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211	Carbon Dating of Agricultural Soils and Further Understanding the Transport of CO2 Gas Using Isotopes Zal, David 22 August 2023 (has links) CO2 is a greenhouse gas which is significantly emitted by agricultural soils through the decomposition of plant residue and soil organic carbon. Carbon isotopes can be used in determining the source of the CO2, origin of the carbon, and the age of the CO2 emissions. This study investigates the transport of CO2 gas through agricultural soils using carbon isotopes 14C and 13C to complement concentration and production rate measurements in two comparative agricultural settings in Eastern Ontario, one of which has been modified by clearing and dredging of the adjacent riparian zone and one left undredged. Traditional radiocarbon dating measures time through loss by decay, while recent dating is based on matching measurements with the atmospheric 14CO2 signal (F14C) generated by nuclear bomb testing in the 1950s and 1960s. CO2 emissions were analyzed from soil core sections together with soil-probe gas samples and surface flux chamber samples collected from the study area. Soil cores were collected from 0- 90 cm at 7.5 cm increments and placed into IsoJar® microcosms for a period of one month. CO2 in-growth was monitored to provide production rates and samples for 14C and 13C analysis. The radiocarbon data for the microcosms showed that values increase with depth from the current fraction modern value of 1.00 F14C at the surface to an attenuated peak of 1.04 F14C at a depth of 30 to 40 cm and then decrease to values below 1.00 F14C. The data collected from the soil-probe gas showed a significant depletion in comparison to the microcosms and the surface chambers. The soil cores were subsequently analyzed by a selective leach oxidation protocol to sample decreasingly labile solid organic carbon. This involved placing the weighed soil samples into MilliQ water for 24 hours, before being passed through two sieves, 63 microns and 0.45 microns. The DOC leachate was collected and analyzed for 14C and 13C. The two solid soil fractions were then dried, treated with HCl to remove carbonate and then oxidized under vacuum with 5% H2O2 yielding CO2 and residual soil carbon for 14C and 13C. The radiocarbon analysis of these variously labile fractions, together with the microcosm and soil probe measurements, demonstrate that surface emissions at both sites are greatly dominated by CO2 from recently-sequestered labile organic carbon from the upper 30 cm with minor contribution from earlier, bomb-pulse carbon or from deeper pre-bomb carbon. No significant difference in age of emissions between the dredged and undredged sites was found. Carbon dating Soil Organic Carbon Recalcitrant Carbon Green House Gases Fraction modern carbon Dissolved Organic Carbon C13 C14 Carbonate weathering Organic carbon Depth profile Agriculture Fields Agriculture Soil C3 C4 Carbon 13 Carbon 14 Radiocarbon Dating Dating of agriculture soils Carbon pool Carbon pool separation Recalcitrant Carbon
212	Äolische Prozesse und Landschaftsformen im mittleren Baruther Urstromtal seit dem Hochglazial der Weichselkaltzeit Boer, Wierd Mathijs de 16 November 2012 (has links) Das mittlere Baruther Urstromtal und Umgebung zwischen Luckenwalde und Golßen (Brandenburg, Deutschland) ist reich an äolischen Bildungen (DE BOER, 1990). Aus einer Kombination der bekannten Dünentypen (Parabel-, Längs-, Quer- und Kupstendünen) wird eine Reihe von 6 Dünenkomplexen abgeleitet. Sie sind aus einem oder mehreren Dünentypen aufgebaut und haben eine unterschiedliche Genese, Unterschiede im Alter und der Alterssfolge sowie eine bestimmte topographische Lage. Die (oberflächig anstehenden) Talsande/Flug(deck)sande, die Alt- und die Jungdünensande werden von Fein- bis Mittelsanden gebildet. In den jeweiligen Vertikalprofilen ist nach dem Körnungsbild eine Dreiteilung zu erkennen: die "liegenden" (Urstromtalterrassen-)Sande, die Altdünensande und die "hangenden" Jungdünensande. Das Liegende der ältesten Binnendünen ähnelt den Terrassensanden sehr. Daher darf angenommen werden, daß die oberen Urstromtalsande eine starke äolische Komponente besitzen. Altersbestimmungen wurden durch relative Positionierung, Feststellungen zur Art der Bodenbildungen, archäologische Funde, Pollenanalysen sowie Karten- und Literaturstudien vorgenommen, ergänzt durch Radiokarbon- (14C-) und Thermolumineszenzdatierungen. Eine methodische Neuerung ist die automatisierte Bearbeitung der Dünnschliffbilder. Mit dem Quantimet-970-Bildverarbeitungssystem wurde die Einregelung der Längsachsen von Quarzkörnern ermittelt. Die Messungen ergaben, dass die (N)NO-(S)SW-, die ONO-WSW- und die SSO-NNW-Richtungen vorherrschen. Es ist zu vermuten, dass die wichtigsten dünenbildenden Winde im Weichselspätglazial und im Holozän aus den westlichen und südlichen Quadranten wehten, wobei Südwestwinde vorgeherrscht haben dürften. Auf Grund der Forschungsergebnisse werden 12 Phasen der Dünenbildung unterschieden. Sie vermitteln ein Bild der äolischen Prozesse und Landschaftsformen, welches mit Daten aus Niedersachsen und West-Polen größtenteils übereinstimmt. / The Central Baruth Ice-Marginal Valley and surroundings between Luckenwalde and Golßen (Brandenburg, Germany) is rich in aeolian deposits and aeolian landscape forms DE