Radiocarbon最新文献_第3页

Estimation of groundwater residence time using radiocarbon and stable carbon isotope ratio in dissolved inorganic carbon and soil CO2 利用溶解无机碳和土壤二氧化碳中的放射性碳和稳定碳同位素比值估算地下水的停留时间

IF 8.3 3区地球科学

Radiocarbon Pub Date : 2024-04-29 DOI: 10.1017/rdc.2024.43

Rahul Kumar Agrawal, Ranjan Kumar Mohanty, Ajayeta Rathi, Shreya Mehta, M G Yadava, Sanjeev Kumar, Amzad H Laskar

{"title":"Estimation of groundwater residence time using radiocarbon and stable carbon isotope ratio in dissolved inorganic carbon and soil CO2","authors":"Rahul Kumar Agrawal, Ranjan Kumar Mohanty, Ajayeta Rathi, Shreya Mehta, M G Yadava, Sanjeev Kumar, Amzad H Laskar","doi":"10.1017/rdc.2024.43","DOIUrl":"https://doi.org/10.1017/rdc.2024.43","url":null,"abstract":"Estimation of residence time of groundwater, particularly in regions with inadequate surface waters are very important for formulating sustainable groundwater management policies. We developed a technique for extracting dissolved inorganic carbon (DIC) quantitatively from water for measuring its 14C contents and presented the analytical details here. We also measured stable carbon isotope ratio (δ13C) in soil CO2 and groundwater DIC to correct the groundwater 14C ages. In addition, 14C in soil CO2 were measured for making necessary correction in the initial activity of the recharging water. The corrected 14C contents in the groundwater samples were used to estimate their residence times employing Lumped Parameter Models (LPM), a set of mathematical models to account for the processes that take place during transport from the recharge to the sampling spots. We present a case study focused on the calculation of radiocarbon ages and residence times for a groundwater sample collected from the campus of Physical Research Laboratory in Ahmedabad, Gujarat, India. The study also includes estimations of groundwater residence times using previously measured 14C ages of groundwater samples from Gujarat, India. Various factors controlling the groundwater ages in the LPM and their applicability are discussed.","PeriodicalId":21020,"journal":{"name":"Radiocarbon","volume":"7 1","pages":""},"PeriodicalIF":8.3,"publicationDate":"2024-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140812471","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}

引用次数: 0

A HOMEMADE SEMIAUTOMATIC GRAPHITIZATION DEVICE FOR AMS 14C DATING AT NTUAMS LAB 自制半自动石墨化装置，用于在 Ntuams 实验室进行 ams 14c 测定

IF 8.3 3区地球科学

Radiocarbon Pub Date : 2024-04-29 DOI: 10.1017/rdc.2024.48

Tzu-Tsen Shen, Hong-Chun Li, Rick Qiu

{"title":"A HOMEMADE SEMIAUTOMATIC GRAPHITIZATION DEVICE FOR AMS 14C DATING AT NTUAMS LAB","authors":"Tzu-Tsen Shen, Hong-Chun Li, Rick Qiu","doi":"10.1017/rdc.2024.48","DOIUrl":"https://doi.org/10.1017/rdc.2024.48","url":null,"abstract":"A low-cost and computer-controlled graphitization system connected to an elemental analyzer (EA) has been designed and built at the NTUAMS Lab. This semiautomatic system equips 6-unit reactors for the graphitization of CO2 with H2 on the iron catalyst. The entire procedure takes about 7 hours for iron conditioning, sample combustion and loading, and graphitization. The system can produce good-quality graphite for samples containing 0.5–1.6 mg carbon mass, with the pressure yield of graphitization ranging from 57.7% to 87.1%. The average values of OXI and OXII agree well with the consensus value, but the result of ANU sucrose was observed to be slightly higher than the reported one. The background samples of anthracite over ten months yielded an average of 0.38±0.10 pMC (n=21) corresponding to a 14C age of 45 kyr BP. Intercomparison samples L and M of FIRI exhibit that the measured 14C ages are almost identical to the consensus values and have a small spread in these values. The system has been carrying out graphitization for total organic carbon (TOC) of peat samples, and providing a more efficient and convenient way for AMS 14C dating.","PeriodicalId":21020,"journal":{"name":"Radiocarbon","volume":"79 1","pages":""},"PeriodicalIF":8.3,"publicationDate":"2024-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140811487","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}

引用次数: 0

Radiocarbon dates from the archaeological site of Sakas, Bihar, India 印度比哈尔邦萨卡斯考古遗址的放射性碳年代测定

