نتایج جستجو برای: anoxic ocean
تعداد نتایج: 70018 فیلتر نتایج به سال:
Recurrent deposition of organic-rich sediment layers (sapropels) in the eastern Mediterranean Sea is caused by complex interactions between climatic and biogeochemical processes. Disentangling these influences is therefore important for Mediterranean palaeo-studies in particular, and for understanding ocean feedback processes in general. Crucially, sapropels are diagnostic of anoxic deep-water ...
Extensive and expanding oxygen minimum zones (OMZs) exist at variable depths in coastal and open ocean waters. As oxygen levels decline, nutrients and energy are increasingly diverted away from higher trophic levels into microbial community metabolism, resulting in fixed nitrogen loss and production of climate active trace gases including nitrous oxide and methane. While ocean deoxygenation has...
Multi-proxy approach for the reconstruction of paleo-redox conditions is attempted on a radiocarbon (14C) dated sediment core near the equatorial Indian Ocean. Based on the behavior and distribution of redox sensitive and productivity proxies, study demonstrates prevalence of anoxic bottom water conditions during LGM due to poorly ventilated bottom waters augmented by high surface productivity ...
Abstract Understanding the causal mechanisms of past marine deoxygenation is critical to predicting long-term Earth systems response climate change. However, processes and events preceding widespread carbon burial coincident with oceanic anoxic remain poorly constrained. Here, we report a comprehensive biomarker inventory enveloping Oceanic Anoxic Event 2 that captures microbial communities spa...
Today in Scientific Data, two compendia of geochemical and multi-omic sequence information (DNA, RNA, protein) generated over almost a decade of time series monitoring in a seasonally anoxic coastal marine setting are presented to the scientific community. These data descriptors introduce a model ecosystem for the study of microbial responses to ocean deoxygenation, a phenotype that is currentl...
Up to 7% of the modern ocean is considered to be devoid of oxygen, including upwelling regions on the western continental shelves and stratified marginal seas (Baltic Sea, Black Sea) as prominent examples (Wright et al. 2012). Oxygen depleted environments, and oxic-anoxic transition zones (redoxclines) in particular, are known as sites of high redox-driven microbial activity, with impacts on th...
Because animals require oxygen, an increase in late-Neoproterozoic oxygen concentrations has been suggested as a stimulus for their evolution. The iron content of deep-sea sediments shows that the deep ocean was anoxic and ferruginous before and during the Gaskiers glaciation 580 million years ago and that it became oxic afterward. The first known members of the Ediacara biota arose shortly aft...
An importance of diazotrophic cyanobacteria as a primary producer during Cretaceous Oceanic Anoxic Event 2 N. Ohkouchi, Y. Kashiyama, J. Kuroda, N. O. Ogawa, and H. Kitazato Institute for Research on Earth Evolution, Japan Agency for Marine-Earth Science and Technology, 2-15 Natsushima-cho Yokosuka 237-0061, Japan Department of Earth and Planetary Sciences, University of Tokyo, Hongo Bunkyo-ku ...
Reconstructing redox conditions in the paleo-ocean is essential to understand Earth’s biogeochemical evolution. Cerium (Ce) anomaly marine sediments has been used distinguish oxic versus anoxic depositional environments Paleo-ocean. Previous studies suggested that dissolved oxygen indispensable cerium oxidation. Therefore, this reaction can be thermodynamically modeled quantify contents ocean. ...
Diatom-bacteria aggregates are key for the vertical transport of organic carbon in the ocean. Sinking aggregates also represent pelagic microniches with intensified microbial activity, oxygen depletion in the center, and anaerobic nitrogen cycling. Since some of the aggregate-forming diatom species store nitrate intracellularly, we explored the fate of intracellular nitrate and its availability...
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