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Sample records for radiocarbon age calibration

  1. IntCal04 terrestrial radiocarbon age calibration, 0-26 cal kyr BP

    NARCIS (Netherlands)

    Reimer, Paula J.; Baillie, Mike G.L.; Bard, Edouard; Bayliss, Alex; Beck, J. Warren; Bertrand, Chanda J.H.; Blackwell, Paul G.; Buck, Caitlin E.; Burr, George S.; Cutler, Kirsten B.; Damon, Paul E.; Edwards, R. Lawrence; Fairbanks, Richard G.; Friedrich, Michael; Guilderson, Thomas P.; Hogg, Alan G.; Hughen, Konrad A.; Kromer, Bernd; McCormac, Gerry; Manning, Sturt; Bronk Ramsey, Christopher; Reimer, Ron W.; Remmele, Sabine; Southon, John R.; Stuiver, Minze; Talamo, Sahra; Taylor, F.W.; Plicht, Johannes van der; Weyhenmeyer, Constanze E.

    2004-01-01

    A new calibration curve for the conversion of radiocarbon ages to calibrated (cal) ages has been constructed and internationally ratified to replace IntCal98, which extended from 0–24 cal kyr BP (Before Present, 0 cal BP = AD 1950). The new calibration data set for terrestrial samples extends from

  2. Marine04 marine radiocarbon age calibration, 0-26 cal kyr BP

    NARCIS (Netherlands)

    Hughen, Konrad A.; Baillie, Mike G.L.; Bard, Edouard; Beck, J. Warren; Bertrand, Chanda J.H.; Blackwell, Paul G.; Buck, Caitlin E.; Burr, George S.; Cutler, Kirsten B.; Damon, Paul E.; Edwards, Richard L.; Fairbanks, Richard G.; Friedrich, Michael; Guilderson, Thomas P.; Kromer, Bernd; McCormac, Gerry; Manning, Sturt; Bronk Ramsey, Christopher; Reimer, Paula J.; Reimer, Ron W.; Remmele, Sabine; Southon, John R.; Stuiver, Minze; Talamo, Sahra; Taylor, F.W.; Plicht, Johannes van der; Weyhenmeyer, Constanze E.

    2004-01-01

    New radiocarbon calibration curves, IntCal04 and Marine04, have been constructed and internationally ratified to replace the terrestrial and marine components of IntCal98. The new calibration data sets extend an additional 2000 yr, from 0–26 cal kyr BP (Before Present, 0 cal BP = AD 1950), and

  3. INTCAL09 AND MARINE09 RADIOCARBON AGE CALIBRATION CURVES, 0-50,000 YEARS CAL BP

    NARCIS (Netherlands)

    Reimer, P. J.; Baillie, M. G. L.; Bard, E.; Bayliss, A.; Beck, J. W.; Blackwell, P. G.; Ramsey, C. Bronk; Buck, C. E.; Burr, G. S.; Edwards, R. L.; Friedrich, M.; Grootes, P. M.; Guilderson, T. P.; Hajdas, I.; Heaton, T. J.; Hogg, A. G.; Hughen, K. A.; Kaiser, K. F.; Kromer, B.; McCormac, F. G.; Manning, S. W.; Reimer, R. W.; Richards, D. A.; Southon, J. R.; Talamo, S.; Turney, C. S. M.; van der Plicht, J.; Weyhenmeye, C. E.; Weyhenmeyer, C.E.

    2009-01-01

    The IntCal04 and Marine04 radiocarbon calibration curves have been updated from 12 cal kBP (cal kBP is here defined as thousands of calibrated years before AD 1950), and extended to 50 cal kBP, utilizing newly available data sets that meet the IntCal Working Group criteria for pristine corals and

  4. Research on radiocarbon calibration records, focussing on new measurements from Lake Suigetsu, Japan

    OpenAIRE

    2011-01-01

    Radiocarbon calibration is a fundamental stage of the radiocarbon dating process if meaningful calendar ages are to be derived from samples’ radiocarbon determinations. However, the present limit of direct, non-reservoir-corrected, atmospheric radiocarbon calibration is 12,550 calibrated years before present (Reimer et al. 2009), leaving approximately three quarters of the radiocarbon timescale to be necessarily calibrated via less secure marine records.The sediment profile of Lake Suigetsu, ...

  5. IntCal13 and Marine13 Radiocarbon Age Calibration Curves 0–50,000 Years cal BP

    NARCIS (Netherlands)

    Reimer, Paula J.; Bard, Edouard; Bayliss, Alex; Beck, J. Warren; Blackwell, Paul G.; Bronk Ramsey, Christopher; Buck, Caitlin E.; Cheng, Hai; Edwards, R. Lawrence; Friedrich, Michael; Grootes, Pieter M.; Guilderson, Thomas P.; Haflidason, Haflidi; Hajdas, Irka; Hatté, Christine; Heaton, Timothy J.; Hoffmann, Dirk L.; Hogg, Alan G.; Hughen, Konrad A.; Kaiser, K. Felix; Kromer, Bernd; Manning, Sturt W.; Niu, Mu; Reimer, Ron W.; Richards, David A.; Scott, E. Marian; Southon, John R.; Staff, Richard A.; Turney, Christian S.M.; Plicht, Johannes van der; Reimer, Paula J.

    2013-01-01

    The IntCal09 and Marine09 radiocarbon calibration curves have been revised utilizing newly available and updated data sets from C-14 measurements on tree rings, plant macrofossils, speleothems, corals, and foraminifera. The calibration curves were derived from the data using the random walk model

  6. Radiocarbon calibration - past, present and future

    Energy Technology Data Exchange (ETDEWEB)

    Plicht, J. van der E-mail: plicht@phys.rug.nl

    2004-08-01

    Calibration of the Radiocarbon timescale is traditionally based on tree-rings dated by dendrochronology. At present, the tree-ring curve dates back to about 9900 BC. Beyond this limit, marine datasets extend the present calibration curve INTCAL98 to about 15 600 years ago. Since 1998, a wealth of AMS measurements became available, covering the complete {sup 14}C dating range. No calibration curve can presently be recommended for the older part of the dating range until discrepancies are resolved.

  7. Radiocarbon calibration - past, present and future

    International Nuclear Information System (INIS)

    Plicht, J. van der

    2004-01-01

    Calibration of the Radiocarbon timescale is traditionally based on tree-rings dated by dendrochronology. At present, the tree-ring curve dates back to about 9900 BC. Beyond this limit, marine datasets extend the present calibration curve INTCAL98 to about 15 600 years ago. Since 1998, a wealth of AMS measurements became available, covering the complete 14 C dating range. No calibration curve can presently be recommended for the older part of the dating range until discrepancies are resolved

  8. Observation models in radiocarbon calibration

    International Nuclear Information System (INIS)

    Jones, M.D.; Nicholls, G.K.

    2001-01-01

    The observation model underlying any calibration process dictates the precise mathematical details of the calibration calculations. Accordingly it is important that an appropriate observation model is used. Here this is illustrated with reference to the use of reservoir offsets where the standard calibration approach is based on a different model to that which the practitioners clearly believe is being applied. This sort of error can give rise to significantly erroneous calibration results. (author). 12 refs., 1 fig

  9. Tree rings and radiocarbon calibration

    International Nuclear Information System (INIS)

    Barbetti, M.

    1999-01-01

    Only a few kinds of trees in Australia and Southeast Asia are known to have growth rings that are both distinct and annual. Those that do are therefore extremely important to climatic and isotope studies. In western Tasmania, extensive work with Huon pine (Lagarostrobos franklinii) has shown that many living trees are more than 1,000 years old, and that their ring widths are sensitive to temperature, rainfall and cloud cover (Buckley et al. 1997). At the Stanley River there is a forest of living (and recently felled) trees which we have sampled and measured. There are also thousands of subfossil Huon pine logs, buried at depths less than 5 metres in an area of floodplain extending over a distance of more than a kilometre with a width of tens of metres. Some of these logs have been buried for 50,000 years or more, but most of them belong to the period between 15,000 years and the present. In previous expeditions in the 1980s and 1990s, we excavated and sampled about 350 logs (Barbetti et al. 1995; Nanson et al. 1995). By measuring the ring-width patterns, and matching them between logs and living trees, we have constructed a tree-ring dated chronology from 571 BC to AD 1992. We have also built a 4254-ring floating chronology (placed by radiocarbon at ca. 3580 to 7830 years ago), and an earlier 1268-ring chronology (ca. 7,580 to 8,850 years ago). There are many individuals, or pairs of logs which match and together span several centuries, at 9,000 years ago and beyond

  10. AMS radiocarbon dating of ancient Japanese documents of known age

    International Nuclear Information System (INIS)

    Oda, H.; Niu, E.; Nakamura, T.

    2003-01-01

    Radiocarbon ages of 17 ancient Japanese documents of known age and 3 unknown samples were measured by AMS. Radiocarbon dating on the known documents concluded that the Japanese paper is a suitable sample for radiocarbon dating because of small discrepancy between the calibrated radiocarbon age and the historical age due to the characteristics of Japanese paper. From the dating of the paper samples of unknown age, the wood-block prints, it was clarified that they had been produced between the 11th century and the first half of the 12th century as the historical information suggested. (author)

  11. Dating the time of birth: A radiocarbon calibration curve for human eye-lens crystallines

    Energy Technology Data Exchange (ETDEWEB)

    Kjeldsen, Henrik, E-mail: kjeldsen@phys.au.d [AMS 14C Dating Centre, Department of Physics and Astronomy, University of Aarhus, Aarhus (Denmark); Heinemeier, Jan [AMS 14C Dating Centre, Department of Physics and Astronomy, University of Aarhus, Aarhus (Denmark); Heegaard, Steffen [Eye Pathology Section, Department of Neuroscience and Pharmacology, University of Copenhagen, Copenhagen (Denmark); Jacobsen, Christina; Lynnerup, Niels [Department of Forensic Medicine, University of Copenhagen, Copenhagen (Denmark)

    2010-04-15

    Radiocarbon bomb-pulse dating has been used to measure the formation age of human eye-lens crystallines. Lens crystallines are special proteins in the eye-lens that consist of virtually inert tissue. The experimental data show that the radiocarbon ages to a large extent reflect the time of birth, in accordance with expectations. Moreover, it has been possible to develop an age model for the formation of the eye-lens crystallines. From this model a radiocarbon calibration curve for lens crystallines has been calculated. As a consequence, the time of birth of humans can be determined with an accuracy of a few years by radiocarbon dating.

  12. Dating the time of birth: A radiocarbon calibration curve for human eye-lens crystallines

    International Nuclear Information System (INIS)

    Kjeldsen, Henrik; Heinemeier, Jan; Heegaard, Steffen; Jacobsen, Christina; Lynnerup, Niels

    2010-01-01

    Radiocarbon bomb-pulse dating has been used to measure the formation age of human eye-lens crystallines. Lens crystallines are special proteins in the eye-lens that consist of virtually inert tissue. The experimental data show that the radiocarbon ages to a large extent reflect the time of birth, in accordance with expectations. Moreover, it has been possible to develop an age model for the formation of the eye-lens crystallines. From this model a radiocarbon calibration curve for lens crystallines has been calculated. As a consequence, the time of birth of humans can be determined with an accuracy of a few years by radiocarbon dating.

  13. A re-analysis of the Lake Suigetsu terrestrial radiocarbon calibration dataset

    International Nuclear Information System (INIS)

    Staff, R.A.; Bronk Ramsey, C.; Nakagawa, T.

    2010-01-01

    Lake Suigetsu, Honshu Island, Japan provides an ideal sedimentary sequence from which to derive a wholly terrestrial radiocarbon calibration curve back to the limits of radiocarbon detection (circa 60 ka bp). The presence of well-defined, annually-deposited laminae (varves) throughout the entirety of this period provides an independent, high resolution chronometer against which radiocarbon measurements of plant macrofossils from the sediment column can be directly related. However, data from the initial Lake Suigetsu project were found to diverge significantly from alternative, marine-based calibration datasets released around the same time (e.g. ). The main source of this divergence is thought to be the result of inaccuracies in the absolute age profile of the Suigetsu project, caused by both varve counting uncertainties and gaps in the sediment column of unknown duration between successively-drilled core sections. Here, a re-analysis of the previously-published Lake Suigetsu data is conducted. The most recent developments in Bayesian statistical modelling techniques (OxCal v4.1; ) are implemented to fit the Suigetsu data to the latest radiocarbon calibration datasets and thereby estimate the duration of the inter-core section gaps in the Suigetsu data. In this way, the absolute age of the Lake Suigetsu sediment profile is more accurately defined, providing significant information for both radiocarbon calibration and palaeoenvironmental reconstruction purposes.

  14. SELECTION AND TREATMENT OF DATA FOR RADIOCARBON CALIBRATION : AN UPDATE TO THE INTERNATIONAL CALIBRATION (INTCAL) CRITERIA

    NARCIS (Netherlands)

    Reimer, Paula J.; Bard, Edouard; Bayliss, Alex; Beck, J. Warren; Blackwell, Paul G.; Ramsey, Christopher Bronk; Brown, David M.; Buck, Caitlin E.; Edwards, R. Lawrence; Friedrich, Michael; Grootes, Pieter M.; Guilderson, Thomas P.; Haflidason, Haflidi; Hajdas, Irka; Hatte, Christine; Heaton, Timothy J.; Hogg, Alan G.; Hughen, Konrad A.; Kaiser, K. Felix; Kromer, Bernd; Manning, Sturt W.; Reimer, Ron W.; Richards, David A.; Scott, E. Marian; Southon, John R.; Turney, Christian S. M.; van der Plicht, Johannes

    2013-01-01

    High-quality data from appropriate archives are needed for the continuing improvement of radiocarbon calibration curves. We discuss here the basic assumptions behind C-14 dating that necessitate calibration and the relative strengths and weaknesses of archives from which calibration data are

  15. Atmospheric radiocarbon calibration beyond 11,900 cal BP from Lake Suigetsu laminated sediments

    NARCIS (Netherlands)

    Kitagawa, H; van der Plicht, J

    2000-01-01

    This paper presents an updated atmospheric radiocarbon calibration from annually laminated (varved) sediments from Lake Suigetsu (LS). central Japan. As presented earlier, the LS varved sediments can be used to extend the radiocarbon time scale beyond the tree ring calibration range that reaches

  16. Dating the time of birth: A radiocarbon calibration curve for human eye-lens crystallines

    DEFF Research Database (Denmark)

    Kjeldsen, Henrik; Heinemeier, Jan; Heegaard, Steffen

    2010-01-01

    Radiocarbon bomb-pulse dating has been used to measure the formation age of human eye-lens crystallines. Lens crystallines are special proteins in the eye-lens that consist of virtually inert tissue. The experimental data show that the radiocarbon ages to a large extent reflect the time of birth...

  17. Atmospheric radiocarbon calibration to 45,000 yr BP: Late glacial fluctuations and cosmogenic isotope production

    NARCIS (Netherlands)

    Kitagawa, H.; van der Plicht, J.

    1998-01-01

    More than 250 carbon-14 accelerator mass spectrometry dates of terrestrial macrofossils from annually laminated sediments from Lake Suigetsu (Japan) provide a first atmospheric calibration for almost the total range of the radiocarbon method (45,000 years before the present), The results confirm the

  18. Old ages of two historical Romanian trees assessed by AMS radiocarbon dating

    International Nuclear Information System (INIS)

    Patrut, Adrian; Reden, Karl F. von; Lowy, Daniel A.; Patrut, Roxana T.; Lucian Vaida, D.; Margineanu, Dragos

    2013-01-01

    Two large Romanian poplars are considered to be associated with significant historical events of the past. In order to verify these claims, wood samples collected from the broken trunks of the two poplars were radiocarbon dated by AMS. The oldest radiocarbon dates were found to be 275 ± 20 bp for the black poplar of Mocod and 316 ± 22 bp for the gray poplar of Rafaila. These values correspond to calibrated ages of 365 ± 10 and 465 ± 25 years, respectively. The dating results indicate old ages for the two trees, i.e., 455 years for the Mocod poplar and 560 years for the Rafaila poplar. Such age values validate historical information on the two large Romanian trees.

  19. Old ages of two historical Romanian trees assessed by AMS radiocarbon dating

    Energy Technology Data Exchange (ETDEWEB)

    Patrut, Adrian, E-mail: apatrut@gmail.com [Babes-Bolyai University, Department of Chemistry, Arany Janos 11, 400028 Cluj-Napoca (Romania); Reden, Karl F. von [Woods Hole Oceanographic Institution, Department of Geology and Geophysics, NOSAMS Facility, 360 Woods Hole Rd., Mailstop 8, Woods Hole, MA 02543 (United States); Lowy, Daniel A. [FlexEl, LLC, 387 Technology Drive, College Park, MD 20742 (United States); Patrut, Roxana T. [Babes-Bolyai University, Department of Biology and Geology, Gh. Bilascu 44, 400015 Cluj-Napoca (Romania); Lucian Vaida, D. [Museum of Border Regiment Nasaud, Granicerilor 19, 425200 Nasaud (Romania); Margineanu, Dragos [Babes-Bolyai University, Department of Chemistry, Arany Janos 11, 400028 Cluj-Napoca (Romania)

    2013-01-15

    Two large Romanian poplars are considered to be associated with significant historical events of the past. In order to verify these claims, wood samples collected from the broken trunks of the two poplars were radiocarbon dated by AMS. The oldest radiocarbon dates were found to be 275 {+-} 20 bp for the black poplar of Mocod and 316 {+-} 22 bp for the gray poplar of Rafaila. These values correspond to calibrated ages of 365 {+-} 10 and 465 {+-} 25 years, respectively. The dating results indicate old ages for the two trees, i.e., 455 years for the Mocod poplar and 560 years for the Rafaila poplar. Such age values validate historical information on the two large Romanian trees.

  20. Radiocarbon ages of Sorori ancient rice of Korea

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kyeong Ja, E-mail: kjkim@kigam.re.kr [Korea Institute of Geoscience and Mineral Resources, Daejeon (Korea, Republic of); Lee, Yung-Jo; Woo, Jong-Yoon [Institute of Korean Prehistory, Cheongju (Korea, Republic of); Jull, A.J. Timothy [NSF Arizona AMS Laboratory, University of Arizona, Tucson, AZ 85721 (United States)

    2013-01-15

    Samples of Sorori ancient rice were excavated in 1998 from the Sorori Paleolithic site located at Sorori, Oksan-myeon, Cheong-won County in Chungcheongbuk-do, Korea. We have made new radiocarbon measurements for Sorori samples in 2009 at the NSF Arizona AMS Laboratory. Both ancient rice samples and surrounded peat from the Sorori site were dated. The AMS results confirmed that the ages of the rice and peat soil were 12,520 {+-} 150 and 12,552 {+-} 90 BP, respectively. These radiocarbon ages are consistent with the previously published data of quasi rice measured at Seoul National University and confirm that the Sorori rice is the oldest ancient rice currently reported.

  1. Age-depth modelling with radiocarbon

    International Nuclear Information System (INIS)

    Howarth, J.D.

    2017-01-01

    Chronology is a critical component of any study into the Quaternary because the information about climate and environmental change preserved in sedimentary deposits can only be placed in a useful context when it is associated with a robust chronological framework. This overview will introduce you to the key concepts in age depth modelling.

  2. Surface Ocean Radiocarbon Reservoir Ages From Land-Sea Tephra Correlation Constrains Deglacial Chronology and Ocean Circulation in the Southeast Bering Sea

    Science.gov (United States)

    Cook, M. S.; Miller, R.; White-Nockleby, C.; Chapman, A.; Mix, A. C.

    2017-12-01

    Radiocarbon estimates of the past ocean are valuable because unlike passive tracers, radiocarbon has the potential to trace both the distribution and rate of transport of water masses. Most studies using paired radiocarbon measurements on planktonic and benthic foraminifera assume that the surface reservoir age was constant at the preindustrial value, which if incorrect, can strongly bias radiocarbon reconstructions. The subarctic Pacific is ringed by volcanic arcs, and there is great potential to use tephrochronology as a stratigraphic tool in sediments from the last glacial and deglaciation, and assign calendar ages to the marine sediment without relying on calibrated planktonic radiocarbon ages. In this study, we use major and trace element analysis of volcanic glass to match tephras between radiocarbon-dated lake cores from Sanak Island in the eastern Aleutians to marine cores from Umnak Plateau in the southeast Bering Sea. There are numerous thin tephras preserved in laminated sediments from the Bolling-Allerod and early Holocene in marine cores from depths (1000-1500 m) within the modern oxygen minimum zone. We find that trace elements are crucial in distinguishing tephras from individual eruptions. Our preliminary radiocarbon measurements suggest that the benthic-atmosphere radiocarbon differences and marine surface reservoir ages in the Bolling-Allerod are similar to pre-industrial values, supporting previously published radiocarbon reconstructions from the region.

  3. Radiocarbon dating of ancient Japanese documents

    International Nuclear Information System (INIS)

    Oda, H.

    2001-01-01

    History is a reconstruction of past human activity, evidence of which is remained in the form of documents or relics. For the reconstruction of historic period, the radiocarbon dating of ancient documents provides important information. Although radiocarbon age is converted into calendar age with the calibration curve, the calibrated radiocarbon age is still different from the historical age when the document was written. The difference is known as 'old wood effect' for wooden cultural property. The discrepancy becomes more serious problem for recent sample which requires more accurate age determination. Using Tandetron accelerator mass spectrometer at Nagoya University, we have measured radiocarbon ages of Japanese ancient documents, sutras and printed books written dates of which are clarified from the paleographic standpoint. The purpose is to clarify the relation between calibrated radiocarbon age and historical age of ancient Japanese document by AMS radiocarbon dating. This paper reports 23 radiocarbon ages of ancient Japanese documents, sutras and printed books. The calibrated radiocarbon ages are in good agreement with the corresponding historical ages. It was shown by radiocarbon dating of the ancient documents that Japanese paper has little gap by 'old wood effect'; accordingly, ancient Japanese paper is a suitable sample for radiocarbon dating of recent historic period. (author)

  4. Radiocarbon ages of pedogenic calcic nodules formed within vertisols, Coimbatore region, Tamil Nadu, India

    International Nuclear Information System (INIS)

    Achyuthan, H.; Flora, O.; Braida, M.; Stenni, B.; Shankar, N.

    2009-05-01

    In this paper we discuss the limitation of radiocarbon dates on the pedogenic calcic nodules formed in situ within the vertisols in the upland region of Coimbatore, Tamil Nadu. The radiocarbon ages were obtained using low level scintillation counters and the ages range from ∼24 Ka to ∼31 Ka. The ages correlate well with the marine isotope stage of Late MIS3. Since the calcic nodules are pedogenised and formed in a terrestrial open system we express caution in the interpretation of the radiocarbon ages obtained on pedogenic carbonate nodules. The radiocarbon dates represent maximum ages and hence the ages measured should only be considered as age estimates and not absolute geologic ages. Multiple sub-mm size subsamples could provide more reliable estimates of soil chronology. (author)

  5. Radiocarbon Based Ages and Growth Rates: Hawaiian Deep Sea Corals

    Energy Technology Data Exchange (ETDEWEB)

    Roark, E B; Guilderson, T P; Dunbar, R B; Ingram, B L

    2006-01-13

    The radial growth rates and ages of three different groups of Hawaiian deep-sea 'corals' were determined using radiocarbon measurements. Specimens of Corallium secundum, Gerardia sp., and Leiopathes glaberrima, were collected from 450 {+-} 40 m at the Makapuu deep-sea coral bed using a submersible (PISCES V). Specimens of Antipathes dichotoma were collected at 50 m off Lahaina, Maui. The primary source of carbon to the calcitic C. secundum skeleton is in situ dissolved inorganic carbon (DIC). Using bomb {sup 14}C time markers we calculate radial growth rates of {approx} 170 {micro}m y{sup -1} and ages of 68-75 years on specimens as tall as 28 cm of C. secundum. Gerardia sp., A. dichotoma, and L. glaberrima have proteinaceous skeletons and labile particulate organic carbon (POC) is their primary source of architectural carbon. Using {sup 14}C we calculate a radial growth rate of 15 {micro}m y{sup -1} and an age of 807 {+-} 30 years for a live collected Gerardia sp., showing that these organisms are extremely long lived. Inner and outer {sup 14}C measurements on four sub-fossil Gerardia spp. samples produce similar growth rate estimates (range 14-45 {micro}m y{sup -1}) and ages (range 450-2742 years) as observed for the live collected sample. Similarly, with a growth rate of < 10 {micro}m y{sup -1} and an age of {approx}2377 years, L. glaberrima at the Makapuu coral bed, is also extremely long lived. In contrast, the shallow-collected A. dichotoma samples yield growth rates ranging from 130 to 1,140 {micro}m y{sup -1}. These results show that Hawaiian deep-sea corals grow more slowly and are older than previously thought.

  6. Radiocarbon calibration curves indicate location dependent differences in the C-14 content of wood

    International Nuclear Information System (INIS)

    McCormac, F.G.; Baillie, M.G.L.

    1997-01-01

    Full text: The C-14 chronologies currently used as calibration curves combine results from wood that grew in the western United States, the British Isles and Germany. Recent corrections to the published measurements indicate that data from these long chronologies are no longer entirely consistent, implying either the existence of interlaboratory biases, or C-14 variations in the wood from different species and/or regions. It has long been accepted that wood from the Southern Hemisphere gives radiocarbon dates that are approximately 40 years older than contemporaneous Northern Hemisphere wood. The reasons suggested for the difference are typically that the larger expanse of ocean and the slightly higher average wind speeds result in enhanced CO 2 exchange with the mixed layer of the ocean. measurements presented in a companion paper (Hogg et al) explore the difference between the hemispheres, by re-measurement of a section of the Northern Hemisphere calibration dataset and wood from New Zealand. Only by making careful replicated comparisons of the C-14 content of wood from different regions, over long time scales, can we verify the presence or absence of temporal variations. In this paper we will discuss the Northern Hemisphere calibration dataset and show the importance of experimental design in determining if small, temporally varying offsets exist between regional tree-ring chronologies

  7. Examining sources of bias in radiocarbon ages of New Zealand Kiore

    Energy Technology Data Exchange (ETDEWEB)

    Beavan, N.R.; Sparks, R.J. [Institute of Geological and Nuclear Sciences, (New Zealand). Rafter Radiocarbon Laboratory

    1997-12-31

    Recent AMS dates for the Pacific rat (Rattus exulans / Kiore) from natural and archaeological sites are significantly older than the generally accepted time for human arrival in New Zealand. Because Rattus exulans is recognized as a human commensal for Polynesian colonization in Oceania, radiocarbon ages for Kiore could be used as an indicator of earliest human contact with New Zealand. A strictly chronological interpretation of the radiocarbon ages assembled, though, raises serious questions about this arrival time. Therefore, factors that could affect the age determinations were also examined. A research programme in progress at the Rafter Radiocarbon Laboratory aims to identify the range and influence of natural bias and variance in radiocarbon ages in kiore bone samples. It was found that the main factors that could bias these ages were the incomplete removal of contaminants by the current bone preparation methods, and dietary carbon reservoir effects. Preliminary results of the various analytical techniques employed are presented.

  8. Millennial-scale variability in the local radiocarbon reservoir age of south Florida during the Holocene

    Science.gov (United States)

    Toth, Lauren T.; Cheng, Hai; Edwards, R. Lawrence; Ashe, Erica; Richey, Julie N.

    2017-01-01

    -scale changes in western Atlantic circulation associated with an increase in the supply of equatorial South Atlantic water to the Caribbean and shifts in the character of South Atlantic waters resulting from variation in the intensity of upwelling off the southwest coast of Africa. Because accurate estimates of ΔR are critical to precise calibrations of radiocarbon dates from marine samples, we also developed models of nearshore and open-ocean ΔR versus conventional 14C ages that can be used for regional radiocarbon calibrations for the Holocene. Our study provides new insights into the patterns and drivers of oceanographic and hydrologic variability in the Straits of Florida and highlights the value of the paleoceanographic records from south Florida to our understanding of Holocene changes in climate and ocean circulation throughout the Atlantic.

  9. Radiocarbon age and diagenesis of oolitic sediments from the Persian Gulf

    International Nuclear Information System (INIS)

    Silar, J.

    1980-01-01

    Radiocarbon measurements of different parts of ooids of Pleistocene and Holocene oolitic sediments from the Persian Gulf on the coast of Kuwait indicated that atmospheric carbon dioxide had been involved in the recrystallization of aragonite and in the diagenesis of the oolitic sediments. The radiocarbon activity of different layers of sediments generally corresponds to their stratigraphic sequence. The radiocarbon ages of several earlier layers, however, seem to be reduced due to recrystallization and diagenesis. The radiocarbon ages of well-preserved shells of mollusks of the fossiliferous horizon are lower than their alleged Pleistocene geological age. The rate of emergence of the shore between one and several mm.yr -1 was established which corresponds to that recorded in the mouth of the Persian Gulf and in Qatar. (author)

  10. An Improved Method for Estimating Water-Mass Ventilation Age from Radiocarbon Measurements

    Science.gov (United States)

    Devries, T. J.; Primeau, F. W.

    2009-12-01

    Paleoceanographic data can help to constrain the state of the past ocean circulation. One critical quantity that can be constrained by paleoceanographic data is the ventilation age, which measures the vigor of the ocean circulation. Paleoceanographers often use radiocarbon data to estimate paleo-ventilation ages by calculating either the benthic-planktonic (B-P) age difference, or the so-called “projection” age. However, recent studies have shown that neither of these calculations yield correct estimates of ventilation age, due to fluctuations in atmospheric radiocarbon content and mixing processes in the ocean. Here we propose a new method for more accurately inferring paleo-ventilation ages based on radiocarbon data. Our method makes use of a model that uses parameterized transfer functions to simulate the effects of circulation and mixing in the ocean. We show how this model can be used in a Bayesian framework to infer a ventilation age from a paired radiocarbon- and calendar-age measurement. The Bayesian framework allows us to quantify the uncertainty in the inferred ventilation age due to uncertainty in the data, as well as uncertainty in the assumptions made in the model itself. We applied this framework to previously published radiocarbon data from the deep North Pacific spanning 10 000 to 20 000 years before present. Ventilation ages inferred using our method are significantly different from the B-P ages or projection ages calculated from the same data. Furthermore, our analysis suggests that the uncertainty of the ventilation ages is on the order of 400-500 years, and that the main sources of uncertainty are uncertainty in the age of surface source waters and in the true calendar age of the radiocarbon data. Our results do not show a clear change in the ventilation age of deep North Pacific waters during the last deglaciation.

  11. Constraint on radiocarbon age correction in Lake Biwa environment from the middle to late Holocene

    Energy Technology Data Exchange (ETDEWEB)

    Miyata, Y., E-mail: miyata@nendai.nagoya-u.ac.jp [Center for Chronological Research, Nagoya University, Nagoya 464-8602 (Japan); National Museum of Japanese History, Sakura 285-8502 (Japan); Minami, M. [Center for Chronological Research, Nagoya University, Nagoya 464-8602 (Japan); Onbe, S. [National Museum of Japanese History, Sakura 285-8502 (Japan); Archaeological Heritage Management Office, Tokushima University, Tokushima 770-8503 (Japan); Sakamoto, M. [National Museum of Japanese History, Sakura 285-8502 (Japan); Nakamura, T. [Center for Chronological Research, Nagoya University, Nagoya 464-8602 (Japan); Imamura, M. [National Museum of Japanese History, Sakura 285-8502 (Japan)

    2013-01-15

    Using data from previous studies and newly collected data, we compared the measured radiocarbon ages of molluscan shells, common reed (Phragmites australis) and pine needles (Pinus thunbergii) collected in 1966, 1970, 1990 and 2008 at Lake Biwa in Japan, and of archaeological samples, to examine radiocarbon reservoir effects at Lake Biwa. We also tested for differences in the radiocarbon reservoir effect between species and locations in the lake. The effects of nuclear bomb tests conducted in the 1950s and 1960s are clear, the offset between atmospheric {sup 14}C and the Lake Biwa freshwater {sup 14}C is larger for this period because the atmospheric {sup 14}C is so high. The semiclosed Lake Biwa system is in dynamic equilibrium with the atmosphere, resulting in the {sup 14}C content of the water following the changes in atmospheric {sup 14}C caused by nuclear testing. The shells collected after 1990 had radiocarbon ages that were 330-450 {sup 14}C years older than those of the coeval atmosphere. The apparent differences in radiocarbon age (about 300 {sup 14}C years) between shell fossils and wood samples excavated from the same layer of the submerged Awazu shell midden at Lake Biwa suggest that the radiocarbon reservoir effect also existed in the middle Holocene (the Middle Jomon period, about 5000 years ago). Because the present-day average residence time of Lake Biwa water is 3-6 years, its direct influence on the radiocarbon reservoir effect is small, which suggests that old carbon has been supplied into Lake Biwa.

  12. AMS radiocarbon dating of ancient Japanese sutras

    CERN Document Server

    Oda, H; Nakamura, T; Fujita, K

    2000-01-01

    Radiocarbon ages of ancient Japanese sutras whose historical ages were known paleographically were measured by means of accelerator mass spectrometry (AMS). Calibrated radiocarbon ages of five samples were consistent with the corresponding historical ages; the 'old wood effect' is negligible for ancient Japanese sutras. Japanese paper has been made from fresh branches grown within a few years and the interval from trimming off the branches to writing sutra on the paper is within one year. The good agreement between the calibrated radiocarbon ages and the historical ages is supported by such characteristics of Japanese paper. It is indicated in this study that Japanese sutra is a suitable sample for radiocarbon dating in the historic period because of little gap by 'old wood effect'.

  13. AMS radiocarbon dating of ancient Japanese sutras

    International Nuclear Information System (INIS)

    Oda, Hirotaka; Yoshizawa, Yasukazu; Nakamura, Toshio; Fujita, Keiko

    2000-01-01

    Radiocarbon ages of ancient Japanese sutras whose historical ages were known paleographically were measured by means of accelerator mass spectrometry (AMS). Calibrated radiocarbon ages of five samples were consistent with the corresponding historical ages; the 'old wood effect' is negligible for ancient Japanese sutras. Japanese paper has been made from fresh branches grown within a few years and the interval from trimming off the branches to writing sutra on the paper is within one year. The good agreement between the calibrated radiocarbon ages and the historical ages is supported by such characteristics of Japanese paper. It is indicated in this study that Japanese sutra is a suitable sample for radiocarbon dating in the historic period because of little gap by 'old wood effect'

  14. Age estimation in forensic sciences: Application of combined aspartic acid racemization and radiocarbon analysis

    Energy Technology Data Exchange (ETDEWEB)

    Alkass, K; Buchholz, B A; Ohtani, S; Yamamoto, T; Druid, H; Spalding, S L

    2009-11-02

    Age determination of unknown human bodies is important in the setting of a crime investigation or a mass disaster, since the age at death, birth date and year of death, as well as gender, can guide investigators to the correct identity among a large number of possible matches. Traditional morphological methods used by anthropologists to determine age are often imprecise, whereas chemical analysis of tooth dentin, such as aspartic acid racemization has shown reproducible and more precise results. In this paper we analyze teeth from Swedish individuals using both aspartic acid racemization and radiocarbon methodologies. The rationale behind using radiocarbon analysis is that above-ground testing of nuclear weapons during the cold war (1955-1963) caused an extreme increase in global levels of carbon-14 ({sup 14}C) which have been carefully recorded over time. Forty-four teeth from 41 individuals were analyzed using aspartic acid racemization analysis of tooth crown dentin or radiocarbon analysis of enamel and ten of these were split and subjected to both radiocarbon and racemization analysis. Combined analysis showed that the two methods correlated well (R2=0.66, p < 0.05). Radiocarbon analysis showed an excellent precision with an overall absolute error of 0.6 {+-} 04 years. Aspartic acid racemization also showed a good precision with an overall absolute error of 5.4 {+-} 4.2 years. Whereas radiocarbon analysis gives an estimated year of birth, racemization analysis indicates the chronological age of the individual at the time of death. We show how these methods in combination can also assist in the estimation of date of death of an unidentified victim. This strategy can be of significant assistance in forensic casework involving dead victim identification.

  15. Application of the bomb radiocarbon chronometer to the validation of redfish Centroberyx affinis age

    International Nuclear Information System (INIS)

    Kalish, J.M.

    1995-01-01

    Validation of methods used to estimate fish age is a critical element of the fish stock assessment process. Despite the importance of validation, few procedures are available that provide unbiased estimates of true fish age and those methods that are available are seldom used. The majority of these methods are unlikely to provide an indication of the true age of individual fish, data that are best suited to the validation process. Accelerator mass spectrometry analyses of radiocarbon in selected regions of Centroberyx affinis otoliths were used to validate the age estimation method for this species. Radiocarbon data from the otoliths of C. affinis with presumed birth dates between 1955 and 1985 described the increase in ocean radiocarbon attributable to the atmospheric detonation of nuclear weapons in the 1950s and 1960s. The results confirm the longevity of C. affinis and demonstrate the effectiveness of the bomb radiocarbon chronometer for the validation of age-estimation methods. (author). 31 refs., 2 tabs., 1 fig

  16. Revised age of deglaciation of Lake Emma based on new radiocarbon and macrofossil analyses

    Science.gov (United States)

    Elias, S.A.; Carrara, P.E.; Toolin, L.J.; Jull, A.J.T.

    1991-01-01

    Previous radiocarbon ages of detrital moss fragments in basal organic sediments of Lake Emma indicated that extensive deglaciation of the San Juan Mountains occurred prior to 14,900 yr B.P. (Carrara et al., 1984). Paleoecological analyses of insect and plant macrofossils from these basal sediments cast doubt on the reliability of the radiocarbon ages. Subsequent accelerator radiocarbon dates of insect fossils and wood fragments indicate an early Holocene age, rather than a late Pleistocene age, for the basal sediments of Lake Emma. These new radiocarbon ages suggest that by at least 10,000 yr B.P. deglaciation of the San Juan Mountains was complete. The insect and plant macrofossils from the basal organic sediments indicate a higher-than-present treeline during the early Holocene. The insect assemblages consisted of about 30% bark beetles, which contrasts markedly with the composition of insects from modern lake sediments and modern specimens collected in the Lake Emma cirque, in which bark beetles comprise only about 3% of the assemblages. In addition, in the fossil assemblages there were a number of flightless insect species (not subject to upslope transport by wind) indicative of coniferous forest environments. These insects were likewise absent in the modern assemblage. ?? 1991.

  17. Atmospheric radiocarbon calibration to 45,000 yr B.P.: late glacial fluctuations and cosmogenic isotope production

    Science.gov (United States)

    Kitagawa; van der Plicht J

    1998-02-20

    More than 250 carbon-14 accelerator mass spectrometry dates of terrestrial macrofossils from annually laminated sediments from Lake Suigetsu (Japan) provide a first atmospheric calibration for almost the total range of the radiocarbon method (45,000 years before the present). The results confirm the (recently revised) floating German pine chronology and are consistent with data from European and marine varved sediments, and combined uranium-thorium and carbon-14 dating of corals up to the Last Glacial Maximum. The data during the Glacial show large fluctuations in the atmospheric carbon-14 content, related to changes in global environment and in cosmogenic isotope production.

  18. Accelerator mass spectrometry radiocarbon ages of amino acid extracts from Californian palaeoindian skeletons

    International Nuclear Information System (INIS)

    Bada, J.L.; Gillespie, R.; Gowlett, J.A.J.; Hedges, R.E.M.

    1984-01-01

    The authors have used accelerator mass spectrometry to determine the radiocarbon ages of the amino acid extracts used in the original racemization studies of skeletal remains found in California. The studies indicate that some of the controversial Californian skeletons, which had been assigned to the Upper Pleistocene, are in fact Holocene. (author)

  19. Age estimation in forensic sciences: application of combined aspartic acid racemization and radiocarbon analysis.

    Science.gov (United States)

    Alkass, Kanar; Buchholz, Bruce A; Ohtani, Susumu; Yamamoto, Toshiharu; Druid, Henrik; Spalding, Kirsty L

    2010-05-01

    Age determination of unknown human bodies is important in the setting of a crime investigation or a mass disaster because the age at death, birth date, and year of death as well as gender can guide investigators to the correct identity among a large number of possible matches. Traditional morphological methods used by anthropologists to determine age are often imprecise, whereas chemical analysis of tooth dentin, such as aspartic acid racemization, has shown reproducible and more precise results. In this study, we analyzed teeth from Swedish individuals using both aspartic acid racemization and radiocarbon methodologies. The rationale behind using radiocarbon analysis is that aboveground testing of nuclear weapons during the cold war (1955-1963) caused an extreme increase in global levels of carbon-14 ((14)C), which has been carefully recorded over time. Forty-four teeth from 41 individuals were analyzed using aspartic acid racemization analysis of tooth crown dentin or radiocarbon analysis of enamel, and 10 of these were split and subjected to both radiocarbon and racemization analysis. Combined analysis showed that the two methods correlated well (R(2) = 0.66, p Aspartic acid racemization also showed a good precision with an overall absolute error of 5.4 +/- 4.2 years. Whereas radiocarbon analysis gives an estimated year of birth, racemization analysis indicates the chronological age of the individual at the time of death. We show how these methods in combination can also assist in the estimation of date of death of an unidentified victim. This strategy can be of significant assistance in forensic casework involving dead victim identification.

  20. Inversions of radiocarbon age of humus in the profile of modern soils

    International Nuclear Information System (INIS)

    Chichagova, O.A.; Cherkinskij, A.E.; Tolchel'nikov, Yu.S.

    1984-01-01

    Exogenous and endogenous inversions of humus radiocarbon age in the orofile of modern soils are studied. The reasons for exogenous and endogenous invesrsions are enumerated and examples are given. Thus, the exogenous inversion of the chernozem by the underbush (Kursk region) is explained by a high activity of soricids. The age determination of the disturbed profile in the depth of 49-59 cm turns out to be rejuvanated - 1820+-70 years and that of the non-disturbed one - 4050+-60 years. A conclusion is made on the necessity of a detailed analysis of each soil profile, specific features of its genesis as well as a possibility of postgenetic transformations, especially Anthropogenic ones. In this case an interpretation of the radiocarbon data will be more accurate

  1. On the work of the International Committee on Calibration of the Radiocarbon Dating Time Scale

    International Nuclear Information System (INIS)

    Olsson, I.U.

    1982-01-01

    Over one thousand reliable measurements of the 14 C content of tree rings have now been published by different scientists, allowing construction of a curve or band for calibration purposes. Since 1969 we have agreed on the general trend of the variations, although the interpretations of the measurements naturally diverge, causing confusion. It is obvious that different calibration principles must be used depending on the type of material. An international committee is working on the construction of a universal curve or band which is intended to be the basis for all calibration procedures. (author)

  2. Radiocarbon ages of upper quaternary deposit in central Nepal and their geomorphological significance

    International Nuclear Information System (INIS)

    Yamanaka, Hidetsugu

    1982-01-01

    The author visited Nepal from October, 1980, to February, 1981, investigated the geomorphology and upper Quaternary geology in Central Nepal, and collected a number of samples for radiocarbon dating. After returning to his university, he dated ten samples by himself. In Nepal, radiocarbon age has been scarcely reported as yet, besides in Kathmandu valley. Therefore, the author's ten data of the age are very important for the late Quaternary chronological study of Nepal Himalayas. In this paper, the author describes sampling localities and horizons, dating results and their geomorphological significance. These ten samples included Pokhara valley, Marsyandi Kohla, Modi Khola, Madi Khola and Muktinath samples. Some conclusion was derived as for the geomorphological development in central Nepal: The last Himalayan glacial age had already ended before 9,000 yr BP (years before A.D. 1950); In the Midland region, from 4,300 to 600 yr BP, some large-scale mudflows broke out nearly contemporaneously in the upper valleys, and they flowed down torrentially and catastrophically to deposit in the middle course of rivers. But the cause of vast quantity of material suddenly brought down from the Great Himalayas has been still left unexplained. The conclusion like this also was able to be applied to the middle Marsyandi Khola and the Pokhara valley. The wide-spread schema that the river was aggraded in the glacial age and degraded in the interglacial age may not be applicable to the rivers in the Midland region of Nepal Himalayas. (Wakatsuki, Y.)

  3. Annual variability in the radiocarbon age and source of dissolved CO2 in a peatland stream

    International Nuclear Information System (INIS)

    Garnett, Mark H.; Dinsmore, Kerry J.; Billett, Michael F.

    2012-01-01

    Radiocarbon dating has the capacity to significantly improve our understanding of the aquatic carbon cycle. In this study we used a new passive sampler to measure the radiocarbon ( 14 C) and stable carbon (δ 13 C) isotopic composition of dissolved CO 2 for the first time in a peatland stream throughout a complete year (May 2010–June 2011). The in-stream sampling system collected time-integrated samples of CO 2 continuously over approximately 1 month periods. The rate of CO 2 trapping was proportional to independently measured streamwater CO 2 concentrations, demonstrating that passive samplers can be used to estimate the time-averaged dissolved CO 2 concentration of streamwater. While there was little variation and no clear trend in δ 13 CO 2 values (suggesting a consistent CO 2 source), we found a clear temporal pattern in the 14 C concentration of dissolved CO 2 . The 14 C age of CO 2 varied from 707 ± 35 to 1210 ± 39 years BP, with the youngest CO 2 in the autumn and oldest in spring/early summer. Mean stream discharge and 14 C content of dissolved CO 2 were positively correlated. We suggest that the observed pattern in the 14 C content of dissolved CO 2 reflects changes in its origin, with older carbon derived from deeper parts of the peat profile contributing proportionally more gaseous carbon during periods of low stream flow. - Highlights: ► Dissolved CO 2 was sampled from a peatland stream and radiocarbon dated. ► Samples collected using new passive sampler are suitable for integrated monthly samples. ► Age of CO 2 ranged from 707 to 1210 years old and seasonal pattern is observed. ► Age correlated with discharge and reflected source of dissolved CO 2 . ► Study highlights the value of 14 C analysis and potential of new method.

  4. Very little in situ produced radiocarbon retained in accumulating Antarctic ice

    NARCIS (Netherlands)

    Kemp, W.J.M. van der; Alderliesten, C.; Borg, K. van der; Holmlund, P.; Jong, A.F.M. de; Karlöf, L.; Lamers, R.A.N.; Oerlemans, J.; Thomassen, M.; Wal, R.S.W. van de

    2000-01-01

    Ice samples from Dronning Maud Land, Antarctica, were analyzed for 14CO2 and 14CO by accelerator mass spectrometry. Only a small amount (~2%) of in situ produced radiocarbon was detected. The calibrated radiocarbon ages, corrected for in situ produced 14C, are in fair agreement with age estimates

  5. Difference in radiocarbon ages of carbonized material from the inner and outer surfaces of pottery from a wetland archaeological site.

    Science.gov (United States)

    Miyata, Yoshiki; Minami, Masayo; Onbe, Shin; Sakamoto, Minoru; Matsuzaki, Hiroyuki; Nakamura, Toshio; Imamura, Mineo

    2011-01-01

    AMS (Accelerator Mass Spectrometry) radiocarbon dates for eight potsherds from a single piece of pottery from a wetland archaeological site indicated that charred material from the inner pottery surfaces (5052 ± 12 BP; N = 5) is about 90 (14)C years older than that from the outer surfaces (4961 ± 22 BP; N = 7). We considered three possible causes of this difference: the old wood effect, reservoir effects, and diagenesis. We concluded that differences in the radiocarbon ages between materials from the inner and outer surfaces of the same pot were caused either by the freshwater reservoir effect or by diagenesis. Moreover, we found that the radiocarbon ages of carbonized material on outer surfaces (soot) of pottery from other wetland archaeological sites were the same as the ages of material on inner surfaces (charred food) of the same pot within error, suggesting absence of freshwater reservoir effect or diagenesis.

  6. Intercomparison of radiocarbon bomb pulse and 210Pb age models. A study in a peat bog core from North Poland

    International Nuclear Information System (INIS)

    Piotrowska, Natalia; Vleeschouwer, Francois De; Sikorski, Jaroslaw; Pawlyta, Jacek; Fagel, Nathalie; Roux, Gael Le; Pazdur, Anna

    2010-01-01

    Radiocarbon and 210 Pb were measured on the uppermost 40 cm of a Wardenaar peat core retrieved from a Baltic raised bog at Slowinskie Blota (Pomerania, North Poland). This site is the subject of ongoing multiproxy studies covering the last 1300 years. Radiocarbon age model was constructed on the basis of 14 AMS dates obtained on selected Sphagnum spp. fragments, with use of P S equence tool. We present here a comparison of this model with the age model obtained using CRS model classically applied to 210 Pb measurements.

  7. Intercomparison of radiocarbon bomb pulse and 210Pb age models. A study in a peat bog core from North Poland

    Science.gov (United States)

    Piotrowska, Natalia; De Vleeschouwer, François; Sikorski, Jarosław; Pawlyta, Jacek; Fagel, Nathalie; Le Roux, Gaël; Pazdur, Anna

    2010-04-01

    Radiocarbon and 210Pb were measured on the uppermost 40 cm of a Wardenaar peat core retrieved from a Baltic raised bog at Słowińskie Błota (Pomerania, North Poland). This site is the subject of ongoing multiproxy studies covering the last 1300 years. Radiocarbon age model was constructed on the basis of 14 AMS dates obtained on selected Sphagnum spp. fragments, with use of P_Sequence tool. We present here a comparison of this model with the age model obtained using CRS model classically applied to 210Pb measurements.

  8. Radiocarbon age-offsets in an arctic lake reveal the long-term response of permafrost carbon to climate change

    Science.gov (United States)

    Gaglioti, Benjamin V.; Mann, Daniel H.; Jones, Benjamin M.; Pohlman, John W.; Kunz, Michael L.; Wooller, Matthew J.

    2014-01-01

    Continued warming of the Arctic may cause permafrost to thaw and speed the decomposition of large stores of soil organic carbon (OC), thereby accentuating global warming. However, it is unclear if recent warming has raised the current rates of permafrost OC release to anomalous levels or to what extent soil carbon release is sensitive to climate forcing. Here we use a time series of radiocarbon age-offsets (14C) between the bulk lake sediment and plant macrofossils deposited in an arctic lake as an archive for soil and permafrost OC release over the last 14,500 years. The lake traps and archives OC imported from the watershed and allows us to test whether prior warming events stimulated old carbon release and heightened age-offsets. Today, the age-offset (2 ka; thousand of calibrated years before A.D. 1950) and the depositional rate of ancient OC from the watershed into the lake are relatively low and similar to those during the Younger Dryas cold interval (occurring 12.9–11.7 ka). In contrast, age-offsets were higher (3.0–5.0 ka) when summer air temperatures were warmer than present during the Holocene Thermal Maximum (11.7–9.0 ka) and Bølling-Allerød periods (14.5–12.9 ka). During these warm times, permafrost thaw contributed to ancient OC depositional rates that were ~10 times greater than today. Although permafrost OC was vulnerable to climate warming in the past, we suggest surface soil organic horizons and peat are presently limiting summer thaw and carbon release. As a result, the temperature threshold to trigger widespread permafrost OC release is higher than during previous warming events.

  9. Radiocarbon measurements of tree-ring samples from Japanese woods

    International Nuclear Information System (INIS)

    Ozaki, Hiromasa; Sakamoto, Minoru; Imamura, Mineo; Mitsutani, Takumi

    2008-01-01

    Since radiocarbon age is a model age based on constancy of atmospheric radiocarbon concentration and a provisional value of 5568 years for the 14 C half-life, calibration to calendar age is required for practical dating. The dataset, called IntCal, used for the calibration has been constructed by international consortium. Most parts of the IntCal have been based on the measurement of radiocarbon in dendrochronologically dated tree-ring samples from woods in Europe and North America. Regional offsets, which are designed as differences of local atmospheric radiocarbon from IntCal, have been pointed out based on recent radiocarbon measurements for tree-ring samples from a few regions. We have also measured radiocarbon of tree-ring samples from Japanese woods in order to investigate regional offsets in Japan. In this study, radiocarbon measurements for tree-ring samples from three different Japanese woods at around AD500 were carried out. Consequently, differences from IntCal04 at around AD500 were confirmed, although no systematic offset are found. However, the results obtained in this study agree with the raw data used for construction of IntCal04. This could pose a question to calculation method of IntCal04. (author)

  10. Constructing deposition chronologies for peat deposits using radiocarbon dating

    Directory of Open Access Journals (Sweden)

    N. Piotrowska

    2011-06-01

    Full Text Available Radiocarbon dating is one of the main methods used to establish peat chronologies. This article reviews the basis of the method and its application to dating of peat deposits. Important steps in the radiocarbon dating procedure are described, including selection and extraction of material (and fractions for dating, chemical and physical preparation of media suitable for measurements, measurements of 14C activity or concentration, calculations, calibration of results and age-depth modelling.

  11. New accelerator mass spectrometry radiocarbon ages for the Mazama tephra layer from Kootenay National Park, British Columbia, Canada

    International Nuclear Information System (INIS)

    Hallett, D.J.; Hills, L.V.; Clague, J.J.

    1997-01-01

    Charcoal fragments recovered from the Mazama air-fall tephra layer in cores from Dog and Cobb lakes, Kootenay National Park, British Columbia, yielded accelerator mass spectrometry ages of 6720 ± 70 and 6760 ± 70 14 C years BP, respectively. These two new ages, together with other previously published radiocarbon ages on charcoal and twig fragments from Mazama air-fall deposits, indicate that the climatic eruption of Mount Mazama occurred 6730 ± 40 14 C years BP. (author)

  12. Radiocarbon ages of ground water as a basis for the determination of safe limits of aquifer exploitation

    International Nuclear Information System (INIS)

    Tamers, M.A.; Stipp, J.J.; Weiner, R.

    1975-01-01

    Deep ground waters of the Biscayne aquifer of south Florida were studied with radiocarbon dating techniques. Dissolved carbonates served as the material for the age determinations. Limestone dilution corrections of the measured carbon-14 activities were made by comparison of the relative concentrations of bicarbonate and total carbonates. The deep well waters of the southern portion of the deposit have corrected radiocarbon contents indicating thermonuclear weapon testing contamination; they are, therefore, less than 20 years old. The ages of the ground waters generally increase in the northern direction. This is interpreted as due to the greater depth of the deposit of that region. A model is formulated for ground water movement in an unconfined producing hydrological unit and applied to the radiocarbon results of the most intensively exploited zone of the Biscayne aquifer. It is shown that the water which is extracted by the municipal wells in this area is limited to the bottom third of the deposit. The avoidance of pollution from the surrounding septic tanks in the shallower depths of the area is explained in this way. The model leads to an objective estimation of the safe limit for the ground water extraction rate in the zone. By application of radiocarbon dating, it is possible to obtain useful information without disturbing the water supply

  13. Radiocarbon ages and age models for the past 30,000 years in Bear Lake, Utah and Idaho

    Science.gov (United States)

    Colman, Steven M.; Rosenbaum, J.G.; Kaufman, D.S.; Dean, W.E.; McGeehin, J.P.

    2009-01-01

    Radiocarbon analyses of pollen, ostracodes, and total organic carbon (TOC) provide a reliable chronology for the sediments deposited in Bear Lake over the past 30,000 years. The differences in apparent age between TOC, pollen, and carbonate fractions are consistent and in accord with the origins of these fractions. Comparisons among different fractions indicate that pollen sample ages are the most reliable, at least for the past 15,000 years. The post-glacial radiocarbon data also agree with ages independently estimated from aspartic acid racemization in ostracodes. Ages in the red, siliclastic unit, inferred to be of last glacial age, appear to be several thousand years too old, probably because of a high proportion of reworked, refractory organic carbon in the pollen samples. Age-depth models for five piston cores and the Bear Lake drill core (BL00-1) were constructed by using two methods: quadratic equations and smooth cubic-splinefits. The two types of age models differ only in detail for individual cores, and each approach has its own advantages. Specific lithological horizons were dated in several cores and correlated among them, producing robust average ages for these horizons. The age of the correlated horizons in the red, siliclastic unit can be estimated from the age model for BL00-1, which is controlled by ages above and below the red, siliclastic unit. These ages were then transferred to the correlative horizons in the shorter piston cores, providing control for the sections of the age models in those cores in the red, siliclastic unit. These age models are the backbone for reconstructions of past environmental conditions in Bear Lake. In general, sedimentation rates in Bear Lake have been quite uniform, mostly between 0.3 and 0.8 mm yr-1 in the Holocene, and close to 0.5 mm yr-1 for the longer sedimentary record in the drill core from the deepest part of the lake. Copyright ?? 2009 The Geological Society of America.

  14. Offsets in radiocarbon ages between plants and shells from same horizons of coastal sediments in Korea

    Energy Technology Data Exchange (ETDEWEB)

    Nakanishi, Toshimichi [Geologic Environment Division, Korea Institute of Geoscience & Mineral Resources, Gajeong-dong 30, Yuseong-gu, Daejeon (Korea, Republic of); Hong, Wan, E-mail: whong@kigam.re.kr [Geologic Environment Division, Korea Institute of Geoscience & Mineral Resources, Gajeong-dong 30, Yuseong-gu, Daejeon (Korea, Republic of); Sung, Ki Suk [Geologic Environment Division, Korea Institute of Geoscience & Mineral Resources, Gajeong-dong 30, Yuseong-gu, Daejeon (Korea, Republic of); Carbon Analysis Laboratory (CAL), 25, 114 Gil, Taejeon-ro, Dong-gu, Daejeon (Korea, Republic of); Sung, Kil Ho [Geologic Environment Division, Korea Institute of Geoscience & Mineral Resources, Gajeong-dong 30, Yuseong-gu, Daejeon (Korea, Republic of); University of Science and Technology (UST), 217 Gajeong-ro, Yuseong-gu, Daejeon (Korea, Republic of); Nakashima, Rei [Institute of Geology & Geoinformation, Advanced Industrial Science & Technology, Higashi 1-1-1, Tsukuba, Ibaraki (Japan)

    2015-10-15

    To measure the spatial and chronological changes of the reservoir effect around the Korean Peninsula, the radiocarbon ages of 38 marine shell and terrestrial plant pairs from the same horizons of six cores of Holocene sediments collected from the southern coast and western coast sites of the peninsula were measured. These reservoir ages (R) were distributed in the range of 430 ± 190 yrs within 60 ± 60 to 1000 ± 60 yrs starting in 9000 cal BP. The average R values of the cores obtained from large rivers, such as the S13 and YAR-4 cores (340 and 190 yrs), were clearly smaller than the R values of the sites far from a large river, such as the S15 and W09 cores (470 and 650 yrs). This is thought to be associated with the mixing process of old brine and young freshwater. On the other hand, the R values of the S13, W17, and YAR-4 cores gradually increased during the time span from 6700 to 8200 cal BP. The R values for the S15 core also increased in the period from 2800 to 3800 cal BP. Such tendencies result from the mixing ratio increase of brine due to the rising sea level.

  15. Offsets of atmospheric radiocarbon concentration from IntCal09 in East Asia appeared in human bones excavated at Imdangdong tombs, Jingshan, Korea

    International Nuclear Information System (INIS)

    Sakamoto, Minoru; Takada, Kanta; Lee, Chang-hee; Fujio, Shin'ichiro; Woo, Byoung-cheul; Park, Seung-kyu

    2013-01-01

    Radiocarbon dating of human bones excavated from Imdangdong toms, Korea, was carried out. The preservation of bone collagen was poor, and even though the measurement was successful, their calibrated ages were not in good agreement with archaeological observations as well. However, in comparing to the radiocarbon offsets appeared in Japanese tree rings, the calibration age shifted to the proper age. This might show that the regional effects on calibration curve were coincident between Japanese archipelagos and Korean peninsula. (author)

  16. Tephrochronology as a tool to constrain radiocarbon reservoir age in the deglacial Bering Sea

    Science.gov (United States)

    Chapman, A. U.; White-Nockleby, C.; de Konkoly Thege, P. A.; Rubel, J. N.; Cook, M. S.; Mix, A. C.; Addison, J. A.

    2015-12-01

    these cores could have implications for evaluating the accuracy of radiocarbon reconstructions of Pacific circulation that assume a constant preindustrial surface reservoir age.

  17. Radiocarbon ages of 'exposed reef' at Minamitori-shima (Marcus Island), Central Pacific

    International Nuclear Information System (INIS)

    Konishi, Kenji; Tanaka, Takeo; Omura, Akio

    1985-01-01

    Studies were carried out on the geoscientific features of bench-like steps and exposed or elevated reef on the coast of Minamitori-shima (Marcus Island) by referring mainly Bryan's report in 1903. Field work were carried out in May, 1979 for geoscientific survey and coral sample collection. Features of the bench-like steps survey clarified that only four steps were found for those reported by Bryan. As for the exposed reef reported by him, it was found at the northern corner of the western beach in contact with the moat of present reef. Across the northern part of the western coast two transects, A and B, were selected, and cobble-size fossils of corals composed by mainly Favia and Favites were collected from beach conglomerate at 6 and 8 sampling points of the A and B transects, respectively. Except one specimen, all the collected corals of the both transects showed their age by radiocarbon dating of 2,430 to 3,210 y B.P. and their average value was 2,838 +- 206 y B.P. As for ages of reef creast and reef flat, they were 2,130 and 2,880 y B.P., and 540 and 1,280 y B.P., respectively. Based on these coral age data and related geoscientific understandings, it was speculated that the origin of beach conglomerate was a tempesite deposited above mean sea level through stormy high tide. In addition to this speculation, geotectonic movement and geological features are also discussed in this paper. (Takagi, S.)

  18. Radiocarbon dating of a very large African baobab.

    Science.gov (United States)

    Patrut, Adrian; von Reden, Karl F; Lowy, Daniel A; Alberts, Andries H; Pohlman, John W; Wittmann, Rudolf; Gerlach, Dana; Xu, Li; Mitchell, Clark S

    2007-11-01

    In late 2004, Grootboom, probably the largest known African baobab (Adansonia digitata L.), collapsed unexpectedly in northeastern Namibia. Ten wood samples collected from different areas of the trunk were processed and investigated by accelerator mass spectrometry radiocarbon dating. The radiocarbon dates of three samples were greater than 1000 years BP (radiocarbon years before present, i.e., before AD 1950). The corresponding calibrated calendar age of the oldest sample was 1275 +/- 50 years, making Grootboom the oldest known angiosperm tree with reliable dating results. Variations in radiocarbon dates among the wood samples indicated that, morphologically, Grootboom was a quintuple tree, whereas genetically, it was a single individual. Ages of extreme lateral samples revealed that, over the past 500-600 years, Grootbooom had almost ceased growing, providing information about climate changes in central southern Africa. The sudden demise of Grootboom coincided with the spread of the poorly studied baobab disease, which has become epidemic in Namibia.

  19. Determination of radiocarbon reservoir age of Lake Van by mineral magnetic and geochemical analysis

    Science.gov (United States)

    Makaroglu, Ozlem; Namik Cagatay, M.; Pesonen, Lauri J.; Orbay, Naci

    2017-04-01

    Lake Van is the largest soda lake in the world, located on the east Anatolian Plateau in Turkey. Its varved sediments provide an excellent archive of high-resolution paleoclimate record for the Near East. Varve counting and radiocarbon methods are therefore important dating techniques for investigating the Lake Van sedimentary paleoclimate record. In here we present detailed magnetic and geochemical record of Lake Van. We have studied 4.56 m (core VP0801) and 4.70 m (core VP0807) long cores recovered from 80 m and 65 m water depths located in SE and SW of Lake Van, respectively. Here, we have benefited from magnetic properties with associated remanent magnetization of the sediments from Lake Van to correlate the cores which contain of tephra layers. The cores cover the last 8.4 ka and lithologically include three laminated sedimentary units. From top to the bottom, the units were dated 4.2 ka BP-present, 5.4-4.2 ka BP and older than 5.4 ka BP. We identified tephra layers previously dated by varve counting, and used the varve ages to obtain age models for the cores. We also obtained a total of eight Accelerator Mass Spectrometry (AMS) 14C dates from total organic carbon (TOC) in the two cores, close to the tephra layers. Comparison of the varve ages of the AMS 14C dated samples with their corresponding AMS 14C dates indicates large differences, suggesting significant reservoir ages that range from 2.8 to 2.5 ka for 3.0-2.4 varve ka BP and from 2.8 to 3.3 ka for 8.0-5.9 varve ka BP. The results suggest that the reservoir age of the organic matter increases with the varve age of the sediments. This increase is mainly related to the rate of supply of "dead" carbon from the old carbonate rocks in the watershed of Lake Van, which was relatively higher during 8.4-5.9 ka than during 3.0-2.4 ka BP because of the higher atmospheric precipitation and higher rate of biochemical weathering during the former period.

  20. Radiocarbon age of the recent deposits of the Indian Ocean western part (Seychelles)

    International Nuclear Information System (INIS)

    Svitoch, A.A.; Parunin, O.B.

    1988-01-01

    Mass radiocarbon dating according to Pleistocene precipitations of the islands of the Western Part of the Indian ocean is carried out. Time of formation of black-rock precipitations, low benches and island sandstones of low islands - middle-late Holocene - is established. Rocks of a reef complex are late Pleistocene. Relative concentration of dates according to various types of deposits points to the trustworthness and testifies about usefulness of radiocarbon analysis for stratigraphic and chronological separation of carbonate precipitations of islands of the equatorial zone of the ocean

  1. Very little in situ produced radiocarbon retained in accumulating Antarctic ice

    International Nuclear Information System (INIS)

    Kemp, W.J.M. van der; Alderliesten, C.; Borg, K. van der; Holmlund, P.; Jong, A.F.M. de; Karloef, L.; Lamers, R.A.N.; Oerlemans, J.; Thomassen, M.; Wal, R.S.W. van de

    2000-01-01

    Ice samples from Dronning Maud Land, Antarctica, were analyzed for 14 CO 2 and 14 CO by accelerator mass spectrometry. Only a small amount (∼2%) of in situ produced radiocarbon was detected. The calibrated radiocarbon ages, corrected for in situ produced 14 C, are in fair agreement with age estimates obtained from stratigraphical methods added to a gas inclusion model. The ages of the entrapped air range from recent to ca. 1200 AD

  2. A simple radiocarbon dating method for determining the age and growth rate of deep-sea sponges

    International Nuclear Information System (INIS)

    Fallon, S.J.; James, K.; Norman, R.; Kelly, M.; Ellwood, M.J.

    2010-01-01

    The ability to reliably age siliceous sponges is explored using radiocarbon dating of several hexactinellid sponge specimens including Rossella racovitzaeracovitzae Topsent, 1901 (C. Hexactinellida: O. Lyssacinosida: F. Rossellidae), collected from the Ross Sea, Antarctica. The optimal pretreatment was found to consist of both sequential acid digestion and pre-roasting at temperatures >400 deg. C. Subsequent combustion at 900 deg. C liberated the proteinaceous material within the spicule matrix and once the reservoir age of the surrounding water was accounted for, a linear extension rate was calculated to be around 2.9 mm yr -1 , aging the sponge at ∼440 years old.

  3. A simple radiocarbon dating method for determining the age and growth rate of deep-sea sponges

    Science.gov (United States)

    Fallon, S. J.; James, K.; Norman, R.; Kelly, M.; Ellwood, M. J.

    2010-04-01

    The ability to reliably age siliceous sponges is explored using radiocarbon dating of several hexactinellid sponge specimens including Rossella racovitzaeracovitzae Topsent, 1901 ( C. Hexactinellida: O. Lyssacinosida: F. Rossellidae), collected from the Ross Sea, Antarctica. The optimal pretreatment was found to consist of both sequential acid digestion and pre-roasting at temperatures >400 °C. Subsequent combustion at 900 °C liberated the proteinaceous material within the spicule matrix and once the reservoir age of the surrounding water was accounted for, a linear extension rate was calculated to be around 2.9 mm yr -1, aging the sponge at ˜440 years old.

  4. Youngest radiocarbon age for Jefferson's ground sloth, Megalonyx jeffersonii (Xenarthra, Megalonychidae)

    DEFF Research Database (Denmark)

    Gregory McDonald, H.; Stafford, Thomas W.; Gnidovec, Dale M.

    2015-01-01

    A partial skeleton of the extinct ground sloth, Megalonyx jeffersonii, recovered from a farm near Millersburg, Ohio in 1890, was radiocarbon dated for the first time. The ungual dated is part of a skeleton mounted for exhibit at the Orton Geological Museum at Ohio State University and was the fir...

  5. THE IRON AGE AROUND THE MEDITERRANEAN : A HIGH CHRONOLOGY PERSPECTIVE FROM THE GRONINGEN RADIOCARBON DATABASE

    NARCIS (Netherlands)

    van der Plicht, J.; Bruins, H.J.; Nijboer, A.J.

    2009-01-01

    In this paper, we present an overview of radiocarbon dating contributions from Groningen, concerning 9 sites from around the Mediterranean region: Israel, Sinai (Egypt), Jordan, Spain, Tunisia, and Italy. Full date lists of the 9 sites are presented. Our (14)C dates are discussed in terms of present

  6. The neolithic demographic transition in Europe: correlation with juvenility index supports interpretation of the summed calibrated radiocarbon date probability distribution (SCDPD as a valid demographic proxy.

    Directory of Open Access Journals (Sweden)

    Sean S Downey

    Full Text Available Analysis of the proportion of immature skeletons recovered from European prehistoric cemeteries has shown that the transition to agriculture after 9000 BP triggered a long-term increase in human fertility. Here we compare the largest analysis of European cemeteries to date with an independent line of evidence, the summed calibrated date probability distribution of radiocarbon dates (SCDPD from archaeological sites. Our cemetery reanalysis confirms increased growth rates after the introduction of agriculture; the radiocarbon analysis also shows this pattern, and a significant correlation between both lines of evidence confirms the demographic validity of SCDPDs. We analyze the areal extent of Neolithic enclosures and demographic data from ethnographically known farming and foraging societies and we estimate differences in population levels at individual sites. We find little effect on the overall shape and precision of the SCDPD and we observe a small increase in the correlation with the cemetery trends. The SCDPD analysis supports the hypothesis that the transition to agriculture dramatically increased demographic growth, but it was followed within centuries by a general pattern of collapse even after accounting for higher settlement densities during the Neolithic. The study supports the unique contribution of SCDPDs as a valid demographic proxy for the demographic patterns associated with early agriculture.

