Mid- to Late Holocene elemental record and isotopic composition of lead in a peat core from Wolbrom (S Poland)

Peat Core W3 was taken from the fen in Wolbrom (Silesian-Cracovian Upland, Southern Poland) in September 2015. Previous analyses of Core W3 showed a significant increase in lead concentration during the time of the Roman Empire as well as some changes in peat accumulation conditions. The work reported here investigates its geochemical composition in terms of major and trace elements (Pb, Zn, Na, K, Ca, Fe, Mg, Mn, Cu, Ni, Cr by AAS) as well as Pb isotopic composition, to identify the sources of metal pollution in the Wolbrom peat deposit. The geochemical record spans the period from 4900 BC to modern times, with a likely hiatus corresponding to the period from the Middle Ages to the beginning of the contemporary metallurgical industry. The Pb isotopic composition combined with a cluster analysis allows identification of the primary sources of Pb. In addition, Principal Component Analysis (PCA) helps to decipher the most important factors that affected the chemical composition of sediments at Wolbrom. These factors were linked to chemical denudation and human activity

Dating WF16: Exploring the Chronology of a Pre-Pottery Neolithic A Settlement in the Southern Levant

A pre-requisite for understanding the transition to the Neolithic in the Levant is the establishment of a robust chronology, most notably for the late Epi-Palaeolithic and Pre-Pottery Neolithic A (PPNA) periods. In this contribution we undertake a dating analysis of the Pre-Pottery Neolithic site of WF16, southern Jordan, drawing on a sample of 46 AMS 14C dates. We utilise Bayesian methods to quantify an old wood effect to provide an offset that we factor into chronological models for a number of individual structures at WF16 and for the settlement as a whole. In doing so we address the influence of slope variations in the calibration curve and expose the significance of sediment and sample re-deposition within sites of this nature. We conclude that for the excavated deposits at WF16 human activity is likely to have started by c. 11.84ka cal BP and lasted for at least c. 1590 years, ceasing by c. 10.24ka cal BP. This is marked by a particularly intensive period of activity lasting for c. 350 years centred on 11.25ka cal BP followed by less intensive activity lasting a further c. 880 years. The study reveals the potential of WF16 as a laboratory to explore methodological issues concerning 14C dating of early Neolithic sites in arid, erosional environments

Reconstructing the accumulation history of a saltmarsh sediment core: which age-depth model is best?

Saltmarsh-based reconstructions of relative sea-level (RSL) change play a central role in current efforts seeking to quantify the relationship between climate and sea-level rise. The development of an accurate chronology is pivotal, since errors in age-depth relationships will propagate to the final record as alterations in both the timing and magnitude of reconstructed change. A range of age-depth modelling packages are available but differences in their theoretical basis and practical operation mean contrasting accumulation histories can be produced from the same dataset. We compare the performance of five age-depth modelling programs (Bacon, Bchron, Bpeat, Clam and OxCal) when applied to the kinds of data used in high resolution, saltmarsh-based RSL reconstructions. We investigate their relative performance by comparing modelled accumulation curves against known age-depth relationships generated from simulated stratigraphic sequences. Bpeat is particularly sensitive to non-linearities which, whilst maximising the detection of small rate changes, has the potential to generate spurious variations, particularly in the last 400 years. Bacon generally replicates the pattern and magnitude of change but with notable offsets in timing. Bchron and OxCal successfully constrain the known accumulation history within their error envelopes although the best-fit solutions tend to underestimate the magnitude of change. The best-fit solutions of Clam generally replicate the timing and magnitude of changes well, but are sensitive to the underlying shape of the calibration curve, performing poorly where plateaus in atmospheric 14C concentration exist. We employ an ensemble of age-depth models to reconstruct a 1500 year accumulation history for a saltmarsh core recovered from Connecticut, USA based on a composite chronology comprising 26 AMS radiocarbon dates, 210Pb, 137Cs radionuclides and an historical pollen chronohorizon. The resulting record reveals non-linear accumulation during the late Holocene with a marked increase in rate around AD1800. With the exception of the interval between AD1500 and AD1800, all modelsproduce accumulation curves that agree to within ~10 cm at the century-scale. The accumulation rate increase around AD1800 is associated with the transition from a radiocarbon-based to a 210Pb dominated chronology. Whilst repeat analysis excluding the 210Pb data alters the precise timing and magnitude of this acceleration, a shift to faster accumulation compared to the long-term rate is a robust feature of the record and not simply an artefact of the switch in dating methods. Simulation indicates that a rise of similar magnitude to the post-AD1800 increase (detrended increase of ~16 cm) is theoretically constrained and detectable within the radiocarbon-dated portion of the record. The absence of such a signal suggests that the recent rate of accumulation is unprecedented in the last 1500 years. Our results indicate that reliable (sub)century-scale age-depth models can be developed from saltmarsh sequences, and that the vertical uncertainties associated with them translate to RSL reconstruction errors that are typically smaller than those associated with the most precise microfossil-based estimates of palaeomarsh-surface elevation

