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Sample records for 14c dates obtained

  1. Effect of HF leaching on 14C dates of pottery

    NASA Astrophysics Data System (ADS)

    Goslar, Tomasz; Kozłowski, Janusz; Szmyt, Marzena; Czernik, Justyna

    2013-01-01

    This paper presents the experiments with 14C dating of two potsherds, which contained carbon dispersed rather homogeneously in their clay fabric. After AAA treatment, the potsherds still appeared to be contaminated with young carbon, presumably connected with humic acids. To make removal of humic acids more effective, we treated the sherds with HF acid of different concentration. The 14C results obtained demonstrate that HF treatment indeed helps to remove humic contaminants, but it also mobilizes carbon bound to raw clay, which may make 14C dates too old. We conclude therefore, that using a simple combination of HF and AAA treatment seems insufficient in reliable 14C dating of carbon homogeneously dispersed in the volume of potsherds.

  2. Pyrolysis-combustion 14C dating of soil organic matter

    USGS Publications Warehouse

    Wang, Hongfang; Hackley, Keith C.; Panno, S.V.; Coleman, D.D.; Liu, J.C.-L.; Brown, J.

    2003-01-01

    Radiocarbon (14C) dating of total soil organic matter (SOM) often yields results inconsistent with the stratigraphic sequence. The onerous chemical extractions for SOM fractions do not always produce satisfactory 14C dates. In an effort to develop an alternative method, the pyrolysis-combustion technique was investigated to partition SOM into pyrolysis volatile (Py-V) and pyrolysis residue (Py-R) fractions. The Py-V fractions obtained from a thick glacigenic loess succession in Illinois yielded 14C dates much younger but more reasonable than the counterpart Py-R fractions for the soil residence time. Carbon isotopic composition (??13C) was heavier in the Py-V fractions, suggesting a greater abundance of carbohydrate- and protein-related constituents, and ??13C was lighter in the Py-R fractions, suggesting more lignin- and lipid-related constituents. The combination of 14C dates and ??13C values indicates that the Py-V fractions are less biodegradation resistant and the Py-R fractions are more biodegradation resistant. The pyrolysis-combustion method provides a less cumbersome approach for 14C dating of SOM fractions. With further study, this method may become a useful tool for analyzing unlithified terrestrial sediments when macrofossils are absent. ?? 2003 University of Washington. Published by Elsevier Inc. All rights reserved.

  3. 14C AMS dating Yongcheon cave

    NASA Astrophysics Data System (ADS)

    Lee, J. H.; Choe, K.; Kim, J. C.; Choi, S. H.; Kang, J.; Song, S.; Song, Y. M.; Jang, J. G.

    2013-01-01

    The biggest island in South Korea is Jeju Island, which lies 80 km south of the mainland and has one shield volcano, Mt. Halla. The volcanic island and its lava tubes were added to the world heritage list by UNESCO in 2007. Among the many lava tubes on the island, a unique cave had been accidentally found in 2005 while some workers were replacing a telephone pole. Until the discovery, it had been completely isolated from the outside by naturally-built sand blocks. Yongcheon cave is a lime-decorated lava tube showing both the properties of a volcanic lava tube and a limestone cave. This cave, about 3 km in length, is acknowledged to be the best of this type in the world and includes a large clean-water lake, lava falls, and richly developed speleothems inside it. Even though there is archaeological evidence from well preserved pottery that ancient people entered this place, the preservation of artifacts was ensured by a geological change that made later entrance difficult. We have collected charcoal samples scattered around the cave and dated them using AMS. Ages were in the range of ca. 1570-1260 BP (A.D. 340-880) and this corresponds to the Ancient Three Kingdoms and the Unified Silla era in Korean history. The 14C AMS measurement results presented in this paper on wood charcoal provide precise dates which will be very useful not only to clarify the nature of human activities in this cave but also to provide reference dates when comparing other dating methods.

  4. Forensic applications of 14C bomb-pulse dating

    NASA Astrophysics Data System (ADS)

    Zoppi, U.; Skopec, Z.; Skopec, J.; Jones, G.; Fink, D.; Hua, Q.; Jacobsen, G.; Tuniz, C.; Williams, A.

    2004-08-01

    After a brief review of the basics of 14C bomb-pulse dating, this paper presents two unique forensic applications. Particular attention is dedicated to the use of the 14C bomb-pulse to establish the time of harvest of illicit drugs such as heroin and opium. Preliminary measurements of 14C concentrations in milligram samples taken from seized drugs are presented. 14C bomb-pulse dating can determine whether drug distribution originates from stockpiles or recent manufacture, and support the action of law enforcement authorities against criminal organisations involved in drug trafficking. In addition, we describe the dating of wine vintages for a number of authenticated single label vintage red wines from the Barossa Valley - South Australia. Our results show that radiocarbon dating can be used to accurately determine wine vintages and therefore reveal the addition of unrelated materials of natural and synthetic origin.

  5. May 14C be used to date contemporary art?

    NASA Astrophysics Data System (ADS)

    Fedi, M. E.; Caforio, L.; Mandò, P. A.; Petrucci, F.; Taccetti, F.

    2013-01-01

    The use of radiocarbon in forensics is by now widespread, thanks to the so-called bomb peak, which makes it possible to perform high-precision dating. Since 1955, 14C concentration in the atmosphere had strongly increased due to nuclear explosions, reaching its maximum value in 1963-1965. After the Nuclear Test Ban Treaty, 14C started to decrease as a consequence of the exchanges between atmosphere and the other natural carbon reservoirs. Nowadays, it is still slightly above the pre-bomb value. The work presented in this paper is based on the idea of exploiting the bomb peak to “precisely” date works of contemporary art, with the aim at identifying possible fakes. We analysed two kinds of materials from the 20th century: newspapers and painting canvases. Newspaper samples were taken because they might in principle be considered to represent dated samples (considering the date on the issues). Our data (28 samples) show a trend similar to atmospheric data in the literature, although with some differences; the paper peak is flatter and shifted towards more recent years (about five years) with respect to the atmospheric data. This can be explained by taking paper manufacturing processes into account. As to the canvas samples, the measured 14C concentrations were generally reasonably consistent with the expected concentrations (based on the year on the paintings). However, this does not indicate that the interpretation of the results is simpler and more straightforward. Obviously, we only measure the 14C concentration of the fibre used for the canvas, which does not necessarily measure the date the painting was manufactured. In this paper, sample preparation and experimental results will be discussed, in order to show the potential as well as the limitations of radiocarbon to date contemporary art.

  6. Direct dating of archaeological pottery by compound-specific 14C analysis of preserved lipids.

    PubMed

    Stott, Andrew W; Berstan, Robert; Evershed, Richard P; Bronk-Ramsey, Christopher; Hedges, Robert E M; Humm, Martin J

    2003-10-01

    A methodology is described demonstrating the utility of the compound-specific 14C technique as a direct means of dating archaeological pottery. The method uses automated preparative capillary gas chromatography employing wide-bore capillary columns to isolate individual compounds from lipid extracts of archaeological potsherds in high purity (>95%) and amounts (>200 microg) sufficient for radiocarbon dating using accelerator mass spectrometry (AMS). A protocol was developed and tested on n-alkanes and n-carboxylic acids possessing a broad range of 14C ages. Analytical blanks and controls allowed background 14C measurements to be assessed and potential sources of errors to be detected, i.e., contamination with modern or dead 14C, isotopic fraction effects, etc. A "Russian doll" method was developed to transfer isolated target compounds onto tin powder/capsules prior to combustion and AMS analyses. The major advantage of the compound-specific technique is that 14C dates obtained for individual compounds can be directly linked to the commodities processed in the vessels during their use, e.g., animal fats. The compound-specific 14C dating protocol was validated on a suite of ancient pottery whose predicted ages spanned a 5000-year date range. Initial results indicate that meaningful correlations can be obtained between the predicted date of pottery and that of the preserved lipids. These findings constitute an important step forward to the direct dating of archaeological pottery.

  7. A simplified approach to calibrating [sup 14]C dates

    SciTech Connect

    Talma, A.S.; Vogel, J.C. )

    1993-01-01

    The authors propose a simplified approach to the calibration of radiocarbon dates. They use splines through the tree-ring data as calibration curves, thereby eliminating a large part of the statistical scatter of the actual data points. To express the age range, they transform the [plus minus]1 [sigma] and [plus minus]2 [sigma] values of the BP age to calendar dates and interpret them as the 68% and 95% confidence intervals. This approach by-passes the conceptual problems of the transfer of individual probability values from the radiocarbon to the calendar age. They have adapted software to make this calibration possible.