IF 8.3 3区地球科学

Radiocarbon Pub Date : 2024-04-29 DOI: 10.1017/rdc.2024.42

J Bates, V K Singh, R N Singh, Manisha Singh, Brij Mohan, Sudarshan Chakradhari, Abhay P Singh, Matthew Conte, Yongje Oh

引用次数: 0

SQUEAKY CLEAN CELLULOSE: COMPARING PRETREATMENT EFFECTIVENESS ON SINGLE TREE RINGS AND WOODEN LATHS 吱吱作响的洁净纤维素：比较单个树环和木板条的预处理效果

IF 8.3 3区地球科学

Radiocarbon Pub Date : 2024-04-04 DOI: 10.1017/rdc.2024.20

Wendy Hlengiwe Khumalo, Helene Løvstrand Svarva, Damaris Zurbach, Marie-Josée Nadeau

{"title":"SQUEAKY CLEAN CELLULOSE: COMPARING PRETREATMENT EFFECTIVENESS ON SINGLE TREE RINGS AND WOODEN LATHS","authors":"Wendy Hlengiwe Khumalo, Helene Løvstrand Svarva, Damaris Zurbach, Marie-Josée Nadeau","doi":"10.1017/rdc.2024.20","DOIUrl":"https://doi.org/10.1017/rdc.2024.20","url":null,"abstract":"Obtaining accurate radiocarbon (14C) results from wood samples requires the extraction of cellulose. In the past, this has been done using different combinations of methods including acidified bleaching, acid-base-acid, and strong bases. This often becomes a time-consuming task in most analyses, especially when single ring isotope chronologies are needed from wood samples. Using 14C and Fourier-transform infrared spectroscopy (FTIR), we tested four different pretreatment methods to determine their ability to produce high quality cellulose. We then adjusted the best methods to determine a method for pretreating wood laths of multiple rings. A sequence of base-acid-base-acid-bleach + strong base (BABAB+) and BABAB produced the most accurate results when compared to the Bomb20 Northern Hemisphere Zone 1 curve with an average difference in Δ14C of 1.3‰ and 5.8‰ respectively. These methods were adjusted to pretreat an entire wood lath and a comparison of the FTIR results suggest that our adjusted BABAB+ and BABAB produced high quality cellulose comparable to that of an individually pretreated ring. The possibility to pretreat wood lath samples has the potential to more than double the number of tree rings which can be pretreated in a week. This is a significant reduction in time when creating long tree ring chronologies.","PeriodicalId":21020,"journal":{"name":"Radiocarbon","volume":"249 1","pages":""},"PeriodicalIF":8.3,"publicationDate":"2024-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140559894","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}

引用次数: 0

EARLY HOLOCENE OXYGEN ISOTOPE CHRONOLOGIES (11,267–6420 CAL BP) FROM ICE WEDGE AT CHARA, TRANSBAIKALIA 横贝加尔湖畔查拉冰楔的全新世早期氧同位素年代学（11267-6420 卡平方公里

IF 8.3 3区地球科学

Radiocarbon Pub Date : 2024-04-04 DOI: 10.1017/rdc.2024.34

Yurij K Vasil’chuk, Alla C Vasil’chuk, Nadine A Budantseva, Alexander P Ginzburg, Igor V Tokarev, Jessica Yu Vasil’chuk

引用次数: 0

RADIOCARBON AGES OF PLANT REMAINS IN MASSIVE GROUND ICE AND UNDERLYING SEDIMENTS OF THE BARROW PERMAFROST TUNNEL, ALASKA 阿拉斯加巴罗永久冻土隧道块状地表冰和底层沉积物中植物遗骸的放射性碳年龄

IF 8.3 3区地球科学

Radiocarbon Pub Date : 2024-04-04 DOI: 10.1017/rdc.2024.25

Go Iwahana, Masao Uchida, Kazuho Horiuchi, Jody Deming, Hajo Eicken, Hiroshi Ohno, Kanako Mantoku, Toshiyuki Kobayashi, Kazuyuki Saito

