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  • 1
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    PANGAEA
    In:  Supplement to: Kienast, Stephanie S; Calvert, Stephen E; Pedersen, Thomas F (2002): Nitrogen isotope and productivity variations along the northeast Pacific margin over the last 120 kyr: Surface and subsurface paleoceanography. Paleoceanography, 17(4), 1055, https://doi.org/10.1029/2001PA000650
    Publication Date: 2020-01-17
    Description: Glacial-interglacial changes in sedimentary d15N over the last 120 kyr display a remarkably similar pattern in timing and amplitude in core records extending from the denitrification zone in the eastern tropical North Pacific (ETNP), where subsurface denitrification is active, to the Oregon margin, where no denitrification occurs today. Low d15N values (4-6 per mil) generally characterize glacial stages 2 and 4, and higher d15N values (7-10 per mil) are representative of the Holocene, millennial-scale periods within stage 3, and stage 5. The inferred synchroneity of d15N variations along the entire margin implies that the nitrate isotopic signal produced in the oxygen-poor subsurface waters in the ETNP is rapidly advected northward and recorded at sites far beyond the boundaries of the modern denitrification zone. Similar to d15N, primary production indicators (percent Corg, Ba/Al, and percent opal) show glacial-interglacial as well as millennial-scale variations along the NE Pacific margin, with higher primary production during warm periods. However, the relative phasing between d15N and paleoproduction tracers within individual records changes latitudinally. Whereas d15N and primary production vary approximately synchronously in the midlatitudes, production lags d15N in the ETNP by several kiloyears. This lag calls for a new understanding of the processes driving denitrification in the ETNP. We suggest that oxygen input by the Equatorial Undercurrent as well as local organic matter flux controls denitrification rates in the ETNP. Moreover, the differences in relative timing point to a time-transgressive development of upwelling-favorable winds along the NE Pacific margin after the last glaciation, with those in the north developing several kiloyears earlier.
    Type: Dataset
    Format: application/zip, 5 datasets
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  • 2
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    PANGAEA
    In:  Supplement to: Crusius, John; Pedersen, Thomas F; Calvert, Stephen E; Cowie, Greg I; Oba, Tadamichi (1999): A 36 kyr geochemical record from the Sea of Japan of organic matter flux variations and changes in intermediate water oxygen concentrations. Paleoceanography, 14(2), 248-259, https://doi.org/10.1029/1998PA900023
    Publication Date: 2020-01-17
    Description: Intervals of organic C- and carbonate-rich laminated sediments occur in the Sea of Japan with roughly the same frequency as temperature changes observed in Greenland ice cores, providing clear evidence of rapid oceanographic change during the past 36 kyr. Planktonic foraminiferal d18O data suggest that only the laminated sediments deposited during the Last Glacial Maximum (LGM), and perhaps one other interval formed during a period of increased water column stratification. Sedimentary Re and Mo data are consistent with bottom waters that were sulfidic during the LGM and suboxic during other laminated intervals. Results of a numerical model of Corg and Re burial are consistent with a mechanism whereby an increased Corg flux to the seafloor drove oxygen concentrations toward depletion during times of deposition of the suboxic laminated intervals. Such a process could have resulted from increased upwelling driven either by increased deep water formation due to colder and/or more saline surface waters or by stronger northeasterly monsoonal winds.
    Type: Dataset
    Format: application/zip, 3 datasets
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  • 3
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    PANGAEA
    In:  Supplement to: Oba, Tadamichi; Pedersen, Thomas F (1999): Paleoclimatic Significance of Eolian Carbonates Supplied to the Japan Sea during the Last Glacial Maximum. Paleoceanography, 14(1), 34-41, https://doi.org/10.1029/98PA02507
    Publication Date: 2020-01-17
    Description: Laminated sediments deposited under anoxic bottom waters in the Japan Sea during the last glacial maximum (LGM) contain extremely well preserved calcareous microfossils and eolian carbonates. The radiocarbon age-difference between bulk sediment and monospecific planktonic foraminifera in discrete laminae from a core in the southern Japan Sea implies that ~40% of the total carbonates in the sediments at the LGM are of eolian origin. Extrapolation of this result yields a rate of supply of eolian carbonates of ~2800 tons/d to the entire Japan Sea during the LGM. The climatic significance of this flux potentially lies in its broader geographic extension, particularly in the interaction of the carbonate-bearing dust with shallow, corrosive North Pacific waters and with rain in the atmosphere. By increasing the alkalinity of such waters and by enhancing the biological pump the dust flux could have increased CO2 absorption by both the ocean and rain during the LGM.
    Type: Dataset
    Format: application/zip, 2 datasets
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  • 4
    Publication Date: 2020-01-17
    Type: Dataset
    Format: text/tab-separated-values, 18 data points
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  • 5
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    PANGAEA
    In:  Supplement to: Hendy, Ingrid L; Pedersen, Thomas F; Kennett, James P; Tada, Ryuji (2004): Intermittent existence of a southern Californian upwelling cell during submillennial climate change of the last 60 kyr. Paleoceanography, 19(3), PA3007, https://doi.org/10.1029/2003PA000965
    Publication Date: 2020-01-17
    Description: Application of a high-resolution multiproxy approach to a sedimentary section drilled at Ocean Drilling Program Site 1017, located under a highly active upwelling cell off Point Conception, California, provides clear evidence for surface ocean productivity shifts on submillennial timescales during the last 60 kyr. The proxies include bulk-sediment major and minor elements, organic carbon and carbonate concentrations, d15N, and planktonic foraminiferal species assemblage and carbon isotope determinations. The collective results demonstrate that marine productivity in this area was not simply linearly related to cold and warm cycles except during the millennial-scale climate oscillations of marine isotope stage (MIS) 3. During that interval, the upwelling cell and resulting high productivity were active during warm interstadial events and were largely inactive during cool stadial events. However, the Last Glacial Maximum was also relatively productive. Productivity increased dramatically during the Bølling warm interval, while the Ållerød and Younger Dryas were much less productive. High coccolithophorid abundance commenced during the earliest Holocene after 10 ka. The complexity of the productivity response was probably related to interplay between local winds, as well as California Undercurrent strength.
    Type: Dataset
    Format: application/zip, 2 datasets
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  • 6
    Publication Date: 2020-01-17
    Type: Dataset
    Format: text/tab-separated-values, 102 data points
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  • 7
    Publication Date: 2020-01-17
    Type: Dataset
    Format: text/tab-separated-values, 147 data points
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  • 8
    Publication Date: 2020-01-17
    Type: Dataset
    Format: text/tab-separated-values, 148 data points
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  • 9
    Publication Date: 2020-01-17
    Type: Dataset
    Format: text/tab-separated-values, 428 data points
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  • 10
    Publication Date: 2020-01-17
    Type: Dataset
    Format: text/tab-separated-values, 102 data points
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