1,721,681 research outputs found
Paleoenvironmental events during the last 13,000 years in the central Red Sea as recorded by pteropoda
No full textA high-resolution record was obtained by investigating a sedimentary sequence from two cores taken in the central Red Sea (R/V Meteor cruise 5, leg 2). The numerical variations between nonmigratory and migratory pteropods and their stable isotopic record were studied together with variations in the carbonate and total organic carbon content in order to estimate changes in the structure of the water column during the last 13 kyr. The results indicate the existence of a highly stratified water column during deglaciation and early Holocene (13–8.5 ka). During this period the depth of the mixed layer varied between less than 50–100 m at most, and productivity was markedly reduced in comparison to the recent situation. The intermediate and deep water were constantly highly depleted in oxygen. A pronounced Younger Dryas event was recognized at 10.4 ka which coincides with an arid phase on the border land. The oxygenation of the intermediate water improved remarkably after 7.5 ka and peaked during the period between 4.6 and 2.0 ka. During this period the mixed layer reached its present depth and the productivity which was maximal during middle Holocene attained present level during the last 4.6 kyr
Response of Red Sea deep-water agglutinated foraminifera to water-mass changes during the Late Quaternary
No full textThree hundred eighty thousand year long stable isotope and faunal records from the Red Sea : influence of global sea level change on hydrography
Full text linkStable isotope and faunal records from the central Red Sea show high-amplitude oscillations for the past 380,000 years. Positive δ18O anomalies indicate periods of significant salt buildup during periods of lowered sea level when water mass exchange with the Arabian Sea was reduced due to a reduced geometry of the Bab el Mandeb Strait. Salinities as high as 53‰ and 55‰ are inferred from pteropod and benthic foraminifera δ18O, respectively, for the last glacial maximum. During this period all planktonic foraminifera vanished from this part of the Red Sea. Environmental conditions improved rapidly after 13 ka as salinities decreased due to rising sea level. The foraminiferal fauna started to reappear and was fully reestablished between 9 ka and 8 ka. Spectral analysis of the planktonic δ18O record documents highest variance in the orbital eccentricity, obliquity, and precession bands, indicating a dominant influence of climatically - driven sea level change on environmental conditions in the Red Sea. Variance in the precession band is enhanced compared to the global mean marine climate record (SPECMAP), suggesting an additional influence of the Indian monsoon system on Red Sea climates
Short gravity surface sediment cores from SE Skagerrak shelf, slope and deeps: Water, Pb210, Cs137, grain size and heavy metals, 1978-1980
No full text2 short surface sediment cores (13-93 cm; gravity cores 1 m, 80 mm iD) from shelf, slope and deeps of mid SE Skagerrak were analysed for water content, Pb210, and partly for Cs137, grain size and heavy metals. The data address sediment accumulation and modification in this hydrodynamically exposed area downslope to the deep depositional sites
On the influence of sea level and monsoon climate on the southern South China Sea freshwater budget over the last 22,000 years
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An Internally Consistent Dataset of delta13C-DIC in the North Atlantic Ocean - NAC13v1
No full textThe stable carbon isotope composition of dissolved inorganic carbon (δ13C-DIC) can be used to quantify fluxes within the carbon system. For example, knowing the δ13C signature of the inorganic carbon pool can help in describing the amount of anthropogenic carbon in the water column. The measurements can also be used for evaluating modeled carbon fluxes, for making basin-wide estimates of anthropogenic carbon, and for studying seasonal and interannual variability or decadal trends in interior ocean biogeochemistry. For all these purposes, it is not only important to have a sufficient amount of data, but these data must also be internally consistent and of high quality.
In this study, we present a δ13C-DIC dataset for the North Atlantic which has undergone secondary quality control. The data originate from oceanographic research cruises between 1981 and 2014. During a primary quality control step based on simple range tests, obviously bad data were flagged. In a second quality control step, biases between measurements from different cruises were quantified through a crossover analysis using nearby data of the respective cruises, and values of biased cruises were adjusted in the data product. The crossover analysis was possible for 24 of the 32 cruises in our dataset, and adjustments were applied to 11 cruises. The internal accuracy of this dataset is 0.017 ‰
(Table I) Metal, organic carbon and aluminium oxide concentrations in sediment core GIK10193-2
No full text(Table I) Metal, organic carbon and aluminium oxide concentrations in sediment core GIK10193-
Stable oxygen and carbon isotope ratios of planktonic foraminifera from sediment core MD99-2339
No full text(Table II) Radiocarbon ages and carbon isotope ratios in sediment core GIK10193-2
No full textFor radiocarbon ages, 1950 (AD) was taken as the reference year
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