  8. New and revised 14C dates for Hawaiian surface lava flows: Paleomagnetic and geomagnetic implications

    USGS Publications Warehouse

    Pressline, N.; Trusdell, F.A.; Gubbins, David

    2009-01-01

    Radiocarbon dates have been obtained for 30 charcoal samples corresponding to 27 surface lava flows from the Mauna Loa and Kilauea volcanoes on the Island of Hawaii. The submitted charcoal was a mixture of fresh and archived material. Preparation and analysis was undertaken at the NERC Radiocarbon Laboratory in Glasgow, Scotland, and the associated SUERC Accelerator Mass Spectrometry facility. The resulting dates range from 390 years B.P. to 12,910 years B.P. with corresponding error bars an order of magnitude smaller than previously obtained using the gas-counting method. The new and revised 14C data set can aid hazard and risk assessment on the island. The data presented here also have implications for geomagnetic modelling, which at present is limited by large dating errors. Copyright 2009 by the American Geophysical Union.

  9. Development of a nanofiltration method for bone collagen 14C AMS dating

    NASA Astrophysics Data System (ADS)

    Boudin, Mathieu; Boeckx, Pascal; Buekenhoudt, Anita; Vandenabeele, Peter; Van Strydonck, Mark

    2013-01-01

    Radiocarbon dating of bones is usually performed on the collagen fraction. However, this collagen can contain exogenous molecules, including humic substances (HSs) and/or other soil components that may have a different age than the bone. Incomplete removal can result in biased 14C dates. Ultrafiltration of collagen, dissolved as gelatin (molecular weight (MW) ∼100,000 Dalton), has received considerable attention to obtain more reliable dates. Ultrafiltration is an effective method of removal of low-molecular weight contaminants from bone collagen but it does not remove high-molecular weight contaminants, such as cross-linked humic collagen complexes. However, comparative dating studies have raised the question whether this cleaning step itself may introduce contamination with carbon from the filters used. In this study, a nanofiltration method was developed using a ceramic filter to avoid a possible extraneous carbon contamination introduced by the filter. This method should be applicable to various protein materials e.g. collagen, silk, wool, leather and should be able to remove low-molecular and high molecular weight HSs. In this study bone collagen was hot acid hydrolyzed to amino acids and nanofiltrated. A filter with a molecular weight cutoff (MWCO) of 450 Dalton was chosen in order to collect the amino acids in the permeate and the HSs in the retentate. Two pilot studies were set up. Two nanofiltration types were tested in pilot study 1: dead end and cross flow filtration. Humic substance (HS)-solutions with fossil carbon and modern hydrolyzed collagen contaminated with HSs were filtrated and analyzed with spectrofluorescence to determine the HS removal. Cross flow nanofiltration showed the most efficient HS removal. A second pilot study based upon these results was set up wherein only cross flow filtration was performed. 14C measurements of the permeates of hydrolyzed modern collagen contaminated with fossil HSs demonstrate a significant but incomplete

  10. Accuracy of post-bomb 137Cs and 14C in dating fluvial deposits

    USGS Publications Warehouse

    Ely, L.L.; Webb, R.H.; Enzel, Y.

    1992-01-01

    The accuracy and precision of 137Cs and 14C for dating post-1950 alluvial deposits were evaluated for deposits from known floods on two rivers in Arizona. The presence of 137Cs reliably indicates that deposition occurred after intensive above-ground nuclear testing was initiated around 1950. There was a positive correlation between the measured level of 137Cs activity and the clay content of the sediments, although 137Cs was detected even in sandy flood sediments with low clay content. 137Cs is a valuable dating tool in arid environments where organic materials for 14C or tree-ring dating are scarce and observational records are limited. The 14C activity measured in different types of fine organic detritus yielded dates within 1 to 8 yr of a 1980 flood deposit, and the accuracy was species-dependent. However, undifferentiated mixtures of fine organic materials from several post-bomb deposits of various ages repeatedly yielded dates between 1958 and 1962, and detrital charcoal yielded a date range of 1676-1939. In semiarid environments, the residence time of most types of organic debris precludes accurate annual resolution of post-bomb 14C dates. ?? 1992.

  11. A climatic record from 14C-dated wood fragments from southwestern Colorado

    USGS Publications Warehouse

    Epstein, S.; Xu, X.; Carrara, P.

    1999-01-01

    Deuterium concentrations in trees are related to the climatic temperature at which the trees grew. Deuterium analyses were made on all available (39) 14C-dated (all 14C dates cited are uncorrected) wood fragments collected from Lake Emma sediments. The 14C dates range from 9600 to 5400 'B.P.'. Tree line was above Lake Emma at 9600 'B.P.', was at Lake Emma at about 5000 'B.P.', and is 80 m below Lake Emma at the present time. The isotopic records at the various intervals of time coincide very well with this history. The range of ??D values is maximum at 9600 'B.P.' and is minimum at about 5400 'B.P.'. These data allow us to estimate the temperature range for the area between tree line and Lake Emma between these times. These results confirm previously observed cooling trends from several sources in the Western Hemisphere.

  12. Influence of increasing combustion temperature on the AMS 14C dating of modern crop phytoliths

    PubMed Central

    Yin, Jinhui; Yang, Xue; Zheng, Yonggang

    2014-01-01

    Several attempts have been made to directly date phytoliths, but most 14C results are not consistent with other independent chronologies. Due to the limited dataset, there is not a clear explanation for these discrepancies. Herein, we report the 14C ages of phytolith-occluded carbon (PhytOC) from contemporary rice and millet crops that were combusted at different temperatures to investigate the relationship between the combustion temperature and resulting 14C age. Our results show that the 14C age of PhytOC increases directly with combustion temperature (up to 1100°C) and results in age overestimations of hundreds of years. Considerably older ages are observed at higher temperatures, suggesting that it may be possible to distinguish between two fractions of organic carbon in phytoliths: labile and recalcitrant carbon. These findings challenge the assumption that PhytOC is homogeneous, an assumption made by those who have previously attempted to directly date phytoliths using 14C. PMID:25288281

  13. Establishing chronologies for loess records within 40 ka by AMS 14C-dating of small mollusc shells

    NASA Astrophysics Data System (ADS)

    Ujvari, Gabor; Molnar, Mihaly; Novothny, Agnes; Kovacs, Janos

    2014-05-01

    The key objective of the INTIMATE project is to determine whether abrupt climatic changes during the period of 60 to 8 ka, as reflected in a range of proxy records, were regionally synchronous or whether there were significant 'leads' and 'lags' between the atmospheric, marine, terrestrial and cryospheric realms. Such goals require precisely dated records of paleoenvironmental change for this period. Although wind-blown loess deposits are regarded as key terrestrial archives of millennial or even centennial scale environmental changes, these records are mostly poorly dated and/or their age-depth models have uncertainties of millennial magnitude. This prevents us from addressing issues like synchroneity of abrupt climatic/environmental events on millennial time scales. Two different means of dating are commonly applied for loess sequences: luminescence and radiocarbon dating. Major problems are low precision of luminescence ages and the general lack of organic macrofossils (e.g. charcoal) in loess that can reliably be dated using 14C. Other datable phases in loess are mollusc shells, rhizoliths and organic matter. While organic matter 14C ages are often seriously compromised by rejuvenation in loess sequences, rhizolites consistently yield very young ages as first demonstrated in German loess profiles. Indeed, hypocatings (rhizolites) gave Holocene ages from three different depths (4.00 m: 9744-10156 2σ age range in cal yr BP, 5.00 m: 8013-8167 cal yr BP and 6.00 m: 9534-9686 cal yr BP) in the Dunaszekcső loess record we investigated. Mollusc shells are the only remaining phases for dating, but these are usually regarded as unreliable material for 14C-dating, as they may incorporate 14C-deficient (or dead) carbon from the local carbonate-rich substrate during shell formation, thereby producing anomalously old ages by up to 3000 years. Recent studies, however, indicated that reliable ages can be obtained by radiocarbon dating of molluscs having comparatively small (

  14. Stepped-combustion 14C dating of bomb carbon in lake sediment

    USGS Publications Warehouse

    McGeehin, J.; Burr, G.S.; Hodgins, G.; Bennett, S.J.; Robbins, J.A.; Morehead, N.; Markewich, H.

