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  • Deep ocean  (1)
  • Dissolved organic matter (DOM)  (1)
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  • 1
    ISSN: 1573-5052
    Keywords: Bacterial utilization ; Bacterioplankton ; Dissolved organic matter (DOM) ; Radiation ; Ultraviolet-B (UV-B)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Attenuation of ultraviolet (UV)-radiation into the water column is highly correlated with the concentration of the dissolved organic matter (DOM). Thus UV penetrates deeper into marine waters than into freshwater systems. DOM is efficiently cleaved by solar surface radiation levels consuming more oxygen than bacterial metabolism. This photolytically cleaved DOM exhibits higher absorbance ratios (250/365 nm) than untreated DOM. Natural bacterioplankton reach higher abundance if inoculated in previously solar-exposed DOM than in untreated DOM; during bacterial growth the absorbance ratio declines steadily indicating the utilization of the photolytically cleaved DOM. On the other hand, bacterioplankton are greatly reduced in their activity if exposed to surface solar radiation levels. Photoenzymatic repair of DNA induced by UV-A radiation, however, leads to an efficient recovery of bacterial activity once the UV-B stress is released. Turbulent mixing of the upper layers of the water column leads to a continuous alteration of the UV exposure regime. Close to the surface, bacteria and DOM are exposed to high levels of UV-B leading to a reduction in bacterial activity and to photolysis of DOM. Once mixed into deeper layers where UV-B is attenuated, but sufficient UV-A is remaining to allow photoenzymatic repair, the photolytically cleaved DOM is efficiently taken up by bacterioplankton leading to even higher bacterial activity than prior to the exposure. Thus, the overall effect of UV on bacterioplankton is actually an enhancement of bacterial activity despite their lack of protective pigments.
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2023-03-11
    Description: © The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Conte, M., Pàmies, R., Honda, M., & Herndl, G. Editorial: the oceanic particle flux and its cycling within the deep water column. Frontiers in Earth Science, 10, (2022): 1020065, https://doi.org/10.3389/feart.2022.1020065.
    Description: The oceanic particle flux transfers energy and material from the surface through the water column to the seafloor. (See review by Conte (2019) and references therein). The particle flux fuels life below the sunlit photic zone, exerts a major control on the global cycling of carbon and particle-associated elements, and also plays a major role in long-term carbon sequestration. In this Research Topic we present a collection of articles that provide a broad overview of current research on the interlinked processes controlling the magnitude and composition of the oceanic particle flux, and its cycling and depth attenuation within the deep water column.
    Keywords: Particle flux ; Deep ocean ; Marine particles ; Ocean biogeochemistry ; Carbon cycling ; Marine chemistry
    Repository Name: Woods Hole Open Access Server
    Type: Article
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