| 1. |
- Adolphi, Florian, et al.
(författare)
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Intercomparison of C-14 Dating of Wood Samples at Lund University and Eth-Zurich Ams Facilities: Extraction, Graphitization, and Measurement
- 2013
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Ingår i: Radiocarbon. - 0033-8222. ; 55:2-3, s. 391-400
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Tidskriftsartikel (refereegranskat)abstract
- We conducted an interlaboratory comparison between our radiocarbon-related research group at Lund University and the established ETH-Zurich facility to test the quality of the results obtained in Lund and to identify sources of potential background differences and scatter. We did find differences between the 2 laboratories in the contributions of chemical preparation, graphitization, and measurements to the overall background. The resulting overall background is, however, almost similar. Multiple measurements on 2 wood samples of known calendar age yield consistent and accurate C-14 ages in both laboratories. However, one of our known samples indicates that IntCal09 is similar to 38 +/- 16 C-14 BP too young at 7020 calendar yr BP, which is consistent with one of the raw data sets contributing to IntCal09. Overall, our results show that a systematic approach to compare the different steps involved in C-14 age determination is a useful exercise to pinpoint targets for improvement of lab routines and assess interlaboratory differences. These effects do not necessarily become apparent when comparing C-14 measurements that integrate over the whole process of preparation and measurement of different laboratories.
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| 2. |
- Blaauw, Maarten, et al.
(författare)
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A Bayesian framework for age-modelling of radiocarbon-dated peat deposits: case studies from the Netherlands
- 2007
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Ingår i: Radiocarbon. - 0033-8222 .- 1945-5755. ; 49:2, s. 357-367
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Tidskriftsartikel (refereegranskat)abstract
- Recently, Bayesian statistical software has been developed for age-depth modeling (“wiggle-match dating”) ofsequences of densely spaced radiocarbon dates from peat cores. The method is described in non-statistical terms, and is com-pared with an alternative method of chronological ordering of 14C dates. Case studies include the dating of the start of agri-culture in the northeastern part of the Netherlands, and of a possible Hekla-3 tephra layer in the same country. We discussfuture enhancements in Bayesian age modeling.
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| 3. |
- Bonsall, Clive, et al.
(författare)
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Food for Thought : Re-Assessing Mesolithic Diets in the Iron Gates
- 2015
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Ingår i: Radiocarbon. - : Cambridge University Press (CUP). - 0033-8222 .- 1945-5755. ; 57:4, s. 689-699
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Tidskriftsartikel (refereegranskat)abstract
- Stable isotope ratios of carbon, nitrogen, and sulfur in human bone collagen are used routinely to aid in the reconstruction of ancient diets. Isotopic analysis of human remains from sites in the Iron Gates section of the Lower Danube Valley has led to conflicting interpretations of Mesolithic diets in this key region of southeast Europe. One view (Bonsall et al. 1997, 2004) is that diets were based mainly on riverine resources throughout the Mesolithic. A competing hypothesis (Nehlich et al. 2010) argues that Mesolithic diets were more varied with at least one Early Mesolithic site showing an emphasis on terrestrial resources, and riverine resources only becoming dominant in the Later Mesolithic. The present article revisits this issue, discussing the stable isotope data in relation to archaeozoological and radiocarbon evidence.
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| 4. |
- Bronk Ramsey, Christopher, et al.
(författare)
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Development of the Intcal Database
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Ingår i: Radiocarbon. - 0033-8222.
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Tidskriftsartikel (refereegranskat)abstract
- The IntCal family of radiocarbon (14C) calibration curves is based on research spanning more than three decades. The IntCal group have collated the 14C and calendar age data (mostly derived from primary publications with other types of data and meta-data) and, since 2010, made them available for other sorts of analysis through an open-access database. This has ensured transparency in terms of the data used in the construction of the ratified calibration curves. As the IntCal database expands, work is underway to facilitate best practice for new data submissions, make more of the associated metadata available in a structured form, and help those wishing to process the data with programming languages such as R, Python, and MATLAB. The data and metadata are complex because of the range of different types of archives. A restructured interface, based on the "IntChron"open-access data model, includes tools which allow the data to be plotted and compared without the need for export. The intention is to include complementary information which can be used alongside the main 14C series to provide new insights into the global carbon cycle, as well as facilitating access to the data for other research applications. Overall, this work aims to streamline the generation of new calibration curves.