  7. Radiocarbon dating of a sutra container excavated at the Minagi Daibutsuyama site, Fukuoka Prefecture, Japan

    International Nuclear Information System (INIS)

    Oda, Hirotaka; Nakamura, Toshio; Tsukamoto, Toshio

    2004-01-01

    The historical age of a sutra container (Kyozutsu) excavated at the Minagi Daibutsuyama site was estimated by the AMS method. Radiocarbon ages for samples of the charred sutra kept in the container range from 950 to 1000 BP, corresponding to the first half of the 11th or the middle of the 12th century in the calibrated ages. The radiocarbon ages of wood charcoal blocks excavated around the container range from 1000 to 1100 BP, corresponding to calibrated ages from the 10th to the early 11th century. Since the radiocarbon age of wood charcoal can be decades older than the age of production as a result of the old wood effect, the historical age of the sutra container formation is estimated at the first half of the 11th century

  8. Rate estimates for lateral bedrock erosion based on radiocarbon ages, Duck River, Tennessee

    International Nuclear Information System (INIS)

    Brakenridge, G.R.

    1985-01-01

    Rates of bedrock erosion in ingrown meandering rivers can be inferred from the location of buried relict flood-plain and river-bank surfaces, associated paleosols, and radiocarbon dates. Two independent methods are used to evaluate the long-term rates of limestone bedrock erosion by the Duck River. Radiocarbon dates on samples retrieved from buried Holocene flood-plain and bank surfaces indicate lateral migration of the river bank at average rates of 0.6-1.9 m/100 yr. Such rates agree with lateral bedrock cliff erosion rates of 0.5-1.4 m/100 yr, as determined from a comparison of late Pleistocene and modern bedrock cliff and terrace scarp positions. These results show that lateral bedrock erosion by this river could have occurred coevally with flood-plain and terrace formation and that the resulting evolution of valley meander bends carved into bedrock is similar in many respects to that of channel meanders cut into alluvium. 11 references, 5 figures

  9. Bomb pulse radiocarbon dating

    International Nuclear Information System (INIS)

    Tuniz, C.; Zoppi, U.; Hotchkis, M.A.C.

    2004-01-01

    by measuring the residual 14 C concentration in organic samples, it is possible to calculate the time elapsed since the material was originally formed. Ages up to about 50 000 before present (BP) can be determined by radiocarbon dating. Calibration curves determined with high precision for all of the Holocene by radiocarbon measurements on tree ring samples, which are independently and precisely dated by dendrochronology, are used to correct for variations of 14 C production rate in the atmosphere due to geomagnetic and heliomagnetic effects and global variations in the parameters of the carbon cycle

  10. Intercomparison of radiocarbon bomb pulse and {sup 210}Pb age models. A study in a peat bog core from North Poland

    Energy Technology Data Exchange (ETDEWEB)

    Piotrowska, Natalia, E-mail: natalia.piotrowska@polsl.p [Department of Radioisotopes, Institute of Physics, Silesian University of Technology, Krzywoustego, 2, Gliwice 44100 (Poland); Vleeschouwer, Francois De; Sikorski, Jaroslaw; Pawlyta, Jacek [Department of Radioisotopes, Institute of Physics, Silesian University of Technology, Krzywoustego, 2, Gliwice 44100 (Poland); Fagel, Nathalie; Roux, Gael Le [Clays and Palaeoclimate Unit, Department of Geology, University of Liege, Allee du 6 Aout, B18, Sart Tilman, Liege 4000 (Belgium); Pazdur, Anna [Department of Radioisotopes, Institute of Physics, Silesian University of Technology, Krzywoustego, 2, Gliwice 44100 (Poland)

    2010-04-15

    Radiocarbon and {sup 210}Pb were measured on the uppermost 40 cm of a Wardenaar peat core retrieved from a Baltic raised bog at Slowinskie Blota (Pomerania, North Poland). This site is the subject of ongoing multiproxy studies covering the last 1300 years. Radiocarbon age model was constructed on the basis of 14 AMS dates obtained on selected Sphagnum spp. fragments, with use of P{sub S}equence tool. We present here a comparison of this model with the age model obtained using CRS model classically applied to {sup 210}Pb measurements.

  11. Age validation of canary rockfish (Sebastes pinniger) using two independent otolith techniques: lead-radium and bomb radiocarbon dating.

    Energy Technology Data Exchange (ETDEWEB)

    Andrews, A H; Kerr, L A; Cailliet, G M; Brown, T A; Lundstrom, C C; Stanley, R D

    2007-11-04

    Canary rockfish (Sebastes pinniger) have long been an important part of recreational and commercial rockfish fishing from southeast Alaska to southern California, but localized stock abundances have declined considerably. Based on age estimates from otoliths and other structures, lifespan estimates vary from about 20 years to over 80 years. For the purpose of monitoring stocks, age composition is routinely estimated by counting growth zones in otoliths; however, age estimation procedures and lifespan estimates remain largely unvalidated. Typical age validation techniques have limited application for canary rockfish because they are deep dwelling and may be long lived. In this study, the unaged otolith of the pair from fish aged at the Department of Fisheries and Oceans Canada was used in one of two age validation techniques: (1) lead-radium dating and (2) bomb radiocarbon ({sup 14}C) dating. Age estimate accuracy and the validity of age estimation procedures were validated based on the results from each technique. Lead-radium dating proved successful in determining a minimum estimate of lifespan was 53 years and provided support for age estimation procedures up to about 50-60 years. These findings were further supported by {Delta}{sup 14}C data, which indicated a minimum estimate of lifespan was 44 {+-} 3 years. Both techniques validate, to differing degrees, age estimation procedures and provide support for inferring that canary rockfish can live more than 80 years.

  12. Borderline radiocarbon

    NARCIS (Netherlands)

    van der Plicht, J.

    Radiocarbon dating of peat has its intrinsic problems. This is often caused by mobile organic fractions. For the Weichselian Pleniglacial, another methodological problem arises: the limit of the C-14 dating method. This is discussed in terms of bulk (i.e. non-selected material, generally dated

  13. Radiocarbon ages of soil charcoals from the southern Alps, Ticino, Switzerland

    International Nuclear Information System (INIS)

    Hajdas, Irka; Schlumpf, Nadia; Minikus-Stary, Nicole; Hagedorn, Frank; Eckmeier, Eileen; Schoch, Werner; Burga, Conradin; Bonani, Georges; Schmidt, Michael W.I.; Cherubini, Paolo

    2007-01-01

    Radiocarbon dating of macroscopic charcoal is a useful tool for paleoclimatic and paleoecologic reconstructions. Here we present results of 14 C dating of charcoals found in charcoal-rich soils of Ticino and the Misox Valley (southern Switzerland) which indicate that the Late Glacial and early Holocene fires coincided with warm phases in the North Atlantic region and low lake levels in the Central Europe. Late Holocene charcoals found in these soils document an earlier than believed presence of sweet chestnut (Castanea sativa Mill.) in southern Switzerland. Sweet chestnut trees play a key role in Mediterranean woodlands, and for longer than two millennia have been used as a food source. Based on palynological evidence it is commonly believed that in southern Switzerland C. sativa was first introduced 2000 years ago by the Romans, who cultivated it for wood and fruit production. Our results indicate that this tree species was present on the southern slopes of the Alps ∼1500 years earlier than previously assumed, and therefore was likely introduced independently from cultivation by the Romans

  14. Calibration of the 14C timescale over the past 30,000 years using mass spectrometric U-Th ages from Barbados corals

    International Nuclear Information System (INIS)

    Bard, E.; Hamelin, B.; Fairbanks, R.G.; Zindler, A.

    1990-01-01

    Uranium-thorium ages obtained by mass spectrometry from corals raised off the island of Barbados confirm the high precision of this technique over at least the past 30,000 years. Comparison of the U-Th ages with 14 C ages obtained on the Holocene samples shows that the U-Th ages are accurate, because they accord with the dendrochronological calibration. Before 9,000 yr BP the 14 C ages are systematically younger than the U-Th ages, with a maximum difference of ∼3,500 yr at ∼20,000 yr BP. The U-Th technique thus provides a way of calibrating the radiocarbon timescale beyond the range of dendrochronological calibration. (author)

  15. Radiocarbon ages of insects and plants frozen in the No. 31 Glacier, Suntar-Khayata Range, eastern Siberia

    Energy Technology Data Exchange (ETDEWEB)

    Nakazawa, F., E-mail: nakazawa@nipr.ac.jp [National Institute of Polar Research, 10-3 Midori-cho, Tachikawa, Tokyo 190-8518 (Japan); Transdisciplinary Research Integration Center, Hulic Kamiyacho Bldg. 2F, 4-3-13 Toranomon, Minato-ku, Tokyo 105-0001 (Japan); Uchida, M.; Kondo, M. [Center for Environmental Measurement and Analysis, National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305-0053 (Japan); Kadota, T. [Japan Agency for Marine-Earth Science and Technology, 2-15 Natsushima, Yokosuka 237-0061 (Japan); Shirakawa, T. [Kitami Institute of Technology, Kitami, Hokkaido 090-8507 (Japan); Enomoto, H. [National Institute of Polar Research, 10-3 Midori-cho, Tachikawa, Tokyo 190-8518 (Japan); Department of Polar Science, The Graduate University for Advanced Studies (SOKENDAI), 10-3 Midori-cho, Tachikawa, Tokyo 190-8518 (Japan); Fedorov, A.N. [Melnikov Permafrost Institute, SB RAN, Yakutsk 6770110 (Russian Federation); North-Eastern Federal University, Yakutsk 677010 (Russian Federation); Fujisawa, Y. [Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522 (Japan); Konstantinov, P.Y. [Melnikov Permafrost Institute, SB RAN, Yakutsk 6770110 (Russian Federation); Kusaka, R. [Kitami Institute of Technology, Kitami, Hokkaido 090-8507 (Japan); Miyairi, M. [Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522 (Japan); Ohata, T.; Yabuki, H. [Japan Agency for Marine-Earth Science and Technology, 2-15 Natsushima, Yokosuka 237-0061 (Japan)

    2015-10-15

    The aim of this study was to estimate the age of glacier ice in the No. 31 Glacier in the Suntar-Khayata Range of eastern Siberia by performing dating of insects thought to be long-legged fly species (Dolichopodidae) as well as plants (species unknown) fragments preserved in the ice. Ice samples containing organisms were collected at depths of 0.4–1.1 m at five points from the middle to lowest parts of the glacier in 2013. The age of an insect collected at the lowest point on the glacier was estimated as 2038 ± 32 yr B.P. Insects collected at higher points had a modern or near-modern radiocarbon age. The age of plant fragments collected at the uppermost and middle points was 1531 ± 44 and 1288 ± 26 yr B.P., respectively, and that of a mixture of plant and insect fragments collected at the lowest point was 9772 ± 42 yr B.P. When comparing specimens collected at the same point, the plant fragments were found to be older than the insects. In 2012–2014 observations, some living insects were found on the glacier, and thus the age of the insects appears to correspond to the age of the ice. On the other hand, the plant fragments might have already aged since detachment from the source plants. This study found an approximately 2000-year gap in the age of the ice between the lowest and higher points. Annual mass balance observations from 2012 to 2014 showed that in recent years, the glacier sometimes had no accumulation area. Therefore, the wide gap in the age of ice may be due to a difference in past melting processes between the lowest and higher points on the glacier.

  16. Radiocarbon dating

    International Nuclear Information System (INIS)

    Lazos R, L.

    2005-01-01

    The application of the radiocarbon dating in archaeology has not served only to solve problems related with the establishment of chronologies, but also in the development of archaeological methods of excavation and interpretation. This has been possible because the dating method by radiocarbon provides a common temporary scale that transcends the cultural and regional frontiers. It is even spoken of the revolution that has meant the fact that the application of this method has allowed to the archaeologist to pass from the construction of chronologies until the evaluation and dynamic interpretation of the archaeological data to build theories. This work explains and compares methods for the detection of 14 C, as the gas counting, the liquid scintillation counting and the mass spectrometry with accelerators. (Author)

  17. Origins of the Iberomaurusian in NW Africa: new AMS radiocarbon dating of the Middle and Later Stone Age deposits at Taforalt Cave, Morocco.

    Science.gov (United States)

    Barton, R N E; Bouzouggar, A; Hogue, J T; Lee, S; Collcutt, S N; Ditchfield, P

    2013-09-01

    Recent genetic studies based on the distribution of mtDNA of haplogroup U6 have led to subtly different theories regarding the arrival of modern human populations in North Africa. One proposes that groups of the proto-U6 lineage spread from the Near East to North Africa around 40-45 ka (thousands of years ago), followed by some degree of regional continuity. Another envisages a westward human migration from the Near East, followed by further demographic expansion at ∼22 ka centred on the Maghreb and associated with a microlithic bladelet culture known as the Iberomaurusian. In evaluating these theories, we report on the results of new work on the Middle (MSA) and Later Stone (LSA) Age deposits at Taforalt Cave in Morocco. We present 54 AMS radiocarbon dates on bone and charcoals from a sequence of late MSA and LSA occupation levels of the cave. Using Bayesian modelling we show that an MSA non-Levallois flake industry was present until ∼24.5 ka Cal BP (calibrated years before present), followed by a gap in occupation and the subsequent appearance of an LSA Iberomaurusian industry from at least 21,160 Cal BP. The new dating offers fresh light on theories of continuity versus replacement of populations as presented by the genetic evidence. We examine the implications of these data for interpreting the first appearance of the LSA in the Maghreb and providing comparisons with other dated early blade and bladelet industries in North Africa. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. Radiocarbon dating for contributors

    International Nuclear Information System (INIS)

    Jansen, H.S.

    1984-06-01

    This report describes the radiocarbon facility at the Institute of Nuclear Sciences, and is written for potential contributors, current users, and for those who advise others. The report briefly outlines the principles and practices of C-14 dating; with emphasis on factors that enable contributors to judge whether C-14 work is appropriate, and to assist them with the procedures to be followed in order to get the best results. Age determinations, being the main requirements by contributors, have been discussed in detail

  19. Radiocarbon Dating of an Olive Tree Cross-Section: New Insights on Growth Patterns and Implications for Age Estimation of Olive Trees

    Directory of Open Access Journals (Sweden)

    Yael Ehrlich

    2017-11-01

    Full Text Available The age of living massive olive trees is often assumed to be between hundreds and even thousands of years. These estimations are usually based on the girth of the trunk and an extrapolation based on a theoretical annual growth rate. It is difficult to objectively verify these claims, as a monumental tree may not be cut down for analysis of its cross-section. In addition, the inner and oldest part of the trunk in olive trees usually rots, precluding the possibility of carting out radiocarbon analysis of material from the first years of life of the tree. In this work we present a cross-section of an olive tree, previously estimated to be hundreds of years old, which was cut down post-mortem in 2013. The cross-section was radiocarbon dated at numerous points following the natural growth pattern, which was made possible to observe by viewing the entire cross-section. Annual growth rate values were calculated and compared between different radii. The cross-section also revealed a nearly independent segment of growth, which would clearly offset any estimations based solely on girth calculations. Multiple piths were identified, indicating the beginning of branching within the trunk. Different radii were found to have comparable growth rates, resulting in similar estimates dating the piths to the 19th century. The estimated age of the piths represent a terminus ante quem for the age of the tree, as these are piths of separate branches. However, the tree is likely not many years older than the dated piths, and certainly not centuries older. The oldest radiocarbon-datable material in this cross-section was less than 200 years old, which is in agreement with most other radiocarbon dates of internal wood from living olive trees, rarely older than 300 years.

  20. Centuries of marine radiocarbon reservoir age variation within archaeological Mesodesma Donacium shells from Southern Peru

    Science.gov (United States)

    Jones, K.B.; Hodgins, G.W.L.; Etayo-Cadavid, M. F.; Andrus, C.F.T.; Sandweiss, D.H.

    2010-01-01

    Mollusk shells provide brief (Peru. The ranges in marine 14C ages (and thus R) from the 2 shells are 530 and 170 14C yr; R from individual aragonite samples spans 130 ?? 60 to 730 ?? 170 14C yr. This intrashell 14C variability suggests that 14C dating of small (time-slice much less than 1 yr) marine samples from a variable-R (i.e. variable-upwelling) environment may introduce centuries of chronometric uncertainty. ?? 2010 by the Arizona Board of Regents on behalf of the University of Arizona.

  1. Radiocarbon dates XXI

    International Nuclear Information System (INIS)

    Lowdon, J.A.; Blake, W. Jr.

    1981-01-01

    This list includes 105 radiocarbon age determinations on 104 geological samples made by the Radiocarbon Dating Laboratory. They are on samples from various areas as follows: Labrador Shelf (2); Newfoundland (12); Nova Scotia (2); New Brunswick (1); Quebec (3); Ontario (1); Manitoba (1); Alberta (2); British Columbia (15); Yukon Territory (35); Northwest Territories, Mainland (10); Northwest Territories, Arctic Archipelago (21). Details of background and standard for the 2 L and 5 L counters during the period from November 4, 1980 to October 31, 1981 are summarized in Tables 1 and 2; Table 3 gives the number of counts used to determine the average background and standard counting rates; and Table 4 lists the number of different background and standard gas preparations used for counting

  2. Maximum possible age of a petrel breeding colony near Punakaiki (South Island, New Zealand) from radiocarbon and stable isotope analysis of soil

    International Nuclear Information System (INIS)

    Hawke, D.J.

    2004-01-01

    The lifetime of individual petrel colonies is poorly known. This study used radiocarbon, 13 C, and 15 N analysis of soil to determine the maximum possible age of a colony presently occupied by Westland petrels. A sample of Ap horizon soil in lithic contact was selected for analysis, as soil least likely to have been redistributed by petrel burrowing. Chemical removal of mobile organic matter decreased δ 15 N from 14.0 permille (typical of breeding colony soils) to 6.1 permille (within the range of temperate forest soils without sea-bird breeding). δ 13 C values changed little, from -27.1 permille (untreated soil) to -28.4 permille (treated soil), and were typical of forest soil with with C 3 vegetation and no incorporation of marine C. Duplicate AMS radiocarbon analysis of treated sample yielded a combined conventional radiocarbon age of 864 ± 32 BP, indicating that sea-bird breeding could not have occurred at the site for more than 740-960 calendar years. Initial colony occupation may have occurred much later than this, and not been continuous. Sea bird species other than Westland petrels may also have used the site. (author). 30 refs., 2 figs

  3. Late-Holocene marine radiocarbon reservoir correction (ΔR) for the west coast of South Africa

    CSIR Research Space (South Africa)

    Dewar, G

    2012-06-01

    Full Text Available In order to calibrate radiocarbon ages based on samples with a marine carbon component it is important to know the marine carbon reservoir correction or ΔR value. This study measured the ΔR on both known-age pre-bomb marine shells and paired marine...

  4. Radiocarbon dating for the Quaternary scientist

    International Nuclear Information System (INIS)

    Pilcher, J.R.

    1991-01-01

    The accuracy of many conventional and accelerator mass spectrometry (AMS) radiocarbon dates is not adequate for the sort of questions now being asked in Quaternary studies. The need for, and effects of, radiocarbon calibration are discussed and guide-lines offered for the selection of a laboratory. High precision laboratories and the use of wiggle matching will go a long way to answering the critical questions of rates of change and durations of events in the Holocene. (Author)

  5. Radiocarbon dating of lowbog peat

    International Nuclear Information System (INIS)

    Trettin, R.; Hiller, A.; Mundel, G.

    1982-01-01

    Owing to complex formation conditions, the age determination of lowbog peat is generally considered difficult. Within the framework of peat profile investigations of the Havellaendisches Luch, factors that may exercise an influence on the radiocarbon concentration and disturb an ordered age sequence are discussed. With regard to lowbog peat, the interpretation of the sample material to be measured is of particular importance. (author)

  6. Estimating the age of Heliconius butterflies from calibrated photographs

    Directory of Open Access Journals (Sweden)

    Denise Dalbosco Dell’Aglio

    2017-09-01

    Full Text Available Mating behaviour and predation avoidance in Heliconius involve visual colour signals; however, there is considerable inter-individual phenotypic variation in the appearance of colours. In particular, the red pigment varies from bright crimson to faded red. It has been thought that this variation is primarily due to pigment fading with age, although this has not been explicitly tested. Previous studies have shown the importance of red patterns in mate choice and that birds and butterflies might perceive these small colour differences. Using digital photography and calibrated colour images, we investigated whether the hue variation in the forewing dorsal red band of Heliconius melpomene rosina corresponds with age. We found that the red hue and age were highly associated, suggesting that red colour can indeed be used as a proxy for age in the study of wild-caught butterflies.

  7. Otoliths as recorders of palaeoenvironments: comparison of radiocarbon age and isoleucine epimerization in Pleistocene golden perch 'Macquaria ambigua' otoliths from Willandra Lakes

    International Nuclear Information System (INIS)

    Kalish, J.M.; Pritchard, C.; Miller, G.H.; Rosewater, A.

    1997-01-01

    Fish otoliths form by the accretion of layers of calcium carbonate and organic-rich material that often form distinctive layers over time scales ranging from days to years. These layers are not resorbed during the life of the fish and have potential to provide data relevant to both the biology of the fish and the environment to which the fish has been exposed. Environmental variability based on otoliths can be estimated through measures of stable oxygen isotopes, trace elements, and the widths of both daily and annual increments. Although otoliths can be dated based on measurement of radiocarbon by accelerator mass spectrometry this method is relatively expensive. An alternative method for dating golden perch otoliths is based on measurements of isoleucine D/L ratios. Miller and Rosewater (1995) demonstrated that golden perch otoliths are near a perfect closed system for racemization and that otoliths have potential of dating surrounding sediments older than 100 ka. Despite the suitability of these structures for racemization measurements, many of collections of Pleistocene otoliths from Willandra Lakes are not appropriate for determination of sample age. Most otoliths sampled in the region have been derived from surface collections, while it is recommended that samples should have been buried at least 1 m during most of their history. Therefore, the majority of existing otolith collections are not appropriate for geochronology or palaeothermometry. Nevertheless, when used in conjunction with radiocarbon dates, racemization data may be of value in assessing the relationship among otoliths in an assemblage. Radiocarbon ages and isoleucine D/L ratios were determined for 30 otoliths collected from Willandra Lakes. The rostrum of each otolith was analysed for D/L ratios and a portion of the posterior of the same otolith was analysed for radiocarbon by accelerator mass spectrometry. Sample weights for both analyses ranged from 14.0 to 25.6 mg. The central portion of the

  8. 40Ar/39Ar age calibration against counted annuallayers

    DEFF Research Database (Denmark)

    Storey, Michael; Stecher, Ole

    2008-01-01

    The 40Ar/39Ar method, based on the decay of the naturally occurring radioactive isotope 40K, is capable of producing ages with precision better than ± 0.1 %. However, accuracy is limited to no better than 1 % mainly due to the relatively large uncertainty in the 40K decay constants. One approach...... worth exploring for an improved absolute age basis for the 40Ar/39Ar system is through cross-calibration with counted annual layers (e.g. tree rings, varves and ice cores). North Atlantic Ash Zone (NAAZ) II is found within the dated part of the annual Greenland ice core record. NAAZ II has been...... correlated to the Icelandic peralkaline rhyolitic Thorsmörk ignimbrite. We will present preliminary 40Ar/39Ar results on the age of this eruption...

  9. Calibrating recruitment estimates for mourning doves from harvest age ratios

    Science.gov (United States)

    Miller, David A.; Otis, David L.

    2010-01-01

    We examined results from the first national-scale effort to estimate mourning dove (Zenaida macroura) age ratios and developed a simple, efficient, and generalizable methodology for calibrating estimates. Our method predicted age classes of unknown-age wings based on backward projection of molt distributions from fall harvest collections to preseason banding. We estimated 1) the proportion of late-molt individuals in each age class, and 2) the molt rates of juvenile and adult birds. Monte Carlo simulations demonstrated our estimator was minimally biased. We estimated model parameters using 96,811 wings collected from hunters and 42,189 birds banded during preseason from 68 collection blocks in 22 states during the 2005–2007 hunting seasons. We also used estimates to derive a correction factor, based on latitude and longitude of samples, which can be applied to future surveys. We estimated differential vulnerability of age classes to harvest using data from banded birds and applied that to harvest age ratios to estimate population age ratios. Average, uncorrected age ratio of known-age wings for states that allow hunting was 2.25 (SD 0.85) juveniles:adult, and average, corrected ratio was 1.91 (SD 0.68), as determined from harvest age ratios from an independent sample of 41,084 wings collected from random hunters in 2007 and 2008. We used an independent estimate of differential vulnerability to adjust corrected harvest age ratios and estimated the average population age ratio as 1.45 (SD 0.52), a direct measure of recruitment rates. Average annual recruitment rates were highest east of the Mississippi River and in the northwestern United States, with lower rates between. Our results demonstrate a robust methodology for calibrating recruitment estimates for mourning doves and represent the first large-scale estimates of recruitment for the species. Our methods can be used by managers to correct future harvest survey data to generate recruitment estimates for use in

  10. Youngest reported radiocarbon age of a moa (Aves : Dinornithiformes) dated from a natural site in New Zealand

    International Nuclear Information System (INIS)

    Rawlence, N.J.; Cooper, A.

    2013-01-01

    The extinction date of the giant flightless New Zealand ratite bird, the crested moa (Pachyornis australis), is of considerable interest because the youngest verified remains are dated to the Pleistocene–Holocene transition c. 10,000 yr BP, which was characterised by severe climatic and habitat change, and are considerably earlier than the late Holocene extinctions of the other eight moa species. Analysis of a partial crested moa skeleton (NMNZ S23569) from Castle Keep Entrance, Bulmer Cave System, Mount Owen, South Island, generated a radiocarbon date of 564±26 yr BP (544-508 cal yr BP; 95.4% AD 1396-1442). As a result the Bulmer Cave specimen represents the youngest moa yet found from a natural site in New Zealand. Combined with additional crested moa remains dated to the late Holocene from Cheops Cave (Mount Arthur) and Magnesite Quarry (Cobb Valley), this indicates that crested moa did not go extinct during the Pleistocene–Holocene transition but survived until after Polynesian colonisation in c. AD 1280. The new radiocarbon dates reported here have important implications for the timing of moa extinction and the late survival of moa in alpine areas of New Zealand. (author). 47 refs., 2 figs., 1 tab.

  11. Chronometric investigations of the Middle to Upper Paleolithic transition in the Zagros Mountains using AMS radiocarbon dating and Bayesian age modelling.

    Science.gov (United States)

    Becerra-Valdivia, Lorena; Douka, Katerina; Comeskey, Daniel; Bazgir, Behrouz; Conard, Nicholas J; Marean, Curtis W; Ollé, Andreu; Otte, Marcel; Tumung, Laxmi; Zeidi, Mohsen; Higham, Thomas F G

    2017-08-01

    The Middle to Upper Paleolithic transition is often linked with a bio-cultural shift involving the dispersal of modern humans outside of Africa, the concomitant replacement of Neanderthals across Eurasia, and the emergence of new technological traditions. The Zagros Mountains region assumes importance in discussions concerning this period as its geographic location is central to all pertinent hominin migration areas, pointing to both east and west. As such, establishing a reliable chronology in the Zagros Mountains is crucial to our understanding of these biological and cultural developments. Political circumstance, coupled with the poor preservation of organic material, has meant that a clear chronological definition of the Middle to Upper Paleolithic transition for the Zagros Mountains region has not yet been achieved. To improve this situation, we have obtained new archaeological samples for AMS radiocarbon dating from three sites: Kobeh Cave, Kaldar Cave, and Ghār-e Boof (Iran). In addition, we have statistically modelled previously published radiocarbon determinations for Yafteh Cave (Iran) and Shanidar Cave (Iraqi Kurdistan), to improve their chronological resolution and enable us to compare the results with the new dataset. Bayesian modelling results suggest that the onset of the Upper Paleolithic in the Zagros Mountains dates to 45,000-40,250 cal BP (68.2% probability). Further chronometric data are required to improve the precision of this age range. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Effect of ageing on the calibration of ballistic gelatin.

    Science.gov (United States)

    Guey, Jason; Rodrigues, S; Pullen, A; Shaw, B; Kieser, D C

    2018-02-27

    Ballistic gelatin is commonly used as a validated surrogate for soft tissue during terminal ballistic testing. However, the effect of a delay between production and testing of a gelatin mould remains unknown. The aim of this study was to determine any potential effects of ageing on ballistic gelatin. Depth of penetration (DoP) of 4.5 mm spherical fragment simulating projectiles was ascertained using mixtures of 10%, 11.25% and 20% Type A 250 Bloom ballistic gelatin. Testing was performed daily for 5 days using velocities between 75 and 210 m/s. DoP at day 5 was statistically compared with day 1, and net mass change was recorded daily. No significant difference was found for DoP observed with time in any of the samples (P>0.05). Spearman correlation was excellent in all moulds. The moulds with known standard calibrations remained in calibration throughout the study period. Mass loss of less than 1% was noted in all samples. Mass loss was the only quantifiable measure of changes in the blocks with time, but did not correlate with any changes in DoP. This may provide reassurance when undertaking such testing that an inadvertent delay will not significantly alter the penetration properties of the mould. Future research is recommended to determine any potential effect on the mechanical properties of gelatin at higher velocity impacts and whether the calibration corresponds to an adequate simulation under such conditions. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  13. The 3.6 ka Aniakchak tephra in the Arctic Ocean: a constraint on the Holocene radiocarbon reservoir age in the Chukchi Sea

    Science.gov (United States)

    Pearce, Christof; Varhelyi, Aron; Wastegård, Stefan; Muschitiello, Francesco; Barrientos, Natalia; O'Regan, Matt; Cronin, Thomas M.; Gemery, Laura; Semiletov, Igor; Backman, Jan; Jakobsson, Martin

    2017-04-01

    The caldera-forming eruption of the Aniakchak volcano in the Aleutian Range on the Alaskan Peninsula at 3.6 cal kyr BP was one of the largest Holocene eruptions worldwide. The resulting ash is found as a visible sediment layer in several Alaskan sites and as a cryptotephra on Newfoundland and Greenland. This large geographic distribution, combined with the fact that the eruption is relatively well constrained in time using radiocarbon dating of lake sediments and annual layer counts in ice cores, makes it an excellent stratigraphic marker for dating and correlating mid-late Holocene sediment and paleoclimate records. This study presents the outcome of a targeted search for the Aniakchak tephra in a marine sediment core from the Arctic Ocean, namely Core SWERUS-L2-2-PC1 (2PC), raised from 57 m water depth in Herald Canyon, western Chukchi Sea. High concentrations of tephra shards, with a geochemical signature matching that of Aniakchak ash, were observed across a more than 1.5 m long sediment sequence. Since the primary input of volcanic ash is through atmospheric transport, and assuming that bioturbation can account for mixing up to ca. 10 cm of the marine sediment deposited at the coring site, the broad signal is interpreted as sustained reworking at the sediment source input. The isochron is therefore placed at the base of the sudden increase in tephra concentrations rather than at the maximum concentration. This interpretation of major reworking is strengthened by analysis of grain size distribution which points to ice rafting as an important secondary transport mechanism of volcanic ash. Combined with radiocarbon dates on mollusks in the same sediment core, the volcanic marker is used to calculate a marine radiocarbon reservoir age offset ΔR = 477 ± 60 years. This relatively high value may be explained by the major influence of typically carbon-old Pacific waters, and it agrees well with recent estimates of ΔR along the northwest Alaskan coast, possibly

  14. Calibration

    International Nuclear Information System (INIS)

    Greacen, E.L.; Correll, R.L.; Cunningham, R.B.; Johns, G.G.; Nicolls, K.D.

    1981-01-01

    Procedures common to different methods of calibration of neutron moisture meters are outlined and laboratory and field calibration methods compared. Gross errors which arise from faulty calibration techniques are described. The count rate can be affected by the dry bulk density of the soil, the volumetric content of constitutional hydrogen and other chemical components of the soil and soil solution. Calibration is further complicated by the fact that the neutron meter responds more strongly to the soil properties close to the detector and source. The differences in slope of calibration curves for different soils can be as much as 40%

  15. Identifying sources of dissolved organic carbon in agriculturally dominated rivers using radiocarbon age dating: Sacramento-San Joaquin River Basin, California

    Science.gov (United States)

    Sickman, James O.; DiGiorgio, Carol L.; Davisson, M. Lee; Lucero, Delores M.; Bergamaschi, Brian A.

    2010-01-01

    We used radiocarbon measurements of dissolved organic carbon (DOC) to resolve sources of riverine carbon within agriculturally dominated landscapes in California. During 2003 and 2004, average Δ14C for DOC was −254‰ in agricultural drains in the Sacramento–San Joaquin Delta, −218‰ in the San Joaquin River, −175‰ in the California State Water Project and −152‰ in the Sacramento River. The age of bulk DOC transiting the rivers of California’s Central Valley is the oldest reported for large rivers and suggests wide-spread loss of soil organic matter caused by agriculture and urbanization. Using DAX 8 adsorbent, we isolated and measured 14C concentrations in hydrophobic acid fractions (HPOA); river samples showed evidence of bomb-pulse carbon with average Δ14C of 91 and 76‰ for the San Joaquin and Sacramento Rivers, respectively, with older HPOA, −204‰, observed in agricultural drains. An operationally defined non-HPOA fraction of DOC was observed in the San Joaquin River with seasonally computed Δ14C values of between −275 and −687‰; the source of this aged material was hypothesized to be physically protected organic-matter in high clay-content soils and agrochemicals (i.e., radiocarbon-dead material) applied to farmlands. Mixing models suggest that the Sacramento River contributes about 50% of the DOC load in the California State Water Project, and agricultural drains contribute approximately one-third of the load. In contrast to studies showing stabilization of soil carbon pools within one or two decades following land conversion, sustained loss of soil organic matter, occurring many decades after the initial agricultural-land conversion, was observed in California’s Central Valley.

  16. Progress in radiocarbon dating

    International Nuclear Information System (INIS)

    Hedges, R.E.M.

    1985-01-01

    The article concerns radiocarbon dating, the most important method for dating in archaeology. The principles and practice of the dating method are described. Recent developments in radiocarbon dating due to technical advances, are discussed, and include radiometric counting of small samples and accelerator mass spectrometry. Carbon isotopes and the environment are also discussed. (U.K.)

  17. Accuracy of radiocarbon analyses at ANTARES

    Energy Technology Data Exchange (ETDEWEB)

    Lawson, E M; Fink, D; Hotchkis, M; Hua, Q; Jacobsen, G; Smith, A M; Tuniz, C [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia)

    1997-12-31

    Accuracy in Accelerator Mass Spectroscopy (AMS) measurements, as distinct from precision, requires the application of a number of corrections. Most of these are well known except in extreme circumstances and AMS can deliver radiocarbon results which are both precise and accurate in the 0.5 to 1.0% range. The corrections involved in obtaining final radiocarbon ages are discussed. 3 refs., 1 tab.

  18. Accuracy of radiocarbon analyses at ANTARES

    Energy Technology Data Exchange (ETDEWEB)

    Lawson, E.M.; Fink, D.; Hotchkis, M.; Hua, Q.; Jacobsen, G.; Smith, A.M.; Tuniz, C. [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia)

    1996-12-31

    Accuracy in Accelerator Mass Spectroscopy (AMS) measurements, as distinct from precision, requires the application of a number of corrections. Most of these are well known except in extreme circumstances and AMS can deliver radiocarbon results which are both precise and accurate in the 0.5 to 1.0% range. The corrections involved in obtaining final radiocarbon ages are discussed. 3 refs., 1 tab.

  19. High-precision radiocarbon chronometry of ancient Egypt, and comparisons with Nubia, Palestine and Mesopotamia

    Energy Technology Data Exchange (ETDEWEB)

    Hassan, F A; Robinson, S W

    1987-03-01

    The use of radiocarbon age measurements in historical chronology is examined for ancient Egypt and neighbouring regions. A methodology is presented aimed at improving the reliability and precision of radiocarbon age determinations.

  20. The feasibility of bomb radiocarbon analysis to support an age-at-length relationship for red abalone, Haliotis rufescens Swainson in northern California

    Energy Technology Data Exchange (ETDEWEB)

    Leaf, R T; Andrews, A H; Cailliet, G M; Brown, T A

    2009-01-07

    Analysis of bomb generated radiocarbon ({sup 14}C) changes in a red abalone, Haliotis rufescens Swainson shell was used to investigate age-at-length relationships derived from data from a previous multi-year, multi-site tag-recapture study. Shell carbonate was extracted from four successive growth trajectory locations in a single shell with a length of 251 mm MSL. Extraction locations were based on VBGF predictions and chosen to span the initial rise of the {sup 14}C-bomb pulse that is known to have occurred in surface ocean waters during 1958 {+-} 1 y in the northeast Pacific. The close temporal correspondence of the red abalone sample series to regional {Delta}{sup 14}C records demonstrated the utility of the technique for validating age-at-length relationships for the red abalone. The findings provided support for a mean VBGF derived age of 32 y (range 30 to 33 y) for the specimen; however, the analysis of {sup 14}C data indicated that the specimen could be older.

  1. Moving beyond the age-depth model paradigm in deep-sea palaeoclimate archives: dual radiocarbon and stable isotope analysis on single foraminifera

    Science.gov (United States)

    Lougheed, Bryan C.; Metcalfe, Brett; Ninnemann, Ulysses S.; Wacker, Lukas

    2018-04-01

    Late-glacial palaeoclimate reconstructions from deep-sea sediment archives provide valuable insight into past rapid changes in ocean chemistry. Unfortunately, only a small proportion of the ocean floor with sufficiently high sediment accumulation rate (SAR) is suitable for such reconstructions using the long-standing age-depth model approach. We employ ultra-small radiocarbon (14C) dating on single microscopic foraminifera to demonstrate that the long-standing age-depth model method conceals large age uncertainties caused by post-depositional sediment mixing, meaning that existing studies may underestimate total geochronological error. We find that the age-depth distribution of our 14C-dated single foraminifera is in good agreement with existing bioturbation models only after one takes the possibility of Zoophycos burrowing into account. To overcome the problems associated with the age-depth paradigm, we use the first ever dual 14C and stable isotope (δ18O and δ13C) analysis on single microscopic foraminifera to produce a palaeoclimate time series independent of the age-depth paradigm. This new state of the art essentially decouples single foraminifera from the age-depth paradigm to provide multiple floating, temporal snapshots of ocean chemistry, thus allowing for the successful extraction of temporally accurate palaeoclimate data from low-SAR deep-sea archives. This new method can address large geographical gaps in late-glacial benthic palaeoceanographic reconstructions by opening up vast areas of previously disregarded, low-SAR deep-sea archives to research, which will lead to an improved understanding of the global interaction between oceans and climate.

  2. Fish age validation study with bomb-produced radiocarbon (14C) conducted on yellowfin sole (Limanda aspera) and northern rockfish (Sebastes polyspinis) by Alaska Fisheries Science Center, Fisheries Monitoring and Analysis division from 1987-01-01 to 2004-01-01 (NCEI Accession 0134853)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Fish age validation with bomb-produced radiocarbon (14C) requires a known-age Delta14C reference chronology spanning the era of a marine increase in bomb-produced...

  3. Radiocarbon dating of a Japanese ancient document 'Minamoto no Yoritomo Sodehan Migyosho' by AMS

    International Nuclear Information System (INIS)

    Oda, H.; Nakaura, T.; Akiyama, M.

    2005-01-01

    In this study, radiocarbon age of a Japanese ancient document 'Minamoto no Yoritomo Sodehan Migyosho' was measured by AMS. The purpose of this study is to judge whether the document is genuine or not. The document descended to the Matsugi family which had controlled the craftsmen of metal casting. The document has a description of the written age, AD1189. The content of the document is about the formal recognition of their authority over the craftsmen by Minamoto no Yoritomo who established the first military government in AD1192. This document is written on a slightly-blackish-paper sheet called Shukushi. Shukushi paper sheets had been commonly used for the official documents of the Emperor. Therefore, if the document was really issued by Minamoto no Yoritomo, it can be a sole example as the document of warrior class among the extant Shukushi paper. The paleographical views, however, suggested that the document may be a counterfeit written in several centuries later. Japanese paper fragment is a suitable sample for radiocarbon dating because there is little discrepancy between the calibrated radiocarbon age and the written age. The calibrated radiocarbon age of 'Minamoto no Yoritomo Sodehan Migyosho' indicated the 16th century or the first half of the 17th century. This age corresponds to the period when the ancestor of Matsugi family appeared in Japanese history. This result shows that the document was forged in the Warring State Period for the legitimacy of their control over the craftsmen. The Shukusi used for the counterfeit document of warrior class is the outcome of the forger's misunderstanding that Shukushi paper should be used for the important documents.

  4. AMS radiocarbon investigation of the African baobab: Searching for the oldest tree

    Energy Technology Data Exchange (ETDEWEB)

    Patrut, Adrian, E-mail: apatrut@gmail.com [Babes-Bolyai University, Department of Chemistry, Arany Janos 11, 400028 Cluj-Napoca (Romania); Reden, Karl F. von [Woods Hole Oceanographic Institution, Department of Geology and Geophysics, NOSAMS Facility, 360 Woods Hole Rd., Mailstop 8, Woods Hole, MA 02543 (United States); Mayne, Diana H. [Baobab Trust, P.O. Box 1566, Parklands 2121, Johannesburg (South Africa); Lowy, Daniel A. [FlexEl, LLC, 387 Technology Drive, College Park, MD 20742 (United States); Patrut, Roxana T. [Babes-Bolyai University, Department of Biology and Geology, Gh. Bilascu 44, 400015 Cluj-Napoca (Romania)

    2013-01-15

    The Glencoe baobab, a very large specimen from South Africa, split twice in 2009. Several wood samples were collected from the eastern cavity, from the outer part of the main section and also from the largest broken segment which was connected to this section. These wood samples were processed and investigated by AMS radiocarbon dating. The radiocarbon date of the oldest sample was found to be 1838 {+-} 21 BP, which corresponds to a calibrated age of 1835 {+-} 40 years. Thus, the Glencoe baobab becomes the oldest dated baobab and also the oldest angiosperm tree with accurate dating results. The distribution of dating results revealed that the Glencoe baobab is a multi-generation tree, with several standing or collapsed and partially fused stems, showing different ages.

  5. The freshwater reservoir effect in radiocarbon dating

    DEFF Research Database (Denmark)

    Philippsen, Bente

    case studies will show the degree of variability of the freshwater reservoir effect over short and long timescales. Radiocarbon dating of recent water samples, aquatic plants and animals, shows that age differences of up to 2000 years can occur within one river. In the Limfjord, freshwater influence......The freshwater reservoir effect can result in too high radiocarbon ages of samples from lakes and rivers, including the bones of people whose subsistence was based on freshwater fish, and pottery in which fish was cooked. In my talk, I will explain the causes and consequences of this effect. Two...... caused reservoir ages to vary between 250 and 700 years during the period 5400 BC - AD 700. Finally, I will discuss the implications of the freshwater reservoir effect for radiocarbon dating of Mesolithic pottery from inland sites of the Ertebølle culture in Northern Germany....

  6. Radiocarbon determination of particulate organic carbon in glacier ice from the Grenzgletscher (Monte Rosa)

    International Nuclear Information System (INIS)

    Steier, P.; Drosg, R.; Kutschera, W.; Wild, E.M.; Fedi, M.; Schock, M.; Wagenbach, D.

    2005-01-01

    Full text: Dating ice cores from cold glaciers via radiocarbon is still an unsolved problem. This work describes our approach towards extraction and AMS radiocarbon dating of the particulate organic carbon (POC) fraction in ice samples at VERA (Vienna Environmental Research Accelerator). First measurements were performed on 1 snow and 11 ice samples from Gorner Glacier and Colle Gnifetti in the Monte Rosa Mountain region (Swiss Alps). The sample masses used were between 0.3 kg and 1.4 kg ice yielding between 18 μg and 307 μg carbon as POC. The carbon contamination introduced during the sample processing varied between 9 μg and 33 μg C and originates mainly from the quartz filters and the rinsing liquids used. Minimum sample sizes for successful graphitization of carbon dioxide in our laboratory have been reduced to less than 10 μg carbon. The background in the graphitization process is approximately 0.5 μg carbon of 40 pMC. Scatter and outliers in the radiocarbon data suggest that presently a single radiocarbon date of glacial POC has limited significance. For the set of 11 ice samples, a calibrated age of 2100 BC to 900 AD (95% confidence level) is obtained. (author)

  7. Radiocarbon dating of a pine tree (Pinus densiflora) from Yeongwol, Korea

    International Nuclear Information System (INIS)

    Kim, C.H.; Lee, J.H.; Kang, J.; Song, S.; Yun, M.H.; Kim, J.C.

    2015-01-01

    We report the results of the dating of a pine tree (Pinus densiflora) from Yeongwol, Korea. The age of the tree was estimated to be in the range of hundreds of years, however, the tree had been broken by a strong wind in March 2010 and now only the stump of the tree is left. At the time of sampling in 2014, there were several decayed parts in the stump, so using the usual dendrochronological method (i.e. ring counting) for dating was difficult. However, we found a small wood sample with tree rings near the center of the stump that could be used for radiocarbon wiggle-match dating. Radiocarbon dates were determined using Accelerator mass spectrometry (AMS). The IntCal13 curve was used to calibrate the radiocarbon dates, and the wiggle matching technique was used to reduce the error of the calibrated ages. Based on the dating results, we suggest that the pine tree is approximately 300 years or older.

  8. Radiocarbon dating of a pine tree (Pinus densiflora) from Yeongwol, Korea

    Energy Technology Data Exchange (ETDEWEB)

    Kim, C.H.; Lee, J.H.; Kang, J.; Song, S.; Yun, M.H. [AMS Lab., NCIRF, Seoul National University, Seoul 151-742 (Korea, Republic of); Kim, J.C. [Dept. of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of)

    2015-10-15

    We report the results of the dating of a pine tree (Pinus densiflora) from Yeongwol, Korea. The age of the tree was estimated to be in the range of hundreds of years, however, the tree had been broken by a strong wind in March 2010 and now only the stump of the tree is left. At the time of sampling in 2014, there were several decayed parts in the stump, so using the usual dendrochronological method (i.e. ring counting) for dating was difficult. However, we found a small wood sample with tree rings near the center of the stump that could be used for radiocarbon wiggle-match dating. Radiocarbon dates were determined using Accelerator mass spectrometry (AMS). The IntCal13 curve was used to calibrate the radiocarbon dates, and the wiggle matching technique was used to reduce the error of the calibrated ages. Based on the dating results, we suggest that the pine tree is approximately 300 years or older.

  9. Radiocarbon dating of a pine tree (Pinus densiflora) from Yeongwol, Korea

    Science.gov (United States)

    Kim, C. H.; Lee, J. H.; Kang, J.; Song, S.; Yun, M. H.; Kim, J. C.

    2015-10-01

    We report the results of the dating of a pine tree (Pinus densiflora) from Yeongwol, Korea. The age of the tree was estimated to be in the range of hundreds of years, however, the tree had been broken by a strong wind in March 2010 and now only the stump of the tree is left. At the time of sampling in 2014, there were several decayed parts in the stump, so using the usual dendrochronological method (i.e. ring counting) for dating was difficult. However, we found a small wood sample with tree rings near the center of the stump that could be used for radiocarbon wiggle-match dating. Radiocarbon dates were determined using Accelerator mass spectrometry (AMS). The IntCal13 curve was used to calibrate the radiocarbon dates, and the wiggle matching technique was used to reduce the error of the calibrated ages. Based on the dating results, we suggest that the pine tree is approximately 300 years or older.

  10. AMS Radiocarbon Dating of Large Za Baobabs (Adansonia za) of Madagascar.

    Science.gov (United States)

    Patrut, Adrian; Patrut, Roxana T; Danthu, Pascal; Leong Pock-Tsy, Jean-Michel; Rakosy, Laszlo; Lowy, Daniel A; von Reden, Karl F

    2016-01-01

    The article reports the radiocarbon investigation of Anzapalivoro, the largest za baobab (Adansonia za) specimen of Madagascar and of another za, namely the Big cistern baobab. Several wood samples collected from the large inner cavity and from the outer part/exterior of the tree were investigated by AMS (accelerator mass spectrometry) radiocarbon dating. For samples collected from the cavity walls, the age values increase with the distance into the wood up to a point of maximum age, after which the values decrease toward the outer part. This anomaly of age sequences indicates that the inner cavity of Anzapalivoro is a false cavity, practically an empty space between several fused stems disposed in a ring-shaped structure. The radiocarbon date of the oldest sample was 780 ± 30 bp, which corresponds to a calibrated age of around 735 yr. Dating results indicate that Anzapalivoro has a closed ring-shaped structure, which consists of 5 fused stems that close a false cavity. The oldest part of the biggest za baobab has a calculated age of 900 years. We also disclose results of the investigation of a second za baobab, the Big cistern baobab, which was hollowed out for water storage. This specimen, which consists of 4 fused stems, was found to be around 260 years old.

  11. AMS Radiocarbon Dating of Large Za Baobabs (Adansonia za of Madagascar.

    Directory of Open Access Journals (Sweden)

    Adrian Patrut

    Full Text Available The article reports the radiocarbon investigation of Anzapalivoro, the largest za baobab (Adansonia za specimen of Madagascar and of another za, namely the Big cistern baobab. Several wood samples collected from the large inner cavity and from the outer part/exterior of the tree were investigated by AMS (accelerator mass spectrometry radiocarbon dating. For samples collected from the cavity walls, the age values increase with the distance into the wood up to a point of maximum age, after which the values decrease toward the outer part. This anomaly of age sequences indicates that the inner cavity of Anzapalivoro is a false cavity, practically an empty space between several fused stems disposed in a ring-shaped structure. The radiocarbon date of the oldest sample was 780 ± 30 bp, which corresponds to a calibrated age of around 735 yr. Dating results indicate that Anzapalivoro has a closed ring-shaped structure, which consists of 5 fused stems that close a false cavity. The oldest part of the biggest za baobab has a calculated age of 900 years. We also disclose results of the investigation of a second za baobab, the Big cistern baobab, which was hollowed out for water storage. This specimen, which consists of 4 fused stems, was found to be around 260 years old.

  12. History of radiocarbon dating

    Energy Technology Data Exchange (ETDEWEB)

    Libby, W F [Department of Chemistry and Institute of Geophysics, University of California, Los Angeles, CA (United States)

    1967-08-15

    The development is traced of radiocarbon dating from its birth in curiosity regarding the effects of cosmic radiation on Earth. Discussed in historical perspective are: the significance of the initial measurements in determining the course of developments; the advent of the low-level counting technique; attempts to avoid low-level counting by the use of isotopic enrichment; the gradual appearance of the environmental effect due to the combustion of fossil fuel (Suess effect); recognition of the atmosphere ocean barrier for carbon dioxide exchange; detailed understanding of the mixing mechanism from the study of fallout radiocarbon; determination of the new half-life; indexing and the assimilation problem for the massive accumulation of dates; and the proliferation of measurement techniques and the impact of archaeological insight on the validity of radiocarbon dates. (author)

  13. Analysis of radiocarbon dates of an archaeological site in the Russian Far East: The marine reservoir effect as seen on charred remains on pottery

    International Nuclear Information System (INIS)

    Kunikita, Dai; Yoshida, Kunio; Miyazaki, Yumiko; Saito, Keita; Endo, Aya; Matsuzaki, Hiroyuki; Ito, Shinji; Kobayashi, Tatsuo; Fujimoto, Tsuyoshi; Kuznetsov, A.M.; Krupyanko, A.A.; Tabarev, A.M.

    2007-01-01

    In order to obtain precise and accurate calibrated radiocarbon chronologies for archaeological sites, it is necessary to determine the provenance of the carbon material being dated. Of particular note is determining the provenance and radiocarbon age of charcoal remains on pottery. In this context, we discuss the decipherment of dates on the Ustinovka-8 site in the Russian Far East. Using δ 13 C, δ 15 N and C:N it is possible to ascribe charcoal provenance to terrestrial and marine origins. Our data show radiocarbon age difference that are clearly associated with carbon origin, and a maximum estimated ΔR of approximately 400 years during the Zaisanovskaya culture, 4400 cal BP. A combination of pottery analysis and 14 C dating at this site determined the Zaisanovskaya cultural period to be 4000-5000 cal BP, the Boismanskaya and the Late Rudninskaya cultural period 5800-6500 cal BP, and the Early Rudninskaya cultural period of 6800-7100 cal BP

  14. Growth process in an elephant tusk: Age estimations based on temporal variations in bomb-radiocarbon content

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, Toshio, E-mail: nakamura@nendai.nagoya-u.ac.jp [Center for Chronological Research, Nagoya University, Chikusa, Nagoya, Aichi 464-8602 (Japan); Koike, Hiroko [Kyushu University Museum, Kyushu University, Hakozaki, Fukuoka, Fukuoka 814-0180 (Japan); Aizawa, Jun; Okuno, Mitsuru [Department of Earth System Science, Faculty of Science, Fukuoka University, 8-19-1 Nanakuma, Jonan-ku, Fukuoka, Fukuoka 814-0180 (Japan)

    2015-10-15

    In this study, {sup 14}C analysis by accelerator mass spectrometry (AMS) was applied to age estimation based on temporal variations in bomb-produced-{sup 14}C contents of a full elephant tusk registered at Kyushu University. The tusk measured 175 cm long and 13.8 cm in diameter at the root. Thirty tusk-fragment samples were used for {sup 14}C analysis with AMS to estimate the formation ages of different positions according to catalogued global {sup 14}C contents (F{sup 14}C). The F{sup 14}C value of the tip of the tusk suggested that the elephant was born around 1980, while that of the root suggested death around 1994, a lifespan of at least 14 years, rather shorter period than the average lifetime of an elephant (ca. 80 years). In addition, the F{sup 14}C values of fragments collected along a cross-sectional line suggested that the outer part of the tusk formed first with inner parts being deposited gradually with growth.

  15. Compound-Specific Radiocarbon Dating Reveals the Age Distribution of Plant-Wax Biomarkers Exported to the Bengal Fan

    Science.gov (United States)

    Galy, V.; French, K. L.; Hein, C. J.; Haghipour, N.; Wacker, L.; Kudrass, H.; Eglinton, T. I.

    2017-12-01

    The stable isotope composition of leaf-wax compounds preserved in lacustrine and marine sediments has been widely used to reconstruct terrestrial paleo-environments. However, the timescales of plant-wax storage in continental reservoirs before riverine export are not well known, representing a key uncertainty in paleo-environment studies. We couple numerical models with bulk and leaf-wax fatty acid organic 13C and 14C signatures hosted in a high-deposition-rate sediment core from the Bengal shelf canyon in order to estimate storage timescales within the Ganges-Brahmaputra catchment area. The fatty acid 14C record reveals a muted nuclear weapons bomb spike, requiring that the Ganges-Brahmaputra river system exports a mixture of young and old (pre-aged) leaf-wax compounds. According to numerical simulations, 79-83% of the leaf-wax fatty acids in this core are sourced from continental reservoirs that store organic carbon on an average of 1000-1200 calendar years, while the remainder has an average age of 15 years. These results demonstrate that a majority of the leaf-wax compounds produced in the Ganges-Brahmaputra river basin was stored in soils, floodplains, and wetlands prior to its export to the Bengal Fan. We will discuss the implications of these findings for plant-wax based paleoenvironmental records.

  16. Growth process in an elephant tusk: Age estimations based on temporal variations in bomb-radiocarbon content

    International Nuclear Information System (INIS)

    Nakamura, Toshio; Koike, Hiroko; Aizawa, Jun; Okuno, Mitsuru

    2015-01-01

    In this study, "1"4C analysis by accelerator mass spectrometry (AMS) was applied to age estimation based on temporal variations in bomb-produced-"1"4C contents of a full elephant tusk registered at Kyushu University. The tusk measured 175 cm long and 13.8 cm in diameter at the root. Thirty tusk-fragment samples were used for "1"4C analysis with AMS to estimate the formation ages of different positions according to catalogued global "1"4C contents (F"1"4C). The F"1"4C value of the tip of the tusk suggested that the elephant was born around 1980, while that of the root suggested death around 1994, a lifespan of at least 14 years, rather shorter period than the average lifetime of an elephant (ca. 80 years). In addition, the F"1"4C values of fragments collected along a cross-sectional line suggested that the outer part of the tusk formed first with inner parts being deposited gradually with growth.

  17. Dating stratified settlement sites at Kom K and Kom W: Fifth millennium BCE radiocarbon ages for the Fayum Neolithic

    Energy Technology Data Exchange (ETDEWEB)

    Wendrich, W. [Department of Near Eastern Languages and Cultures, University of California, Los Angeles, CA 92521 (United States); Cotsen Institute of Archaeology, University of California, Los Angeles, CA 92521 (United States); Taylor, R.E., E-mail: retaylor@ucr.ed [Department of Anthropology, University of California, Riverside, Riverside, CA 92521 (United States); Cotsen Institute of Archaeology, University of California, Los Angeles, CA 92521 (United States); Keck Carbon Cycle Accelerator Mass Spectrometry Laboratory, Department of Earth System Science, University of California, Irvine, CA 92697 (United States); Southon, J. [Keck Carbon Cycle Accelerator Mass Spectrometry Laboratory, Department of Earth System Science, University of California, Irvine, CA 92697 (United States)

    2010-04-15

    The earliest evidence of the use of domesticated plants, a traditional hallmark of Neolithic societies in the ancient Near East, first appears in Egypt in archaeological sites in the Fayum depression. Due to wind erosion often resulting in deflation of sediments in this region, stratified sites containing organic materials are rare and the depositional contexts of some earlier {sup 14}C measurements on Fayum Neolithic materials are not precisely documented. We report the results of 29 AMS-based {sup 14}C determinations on charcoal recovered from stratified contexts in two Fayum Neolithic village sites, Kom K and Kom W. These data assign a mid-5th millennium BCE age to these sites and permit an estimate of the length of their occupation to be approximately three centuries.

  18. Dating stratified settlement sites at Kom K and Kom W: Fifth millennium BCE radiocarbon ages for the Fayum Neolithic

    International Nuclear Information System (INIS)

    Wendrich, W.; Taylor, R.E.; Southon, J.

    2010-01-01

    The earliest evidence of the use of domesticated plants, a traditional hallmark of Neolithic societies in the ancient Near East, first appears in Egypt in archaeological sites in the Fayum depression. Due to wind erosion often resulting in deflation of sediments in this region, stratified sites containing organic materials are rare and the depositional contexts of some earlier 14 C measurements on Fayum Neolithic materials are not precisely documented. We report the results of 29 AMS-based 14 C determinations on charcoal recovered from stratified contexts in two Fayum Neolithic village sites, Kom K and Kom W. These data assign a mid-5th millennium BCE age to these sites and permit an estimate of the length of their occupation to be approximately three centuries.

  19. New age estimations for the western outer city wall of ancient Tayma (NW Saudi Arabia) based on OSL and radiocarbon data and geomorphologic evidence

    Science.gov (United States)

    Engel, M.; Klasen, N.; Brückner, H.; Eichmann, R.; Hausleiter, A.; Al-Najem, M. H.; Al-Said, S. F.; Schneider, P. I.

    2009-04-01

    Since 2004 tremendous progress has been achieved in deciphering the cultural genesis of the Tayma oasis (NW Saudi Arabia), due to the joint investigations of the German Archaeological Institute Berlin (DAI), the General Commission for Tourism and Antiquities, Kingdom of Saudi Arabia, and the Department of Archaeology and Epigraphy, King Saud University Riyadh. Nevertheless, archaeological research is still suffering from a lacking locally-based absolute chronology of buildings. The pattern of ancient constructions at Tayma is dominated by a prominent city wall system surrounding the ancient town center (Qraya) and stretching 15 km around the oasis. Its internal structure indicates several building periods, i.e. phases of wall modification or extension of the entire system. So far, according to silex and carnelian fragments included in the mud bricks and a previous 14C age of charcoal remains from the central excavation district (wall section at Area A), an initial construction date of the wall between the late 3rd and the early 2nd millennium BC seemed likely. At the excavated western outer city wall a new systematic dating approach - combining the optically stimulated luminescence (OSL) and 14C methods - has been applied to generate a reliable age for the oldest branch of the wall system which nowadays is covered by aeolian sand. The dune deposit is genetically related to the existence of the wall and, therefore, dating its accumulation provides termini ante quem for the construction of the wall. Five OSL dates were generated from the dune deposit providing ages between 4,900 and 3,500 yrs. Two radiocarbon ages support the dating sequence and also contribute to its consistency. By combining the results with geomorphologic evidence we draw the following conclusions: Initial settlement activities at Qraya were accompanied by a regulation of wadi dynamics and the construction of the outer city wall, indicated by the abrupt boundary between the pre-settlement alluvial

  20. Spatial and temporal variation of radiocarbon in tree rings - some preliminary results

    International Nuclear Information System (INIS)

    Higham, T.F.G.; Hogg, A.G.; McCormac, F.G.; Baillie, M.G.L.; Brown, D.; Palmer, J.G.; Xiong, L.

    1997-01-01

    A number of researchers have identified a measurable difference between the 14 C activities of tree rings of identical dendochronological age between the Northern and the Southern Hemispheres. It is also acknowledged that there is an urgent need for new high precision Δ 14 C data from tree rings in both Hemispheres to help resolve the questions relating to the magnitude and cause of the locality and temporal dependence of the Δ 14 C record, to provide a reliable Southern Hemisphere calibration curve and to throw light upon the 1986 and 1993 Calibration data set discrepancies. In this paper, the authors present the research design of a project to investigate these critical issues in radiocarbon age calibration and describe the preliminary results

  1. Spatial and temporal variation of radiocarbon in tree rings - some preliminary results

    Energy Technology Data Exchange (ETDEWEB)

    Higham, T.F.G.; Hogg, A.G. [Waikato Univ., Hamilton (New Zealand); McCormac, F.G.; Baillie, M.G.L.; Brown, D. [Queens`s University, Belfast, (Ireland). School of Geosciences; Palmer, J.G.; Xiong, L. [Lincoln University, Canterbury (New Zealand). Department of Plant Science

    1997-12-31

    A number of researchers have identified a measurable difference between the {sup 14}C activities of tree rings of identical dendochronological age between the Northern and the Southern Hemispheres. It is also acknowledged that there is an urgent need for new high precision {Delta}{sup 14}C data from tree rings in both Hemispheres to help resolve the questions relating to the magnitude and cause of the locality and temporal dependence of the {Delta}{sup 14}C record, to provide a reliable Southern Hemisphere calibration curve and to throw light upon the 1986 and 1993 Calibration data set discrepancies. In this paper, the authors present the research design of a project to investigate these critical issues in radiocarbon age calibration and describe the preliminary results. Paper no. 30; Extended abstract; 12 refs.

  2. A Chronology of Late-Glacial and Holocene Advances of Quelccaya Ice Cap, Peru, Based on 10Be and Radiocarbon Dating

    Science.gov (United States)

    Kelly, M. A.; Lowell, T. V.; Schaefer, J. M.

    2007-12-01

    The Quelccaya Ice Cap region in the southeastern Peruvian Andes (~13-14°S latitude) is a key location for the development of late-glacial and Holocene terrestrial paleoclimate records in the tropics. We present a chronology of past extents of Quelccaya Ice Cap based on ~thirty internally consistent 10Be dates of boulders on moraines and bedrock as well as twenty radiocarbon dates of organic material associated with moraines. Based on results from both dating methods, we suggest that significant advances of Quelccaya Ice Cap occurred during late-glacial time, at ~12,700-11,400 yr BP, and during Late Holocene time ~400-300 yr BP. Radiocarbon dating of organic material associated with moraines provides maximum and minimum ages for ice advances and recessions, respectively, thus providing an independent check on 10Be dates of boulders on moraines. The opportunity to use both 10Be and radiocarbon dating makes the Quelccaya Ice Cap region a potentially important low-latitude calibration site for production rates of cosmogenic nuclides. Our radiocarbon chronology provides a tighter constraint on maximum ages of late-glacial and Late Holocene ice advances. Upcoming field research will obtain organic material for radiocarbon dating to improve minimum age constrains for late-glacial and Late Holocene ice recessions.

  3. Tell es-Sultan (Jericho) : Radiocarbon results of short-lived cereal and multiyear charcoal samples from the end of the Middle Bronze Age

    NARCIS (Netherlands)

    Bruins, HJ; VanDerPlicht, J; Bruins, Hendrik J.; Cook, G.T.; Harkness, D.D.; Miller, B.F.; Scott, E.M.

    1995-01-01

    Samples from Tell es-Sultan, Jericho, were selected for high-precision C-14 dating as a contribution toward the establishment of an independent radiocarbon chronology of Near Eastern archaeology. The material derives from archaeological excavations conducted by K. M. Kenyon in the 1950s. We present

  4. Probable age of Autolycus and calibration of lunar stratigraphy

    Science.gov (United States)

    Ryder, G.; Bogard, D.; Garrison, D.

    1991-01-01

    Ar-39 - Ar-40 analyses of three petrographically distinct, shocked Apollo 15 KREEP (i.e., high K, rare earth element, P, and other trace element contents) basalt samples demonstrate that a major impact event affected all three samples at about 2.1 Ga. The Copernican System craters Aristillus and Autolycus are to the north. Autolycus, the older of the two, is in a particularly appropriate terrain and is the most likely source of the 2.1 Ga heating and delivery event. With this calibration point, and if Autolycus really is a Copernican crater, the Copernican System lasted twice as long as has previously been suggested. Furthermore, the moon was not subjected to a constant cratering rate over the past 3 billion years; the average rate in the preceding Eratosthenian must have been twice that in the Copernican.

  5. Radiocarbon dating of interlaboratory check samples

    International Nuclear Information System (INIS)

    Blake, W.

    1983-01-01

    This note presents the results of a series of interlaboratory age determinations in which the Geological Survey of Canada's Radiocarbon Dating Laboratory has been involved. There is good agreement between laboratories, although there may be other problems related to the interpretation of individual samples

  6. Radiocarbon dates of the Iron Age hillfort of O Achadizo (Boiro, A Coruña, NW Iberia: an approach to the dating of marine shells

    Directory of Open Access Journals (Sweden)

    Rubinos Pérez, Antonio

    1999-06-01

    Full Text Available The excavation of the hillfort of O Achadizo has brought to light several domestic structures intermingled with rubish heaps, belonging to the Iron Age Castro culture of NW Iberia. The abundant organic remains have constituted the basis for a systematic programme of radiocarbon dating of the different stratigraphic levels, which shows that the main occupation of the site took place between the VI and the II centuries cal. BC. Moreover, we have checked the 14C dates obtained from terrestrial samples (bones and charcoal against those made on marine shells coming from the same strata. As a result, we have found that the latter have an apparent age of 316±I9 years, caused by the reservoir effect. Therefore, we stress the need for taking into account -and correcting whenever possible- such a deviation before using samples of marine origin for chronological purposes.

    La excavación del castro de O Achadizo (Boiro, A Coruña puso al descubierto una serie de estructuras domésticas, así como varios basureros, encuadrables todos ellos dentro de la cultura castreña del Noroeste ibérico. El hecho de poder disponer de una gran cantidad de material orgánico procedente de los distintos niveles de habitación ha permitido llevar a cabo un programa sistemático de datación mediante el radiocarbono. Como resultado de los análisis radiométricos se deduce que la principal ocupación del yacimiento tuvo lugar entre los siglos VI al II cal BC. Por otra parte hemos cotejado las dataciones obtenidas sobre muestras con la misma procedencia estratigráfica, de origen terrestre (huesos y carbones y oceánico (conchas, a fin de evaluar el efecto de reserva marina. El valor medio de la edad aparente de las conchas de O Achadizo (316 ±19 es semejante al calculado para la costa portuguesa y subraya la necesidad de efectuar una corrección de las dataciones hechas sobre material orgánico de origen marino.

  7. Probable age of Autolycus and calibration of lunar stratigraphy

    International Nuclear Information System (INIS)

    Ryder, G.; Bogard, D.; Garrison, D.

    1991-01-01

    39 Ar- 40 Ar analyses of three petrographically distinct, shocked Apollo 15 KREEP (i.e., high K, rare earth element, P, and other trace element contents) basalt samples demonstrate that a major impact event affected all three samples at about 2.1 Ga. The Copernican System craters Aristillus and Autolycus are to the north; a ray from one of them crosses the landing site and had been suggested prior to the Apollo 15 mission as a source of material that could be used to date these craters. Autolycus, the older of the two, is in a particularly appropriate terrain and is the most likely source of the 2.1 Ga heating and delivery event. With this calibration point, and if Autolycus really is a Copernican crater, the Copernican System lasted twice as long as has previously been suggested. Furthermore, the Moon was not subjected to a constant cratering rate over the past 3 b.y.; the average rate in the preceding Eratosthenian must have been twice that in the Copernican

  8. Development of BASIC program for radiocarbon dating

    International Nuclear Information System (INIS)

    Omoto, Kunio

    1982-01-01

    The continuous improvement of the system and the needs have produced the successful radiocarbon dating system of today to detect very low energy β-radioactivity. However, it still takes longer than 1,000 minutes for a sample counting. In a gas counting system, it is very difficult to keep the drift of impressed high voltage for a proportional counter less than 5 volts throughout the counting time. The temperature and the characteristics of gas itself also change during experiment. The accumulation of the above drift and errors are closely concerned with the accuracy and reliability of the radiocarbon date. The detection and reduction of the errors are only possible by using a ''fully automatic radiocarbon dating system'' linked to a personal computer system. In this paper, the author presents the BASIC (Beginners All-purpose Symbolic Instruction Code) program for a fully automatic radiocarbon dating system. In this paper, the outline of the system and software development are described. The details of the program include the description for gas-collection, gas-enclosing, plateau counting, β-ray counting, age calculation and data file maintenance. The author wrote numerous remark statements into the program so that it can be understood by users without detailed knowledge of the operation of a personal computer system or of the radiocarbon dating. Using this system, the author found that the radiocarbon dating has greatly progressed in speed and labour-saving, and that the accuracy and reliability of the date itself has also improved much than former manual systems. (Wakatsuki, Y.)

  9. Support for the Astronomically Calibrated 40Ar/39Ar Age of Fish Canyon Sanidine

    DEFF Research Database (Denmark)

    Rivera, Tiffany; Storey, Michael; Zeeden, Christian

    2011-01-01

    al. (2008) determined an astronomically calibrated 40Ar/39Ar age of 28.201 0.046 Ma (2), relative to the indirect astronomically tuned Moroccan Melilla Basin Messâdit section. Here, we provide independent verification for the Kuiper, et al. (2008) FCs age using sanidines extracted from the A1 tephra...

  10. Radiocarbon dating of lake sediments

    OpenAIRE

    Pocevičius, Matas

    2016-01-01

    Matas Pocevičius, Radiocarbon dating of lake sediments, bachelor thesis, Vilnius University, Faculty of Physics, Department of General Physics and Spectroscopy, physics, Vilnius, 45 p., 2016. The aim of this study is to evaluate the possibility of radiocarbon dating application for Tapeliai lake bottom sediments. The literature review discusses topics related to accelerator mass spectrometry, principles of radiocarbon formation, importance of nuclear fallout for 14C, possible applications of ...

