The Biogeochemical Sulfur Cycle of Marine Sediments

Frontiers in Microbiology, Journal Year: 2019, Volume and Issue: 10

Published: April 24, 2019

Microbial dissimilatory sulfate reduction to sulfide is a predominant terminal pathway of organic matter mineralization in the anoxic seabed. Chemical or microbial oxidation produced establishes complex network pathways sulfur cycle, leading intermediate species and partly back sulfate. The intermediates include elemental sulfur, polysulfides, thiosulfate, sulfite, which are all substrates for further oxidation, disproportionation. New microbiological discoveries, such as long-distance electron transfer through oxidizing cable bacteria, add complexity. Isotope exchange reactions play an important role stable isotope geochemistry experimental study transformations using radiotracers. Microbially catalyzed processes reversible whereby back-reaction affects our interpretation radiotracer experiments provides mechanism fractionation. We here review progress current status understanding cycle seabed with respect its ecology, biogeochemistry, geochemistry.

Language: Английский

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Ocean Alkalinity, Buffering and Biogeochemical Processes

Reviews of Geophysics, Journal Year: 2020, Volume and Issue: 58(3)

Published: June 9, 2020

Alkalinity, the excess of proton acceptors over donors, plays a major role in ocean chemistry, buffering and calcium carbonate precipitation dissolution. Understanding alkalinity dynamics is pivotal to quantify carbon dioxide uptake during times global change. Here we review its as well biogeochemical processes governing pH ocean. We show that it important distinguish between measurable titration charge balance used calcification dissolution needed understand impact on components system. A general treatment quantification via sensitivity factors presented link existing buffer factors. The individual discussed quantified using these Processes longer time scales such compensation, (reversed) silicate weathering, anaerobic mineralization are derive close-to-balance budget for modern

Language: Английский

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The fate of organic carbon in marine sediments - New insights from recent data and analysis

Earth-Science Reviews, Journal Year: 2020, Volume and Issue: 204, P. 103146 - 103146

Published: Feb. 29, 2020

Language: Английский

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Sediment oxygen consumption: Role in the global marine carbon cycle

Earth-Science Reviews, Journal Year: 2022, Volume and Issue: 228, P. 103987 - 103987

Published: March 12, 2022

The seabed plays a key role in the marine carbon cycle as a) terminal location of aerobic oxidation organic matter, b) greatest anaerobic bioreactor, and c) repository for reactive on Earth. We compiled data oxygen uptake sediments with objective to understand constraints mineralization rates deposited matter their relation environmental parameters. database includes nearly 4000 O2 is available supplementary material. It also information bottom water concentration, penetration depth, geographic position, full sources. present different situ ex approaches measure total (TOU) diffusive (DOU) discuss robustness towards methodological errors statistical uncertainty. transport through benthic boundary layers, diffusion- fauna-mediated uptake, coupling respiration processes. Five regional examples are presented illustrate diversity seabed: Eutrophic seas, minimum zones, abyssal plains, mid-oceanic gyres, hadal trenches. A multiple correlation analysis shows that primarily controlled by ocean depth sea surface primary productivity. scales DOU according power law breaks down under gyres. developed model was used draw global map rates. Respiratory coefficients, differentiated regions ocean, were convert oxidation. resulting budget an 212 Tmol C yr−1 5-95% confidence interval 175-260 yr−1. comparison flux particulate (POC) from photic waters deep sea, determined sediment trap studies, suggests deficit sedimentation at 2000 m about 70% relative turnover underlying seabed. At margins, rivers vegetated coastal ecosystems contributes greatly may even exceed phytoplankton production inner continental shelf.

