Application of the Triple-Photomultiplier Liquid Spectrometer Hidex 300 SL in Radiocarbon Dating

The Hidex 300 SL is a liquid scintillation analyzer with an automatic sample changer and a triple-photomultiplier tube detection assembly that registers triple- as well as double-coincidence spectra. In the triple mode, the background in the 14C window is 13.7 cpm (14C standard 30.8 cpm; =154.3 cpm/5.01), so the factor of merit equals 8.7. The triple-to-double coincidence ratio (TDCR) allows for determining the 14C counting efficiency, the quench level, and quench correction. However, in the case of very low-activity samples, which is the case even for modern 14C samples, the TDCR is not the best method for the correction of benzene impurities. We propose using the position (channel) of the right slope of the sample (14C) logarithmic pulse-height spectrum. In the case of near-background samples, the cosmic muon peak can be used instead. The Monte Carlo modeling of spectra gave the 14C level below which the muon peak is a better quench correction parameter than the position of the 14C spectrum. The spectrometer, with the proposed quench correction method, was tested with wood samples dated dendrochronologically. For 21 samples, there is no systematic bias observed, and the standard deviation of the age differences scaled by the Poisson errors is 1.24 +/- 0.15, which means that the counting statistics account for 80% of the total variability (including sample preparation).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

Krakow Radiocarbon Measurements I

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

Infrasound fluctuations during heavy fog event in the Arctic: A case study

Extremely dense fog event was studied on the 3rd December 2001, which occurred in the city of Apatity, the Kola Peninsula, northwestern Russia. Fog had low visibility (30–50 m) and lasted 17 h. Variations of atmospheric pressure and electric field before and during the fog event were measured. Multiple Taper Method (MTM) of spectral analysis has revealed pulsations of the atmospheric electric field in the frequency band of 0.007–0.05 Hz with a power-law turbulence spectrum. MTM and wavelet decomposition analysis results indicate the appearance of two types of atmospheric pressure oscillations under the fog conditions: low-frequency variations with periods of internal gravity waves and a substantial increase in pulsation intensity (more than an order of magnitude) in the high frequency (0.03–0.35 Hz) range. These results may help to improve the understanding of the microphysics of fog formation, development, and dissipation. High-frequency pulsations generation of atmospheric pressure under the fog conditions is also of interest because their period is close to the range of infrasonic oscillations, which can have negative consequences for human health

Geology, stratigraphy and palaeoenvironmental evolution of the Stephanorhinus kirchbergensis-bearing Quaternary palaeolake(s) of Gorzów Wielkopolski (NW Poland, Central Europe)

The sedimentary succession exposed in the Gorzów Wielkopolski area includes Eemian Interglacial (MIS 5e) or Early Weichselian (MIS 5d–e) deposits. The sedimentary sequence has been the object of intense interdisciplinary study, which has resulted in the identification of at least two palaeolake horizons. Both yielded fossil remains of large mammals, alongside pollen and plant macrofossils. All these proxies have been used to reconstruct the environmental conditions prevailing at the time of deposition, as well as to define the geological context and the biochronological position of the fauna. Optically stimulated luminescence dating of the glaciofluvial layers of the GS3 succession to 123.6 ± 10.1 (below the lower palaeolake) and 72.0 ± 5.2 ka (above the upper palaeolake) indicate that the site formed during the Middle–Late Pleistocene (MIS 6 – MIS 5). Radiocarbon-dating of the lacustrine organic matter revealed a tight cluster of Middle Pleniglacial Period (MIS 3) ages in the range of ~41–32 ka cal bp (Hengelo – Denekamp Interstadials). Holocene organic layers have also been found, with C ages within a range of 4330–4280 cal bp (Neolithic). Pollen and plant macrofossil records, together with sedimentological and geochemical data, confirm the dating to the Eemian Interglacial.This research was supported by grant 0201/2048/18 ‘Life and death of extinctrhino (Stephanorhinus sp.) from Western Poland: a multiproxy palaeoenvironmental approach’ financed by the National Science Centre, Poland. LiDAR DTM data presented in this study were used under academic licences DIO.DFT.DSI.7211.1619.2015_PL_N and DIO.DFT.7211.9874. 2015_PL_N awarded to the Faculty of Earth Sciences and the Environmental Management University of Wrocław, in accordance with the Polish legal regulations of the administration of the Head Office of Land Surveying and Cartography

Atmospheric drying across Europe is unprecedented in a pre-industrial context

Vapour pressure deficit (VPD) represents the desiccation strength of the atmosphere, fundamentally impacting evapotranspiration, ecosystem functioning and vegetation productivity. Its spatial patterns and long-term changes under natural versus human-induced climate change are poorly understood but are essential for predicting its future ecological and socio-economic effects, e.g., on crop yield, bioclimatic comfort or wildfires. We combine regional reconstructions of pre-industrial summer VPD variability from a European tree-ring oxygen-isotope network with excellent climate sensitivity with observations and Earth System Model simulations. We demonstrate a recent human-induced intensification of atmospheric drying across Europe that exceeds natural variability specifically in the Alps and Pyrenees, but also in western, central and southern Europe. A less distinct increase occurs in Fennoscandia. This VPD increase may cause an enhanced risk of tree mortality, forest decline and yield reductionsevenin the temperate lowland regions of Europe, particularly when considering the extreme drought events in the recent years

Recent human-induced atmospheric drying across Europe unprecedented in the last 400 years

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