Das Alter der Federmesser-Zivilisation auf Grund neuer naturwissenschaftlicher Untersuchungen

Mit Hilfe verschiedener naturwissenschaftlicher Untersuchungsmethoden konnte die früher von uns als ausklingendes Magdalénien angesprochene Federmesser-Zivilisation des nordwesteuropäischen Flachlandes über die typologische Einstufung hinaus genau datiert werden. Nach der Pollenanalyse gehören alle drei Gruppen dieser Zivilisation - die Rissener, Wehlener und Tjonger-Gruppe - in das späte Alleröd oder in den Übergang Alleröd / Jüngere Dryaszeit. Durch C14-Messungen wurde dies bestätigt. Danach liegt das Alter der drei Federmesser-Gruppen etwa zwischen 9500 und 9000 v. Chr. Geb.researc

Das Alter des Schädels von Rhünda. III.: C14-Datierung der Fundschicht

Aus der Fundschicht des fossilen Menschenschädels von Rhünda wurden C14-Gehalt und C13-Abweichung von Kalksinter-Inkrustationen um Algen und Pflanzenhäcksel gemessen. Die Fundschicht ist danach 9000 Jahre, bei Berücksichtigung von möglicherweise eingelagertem Löß-Kalk mindestens 8500 Jahre alt und stammt somit aus dem späten Präboreal, allenfalls aus dem Beginn des Boreals.researc

Carbon-14 and Carbon-13 in Soil CO2

From the 10th International Radiocarbon Conference held in Bern, Switzerland and Heidelberg, Germany, August 19-26, 1979.Carbon isotope measurements in soil CO2 are presented and discussed. Soil CO2 concentration and 13C profiles were measured using a new technique. A simple model describing the CO2 transport from the soil to the atmosphere is derived. The finding that CO, in the soil is richer in 13C than the CO2 leaving the soil is attributed to isotopic fractionation in molecular diffusion.This material was digitized as part of a cooperative project between Radiocarbon and the University of Arizona Libraries.The Radiocarbon archives are made available by Radiocarbon and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform February 202

A Multi-Counter System for High Precision Carbon-14 Measurements

A new 14C detector system containing nine, independently working, CO2 proportional counters is described. The system is designed for a sufficient measuring capacity at a precision level better than sigma = +/- 2 per mil, which requires a counting time of about one week per sample. The size of the installation requires a simple and economic design of counters and electronics. A single anticoincidence shield for all counters consists of five newly developed flat counters. The modern counting rate (52 cpm) is sensitively checked by running Heidelberg sodium carbonate standard samples wth a counting rate of about 10 times modern. A microcomputer (DEC PDP-11/03) is used for data acquisition. Recent developments in laboratory techniques (preparation and gaschromatographic purification of samples) are also reported.This material was digitized as part of a cooperative project between Radiocarbon and the University of Arizona Libraries.The Radiocarbon archives are made available by Radiocarbon and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform February 202

On the 14C to Tritium Relationship in the North Atlantic Ocean

From the 10th International Radiocarbon Conference held in Bern, Switzerland and Heidelberg, Germany, August 19-26, 1979.Nuclear-weapon produced 14C (or bomb 14C) in the ocean can be traced by simultaneous tritium observations. Data are presented on the general relationship of bomb 14C and tritium in the North Atlantic. For the period 1965 to 1973, the excess 14C to tritium ratios in the surface water vary, systematically, over a factor of 10: the ratios monotonically increase with time, and decrease with latitude, particularly so for the later observations. The sub-surface water ratios show that the midand low-latitude water below about the 15 degrees C isothermal horizon (~500m depth) originates from higher northern latitudes, rather than being renewed by local vertical mixing. It is further shown that in the North Atlantic, bomb 14C did not penetrate beyond the horizon where the presently observed 14C concentration is Delta-14C = -75 per mil. Observed concentrations up to about -40 per mil can be corrected for a bomb contribution if the tritium concentration is known because the bomb 14C to tritium concentration ratio is rather uniform in this range. A surface water 14C concentration versus time curve is presented for the period since 1957. This curve is based on a North Atlantic mixing model and is fitted to the 14C observations. Making use of a previously published tritium versus time curve obtained by the same model, a time curve for the average excess 14C to tritium ratio in North Atlantic surface water is given. This curve reproduces the observations well. The presented data and theoretical curves show the usefulness of simultaneous 14C and tritium observations for mixing studies and to provide corrections for bomb 14C in sub-surface 14C data in the North Atlantic.This material was digitized as part of a cooperative project between Radiocarbon and the University of Arizona Libraries.The Radiocarbon archives are made available by Radiocarbon and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform February 202