    2004-01-01

    In this study, we applied a stepped-combustion approach to dating post-bomb lake sediment from north-central Mississippi. Samples were combusted at a low temperature (400 ??C) and then at 900 ??C. The CO2 was collected separately for both combustions and analyzed. The goal of this work was to develop a methodology to improve the accuracy of 14C dating of sediment by combusting at a lower temperature and reducing the amount of reworked carbon bound to clay minerals in the sample material. The 14C fraction modern results for the low and high temperature fractions of these sediments were compared with well-defined 137Cs determinations made on sediment taken from the same cores. Comparison of "bomb curves" for 14C and 137Cs indicate that low temperature combustion of sediment improved the accuracy of 14C dating of the sediment. However, fraction modern results for the low temperature fractions were depressed compared to atmospheric values for the same time frame, possibly the result of carbon mixing and the low sedimentation rate in the lake system.

  15. A numerical approach to 14C wiggle-match dating of organic deposits: best fits and confidence intervals

    NASA Astrophysics Data System (ADS)

    Blaauw, Maarten; Heuvelink, Gerard B. M.; Mauquoy, Dmitri; van der Plicht, Johannes; van Geel, Bas

    2003-06-01

    14C wiggle-match dating (WMD) of peat deposits uses the non-linear relationship between 14C age and calendar age to match the shape of a sequence of closely spaced peat 14C dates with the 14C calibration curve. A numerical approach to WMD enables the quantitative assessment of various possible wiggle-match solutions and of calendar year confidence intervals for sequences of 14C dates. We assess the assumptions, advantages, and limitations of the method. Several case-studies show that WMD results in more precise chronologies than when individual 14C dates are calibrated. WMD is most successful during periods with major excursions in the 14C calibration curve (e.g., in one case WMD could narrow down confidence intervals from 230 to 36 yr).

  16. 14C BOMB-PULSE DATING AND STABLE ISOTOPE ANALYSIS FOR GROWTH RATE AND DIETARY INFORMATION IN BREAST CANCER?

    PubMed

    Lång, K; Eriksson Stenström, K; Rosso, A; Bech, M; Zackrisson, S; Graubau, D; Mattsson, S

    2016-06-01

    The purpose of this study was to perform an initial investigation of the possibility to determine breast cancer growth rate with (14)C bomb-pulse dating. Tissues from 11 breast cancers, diagnosed in 1983, were retrieved from a regional biobank. The estimated average age of the majority of the samples overlapped the year of collection (1983) within 3σ Thus, this first study of tumour tissue has not yet demonstrated that (14)C bomb-pulse dating can obtain information on the growth of breast cancer. However, with further refinement, involving extraction of cell types and components, there is a possibility that fundamental knowledge of tumour biology might still be gained by the bomb-pulse technique. Additionally, δ (13)C and δ (15)N analyses were performed to obtain dietary and metabolic information, and to serve as a base for improvement of the age determination.

  17. 14C BOMB-PULSE DATING AND STABLE ISOTOPE ANALYSIS FOR GROWTH RATE AND DIETARY INFORMATION IN BREAST CANCER?

    PubMed Central

    Lång, K.; Eriksson Stenström, K.; Rosso, A.; Bech, M.; Zackrisson, S.; Graubau, D.; Mattsson, S.

    2016-01-01

    The purpose of this study was to perform an initial investigation of the possibility to determine breast cancer growth rate with 14C bomb-pulse dating. Tissues from 11 breast cancers, diagnosed in 1983, were retrieved from a regional biobank. The estimated average age of the majority of the samples overlapped the year of collection (1983) within 3σ. Thus, this first study of tumour tissue has not yet demonstrated that 14C bomb-pulse dating can obtain information on the growth of breast cancer. However, with further refinement, involving extraction of cell types and components, there is a possibility that fundamental knowledge of tumour biology might still be gained by the bomb-pulse technique. Additionally, δ 13C and δ 15N analyses were performed to obtain dietary and metabolic information, and to serve as a base for improvement of the age determination. PMID:27179119

  18. Test of AMS 14C dating of pollen concentrates using tephrochronology

    NASA Astrophysics Data System (ADS)

    Newnham, Rewi M.; Vandergoes, Marcus J.; Garnett, Mark H.; Lowe, David J.; Prior, Christine; Almond, Peter C.

    2007-01-01

    Previous attempts to radiocarbon date sediments >10 kyr from the high rainfall region of Westland, New Zealand, a critical location for investigation of interhemispheric patterns of climate change, have been problematic. This study, building on recent work by Vandergoes and Prior ([2003]), shows that AMS 14C dating of pollen concentrates has potential to provide more reliable ages than other sediment constituents, including plant macrofossils. The method was applied to sediments from three sites containing the 22.6k 14C yr Kawakawa Tephra, which provided an independent test of the 14C ages. Although some minor laboratory contamination was detected in tests on background standards, the modelled relationship between sample mass and measured 14C content permitted an appropriate correction to be determined. Improved pollen concentrations derived by density separation between 1.4 and 1.2 specific gravity and sieving in the range 10-50 m provided either older ages than other fractions of the same sample or, where in situ contamination was not evident, equivalent ages. Differences in degree of in situ contamination between depositional environments indicated that, in Westland, lake sites may be less susceptible to contamination by younger carbon than peat sites, where this process may be facilitated by root penetration into underlying sediments. Copyright

  19. OSL versus 14C dating of sandy pedosediments as paleo-ecological archives in cultural landscapes

    NASA Astrophysics Data System (ADS)

    van Mourik, J. M.

    2009-04-01

    Late glacial aeolian coversand dominates the surface geology of an extensive area in Northwest Europe. During prehistoric and early historic time, forest grazing, wood cutting and shifting cultivation gradually transformed natural forest into heath land. Subsequently the use of the heath for the production of organic manure during the period of plaggen agriculture (from early Middle Ages to the invention of chemical fertilizers around 1900 AD) resulted in the comeback of active sand drifting. Locally the coversand landscape transformed into a driftsand landscape with characteristic new landforms and soils. Important parts of soil archives in these cultural landscapes are fimic covers, records of a long period of agricultural history and polycyclic driftsand deposits, records of alternating instable and stable phases in landscape development. Based on pollen analysis of fimic covers and buried humic soil horizons in polycyclic driftsand sequences, a lot of paleoecological information is available to reconstruct the development of soils and landforms in cultural landscapes, but we need a correct chronological framework to correlate information of various sources and sites. Traditionally 14C dating was applied on humic horizons of buried soils and a 14C based chronological framework was designed to estimate the accumulation rate of fimic covers and to date stable and instable periods in polycyclic driftsand profiles. However, 14C dates of extracted SOM (soil organic matter) are not always reliable. Firstly, in studies of fimic antrosols arose disagreement between paleoecological and historical interpretators of the evolution of these antrosols. The results of soil micromorphology and 14C dating, applied on separated SOM fractions (humine, humic acids and fulvic acids) showed that SOM, present in fimic horizons, consists of a complex mix of compounds of different ages and sources. Secondly, 14C dates of buried humic soil horizons are not always reliable. In thin

  20. Carbonation rates of peridotite in the Samail Ophiolite, Sultanate of Oman, constrained through 14C dating and stable isotopes

    NASA Astrophysics Data System (ADS)

    Mervine, Evelyn M.; Humphris, Susan E.; Sims, Kenneth W. W.; Kelemen, Peter B.; Jenkins, William J.

    2014-02-01

    Detailed 14C dating as well as stable C and O isotope analyses were conducted on carbonates formed during alteration of the peridotite layer of the Samail Ophiolite, Sultanate of Oman. 14C results obtained in this and previous studies indicate that surface travertines range in age from modern to >45,000 yr BP, indicating long-term deposition and preservation. Travertine deposition rates in two localities were ˜0.1 to 0.3 mm/yr between ˜30,000 and 45,000 yr BP. Using an estimate of total travertine area, this would result in a maximum of ˜1000 to 3000 m3/yr of travertine being deposited throughout the ophiolite during this time period. This travertine deposition would have sequestered a maximum of ˜1 to 3 × 106 kg CO2/yr. Ca-rich carbonate veins that are associated with the surface travertine deposits have ages ranging from ˜4000 to 36,000 yr BP (average: 15,000 yr BP). Mg-rich carbonate veins exposed in outcrops have ages ranging from ˜8000 to 45,000 yr BP (average: 35,000 yr BP). Detailed sampling from numerous locations (3 locations in this study and 10 locations in the previous studies) indicates that no carbonate veins from the natural peridotite weathering surface are older than the ˜50,000 yr BP dating limit of 14C. However, 14C dating of Mg-rich carbonate veins from three roadcut exposures (Qafeefah, Fanja, and Al-Wuqbah) indicates that a significant number of roadcut veins are 14C dead (>50,000 yr BP). A location weighted average indicates that ˜40% of veins sampled at the three roadcuts are 14C dead. An average including veins sampled at both roadcuts and outcrops indicates that overall ˜8% of Mg-rich carbonate veins are 14C dead. Mg-rich carbonate veins are estimated to sequester on the order of 107 kg CO2/yr throughout the ophiolite.

