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  • 1
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Microcolumn Separations 4 (1992), S. 221-225 
    ISSN: 1040-7685
    Schlagwort(e): Azo-t-butane ; cross-linking ; immobilization ; capillary columns ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The ability of commercially available azo-t-butun (ATB) to facilitate immobilization of polysiloxane stationary phases in capillary columns deteriorates upon storage. Aged ATB produces columns with high bleed, solute retention shifts, erratic immobilization efficiency, and high activity. This deterioration is accelerated in the presence of light, suggesting free radical processes are involved. The loss of certain lowlevel impurities, which act as free radical transfer agents or radical sinks, may be responsible for the performance change. Regeneration can often temporarily be accomplished using platinum catalyzed reduction with trichlorosilane. The addition of small amounts of toluene or other radical transfer agents to aged ATB moderates the cross-linking process, allowing the reproducible production of columns with good immobilization efficiency, excellent intertness, low thermal bleed, and proper polarity.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Microcolumn Separations 4 (1992), S. 215-220 
    ISSN: 1040-7685
    Schlagwort(e): retention index ; supercritical fluid chromatography ; selectivity ; temperature ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Retention indices (RI) for a variety of probe compounds were determined on 50-μm i. d. columns coated with eight different stationary phases under density programmed SFC conditions at isothermal temperatures of 80 and 150°C. RI values were strongly dependent on temperature for polar probes on the polar phases containing high levels of cyanopropyl or polyethylene glycol (PEG) functionality. A lower apparent polarity was observed for polar columns at higher temperatures. Moderate RI differences were apparent with the same probes on columns with polarizable stationary phases of high phenyl or biphenyl content. Nonpolar alkyl substituted stationary phases showed only a slight temperature dependence on RI for all test compounds. Alkanes of lower molecular weight eluted at lower densities on all columns when the temperature was raised because of the contribution of volatility to elution in SFC. This same effect was observed for the higher alkanes on both nonpolar and PEG columns, but they eluted at similar densities on cyanopropyl columns and at higher densities on columns with polarizable phases when the temperature was raised. Temperature controlled selectivity tuning is a useful tool in optimizing separations in SFC.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Basel : Wiley-Blackwell
    Die Makromolekulare Chemie, Rapid Communications 6 (1985), S. 57-63 
    ISSN: 0173-2803
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 4
    Publikationsdatum: 2022-05-25
    Beschreibung: © The Author(s), 2018. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Scientific Reports 8 (2018): 15219, doi:10.1038/s41598-018-33283-4.
    Beschreibung: This Article corrects an error in Equation 1
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 5
    Publikationsdatum: 2022-05-25
    Beschreibung: © The Author(s), 2018. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Scientific Reports 8 (2018): 9478, doi:10.1038/s41598-018-26948-7.
    Beschreibung: Tidal wetlands produce long-term soil organic carbon (C) stocks. Thus for carbon accounting purposes, we need accurate and precise information on the magnitude and spatial distribution of those stocks. We assembled and analyzed an unprecedented soil core dataset, and tested three strategies for mapping carbon stocks: applying the average value from the synthesis to mapped tidal wetlands, applying models fit using empirical data and applied using soil, vegetation and salinity maps, and relying on independently generated soil carbon maps. Soil carbon stocks were far lower on average and varied less spatially and with depth than stocks calculated from available soils maps. Further, variation in carbon density was not well-predicted based on climate, salinity, vegetation, or soil classes. Instead, the assembled dataset showed that carbon density across the conterminous united states (CONUS) was normally distributed, with a predictable range of observations. We identified the simplest strategy, applying mean carbon density (27.0 kg C m−3), as the best performing strategy, and conservatively estimated that the top meter of CONUS tidal wetland soil contains 0.72 petagrams C. This strategy could provide standardization in CONUS tidal carbon accounting until such a time as modeling and mapping advancements can quantitatively improve accuracy and precision.
    Beschreibung: Synthesis efforts were funded by NASA Carbon Monitoring System (CMS; NNH14AY67I), USGS LandCarbon and the Smithsonian Institution. J.R.H. was additionally supported by the NSF-funded Coastal Carbon Research Coordination Network while completing this manuscript (DEB-1655622). J.M.S. coring efforts were funded by NSF (EAR-1204079). B.P.H. coring efforts were funded by Earth Observatory (Publication Number 197).
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 6
    Publikationsdatum: 2022-10-26
    Beschreibung: © The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Christie, M. A., Bernhardt, C. E., Parnell, A. C., Shaw, T. A., Khan, N. S., Corbett, D. R., Garcia-Artola, A., Clear, J., Walker, J. S., Donnelly, J. P., Hasse, T. R., & Horton, B. P. Pollen geochronology from the Atlantic Coast of the United States during the last 500 years. Water, 13(3), (2021): 362, https://doi.org/10.3390/w13030362.
    Beschreibung: Building robust age–depth models to understand climatic and geologic histories from coastal sedimentary archives often requires composite chronologies consisting of multi-proxy age markers. Pollen chronohorizons derived from a known change in vegetation are important for age–depth models, especially those with other sparse or imprecise age markers. However, the accuracy of pollen chronohorizons compared to other age markers and the impact of pollen chronohorizons on the precision of age–depth models, particularly in salt marsh environments, is poorly understood. Here, we combine new and published pollen data from eight coastal wetlands (salt marshes and mangroves) along the Atlantic Coast of the United States (U.S.) from Florida to Connecticut to define the age and uncertainty of 17 pollen chronohorizons. We found that 13 out of 17 pollen chronohorizons were consistent when compared to other age markers (radiocarbon, radionuclide 137Cs and pollution markers). Inconsistencies were likely related to the hyperlocality of pollen chronohorizons, mixing of salt marsh sediment, reworking of pollen from nearby tidal flats, misidentification of pollen signals, and inaccuracies in or misinterpretation of other age markers. Additionally, in a total of 24 models, including one or more pollen chronohorizons, increased precision (up to 41 years) or no change was found in 18 models.