  11. An assessment of variability in radiocarbon dating

    International Nuclear Information System (INIS)

    Scott, E.M.; Baxter, M.S.; Aitchison, T.C.

    1981-01-01

    A series of replicate experiments, involving analysis of homogenized wood and identical tree-ring sections, suggests that the 14 C counting error in radiocarbon dating quantifies only part of the total variability of measurement. Statistical modelling implies that a more realistic assessment of error is provided by a value approximately three times the counting error. The incorporation of this more realistic measure of variability into an appropriate procedure for calibrating a single date and for matching a floating chronology to a master chronology is described. (author)

  12. Marine radiocarbon reservoir age variation in Donax obesulus shells from northern Peru: late Holocene evidence for extended El Niño

    Science.gov (United States)

    Etayo-Cadavid, Miguel F.; Andrus, C. Fred T.; Jones, Kevin B.; Hodgins, Gregory W. L.; Sandweiss, Daniel H.; Uceda-Castillo, Sandiago; Quilter, Jeffrey

    2013-01-01

    For at least 6 m.y., El Niño events have posed the greatest environmental risk on the Peruvian coast. A better understanding of El Niño is essential for predicting future risk and growth in this tropical desert. To achieve this we analyzed archaeological and modern pre-bomb shells from the surf clam Donax for the radiocarbon reservoir effect (ΔR) to characterize late Holocene coastal upwelling conditions in northern Peru (8°14′S). Mean ΔR values from these shells suggest that modern upwelling conditions in this region were likely established between A.D. 539 and A.D. 1578. Our radiocarbon data suggest that upwelling conditions ca. A.D. 539 were less intense than those in modern times. The observed coastal water enrichment in 14C may be consequence of frequent strong El Niño events or extended El Niño–like conditions. These ΔR-inferred marine conditions are in agreement with proposed extended El Niño activity in proxy and archaeological records of ca. A.D. 475–530. Extended El Niño conditions have been linked to political destabilization, societal transformation, and collapse of the Moche civilization in northern Peru. A return to such conditions would have significant impacts on the dense population of this region today and in the near future.

  13. The freshwater reservoir effect in radiocarbon dating

    DEFF Research Database (Denmark)

    Philippsen, Bente

    2013-01-01

    of magnitude and degree of variability of the freshwater reservoir effect over short and long timescales. Radiocarbon dating of recent water samples, aquatic plants, and animals, shows that age differences of up to 2000 14C years can occur within one river. The freshwater reservoir effect has also implications......The freshwater reservoir effect can result in anomalously old radiocarbon ages of samples from lakes and rivers. This includes the bones of people whose subsistence was based on freshwater fish, and pottery in which fish was cooked. Water rich in dissolved ancient calcium carbonates, commonly known...... as hard water, is the most common reason for the freshwater reservoir effect. It is therefore also called hardwater effect. Although it has been known for more than 60 years, it is still less well-recognized by archaeologists than the marine reservoir effect. The aim of this study is to examine the order...

  14. Annually resolved atmospheric radiocarbon records reconstructed from tree-rings

    Science.gov (United States)

    Wacker, Lukas; Bleicher, Niels; Büntgen, Ulf; Friedrich, Michael; Friedrich, Ronny; Diego Galván, Juan; Hajdas, Irka; Jull, Anthony John; Kromer, Bernd; Miyake, Fusa; Nievergelt, Daniel; Reinig, Frederick; Sookdeo, Adam; Synal, Hans-Arno; Tegel, Willy; Wesphal, Torsten

    2017-04-01

    The IntCal13 calibration curve is mainly based on data measured by decay counting with a resolution of 10 years. Thus high frequency changes like the 11-year solar cycles or cosmic ray events [1] are not visible, or at least not to their full extent. New accelerator mass spectrometry (AMS) systems today are capable of measuring at least as precisely as decay counters [2], with the advantage of using 1000 times less material. The low amount of material required enables more efficient sample preparation. Thus, an annually resolved re-measurement of the tree-ring based calibration curve can now be envisioned. We will demonstrate with several examples the multitude of benefits resulting from annually resolved radiocarbon records from tree-rings. They will not only allow for more precise radiocarbon dating but also contain valuable new astrophysical information. The examples shown will additionally indicate that it can be critical to compare AMS measurements with a calibration curve that is mainly based on decay counting. We often see small offsets between the two measurement techniques, while the reason is yet unknown. [1] Miyake F, Nagaya K, Masuda K, Nakamura T. 2012. A signature of cosmic-ray increase in AD 774-775 from tree rings in Japan. Nature 486(7402):240-2. [2] Wacker L, Bonani G, Friedrich M, Hajdas I, Kromer B, Nemec M, Ruff M, Suter M, Synal H-A, Vockenhuber C. 2010. MICADAS: Routine and high-precision radiocarbon dating. Radiocarbon 52(2):252-62.

  15. The radiocarbon timescale

    International Nuclear Information System (INIS)

    Mook, W.G.

    1977-01-01

    The relation between the conventional 14 C timescale and the astronomical timescale is of increasing importance and interest. A concise review is given of the calibrations which have been carried out thus far on dendrochronologically dated tree rings. The causes of the discrepancies between both scales are briefly indicated. The reliability of the existing calibration curves, the problems which are encountered in using them and the necessity of further calibration measurements are discussed. (author)

  16. Pre-bomb marine reservoir ages in the western north Pacific : Preliminary result on Kyoto University collection

    NARCIS (Netherlands)

    Yoneda, M; Kitagawa, H; van der Plicht, J; Uchida, M; Tanaka, A; Uehiro, T; Shibata, Y; Morita, M; Ohno, T

    2000-01-01

    The calibration of radiocarbon dates on marine materials involves a global marine calibration with regional corrections. The marine reservoir ages in the Western North Pacific have not been discussed, while it is quite important to determine the timing of palaeo-environmental changes as well as

  17. Radiocarbon measurements on submerged forest floating chronologies

    International Nuclear Information System (INIS)

    Campbell, J.A.; Baxter, M.S.

    1979-01-01

    It is stated that the submerged forests along the west coast of England and Wales provide a unique source of wood for radiocarbon/ dendrochronological studies. 14 C age determinations are reported on sequential growth increments from three 'gloating' chronologies. A sampling frequency of approximately 10 samples per century was used. Fluctuations in atmospheric 14 C levels of 2 to 3% over several decades can occur, these variations being superimposed on a smoothly changing trend. (author)

  18. Assessing screening criteria for the radiocarbon dating of bone mineral

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, Ricardo, E-mail: ldv1452@gmail.com [Leibniz Labor for Isotopic and Radiometric Dating, Max-Eyth-Str. 11-13, 24118 Kiel (Germany); Graduate School Human Development in Landscapes, Christian Albrecht University, Kiel (Germany); Huels, Matthias [Leibniz Labor for Isotopic and Radiometric Dating, Max-Eyth-Str. 11-13, 24118 Kiel (Germany); Nadeau, Marie-Josee; Grootes, Pieter M. [Leibniz Labor for Isotopic and Radiometric Dating, Max-Eyth-Str. 11-13, 24118 Kiel (Germany); Graduate School Human Development in Landscapes, Christian Albrecht University, Kiel (Germany); Garbe-Schoenberg, C.-Dieter [Institute of Geosciences, Marine Climate Research and ICPMS Lab, Kiel University, Ludewig-Meyn-Str. 10, D-24118 Kiel (Germany); Graduate School Human Development in Landscapes, Christian Albrecht University, Kiel (Germany); Hollund, Hege I. [Institute for Geo- and Bioarchaeology, The VU University, De Boelelaan 1085, 1081 HV Amsterdam (Netherlands); Lotnyk, Andriy [Faculty of Engineering, Institute for Material Science, Synthesis and Real Structure, Kiel University, Kaiserstr. 2, D-24143 Kiel (Germany); Leibniz Institute of Surface Modification (IOM), Permoserstr. 15, D-04318 Leipzig (Germany); Kienle, Lorenz [Faculty of Engineering, Institute for Material Science, Synthesis and Real Structure, Kiel University, Kaiserstr. 2, D-24143 Kiel (Germany); Graduate School Human Development in Landscapes, Christian Albrecht University, Kiel (Germany)

    2013-01-15

    Radiocarbon dating of bone mineral (carbonate in the apatite lattice) has been the target of sporadic research for the last 40 years. Results obtained by different decontamination protocols have, however, failed to provide a consistent agreement with reference ages. In particular, quality criteria to assess bone mineral radiocarbon dating reliability are still lacking. Systematic research was undertaken to identify optimal preservation criteria for bone mineral in archeological bones. Six human long bones, originating from a single site, were radiocarbon-dated both for collagen and apatite, with the level of agreement between the dates providing an indication of exogenous carbon contamination. Several techniques (Histology, FTIR, TEM, LA-ICP-MS) were employed to determine the preservation status of each sample. Research results highlight the importance of a micro-scale approach in establishing bone preservation, in particular the use of trace element concentration profiles demonstrated its potential use as a viable sample selection criterion for bone carbonate radiocarbon dating.

  19. Impact of fossil fuel emissions on atmospheric radiocarbon and various applications of radiocarbon over this century.

    Science.gov (United States)

    Graven, Heather D

    2015-08-04

    Radiocarbon analyses are commonly used in a broad range of fields, including earth science, archaeology, forgery detection, isotope forensics, and physiology. Many applications are sensitive to the radiocarbon ((14)C) content of atmospheric CO2, which has varied since 1890 as a result of nuclear weapons testing, fossil fuel emissions, and CO2 cycling between atmospheric, oceanic, and terrestrial carbon reservoirs. Over this century, the ratio (14)C/C in atmospheric CO2 (Δ(14)CO2) will be determined by the amount of fossil fuel combustion, which decreases Δ(14)CO2 because fossil fuels have lost all (14)C from radioactive decay. Simulations of Δ(14)CO2 using the emission scenarios from the Intergovernmental Panel on Climate Change Fifth Assessment Report, the Representative Concentration Pathways, indicate that ambitious emission reductions could sustain Δ(14)CO2 near the preindustrial level of 0‰ through 2100, whereas "business-as-usual" emissions will reduce Δ(14)CO2 to -250‰, equivalent to the depletion expected from over 2,000 y of radioactive decay. Given current emissions trends, fossil fuel emission-driven artificial "aging" of the atmosphere is likely to occur much faster and with a larger magnitude than previously expected. This finding has strong and as yet unrecognized implications for many applications of radiocarbon in various fields, and it implies that radiocarbon dating may no longer provide definitive ages for samples up to 2,000 y old.

  20. Si-Traceable Scale for Measurements of Radiocarbon Concentration

    Science.gov (United States)

    Hodges, Joseph T.; Fleisher, Adam J.; Liu, Qingnan; Long, David A.

    2017-06-01

    Radiocarbon (^{14}C) dating of organic materials is based on measuring the ^{14}C/^{12}C atomic fraction relative to the nascent value that existed when the material was formed by photosynthetic conversion of carbon dioxide present in the atmosphere. This field of measurement has numerous applications including source apportionment of anthropogenic and biogenic fuels and combustion emissions, carbon cycle dynamics, archaeology, and forensics. Accelerator mass spectrometry (AMS) is the most widely used method for radiocarbon detection because it can measure extremely small amounts of radiocarbon (background of nominally 1.2 parts-per-trillion) with high relative precision (0.4 %). AMS measurements of radiocarbon are typically calibrated by reference to standard oxalic-acid (C_2H_2O_4) samples of known radiocativity that are derived from plant matter. Specifically, the internationally accepted absolute dating reference for so-called "modern-equivalent" radiocarbon is 95 % of the specific radioactivity in AD 1950 of the National Bureau of Standards (NBS) oxalic acid standard reference material and normalized to δ^{13}C_{VPDB} = 19 per mil. With this definition, a "modern-equivalent" corresponds to 1.176(70) parts-per-trillion of ^{14}C relative to total carbon content. As an alternative radiocarbon scale, we propose an SI-traceable method to determine ^{14}C absolute concentration which is based on linear Beer-Lambert-law absorption measurements of selected ^{14}C^{16}O_2 ν_3-band line areas. This approach is attractive because line intensities of chosen radiocarbon dioxide transitions can be determined by ab initio calculations with relative uncertainties below 0.5 %. This assumption is justified by the excellent agreement between theoretical values of line intensities and measurements for stable isotopologues of CO_2. In the case of cavity ring-down spectroscopy (CRDS) measurements of ^{14}C^{16}O_2 peak areas, we show that absolute, SI-traceable concentrations of

  1. Radiocarbon dating development and practices at MINT

    International Nuclear Information System (INIS)

    Kamisah Alias; Bashillah Baharuddin; Juhari Mohd Yusof; Ahmad Raduan Ujang

    2002-01-01

    The MINT radiocarbon dating technique was introduced and a very well-designed vacuum line was developed to generate benzene from samples containing carbon. A liquid scintillation counter provides a very good prerequisite for precise measurement of the C-14 activity in the benzene. From time to time, assessment on the status of the analytical capabilities of the system and advice on improvement and upgrading required was made. For routine analysis, standard sampling, pretreatment, carbon dioxide conversion and measurement procedures were adopted. Radiocarbon dating is now, one of the most important developments of the twenties century in the comprehension of the history of human development, a quick, easy, reliable and scientifically acceptable method to determine the age of historical artefacts and archaeological samples. (Author)

  2. Geological Survey of Canada radiocarbon dates XXIX

    International Nuclear Information System (INIS)

    McNeely, R.; McCuaig, S.

    1991-01-01

    This list presents 622 radiocarbon age determinations made by the Radiocarbon Dating Laboratory. All samples dated more than two years ago have now been reported in date lists. The total number (609) of samples from various areas are as follows: Offshore (43); Newfoundland (42); Labrador (11); Nova Scotia (39); New Brunswick (7); Champlain Sea (38); Quebec (54); Ontario (23); Manitoba (3); Saskatchewan (9); Alberta (6); British Columbia (92); Yukon Territory (71); Northwest Territories, mainland (33); Northwest Territories, Arctic Archipelago (126); U.S.A. - New York (6); Washington (1); Denmark Greenland (3). Tables 1 and 2 summarize the details of background and standard counts for the 2 L and 5 L counters during the period from December 6, 1988 to January 9, 1990. (author). Refs

  3. Geological Survey of Canada radiocarbon dates XXIX

    Energy Technology Data Exchange (ETDEWEB)

    McNeely, R; McCuaig, S

    1992-12-31

    This list presents 622 radiocarbon age determinations made by the Radiocarbon Dating Laboratory. All samples dated more than two years ago have now been reported in date lists. The total number (609) of samples from various areas are as follows: Offshore (43); Newfoundland (42); Labrador (11); Nova Scotia (39); New Brunswick (7); Champlain Sea (38); Quebec (54); Ontario (23); Manitoba (3); Saskatchewan (9); Alberta (6); British Columbia (92); Yukon Territory (71); Northwest Territories, mainland (33); Northwest Territories, Arctic Archipelago (126); U.S.A. - New York (6); Washington (1); Denmark Greenland (3). Tables 1 and 2 summarize the details of background and standard counts for the 2 L and 5 L counters during the period from December 6, 1988 to January 9, 1990. (author). Refs.

  4. Bayesian calibration : past achievements and future challenges

    International Nuclear Information System (INIS)

    Christen, J.A.

    2001-01-01

    Due to variations of the radiocarbon content in the biosphere over time, radiocarbon determinations need to be calibrated to obtain calendar years. Over the past decade a series of researchers have investigated the possibility of using Bayesian statistics to calibrate radiocarbon determinations, the main feature being the inclusion of contextual information into the calibration process. This allows for a coherent calibration of groups of determinations arising from related contexts (stratigraphical layers, peat cores, cultural events, ect.). Moreover, the 'related contexts' are also dated, and not only the material radiocarbon dated itself. We review Bayesian Calibration and state some of its current challenges like: software development, prior specification, robustness, etc. (author). 14 refs., 4 figs

  5. New biomedical applications of radiocarbon

    International Nuclear Information System (INIS)

    Davis, J.C.

    1990-12-01

    The potential of accelerator mass spectrometry (AMS) and radiocarbon in biomedical applications is being investigated by Lawrence Livermore National Laboratory (LLNL). A measurement of the dose-response curve for DNA damage caused by a carcinogen in mouse liver cells was an initial experiment. This demonstrated the sensitivity and utility of AMS for detecting radiocarbon tags and led to numerous follow-on experiments. The initial experiment and follow-on experiments are discussed in this report. 12 refs., 4 figs. (SM)

  6. A Refined Astronomically Calibrated 40Ar/39Ar Age for Fish Canyon Sanidine

    DEFF Research Database (Denmark)

    Rivera, Tiffany; Storey, Michael; Zeeden, Christian

    2011-01-01

    Intercalibration between the astronomical and radio-isotopic dating methods provides a means to improving accuracy and reducing uncertainty of an integrated, multi-chronometer geologic timescale. Here we report a high-precision 40Ar/39Ar age for the Fish Canyon sanidine (FCs) neutron fluence...... sanidine age of 0.7674±0.0022 Ma (2σ, external errors) is indistinguishable from the ID-TIMS U/Pb zircon age (0.7671±0.0019 Ma). The consistency between the astronomically calibrated 40Ar/39Ar sanidine age and U/Pb zircon age for this Quaternary unit suggests that agreement between these two radio-isotopic...... dating techniques is now achievable at better than±0.3% (2σ) in the youngest part of geologic time (

  7. Radiocarbon C-14 dating - MINT experience

    International Nuclear Information System (INIS)

    Kamisah Alias

    2002-01-01

    The measurement of a radiocarbon date is a complex process which involved all the stages from advice given prior to submission of samples right through to reporting of results. The aim of our radiocarbon dating is to determine the residual 14 C content of a sample, the value of which is translated into an age that is an estimate of the time elapsed since the given sample was removed from the environment in which it had formed in equilibrium with respect to 14-C radioactive decay and metabolic assimilation. Carbon is obtained from carbon containing samples in the form of carbon dioxide, which is then reacted with lithium forming lithium carbide. The carbide is then hydrolysed to acetylene before it was polymerised to benzene using a high-efficiency vanadium-alumina-silica catalyst to produce benzene with up to 96% yield. Sample, background and modem standard activities are measured with a coincidence scintillation counter using in glass vials of 21 ml capacity. An improved chemical procedure was used to obtain and purify the benzene from the samples for measurement using a liquid scintillation counter. Radiocarbon dating measurements of samples collected reveal some results. The validity of the data have yet to be confirmed by the results of the measurements on two international control samples. (Author)

  8. Radiocarbon Ages and Environments of Deposition of the Wono and Trego Hot Springs Tephra Layers in the Pyramid Lake Subbasin, Nevada

    Science.gov (United States)

    Benson, L.V.; Smoot, J.P.; Kashgarian, Michaele; Sarna-Wojcicki, A.; Burdett, J.W.

    1997-01-01

    Uncalibrated radiocarbon data from core PLC92B taken from Wizards Cove in the Pyramid Lake subbasin indicate that the Trego Hot Springs and Wono tephra layers were deposited 23,200 ?? 300 and 27,300 ??300 14C yr B.P. (uncorrected for reservoir effect). Sedimentological data from sites in the Pyramid Lake and Smoke Creek-Black Rock Desert subbasins indicate that the Trego Hot Springs tephra layer was deposited during a relatively dry period when Pyramid Lake was at or below its spill point (1177 m) to the Winnemucca Lake subbasin. The Wono tephra layer was deposited when lake depth was controlled by spill across Emerson Pass sill (1207 m) to the Smoke Creek-Black Rock Desert subbasin. 18O data from core PLC92B also support the concept that the Trego Hot Springs tephra fell into a relatively shallow Pyramid Lake and that the Wono tephra fell into a deeper spilling lake. ?? 1997 University of Washington.

  9. Radiocarbon dating prehistoric pottery from Northern Europe

    DEFF Research Database (Denmark)

    Philippsen, Bente; Craig, Oliver; Heron, Carl

    2012-01-01

    , such as when aquatic products have been prepared in the pottery. Soot can derive from old wood that was used for the hearth fire, or from (potentially aquatic) food that boiled over. Plant remains may have been present in the clay for a long time before manufacture of the pottery. Post......-depositional contamination with organic carbon, such as humic acids, may also be problematic. We present these data with radiocarbon datings of contemporaneous terrestrial and aquatic samples to find out the true age of the pottery and estimate the reservoir age. Lipid analysis and bulk carbon and nitrogen stable isotope...

  10. Studies on the radiocarbon sample from the shroud of turin

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, Raymond N. [Los Alamos National Laboratory, University of California, 1961 Cumbres Patio, Los Alamos, NM 87544 (United States)]. E-mail: rnrogers@att.net

    2005-01-20

    In 1988, radiocarbon laboratories at Arizona, Cambridge, and Zurich determined the age of a sample from the Shroud of Turin. They reported that the date of the cloth's production lay between A.D. 1260 and 1390 with 95% confidence. This came as a surprise in view of the technology used to produce the cloth, its chemical composition, and the lack of vanillin in its lignin. The results prompted questions about the validity of the sample. Preliminary estimates of the kinetics constants for the loss of vanillin from lignin indicate a much older age for the cloth than the radiocarbon analyses. The radiocarbon sampling area is uniquely coated with a yellow-brown plant gum containing dye lakes. Pyrolysis-mass-spectrometry results from the sample area coupled with microscopic and microchemical observations prove that the radiocarbon sample was not part of the original cloth of the Shroud of Turin. The radiocarbon date was thus not valid for determining the true age of the shroud.

  11. Studies on the radiocarbon sample from the shroud of turin

    International Nuclear Information System (INIS)

    Rogers, Raymond N.

    2005-01-01

    In 1988, radiocarbon laboratories at Arizona, Cambridge, and Zurich determined the age of a sample from the Shroud of Turin. They reported that the date of the cloth's production lay between A.D. 1260 and 1390 with 95% confidence. This came as a surprise in view of the technology used to produce the cloth, its chemical composition, and the lack of vanillin in its lignin. The results prompted questions about the validity of the sample. Preliminary estimates of the kinetics constants for the loss of vanillin from lignin indicate a much older age for the cloth than the radiocarbon analyses. The radiocarbon sampling area is uniquely coated with a yellow-brown plant gum containing dye lakes. Pyrolysis-mass-spectrometry results from the sample area coupled with microscopic and microchemical observations prove that the radiocarbon sample was not part of the original cloth of the Shroud of Turin. The radiocarbon date was thus not valid for determining the true age of the shroud

  12. Relevance of medieval, Egyptian and American dates to the study of climatic and radiocarbon variability

    International Nuclear Information System (INIS)

    Berger, R.

    1990-01-01

    Basic radiocarbon dating and dendrochronology have been combined to yield calibrated dates that are more accurate than conventional radiocarbon dates. This has been shown to be true for medieval and Egyptian dynastic dating. Because radiocarbon is a cosmogenically produced radioisotope, heliomagnetic and geomagnetic fields play a major role in its synthesis in the Earth's upper atmosphere. Inasmuch as a calibrated radiocarbon record exists for nearly 10 000 years, we now seem to possess in the short-time variations of the production rate a history of solar activity expressed via heliomagnetic fields carried by the solar wind. In turn, solar activity has a controlling effect on climate on Earth within modifications provided by the complex interactions of the atmosphere-Earth-ocean system. Both radiocarbon measurements and other empirical research methods agree on variations of climate during historically more recent periods on Earth. This leads to the suggestion that the radiocarbon calibration curve may be also a significant indicator or tracer for climatic changes for the Holocene or the Neolithic-Mesolithic. (author)

  13. Relevance of medieval, Egyptian and American dates to the study of climatic and radiocarbon variability

    Energy Technology Data Exchange (ETDEWEB)

    Berger, R [California Univ., Los Angeles, CA (USA). Inst. of Geophysics and Planetary Physics

    1990-04-24

    Basic radiocarbon dating and dendrochronology have been combined to yield calibrated dates that are more accurate than conventional radiocarbon dates. This has been shown to be true for medieval and Egyptian dynastic dating. Because radiocarbon is a cosmogenically produced radioisotope, heliomagnetic and geomagnetic fields play a major role in its synthesis in the Earth's upper atmosphere. Inasmuch as a calibrated radiocarbon record exists for nearly 10 000 years, we now seem to possess in the short-time variations of the production rate a history of solar activity expressed via heliomagnetic fields carried by the solar wind. In turn, solar activity has a controlling effect on climate on Earth within modifications provided by the complex interactions of the atmosphere-Earth-ocean system. Both radiocarbon measurements and other empirical research methods agree on variations of climate during historically more recent periods on Earth. This leads to the suggestion that the radiocarbon calibration curve may be also a significant indicator or tracer for climatic changes for the Holocene or the Neolithic-Mesolithic. (author).

  14. Reconciling radiocarbon and ice core timescales over the Holocene - Cosmogenic radionuclides as synchronization tools

    Science.gov (United States)

    Muscheler, R.; Adolphi, F.; Mekhaldi, F.

    2015-12-01

    The atmospheric production rates of cosmogenic radionuclides, such as 14C and 10Be, vary globally due to external processes, namely the solar and geomagnetic modulation of the galactic cosmic ray flux as well as solar proton events. This signature is recorded in various archives such as ice cores (10Be) and tree-rings (14C). Hence, cosmogenic radionuclides offer a means to continuously assess timescale differences between two of the most widely used timescales in paleoclimatology - the radiocarbon and the ice core timescales. Short lived solar proton events additionally provide distinct marker horizons that allow synchronization of discrete horizons at annual precision. We will present a cosmogenic radionuclide based synchronization of the Greenland ice core timescale (GICC05, Svensson et al., 2008) and the radiocarbon timescale (IntCal13, Reimer et al., 2013) over the Holocene. This synchronization allows radiocarbon dated and ice core paleoclimate records to be compared on a common timescale at down to sub-decadal precision. We will compare these results to independent discrete isochrones obtained from tephrochronology and solar proton events. In addition, we will discuss implications for the accuracy and uncertainty estimates of GICC05 over the Holocene. Reimer, P. J., Bard, E., Bayliss, A., Beck, J. W., Blackwell, P. G., Bronk Ramsey, C., Buck, C. E., Cheng, H., Edwards, R. L., Friedrich, M., Grootes, P. M., Guilderson, T. P., Haflidason, H., Hajdas, I., Hatté, C., Heaton, T. J., Hoffmann, D. L., Hogg, A. G., Hughen, K. A., Kaiser, K. F., Kromer, B., Manning, S. W., Niu, M., Reimer, R. W., Richards, D. A., Scott, E. M., Southon, J. R., Staff, R. A., Turney, C. S. M., and van der Plicht, J.: IntCal13 and Marine13 Radiocarbon Age Calibration Curves 0-50,000 Years cal BP, Radiocarbon, 55, 1869-1887, 10.2458/azu_js_rc.55.16947, 2013. Svensson, A., Andersen, K. K., Bigler, M., Clausen, H. B., Dahl-Jensen, D., Davies, S. M., Johnsen, S. J., Muscheler, R., Parrenin

  15. Sensitivity of Deep Soil Organic Carbon Age to Sorption, Transport and Microbial Interactions - Insights from a Calibrated Process Model

    Science.gov (United States)

    Ahrens, B.; Schrumpf, M.; Reichstein, M.

    2013-12-01

    Subsoil soil organic carbon (SOC) is characterized by conventional radiocarbon ages on the order of centuries to millennia. Most vertically explicit SOC turnover models represent this persistence of deep SOC by one pool that has millennial turnover times. This approach lumps different stabilizing mechanisms such as chemical recalcitrance, sorptive stabilization and energy limitation into a single rate constant. As an alternative, we present a continuous, vertically explicit SOC decomposition model that allows for stabilization via sorption and microbial interactions (COMISSION model). We compare the COMISSION model with the SOC profile of a Haplic Podzol under a Norway spruce forest. In the COMISSION model two pools receive aboveground litter input and vertically distributed root litter input. The readily leachable and soluble fraction of litter input enters a dissolved organic carbon pool (DOC), while the rest enters the residue pool which represents polymeric, non-soluble SOC. The residue pool is depolymerized with extracellular enzymes produced by a microbial pool to enter the DOC pool which represents SOC potentially available for assimilation by microbes. The adsorption/desorption of DOC from/to mineral surfaces controls the availability of carbon in the DOC pool for assimilatory uptake by microbes. The sorption of DOC is modeled with dynamic Langmuir equations. The desorbed part of the DOC pool not only constitutes the substrate for the microbial pool, but is also transported via advection. Interactions of microbes with the residue and DOC pool are modeled with Michaelis-Menten kinetics - this not only allows representing ';priming', but also the retardation of decomposition via energy limitation in the deep soil where substrate is scarce. Further, soil organic matter is recycled within the soil profile through microbial processing - dead microbes either enter the DOC or the residue pool, and thereby also contribute to longer residence times with soil depth

  16. The biochemical estimation of age in Euphausiids: Laboratory calibration and field comparisons

    Science.gov (United States)

    Harvey, H. R.; Ju, Se-J.; Son, S.-K.; Feinberg, L. R.; Shaw, C. T.; Peterson, W. T.

    2010-04-01

    Euphausiids play a key role in many marine ecosystems as a link between primary producers and top predators. Understanding their demographic (i.e. age) structure is an essential tool to assess growth and recruitment as well as to determine how changes in environmental conditions might alter their condition and distribution. Age determination of crustaceans cannot be accomplished using traditional approaches, and here we evaluate the potential for biochemical products of tissue metabolism (termed lipofuscins) to determine the demographic structure of euphausiids in field collections . Lipofuscin was extracted from krill neural tissues (eye and eye-stalk), quantified using fluorescent intensity and normalized to tissue protein content to allow comparisons across animal sizes. Multiple fluorescent components from krill were observed, with the major product having a maximum fluorescence at excitation of 355 nm and emission of 510 nm. Needed age calibration of lipofuscin accumulation in Euphausia pacifica was accomplished using known-age individuals hatched and reared in the laboratory for over one year. Lipofuscin content extracted from neural tissues of laboratory-reared animals was highly correlated with the chronological age of animals ( r=0.87). Calibrated with laboratory lipofuscin accumulation rates, field-collected sub-adult and adult E. pacifica in the Northeast Pacific were estimated to be older than 100 days and younger than 1year. Comparative data for the Antarctic krill, E. superba showed much higher lipofuscin values suggesting a much longer lifespan than the more temperate species, E. pacifica. These regional comparisons suggest that biochemical indices allow a practical approach to estimate population age structure of diverse populations, and combined with other measurements can provide estimates of vital rates (i.e. longevity, mortality, growth) for krill populations in dynamic environments.

  17. Precision radiocarbon dating of a Late Holocene vegetation history

    International Nuclear Information System (INIS)

    Prior, C.A.; Chester, P.I.

    2001-01-01

    The purpose of this research is to precisely date vegetation changes associated with early human presence in the Hawkes Bay region. A sequence of AMS radiocarbon ages was obtained using a new technique developed at Rafter Radiocarbon Laboratory. A density separation method was used to concentrate pollen and spores extracted from unconsolidated lake sediments from a small-enclosed lake in coastal foothills of southern Hawkes Bay. Radiocarbon measurements were made on fractions of concentrated pollen, separated from associated organic debris. These ages directly date vegetation communities used to reconstruct the vegetation history of the region. This technique results in more accurate dating of Late Holocene vegetation changes interpreted from palynological analyses than techniques formerly used. Precision dating of palynological studies of New Zealand prehistory and history is necessary for correlation of vegetation changes to cultural changes because of the short time span of human occupation of New Zealand. (author). 35 refs., 3 figs., 1 tab

  18. Effects of aging on calibration and response time of nuclear plant pressure transmitters

    International Nuclear Information System (INIS)

    Hashemian, H.M.

    1991-01-01

    This paper presents the key results of an experimental research project conducted for the Nuclear Regulatory Commission to quantify the effects of normal aging on static and dynamic performance of nuclear grade pressure, level, and flow transmitters (hereafter referred to as pressure transmitters). The project involved laboratory testing of representative pressure transmitters manufactured by Barton, Foxboro, Rosemount, and Tobar (or Veritrak) companies. These manufacturers provide the four most commonly used pressure transmitters in the safety systems of US nuclear power plants. The transmitters were tested under normal aging conditions as opposed to accelerated aging, even though accelerated aging will be used in the last few months of the project to determine the weak links and failure modes of the transmitters. The project has been performed in two phases. The Phase 1 project which was a six month feasibility study has been completed and the results published in NUREG/CR-5383. The Phase 2 project is still underway with the final report due in the fall of 1991. The project has focused on the following areas: (1) effects of aging on calibration stability; (2) effects of aging on response time; (3) study of individual components of pressure transmitters that are sensitive to aging degradation; (4) sensing line blockages due to solidification of boron, formation of sludge, freezing, and other effects; (5) search of licensee event reports and component reliability databases for failures of safety-related pressure transmitters; and (6) oil loss syndrome in Rosemount pressure transmitters

  19. Gas chromatographic isolation technique for compound-specific radiocarbon analysis

    International Nuclear Information System (INIS)

    Uchida, M.; Kumamoto, Y.; Shibata, Y.; Yoneda, M.; Morita, M.; Kawamura, K.

    2002-01-01

    Full text: We present here a gas chromatographic isolation technique for the compound-specific radiocarbon analysis of biomarkers from the marine sediments. The biomarkers of fatty acids, hydrocarbon and sterols were isolated with enough amount for radiocarbon analysis using a preparative capillary gas chromatograph (PCGC) system. The PCGC systems used here is composed of an HP 6890 GC with FID, a cooled injection system (CIS, Gerstel, Germany), a zero-dead-volume effluent splitter, and a cryogenic preparative collection device (PFC, Gerstel). For AMS analysis, we need to separate and recover sufficient quantity of target individual compounds (>50 μgC). Yields of target compounds from C 14 n-alkanes to C 40 to C 30 n-alkanes and approximately that of 80% for higher molecular weights compounds more than C 30 n-alkanes. Compound specific radiocarbon analysis of organic compounds, as well as compound-specific stable isotope analysis, provide valuable information on the origins and carbon cycling in marine system. Above PCGC conditions, we applied compound-specific radiocarbon analysis to the marine sediments from western north Pacific, which showed the possibility of a useful chronology tool for estimating the age of sediment using organic matter in paleoceanographic study, in the area where enough amounts of planktonic foraminifera for radiocarbon analysis by accelerator mass spectrometry (AMS) are difficult to obtain due to dissolution of calcium carbonate. (author)

  20. The Worldwide Marine Radiocarbon Reservoir Effect: Definitions, Mechanisms, and Prospects

    Science.gov (United States)

    Alves, Eduardo Q.; Macario, Kita; Ascough, Philippa; Bronk Ramsey, Christopher

    2018-03-01

    When a carbon reservoir has a lower radiocarbon content than the atmosphere, this is referred to as a reservoir effect. This is expressed as an offset between the radiocarbon ages of samples from the two reservoirs at a single point in time. The marine reservoir effect (MRE) has been a major concern in the radiocarbon community, as it introduces an additional source of error that is often difficult to accurately quantify. For this reason, researchers are often reluctant to date marine material where they have another option. The influence of this phenomenon makes the study of the MRE important for a broad range of applications. The advent of Accelerator Mass Spectrometry (AMS) has reduced sample size requirements and increased measurement precision, in turn increasing the number of studies seeking to measure marine samples. These studies rely on overcoming the influence of the MRE on marine radiocarbon dates through the worldwide quantification of the local parameter ΔR, that is, the local variation from the global average MRE. Furthermore, the strong dependence on ocean dynamics makes the MRE a useful indicator for changes in oceanic circulation, carbon exchange between reservoirs, and the fate of atmospheric CO2, all of which impact Earth's climate. This article explores data from the Marine Reservoir Database and reviews the place of natural radiocarbon in oceanic records, focusing on key questions (e.g., changes in ocean dynamics) that have been answered by MRE studies and on their application to different subjects.

  1. Radiocarbon dating of American pika fecal pellets provides insights into population extirpations and climate refugia.

    Science.gov (United States)

    Millar, Constance I; Heckman, Katherine; Swanston, Christopher; Schmidt, Karena; Westfall, Robert D; Delany, Diane L

    The American pika (Ochotona princeps) has become a species of concern for its sensitivity to warm temperatures and potential vulnerability to global warming. We explored the value of radiocarbon dating of fecal pellets to address questions of population persistence and timing of site extirpation. Carbon was extracted from pellets collected at 43 locations in the western Great Basin, USA, including three known occupied sites and 40 sites of uncertain status at range margins or where previous studies indicated the species is vulnerable. We resolved calibrated dates with high precision (within several years), most of which fell in the period of the mid-late 20th century bomb curve. The two-sided nature of the bomb curve renders far- and near-side dates of equal probability, which are separated by one to four decades. We document methods for narrowing resolution to one age range, including stratigraphic analysis of vegetation collected from pika haypiles. No evidence was found for biases in atmospheric 14C levels due to fossil-derived or industrial CO2 contamination. Radiocarbon dating indicated that pellets can persist for >59 years; known occupied sites resolved contemporary dates. Using combined evidence from field observations and radiocarbon dating, and the Bodie Mountains as an example, we propose a historical biogeographic scenario for pikas in minor Great Basin mountain ranges adjacent to major cordillera, wherein historical climate variability led to cycles of extirpation and recolonization during alternating cool and warm centuries. Using this model to inform future dynamics for small ranges in biogeographic settings similar to the Bodie Mountains in California, extirpation of pikas appears highly likely under directional warming trends projected for the next century, even while populations in extensive cordillera (e.g., Sierra Nevada, Rocky Mountains, Cascade Range) are likely to remain viable due to extensive, diverse habitat and high connectivity.

  2. Radiocarbon dating of iron artefacts

    Energy Technology Data Exchange (ETDEWEB)

    Cresswell, R. [Australian National Univ., Canberra, ACT (Australia). Dept. of Nuclear Physics

    1997-12-31

    Iron artefacts are generally dated by association or on stylistic grounds. This may not give a true indication of the date of manufacture, or may not be possible if the piece is out of context, ambiguous in style, or a copy. Obtaining a direct date on the artefact would be preferable. During the processes of manufacture, carbon is incorporated into the iron from the fuel source. If the fuel is of a material containing contemporaneous carbon, i.e. has an ambient radiocarbon signature, e.g. charcoal, then we may reliably radiocarbon date the artefact by extracting this carbon. Care must be taken, however, to ensure that re-working has not introduced multiple sources of carbon that would give an erroneous date. Detailed chemical analysis must precede radiocarbon analysis. Sample size is determined by carbon content, and before the advent of accelerator mass spectrometry, several tens of grams of carbon were required for radiocarbon dating (van der Merwe, 1969), prohibiting this method except for high-carbon cast-irons and bulk samples, e.g. caches of nails. AMS permits the analysis of sub-gram pieces of iron (Cresswell, 1991), thereby permitting the analysis of museum pieces with only minimal loss of material, and small fragments of iron recovered from archaeological sites. A few examples are given to illustrate these points. Paper no. 41; Extended abstract. 6 refs.

  3. Radiocarbon dating of iron artefacts

    International Nuclear Information System (INIS)

    Cresswell, R.

    1997-01-01

    Iron artefacts are generally dated by association or on stylistic grounds. This may not give a true indication of the date of manufacture, or may not be possible if the piece is out of context, ambiguous in style, or a copy. Obtaining a direct date on the artefact would be preferable. During the processes of manufacture, carbon is incorporated into the iron from the fuel source. If the fuel is of a material containing contemporaneous carbon, i.e. has an ambient radiocarbon signature, e.g. charcoal, then we may reliably radiocarbon date the artefact by extracting this carbon. Care must be taken, however, to ensure that re-working has not introduced multiple sources of carbon that would give an erroneous date. Detailed chemical analysis must precede radiocarbon analysis. Sample size is determined by carbon content, and before the advent of accelerator mass spectrometry, several tens of grams of carbon were required for radiocarbon dating (van der Merwe, 1969), prohibiting this method except for high-carbon cast-irons and bulk samples, e.g. caches of nails. AMS permits the analysis of sub-gram pieces of iron (Cresswell, 1991), thereby permitting the analysis of museum pieces with only minimal loss of material, and small fragments of iron recovered from archaeological sites. A few examples are given to illustrate these points

  4. Late-Glacial radiocarbon- and palynostratigraphy in the Swiss Plateau

    International Nuclear Information System (INIS)

    Ammann, B.; Lotter, A.F.

    1989-01-01

    A detailed Late-Glacial radiocarbon stratigraphy for the Swiss Plateau has been established on the basis of over 90 accelerator 14 C dates on terrestrial plant macrofossils. A comparison of the radiocarbon ages derived from terrestrial, telmatic and limnic material at different sites on the Swiss Plateau yields a proposal for modifying the zonation system of Welten for the Late-Glacial. By retaining the limits of chronozones and by refining the palynostratigraphic criteria for the limits of biozones, a separation between chrono- and biozonation at the beginning of the Boelling and the Younger Dryas becomes obvious. 54 refs

  5. Radiocarbon dating of mortars from ancient Greek palaces

    International Nuclear Information System (INIS)

    Zouridakis, N.; Saliege, J.F.; Person, A.; Filippakis, S.E.

    1987-01-01

    The study deals with radiocarbon dating of lime mortars which were used as supports for Mycenaean and Minoan paintings. The 14 C dates are, on the whole, compatible with the historical data, and thus show that a large proportion of the Mycenaean surficial coatings can be dated by the radiocarbon method. However, in order to determine the age of the mortars accurately, it is necessary to evaluate the amount of sedimentary carbonate which may have been added to them. It is shown here that the oxygen and carbon isotope compositions of lime mortars are significant indicators that such a mixing actually took place. (author)

  6. Radiocarbon dating of mortars from ancient Greek palaces

    Energy Technology Data Exchange (ETDEWEB)

    Zouridakis, N.; Saliege, J.F.; Person, A.; Filippakis, S.E.

    1987-02-01

    The study deals with radiocarbon dating of lime mortars which were used as supports for Mycenaean and Minoan paintings. The /sup 14/C dates are, on the whole, compatible with the historical data, and thus show that a large proportion of the Mycenaean surficial coatings can be dated by the radiocarbon method. However, in order to determine the age of the mortars accurately, it is necessary to evaluate the amount of sedimentary carbonate which may have been added to them. It is shown here that the oxygen and carbon isotope compositions of lime mortars are significant indicators that such a mixing actually took place.

  7. Prehistoric peyote use: alkaloid analysis and radiocarbon dating of archaeological specimens of Lophophora from Texas.

    Science.gov (United States)

    El-Seedi, Hesham R; De Smet, Peter A G M; Beck, Olof; Possnert, Göran; Bruhn, Jan G

    2005-10-03

    Two archaeological specimens of peyote buttons, i.e. dried tops of the cactus Lophophora williamsii (Lem.) Coulter, from the collection of the Witte Museum in San Antonio, was subjected to radiocarbon dating and alkaloid analysis. The samples were presumably found in Shumla Cave No. 5 on the Rio Grande, Texas. Radiocarbon dating shows that the calibrated 14C age of the weighted mean of the two individual dated samples corresponds to the calendric time interval 3780-3660 BC (one sigma significance). Alkaloid extraction yielded approximately 2% of alkaloids. Analysis with thin-layer chromatography (TLC) and gas chromatography-mass spectrometry (GC-MS) led to the identification of mescaline in both samples. No other peyote alkaloids could be identified. The two peyote samples appear to be the oldest plant drug ever to yield a major bioactive compound upon chemical analysis. The identification of mescaline strengthens the evidence that native North Americans recognized the psychotropic properties of peyote as long as 5700 years ago.

  8. Time in tortoiseshell: a bomb radiocarbon-validated chronology in sea turtle scutes.

    Science.gov (United States)

    Van Houtan, Kyle S; Andrews, Allen H; Jones, T Todd; Murakawa, Shawn K K; Hagemann, Molly E

    2016-01-13

    Some of the most basic questions of sea turtle life history are also the most elusive. Many uncertainties surround lifespan, growth rates, maturity and spatial structure, yet these are critical factors in assessing population status. Here we examine the keratinized hard tissues of the hawksbill (Eretmochelys imbricata) carapace and use bomb radiocarbon dating to estimate growth and maturity. Scutes have an established dietary record, yet the large keratin deposits of hawksbills evoke a reliable chronology. We sectioned, polished and imaged posterior marginal scutes from 36 individual hawksbills representing all life stages, several Pacific populations and spanning eight decades. We counted the apparent growth lines, microsampled along growth contours and calibrated Δ(14)C values to reference coral series. We fit von Bertalanffy growth function (VBGF) models to the results, producing a range of age estimates for each turtle. We find Hawaii hawksbills deposit eight growth lines annually (range 5-14), with model ensembles producing a somatic growth parameter (k) of 0.13 (range 0.1-0.2) and first breeding at 29 years (range 23-36). Recent bomb radiocarbon values also suggest declining trophic status. Together, our results may reflect long-term changes in the benthic community structure of Hawaii reefs, and possibly shed light on the critical population status for Hawaii hawksbills. © 2016 The Author(s).

  9. Radiocarbon dating of Irish Sea sediments

    Science.gov (United States)

    Kershaw, P. J.

    1986-09-01

    Radiocarbon dating has been carried out on three cores from areas of muddy sediments in the N. Irish Sea to estimate rates of sediment accumulation. 14C age profiles of the two eastern basin cores revealed a near-constant age from the sediment surface to the base of the core (12 500±1000 years bp). The 14C age profile of the western basin core revealed a zone of apparent mixing to a depth of 55 cm, underlain by a zone of constant sedimentation rate (0·018 cm y -1) to 160 cm. These data are discussed in relation both to previously reported sedimentological studies of the area and to the authorised discharges of low-level radioactive waste from the Sellafield nuclear fuel reprocessing plant.

  10. Solar Flare Track Exposure Ages in Regolith Particles: A Calibration for Transmission Electron Microscope Measurements

    Science.gov (United States)

    Berger, Eve L.; Keller, Lindsay P.

    2015-01-01

    Mineral grains in lunar and asteroidal regolith samples provide a unique record of their interaction with the space environment. Space weathering effects result from multiple processes including: exposure to the solar wind, which results in ion damage and implantation effects that are preserved in the rims of grains (typically the outermost 100 nm); cosmic ray and solar flare activity, which result in track formation; and impact processes that result in the accumulation of vapor-deposited elements, impact melts and adhering grains on particle surfaces. Determining the rate at which these effects accumulate in the grains during their space exposure is critical to studies of the surface evolution of airless bodies. Solar flare energetic particles (mainly Fe-group nuclei) have a penetration depth of a few millimeters and leave a trail of ionization damage in insulating materials that is readily observable by transmission electron microscope (TEM) imaging. The density of solar flare particle tracks is used to infer the length of time an object was at or near the regolith surface (i.e., its exposure age). Track measurements by TEM methods are routine, yet track production rate calibrations have only been determined using chemical etching techniques [e.g., 1, and references therein]. We used focused ion beam-scanning electron microscope (FIB-SEM) sample preparation techniques combined with TEM imaging to determine the track density/exposure age relations for lunar rock 64455. The 64455 sample was used earlier by [2] to determine a track production rate by chemical etching of tracks in anorthite. Here, we show that combined FIB/TEM techniques provide a more accurate determination of a track production rate and also allow us to extend the calibration to solar flare tracks in olivine.

  11. High-resolution dating of ancient ceramic kilns in Thailand, Laos and Burma by radiocarbon and palaeomagnetism

    International Nuclear Information System (INIS)

    Barbetti, M.; Hein, D.

    1997-01-01

    Full text: Radiocarbon dating is widely used on organic samples, especially wood, charcoal and bone. Classical techniques use samples of several grams, but only a few milligrams is needed for measurements by Accelerator Mass Spectrometry (AMS). Palaeomagnetic techniques are readily applicable to the study of ancient kilns. Core samples are drilled from the walls and floors, and oriented before being detached and measured on a sensitive spinner magnetometer in a laboratory. Resolution of a quarter of a century at 95% confidence can be achieved in favourable circumstances but only at certain periods of time. Radiocarbon dating shows that the earliest stoneware ceramics are from the 11th - 12th centuries AD and palaeomagnetism indicates that many in-ground kilns are of this age. Kilns of this type, which were hollowed out in sediments near river banks or old terraces, are found near Sisatchanalai in north-central Thailand and near Luang Prabang in northern Laos; they are similar in age to the Khmer-type kilns found at Suphanburi in central Thailand. A different type of kiln, constructed of bricks and located above-ground, appears towards the end of the 13th century AD. One of the earliest surface kilns at Sisatchanalai has a well determined date of 1290 ± 15 AD (calibrated radiocarbon age, 95% confidence).There is an overlap of the two technologies; stratigraphy and palaeomagnetic results show that in-ground and above-ground brick kilns continue almost side-by-side throughout the 14th century AD. One of the latest in-ground kilns at Sisatchanalai has a date of 1410 ± 25 AD (calibrated radiocarbon age, 95% confidence). There are many brick kilns belonging to the l5th century AD at Sisatchanalai, and they appear then at other sites in north-central Thailand (e.g., Sukhothai and Phitsanulok) and in Burma (e.g., Lagumbyee). In-ground kilns continue to be used in northern Laos even in the 15th century AD. The latest brick kilns at Sisatchanalai are 16th and possibly 17th

  12. Calibrating the Cryogenian

    Science.gov (United States)

    MacDonald, F. A.; Schmitz, M. D.; Crowley, J. L.; Haam, E.; Huybers, P.; Cohen, P. A.; Johnston, D. T.

    2009-12-01

    The IGCP 512 sub-commission on the Neoproterozoic is currently discussing criteria for the definition of the Cryogenian period. Herein we provide new U/Pb ID-TIMS ages and carbon and oxygen isotope data from Fifteenmile and Mt. Harper Groups in the Yukon Territory that inform the basis for the placement of the basal Cryogenian “golden spike”. Our U/Pb ages are from volcanic tuffs interbedded within glaciogenic, fossiliferous, and carbonate strata. With the current lack of Neoproterozoic index fossils and the paucity of radiogenic age constraints, chemo-stratigraphic correlations are particularly important for tuning the Neoproterozoic timescale. In an effort to move beyond conventional 'wiggle matching', chemostratigraphic correlations are determined using a new statistical method1, which indicates that the resulting chemo-stratigraphic correlations are statistically significant. These results permit us to refine and integrate Neoproterozoic climate, microfossil, and geochemical proxy records both regionally and globally. The newly calibrated microfossil record points to a eukaryotic radiation roughly coincident with the Bitter Springs isotopic stage and a barren interval between the Sturtian and Marinoan glaciations. 1 Haam, E. & Huybers, P., 2009, A test for the presence of covariance between time-uncertain series of data with applications to the Dongge Cave speleothem and atmospheric radiocarbon records, Paleoceanography, in press.

  13. Age estimations of wild pallid sturgeon (Scaphirhynchus albus, Forbes & Richardson 1905) based on pectoral fin spines, otoliths and bomb radiocarbon: inferences on recruitment in the dam-fragmented Missouri River

    Science.gov (United States)

    Braaten, P. J.; Campana, S. E.; Fuller, D. B.; Lott, R. D.; Bruch, R. M.; Jordan, G. R.

    2015-01-01

    An extant stock of wild pallid sturgeon Scaphirhynchus albus persists in the fragmented upper Missouri River basin of Montana and North Dakota. Although successful spawning and hatch of embryos has been verified, long-term catch records suggest that recruitment has not occurred for several decades as the extant stock lacks juvenile size classes and is comprised exclusively of large, presumably old individuals. Ages of 11 deceased (death years 1997–2007) wild S. albus (136–166 cm fork length) were estimated based on pectoral fin spines, sagittal otoliths and bomb radiocarbon (14C) assays of otoliths to test the hypothesis that members of this stock are old and to provide inferences on recruitment years that produced the extant stock. Age estimations based on counts of presumed annuli were about 2 years greater for otoliths (mean = 51 years, range = 43–57 years) than spines (mean = 49 years, range = 37–59 years). Based on 14C assays, confirmed birth years for all individuals occurred prior to 1957, thus establishing known longevity of at least 50 years. Estimated age based on presumed otolith annuli for one S. albus was validated to at least age 49. Although 14C assays confirmed pre-1957 birth years for all S. albus, only 56% of estimated ages from spines and 91% of estimated ages from otoliths depicted pre-1957 birth years. Both ageing structures were subject to under-ageing error (up to 15 years). Lack of or severe curtailment of S. albus recruitment in the upper Missouri River basin since the mid-1950s closely parallels the 1953–1957 timeframe when a mainstem reservoir was constructed and started to fill. This reservoir may function as a system-wide stressor to diminish recruitment success of S. albus in the upper Missouri River basin.

  14. Radiocarbon intercomparison program for Chauvet Cave

    International Nuclear Information System (INIS)

    Cuzange, M.T.; Delque-Kolic, E.; Oberlin, C.; Goslar, T.; Grootes, P.M.; Nadeau, M.J.; Higham, T.; Ramsey, C.B.; Kaltnecker, E.; Paterne, M.; Valladas, H.; Van der Plicht, J.; Van der Plicht, J.; Clottes, J.; Geneste, J.M.

    2007-01-01

    We present the first results of an accelerator mass spectrometry (AMS) radiocarbon intercomparison program on 3 different charcoal samples collected in one of the hearths of the Megaceros gallery of Chauvet Cave (Ardeche, France). This cave, rich in parietal decoration, is important for the study of the appearance and evolution of prehistoric art because certain drawings have been 14 C dated to the Aurignacian period at the beginning of the Upper Paleolithic. The new dates indicate an age of about 32,000 BP, which is consistent with this attribution and in agreement with the results from the same sector of the cave measured previously at the Laboratoire des Sciences du Climat et de l'Environnement (LSCE). Six laboratories were involved in the intercomparison. Samples were measured in 4 AMS facilities: Center for Isotope Research, Groningen University, the Netherlands; the Oxford Radiocarbon Accelerator Unit, UK; the Centre de datation par le carbone 14, Univ. Claude Bernard Lyon 1, France (measured by AMS facilities of Poznan University, Poland); and the LSCE, UMR CEA-CNRS-UVSQ, France (measured by the Leibniz-Labor of Christian-Albrechts-Universitat Kiel, Germany). (authors)

  15. Dating the humans by radiocarbon

    International Nuclear Information System (INIS)

    Fedi, M.E.

    2011-01-01

    Radiocarbon has become a very powerful tool used for dating. This paper deals with a specific application of 1 4C i.e. dating of humans. Attention is focused on those aspects that, if neglected, might lead to a misinterpretation of the results or to an unsatisfying accuracy of the measurement. After a brief description of the main principles on which the radiocarbon method is based and of Accelerator Mass Spectrometry, examples taken from the research activity of INFN-LABEC (Laboratorio di Tecniche Nucleari per I Beni Culturali) in Florence are presented. The case of the relic of St. Francis represents an example of dating not directly human remains but other objects that can be associated to them. The case of two burials from the archaeological area of Baratti-Populonia, in Tuscany, gives the possibility to show the importance of estimating the human palaeodiet when dating bone samples.

  16. Moving beyond the age-depth model paradigm in deep sea palaeoclimate archives: dual radiocarbon and stable isotope analysis on single foraminifera

    NARCIS (Netherlands)

    Lougheed, Bryan C.; Metcalfe, Brett; Ninnemann, Ulysses S.; Wacker, Lukas

    2017-01-01

    Late-glacial palaeoclimate reconstructions from deep-sea sediment archives provide valuable insight into past rapid changes in ocean chemistry, but only a small proportion of the ocean floor is suitable for such reconstructions using the existing state-of-the-art using the age-depth approach. We

  17. Radiocarbon dating of planktonic foraminifer shells: A cautionary tale

    Science.gov (United States)

    Mekik, Figen

    2014-01-01

    rate, bioturbation, winnowing, and calcite dissolution produce significant radiocarbon age offsets among multiple species of coexisting planktonic foraminifers and pteropod fragments. We compare the radiocarbon age of foraminifer species and pteropod fragments with estimates of percent calcite dissolved made with a sedimentary proxy (Globorotalia menardii fragmentation index—MFI) to delineate the effect of dissolution on radiocarbon age of foraminifers. Data from two core top transects on the Rio Grande Rise (RIO) and Ontong Java Plateau (OJP) and from down core sediments of varying sedimentation rates in the tropical Pacific (ME-27, MD98 2177, and MW91-9 56GGC) reveal that sediments with the greatest accumulation rates produce the least age offsets among coexisting species. Age offsets among coexisting foraminifers are about 3500 years on RIO, and 1000 years on OJP. Two core tops from RIO yield an age of the Last Glacial Maximum possibly due to mass displacement of younger sediments downslope. Foraminifer age increases with increasing dissolution and there is a consistent pattern of older foraminifer fragments coexisting with younger whole shells of the same species. The only exception is sediments which have experienced high dissolution where fragments are younger than whole shells. The age offset between fragments of G. menardii and its coexisting whole shells does not exceed the age offset among other coexisting foraminifer species in the same core tops.

  18. Radiocarbon dating methods using benzene liquid scintillation

    International Nuclear Information System (INIS)

    Togashi, Shigeko; Matsumoto, Eiji

    1983-01-01

    The radiocarbon dating method using benzene liquid scintillation is reported in detail. The results of measurement of NBS oxalic acid agree with the recommended value, indicating that isotopic fractionation during benzene synthesis can be negligible. Ten samples which have been already measured by gas counter are dated by benzene liquid scintillation. There is no significant difference in age for the same sample between benzene liquid scintillation and gas counters. It is shown that quenching has to be corrected for the young sample. Memory effect in stainless steel reaction vessel can be removed by using an exchangeable inner vessel and by baking it in the air. Using this method, the oldest age that can be measured with 2.3 g carbon is 40,000 years B.P. (author)

  19. LBA-ECO CD-08 Radiocarbon Dates for Large Trees from a Forest near Manaus, Brazil

    Data.gov (United States)

    National Aeronautics and Space Administration — This data set reports the ages and growth rates of trees as determined by radiocarbon dating (14C), selected from a logging operation near the city of Itacoatiara,...

  20. LBA-ECO CD-08 Radiocarbon Dates for Large Trees from a Forest near Manaus, Brazil

    Data.gov (United States)

    National Aeronautics and Space Administration — ABSTRACT: This data set reports the ages and growth rates of trees as determined by radiocarbon dating (14C), selected from a logging operation near the city of...

  1. Radiocarbon and cation-radio ages for rock varnish on Tioga and Tahoe marainal boulders of Pine Creek, eastern Sierra Nevada, California, and their paleoclimatic implications

    Science.gov (United States)

    Dorn, R.I.; Turrin, B.D.; Jull, A.J.T.; Linick, T.W.; Donahue, D.J.

    1987-01-01

    Accelerator mass spectrometry 14C analyses of organic matter extracted from rock varnishes on morainal boulders yield limiting minimum ages for three crests of the Tioga glaciation. At Pine Creek in the eastern Sierra Nevada, varnish started to form on boulders of the outermost Tioga moraine before 19,000 yr B.P., and varnish originated on the innermost Tioga moraine before 13,200 yr B.P. Comparisons with lake-level, paleohydrological, paleoecological, colluvial, and rock varnish micromorphological data indicate that central-eastern California and western Nevada experienced a moisture-effective period during the late Pleistocene but after the Tioga maximum, and perhaps as Tioga glaciers receded from the mouth of Pine Creek canyon. Varnishes on Tahoeage morainal boulders at Pine Creek have cation-ratio ages of about 143,000-156,000 yr B.P., suggesting that the Tahoe glaciation should not be correlated with oxygen-isotope stage 4 in the early Wisconsin, but rather with stage 6. Varnishes on morainal boulders of an older glaciation at Pine Creek are dated by cation ratio at about 182,000-187,000 yr B.P. ?? 1987.

  2. Investigating bomb radiocarbon transport in the southern Pacific Ocean with otolith radiocarbon

    Science.gov (United States)

    Grammer, G. L.; Fallon, S. J.; Izzo, C.; Wood, R.; Gillanders, B. M.

    2015-08-01

    To explore the transport of carbon into water masses from the surface ocean to depths of ∼ 1000 m in the southwest Pacific Ocean, we generated time series of radiocarbon (Δ14C) from fish otoliths. Otoliths (carbonate earstones) from long-lived fish provide an indirect method to examine the "bomb pulse" of radiocarbon that originated in the 1950s and 1960s, allowing identification of changes to distributions of 14C that has entered and mixed within the ocean. We micro-sampled ocean perch (Helicolenus barathri) otoliths, collected at ∼ 400- 500 m in the Tasman Sea, to obtain measurements of Δ14C for those depths. We compared our ocean perch Δ14C series to published otolith-based marine surface water Δ14C values (Australasian snapper (Chrysophrys auratus) and nannygai (Centroberyx affinis)) and to published deep-water values (800-1000 m; orange roughy (Hoplostethus atlanticus)) from the southwest Pacific to establish a mid-water Δ14C series. The otolith bomb 14C results from these different depths were consistent with previous water mass results in the upper 1500 m of the southwest Pacific Ocean (e.g. World Ocean Circulation Experiment and Geochemical Ocean Sections Study). A comparison between the initial Δ14C bomb pulse rise at 400-500 m suggested a ventilation lag of 5 to 10 yr, whereas a comparison of the surface and depths of 800-1000 m detailed a 10 to 20 yr lag in the time history of radiocarbon invasion at this depth. Pre-bomb reservoir ages derived from otolith 14C located in Tasman Sea thermocline waters were ∼ 530 yr, while reservoir ages estimated for Tasman Antarctic intermediate water were ∼ 730 yr.

  3. AMS radiocarbon dating of 'Grotta Cappuccini' in Southern Italy

    International Nuclear Information System (INIS)

    Quarta, G.; Calcagnile, L.; D'Elia, M.; Rizzo, A.; Ingravallo, E.

    2004-01-01

    We present the results of AMS radiocarbon dating of human bones recovered in 'Grotta Cappuccini', a prehistoric cave in Galatone, Lecce (Southern Italy). The AMS analysis has confirmed the archaeological dating of the cave to the period between the end of the Copper Age and the early Bronze Age, and has given a fundamental contribution to the chronological definition of an important cultural aspect of the prehistory of Southern Italy

  4. Radiocarbon ages of archeological remains related with the 13th century Mongol Invasion to Japan. Shell samples collected near Mongolian submerged wrecks located off Takashima, Nagasaki prefecture, Japan

    International Nuclear Information System (INIS)

    Nakamura, Toshio

    2013-01-01

    The shallow sea floor off Takashima, Matsuura, Nagasaki Prefecture, has been investigated archeologically as a potential site where many fragments of broken Mongolian warships may exist below the sea sediments. It is historically recorded that more than 4,000 Mongolian warships were destroyed by a typhoon during the Mongol Invasion to Japan in 1281. The underwater investigations have been performed since 1980, and a lot of archeological remains related with the invasion have been collected there. Recently a body of submerged wrecks most probably originated from Mongolian warship has been discovered in the 1m-deep horizon of the sea sediment off Takashima. During the survey of the newly discovered warship, shell samples were collected near the ship. Some shells were recognized to be hull-fouling species, which may have grown up on the bottom of Mongolian warship and preserved along with the broken ship in the sea sediment. We have conducted 14 C dating for some shell samples and found out that shells belong to hull-fouling species showed 14 C ages consistent with the time of Mongol Invasion. Some other shells not belonging to hull-fouling species showed younger or older dates as compared with the time of Mongol Invasion. (author)

  5. Status of mass spectrometric radiocarbon detection at ETHZ

    Energy Technology Data Exchange (ETDEWEB)

    Seiler, Martin; Maxeiner, Sascha; Wacker, Lukas; Synal, Hans-Arno

    2015-10-15

    A prototype of a mass spectrometric radiocarbon detection instrument without accelerator stage was built for the first time and set into operation at ETH Zurich. The system is designed as an experimental platform to optimize performance of {sup 14}C detection at low ion energies and to study the most relevant processes that may limit system performance. The optimized stripper unit incorporates differential pumping to maintain a low gas outflow and a revised tube design to better match the phase space volume of the ion beam at low energies. The system is fully operational and has demonstrated true radiocarbon dating capabilities. The overall beam transmission through the stripper tube is about 40% for the 1{sup +} charge state. Radiocarbon analyses with an overall precision of 0.6% were obtained on a single sample under regular measurement conditions. By analyzing multiple targets of the same sample material an uncertainty level of 0.3% has been reached. The background level corresponds to a radiocarbon age of 40,000 years.

  6. Radiocarbon positive-ion mass spectrometry

    International Nuclear Information System (INIS)

    Freeman, Stewart P.H.T.; Shanks, Richard P.; Donzel, Xavier; Gaubert, Gabriel

    2015-01-01

    Proof-of-principle of a new mass spectrometric technique for radiocarbon measurement is demonstrated. Interfering nitrogen and hydrocarbon molecules are largely eliminated in a charge-exchange cell operating on non-metallic gas. The positive-to-negative ion conversion is the reverse of that conventionally used in accelerator mass spectrometry (AMS) and is compatible with plasma ion sources that may be significantly more efficient and capable of greater output than are AMS sputter ion sources. The Nanogan electron cyclotron resonance (ECR) ion source employed exhibited no sample memory and the >50 kyrs age range of AMS was reproduced. A bespoke prototype new instrument is now required to optimise the plasma and cell physics and to realise hypothetical performance gains over AMS.

  7. Radiocarbon positive-ion mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Freeman, Stewart P.H.T.; Shanks, Richard P. [Scottish Universities Environmental Research Centre (SUERC), Scottish Enterprise Technology Park, East Kilbride G75 0QF (United Kingdom); Donzel, Xavier; Gaubert, Gabriel [Pantechnik S.A., 13 Rue de la Résistance, 14400 Bayeux (France)

    2015-10-15

    Proof-of-principle of a new mass spectrometric technique for radiocarbon measurement is demonstrated. Interfering nitrogen and hydrocarbon molecules are largely eliminated in a charge-exchange cell operating on non-metallic gas. The positive-to-negative ion conversion is the reverse of that conventionally used in accelerator mass spectrometry (AMS) and is compatible with plasma ion sources that may be significantly more efficient and capable of greater output than are AMS sputter ion sources. The Nanogan electron cyclotron resonance (ECR) ion source employed exhibited no sample memory and the >50 kyrs age range of AMS was reproduced. A bespoke prototype new instrument is now required to optimise the plasma and cell physics and to realise hypothetical performance gains over AMS.

  8. Radiocarbon dating with accelerator mass spectrometry

    International Nuclear Information System (INIS)

    Blake, W. Jr.

    1985-01-01

    Radiocarbon dating by means of accelerator mass spectrometry (AMS) has two great advantages over conventional dating: 1) much smaller samples can be handled and 2) counting time is significantly shorter. Three examples are given for Holocene-age material from east-central Ellesmere Island. The results demonstrate the potential use of this technique as a powerful research tool in studies of Quaternary chronology. Individual fragments of marine shells as small as 0.1 g have been dated successfully at the IsoTrace Laboratory, University of Toronto. In the case of an aquatic moss from a lake sediment core, an increment 0.5 cm thick could be used instead of a 5 cm-thick slice, thus allowing a much more precise estimate of the onset of organic sedimentation

  9. Radiocarbon dating of soils, a review

    International Nuclear Information System (INIS)

    Scharpenseel, H.W.; Schiffmann, H.

    1977-01-01

    The application of radiocarbon dating techniques for pedological purposes is reviewed in chronological sequence of its phases of introduction. Initially dating of charcoal and buried paleosols was dominating and accompanied by few soil dating attempts of recent soil formations on the basis of extracted humic acid-C. The following controversy regarding the potentialities and limitations of recent soil dating, still being involved in the intact turnover processes of modern biodynamics, led to intensive search for the relatively oldest, most favorable C-fraction, particularly a biologically inert C-fraction of the organic C-pool. Inclusion of C-14 dating in pedogenetic working concepts required soil profile date-scanning in order to reveal the age versus depth interdependence. (orig./HK) [de

  10. Improved precision radiocarbon measurements and natural 14C variations around 10.000 cal BP

    International Nuclear Information System (INIS)

    Goslar, T.

    1990-01-01

    The subject of present work, natural radiocarbon variations in the past, is one of the most significant methodological questions of radiocarbon chronology. In the first three chapters, the author discusses problems connected with calibration of conventional radiocarbon dates, and consequences of monitoring the 14 C variations for the research of the changes of geomagnetic field, solar activity and global carbon cycle. Dendrochronological dating, which, in connection with 14 C measurements enables us to reconstruct the radiocarbon variations in the past, is also widely described. Fourth chapter concerns the technical problems of detection 14 C β-activity, especially accounting for proportional counters technique. In the next chapter the author describes results of his own dendrochonological research. Sixth chapter comprises frame discussion of the system for improved precision radiocarbon dating, together with short presentation of equipment, its calibration and analysis of errors. The last chapter gives the reconstruction of the pattern of atmospheric 14 C variations in 300-year period around 10.000 cal BP. It was found that in the last 10.000 years similar pattern repeats periodically. In the end, the author discusses the meaning of negative correlation between 14 C variations and changes of annual tree-ring widths in the oak trunk from Lublinek, for searching the connection between solar activity and climate. (author)

  11. ZAGRADA - A New Radiocarbon Database

    International Nuclear Information System (INIS)

    Portner, A.; Obelic, B.; Krajcar Bornic, I.

    2008-01-01

    In the Radiocarbon and Tritium Laboratory at the Rudjer Boskovic Institute three different techniques for 14C dating have been used: Gas Proportional Counting (GPC), Liquid Scintillation Counting (LSC) and preparation of milligram-sized samples for AMS dating (Accelerator Mass Spectrometry). The use of several measurement techniques has initiated a need for development of a new relational database ZAGRADA (Zagreb Radiocarbon Database) since the existing software package CARBO could not satisfy the requirements for parallel processing/using of several techniques. Using the SQL procedures, and constraints defined by primary and foreign keys, ZAGRADA enforces high data integrity and provides better performances in data filtering and sorting. Additionally, the new database for 14C samples is a multi-user oriented application that can be accessed from remote computers in the work group providing thus better efficiency of laboratory activities. In order to facilitate data handling and processing in ZAGRADA, the graphical user interface is designed to be user-friendly and to perform various actions on data like input, corrections, searching, sorting and output to printer. All invalid actions performed in user interface are registered with short textual description of an error occurred and appearing on screen in message boxes. Unauthorized access is also prevented by login control and each application window has implemented support to track last changes made by the user. The implementation of a new database for 14C samples has significant contribution to scientific research performed in the Radiocarbon and Tritium Laboratory and will provide better and easier communication with customers.(author)

  12. Radiocarbon dating of ancient Japanese calligraphy sheets and the discovery of 45 letters of a lost manuscript

    Energy Technology Data Exchange (ETDEWEB)

    Oda, H. [Nagoya Univ. (Japan). Center for Chronological Research; Yasu, H. [Taga High School, Hitachi, Ibaragi (Japan); Ikeda, K. [Chuo Univ., Tokyo (Japan). Faculty of Letters; Sakamoto, M. [National Museum of Japanese History, Sakura, Chiba (Japan); Yoshizawa, Y.

