ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Publication Date: 2018-02-12
    Description: The Permian-Triassic mass extinction represents the most severe environmental crisis in Earth’s history, which dictated the course for evolution of life until today. Volcanism from Siberian traps played a significant role involving a substantial input of relatively light carbon into the atmosphere leading to a combination of global warming by ~6°C, sporadic anoxia or euxinia, and ocean acidification. However, its detailed manifestation and environmental impact is yet to be fully understood. This lack of knowledge also extends to a better quantification of emitted and sequestered carbon budgets (cf. Gutjahr et al., 2017).
    Type: Article , NonPeerReviewed , info:eu-repo/semantics/article
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Publication Date: 2017-03-06
    Type: Conference or Workshop Item , NonPeerReviewed
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Publication Date: 2018-07-03
    Type: Conference or Workshop Item , NonPeerReviewed
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Publication Date: 2019-02-01
    Description: Lakes and reservoirs play an important role in the carbon cycle, and therefore monitoring their metabolic rates is essential. The triple oxygen-isotope anomaly of dissolved O2 [17Δ =  ln(1+δ17O) − 0.518  ×  ln(1 + δ18O)] offers a new, in situ, perspective on primary production, yet little is known about 17Δ from freshwater systems. We investigated the 17Δ together with the oxygen : argon ratio [Δ(O2 ∕ Ar)] in the subtropical Feitsui Reservoir in Taiwan from June 2014 to July 2015. Here, we present the seasonal variations in 17Δ, GP (gross production), NP (net production) and the NP ∕ GP (net to gross ratio) in association with environmental parameters. The 17Δ varied with depth and season, with values ranging between 26 and 205 per meg. The GP rates were observed to be higher (702 ± 107 mg C m−2 d−1) in winter than those (303 ± 66 mg C m−2 d−1) recorded during the summer. The overall averaged GP was 220 g C m−2 yr−1 and NP was −3 g C m−2 yr−1, implying the reservoir was net heterotrophic on an annual basis. This is due to negative NP rates from October to February (−198 ± 78 mg C m−2 d−1). Comparisons between GP rates obtained from the isotope mass balance approach and 14C bottle incubation method (14C–GP) showed consistent values on the same order of magnitude with a GP ∕ 14C–GP ratio of 1.2 ± 1.1. Finally we noted that, although typhoon occurrences were scarce, higher than average 17Δ values and GP rates were recorded after typhoon events.
    Type: Article , PeerReviewed
    Format: text
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    facet.materialart.
    facet.materialart.
    In:  (Doctoral thesis/PhD), Christian-Albrechts-Universität, Kiel, 144 pp
    Publication Date: 2019-02-01
    Type: Thesis , NonPeerReviewed
    Format: text
    Format: text
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    Publication Date: 2019-02-11
    Description: CO2-induced ocean acidification and associated decrease of seawater carbonate saturation state contributed to multiple environmental crises in Earth’s history, and currently poses a major threat for marine calcifying organisms. Owing to their high abundance and good preservation in the Phanerozoic geological record, brachiopods present an advantageous taxon of marine calcifiers for palaeo-proxy applications as well as studies on biological mechanism to cope with environmental change. To investigate the geochemical and physiological responses of brachiopods to prolonged low-pH conditions we cultured Magellania venosa, Terebratella dorsata and Pajaudina atlantica under controlled experimental settings over a period of more than two years. Our experiments demonstrate that brachiopods form their calcite shells under strong biological control, which enables them to survive and grow under low-pH conditions and even in seawater strongly undersaturated with respect to calcite (pH = 7.35, Ωcal = 0.6). Using boron isotope (δ11B) systematics including MC-ICP-MS as well as SIMS analyses, validated against in vivo microelectrode measurements, we show that this resilience is achieved by strict regulation of the calcifying fluid pH between the epithelial mantle and the shell. We provide a culture-based δ11B−pH calibration, which as a result of the internal pH regulatory mechanisms deviates from the inorganic borate ion to pH relationship, but confirms a clear yet subtle pH dependency for brachiopods. At a micro-scale level, the incorporation of 11B appears to be principally driven by a physiological gradient across the shell, where the δ11B values of the innermost calcite record the internal calcifying fluid pH while the composition of the outermost layers is also influenced by seawater pH. These findings are of consequence to studies on biomineralisation processes, physiological adaptations as well as past climate reconstructions.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Publication Date: 2019-02-12