    Beschreibung: MC was funded by the National Science Foundation EAR 1624551. NSK, TS, and BPH were funded by the Ministry of Education Academic Research Fund MOE2018-T2-1-030 and MOE2019-T3-1-004, the National Research Foundation Singapore, and the Singapore Ministry of Education, under the Research Centres of Excellence initiative. This article is a contribution to International Geoscience Program (IGCP) Project 639, “Sea Level Change from Minutes to Millennia”. This work is Earth Observatory of Singapore contribution 349. AP wishes to acknowledge the funding Science Foundation Ireland Career Development Award (17/CDA/4695); an investigator award (16/IA/4520); a Marine Research Programme funded by the Irish Government, co-financed by the European Regional Development Fund (Grant-Aid Agreement No. PBA/CC/18/01); European Union’s Horizon 2020 research and innovation programme under grant agreement No 818144; and SFI Research Centre awards 16/RC/3872 and 12/RC/2289_P2.
    Schlagwort(e): Pollen ; Age–depth models ; Geochronology ; Holocene ; Coastal wetlands
    Repository-Name: Woods Hole Open Access Server
    Materialart: Article
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 7
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    Unbekannt
    Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact: bco-dmo-data@whoi.edu
    Publikationsdatum: 2022-10-31
    Beschreibung: Dataset: Salt Marsh Water Exchange-Water
    Beschreibung: Surface and porewater salinity, radium/thorium radionuclide measurements, and nitrogen oxide concentration measurements. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at: https://www.bco-dmo.org/dataset/869708
    Beschreibung: NSF Division of Ocean Sciences (NSF OCE) OCE-1559274
    Schlagwort(e): Pore water exchange (PEX) ; Radium ; Disequilibrium ; Thorium ; Salt marsh
    Repository-Name: Woods Hole Open Access Server
    Materialart: Dataset
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 8
    Publikationsdatum: 2013-12-31
    Beschreibung: Physical and optical measurements taken over the mud belt on the southern continental shelf of Monterey Bay, California documented the frequent occurrence of suspended particulate matter features, the majority of which were detached from the seafloor, centered 9 to 33 meters above the bed. In fall 2011, an automated profiling mooring and fixed instrumentation, including a thermistor chain and upward-looking acoustic Doppler current profiler, were deployed at 70-m depth for 5 weeks, and from 12-16 October a long-range autonomous underwater vehicle performed across shelf transects. Individual SPM events were uncorrelated with local bed shear stress caused by surface waves and bottom currents. Nearly half of all observed SPM layers occurred during one week of the study, 9-16 October 2011, and were advected past the fixed profiling mooring by the onshore phase of semidiurnal internal tide bottom currents. At the start of the 9-16 October period we observed intense near-bed vertical velocities capable of lifting particulates into the middle of the water column. This “updraft” event appears to have been associated with nonlinear adjustment of high-amplitude internal tides over the mid and outer shelf. These findings suggest that nonlinear internal tidal motions can erode material over the outer shelf and that, once suspended this SPM can then be transported shoreward to the middle and shallow sections of the mud belt. This represents a fundamental broadening of our understanding of how shelf mud belts may be built up and sustained.
    Print ISSN: 0148-0227
    Thema: Geologie und Paläontologie , Physik
    Publiziert von Wiley-Blackwell im Namen von American Geophysical Union (AGU).
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 9
    Publikationsdatum: 2014-07-16
    Beschreibung: A nearly-year-long series of upper ocean temperature, conductivity, and temperature microstructure profiles were collected from an ice camp drifting in the Beaufort Gyre as part of the 1997-1998 Surface Heat Budget of the Arctic Experiment (SHEBA). Geographically, the record includes portions over the deep Canada Basin and the steep bathymetry of the Chukchi Borderlands region. Hydrographically, the record includes “cool”, Pacific-origin haloclines, which contain a variety of subsurface temperature maxima, and cold haloclines typical of the Eurasian Basins. We present estimates of the vertical turbulent diffusivity derived from the dissipation rate of thermal variance and calculations of the associated vertical heat fluxes. We find that vertical diffusion proceeds at molecular rates in the deep basins and away from topographic features. While still relatively small, diffusivity is enhanced by one order of magnitude near and above the Chukchi Borderlands. The enhanced diffusivity is correlated to an increase in water column strain variance above the Borderlands, providing a linkage between bathymetry, internal wave activity, and turbulence. The Chukchi Borderlands play a significant role in heat transport in the Western Arctic. They are a pathway for horizontal heat transport and a hotspot for vertical heat transport. Vertical fluxes make a substantial contribution to the energy balance of the sea ice cover in this region. Heat fluxes between the halocline and underlying Atlantic Water are shown to be small and lacking vertical connection near-surface waters.
    Print ISSN: 0148-0227
    Thema: Geologie und Paläontologie , Physik
    Publiziert von Wiley-Blackwell im Namen von American Geophysical Union (AGU).
    Standort Signatur Einschränkungen Verfügbarkeit
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