    2011-07-01

    The Miidera-gire is an ancient paper sheet with different, elegant calligraphy on both sides. One side contains a part of a Buddhist scripture from around the ninth to the twelfth century and written in cursive hand, while the other side contains a part of Monzen (an anthology of Chinese literary works). The paleographical style of this Monzen seems to be older than that of the Buddhist scripture and is similar to some Chinese manuscripts written in the Tang Dynasty (AD 618-907). However, amid these elegant calligraphic writings, there exist many copies and counterfeits that were written several centuries later. We, therefore, measured the radiocarbon age of the Miidera-gire by using accelerator mass spectrometry. The calibrated radiocarbon age indicated 666-776 [cal AD] (2{sigma} error), thus leading to the conclusion that the Monzen was first written on the obverse side, and long afterwards, the Buddhist scripture was written on the reverse side. Since only a few incomplete books of Monzen were written before the ninth century, this calligraphy is one of the oldest of the existing Monzen manuscripts. (orig.)

  13. Radiocarbon dating of ancient Japanese calligraphy sheets and the discovery of 45 letters of a lost manuscript

    International Nuclear Information System (INIS)

    Oda, H.; Ikeda, K.; Yoshizawa, Y.

    2011-01-01

    The Miidera-gire is an ancient paper sheet with different, elegant calligraphy on both sides. One side contains a part of a Buddhist scripture from around the ninth to the twelfth century and written in cursive hand, while the other side contains a part of Monzen (an anthology of Chinese literary works). The paleographical style of this Monzen seems to be older than that of the Buddhist scripture and is similar to some Chinese manuscripts written in the Tang Dynasty (AD 618-907). However, amid these elegant calligraphic writings, there exist many copies and counterfeits that were written several centuries later. We, therefore, measured the radiocarbon age of the Miidera-gire by using accelerator mass spectrometry. The calibrated radiocarbon age indicated 666-776 [cal AD] (2σ error), thus leading to the conclusion that the Monzen was first written on the obverse side, and long afterwards, the Buddhist scripture was written on the reverse side. Since only a few incomplete books of Monzen were written before the ninth century, this calligraphy is one of the oldest of the existing Monzen manuscripts. (orig.)

  14. Compound-specific radiocarbon analysis - Analytical challenges and applications

    Science.gov (United States)

    Mollenhauer, G.; Rethemeyer, J.

    2009-01-01

    Within the last decades, techniques have become available that allow measurement of isotopic compositions of individual organic compounds (compound-specific isotope measurements). Most often the carbon isotopic composition of these compounds is studied, including stable carbon (δ13C) and radiocarbon (Δ14C) measurements. While compound-specific stable carbon isotope measurements are fairly simple, and well-established techniques are widely available, radiocarbon analysis of specific organic compounds is a more challenging method. Analytical challenges include difficulty obtaining adequate quantities of sample, tedious and complicated laboratory separations, the lack of authentic standards for measuring realistic processing blanks, and large uncertainties in values of Δ14C at small sample sizes. The challenges associated with sample preparation for compound-specific Δ14C measurements will be discussed in this contribution. Several years of compound-specific radiocarbon analysis have revealed that in most natural samples, purified organic compounds consist of heterogeneous mixtures of the same compound. These mixtures could derive from multiple sources, each having a different initial reservoir age but mixed in the same terminal reservoir, from a single source but mixed after deposition, or from a prokaryotic organism using variable carbon sources including mobilization of ancient carbon. These processes not only represent challenges to the interpretation of compound-specific radiocarbon data, but provide unique tools for the understanding of biogeochemical and sedimentological processes influencing the preserved organic geochemical records in marine sediments. We will discuss some examples where compound-specific radiocarbon analysis has provided new insights for the understanding of carbon source utilization and carbon cycling.

  15. Microscale radiocarbon dating of paintings

    International Nuclear Information System (INIS)

    Hendriks, Laura; Hajdas, Irka; McIntyre, Cameron; Kueffner, Markus; Ferreira, Ester S.B.; Scherrer, Nadim C.

    2016-01-01

    In this paper, radiocarbon dating of paintings using minimal sample sizes has been investigated, in an effort to address the problem of limited access to sample material in paintings. 14 C analyses were conducted on signed and dated paintings from two Swiss artists of the twentieth century. The selected paintings dated from the 1930s and 1960s, provided the opportunity to evaluate the dating accuracy on paintings realized before and after 1950 AD when the 14 C bomb peak was created, as a result of the nuclear tests conducted in the 1950/1960s. The work focused on the one hand on minimizing the size of the canvas sample required for accelerator mass spectrometer radiocarbon measurement on the gas ion source of the MICADAS and, on the other hand, on testing the possibility of dating the organic binder of the paint. Following careful characterization of the paint composition by X-ray fluorescence spectroscopy, Fourier transformed infrared spectroscopy, and Raman spectroscopy, paints containing no other carbon source than the natural organic binder were identified and dated. (orig.)

  16. Microscale radiocarbon dating of paintings

    Energy Technology Data Exchange (ETDEWEB)

    Hendriks, Laura; Hajdas, Irka; McIntyre, Cameron [ETH Zurich, Ion Beam Physics, Zurich (Switzerland); Kueffner, Markus; Ferreira, Ester S.B. [SIK-ISEA, Zurich, Zurich (Switzerland); Scherrer, Nadim C. [Bern University of Applied Sciences, HKB, Bern (Switzerland)

    2016-03-15

    In this paper, radiocarbon dating of paintings using minimal sample sizes has been investigated, in an effort to address the problem of limited access to sample material in paintings. {sup 14}C analyses were conducted on signed and dated paintings from two Swiss artists of the twentieth century. The selected paintings dated from the 1930s and 1960s, provided the opportunity to evaluate the dating accuracy on paintings realized before and after 1950 AD when the {sup 14}C bomb peak was created, as a result of the nuclear tests conducted in the 1950/1960s. The work focused on the one hand on minimizing the size of the canvas sample required for accelerator mass spectrometer radiocarbon measurement on the gas ion source of the MICADAS and, on the other hand, on testing the possibility of dating the organic binder of the paint. Following careful characterization of the paint composition by X-ray fluorescence spectroscopy, Fourier transformed infrared spectroscopy, and Raman spectroscopy, paints containing no other carbon source than the natural organic binder were identified and dated. (orig.)

  17. Radiocarbon dating of an ancient Japanese document 'Minamoto no Yoritomo Sodehan Migyosho' by accelerator mass spectrometry

    International Nuclear Information System (INIS)

    Oda, H.; Nakamura, T.; Masuda, T.

    2007-01-01

    We measured radiocarbon age of an ancient document 'Minamoto no Yoritomo Sodehan Migyosho'. The content tells that it was issued in 1189 by 'Minamoto no Yoritomo' known as the virtually first shogun in Japan to grant 'Matsugi' family the privilege of controlling craftsmen of foundry industry. Paleographical views, however, suggested that it can be a counterfeit. The radiocarbon dating clarified that the document was written not in the 12 th but after the 16 th century. (author)

  18. Atmospheric radiocarbon variations 11,000 years ago

    Energy Technology Data Exchange (ETDEWEB)

    Hajdas, I.; Bonani, G. [Eidgenoessische Technische Hochschule, Zurich (Switzerland); Peteet, D. [LDEO of Columbia Univ. (United States); Boden, P. [Stockholm Univ. (Sweden)

    1997-09-01

    Records of climate changes were {sup 14}C dated using AMS method. High resolution dating allowed reconstruction of the atmospheric {sup 14}C variations at the time of deglaciation. An abrupt rise of up to 100%o in the atmospheric {sup 14}C/{sup 12}C ratio was found at 11`000 BP (radiocarbon age) which coincides with the limit of an abrupt cooling and a decrease in ocean ventilation. (author) 1 fig., 6 refs.

  19. Making a date with radiocarbon

    International Nuclear Information System (INIS)

    Gribbin, J.

    1979-01-01

    The use of 14 C dating techniques for samples of organic materials up to 50,000 years old is discussed with especial reference to adjustment necessary to take account of both the most recent figure for the 14 C half-life and also the natural fluctuations in the production of 14 C over 50,000 years. Methods of detection and the accuracy of the measurements are considered. It is hoped that future developments including both the possibility of counting 14 C ions directly using an accelerator as a mass spectrometer, and also the use of laser enrichment techniques will not only push back the radiocarbon calendar to 100,000 years but will also allow the use of much smaller samples than before. (U.K.)

  20. Cosmogonic radiocarbon in the Earth atmosphere

    International Nuclear Information System (INIS)

    Dergachev, V.A.

    1981-01-01

    The state and prospects of studying some processes in nature (cosmic ray intensity variations on a long time scale, mainly) using radiocarbon methods are discussed. The problem of radiocarbon preparation in exchange geochemical tanks is considered. It is noted that a set of dendrochronological and nuclear methods for analyzing tree rings is a powerful instrument for studying different processes in nature. The measurement results of radiocarbon concentration in dated wood samples for the last approximately 8000 years are presented. The relation between different indices of solar activity and the rate of radiocarbon production for separate solar cycles is investigated. The production rate variation both for separate cycles and long periods is estimated. The results of investigations lead to the conclusion that 11-year, secular, more durable peculiarities in the run of radiocarbon activity variations in the atmospheric reservoir can be explained by solar origin. The analysis of the experimental data on radiocarbon permit to compare the radiocarbon concentration variations with magnetic or solar activity [ru

  1. Earliest Human Presence in North America Dated to the Last Glacial Maximum: New Radiocarbon Dates from Bluefish Caves, Canada.

    Directory of Open Access Journals (Sweden)

    Lauriane Bourgeon

    Full Text Available The timing of the first entry of humans into North America is still hotly debated within the scientific community. Excavations conducted at Bluefish Caves (Yukon Territory from 1977 to 1987 yielded a series of radiocarbon dates that led archaeologists to propose that the initial dispersal of human groups into Eastern Beringia (Alaska and the Yukon Territory occurred during the Last Glacial Maximum (LGM. This hypothesis proved highly controversial in the absence of other sites of similar age and concerns about the stratigraphy and anthropogenic signature of the bone assemblages that yielded the dates. The weight of the available archaeological evidence suggests that the first peopling of North America occurred ca. 14,000 cal BP (calibrated years Before Present, i.e., well after the LGM. Here, we report new AMS radiocarbon dates obtained on cut-marked bone samples identified during a comprehensive taphonomic analysis of the Bluefish Caves fauna. Our results demonstrate that humans occupied the site as early as 24,000 cal BP (19,650 ± 130 14C BP. In addition to proving that Bluefish Caves is the oldest known archaeological site in North America, the results offer archaeological support for the "Beringian standstill hypothesis", which proposes that a genetically isolated human population persisted in Beringia during the LGM and dispersed from there to North and South America during the post-LGM period.

  2. Earliest Human Presence in North America Dated to the Last Glacial Maximum: New Radiocarbon Dates from Bluefish Caves, Canada.

    Science.gov (United States)

    Bourgeon, Lauriane; Burke, Ariane; Higham, Thomas

    2017-01-01

    The timing of the first entry of humans into North America is still hotly debated within the scientific community. Excavations conducted at Bluefish Caves (Yukon Territory) from 1977 to 1987 yielded a series of radiocarbon dates that led archaeologists to propose that the initial dispersal of human groups into Eastern Beringia (Alaska and the Yukon Territory) occurred during the Last Glacial Maximum (LGM). This hypothesis proved highly controversial in the absence of other sites of similar age and concerns about the stratigraphy and anthropogenic signature of the bone assemblages that yielded the dates. The weight of the available archaeological evidence suggests that the first peopling of North America occurred ca. 14,000 cal BP (calibrated years Before Present), i.e., well after the LGM. Here, we report new AMS radiocarbon dates obtained on cut-marked bone samples identified during a comprehensive taphonomic analysis of the Bluefish Caves fauna. Our results demonstrate that humans occupied the site as early as 24,000 cal BP (19,650 ± 130 14C BP). In addition to proving that Bluefish Caves is the oldest known archaeological site in North America, the results offer archaeological support for the "Beringian standstill hypothesis", which proposes that a genetically isolated human population persisted in Beringia during the LGM and dispersed from there to North and South America during the post-LGM period.

  3. Radiocarbon dates for the earliest period of habitation in the Baltic States

    International Nuclear Information System (INIS)

    Zagorska, I.

    2003-01-01

    Hitherto, the Stone age of the East Baltic was known for its series of Late Mesolithic - Early Neolithic dates, but over the past decade the number of the dates for the Middle Stone Age and the Final Palaeolithic has also increased. The article brings together the published Palaeolithic and Mesolithic dates from the East Baltic, based on radiocarbon age. This is because a proportion of the dates has never been calibrated, while a proportion of the new dates have been calibrated using various software programmes, often without stating the programme used. For the first time, radiocarbon dates have been obtained for the Late Palaeolithic in Lithuania: 10 550-9820 BP (cal. 10 600-9000 BC). This period is connected with the Swidry Culture in the central and southern part of the East Baltic. At the present best-dated stage of the Mesolithic is the Early Mesolithic, with several dates from Estonia (Pulli, Kunda-Lammasmagi) and Latvia, covering the period 9600 to around 9000 BP (cal. 8900-8300 BC). These dates are also supported by dates obtained from Mesolithic sites in neighbouring areas: northern Poland, southern Finland and north-east Russia. Much has been gained from the dating in recent years of burials in Lithuania and Latvia. Currently the oldest known burial is male buried in the cultural layer of Zvejnieki II settlement site, dated to 8240 BP. Another three burials in Lithuania,in the Spiginas and Duonkalnis cemeteries, as well as eight burials at Zvejnieki cemetery, date from the late Mesolithic, confirming the idea that it was in the Late Mesolithic that large special burial sites developed adjacent to settlements in the Baltic basin, both in the east and west. The development of cemeteries in Lithuania began in the period 7780-7470 BP, while the Late Mesolithic graves at Zvejnieki date from 6900-6400 BP. The dates show that a special feature of the cemeteries in the Baltic is their long duration of use, starting from the Middle Mesolithic up to the end of the

  4. NERC radiocarbon dating: 1975-1985

    International Nuclear Information System (INIS)

    Bowen, D.Q.; Harkness, D.D.

    1986-06-01

    The paper reviews the work of the Natural Environment Research Council Radiocarbon Dating Laboratory in connection with Quaternary research, over the last decade. A description is given of the development of the dating service and in-house research. Quaternary research investigations aided by radiocarbon dating are described under the topic headings: The late Devensian glacial maximum, late glacial, middle Devensian, palaeomagnetic secular variation in lake sediments, vegetational history, faunal history, palaeolimnology, ground water, volcanology, periglacial research, palaoeohydrology, geomorphology, quaternary events in low-latitudes, environmental archaeology, archaeology, deep sea sediments, continental shelf, coastal geomorphology, and radiocarbon dating in Antarctica. (U.K.)

  5. The utilisation of thermal analysis to optimise radiocarbon dating procedures

    International Nuclear Information System (INIS)

    Brandova, D.; Keller, W.A.; Maciejewski, M.

    1999-01-01

    Thermal analysis combined with mass spectrometry was applied to radiocarbon dating procedures (age determination of carbon-containing samples). Experiments carried out under an oxygen atmosphere were used to determine carbon content and combustion range of soil and wood samples. Composition of the shell sample and its decomposition were investigated. The quantification of CO 2 formed by the oxidation of carbon was done by the application of pulse thermal analysis. Experiments carried out under an inert atmosphere determined the combustion range of coal with CuO as an oxygen source. To eliminate a possible source of contamination in the radiocarbon dating procedures the adsorption of CO 2 by CuO was investigated. (author)

  6. New radiocarbon dates on the cereals from Wadi Kubbaniya

    International Nuclear Information System (INIS)

    Wendorf, F.; Schild, R.; Close, A.E.

    1984-01-01

    In 1978, three carbonized grains of barley and a carbonized grain of einkorn wheat were found in a buried hearth at a Late Paleolithic site at Wadi Kubbaniya in Egypt. In 1981, two large clusters of barley seeds, which were identified as six-row barley and thus domestic, were found at a nearby site of comparable age. Numerous grinding stones, presumed to have been used for processing the cereals, were found in these and other sites, often deeply buried, and 30 radiocarbon dates placed the occupations between 18,500 and 17,000 radiocarbon years ago. These finds led us to suggest an early origin of food production, with implications for the initial development of complex societies. Several barley seeds were analyzed by electron spin resonance spectroscopy to determine the maximal temperature to which they had been subjected before burial. Six barley seeds and three small pieces of wood charcoal were dated directly by using a tandem accelerator mass spectrometer

  7. An evaluation of fossil tip-dating versus node-age calibrations in tetraodontiform fishes (Teleostei: Percomorphaceae).

    Science.gov (United States)

    Arcila, Dahiana; Alexander Pyron, R; Tyler, James C; Ortí, Guillermo; Betancur-R, Ricardo

    2015-01-01

    Time-calibrated phylogenies based on molecular data provide a framework for comparative studies. Calibration methods to combine fossil information with molecular phylogenies are, however, under active development, often generating disagreement about the best way to incorporate paleontological data into these analyses. This study provides an empirical comparison of the most widely used approach based on node-dating priors for relaxed clocks implemented in the programs BEAST and MrBayes, with two recently proposed improvements: one using a new fossilized birth-death process model for node dating (implemented in the program DPPDiv), and the other using a total-evidence or tip-dating method (implemented in MrBayes and BEAST). These methods are applied herein to tetraodontiform fishes, a diverse group of living and extinct taxa that features one of the most extensive fossil records among teleosts. Previous estimates of time-calibrated phylogenies of tetraodontiforms using node-dating methods reported disparate estimates for their age of origin, ranging from the late Jurassic to the early Paleocene (ca. 150-59Ma). We analyzed a comprehensive dataset with 16 loci and 210 morphological characters, including 131 taxa (95 extant and 36 fossil species) representing all families of fossil and extant tetraodontiforms, under different molecular clock calibration approaches. Results from node-dating methods produced consistently younger ages than the tip-dating approaches. The older ages inferred by tip dating imply an unlikely early-late Jurassic (ca. 185-119Ma) origin for this order and the existence of extended ghost lineages in their fossil record. Node-based methods, by contrast, produce time estimates that are more consistent with the stratigraphic record, suggesting a late Cretaceous (ca. 86-96Ma) origin. We show that the precision of clade age estimates using tip dating increases with the number of fossils analyzed and with the proximity of fossil taxa to the node under

  8. Radiocarbon Values From Otoliths of Regional Bottomfishes

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data set contains bomb radiocarbon dating of opakapaka (Pristipomoides filamentosus) otoliths from recent and archival collections (1978-2008). Specimens were...

  9. Bomb radiocarbon: imbalance in the budget

    International Nuclear Information System (INIS)

    Joos, Fortunat

    1994-01-01

    An improved understanding of the global carbon cycle is crucial to global climate change research. The uncertainties surrounding the level of oceanic carbon uptake are discussed. A revision downwards of 25% in the currently accepted figure is suggested by authors who base their estimates on a new analysis of the oceanic uptake of radiocarbon released in the atomic bomb tests of the late 1950s and early 1960s. The reduction in uptake level is required to take account of a global imbalance in the bomb-radiocarbon budget in the post test-ban period which emerges from recent carbon-cycle models. Large uncertainties exist in the estimate of the imbalance, however, and bomb-radiocarbon and anthropogenic CO 2 do not behave identically. Any revision of CO 2 uptake estimates may be substantially smaller than the 25% put forward for the bomb-radiocarbon inventory. (UK)

  10. What Can Radiocarbon Depth Profiles Tell Us About The LGM Circulation?

    Science.gov (United States)

    Burke, A.; Stewart, A.; Adkins, J. F.; Ferrari, R. M.; Thompson, A. F.; Jansen, M. F.

    2014-12-01

    Published reconstructions of radiocarbon in the Atlantic sector of the Southern Ocean indicate that there is a mid-depth maximum in radiocarbon age during the last glacial maximum (LGM). This is in contrast to the modern ocean where intense mixing between water masses along shared density surfaces (isopycnals) results in a relatively homogenous radiocarbon profile. A recent study (Ferrari et al. 2014) suggested that the extended Antarctic sea ice cover during the LGM necessitated a shallower boundary between the upper and lower branches of the meridional overturning circulation (MOC). This shoaled boundary lay above major topographic features and their associated strong diapycnal mixing, which isolated dense southern-sourced water in the lower branch of the overturning circulation. This isolation would have allowed radiocarbon to decay, and thus provides a possible explanation for the mid-depth radiocarbon age bulge. We test this hypothesis using an idealized, 2D, residual-mean dynamical model of the global overturning circulation. Concentration distributions of a decaying tracer that is advected by the simulated overturning are compared to published radiocarbon data. We test the sensitivity of the mid-depth radiocarbon age to changes in sea ice extent, wind strength, and isopycnal and diapycnal diffusion. The mid-depth radiocarbon age bulge is most likely caused by the different circulation geometry, associated with increased sea ice extent. In particular, with an LGM-like sea ice extent the upper and lower branches of the MOC no longer share isopycnals, so radiocarbon-rich northern-sourced water is no longer mixed rapidly into the southern-sourced water. However, this process alone cannot explain the magnitude of the glacial radiocarbon anomalies; additional isolation (e.g. from reduced air-sea gas exchange associated with the increased sea ice) is required. Ferrari, R., M. F. Jansen, J. F. Adkins, A. Burke, A. L. Stewart, and A. F. Thompson (2014), Antarctic sea

  11. Sample processing procedures and radiocarbon dating

    International Nuclear Information System (INIS)

    Svetlik, Ivo; Tomaskova, Lenka; Dreslerova, Dagmar

    2010-01-01

    The article outlines radiocarbon dating routines and highlights the potential and limitations of this method. The author's institutions have been jointly running a conventional radiocarbon dating laboratory using the international CRL code. A procedure based on the synthesis of benzene is used. Small samples are sent abroad for dating because no AMS instrumentation is available in the Czech Republic so far. Our laboratory plans to introduce routines for the processing of milligram samples and preparation of graphitized targets for AMS

  12. AMS Radiocarbon Dating at Notre Dame

    Science.gov (United States)

    Howard, Sean

    2014-09-01

    Current development of a local radiocarbon dating method using Accelerator Mass Spectrometry (AMS) at the University of Notre Dame seeks to provide sensitive, reproducible, and accurate measurements for future interdisciplinary projects. While AMS has been the premier radiocarbon dating method for a few decades, repurposing Notre Dame's FN Tandem accelerator for radiocarbon dating has provided many unique challenges. Experiments have shown radiocarbon dating possible and reproducible using the FN Tandem accelerator, found optimal settings for said accelerator, and established sensitivity limits comparable to dedicated radiocarbon dating facilities. In addition, there is ongoing work to create a local chemistry lab to convert organic artifacts into graphite samples to be dated locally. Once the chemistry side has been completed, several artifacts from the IAEA's radiocarbon intercomparison have been procured. Dating these previously studied artifacts will provide an additional measure on the accuracy and repeatability of both the accelerator and chemical treatment. Provided that these IAEA artifacts are dated successfully, exciting projects will ensue, such as the authentication of artwork and dating of anthropological samples.

  13. The Schmidt hammer as a relative-age dating tool and its potential for calibrated-age dating in Holocene glaciated environments

    Science.gov (United States)

    Shakesby, Richard A.; Matthews, John A.; Owen, Geraint

    2006-11-01

    The Schmidt hammer is a relatively cheap, portable, sturdy instrument with proven value over the last two decades or so in rapidly dating coarse inorganic deposits of diverse origins. Early views were that its dating role was limited to distinguishing recently exposed from much older. Typically, either a few sites of possibly different ages or occasional older surfaces amongst many young sites were studied. More recently, calibration curves based on individual R-value means from small numbers (2-4) of sites of known ages have been used to estimate the ages of undated sites. We present Schmidt hammer rebound ( R-) values from 28 'Little Ice Age' (and younger), 23 Preboreal and 7 Younger Dryas glaciated surfaces in southern Norway in order, first, to test rigorously the robustness of the instrument as a relative-age dating tool. Despite being obtained from different surfaces (moraines, glaciofluvial deposits and bedrock) and varied metamorphic lithologies, the R-value overall means and 95% confidence intervals for the 'Little Ice Age', Preboreal and Younger Dryas age categories (respectively, 60.0±1.6, 41.6±1.4 and 34.2±2.0) are statistically significantly different. Only two outlying sites in the two younger age categories have overlapping confidence intervals, demonstrating remarkable robustness in differentiating early- and late-Holocene surfaces. The distinction between Preboreal and Younger Dryas sites (with terminal dates factors, including some previously considered critical (instrument wear, operator bias, initial rock surface texture), which emerge either as less important than previously argued or as relatively unimportant, together with others previously unreported (e.g. long-term changes in lichen, soil, snow and vegetation covers). Third, we investigate the potential for calibrated-age dating by applying exploratory, linear rates of R-value decline to selected combinations of sites. The results suggest that error limits of ca ±700 to ±1600 years

  14. Radiocarbon-dating of earthenware of the Earliest Jomon period from Obihiro city, in Hokkaido prefecture

    International Nuclear Information System (INIS)

    Kobayashi, Kenichi

    2013-01-01

    This paper investigated radiocarbon dating of earthenware of the Earliest Jomon period from Obihiro City, in Hokkaido Prefecture. The authors investigated radiocarbon age differences among charred woods and charred residues on the surface of potteries. Results of radiocarbon dates of URAHORO-type pottery adhesions showed ca. 7560-7987 14 C BP, and that of charcoals were ca. 7180 14 C BP and 7285 14 C BP. The age of charred residues on the inside surface of potteries show 300-800 yrs older than the 14 C age of the charred woods, which corresponded to the actual age of the archaeological site, respectively. It becomes a cause to have cooked the salmon by earthenware and I think that the marine reservoir effect occurred. (author)

  15. Year of birth determination using radiocarbon dating of dental enamel.

    Science.gov (United States)

    Buchholz, B A; Spalding, K L

    2010-05-01

    Radiocarbon dating is typically an archaeological tool rather than a forensic one. Recently however, we have shown that the amount of radiocarbon present in tooth enamel, as a result of nuclear bomb testing during the cold war, is a remarkably accurate indicator of when a person is born. Enamel isolated from human teeth is processed to form graphite and carbon-14 ((14)C) levels are measured using accelerator mass spectrometry. Since there is no turnover of enamel after it is formed, (14)C levels in the enamel represent (14)C levels in the atmosphere at the time of its formation. In this paper we describe the strategy used to determine the date of birth of an individual based on radiocarbon levels in tooth enamel, focusing on the methodology of this strategy. Year of birth information can significantly assist police investigators when the identity of a deceased individual is unknown. In such cases police will try to match particulars of the unidentified individual (which is often only gender and/or an estimate of age), with particulars from missing persons lists.

  16. Year of Birth Determination Using Radiocarbon Dating of Dental Enamel

    Energy Technology Data Exchange (ETDEWEB)

    Buchholz, B A; Spalding, K L

    2009-03-10

    Radiocarbon dating is typically an archaeological tool rather than a forensic one. Recently however, we have shown that the amount of radiocarbon present in tooth enamel, as a result of nuclear bomb testing during the cold war, is a remarkably accurate indicator of when a person is born. Enamel isolated from human teeth is processed to form graphite and carbon-14 ({sup 14}C) levels are measured using accelerator mass spectrometry. Since there is no turnover of enamel after it is formed, {sup 14}C levels in the enamel represent {sup 14}C levels in the atmosphere at the time of its formation. In this paper we describe the strategy used to determine the date of birth of an individual based on radiocarbon levels in tooth enamel, focusing on the methodology of this strategy. Year of birth information can significantly assist police investigators when the identity of a deceased individual is unknown. In such cases police will try to match particulars of the unidentified individual (which is often only gender and/or an estimate of age), with particulars from missing persons lists.

  17. Air pollutants targeted by radiocarbon dating

    International Nuclear Information System (INIS)

    Anon.

    1987-01-01

    Chemists at the Commerce Department's National Bureau of Standards (NBS) are answering questions about where certain atmospheric contaminants originate by refining a method best known for determining the age of archeological objects. Called radiocarbon dating, the method allows NBS scientists to examine air samples and determine whether contaminants come from naturally occurring or manmade sources-or a combination of the two. Making these distinctions is important to federal and state environmental agencies, which identify industrial sources of pollution for regulatory action. An overbalance of atmospheric carbon can cause a number of environmental problems. In methane's case, high levels are of concern to environmental agencies because of greenhouse properties. Methane also has been implicated as a possible contributor to changes in the ozone layer that protects the Earth from excessive ultraviolet light. Levels of methane have been increasing at an annual rate of about one percent over the last decade. This has caused concern in the environmental community, which hopes to determine just where the elevated levels are coming from. The NBS research is aimed at definitively pinpointing sources of methane and other atmospheric contaminants

  18. Reservoir effects in radiocarbon dating

    International Nuclear Information System (INIS)

    Head, M.J.

    1997-01-01

    Full text: The radiocarbon dating technique depends essentially on the assumption that atmospheric carbon dioxide containing the cosmogenic radioisotope 14 C enters into a state of equilibrium with all living material (plants and animals) as part of the terrestrial carbon cycle. Terrestrial reservoir effects occur when the atmospheric 14 C signal is diluted by local effects where systems depleted in 14 C mix with systems that are in equilibrium with the atmosphere. Naturally, this can occur with plant material growing close to an active volcano adding very old CO 2 to the atmosphere (the original 14 C has completely decayed). It can also occur in highly industrialised areas where fossil fuel derived CO 2 dilutes the atmospheric signal. A terrestrial reservoir effect can occur in the case of fresh water shells living in rivers or lakes where there is an input of ground water from springs or a raising of the water table. Soluble bicarbonate derived from the dissolution of very old limestone produces a 14 C dilution effect. Land snail shells and stream carbonate depositions (tufas and travertines) can be affected by a similar mechanism. Alternatively, in specific cases, these reservoir effects may not occur. This means that general interpretations assuming quantitative values for these terrestrial effects are not possible. Each microenvironment associated with samples being analysed needs to be evaluated independently. Similarly, the marine environment produces reservoir effects. With respect to marine shells and corals, the water depth at which carbonate growth occurs can significantly affect quantitative 14 C dilution, especially in areas where very old water is uplifted, mixing with top layers of water that undergo significant exchange with atmospheric CO 2 . Hence, generalisations with respect to the marine reservoir effect also pose problems. These can be exacerbated by the mixing of sea water with either terrestrial water in estuaries, or ground water where

  19. Astronomically calibrated 40Ar/39Ar age for the Toba supereruption and global synchronization of late Quaternary records

    Science.gov (United States)

    Storey, Michael; Roberts, Richard G.; Saidin, Mokhtar

    2012-11-01

    The Toba supereruption in Sumatra, ∼74 thousand years (ka) ago, was the largest terrestrial volcanic event of the Quaternary. Ash and sulfate aerosols were deposited in both hemispheres, forming a time-marker horizon that can be used to synchronize late Quaternary records globally. A precise numerical age for this event has proved elusive, with dating uncertainties larger than the millennial-scale climate cycles that characterized this period. We report an astronomically calibrated 40Ar/39Ar age of 73.88 ± 0.32 ka (1σ, full external errors) for sanidine crystals extracted from Toba deposits in the Lenggong Valley, Malaysia, 350 km from the eruption source and 6 km from an archaeological site with stone artifacts buried by ash. If these artifacts were made by Homo sapiens, as has been suggested, then our age indicates that modern humans had reached Southeast Asia by ∼74 ka ago. Our 40Ar/39Ar age is an order-of-magnitude more precise than previous estimates, resolving the timing of the eruption to the middle of the cold interval between Dansgaard-Oeschger events 20 and 19, when a peak in sulfate concentration occurred as registered by Greenland ice cores. This peak is followed by a ∼10 °C drop in the Greenland surface temperature over ∼150 y, revealing the possible climatic impact of the eruption. Our 40Ar/39Ar age also provides a high-precision calibration point for other ice, marine, and terrestrial archives containing Toba sulfates and ash, facilitating their global synchronization at unprecedented resolution for a critical period in Earth and human history beyond the range of 14C dating.

  20. Timing of Expansions of the Quelccaya Ice Cap, Peru, and Implications for Cosmogenic Nuclide Production Rate Calibration

    Science.gov (United States)

    Lowell, T. V.; Kelly, M. A.; Applegate, P. J.; Smith, C. A.; Phillips, F. M.; Hudson, A. M.

    2010-12-01

    We calibrate the production rate of the cosmogenic nuclide beryllium-10 (10Be) at a low-latitude, high-elevation site, using nuclide concentrations measured in moraine boulders and an independent chronology determined with bracketing radiocarbon dates. The measurement of terrestrial cosmogenic nuclide (TCN) concentrations in earth surface materials has been an important development for understanding a host of earth surface processes. Uncertainty in cosmogenic nuclide production rates has hampered application of this method. Here, we contribute to the estimation of 10Be production rates by reporting both preliminary 10Be concentrations and independent radiocarbon dates from a low latitude, high elevation site. Our study site in the southeastern Peruvian Andes (~13.9°S, 70.9°W, 4850 m asl) is centered on a moraine set, known as the Huancané II moraines, that represents a ~4 km expansion of Quelccaya Ice Cap during late glacial time. At this location, organic material situated both stratigraphically below and above moraines in two adjacent valleys provide material for radiocarbon dating. Based on geomorphic arguments, we correlate results from the two valleys. The timing of ice cap margin advance is bracketed by 13 radiocarbon ages on organic material within the outermost Huancané II moraines that range from 13.6 to 12.5 ka. Two stratigraphic sections upvalley from the moraines yield 6 radiocarbon ages from 11.3 to 12.4 ka, indicating the time of retreat . We computed the probability density function that lies between these two sets of dates, and assign an age of 12.4 ka (+/-???) for the formation of the Huancané II moraines. Calculating beryllium-10 exposure dates from the measured concentrations yield exposure dates that significantly underestimate the independently determined age of the moraine (~8-30%), if existing production rate estimates are used. We suggest that the radiocarbon age for the moraines can be used as a robust independent calibration for 10Be

  1. Vertebral bomb radiocarbon suggests extreme longevity in white sharks.

    Science.gov (United States)

    Hamady, Li Ling; Natanson, Lisa J; Skomal, Gregory B; Thorrold, Simon R

    2014-01-01

    Conservation and management efforts for white sharks (Carcharodon carcharias) remain hampered by a lack of basic demographic information including age and growth rates. Sharks are typically aged by counting growth bands sequentially deposited in their vertebrae, but the assumption of annual deposition of these band pairs requires testing. We compared radiocarbon (Δ(14)C) values in vertebrae from four female and four male white sharks from the northwestern Atlantic Ocean (NWA) with reference chronologies documenting the marine uptake of (14)C produced by atmospheric testing of thermonuclear devices to generate the first radiocarbon age estimates for adult white sharks. Age estimates were up to 40 years old for the largest female (fork length [FL]: 526 cm) and 73 years old for the largest male (FL: 493 cm). Our results dramatically extend the maximum age and longevity of white sharks compared to earlier studies, hint at possible sexual dimorphism in growth rates, and raise concerns that white shark populations are considerably more sensitive to human-induced mortality than previously thought.

  2. Results of radiocarbon dating of Holocene fluvial sediments from Northeastern Bohemia

    International Nuclear Information System (INIS)

    Silar, J.; Zeman, A.

    1989-01-01

    Samples of wood and charcoal from the latest Holocene fluvial sediments under the lowest surface of alluvial plains were dated by radiocarbon in order to check paleomagnetic data at four sites in northeastern Bohemia. The results are presented as funcorrected 14 C ages and dendrochronologically corrected ages. Two samples were recent. 4 figs., 1 tab., 3 refs

  3. Radiocarbon dating uncertainties and their effects on studies of the past

    International Nuclear Information System (INIS)

    Chappell, J.

    1982-01-01

    The handling of sets of age results and their errors for hypothesis testing is discussed. The paper focusses on radiocarbon dating but most of the principles apply to other dating methods, although some formulae will be different. One conclusion is that the conventional age error should be enlarged to allow for past variations of 14 C level in the atmosphere

  4. Radiocarbon chronology of Manot Cave, Israel and Upper Paleolithic dispersals

    Science.gov (United States)

    Alex, Bridget; Barzilai, Omry; Hershkovitz, Israel; Marder, Ofer; Berna, Francesco; Caracuta, Valentina; Abulafia, Talia; Davis, Lauren; Goder-Goldberger, Mae; Lavi, Ron; Mintz, Eugenia; Regev, Lior; Bar-Yosef Mayer, Daniella; Tejero, José-Miguel; Yeshurun, Reuven; Ayalon, Avner; Bar-Matthews, Mira; Yasur, Gal; Frumkin, Amos; Latimer, Bruce; Hans, Mark G.; Boaretto, Elisabetta

    2017-01-01

    The timing of archeological industries in the Levant is central for understanding the spread of modern humans with Upper Paleolithic traditions. We report a high-resolution radiocarbon chronology for Early Upper Paleolithic industries (Early Ahmarian and Levantine Aurignacian) from the newly excavated site of Manot Cave, Israel. The dates confirm that the Early Ahmarian industry was present by 46,000 calibrated years before the present (cal BP), and the Levantine Aurignacian occurred at least between 38,000 and 34,000 cal BP. This timing is consistent with proposed migrations or technological diffusions between the Near East and Europe. Specifically, the Ahmarian could have led to the development of the Protoaurignacian in Europe, and the Aurignacian in Europe could have spread back to the Near East as the Levantine Aurignacian. PMID:29152566

  5. Radiocarbon dating of extinct fauna in the Americas recovered from tar pits

    International Nuclear Information System (INIS)

    Jull, A.J.T.; Iturralde-Vinent, M.; O'Malley, J.M.; MacPhee, R.D.E.; McDonald, H.G.; Martin, P.S.; Moody, J.; Rincon, A.

    2004-01-01

    We have obtained radiocarbon dates by accelerator mass spectrometry on bones of extinct large mammals from tar pits. Results on some samples of Glyptodon and Holmesina (extinct large mammals similar to armadillos) yielded ages of >25 and >21 ka, respectively. We also studied the radiocarbon ages of three different samples of bones from the extinct Cuban ground sloth, Parocnus bownii, which yielded dates ranging from 4960 ± 280 to 11 880 ± 420 yr BP. In order to remove the tar component pretreat the samples sufficiently to obtain reliable dates, we cleaned the samples by Soxhlet extraction in benzene. Resulting samples of collagenous material were often small

  6. Towards radiocarbon dating of single foraminifera with a gas ion source

    Science.gov (United States)

    Wacker, L.; Lippold, J.; Molnár, M.; Schulz, H.

    2013-01-01

    Carbonate shells from foraminifera are often analysed for radiocarbon to determine the age of deep-sea sediments or to assess radiocarbon reservoir ages. However, a single foraminiferal test typically contains only a few micrograms of carbon, while most laboratories require more than 100 μg for radiocarbon dating with an accelerator mass spectrometry (AMS) system. The collection of the required amount of foraminifera for a single analyses is therefore time consuming and not always possible. Here, we present a convenient method to measure the radiocarbon content of foraminifera using an AMS system fitted with a gas ion source. CO2 is liberated from 150 to 1150 μg of carbonate in septum sealed vials by acid decomposition of the carbonate. The CO2 is collected on a zeolite trap and subsequently transferred to a syringe from where it is delivered to the ion source. A sample of 400 μg (50 μg C) typically gives a 12C- ion source current of 10-15 μA over 20 min, yielding a measurement precision of less than 7 per mil for a modern sample. Using this method, we were able to date a single 560 μg Cibicides pseudoungerianus test at 14,030 ± 160 radiocarbon years. Only a minor modification to our existing gas handling system was required and the system is fully automatable to further reduce the effort involved for sample preparation.

  7. Towards radiocarbon dating of single foraminifera with a gas ion source

    International Nuclear Information System (INIS)

    Wacker, L.; Lippold, J.; Molnár, M.; Schulz, H.

    2013-01-01

    Carbonate shells from foraminifera are often analysed for radiocarbon to determine the age of deep-sea sediments or to assess radiocarbon reservoir ages. However, a single foraminiferal test typically contains only a few micrograms of carbon, while most laboratories require more than 100 μg for radiocarbon dating with an accelerator mass spectrometry (AMS) system. The collection of the required amount of foraminifera for a single analyses is therefore time consuming and not always possible. Here, we present a convenient method to measure the radiocarbon content of foraminifera using an AMS system fitted with a gas ion source. CO 2 is liberated from 150 to 1150 μg of carbonate in septum sealed vials by acid decomposition of the carbonate. The CO 2 is collected on a zeolite trap and subsequently transferred to a syringe from where it is delivered to the ion source. A sample of 400 μg (50 μg C) typically gives a 12 C − ion source current of 10–15 μA over 20 min, yielding a measurement precision of less than 7 per mil for a modern sample. Using this method, we were able to date a single 560 μg Cibicides pseudoungerianus test at 14,030 ± 160 radiocarbon years. Only a minor modification to our existing gas handling system was required and the system is fully automatable to further reduce the effort involved for sample preparation.

  8. Towards radiocarbon dating of single foraminifera with a gas ion source

    Energy Technology Data Exchange (ETDEWEB)

    Wacker, L., E-mail: wacker@phys.ethz.ch [Laboratory of Ion Beam Physics, ETH Zurich, 8093 Zurich (Switzerland); Lippold, J. [Heidelberg Academy of Sciences, 69120 Heidelberg (Germany); Molnar, M. [Laboratory of Ion Beam Physics, ETH Zurich, 8093 Zurich (Switzerland); Institute of Nuclear Research, Hungarian Academy of Sciences, 4026 Debrecen (Hungary); Schulz, H. [Institute for Geosciencies, University of Tuebingen, 72076 Tuebingen (Germany)

    2013-01-15

    Carbonate shells from foraminifera are often analysed for radiocarbon to determine the age of deep-sea sediments or to assess radiocarbon reservoir ages. However, a single foraminiferal test typically contains only a few micrograms of carbon, while most laboratories require more than 100 {mu}g for radiocarbon dating with an accelerator mass spectrometry (AMS) system. The collection of the required amount of foraminifera for a single analyses is therefore time consuming and not always possible. Here, we present a convenient method to measure the radiocarbon content of foraminifera using an AMS system fitted with a gas ion source. CO{sub 2} is liberated from 150 to 1150 {mu}g of carbonate in septum sealed vials by acid decomposition of the carbonate. The CO{sub 2} is collected on a zeolite trap and subsequently transferred to a syringe from where it is delivered to the ion source. A sample of 400 {mu}g (50 {mu}g C) typically gives a {sup 12}C{sup -} ion source current of 10-15 {mu}A over 20 min, yielding a measurement precision of less than 7 per mil for a modern sample. Using this method, we were able to date a single 560 {mu}g Cibicides pseudoungerianus test at 14,030 {+-} 160 radiocarbon years. Only a minor modification to our existing gas handling system was required and the system is fully automatable to further reduce the effort involved for sample preparation.

  9. Luminescence and radiocarbon dating of raised beach sediments, Bunger Hills, East Antarctica

    International Nuclear Information System (INIS)

    Augustinus, P.C.; Duller, G.A.T.

    2002-01-01

    Luminescence and radiocarbon dating of raised marine sediments from the Bunger Hills, East Antarctica, demonstrates that luminescence methods can be applied to such poorly bleached sediments as long as the luminescence behaviour of the sediments is understood. This is essential as the complete zeroing of the luminescence signal due to light exposure is required to allow an accurate age for the sediment accumulation. Unfortunately, independent checks on the luminescence ages are rare. In the present study, some independent age control is provided by AMS radiocarbon ages from shell obtained from and adjacent to the luminescence dated horizons, although the radiocarbon ages may suffer to some degree from variability in the marine reservoir effect. Application of the single aliquot luminescence technique to feldspar grains from the marine sediments demonstrated that the luminescence behaviour of the sediments was complex. For each sample, 18 replicate paleodose estimates were used to demonstrate whether the sediments were well bleached before deposition. Optically, well-bleached samples give younger luminescence ages, whilst poorly bleached samples often give excessively old ages compared to the associated radiocarbon-dated material. (author)

  10. Radiocarbon dates on bones of extinct birds from Hawaii.

    OpenAIRE

    James, H F; Stafford, T W; Steadman, D W; Olson, S L; Martin, P S; Jull, A J; McCoy, P C

    1987-01-01

    Bones from a stratified sedimentary deposit in the Puu Naio Cave site on Maui, Hawaiian Islands, reveal the late Holocene extinction of 19 species of birds. The age of the sediment and associated fauna was determined by direct radiocarbon dating (tandem particle accelerator-mass spectrometer; TAMS) of amino acids extracted from bones weighing as little as 450 mg. The 14C dates indicate that sediment has been accumulating in the lava tube for at least the last 7750 years, a suitable time frame...

  11. Rarotonga Radiocarbon (delta 14C) for 1950 to 1997

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Rarotonga coral radiocarbon (14C) timeseries. Coral radiocarbon (Delta-14C) on untreated, low-speed drilled samples. Precision is +/- 4 per mil as documented by an...

  12. Application of Bomb Radiocarbon Chronologies to Shortfin Mako (Isurus oxyrinchus)

    Energy Technology Data Exchange (ETDEWEB)

    Ardizzone, D; Cailliet, G M; Natanson, L J; Andrews, A H; Kerr, L A; Brown, T A

    2007-07-16

    and the number of samples for MIA analysis was insufficient for some months. Hence, unequivocal validation of shortfin mako age estimates has yet to be accomplished. Atmospheric testing of thermonuclear devices in the 1950s and 1960s effectively doubled the natural atmospheric radiocarbon ({sup 14}C). The elevated {sup 14}C levels were first recorded in 1957-58, with a peak around 1963. As a consequence, {sup 14}C entered the ocean through gas exchange with the atmosphere at the ocean surface and in terrestrial runoff. Despite variable oceanographic conditions, a worldwide rise of the bomb {sup 14}C signal entered the ocean mixed layer as dissolved inorganic carbon (DIC) in 1957-58. The large amounts of {sup 14}C released from the bomb tests produced a signature that can be followed through time, throughout the marine food web, and into deeper waters. The marked increase of radiocarbon levels was first measured in the DIC of seawater and in biogenic marine carbonates of hermatypic corals in Florida. Subsequently, this record was documented in corals from other regions and in the thallus of rhodoliths. The accumulation of radiocarbon in the hard parts of most marine organisms in the mixed layer (such as fish otoliths and bivalves) was synchronous with the coral time-series. This technique has been used to validate age estimates and longevity of numerous bony fishes to date, as well as to establish bomb radiocarbon chronologies from different oceans. In the first application of this technique to lamnoid sharks, validated annual band-pair deposition in vertebral growth bands for the porbeagle (Lamna nasus) aged up to 26 years. Radiocarbon values from samples obtained from 15 porbeagle caught in the western North Atlantic Ocean (some of which were known-age) produced a chronology similar in magnitude to the reference carbonate chronology for that region. The observed phase shift of about 3 years was attributed to different sources of carbon between vertebrae and those for

  13. New hydroxyproline radiocarbon dates from Sungir, Russia, confirm early Mid Upper Palaeolithic burials in Eurasia.

    Directory of Open Access Journals (Sweden)

    Shweta Nalawade-Chavan

    Full Text Available Sungir (Russia is a key Mid-Upper Palaeolithic site in Eurasia, containing several spectacular burials that disclose early evidence for complex burial rites in the form of a range of grave goods deposited along with the dead. Dating has been particularly challenging, with multiple radiocarbon dates ranging from 19,160±270 to 28,800±240 BP for burials that are believed to be closely similar in age. There are disparities in the radiocarbon dates of human bones, faunal remains and charcoal found on the floor of burials. Our approach has been to develop compound-specific methods using High Performance Liquid Chromatography (HPLC to separate single amino acids, such as hydroxyproline, and thereby avoid the known human contamination on the bones themselves. Previously, we applied this technique to obtain radiocarbon dates of ∼30,000 BP for Sungir 2, Sungir 3 and a mammoth bone from the occupation levels of the site. The single amino acid radiocarbon dates were in good agreement with each other compared to all the dates previously reported, supporting their reliability. Here we report new hydroxyproline dates for two more human burials from the same site, Sungir 1 and Sungir 4. All five hydroxyproline dates reported are statistically indistinguishable and support an identical age for the group. The results suggest that compound-specific radiocarbon analysis should be considered seriously as the method of choice when precious archaeological remains are to be dated because they give a demonstrably contaminant-free radiocarbon age. The new ages are, together with the previously dated 'Red Lady of Paviland' human in the British Isles, the earliest for Mid Upper Palaeolithic burial behaviour in Eurasia, and point to the precocious appearance of this form of rite in Europe Russia.

  14. New hydroxyproline radiocarbon dates from Sungir, Russia, confirm early Mid Upper Palaeolithic burials in Eurasia.

    Science.gov (United States)

    Nalawade-Chavan, Shweta; McCullagh, James; Hedges, Robert

    2014-01-01

    Sungir (Russia) is a key Mid-Upper Palaeolithic site in Eurasia, containing several spectacular burials that disclose early evidence for complex burial rites in the form of a range of grave goods deposited along with the dead. Dating has been particularly challenging, with multiple radiocarbon dates ranging from 19,160±270 to 28,800±240 BP for burials that are believed to be closely similar in age. There are disparities in the radiocarbon dates of human bones, faunal remains and charcoal found on the floor of burials. Our approach has been to develop compound-specific methods using High Performance Liquid Chromatography (HPLC) to separate single amino acids, such as hydroxyproline, and thereby avoid the known human contamination on the bones themselves. Previously, we applied this technique to obtain radiocarbon dates of ∼30,000 BP for Sungir 2, Sungir 3 and a mammoth bone from the occupation levels of the site. The single amino acid radiocarbon dates were in good agreement with each other compared to all the dates previously reported, supporting their reliability. Here we report new hydroxyproline dates for two more human burials from the same site, Sungir 1 and Sungir 4. All five hydroxyproline dates reported are statistically indistinguishable and support an identical age for the group. The results suggest that compound-specific radiocarbon analysis should be considered seriously as the method of choice when precious archaeological remains are to be dated because they give a demonstrably contaminant-free radiocarbon age. The new ages are, together with the previously dated 'Red Lady of Paviland' human in the British Isles, the earliest for Mid Upper Palaeolithic burial behaviour in Eurasia, and point to the precocious appearance of this form of rite in Europe Russia.

  15. Handlist of radiocarbon laboratories. Appendix III

    International Nuclear Information System (INIS)

    Watkins, T.; Harkness, D.D.

    1975-01-01

    A list is given of radiocarbon laboratories known to be active, and open to archaeologists, at least in some circumstances. It is not claimed to have produced an exhaustive list, which can be found in the journal Radiocarbon. The present list gives (a) some indication to would-be users, of the ability of willingness of laboratories to undertake archaeological dating; (b) a statement from each laboratory concerning the special services it may offer; (c) the likely time taken to obtain a C-14 date; and (d) a scale of charges. (U.K.)

  16. The Gaia-ESO Survey: open clusters in Gaia-DR1 . A way forward to stellar age calibration

    Science.gov (United States)

    Randich, S.; Tognelli, E.; Jackson, R.; Jeffries, R. D.; Degl'Innocenti, S.; Pancino, E.; Re Fiorentin, P.; Spagna, A.; Sacco, G.; Bragaglia, A.; Magrini, L.; Prada Moroni, P. G.; Alfaro, E.; Franciosini, E.; Morbidelli, L.; Roccatagliata, V.; Bouy, H.; Bravi, L.; Jiménez-Esteban, F. M.; Jordi, C.; Zari, E.; Tautvaišiene, G.; Drazdauskas, A.; Mikolaitis, S.; Gilmore, G.; Feltzing, S.; Vallenari, A.; Bensby, T.; Koposov, S.; Korn, A.; Lanzafame, A.; Smiljanic, R.; Bayo, A.; Carraro, G.; Costado, M. T.; Heiter, U.; Hourihane, A.; Jofré, P.; Lewis, J.; Monaco, L.; Prisinzano, L.; Sbordone, L.; Sousa, S. G.; Worley, C. C.; Zaggia, S.

    2018-05-01

    Context. Determination and calibration of the ages of stars, which heavily rely on stellar evolutionary models, are very challenging, while representing a crucial aspect in many astrophysical areas. Aims: We describe the methodologies that, taking advantage of Gaia-DR1 and the Gaia-ESO Survey data, enable the comparison of observed open star cluster sequences with stellar evolutionary models. The final, long-term goal is the exploitation of open clusters as age calibrators. Methods: We perform a homogeneous analysis of eight open clusters using the Gaia-DR1 TGAS catalogue for bright members and information from the Gaia-ESO Survey for fainter stars. Cluster membership probabilities for the Gaia-ESO Survey targets are derived based on several spectroscopic tracers. The Gaia-ESO Survey also provides the cluster chemical composition. We obtain cluster parallaxes using two methods. The first one relies on the astrometric selection of a sample of bona fide members, while the other one fits the parallax distribution of a larger sample of TGAS sources. Ages and reddening values are recovered through a Bayesian analysis using the 2MASS magnitudes and three sets of standard models. Lithium depletion boundary (LDB) ages are also determined using literature observations and the same models employed for the Bayesian analysis. Results: For all but one cluster, parallaxes derived by us agree with those presented in Gaia Collaboration (2017, A&A, 601, A19), while a discrepancy is found for NGC 2516; we provide evidence supporting our own determination. Inferred cluster ages are robust against models and are generally consistent with literature values. Conclusions: The systematic parallax errors inherent in the Gaia DR1 data presently limit the precision of our results. Nevertheless, we have been able to place these eight clusters onto the same age scale for the first time, with good agreement between isochronal and LDB ages where there is overlap. Our approach appears promising

  17. Supporting Evidence for the Astronomically Calibrated Age of Fish Canyon Sanidine

    DEFF Research Database (Denmark)

    Rivera, Tiffany; Storey, Michael; Zeeden, Christian

    The relative nature of the 40Ar/39Ar radio-isotopic dating technique requires that the age and error of the monitor mineral be accurately known. The most widely accepted monitor for Cenozoic geochronology is the Fish Canyon sanidine (FCs), whose recommended published ages have varied by up to 2...... tuned stratigraphic sections. The increasingly robust quality of the astronomical timescale, with precision better than 0.1% for the last 10 million years, suggests this method of intercalibration as the best way to proceed with addressing the true age of FCs. Recently, Kuiper, et al. (2008) determined...... Noblesse multi-collector noble gas mass spectrometer for the 40Ar/39Ar experiments, analyzing single crystals of FCs relative to sanidines from the astronomically dated tephra. The use of the multi-collector instrument allowed us to obtain high precision analyses with a level of precision for fully...

  18. The age calibration of integrated ultraviolet colors and young stellar clusters in the Large Magellanic Cloud

    International Nuclear Information System (INIS)

    Barbero, J.; Brocato, E.; Cassatella, A.; Castellani, V.; Geyer, E.H.

    1990-01-01

    Integrated colors in selected far-UV bands are presented for a large sample of Large Magellanic Cloud (LMC) clusters. Theoretical calculations of these integrated colors are derived and discussed. The location in the two-color diagram C(18-28), C(15-31) is expected to be a sensitive but smooth function of cluster age for ages in the range 5 to 800 million yr. Theoretical results appear in very good agreement with the observed colors of LMC clusters. From this comparison, the gap in the observed colors is suggested to be caused by the lack of LMC clusters in the range of ages between 200 million to one billion yr. The two-color location of old globulars is discussed, also in connection with available data for the M31 clusters. 36 refs

  19. Effects of normal aging on calibration and response time of nuclear plant RTDs and pressure sensors

    International Nuclear Information System (INIS)

    Hashemian, H.L.; Riner, J.L.

    1993-01-01

    Resistance temperature detectors (RTDs) and pressure, level, and flow transmitters provide a majority of the vital signals for the control and safety of nuclear power plants. Therefore, it is crucial to ensure that the performance of these sensors are maintained at an acceptable level while the plant is operating. Since aging has the potential to cause performance degradation in RTDs and pressure transmitters, several research projects have been sponsored by the US Nuclear Regulatory Commission (NRC) to study the aging characteristics of these sensors and ensure that adequate test methods and test frequencies are followed by the nuclear industry to ensure safety. The details of these projects are summarized in this paper

  20. A refined astronomically calibrated 40Ar/39Ar age for Fish Canyon sanidine

    NARCIS (Netherlands)

    Rivera, T.A.; Storey, M.; Zeeden, C.; Hilgen, F.J.; Kuiper, K.

    2011-01-01

    Intercalibration between the astronomical and radio-isotopic dating methods provides a means to improving accuracy and reducing uncertainty of an integrated, multi-chronometer geologic timescale. Here we report a high-precision 40Ar/39Ar age for the FishCanyon sanidine (FCs) neutron fluence monitor,

  1. Carbon extraction methods for radiocarbon dating of pottery

    International Nuclear Information System (INIS)

    Delque-Kolic, E.

    1995-01-01

    Pottery is a direct witness of human activity and gives, through its macroscopic and microscopic studies, lots of information about its manufacturers. Nevertheless, radiocarbon dating, currently applied in archaeology to charcoals, wood and bones has only been rarely employed with ceramic. The problem is that many different carbon sources, of different radiocarbon age, may contribute to the potsherd carbon content. So, the aim of all dating projects is to separate carbon related to the period when the potsherd was manufactured and used. In a first time, we have made our own samples with raw materials (clay and temper) known in nature and age. We have fired them with wood of known age under reducing atmosphere. Under these conditions, soot produced by wood burning forms a more or less important deposit on the surface of the pots. It is this source of carbon, present in many archaeological sherds, that we first tried to select. Burning these potsherds at low temperature under an O 2 flow, we have noticed that carbon from kiln wood was preferentially extracted. This treatment applied to a thin lamella cut in a smoked part of the potsherd provides, almost exclusively, carbon from smoke. These techniques, applied to known archaeological sherds, have given encouraging results. We have also explored a new method which consists in oxidizing carbon with a laser beam at the surface of the sample. The use of this process for extracting carbon from smoke seems promising if serious experimental precautions are taken when working with so low carbon content. (author)

  2. A combined method for DNA analysis and radiocarbon dating from a single sample.

    Science.gov (United States)

    Korlević, Petra; Talamo, Sahra; Meyer, Matthias

    2018-03-07

    Current protocols for ancient DNA and radiocarbon analysis of ancient bones and teeth call for multiple destructive samplings of a given specimen, thereby increasing the extent of undesirable damage to precious archaeological material. Here we present a method that makes it possible to obtain both ancient DNA sequences and radiocarbon dates from the same sample material. This is achieved by releasing DNA from the bone matrix through incubation with either EDTA or phosphate buffer prior to complete demineralization and collagen extraction utilizing the acid-base-acid-gelatinization and ultrafiltration procedure established in most radiocarbon dating laboratories. Using a set of 12 bones of different ages and preservation conditions we demonstrate that on average 89% of the DNA can be released from sample powder with minimal, or 38% without any, detectable collagen loss. We also detect no skews in radiocarbon dates compared to untreated samples. Given the different material demands for radiocarbon dating (500 mg of bone/dentine) and DNA analysis (10-100 mg), combined DNA and collagen extraction not only streamlines the sampling process but also drastically increases the amount of DNA that can be recovered from limited sample material.

  3. Use of radiocarbon technique for archaelogic dating

    International Nuclear Information System (INIS)

    Chausson, Y.

    1986-01-01

    The nuclear technique based on the beta radiation measurements emitted by the radiocarbon is applied an the geochronologycal dating of organic samples of prehistoric fires and sambaqui shells. This paper describes the origin of the method, the technique used and its applications, the analysis method, the equipments and the experiences performed. (Author) [pt

  4. The use of AMS radiocarbon dating for Xia-Shang-Zhou chronology

    CERN Document Server

    Guo, Z Y; LiuKeXin; Lu Xiang Yang; Ma Hong Ji; Wu Xiao Hon; Yuan Si Xun

    2000-01-01

    The possibility and problems of using radiocarbon dating to historical chronology are discussed. The current situation of ancient Chinese chronology and the project of Xia-Shang-Zhou chronology are introduced. A chronological study requires the AMS radiocarbon dating with high precision, high reliability and high efficiency. The Peking University AMS facility (PKUAMS) has been upgraded and a series of quality control steps were adopted. To reduce the error of calendar age, wiggle matching with serial samples should be used. Some preliminary results of Xia-Shang-Zhou chronology are presented.

  5. Numerical flow models and their calibration using tracer based ages: Chapter 10

    Science.gov (United States)

    Sanford, W.

    2013-01-01

    Any estimate of ‘age’ of a groundwater sample based on environmental tracers requires some form of geochemical model to interpret the tracer chemistry (chapter 3) and is, therefore, referred to in this chapter as a tracer model age. the tracer model age of a groundwater sample can be useful for obtaining information on the residence time and replenishment rate of an aquifer system, but that type of data is most useful when it can be incorporated with all other information that is known about the groundwater system under study. groundwater fl ow models are constructed of aquifer systems because they are usually the best way of incorporating all of the known information about the system in the context of a mathematical framework that constrains the model to follow the known laws of physics and chemistry as they apply to groundwater flow and transport. It is important that the purpose or objective of the study be identified first before choosing the type and complexity of the model to be constructed, and to make sure such a model is necessary. The purpose of a modelling study is most often to characterize the system within a numerical framework, such that the hydrological responses of the system can be tested under potential stresses that might be imposed given future development scenarios. As this manual discusses dating as it applies to old groundwater, most readers are likely to be interested in studying regional groundwater flow systems and their water resource potential.

  6. Holocene environmental changes disclosed from anoxic fjord sediments by biomarkers and their radiocarbon content

    NARCIS (Netherlands)

    Smittenberg, R.H.

    2003-01-01

    The power and validity of compound-specific radiocarbon dating was evaluated using sediments from Saanich Inlet, Canada, in age ranging from recent to 5000 yr BP. Compounds characteristic of higher plants, phytoplankton and archaea, were isolated by preparative GC and

  7. The marine radiocarbon bomb pulse across the temperate North Atlantic: a compilation of Delta

    NARCIS (Netherlands)

    Scourse, J.D.; Wanamaker jr., A.D.; Weidman, C.; Heinemeier, J.; Reimer, P.J.; Butler, P.G.; Witbaard, R.; Richardson, C.A.

    2012-01-01

    Marine radiocarbon bomb-pulse time histories of annually resolved archives from temperate regions have been underexploited. We present here series of Delta C-14 excess from known-age annual increments of the long-lived bivalve mollusk Arctica islandica from 4 sites across the coastal North Atlantic

  8. Age-related changes in brain hemodynamics; A calibrated MRI study

    DEFF Research Database (Denmark)

    De Vis, J B; Hendrikse, J; Bhogal, A

    2015-01-01

    INTRODUCTION: Blood oxygenation-level dependent (BOLD) magnetic resonance imaging signal changes in response to stimuli have been used to evaluate age-related changes in neuronal activity. Contradictory results from these types of experiments have been attributed to differences in cerebral blood....... A dual-echo pseudocontinuous arterial spin labeling (ASL) sequence was performed during normocapnic, hypercapnic, and hyperoxic breathing challenges. Whole brain and regional gray matter values of CBF, ASL cerebrovascular reactivity (CVR), BOLD CVR, oxygen extraction fraction (OEF), and CMRO2 were...... calculated. RESULTS: Whole brain CBF was 49 ± 14 and 40 ± 9 ml/100 g/min in young and older subjects respectively (P brain, in the frontal...

  9. Ancient human mitochondrial DNA and radiocarbon analysis of archived quids from the Mule Spring Rockshelter, Nevada, USA.

    Directory of Open Access Journals (Sweden)

    Scott D Hamilton-Brehm

    Full Text Available Chewed and expectorated quids, indigestible stringy fibers from the roasted inner pulp of agave or yucca root, have proven resilient over long periods of time in dry cave environments and correspondingly, although little studied, are common in archaeological archives. In the late 1960s, thousands of quids were recovered from Mule Spring Rockshelter (Nevada, USA deposits and stored without consideration to DNA preservation in a museum collection, remaining unstudied for over fifty years. To assess the utility of these materials as repositories for genetic information about past inhabitants of the region and their movements, twenty-one quids were selected from arbitrary excavation depths for detailed analysis. Human mitochondrial DNA sequences from the quids were amplified by PCR and screened for diagnostic single nucleotide polymorphisms. Most detected single nucleotide polymorphisms were consistent with recognized Native American haplogroup subclades B2a5, B2i1, C1, C1c, C1c2, and D1; with the majority of the sample set consistent with subclades C1, C1c, and C1c2. In parallel with the DNA analysis, each quid was radiocarbon dated, revealing a time-resolved pattern of occupancy from 347 to 977 calibrated years before present. In particular, this dataset reveals strong evidence for the presence of haplogroup C1/C1c at the Southwestern edge of the US Great Basin from ~670 to 980 cal YBP, which may temporally correspond with the beginnings of the so-called Numic Spread into the region. The research described here demonstrates an approach which combines targeted DNA analysis with radiocarbon age dating; thus enabling the genetic analysis of archaeological materials of uncertain stratigraphic context. Here we present a survey of the maternal genetic profiles from people who used the Mule Spring Rockshelter and the historic timing of their utilization of a key natural resource.

  10. Radiocarbon dating of VIRI bone samples using ultrafiltration

    Energy Technology Data Exchange (ETDEWEB)

    Minami, Masayo, E-mail: minami@nendai.nagoya-u.ac.jp [Center for Chronological Research, Nagoya University, Nagoya 464-8602 (Japan); Yamazaki, Kana [Faculty of Science, Nagoya University, Nagoya 464-8602 (Japan); Omori, Takayuki [University Museum, University of Tokyo, Tokyo 113-0033 (Japan); Nakamura, Toshio [Center for Chronological Research, Nagoya University, Nagoya 464-8602 (Japan)

    2013-01-15

    Ultrafiltration can effectively remove low-molecular-weight (LMW) contaminants from bone gelatin to extract high-molecular-weight (HMW) proteins that are derived from original bone collagen, though it cannot remove HMW collagen crosslinked with humic acids. Therefore, ultrafiltration is often used to obtain more accurate {sup 14}C dates of bones. However, ultrafiltration may introduce new contaminants to bone gelatins, mainly from ultrafilters used. To study the effects of ultrafiltration on {sup 14}C age, we analyzed the C/N ratio, {delta}{sup 13}C{sub PDB} and {delta}{sup 15}N{sub AIR} values, and {sup 14}C ages of acid-soluble bone collagen obtained by decalcification, gelatin extracted from acid-insoluble bone collagen, and the HMW gelatin and LMW fractions produced during ultrafiltration of the extracted gelatin. Bone samples from the Fifth International Radiocarbon Intercomparison (VIRI) were used: VIRI-E (mammoth), -F (horse), -G (human), and -I (whale). In this study, carbon and nitrogen content and gelatin yields were used to evaluate collagen preservation in the VIRI bone samples. Radiocarbon ages, {delta}{sup 13}C{sub PDB} and {delta}{sup 15}N{sub AIR} values of unfiltered and HMW gelatins were obtained and compared with the published consensus values. The LMW fraction was found to exhibit different values from those of the other fractions, indicating the possible presence of extraneous contamination. The Vivaspin Trade-Mark-Sign 6 ultrafilters used in this study were analyzed and radiocarbon dated both before and after cleaning. We present evidence to suggest that LMW fraction contaminants could be derived from the ultrafilters rather than humic substances. Excessively long ultrafiltration time was suspected to have contaminated the bone samples with material from the ultrafilter, because those samples exhibited older {sup 14}C ages than did those filtered for shorter durations. The results in this study indicate that {sup 14}C ages of unfiltered

  11. Tohoku University radiocarbon measurements, 6

    International Nuclear Information System (INIS)

    Omoto, Kunio

    1978-01-01

    With check, geomorphic, geologic, archaeological and foreign samples, the 14 C ages reported were mostly measured between November, 1977, and April, 1978. Age measurement and sample processing were the same as before. TH-207 and following dates were measured with a new set of amplifier units and high voltage units linked with Canon SX-350 computer system. Age calculations were based on the contemporary value equal to 95 percent of the activity of NBS oxalic acid standard and on the conventional half-life for 14 C of 5,570 +- 30 years. The results are represented in years before 1950 (years BP). Errors quoted were calculated on the basis of one standard deviation in the statistical error of counting rate of the samples. Sample descriptions are based on the information provided by the submitter. (Mori, K.)

  12. Radiocarbon accelerator mass spectrometry: background and contamination

    International Nuclear Information System (INIS)

    Beukens, R.P.

    1993-01-01

    Since the advent of radiocarbon accelerator mass spectrometry (AMS) many studies have been conducted to understand the background from mass spectrometric processes and the origins of contamination associated with the ion source and sample preparation. By studying the individual contributions a better understanding of these processes has been obtained and it has been demonstrated that it is possible to date samples reliably up to 60 000 BP. (orig.)

  13. Radiocarbon mass spectrometry for drug development

    International Nuclear Information System (INIS)

    Ulrich, Schulze-Konig Tim

    2011-01-01

    Full text: Radiocarbon has a huge potential as a tracer for metabolism studies in humans. By using Accelerator Mass Spectrometry (AMS) for its detection, a unique sensitivity is reached reducing required radiation doses to a negligible level. Until recently, a widespread use of AMS in biomedical research was impeded by the high complexity of the instrument, time-consuming sample preparation, and a limited availability of measurement capacity. Over the last few years, tremendous progress has been achieved in the reduction of size and complexity of AMS instruments. It allowed designing a compact AMS system, dubbed BioMICADAS to address the needs of biomedical users. For more than two years, this system is in successful operation at a commercial service provider for the pharmaceutical industry. A further drastic simplification of radiocarbon mass spectrometers seems possible and could establish a regular usage of this technology in drug development. However, to reach this goal a better integration of AMS into the workflow of bioanalytical laboratories will be necessary. For this purpose, CO 2 accepting ion sources may be a key, since they enable an almost automated sample preparation. The status of radiocarbon AMS in biomedical research and its perspective will be discussed

  14. Accelerator mass spectrometry for radiocarbon dating

    International Nuclear Information System (INIS)

    Bronk, C.R.