  1. Correlating the Ancient Maya and Modern European Calendars with High-Precision AMS 14C Dating

    NASA Astrophysics Data System (ADS)

    Kennett, Douglas J.; Hajdas, Irka; Culleton, Brendan J.; Belmecheri, Soumaya; Martin, Simon; Neff, Hector; Awe, Jaime; Graham, Heather V.; Freeman, Katherine H.; Newsom, Lee; Lentz, David L.; Anselmetti, Flavio S.; Robinson, Mark; Marwan, Norbert; Southon, John; Hodell, David A.; Haug, Gerald H.

    2013-04-01

    The reasons for the development and collapse of Maya civilization remain controversial and historical events carved on stone monuments throughout this region provide a remarkable source of data about the rise and fall of these complex polities. Use of these records depends on correlating the Maya and European calendars so that they can be compared with climate and environmental datasets. Correlation constants can vary up to 1000 years and remain controversial. We report a series of high-resolution AMS 14C dates on a wooden lintel collected from the Classic Period city of Tikal bearing Maya calendar dates. The radiocarbon dates were calibrated using a Bayesian statistical model and indicate that the dates were carved on the lintel between AD 658-696. This strongly supports the Goodman-Martínez-Thompson (GMT) correlation and the hypothesis that climate change played an important role in the development and demise of this complex civilization.

  2. AMS 14C dating at CIRCE: The Major Temple in Cumae (NA - Italy)

    NASA Astrophysics Data System (ADS)

    Capano, M.; Rescigno, C.; Sirleto, R.; Passariello, I.; Marzaioli, F.; D'Onofrio, A.; Terrasi, F.

    2015-10-01

    We present here one recent CIRCE (Centre for Isotopic Research on Cultural and Environmental Heritage) - Caserta (Italy) project on cultural heritage field, analysing several mice bones, discovered in the Major Temple on the acropolis of Cumae (Napoli, Southern Italy). The bones were found in a vase linked to the holy context. In order to know their dating and formulate an hypothesis on their presence on the site, if it was an accidental rodent inclusion (believed on the base of archaeological context to have occurred during building abandonment periods (IV-V or XIII centuries AD)) or an intentional and ritual remain, the bones were 14C dated by AMS at CIRCE. The results indicate that the mice bones date to the IV century BC and are contemporaneous with building construction. This dating seems to exclude an accidental rodent presence and it supports the hypothesis of Apollo veneration in the temple, based on the already known link between mice and Apollo worship rituals.

  3. Correlating the ancient Maya and modern European calendars with high-precision AMS 14C dating.

    PubMed

    Kennett, Douglas J; Hajdas, Irka; Culleton, Brendan J; Belmecheri, Soumaya; Martin, Simon; Neff, Hector; Awe, Jaime; Graham, Heather V; Freeman, Katherine H; Newsom, Lee; Lentz, David L; Anselmetti, Flavio S; Robinson, Mark; Marwan, Norbert; Southon, John; Hodell, David A; Haug, Gerald H

    2013-01-01

    The reasons for the development and collapse of Maya civilization remain controversial and historical events carved on stone monuments throughout this region provide a remarkable source of data about the rise and fall of these complex polities. Use of these records depends on correlating the Maya and European calendars so that they can be compared with climate and environmental datasets. Correlation constants can vary up to 1000 years and remain controversial. We report a series of high-resolution AMS (14)C dates on a wooden lintel collected from the Classic Period city of Tikal bearing Maya calendar dates. The radiocarbon dates were calibrated using a Bayesian statistical model and indicate that the dates were carved on the lintel between AD 658-696. This strongly supports the Goodman-Martínez-Thompson (GMT) correlation and the hypothesis that climate change played an important role in the development and demise of this complex civilization.

  4. Correlating the Ancient Maya and Modern European Calendars with High-Precision AMS 14C Dating

    PubMed Central

    Kennett, Douglas J.; Hajdas, Irka; Culleton, Brendan J.; Belmecheri, Soumaya; Martin, Simon; Neff, Hector; Awe, Jaime; Graham, Heather V.; Freeman, Katherine H.; Newsom, Lee; Lentz, David L.; Anselmetti, Flavio S.; Robinson, Mark; Marwan, Norbert; Southon, John; Hodell, David A.; Haug, Gerald H.

    2013-01-01

    The reasons for the development and collapse of Maya civilization remain controversial and historical events carved on stone monuments throughout this region provide a remarkable source of data about the rise and fall of these complex polities. Use of these records depends on correlating the Maya and European calendars so that they can be compared with climate and environmental datasets. Correlation constants can vary up to 1000 years and remain controversial. We report a series of high-resolution AMS 14C dates on a wooden lintel collected from the Classic Period city of Tikal bearing Maya calendar dates. The radiocarbon dates were calibrated using a Bayesian statistical model and indicate that the dates were carved on the lintel between AD 658-696. This strongly supports the Goodman-Martínez-Thompson (GMT) correlation and the hypothesis that climate change played an important role in the development and demise of this complex civilization. PMID:23579869

  5. 14C dating of bone using (gamma) Carboxyglutamic Acid and Carboxyglycine (Aminomalonate)

    SciTech Connect

    Southon, J R; Burky, R T; Kirner, D L; Taylor, R E; Hare, P E

    1999-04-27

    Radiocarbon determinations have been obtained on {gamma}-carboxyglutamic acid [Gla] and {alpha}-carboxyglycine (aminomalonate) [Am] as well as acid- and base-hydrolyzed total amino acids isolated from a series of fossil bones. As far as they are aware, Am has not been reported previously in fossil bone and neither Gla nor Am {sup 14}C values have been measured previously. Interest in Gla, an amino acid found in the non-collagen proteins osteocalcin and matrix Gla-protein (MGP), proceeds from the suggestion that it may be preferentially retained and more resistant to diagenetic contamination affecting {sup 14}C values in bones exhibiting low and trace amounts of collagen. The data do not support these suggestions. The suite of bones examined showed a general tendency for total amino acid and Gla concentrations to decrease in concert. Even for bones retaining significant amounts of collagen, Gla (and Am extracts) can yield {sup 14}C values discordant with their expected age and with {sup 14}C values obtained on total amino-acid fractions isolated from the same bone sample.

  6. A comparison of U/Th and rapid-screen 14C dates from Line Island fossil corals

    NASA Astrophysics Data System (ADS)

    Grothe, Pamela R.; Cobb, Kim M.; Bush, Shari L.; Cheng, Hai; Santos, Guaciara M.; Southon, John R.; Lawrence Edwards, R.; Deocampo, Daniel M.; Sayani, Hussein R.

    2016-03-01

    Time-consuming and expensive radiometric dating techniques limit the number of dates available to construct absolute chronologies for high-resolution paleoclimate reconstructions. A recently developed rapid-screen 14C dating technique reduces sample preparation time and per sample costs by 90%, but its accuracy has not yet been tested on shallow-water corals. In this study, we test the rapid-screen 14C dating technique on shallow-water corals by comparing 44 rapid-screen 14C dates to both high-precision 14C dates and U/Th dates from mid- to late-Holocene fossil corals collected from the central tropical Pacific (2-4°N, 157-160°W). Our results show that 42 rapid-screen 14C and U/Th dates agree within uncertainties, confirming closed-system behavior and ensuring chronological accuracy. However, two samples that grew ˜6500 years ago have calibrated 14C ages ˜1000 years younger than the corresponding U/Th ages, consistent with diagenetic alteration as indicated by the presence of 15-23% calcite. Mass balance calculations confirm that the observed dating discrepancies are consistent with 14C addition and U removal, both of which occur during diagenetic calcite recrystallization. Under the assumption that aragonite-to-calcite replacement is linear through time, we estimate the samples' true ages using the measured 14C and U/Th dates and percent calcite values. Results illustrate that the rapid-screen 14C dates of Holocene-aged fossil corals are accurate for samples with less than 2% calcite. Application of this rapid-screen 14C method to the fossil coral rubble fields from Kiritimati Island reveal significant chronological clustering of fossil coral across the landscape, with older ages farther from the water's edge.

  7. 14C dating with the bomb peak: An application to forensic medicine

    NASA Astrophysics Data System (ADS)

    Wild, E. M.; Arlamovsky, K. A.; Golser, R.; Kutschera, W.; Priller, A.; Puchegger, S.; Rom, W.; Steier, P.; Vycudilik, W.

