cGENIE Earth system model

Abstract.

"The methane (CH4) cycle is a key component of the Earth system that links planetary climate, biological metabolism, and the global biogeochemical cycles of carbon, oxygen, sulfur, and hydrogen. However, currently lacking is a numerical model capable of simulating a diversity of environments in the ocean where CH4 can be produced and destroyed, and with the flexibility to be able to explore not only relatively recent perturbations to Earth’s CH4 cycle but also to probe CH4 cycling and associated climate impacts under the very low-O2 conditions characteristic of most of Earth history and likely widespread on other Earth-like planets. [...]"

Source: Geoscientific Model Development
Authors: Christopher T. Reinhard et al.
DOI: 10.5194/gmd-2020-32

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The control of hydrogen sulfide on benthic iron and cadmium fluxes in the oxygen minimum zone off Peru

Abstract.

"Sediments in oxygen-depleted marine environments can be an important sink or source of bio-essential trace metals in the ocean. However, the key mechanisms controlling the release from or burial of trace metals in sediments are not exactly understood. Here, we investigate the benthic biogeochemical cycling of Fe and Cd in the oxygen minimum zone off Peru. We combine bottom water profiles, pore water profiles, as well as benthic fluxes determined from pore water profiles and in-situ from benthic chamber incubations along a depth transect at 12° S. In agreement with previous studies, both concentration-depth profiles and in-situ benthic fluxes indicate a Fe release from sediments into bottom waters. [...]"

Source: Biogeosciences  (Preprint)
Authors: Anna Plass et al.
DOI: 10.5194/bg-2019-390

Read the full article here.


Atmosphere–ocean oxygen and productivity dynamics during early animal radiations

Abstract.

"The proliferation of large, motile animals 540 to 520 Ma has been linked to both rising and declining O2 levels on Earth. To explore this conundrum, we reconstruct the global extent of seafloor oxygenation at approximately submillion-year resolution based on uranium isotope compositions of 187 marine carbonates samples from China, Siberia, and Morocco, and simulate O2 levels in the atmosphere and surface oceans using a mass balance model constrained by carbon, sulfur, and strontium isotopes in the same sedimentary successions. [...]"

Source: PNAS
Authors: Tais W. Dahl et al.
DOI: 10.1073/pnas.1901178116

Read the full article here.


A New Characterization of the Upper Waters of the central Gulf of México based on Water Mass Hydrographic and Biogeochemical Characteristics

Abstract.

" In the Gulf of Mexico (GoM) at least three near-surface water masses are affected by mesoscale processes that modulate the biogeochemical cycles. Prior studies have presented different classifications of water masses where the greater emphasis was on deep waters and not on the surface waters (σθ < 26 kg m−3), as in this work. Here presents a new classification of water masses in the GoM, based on thermohaline properties and dissolved oxygen (DO) concentration using data from a total of five summer and winter cruises carried out primarily in the central GoM. [...]"

Source: Biogeosciences
Authors: Gabriela Yareli Cervantes-Diaz et al.
DOI: 10.5194/bg-2019-340

Read the full article here.


The effect of marine aggregate parameterisations on nutrients and oxygen minimum zones in a global biogeochemical model

Abstract.

"Particle aggregation determines the particle flux length scale and affects the marine oxygen concentration and thus the volume of oxygen minimum zones (OMZs) that are of special relevance for ocean nutrient cycles and marine ecosystems and that have been found to expand faster than can be explained by current state-of-the-art models. [...]"

Source: Biogeosciences
Author: Daniela Niemeyer et al.
DOI: 10.5194/bg-16-3095-2019

Read the full article here.


Oxygen minimum zone-type biogeochemical cycling in the Cenomanian-Turonian Proto-North Atlantic across Oceanic Anoxic Event 2

Abstract.

"Oceanic Anoxic Events (OAEs) in Earth's history are regarded as analogues for current and future ocean deoxygenation, potentially providing information on its pacing and internal dynamics. In order to predict the Earth system's response to changes in greenhouse gas concentrations and radiative forcing, a sound understanding of how biogeochemical cycling differs in modern and ancient marine environments is required. [...]"

Source: Earth and Planetary Science Letters
Authors: Florian Scholz et al.
DOI: 10.1016/j.epsl.2019.04.008

Read the full article here.


Isotopic evidence for complex biogeochemical cycling of Cd in the eastern tropical South Pacific

Abstract.

"Over the past decades, observations have confirmed decreasing oxygen levels and shoaling of oxygen minimum zones (OMZs) in the tropical oceans. Such changes impact the biogeochemical cycling of micronutrients such as Cd, but the potential consequences are only poorly constrained. Here, we present seawater Cd concentrations and isotope compositions for 12 depth profiles at coastal, nearshore and offshore stations from 4°S to 14°S in the eastern tropical South Pacific, where one of the world's strongest OMZs prevails. [...]"

Source: Earth and PLanetary Science Letters
Authors: Ruifang C. Xie et al.
DOI: 10.1016/j.epsl.2019.02.001

Read the full article here.