    1987-01-01

    Accelerator mass spectrometry (AMS) has been used routinely for radiocarbon measurements for several years. This thesis describes theoretical work to understand the reasons for low accuracy and range and offers practical solutions. The production and transport of the ions used in the measurements are found to be the most crucial stages in the process. The theories behind ion production by sputtering are discussed and applied to the specific case of carbon sputtered by caesium. Experimental evidence is also examined in relation to the theories. The phenomena of space charge and lens aberrations are discussed along with the interaction between ion beams and gas molecules in the vacuum. Computer programs for calculating phase space transformations are then described; these are designed to help investigations of the effects of space charge and aberrations on AMS measurements. Calculations using these programs are discussed in relation both to measured ion beam profiles in phase space and to the current dependent transmission of ions through the Oxford radiocarbon accelerator. Improvements have been made to this accelerator and these are discussed in the context of the calculations. C - ions are produced directly from carbon dioxide at the Middleton High Intensity Sputter Source. Experiments to evaluate the performance of such a source are described and detailed design criteria established. An ion source designed and built specifically for radiocarbon measurements using carbon dioxide is described. Experiments to evaluate its performance and investigate the underlying physical processes are discussed. (author)

  15. Detection of radiocarbon in the cyclotrino

    International Nuclear Information System (INIS)

    Bertsche, K.J.; Karadi, C.A.; Muller, R.A.; Paulson, G.C.

    1990-04-01

    A small low energy cyclotron (the ''cyclotrino''), which was proposed for direct detection of radiocarbon in 1980, has now detected radiocarbon at natural abundance. This device combines the suppression of background through the use of negative ions with the high intrinsic mass resolution of a cyclotron. A high current cesium sputter negative ion source generates a beam of carbon ions which is pre-separated with Wien filter and is transported to the cyclotron via a series of electrostatic lenses. Beam is injected radially into the cyclotron using electrostatic deflectors and an electrostatic mirror. Axial focusing is entirely electrostatic. A microchannel plate detector is used with a phase-gated output. Data is presented showing resolution of radiocarbon at natural abundance. In its present form the system is capable of improving the sensitivity of detecting 14 C in some biomedical experiments by a factor of 10 4 . Modifications are discussed which could bring about an additional factor of 100 in sensitivity, which is important for archaeological and geological applications. Possibilities for measurements of other isotopes are discussed. 16 refs., 7 figs

  16. Low energy cyclotron for radiocarbon dating

    International Nuclear Information System (INIS)

    Welch, J.J.

    1984-12-01

    The measurement of naturally occurring radioisotopes whose half lives are less than a few hundred million years but more than a few years provides information about the temporal behavior of geologic and climatic processes, the temporal history of meteoritic bodies as well as the production mechanisms of these radioisotopes. A new extremely sensitive technique for measuring these radioisotopes at tandem Van de Graaff and cyclotron facilities has been very successful though the high cost and limited availability have been discouraging. We have built and tested a low energy cyclotron for radiocarbon dating similar in size to a conventional mass spectrometer. These tests clearly show that with the addition of a conventional ion source, the low energy cyclotron can perform the extremely high sensitivity 14 C measurements that are now done at accelerator facilities. We found that no significant background is present when the cyclotron is tuned to accelerate 14 C negative ions and the transmission efficiency is adequate to perform radiocarbon dating on milligram samples of carbon. The internal ion source used did not produce sufficient current to detect 14 C directly at modern concentrations. We show how a conventional carbon negative ion source, located outside the cyclotron magnet, would produce sufficient beam and provide for quick sampling to make radiocarbon dating milligram samples with a modest laboratory instrument feasible

  17. 14C age determination for human bones during the Yayoi period - the calibration ambiguity around 2400 BP and the marine reservoir effect

    International Nuclear Information System (INIS)

    Mihara, S.; Miyamoto, K.; Nakamura, T.; Koike, H.

    2004-01-01

    14 C ages for Japanese prehistoric samples from the Latest Jomon period to the early Yayoi period have a calibration ambiguity for dates around 2400 BP. It is also necessary to correct for the marine reservoir effect on 14 C ages of human bone samples from people who consumed marine food as a protein source. The Ohtomo site in western Japan, is a cemetery site used from the end of the Latest Jomon period to the Kofun period, provide a useful archaeological chronology. Human bones found in dolmen burials, jar burials and cist burials. In this study, we determined the 14 C ages of human bone samples and calculated the marine reservoir effect, using diet analysis based on carbon and nitrogen stable isotopes. Diet analysis showed that these people obtained from 40% to 60% of their protein from marine sources. Their 14 C ages with calibration and marine reservoir correction were serially matched with the archaeological chronology

  18. Ethnic variability in body size, proportions and composition in children aged 5 to 11 years: is ethnic-specific calibration of bioelectrical impedance required?

    Directory of Open Access Journals (Sweden)

    Simon Lee

    Full Text Available Bioelectrical Impedance Analysis (BIA has the potential to be used widely as a method of assessing body fatness and composition, both in clinical and community settings. BIA provides bioelectrical properties, such as whole-body impedance which ideally needs to be calibrated against a gold-standard method in order to provide accurate estimates of fat-free mass. UK studies in older children and adolescents have shown that, when used in multi-ethnic populations, calibration equations need to include ethnic-specific terms, but whether this holds true for younger children remains to be elucidated. The aims of this study were to examine ethnic differences in body size, proportions and composition in children aged 5 to 11 years, and to establish the extent to which such differences could influence BIA calibration.In a multi-ethnic population of 2171 London primary school-children (47% boys; 34% White, 29% Black African/Caribbean, 25% South Asian, 12% Other detailed anthropometric measurements were performed and ethnic differences in body size and proportion were assessed. Ethnic differences in fat-free mass, derived by deuterium dilution, were further evaluated in a subsample of the population (n = 698. Multiple linear regression models were used to calibrate BIA against deuterium dilution.In children < 11 years of age, Black African/Caribbean children were significantly taller, heavier and had larger body size than children of other ethnicities. They also had larger waist and limb girths and relatively longer legs. Despite these differences, ethnic-specific terms did not contribute significantly to the BIA calibration equation (Fat-free mass = 1.12+0.71*(height2/impedance+0.18*weight.Although clear ethnic differences in body size, proportions and composition were evident in this population of young children aged 5 to 11 years, an ethnic-specific BIA calibration equation was not required.

  19. Accelerator radiocarbon dating of evidence for prehistoric horticulture in Illinois

    Science.gov (United States)

    Conard, N.; Asch, D.L.; Asch, N.B.; Elmore, D.; Gove, H.; Rubin, M.; Brown, J.A.; Wiant, M.D.; Farnsworth, K.B.; Cook, T.G.

    1984-01-01

    With the development of direct detection radiocarbon dating, which uses an accelerator as part of a highly selective mass spectrometer, it is now possible to determine the age of milligram samples of organic materials1-5. One application of accelerator dating is in evaluating scanty, sometimes controversial evidence for early horticulture throughout the world. We have now used the technique to date small samples of carbonized, cultivated plant remains from archaeological sites in Illinois. The results, reported here, establish (1) that squash was introduced by 7,000 yr ago, 2,500 yr before eastern North American records previously reported; (2) that horticulture involving indigenous plants had begun by 4,000 BP in eastern North America with domestication of Iva annua, a small-seeded annual; (3) that anomalous discoveries of Archaic period maize represent contaminants; and (4) that introduction of maize by initial Middle Woodland times (~2,000 BP) is questionable.

  20. Radiocarbon dating of bone samples by liquid scintillation spectroscopy

    International Nuclear Information System (INIS)

    Lisi, C.S.; Pessenda, L.C.R.; Cruz, M.V.; Pessin, G.; Pazdur, M.F.

    1995-01-01

    It is developed and adapted methodology for radiocarbon dating of bone samples. The collagen, the most representative fraction of age of bone samples, was extracted by Login method. To eliminate/minimize the contamination of gaseous compounds (nitrogen oxides) produced during the collagen combustion, two methods were used: CO 2 precipitation as Ba CO 3 and Sr CO 3 with subsequent acid hydrolysis. It was determined the efficiency of combustion of collagen sample, the performance of methods in the CO 2 purification and the effect of atmospheric 14 CO 2 contamination and radioactivity of reagents in the determination of 14 C activity. To verify the accuracy of the method, it was realized a laboratory intercomparison, analysing bone and collagen samples also dated by 14 C laboratories of Gliwice, Poland and Groningen, the Netherlands. (author). 4 refs, 2 figs, 1 tab

  1. Using accelerator mass spectrometry for radiocarbon dating of textiles

    Energy Technology Data Exchange (ETDEWEB)

    Jull, A.J.T.

    1997-12-01

    Since 1981 we have operated an NSF Accelerator Mass Spectrometry (AMS) Facility at the University of Arizona. The AMS method allows us to use very small samples of carbon, <1 mg for radiocarbon dating in contrast to earlier counting techniques. This has opened a vast array of applications of radiocarbon dating that was difficult to do before AMS because of sample size limitations of decay counting. Some of the many applications of AMS include paleoclimatic studies, archaeological research and the age of first settlement of North America by man, dating of art works and artifacts, fall times and terrestrial residence ages of meteorites, production of {sup 14}C in lunar samples by galactic and solar cosmic rays, studies of in situ {sup 14}C produced by cosmic ray spallation in rocks and ice, and studies of {sup 14}C in groundwater dissolved inorganic carbon and dissolved organic carbon. At our laboratory, we have also successfully applied AMS {sup 14}C to dating of many types of textiles, including silks and linens, art works, documents and artifacts fabricated from wood, parchment, ivory, and bone. The results for many of these samples are often important in questions of the authenticity of these works of art and artifacts. Our studies have encompassed a wide range of art works ranging from the Dead Sea Scrolls, the Shroud of Turin, and the Chinese silk trade to the works of Raphael, Rembrandt, and Picasso. Recently, we also dated the Vinland Map, a controversial document that shows the eastern coast of North America apparently using information from Viking voyages.

  2. The Remarkable Metrological History of Radiocarbon Dating [II].

    Science.gov (United States)

    Currie, Lloyd A

    2004-01-01

    This article traces the metrological history of radiocarbon, from the initial breakthrough devised by Libby, to minor (evolutionary) and major (revolutionary) advances that have brought (14)C measurement from a crude, bulk [8 g carbon] dating tool, to a refined probe for dating tiny amounts of precious artifacts, and for "molecular dating" at the 10 µg to 100 µg level. The metrological advances led to opportunities and surprises, such as the non-monotonic dendrochronological calibration curve and the "bomb effect," that gave rise to new multidisciplinary areas of application, ranging from archaeology and anthropology to cosmic ray physics to oceanography to apportionment of anthropogenic pollutants to the reconstruction of environmental history. Beyond the specific topic of natural (14)C, it is hoped that this account may serve as a metaphor for young scientists, illustrating that just when a scientific discipline may appear to be approaching maturity, unanticipated metrological advances in their own chosen fields, and unanticipated anthropogenic or natural chemical events in the environment, can spawn new areas of research having exciting theoretical and practical implications.

  3. Physical Research Laboratory radiocarbon 14C dates : CS-I

    International Nuclear Information System (INIS)

    Agrawal, D.P.; Krishnamurthy, R.V.; Kusumgar, Sheela; Pant, R.K.

    1978-01-01

    The 14 C dates of archaeological samples measured at the Radiocarbon Laboratory of the Physical Research Laboratory, Ahmedabad are presented. Samples were converted into methane and measured in gas proportional counters. Ninety-five percent activity of NBS oxalic acid was used as modern standard. The dates in years B.P. are given for each sample based on the half-life values of 5568 +- 30 years and 5730 +- 40 years, the latter within parenthesis. The dates are not calibrated for 14 C/ 12 C variations. To convert the dates into AD/BC scale, 1950 AD should be used as reference year. A number of 14 C dates (PRL-81, -83, -67, -68) now confirm that the Painted Grey Ware culture extended upto the 3rd century BC. Some of the dates from Barkhera (PRL-113), Bateshwar (PRL-200), Bhimbetka (PRL-17) and Koldihawa (PRL-100, 101) are older than normally expected, probably indicative of some hitherto unknown basal cultures in these regions. 14 C dates on in situ Megalithic materials do not seem to go beyond 200 BC. (author)

  4. Radiocarbon clock strikes the glacial period pulse

    International Nuclear Information System (INIS)

    Serebryannyj, L.R.

    1976-01-01

    Discussed are some aspects of the theory of radiocarbon dating in application to the study of the history of the Earth. The accumulation and the decay of C 14 and methods for its recording are desribed. Presented is a block diagram of a scintillation counter for recording C 14 . The chronology of the last glaciation of Europe has been determined: the Interglacial period (between 50 and 40 thousand years) a prolonged preglacil period (between 40 and 25 thousand years), the last glaciation (between 25 and 10 thousand years ago)

  5. Analysis of past recurrent methane seep activity using radiocarbon dating of Calyptogena spp. shells in the eastern Nankai subduction zone, Japan

    Science.gov (United States)

    Yagasaki, Kazuhiro; Ashi, Juichiro; Yokoyama, Yusuke; Miyairi, Yosuke; Kuramoto, Shin'ichi

    2016-04-01

    Fault activity around subduction zones have been widely studied and monitored through drilling of oceanic plates, studying piston cores, use of monitoring equipment or through visual analysis using submersible vehicles. Yet the understanding of how small scale faults near shallow regions of the seabed behave in relation to cold seep vent activity is still vague, especially determining when they were active in the past. In tectonically active margins such as the Nankai and Tokai regions off Japan, dense methane hydrate reservoirs have been identified. Cold seeps releasing methane rich hydrocarbon fluids are common here, supporting a wide variety of biological species that hold a symbiotic relationship with the chemosynthetic bacteria. In 1998 a large dead Calyptogena spp. bivalve colony (over 400m2 in size) was discovered off Tokai, Japan. It is unusual for a bivalve colony this size to mostly be dead, raising questions as to what caused their death. In this study we document the radiocarbon 14C age of these bivalve shells to attempt analysing the possible methane seep bahaviour in the past. The measured 14C age ranged in three age groups of 1396±36-1448±34, 1912±31-1938±35 and 5975±34. The 14C age of shells that were alive upon collection and the dissolved inorganic carbon (DIC) in seawater show little difference (˜100 14C age) indicating that shells are not heavily affected by the dead carbon effect from cold seeps that is of biogenic or thermogenic origin, which can make the age to become considerably older than the actual age. Thus the novel calibration model used was based on the seawater DIC collected above the Calyptogena spp. colony site (1133±31), which resulted in the dead shells to be clustered around 1900 Cal AD. This proves to be interesting as the predicted epicenter of the Ansei-Tokai earthquake (M 8.4) in 1854 is extremely close to the bibalve colony site. Using geological data obtained using visual analysis and sub-seafloor structural

  6. Second radiocarbon intercomparison program for the Chauvet-Pont d'Arc cave, Ardeche, France

    International Nuclear Information System (INIS)

    Quiles, A.; Valladas, H.; Kaltnecker, E.; Geneste, J.M.; Clottes, J.; Berthier, B.; Delque-Kolic, E.; Dumoulin, J.P.

    2014-01-01

    The Chauvet-Pont d'Arc Cave is one of the most important sites for the study of the earliest manifestations and development of prehistoric art at the beginning of the Upper Paleolithic. Different dating techniques have been performed thus far (AMS 14 C, U/Th TIMS, 36 Cl dating) to model the chronological framework of this decorated cave. The cave yielded several large charcoal fragments, which enabled the opportunity for obtaining multiple dates; thus, a First Radiocarbon Intercomparison Program (FIP) was initiated in 2004 using three charcoal pieces. The FIP demonstrated that those cross-dated samples belonged to a time period associated with the first human occupation. One of the statistical interests of an intercomparison program is to reduce the uncertainty on the sample age; thus, to further assess the accuracy of the chronological framework, the Second Intercomparison Program (SIP) involving 10 international 14 C laboratories was carried out on two pieces of charcoal found inside two hearth structures of the Galerie des Megaceros. Each laboratory used its own pretreatment and AMS facilities. In total, 21 and 22 measurements were performed, respectively, which yielded consistent results averaging ∼32 ka BP. Two strategies have currently been developed to identify statistical outliers and to deal with them; both lead to quasi-identical calibrated combined densities. Finally, the new results were compared with those of the FIP, leading to the important conclusion that five different samples from at least three different hearth structures give really tightened temporal densities, associated with one short human occupation in the Galerie des Megaceros. (authors)

  7. Radiocarbon and other radionuclide studies using accelerator mass spectrometry

    International Nuclear Information System (INIS)

    Jull, A.J.T.; Donahue, D.J.; Burr, G.S.; Beck, J.W.; McHargue, L.R.; Hatheway, A.L.; Lange, T.E.; O'Malley, J.M.; Biddulph, D.L.

    2002-01-01

    The research program at our laboratory encompasses a wide range of applications of AMS radiocarbon dating. We highlight some of our methods as well as some of these radiocarbon applications in this paper. We also discuss results of 10 Be and 129 I measurements made on the new 3MV AMS machine in Tucson. (author)

  8. Gaseous radiocarbon measurements of small samples

    International Nuclear Information System (INIS)

    Ruff, M.; Szidat, S.; Gaeggeler, H.W.; Suter, M.; Synal, H.-A.; Wacker, L.

    2010-01-01

    Radiocarbon dating by means of accelerator mass spectrometry (AMS) is a well-established method for samples containing carbon in the milligram range. However, the measurement of small samples containing less than 50 μg carbon often fails. It is difficult to graphitise these samples and the preparation is prone to contamination. To avoid graphitisation, a solution can be the direct measurement of carbon dioxide. The MICADAS, the smallest accelerator for radiocarbon dating in Zurich, is equipped with a hybrid Cs sputter ion source. It allows the measurement of both, graphite targets and gaseous CO 2 samples, without any rebuilding. This work presents experiences dealing with small samples containing 1-40 μg carbon. 500 unknown samples of different environmental research fields have been measured yet. Most of the samples were measured with the gas ion source. These data are compared with earlier measurements of small graphite samples. The performance of the two different techniques is discussed and main contributions to the blank determined. An analysis of blank and standard data measured within years allowed a quantification of the contamination, which was found to be of the order of 55 ng and 750 ng carbon (50 pMC) for the gaseous and the graphite samples, respectively. For quality control, a number of certified standards were measured using the gas ion source to demonstrate reliability of the data.

  9. A coherent high-precision radiocarbon chronology for the Late-glacial sequence at Sluggan Bog, Co. Antrim, Northern Ireland

    Science.gov (United States)

    Lowe, J. J.; Walker, M. J. C.; Scott, E. M.; Harkness, D. D.; Bryant, C. L.; Davies, S. M.

    2004-02-01

    Seventy-five radiocarbon dates are presented from Sluggan Bog in Co. Antrim, Northern Ireland. The Holocene peats are underlain by Late-glacial sediments, which also appear to have accumulated largely in a mire environment. The radiocarbon dates, from the Late-glacial and early Holocene part of the profile, were obtained from the humic and humin fractions of the sedimentary matrix, and from plant macrofossils. The last-named were dated by AMS and the sediment samples by radiometric (beta counting) methods. Age-depth models for the three dating series show a very high level of agreement between the two fractions and the macrofossils. No statistically significant difference is found between the beta counting and AMS results. Three tephras were located in the profile, the uppermost of which is in a stratigraphical position suggestive of the Vedde Ash, but the geochemical and radiocarbon evidence do not support this interpretation. The lower ashes are in the correct stratigraphical position for the Laacher See and Borrobol tephras, attributions substantiated by the radiocarbon evidence, but not by the geochemical data. The Sluggan sequence has generated one of the most internally consistent radiocarbon chronologies for any Late-glacial site in the British Isles, and it is suggested that in future more effort should be devoted to the search for, and analysis of, Late-glacial mire sequences, rather than the limnic records that have formed the principal focus of Late-glacial investigations hitherto. Copyright

  10. NotCal04 : Comparison/calibration C-14 records 26-50 cal kyr BP

    NARCIS (Netherlands)

    Plicht, J. van der; Beck, J.W.; Bard, E.; Baillie, M.G.L.; Blackwell, P.G.; Buck, C.E.; Friedrich, M.; Guilderson, T.P.; Hughen, K.A.; Kromer, B.; McCormac, F.G.; Bronk Ramsey, C.; Reimer, P.J.; Reimer, R.W.; Remmele, S.; Richards, D.A.; Southon, J.R.; Stuiver, M.; Weyhenmeyer, C.E.

    2004-01-01

    The radiocarbon calibration curve ImCal04 extends back to 26 cal kyr BP. While several high-resolution records exist beyond this limit, these data sets exhibit discrepancies of up, to several millennia. As a result, no calibration curve for the time range 26-50 cal kyr BP can be recommended as yet,

  11. The Geological Survey of Canada Radiocarbon Dating Laboratory

    International Nuclear Information System (INIS)

    Lowdon, J.A.

    1985-01-01

    The Radiocarbon Dating Laboratory of the Geological Survey of Canada began routine 14 C age determinations in 1961 using a 2 litre copper, proportional counter and CO 2 as the counting gas. This counter is operated routinely at a pressure of 2 atmospheres where the maximum dating limit is approximately 40 000 years using the 4σ criterion. In 1964 a 5 litre counter was put into operation. Routinely this counter is operated at a pressure of 1 atmosphere where its dating limit is approximately 40 000 years. When operated at 4 atmospheres its age limit increases to about 54 000 years. Organic samples are burned in a stream of oxygen and the CO 2 released is purified on passage through a series of chemicals and traps. Inorganic samples are dissolved in phosphoric acid. Up to the end of 1983 more than 3700 age determinations have been carried out on various types of sample material. Since 1963 twenty-three Geological Survey of Canada Date Lists have been published. The Laboratory also carries out a program of 14 C determinations of samples of known age for the purpose of assessing the accuracy of the method and learning more about the natural and man-made 14 C distribution and circulation in nature

  12. Direct radiocarbon dating and DNA analysis of the Darra-i-Kur (Afghanistan) human temporal bone.

    Science.gov (United States)

    Douka, Katerina; Slon, Viviane; Stringer, Chris; Potts, Richard; Hübner, Alexander; Meyer, Matthias; Spoor, Fred; Pääbo, Svante; Higham, Tom

    2017-06-01

    The temporal bone discovered in the 1960s from the Darra-i-Kur cave in Afghanistan is often cited as one of the very few Pleistocene human fossils from Central Asia. Here we report the first direct radiocarbon date for the specimen and the genetic analyses of DNA extracted and sequenced from two areas of the bone. The new radiocarbon determination places the find to ∼4500 cal BP (∼2500 BCE) contradicting an assumed Palaeolithic age of ∼30,000 years, as originally suggested. The DNA retrieved from the specimen originates from a male individual who carried mitochondrial DNA of the modern human type. The petrous part yielded more endogenous ancient DNA molecules than the squamous part of the same bone. Molecular dating of the Darra-i-Kur mitochondrial DNA sequence corroborates the radiocarbon date and suggests that the specimen is younger than previously thought. Taken together, the results consolidate the fact that the human bone is not associated with the Pleistocene-age deposits of Darra-i-Kur; instead it is intrusive, possibly re-deposited from upper levels dating to much later periods (Neolithic). Despite its Holocene age, the Darra-i-Kur specimen is, so far, the first and only ancient human from Afghanistan whose DNA has been sequenced. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Perspectives in radiocarbon dating by radiometry

    International Nuclear Information System (INIS)

    Polach, H.A.

    1987-01-01

    Opportunities for individual contributions to the technology of radiocarbon dating over the past 40 years have been large. Meaningful developments are traced in this review of C-14 dating by gas proportional (GP) and liquid scintillation (LS) spectrometry. The performance of characteristic as well as state of the art GP and LS systems is tabulated and their merit for low-level counting of C-14 is evaluated. Future developments in radiometry will lie in the updating of existing systems to incorporate new technologies and the refinement of resolution and identification of extreme low-level signals. Parallel development with AMS, sharing on merit the ever widening applied C-14 research field, and enhanced interdisciplinary collaboration are foreseen as the scenario leading to the year 2000

  14. Perspectives in radiocarbon dating by radiometry

    International Nuclear Information System (INIS)

    Polach, H.A.

    1987-01-01

    Opportunities for individual contributions to the technology of radiocarbon dating over the past 40 years have been large. Meaningful developments are traced in this review of C-14 dating by gas proportional (GP) and liquid scintillation (LS) spectrometry. The performance of characteristic as well as state of the art GP and LS systems is tabulated and their merit for low-level counting of C-14 is evaluated. Future developments in radiometry will lie in the updating of existing systems to incorporate new technologies and the refinement of resolution and identification of extreme low-level signals. Parallel development with AMS, sharing on merit the ever widening applied C-14 research field, and enhanced interdisciplinary collaboration are foreseen as the scenario leading to the year 2000. (orig.)

  15. Radiocarbon dating in the quarternary geology and archaeology of Estonia

    International Nuclear Information System (INIS)

    Ilves, Eh.; Liiva, A.; Punning, Ya.M.

    1974-01-01

    Work of the Tartusk radiocarbon laboratory for the last 15 years is presented. Methodological problems of the radiocarbon method are discussed. The geochemistry of carbon isotopes, principles of radiocarbon dating, and areas of its application are considered. Methods of recording natural radiocarbon and materials used for radiocarbon dating are discussed. Preliminary treatment of the samples and synthesis of the radioactive carbon carrier are presented. The preparation of the counter compound in the form of a liquid scintillator from the synthesized natural radiocarbon carrier is described. The scintillator efficiencies of different scintillators are compared. Data are given on the development of criteria for selecting the photoelectron multiplier. Construction of alumina cuvettes used for scintillation counting is described. It is noted that, in the counter apparatus system, amplitude analyzers with two differential discriminators are used, which allows directing the recording of activity to two 14 C regions. The results of using the radiocarbon method for different aspects of natural science and archeology are considered. Problems of geology of the late Pleistocene and the Pre-Baltic Holocene are considered: base of the mid-Valdaisk Karukyulask interglacier, history of deterioration of the final glacial mantle, development of a drainage system and late glacier, development and paleography of the Holocene, and others. New material on the chronology of primeval cultures in the Estonia region and on growth of meteoric craters are presented

  16. Optimization of simultaneous tritium–radiocarbon internal gas proportional counting

    Energy Technology Data Exchange (ETDEWEB)

    Bonicalzi, R.M. [Seattle Central College, 1701 Broadway, Seattle, WA 98122 (United States); Aalseth, C.E.; Day, A.R.; Hoppe, E.W. [Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, WA 99352 (United States); Mace, E.K., E-mail: Emily.Mace@pnl.gov [Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, WA 99352 (United States); Moran, J.J.; Overman, C.T.; Panisko, M.E.; Seifert, A. [Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, WA 99352 (United States)

    2016-03-21

    Specific environmental applications can benefit from dual tritium and radiocarbon measurements in a single compound. Assuming typical environmental levels, it is often the low tritium activity relative to the higher radiocarbon activity that limits the dual measurement. In this paper, we explore the parameter space for a combined tritium and radiocarbon measurement using a natural methane sample mixed with an argon fill gas in low-background proportional counters of a specific design. We present an optimized methane percentage, detector fill pressure, and analysis energy windows to maximize measurement sensitivity while minimizing count time. The final optimized method uses a 9-atm fill of P35 (35% methane, 65% argon), and a tritium analysis window from 1.5 to 10.3 keV, which stops short of the tritium beta decay endpoint energy of 18.6 keV. This method optimizes tritium-counting efficiency while minimizing radiocarbon beta-decay interference. - Highlights: • Use of a single compound (methane) for dual tritium and radiocarbon measurements. • Optimized analysis window for simultaneous tritium and radiocarbon measurement. • Allows for optimization of tritium counting in the presence of radiocarbon.

  17. Calibration of a transient transport model to tritium data in streams and simulation of groundwater ages in the western Lake Taupo catchment, New Zealand

    Directory of Open Access Journals (Sweden)

    M. A. Gusyev

    2013-03-01

    Full Text Available Here we present a general approach of calibrating transient transport models to tritium concentrations in river waters developed for the MT3DMS/MODFLOW model of the western Lake Taupo catchment, New Zealand. Tritium has a known pulse-shaped input to groundwater systems due to the bomb tritium in the early 1960s and, with its radioactive half-life of 12.32 yr, allows for the determination of the groundwater age. In the transport model, the tritium input (measured in rainfall passes through the groundwater system, and the simulated tritium concentrations are matched to the measured tritium concentrations in the river and stream outlets for the Waihaha, Whanganui, Whareroa, Kuratau and Omori catchments from 2000–2007. For the Kuratau River, tritium was also measured between 1960 and 1970, which allowed us to fine-tune the transport model for the simulated bomb-peak tritium concentrations. In order to incorporate small surface water features in detail, an 80 m uniform grid cell size was selected in the steady-state MODFLOW model for the model area of 1072 km2. The groundwater flow model was first calibrated to groundwater levels and stream baseflow observations. Then, the transient tritium transport MT3DMS model was matched to the measured tritium concentrations in streams and rivers, which are the natural discharge of the groundwater system. The tritium concentrations in the rivers and streams correspond to the residence time of the water in the groundwater system (groundwater age and mixing of water with different age. The transport model output showed a good agreement with the measured tritium values. Finally, the tritium-calibrated MT3DMS model is applied to simulate groundwater ages, which are used to obtain groundwater age distributions with mean residence times (MRTs in streams and rivers for the five catchments. The effect of regional and local hydrogeology on the simulated groundwater ages is investigated by demonstrating groundwater ages

  18. The immigration and spread of spruce forest in Norway, traced by biostratigraphical studies and radiocarbon datings. A preliminary report

    International Nuclear Information System (INIS)

    Hafsten, U.

    1985-01-01

    Pollen-analytic studies and radiocarbon datings from 86 sites, mostly ombrotrophic peatbogs, situated within the Norwegian spruce domain, show that the occupation of the areas by spruce forest was the result of a protracted spread from cast, or northeast, to west and south, which started in late pre-Christian time and was completed mainly during the Middle Ages

  19. Radiocarbon and optically stimulated luminescence dating based chronology of a polycyclic driftsand sequence at Weerterbergen (SE Netherlands)

    NARCIS (Netherlands)

    van Mourik, J.M.; Nierop, K.G.J.; Vandenberghe, D.A.G.

    2010-01-01

    The chronology of polycyclic driftsand sequences in cultural landscapes has mainly been based on the combination of radiocarbon (14C) dating of intercalated organic horizons and pollen analysis. This approach, however, yields indirect age information for the sediment units. Also, as soils are

  20. Optimal model of radiocarbon residence time in exchange reservoir

    International Nuclear Information System (INIS)

    Dergachev, V.A.

    1977-01-01

    Radiocarbon content variations in the earth atmosphere were studied using a mathematical model. The so-called exchange reservoir was considered consisting of layers, and the radiocarbon exchange rate at the interfaces between these layers was supposed to be constant. The process of 14 C mixing and exchange in a dynamic system is described by a system of nonhomogeneous 1st order differential equations. The model also accounts for the change in rate of radiocarbon formation in the earth atmosphere due to cosmic and geophysical effects (solar activity, solar cycle, etc.). (J.P.)

  1. Enhancing sample preparation capabilities for accelerator mass spectrometry radiocarbon and radiocalcium studies

    International Nuclear Information System (INIS)

    Taylor, R.E.

    1991-01-01

    With support provided by the LLNL Accelerator Mass Spectrometry Laboratory, the UCR Radiocarbon Laboratory continued its studies involving sample pretreatment and target preparation for both AMS radiocarbon ( 14 C) and radiocalcium ( 41 Ca) involving applications to archaeologically -- and paleoanthropologically- related samples. With regard to AMS 14 C-related studies, we have extended the development of a series of procedures which have, as their initial goal, the capability to combust several hundred microgram amounts of a chemically-pretreated organic sample and convert the resultant CO 2 to graphitic carbon which will consistently yield relatively high 13 C - ion currents and blanks which will yield, on a consistent basis, 14 C count rates at or below 0.20% modern, giving an 2 sigma age limit of >50,000 yr BP

  2. Radiocarbon dating of floodplain and young terraces alluvial sediments of Latvia rivers

    International Nuclear Information System (INIS)

    Eberhards, G.; Saltupe, B.

    2000-01-01

    This paper include new information about alluvial sediments structure and radiocarbon data of some Latvia free-meandering rivers (Gauja, Ogre, Liela and Maza Jugla, Daugava) floodplains and first terraces. In this present study we examined Gauja river floodplains in the different geomorphological and geological areas. Radiocarbon dating add the fact that the high level floodplain (4-5 m) formation and sediment accumulation take place 3000-5000 years before present (BP) middle level floodplains formed 1500-2100 years BP. Investigations show that one river terraces and floodplains with same relative height have a several absolute age. The rivers crossed same hypsometrical regions (highlands, lowlands) downstream in lowlands alluvial terraces performed as floodplains or from from floodplains to terraces with same height. On the highest, middle and in the lower parts of the rivers with free - meandering channel to - day the dynamic balance of the channel processes exits 4000-5000 years. (author)

  3. Gas chromatographic isolation of individual compounds from complex matrices for radiocarbon dating.

    Science.gov (United States)

    Eglinton, T I; Aluwihare, L I; Bauer, J E; Druffel, E R; McNichol, A P

    1996-03-01

    This paper describes the application of a novel, practical approach for isolation of individual compounds from complex organic matrices for natural abundance radiocarbon measurement. This is achieved through the use of automated preparative capillary gas chromatography (PCGC) to separate and recover sufficient quantities of individual target compounds for (14)C analysis by accelerator mass spectrometry (AMS). We developed and tested this approach using a suite of samples (plant lipids, petroleums) whose ages spanned the (14)C time scale and which contained a variety of compound types (fatty acids, sterols, hydrocarbons). Comparison of individual compound and bulk radiocarbon signatures for the isotopically homogeneous samples studied revealed that Δ(14)C values generally agreed well (±10%). Background contamination was assessed at each stage of the isolation procedure, and incomplete solvent removal prior to combustion was the only significant source of additional carbon. Isotope fractionation was addressed through compound-specific stable carbon isotopic analyses. Fractionation of isotopes during isolation of individual compounds was minimal (radiocarbon measurements. The addition of carbon accompanying derivatization of functionalized compounds (e.g., fatty acids and sterols) prior to chromatographic separation represents a further source of potential error. This contribution can be removed using a simple isotopic mass balance approach. Based on these preliminary results, the PCGC-based approach holds promise for accurately determining (14)C ages on compounds specific to a given source within complex, heterogeneous samples.

  4. The measure of radiocarbon in the drating of environmental samples

    International Nuclear Information System (INIS)

    Ruiz Pessenda, L.C.; Camargo, P.B. de

    1990-01-01

    An analytical system for radiocarbon dating of environmental samples (charcoal, shell, wood, etc.) using low level liquid scintillation spectrometry has been developed and optimized at Center for Nuclear Energy in Agriculture of the University of Sao Paulo. Physical and chemical pretreatment of samples to remove oils, resins, carbonates and fulvic and humic acids; the benzene synthesis of NBS oxalic acid standard, calcium carbonate P.A. and marble and the results of benzene yield; the optimization of radiocarbon counting window; the effect of scintillators PPO-POPOP and butyl PBD on the efficiency of detection and background of radiocarbon, are described. Samples of charcoal, shell and wood, previously dated at the radiocarbon laboratories of Centre des Faibles Radioactives, France, and Instituto de Geociencias of USP, are analysed for preliminary laboratory intercomparison. (author) [pt

  5. Optimization of simultaneous tritium–radiocarbon internal gas proportional counting

    Energy Technology Data Exchange (ETDEWEB)

    Bonicalzi, R. M.; Aalseth, C. E.; Day, A. R.; Hoppe, E. W.; Mace, E. K.; Moran, J. J.; Overman, C. T.; Panisko, M. E.; Seifert, A.

    2016-03-01

    Specific environmental applications can benefit from dual tritium and radiocarbon measurements in a single compound. Assuming typical environmental levels, it is often the low tritium activity relative to the higher radiocarbon activity that limits the dual measurement. In this paper, we explore the parameter space for a combined tritium and radiocarbon measurement using a methane sample mixed with an argon fill gas in low-background proportional counters of a specific design. We present an optimized methane percentage, detector fill pressure, and analysis energy windows to maximize measurement sensitivity while minimizing count time. The final optimized method uses a 9-atm fill of P35 (35% methane, 65% argon), and a tritium analysis window from 1.5 to 10.3 keV, which stops short of the tritium beta decay endpoint energy of 18.6 keV. This method optimizes tritium counting efficiency while minimizing radiocarbon beta decay interference.

  6. Calibration uncertainty

    DEFF Research Database (Denmark)

    Heydorn, Kaj; Anglov, Thomas

    2002-01-01

    Methods recommended by the International Standardization Organisation and Eurachem are not satisfactory for the correct estimation of calibration uncertainty. A novel approach is introduced and tested on actual calibration data for the determination of Pb by ICP-AES. The improved calibration...

  7. Mass spectrometric detection of radiocarbon for dating applications

    OpenAIRE

    Synal Hans-Arno

    2013-01-01

    Radiocarbon is still the most important nuclide measured by accelerator mass spectrometry (AMS). The related capabilities for dating and tracer studies are eminent not only in archaeology but also drive important applications in the earth and environmental sciences as well as in biomedical research. So far standard mass spectrometric systems have not been capable of radiocarbon dating because of interfering molecular isobars which however can be completely eliminated in charge changing proces...

  8. Mass spectrometric detection of radiocarbon for dating applications

    Energy Technology Data Exchange (ETDEWEB)

    Synal, H.-A., E-mail: synal@phys.ethz.ch [ETH Zurich, Laboratory of Ion Beam Physics, Building HPK, 8093 Zurich (Switzerland); Schulze-Koenig, T.; Seiler, M.; Suter, M.; Wacker, L. [ETH Zurich, Laboratory of Ion Beam Physics, Building HPK, 8093 Zurich (Switzerland)

    2013-01-15

    Radiocarbon is still the most important nuclide measured by accelerator mass spectrometry (AMS). The related capabilities for dating and tracer studies are eminent not only in archaeology but also drive important applications in the earth and environmental sciences as well as in biomedical research. So far, standard mass spectrometric systems have not been capable of radiocarbon dating because of interfering molecular isobars which, however, can be completely eliminated in charge changing processes at high ion beam energies (MeV) [1,2]. Here, we present a novel type mass spectrometry system for radiocarbon analyses. Radiocarbon dating was performed using 45 keV {sup 14}C ions from the ion source and a molecule dissociation unit kept at ground potential. This proof-of-principle experiment demonstrates for the first time the feasibility of mass spectrometric radiocarbon dating without an accelerator. The results obtained will be the basis of an optimized design for a radiocarbon dating instrument comparable in size, complexity and cost to standard mass spectrometers.

  9. Mass spectrometric detection of radiocarbon for dating applications

    International Nuclear Information System (INIS)

    Synal, H.-A.; Schulze-König, T.; Seiler, M.; Suter, M.; Wacker, L.

    2013-01-01

    Radiocarbon is still the most important nuclide measured by accelerator mass spectrometry (AMS). The related capabilities for dating and tracer studies are eminent not only in archaeology but also drive important applications in the earth and environmental sciences as well as in biomedical research. So far, standard mass spectrometric systems have not been capable of radiocarbon dating because of interfering molecular isobars which, however, can be completely eliminated in charge changing processes at high ion beam energies (MeV) [1,2]. Here, we present a novel type mass spectrometry system for radiocarbon analyses. Radiocarbon dating was performed using 45 keV 14 C ions from the ion source and a molecule dissociation unit kept at ground potential. This proof-of-principle experiment demonstrates for the first time the feasibility of mass spectrometric radiocarbon dating without an accelerator. The results obtained will be the basis of an optimized design for a radiocarbon dating instrument comparable in size, complexity and cost to standard mass spectrometers.

  10. Mass spectrometric detection of radiocarbon for dating applications

    Science.gov (United States)

    Synal, H.-A.; Schulze-König, T.; Seiler, M.; Suter, M.; Wacker, L.

    2013-01-01

    Radiocarbon is still the most important nuclide measured by accelerator mass spectrometry (AMS). The related capabilities for dating and tracer studies are eminent not only in archaeology but also drive important applications in the earth and environmental sciences as well as in biomedical research. So far, standard mass spectrometric systems have not been capable of radiocarbon dating because of interfering molecular isobars which, however, can be completely eliminated in charge changing processes at high ion beam energies (MeV) [1,2]. Here, we present a novel type mass spectrometry system for radiocarbon analyses. Radiocarbon dating was performed using 45 keV 14C ions from the ion source and a molecule dissociation unit kept at ground potential. This proof-of-principle experiment demonstrates for the first time the feasibility of mass spectrometric radiocarbon dating without an accelerator. The results obtained will be the basis of an optimized design for a radiocarbon dating instrument comparable in size, complexity and cost to standard mass spectrometers.

  11. Predicted net efflux of radiocarbon from the ocean and increase in atmospheric radiocarbon content

    Science.gov (United States)

    Caldeira, Ken; Rau, Greg H.; Duffy, Philip B.

    Prior to changes introduced by man, production of radiocarbon (14C) in the stratosphere nearly balanced the flux of 14C from the atmosphere to the ocean and land biosphere, which in turn nearly balanced radioactive decay in these 14C reservoirs. This balance has been altered by land-use changes, fossil-fuel burning, and atmospheric nuclear detonations. Here, we use a model of the global carbon cycle to quantify these radiocarbon fluxes and make predictions about their magnitude in the future. Atmospheric nuclear detonations increased atmospheric 14C content by about 80% by the mid-1960's. Since that time, the 14C content of the atmosphere has been diminishing as this bomb radiocarbon has been entering the oceans and terrestrial biosphere. However, we predict that atmospheric 14C content will reach a minimum and start to increase within the next few years if fossil-fuel burning continues according to a “business-as-usual” scenario, even though fossil fuels are devoid of 14C. This will happen because fossil-fuel carbon diminishes the net flux of 14C from the atmosphere to the oceans and land biosphere, forcing 14C to accumulate in the atmosphere. Furthermore, the net flux of both bomb and natural 14C into the ocean are predicted to continue to slow and then, in the middle of the next century, to reverse, so that there will be a net flux of 14C from the ocean to the atmosphere. The predicted reversal of net 14C fluxes into the ocean is a further example of human impacts on the global carbon cycle.

  12. Atmospheric radiocarbon as a Southern Ocean wind proxy over the last 1000 years

    Science.gov (United States)

    Rodgers, K. B.; Mikaloff Fletcher, S.; Galbraith, E.; Sarmiento, J. L.; Gnanadesikan, A.; Slater, R. D.; Naegler, T.

    2009-04-01

    Measurements of radiocarbon in tree rings over the last 1000 years indicate that there was a pre-industrial latitudinal gradient of atmospheric radiocarbon of 3.9-4.5 per mail and that this gradient had temporal variability of order 6 per mil. Here we test the idea that the mean gradient as well as variability in he gradient is dominated by the strength of the winds over the Southern Ocean. This is done using an ocean model and an atmospheric transport model. The ocean model is used to derive fluxes of 12CO2 and 14CO2 at the sea surface, and these fluxes are used as a lower boundary condition for the transport model. For the mean state, strong winds in the Southern Ocean drive significant upwelling of radiocarbon-depleted Circumpolar Deep Water (CDW), leading to a net flux of 14CO2 relative to 12CO2 into the ocean. This serves to maintain a hemispheric gradient in pre-anthropogenic atmospheric delta-c14. For perturbations, increased/decreased Southern Ocean winds drive increased/decreased uptake of 14CO2 relative to 12CO2, thus increasing/decreasing the hemispheric gradient in atmospheric delta-c14. The tree ring data is interpreted to reveal a decrease in the strength of the Southern Ocean winds at the transition between the Little Ice Age and the Medieval Warm Period.

  13. Radiocarbon constraints on the glacial ocean circulation and its impact on atmospheric CO2

    Science.gov (United States)

    Skinner, L. C.; Primeau, F.; Freeman, E.; de la Fuente, M.; Goodwin, P. A.; Gottschalk, J.; Huang, E.; McCave, I. N.; Noble, T. L.; Scrivner, A. E.

    2017-01-01

    While the ocean’s large-scale overturning circulation is thought to have been significantly different under the climatic conditions of the Last Glacial Maximum (LGM), the exact nature of the glacial circulation and its implications for global carbon cycling continue to be debated. Here we use a global array of ocean–atmosphere radiocarbon disequilibrium estimates to demonstrate a ∼689±53 14C-yr increase in the average residence time of carbon in the deep ocean at the LGM. A predominantly southern-sourced abyssal overturning limb that was more isolated from its shallower northern counterparts is interpreted to have extended from the Southern Ocean, producing a widespread radiocarbon age maximum at mid-depths and depriving the deep ocean of a fast escape route for accumulating respired carbon. While the exact magnitude of the resulting carbon cycle impacts remains to be confirmed, the radiocarbon data suggest an increase in the efficiency of the biological carbon pump that could have accounted for as much as half of the glacial–interglacial CO2 change. PMID:28703126

  14. The comparison of absolute dating (Radiocarbon dating) and relative dating of Pringapus and Gondosuli temples

    International Nuclear Information System (INIS)

    Faisal, W; Arumbinang, H; Taftazani, A; Widayati, S; Sumiyatno; Suhardi

    1996-01-01

    The absolute dating (radiocarbon, 14 C dating) and relative dating of Pringapus and Gondosuli temples in Temanggung regency (district) of Central Java Province have been carried out. The field sampling was done especially with the purpose to obtain vertical data, so that excavation method was adopted in the case. The main data were the ecofacts of organic habitation such as bones, woods, charcoals, shells, and paper artefacts. The artefacts data were used as a comparison. The comparative data analysis were conducted at Yogyakarta archaeological Department Laboratory, thus included dating of artefacts which were performed according to archaeological analysis procedures, generally based on the attributes attached to the artefacts, whereas the absolute dating of charcoal samples were performed in the Radiocarbon Dating Laboratory at Yogyakarta Nuclear Research Centre. Based on the relative dating of epigraphy content on the andesit rock from Gondosuli Temple which showed the year of 754 Saka or 832 AD, the Pringapus Temple was estimated to be built in the 850 AD. According to the absolute dating (Radiocarbon Dating with delta 13 C and tree ring corrections) the age for Gondosuli temple based on GDS/LU-2/Spit-7 samples is (384 -602) AD and from GDS/LU-2/Spit-8 = (452 - 652) AD. With these significant differences in the results obtained, it can be concluded that culture environment where the sample were collected already existed before the temple was built. Further investigation is still required

  15. Radiocarbon dating of Sphagnum cellulose from Mohos peat bog, East Carpathians

    Science.gov (United States)

    Hubay, Katalin; Braun, Mihály; Harangi, Sándor; Palcsu, László; Túri, Marianna; Rinyu, László; Molnár, Mihály

    2015-04-01

    This work focuses on building a high-resolution age-depth model for quantitative paleoclimate study from the Mohos peat bog, East Carpathians. Peats are important archives for Quaternary science, because they preserve environmental changes. To study the chronology of peat profiles the key is in the precise coring and reliable dating. However, many studies dealing with coring and radiocarbon dating of peat deposits they often shown problems with the proper methods and material. With our novel coring technique we reached undisturbed and uncompressed peat cores from the Mohos bog. A 10 meter deep peat profile was drilled in 2012 using a modified technique of a piston corer. The core presents a continuous peat profile from the last 11.500 cal. yr BP. The chronology was based on AMS radiocarbon analyses of the separated Sphagnum samples from different depths of the profile. The peat samples were wet sieved (40-280 μm) to avoid contamination by rootlets. Dry Sphagnum samples for AMS dating were prepared using the classical acid-base-acid (ABA) method completed with an oxidative bleaching step to get clean cellulose. Sphagnum cellulose samples were converted to CO2 and later graphite and measured by EnvironMICADAS accelerator mass spectrometry (AMS) in Hertelendi Laboratory (Debrecen, Hungary). Fine peat accumulation rate changes (sections with lowest accumulation values) were observed along the profile. Based on the chronology in further studies we want to focus special intervals to investigate environmental changes in the Holocene. Key words: peat, radiocarbon, cellulose

  16. Radiocarbon data collection, filtering and analysis at the NRL TEAMS facility

    International Nuclear Information System (INIS)

    Tumey, S.J.; Grabowski, K.S.; Knies, D.L.; Mignerey, A.C.

    2004-01-01

    This report describes a novel approach to collection and analysis of radiocarbon data due to the unique design of the Naval Research Laboratory Trace Element Accelerator Mass Spectrometry system. In this approach, targets are loaded on the cathode wheel such that samples are clustered in groups of five between standards. Each target is measured until the external error asymptotically reaches a constant value and the internal error dominates, or until a predefined time limit is reached. These measurements are repeated until the desired level of counting statistics is attained. Cycle control software saves the measured beam currents and count rate, as well as all system parameters to disc at fixed intervals throughout each measurement. Data visualization software has aided in system diagnosis by exposing relationships between the measured isotope ratios and system parameters. A filtering algorithm is employed to the data set of each target measurement in an attempt to achieve a Gaussian distribution. Final results are generated by a radiocarbon calculator that allows a user to select which target measurements to treat as samples, standards and blanks, and calculates the desired values (i.e. conventional radiocarbon age, percent modern carbon, etc.) with full error propagation. Currently, a Microsoft Access [reg] relational database is being developed which will be integrated into the existing LabVIEW [reg] control, filtering and calculation programs in order to streamline the process from sample submission to report generation, as well as improve quality control

  17. From scrolls to Picasso: AMS radiocarbon dating applied to textiles, art works and artifacts

    Energy Technology Data Exchange (ETDEWEB)

    Jull, A.J.T.; Donahue, D.J.; Beck, J.W.; Burr, G.S.; O`Malley, J.; Hewitt, L.; Biddulph, D.; Hatheway, A.L.; Lange, T.E.; Toolin, J. [Arizona Univ., Tucson, AZ (United States). NSF Arizona Accelerator Mass Spectrometry Facility

    1997-12-31

    Full text: The use of accelerator mass spectrometry (AMS) for radiocarbon dating allows us to use very small samples of carbon, <1 mg. This has opened a vast array of applications of radiocarbon dating which were difficult to do before AMS, due to sample size limitations of decay counting. We have successfully applied AMS {sup 14}C to dating of many types of textiles, including silks and linens, art works, documents and artifacts fabricated from wood, parchment, ivory and bone. For many of these types of samples, the results are often important in questions of the authenticity of these works of art and artifacts. This has encompassed a wide range of art works ranging from the Dead Sea Scrolls, the Shroud of Turin and the Chinese silk trade to the works of Raphael, Rembrandt and Picasso. Most recently, we have also dated the Vinland Map, a controversial document which shows the eastern coast of North America apparently using information from Viking voyages. An important issue in such studies is also the radiocarbon calibration curve. For some periods, most notably 1700-1950 AD we know that several changes in the {sup 14}C composition of the atmosphere make it almost impossible to date a sample during this period more precisely than the entire range. However, before this period, we have successfully dated materials to high precision. We have also studied the use of the period l900-1950 AD for {sup 14}C measurements and will present some examples where the rapid decline in {Delta} {sup 14}C can be used to date art works. The period after 1950AD also allows us to identify works fabricated from recent materials using the `spike` in {sup 14}C due to atmospheric nuclear testing. This bomb {sup 14}C has also been successfully used to identify originals from copies of works purporting to be the originals. We will discuss some artifacts, art works and forgeries, where {sup 14}C can resolve problems of authenticity (authors).

  18. Radiocarbon dispersion around Canadian nuclear facilities

    International Nuclear Information System (INIS)

    Milton, G.M.; Kramer, S.J.; Brown, R.M.; Repta, C.J.W.; King, K.J.; Rao, R.R.

    1995-01-01

    Canadian deuterium uranium (CANDU) pressurized heavy-water reactors produce 14 C by neutron activation of trace quantities of nitrogen in annular gas and reactor components ( 14 N(n,p) 14 C), and from 17 O in the heavy water moderator by ( 17 O(n,α) 14 C). The radiocarbon produced in the moderator is removed on ion exchange resins incorporated in the water purification systems; however, a much smaller gaseous portion is vented from reactor stacks at activity levels considerably below 1% of permissible derived emission limits. Early measurements of the carbon speciation indicated that >90% of the 14 C emitted was in the form of CO 2 .We conducted surveys of the atmospheric dispersion of 14 CO 2 at the Chalk River Laboratories and at the Pickering Nuclear Generating Station. We analyzed air, vegetation, soils and tree rings to add to the historical record of 14 C emissions at these sites, and to gain an understanding of the relative importance of the various carbon pools that act as sources/sinks within the total 14 C budget. Better model parameters than those currently available for calculating the dose to the critical group can be obtained in this manner. Global dose estimates may require the development of techniques for estimating emissions occurring outside the growing season. (author)

  19. Radiocarbon: nature's tracer for carbonaceous pollutants

    International Nuclear Information System (INIS)

    Currie, L.A.; Klouda, G.A.; Gerlach, R.W.

    1982-01-01

    Recent developments in radiocarbon dating techniques have made it feasible to determine 14 C/ 12 C ratios in samples containing milligram or even microgram quantities of carbon. As a result, it has become practicable to apply these techniques to the study of trace gases and particles in the atmosphere, as a means of resolving anthropogenic from natural source components. Interpretation of 14 C data is straightforward: biospheric carbon (such as vegetation) is alive with a 14 C/ 12 C ratio of about 1.5 x 10 -12 , whereas fossil carbon is dead. Beyond this dichotomous classification it becomes very interesting to combine the isotopic data with concurrent chemical data, as well as spatial and temporal distributions, in order to infer the strengths of specific sources of carbonaceous pollutants. A brief review will be presented of our program on atmospheric gases and carbonaceous particles. For the latter, we have assayed individual chemical and size fractions, and samples collected in urban, rural, and remote locales. The biogenic carbon fraction - presumably from wood-burning - ranged from 10% to 100% for the urban samples analyzed

  20. Considerations on the modelling of environmental radiocarbon

    International Nuclear Information System (INIS)

    Scott, E.M.; McCartney, M.

    1991-01-01

    Modelling radionuclide transfer within the natural environment involves three general steps: model formulation, its fitting using appropriate experimental data and model validation. The last process typically involves a sensitivity analysis and is used to modify model formulation and to direct future experimental effort. A wide variety of models exists appropriate to a number of different applications. Recently, attention has been directed to the development of principles for establishing local, regional and global upper bounds to doses. Here important considerations in model choice are the spatial detail required within the model, the links between models of differing resolution and the availability of suitable experimental data. We illustrate the model-building stages and discuss the above considerations in transfer modelling using radiocarbon which is produced and released as part of the nuclear fuel cycle. Its long half life of 5730 years, its mobility in the environment and its incorporation into man via the food chain make it of some considerable radiological significance. We consider local modelling of 14 C transfer using a Gaussian plume model, while its global dispersal is modelled using a large globally-averaged compartmental model. The global analysis is used to make short term predictions of 14 C specific activities to 2050 and longer-term predictions over a period of 10,000 years. We discuss the validation of these models and attempt to quantify the sources and magnitudes of the uncertainties in the model predictions. (26 refs., 2 figs.)

  1. Calibration factor or calibration coefficient?

    International Nuclear Information System (INIS)

    Meghzifene, A.; Shortt, K.R.

    2002-01-01

    Full text: The IAEA/WHO network of SSDLs was set up in order to establish links between SSDL members and the international measurement system. At the end of 2001, there were 73 network members in 63 Member States. The SSDL network members provide calibration services to end-users at the national or regional level. The results of the calibrations are summarized in a document called calibration report or calibration certificate. The IAEA has been using the term calibration certificate and will continue using the same terminology. The most important information in a calibration certificate is a list of calibration factors and their related uncertainties that apply to the calibrated instrument for the well-defined irradiation and ambient conditions. The IAEA has recently decided to change the term calibration factor to calibration coefficient, to be fully in line with ISO [ISO 31-0], which recommends the use of the term coefficient when it links two quantities A and B (equation 1) that have different dimensions. The term factor should only be used for k when it is used to link the terms A and B that have the same dimensions A=k.B. However, in a typical calibration, an ion chamber is calibrated in terms of a physical quantity such as air kerma, dose to water, ambient dose equivalent, etc. If the chamber is calibrated together with its electrometer, then the calibration refers to the physical quantity to be measured per electrometer unit reading. In this case, the terms referred have different dimensions. The adoption by the Agency of the term coefficient to express the results of calibrations is consistent with the 'International vocabulary of basic and general terms in metrology' prepared jointly by the BIPM, IEC, ISO, OIML and other organizations. The BIPM has changed from factor to coefficient. The authors believe that this is more than just a matter of semantics and recommend that the SSDL network members adopt this change in terminology. (author)

  2. Radiocarbon dates for beeswax figures in the prehistoric rock art of northern Australia

    International Nuclear Information System (INIS)

    Nelson, D.E.; Chippindale, C.; Alderson, M.S.

    1995-01-01

    Accelerator mass spectrometry radiocarbon ages have been taken for a test suite of small samples of material removed from some of the ''beeswax'' art figures found in rock shelters in northern Australia. The results indicate that we can reliably date this unique form of rock art with no noticeable damage. We had not expected to find figures of any great antiquity, and so were surprised to find that the ages obtained spanned the time period from the recent past to about 4000 BP. (Author)

  3. Radiocarbon dates for Maioro, N15/5, South Auckland, 1965-66

    International Nuclear Information System (INIS)

    Green, R.C.

    1983-01-01

    The 1965-66 excavations at the South Auckland site of Maioro were described and interpreted by Aileen Fox and R.C. Green in the previous volume. Their report indicated that six radiocarbon samples had been submitted for age determination, and would be reported when available. The results are now to hand and provide a 13th century A.D. estimation as the age for the initial settlement occupation of the site, and a 15th century date as the time for its major use as a stockaded pa

  4. Single amino acid radiocarbon dating of Upper Paleolithic modern humans

    Science.gov (United States)

    Marom, Anat; McCullagh, James S. O.; Higham, Thomas F. G.; Sinitsyn, Andrey A.; Hedges, Robert E. M.

    2012-01-01

    Archaeological bones are usually dated by radiocarbon measurement of extracted collagen. However, low collagen content, contamination from the burial environment, or museum conservation work, such as addition of glues, preservatives, and fumigants to “protect” archaeological materials, have previously led to inaccurate dates. These inaccuracies in turn frustrate the development of archaeological chronologies and, in the Paleolithic, blur the dating of such key events as the dispersal of anatomically modern humans. Here we describe a method to date hydroxyproline found in collagen (∼10% of collagen carbon) as a bone-specific biomarker that removes impurities, thereby improving dating accuracy and confidence. This method is applied to two important sites in Russia and allows us to report the earliest direct ages for the presence of anatomically modern humans on the Russian Plain. These dates contribute considerably to our understanding of the emergence of the Mid-Upper Paleolithic and the complex suite of burial behaviors that begin to appear during this period. PMID:22517758

  5. Contamination and UV ageing of diffuser targets used in satellite inflight and ground reference test site calibrations

    Science.gov (United States)

    Vaskuri, Anna; Greenwell, Claire; Hessey, Isabel; Tompkins, Jordan; Woolliams, Emma

    2018-02-01

    Diffuser reflectance targets are key components in in-orbit calibrations and for verifying ground reference test sites. In this work, Spectralon, Diffusil, and Heraeus diffusers were exposed to exhaust gases and ultraviolet (UV) radiation in the ambient air conditions and their degradations were monitored by measuring changes in spectral reflectances. Spectralon is a state-of-the-art diffuser made of polytetrafluoroethylene, and Diffusil and Heraeus diffusers are made of fused silica with gas bubbles inside. Based on the contamination tests, Spectralon degrades faster than fused silica diffusers. For the samples exposed to contamination for 20 minutes, the 250 nm - 400 nm total diffuse spectral reflectance of Spectralon degraded 3-5 times more when exposed to petrol-like emission and 16-23 times more when exposed to diesel-like emission, compared with Diffusil. When the reflectance changes of Spectralon were compared with those of Heraeus, Spectralon degraded 3-4 times more when exposed to petrol-like emission for 20 minutes and 5-7 times more when exposed to diesel-like emission for 7.5 minutes. When the samples contaminated were exposed to UV radiation in the ambient air, their reflectance gradually restored back to the original level. In conclusion, fused silica diffusers are more resistant to hydrocarbon contaminants present in ground reference test sites, and thus more stable under UV radiation in the air.

  6. Age estimates for the buckwheat family Polygonaceae based on sequence data calibrated by fossils and with a focus on the amphi-Pacific Muehlenbeckia.

    Directory of Open Access Journals (Sweden)

    Tanja M Schuster

    Full Text Available The buckwheat family Polygonaceae is a diverse group of plants and is a good model for investigating biogeography, breeding systems, coevolution with symbionts such as ants and fungi, functional trait evolution, hybridization, invasiveness, morphological plasticity, pollen morphology and wood anatomy. The main goal of this study was to obtain age estimates for Polygonaceae by calibrating a Bayesian phylogenetic analysis, using a relaxed molecular clock with fossil data. Based on the age estimates, we also develop hypotheses about the historical biogeography of the Southern Hemisphere group Muehlenbeckia. We are interested in addressing whether vicariance or dispersal could account for the diversification of Muehlenbeckia, which has a "Gondwanan" distribution. Eighty-one species of Polygonaceae were analysed with MrBayes to infer species relationships. One nuclear (nrITS and three chloroplast markers (the trnL-trnF spacer region, matK and ndhF genes were used. The molecular data were also analysed with Beast to estimate divergence times. Seven calibration points including fossil pollen and a leaf fossil of Muehlenbeckia were used to infer node ages. Results of the Beast analyses indicate an age of 110.9 (exponential/lognormal priors/118.7 (uniform priors million years (Myr with an uncertainty interval of (90.7-125.0 Myr for the stem age of Polygonaceae. This age is older than previously thought (Maastrichtian, approximately 65.5-70.6 Myr. The estimated divergence time for Muehlenbeckia is 41.0/41.6 (39.6-47.8 Myr and its crown clade is 20.5/22.3 (14.2-33.5 Myr old. Because the breakup of Gondwana occurred from 95-30 Myr ago, diversification of Muehlenbeckia is best explained by oceanic long-distance and maybe stepping-stone dispersal rather than vicariance. This study is the first to give age estimates for clades of Polygonaceae and functions as a jumping-off point for future studies on the historical biogeography of the family.

  7. Rate of radiocarbon retention onto calcite by isotope exchange

    Energy Technology Data Exchange (ETDEWEB)

    Lempinen, Janne; Lehto, Jukka [Helsinki Univ. (Finland). Lab. of Radiochemistry

    2016-11-01

    Radiocarbon ({sup 14}C) is a top priority class radionuclide associated with the long-term safety of spent nuclear fuel disposal. Dissolved inorganic radiocarbon can be retained in bedrock via isotope exchange with calcite (CaCO{sub 3}) at solubility equilibrium with groundwater. In the present study, the rate of the isotope exchange process was investigated on synthetic calcite using batch experiments. Experiments were performed in solutions with a calcium concentration of 0.0002-0.1 M, including two synthetic reference groundwaters. The radiocarbon activity in the solutions decreased exponentially as a function of time, thus following first-order kinetics. The rate of isotope exchange was quantified from an exponential fit to the activity data over time. The rate of radiocarbon retention increased as a function of the calcium activity. The isotope exchange half-life was only 4.3 days at calcium ion activities over 0.01. This half-life is very much shorter than the half-life of {sup 14}C or the time scale of groundwater movements; consequently calcite can effectively retain radiocarbon from brackish and saline groundwaters.

  8. Rate of radiocarbon retention onto calcite by isotope exchange

    International Nuclear Information System (INIS)

    Lempinen, Janne; Lehto, Jukka

    2016-01-01

    Radiocarbon ( 14 C) is a top priority class radionuclide associated with the long-term safety of spent nuclear fuel disposal. Dissolved inorganic radiocarbon can be retained in bedrock via isotope exchange with calcite (CaCO 3 ) at solubility equilibrium with groundwater. In the present study, the rate of the isotope exchange process was investigated on synthetic calcite using batch experiments. Experiments were performed in solutions with a calcium concentration of 0.0002-0.1 M, including two synthetic reference groundwaters. The radiocarbon activity in the solutions decreased exponentially as a function of time, thus following first-order kinetics. The rate of isotope exchange was quantified from an exponential fit to the activity data over time. The rate of radiocarbon retention increased as a function of the calcium activity. The isotope exchange half-life was only 4.3 days at calcium ion activities over 0.01. This half-life is very much shorter than the half-life of 14 C or the time scale of groundwater movements; consequently calcite can effectively retain radiocarbon from brackish and saline groundwaters.

  9. Support for the Astronomically Calibrated 40Ar/39Ar Age of Fish Canyon Sanidine: Evidence from the Quaternary

    NARCIS (Netherlands)

    Rivera, T.; Storey, M.; Zeeden, C.; Kuiper, K.; Hilgen, F.

    2011-01-01

    Fish Canyon sanidine (FCs) is the neutron fluence monitor most widely used in Cenozoic argon geochronology. Recommend published ages for FCs have been determined through various intercalibration techniques, but have varied by up to 2% over the last three decades. The robust quality of the

  10. Inland Ertebølle Culture: the importance of aquatic resources and the freshwater reservoir effect in radiocarbon dates from pottery food crusts

    Directory of Open Access Journals (Sweden)

    Bente Philippsen

    2014-11-01

    Full Text Available The Ertebølle culture is a late Mesolithic hunter-gatherer-fisher culture in southern Scandinavia, northern Germany and Poland. Archaeological finds as well as scientific analyses of humans and their artefacts indicate the great importance of aquatic resources, both marine and freshwater, to Ertebølle subsistence. In northern Germany, modern freshwater fish samples can have very high apparent radiocarbon ages (up to 3000 years. If such dramatic 'freshwater reservoir effects' also existed during the late Mesolithic, they could lead to artificially old radiocarbon dates for the bones of Ertebølle humans and domestic dogs, and for carbonised food crusts on cooking pots. Conversely, if we can demonstrate radiocarbon age 'offsets' in such samples, we can often attribute them to the exploitation of freshwater food resources. This article discusses methods of identifying freshwater resources in prehistoric pottery, including radiocarbon reservoir effects. We consider the results of radiocarbon, stable isotope and elemental analyses of food crusts on prehistoric pottery from four sites in the Alster and Trave valleys: Kayhude, Schlamersdorf, Bebensee and Seedorf.

  11. Radiocarbon and thermoluminescence dating of quaternary sediments in Deception Bay, southeast Queensland: some problems encountered

    International Nuclear Information System (INIS)

    Cotter, M.M.

    1999-01-01

    Full text: Radiocarbon and Thermoluminescence dating of sediment facies were utilised to develop a chronometric framework for the quaternary coastal evolution of Deception Bay southeast Queensland (Cotter 1996). This chronometric framework was developed in the context of a broader geoarchaeological and palaeogeographical investigation of the indigenous cultural landscape of the area. The TL analysis confirmed the presence of previously undated Pleistocene sands within the study area. However in the course of dating one sedimentary sequence, conventional radiocarbon analysis of Notispisula sheldls produced an age of 5190± 90 years BP (Beta-85415) whilst an overlying sandy unit (shown by particle size analysis and SEM surface textural analysis to be aeolian transported) subject to TL-dating produced an age of 14,900 ± 3300 years BP (W1942). This poster highlights the considerations made in order to reconcile this obvious anomaly. In effect, previously obtained radiometric data within the study area (Flood 1981; Hall 1996), in conjunction with an examination of the adequacy of the sampled materials for radiocarbon and TL age determinations point to the TL determination being in error. Similar anomalies have been shown to occur elsewhere in southeast Queensland (Tejan-Kella et al. 1990) explanations for which have been related to selective rather than total bleaching of Holocene sands (Prescott personal communication). Re-dating of the sand sequence using the selective bleach method is required to examine whether the dating anomaly shown for Deception Bay parallels selective bleaching effects determined for other sequences within southeast Queensland. Unfortunately this is beyond the scope and funds of this geoarchaeological study

  12. A reevaluation of the Pallett Creek earthquake chronology based on new AMS radiocarbon dates, San Andreas fault, California

    Science.gov (United States)

    Scharer, K.M.; Biasi, G.P.; Weldon, R.J.

    2011-01-01

    The Pallett Creek paleoseismic record occupies a keystone position in most attempts to develop rupture histories for the southern San Andreas fault. Previous estimates of earthquake ages at Pallett Creek were determined by decay counting radiocarbon methods. That method requires large samples which can lead to unaccounted sources of uncertainty in radiocarbon ages because of the heterogeneous composition of organic layers. In contrast, accelerator mass spectrometry (AMS) radiocarbon dates may be obtained from small samples that have known carbon sources and also allow for a more complete sampling of the section. We present 65 new AMS radiocarbon dates that span nine ground-rupturing earthquakes at Pallett Creek. Overall, the AMS dates are similar to and reveal no dramatic bias in the conventional dates. For many layers, however, individual charcoal samples were younger than the conventional dates, leading to earthquake ages that are overall slightly younger than previously reported. New earthquake ages are determined by Bayesian refinement of the layer ages based on stratigraphic ordering and sedimentological constraints. The new chronology is more regular than previously published records in large part due to new samples constraining the age of event R. The closed interval from event C to 1857 has a mean recurrence of 135years (?? = 83.2 years) and a quasiperiodic coefficient of variation (COV) of 0.61. We show that the new dates and resultant earthquake chronology have a stronger effect on COV than the specific membership of this long series and dating precision improvements from sedimentation rates. Copyright 2011 by the American Geophysical Union.

  13. Age spans of some Indian speleothems

    International Nuclear Information System (INIS)

    Yadava, M.G.; Ramesh, R.; Polyak, V.J.; Asmerom, Y.

    2009-01-01

    In recent years, research on speleothems (minerals growing in caves, i.e. stalactites, stalagmites and flowstones) have shown that these have potential to provide records of past climate and environmental changes. Speleothems have several advantages compared to other high-resolution land archives (e.g., tree rings and lake sediments). Firstly, these are unaffected by natural erosion processes yielding long records of climate variability. Secondly, precise chronology by U-Th mass spectrometry is possible now. Prior to the advent of mass spectrometry (late 1980s), radiocarbon decay method was applied to date young samples (<40 kyr) and U-Th-alpha-counting method was adopted for older samples. In comparison with radiocarbon dates uranium series dates are absolute ages and no calibration is required. In India, palaeoclimate research using speleothem is in infancy, some work has been reported from Himalaya, central India and Peninsular India, with oxygen isotopes being used as monsoon proxy. Five speleothems from four Indian caves have been dated by U- Th method to estimate their ages and growth durations. Results indicate that these grew during various time intervals in Holocene and late Pleistocene

  14. Radiocarbon dates from the Oxford AMS system: Archaeometry datelist 17

    International Nuclear Information System (INIS)

    Hedges, R.E.M.; Housley, R.A.; Ramsey, C.B.; Van Klinken, G.J.