    2000-10-01

    Samples originating from the time period after 1950 can be radiocarbon dated utilising the 14C bomb peak as a calibration curve. The applicability of "radiocarbon dating" of recent organic human material for the determination of the time of death of humans was tested. The radiocarbon results from hair and lipid samples from individuals with known date of death were compared with the results from two individuals with unknown time of death. An estimate of the year of death for the unknowns could be derived by this way. Due to the long turnover time of collagen in human bones it is not possible to use the radiocarbon content of bone collagen for a reliable estimate. In order to study the time dependence of the collagen turnover we tested "soft" chemical methods for the isolation of collagen from the bone matrix. First radiocarbon results of this investigation are presented.

  8. AMS 14C Dates for Extinct Lemurs from Caves in the Ankarana Massif, Northern Madagascar

    NASA Astrophysics Data System (ADS)

    Simons, Elwyn L.; Burney, David A.; Chatrath, Prithijit S.; Godfrey, Laurie R.; Jungers, William L.; Rakotosamimanana, Berthe

    1995-03-01

    An extensive late Quaternary fauna, including many extinct giant lemurs, has been collected recently in a 110+-km system of caves in the Ankarana Massif of northern Madagascar. AMS 14C dates for the acid-insoluble (collagen/gelatin) fraction of bones of the giant lemur Megaladapis (26,150 ± 400 and 12,760 ± 70 yr B.P.) confirm its presence in the area during the late Pleistocene and provide the first Pleistocene 14 C ages from bones of the extinct megafauna of the island. The first date from bones of the recently described extinct Babakotia radofilai (4400 ± 60 yr B.P.) shows that it was present in northern Madagascar in mid-Holocene times. A comparatively recent age of 1020 ± 50 yr B.P. for the extinct Archaeolemur indicates survival of this genus for at least a millennium after the first direct evidence for humans in Madagascar. This suggests that the island's "extinction window" may have represented a longer time span than would have been expected under the Blitzkrieg model of late Quaternary extinctions. A mid-Holocene age (4560 ± 70 yr B.P.) for a bone sample of the small extant lemur Hapalemur simus indicates that the disappearance of this now-restricted species from the Ankarana occurred after this date. New data from the Ankarana and other sites on the island add to the consensus that major biotic changes occurred on Madagascar in the late Holocene.

  9. The first case study of 230Th/U and 14C dating of mid-valdai organic deposits

    NASA Astrophysics Data System (ADS)

    Maksimov, F. E.; Kuznetsov, V. Yu.; Zaretskaya, N. E.; Subetto, D. A.; Shebotinov, V. V.; Zherebtsov, I. E.; Levchenko, S. B.; Kuznetsov, D. D.; Larsen, E.; Lysö, A.; Jensen, M.

    2011-05-01

    From the viewpoint of precision and reliability of radioisotopic dating, deposits whose quantitative age can be determined through several methods of geochronometry are of special interest. The mutually conforming finite 14C and 230Th/U dates of buried Neopleistocene organic deposits, taken from the Tolokonka section by the North Dvina River (100 km downstream from the city of Kotlas), have been obtained for the first time in Russia. The stratigraphical reference of these results to those obtained via the optically induced luminescence for upper and lower bedding layers has been established. The presented geochronometric data have allowed us to consider the age of oxbow lake organic deposits completely reliable and refer the time of their formation to the Tyrbei warming within the MIS-3. The applicability of the new version of the 230Th/U method for dating of interglacial and interstadial deposits, for the purpose of solving the Middle and Late Neopleistocene chronostratigraphy issues, is confirmed.

  10. The coevolution of ritual and society: New 14C dates from ancient Mexico

    PubMed Central

    Marcus, Joyce; Flannery, Kent V.

    2004-01-01

    New 14C dates from Oaxaca, Mexico, document changes in religious ritual that accompanied the evolution of society from hunting and gathering to the archaic state. Before 4000 B.P. in conventional radiocarbon years, a nomadic egalitarian lifeway selected for unscheduled (ad hoc) ritual from which no one was excluded. With the establishment of permanent villages (4000–3000 B.P.), certain rituals were scheduled by solar or astral events and restricted to initiates/social achievers. After state formation (2050 B.P.), many important rituals were performed only by trained full-time priests using religious calendars and occupying temples built by corvée labor. Only 1,300–1,400 years seem to have elapsed between the oldest known ritual building and the first standardized state temple. PMID:15601758

  11. The coevolution of ritual and society: new 14C dates from ancient Mexico.

    PubMed

    Marcus, Joyce; Flannery, Kent V

    2004-12-28

    New (14)C dates from Oaxaca, Mexico, document changes in religious ritual that accompanied the evolution of society from hunting and gathering to the archaic state. Before 4000 B.P. in conventional radiocarbon years, a nomadic egalitarian lifeway selected for unscheduled (ad hoc) ritual from which no one was excluded. With the establishment of permanent villages (4000-3000 B.P.), certain rituals were scheduled by solar or astral events and restricted to initiates/social achievers. After state formation (2050 B.P.), many important rituals were performed only by trained full-time priests using religious calendars and occupying temples built by corvee labor. Only 1,300-1,400 years seem to have elapsed between the oldest known ritual building and the first standardized state temple.

  12. A Holocene paleosecular variation from 14C-dated volcanic rocks in Western North America

    USGS Publications Warehouse

    Hagstrum, J.T.; Champion, D.E.

    2002-01-01

    A paleosecular variation (PSV) curve for western North America is presented on the basis of 94 virtual geomagnetic poles (VGPs) from dated volcanic rocks sampled at 446 sites. Approximately 60% of the paleomagnetic database has been previously published. A curve defined by "spherical smoothed splines" is fitted to the VGPs, ranked by the quality of the age determinations, where the data density is highest between 3690 and -30 years before present (B.P.) (A.D. 1950), between 7800 and 7050 years B.P., and between 14,060 and 12,700 years B.P. The younger segments of the curve derived from volcanic rocks are similar but less complex than other high-resolution PSV curves derived from lacustrine sediments, particularly the record at Fish Lake, Oregon. The PSV record from lava flows (PSVL), however, is perhaps more reliable in its general shape and chronology because of the higher fidelity of volcanic rocks as magnetic field recorders and because of the greater density of 14C dates. The new PSVL record provides a partial Holocene master curve for western North America and will be of particular value in dating geological and archeological materials using paleomagnetic directions.

  13. Insights into Holocene megafauna survival and extinction in southeastern Brazil from new AMS 14C dates

    NASA Astrophysics Data System (ADS)

    Hubbe, Alex; Hubbe, Mark; Karmann, Ivo; Cruz, Francisco W.; Neves, Walter A.

    2013-03-01

    The extinction of late Quaternary megafauna in South America has been extensively debated in past decades. The majority of the hypotheses explaining this phenomenon argue that the extinction was the result of human activities, environmental changes, or even synergism between the two. Although still limited, a good chronological framework is imperative to discuss the plausibility of the available hypotheses. Here we present six new direct AMS 14C radiocarbon dates from the state of São Paulo (Brazil) to further characterize the chronological distribution of extinct fauna in this part of South America. The new dates make evident that ground sloths, toxodonts, and saber-toothed cats lived in the region around the Pleistocene/Holocene transition, and, in agreement with previous studies, also suggest an early Holocene survival for the ground sloth Catonyx cuvieri. Taken together with local paleoclimatic and archaeological data, the new dates do not support hunting or indirect human activities as a major cause for megafauna extinction. Although more data are required, parsimony suggests that climatic changes played a major role in this extinction event.

  14. A new procedure for extraction of collagen from modern and archaeological bones for 14C dating.

    PubMed

    Maspero, F; Sala, S; Fedi, M E; Martini, M; Papagni, A

    2011-10-01

    Bones are potentially the best age indicators in a stratigraphic study, because they are closely related to the layer in which they are found. Collagen is the most suitable fraction and is the material normally used in radiocarbon dating. Bone contaminants can strongly alter the carbon isotopic fraction values of the samples, so chemical pretreatment for (14)C dating by accelerator mass spectrometry (AMS) is essential. The most widespread method for collagen extraction is based on the Longin procedure, which consists in HCl demineralization to dissolve the inorganic phase of the samples, followed by dissolution of collagen in a weak acid solution. In this work the possible side effects of this procedure on a modern bone are presented; the extracted collagen was analyzed by ATR-IR spectroscopy. An alternative procedure, based on use of HF instead of HCl, to minimize unwanted degradation of the organic fraction, is also given. A study by ATR-IR spectroscopic analysis of collagen collected after different demineralization times and with different acid volumes, and a study of an archaeological sample, are also presented.

