Radiocarbon最新文献

{"title":"EARLY HOLOCENE OXYGEN ISOTOPE CHRONOLOGIES (11,267–6420 CAL BP) FROM ICE WEDGE AT CHARA, TRANSBAIKALIA","authors":"Yurij K Vasil’chuk, Alla C Vasil’chuk, Nadine A Budantseva, Alexander P Ginzburg, Igor V Tokarev, Jessica Yu Vasil’chuk","doi":"10.1017/rdc.2024.34","DOIUrl":"https://doi.org/10.1017/rdc.2024.34","url":null,"abstract":"Accelerator mass spectrometry radiocarbon (AMS <jats:sup>14</jats:sup>C) dating was used for determining the age of wedge ice. It has been found that between 11,270 and 6420 cal BP, or the Greenlandian and Northgrippian stages of the Holocene, ice wedges grew syngenetically in sandy deposits with gravel in the Chara River valley. The variations of δ<jats:sup>18</jats:sup>O values in the ice wedges are about 8‰, from –25.5‰ to –18.8‰. Based on the stable isotope composition of ice wedges, paleotemperature reconstructions revealed that the mean January temperature was as low as –38°C during the coldest periods of the early half of the Holocene and as high as –28°C during the warmer periods.","PeriodicalId":21020,"journal":{"name":"Radiocarbon","volume":null,"pages":null},"PeriodicalIF":8.3,"publicationDate":"2024-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140560130","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"NEW PERSPECTIVES ON OLD MATTERS: A REVIEW OF ARCHAEOLOGICAL AND CHRONOMETRIC DATA FROM ABRIGO DO SOL (MATO GROSSO, BRAZIL)","authors":"Simon-Pierre Gilson, Lucas Bueno","doi":"10.1017/rdc.2024.30","DOIUrl":"https://doi.org/10.1017/rdc.2024.30","url":null,"abstract":"<p>Based on the study of the primary documentation related to the excavations carried out by Eurico Miller in the 1970s at Abrigo do Sol, Mato Grosso (Brazil), we propose a new reading of the stratigraphic and chronological information obtained from this rock shelter. Despite the apparent incongruity in the chrono-stratigraphic distribution of published dates, a detailed examination of the stratigraphy and field notes allowed us to identify a chronometric sequence with regular distribution between the Middle Holocene and the Late Pleistocene periods for the Abrigo do Sol site. We present here the original documents related to radiocarbon dating and their analysis. We finally show the implications of this study for understanding this site and the discussions related to the ancient settlements of the Amazon forest.</p>","PeriodicalId":21020,"journal":{"name":"Radiocarbon","volume":null,"pages":null},"PeriodicalIF":8.3,"publicationDate":"2024-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140559921","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"ADDRESSING THE INTENSITY OF CHANGES IN THE PREHISTORIC POPULATION DYNAMICS: POPULATION GROWTH RATE ESTIMATIONS IN THE CENTRAL BALKANS EARLY NEOLITHIC","authors":"Tamara Blagojević, Marko Porčić, Sofija Stefanović","doi":"10.1017/rdc.2024.23","DOIUrl":"https://doi.org/10.1017/rdc.2024.23","url":null,"abstract":"The intensity of changes in the population dynamics of the Early Neolithic (ca. 6250–5300 cal BC) communities in the Central Balkans was addressed by estimating the growth rate values. The Bayesian approach (Crema and Shoda 2021) of estimating intrinsic growth rates by fitting different models of population growth was applied to radiocarbon dates from the Early Neolithic sites in Serbia. We explored two possible episodes of population growth based on the results of the population dynamics reconstruction using the summed calibrated radiocarbon probability distributions (SPD) method. The results have shown that, within the first episode of growth, the intrinsic growth rate mean values are higher than the estimated continental average (between 1% and 2%). The results indicate a sudden and fast rise in population size, possibly due to the influx of the new population settling in the region at the beginning of the Neolithic. Lower values for the second episode could indicate more gradual population growth due to the mechanisms associated with the Neolithic Demographic Transition and the rise in fertility.","PeriodicalId":21020,"journal":{"name":"Radiocarbon","volume":null,"pages":null},"PeriodicalIF":8.3,"publicationDate":"2024-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140560698","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"IMPROVING IONPLUS MICADAS PERFORMANCE WITH RECESSED GRAPHITE","authors":"Taylor A B Broek, Mark L Roberts","doi":"10.1017/rdc.2024.36","DOIUrl":"https://doi.org/10.1017/rdc.2024.36","url":null,"abstract":"Cathodes