A Computer-Based Database for Radiocarbon Dates of Central Andean Archaeology

We established a database of 14C dates from archaeological sites of the Central Andes region of Peru, Ecuador and Bolivia on an IBM PC-compatible microcomputer running on an MS-DOS operating system using software package dBASE IV, version 1.1. Relevant data are stored in three DBF-type database files. The file ANDY.DBF contains information on dates and samples; REFERENC.DBF contains references to relevant publications and CALAND.DBF contains calibrated dates. The total number of records of the ANDY database slightly exceeds 2650.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

Age-Depth Model of Lake Soppensee (Switzerland) Based on the High-Resolution 14C Chronology Compared with Varve Chronology

From the 20th International Radiocarbon Conference held in Kona, Hawaii, USA, May 31-June 3, 2009.An age-depth model for laminated sediments of Lake Soppensee is constructed using radiocarbon ages of macrofossils and a depositional model of the OxCal v 4.1 program with the updated IntCal09 data set. The resulting calendar chronology is compared with the varve chronology that was built for this record in a previous study (Hajdas 1993); there is a very good agreement between the 2 approaches. This illustrates the potential of high-resolution 14C dating for construction of reliable, high-resolution calendar timescales for sedimentary records. Based on the age-depth model of this study, the Vasset/Killian tephra found in sediment of Soppensee dates to a calendar age of 9291-9412 cal BP (2-delta range) while the Lachersee tephra dates to 12,735-12,871 cal BP (2-delta range). Precise dating of the Late Glacial boundaries is possible with this chronology but requires more precise correlation between proxies and records than typically practiced.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

Estimation of Gas Purity in a CO 2

From the 16th International Radiocarbon Conference held in Gronigen, Netherlands, June 16-20, 1997.Since 1994, a new data-acquisition system with rise-time (RT) based background reduction has been in operation at the Gliwice Radiocarbon Laboratory. During long-term stability tests, we observed large shifts in the RT spectra obtained during various measurement series. These shifts caused important changes in the count rate measured with RT reduction. As a result, we have ascertained that the shifts are the consequence of variable concentration of electronegative impurities. A correction method was considered, using average RT of pulses obtained in coincidence with the muon events, so-called ARTL (average rise time of L pulses), for estimation of the RT of the spectrum's shift. However, radiocarbon dates calculated based on count rates with RT discrimination, which were corrected using this method, are not more precise than traditional 14C dates. Nevertheless, the value of the average coincidence pulse RT is a good indication of sample gas purity.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

Estimation of Gas Purity in a CO2-Filled Proportional Counter by Rise-Time Analysis