  15. Cross-checking groundwater age by 4He and 14C dating in a granite, Tono area, central Japan

    NASA Astrophysics Data System (ADS)

    Hasegawa, Takuma; Nakata, Kotaro; Tomioka, Yuichi; Goto, Kazuyuki; Kashiwaya, Koki; Hama, Katsuhiro; Iwatsuki, Teruki; Kunimaru, Takanori; Takeda, Masaki

    2016-11-01

    Groundwater dating was performed simultaneously by the 4He and 14C methods in granite of the Tono area in central Japan. Groundwater was sampled at 30 packed-off sections of six 1000-m boreholes. 4He concentrations increased and 14C concentrations decreased along a groundwater flow path on a topographic gradient. 4He ages were calculated by using the in situ 4He production rate derived from the porosity, density, and U and Th content of the rock, neglecting external flux. 14C ages were calculated with a noncorrected model in which the initial 14C content was 100 percent of the modern radiocarbon level (Co = 100 pmC), a statistical model using the average 14C content of tritium-bearing samples (Co = 46.4 pmC), and a δ13C model based on the isotopic mass balance. Although the absolute 14C ages calculated by the models were different, the relative 14C ages were almost identical. The relative 14C ages were considered reliable because dissolved inorganic carbon has no significant geochemical reactions in granite. The relation between the 4He ages and the noncorrected 14C ages was [4He age] = 1.15 [14C age] + 7200 (R2 = 0.81), except in the discharge area. The slope of this relation was equivalent to unity, which indicates that the 4He accumulation rate is confirmed by the relative 14C ages. Moreover, the accumulated 3He/4He ratio was equivalent to that derived from the 6Li(α,n)3H reaction in granite. These results show that the accumulated He is of crustal origin, produced in situ without external flux, except in the discharge area. The intercept value of 7200 a implies that the 14C concentrations were diluted due to geochemical reactions. Tritium-bearing samples supported this result. Simultaneous measurements make it feasible to estimate the accumulation rate of 4He and initial dilution of 14C, which cannot be done with a single method. Cross-checking groundwater dating has the potential to provide more reliable groundwater ages. The circulation time of the

  16. Local variations in 14C - How is bomb-pulse dating of human tissues and cells affected?

    NASA Astrophysics Data System (ADS)

    Stenström, Kristina; Skog, Göran; Nilsson, Carl Magnus; Hellborg, Ragnar; Svegborn, Sigrid Leide; Georgiadou, Elisavet; Mattsson, Sören

    2010-04-01

    Atmospheric nuclear weapons testing in the late 1950s and early 1960s almost doubled the amount of 14C in the atmosphere. The resulting 14C "bomb-pulse" has been shown to provide useful age information in e.g. forensic and environmental sciences, biology and the geosciences. The technique is also currently being used for retrospective cell dating in man, in order to provide insight into the rate of formation of new cells in the human body. Bomb-pulse dating relies on precise measurements of the declining 14C concentration in atmospheric CO 2 collected at clean-air sites. However, it is not always recognized that the calculations can be complicated in some cases by significant local variations in the specific activity of 14C in carbon in the air and foodstuff. This paper presents investigations of local 14C variations in the vicinities of nuclear installations and laboratories using 14C. Levels of 14C in workers using this radioisotope are also discussed.

  17. A sedimentologic and 14C dating study of five eastern Australian upper continental slope submarine landslides

    NASA Astrophysics Data System (ADS)

    Clarke, S. L.; Hubble, T.; Webster, J.; Airey, D.; De Carli, E.; Ferraz, C.; Reimer, P. J.; Boyd, R.; Keene, J.

    2013-12-01

    Sedimentologic and AMS 14C age data are reported for calcareous hemipelagic mud samples taken from gravity cores collected at sites within, or adjacent to five submarine landslides identified with multibeam bathymetry data on the Nerrang Plateau segment and surrounding canyons of eastern Australia's continental slope (Bribie Bowl, Coolangatta-2, Coolangatta-1, Cudgen and Byron). Sediments are comprised of mixtures of calcareous and terrigenous clay (10-20%), silt (50-65%) and sand (15-40%) and are generally uniform in appearance. Their carbonate contents vary between and 17% and 22% by weight while organic carbon contents are less than 10% by weight. Dating of conformably deposited material identified in ten of the twelve cores indicates a range of sediment accumulation rates between 0.017mka-1 and 0.2 mka-1 which are consistent with previous estimates reported for this area. One slide-adjacent core, and four within-landslide cores present depositional hiatus surfaces located at depths of 0.8 to 2.2 meters below the present-day seafloor and identified by a sharp, colour-change boundary; discernable but small increases in sediment stiffness; and a slight increase in sediment bulk density of 0.1 gcm-3. Distinct gaps in AMS 14C age of at least 20ka are recorded across these boundary surfaces. Examination of sub-bottom profiler records of transects through three of the within-slide core-sites and their nearby landslide scarps available for the Coolangatta-1 and Cudgen slides indicate that: 1) the youngest identifiable sediment layer reflectors upslope of these slides, terminate on and are truncated by slide rupture surfaces; and 2) there is no obvious evidence in the sub-bottom profiles for a post-slide sediment layer draped over or otherwise burying slide ruptures or exposed slide detachment surfaces. This suggests that both these submarine landslides are geologically recent and suggests that the hiatus surfaces identified in Coolangatta-1's and Cudgen's within

  18. A Comparison of Rapid-Screen 14C Dates and U/Th Dates from Fossil Corals: Implications for Paleoclimate Reconstruction

    NASA Astrophysics Data System (ADS)

    Grothe, P. R.; Cobb, K. M.; Bush, S.; Cheng, H.; Santos, G.; Southon, J. R.; Edwards, R. L.

    2014-12-01

    Paleoclimate records from fossil corals provide valuable benchmarks for climate model simulations of tropical climate variability. Unfortunately, the number of such reconstructions is limited by the rarity of the relatively large fossil coral heads that are targeted for paleoclimate studies. Abundant, albeit shorter (5-10yrs-long) fossil coral sequences could be used to generate a more robust, quasi-continuous reconstruction of tropical climate with built-in uncertainty estimates, but the large number of radiometric dates required is costly. A new rapid-screen 14C dating method, with a nominal precision of ±1.8% (1σ) for young carbonates (Bush et al., 2013), is roughly 10 times faster than high-precision U/Th dating, making it well-suited to screening a large number of corals. In this study, we compare rapid-screen 14C dates to both high-precision 14C dates and U/Th dates from well-characterized mid- to late-Holocene fossil corals collected from Christmas and Fanning Islands (2-4°N, 157-160°W) (Cobb et al., 2013). Our results show that most rapid-screen 14C dates agree with high-precision 14C dates (N=3) and U/Th dates (N=42), within combined uncertainties. However, two samples that contain 15 and 23% calcite (as determined by XRD) are associated with large discrepancies in calibrated 14C vs published U/Th ages (5065-5579 yBP (2σ) versus 6350 ±13 yBP (2σ) and 4868-5424 yBP (2σ) vs 6598 ±13 yBP (2σ)), respectively (Cobb et al., 2013). The 14C-U/Th mismatches, as well as poor reproducibility of replicate U/Th dates from these samples, are consistent with diagenetic alteration indicated by the presence of calcite. Mass balance calculations indicate that the dating discrepancies can be explained by a combination of 14C addition and U removal, both of which can occur through calcite recrystallization during freshwater diagenesis. Results illustrate that the rapid-screen 14C dating method is well-suited to surveying a large number (~100's) of fossil coral