The emergence of a globally productive biosphere

Abstract.

"A productive biosphere and oxygenated atmosphere are defining features of Earth and are fundamentally linked. Here I argue that cellular metabolism imposes central constraints on the historical trajectories of biopsheric productivity and atmospheric oxygenation. Photosynthesis depends on iron, but iron is highly insoluble under the aerobic conditions produced by oxygenic photosynthesis. [...]"

Source: PeerJ Preprints
Author: Rogier Braakman
DOI: 10.7287/peerj.preprints.27269v1

Read the full article here.


Ecology and evolution of seafloor and subseafloor microbial communities

Abstract.

"Vast regions of the dark ocean have ultra-slow rates of organic matter sedimentation, and their sediments are oxygenated to great depths yet have low levels of organic matter and cells. Primary production in the oxic seabed is supported by ammonia-oxidizing archaea, whereas in anoxic sediments, novel, uncultivated groups have the potential to produce H2 and CH4, which fuel anaerobic carbon fixation. [...]"

Source: Nature Reviews Microbiology
Authors: William D. Orsi
DOI: 10.1038/s41579-018-0046-8

Read the full article here.


Early Palaeozoic ocean anoxia and global warming driven by the evolution of shallow burrowing

Abstract.

"The evolution of burrowing animals forms a defining event in the history of the Earth. It has been hypothesised that the expansion of seafloor burrowing during the Palaeozoic altered the biogeochemistry of the oceans and atmosphere. However, whilst potential impacts of bioturbation on the individual phosphorus, oxygen and sulphur cycles have been considered, combined effects have not been investigated, leading to major uncertainty over the timing and magnitude of the Earth system response to the evolution of bioturbation. [...]"

Source: Nature Communications
Authors: Sebastiaan van de Velde et al.
DOI: 10.1038/s41467-018-04973-4

Read the full article here.


Enhanced carbon-sulfur cycling in the sediments of Arabian Sea oxygen minimum zone center

Abstract.

"Biogeochemistry of oxygen minimum zone (OMZ) sediments, which are characterized by high input of labile organic matter, have crucial bearings on the benthic biota, gas and metal fluxes across the sediment-water interface, and carbon-sulfur cycling. Here we couple pore-fluid chemistry and comprehensive microbial diversity data to reveal the sedimentary carbon-sulfur cycle across a water-depth transect covering the entire thickness of eastern Arabian Sea OMZ, off the west coast of India. [...]"

Source: Scientific Reports
Authors: Svetlana Fernandes et al.
DOI: 10.1038/s41598-018-27002-2

Read the full article here.


Biogeochemical role of subsurface coherent eddies in the ocean: Tracer cannonballs, hypoxic storms, and microbial stewpots?

Abstract.

"Subsurface coherent eddies are well-known features of ocean circulation, but the sparsity of observations prevents an assessment of their importance for biogeochemistry. Here, we use a global eddying (0.1° ) ocean-biogeochemical model to carry out a census of subsurface coherent eddies originating from eastern boundary upwelling systems (EBUS), and quantify their biogeochemical effects as they propagate westward into the subtropical gyres.  [...]"

Source: Global Biogeochemical Cycles
Authors: Ivy Frenge et al.
DOI: 10.1002/2017GB005743


Marine N2O emissions from nitrification [...] constrained by modern observations and projected in multi-millennial global warming simula

Abstract.

"Nitrous oxide (N2O) is a potent greenhouse gas (GHG) and ozone destructing agent, yet, global estimates of N2O emissions are uncertain. Marine N2O stems from nitrification and denitrification processes which depend on organic matter cycling and dissolved oxygen (O2). We introduce N2O as an obligate intermediate product of denitrification and as an O2-dependent byproduct from nitrification in the Bern3D ocean model. [...]"

Source: Global Biogeochemical Cycles
Authors: G. Battaglia, F. Joos
DOI: 10.1002/2017GB005671

Read the full article here.


Diverse Marinimicrobia bacteria may mediate coupled biogeochemical cycles along eco-thermodynamic gradients

Abstract.

"Microbial communities drive biogeochemical cycles through networks of metabolite exchange that are structured along energetic gradients. As energy yields become limiting, these networks favor co-metabolic interactions to maximize energy disequilibria. Here we apply single-cell genomics, metagenomics, and metatranscriptomics to study bacterial populations of the abundant “microbial dark matter” phylum Marinimicrobia along defined energy gradients. [...]"

Source: Nature Communications
Authors: Alyse K. Hawley et al.
DOI: 10.1038/s41467-017-01376-9

Read the full article here.


A dynamic microbial community with high functional redundancy inhabits the cold, oxic subseafloor aquifer

Abstract.

"The rock-hosted subseafloor crustal aquifer harbors a reservoir of microbial life that may influence global marine biogeochemical cycles. Here we utilized metagenomic libraries of crustal fluid samples from North Pond, located on the flanks of the Mid-Atlantic Ridge, a site with cold, oxic subseafloor fluid circulation within the upper basement to query microbial diversity. [...]"