From the 16th International Radiocarbon Conference held in Gronigen, Netherlands, June 16-20, 1997.Since 1994, a new data-acquisition system with rise-time (RT) based background reduction has been in operation at the Gliwice Radiocarbon Laboratory. During long-term stability tests, we observed large shifts in the RT spectra obtained during various measurement series. These shifts caused important changes in the count rate measured with RT reduction. As a result, we have ascertained that the shifts are the consequence of variable concentration of electronegative impurities. A correction method was considered, using average RT of pulses obtained in coincidence with the muon events, so-called ARTL (average rise time of L pulses), for estimation of the RT of the spectrum's shift. However, radiocarbon dates calculated based on count rates with RT discrimination, which were corrected using this method, are not more precise than traditional 14C dates. Nevertheless, the value of the average coincidence pulse RT is a good indication of sample gas purity.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

Variability of trace element concentrations in deposits of the Wolbrom and Otrębowskie Brzegi peatlands: a reflection of an anthropogenic impact

W artykule zaprezentowano analizę geochemiczną profili torfowych z dwóch torfowisk, położonych w Polsce Południowej, dokumentujących przedział czasowy od okresu atlantyckiego (od 4900 BC Wolbrom i od 4200 BC Otrębowskie Brzegi) do czasów współczesnych. Jej wyniki poddano analizie statystycznej z użyciem programu PAST, celem porównania badanych torfowisk pod względem wpływu działalności człowieka oraz położenia w różnych zlewniach, z uwzględnieniem przeprowadzonych wcześniej analiz botanicznych, datowania radiowęglowego i ołowiem-210 oraz analizy składu izotopowego Pb. Koncentracja pierwiastków w badanych profilach torfowych zależała od rodzaju osadu i była mocno zróżnicowana, wahając się w przedziale od wartości niskich, zbliżonych do lokalnego tła geochemicznego, aż do ekstremalnie wysokich (w szczególności w przypadku metali ciężkich, takich jak cynk i ołów). Przeprowadzona analiza porównawcza pozwoliła na zaobserwowanie synchronicznego zapisu lokalnych, jak i regionalnych zmian składu chemicznego w dwóch torfowiskach, różniących się lokalizacją, litologią i rodzajem torfu.A geochemical analysis was conducted on peat cores from two peatlands in Southern Poland that cover a time span from the Atlantic period (from 4900 BC in Wolbrom and from 4200 BC in Otrębowskie Brzegi) to modern times. The results were subjected to a statistical analysis using PAST software. The analysis was conducted taking into account previous botanical analyses, radiocarbon dating and lead-210 dating. The aim was to compare these two study sites in terms of their locations in different basins and anthropogenic activity. Elemental concentrations in the tested peat profiles were dependent on sediment type and their values range between very low (close to geochemical background values) and extremely high – especially in the case of heavy metals, like zinc and lead. The comparative analysis showed a synchronous record of local and regional changes of chemical composition in the two peatlands, which vary in terms of location, lithology and type of peat sediment

Frequency Distribution of Radiocarbon Dates as a Tool for Reconstructing Environmental Changes

From the 19th International Radiocarbon Conference held in Keble College, Oxford, England, April 3-7, 2006.Large sets of radiocarbon dates of 1019 peat, 155 speleothem, and 100 tufa samples, as well as dates of 330 fluvial samples, were investigated in order to estimate environmental variability during the last 16,000 calendar years in Poland. All 14C dating was carried out in the Gliwice Radiocarbon Laboratory, and results are stored in the RoS database. Probability density functions (PDFs) were created by summing up (on the calendar timescale) individual age probability distributions of all dates for different types of material and for different regions of Poland. We used an updated version of the Gliwice Radiocarbon Laboratory calibration program GdCALIB. The 14C dates were calibrated using the IntCal04 calibration curve (Reimer et al. 2004), and results were compared with other paleoenvironmental records. The authors conclude that analyzing PDFs of different types of sediments can be helpful in the qualitative reconstruction of the past environment. The PDF for peat samples primarily reflects paleohydrological conditions; the PDFs for speleothem and tufa samples reflect changes in temperature and humidity, while analysis of the PDF created for fluvial data is in a general agreement with the PDFs constructed for peat samples.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