  19. Analysis of 14C and 13C in teeth provides precise birth dating and clues to geographical origin

    PubMed Central

    K, Alkass; BA, Buchholz; H, Druid; KL, Spalding

    2011-01-01

    The identification of human bodies in situations when there are no clues as to the person’s identity from circumstantial data, poses a difficult problem to investigators. The determination of age and sex of the body can be crucial in order to limit the search to individuals that are a possible match. We analyzed the proportion of bomb pulse derived carbon-14 (14C) incorporated in the enamel of teeth from individuals from different geographical locations. The ‘bomb pulse’ refers to a significant increase in 14C levels in the atmosphere caused by above ground test detonations of nuclear weapons during the cold war (1955-1963). By comparing 14C levels in enamel with 14C atmospheric levels systematically recorded over time, high precision birth dating of modern biological material is possible. Above ground nuclear bomb testing was largely restricted to a couple of locations in the northern hemisphere, producing differences in atmospheric 14C levels at various geographical regions, particularly in the early phase. Therefore, we examined the precision of 14C birth dating of enamel as a function of time of formation and geographical location. We also investigated the use of the stable isotope 13C as an indicator of geographical origin of an individual. Dental enamel was isolated from 95 teeth extracted from 84 individuals to study the precision of the 14C method along the bomb spike. For teeth formed before 1955 (N = 17), all but one tooth showed negative Δ14C values. Analysis of enamel from teeth formed during the rising part of the bomb-spike (1955-1963, N = 12) and after the peak (>1963, N = 66) resulted in an average absolute date of birth estimation error of 1.9 ±1.4 and 1.3 ± 1.0 years, respectively. Geographical location of an individual had no adverse effect on the precision of year of birth estimation using radiocarbon dating. In 46 teeth, measurement of 13C was also performed. Scandinavian teeth showed a substantially greater depression in average δ13C

  20. Analysis of 14C and 13C in teeth provides precise birth dating and clues to geographical origin.

    PubMed

    Alkass, K; Buchholz, B A; Druid, H; Spalding, K L

    2011-06-15

    The identification of human bodies in situations when there are no clues as to the person's identity from circumstantial data, poses a difficult problem to the investigators. The determination of age and sex of the body can be crucial in order to limit the search to individuals that are a possible match. We analyzed the proportion of bomb pulse derived carbon-14 ((14)C) incorporated in the enamel of teeth from individuals from different geographical locations. The 'bomb pulse' refers to a significant increase in (14)C levels in the atmosphere caused by above ground test detonations of nuclear weapons during the cold war (1955-1963). By comparing (14)C levels in enamel with (14)C atmospheric levels systematically recorded over time, high precision birth dating of modern biological material is possible. Above ground nuclear bomb testing was largely restricted to a couple of locations in the northern hemisphere, producing differences in atmospheric (14)C levels at various geographical regions, particularly in the early phase. Therefore, we examined the precision of (14)C birth dating of enamel as a function of time of formation and geographical location. We also investigated the use of the stable isotope (13)C as an indicator of geographical origin of an individual. Dental enamel was isolated from 95 teeth extracted from 84 individuals to study the precision of the (14)C method along the bomb spike. For teeth formed before 1955 (N=17), all but one tooth showed negative Δ(14)C values. Analysis of enamel from teeth formed during the rising part of the bomb-spike (1955-1963, N=12) and after the peak (>1963, N=66) resulted in an average absolute date of birth estimation error of 1.9±1.4 and 1.3±1.0 years, respectively. Geographical location of an individual had no adverse effect on the precision of year of birth estimation using radiocarbon dating. In 46 teeth, measurement of (13)C was also performed. Scandinavian teeth showed a substantially greater depression in

  1. Analysis of 14C and 13C in teeth provides precise birth dating and clues to geographical origin.

    PubMed

    Alkass, K; Buchholz, B A; Druid, H; Spalding, K L

    2011-06-15

    The identification of human bodies in situations when there are no clues as to the person's identity from circumstantial data, poses a difficult problem to the investigators. The determination of age and sex of the body can be crucial in order to limit the search to individuals that are a possible match. We analyzed the proportion of bomb pulse derived carbon-14 ((14)C) incorporated in the enamel of teeth from individuals from different geographical locations. The 'bomb pulse' refers to a significant increase in (14)C levels in the atmosphere caused by above ground test detonations of nuclear weapons during the cold war (1955-1963). By comparing (14)C levels in enamel with (14)C atmospheric levels systematically recorded over time, high precision birth dating of modern biological material is possible. Above ground nuclear bomb testing was largely restricted to a couple of locations in the northern hemisphere, producing differences in atmospheric (14)C levels at various geographical regions, particularly in the early phase. Therefore, we examined the precision of (14)C birth dating of enamel as a function of time of formation and geographical location. We also investigated the use of the stable isotope (13)C as an indicator of geographical origin of an individual. Dental enamel was isolated from 95 teeth extracted from 84 individuals to study the precision of the (14)C method along the bomb spike. For teeth formed before 1955 (N=17), all but one tooth showed negative Δ(14)C values. Analysis of enamel from teeth formed during the rising part of the bomb-spike (1955-1963, N=12) and after the peak (>1963, N=66) resulted in an average absolute date of birth estimation error of 1.9±1.4 and 1.3±1.0 years, respectively. Geographical location of an individual had no adverse effect on the precision of year of birth estimation using radiocarbon dating. In 46 teeth, measurement of (13)C was also performed. Scandinavian teeth showed a substantially greater depression in

  2. Dating ivory by determination of 14C, 90Sr and 228/232Th.

    PubMed

    Schmied, Stefanie A K; Brunnermeier, Matthias J; Schupfner, Robert; Wolfbeis, Otto S

    2012-09-10

    A method is described to determine the time of death of elephants. This is accomplished by analysis of the radionuclides 14C, 90Sr and 228/232Th in known samples of ivory, and in samples of unknown age. The reliability of this method is considerably increased by multi nuclide analysis.

  3. Marine reservoir effect deduced from 14C dates on marine shells and terrestrial remains at archeological sites in Japan

    NASA Astrophysics Data System (ADS)

    Nakamura, Toshio; Nishida, Iwao; Takada, Hideki; Okuno, Mitsuru; Minami, Masayo; Oda, Hirotaka

    2007-06-01

    Paired marine and terrestrial samples were collected at archeological shell mounds in Kagoshima, Saga and Aichi prefectures and selected from sediment samples bored at the Mawaki archeological site in Ishikawa prefecture, to evaluate the local marine reservoir effect in Japan. The local reservoir corrections, ΔR, were evaluated to be 8 ± 110 and -178 ± 113 14C years for Miyasaka shell mound, -125 ± 50 to -45 ± 49 and -86 ± 48 to -21 ± 50 14C years for Higashimyo shell mound, -46 ± 52, 40 ± 44, -136 ± 44 and 100 ± 44 14C years for Yoshigo shell mound, -255 ± 38 and -146 ± 46 14C years for Kuzubasama shell mound, -71 ± 33, -30 ± 85 and -78 ± 74 14C years on average for C4, C5 and C6 cores, respectively, from the Mawaki site. The existing data along with the present results suggest that the ΔR values obtained for central to southern part of Japan are consistent with zero or a bit negative, but are different from the ΔR values of 200 to 500 14C years for the northern parts of the Japanese archipelago.

  4. The remarkable metrological history of 14C dating: From ancient Egyptian artifacts to particles of soot and grains of pollen

    NASA Astrophysics Data System (ADS)

    Currie, L. A.

    2003-01-01

    Radiocarbon dating would not have been possible if 14C had not had the “wrong” half-life—a fact that delayed its discovery [1]. Following the discovery of this 5730 year radionuclide in laboratory experiments by Ruben and Kamen, it became clear to W. F. Libby that 14C should exist in nature, and that it could serve as a quantitative means for dating artifacts and events marking the history of civilization. The search for natural radiocarbon was a metrological challenge; the level in the living biosphere [ca. 230 Bq/kg] lay far beyond the then current state of the measurement art. 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 14C 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 spawned new multidisciplinary areas of application, ranging from cosmic ray physics to oceanography to the reconstruction of environmental history.

  5. Accelerator 14C dates for early upper paleolithic (basal Aurignacian) at El Castillo Cave (Spain)

    USGS Publications Warehouse

    Valdes, V.C.; Bischoff, J.L.

    1989-01-01

    Three fragments of charcoal taken from different parts of the lowermost bed containing Aurignacian artifacts at El Castillo Cave yielded AMS dates of 37??7 (?? 1??8) ka bp, 38??5 (?? 1??8) ka bp, and 40??0 (?? 2??1) ka bp (average 38??7 ?? 1??9 ka bp). These dates are almost identical to new AMS dates from l'Arbreda cave in Catalunya on the same cultural horizon (average 38??5 ?? 1??0 ka bp) and are significantly older than the earliest dates for Aurignacian industries in the Aquitaine and in other parts of Central and Western Europe. ?? 1989.