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| 5. |
- Dury, Jack P. R., et al.
(författare)
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CONSIDERATION OF FRESHWATER AND MULTIPLE MARINE RESERVOIR EFFECTS : DATING OF INDIVIDUALS WITH MIXED DIETS FROM NORTHERN SWEDEN
- 2018
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Ingår i: Radiocarbon. - 0033-8222 .- 1945-5755. ; 60:5, s. 1561-1585
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Tidskriftsartikel (refereegranskat)abstract
- Human burials from the cemetery at the Rounala church, northern Sweden, were radiocarbon (C-14) dated to shed light on the use of the cemetery. Carbon, nitrogen and sulfur stable isotope analysis of bone collagen from 19 distinct individuals indicated that these individuals had a mixed diet consisting of freshwater, marine and terrestrial resources. Dietary modeling using FRUITS was employed to calculate the contributions of the different resources for each individual. These data were then used to calculate individual Delta R values, taking into account freshwater and multiple marine reservoir effects, the latter caused by Baltic and Atlantic marine dietary inputs, respectively. C-14 dating of tissues from modern freshwater fish species demonstrate a lack of a freshwater reservoir effect in the area. Two OxCal models were used to provide endpoint age estimates. The calibrated data suggest that the site's cemetery was most likely in use already from the 14th century, and perhaps until at least the late 18th century.
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| 6. |
- Eilers, Gerriet, et al.
(författare)
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The Radiocarbon Intracavity Optogalvanic Spectroscopy Setup at Uppsala
- 2013
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Ingår i: Radiocarbon. - : Cambridge University Press (CUP). - 0033-8222 .- 1945-5755. ; 55:3-4, s. 237-250
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Tidskriftsartikel (refereegranskat)abstract
- Accelerator mass spectrometry (AMS) is by far the predominant technology deployed for radiocarbon tracer studies. Applications are widespread from archaeology to biological, environmental, and pharmaceutical sciences. In spite of its excellent performance, AMS is expensive and complicated to operate. Consequently, alternative detection techniques for 14C are of great interest, with the vision of a compact, user-friendly, and inexpensive analytical method. Here, we report on the use of intracavity optogalvanic spectroscopy (ICOGS) for measurements of the 14C/12C ratio. This new detection technique was developed by Murnick et al. (2008). In the infrared (IR) region, CO2 molecules have strong absorption coefficients. The IR-absorption lines are narrow in line width and shifted for different carbon isotopes. These properties can potentially be exploited to detect 14CO2, 13CO2, or 12CO2 molecules unambiguously. In ICOGS, the sample is in the form of CO2 gas, eliminating the graphitization step that h is required in most AMS labs. The status of the ICOGS setup in Uppsala is presented. The system is operational but not yet fully developed. Data are presented for initial results that illustrate the dependence of the optogalvanic signal on various parameters, such as background and plasma-induced changes in the sample gas composition.
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| 7. |
- Eriksson Stenström, Kristina, et al.
(författare)
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Environmental levels of radiocarbon in Lund, Sweden, prior to the start of the European Spallation Source
- 2022
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Ingår i: Radiocarbon. - 0033-8222. ; 64:1, s. 51-56
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Tidskriftsartikel (refereegranskat)abstract
- The European Spallation Source (ESS) is a neutron-based research facility under construction in Lund in southern Sweden. The spallation reactions will generate not only the desired neutrons, but also many radioactive byproducts, including 14C. As part of the licensing process, and as recommended by the IAEA, various preoperational studies are being carried out, including mapping the “zero-point” radiation environment around the site. As the city of Lund hosts several facilities using 14C-labeled substances, and since temporary and local 14C contamination have been observed in the past, 14C mapping is an important part of these baseline assessments. We here present a summary of 14C levels in various terrestrial environmental samples in Lund and in southern Sweden during the years 2012 to 2020. These environmental F14C do not display significantly elevated levels compared to sites located remote from Lund. We also describe a local 14C contamination event that was detected at the Lund Radiocarbon Dating Laboratory in 2009. Horse-chestnut leaves collected close to the laboratory exhibited F14C values of up to ∼25% above the clean air background. Elevated values of F14C were also found in a short tree-ring series, especially in 2007. The source of this contamination was identified and successfully removed.