with recessed sample surfaces have several benefits in cesium sputter ion sources, including higher output, more efficient use of sample material, and improved focusing of the extracted ion beam. However, the Ionplus MICADAS uses cathodes with a graphite surface that is essentially flush with the sample holder. To evaluate the performance of recessed graphite with the MICADAS and determine the optimal surface depth, we tested four different depths, including the standard (flush) pressing method, 0.5 mm, 1.0 mm, and 1.5 mm. We found that recessed depths of 1.0 and 1.5 mm resulted in 20% higher ion beam current compared to the standard method under the same source conditions. The results are consistent with the beam produced from the recessed targets being more narrowly focused with a lower emittance, resulting in better transmission through the accelerator. Small graphite samples (200 µg C) with recessed surfaces produced higher currents for longer, leading to a 2–3× increase in sample ionization efficiency. Additionally, there was some evidence that isotopic ratio measurements of recessed samples were more stable over time. Overall, samples recessed to 1 mm depth offered numerous advantages over the standard pressing method and we have subsequently started pressing all MICADAS graphite using this approach.","PeriodicalId":21020,"journal":{"name":"Radiocarbon","volume":null,"pages":null},"PeriodicalIF":8.3,"publicationDate":"2024-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140560365","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"DISCUSSION: PRESENTATION OF ATMOSPHERIC 14CO2 DATA","authors":"Stephen E Schwartz, Quan Hua, David E Andrews, Ralph F Keeling, Scott J Lehman, Jocelyn C Turnbull, Paula J Reimer, John B Miller, Harro A J Meijer","doi":"10.1017/rdc.2024.27","DOIUrl":"https://doi.org/10.1017/rdc.2024.27","url":null,"abstract":"<p>Observations of radiocarbon (<span>14</span>C) in Earth’s atmosphere and other carbon reservoirs are important to quantify exchanges of CO<span>2</span> between reservoirs. The amount of <span>14</span>C is commonly reported in the so-called Delta notation, i.e., Δ<span>14</span>C, the decay- and fractionation-corrected departure of the ratio of <span>14</span>C to total C from that ratio in an absolute international standard; this Delta notation permits direct comparison of <span>14</span>C/C ratios in the several reservoirs. However, as Δ<span>14</span>C of atmospheric CO<span>2</span>, Δ<span>14</span>CO<span>2</span> is based on the ratio of <span>14</span>CO<span>2</span> to total atmospheric CO<span>2</span>, its value can and does change not just because of change in the amount of atmospheric<span>14</span>CO<span>2</span> but also because of change in the amount of total atmospheric CO<span>2</span>, complicating ascription of change in Δ<span>14</span>CO<span>2</span> to change in one or the other quantity. Here we suggest that presentation of atmospheric <span>14</span>CO<span>2</span> amount as mole fraction relative to dry air (moles of <span>14</span>CO<span>2</span> per moles of dry air in Earth’s atmosphere), or as moles or molecules of <span>14</span>CO<span>2</span> in Earth’s atmosphere, all readily calculated from Δ<span>14</span>CO<span>2</span> and the amount of atmospheric CO<span>2</span> (with slight dependence on δ<span>13</span>CO<span>2</span>), complements presentation only as Δ<span>14</span>CO<span>2</span>, and can provide valuable insight into the evolving budget and distribution of atmospheric <span>14</span>CO<span>2</span>.</p>","PeriodicalId":21020,"journal":{"name":"Radiocarbon","volume":null,"pages":null},"PeriodicalIF":8.3,"publicationDate":"2024-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140302806","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A TIME-INTEGRATED SAMPLER FOR RADIOCARBON ANALYSIS OF AQUATIC METHANE","authors":"M H Garnett, J F Dean","doi":"10.1017/rdc.2024.31","DOIUrl":"https://doi.org/10.1017/rdc.2024.31","url":null,"abstract":"<p>Freshwater ecosystems are responsible for a large proportion of global methane emissions to the atmosphere. The radiocarbon (<span>14</span>C) content of this aquatic methane is useful for determining the age and source of this important greenhouse gas. Several methods already exist for the collection of aquatic methane for radiocarbon analysis, but they tend to only sample over short periods of time, which can make them unsuitable for characterizing aquatic methane over longer timespans, and