    1993-01-01

    This seventeenth list of accelerator dates consists mainly of material dated since the beginning of 1991, but includes a number of measurements made earlier in the dating programme. In accordance with international radiocarbon convention all dates are expressed in radiocarbon years before AD 1950 (years BP) using the half-life of 5568 years, this convention having been reaffirmed at the Trondheim Radiocarbon Conference 1985. Errors are quoted as one standard deviation and are based on an assessment of all the contributions to the error in the laboratory isotope ratio measurement. Natural fractionation of carbon isotopes is accounted for by estimating δ 13 C values except for more recent dates where δ 13 C have been measured relative to PDB (only to within ± 0.5-1.0%). All combining procedures and significance tests are based on Ward and Wilson (1978). Comments composed by the Laboratory on the basis of information supplied by submitters are given without attribution. (author)

  15. Radiocarbon dating of groundwater in tertiary sediments of the eastern Murray Basin

    International Nuclear Information System (INIS)

    Drury, L.W.; Calf, G.E.

    1984-01-01

    The Tertiary sediments located in the eastern part of the Murray Basin contain one of the most important low salinity groundwater resources in New South Wales. It is imperative that the hydrogeological environment in which the groundwater occurs be thoroughly understood to allow adequate management of the resource. A radiocarbon dating project was carried out on 37 groundwater samples from bores screened in these unconsolidated sediments. The results indicate water ages in the range 'modern' to 15 800 years. Groundwater recharge areas are indicated and rates of groundwater recharge and movement determined. The latter shows close correlation with velocity values quantitatively determined by Darcy's law

  16. Radiocarbon dating of the silk fabrics laced with colored threads 'Ezo Nishiki' by AMS

    International Nuclear Information System (INIS)

    Oda, Hirotaka; Nakamura, Kazuyuki; Amano, Hikaru; Yoshida, Miyo; Takimoto, Hisafumi

    2010-01-01

    Ezo Nishiki are silk fabrics in which elegant designs of dragon or peony were laced with color threads. They were made originally in China and imported into Japan by way of the Amur Basin and Sakhalin. Although the foreign commerce flourished actively during Quing dynasty (1616-1912), a few ancient records suggests that the origin ascends to Yuan (1271-1368) or early Ming dynasty (1368-1644). We measured radiocarbon ages of 34 Ezo Nishiki samples. Although most of them showed the period of Quing dynasty, a sample indicated that the origin of the trade can be traced back to the middle 14th or the early 15th century. (author)

  17. Radiocarbon dating of groundwater in Tertiary sediments of the eastern Murray Basin

    Energy Technology Data Exchange (ETDEWEB)

    Drury, L.W. (Water Resources Commission of New South Wales, Sydney (Australia)); Calf, G.E. (Australian Atomic Energy Commission Research Establishment, Lucas Heights. Isotope Div.); Dharmasiri, J.K. (Colombo Univ. (Sri Lanka))

    1984-01-01

    The Tertiary sediments located in the eastern part of the Murray Basin contain one of the most important low salinity groundwater resources in New South Wales. It is imperative that the hydrogeological environment in which the groundwater occurs be thoroughly understood to allow adequate management of the resource. A radiocarbon dating project was carried out on 37 groundwater samples from bores screened in these unconsolidated sediments. The results indicate water ages in the range 'modern' to 15 800 years. Groundwater recharge areas are indicated and rates of groundwater recharge and movement determined. The latter shows close correlation with velocity values quantitatively determined by Darcy's law.

  18. Precision and reproducibility in AMS radiocarbon measurements.

    Energy Technology Data Exchange (ETDEWEB)

    Hotchkis, M A; Fink, D; Hua, Q; Jacobsen, G E; Lawson, E M; Smith, A M; Tuniz, C [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia)

    1997-12-31

    Accelerator Mass Spectrometry (AMS) is a technique by which rare radioisotopes such as {sup 14}C can be measured at environmental levels with high efficiency. Instead of detecting radioactivity, which is very weak for long-lived environmental radioisotopes, atoms are counted directly. The sample is placed in an ion source, from which a negative ion beam of the atoms of interest is extracted, mass analysed, and injected into a tandem accelerator. After stripping to positive charge states in the accelerator HV terminal, the ions are further accelerated, analysed with magnetic and electrostatic devices and counted in a detector. An isotopic ratio is derived from the number of radioisotope atoms counted in a given time and the beam current of a stable isotope of the same element, measured after the accelerator. For radiocarbon, {sup 14}C/{sup 13}C ratios are usually measured, and the ratio of an unknown sample is compared to that of a standard. The achievable precision for such ratio measurements is limited primarily by {sup 14}C counting statistics and also by a variety of factors related to accelerator and ion source stability. At the ANTARES AMS facility at Lucas Heights Research Laboratories we are currently able to measure {sup 14}C with 0.5% precision. In the two years since becoming operational, more than 1000 {sup 14}C samples have been measured. Recent improvements in precision for {sup 14}C have been achieved with the commissioning of a 59 sample ion source. The measurement system, from sample changing to data acquisition, is under common computer control. These developments have allowed a new regime of automated multi-sample processing which has impacted both on the system throughput and the measurement precision. We have developed data evaluation methods at ANTARES which cross-check the self-consistency of the statistical analysis of our data. Rigorous data evaluation is invaluable in assessing the true reproducibility of the measurement system and aids in

  19. Precision and reproducibility in AMS radiocarbon measurements.

    Energy Technology Data Exchange (ETDEWEB)

    Hotchkis, M.A.; Fink, D.; Hua, Q.; Jacobsen, G.E.; Lawson, E. M.; Smith, A.M.; Tuniz, C. [Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW (Australia)

    1996-12-31

    Accelerator Mass Spectrometry (AMS) is a technique by which rare radioisotopes such as {sup 14}C can be measured at environmental levels with high efficiency. Instead of detecting radioactivity, which is very weak for long-lived environmental radioisotopes, atoms are counted directly. The sample is placed in an ion source, from which a negative ion beam of the atoms of interest is extracted, mass analysed, and injected into a tandem accelerator. After stripping to positive charge states in the accelerator HV terminal, the ions are further accelerated, analysed with magnetic and electrostatic devices and counted in a detector. An isotopic ratio is derived from the number of radioisotope atoms counted in a given time and the beam current of a stable isotope of the same element, measured after the accelerator. For radiocarbon, {sup 14}C/{sup 13}C ratios are usually measured, and the ratio of an unknown sample is compared to that of a standard. The achievable precision for such ratio measurements is limited primarily by {sup 14}C counting statistics and also by a variety of factors related to accelerator and ion source stability. At the ANTARES AMS facility at Lucas Heights Research Laboratories we are currently able to measure {sup 14}C with 0.5% precision. In the two years since becoming operational, more than 1000 {sup 14}C samples have been measured. Recent improvements in precision for {sup 14}C have been achieved with the commissioning of a 59 sample ion source. The measurement system, from sample changing to data acquisition, is under common computer control. These developments have allowed a new regime of automated multi-sample processing which has impacted both on the system throughput and the measurement precision. We have developed data evaluation methods at ANTARES which cross-check the self-consistency of the statistical analysis of our data. Rigorous data evaluation is invaluable in assessing the true reproducibility of the measurement system and aids in

  20. Investigating the Impact of Past and Future CO2 Emissions on the Distribution of Radiocarbon in the Ocean

    Science.gov (United States)

    Khatiwala, S.; Payne, S.; Graven, H. D.; Heimbach, P.

    2015-12-01

    The ocean is a significant sink for carbon dioxide from fossil fuel burning, absorbing roughly a third of human CO2 emitted over the industrial period. This has implications not only for climate but also for the chemical and isotopic composition of the ocean. Human activities have increased the ocean radiocarbon content through nuclear bomb tests in the 1950s-60s, which released a large amount of radiocarbon (14C) into the atmosphere, but fossil fuel emissions are decreasing the radiocarbon content through the release of 14C-depleted CO2. Here, we use the ECCO-v4 ocean state estimate to examine the changing nature of the air-sea flux of radiocarbon and its spatial distribution in the ocean in response to past and future CO2 emissions, the latter taken from the the Representative Concentration Pathway (RCP) database used in IPCC simulations. In line with previous studies we find that the large air-sea gradient of 14C induced by nuclear bomb testing led to rapid accumulation of radiocarbon in the surface ocean. Surface fluxes of 14C have considerably weakened over the past several decades and in some areas 14C is being returned to the atmosphere. As fossil fuel emissions continue to reduce the atmospheric 14C/C ratio (Δ14C), in most RCP scenarios the total ocean 14C inventory starts decreasing by 2030. With strong emissions, the Δ14C of surface waters is driven to increasingly negative values and in RCP 8.5 by 2100 much of the surface ocean has apparent radiocarbon ages in excess of 2000 years, with subtropical gyres more depleted in 14C than the Southern Ocean. Surface waters become significantly more negative in Δ14C than underlying waters. As a result, turning conventional tracer oceanography on its head, recently ventilated waters are characterized by more negative Δ14C values. Similar patterns can be expected for CFCs in the ocean as atmospheric concentrations decrease over the next several decades. Our results have a number of implications, notably for

  1. Microgram level radiocarbon (14C) determination on carbonaceous particles in ice

    DEFF Research Database (Denmark)

    Jenk, Theo Manuel; Szidat, S.; Schwikowski, M.

    2007-01-01

    Accelerator mass spectrometry; Organic carbon; Elemental carbon; Radiocarbon dating; Ice cores; Paleo-record Udgivelsesdato: June......Accelerator mass spectrometry; Organic carbon; Elemental carbon; Radiocarbon dating; Ice cores; Paleo-record Udgivelsesdato: June...

  2. Urvina Bay, Galapagos Coral Radiocarbon (delta 14C) Data for 1956 to 1982

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Urvina Bay coral radiocarbon (14C) timeseries. (90 deg W, 0.5 deg S) Coral radiocarbon (Delta-14C) on untreated, low-speed drilled samples. Precision is +/- 4 per...

  3. Radiocarbon-dates of snow petrel regurgitations can reveal exposure periods for nunataks in Antarctica

    CSIR Research Space (South Africa)

    Ryan, PG

    1992-11-01

    Full Text Available There are several problems associated with determining radiocarbon dates, particularly for organic material from Antarctica. However, this study attempts to find accurate measure of the length of time these radiocarbon dates have been established...

  4. Radiocarbon dates to access the origin of the ice man

    Energy Technology Data Exchange (ETDEWEB)

    Niklaus, R. [Institute of Particle Physics, ETH Zurich, Hongerberg (Switzerland)]|[Commonwealth Scientific and Industrial Research Organisation (CSIRO), North Ryde, NSW (Australia). Div. of Exploration Geoscience; Bonani, G. [Institute of Particle Physics, ETH Zurich, Hongerberg (Switzerland); Prinoth-Fornwagner, R. [Innsbruck Univ. (Austria)

    1996-12-31

    Different samples from the Late and Final Neolithic in Northern Italy were radiocarbon dated at the AMS Facility in Zurich, Switzerland in order to determine the origin of the Ice Man from the Hauslabjoch. The cultural classification was obtained on the basis of topological studies of the cooper axe and of the flint dagger as well as studies of artefact materials (the flint or the wood of a composite arrow), while the chronological classification of the Ice Man was obtained with the help of new and old radiocarbon dates. 9 refs., 1 tab., 2 figs.

  5. Radiocarbon dates to access the origin of the ice man

    Energy Technology Data Exchange (ETDEWEB)

    Niklaus, R [Institute of Particle Physics, ETH Zurich, Hongerberg (Switzerland); [Commonwealth Scientific and Industrial Research Organisation (CSIRO), North Ryde, NSW (Australia). Div. of Exploration Geoscience; Bonani, G [Institute of Particle Physics, ETH Zurich, Hongerberg (Switzerland); Prinoth-Fornwagner, R [Innsbruck Univ. (Austria)

    1997-12-31

    Different samples from the Late and Final Neolithic in Northern Italy were radiocarbon dated at the AMS Facility in Zurich, Switzerland in order to determine the origin of the Ice Man from the Hauslabjoch. The cultural classification was obtained on the basis of topological studies of the cooper axe and of the flint dagger as well as studies of artefact materials (the flint or the wood of a composite arrow), while the chronological classification of the Ice Man was obtained with the help of new and old radiocarbon dates. 9 refs., 1 tab., 2 figs.

  6. Standard reference materials analysis for MINT Radiocarbon Laboratory

    International Nuclear Information System (INIS)

    Noraishah Othman; Kamisah Alias; Nasasni Nasrul

    2004-01-01

    As a follow-up to the setting up of the MINT Radiocarbon Dating facility. an exercise on the IAEA standard reference materials was carried out. Radiocarbon laboratories frequently used these 8 natural samples to verify their systems. The materials were either pretreated or analysed directly to determine the activity of 14 C isotopes of the five samples expressed in % Modern (pMC) terms and to make recommendations on further use of these materials. We present the results of the five materials and discuss the analyses that were undertaken. (Author)

  7. Bomb radiocarbon in metabolically inert tissues from terrestrial and marine mammals

    International Nuclear Information System (INIS)

    Bada, J.L.; Vrolijk, C.D.; Brown, S.; Druffel, E.R.M.; Hedges, R.E.M.

    1987-01-01

    We report here radiocarbon measurements of monkey eye lens nucleus proteins and a narwhal tusk, biological tissues which have sampled the bomb radiocarbon signal in different ways. The results confirm the metabolic inertness of eye lens nucleus proteins and demonstrate the feasibility of measuring radiocarbon in small samples of biological tissue using accelerator mass spectrometry (AMS). The narwhal tusk provides a unique record of the radiocarbon activity in Arctic Ocean waters over most of the 20th century

  8. Calibration of C-14 dates: some remaining uncertainties and limitations

    International Nuclear Information System (INIS)

    Burleigh, R.

    1975-01-01

    A brief review is presented of the interpretation of radiocarbon dates in terms of calendar years. An outline is given of the factors that make such correlations necessary and of the work that has so far been done to make them possible. The calibration of the C-14 timescale very largely depends at present on the bristlecone pine chronology, but it is clear that many detailed uncertainties still remain. These are discussed. (U.K.)

  9. Reservoir effects in a Stone Age fjord on Lolland, Denmark

    DEFF Research Database (Denmark)

    Philippsen, Bente

    2018-01-01

    to be known for accurate radiocarbon dating of samples with possible aquatic carbon sources, such as human bones or food residues on pottery. Therefore, this paper attempts at calculating the local reservoir effect for the study area. I will discuss the possibilities and limitations when analysing radiocarbon...... for building chronologies and for reconstructing the environment of the Stone Age fjord. Finally, I will discuss the pitfalls and uncertainties associated with radiocarbon dates for sea level reconstruction....

  10. Accurate dating with radiocarbon from the atom bomb tests

    CSIR Research Space (South Africa)

    Vogel

    2002-09-01

    Full Text Available The artificial radiocarbon produced by the thermonuclear bomb tests in the 1950s and 1960s significantly increased the level of C-14 in the environment. A detailed record of the subsequent changes in the C-14 concentration of the atmosphere can...

  11. Radiocarbon dating of Mesolithic pottery from Northern Germany

    DEFF Research Database (Denmark)

    Philippsen, Bente

    2013-01-01

    The earliest pottery in Schleswig-Holstein, Northern Germany, was produced by the Final Mesolithic Ertebølle culture. Radiocarbon dating of food crusts on Ertebølle pottery indicated that ceramics from inland sites were substantially older than those from the coast. Therefore, a freshwater...

  12. Short-term variations of radiocarbon during the last century

    International Nuclear Information System (INIS)

    Burchuladze, A.A.; Pagava, S.V.; Jurina, V.; Povinec, P.; Usacev, S.

    1982-01-01

    Radiocarbon variations related to the 11-year solar cycle during the last century are discussed. Previous investigations on short term 14 C variations in tree rings are compared with 14 C measurements in Georgian wine samples. The amplitude of 14 C variations as obtained by various authors ranges from 0.2 to about 1%. (author)

  13. Radiocarbon dating in archaeology: Interdisciplinary aspects and consequences (an overview)

    Science.gov (United States)

    Palincaş, Nona

    2017-06-01

    This paper is an overview of recent developments in the radiocarbon dating of the most frequently analyzed archaeological materials - wood, short-lived plants, and human and animal bones - and draws attention to two sets of consequences. Firstly, while radiocarbon dating has become more accessible to archaeologists thanks to an increase in the number of laboratories, a lowering of prices, and a reduction in sample sizes, it has also grown far more dependent on fields of research, other than the traditional chemical pretreatment of samples and the physics involved in their measurement, such as wood anatomy and other fields of botany, stable isotope-based diet studies, geochemistry, micromorphology, statistics, etc., most of which are not easily accessible by the vast majority of users of radiocarbon dating (and sometimes not familiar to practicing archaeologists). Secondly, given that, on the one hand, there is still much scope for research in radiocarbon dating and, on the other, archaeological sites are a limited resource, there is need to create archives containing the detailed documentation of samples and, whenever possible, sample residues.

  14. Radiocarbon application in environmental science and archaeology in Croatia

    Energy Technology Data Exchange (ETDEWEB)

    Krajcar Bronic, I., E-mail: krajcar@irb.h [Radiocarbon Laboratory, Department of Experimental Physics, Ruder Boskovic Institute, Bijenicka 54, 10000 Zagreb (Croatia); Obelic, B.; Horvatincic, N.; Baresic, J.; Sironic, A. [Radiocarbon Laboratory, Department of Experimental Physics, Ruder Boskovic Institute, Bijenicka 54, 10000 Zagreb (Croatia); Minichreiter, K. [Institute of Archaeology, Ulica grada Vukovara 68, 10000 Zagreb (Croatia)

    2010-07-21

    Radiocarbon is a cosmogenic radioisotope equally distributed throughout the troposphere and biosphere. This fact enables its most common application-radiocarbon dating. Natural equilibrium of radiocarbon has been disturbed by diverse anthropogenic activities during the last {approx}150 years, enabling also the use of {sup 14}C in various environmental applications. Here we present three types of studies by using {sup 14}C that were performed in the Zagreb Radiocarbon Laboratory. {sup 14}C in atmospheric CO{sub 2} has been monitored at several sites with various anthropogenic influences and the difference between the clean-air sites, the industrial city and the vicinity of a nuclear power plant has been established. {sup 14}C has been applied in geochronology of karst areas, especially in dating of tufa, speleothems and lake sediments, as well as in studies of geochemical carbon cycle. {sup 14}C has been used in various archaeological studies, among which the dating of the early Neolithic settlements in Croatia is presented. In these studies {sup 14}C was measured by radiometric techniques, i.e., by gas proportional counting and more recently by liquid scintillation counting (LSC). Two sample preparation techniques for LSC measurement were used: benzene synthesis for archaeological dating and other applications that require better precision, and direct absorption of CO{sub 2} for monitoring purposes. The presented results show that various studies by using {sup 14}C can be successfully performed by the LSC technique, providing a large enough sample (>1 g of carbon).

  15. Radiocarbon adjustments to the dendrochronology of a yellowwood tree

    CSIR Research Space (South Africa)

    Vogel, JC

    2001-03-01

    Full Text Available High-precision radiocarbon dating of a millennium-old yellowwood tree from the Midlands of Natal shows that the tree-rings do, in general, record annual growth, but that both missing and false rings occur. At two places along the transect...

  16. Laboratory Intercomparison of Pleistocene Bone Radiocarbon Dating Protocols

    NARCIS (Netherlands)

    Huels, Matthias; van der Plicht, Johannes; Brock, Fiona; Matzerath, Simon; Chivall, David

    2017-01-01

    Since its invention in the late 1940s, radiocarbon (14C) dating has become an important tool for absolute dating. A prerequisite for the acceptance of this method is consistency between, and compatibility of, 14C dates from different laboratories. To meet these requirements, international laboratory

  17. A chronology of the PY608E–PC sediment core (Lake Pumoyum Co, southern Tibetan Plateau) based on radiocarbon dating of total organic carbon

    International Nuclear Information System (INIS)

    Watanabe, Takahiro; Nakamura, Toshio; Matsunaka, Tetsuya; Nara, Fumiko Watanabe; Zhu Liping; Wang Junbo; Kakegawa, Takeshi; Nishimura, Mitsugu

    2013-01-01

    Paleoclimatic records from the Tibetan Plateau provide important clues for understanding the Asian monsoon and Asian climate systems. To reconstruct climatic and environmental changes in the southern Tibetan Plateau, a 3.77-m-long sediment core (PY608E–PC) was taken from the southeastern part of Lake Pumoyum Co in August 2006. Because terrestrial plant residues are extremely rare in this core, we performed radiocarbon dating on the total organic carbon fraction. We also estimated the old carbon effect and radiocarbon reservoir age of the total organic carbon fraction. Using these estimates, we propose a new radiocarbon chronology for past climatic changes from ca. 12,500 to 700 cal BP. The linear sedimentation rate of the core was founded to be constant at 32.0 cm/kyr, indicating stable sedimentation conditions in Lake Pumoyum Co from the period of the Younger Dryas to the Holocene.

  18. A chronology of the PY608E-PC sediment core (Lake Pumoyum Co, southern Tibetan Plateau) based on radiocarbon dating of total organic carbon

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Takahiro, E-mail: twatanabe@geo.kankyo.tohoku.ac.jp [Graduate School of Environmental Studies, Tohoku University, 6-6-20 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8579 (Japan); Graduate School of Science, Tohoku University, 6-3 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8578 (Japan); Nakamura, Toshio [Center for Chronological Research, Nagoya University, Furo-cho, Chikusa, Nagoya 464-8601 (Japan); Matsunaka, Tetsuya [School of Marine Science and Technology, Tokai University, 3-20-1 Orido, Shimizu, Shizuoka 424-0902 (Japan); Nara, Fumiko Watanabe [Graduate School of Science, Tohoku University, 6-3 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8578 (Japan); Zhu Liping; Wang Junbo [Institute of Tibetan Plateau Research, Chinese Academy of Science, No. 18 Shuangqing Road, Haidian District, Beijing 100085 (China); Kakegawa, Takeshi [Graduate School of Science, Tohoku University, 6-3 Aramaki Aza Aoba, Aoba-ku, Sendai 980-8578 (Japan); Nishimura, Mitsugu [School of Marine Science and Technology, Tokai University, 3-20-1 Orido, Shimizu, Shizuoka 424-0902 (Japan)

    2013-01-15

    Paleoclimatic records from the Tibetan Plateau provide important clues for understanding the Asian monsoon and Asian climate systems. To reconstruct climatic and environmental changes in the southern Tibetan Plateau, a 3.77-m-long sediment core (PY608E-PC) was taken from the southeastern part of Lake Pumoyum Co in August 2006. Because terrestrial plant residues are extremely rare in this core, we performed radiocarbon dating on the total organic carbon fraction. We also estimated the old carbon effect and radiocarbon reservoir age of the total organic carbon fraction. Using these estimates, we propose a new radiocarbon chronology for past climatic changes from ca. 12,500 to 700 cal BP. The linear sedimentation rate of the core was founded to be constant at 32.0 cm/kyr, indicating stable sedimentation conditions in Lake Pumoyum Co from the period of the Younger Dryas to the Holocene.

  19. Fire and Fish: Using Radiocarbon And Stratigraphy To Discern The Impact Of Wildfire On Fish Metapopulations

    Science.gov (United States)

    Schaffrath, K. R.; Finch, C.; Belmont, P.; Budy, P.

    2015-12-01

    sampled 10-15 individual wildfires and radiocarbon ages range from 150-8,100 years.

  20. Environmental changes in the western Amazonia: morphological framework, geochemistry, palynology and radiocarbon dating data

    International Nuclear Information System (INIS)

    Horbe, Adriana M.C.; Behling, Hermann; Nogueira, Afonso C.R.; Mapes, Russell

    2011-01-01

    The sediments from the Coari lake, a 'terra firme' lake sculpted into Plio-Pleistocene deposits, and the Acara lake, a flooding-type lake developed on Quaternary sediments in the flood plain of the mid-Solimoes river, in the western Amazonia, Brazil, were studied to investigate the environmental condition of their developing. This study includes mineral composition, geochemistry, Pb isotope, palinology, radiocarbon-age and morphological framework of the lakes obtained from SRTM satellite images. The geological and the environmental conditions in the two lakes are highly variable and suggest that their evolution reflect autogenic processes under humid rain forest condition. Although kaolinite, quartz, muscovite, illite, and smectite are the main minerals in both lakes, the geochemistry indicates distinct source, the Acara lake sediments have higher concentrations of Al 2 O 3 , Fe 2 O 3 , Fe O, Ca O, K 2 O, Mg O, Na 2 O, P 2 O 5 , Ba, V, Cu, Ni, Zn, Pb, Sr, Li, Y and La and have more radiogenic Pb than the Coari lake sediments. The radiocarbon ages suggest that at 10160 yr BP the Coari lake started to be developed due to avulsion of the Solimoes river, and the Acara lake was formed by the meander abandonment of Solimoes river retaining its grass dominated shore at ca. 3710 yr BP. (author)

  1. Secular variation of cosmic ray intensity recorded in the radiocarbon concentration of tree rings

    International Nuclear Information System (INIS)

    Kigoshi, K.

    1978-01-01

    Study of the secular variations of cosmic ray intensity on the basis of the secular variations of atmospheric radiocarbon concentration in 8000 years is considered. The data on the radiocarbon concentration is received by three laboratories using the dendrochronologically dated tree ring samples. In order to use the data the variations due to geochemical process must be eliminated. From this point of view the climatic effect on the atmospheric radiocarbon concenttration is estimated using the data on sunspot number and global surface temperature during 1650-1800 y. The barge influence of climate on the atmospheric radiocarbon concentration syggests the small contribution of change of radiocarbon production rate to the short-period fluctuations in the atmospheric radiocarbon concentration. Elimination of variations caused by climate and sunspot activities from the variations in atmospheric radiocarbon concentration gives a long-term scale of its concentration which agrees well to the observed paleo-geomagnetic data

  2. Radiocarbon of Respired CO2 Following Fire in Alaskan Boreal Forest: Can Disturbance Release Old Soil Carbon to the Atmosphere?

    Science.gov (United States)

    Schuur, E. A.; Randerson, J. A.; Fessenden, J.; Trumbore, S. E.

    2002-12-01

    Fire in the boreal forest releases carbon stored in vegetation and soil to the atmosphere. Following fire, microbial decomposition is stimulated by inputs of plant detritus and changes in soil microclimate, which can result in large losses of carbon. Furthermore, warmer summer soil temperatures and deeper thaw depths in burned ecosystems may make carbon that was previously climatically protected by low soil temperatures susceptible to decomposition. We used radiocarbon measurements to estimate the age of carbon released by soil respiration following fire in two black spruce (Picea mariana) forests in interior Alaska that burned during the summer of 1999. To isolate soil respiration, we established manipulated plots where vegetation was prevented from recolonizing, and paired control plots in nearby unburned forest. Soil respiration radiocarbon signatures in the burned manipulation ranged from +112\\permil to +192\\permil and differed significantly from the unburned controls that ranged from +100\\permil to +130\\permil. Burned plots appear to respire older carbon than unburned forest, which could either be due to the stimulation of decomposition of intermediate age soil organic matter pools, to the lack of plant respiration that reflects the atmospheric radiocarbon signature of +92\\permil, or both. At least during the initial phase following fire, these data suggest that carbon fluxes from soil are dominated by soil organic matter pools with decadal scale turnover times.

  3. Increase of radiocarbon concentration in tree rings from Kujawy (SE Poland) around AD 774-775

    Science.gov (United States)

    Rakowski, Andrzej Z.; Krąpiec, Marek; Huels, Mathias; Pawlyta, Jacek; Dreves, Alexander; Meadows, John

    2015-10-01

    Evidence of a rapid increase in atmospheric radiocarbon (14C) content in AD 774-775 was presented by Miyake et al. (2012), who observed an increase of about 12‰ in the 14C content in annual tree rings from Japanese cedar. Usoskin et al. (2013) report a similar 14C spike in German oak, and attribute it to exceptional solar activity. If this phenomenon is global in character, such rapid changes in 14C concentration may affect the accuracy of calibrated dates, as the existing calibration curve is composed mainly of decadal samples. Single-year samples of dendro-chronologically dated tree rings of deciduous oak (Quercus robur) from Kujawy, a village near Krakow (SE Poland), spanning the years AD 765-796, were collected and their 14C content was measured using the AMS system in the Leibniz Laboratory. The results clearly show a rapid increase of 9.2 ± 2.1‰ in the 14C concentration in tree rings between AD 774 and AD 775, with maximum Δ14C = 4.1 ± 2.3‰ noted in AD 776.

  4. Increase of radiocarbon concentration in tree rings from Kujawy (SE Poland) around AD 774–775

    International Nuclear Information System (INIS)

    Rakowski, Andrzej Z.; Krąpiec, Marek; Huels, Mathias; Pawlyta, Jacek; Dreves, Alexander; Meadows, John

    2015-01-01

    Evidence of a rapid increase in atmospheric radiocarbon ( 14 C) content in AD 774–775 was presented by Miyake et al. (2012), who observed an increase of about 12‰ in the 14 C content in annual tree rings from Japanese cedar. Usoskin et al. (2013) report a similar 14 C spike in German oak, and attribute it to exceptional solar activity. If this phenomenon is global in character, such rapid changes in 14 C concentration may affect the accuracy of calibrated dates, as the existing calibration curve is composed mainly of decadal samples. Single-year samples of dendro-chronologically dated tree rings of deciduous oak (Quercus robur) from Kujawy, a village near Krakow (SE Poland), spanning the years AD 765–796, were collected and their 14 C content was measured using the AMS system in the Leibniz Laboratory. The results clearly show a rapid increase of 9.2 ± 2.1‰ in the 14 C concentration in tree rings between AD 774 and AD 775, with maximum Δ 14 C = 4.1 ± 2.3‰ noted in AD 776.

  5. Increase of radiocarbon concentration in tree rings from Kujawy (SE Poland) around AD 774–775

    Energy Technology Data Exchange (ETDEWEB)

    Rakowski, Andrzej Z., E-mail: arakowski@polsl.pl [Leibniz-Laboratory for Radiometric Dating and Isotope Research, University Kiel, Max-Eyth-Str. 11-13, 24118 Kiel (Germany); Institute of Physics – Center for Science and Education, Silesian University of Technology, Konarskiego Str. 22B, 44-100 Gliwice (Poland); Krąpiec, Marek [AGH University of Science and Technology, Mickiewicza Av. 30, 30-059 Krakow (Poland); Huels, Mathias [Leibniz-Laboratory for Radiometric Dating and Isotope Research, University Kiel, Max-Eyth-Str. 11-13, 24118 Kiel (Germany); Pawlyta, Jacek [Institute of Physics – Center for Science and Education, Silesian University of Technology, Konarskiego Str. 22B, 44-100 Gliwice (Poland); Dreves, Alexander [Leibniz-Laboratory for Radiometric Dating and Isotope Research, University Kiel, Max-Eyth-Str. 11-13, 24118 Kiel (Germany); Meadows, John [Leibniz-Laboratory for Radiometric Dating and Isotope Research, University Kiel, Max-Eyth-Str. 11-13, 24118 Kiel (Germany); Centre for Baltic and Scandinavian Archaeology, Schleswig-Holstein State Museums Foundation, Schloss Gottorf, Schloßinsel, 24837 Schleswig (Germany)

    2015-10-15

    Evidence of a rapid increase in atmospheric radiocarbon ({sup 14}C) content in AD 774–775 was presented by Miyake et al. (2012), who observed an increase of about 12‰ in the {sup 14}C content in annual tree rings from Japanese cedar. Usoskin et al. (2013) report a similar {sup 14}C spike in German oak, and attribute it to exceptional solar activity. If this phenomenon is global in character, such rapid changes in {sup 14}C concentration may affect the accuracy of calibrated dates, as the existing calibration curve is composed mainly of decadal samples. Single-year samples of dendro-chronologically dated tree rings of deciduous oak (Quercus robur) from Kujawy, a village near Krakow (SE Poland), spanning the years AD 765–796, were collected and their {sup 14}C content was measured using the AMS system in the Leibniz Laboratory. The results clearly show a rapid increase of 9.2 ± 2.1‰ in the {sup 14}C concentration in tree rings between AD 774 and AD 775, with maximum Δ{sup 14}C = 4.1 ± 2.3‰ noted in AD 776.

  6. From scrolls to Picasso: AMS radiocarbon dating applied to textiles, art works and artifacts

    International Nuclear Information System (INIS)

    Jull, A.J.T.; Donahue, D.J.; Beck, J.W.; Burr, G.S.; O'Malley, J.; Hewitt, L.; Biddulph, D.; Hatheway, A.L.; Lange, T.E.; Toolin, J.

    1997-01-01

    Full text: The use of accelerator mass spectrometry (AMS) for radiocarbon dating allows us to use very small samples of carbon, 14 C to dating of many types of textiles, including silks and linens, art works, documents and artifacts fabricated from wood, parchment, ivory and bone. For many of these types of samples, the results are often important in questions of the authenticity of these works of art and artifacts. This has encompassed a wide range of art works ranging from the Dead Sea Scrolls, the Shroud of Turin and the Chinese silk trade to the works of Raphael, Rembrandt and Picasso. Most recently, we have also dated the Vinland Map, a controversial document which shows the eastern coast of North America apparently using information from Viking voyages. An important issue in such studies is also the radiocarbon calibration curve. For some periods, most notably 1700-1950 AD we know that several changes in the 14 C composition of the atmosphere make it almost impossible to date a sample during this period more precisely than the entire range. However, before this period, we have successfully dated materials to high precision. We have also studied the use of the period l900-1950 AD for 14 C measurements and will present some examples where the rapid decline in Δ 14 C can be used to date art works. The period after 1950AD also allows us to identify works fabricated from recent materials using the 'spike' in 14 C due to atmospheric nuclear testing. This bomb 14 C has also been successfully used to identify originals from copies of works purporting to be the originals. We will discuss some artifacts, art works and forgeries, where 14 C can resolve problems of authenticity (authors)

  7. Compound specific radiocarbon content of lignin oxidation products from the Altamaha river and Coastal Georgia

    Energy Technology Data Exchange (ETDEWEB)

    Culp, Randy, E-mail: rculp@uga.edu [Center for Applied Isotope Studies, University of Georgia, Athens, Georgia (United States)

    2013-01-15

    Compound-specific isotope analysis (CSIA) is a powerful tool in organic geochemistry by providing detailed information about an individual organic compound's history with regard to its source and process of formation. Most CSIA involves measurement of the stable isotope ratio of carbon ({sup 13}C/{sup 12}C) and hydrogen (D/H) following separation by gas or liquid chromatography. New applications are being developed using compound-specific radiocarbon ({sup 14}C) content for delineating age of materials, rates of decomposition and residence time in various environments. This paper details the isotopic work on specific lignin monomers derived from terrestrial plants transported and deposited within the Altamaha River, estuary and off-shore Georgia in the Atlantic Ocean. By using gas chromatographic separation and identification of selected lignin oxidation products (LOP), the harvesting of these compounds using preparative fraction collection, and measurement of their {sup 14}C content using accelerator mass spectrometry, details of the age and presence of specific biomarkers unique to a given terrestrial source are revealed. Radiocarbon ages determined from water-column particulate organic carbon and sediment LOPs indicate a range of ages from modern to well over 5,000 years for the former and latter respectively. Transport mechanisms and particle size associations on mineral grains may play a significant role in {sup 14}C distribution in estuary and near-shore coastal environments. This data indicates higher than modern {sup 14}C activities in large particle-size sediment fractions in contrast to older LOP {sup 14}C ages found associated with the same coarse grain sediments. Individual LOP ages substantiate older terrestrial materials persist in the off-shore environment even though in the presence of modern marine {sup 14}C sources.

  8. Compound specific radiocarbon content of lignin oxidation products from the Altamaha river and Coastal Georgia

    International Nuclear Information System (INIS)

    Culp, Randy

    2013-01-01

    Compound-specific isotope analysis (CSIA) is a powerful tool in organic geochemistry by providing detailed information about an individual organic compound’s history with regard to its source and process of formation. Most CSIA involves measurement of the stable isotope ratio of carbon ( 13 C/ 12 C) and hydrogen (D/H) following separation by gas or liquid chromatography. New applications are being developed using compound-specific radiocarbon ( 14 C) content for delineating age of materials, rates of decomposition and residence time in various environments. This paper details the isotopic work on specific lignin monomers derived from terrestrial plants transported and deposited within the Altamaha River, estuary and off-shore Georgia in the Atlantic Ocean. By using gas chromatographic separation and identification of selected lignin oxidation products (LOP), the harvesting of these compounds using preparative fraction collection, and measurement of their 14 C content using accelerator mass spectrometry, details of the age and presence of specific biomarkers unique to a given terrestrial source are revealed. Radiocarbon ages determined from water-column particulate organic carbon and sediment LOPs indicate a range of ages from modern to well over 5,000 years for the former and latter respectively. Transport mechanisms and particle size associations on mineral grains may play a significant role in 14 C distribution in estuary and near-shore coastal environments. This data indicates higher than modern 14 C activities in large particle-size sediment fractions in contrast to older LOP 14 C ages found associated with the same coarse grain sediments. Individual LOP ages substantiate older terrestrial materials persist in the off-shore environment even though in the presence of modern marine 14 C sources.

  9. Establishing the date of Maori environmental impact in New Zealand through pollen analysis and radiocarbon dating

    Energy Technology Data Exchange (ETDEWEB)

    McGlone, M.S.; Wilmshurst, J.M. [Landcare Research, Lincoln, (New Zealand)

    1997-12-31

    Full text: Over the last decade there has been an intense debate about whether New Zealand prehistory is long ( > 1500 years) or short ( < 800 years). Pollen and charcoal analyses have played a key role in this debate by helping to pinpoint the transition from relatively undisturbed environments to those deforested by anthropogenic fires. Problems with in situ contamination, reworking of sediments, confusion of natural with anthropogenic impacts, and different theoretical expectations of growth, spread and impact of early Maori populations have led to disparate conclusions. We review pollen based studies carried out on a variety of fossil sites, including peat bogs, swamps, estuaries and lakes, and contribute new results. Different sedimentary environments show varying susceptibilities to contamination and have resulted in a wide spread of ages for initial Maori impact. Datable materials least susceptible to contamination by old or young carbon are pure peat and macrofossils, whereas lake, swamp and silty sediments are most susceptible. Analysis of the radiocarbon ages obtained for the start of Maori deforestation show that ages falling in the `long` prehistory period are exclusively derived from lake sediments and swamps. In contrast, the bulk of the ages falling in the `short` prehistory period are from pure peat and selected plant fragments. We conclude from our analysis of radiocarbon ages for pollen based deforestation that the first evidence of Maori environmental impact began about 700-550 calendar years BP (1250-1400 AD). Finer age resolution is limited by dating techniques, site limitations and the uncertainty associated with identifying the first signs of human impact. The period we have identified corresponds with the oldest dated archaeological sites and supports the short prehistory hypothesis. We discuss how to distinguish reliable fossil sites from those that have a high risk of giving misleading results.

  10. Establishing the date of Maori environmental impact in New Zealand through pollen analysis and radiocarbon dating

    International Nuclear Information System (INIS)

    McGlone, M.S.; Wilmshurst, J.M.

    1997-01-01

    Full text: Over the last decade there has been an intense debate about whether New Zealand prehistory is long ( > 1500 years) or short ( < 800 years). Pollen and charcoal analyses have played a key role in this debate by helping to pinpoint the transition from relatively undisturbed environments to those deforested by anthropogenic fires. Problems with in situ contamination, reworking of sediments, confusion of natural with anthropogenic impacts, and different theoretical expectations of growth, spread and impact of early Maori populations have led to disparate conclusions. We review pollen based studies carried out on a variety of fossil sites, including peat bogs, swamps, estuaries and lakes, and contribute new results. Different sedimentary environments show varying susceptibilities to contamination and have resulted in a wide spread of ages for initial Maori impact. Datable materials least susceptible to contamination by old or young carbon are pure peat and macrofossils, whereas lake, swamp and silty sediments are most susceptible. Analysis of the radiocarbon ages obtained for the start of Maori deforestation show that ages falling in the 'long' prehistory period are exclusively derived from lake sediments and swamps. In contrast, the bulk of the ages falling in the 'short' prehistory period are from pure peat and selected plant fragments. We conclude from our analysis of radiocarbon ages for pollen based deforestation that the first evidence of Maori environmental impact began about 700-550 calendar years BP (1250-1400 AD). Finer age resolution is limited by dating techniques, site limitations and the uncertainty associated with identifying the first signs of human impact. The period we have identified corresponds with the oldest dated archaeological sites and supports the short prehistory hypothesis. We discuss how to distinguish reliable fossil sites from those that have a high risk of giving misleading results

  11. Instrumentation calibration

    International Nuclear Information System (INIS)

    Mack, D.A.

    1976-08-01

    Procedures for the calibration of different types of laboratory equipment are described. Provisions for maintaining the integrity of reference and working standards traceable back to a national standard are discussed. Methods of validation and certification methods are included. An appendix lists available publications and services of national standardizing agencies

  12. New 40Ar/39Ar age of the Bishop Tuff from multiple sites and sediment rate calibration for the Matuyama-Brunhes boundary

    Science.gov (United States)

    Sarna-Wojcicki, A. M.; Pringle, M.S.; Wijbrans, J.

    2000-01-01

    Precise dating of sanidine from proximal ash flow Bishop Tuff and air fall Bishop pumice and ash, California, can be used to derive an absolute age of the Matuyama Reversed-Brunhes Normal (M-B) paleomagnetic transition, identified stratigraphically close beneath the Bishop Tuff and ash at many sites in the western United States. An average age of 758.9 ?? 1.8 ka, standard error of the mean (SEM), was obtained for individual sanidine crystals or groups of several crystals, determined from ???70 individual analyses of sanidine separates from 11 sample groups obtained at five localities. The basal air fall pumice (757.7 ?? 1.8 ka) and overlying ash flow tuff (762.2 ?? 4.7 ka) from near the source yield essentially the same dates within errors of analysis, suggesting that the two units were emplaced close in time. A date on distal Bishop air fall ash bed at Friant, California, ???100 km to the west of the source area, is younger, 750.1 ?? 4.3 ka, but not significantly different within analytical error (??1 standard deviation). Previous dates of the Bishop Tuff, obtained by others using conventional K-Ar and the fission track method on zircons, ranged from ???650 ka to ???1.0 Ma. The most recent, generally accepted date by the K-Ar method on sanidine was 738 ?? 3 ka. We infer, as others before, that many K-Ar dates on sanidine feldspar are too young owing to incomplete degassing of radiogenic Ar during fusion in the K-Ar technique and that many older K-Ar dates are too old owing to detrital or xenocrystic contamination in the larger samples that are necessary for the technique. The new dates are similar to recent 40Ar/39Ar ages of the Bishop Tuff determined on individual samples by others but are derived from a larger proximal sample population and from multiple analysis of each sample. The results provide a definitive and precise age calibration of this widespread chronostratigraphic marker in the western United States and northeastern Pacific Ocean. We calculated the

  13. Development of a sample preparation system for AMS radiocarbon dating at CRICH, Korea

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Myung-Jin; Lee, Byeong-Cheol; Lim, Eun-Soo [Cultural Research Institute of Chungcheong Heritage, Gongju (Korea, Republic of); Hong, Duk-Geun [Kangwon National University, Chuncheon (Korea, Republic of); Park, Soon-Bal [Chungnam National University, Daejeon (Korea, Republic of); Youn, Min-Young [Seoul National University, Seoul (Korea, Republic of)

    2010-01-15

    We developed a sample preparation system for radiocarbon dating by using AMS measurement at Cultural Research Institute of Chungcheong Heritage, Korea. From the investigation of the reduction process, the optimum graphitization temperature was chosen as 625 .deg. C. Using Aldrich graphite powder of 0.75 {+-} 0.023 pMC, the background value of our preparation system was controlled at a low level. The robustness against chemical treatment and contamination was also observed from samples of Oxalic acid II and IAEA-C4. The resultant values, 134.04 {+-} 0.99 pMC and 0.38 {+-} 0.043 pMC, were in good agreement with the consensus values. Based on comparison, our conventional ages agreed very well with those of Beta Analytic Co. and SNU-AMS. No memory effect existed in the preparation system. Therefore, we concluded that the sample preparation system was operated in a stable manner and that the basic radiocarbon dating procedures were completely verified.

  14. Radiocarbon analysis of halophilic microbial lipids from an Australian salt lake

    Science.gov (United States)

    Bray, P. Sargent; Jones, Claudia M.; Fallon, Stewart J.; Brocks, Jochen J.; George, Simon C.

    2012-01-01

    Assigning accurate dates to hypersaline sediments opens important terrestrial records of local and regional paleoecologies and paleoclimatology. However, as of yet no conventional method of dating hypersaline systems has been widely adopted. Biomarker, mineralogical, and radiocarbon analyses of sediments and organic extracts from a shallow (13 cm) core from a hypersaline playa, Lake Tyrrell, southeastern Australia, produce a coherent age-depth curve beginning with modern microbial mats and extending to ~ 7500 cal yr BP. These analyses are furthermore used to identify and constrain the timing of the most recent change in hydrological regime at Lake Tyrrell, a shift from a clay deposit to the precipitation of evaporitic sands occurring at some time between ~ 4500 and 7000 yr. These analyses show the potential for widespread dating of hypersaline systems integrating the biomarker approach, reinforce the value of the radiocarbon content of biomarkers in understanding the flow of carbon in modern ecologies, and validate the temporal dimension of data provided by biomarkers when dating late Quaternary sediments.

  15. Re-Development of Radiocarbon Dating Laboratory in Malaysian Nuclear Agency

    International Nuclear Information System (INIS)

    Norfaizal Mohamed; Nita Salina Abu Bakar; Phillip, E.

    2015-01-01

    Nuclear Dating Laboratory, formerly known as Radiocarbon Laboratory was established in Malaysian Nuclear Agency (Nuclear Malaysia) since 1983. A benzene synthesis line for radiocarbon (carbon-14) dating was installed in this laboratory by Australian Atomic Energy Commission (AAEC) under the Hydrology Isotope Project, a collaboration project between IAEA, AAEC and PUSPATI (former name for Nuclear Malaysia). Determining the age of samples could be performed using this facility throughout two main processes, namely the production of benzene containing C-14 isotopes and activity determination of C-14 using Liquid Scintillation Counter. Realizing the need and importance of Nuclear Dating Laboratory for the nations science and technology development, the Top Management of Nuclear Malaysia was agreed to hand over this laboratory and its facilities to Waste Technology and Environmental Division (BAS) started in June 2013 for the redevelopment. Hence, this paper will highlight the weaknesses and problems that need to be addressed and improved to enable it to be used in providing a good service. (author)

  16. TL and radiocarbon dating of neolithic sepultures from Sudan: intercomparison of results

    International Nuclear Information System (INIS)

    Guibert, P.; Ney, C.; Bechtel, F.; Schvoerer, M.; Geus, F.

    1994-01-01

    Thermoluminescence dating of a set of 29 pottery sherds excavated at the neolithic sites of El Kadada and El Ghaba (near Shendi, Central Sudan) was carried out at Bordeaux University. The archaeological dose was measured using the fine grain technique. The annual dose was determined by analytical techniques (neutron activation analysis, ICP spectrometry, XRF, low background gamma spectrometry) and by ''on-site'' measurements of the environmental radioactivity (gammametry). The crystalline inclusions of the samples were characterized by optical microscopy and cathodoluminescence: the TL minerals mainly consist of quartz and K-feldspar crystals. In some cases, radioactive inclusions of zircons and monazites are observed. The TL and the radiocarbon dates show a good agreement, verifying the validity of the radiocarbon ages which were suspected to be too old because of the nature of the dated material (shells). Taking into account all the chronological data, it is shown that El Ghaba and El Ghaba necropolis were used respectively within the 4800-3300 B.C. and 4200-3000 B.C. date-ranges for neolithic cultures, the occupation of El Kadada starting five or six centuries later than El Ghaba. (Author)

  17. Preliminary results on the implantation of a laboratory for the measurement of natural radiocarbon

    International Nuclear Information System (INIS)

    Pessenda, C.L.R.; Pessenda, R.; Nascimento Filho, V.F. do; Victoria, R.L.; Matsui, E.

    1990-01-01

    Though the project 'Amazonia I', activity 'Paleoclimatology', sub-project 'hydrologic cycle', the Centro de Energia Nuclear da Agricultura (CENA) from Universidade de Sao Paulo has received recently, from Atomic Energy International Agency a research apparatus for the tranformation of carbon from benzene samples and a liquid scintillator spectrometer of low background, for the detection of natural radiocarbon. In the production of 3ml of benzene, synthetized from oxalic acid P.A. and calcium carbonate P.A., it was obtained a performance of more than 80%; preliminary results were also obtained for shell and coal samples. For the detection of radiocarbon, after optimization of the spectral region, and selection of samples, it was seen that the efficiency of the spectrometer was of the order of 55%, with a base counting rate of 1,3 cmp. The age limit, under the actual operation conditions was 41.600 years 95% (2σ) and 36.700 years for 99% (3σ) considering a time counting of 1000 minutes for the sample and the bacground radiation. (A.C.A.S.) [pt

  18. Radiocarbon dates on desiccated moa (Dinornithiformes) flesh from inland Otago, New Zealand

    International Nuclear Information System (INIS)

    Anderson, A.; Rowe, L.; Petchey, F.; White, M.

    2010-01-01

    Remains of soft tissues from extinct moa (Dinornithiformes), mainly desiccated sinew, muscle, skin, and feathers have been recovered rather seldom but their distribution is distinctive. Of 22 records of such finds accumulated between 1864 and 1987, 15 came from inland Otago, west of Dunedin in the southern South Island. Most were found in the late nineteenth century in rockshelters, clefts or alluvial sediments and were regarded at the time as ev dence of the survival of moa up to about AD 1800. Improbable as this latter point is, it has not been tested by radiocarbon dating until now. Our particular impetus to do so, however, arises in another way. It is from research, again largely within inland Otago, on Maori artefacts which have also been made from various other kinds of soft tissues (flax, grasses, dog skin, bird skin, feathers etc.). A series of accelerator mass spectrometry (AMS) radiocarbon dates on these shows that they are exclusively late, post-AD 1650, which begs the question of why the age range does not extend across the full prehistoric period, beginning about AD 1300. (author). 6 refs., 2 figs., 1 tab.

  19. AMS radiocarbon dating of very large Grandidier’s baobabs (Adansonia grandidieri)

    Energy Technology Data Exchange (ETDEWEB)

    Patrut, Adrian [Babeş-Bolyai University, Faculty of Chemistry, Cluj-Napoca (Romania); Reden, Karl F. von [NOSAMS Facility, Dept. of Geology & Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA (United States); Danthu, Pascal [Cirad, UPR BSEF, Montpellier (France); DP Forêt et Biodiversité, Antananarivo (Madagascar); Leong Pock-Tsy, Jean-Michel [DP Forêt et Biodiversité, Antananarivo (Madagascar); Rakosy, Laszlo; Patrut, Roxana T. [Babeş-Bolyai University, Faculty of Biology and Geology, Cluj-Napoca (Romania); Lowy, Daniel A. [Nova University, Alexandria Campus, Alexandria, VA (United States); Margineanu, Dragos [Babeş-Bolyai University, Faculty of Chemistry, Cluj-Napoca (Romania)

    2015-10-15

    The article reports the AMS radiocarbon investigation of the two largest known Adansonia grandidieri specimens. The two baobabs, which are named Tsitakakoike and Pregnant baobab, are located in Southwestern Madagascar, near Andombiro. A third specimen from this area, the House baobab, was also investigated. According to measurements, Tsitakakoike is the biggest individual above ground level of all Adansonia species. The House baobab was selected for its exposed structure, which is identical to the closed ring-shaped structure with false cavities identified by us in large and old Adansonia digitata specimens. According to our research, Tsitakakoike and the Pregnant baobab have multi-stemmed cylindrical trunks which are mainly hollow; the two very large baobabs also possess a ring-shaped structure. The radiocarbon dates of the oldest wood samples collected from the large trunks were 1274 ± 20 BP for Tsitakakoike and 930 ± 20 BP for the Pregnant baobab. According to their original positions and to the architectures of the two A. grandidieri, the ages of Tsitakakoike and Pregnant baobab would be between 1300 and 1500 years. Therefore, A. grandidieri becomes the third Adansonia species with individuals that can live over 1000 years, according to accurate dating results.

  20. Identification and synchronization of the common cosmic-ray signal in the IntCal13 14C calibration and the Greenland ice-core 10Be records

    Science.gov (United States)

    Muscheler, Raimund; Adolphi, Florian; Bronk Ramsey, Christopher; Rasmussen, Sune; Hughen, Konrad; Cooper, Alan; Turney, Chris

    2017-04-01

    core and radiocarbon timescales over the Holocene - Bayesian wiggle-matching of cosmogenic radionuclide records: Clim. Past. , v. 12, p. 15-30. Muscheler, R., Adolphi, F., and Svensson, A., 2014, Challenges in 14C dating towards the limit of the method inferred from anchoring a floating tree ring radiocarbon chronology to ice core records around the Laschamp geomagnetic field minimum: Earth Planet. Sci. Lett., v. 394, p. 209-215. Reimer, P., Bard, E., Bayliss, A., Beck, J. W., Blackwell, P. G., Bronk Ramsey, C., Buck, C. E., Cheng, H., Edwards, R. L., Friedrich, M., Grootes, P., Guilderson, T. P., Haflidison, H., Hajdas, I., Hatté, C., Heaton, T. J., Hoffmann, D. L., Hogg, A. G., Hughen, K. A., Kaiser, K. F., Kromer, B., Manning, S. W., Niu, M., Reimer, R. W., Richards, D. A., Scott, E. M., Southon, J., Staff, R. A., Turney, C. S. M., and van der Plicht, J., 2013, IntCal13 AND Marine13 radiocarbon age calibration curves 0-50,000 years cal BP: Radiocarbon, v. 55, No. 4, p. 1869-1887.

  1. The PSI/ETH small radiocarbon dating system

    International Nuclear Information System (INIS)

    Synal, H.-A.; Jacob, S.; Suter, M.

    2000-01-01

    A small and compact radiocarbon dating system has been built at PSI/ETH. The system is based on a National Electrostatics Corporation (NEC) pelletron accelerator with a maximum terminal voltage of 550 kV. It is the first accelerator mass spectrometry (AMS) system that uses 1 + ions at the high-energy end of the accelerator. Interfering isobaric molecules are destroyed by collisions in the gas stripper inside the accelerator. The system has been designed to fulfill two primary goals. First, it can be used as an experimental platform to study the relevant charge exchange and molecular break up processes at low energies. Second, it is able to perform high quality radiocarbon dating measurements. A detailed system description is given and results of performance tests are discussed

  2. Techniques of biomolecular quantification through AMS detection of radiocarbon

    International Nuclear Information System (INIS)

    Vogel, S.J.; Turteltaub, K.W.; Frantz, C.; Felton, J.S.; Gledhill, B.L.

    1992-01-01

    Accelerator mass spectrometry offers a large gain over scintillation counting in sensitivity for detecting radiocarbon in biomolecular tracing. Application of this sensitivity requires new considerations of procedures to extract or isolate the carbon fraction to be quantified, to inventory all carbon in the sample, to prepare graphite from the sample for use in the spectrometer, and to derive a meaningful quantification from the measured isotope ratio. These procedures need to be accomplished without contaminating the sample with radiocarbon, which may be ubiquitous in laboratories and on equipment previously used for higher dose, scintillation experiments. Disposable equipment, materials and surfaces are used to control these contaminations. Quantification of attomole amounts of labeled substances are possible through these techniques

  3. Lichens as indicators of tritium and radiocarbon contamination

    International Nuclear Information System (INIS)

    Daillant, Olivier; Kirchner, Gerald; Pigree, Gilbert; Porstendorfer, Justin

    2004-01-01

    Lichens were collected in France in the surroundings of a military nuclear facility in Burgundy, near the la Hague reprocessing plant and in an area away from any direct source of contamination. Organically bound tritium (OBT) has been analysed on 18 samples and radiocarbon on 11. It appeared that on the most contaminated spots, the OBT activity in lichens was higher than the background by a factor of 1000 and was still a factor 10-100 at a distance of 20 km from the source. Radiocarbon from la Hague could be traced by lichens. The slow metabolism of lichens makes them suitable for the follow-up of 3 H and 14 C, which have been incorporated by photosynthesis

  4. Radiocarbon concentration in modern tree rings from Valladolid, Spain

    International Nuclear Information System (INIS)

    Rakowski, Andrzej Z.; Nakamura, Toshio; Pazdur, Anna; Charro, Elena; Villanueva, Jose Luis Gutierrez; Piotrowska, Natalia

    2010-01-01

    New results of radiocarbon concentration in tree rings from the City of Valladolid (Spain) covering a growth period of 22 year have been measured using an AMS. Samples were taken using a hollow drill from a living tree, and α-cellulose was extracted from each of annual rings (early and late wood separately). The set of data shows lower radiocarbon concentration than that reported for 'clean air' at the reference station, indicating a remarkable input of 'dead' CO 2 of fossil fuel origin. Using data of carbon dioxide and 14 C concentrations from Schauinsland, the corresponding summer and winter values of the fossil component (c f ) in carbon dioxide were calculated for the City of Valladolid. By fitting exponential and linear functions to the experimental data, the exchange time was calculated, and the expected future 14 C concentration in the atmosphere was estimated.

  5. Willard Libby, Radiocarbon, and Carbon Dating

    Science.gov (United States)

    age determination in archaeology, geology, geophysics, and other branches of science". 1 Edited of California, Los Angeles,2 where he founded the UCLA Environmental Science and Engineering (ESE Libby, Chemistry: Berkeley and Los Angeles 3 Edited excerpt from Environmental Science and Engineering

  6. AMS radiocarbon dating of cemetery of Jin Marquises in China

    CERN Document Server

    Wu, X; Wang, J; Guo, Z; Liu, K; Lü, X; Ma, H; Li, K; Yuan, J; Cai, L

    2000-01-01

    Bones are very important samples to determine the hosts of the cemetery of Jin Marquises which were excavated at Tianma-Qucun site in Shanxi Province in China. In order to obtain accurate AMS radiocarbon dates, bones were pretreated by two kinds of methods, the gelatin-extraction method and the amino-acid method. Charcoals collected from the same sites were also used. The measured dates agree with historical record.

  7. Radiocarbon dating of sediment cores from Hachinohe, the Kamikita Plain

    International Nuclear Information System (INIS)

    Hitoki, Eri; Nakamura, Toshio; Matsumoto, Yui; Tsuji, Sei-ichiro; Fujine, Hisashi

    2013-01-01

    We investigated stratigraphy and chronology by analyses of Holocene sediments and radiocarbon dating of sediment cores from the Kamikita Plain. On the Kamikita Plain, which faces the Pacific coast of Northeast Japan, marine and fluvial terraces covered with tephras derived from Towada and Hakkoda volcanoes are well developed. We clarified that Towada Chuseri tephra and fluvial deposits consisted of volcanic sediments influenced an alluvial depositional system in the Kamikita Plain after a maximum of the Jomon Transgression. (author)

  8. Radiocarbon dating of archaeological geological and groundwater samples

    International Nuclear Information System (INIS)

    Chinh, N.K.; Dung, H.H.; Quan, H.M.; Thuy, T.K.

    1989-01-01

    In the context of the project VIE/8/003 sponsored by the IAEA, a regular and complete C 1 4 laboratory was installed at the Centre of the Nuclear Techniques in 1986. In this paper the authors present the procedure of sample treatment and saple activity measurement of the radiocarbon method and some preliminary results obtained after more than one year of operation of the laboratory

  9. Radiocarbon dating at sub MeV energies

    International Nuclear Information System (INIS)

    Synal, H.A.; Jacob, S.; Suter, M.

    1999-01-01

    Accelerator Mass Spectrometry (AMS) is currently the leading technique for the detection of long-lived radionuclides, such as 10 Be, 14 C, 26 Al, 36 Cl, 41 Ca, 53 Mn, 59 Ni, 60 Fe and 129 I at natural isotopic concentrations. However, radiocarbon plays the primary role and 14 C AMS systems, which are able to provide high precision measurements, are nowadays commercially available

  10. New radiocarbon dates for Milu (Elaphurus davidianus) sub-fossils from southeast China

    Energy Technology Data Exchange (ETDEWEB)

    Ding, X.F. [State Key Laboratory of Nuclear Physics and Technology and Institute of Heavy Ion Physics, School of Physics, Peking University, Beijing 100871 (China); Shen, C.D., E-mail: cdshen@gig.ac.cn [State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, 510640 Guangzhou (China); Ding, P.; Yi, W.X. [State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, 510640 Guangzhou (China); Fu, D.P.; Liu, K.X. [State Key Laboratory of Nuclear Physics and Technology and Institute of Heavy Ion Physics, School of Physics, Peking University, Beijing 100871 (China)

    2013-01-15

    Milu (Elaphurus davidianus, Pere David's deer) is one of the few species of large mammals that became extinct in the wild, but survived domestically. A good understanding of expansion and habitat is required if the reintroduction of Milu into the wild is to be implemented. Among the widely reported findings of Milu sub-fossils, only a small fraction have been dated. Here we report new AMS radiocarbon dates on Milu sub-fossil samples unearthed from two sites at Qingdun, Jiangsu and Fujiashan, Zhejiang in southeast China. These AMS {sup 14}C ages of Milu sub-fossils provide new evidence for the presence of Milu expansion in the lower reaches of the Yangtze River during the Holocene Optimum interval from 5000 yr BC to 3000 yr BC. These new ages also have important implications for the reconstruction of the paleoclimate and paleogeography during the Neolithic Period in southeast China.

  11. Late Holocene Radiocarbon Variability in Northwest Atlantic Slope Waters

    Energy Technology Data Exchange (ETDEWEB)

    Sherwood, O; Edinger, E; Guilderson, T P; Ghaleb, B; Risk, M J; Scott, D B

    2008-08-15

    Deep-sea gorgonian corals secrete a 2-part skeleton of calcite, derived from dissolved inorganic carbon at depth, and gorgonin, derived from recently fixed and exported particulate organic matter. Radiocarbon contents of the calcite and gorgonin provide direct measures of seawater radiocarbon at depth and in the overlying surface waters, respectively. Using specimens collected from Northwest Atlantic slope waters, we generated radiocarbon records for surface and upper intermediate water layers spanning the pre- and post bomb-{sup 14}C eras. In Labrador Slope Water (LSW), convective mixing homogenizes the pre-bomb {Delta}{sup 14}C signature (-67 {+-} 4{per_thousand}) to at least 1000 m depth. Surface water bomb-{sup 14}C signals were lagged and damped (peaking at {approx} +45{per_thousand} in the early 1980s) relative to other regions of the northwest Atlantic, and intermediate water signals were damped further. Off southwest Nova Scotia, the vertical gradient in {Delta}{sup 14}C is much stronger. In surface water, pre-bomb {Delta}{sup 14}C averaged -75 {+-} 5{per_thousand}. At 250-475 m depth, prebomb {Delta}{sup 14}C oscillated quasi-decadally between -80 and -100{per_thousand}, likely reflecting interannual variability in the presence of Labrador Slope Water vs. Warm Slope Water (WSW). Finally, subfossil corals reveal no systematic changes in vertical {Delta}{sup 14}C gradients over the last 1200 years.

  12. Metabolic kinetics and biological effects of radiocarbon (14C)

    International Nuclear Information System (INIS)

    Vasilenko, I.Ya.; Osipov, V.A.; Lyaginskaya, A.M.; Bugryshev, P.F.; Istomina, A.G.; Turova, V.I.; Dement'ev, S.I.; Zhorova, E.S.; Mart'yanov, B.M.; Shal'nova, G.A.; Kuz'mina, T.D.; Shebenko, V.A.; Pomerantseva, M.D.; Ramajya, L.K.

    1988-01-01

    Radiocarbon 14 C is one of the most widespread radionuclides. Increased concentration of anthropogenic 14 C in the biosphere is a problem of considerable hygienic and ecological significance. The paper presents the results of comprehensive studies for years on biokinetics of the main 14 C compounds, inorganic (Na H 14 CO 3 , Na 2 14 CO 3 , K 2 14 CO 3 , Ca 14 CO 3 ) as well as organic ( 14 C-glucose, 14 C-succinic acid, 14 C-glucosamine, 14 C-glycine, 14 C-tryptophane, 14 C-valine, 14 C-palmitic acid, 14 C-stearic acid, 14 C-ethyl alcohol, 14 C-methyl alcohol, 14 C-urea), of 14 C as food constituent and of elementary radiocarbon. The 14 C toxicity is investigated for both acute and chronic small doses received by animals. The nuclide's genetic efficiency is assessed. Based on research evidence, the accumulation multiple and equilibrium time are estimated for long-term 14 C intake by humans. The data may be used for setting genetic standards and estimating an anthropogenic increase of 14 C concentration in the environment. The hazard of anthropogenic radiocarbon is assessed with allowance for further development of nuclear power industry. (author)

  13. Influence of marine sources on 14C ages : isotopic data from Watom Island, Papua New Guinea inhumations and pig teeth in light of new dietary standards

    International Nuclear Information System (INIS)

    Beavan Athfield, N.R.; Green, R.C.; Craig, J.; McFadgen, B.; Bickler, S.

    2008-01-01

    Gauging the effect of 14 C-depleted marine foods on radiocarbon ages requires an accurate assessment of the likely proportion of marine foods in the diet. Several factors must be considered, including region-specific δ 13 C, δ 15 N and δ 34 S data values (regional stable isotope values can differ from global averages), temporal variations in δ 13 C which offset values in modern dietary standards by up to 1.5 permille, and that modelling which considers only 13 C may overestimate the contribution of various dietary sources. Here, we compare previous calculations by linear interpolation of δ 13 C and a complex computer simulation of marine contribution to the diet of inhumations from the SAC archaeological site Watom Island, Papua New Guinea, with the ISOSOURCE mixing model and a revised database of regional dietary sources and their isotopic values, to estimate marine diet contributions and radiocarbon offsets for burials from the SAC site. Though different estimates of marine contribution to diet do not significantly alter previous calibrations of radiocarbon ages for the inhumations, the new ISOSOURCE calculations challenge the idea of excessive exploitation of marine resources and support evidence for arboriculture and horticulture being a major component in Lapita diet. (author). 87 refs., 3 figs., 8 tabs

  14. Feasibility Study: Applicability of geochronologic methods involving radiocarbon and other nuclides to the groundwater hydrology of the Rustler Formation, southeastern New Mexico

    International Nuclear Information System (INIS)

    Lambert, S.J.

    1987-12-01

    Radiocarbon, tritium, and 36 Cl were measured in groundwaters from the dolomite aquifers of the Rustler Formation in the northern Delaware Basin of southeastern New Mexico to determine the feasibility of using these nuclides in dating the groundwater at and near the Waste Isolation Pilot Plant, a facility for geological disposal of Radioactive waste. No measurable 36 Cl was found in any of these groundwaters, which derive their dissolved chloride from Permian evaporites. Demonstrably uncontaminated groundwaters contained no significant amounts of tritium ( 13 C does not linearly correlate with bicarbonate, indicating no single source of contaminant radiocarbon. Values of PMC and δ 13 C for groundwaters were used to calculate apparent radiocarbon ages according to an interpretive model that accounts for water/rock interactions in carbonate aquifers. All but six pairs of values give significant negative ages (-1,000 to -7,000 years). This suggests that in contaminated samples the model over-adjusts (based on δ 13 C) for radiocarbon loss due to dilution and isotopic exchange with the rock. 52 refs., 10 figs., 6 tabs

  15. Uses of radiocarbon dating in archaeology

    International Nuclear Information System (INIS)

    Purohit, Anila; Bishnoi, Indra; Charan, Sumitra

    2012-01-01

    Carbon dating is one of the mist effective tools in the archaeologist's kit. It has provided illumination where none was once thought possible. The historians of one hundred years ago could only dream of such a wonderful, albeit frightening atomic clock ticking away, helping to mark the passing of the years and the ages of man. It is a vital part in the investigation and preservation of our past and a lovely bit of analysis to compliment digital records of monuments. It places the plants, animals, and people of yore into an understandable and verifiable context

  16. Radiocarbon dating of the first Turkish bridge over the River Tisza

    International Nuclear Information System (INIS)

    Szanto, Zs.; Molnar, M.; Futo, I.; Svingor, E.; Rinyu, L.; Palcsu, L.; Morgos, A.

    2004-01-01

    Complete text of publication follows. Situated at the junction of the Tisza and Zagyva rivers, the territory of the presentday Szolnok town has been nearly continuously inhabited since the beginning of the Neolithic age. Gravures and other written documents attested the presence of bridge(s) over the River Tisza during the centuries. The first bridges were mentioned in 1526 as temporary pontoon bridges used for the needs of the Turkish army. The remainings of an old bridge on the River Tisza were discovered last summer in excavations of the river bank at Szolnok. It was supposed that the remainings found were probably part of the bridge built in 1562, the first wooden bridge over the River Tisza mentioned in the letter of bishop of town Eger [1] but could also been parts of a bridge built much later. Although the mineral water and sodium silicate have penetrated the wood logs resulting in though blackish-brown and hardened by petrifaction samples, the original character of the pylons was still evident. Six timbers (7 samples) have been radiocarbon dated. Samples were physically and chemically pre-treated to remove contamination before they were converted to CO 2 . In order to avoid the 'old wood' effect, in which the inner tree rings may be tenths of years older than the outer ring of sapwood deposited just before the tree died the exterior was removed. Physical treatments consisted of cleaning, sorting, grinding and sieving. Chemical treatment included the standard A/A/A method. The pre-treated samples were combusted to CO 2 in a controlled oxygen stream. The purified CO 2 was trapped and measured by gas proportional counting [2]. Correction for fractionation was done by measuring the δ 13 C PDB value. Calibration of 14 C dates to calendar years was performed using the Calib 4.4.2 program [3]. The results showed the wood sample prepared by A/A/A contained contaminants of more recent carbon material which gave it a more recent date and spread the results over four

  17. AFSC/REFM: Bomb-produced age validation study

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Fish age validation with bomb-produced radiocarbon (14C) requires a known-age Delta14C reference chronology spanning the era of a marine increase in bomb-produced...

  18. Radiocarbon dating, chronologic framework, and changes in accumulation rates of holocene estuarine sediments from Chesapeake Bay

    Science.gov (United States)

    Colman, Steven M.; Baucom, P.C.; Bratton, J.F.; Cronin, T. M.; McGeehin, J.P.; Willard, D.; Zimmerman, A.R.; Vogt, P.R.