Fast 14C Sample Preparation of Organic Material

From the 13th International Radiocarbon Conference held in Dubrovnik, Yugoslavia, June 20-25, 1988.A fast 14C sample preparation technique for organic material in conventional 14C counting is described. The basic difference from conventional preparation is oxidation of the organic substances in a closed system under an oxygen pressure of ca 10 bars. After the explosion-like combustion, the reaction products SO2 and NO2 are oxidized immediately to SO4^-2 and NO3^- and precipitated on the wall of the reaction vessel. The residual gis mixture is passed first through a cold trap at -78 degrees C to remove water vapor and then through an activated charcoal column at 0 degrees C for purification. CO2 is removed from the remaining O2-CO2 gas mixture in a LN2 trap at a pressure approximately equal to 100mbar. With this method sample preparation time is reduced from ca 10 hr to ca 1 hr. The efficiency and reproducibility of the procedure is shown with 14C and 13C measurements of a sugar-carbon standard. The results obtained by the new technique agree well with conventionally prepared wood and bone samples.This material was digitized as part of a cooperative project between Radiocarbon and the University of Arizona Libraries.The Radiocarbon archives are made available by Radiocarbon and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform February 202

A transatlantic 14C-section near 40°N

14C concentrations, as weil as 13C, hydrographic and nutrient data are reported for 5 hydrographic stations that form a transatlantic section near 40° N ("Meteor" cruise no. 23, 1971). Precision (for 14C ± 0.3% or better) and comparability with literature data are specified. A planned intercomparison with the US GEOSECS program within the Newfoundland Basin deep water failed because of variability of water characteristics. The observed 14C values decrease from about Δ 14C = + 80‰ at the surface to -70‰ at 2000 m depth. Deeper down, the values west of the Midatlantic Ridge remain similar, whereas those east of the ridge decrease further, to about -110‰. It is shown that bomb-14C is prominent down to about 1500 m depth. Beyond this depth the bomb 14C component is small and is negligible in the eastern basin below 2800 m. On the basis of the 14C-tritium correlation, the distribution of natural 14C below about 1500 m depth is derived from the observations. In the deep and bottom water east of the ridge the 14C-salinity relationship seemingly is non-linear. Contrary to expectation, the 14C concentration in the bottom water is not lower than found on an US GEOSECS station near 10° N. Apparently, lateral concentration differences in the Northeast Atlantic bottom water as well as nonlinearity of the 14C-salinity relationship at 40°N do not exceed 10‰ in Δ 14C

25 Years of Trospheric 14C Observations

A long-term mountain station series of tropospheric 14C data for the period 1959 to 1984 is presented. This series is considered representative of the higher altitude 14C level over central Europe. Even tree-ring 14C levels from a rural ground level site in southern Germany are consistently lower (by Delta-14C depression = -15 per mil if compared with the mountain station summer average in atmospheric CO2). The rural tree-ring series is considered to represent the additional continental Suess effect at ground level without local contamination. This Suess effect decreases gradually with the distance from the ground (ie, source) level. We therefore estimate the additional continental Suess effect in the vegetation period to be Delta-14C depression = -5 per mil for the mountain station and -20 per mil for a rural ground level site, respectively. Based on this assumption, yearly mean tropospheric 14C levels corrected for fossil fuel contamination and representative of the Northern Hemisphere are provided for use in global carbon cycle models.This material was digitized as part of a cooperative project between Radiocarbon and the University of Arizona Libraries.The Radiocarbon archives are made available by Radiocarbon and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform February 202

The geology, origin and age of the ground water supplies in some desert areas of U.A.R.

In a joint enterprise, the ground water supplies in some Oases in UAR (namely El Kharga, El Dakhla, El Baharia and Siwa), in Wadi El Natrun (to the west of the Nile Delta), in Ayoun Mousa (West Sinai) and in some places along the Mediterranean Littoral, have been investigated. According to the dating of the water by the C14 method, the age of the artesian water from the Oases is between 25,000 and 40,000 years and the origin is obviously from rain water which fell and infiltrated within the "Nubian Sandstone" layers, occupying almost entirely the southern portion of the western Desert (the water underwent some evaporation before it disappeared in the subsurface as indicated from the loss of the 016). This process took place during one or more of the Pluvial periods which followed (and were not coincident with) the last "Würm" eustatic lowering of the Mediterranean. No infiltration water have presumably recharged the layers in question, so almost entirely fossil water reserves are tapped at present. The quantities of such reserves are unknown. More ancient waters, however, may be expected to the north of El Kharga and El Dakhla Oases. Such waters may- to their greater portions - enter these two oases from that direction. On the other hand, little or almost no water is expected to feed the reservoir from the opposite direction

Radiocarbon Calibration Data for the 6th to the 8th Millennia BC

From the 12th International Radiocarbon Conference held in Trondheim, June 24-28, 1985.14C calibration curves derived from South German oak tree-ring series are presented. They cover the interval between 4400 and 7200 BC complementing existing data sets and extending them to older periods. The atmospheric 14C level before 6200 BC no longer follows the long-term sinusoidal trend fitted to the bristlecone data. This observation is supported by a tentative match of the Main 9 series.This material was digitized as part of a cooperative project between Radiocarbon and the University of Arizona Libraries.The Radiocarbon archives are made available by Radiocarbon and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform February 202