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| 8. |
- Fahrni, Simon M., et al.
(författare)
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Single-Year German oak and Californian Bristlecone Pine C Data at the Beginning of the Hallstatt Plateau from 856 BC to 626 BC
- 2020
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Ingår i: Radiocarbon. - 0033-8222. ; 62:4, s. 919-937
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Tidskriftsartikel (refereegranskat)abstract
- As part of the ongoing effort to improve the Northern Hemisphere radiocarbon (C) calibration curve, this study investigates the period of 856 BC to 626 BC (2805-2575 yr BP) with a total of 403 single-year C measurements. In this age range, IntCal13 was constructed largely from German and Irish oak as well as Californian bristlecone pine C dates, with most samples measured with a 10-yr resolution. The new data presented here is the first atmospheric C single-year record of the older end of the Hallstatt plateau based on an absolutely dated tree-ring chronology. The data helped reveal a major solar proton event (SPE) which caused a spike in the production rate of cosmogenic radionuclides around 2610/2609 BP. This production event is thought to have reached a magnitude similar to the 774/775 AD production event but has remained undetected due to averaging effects in the decadal calibration data. The record leading up to the 2610/2609 BP event reveals a 11-yr solar cycle with varying cyclicity. Features of the new data and the benefits of higher resolution calibration are discussed.
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| 9. |
- Fischer, Anders, 1951, et al.
(författare)
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The Nekselø fish weir and marine reservoir effect in Neolithization period Denmark
- 2021
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Ingår i: Radiocarbon. - 0033-8222. ; 63:3, s. 805-820
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Tidskriftsartikel (refereegranskat)abstract
- The Nekselø Wickerwork provides an unusually solid estimate on the marine reservoir age in the Holocene. The basis for this result is a 5200-year-old fish weir, built of hazel wood with a brief biological age of its own. Oysters settled on this construction. They had lived only for a short number of years when the fence capsized and was covered in mud and the mollusks suffocated. Based on the difference in radiocarbon (14C) age between accelerator mass spectrometry (AMS) samples of oyster shells and wood, respectively, the marine reservoir age for this site is estimated to 273 ± 18 14C years. Re-evaluations of previously produced data from geological and archaeological sites of Holocene date in the Danish archipelago indicate marine reservoir ages in the same order as that of the Wickerwork. Consequently, we recommend the use of the new value, rather than the ca. 400 14C years hitherto favored, when correcting for the dietary induced reservoir effect in radiocarbon dates of humans and animals from the Late Mesolithic and Early Neolithic periods of this region.
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| 10. |
- Fogtmann-Schulz, Alexandra, et al.
(författare)
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Batch processing of tree-ring samples for radiocarbon analysis
- 2021
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Ingår i: Radiocarbon. - 0033-8222. ; 63:1, s. 77-89
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Tidskriftsartikel (refereegranskat)abstract
- We here present a comparison of methods for the pretreatment of a batch of tree rings for high-precision measurement of radiocarbon at the Aarhus AMS Centre (AARAMS), Aarhus University, Denmark. The aim was to develop an efficient and high-Throughput method able to pretreat ca. 50 samples at a time. We tested two methods for extracting α-cellulose from wood to find the most optimal for our use. One method used acetic acid, the other used HCl acid for the delignification. The testing was conducted on background 14C samples, in order to assess the effect of the different pretreatment methods on low-Activity samples. Furthermore, the extracted wood and cellulose fractions were analyzed using Fourier transform infrared (FTIR) spectroscopy, which showed a successful extraction of α-cellulose from the samples. Cellulose samples were pretreated at AARAMS, and the graphitization and radiocarbon analysis of these samples were done at both AARAMS and the radiocarbon dating laboratory at Lund University to compare the graphitization and AMS machine performance. No significant offset was found between the two sets of measurements. Based on these tests, the pretreatment of tree rings for high-precision radiocarbon analysis at AARAMS will henceforth use HCI for the delignification.
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