Source: The ISME Journal
Authors: Benjamin J. Tully et al.
DOI: 10.1038/ismej.2017.187

Read the full article here.


Impacts of El Niño events on the Peruvian upwelling system productivity

Abstract.

"Every 2–7 years, El Niño events trigger a strong decrease in phytoplankton productivity off Peru, which profoundly alters the environmental landscape and trophic chain of the marine ecosystem. Here we use a regional coupled physical-biogeochemical model to study the dynamical processes involved in the productivity changes during El Nino, with a focus on the strongest events of the 1958–2008 period. Model evaluation using satellite and in situ observations shows that the model reproduces the surface and subsurface interannual physical and biogeochemical variability. [...]"

Source: Journal of Geophysical Research: Oceans
Authors: D. Espinoza-Morriberón
DOI: 10.1002/2016JC012439

Read the full article here.


Spatial Patterns of Groundwater Biogeochemical Reactivity in an Intertidal Beach Aquifer

Abstract.

"Beach aquifers host a dynamic and reactive mixing zone between fresh and saline groundwater of contrasting origin and composition. Seawater, driven up the beachface by waves and tides, infiltrates into the aquifer and meets the seaward-discharging fresh groundwater, creating and maintaining a reactive intertidal circulation cell. Within the cell, land-derived nutrients delivered by fresh groundwater are transformed or attenuated. We investigated this process by collecting porewater samples from multi-level wells along a shore-perpendicular transect on a beach near Cape Henlopen, Delaware and analyzing solute and particulate concentrations. [...]"

Source: Biogeosciences
Authors: Kyra H. Kim
DOI: 10.1002/2017JG003943

Read the full article here.


Widespread seawater circulation in 18–22 Ma oceanic crust: Impact on heat flow and sediment geochemistry

Abstract.

"On the basis of heat-flow measurements, seismic mapping, and sediment pore-water analysis, we demonstrate widespread and efficient ventilation of the 18–22 Ma oceanic crust of the northeast equatorial Pacific Ocean. Recharge and discharge appear to be associated with basement outcrops, including seamounts and north-south–trending faults, along which sediment cover thins out and volcanic rocks are exposed. Low-temperature hydrothermal circulation through the volcanic crust leads to the reduction of heat flow through overlying sediments, with measured heat-flow values that are well below those expected from conductive cooling curves for lithosphere of this age. [...]"

Source: Geology
Authors: Thomas Kuhn et al.
DOI: 10.1130/G39091.1

Read the full article here.


The onset of widespread marine red beds and the evolution of ferruginous oceans

Abstract.

"Banded iron formations were a prevalent feature of marine sedimentation ~3.8–1.8 billion years ago and they provide key evidence for ferruginous oceans. The disappearance of banded iron formations at ~1.8 billion years ago was traditionally taken as evidence for the demise of ferruginous oceans, but recent geochemical studies show that ferruginous conditions persisted throughout the later Precambrian, and were even a feature of Phanerozoic ocean anoxic events. [...]"

Source: Nature Communications
Authors: Haijun Song et al.
DOI: 10.1038/s41467-017-00502-x

Read the full article here.


Ecological Energetic Perspectives on Responses of Nitrogen-Transforming Chemolithoautotrophic Microbiota to Changes in the Marine Environment

"Transformation and mobilization of bioessential elements in the biosphere, lithosphere, atmosphere and hydrosphere constitute the Earth's biogeochemical cycles, which are driven mainly by microorganisms through their energy and material metabolic processes. Without microbial energy harvesting from sources of light and inorganic chemical bonds for autotrophic fixation of inorganic carbon, there would not be sustainable ecosystems in the vast ocean. Although ecological energetics (eco-energetics) has been emphasized as a core aspect of ecosystem analyses and microorganisms largely control the flow of matter and energy in marine ecosystems, marine microbial communities are rarely studied from the eco-energetic perspective. [...]"

Source: Frontiers in Microbiology
Authors: Hongyue Dang and Chen-Tung A. Chen
DOI: 10.3389/fmicb.2017.01246

Full article


Eutrophication-Driven Deoxygenation in the Coastal Ocean

Abstract.

"Human activities, especially increased nutrient loads that set in motion a cascading chain of events related to eutrophication, accelerate development of hypoxia (lower oxygen concentration) in many areas of the world’s coastal ocean. Climate changes and extreme weather events may modify hypoxia. Organismal and fisheries effects are at the heart of the coastal hypoxia issue, but more subtle regime shifts and trophic interactions are also cause for concern. The chemical milieu associated with declining dissolved oxygen concentrations affects the biogeochemical cycling of oxygen, carbon, nitrogen, phosphorus, silica, trace metals, and sulfide as observed in water column processes, shifts in sediment biogeochemistry, and increases in carbon, nitrogen, and sulfur, as well as shifts in their stable isotopes, in recently accumulated sediments."

Source: Oceanography Volume 27 (2014)
Authors: Nancy N. Rabalais et al.
DOI: 10.5670/oceanog.2014.21

Full article


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