{"title":"RADIOCARBON AGES OF PLANT REMAINS IN MASSIVE GROUND ICE AND UNDERLYING SEDIMENTS OF THE BARROW PERMAFROST TUNNEL, ALASKA","authors":"Go Iwahana, Masao Uchida, Kazuho Horiuchi, Jody Deming, Hajo Eicken, Hiroshi Ohno, Kanako Mantoku, Toshiyuki Kobayashi, Kazuyuki Saito","doi":"10.1017/rdc.2024.25","DOIUrl":"https://doi.org/10.1017/rdc.2024.25","url":null,"abstract":"Massive ground ice found in the Barrow Permafrost Tunnel at 3–7 m depths from the surface has been interpreted as an ice wedge and used to reconstruct early Holocene environmental changes. To better understand the development of this ground ice, we conducted radiocarbon dating for 34 samples of plant remains from the massive ground ice and underlying sediment layer. A significantly large gap in the measured radiocarbon ages (more than 24 ka) between massive ice and the underlying sediment layer throughout the tunnel profile suggested at least two possibilities. One is that the lower and older sediment layer had thrust upwards at the boundary between intruding ice wedge and adjacent sediment, and the growing ice had pushed the sediment sideways. Another is that erosional events had removed surface materials at about 12–36 ka BP (14–41 cal ka BP) before the overlaying sediment layer with massive ground ice developed. The overall distribution of radiocarbon ages from the massive ice supported the ice-wedge hypothesis as a formation mechanism, although our results showed several age inversions and large fluctuations. Dating of densely spaced samples revealed two ground-ice regions with similar ages around 11–11.5 and 10–10.5 ka BP divided by a relatively narrow region of transitional ages along the tunnel long-axis. This distribution may be explained by a possible misalignment between the sampling direction and the ice-wedge growth line or by intermittent ice growth with repeated cracking at more random locations than the classic ice-wedge growth model suggested.","PeriodicalId":21020,"journal":{"name":"Radiocarbon","volume":"10 22 1","pages":""},"PeriodicalIF":8.3,"publicationDate":"2024-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140560348","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}

引用次数: 0

NEW PERSPECTIVES ON OLD MATTERS: A REVIEW OF ARCHAEOLOGICAL AND CHRONOMETRIC DATA FROM ABRIGO DO SOL (MATO GROSSO, BRAZIL) 旧问题的新视角：巴西马托格罗索州阿布里戈-多索尔的考古和年代测定数据综述

IF 8.3 3区地球科学

Radiocarbon Pub Date : 2024-04-04 DOI: 10.1017/rdc.2024.30

Simon-Pierre Gilson, Lucas Bueno

引用次数: 0

ADDRESSING THE INTENSITY OF CHANGES IN THE PREHISTORIC POPULATION DYNAMICS: POPULATION GROWTH RATE ESTIMATIONS IN THE CENTRAL BALKANS EARLY NEOLITHIC 研究史前人口动态变化的强度：新石器时代早期中巴尔干地区人口增长率的估算

IF 8.3 3区地球科学

Radiocarbon Pub Date : 2024-04-04 DOI: 10.1017/rdc.2024.23

Tamara Blagojević, Marko Porčić, Sofija Stefanović

{"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":"25 1","pages":""},"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}

引用次数: 0

IMPROVING IONPLUS MICADAS PERFORMANCE WITH RECESSED GRAPHITE 利用嵌入式石墨提高 ionplus micadas 的性能

IF 8.3 3区地球科学

Radiocarbon Pub Date : 2024-04-04 DOI: 10.1017/rdc.2024.36

Taylor A B Broek, Mark L Roberts

{"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":"24 1","pages":""},"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}

引用次数: 0

DISCUSSION: PRESENTATION OF ATMOSPHERIC 14CO2 DATA 讨论：大气 14co2 数据的介绍

IF 8.3 3区地球科学

Radiocarbon Pub Date : 2024-03-27 DOI: 10.1017/rdc.2024.27

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

{"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":"Observations of radiocarbon (14C) in Earth’s atmosphere and other carbon reservoirs are important to quantify exchanges of CO2 between reservoirs. The amount of 14C is commonly reported in the so-called Delta notation, i.e., Δ14C, the decay- and fractionation-corrected departure of the ratio of 14C to total C from that ratio in an absolute international standard; this Delta notation permits direct comparison of 14C/C ratios in the several reservoirs. However, as Δ14C of atmospheric CO2, Δ14CO2 is based on the ratio of 14CO2 to total atmospheric CO2, its value can and does change not just because of change in the amount of atmospheric14CO2 but also because of change in the amount of total atmospheric CO2, complicating ascription of change in Δ14CO2 to change in one or the other quantity. Here we suggest that presentation of atmospheric 14CO2 amount as mole fraction relative to dry air (moles of 14CO2 per moles of dry air in Earth’s atmosphere), or as moles or molecules of 14CO2 in Earth’s atmosphere, all readily calculated from Δ14CO2 and the amount of atmospheric CO2 (with slight dependence on δ13CO2), complements presentation only as Δ14CO2, and can provide valuable insight into the evolving budget and distribution of atmospheric 14CO2.","PeriodicalId":21020,"journal":{"name":"Radiocarbon","volume":"86 1","pages":""},"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}

引用次数: 0