    Description: In the last few decades and in the near future CO2-induced ocean acidification is potentially a big threat to marine calcite-shelled animals (e.g. brachiopods, bivalves, corals and gastropods). Despite the great number of studies focusing on the effects of acidification on shell growth, metabolism, shell dissolution and shell repair, the consequences for biomineral formation remain poorly understood. Only a few studies have addressed the impact of ocean acidification on shell microstructure and geochemistry. In this study, a detailed microstructure and stable isotope geochemistry investigation was performed on nine adult brachiopod specimens of Magellania venosa (Dixon, 1789). These were grown in the natural environment as well as in controlled culturing experiments under different pH conditions (ranging from 7.35 to 8.15 ± 0.05) over different time intervals (214 to 335 days). Details of shell microstructural features, such as thickness of the primary layer, density and size of endopunctae and morphology of the basic structural unit of the secondary layer were analysed using scanning electron microscopy. Stable isotope compositions (δ13C and δ18O) were tested from the secondary shell layer along shell ontogenetic increments in both dorsal and ventral valves. Based on our comprehensive dataset, we observed that, under low pH conditions, M. venosa produced a more organic-rich shell with higher density of and larger endopunctae, and smaller secondary layer fibres. Also, increasingly negative δ13C and δ18O values are recorded by the shell produced during culturing and are related to the CO2 source in the culture set-up. Both the microstructural changes and the stable isotope results are similar to observations on brachiopods from the fossil record and strongly support the value of brachiopods as robust archives of proxies for studying ocean acidification events in the geologic past.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , NonPeerReviewed , info:eu-repo/semantics/article
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Publication Date: 2019-02-18
    Description: Throughout the last few decades and in the near future CO2–induced ocean acidification is potentially a big threat to marine calcite-shelled animals (e.g., brachiopods, bivalves, corals and gastropods). Despite the great number of studies focusing on the effects of acidification on shell growth, metabolism, shell dissolution and shell repair, the consequences on biomineral formation remain poorly understood, and only few studies addressed contemporarily the impact of acidification on shell microstructure and geochemistry. In this study, a detailed microstructure and stable isotope geochemistry investigation was performed on nine adult brachiopod specimens of Magellania venosa (Dixon, 1789), grown in the natural environment as well as in controlled culturing experiments at different pH conditions (ranging 7.35 to 8.15±0.05) over different time intervals (214 to 335 days). Details of shell microstructural features, such as thickness of the primary layer, density and size of endopunctae and morphology of the basic structural unit of the secondary layer were analysed using scanning electron microscopy (SEM). Stable isotope compositions (δ13C and δ18O) were tested from the secondary shell layer along shell ontogenetic increments in both dorsal and ventral valves. Based on our comprehensive dataset, we observed that, under low pH conditions, M. venosa produced a more organic-rich shell with higher density of and larger endopunctae, and smaller secondary layer fibres, when subjected to about one year of culturing. Also, increasingly negative δ13C and δ18O values are recorded by the shell produced during culturing and are related to the CO2–source in the culture setup. Both the microstructural changes and the stable isotope results are similar to observations on brachiopods from the fossil record and strongly support the value of brachiopods as robust archives of proxies for studying ocean acidification events in the geologic past.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
    Format: archive
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Publication Date: 2019-02-26
    Type: Conference or Workshop Item , NonPeerReviewed
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    facet.materialart.
    facet.materialart.
    In:  [Poster] In: 8. International Brachiopod Congress 2018, 11.-14.09.2018, Milano, Italy .
    Publication Date: 2019-02-26
    Description: Marine biogenic carbonates have the potential to serve as a proxy for evolution of seawater chemistry. In order to compile a record of the past and recent δ7Li in the oceans, foraminifera shells, scleractinian corals and belemnites have been used. However, only a foraminifera-based record appears to more accurately reflect the Li isotope composition of ocean water. At present, this record is available for the Cenozoic with implications for major events during this period of time, including K/T event [1]. A record for the entire Phanerozoic has not yet been obtained. In order to extend this record to the more distant past, Li elemental/isotope systematics of brachiopods were investigated because these marine animals were already present in Early Cambrian oceans and because they are less sensitive to diagenesis-induced modifications due to their shell mineralogy (low-Mg calcite). The preliminary data indicates a species-, temperature- and salinity-independent behavior of Li isotopes in brachiopod shells. Also, no vital effects have been observed for different shell parts. The consistent offset of -4‰ relative to modern seawater is in accordance with experimental data [2]. Further data are now being collected for Cenozoic specimens to more rigorously test brachiopods as possible archives of past seawater in comparison to the existing foraminiferal records. [1] Misra & Froelich (2012) Science 335, 818-823 [2] Marriott et al. (2004) Chem Geol 212, 5-15
    Type: Conference or Workshop Item , NonPeerReviewed
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...