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  • 1
    In: Aquatic microbial ecology, Oldendorf, Luhe : Inter-Research, 1995, 34(2004), 1, Seite 93-104, 1616-1564
    In: volume:34
    In: year:2004
    In: number:1
    In: pages:93-104
    Description / Table of Contents: The role of transparent exopolymer particles (TEP) and dissolved organic carbon (DOC) for organic carbon partitioning under different CO2 conditions was examined during a mesocosm experiment with the coccolithophorid Emiliania huxleyi. We designed 9 outdoor enclosures (~11 m3) to simulate CO2 concentrations of estimated ŒYear 2100£ (~710 ppm CO2), Œpresent (~410 ppm CO2) and Œglacial (~190 ppm CO2) environments, and fertilized these with nitrate and phosphate to favor bloom development. Our results showed fundamentally different TEP and DOC dynamics during the bloom. In all mesocosms, TEP concentration increased after nutrient exhaustion and accumulated steadily until the end of the study. TEP concentration was closely related to the abundance of E. huxleyi and accounted for an increase in POC concentration of 35 ± 2% after the onset of nutrient limitation. The production of TEP normalized to the cell abundance of E. huxleyi was highest in the Year 2100 treatment. In contrast, DOC concentration exhibited considerable short-term fluctuations throughout the study. In all mesocosms, DOC was neither related to the abundance of E. huxleyi nor to TEP concentration. A statistically significant effect of the CO2 treatment on DOC concentration was not determined. However, during the course of the bloom, DOC concentration increased in 2 of the 3 Year 2100 mesocosms and in 1 of the present mesocosms, but in none of the glacial mesocosms. It is suggested that the observed differences between TEP and DOC were determined by their different bioavailability and that a rapid response of the microbial food web may have obscured CO2 effects on DOC production by autotrophic cells.
    Type of Medium: Online Resource
    Pages: Ill., graph. Darst
    ISSN: 1616-1564
    Language: English
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  • 2
    Publication Date: 2016-05-26
    Description: The role of transparent exopolymer particles (TEP) and dissolved organic carbon (DOC) for organic carbon partitioning under different CO2 conditions was examined during a mesocosm experiment with the coccolithophorid Emiliania huxleyi. We designed 9 outdoor enclosures (similar to11 m(3)) to simulate CO2 concentrations of estimated 'Year 2100' (similar to710 ppm CO2), 'present' (similar to410 ppm CO2) and 'glacial' (similar to190 ppm CO2) environments, and fertilized these with nitrate and phosphate to favor bloom development. Our results showed fundamentally different TEP and DOC dynamics during the bloom. In all mesocosms, TEP concentration increased after nutrient exhaustion and accumulated steadily until the end of the study. TEP concentration was closely related to the abundance of E. huxleyi and accounted for an increase in POC concentration of 35 2 % after the onset of nutrient limitation. The production of TEP normalized to the cell Abundance of E. huxleyi was highest in the Year 2100 treatment. In contrast, DOC concentration exhibited considerable short-term fluctuations throughout the study. In all mesocosms, DOC was neither related to the abundance of E. huxleyi nor to TEP concentration. A statistically significant effect of the CO2 treatment on DOC concentration was not determined. However, during the course of the bloom, DOC concentration increased in 2 of the 3 Year 2100 mesocosms and in 1 of the present mesocosms, but in none of the glacial mesocosms. It is suggested that the observed differences between TEP and DOC were determined by their different bioavailability and that a rapid response of the microbial food web may have obscured CO2 effects on DOC production by autotrophic cells.
    Type: Article , PeerReviewed
    Format: text
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  • 3
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    Springer
    In:  In: Ocean-Atmosphere Interactions of Gases and Particles. , ed. by Liss, P. and Johnson, M. T. Springer Earth System Sciences . Springer, Berlin, Germany, pp. 113-169. ISBN 978-3-642-25642-4
    Publication Date: 2019-09-23
    Description: Understanding and quantifying ocean–atmosphere exchanges of the long-lived greenhouse gases carbon dioxide (CO2), nitrous oxide (N2O) and methane (CH4) are important for understanding the global biogeochemical cycles of carbon and nitrogen in the context of ongoing global climate change. In this chapter we summarise our current state of knowledge regarding the oceanic distributions, formation and consumption pathways, and oceanic uptake and emissions of CO2, N2O and CH4, with a particular emphasis on the upper ocean. We specifically consider the role of the ocean in regulating the tropospheric content of these important radiative gases in a world in which their tropospheric content is rapidly increasing and estimate the impact of global change on their present and future oceanic uptake and/or emission. Finally, we evaluate the various uncertainties associated with the most commonly used methods for estimating uptake and emission and identify future research needs.
