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  • 1
    Online Resource
    Online Resource
    Intracellular nitrate storage by diatoms can be an important nitrogen pool in freshwater and marine ecosystems
    Springer Science and Business Media LLC ; 2022
    In:  Communications Earth & Environment Vol. 3, No. 1 ( 2022-07-04)
    Details
    In: Communications Earth & Environment, Springer Science and Business Media LLC, Vol. 3, No. 1 ( 2022-07-04)
    Abstract: Identifying and quantifying nitrogen pools is essential for understanding the nitrogen cycle in aquatic ecosystems. The ubiquitous diatoms represent an overlooked nitrate pool as they can accumulate nitrate intracellularly and utilize it for nitrogen assimilation, dissipation of excess photosynthetic energy, and Dissimilatory Nitrate Reduction to Ammonium (DNRA). Here, we document the global co-occurrence of diatoms and intracellular nitrate in phototrophic microbial communities in freshwater ( n  = 69), coastal ( n  = 44), and open marine ( n  = 4) habitats. Diatom abundance and total intracellular nitrate contents in water columns, sediments, microbial mats, and epilithic biofilms were highly significantly correlated. In contrast, diatom community composition had only a marginal influence on total intracellular nitrate contents. Nitrate concentrations inside diatom cells exceeded ambient nitrate concentrations ∼100–4000-fold. The collective intracellular nitrate pool of the diatom community accounted for 〈 1% of total nitrate in pelagic habitats and 65–95% in benthic habitats. Accordingly, nitrate-storing diatoms are emerging as significant contributors to benthic nitrogen cycling, in particular through Dissimilatory Nitrate Reduction to Ammonium activity under anoxic conditions.
    Type of Medium: Online Resource
    ISSN: 2662-4435
    URL: Article
    DOI: 10.1038/s43247-022-00485-8
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2022
    detail.hit.zdb_id: 3037243-4
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  • 2
    Online Resource
    Online Resource
    Full in vivo characterization of carbonate chemistry at the site of calcification in corals
    American Association for the Advancement of Science (AAAS) ; 2019
    In:  Science Advances Vol. 5, No. 1 ( 2019-01-04)
    Details
    In: Science Advances, American Association for the Advancement of Science (AAAS), Vol. 5, No. 1 ( 2019-01-04)
    Abstract: Reef-building corals form their calcium carbonate skeletons within an extracellular calcifying medium (ECM). Despite the critical role of the ECM in coral calcification, ECM carbonate chemistry is poorly constrained in vivo, and full ECM carbonate chemistry has never been characterized based solely on direct in vivo measurements. Here, we measure pH ECM in the growing edge of Stylophora pistillata by simultaneously using microsensors and the fluorescent dye SNARF-1, showing that, when measured at the same time and place, the results agree. We then conduct microscope-guided microsensor measurements of pH, [Ca 2+ ], and [CO 3 2− ] in the ECM and, from this, determine [DIC] ECM and aragonite saturation state (Ω arag ), showing that all parameters are elevated with respect to the surrounding seawater. Our study provides the most complete in vivo characterization of ECM carbonate chemistry parameters in a coral species to date, pointing to the key role of calcium- and carbon-concentrating mechanisms in coral calcification.
    Type of Medium: Online Resource
    ISSN: 2375-2548
    URL: Article
    DOI: 10.1126/sciadv.aau7447
    Language: English
    Publisher: American Association for the Advancement of Science (AAAS)
    Publication Date: 2019
    detail.hit.zdb_id: 2810933-8
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  • 3
    Online Resource
    Online Resource
    Table_3.XLSX
    Frontiers Media SA ; 2021
    In:  Frontiers in Earth Science Vol. 9 ( 2021-4-30)
    Details
    In: Frontiers in Earth Science, Frontiers Media SA, Vol. 9 ( 2021-4-30)
    Abstract: Here we present the carbon isotopic composition of dissolved inorganic carbon (DIC) and the sulfur isotopic composition of sulfate, along with changes in sulfate concentrations, of the pore fluid collected from a series of sediment cores located along a depth transect on the Iberian Margin. We use these data to explore the coupling of microbial sulfate reduction (MSR) to organic carbon oxidation in the uppermost (up to nine meters) sediment. We argue that the combined use of the carbon and sulfur isotopic composition, of DIC and sulfate respectively, in sedimentary pore fluids, viewed through a δ 13 C DIC vs. δ 34 S SO4 cross plot, reveals significant insight into the nature of carbon-sulfur coupling in marine sedimentary pore fluids on continental margins. Our data show systemic changes in the carbon and sulfur isotopic composition of DIC and sulfate (respectively) where, at all sites, the carbon isotopic composition of the DIC decreases before the sulfur isotopic composition of sulfate increases. We compare our results to global data and show that this behavior persists over a range of sediment types, locations and water depths. We use a reactive-transport model to show how changes in the amount of DIC in seawater, the carbon isotopic composition of organic matter, the amount of organic carbon oxidation by early diagenetic reactions, and the presence and source of methane influence the carbon and sulfur isotopic composition of sedimentary pore fluids and the shape of the δ 13 C DIC vs. δ 34 S SO4 cross plot. The δ 13 C of the DIC released during sulfate reduction and sulfate-driven anaerobic oxidation of methane is a major control on the minimum δ 13 C DIC value in the δ 13 C DIC vs. δ 34 S SO4 cross plot, with the δ 13 C of the organic carbon being important during both MSR and combined sulfate reduction, sulfate-driven AOM and methanogenesis.
    Type of Medium: Online Resource
    ISSN: 2296-6463
    URL: Article
    URL: Article
    URL: Article
    URL: Article
    URL: Article
    DOI: 10.3389/feart.2021.652960
    DOI: 10.3389/feart.2021.652960.s001
    DOI: 10.3389/feart.2021.652960.s002
    DOI: 10.3389/feart.2021.652960.s003
    DOI: 10.3389/feart.2021.652960.s004
    Language: Unknown
    Publisher: Frontiers Media SA
    Publication Date: 2021
    detail.hit.zdb_id: 2741235-0
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