Language: Английский

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Methane emissions offset atmospheric carbon dioxide uptake in coastal macroalgae, mixed vegetation and sediment ecosystems

Nature Communications, Journal Year: 2023, Volume and Issue: 14(1)

Published: Jan. 3, 2023

Coastal ecosystems can efficiently remove carbon dioxide (CO2) from the atmosphere and are thus promoted for nature-based climate change mitigation. Natural methane (CH4) emissions these may counterbalance atmospheric CO2 uptake. Still, knowledge of mechanisms sustaining such CH4 their contribution to net radiative forcing remains scarce globally prevalent macroalgae, mixed vegetation, surrounding depositional sediment habitats. Here we show that habitats emit in range 0.1 - 2.9 mg m-2 d-1 atmosphere, revealing situ macroalgae were sustained by divergent methanogenic archaea anoxic microsites. Over an annual cycle, CO2-equivalent offset 28 35% sink capacity attributed uptake vegetation habitats, respectively, augment release unvegetated sediments 57%. Accounting alongside sea-air fluxes identifying controlling is crucial constrain potential coastal as sinks develop informed mitigation strategies.

Language: Английский

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Cryptic CH4 cycling in the sulfate–methane transition of marine sediments apparently mediated by ANME-1 archaea

The ISME Journal, Journal Year: 2018, Volume and Issue: 13(2), P. 250 - 262

Published: Sept. 7, 2018

Language: Английский

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Widespread energy limitation to life in global subseafloor sediments

Science Advances, Journal Year: 2020, Volume and Issue: 6(32)

Published: Aug. 5, 2020

Microbial cells buried in subseafloor sediments comprise a substantial portion of Earth's biosphere and control global biogeochemical cycles; however, the rate at which they use energy (i.e., power) is virtually unknown. Here, we quantify organic matter degradation calculate power utilization microbial throughout Quaternary-age sediments. Aerobic respiration, sulfate reduction, methanogenesis mediate 6.9, 64.5, 28.6% degradation, respectively. The total sediment 37.3 gigawatts, less than 0.1% produced marine photic zone. heterotrophs largest share (54.5%) with median 2.23 × 10-18 watts per cell, while reducers methanogens 1.08 10-19 1.50 10-20 Most subsist fluxes lower have previously been shown to support life, calling into question limit life.

Language: Английский

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Anthropogenic and Environmental Constraints on the Microbial Methane Cycle in Coastal Sediments

Frontiers in Microbiology, Journal Year: 2021, Volume and Issue: 12

Published: Feb. 18, 2021

Large amounts of methane, a potent greenhouse gas, are produced in anoxic sediments by methanogenic archaea. Nonetheless, over 90% the methane is oxidized via sulfate-dependent anaerobic oxidation (S-AOM) sulfate-methane transition zone (SMTZ) consortia methane-oxidizing archaea (ANME) and sulfate-reducing bacteria (SRB). Coastal systems account for majority total marine emissions typically have lower sulfate concentrations, hence S-AOM less significant. However, alternative electron acceptors such as metal oxides or nitrate could be used AOM instead sulfate. The availability determined redox zonation sediment, which may vary due to changes oxygen type rate organic matter inputs. Additionally, eutrophication climate change can affect microbiome, biogeochemical zonation, cycling coastal sediments. This review summarizes current knowledge on processes microorganisms involved factors influencing from these systems. In eutrophic areas, inputs key driver bottom water hypoxia. Global warming reduce solubility surface waters, enhancing column stratification, increasing primary production, favoring methanogenesis. ANME notoriously slow growers not able effectively oxidize upon rapid sedimentation shoaling SMTZ. settings, ANME-2d ( Methanoperedenaceae ) ANME-2a couple iron- and/or manganese reduction AOM, while NC10 Methylomirabilota nitrite reduction. Ultimately, aerobic methanotrophs upper millimeters sediment column. role mitigating sediments, including exact pathways involved, still underexplored, controlling unclear. Further studies needed order understand driving methane-cycling identify responsible microorganisms. Integration microbial geochemical expected lead more accurate predictions zones future.

Language: Английский

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Silicate weathering in anoxic marine sediment as a requirement for authigenic carbonate burial

Earth-Science Reviews, Journal Year: 2019, Volume and Issue: 200, P. 102960 - 102960

Published: Nov. 18, 2019

Language: Английский

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Organoclastic sulfate reduction in the sulfate-methane transition of marine sediments

Geochimica et Cosmochimica Acta, Journal Year: 2019, Volume and Issue: 254, P. 231 - 245

Published: March 20, 2019

Language: Английский

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