    2002-01-01

    Rapidly accumulating Holocene sediments in estuaries commonly are difficult to sample and date. In Chesapeake Bay, we obtained sediment cores as much as 20 m in length and used numerous radiocarbon ages measured by accelarator mass spectrometry methods to provide the first detailed chronologies of Holocene sediment accumulation in the bay. Carbon in these sediments is a complex mixture of materials from a variety of sources. Analyses of different components of the sediments show that total organic carbon ages are largely unreliable, because much of the carbon (including coal) has been transported to the bay from upstream sources and is older than sediments in which it was deposited. Mollusk shells (clams, oysters) and foraminifera appear to give reliable results, although reworking and burrowing are potential problems. Analyses of museum specimens collected alive before atmospheric nuclear testing suggest that the standard reservoir correction for marine samples is appropriate for middle to lower Chesapeake Bay. The biogenic carbonate radiocarbon ages are compatible with 210 Pb and 137 Cs data and pollen stratigraphy from the same sites. Post-settlement changes in sediment transport and accumulation is an important environmental issue in many estuaries, including the Chesapeake. Our data show that large variations in sediment mass accumulation rates occur among sites. At shallow water sites, local factors seem to control changes in accumulation rates with time. Our two relatively deep-water sites in the axial channel of the bay have different long-term average accumulation rates, but the history of sediment accumulation at these sites appears to reflect overall conditions in the bay. Mass accumulation rates at the two deep-water sites rapidly increased by about fourfold coincident with widespread land clearance for agriculture in the Chesapeake watershed.

  19. Radiocarbon evidence for low frequency solar oscillations

    International Nuclear Information System (INIS)

    Damon, P.E.; Jirikowic, I.

    1992-01-01

    From the spectrum of Δ 14 C variations attributed to solar activity modulation of cosmogenic isotope production, a long-period variation (the Hallstattzeit) of 2120±20 years was deduced with 93% statistical confidence. Although most Hallstattzeit harmonic overtones may be shape-related, two also behave as fundamentals: that of 212 years (Suess) and of 88 years (Gleissberg). These exceptional harmonic overtones modulate the 11-year Schwabe solar cycle determined from indices of sunspots. The Hallstattzeit period may be associated with dramatic secular changes in solar behavior. Sun-like stars exhibit quiet and active states consistent with such long-period secular variations. The climate impact of solar output changes may partially explain periods of rapid climate change such as the Little Ice Age associated with 14 C anomalies. (author) 9 tabs., 8 figs., 23 refs

  20. Carbon isotopes: variations of their natural abundance. Application to correction of radiocarbon dates, to the study of plant metabolism and to paleoclimate

    International Nuclear Information System (INIS)

    Lerman, J.C.

    1974-01-01

    The radiocarbon activity of contemporaneous samples shows: i) variations in the specific activity of the atmospheric C14, which varies with time and locality. ii) variations due to isotope discrimination, or fractionation, of the carbon isotope ratio during the fixation of carbon by organic or inorganic matter. The variation in the atmospheric concentration of carbon 14 as observed in tree rings are synchronous and of the same amplitude for both hemispheres (southern and northern). A curve for correction of radiocarbon dates of the southern hemisphere is given for the last 500 years. The activity of atmospheric radiocarbon as measured in tree rings varies with latitude, showing a difference of (4.5+-1) per mille between the northern and southern hemispheres, the latter having lower concentration of radiocarbon, equivalent to an age difference of about 35 years. This variation can be explained by a larger exchange of carbon 14 between the atmosphere and the sea in the southern hemisphere to a larger free ocean surface (40%) and a higher agitation by winds. The main differences of the isotope fractionation by different types of plants are correlated to their photosynthetic pathways and thus to the enzyme which effects the primary fixation of carbon. The delta C13 values can be used as basis of a paleoclimate indicator [fr

  1. On the radiocarbon record in banded corals: exchange parameters and net transport of 14CO2 between atmosphere and surface ocean

    International Nuclear Information System (INIS)

    Druffel, E.M.; Suess, H.E.

    1983-01-01

    We have made radiocarbon measurements of banded hermatypic corals from Florida, Belize, and the Galapagos Islands. Interpretation is presented here of these previously reported results. These measurements represent the 14 C/ 12 C ratios in dissolved inorganic carbon (DIOC) in the surface ocean waters of the Gulf Stream and the Peru Current at the time of coral ring formation. A depletion in radiocarbon concentration was observed incoral rings that grew from A.D. 1900--1952. It was caused by dilution of existing 14 C levels with dead CO 2 from fossil fuel burning (the Suess effect, or S/sub e/). A similar trend was observed in the distribution of bomb-produced 14 C in corals that had grown during the years following A.D. 1952. The concentration of bomb-produced radiocarbon was much higher in corals from temperate regions (Florida, Belize, Hawaiian Islands) than in corals from tropical regions (Galapagos Islands and Canton Island). The apparent radiocarbon ages of the surface waters in temperate and tropical oceans during the preanthropogenic period range from about 280 to 520 years B.P. (-40 to -69%). At all investigated locations, it is likely that waters at subsurface depths have the same apparent radiocarbon age of about 670 years B.P. From the change of oceanic δ 14 C in the surface during post-bomb times, the approximate annual rate of net input of 14 CO 2 to the ocean waters is calculated to be about 8% of the prevailing 14 C difference between atmosphere and ocean. From this input and from preanthropogenic δ 14 C values found at each location, it can be seen that vertical mixing of water in the Peru Current is about 3 times greater than that in the Gulf Stream

  2. Pre-bomb marine reservoir ages in the western north Pacific: Preliminary result on Kyoto University collection

    International Nuclear Information System (INIS)

    Yoneda, Minoru; Kitagawa, Hiroyuki; Plicht, Johannes van der; Uchida, Masao; Tanaka, Atsushi; Uehiro, Takashi; Shibata, Yasuyuki; Morita, Masatoshi; Ohno, Terufumi

    2000-01-01

    The calibration of radiocarbon dates on marine materials involves a global marine calibration with regional corrections. The marine reservoir ages in the Western North Pacific have not been discussed, while it is quite important to determine the timing of palaeo-environmental changes as well as archaeological interpretation around this region. The lack of adequate collection of the pre-bomb shell from western north Pacific was the biggest problem. Recently we had a chance to examine specimens from an old shell collection stored in Kyoto University, including shell specimens from Japan, Korea, Taiwan and the Micronesia of 1920s and 1930s. We explored the possibility for usage of specimen without clear evidence of live collection by measuring 30 apparent radiocarbon ages of pre-bomb mollusk shells from 18 sites in Western North Pacific. The preliminary results showed several discrepancies with previously reported results and with each other. We have to carefully select the shell specimen that has biological signs such as articulating fulcrum. In order to exploit this big resource of pre-bomb shell collection, the new technique to distinguish fossils from live collected samples should be developed by using chemical and physical methods

  3. Mammoths inside the Alps during the last glacial period: Radiocarbon constraints from Austria and palaeoenvironmental implications

    Science.gov (United States)

    Spötl, Christoph; Reimer, Paula J.; Göhlich, Ursula B.

    2018-06-01

    This study examines remains of the woolly mammoth (Mammuthus primigenius) found inside the Austrian Alps, an area occupied by an extensive ice-stream network during the Last Glacial Maximum. The data demonstrate that these cold steppe-adapted animals locally migrated several tens of kilometers into alpine valleys. Radiocarbon analyses constrain the age of these fossils to the first half of Marine Isotope Stage 3, documenting ice-free conditions in major valleys at that time. We also provide a list of all traceable Austrian sites of Mammuthus primigenius, totaling about 230 localities, compiled through 15 museums and collections in Austria. The vast majority of these findings are from the corridors of the Danube and Mur rivers and their tributaries and the adjacent loess-covered foreland of the Alps, areas that were never ice-covered during Pleistocene glaciations.

  4. Santorini eruption radiocarbon dated to 1627-1600 B.C.

    Science.gov (United States)

    Friedrich, Walter L; Kromer, Bernd; Friedrich, Michael; Heinemeier, Jan; Pfeiffer, Tom; Talamo, Sahra

    2006-04-28

    Precise and direct dating of the Minoan eruption of Santorini (Thera) in Greece, a global Bronze Age time marker, has been made possible by the unique find of an olive tree, buried alive in life position by the tephra (pumice and ashes) on Santorini. We applied so-called radiocarbon wiggle-matching to a carbon-14 sequence of tree-ring segments to constrain the eruption date to the range 1627-1600 B.C. with 95.4% probability. Our result is in the range of previous, less precise, and less direct results of several scientific dating methods, but it is a century earlier than the date derived from traditional Egyptian chronologies.

  5. Vibracore, Radiocarbon, Microfossil, and Grain-Size Data from Apalachicola Bay, Florida

    Science.gov (United States)

    Twichell, D.C.; Pendleton, E.A.; Poore, R.Z.; Osterman, L.E.; Kelso, K.W.

    2009-01-01

    In 2007, the U.S. Geological Survey collected 24 vibracores within Apalachicola Bay, Florida. The vibracores were collected by using a Rossfelder electric percussive (P-3) vibracore system during a cruise on the Research Vessel (R/V) G.K. Gilbert. Selection of the core sites was based on a geophysical survey that was conducted during 2005 and 2006 in collaboration with the National Oceanic and Atmospheric Administration's (NOAA) Coastal Services Center (CSC) and the Apalachicola Bay National Estuarine Research Reserve. This report contains the vibracore data logs, photographs, and core-derived data including grain-size analyses, radiocarbon ages, microfossil counts, and sedimentological interpretations. The long-term goal of this study is to provide maps, data, and assistance to the Apalachicola Bay National Estuarine Research Reserve in their effort to monitor and understand the geology and ecology of Apalachicola Bay Estuary. These data will inform coastal managers charged with the responsibility for resource preservation.

  6. Radiocarbon reservoir between charred seeds and fish bone in Neolithic sites, northeastern Qinghai-Tibetan Plateau

    Science.gov (United States)

    Zhou, A.; Dong, G.; Ren, L.

    2017-12-01

    Many efforts have been done to understand the reservoir effect of Qinghai Lake, yet no agreement has been reached. Five archaeological sites, located around the junction between the estuary of Rivers and Qinghai Lake, are the earliest Neolithic Age sites in the Qinghai- Tibetan Plateau (QTP), which is critical for understanding patterns of prehistoric human inhabitation in the high plateau extreme environments. This study compares radiocarbon dates of fish bones and terrestrial plant remains uncovered from the same archaeological strata to see whether there was reservoir effect reference to reliable data. Results demonstrate that there were reservoir effects ranging from 300 to 600 years back to 3600 years ago, nevertheless, no reservoir was observed of the modern fish. Besides, stable isotopic analysis illustrated that modern fish consumed similar food to those of millennias ago.

  7. Application of AMS radiocarbon in earth system science studies

    International Nuclear Information System (INIS)

    Kang, Dong Jin; Park, Mi Kyung; Kim, Kyung Ryul

    2001-01-01

    Radiocarbon, a cosmic ray-produced isotope, is one of the most important tracers in Earth system sciences. The strong involvement of carbon in the biosphere and its half life of 5720 years are reflected in appropriate applications in archeology, as well as in the Earth system sciences. Radiocarbon dating had an important turning point in 1977 with the discovery that mass spectrometry with tandem acceleration could be used to measure C-14. This new technique, known as AMS or accelerator mass spectrometry reduced the required sample size to the order of mg, three orders of magnitude smaller than for conventional techniques, thus opening the range of applicability of C-14 studies to a much wider range of samples. However, the application has been complicated by two major activities of human beings on a global scale: the extensive usage of fossil fuel since the industrial revolution and nuclear testing in the atmosphere, which have influenced the natural balance of radiocarbon in the atmosphere. However, the separation of bomb-produced carbon from natural background carbon has produced a very fruitful understanding of the global carbon cycle and the conveyor belt system in the ocean, which will be essential for understanding global environmental problems, such as global warming, in the coming century. Carbon cycle studies in Korea have been made since the early 1990s. The studies include monitoring of CO 2 concentrations in the atmosphere, stable isotope studies, and carbon cycle studies in the sea around Korea. The opening of ths AMS facility at Seoul National University (SNU) will enhance carbon studies in Earth system sciences greatly in the future

  8. Radiocarbon accelerator mass spectrometry (AMS) sample preparation laboratory in Brazil

    International Nuclear Information System (INIS)

    Macario, Kita D.; Gomes, Paulo R. S.; Anjos, Roberto M. dos; Linares, Roberto; Queiroz, Eduardo; Oliveira, Fabiana M. de; Cardozo, Laio; Carvalho, Carla R.A.

    2011-01-01

    Full text: For decades Accelerator Mass Spectrometry has been widely used for radiocarbon measurements all over the world with application in several fields of science from archaeology to geosciences. This technique provides ultrasensitive analysis of reduced size samples or even specific compounds since sample atoms are accelerated to high energies and measured using nuclear particle detectors. Sample preparation is extremely important for accurate radiocarbon measurement and includes chemical pre-treatment to remove all possible contaminants. For beam extraction in the accelerator ion source, samples are usually converted to graphite. In this work we report a new radiocarbon sample preparation facility installed at the Physics Institute of Universidade Federal Fluminense (UFF), in Brazil. At the Nuclear Chronology Laboratory (LACRON) samples are chemically treated and converted to carbon dioxide by hydrolysis or combustion. A stainless steel based vacuum line was constructed for carbon dioxide separation and graphitization is performed in sealed quartz tubes in a muffle oven. Successful graphite production is important to provide stable beam currents and to minimize isotopic fractionation. Performance tests for graphite production are currently under way and isotopic analysis will soon be possible with the acquisition of a Single Stage AMS System by our group. The Single Stage Accelerator produced by National Electrostatic Corporation is a 250 kV air insulated accelerator especially constructed to measure the amount of 14 C in small modern graphite samples to a precision of 0.3 % or better. With the installation of such equipment in the first half of 2012, UFF will be ready to perform the 14C -AMS technique. (author)

  9. Radiocarbon dating of bottom sediments of the Red Sea

    International Nuclear Information System (INIS)

    Kuptsov, V.M.; Palkina, A.M.

    1986-01-01

    Results of radiocarbon dating of 23 cores (81 definitions) sampled in the Red Sea rifton at 18 deg N are presented. Dating encompasses all major tectonic structures: the upper and the lower tectonic steps, saline scarp, axial zone. For sediments of the upper tectonic step the normal course of sedimentogenesis is detected, in all other structures with a strongly dissected topography redeposition and nonaccumulation of sediments are widely developed. In Holocene the rate of sediment accumulation is 1.5-2 times lower than that in the late Wurm

  10. Utilization of minicomputer in the radiocarbon analysis measurements

    International Nuclear Information System (INIS)

    Szarka, J.; Krnac, S.

    1984-01-01

    Possibilities of minicomputer applications for radiocarbon analysis with multielement proportional counters are considered. Off-line on-line measuring system operation is possible. TPA-70 minicomputer and CAMAC electronics are used in on-line operation. Block-diagrams of data acquisition and data processing as well as the block-diagram of data evaluation program, which permits not only to increase the precision of the measurements, but also reduces the measuring time by 1/3, as compared with conventional methods, are given

  11. Quantity of dates trumps quality of dates for dense Bayesian radiocarbon sediment chronologies - Gas ion source 14C dating instructed by simultaneous Bayesian accumulation rate modeling

    Science.gov (United States)

    Rosenheim, B. E.; Firesinger, D.; Roberts, M. L.; Burton, J. R.; Khan, N.; Moyer, R. P.

    2016-12-01

    Radiocarbon (14C) sediment core chronologies benefit from a high density of dates, even when precision of individual dates is sacrificed. This is demonstrated by a combined approach of rapid 14C analysis of CO2 gas generated from carbonates and organic material coupled with Bayesian statistical modeling. Analysis of 14C is facilitated by the gas ion source on the Continuous Flow Accelerator Mass Spectrometry (CFAMS) system at the Woods Hole Oceanographic Institution's National Ocean Sciences Accelerator Mass Spectrometry facility. This instrument is capable of producing a 14C determination of +/- 100 14C y precision every 4-5 minutes, with limited sample handling (dissolution of carbonates and/or combustion of organic carbon in evacuated containers). Rapid analysis allows over-preparation of samples to include replicates at each depth and/or comparison of different sample types at particular depths in a sediment or peat core. Analysis priority is given to depths that have the least chronologic precision as determined by Bayesian modeling of the chronology of calibrated ages. Use of such a statistical approach to determine the order in which samples are run ensures that the chronology constantly improves so long as material is available for the analysis of chronologic weak points. Ultimately, accuracy of the chronology is determined by the material that is actually being dated, and our combined approach allows testing of different constituents of the organic carbon pool and the carbonate minerals within a core. We will present preliminary results from a deep-sea sediment core abundant in deep-sea foraminifera as well as coastal wetland peat cores to demonstrate statistical improvements in sediment- and peat-core chronologies obtained by increasing the quantity and decreasing the quality of individual dates.

  12. Radiocarbon Evidence That Millennial and Fast-Cycling Soil Carbon are Equally Sensitive to Warming

    Science.gov (United States)

    Vaughn, L. S.; Torn, M. S.; Porras, R. C.

    2017-12-01

    Within the century, the Arctic is expected to shift from a sink to a source of atmospheric CO2 due to climate-induced increases in soil carbon mineralization. The magnitude of this effect remains uncertain, due in large part to unknown temperature sensitivities of organic matter decomposition. In particular, the distribution of temperature sensitivities across soil carbon pools remains unknown. New experimental approaches are needed, because studies that fit multi-pool models to CO2 flux measurements may be sensitive to model assumptions, statistical effects, and non-steady-state changes in substrate availability or microbial activity. In this study, we developed a new methodology using natural abundance radiocarbon to evaluate temperature sensitivities across soil carbon pools. In two incubation experiments with soils from Barrow, AK, we (1) evaluated soil carbon age and decomposability, (2) disentangled the effects of temperature and substrate depletion on carbon mineralization, and (3) compared the temperature sensitivities of fast- and slow-cycling soil carbon pools. From a long-term incubation, both respired CO2 and the remaining soil organic matter were highly depleted in radiocarbon. At 20 cm depth, median Δ14C values were -167‰ in respired CO2 and -377‰ in soil organic matter, corresponding to turnover times of 1800 and 4800 years, respectively. Such negative Δ14C values indicate both storage and decomposition of old, stabilized carbon, while radiocarbon differences between the mineralized and non-mineralized fractions suggest that decomposability varies along a turnover time gradient. Applying a new analytical method combining CO2 flux and Δ14C, we found that fast- and slow-cycling carbon pools were equally sensitive to temperature, with a Q10 of 2 irrespective of turnover time. We conclude that in these Arctic soils, ancient soil carbon is vulnerable to warming under thawed, aerobic conditions. In contrast to many previous studies, we found no

  13. Absolute dating of the Aegean Late Bronze Age

    International Nuclear Information System (INIS)

    Warren, P.M.

    1987-01-01

    A recent argument for raising the absolute date of the beginning of the Aegean Late Bronze (LB) Age to about 1700 B.C. is critically examined. It is argued here that: (1) the alabaster lid from Knossos did have the stratigraphical context assigned to it by Evans, in all probability Middle Minoan IIIA, c. 1650 B.C.; (2) the attempt to date the alabastron found in an early Eighteenth Dynasty context at Aniba to Late Minoan IIIA:1 is open to objections; (3) radiocarbon dates from Aegean LB I contexts are too wide in their calibrated ranges and too inconsistent both within and between site sets to offer any reliable grounds at present for raising Aegean LB I absolute chronology to 1700 B.C. Other evidence, however, suggests this period began about 1600 B.C., i.e. some fifty years earlier than the conventional date of 1550 B.C. (author)

  14. Change of the radiocarbon natural level in the Earth atmosphere and geomagnetic field

    International Nuclear Information System (INIS)

    Vasil'ev, S.S.; Dergachev, V.A.

    1995-01-01

    Harmonic spectral analysis of change of radiocarbon concentration on the Earth atmosphere during the last 7000 years, including time intervals of both high and low intensity of the Earth magnetic field, was conducted. The effect of geomagnetic field on a harmonic amplitudes and frequencies in variations of radiocarbon concentration, conditioned by solar activity, was shown

  15. Intracavity OptoGalvanic Spectroscopy Not Suitable for Ambient Level Radiocarbon Detection

    NARCIS (Netherlands)

    Paul, Dipayan; Meijer, Harro

    2015-01-01

    IntraCavity OptoGalvanic Spectroscopy as a radiocarbon detection technique was first reported by the Murnick group at Rutgers University, Newark, NJ, in 2008. This technique for radiocarbon detection was presented with tremendous potentials for applications in various fields of research.

  16. New observations on the stratigraphy and radiocarbon dates at the Cross Creek site, Opito, Coromandel Peninsula

    International Nuclear Information System (INIS)

    Furey, L.; Petchey, F.; Sewell, B.; Green, R.

    2008-01-01

    This paper re-examines stratigraphy and radiocarbon dates at Cross Creek in Sarah's Gully. Three new radiocarbon dates are presented for Layer 9, the earliest, and previously undated, occupation. This investigation is part of a programme of archaeological work being carried out on the Coromandel Peninsula. (author). 51 refs., 4 figs., 3 tabs

  17. Bomb conversion of CO2 to graphite for radiocarbon measurement by tandem accelerator mass spectrometry (TAMS)

    International Nuclear Information System (INIS)

    Lowe, D.C.; Judd, W.J.

    1985-01-01

    TAMS has extended the scope of radiocarbon dating but improved sample target preparation techniques are still required. In this paper a quick and reliable method for the conversion of CO 2 into graphite targets suitable for radiocarbon dating is presented. In the outlined procedure a single operator can produce 20 graphite targets a day. (author)

  18. Changes in groundwater reserves and radiocarbon and chloride content due to a wet period intercalated in an arid climate sequence in a large unconfined aquifer

    Science.gov (United States)

    Custodio, E.; Jódar, J.; Herrera, C.; Custodio-Ayala, J.; Medina, A.

    2018-01-01

    The concentration of atmospheric tracers in groundwater samples collected from springs and deep wells is, in most cases, the result of a mixture of waters with a wide range of residence times in the ground. Such is the case of an unconfined aquifer recharged over all its surface area. Concentrations greatly differ from the homogeneous residence time case. Data interpretation relies on knowledge of the groundwater flow pattern. To study relatively large systems, the conservative ion chloride and the decaying radiocarbon (14C) are considered. Radiocarbon (14C) activity in groundwater, after correction to discount the non-biogenic contribution, is often taken as an indication of water age, while chloride can be used to quantify recharge. In both cases, the observed tracer content in groundwater is an average value over a wide range which is related to water renewal time in the ground. This is shown considering an unconfined aquifer recharged all over its area under arid conditions, in which a period of greater recharge happened some millennia ago. The mathematical solution is given. As the solution cannot be made general, to show and discuss the changes in water reserve and in chloride and radiocarbon concentration (apparent ages), two scenarios are worked out, which are loosely related to current conditions in Northern Chile. It is shown that tracer concentration and the estimated water age are not directly related to the time since recharge took place. The existence of a previous wetter-than-present period has an important and lasting effect on current aquifer water reserves and chloride concentration, although the effect on radiocarbon activity is less pronounced. Chloride concentrations are smaller than in current recharge and apparent 14C ages do not coincide with the timing, duration and characteristics of the wet period, except in the case in which recharge before and after the wet period is negligible and dead aquifer reserves are non-significant. The use of

  19. The Acheron rock avalanche deposit, Canterbury, New Zealand : age and implications for dating landslides

    International Nuclear Information System (INIS)

    Smith, G.M.; Bell, D.H.; Davies, T.R.H.

    2012-01-01

    New radiocarbon ages for wood samples retrieved from the base of the Acheron rock avalanche near Porters Pass, Canterbury, show a clustering of ages between 1370 and 1101 yr BP. This is significantly dissimilar to the established radiocarbon age of 500 ± 69 yr BP (NZ547), from weathering-rind thickness measurements and from lichen studies. This contradiction impacts on current calibrations of lichenometric and weathering-rind dating methods, which has serious implications for landslide and earthquake dates based on them. A 500-600 yr BP earthquake event along the Porters Pass-Amberley Fault Zone has been dated in an adjacent trench and is consistent with previous dates but does not correspond to the Acheron rock avalanche emplacement as previously proposed. The landslide may have been caused by either a Porters Pass Fault event (1100-800 yr BP) or by the better-constrained Round Top event (1010 ± 50 yr BP) on the Alpine Fault. (author). 30 refs., 13 figs., 2 tabs.

  20. Aquifer recharging in South Carolina: radiocarbon in environmental hydrogeology

    International Nuclear Information System (INIS)

    Stone, P.A.; Knox, R.L.; Mathews, T.D.

    1985-01-01

    Radiocarbon activities of dissolved inorganic carbon (and tritium activities where infiltration rates are rapid and aquifers shallow) provide relatively unambiguous and inexpensive evidence for identification of significant recharge areas. Such evidence is for the actual occurrence of modern recharge in the aquifer and thus is less inferential than stratigraphic or potentiometric evidence. These underutilized isotopic techniques are neither arcane nor complex and have been more-or-less standardized by earlier researchers. In South Carolina, isotopic evidence has been used from both calcareous and siliceous sedimentary aquifers and fractured crystalline rock aquifers. The Tertiary limestone aquifer is shown not to be principally recharged in its subcrop area, unlike conditions assumed for many other sedimentary aquifers in southeastern United States, and instead receives considerable lateral recharge from interfingering updip Tertiary sand aquifers in the middle coastal plain. Induced recharging at Hilton Head Island is mixing ancient relict water and modern recharge water. Recharging to deeper portions of the Cretaceous Middendorf basal sand aquifer occurs at least as far coastward as the middle coastal plain, near sampling sites that stratigraphically appear to be confined. Pronounced mineralization of water in fractured rocks cannot be considered as evidence of ancient or relict ground water that is isolated from modern contaminants, some of these waters contain considerable radiocarbon and hydrogen-bomb tritium

  1. Influence of thermal treatments on radiocarbon dating of groundwater samples

    Science.gov (United States)

    Stanciu, Iuliana Madalina; Sava, Tiberiu Bogdan; Pacesila, Doru Gheorghe; Gaza, Oana; Simion, Corina Anca; Stefan, Bianca Maria; Sava, Gabriela Odilia; Ghita, Dan Gabriel; Mosu, Vasile

    2017-06-01

    Radiocarbon measurements of dissolved inorganic carbon (DIC) in water provides information about the formation of oceanic circulation of the water volumes, the hydrogeological systems, and also valuable information can be gained about the aquifer storage and the degree of containment relative to the surface waters. Radiocarbon dating refers to the determination of small quantities of the naturally occurring carbon 14 in the water, which can be integrated in the groundwater mass through the gaseous CO2, carbonaceous deposits dissolved by water and organic remains. The aim of this study is to investigate the influence of the temperature and pressure over the amount of each isotope of carbon during the sample preparation stage. The first step was to evaporate several underground water samples at 65°C under different conditions until the carbonates were obtained, then the CO2 was extracted with orto-phosphoric acid and transformed to graphite. The second step was to obtain graphite from an untreated water sample. Finally, the samples were measured with the 1MV Cockcroft-Walton Tandetron Accelerator by Accelerator Mass Spectrometry.

  2. Radiocarbon Dating on Jabung Temple Sites one of the Temples in East Java

    International Nuclear Information System (INIS)

    F, Wisjachudin; Rosyidin; Sumiyatno; Siswanto; Siregar, DarwinA.

    2000-01-01

    Radiocarbon dating of organic materials (charcoal) around Jabung templein Jabung temple village, Paiton, Probolinggo district, East Java provincehas been carried out. Excavation archaeologically in different location incertain distance has been done which is considered relevant to the temple'sage and the location of the excavation boxes are the test holes (TH=LU) i.e :LU 1, LU 2, LU 3, LU 4, LU 5, LU 6, LU 7, and LU 8. From those test holes wecan find out that only LU 4 and LU 3 which contain significant charcoal. Thepretreatment (acid, base, acid washing) followed by continued preparationwith carbon contained charcoal burning process, burn to be acetylene gas (C 2 H 2 ). 14 C contained in acetylene is counted by gas proportional counter.After being processed charcoal from LU 3 is not qualified in volumerequirement which is needed for the next analysis. The result for 3000minutes, for background counting = 1.1 ± 0.21 cpm, counting of standard14.51 ± 0.52 cpm, while counting from charcoal sample only from LU 4location is 13.51 ± 0.12 cpm. From data of LU 4 charcoal counting above,we can count the date (age) of the sample that is 510 ± 80 BP. If we usetree ring correction for the data, result will be between 1306-1456 AD onlevel of confidence 68.3% while on level of confidence 95.4% result will bebetween 1281-1624 AD. Relative dating base on ancient inscription show 1354AD. From the data, relative dating is in the range of to absolute dating(radiocarbon dating). (author)

  3. Radiocarbon dating and wood density chronologies of mangrove trees in arid Western Australia.

    Directory of Open Access Journals (Sweden)

    Nadia S Santini

    Full Text Available Mangrove trees tend to be larger and mangrove communities more diverse in tropical latitudes, particularly where there is high rainfall. Variation in the structure, growth and productivity of mangrove forests over climatic gradients suggests they are sensitive to variations in climate, but evidence of changes in the structure and growth of mangrove trees in response to climatic variation is scarce. Bomb-pulse radiocarbon dating provides accurate dates of recent wood formation and tree age of tropical and subtropical tree species. Here, we used radiocarbon techniques combined with X-ray densitometry to develop a wood density chronology for the mangrove Avicennia marina in the Exmouth Gulf, Western Australia (WA. We tested whether wood density chronologies of A. marina were sensitive to variation in the Pacific Decadal Oscillation Index, which reflects temperature fluctuations in the Pacific Ocean and is linked to the instrumental rainfall record in north WA. We also determined growth rates in mangrove trees from the Exmouth Gulf, WA. We found that seaward fringing A. marina trees (~10 cm diameter were 48 ± 1 to 89 ± 23 years old (mean ± 1 σ and that their growth rates ranged from 4.08 ± 2.36 to 5.30 ± 3.33 mm/yr (mean ± 1 σ. The wood density of our studied mangrove trees decreased with increases in the Pacific Decadal Oscillation Index. Future predicted drying of the region will likely lead to further reductions in wood density and their associated growth rates in mangrove forests in the region.

  4. Bomb-curve radiocarbon measurement of recent biologic tissues and applications to wildlife forensics and stable isotope (paleo)ecology

    Science.gov (United States)

    Uno, Kevin T.; Quade, Jay; Fisher, Daniel C.; Wittemyer, George; Douglas-Hamilton, Iain; Andanje, Samuel; Omondi, Patrick; Litoroh, Moses; Cerling, Thure E.

    2013-07-01

    Above-ground thermonuclear weapons testing from 1952 through 1962 nearly doubled the concentration of radiocarbon (14C) in the atmosphere. As a result, organic material formed during or after this period may be radiocarbon-dated using the abrupt rise and steady fall of the atmospheric 14C concentration known as the bomb-curve. We test the accuracy of accelerator mass spectrometry radiocarbon dating of 29 herbivore and plant tissues collected on known dates between 1905 and 2008 in East Africa. Herbivore samples include teeth, tusks, soft tissue, hair, and horn. Tissues formed after 1955 are dated to within 0.3-1.3 y of formation, depending on the tissue type, whereas tissues older than ca. 1955 have high age uncertainties (>17 y) due to the Suess effect. 14C dating of tissues has applications to stable isotope (paleo)ecology and wildlife forensics. We use data from 41 additional samples to determine growth rates of tusks, molars, and hair, which improve interpretations of serial stable isotope data for (paleo)ecological studies. 14C dating can also be used to calculate the time interval represented in periodic histological structures in dental tissues (i.e., perikymata), which in turn may be used as chronometers in fossil teeth. Bomb-curve 14C dating of confiscated animal tissues (e.g., ivory statues) can be used to determine whether trade of the item is legal, because many Convention of International Trade of Endangered Species restrictions are based on the age of the tissue, and thus can serve as a powerful forensic tool to combat illegal trade in animal parts.

  5. Bomb-curve radiocarbon measurement of recent biologic tissues and applications to wildlife forensics and stable isotope (paleo)ecology

    Science.gov (United States)

    Uno, Kevin T.; Quade, Jay; Fisher, Daniel C.; Wittemyer, George; Douglas-Hamilton, Iain; Andanje, Samuel; Omondi, Patrick; Litoroh, Moses; Cerling, Thure E.

    2013-01-01

    Above-ground thermonuclear weapons testing from 1952 through 1962 nearly doubled the concentration of radiocarbon (14C) in the atmosphere. As a result, organic material formed during or after this period may be radiocarbon-dated using the abrupt rise and steady fall of the atmospheric 14C concentration known as the bomb-curve. We test the accuracy of accelerator mass spectrometry radiocarbon dating of 29 herbivore and plant tissues collected on known dates between 1905 and 2008 in East Africa. Herbivore samples include teeth, tusks, soft tissue, hair, and horn. Tissues formed after 1955 are dated to within 0.3–1.3 y of formation, depending on the tissue type, whereas tissues older than ca. 1955 have high age uncertainties (>17 y) due to the Suess effect. 14C dating of tissues has applications to stable isotope (paleo)ecology and wildlife forensics. We use data from 41 additional samples to determine growth rates of tusks, molars, and hair, which improve interpretations of serial stable isotope data for (paleo)ecological studies. 14C dating can also be used to calculate the time interval represented in periodic histological structures in dental tissues (i.e., perikymata), which in turn may be used as chronometers in fossil teeth. Bomb-curve 14C dating of confiscated animal tissues (e.g., ivory statues) can be used to determine whether trade of the item is legal, because many Convention of International Trade of Endangered Species restrictions are based on the age of the tissue, and thus can serve as a powerful forensic tool to combat illegal trade in animal parts. PMID:23818577

  6. Millennium scale radiocarbon variations in Eastern North Atlantic thermocline waters: 0-7000 years

    Energy Technology Data Exchange (ETDEWEB)

    Frank, N.; Tisnerat-Laborde, N.; Hatte, C. [LSCE, F-91190 Gif Sur Yvette, (France); Colin, C. [Univ Paris 11, IDES, Orsay, (France); Dottori, M.; Reverdin, G. [Univ Paris 06, LOCEAN, F-75252 Paris, (France)

    2009-07-01

    Complete text of publication follows: Deep water corals are exceptional archives of modern and past ocean circulation as combined U-series and radiocarbon dating allows to reconstruct seawater radiocarbon. Here we present thermocline water radiocarbon concentrations that have been reconstructed for the past {approx} 7000 years for the eastern north Atlantic, based on deep-water corals from Rockall Bank and Porcupine Seabight. We find that thermocline water radiocarbon values follow overall the mean atmospheric long term trend with an average offset of {Delta}{sup 14}C between intermediate water and atmosphere of -55{+-}5 per thousand until 1960 AD. Residual variations are strong ({+-}25 per thousand) over the past 7000 years and there is first evidence that those are synchronous to millennium scale climate variability. Over the past 60 years thermocline water radiocarbon values increase due to the penetration of bomb-radiocarbon into the upper intermediate ocean. Radiocarbon increases by {Delta}{sup 14}C of +95 per thousand compared to +210 per thousand for eastern North Atlantic surface waters. Moreover, bomb-radiocarbon penetration to thermocline depth occurs with a delay of {approx} 10-15 years. Based on high resolution ocean circulation models we suggest that radiocarbon changes at upper intermediate depth are today barely affected by vertical mixing and represent more likely variable advection and mixing of water masses from the Labrador Sea and the temperate Atlantic (including Mediterranean outflow water). Consequently, we assume that residual radiocarbon variations over the past 7000 years reflect millennium scale variability of the Atlantic sub-polar and sub-tropical gyres

  7. Optimizing sampling strategy for radiocarbon dating of Holocene fluvial systems in a vertically aggrading setting

    International Nuclear Information System (INIS)

    Toernqvist, T.E.; Dijk, G.J. Van

    1993-01-01

    The authors address the question of how to determine the period of activity (sedimentation) of fossil (Holocene) fluvial systems in vertically aggrading environments. The available data base consists of almost 100 14 C ages from the Rhine-Meuse delta. Radiocarbon samples from the tops of lithostratigraphically correlative organic beds underneath overbank deposits (sample type 1) yield consistent ages, indicating a synchronous onset of overbank deposition over distances of at least up to 20 km along channel belts. Similarly, 14 C ages from the base of organic residual channel fills (sample type 3) generally indicate a clear termination of within-channel sedimentation. In contrast, 14 C ages from the base of organic beds overlying overbank deposits (sample type 2), commonly assumed to represent the end of fluvial sedimentation, show a large scatter reaching up to 1000 14 C years. It is concluded that a combination of sample types 1 and 3 generally yields a satisfactory delimitation of the period of activity of a fossil fluvial system. 30 refs., 11 figs., 4 tabs

  8. Bayesian re-evaluation of Lapita settlement in Fiji : radiocarbon analysis of the Lapita occupation at Bourewa and nearby sites on the Rove Peninsula, Viti Levu Island

    International Nuclear Information System (INIS)

    Nunn, P.D.; Petchey, F.

    2013-01-01

    80 radiocarbon dates are presented for Lapita-era sites on the Rove Peninsula, southwest Viti Levu Island, Fiji. Of these, 67 are from the Bourewa site which is the largest and probably the earliest in the area. Of these, 10 are rejected as not being demonstrably associated with its Lapita occupation. Constraints on date interpretation arising from sample materials are highlighted. In particular, charcoals that have not been identified to short-lived tree species, twigs or seeds are evaluated according to observed contextual associations and established understanding of inbuilt age offsets using Bayesian outlier analysis. It is concluded that many of the dates on charcoal are imprecise indicators of settlement age and have an average offset of 149 years. Shell radiocarbon results are similarly evaluated and it is concluded that the majority have 14 C values that are in equilibrium with the marine radiocarbon reservoir and therefore yield ages that are accurate indicators of Lapita occupation of Bourewa. Results suggest that initial occupation at Bourewa occurred 2816 ± 25 cal BP (2838-2787 cal BP [68.2% prob.]; 2866-2771 cal BP [95.4% prob.]) and ended 2654 ± 21 cal BP (2675-2640 cal BP [68.2% prob.]; 2689-2613 cal BP [95.4% prob.]). Similar analyses applied to other dated Lapita sites in Fiji shows that, while Bourewa is among the earliest, the Matanamuani (VL 21/5) site on Naigani Island remains the earliest to be securely dated. (author)

  9. The role of the archaeologist in C-14 age measurement. Appendix II

    International Nuclear Information System (INIS)

    Harkness, D.D.

    1975-01-01

    A C-14 date may be considered to exist in two forms: (a) the 'conventional age' as reported by C-14 laboratories and/or published in the journal Radiocarbon, and (b) the so-called 'corrected age' derived after recourse to half-life changes and calibration curves or tables. While a great deal of advice has been presented to the archaeologist on how he should best correct and interpret the basic conventional C-14 date the importance of his role in ensuring its validity has been largely neglected. This article would hope to clarify where and why the archaeologist can assist in the practical aspects of dating and in so doing also answer such familiar questions as: which sample material is most suited to the production of a valid C-14 date; how much material is required; how are samples best collected, recorded, stored and transported. (author)

  10. Radiocarbon Analysis to Calculate New End-Member Values for Biomass Burning Source Samples Specific to the Bay Area

    Science.gov (United States)

    Yoon, S.; Kirchstetter, T.; Fairley, D.; Sheesley, R. J.; Tang, X.

    2017-12-01

    Elemental carbon (EC), also known as black carbon or soot, is an important particulate air pollutant that contributes to climate forcing through absorption of solar radiation and to adverse human health impacts through inhalation. Both fossil fuel combustion and biomass burning, via residential firewood burning, agricultural burning, wild fires, and controlled burns, are significant sources of EC. Our ability to successfully control ambient EC concentrations requires understanding the contribution of these different emission sources. Radiocarbon (14C) analysis has been increasingly used as an apportionment tool to distinguish between EC from fossil fuel and biomass combustion sources. However, there are uncertainties associated with this method including: 1) uncertainty associated with the isolation of EC to be used for radiocarbon analysis (e.g., inclusion of organic carbon, blank contamination, recovery of EC, etc.) 2) uncertainty associated with the radiocarbon signature of the end member. The objective of this research project is to utilize laboratory experiments to evaluate some of these uncertainties, particularly for EC sources that significantly impact the San Francisco Bay Area. Source samples of EC only and a mix of EC and organic carbon (OC) were produced for this study to represent known emission sources and to approximate the mixing of EC and OC that would be present in the atmosphere. These samples include a combination of methane flame soot, various wood smoke samples (i.e. cedar, oak, sugar pine, pine at various ages, etc.), meat cooking, and smoldering cellulose smoke. EC fractions were isolated using a Sunset Laboratory's thermal optical transmittance carbon analyzer. For 14C analysis, samples were sent to Woods Hole Oceanographic Institution for isotope analysis using an accelerated mass spectrometry. End member values and uncertainties for the EC isolation utilizing this method will be reported.

  11. Atmospherically dispersed radiocarbon at the Chalk River Laboratories

    International Nuclear Information System (INIS)

    Milton, G.M.; Brown, R.M.; Repta, C.J.W.; Selkirk, C.J.

    1996-01-01

    A small percentage of the total radiocarbon produced by the NRX and NRU experimental reactors at the Chalk River Laboratories has been vented from the main reactor stack and atmospherically dispersed across the site. Surveys conducted in 1982-83 and 1993-94 have shown that atmospheric levels more than 50 m from the stack are never greater than 600 Bq.kg -1 carbon above the natural background level, falling to near-global atmospheric levels at the site boundaries roughly 7 km away. A dispersion factor > 1.2 x 10 6 m 3 .s -1 at ∼ 0.75 km distance from the point of emission is calculated on the basis of recent in-stack monitoring. Analysis of growth rings in on-site trees has provided an opportunity to search for correlations of 14 C output summer power production and/or moderator losses. (author). 16 refs., 14 tabs., 11 figs

  12. Accelerator radiocarbon dating of evidence for prehistoric horticulture in Illinois

    Energy Technology Data Exchange (ETDEWEB)

    Conrad, N [Rochester Univ., NY (USA). Dept. of Anthropology; Rochester Univ., NY (USA). Dept. of Chemistry); Asch, D L; Asch, N B [Center for American Archeology, Kampsville, ILL (USA). Archeobotanical Lab.

    1984-03-29

    The authors have now used direct detection radiocarbon dating (which uses an accelerator as part of a highly selective mass spectrometer) to date small samples of carbonized, cultivated plant remains from archaeological sites in Illinois. The results, reported here, establish (1) that squash was introduced by 7,000 yr ago, 2,500 yr before eastern North American records previously reported; (2) that horticulture involving indigenous plants had begun by 4,000 BP in eastern North American with domestication of Iva annua, a small-seeded annual; (3) that anomalous discoveries of Archaic period maize represent contaminants; and (4) that introduction of maize by initial Middle Woodland times (approx. 2,000 BP) is questionable.

  13. Small-mass AMS radiocarbon analysis at Nagoya University

    Energy Technology Data Exchange (ETDEWEB)

    Minami, Masayo, E-mail: minami@nendai.nagoya-u.ac.jp [Center for Chronological Research, Nagoya University, Chikusa, Nagoya 464-8602 (Japan); Kato, Tomomi [Faculty of Science, Nagoya University, Nagoya 464-8602 (Japan); Miyata, Yoshiki; Nakamura, Toshio [Center for Chronological Research, Nagoya University, Chikusa, Nagoya 464-8602 (Japan); Hua Quan [Australian Nuclear Science and Technology Organization, Locked Bag 2001, Kirrawee DC, NSW 2232 (Australia)

    2013-01-15

    As part of the ongoing development at the AMS facility of the Center for Chronological Research at Nagoya University to radiocarbon ({sup 14}C) analyze samples smaller than 0.5 mg carbon (mgC), a compact graphitization manifold has been built. Tests with various reference materials show it performs well for samples as small as 0.1 mgC. Preparation with this new system is compared with the performance of the older protocol for regular-sized samples. Furthermore, it is shown that the addition of Cu and Ag before and stepwise heating during sealed-tube combustion of samples with high S content improve the degree of conversion to CO{sub 2} without having to resort to special purification measures such as the use of Co{sub 3}O{sub 4} + Ag reagent and an n-pentane/LN{sub 2} trap before graphitization.

  14. Radiocarbon dating with the Chalk River MP Tandem accelerator

    International Nuclear Information System (INIS)

    Ball, G.C.; Andrews, H.R.; Brown, R.M.; Burn, N.; Davies, W.G.; Imahori, Y.; Milton, J.C.D.

    1981-01-01

    During the past three years an automated radiocarbon dating system based on the MP Tandem accelerator has been developed for the analysis of 14 C in groundwater samples from the nuclear waste disposal research program and other small samples of scientific interest. At the present time 14 C/ 12 C ratio measurements can be determined with an accuracy of about 5% and the system background levels (approx. 35000 to 45000 years) are totally determined by sample and/or ion source contamination. Our goal has been to develop a dedicated reliable system for routine analysis that will produce accurate results with a minimum expenditure of human resources and accelerator beam time. Improvements required to operate the tandem accelerator as a quantitative tool have also benefited the rest of the experimental nuclear physics program. The early evolution of the dating facility was described previously. This paper is a brief report of the current status at Chalk River

  15. Problems and Possible Solutions Concerning Radiocarbon Dating of Surface Marine Sediments, Ross Sea, Antarctica

    Science.gov (United States)

    Andrews, John T.; Domack, Eugene W.; Cunningham, Wendy L.; Leventer, Amy; Licht, Kathy J.; Jull, A. J. Timothy; DeMaster, David J.; Jennings, Anne E.

    1999-09-01

    Radiocarbon accelerator mass spectrometric (AMS) dates on the acid-insoluble fraction from 38 core tops from the western Ross Sea, Antarctica, are used to address these questions: (1) What are the apparent ages of sediments at or close to the present sediment/water interface? (2) Is there a statistically significant pattern to the spatial distribution of core top ages? and (3) Is there a "correction factor" that can be applied to these age determinations to obtain the best possible Holocene (downcore) chronologies? Ages of core top sediments range from 2000 to 21,000 14C yr B.P. Some "old" core top dates are from piston cores and probably represent the loss of sediment during the coring process, but some core top samples >6000 14C yr B.P. may represent little or no Holocene deposition. Four possible sources of variability in dates ≤6000 14C yr B.P. (n = 28) are associated with (1) different sample preparation methods, (2) different sediment recovery systems, (3) different geographic regions, and (4) within-sample lateral age variability. Statistical analysis on an a posteriori design indicates that geographic area is the major cause of variability; there is a difference in mean surface sediment age of nearly 2000 yr between sites in the western Ross Sea and sites east of Ross Bank in south-central Ross Sea. The systematic variability in surface age between areas may be attributed to: (a) variable sediment accumulation rates (SAR) (surface age is inversely related to SAR), (b) differences in the percentage of reworked (dead) carbon between each area, and/or (c) differences in the CO2 exchange between the ocean and the atmosphere.

  16. Comparative radiocarbon dating of terrestrial plant macrofossils and aquatic moss from the ice-free corridor of western Canada

    Energy Technology Data Exchange (ETDEWEB)

    MacDonald, G.M.; Beukens, R.P.; Kieser, W.E.; Vitt, D.H.

    1987-09-01

    In order to assess the reliability of aquatic moss for radiocarbon dating, /sup 14/C analyses were performed on a stratigraphic series of terrestrial plant macrofossils and samples of Drepanocladus crassicostatus from a small, hard-water lake (pH = 8.2) in the ice-free corridor of Alberta. All /sup 14/C dating was done by using accelerator mass spectrometry. Mazama Ash provided an independent chronological control. The aquatic bryophyte samples consistently produced /sup 14/C ages significantly older than the terrestrial macrofossils. The relation between the radiocarbon dates from the macrofossils and the moss was not linear, and age differences ranged from approximately 1400 to 6400 yr. The /sup 14/C content of D. crassicostatus growing in the lake at present was less than 85% modern. Despite the apparent inability to take up /sup 14/C-deficient carbon by the direct incorporation of bicarbonate, the bryophytes clearly do not provide reliable material /sup 14/C dating. The /sup 14/C deficiency of aquatic mosses may be explained by the generation of /sup 14/C-deficient CO/sub 2/ through isotopic exchange, the formation of CO/sub 2/ from bicarbonate by chemical processes, and metabolic CO/sub 2/ production. These results demonstrate the potential unreliability of /sup 14/C dates from aquatic mosses and raise serious concerns about the deglaciation dates from the ice-free corridor that were obtained from aquatic Drepanocladus.

  17. Continuous-flow accelerator mass spectrometry for radiocarbon analysis

    International Nuclear Information System (INIS)

    Wills, J.S.C.; Han, B.X.; Von Reden, K.F.; Schneider, R.J.; Roberts, M.L.

    2006-01-01

    Accelerator Mass Spectrometry (AMS) is a widely used technique for radiocarbon dating of archaeological or environmental samples that are very small or very old (up to 50,000 years before present). Because of the method's extreme sensitivity, AMS can also serve as an environmental tracer and supplements conventional nuclear counting techniques for monitoring 14 C emissions from operating nuclear power plants and waste repositories. The utility of present AMS systems is limited by the complex sample preparation process required. Carbon from combusted artefacts must be incorporated into a solid metallic target from which a negative ion beam is produced and accelerated to MeV energies by an accelerator for subsequent analysis. This paper will describe a novel technique being developed by the National Ocean Sciences Accelerator Mass Spectrometry (NOSAMS) Laboratory at the Woods Hole Oceanographic Institution for the production of negative carbon ion beams directly from a continuously flowing sample gas stream, eliminating the requirement for a solid target. A key component of the new technique is a microwave-driven, gaseous-feed ion source originally developed at Chalk River Laboratories for the very different requirements of a high current proton linear accelerator. A version of this ion source is now being adapted to serve as an injector for a dedicated AMS accelerator facility at NOSAMS. The paper begins with a review of the fundamentals of radiocarbon dating. Experiments carried out at NOSAMS with a prototype of the microwave ion source are described, including measurements of sample utilization efficiency and sample 'memory' effect. A new version of the microwave ion source, optimized for AMS, is also described. The report concludes with some predictions of new research opportunities that will become accessible to the technique of continuous-flow AMS. (author)

  18. Radiocarbon detection by ion charge exchange mass spectrometry

    International Nuclear Information System (INIS)

    Hotchkis, Michael; Wei, Tao

    2007-01-01

    A method for detection of radiocarbon at low levels is described and the results of tests are presented. We refer to this method as ion charge exchange mass spectrometry (ICE-MS). The ICE-MS instrument is a two stage mass spectrometer. In the first stage, molecular interferences which would otherwise affect radiocarbon detection at mass 14 are eliminated by producing high charge state ions directly in the ion source (charge state ≥2). 14 N interference is eliminated in the second stage by converting the beam to negative ions in a charge exchange cell. The beam is mass-analysed at each stage. We have built a test apparatus consisting of an electron cyclotron resonance ion source and a pair of analysing magnets with a charge exchange cell in between, followed by an electrostatic analyser to improve the signal to background ratio. With this apparatus we have measured charge exchange probabilities for (C n+ → C - ) from 4.5 to 40.5 keV (n = 1-3). We have studied the sources of background including assessment of limits for nitrogen interference by searching for negative ions from charge exchange of 14 N ions. Our system has been used to detect 14 C in enriched samples of CO 2 gas with 14 C/ 12 C isotopic ratio down to the 10 -9 level. Combined with a measured sample consumption rate of 4 ng/s, this corresponds to a capability to detect transient signals containing only a few μBq of 14 C activity, such as may be obtained from chromatographic separation. The method will require further development to match the sensitivity of AMS with a gas ion source; however, even in its present state its sensitivity is well suited to tracer studies in biomedical research and drug development

  19. Radiocarbon mass balance for a Magnox nuclear power station

    International Nuclear Information System (INIS)

    Metcalfe, M.P.; Mills, R.W.

    2015-01-01

    Highlights: • First comprehensive assessment of C-14 arisings in a Magnox nuclear power station. • C-14 production in graphite and coolant gas quantified by activation modelling. • Principal C-14 production pathway is via C-13 with a small contribution from N-14. • C-14 mass balance model provides a basis for analyses on other reactors. - Abstract: Nuclear power generation in the United Kingdom is based principally on graphite-moderated gas-cooled reactors. The mass of irradiated graphite associated with these reactors, including material from associated experimental, prototype and plutonium production reactors, exceeds 96,000 tonnes. One of the principal long-lived radionuclides produced during graphite irradiation is radiocarbon (C-14). Its potential as a hazard must be taken into account in decommissioning and graphite waste management strategies. While C-14 production processes are well-understood, radionuclide distributions and concentrations need to be characterised. A common misconception is that generic statements can be made about C-14 precursors and their location. In fact, the composition of the original manufactured material, the chemical environment of the graphite during service and its irradiation history will all influence C-14 levels. The analysis presented here provides the first assessment of the principal C-14 activation pathways for a UK Magnox reactor. Activation modelling has been used to predict C-14 production rates in both the graphite core and the carbon dioxide coolant over a selected period of operation and the results compared with monitored site C-14 discharges. Principal activation routes have been identified, which should inform future graphite waste management strategies relating to radiocarbon

  20. Continuous-flow accelerator mass spectrometry for radiocarbon analysis

    International Nuclear Information System (INIS)

    Wills, J.S.C.; Han, B.X.; Von Reden, K.F.; Schneider, R.J.; Roberts, M.L.

    2006-05-01

    Accelerator Mass Spectrometry (AMS) is a widely used technique for radiocarbon dating of archaeological or environmental samples that are very small or very old (up to 50,000 years before present). Because of the method's extreme sensitivity, AMS can also serve as an environmental tracer and supplements conventional nuclear counting techniques for monitoring 14 C emissions from operating nuclear power plants and waste repositories. The utility of present AMS systems is limited by the complex sample preparation process required. Carbon from combusted artefacts must be incorporated into a solid metallic target from which a negative ion beam is produced and accelerated to MeV energies by an accelerator for subsequent analysis. This paper will describe a novel technique being developed by the National Ocean Sciences Accelerator Mass Spectrometry (NOSAMS) Laboratory at the Woods Hole Oceanographic Institution for the production of negative carbon ion beams directly from a continuously flowing sample gas stream, eliminating the requirement for a solid target. A key component of the new technique is a microwave-driven, gaseous-feed ion source originally developed at Chalk River Laboratories for the very different requirements of a high current proton linear accelerator. A version of this ion source is now being adapted to serve as an injector for a dedicated AMS accelerator facility at NOSAMS. The paper begins with a review of the fundamentals of radiocarbon dating. Experiments carried out at NOSAMS with a prototype of the microwave ion source are described, including measurements of sample utilization efficiency and sample 'memory' effect. A new version of the microwave ion source, optimized for AMS, is also described. The report concludes with some predictions of new research opportunities that will become accessible to the technique of continuous-flow AMS. (author)

  1. Radiocarbon dates of sediment cores from inner continental shelf off Taingapatnam, southwest coast of India

    International Nuclear Information System (INIS)

    Nambiar, A.R.; Rajagopalan, G.

    1995-01-01

    Radiocarbon dating of carbonized wood samples from three sediment cores from the inner continental shelf off Taingapatnam, in the southwestern coast of India, indicates ages in the bracket 8400-9400 YBP. These radiometric ages correlate well with the ages of carbonized wood from inner continental shelf off Ponnani, Kerala and Karwar, Karnataka. The occurrence of carbonized wood in widely spread offshore areas probably represents a regional transgressive event in the west coast which resulted in submergence and destruction of coastal mangroves. The rate of sedimentation in the study area varies between 0.12 and 0.37 mm/yr, much lower than those reported from shelf areas north of Mangalore. The slow accumulation of sediments in the southern parts of the western continental shelf of India, as exemplified from the present study, may be due to very poor discharge and low bed load sediments of the west-flowing small rivers of this part of the peninsula and low concentration of suspended particulate matter in them. (author). 24 refs., 2 tabs., 2 figs

  2. Stable isotope and radiocarbon analyses at the Stripa test site. Phase I

    International Nuclear Information System (INIS)

    Fritz, P.; Frape, S.K.; Fontes, J.C.

    1985-01-01

    The 18 O and 2 H contents of groundwaters in the Stripa granite document that deep and shallow groundwaters have a different origin and history. The lower heavy isotopes contents of the deep waters suggest recharge during a cooler climate and thus, possibly, an older age. This is supported by radiocarbon data-although it is not possible to deduce from much data definite ages or mean residence times of the deep waters. Widely variable carbon-13 contents in aqueous carbon and fracture calcites attest to the heterogeneous environments which characterize(d) these fracture systems: very negative S 13 C values in DIC and calcites provide strong indications that redox processes are active (bacterially mediated) and that both S 13 C of DIC and S 34 S values of aqueous sulfate are affected. This is relevant for an overall description of the geochemical environment, yet it has not been possible to assign a definite origin to the aqueous sulfate of these waters. Isotope data also demonstrate that it is not possible to ''age-date'' the deep waters on the basis of isotope echange reactions between sulfate and water

  3. Intracavity OptoGalvanic Spectroscopy not suitable for ambient level radiocarbon detection.

    Science.gov (United States)

    Paul, Dipayan; Meijer, Harro A J

    2015-09-01

    IntraCavity OptoGalvanic Spectroscopy as a radiocarbon detection technique was first reported by the Murnick group at Rutgers University, Newark, NJ, in 2008. This technique for radiocarbon detection was presented with tremendous potentials for applications in various fields of research. Significantly cheaper, this technique was portrayed as a possible complementary technique to the more expensive and complex accelerator mass spectrometry. Several groups around the world started developing this technique for various radiocarbon related applications. The IntraCavity OptoGalvanic Spectroscopy setup at the University of Groningen was constructed in 2012 in close collaboration with the Murnick group for exploring possible applications in the fields of radiocarbon dating and atmospheric monitoring. In this paper we describe a systematic evaluation of the IntraCavity OptoGalvanic Spectroscopy setup at Groningen for radiocarbon detection. Since the IntraCavity OptoGalvanic Spectroscopy setup was strictly planned for dating and atmospheric monitoring purposes, all the initial experiments were performed with CO2 samples containing contemporary levels and highly depleted levels of radiocarbon. Because of recurring failures in differentiating the two CO2 samples, with the radiocarbon concentration 3 orders of magnitude apart, CO2 samples containing elevated levels of radiocarbon were prepared in-house and experimented with. All results obtained thus far at Groningen are in sharp contrast to the results published by the Murnick group and rather support the results put forward by the Salehpour group at Uppsala University. From our extensive test work, we must conclude that the method is unsuited for ambient level radiocarbon measurements, and even highly enriched CO2 samples yield insignificant signal.

  4. The radiocarbon dating of the neolithic flint mines at Krzemionki in central Poland

    International Nuclear Information System (INIS)

    Babel, J.; Braziewicz, J.; JaskoIa, M.; Kretschmer, W.; Pajek, M.; Semaniak, J.; Scharf, A.; Uhl, T.

    2005-01-01

    Ten samples taken from wooden torches and small fireplaces discovered at the Krzemionki neolithic flint mine localized in central Poland were dated using the AMS facility at Erlangen University. The radiocarbon results points two main periods of exploitation of studied mines, i.e. approximately to 3500-3100 BC and to 3100-2900 BC. The results are discussed in the aspect of the mine chronology. The new radiocarbon dates confirm the previous radiocarbon data obtained from other mine units in this part of the Krzemionki mine complex

  5. A case of early Wisconsinan ;over-chill;: New radiocarbon evidence for early extirpation of western camel (Camelops hesternus) in eastern Beringia

    Science.gov (United States)

    Zazula, Grant D.; MacPhee, Ross D. E.; Southon, John; Nalawade-Chavan, Shweta; Reyes, Alberto V.; Hewitson, Susan; Hall, Elizabeth

    2017-09-01

    There are comparatively few fossils that document the presence of the Pleistocene western camel (Camelops hesternus) in the unglaciated regions of Alaska and Yukon, northwestern North America (eastern Beringia). It has been previously reported on the basis of stratigraphic and radiocarbon data that this species was present within this region from the Sangamonian interglaciation (Marine Isotope Stage (MIS) 5) through the Last Glacial Maximum (LGM, MIS 2). However, the continued presence of western camel through the LGM is at odds with its ecological preferences as inferred from more southerly parts of the continent. Here we report 43 new radiocarbon dates on 34 western camel fossils from Alaska and Yukon, including specimens that have been dated previously. To minimize exogenous carbon contamination, we utilized either ultrafiltered collagen or single amino acid (hydroxyproline) methodologies in conducting the analyses. All samples, including previously reported specimens with finite ages, yielded ages that were either non-finite or close to the effective limit of radiocarbon dating. These results indicate that dates implying local presence of western camels in Alaska and Yukon during full-glacial conditions of MIS 2 are erroneous by as much as several tens of millennia, probably because of carbon contamination from glue or varnish used in fossil preparation and conservation. The revised radiocarbon chronology, together with other evidence, indicates that western camels were only able to occupy eastern Beringia only during Pleistocene interglaciations such as MIS 5, when forests and shrublands became the dominant regional biomes. The subsequent transition to cold, arid full-glacial conditions during the early Wisconsinan glaciation (MIS 4) around 75 000 years ago created unfavorable environmental conditions, eliminated browse, and led to their local extirpation in eastern Beringia. After their complete population loss in the Arctic and Subarctic, the range of

  6. Experiments to determine the efficiency of two standard decontamination procedures for radiocarbon samples

    International Nuclear Information System (INIS)

    Currie, D.R.

    1980-02-01

    Laboratory tests were made to decontaminate radiocarbon samples containing known amounts of contamination. Results for both acid-alkali treatment and acid hydrolysis indicate that decontamination is not 100% efficient

  7. Report on Radiocarbon Analysis of Surface Sediments from the Fore-Arc Basin of Nankai Trough

    National Research Council Canada - National Science Library

    Pohlman, John

    2004-01-01

    .... Radiocarbon analysis of the total organic carbon (TOC) and total inorganic carbon (TIC) on 30 sediment samples from two multicores and six piston cores was performed to investigate the fate of methane carbon in sediment of the Nankal Trough...

  8. Contribution of sorption, DOC transport and microbial interactions to the 14C age of a soil organic carbon profile: Insights from a calibrated process model

    NARCIS (Netherlands)

    Ahrens, B.; Braakhekke, M.C.; Guggenberger, G.; Schrumpf, M.; Reichstein, M.

    2015-01-01

    Profiles of soil organic carbon (SOC) are often characterized by a steep increase of 14C age with depth, often leading to subsoil 14C ages of more than 1000 years. These observations have generally been reproduced in SOC models by introducing a SOC pool that decomposes on the time-scale of

  9. Contribution of sorption, DOC transport and microbial interactions to the 14C age of a soil organic carbon profile : Insights from a calibrated process model

    NARCIS (Netherlands)

    Ahrens, Bernhard; Braakhekke, M.C.|info:eu-repo/dai/nl/343063689; Guggenberger, Georg; Schrumpf, Marion; Reichstein, Markus

    2015-01-01

    Profiles of soil organic carbon (SOC) are often characterized by a steep increase of 14C age with depth, often leading to subsoil 14C ages of more than 1000 years. These observations have generally been reproduced in SOC models by introducing a SOC pool that decomposes on the time-scale of

  10. Predicting decadal trends and transient responses of radiocarbon storage and fluxes in a temperate forest soil

    OpenAIRE

    Sierra, C. A.; Trumbore, S. E.; Davidson, E. A.; Frey, S. D.; Savage, K. E.; Hopkins, F. M.

    2012-01-01

    Representing the response of soil carbon dynamics to global environmental change requires the incorporation of multiple tools in the development of predictive models. An important tool to construct and test models is the incorporation of bomb radiocarbon in soil organic matter during the past decades. In this manuscript, we combined radiocarbon data and a previously developed empirical model to explore decade-scale soil carbon dyn...

  11. New radiocarbon measurement methods in the Hertelendi Laboratory, Hungary

    Science.gov (United States)

    Janovics, Róbert; Major, István; Rinyu, László; Veres, Mihály; Molnár, Mihály

    2013-04-01

    In this paper we present two very different and novel methods for C-14 measurement from dissolved inorganic carbonate (DIC) of water samples. A new LSC sample preparation method for liquid scintillation C-14 measurements was implemented in the ATOMKI. The first method uses direct absorption into a special absorbent (Carbosorb E®) and a following liquid scintillation measurement. Typical sample size is 20-40 litre of water. The developed CO2 absorption method is fast, and simple. The C-14 activities is measured by an ultra low background LSC (TRI-CARB 3170 TR/SL, Perkin Elmer) including quenching parameter (tSIE).The corresponding limit of C-14 dating is 31200 year. Several tests were executed with old borehole CO2 gas without significant content of C-14 and also performed on samples of known C-14 activities between 29 and 7000 pMC, previously measured by GPC. The combined uncertainty of the described determination is about 2 % in the case of recent carbon. It is a very cost-effective and easy to use method based on a novel and simple static absorption process for the CO2 extracted from groundwater. The other very sensitive method is based on accelerator mass spectrometry (AMS) using gas ion source. This method does not require graphite generation and a small volume of water sample (1-20mL) is enough for the radiocarbon measurement. The procedure is very similar to pre-treatment of carbonate contained sample preparation for stable isotope measurement with gasbench technique. We applied a MICADAS type accelerator mass spectrometry (AMS) with gas ion source for C-14 analysis. The radiocarbon content of water was sat free with phosphoric acid and then the headspace gas was rinsed vials. The whole measurement needs only 20 min of each sample. The precision of measurement is better than 1% for modern samples. The preparation is vastly reduced compared to the other AMS methods and principally allows fully automated measurements of groundwater samples with an auto

  12. Radiocarbon Mass Balance for a Magnox Nuclear Power Station

    International Nuclear Information System (INIS)

    Metcalfe, M.P.; Mills, R.W.

    2016-01-01

    Nuclear power generation in the United Kingdom is based principally on graphite-moderated gas-cooled reactors. The mass of irradiated graphite associated with these reactors, including material from associated experimental, prototype and production reactors, exceeds 96,000 tonnes. One of the principal long-lived radionuclides produced during graphite irradiation is radiocarbon (C-14), which has a half-life of 5730 ± 40 years. Decommissioning and graphite waste management strategies must take account of this radionuclide. In order to identify appropriate options for addressing the potential hazard of C-14, it is important that the production processes are understood and the distributions and concentrations of C-14 are characterised. In fact, C-14 precursors and their activation processes are well-known. However, there is ongoing debate over the relative importance of different C-14 precursors, which will determine the location of C-14 within graphite components and hence its mobility/response to treatment. A generally held misconception concerning C-14 in irradiated graphite is that generic statements can be made about its precursors and their location. C-14 location and activities will depend upon the composition of the original manufactured graphite (raw materials, impurities), the chemical environment of the graphite during service and the irradiation history of the graphite. So, while there may be some similarities across, for example, carbon dioxide cooled graphite moderated designs (Magnox, AGR, UNGG), any informed assessment of a core’s C-14 inventory would require more-precise characterisation. The analysis presented here focuses on a UK Magnox reactor core, Reactor 1 at Wylfa Nuclear Power Station. The objective of the analysis is to present a full C-14 mass balance over a selected period of operation for which there are accurate C-14 discharge records. The analysis presented here provides the first assessment of the principal C-14 activation pathways

  13. Radionuclide calibrators performance evaluation

    International Nuclear Information System (INIS)

    Mora Ramirez, E.; Zeledon Fonseca, P.; Jimenez Cordero, M.

    2008-01-01

    Radionuclide calibrators are used to estimate accurately activity prior to administration to a patient, so it is very important that this equipment meets its performance requirements. The purpose of this paper is to compare the commercially available 'Calicheck' (Calcorp. Inc), used to assess linearity, versus the well-known source decay method, and also to show our results after performing several recommended quality control tests. The parameters that we wanted to evaluate were carried on using the Capintec CRC-15R and CRC-15 β radionuclide calibrators. The evaluated tests were: high voltage, display, zero adjust, background, reproducibility, source constancy, accuracy, precision and linearity. The first six tests were evaluated on the daily practice, here we analyzed the 2007 recorded data; and the last three were evaluated once a year. During the daily evaluation both calibrators performance were satisfactory comparing with the manufacture's requirements. The accuracy test show result within the ± 10% allowed for a field instrument. Precision performance is within the ± 1 % allowed. On the other hand, the linearity test shows that using the source decay method the relative coefficient is 0.9998, for both equipment and using the Calicheck the relative coefficient is 0.997. However, looking the percentage of error, during the 'Calicheck' test, its range goes from 0.0 % up to -25.35%, and using the source decay method, the range goes from 0.0 % up to -31.05 %, taking into account both instruments. Checking the 'Calicheck' results we can see that the results varying randomly, but using the source decay method the percentage of error increase as the source activity decrease. We conclude that both devices meet its manufactures requirements, in the case of the linearity using the decay method, decreasing the activity source, increasing the percentage of error, this may happen because of the equipment age. (author)

  14. Coastal rainforest boundary dynamics during the late Holocene in monsoonal Australia: evidence from radiocarbon dates of abandoned nests of Orange-footed Scrubfowl

    Energy Technology Data Exchange (ETDEWEB)

    Bowman, D M.J.S.; Panton, W J [Parks and Wildlife Commission of the Northern Territory, Darwin, NT (Australia); Head, J [Australian National Univ, Canberra, ACT (Australia). Quaternary Dating Research Centre

    1998-12-31

    The late Holocene history of monsoon rainforest retreat was explored by radiocarbon dating abandoned Orange-footed Scrubfowl (Megapodius reinwardt Gaimard) nests in coastal savannas in the Northern Territory of Australia. Previous work has demonstrated that in savanna environments this rainforest bird can not build nor maintain the large heaps of soil and leaf litter that it uses for nests. Excavations of two earthen mounds in a savanna habitat verified that they were abandoned Scrubfowl nests, and not Aboriginal middens, given their lack of stratigraphy, non-sequential dating of charcoal in a vertical profile, and absence of archaeological material. Radiocarbon dates of material taken from the surface of abandoned nests were determined for three sites on the coast of the Northern Territory. These analyses revealed that for all three sites, rainforests have contracted within the last 1800 years BP. On Elcho Island an abandoned nest was found to contain the land snail Xanthomelon spheroidea Le Guillou (known to prefer rainforest habitat) with a modern radiocarbon age, suggesting recent contraction of rainforest. The results of this study further weaken the theory that Aboriginal burning was a major cause of rain forest fragmentation in the monsoon tropics, and possibly elsewhere in Australia.