    Type: Book chapter , PeerReviewed
    Format: text
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  • 4
    Publication Date: 2022-01-31
    Description: The cryosphere, which comprises a large portion of Earth’s surface, is rapidly changing as a consequence of global climate change. Ice, snow, and frozen ground in the polar and alpine regions of the planet are known to directly impact atmospheric composition, which for example is observed in the large influence of ice and snow on polar boundary layer chemistry. Atmospheric inputs to the cryosphere, including aerosols, nutrients, and contaminants, are also changing in the anthropocene thus driving cryosphere-atmosphere feedbacks whose understanding is crucial for understanding future climate. Here, we present the Cryosphere and ATmospheric Chemistry initiative (CATCH) which is focused on developing new multidisciplinary research approaches studying interactions of chemistry, biology, and physics within the coupled cryosphere – atmosphere system and their sensitivity to environmental change. We identify four key science areas: (1) micro-scale processes in snow and ice, (2) the coupled cryosphere-atmosphere system, (3) cryospheric change and feedbacks, and (4) improved decisions and stakeholder engagement. To pursue these goals CATCH will foster an international, multidisciplinary research community, shed light on new research needs, support the acquisition of new knowledge, train the next generation of leading scientists, and establish interactions between the science community and society.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
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  • 5
    Publication Date: 2024-02-07
    Description: Leads play an important role in the exchange of heat, gases, vapour, and particles between seawater and the atmosphere in ice-covered polar oceans. In summer, these processes can be modified significantly by the formation of a meltwater layer at the surface, yet we know little about the dynamics of meltwater layer formation and persistence. During the drift campaign of the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC), we examined how variation in lead width, re-freezing, and mixing events affected the vertical structure of lead waters during late summer in the central Arctic. At the beginning of the 4-week survey period, a meltwater layer occupied the surface 0.8 m of the lead, and temperature and salinity showed strong vertical gradients. Stable oxygen isotopes indicate that the meltwater consisted mainly of sea ice meltwater rather than snow meltwater. During the first half of the survey period (before freezing), the meltwater layer thickness decreased rapidly as lead width increased and stretched the layer horizontally. During the latter half of the survey period (after freezing of the lead surface), stratification weakened and the meltwater layer became thinner before disappearing completely due to surface ice formation and mixing processes. Removal of meltwater during surface ice formation explained about 43% of the reduction in thickness of the meltwater layer. The remaining approximate 57% could be explained by mixing within the water column initiated by disturbance of the lower boundary of the meltwater layer through wind-induced ice floe drift. These results indicate that rapid, dynamic changes to lead water structure can have potentially significant effects on the exchange of physical and biogeochemical components throughout the atmosphere–lead–underlying seawater system.
    Type: Article , PeerReviewed
    Format: text
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  • 6
    Publication Date: 2024-03-19
    Keywords: ANTARES-IV; ANTARES-IV_005; Biogeochemical Processes in the Oceans and Fluxes; Bottle number; Carbon dioxide, total; CTD/Rosette; CTD-RO; DEPTH, water; JGOFS; Joint Global Ocean Flux Study; Marion Dufresne (1995); PROOF
    Type: Dataset
    Format: text/tab-separated-values, 24 data points
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  • 7
    Publication Date: 2024-03-19
    Keywords: ANTARES-IV; ANTARES-IV_007; Biogeochemical Processes in the Oceans and Fluxes; Bottle number; Carbon dioxide, total; CTD/Rosette; CTD-RO; DEPTH, water; JGOFS; Joint Global Ocean Flux Study; Marion Dufresne (1995); Oxygen; PROOF
    Type: Dataset
    Format: text/tab-separated-values, 33 data points
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  • 8
    Publication Date: 2024-03-19
    Keywords: Alkalinity, total; ANTARES-IV; ANTARES-IV_052; Biogeochemical Processes in the Oceans and Fluxes; Bottle number; CTD/Rosette; CTD-RO; DEPTH, water; JGOFS; Joint Global Ocean Flux Study; Marion Dufresne (1995); Oxygen; pH; PROOF
    Type: Dataset
    Format: text/tab-separated-values, 48 data points
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  • 9
    Publication Date: 2024-03-19
    Keywords: ANTARES-IV; ANTARES-IV_019; Biogeochemical Processes in the Oceans and Fluxes; Bottle number; Carbon dioxide, total; CTD/Rosette; CTD-RO; DEPTH, water; JGOFS; Joint Global Ocean Flux Study; Marion Dufresne (1995); PROOF
    Type: Dataset
    Format: text/tab-separated-values, 24 data points
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  • 10
    Publication Date: 2024-03-19
    Keywords: ANTARES-IV; ANTARES-IV_020; Biogeochemical Processes in the Oceans and Fluxes; Bottle number; Carbon dioxide, total; CTD/Rosette; CTD-RO; DEPTH, water; JGOFS; Joint Global Ocean Flux Study; Marion Dufresne (1995); PROOF
    Type: Dataset
    Format: text/tab-separated-values, 24 data points
    Location Call Number Limitation Availability
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