vulnerable to missing short-term events. Here, we describe a new time-integrated method for the collection of aquatic methane that provides samples suitable for radiocarbon analysis, that are representative for periods of up to at least 16 days. We report the results of a suite of tests undertaken to verify the reliability of the method, and the <span>14</span>C age of aquatic methane from field trials undertaken at sites within Scotland, UK. We believe that this new method provides researchers with a simple approach that is easily deployable and can be used to collect representative time-integrated samples of methane for radiocarbon analysis from a wide range of aquatic environments.</p>","PeriodicalId":21020,"journal":{"name":"Radiocarbon","volume":null,"pages":null},"PeriodicalIF":8.3,"publicationDate":"2024-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140302603","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"FIRST DIRECT RADIOCARBON DATING (22–27 CAL KA BP) OF MASSIVE ICE AT THE MECHIGMEN AND LAVRENTIYA BAYS COAST, EASTERN CHUKOTKA","authors":"Yurij K Vasil’chuk, Nadine A Budantseva, Alexey A Maslakov, Alla C Vasil’chuk, Jessica Yu Vasil’chuk","doi":"10.1017/rdc.2024.21","DOIUrl":"https://doi.org/10.1017/rdc.2024.21","url":null,"abstract":"<p>The Eastern Chukotka is considered a unique permafrost region where massive ice bodies are widespread. However, the origin and age of these ice formations are often discussed. The age of the massive ice of Chukotka was established for the first time using AMS <span>14</span>C dating. It was revealed that three massive ice bodies on the coast of Mechigmen Bay were formed at the end of the Late Pleistocene: a) near the Akkani site, 21,612 to 22,147 cal BP; b) near the Lavrentiya settlement, 27,553 cal BP; and c) near the Lavrentiya settlement, 22,193 cal BP. Stable isotope values in the studied massive ice vary in a rather wide range by about 10‰ for δ<span>18</span>O values (from –14.8‰ to –24.5‰) and about 75‰ for the δ<span>2</span>H values (from –116‰ to –191‰). The studied massive ice bodies are of intrasedimental genesis and formed epigenetically during the final stage of MIS2 (22–27 cal ka BP).</p>","PeriodicalId":21020,"journal":{"name":"Radiocarbon","volume":null,"pages":null},"PeriodicalIF":8.3,"publicationDate":"2024-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140302683","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"ASSESSING 14C BLANKS IN THE SMALL-SCALE ANALYSIS OF N-ALKANE COMPOUND-SPECIFIC-RADIOCARBON-ANALYSIS","authors":"Kristina Reetz, Ronny Friedrich, Jago J Birk, Wilfried Rosendahl, Sabine Fiedler","doi":"10.1017/rdc.2024.26","DOIUrl":"https://doi.org/10.1017/rdc.2024.26","url":null,"abstract":"Compound-specific radiocarbon analysis (CSRA) provides the possibility to date sample material at a molecular level. <jats:italic>N</jats:italic>-alkanes are considered as specific compounds with high potential to CSRA. As these compounds originate from plant waxes, their radiocarbon (<jats:sup>14</jats:sup>C) analysis can provide valuable information about the age and origin of organic materials. This helps to reconstruct and understand environmental conditions and changes in vegetation in the past. However, CSRA has two main challenges: The small sample size of CSRA samples, making them extremely sensitive to blank effects, and the input of unknown amounts of extraneous carbon during the analytical procedure. According to the previous study from Sun and co-workers, we used different-sized aliquots of leaves <jats:italic>Fagus sylvatica</jats:italic> (<jats:italic>n</jats:italic>C27, <jats:italic>n</jats:italic>C29) and <jats:italic>Festuca rubra agg</jats:italic> (<jats:italic>n</jats:italic>C31, <jats:italic>n</jats:italic>C33) as modern standards and two commercial standards (<jats:italic>n</jats:italic>C26, <jats:italic>n</jats:italic>C28) as fossil standards for blank determination. A third commercial standard (<jats:italic>n</jats:italic>C27) with predetermined radiocarbon content of F<jats:sup>14</jats:sup>C = 0.71 (<jats:sup>14</jats:sup>C age of 2700 BP) serves to evaluate the blank correction. We found that the blank assessment of Sun and co-workers is also applicable to <jats:italic>n</jats:italic>-alkanes, with a minimum sample size of 15 µg C for dependable CSRA dates. We determined that the blank introduced during the analytical procedure has a mass of (4.1 ± 0.7) µg carrying a radiocarbon content of F<jats:sup>14</jats:sup>C = 0.25 ± 0.05. Applying