  15. Coastal rainforest boundary dynamics during the late Holocene in monsoonal Australia: evidence from radiocarbon dates of abandoned nests of Orange-footed Scrubfowl

    Energy Technology Data Exchange (ETDEWEB)

    Bowman, D.M.J.S.; Panton, W.J. [Parks and Wildlife Commission of the Northern Territory, Darwin, NT (Australia); Head, J. [Australian National Univ, Canberra, ACT (Australia). Quaternary Dating Research Centre

    1997-12-31

    The late Holocene history of monsoon rainforest retreat was explored by radiocarbon dating abandoned Orange-footed Scrubfowl (Megapodius reinwardt Gaimard) nests in coastal savannas in the Northern Territory of Australia. Previous work has demonstrated that in savanna environments this rainforest bird can not build nor maintain the large heaps of soil and leaf litter that it uses for nests. Excavations of two earthen mounds in a savanna habitat verified that they were abandoned Scrubfowl nests, and not Aboriginal middens, given their lack of stratigraphy, non-sequential dating of charcoal in a vertical profile, and absence of archaeological material. Radiocarbon dates of material taken from the surface of abandoned nests were determined for three sites on the coast of the Northern Territory. These analyses revealed that for all three sites, rainforests have contracted within the last 1800 years BP. On Elcho Island an abandoned nest was found to contain the land snail Xanthomelon spheroidea Le Guillou (known to prefer rainforest habitat) with a modern radiocarbon age, suggesting recent contraction of rainforest. The results of this study further weaken the theory that Aboriginal burning was a major cause of rain forest fragmentation in the monsoon tropics, and possibly elsewhere in Australia.

  16. Radiocarbon dating uncertainty and the reliability of the PEWMA method of time-series analysis for research on long-term human-environment interaction.

    Science.gov (United States)

    Carleton, W Christopher; Campbell, David; Collard, Mark

    2018-01-01

    Statistical time-series analysis has the potential to improve our understanding of human-environment interaction in deep time. However, radiocarbon dating-the most common chronometric technique in archaeological and palaeoenvironmental research-creates challenges for established statistical methods. The methods assume that observations in a time-series are precisely dated, but this assumption is often violated when calibrated radiocarbon dates are used because they usually have highly irregular uncertainties. As a result, it is unclear whether the methods can be reliably used on radiocarbon-dated time-series. With this in mind, we conducted a large simulation study to investigate the impact of chronological uncertainty on a potentially useful time-series method. The method is a type of regression involving a prediction algorithm called the Poisson Exponentially Weighted Moving Average (PEMWA). It is designed for use with count time-series data, which makes it applicable to a wide range of questions about human-environment interaction in deep time. Our simulations suggest that the PEWMA method can often correctly identify relationships between time-series despite chronological uncertainty. When two time-series are correlated with a coefficient of 0.25, the method is able to identify that relationship correctly 20-30% of the time, providing the time-series contain low noise levels. With correlations of around 0.5, it is capable of correctly identifying correlations despite chronological uncertainty more than 90% of the time. While further testing is desirable, these findings indicate that the method can be used to test hypotheses about long-term human-environment interaction with a reasonable degree of confidence.

  17. Hard Water or High Ages?

    DEFF Research Database (Denmark)

    Philippsen, Bente

    2008-01-01

    to spurious, too high ages of samples from freshwater systems. The possibility of the hardwater effect in food crusts on pottery is investigated for two sites of the Late Mesolithic Ertebølle culture. The first radiocarbon dates from the food crusts from these sites were surprisingly high. I will examine...

  18. Mechanics of log calibration

    International Nuclear Information System (INIS)

    Waller, W.C.; Cram, M.E.; Hall, J.E.

    1975-01-01

    For any measurement to have meaning, it must be related to generally accepted standard units by a valid and specified system of comparison. To calibrate well-logging tools, sensing systems are designed which produce consistent and repeatable indications over the range for which the tool was intended. The basics of calibration theory, procedures, and calibration record presentations are reviewed. Calibrations for induction, electrical, radioactivity, and sonic logging tools will be discussed. The authors' intent is to provide an understanding of the sources of errors, of the way errors are minimized in the calibration process, and of the significance of changes in recorded calibration data

  19. Age

    Science.gov (United States)

    ... adults? How can you reduce anesthesia risks in older patients? Age Age may bring wisdom but it also brings ... Ask your physician to conduct a pre-surgery cognitive test — an assessment of your mental function. The physician can use the results as a ...

  20. Anomalous elevated radiocarbon measurements of PM2.5

    International Nuclear Information System (INIS)

    Buchholz, Bruce A.; Fallon, Stewart J.; Zermeño, Paula; Bench, Graham; Schichtel, Bret A.

    2013-01-01

    Two-component models are often used to determine the contributions made by fossil fuel and natural sources of carbon in airborne particulate matter (PM). The models reduce thousands of actual sources to two end members based on isotopic signature. Combustion of fossil fuels produces PM free of carbon-14 ( 14 C). Wood or charcoal smoke, restaurant fryer emissions, and natural emissions from plants produce PM with the contemporary concentration of 14 C approximately 1.2 × 10 −1214 C/C. Such data can be used to estimate the relative contributions of fossil fuels and biogenic aerosols to the total aerosol loading and radiocarbon analysis is becoming a popular source apportionment method. Emissions from incinerators combusting medical or biological wastes containing tracer 14 C can skew the 14 C/C ratio of PM, however, so critical analysis of sampling sites for possible sources of elevated PM needs to be completed prior to embarking on sampling campaigns. Results are presented for two ambient monitoring sites in different areas of the United States where 14 C contamination is apparent. Our experience suggests that such contamination is uncommon but is also not rare (∼10%) for PM sampling sites.

  1. Titan's Radioactive Haze : Production and Fate of Radiocarbon On Titan

    Science.gov (United States)

    Lorenz, R. D.; Jull, A. J. T.; Swindle, T. D.; Lunine, J. I.

    Just as cosmic rays interact with nitrogen atoms in the atmosphere of Earth to gener- ate radiocarbon (14C), the same process should occur in Titan`s nitrogen-rich atmo- sphere. Titan`s atmosphere is thick enough that cosmic ray flux, rather than nitrogen column depth, limits the production of 14 C. Absence of a strong magnetic field and the increased distance from the sun suggest production rates of 9 atom/cm2/s, approx- imately 4 times higher than Earth. On Earth the carbon is rapidly oxidised into CO2. The fate and detectability of 14C on Titan depends on the chemical species into which it is incorporated in Titan's reducing atmosphere : as methane it would be hopelessly diluted even in only the atmosphere (ignoring the other, much more massive carbon reservoirs likely to be present on Titan, like hydrocarbon lakes.) However, in the more likely case that the 14C attaches to the haze that rains out onto the surface (as tholin, HCN or acetylene and their polymers - a much smaller carbon reservoir) , haze in the atmosphere or recently deposited on the surface would therefore be quite intrinsically radioactive. Such activity may modify the haze electrical charging and hence its coag- ulation. Measurements with compact instrumentation on future in-situ missions could place useful constraints on the mass deposition rates of photochemical material on the surface and identify locations where surface deposits of such material are `freshest`.

  2. Stromatolite laminae (Lagoa Vermelha, Brasil) as archives for reservoir age changes

    Science.gov (United States)

    Bruggmann, Sylvie; Vasconcelos, Crisogono; Hajdas, Irka

    2016-04-01

    .L. Edwards, M. Friedrich, P.M. Grootes, T.P. Guilderson, H. Haflidason, I. Hajdas, C. Hatté, T.J. Heaton, D.L. Hoffmann, A.G. Hogg, K.A. Hughen, K.F. Kaiser, B. Kromer, S.W. Manning, M. Niu, R.W. Reimer, D.A. Richards, E.M. Scott, J. R. Southon, R.A. Staff, C.S.M. Turney, J. van der Plicht (2013). IntCal13 and Marine13 radiocarbon age calibration curves 0-50,000 years cal BP. Radiocarbon 55(4):1869-1887. [3] A.G. Hogg, Q. Hua, P.G. Blackwell, M. Niu, C.E. Buck, T.P. Guilderson, T.J. Heaton, J.G. Palmer, P.J. Reimer, R.W. Reimer, C.S.M. Turney, S.R.H. Zimmerman (2013). Shcal13 southern hemisphere calibration, 0-50,000 years cal BP. Radiocarbon, 55(2):1-15.

  3. Radiocarbon dating of the Peruvian Chachapoya/Inca site at the Laguna de los Condores

    International Nuclear Information System (INIS)

    Wild, Eva Maria; Guillen, Sonia; Kutschera, Walter; Seidler, Horst; Steier, Peter

    2007-01-01

    In 1997 a new archaeological site was discovered in the Peruvian tropical rain forest. The site is located in an area which has been occupied by the Chachapoya, a pre-Incan people, from about 800AD on. The site comprises a large funerary place with several mausoleums built in the cliffs next to the Laguna de los Condores. More than 200 human mummies and funerary bone-bundles together with numerous grave artefacts have been found there. Although the site has been ascribed to the Chachapoya, the mummification method used is very similar to the one applied by the Inca. As part of an ongoing multidisciplinary project to explore the history of this site and of the Chachapoya people, twenty-seven (27) 14 C-AMS age determinations were performed. Samples, bones and textile wrappings as well as samples from a funerary bone bundle plus associated grave artefacts were dated. The 14 C data show that the site originates from the Chachapoya pre-Inca period and that in addition, it was used as a funerary place during the subsequent Inca occupation era. The radiocarbon results indicate that the Chachapoya may have changed their burial tradition due to the colonization by the Inca

  4. New radiocarbon data to study the history of roman and medieval Florence

    International Nuclear Information System (INIS)

    Arnoldus-Huyzendveld, A.; Fedi, M.E.; Cantini, F.; Bruttini, J.; Cartocci, A.; Calabrisotto, C. Scire

    2010-01-01

    Florence is a town worldwide known for its Renaissance masterpieces. It is often forgotten that it was founded during Roman times and remained a small village until the end of the early Middle Ages, practically confined within the ancient Roman boundaries. Since 2003, an extended archaeological research executed by the University of Sienna has studied the most ancient layers in the centre of Florence with the aim to enhance both the archaeological and paleo-environmental reconstruction of this area. One of the peculiarities of these excavations is that the early medieval layers were poor in datable ceramics, thus charcoals were sampled from different stratigraphic layers in order to contribute to the dating. Several data have already been published; here we focus on the excavation site of Palazzo Vecchio, now the seat of the municipality of Florence. This area is located close to the Arno river, along the eastern margin of the slightly elevated height upon which the Roman town was founded; actually, in the layers beneath the surface, the Roman theatre is still preserved. Radiocarbon dating of charcoals was performed in the LABEC laboratory in Florence, at the AMS beam line of the AMS-IBA 3 MV Tandetron accelerator. Comparison of these new data with the former ones and with the archaeological and geological data adds new information especially on natural phenomena like floods and on the human occupation of this area in the past.

  5. Sun, Ocean, Nuclear Bombs, and Fossil Fuels: Radiocarbon Variations and Implications for High-Resolution Dating

    Science.gov (United States)

    Dutta, Koushik

    2016-06-01

    Radiocarbon, or 14C, is a radiometric dating method ideally suited for providing a chronological framework in archaeology and geosciences for timescales spanning the last 50,000 years. 14C is easily detectable in most common natural organic materials and has a half-life (5,730±40 years) relevant to these timescales. 14C produced from large-scale detonations of nuclear bombs between the 1950s and the early 1960s can be used for dating modern organic materials formed after the 1950s. Often these studies demand high-resolution chronology to resolve ages within a few decades to less than a few years. Despite developments in modern, high-precision 14C analytical methods, the applicability of 14C in high-resolution chronology is limited by short-term variations in atmospheric 14C in the past. This article reviews the roles of the principal natural drivers (e.g., solar magnetic activity and ocean circulation) and the anthropogenic perturbations (e.g., fossil fuel CO2 and 14C from nuclear and thermonuclear bombs) that are responsible for short-term 14C variations in the environment. Methods and challenges of high-resolution 14C dating are discussed.

  6. Radiocarbon dating by accelerator mass spectrometry: some recent results and applications

    International Nuclear Information System (INIS)

    Hedges, R.E.M.

    1987-01-01

    14 C differs from other nuclides measured by accelerator mass spectrometry (AMS) in that an extensive database of dates already exists. AMS dates should therefore have comparable accuracy, and the measurement of isotopic ratios to better than 1%, which was an important technical goal, has been reached. The main advantage of being able to date samples 1000 times smaller than previously lies in the extra selectivity that can be employed. This is reflected in the results and applications. Selection can apply at several levels; from objects that formerly contained too little carbon, to the choice of archaeological material, to the extraction of specific chemical compounds from a complex environmental sample. This is particularly useful in removing uncertainty regarding the validity of a date, since a given sample may comprise carbon atoms from different sources each with their own 14 C 'age'. Examples from archaeological and environmental research illustrating these points are given. 14 C dating by AMS differs from conventional radiocarbon dating by having the potential to measure much lower levels of 14 C, and therefore should double the time span of the method. This potential has not yet been realized because of sample contamination effects, and work in progress to reduce these is described. (author)

  7. A novel approach to process carbonate samples for radiocarbon measurements with helium carrier gas

    Energy Technology Data Exchange (ETDEWEB)

    Wacker, L., E-mail: wacker@phys.ethz.ch [Laboratory of Ion Beam Physics, ETH Zurich, 8093 Zurich (Switzerland); Fueloep, R.-H. [Institute of Geology and Mineralogy, University of Cologne, 50674 Cologne (Germany); Hajdas, I. [Laboratory of Ion Beam Physics, ETH Zurich, 8093 Zurich (Switzerland); Molnar, M. [Laboratory of Ion Beam Physics, ETH Zurich, 8093 Zurich (Switzerland); Institute of Nuclear Research, Hungarian Academy of Sciences, 4026 Debrecen (Hungary); Rethemeyer, J. [Institute of Geology and Mineralogy, University of Cologne, 50674 Cologne (Germany)

    2013-01-15

    Most laboratories prepare carbonates samples for radiocarbon analysis by acid decomposition in evacuated glass tubes and subsequent reduction of the evolved CO{sub 2} to graphite in self-made reduction manifolds. This process is time consuming and labor intensive. In this work, we have tested a new approach for the preparation of carbonate samples, where any high-vacuum system is avoided and helium is used as a carrier gas. The liberation of CO{sub 2} from carbonates with phosphoric acid is performed in a similar way as it is often done in stable isotope ratio mass spectrometry where CO{sub 2} is released with acid in septum sealed tube under helium atmosphere. The formed CO{sub 2} is later flushed in a helium flow by means of a double-walled needle mounted from the tubes to the zeolite trap of the automated graphitization equipment (AGE). It essentially replaces the elemental analyzer normally used for the combustion of organic samples. The process can be fully automated from sampling the released CO{sub 2} in the septum-sealed tubes with a commercially available auto-sampler to the graphitization with the automated graphitization. The new method yields in low sample blanks of about 50000 years. Results of processed reference materials (IAEA-C2, FIRI-C) are in agreement with their consensus values.

  8. Thermoluminescence dates for the Lake Mungo aboriginal fireplaces and the implications for radiocarbon dating

    International Nuclear Information System (INIS)

    Bell, W.T.

    1991-01-01

    During the Quaternary period in Australia large areas of western New South Wales and northern Victoria were covered by hundreds of lakes, both large and small. Nearly all are dry today but some may still be recognized by the long low dunes that follow the eastern shorelines. Many traces of early human occupation have been found along the shorelines of nearly all the major lakes and some of the best exposures have occurred on the lunette along the eastern shore of Lake Mungo. This lunette, has suffered massive erosion in recent times and this has uncovered the sites of many ancient fireplaces. Charcoal from some of these fireplaces has been dated by Barbetti and Polach (1973) using the radiocarbon method and the ages place the lakeside dwellers at Mungo in an area of Australian prehistory around 30 000 years ago. The baked sediment from below the fireplaces appears to have been heated to a temperature in excess of 400 o C according to archaeomagnetic studies carried out by Barbetti (1973) and this indicated that the fireplaces might lend themselves to the technique of thermoluminescence (TL) dating. The results of the TL dating programme are described elsewhere. (author)

  9. Thermoluminescence dates for the Lake Mungo aboriginal fireplaces and the implications for radiocarbon dating

    Energy Technology Data Exchange (ETDEWEB)

    Bell, W T [Australian National Univ., Canberra (Australia)

    1991-02-01

    During the Quaternary period in Australia large areas of western New South Wales and northern Victoria were covered by hundreds of lakes, both large and small. Nearly all are dry today but some may still be recognized by the long low dunes that follow the eastern shorelines. Many traces of early human occupation have been found along the shorelines of nearly all the major lakes and some of the best exposures have occurred on the lunette along the eastern shore of Lake Mungo. This lunette, has suffered massive erosion in recent times and this has uncovered the sites of many ancient fireplaces. Charcoal from some of these fireplaces has been dated by Barbetti and Polach (1973) using the radiocarbon method and the ages place the lakeside dwellers at Mungo in an area of Australian prehistory around 30 000 years ago. The baked sediment from below the fireplaces appears to have been heated to a temperature in excess of 400{sup o}C according to archaeomagnetic studies carried out by Barbetti (1973) and this indicated that the fireplaces might lend themselves to the technique of thermoluminescence (TL) dating. The results of the TL dating programme are described elsewhere. (author).

  10. Dead wood biomass and turnover time, measured by radiocarbon, along a subalpine elevation gradient.

    Science.gov (United States)

    Kueppers, Lara M; Southon, John; Baer, Paul; Harte, John

    2004-12-01

    Dead wood biomass can be a substantial fraction of stored carbon in forest ecosystems, and coarse woody debris (CWD) decay rates may be sensitive to climate warming. We used an elevation gradient in Colorado Rocky Mountain subalpine forest to examine climate and species effects on dead wood biomass, and on CWD decay rate. Using a new radiocarbon approach, we determined that the turnover time of lodgepole pine CWD (340+/-130 years) was roughly half as long in a site with 2.5-3 degrees C warmer air temperature, as that of pine (630+/-400 years) or Engelmann spruce CWD (800+/-960 and 650+/-410 years) in cooler sites. Across all sites and both species, CWD age ranged from 2 to 600 years, and turnover time was 580+/-180 years. Total standing and fallen dead wood biomass ranged from 4.7+/-0.2 to 54+/-1 Mg ha(-1), and from 2.8 to 60% of aboveground live tree biomass. Dead wood biomass increased 75 kg ha(-1) per meter gain in elevation and decreased 13 Mg ha(-1) for every degree C increase in mean air temperature. Differences in biomass and decay rates along the elevation gradient suggest that climate warming will lead to a loss of dead wood carbon from subalpine forest.

  11. Synthesis Polarimetry Calibration

    Science.gov (United States)

    Moellenbrock, George

    2017-10-01

    Synthesis instrumental polarization calibration fundamentals for both linear (ALMA) and circular (EVLA) feed bases are reviewed, with special attention to the calibration heuristics supported in CASA. Practical problems affecting modern instruments are also discussed.

  12. Aging

    International Nuclear Information System (INIS)

    Sasaki, Hideo; Kodama, Kazunori; Yamada, Michiko

    1991-01-01

    The hypothesis that exposure to ionizing radiation accelerates the aging process has been actively investigated at ABCC-RERF since 1958, when longitudinal cohort studies of the Adult Health Study (AHS) and the Life Span Study (LSS) were initiated. In their 1975 overall review of aging studies related to the atomic bomb (A-bomb) survivors, Finch and Beebe concluded that while most studies had shown no correlation between aging and radiation exposure, they had not involved the large numbers of subjects required to provide strong evidence for or against the hypothesis. Extending LSS mortality data up to 1978 did not alter the earlier conclusion that any observed life-shortening was associated primarily with cancer induction rather than with any nonspecific cause. The results of aging studies conducted during the intervening 15 years using data from the same populations are reviewed in the present paper. Using clinical, epidemiological, and laboratory techniques, a broad spectrum of aging parameters have been studied, such as postmortem morphological changes, tests of functional capacity, physical tests and measurements, laboratory tests, tissue changes, and morbidity. With respect to the aging process, the overall results have not been consistent and are generally thought to show no relation to radiation exposure. Although some preliminary results suggest a possible radiation-induced increase in atherosclerotic diseases and acceleration of aging in the T-cell-related immune system, further study is necessary to confirm these findings. In the future, applying the latest gerontological study techniques to data collected from subjects exposed 45 years ago to A-bomb radiation at relatively young ages will present a new body of data relevant to the study of late radiation effects. (author) 103 refs

  13. Bomb-curve radiocarbon measurement of recent biologic tissues and applications to wildlife forensics and stable isotope (paleo)ecology

    OpenAIRE

    Uno, Kevin T.; Quade, Jay; Fisher, Daniel C.; Wittemyer, George; Douglas-Hamilton, Iain; Andanje, Samuel; Omondi, Patrick; Litoroh, Moses; Cerling, Thure E.

    2013-01-01

    Above-ground thermonuclear weapons testing from 1952 through 1962 nearly doubled the concentration of radiocarbon (14C) in the atmosphere. As a result, organic material formed during or after this period may be radiocarbon-dated using the abrupt rise and steady fall of the atmospheric 14C concentration known as the bomb-curve. We test the accuracy of accelerator mass spectrometry radiocarbon dating of 29 herbivore and plant tissues collected on known dates between 1905 and 2008 in East Africa...

  14. Aging

    International Nuclear Information System (INIS)

    Finch, S.C.; Beebe, G.W.

    1975-01-01

    The hypothesis that ionizing radiation accelerates natural aging has been under investigation at the Atomic Bomb Casualty Commission since 1959. Postmortem observations of morphologic and chemical changes, tests of functional capacity, physical tests and measurements, clinical laboratory tests, tissue changes, morbidity, and mortality have all been examined by ABCC investigators interested in this hypothesis. These studies have been beset with conceptual difficulties centered on the definition and measurement of aging. An empirical approach early led to the calculation of an index of physiologic age as a linear combination of age-related tests of various organ systems. Most studies have been negative but have not involved the large numbers that might be required to provide strong evidence for or against the hypothesis. Mortality, however, has been examined on the basis of a large sample and over the period 1950-1972 had provided no support for the hypothesis of radiation-accelerated aging. Ionizing radiation dose, of course shorten human life, but its life-shortening effect appears to be the result of specific radiation-induced disease, especially neoplasms. The hypothesis is now much less attractive than it was 10-20 years ago but still has some value in stimulating research on aging. The experience of the A-bomb survivors provides an unusual opportunity for a definitive test of the hypothesis. (auth.)

  15. ORNL calibrations facility

    International Nuclear Information System (INIS)

    Berger, C.D.; Gupton, E.D.; Lane, B.H.; Miller, J.H.; Nichols, S.W.

    1982-08-01

    The ORNL Calibrations Facility is operated by the Instrumentation Group of the Industrial Safety and Applied Health Physics Division. Its primary purpose is to maintain radiation calibration standards for calibration of ORNL health physics instruments and personnel dosimeters. This report includes a discussion of the radioactive sources and ancillary equipment in use and a step-by-step procedure for calibration of those survey instruments and personnel dosimeters in routine use at ORNL

  16. Intracavity optogalvanic spectroscopy: Is there any evidence of a radiocarbon signal?

    International Nuclear Information System (INIS)

    Persson, Anders; Salehpour, Mehran

    2015-01-01

    In 2008, the first report of an ultrasensitive method for ro-vibrational spectrometry of radiocarbon dioxide was published. The method, called intracavity optogalvanic spectroscopy (ICOGS), claimed a sensitivity and limit-of-detection comparable to accelerator mass spectroscopy. ICOGS was claimed to utilize the isotope-dependent ro-vibrational absorption lines of carbon dioxide in the infrared spectrum. In order to facilitate unambiguous detection of radiocarbon, the sample was placed inside the cavity of a radiocarbon dioxide laser. This intracavity approach was claimed to increase the sensitivity by seven orders of magnitude compared with traditional optogalvanic methods. However, despite the methodical and thorough efforts of several research groups worldwide, these claims have not been possible to reproduce. Instead, we have previously reported serious deviations from the original results, where we found that ICOGS suffers from considerable problems with the stability and reproducibility of the optogalvanic signal, and that misinterpretations of these uncertainties likely are the explanation for the claimed sensitivity in the first reports. Having identified the stability and reproducibility of the detection as major concerns, we decided to improve the setup by with state-of-the-art plasma source technology. Deploying a custom-made stripline split-ring resonator optogalvanic detector, we have now investigated the applicability of ICOGS to radiocarbon detection even further. Measurements have been made with a wide range of parameters including different gas mixtures at various pressures and wavelengths. We have also conducted measurements with gas flowing through the sample cell to investigate the effect of plasma induced decomposition of the sample. Still, we have seen no indications of a significant radiocarbon signal in a concentration range between 0.29 Modern and 9.7 Modern, i.e., the range of interest to the radiocarbon community. Hence, our conclusions

  17. AMS radiocarbon analyses from Lake Baikal, Siberia: Challenges of dating sediments from a large, oligotrophic lake

    Science.gov (United States)

    Colman, Steven M.; Jones, Glenn A.; Rubin, M.; King, J.W.; Peck, J.A.; Orem, W.H.

    1996-01-01

    A suite of 146 new accelerator-mass spectrometer (AMS) radiocarbon ages provides the first reliable chronology for late Quaternary sediments in Lake Baikal. In this large, highly oligotrophic lake, biogenic and authigenic carbonate are absent, and plant macrofossils are extremely rare. Total organic carbon is therefore the primary material available for dating. Several problems are associated with the TOC ages. One is the mixture of carbon sources in TOC, not all of which are syndepositional in age. This problem manifests itself in apparent ages for the sediment surface that are greater than zero. However, because most of the organic carbon in Lake Baikal sediments is algal (autochthonous) in origin, this effect is limited to about 1000+500 years, which can be corrected, at least for young deposits. The other major problem with dating Lake Baikal sediments is the very low carbon contents of glacial-age deposits, which makes them extremely susceptible to contamination with modern carbon. This problem can be minimized by careful sampling and handling procedures. The ages show almost an order of magnitude difference in sediment-accumulation rates among different sedimentary environments in Lake Baikal, from about 0.04 mm/year on isolated banks such as Academician Ridge, to nearly 0.3 mm/year in the turbidite depositional areas beneath the deep basin floors, such as the Central Basin. The new AMS ages clearly indicate that the dramatic increase in diatom productivity in the lake, as evidenced by increases in biogenic silica and organic carbon, began about 13 ka, in contrast to previous estimates of 7 ka for the age of this transition. Holocene net sedimentation rates may be less than, equal to, or greater than those in the late Pleistocene, depending on the site. This variability reflects the balance between variable terrigenous sedimentation and increased biogenic sedimentation during interglaciations. The ages reported here, and the temporal and spatial variation in

  18. Radiocarbon measurements at LAC-UFF: Recent performance

    Energy Technology Data Exchange (ETDEWEB)

    Linares, Roberto, E-mail: rlinares@if.uff.br [Laboratório de Radiocarbono, Universidade Federal Fluminense, Av. Gal. Milton Tavares de Souza, s/n, Niterói 24230-346 (Brazil); Macario, Kita D. [Laboratório de Radiocarbono, Universidade Federal Fluminense, Av. Gal. Milton Tavares de Souza, s/n, Niterói 24230-346 (Brazil); Santos, Guaciara M. [Earth System Science, University of California, Irvine, B321 Croul Hall, Irvine, CA 92697-3100 (United States); Carvalho, Carla [Laboratório de Radiocarbono, Universidade Federal Fluminense, Av. Gal. Milton Tavares de Souza, s/n, Niterói 24230-346 (Brazil); Departamento de Geoquímica, Universidade Federal Fluminense, Outeiro São João Batista, s/n, Niterói 24020-141 (Brazil); Santos, Hellen C. dos; Gomes, Paulo R.S.; Castro, Maikel D.; Oliveira, Fabiana M.; Alves, Eduardo Q. [Laboratório de Radiocarbono, Universidade Federal Fluminense, Av. Gal. Milton Tavares de Souza, s/n, Niterói 24230-346 (Brazil)

    2015-10-15

    In 2012 a single stage accelerator mass spectrometer from NEC was installed at the Radiocarbon Laboratory of Universidade Federal Fluminense (LAC-UFF), Niterói, Brazil. Here, we present a status report of our facility. We discuss some modifications applied to our combustion protocol in an attempt to reduce our procedural blank, mostly to processed organic samples. Measurements of reference materials indicate low precision and accuracy that are partially related to beam optics through the acceleration tube. We observed that once the beam current intensity increases the measured {sup 13}C{sup +}/{sup 12}C{sup +} becomes erratic. Therefore, in order to maintain the AMS-δ{sup 13}C values within reasonable values, so that fractionation corrections using the spectrometer {sup 13}C{sup +}/{sup 12}C{sup +} values does not affect the final {sup 14}C results, we are forced to limit the {sup 12}C{sup −} beam intensity to ⩽30 μA. This requirement was confirmed during our accuracy tests, when measuring selected annual tree-rings wood samples from a Parana pine (Araucaria angustifolia) between 1927 and 1997 previously measured at the Keck Carbon Cycle AMS Facility (KCCAMS), at the University of California, Irvine (UCI). At the LAC-UFF tree-ring wood samples were processed and measured in 4 different batches during a period of about 5 months. The {sup 14}C results were later compared to the high-precision data obtained at KCCAMS/UCI and reached a good agreement. Recently a problem associated with graphitization yield were finally identified and new measurements with secondary standards are promising.

  19. Solar flares and radiocarbon abundance in the atmosphere of the Earth

    International Nuclear Information System (INIS)

    Metskhvarishvili, R.Ya.; Imedadze, T.Sh.; Tleugaliev, S.Kh.; Tsinamdzgvrishvili, T.Sh.; Tsereteli, S.L.

    1978-01-01

    The correlation between the radiocarbon ( 14 C) content in the atmosphere of the Earth and the solar activity is studied. Annual measurements of the 14 C content in the tree rings for the last 120 years have been made. Relations of the radiocarbon content in dendrochronologically dated tree rings and the Wolf numbers for the period from 1850 to 1940 are presented. The spectroscopic and Borg methods have been used to ascertain the periodicities in the radiocarbon series. It is shown that well-defined periods of approximately 11 and approximately 65 years are observed in the radiocarbon series. The former is associated with an 11-year and the latter with a secular cycle of the 14 C content in the earth atmosphere. To study the relation of the solar activity to the level of radiocarbon in the earth atmosphere a mutual correlation function was calculated for various values of the time lags of 14 C with respect to the processes on the Sun. It follows from the data obtained that a positive correlation takes place for time lags smaller than three years. The detected positive correlation has revealed that the effect of solar flares in the 11-year cycle is prevalent

  20. Predicting decadal trends and transient responses of radiocarbon storage and fluxes in a temperate forest soil

    Directory of Open Access Journals (Sweden)

    C. A. Sierra

    2012-08-01

    Full Text Available Representing the response of soil carbon dynamics to global environmental change requires the incorporation of multiple tools in the development of predictive models. An important tool to construct and test models is the incorporation of bomb radiocarbon in soil organic matter during the past decades. In this manuscript, we combined radiocarbon data and a previously developed empirical model to explore decade-scale soil carbon dynamics in a temperate forest ecosystem at the Harvard Forest, Massachusetts, USA. We evaluated the contribution of different soil C fractions to both total soil CO2 efflux and microbially respired C. We tested the performance of the model based on measurable soil organic matter fractions against a decade of radiocarbon measurements. The model was then challenged with radiocarbon measurements from a warming and N addition experiment to test multiple hypotheses about the different response of soil C fractions to the experimental manipulations. Our results showed that the empirical model satisfactorily predicts the trends of radiocarbon in litter, density fractions, and respired CO2 observed over a decade in the soils not subjected to manipulation. However, the model, modified with prescribed relationships for temperature and decomposition rates, predicted most but not all the observations from the field experiment where soil temperatures and nitrogen levels were increased, suggesting that a larger degree of complexity and mechanistic relations need to be added to the model to predict short-term responses and transient dynamics.

  1. Age Estimation in Forensic Sciences

    Science.gov (United States)

    Alkass, Kanar; Buchholz, Bruce A.; Ohtani, Susumu; Yamamoto, Toshiharu; Druid, Henrik; Spalding, Kirsty L.

    2010-01-01

    Age determination of unknown human bodies is important in the setting of a crime investigation or a mass disaster because the age at death, birth date, and year of death as well as gender can guide investigators to the correct identity among a large number of possible matches. Traditional morphological methods used by anthropologists to determine age are often imprecise, whereas chemical analysis of tooth dentin, such as aspartic acid racemization, has shown reproducible and more precise results. In this study, we analyzed teeth from Swedish individuals using both aspartic acid racemization and radiocarbon methodologies. The rationale behind using radiocarbon analysis is that aboveground testing of nuclear weapons during the cold war (1955–1963) caused an extreme increase in global levels of carbon-14 (14C), which has been carefully recorded over time. Forty-four teeth from 41 individuals were analyzed using aspartic acid racemization analysis of tooth crown dentin or radiocarbon analysis of enamel, and 10 of these were split and subjected to both radiocarbon and racemization analysis. Combined analysis showed that the two methods correlated well (R2 = 0.66, p Aspartic acid racemization also showed a good precision with an overall absolute error of 5.4 ± 4.2 years. Whereas radiocarbon analysis gives an estimated year of birth, racemization analysis indicates the chronological age of the individual at the time of death. We show how these methods in combination can also assist in the estimation of date of death of an unidentified victim. This strategy can be of significant assistance in forensic casework involving dead victim identification. PMID:19965905

  2. Radiocarbon dating study of ancient iron artifacts with accelerator mass spectrometry

    International Nuclear Information System (INIS)

    Igaki, Kenzo; Nakamura, Toshio; Hirasawa, Masahiro; Kato, Masako; Sano, Masamichi.

    1994-01-01

    In order to study the correlation between the highly resistive property against corrosion and the production method of the ancient iron artifacts, it is essentially necessary to determine the accurate ages of them. 14 C dating with accelerator mass spectrometry was applied to the two ancient artifacts, a Japanese sword of wrought iron with a production age ranged from the Kamakura to the Muromachi period, estimation based on the fabrication technique, and a planning adze of cast iron with no definite origin. The former was dated as 880±150 y.B.P., corresponding to the calendar age ranged from AD 1021 to AD 1263, and the latter as 1720±160 y.B.P. with the calendar age ranged from AD 119 to AD 457 and from AD 483 to AD 508. These calibrated 14 C ages for both iron artifacts are consistent with the relevant ages conjectured by historical considerations. (author)

  3. Demography of the Early Neolithic Population in Central Balkans: Population Dynamics Reconstruction Using Summed Radiocarbon Probability Distributions.

    Directory of Open Access Journals (Sweden)

    Marko Porčić

    Full Text Available The Central Balkans region is of great importance for understanding the spread of the Neolithic in Europe but the Early Neolithic population dynamics of the region is unknown. In this study we apply the method of summed calibrated probability distributions to a set of published radiocarbon dates from the Republic of Serbia in order to reconstruct population dynamics in the Early Neolithic in this part of the Central Balkans. The results indicate that there was a significant population growth after ~6200 calBC, when the Neolithic was introduced into the region, followed by a bust at the end of the Early Neolithic phase (~5400 calBC. These results are broadly consistent with the predictions of the Neolithic Demographic Transition theory and the patterns of population booms and busts detected in other regions of Europe. These results suggest that the cultural process that underlies the patterns observed in Central and Western Europe was also in operation in the Central Balkan Neolithic and that the population increase component of this process can be considered as an important factor for the spread of the Neolithic as envisioned in the demic diffusion hypothesis.

  4. Calibration of cosmogenic 3He and 10Be production rates in the High Tropics

    Science.gov (United States)

    Blard, Pierre-Henri; Martin, Léo; Lavé, Jérôme; Charreau, Julien; Condom, Thomas; Lupker, Maarten; Braucher, Régis; Bourlès, Didier

    2014-05-01

    It is critical to refine both the accuracy and the precision of the in situ cosmogenic dating tool, especially for establishing reliable glacial chronologies that can be compared to other paleoclimatic records. Recent cross-calibrations of cosmogenic 3He in pyroxene and 10Be in quartz [1, 2] showed that, both at low (1300 m) and high elevation (4850 m), the 3He/10Be production ratio was probably ~40% higher than the value of ~23 initially defined in the 90's. This recent update is consistent with the last independent determinations of the sea level high latitude production rates of 10Be and 3He, that are about 4 and 125 at.g-1.yr-1, respectively [e.g. 3, 4]. However, major questions remain about these production rates at high elevation, notably because existing calibration sites for both 3He and 10Be are scarce above 2000 m. It is thus crucial to produce new high precision calibration data at high elevation. Here we report cosmogenic 10Be data from boulders sampled on a glacial fan located at 3800 m in the Central Altiplano (Bolivia), whose age is independently constrained by stratigraphic correlations and radiocarbon dating at ca. 16 ka. These data can be used to calibrate the production rate of 10Be at high elevation, in the Tropics. After scaling to sea level and high latitude, these data yield a sea level high latitude P10 ranging from 3.8 to 4.2 at.g-1.yr-1, depending on the used scaling scheme. These new calibration data are in good agreement with recent absolute and cross-calibration of 3He in pyroxenes and 10Be in quartz, from dacitic moraines located at 4850 m in the Southern Altiplano (22° S, Tropical Andes) [2,5]. The so-obtained 3He/10Be production ratio of 33.3±0.9 (1σ) combined with an absolute 3He production rate locally calibrated in the Central Altiplano, at 3800 m, indeed yielded a sea level high latitude P10 ranging from 3.7±0.2 to 4.1±0.2 at.g-1.yr-1, depending on the scaling scheme [2,5]. These values are also consistent with the 10Be

  5. Combined dendrochronological and radiocarbon dating of six Russian icons from the 15th-17th centuries

    Science.gov (United States)

    Dolgikh, A. V.; Matskovsky, V. V.; Voronin, K. V.; Solomina, O. N.

    2017-06-01

    The results of dendrochronological and radiocarbon dating by means of accelerator mass spectrometry (AMS) of six medieval icons, originating from northern European Russia and painted on wooden panels made from Scots pine, dated to the 15th to 17th centuries are presented. The panels of each icon were studied using dendrochronology. Five to six AMS dates were obtained for four icons. Although five icons were dendro-dated successfully, one failed to be reliably cross-dated with the existing master tree-ring chronologies and it was dated by radiocarbon wiggle-matching. Dendrochronological dating and wiggle-matching of radiocarbon dates allowed us to determine the narrow chronological intervals of icon creation.

  6. Simulation of influence of some climatic factors on radiocarbon concentration in the Earth atmosphere

    International Nuclear Information System (INIS)

    Akhmetkereev, S.Kh.; Dergachev, V.A.

    1981-01-01

    The effect of different climatic factors on radiocarbon concentration in the Earth atmosphere is analyzed by modelling the exchange radiocarbon system. It is supposed that the exchange system consists of four reservoirs: long-lived surface vegetation and its remnants, the atmosphere, surface layer of the World ocean. It is shown that the variations of the ocean temperature and the variations in CO 2 amount in the atmosphere connected with it do not affect the atmosphere radiocarbon concentration. Variations in the square of sea ice on the time scale of >=1000 years could bring about variations in the 14 C concentration with the amplitude up to 1%. 14 C concentration in the atmosphere in the icing maximum 18 thousands of years ago was 7% higher than present concentration [ru

  7. Radiocarbon dating and 13 C/12 C ratio of soils under tropical and subtropical climates

    International Nuclear Information System (INIS)

    Valencia, Edwin P.E.

    1993-01-01

    It was used an association radiocarbon dates with the carbon isotopic composition of soil organic matter, where 14 C dating gives elements of chronology, and δ 13 C is used as indicator of the vegetation types in the environment. The total soil organic matter was dried, floated and sieved. The humin fraction was extracted from the 0,250 mm fraction. Radiocarbon datings were performed by a liquid scintillation method. The carbon of the soil organic matter and humin fraction are transformed into benzene, that was analyzed in low level liquid scintillation spectrometer. Based on results of carbon isotope analysis and Radiocarbon dating of soil samples of Londrina, Piracicaba and Altamira, it is concluded that probable changes of vegetation and climate occurred in the South and Southeast regions of Brazil in the mid-Holocene. (author). 81 refs., 16 figs., 7 tabs

  8. Radiocarbon and stable isotopes in Palmyra corals during the past century

    Science.gov (United States)

    Druffel-Rodriguez, Kevin C.; Vetter, Desiree; Griffin, Sheila; Druffel, Ellen R. M.; Dunbar, Robert B.; Mucciarone, David A.; Ziolkowski, Lori A.; Sanchez-Cabeza, Joan-Albert

    2012-04-01

    Annual samples from two Palmyra Atoll corals (Porites lutea) that lived during the past 110 years were analyzed for radiocarbon (Δ14C) and δ18O. The Δ14C values decreased 7.6‰ from 1896 to 1953, similar to other coral records from the tropical and subtropical Pacific. Δ14C values rose from ˜-60‰ to ˜+110‰ by 1980 due to the input of bomb radiocarbon from the atmosphere. Elevated Δ14C values were observed for the mid- to late-1950s, suggesting early input of bomb radiocarbon, possibly from the largest Marshall Islands bomb tests in 1954. Secondary aragonite precipitation was identified in a portion of one core using scanning electron microscopy and X-radiography, and was responsible for high δ18O and δ13C values and a correlation between them. The Δ14C results were more resistant to alteration, except when contamination was from the bomb era (>1956).

  9. The early Lateglacial re-colonization of Britain: new radiocarbon evidence from Gough's Cave, southwest England

    Science.gov (United States)

    Jacobi, R. M.; Higham, T. F. G.

    2009-09-01

    Gough's Cave is still Britain's most significant Later Upper Palaeolithic site. New ultrafiltered radiocarbon determinations on bone change our understanding of its occupation, by demonstrating that this lasted for only a very short span of time, at the beginning of the Lateglacial Interstadial (Greenland Interstadial 1 (GI-1: Bølling and Allerød)). The application of Bayesian modelling to the radiocarbon dates from this, and other sites from the period in southwest England, suggests that re-colonization after the Last Glacial Maximum took place only after 14,700 cal BP, and is, therefore, more recent than that of the Paris Basin and the Belgian Ardennes. On their own, the radiocarbon determinations cannot tell us whether re-colonization was synchronous with, just prior to, or after, Lateglacial warming. Isotopic studies of humanly-modified mammalian tooth enamel may be one way forward.

  10. Calibration of Flick standards

    International Nuclear Information System (INIS)

    Thalmann, Ruedi; Spiller, Jürg; Küng, Alain; Jusko, Otto

    2012-01-01

    Flick standards or magnification standards are widely used for an efficient and functional calibration of the sensitivity of form measuring instruments. The results of a recent measurement comparison have shown to be partially unsatisfactory and revealed problems related to the calibration of these standards. In this paper the influence factors for the calibration of Flick standards using roundness measurement instruments are discussed in detail, in particular the bandwidth of the measurement chain, residual form errors of the device under test, profile distortions due to the diameter of the probing element and questions related to the definition of the measurand. The different contributions are estimated using simulations and are experimentally verified. Also alternative methods to calibrate Flick standards are investigated. Finally the practical limitations of Flick standard calibration are shown and the usability of Flick standards both to calibrate the sensitivity of roundness instruments and to check the filter function of such instruments is analysed. (paper)

  11. Simultaneous measurement of tritium and radiocarbon by ultra-low-background proportional counting.

    Science.gov (United States)

    Mace, Emily; Aalseth, Craig; Alexander, Tom; Back, Henning; Day, Anthony; Hoppe, Eric; Keillor, Martin; Moran, Jim; Overman, Cory; Panisko, Mark; Seifert, Allen

    2017-08-01

    Use of ultra-low-background capabilities at Pacific Northwest National Laboratory provide enhanced sensitivity for measurement of low-activity sources of tritium and radiocarbon using proportional counters. Tritium levels are nearly back to pre-nuclear test backgrounds (~2-8 TU in rainwater), which can complicate their dual measurement with radiocarbon due to overlap in the beta decay spectra. We present results of single-isotope proportional counter measurements used to analyze a dual-isotope methane sample synthesized from ~120mg of H 2 O and present sensitivity results. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. [Radiocarbon dating of pollen and spores in wedge ice from Iamal and Kolyma].

    Science.gov (United States)

    Vasil'chuk, A K

    2004-01-01

    Radiocarbon dating of pollen concentrate from late Pleistocene syngenetic wedge ice was carried out using acceleration mass spectrometry (AMS) in Seyakha and Bizon sections. Comparison of the obtained dating with palynological analysis and AMS radiocarbon dating previously obtained for other organic fractions of the same samples allowed us to evaluate accuracy of dating of different fractions. Quantitative tests for data evaluation were considered in terms of possible autochthonous or allochthonous accumulation of the material on the basis of pre-Pleistocene pollen content in these samples. Paleoecological information content of pollen spectra from late Pleistocene syngenetic wedge ice was evaluated.

  13. Optical Measurement of Radiocarbon below Unity Fraction Modern by Linear Absorption Spectroscopy.

    Science.gov (United States)

    Fleisher, Adam J; Long, David A; Liu, Qingnan; Gameson, Lyn; Hodges, Joseph T

    2017-09-21

    High-precision measurements of radiocarbon ( 14 C) near or below a fraction modern 14 C of 1 (F 14 C ≤ 1) are challenging and costly. An accurate, ultrasensitive linear absorption approach to detecting 14 C would provide a simple and robust benchtop alternative to off-site accelerator mass spectrometry facilities. Here we report the quantitative measurement of 14 C in gas-phase samples of CO 2 with F 14 C radiocarbon measurement science including the study of biofuels and bioplastics, illicitly traded specimens, bomb dating, and atmospheric transport.

  14. Radiocarbon analysis of the Torah scrolls from the National Museum of Brazil collection

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Fabiana M. [Instituto de Física – Universidade Federal Fluminense (IF-UFF), Campus da Praia Vermelha, Av. Gal. Milton Tavares de Souza, s/n°, CEP 24210-346 Niterói, RJ (Brazil); Araujo, Carlos A.R. [Departamento de História (Programa de História Comparada), Universidade Federal do Rio de Janeiro (UFRJ), Largo de São Francisco 1/sala 311, CEP 20051-070 Centro Rio de Janeiro, RJ (Brazil); Macario, Kita D., E-mail: kitamacario@gmail.com [Instituto de Física – Universidade Federal Fluminense (IF-UFF), Campus da Praia Vermelha, Av. Gal. Milton Tavares de Souza, s/n°, CEP 24210-346 Niterói, RJ (Brazil); Cid, Alberto S. [Instituto de Física – Universidade Federal Fluminense (IF-UFF), Campus da Praia Vermelha, Av. Gal. Milton Tavares de Souza, s/n°, CEP 24210-346 Niterói, RJ (Brazil)

    2015-10-15

    This radiocarbon study aims to physically verify the critical analysis of the Torah scrolls from the National Museum of Brazil collection. Although the manuscript was formerly believed to be as old as the 10th century, the paleographic and stylistic study of the books of Genesis and Deuteronomy revealed features that could be associated to the year 1560 AD. Radiocarbon analysis was performed and a phase model limited by a Historical boundary was applied. The results are in agreement with the critical analysis of the manuscript that it is not older than the 16th century.

  15. Geological data indicate that the interpretation for the age-calibrated phylogeny for the Kurixalus-genus frogs of South, South-east and East Asia (Lv et al., 2018) needs to be rethought.

    Science.gov (United States)

    Ali, Jason R

    2018-02-12

    Recently, Lv et al. (2018) published an age-calibrated phylogenetic tree for the Kurixalus frogs, members of which occur across parts of South, South-east and East Asia. A clade on Taiwan, represented by Kurixalus idiootocus and the Kurixalus eiffingeri species complex, is deemed to have been resident since the middle Cenozoic; its closest congeners are in southern Indochina (not in the adjacent parts of south-east China), and the split between the two is dated at 32.8 Ma. Furthermore, a sub-population of Kurixalus eiffingeri is believed to have colonized islands in the western Ryukyus c. 13.5 Ma. There is, however, a problem with this scenario: the landmass regarded as modern-day Taiwan has existed only for 4-5 million years (it results from a young and ongoing tectonic-plate collision). Assuming the Kurixalus phylogeny and the dating of its branchings are correct, then a palaeobiogeographical scenario involving an older, alternative land surface with later transfer to Taiwan, possibly involving over-water dispersal, would reconcile the biology, but testing this may be difficult/impossible. If the ages of the nodes in the proposed tree are found to be significantly overestimated, the geology and biology might more easily be accommodated. Copyright © 2018 Elsevier Inc. All rights reserved.

  16. Radiocarbon constraints on the coupled growth of sediment and organic carbon reservoirs in fluvial systems

    Science.gov (United States)

    Torres, M. A.; Kemeny, P. C.; Fischer, W. W.; Lamb, M. P.

    2017-12-01

    Vast amounts of sediments are stored transiently in fluvial deposits as they move in rivers from source to sink. The timescale(s) of transient storage have the potential to set the cadence for biogeochemical reactions to occur in river sediments. However, the extent to which storage modulates the chemical composition of river sediments remains unclear. In case of the organic carbon (OC) cycle, transient sediment storage may leave an imprint in the radiocarbon (14C) content of riverine particulate OC (POC), offering a potential tool to trace the coupling of sediment storage and biogeochemical cycling in river systems. We investigated the modern and ancient budgets of sediments and POC in the Efi Haukadalsá River catchment in West Iceland to provide new empirical constraints on the role of sediment storage in the terrestrial OC cycle. This field site is attractive because the basaltic bedrock is free of rock-derived (i.e. "petrogenic") POC such that bulk 14C measurements can be interpreted more directly as constraints on catchment OC storage timescales. Additionally, Lake Haukadalsvatn at the outlet of the river catchment has captured sediment for nearly 13 ka, which offers a complementary record of the evolution of climate-sediment-OC linkages since deglaciation. New 14C measurements show that bulk POC in fine grained fluvial deposits within the Haukadalsá catchment is remarkably old (model ages between 1 and 10 ka). This evidence for "aged" POC in floodplain storage is consistent with previous measurements from Lake Haukadalsvatn, which show that POC is aged in the river system by thousands of years prior to deposition in the lake. Additionally, our estimate of the mean transit time of sediments through the river system matches the millennial-scale reservoir age of riverine POC derived from 14C, which implies a tight coupling between sediment storage and the OC cycle. We interpret the long-term increase in the 14C reservoir age of riverine POC over the last 10 ka

  17. RF impedance measurement calibration

    International Nuclear Information System (INIS)

    Matthews, P.J.; Song, J.J.

    1993-01-01

    The intent of this note is not to explain all of the available calibration methods in detail. Instead, we will focus on the calibration methods of interest for RF impedance coupling measurements and attempt to explain: (1). The standards and measurements necessary for the various calibration techniques. (2). The advantages and disadvantages of each technique. (3). The mathematical manipulations that need to be applied to the measured standards and devices. (4). An outline of the steps needed for writing a calibration routine that operated from a remote computer. For further details of the various techniques presented in this note, the reader should consult the references

  18. Age accuracy and resolution of Quaternary corals used as proxies for sea level

    Science.gov (United States)

    Edinger, E. N.; Burr, G. S.; Pandolfi, J. M.; Ortiz, J. C.

    2007-01-01

    The accuracy of global eustatic sea level curves measured from raised Quaternary reefs, using radiometric ages of corals at known heights, may be limited by time-averaging, which affects the variation in coral age at a given height. Time-averaging was assessed in uplifted Holocene reef sequences from the Huon Peninsula, Papua New Guinea, using radiocarbon dating of coral skeletons in both horizontal transects and vertical sequences. Calibratedage ranges varied from 800 to 1060 years along horizontal transects, but weighted mean ages calculated from 15-18 dates per horizon were accurate to a resolution within 154-214 yr. Approximately 40% of the variability in age estimate resulted from internal variability inherent to 14C estimates, and 60% was due to time-averaging. The accuracy of age estimates of sea level change in studies using single dated corals as proxies for sea level is probably within 1000 yr of actual age, but can be resolved to ≤ 250 yr if supported by dates from analysis of a statistical population of corals at each stratigraphic interval. The range of time-averaging among reef corals was much less than that for shelly benthos. Ecological time-averaging dominated over sedimentological time averaging for reef corals, opposite to patterns reported from shelly benthos in siliciclastic environments.

  19. Calibration of moisture monitors

    International Nuclear Information System (INIS)

    Gutierrez, R.L.

    1979-02-01

    A method for calibrating an aluminum oxide hygrometer against an optical chilled mirror dew-point hygrometer has been established. A theoretical cross-point line of dew points from both hygrometers and a maximum moisture content of 10 ppM/sub v/ are used to define an area for calibrating the sensor probes of the aluminum oxide hygrometer

  20. Site Calibration report

    DEFF Research Database (Denmark)

    Yordanova, Ginka; Vesth, Allan

    The report describes site calibration measurements carried out on a site in Denmark. The measurements are carried out in accordance to Ref. [1]. The site calibration is carried out before a power performance measurement on a given turbine to clarify the influence from the terrain on the ratio...

  1. Topics in Statistical Calibration

    Science.gov (United States)

    2014-03-27

    Natural cubic spline speed di st 110 B.2 The calibrate function The most basic calibration problem, the one often encountered in more advanced ...0040-1706, 1537-2723. A. M. Mood, F. A. Graybill, and D. C. Boes. Introduction to the Theory of Statistics. McGraw-Hill, Auckland , U.A, 1974. ISBN

  2. Sandia WIPP calibration traceability

    Energy Technology Data Exchange (ETDEWEB)

    Schuhen, M.D. [Sandia National Labs., Albuquerque, NM (United States); Dean, T.A. [RE/SPEC, Inc., Albuquerque, NM (United States)

    1996-05-01

    This report summarizes the work performed to establish calibration traceability for the instrumentation used by Sandia National Laboratories at the Waste Isolation Pilot Plant (WIPP) during testing from 1980-1985. Identifying the calibration traceability is an important part of establishing a pedigree for the data and is part of the qualification of existing data. In general, the requirement states that the calibration of Measuring and Test equipment must have a valid relationship to nationally recognized standards or the basis for the calibration must be documented. Sandia recognized that just establishing calibration traceability would not necessarily mean that all QA requirements were met during the certification of test instrumentation. To address this concern, the assessment was expanded to include various activities.

  3. The GERDA calibration system

    Energy Technology Data Exchange (ETDEWEB)

    Baudis, Laura; Froborg, Francis; Tarka, Michael; Bruch, Tobias; Ferella, Alfredo [Physik-Institut, Universitaet Zuerich (Switzerland); Collaboration: GERDA-Collaboration

    2012-07-01

    A system with three identical custom made units is used for the energy calibration of the GERDA Ge diodes. To perform a calibration the {sup 228}Th sources are lowered from the parking positions at the top of the cryostat. Their positions are measured by two independent modules. One, the incremental encoder, counts the holes in the perforated steel band holding the sources, the other measures the drive shaft's angular position even if not powered. The system can be controlled remotely by a Labview program. The calibration data is analyzed by an iterative calibration algorithm determining the calibration functions for different energy reconstruction algorithms and the resolution of several peaks in the {sup 228}Th spectrum is determined. A Monte Carlo simulation using the GERDA simulation software MAGE has been performed to determine the background induced by the sources in the parking positions.

  4. Sandia WIPP calibration traceability

    International Nuclear Information System (INIS)

    Schuhen, M.D.; Dean, T.A.

    1996-05-01

    This report summarizes the work performed to establish calibration traceability for the instrumentation used by Sandia National Laboratories at the Waste Isolation Pilot Plant (WIPP) during testing from 1980-1985. Identifying the calibration traceability is an important part of establishing a pedigree for the data and is part of the qualification of existing data. In general, the requirement states that the calibration of Measuring and Test equipment must have a valid relationship to nationally recognized standards or the basis for the calibration must be documented. Sandia recognized that just establishing calibration traceability would not necessarily mean that all QA requirements were met during the certification of test instrumentation. To address this concern, the assessment was expanded to include various activities

  5. Radiocarbon as a Novel Tracer of Extra-Antarctic Feeding in Southern Hemisphere Humpback Whales.

    Science.gov (United States)

    Eisenmann, Pascale; Fry, Brian; Mazumder, Debashish; Jacobsen, Geraldine; Holyoake, Carlysle Sian; Coughran, Douglas; Bengtson Nash, Susan

    2017-06-29

    Bulk stable isotope analysis provides information regarding food web interactions, and has been applied to several cetacean species for the study of migration ecology. One limitation in bulk stable isotope analysis arises when a species, such as Southern hemisphere humpback whales, utilises geographically distinct food webs with differing isotopic baselines. Migrations to areas with different baselines can result in isotopic changes that mimic changes in feeding relations, leading to ambiguous food web interpretations. Here, we demonstrate the novel application of radiocarbon measurement for the resolution of such ambiguities. Radiocarbon was measured in baleen plates from humpback whales stranded in Australia between 2007 and 2013, and in skin samples collected in Australia and Antarctica from stranded and free-ranging animals. Radiocarbon measurements showed lower values for Southern Ocean feeding than for extra-Antarctic feeding in Australian waters. While the whales mostly relied on Antarctic-derived energy stores during their annual migration, there was some evidence of feeding within temperate zone waters in some individuals. This work, to our knowledge, provides the first definitive biochemical evidence for supplementary feeding by southern hemisphere humpback whales within temperate waters during migration. Further, the work contributes a powerful new tool (radiocarbon) for tracing source regions and geographical feeding.

  6. Radiocarbon dating of the human eye lens crystallines reveal proteins without carbon turnover throughout life

    DEFF Research Database (Denmark)

    Lynnerup, Niels; Kjeldsen, Henrik; Heegaard, Steffen

    2008-01-01

    , there is no subsequent remodelling of these fibers, nor removal of degraded lens fibers. Human tissue ultimately derives its (14)C content from the atmospheric carbon dioxide. The (14)C content of the lens proteins thus reflects the atmospheric content of (14)C when the lens crystallines were formed. Precise radiocarbon...

  7. Radiocarbon dating of fluvial organic matter reveals land-use impacts in boreal peatlands

    DEFF Research Database (Denmark)

    Hulatt, Chris J.; Kaartokallio, Hermanni; Oinonen, Markku

    2014-01-01

    This study measured the effects of land use on organic matter released to surface waters in a boreal peat catchment using radiocarbon dating of particulate and dissolved organic carbon (POC and DOC), DOC concentration, stable carbon and nitrogen isotope composition, and optical measurements. Undi...

  8. Radiocarbon in the air of central Europe: long-term investigations

    Czech Academy of Sciences Publication Activity Database

    Světlík, Ivo; Povinec, P. P.; Molnár, M.; Váňa, M.; Šivo, A.; Bujtás, T.

    2010-01-01

    Roč. 52, č. 2 (2010), s. 823-834 ISSN 0033-8222. [International Radiocarbon Conference /20./. Big Island, Hawai, 31.05.2009-05.06.2009] Institutional research plan: CEZ:AV0Z10480505 Keywords : 14CO2 * troposphere * Suess effect * fossil fuel combustion Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 2.703, year: 2010

  9. Radiocarbon evidence for a smaller oceanic carbon dioxide sink than previously believed

    Science.gov (United States)

    Hesshaimer, Vago; Heimann, Martin; Levin, Ingeborg

    1994-07-01

    RADIOCARBON produced naturally in the upper atmosphere or arti-ficially during nuclear weapons testing is the main tracer used to validate models of oceanic carbon cycling, in particular the exchange of carbon dioxide with the atmosphere1-3 and the mixing parameters within the ocean itself4-7. Here we test the overall consistency of exchange fluxes between all relevant compartments in a simple model of the global carbon cycle, using measurements of the long-term tropospheric CO2 concentration8 and radiocarbon composition9-12, the bomb 14C inventory in the stratosphere13,14 and a compilation of bomb detonation dates and strengths15. We find that to balance the budget, we must invoke an extra source to account for 25% of the generally accepted uptake of bomb 14C by the oceans3. The strength of this source decreases from 1970 onwards, with a characteristic timescale similar to that of the ocean uptake. Significant radiocarbon transport from the remote high stratosphere and significantly reduced uptake of bomb 14C by the biosphere can both be ruled out by observational constraints. We therefore conclude that the global oceanic bomb 14C inventory should be revised downwards. A smaller oceanic bomb 14C inventory also implies a smaller oceanic radiocarbon penetration depth16, which in turn implies that the oceans take up 25% less anthropogenic CO2 than had previously been believed.

  10. MESOLITHIC HUMAN BONES FROM THE UPPER VOLGA BASIN : RADIOCARBON AND TRACE ELEMENTS

    NARCIS (Netherlands)

    Alexandrovskiy, A. L.; Alexandrovskaya, E. I.; Zhilin, M. I.; van der Plicht, J.

    2009-01-01

    Human bones from 3 Mesolithic sites in the Upper Volga basin were analyzed for trace elements, and dated by accelerator mass spectrometry (AMS). The radiocarbon dates of the bones correspond to the Mesolithic era. However, some dates differ from those obtained for the enclosing deposits and for the

  11. Býčí skála Cave, Czech Republic: Radiocarbon dates of rock paintings

    Czech Academy of Sciences Publication Activity Database

    Svoboda, Jiří; van der Plicht, H.; Balák, I.

    2005-01-01

    Roč. 43, - (2005), s. 7-9 ISSN 1022-3282 Institutional research plan: CEZ:AV0Z80010507 Keywords : Býčí skála Czech Republic * rock art * radiocarbon dating Subject RIV: AC - Archeology, Anthropology, Ethnology

  12. The most direct and precise radiocarbon date for the Minoan eruption of Santorini

    DEFF Research Database (Denmark)

    Friedrich, Walter L.; Heinemeier, Jan

    for the Minoan eruption. Together with a second olive tree, excavated only 9 meters from the first one, it enables us to repeat the earlier measurements of the first tree 2006 (Friedrich, W.L . Kromer, B Friedrich, M. Heinemeier, J. Pfeiffer, T. Talamo, S. Santorini Eruption Radiocarbon Dated to 1627-1600 BC...

  13. Summary findings of the fourth international radiocarbon intercomparison (FIRI) (1998–2001)

    NARCIS (Netherlands)

    Boaretto, Elisabetta; Bryant, Charlotte; Carmi, Israel; Cook, Gordon; Gulliksen, Steinar; Harkness, Doug; Heinemeier, Jan; McClure, John; McGee, Edward; Naysmith, Philip; Possnert, Goran; Scott, Marian; Plicht, Hans van der; Strydonck, Mark van

    2002-01-01

    Interlaboratory comparisons have been widely used in applied radiocarbon science. These are an important part of ongoing quality assurance (QA) programmes, which are vital to the appropriate interpretation of the evidence provided by the 14C record in Quaternary applications (including climate

  14. Radiocarbon dating in near-Eastern contexts : Confusion and quality control

    NARCIS (Netherlands)

    van der Plicht, J; Bruins, HJ; Bruins, Hendrik J.; Boaretto, E.; Carmi, I.

    2001-01-01

    Near-Eastern archaeology has long remained oblivious to radiocarbon dating as unique historical calendars brought about a perception that C-14 dating is superfluous. Circular chronological reasoning may occur as a result. There is now strong C-14 evidence that the early part of Egyptian history

  15. Radiocarbon dating of American pika fecal pellets provides insights into population extirpations and climate refugia

    Science.gov (United States)

    Constance I. Millar; Katherine Heckman; Christopher Swanston; Karena Schmidt; Robert D. Westfall; Diane L. Delany

    2014-01-01

    The American pika (Ochotona princeps) has become a species of concern for its sensitivity to warm temperatures and potential vulnerability to global warming. We explored the value of radiocarbon dating of fecal pellets to address questions of population persistence and timing of site extirpation. Carbon was extracted from pellets collected at 43...

  16. New Progress on Radiocarbon Geochronology in Southern Lake Tanganyika (East Africa)

    Science.gov (United States)

    McGlue, M. M.; Soreghan, M. J.

    2017-12-01

    Our limnogeological research in Lake Tanganyika focuses on elucidating the patterns of sediment accumulation on deepwater horsts, outer platforms, and littoral environments in the lake's southern basin ( 6-8°S latitude). Here, we present new radiocarbon (14C) dates from high-quality surface sediment cores, in order to make comparisons with previously published age models, to address the presence and spatiotemporal variability of a reservoir effect, and to constrain sedimentation rates and facies at sites that may be important targets for future scientific drilling. Plant macrofossils are rare in deepwater sediment cores, so charcoal and bulk organic matter have been the primary materials used for dating. On the Kavala Island Ridge (KIR) horst, initial core descriptions revealed variations in laminae presence, thickness, and chemistry. Sediment cores from the KIR at 172m water depth consist of thickly laminated diatom oozes. Charcoal from the bases of these cores returned median ages of 2.1-2.2 cal ka, suggesting linear accumulation rates on the order of 0.51 mm/yr. By contrast, a core from 420 m water depth on the KIR exhibited very thin laminations and diatom layers were much less prominent. Charcoal at the base of this core produced a median age of 8.1 cal ka, suggesting a linear accumulation rate of 0.11 mm/yr. These initial results suggest that sedimentation rates may vary considerably over sublacustrine horst blocks. We will test this initial discovery with additional sedimentation rate information from the Kalya and Nitiri horsts. In addition, we report new 14C dates made on both dead and live-collected shells of the endemic gastropod Neothauma tanganyicense. These shells form vast accumulations along shallow-water platforms of the lake and form an important substrate for a number of other endemic species. The discovery of living snails in southern Lake Tanganyika may allow for the development of a species-specific reservoir correction. A limited N

  17. Radial ooids from Great Salt Lake (Utah) as paleoenvironmental archives: Insights from radiocarbon chronology and stable isotopes

    Science.gov (United States)

    Paradis, O. P.; Corsetti, F. A.; Bardsley, A.; Hammond, D. E.; Xu, X.; Walker, J. C.

    2017-12-01

    Ooids (laminated, carbonate coated grains) are ubiquitous in the geologic record in marine and lacustrine settings, and thus remain a common target for geochemical analysis to understand modern and ancient aqueous environments. However, the processes governing ooid formation remain unclear. Recently, radiocarbon dating has revealed that modern marine ooids grow slowly (Beaupre et al. 2015), and laboratory experiments have highlighted the importance of sediment transport and abrasion on net growth rates and ooid size (Trower et al. 2017). Ooid cortex structure includes micritic, tangential and/or radially oriented fabrics. Most modern marine ooids have tangential or micritic cortices, whereas many ancient ooids have radial cortices—thus, there is a need to understand how radial ooids in ancient rocks might inform us about their depositional environment. The Great Salt Lake (GSL), Utah, provides a unique environment to assess the growth rate of primary radial aragonitic ooids. Ooids collected near Antelope Island in the south arm of GSL were sieved, the 355-500 µm fraction was sequentially leached, and 14C of the evolved gas was analyzed to provide a time series of growth. The oldest inorganic carbon of this size fraction has an apparent 14C age of 6600 yr BP, with subsequent growth spanning over 6,000 years. Closed-basin lakes are particularly susceptible to a "reservoir effect" which results in anomalously old apparent radiocarbon ages. The 14C age of the modern dissolved inorganic carbon (DIC) of the south arm was measured to be 295 yr BP, a reservoir age comparable to estimates from lacustrine cave carbonates (McGee et al. 2012). Net growth rate of south arm ooids ranges between 0.01-0.025 µm per year. The δ13C of the outermost cortex suggests that the ooids resemble the modern DIC in the south arm water, suggesting ooids precipitate in equilibrium with lake water. Finer-scale structure in the δ13C of the ooid cortex through time suggests lake level changed

  18. New protocol for compound-specific radiocarbon analysis of archaeological bones.

    Science.gov (United States)

    Deviese, Thibaut; Comeskey, Daniel; McCullagh, James; Bronk Ramsey, Christopher; Higham, Thomas

    2018-03-15

    For radiocarbon results to be accurate, samples must be free of contaminating carbon. Sample pre-treatment using a high-performance liquid chromatography (HPLC) approach has been developed at the Oxford Radiocarbon Accelerator Unit (ORAU) as an alternative to conventional methods for dating heavily contaminated bones. This approach isolates hydroxyproline from bone collagen, enabling a purified bone-specific fraction to then be radiocarbon dated by accelerator mass spectrometry (AMS). Using semi-preparative chromatography and non-carbon-based eluents, this technique enables the separation of underivatised amino acids liberated by hydrolysis of extracted bone collagen. A particular focus has been the isolation of hydroxyproline for single-compound AMS dating since this amino acid is one of the main contributors to the total amount of carbon in mammalian collagen. Our previous approach, involving a carbon-free aqueous mobile phase, required a two-step separation using two different chromatographic columns. This paper reports significant improvements that have been recently made to the method to enable faster semi-preparative separation of hydroxyproline from bone collagen, making the method more suitable for routine radiocarbon dating of contaminated and/or poorly preserved bone samples by AMS. All steps of the procedure, from the collagen extraction to the correction of the AMS data, are described. The modifications to the hardware and to the method itself have reduced significantly the time required for the preparation of each sample. This makes it easier for other radiocarbon facilities to implement and use this approach as a routine method for preparing contaminated bone samples. Copyright © 2017 John Wiley & Sons, Ltd.

  19. Iron Age Mediterranean Chronology : A Reply

    NARCIS (Netherlands)

    Bruins, Hendrik J.; Nijboer, Albert J.; van der Plicht, Johannes

    2011-01-01

    This article is a reply to the preceding rejoinder by Fantalkin et al., which they wrote in response to our article concerning radiocarbon dates of Iron Age sites in the Mediterranean region measured at Groningen (van der Plicht et al. 2009). We do not agree with much of their criticism. Our reply

  20. Radiocarbon dating of archaeological samples (sambaqui) using CO(2) absorption and liquid scintillation spectrometry of low background radiation.

    Science.gov (United States)

    Mendonça, Maria Lúcia T G; Godoy, José M; da Cruz, Rosana P; Perez, Rhoneds A R

    2006-01-01

    Sambaqui means, in the Tupi language, a hill of shells. The sambaquis are archaeological sites with remains of pre-historical Brazilian occupation. Since the sambaqui sites in the Rio de Janeiro state region are older than 10,000 years, the applicability of CO(2) absorption on Carbo-sorb and (14)C determination by counting on a low background liquid scintillation counter was tested. In the present work, sambaqui shells were treated with H(3)PO(4) in a closed vessel in order to generate CO(2). The produced CO(2) was absorbed on Carbo-sorb. On saturation about 0.6g of carbon, as CO(2), was mixed with commercial liquid scintillation cocktail (Permafluor), and the (14)C activity determined by counting on a low background counter, Packard Tricarb 3170 TR/SL, for a period of 1000 mins to enable detection of a radiocarbon age of 22,400 BP. But only samples with ages up to 3500 BP were submitted to the method because the samples had been collected in the municipality of Guapimirim, in archaeological sambaqui-type sites belonging to this age range. The same samples were sent to the (14)C Laboratory of the Centro de Energia Nuclear na Agricultura (CENA/USP) where similar results were obtained.