BOER (1990). From a combination of the well-known dune forms (longitudinal, transverse, parabolic and hummocky dunes) a series of 6 dune complexes can be identified. These dune complexes are built by one or several dune types and differ in genesis or building sequence, in age or age sequence as well as in topographic position. The (surficial) valley/aeolian sands, the cover sands and the drift sands are mainly composed of fine- to medium-grained fractions. Based on grain-size analysis three units can be distinguished in the studied vertical profiles: the underlying (valley terrace) sands, the cover sands ("Altdünensande") and the overlying drift sands ("Jungdünensande"). The sands of the substratum of the oldest inland dunes are very similar to these dune sands. Therefore it is accepted that the upper parts of the valley sands contain a strong aeolian component. A modernization is the automated method of long axes orientation measurements on elongated quartz grains in thin sections with the Quantimet-970 Image Analyzer. The results showed that the (N)NE-(S)SW-, the ENE-WSW- and the SSE-NNW-directions dominated. It is to be expected that the most important dune building winds during the Weichselian Late Glacial and during the Holocene were winds from the western and southern quadrants, with southwest winds most likely being the most important. Dating was done by means of relative positioning, palaeosols, archaeological finds, pollen analysis, cartographic and literature research as well as by means of the 14C- and thermoluminescence dating methods. Based on the results of this research 12 dune-forming phases have been distinguished. They give an impression of aeolian processes and landscape forms that are in accordance with dates obtained from dunes in Niedersachsen and west Poland. Brandenburg Dünen Binnendünen Luckenwalde Baruth Flugsande Jungdünensande Altdünensande Sandlöss Windrichtungen äolische Landschaftsformen Datierungen Längsachseneinregelung Geomorphologie Geologie Thermolumineszenz Teltow-Fläming Golssen Klein Ziescht Klasdorf Schöbendorf Horstwalde Brandenburg dunes inland dunes aeolian sands drift sands cover sands loessy sands wind directions aeolian landforms datings long axes orientation geomorphology geology thermoluminescence dating Teltow-Fläming Baruth Luckenwalde Golssen Klein Ziescht Klasdorf Schöbendorf Horstwalde 550 Geowissenschaften 31 Geowissenschaften ddc:550
213	Postglazialer Anstieg des Meeresspiegels, Paläoklima und Hydrographie, aufgezeichnet in Sedimenten der Bermuda inshore waters / Postglacial rise of sea level, palaeoclimate and hydrography, recorded in sediments of the Bermuda inshore waters Vollbrecht, Rüdiger Dr. 13 January 1997 (has links) No description available. 550 Geowissenschaften Mathematics and Computer Science Postglazial Meeresspiegel Paläoklima Hydrography Bermuda Sedimente Pleistozän Holozän Quartär Seen Küste Laminite Solarzyklen Sonnenzyklen marin lakustrin Geologie Karbonate Böden Karst Torf Isotopen-Geochemie Altersbestimmung Fazies Paläökologie postglacial sea level palaeoclimate paleoclimate hydrography Bermuda sediments Pleistocene Holocene Quaternary inshore waters lakes laminites solar cycles lacustrine marine geology carbonates soil karst peat isotope geochemistry radiocarbon dating facies palaeoecology paleoecology 38.48 Marine Geologie 38.41 Sedimentation 38.82 Klimatologie 38.19 Historische Geologie: Sonstiges 38.32 Geochemie 38.88 Regionale Hydrologie 38.47 Moore 38.90 Ozeanologie Ozeanographie VAT 250 Litorale Sedimente VCA 520 Quartärgeologie VDI 210 Pleistozän VDI 220 Holozän VEW 200 Karibischer Raum VEZ 130 Inselgruppen TWC 600 Paläoklimatologie VKB 380 Sedimente bestimmter Regionen VKB 378 Rhytmite VKB 376 Organogene Sedimentgesteine VKB 340 Fazieskunde VKB 333 Sonstige Sedimentationsprozesse VKB 332 Sedimentationsbedingungen UHA 700 Marine Geologie (Küsten Watt Inselbildung etc.) UHA 440 Schwankungen
214	Aspects of ancient Near Eastern chronology (c. 1600-700 BC) Furlong, Pierce James January 2007 (has links) (PDF) The chronology of the Late Bronze and Early Iron Age Near East is currently a topic of intense scholarly debate. The conventional/orthodox chronology for this period has been assembled over the past one-two centuries using information from King-lists, royal annals and administrative documents, primarily those from the Great Kingdoms of Egypt, Assyria and Babylonia. This major enterprise has resulted in what can best be described as an extremely complex but little understood jigsaw puzzle composed of a multiplicity of loosely connected data. I argue in my thesis that this conventional chronology is fundamentally wrong, and that Egyptian New Kingdom (Memphite) dates should be lowered by 200 years to match historical actuality. This chronological adjustment is achieved in two stages: first, the removal of precisely 85 years of absolute Assyrian chronology from between the reigns of Shalmaneser II and Ashur-dan II; and second, the downward displacement of Egyptian Memphite dates relative to LBA Assyrian chronology by a further 115 years. Moreover, I rely upon Kuhnian epistemology to structure this alternate chronology so as to make it methodologically superior to the conventional chronology in terms of historical accuracy, precision, consistency and testability.

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