the blank correction to a sediment sample from Lake Holzmaar (Germany) shows that all four isolated <jats:italic>n</jats:italic>-alkanes have similar <jats:sup>14</jats:sup>C ages. However, the bulk material of the sediment and branches found in the sediment core are younger than the CSRA dates. We conclude that the disparity between the actual age of analysed organic material and the age inferred from radiocarbon results, which can occur in sediment traps due to delayed deposition, is the reason for the CSRA age.","PeriodicalId":21020,"journal":{"name":"Radiocarbon","volume":null,"pages":null},"PeriodicalIF":8.3,"publicationDate":"2024-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140302598","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"MONITORING OF MODERN CARBON FRACTION IN DISPOSABLE PACKAGING","authors":"Komal Aziz Gill, Danuta J Michczyńska, Adam Michczyński, Natalia Piotrowska","doi":"10.1017/rdc.2024.35","DOIUrl":"https://doi.org/10.1017/rdc.2024.35","url":null,"abstract":"Radiocarbon (<jats:sup>14</jats:sup>C) methodology was used to investigate the presence of biocarbon in different bio-based disposable packaging products. Packaging waste contributes to a municipal solid waste, which is increasing environmental concerns and resulting in the enhancement of EU regulations that aim to reduce packaging waste. The <jats:sup>14</jats:sup>C amount in samples reflects how much of the biocarbon has been used. In this study, the concentration of <jats:sup>14</jats:sup>C was determined in commonly used types of disposable packaging, such as cups, plates, straws, cutlery, and baking paper. Samples were made of materials such as paper, wheat bran, sugarcane, and wood. The mean concentration of the <jats:sup>14</jats:sup>C isotope, measured by the accelerator mass spectrometry (AMS) technique, is greater than 100 pMC in all tested samples, indicating that the samples are modern. The relatively high <jats:sup>14</jats:sup>C concentration values in the waterproof layer of the sample indicate that bioplastic, rather than plastic, was used in its production. The highest <jats:sup>14</jats:sup>C isotope concentration values were measured for samples that used the oldest biomass (wood and paper), and the lowest for products from current crops (sugarcane and wheat bran), which is consistent with the trend of changes in <jats:sup>14</jats:sup>C concentration in the biosphere. The study also addresses the problem of heterogeneity and representativeness of subsamples.","PeriodicalId":21020,"journal":{"name":"Radiocarbon","volume":null,"pages":null},"PeriodicalIF":8.3,"publicationDate":"2024-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140302678","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"RADIOCARBON DATING OF ST. GEORGE’S ROTUNDA IN NITRIANSKA BLATNICA (SLOVAKIA): AN ARCHAEOLOGICAL COMMENT","authors":"Zbigniew Robak","doi":"10.1017/rdc.2024.33","DOIUrl":"https://doi.org/10.1017/rdc.2024.33","url":null,"abstract":"In 2021, a series of radiocarbon dates for St. George’s Rotunda in Nitrianska Blatnica (Slovakia) was published. The samples were acquired during restoration work. Based on the analysis, the authors dated the rotunda to the period of around AD 820–887, with 86% of the probability distribution lying in the period before AD 863. The chronology is based on the combined radiocarbon date 1191 ± 10 BP, which was obtained from four samples of wood fragments found in the oldest mortar layer. However, the date proposed by the authors raises concerns. The conclusions were based on a selection of samples and modeling of radiocarbon dates but put less emphasis on the results of many years of broad archaeological research on the local settlement agglomeration as well as extant historical and archaeological knowledge. The present re-analysis of the early medieval mortar and plaster samples and simple modeling corroborates the alternative hypothesis, providing us with the date 1115 ± 13 BP (cal AD 892–988 2σ). The resulting probability range is consistent with current archaeological and historical knowledge. Consequently, contrary to former conclusions, the construction of the rotunda should be dated to the period between the end of the 9th century and the end of the 10th century.","PeriodicalId":21020,"journal":{"name":"Radiocarbon","volume":null,"pages":null},"PeriodicalIF":8.3,"publicationDate":"2024-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140166123","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}