  6. Revision of Fontes & Garnier's model for the initial 14C content of dissolved inorganic carbon used in groundwater dating

    USGS Publications Warehouse

    Han, Liang-Feng; Plummer, L. Niel

    2013-01-01

    The widely applied model for groundwater dating using 14C proposed by Fontes and Garnier (F&G) (Fontes and Garnier, 1979) estimates the initial 14C content in waters from carbonate-rock aquifers affected by isotopic exchange. Usually, the model of F&G is applied in one of two ways: (1) using a single 13C fractionation factor of gaseous CO2 with respect to a solid carbonate mineral, εg/s, regardless of whether the carbon isotopic exchange is controlled by soil CO2 in the unsaturated zone, or by solid carbonate mineral in the saturated zone; or (2) using different fractionation factors if the exchange process is dominated by soil CO2 gas as opposed to solid carbonate mineral (typically calcite). An analysis of the F&G model shows an inadequate conceptualization, resulting in underestimation of the initial 14C values (14C0) for groundwater systems that have undergone isotopic exchange. The degree to which the 14C0 is underestimated increases with the extent of isotopic exchange. Examples show that in extreme cases, the error in calculated adjusted initial 14C values can be more than 20% modern carbon (pmc). A model is derived that revises the mass balance method of F&G by using a modified model conceptualization. The derivation yields a “global” model both for carbon isotopic exchange dominated by gaseous CO2 in the unsaturated zone, and for carbon isotopic exchange dominated by solid carbonate mineral in the saturated zone. However, the revised model requires different parameters for exchange dominated by gaseous CO2 as opposed to exchange dominated by solid carbonate minerals. The revised model for exchange dominated by gaseous CO2 is shown to be identical to the model of Mook (Mook, 1976). For groundwater systems where exchange occurs both in the unsaturated zone and saturated zone, the revised model can still be used; however, 14C0 will be slightly underestimated. Finally, in carbonate systems undergoing complex geochemical reactions, such as oxidation of

  7. 14C dates from Tel Rehov: Iron-Age chronology, pharaohs, and Hebrew kings.

    PubMed

    Bruins, Hendrik J; van der Plicht, Johannes; Mazar, Amihai

    2003-04-11

    Stratified radiocarbon dates provide an independent chronological link between archaeological layers and historical data. The invasion by Pharaoh Shoshenq I (Shishak) is a key historical synchronism, approximately 925 B.C.E., mentioned in both Egyptian inscriptions and the Hebrew Bible. The list of places raided by Shoshenq, mentioned at Karnak (Egypt), includes Rehov (Israel). The site yielded a consistent series of radiocarbon dates from the 12th to 9th century B.C.E. Our results (i) suggest a revised Iron-Age chronology; (ii) date an archaeological stratum to Shoshenq's campaign; (iii) indicate the similarity of "Solomonic" and "Omride" pottery; and (iv) provide correlation with Greece and Cyprus.

  8. Holocene marine 14C reservoir age variability: Evidence from 230Th-dated corals in the South China Sea

    NASA Astrophysics Data System (ADS)

    Yu, Kefu; Hua, Quan; Zhao, Jian-xin; Hodge, Ed; Fink, David; Barbetti, Mike

    2010-07-01

    The South China Sea (SCS) is well connected with the western Pacific and influenced by the East Asian monsoon. We have examined temporal variations in radiocarbon marine reservoir ages (R) and regional marine reservoir corrections (ΔR) of the SCS during the Holocene using paired measurements of AMS 14C and TIMS 230Th on 20 pristine corals. The results show large fluctuations in both R and ΔR values over the past 7500 years (yrs) with two distinct plateaus during 7.5-5.6 and 3.5-2.5 thousand calendar years before present (cal ka BP). The respective weighted mean ΔR values of these plateaus are 151 ± 85 and 89 ± 59 yrs, which are significantly higher than its modern value of -23 ± 52 yrs. This suggests that using a constant modern ΔR value to calibrate 14C dates of the SCS marine samples will introduce additional errors to the calibrated ages. Our results provide the first database for the Holocene R and ΔR values of the SCS for improved radiocarbon calibration of marine samples. We interpret the two ΔR plateaus as being related to two intervals with weakened El Niño - Southern Oscillation (ENSO) and intensified East Asian summer monsoon (EASM). This is because the 14C content of the SCS surface water is controlled by both the 14C concentration of the Pacific North Equatorial Current (NEC) which is in turn influenced by ENSO-induced upwelling along the Pacific equator and vertical upwelling within the SCS as a result of moisture transportation to midlatitude region to supply the EASM rainfall.

  9. Angel's share combats wine fraud: (14)C dating of wine without opening the bottle.

    PubMed

    Fahrni, Simon M; Fuller, Benjamin T; Southon, John R

    2015-09-01

    The problem of fraud continues to plague the wine industry, and detecting cases where the original bottle has been refilled with an inferior vintage is especially difficult. A novel noninvasive procedure presented here relies on radiocarbon dating the so-called angel's share: the trace amounts of ethanol and other gases that diffuse into and through the cork as bottled wine ages and matures. These are collected by applying a vacuum to the top of the bottle and cryo-trapping the extracted gas, leaving the liquid contents untouched. Vintage verification is therefore possible without exposing the liquid contents to the atmosphere, which may render a bottle costing tens of thousands of dollars worthless for later resale and consumption. The method also has a potential for stable isotope ratio as well as chemical analysis to find indications for fraud or spoilage of fine and rare wines as well as other liquids with cork stoppers.

  10. Angel's share combats wine fraud: (14)C dating of wine without opening the bottle.

    PubMed

    Fahrni, Simon M; Fuller, Benjamin T; Southon, John R

    2015-09-01

    The problem of fraud continues to plague the wine industry, and detecting cases where the original bottle has been refilled with an inferior vintage is especially difficult. A novel noninvasive procedure presented here relies on radiocarbon dating the so-called angel's share: the trace amounts of ethanol and other gases that diffuse into and through the cork as bottled wine ages and matures. These are collected by applying a vacuum to the top of the bottle and cryo-trapping the extracted gas, leaving the liquid contents untouched. Vintage verification is therefore possible without exposing the liquid contents to the atmosphere, which may render a bottle costing tens of thousands of dollars worthless for later resale and consumption. The method also has a potential for stable isotope ratio as well as chemical analysis to find indications for fraud or spoilage of fine and rare wines as well as other liquids with cork stoppers. PMID:26258285

  11. The contribution of 14C AMS dating to the Greater Angkor archaeological project

    NASA Astrophysics Data System (ADS)

    Zoppi, U.; Barbetti, M.; Fletcher, R.; Hua, Q.; Chhem, R. K.; Pottier, C.; Watanasak, M.

    2004-08-01

    For well over five centuries, the Khmer kingdom ruled over a vast territory, including most of what is now known as Cambodia, Thailand, Vietnam and Laos. Between the 9th and 14th century AD, the Khmer Kings developed the Angkor area into a remarkable administrative and religious centre for their society. According to new estimates by the Greater Angkor Project, the entire urban complex of the capital city covered about 1000 square km making it probably the largest archaeological site in the world. Great stone temples and some other monumental structures and earthworks are the only visible remains of this fascinating civilisation. Thankfully, there is a substantial on-going multinational effort to preserve and restore what is left and in 1992 UNESCO (United Nations Educational Scientific and Cultural Organisation) declared Angkor a World Heritage Site. This paper presents two particular aspects of the Greater Angkor Project where radiocarbon dating by AMS specifically added to our knowledge of the history of this ancient capital city.

  12. Climate and demography in early prehistory: using calibrated (14)C dates as population proxies.

    PubMed

    Riede, Felix

    2009-04-01

    Although difficult to estimate for prehistoric hunter-gatherer populations, demographic variables-population size, density, and the connectedness of demes-are critical for a better understanding of the processes of material culture change, especially in deep prehistory. Demography is the middle-range link between climatic changes and both biological and cultural evolutionary trajectories of human populations. Much of human material culture functions as a buffer against climatic changes, and the study of prehistoric population dynamics, estimated through changing frequencies of calibrated radiocarbon dates, therefore affords insights into how effectively such buffers operated and when they failed. In reviewing a number of case studies (Mesolithic Ireland, the origin of the Bromme culture, and the earliest late glacial human recolonization of southern Scandinavia), I suggest that a greater awareness of demographic processes, and in particular of demographic declines, provides many fresh insights into what structured the archaeological record. I argue that we cannot sideline climatic and environmental factors or extreme geophysical events in our reconstructions of prehistoric culture change. The implications of accepting demographic variability as a departure point for evaluating the archaeological record are discussed.

  13. The next chapter of direct phytolith 14C dating: debunking the myth of occluded photosynthetic carbon exclusivity

    NASA Astrophysics Data System (ADS)

    Santos, G.; Harutyunyan, A.; Alexandre, A. E.; Reyerson, P. E.; Gallagher, K. L.; Isabelle, B. D.

    2014-12-01

    Radiocarbon dating of carbon (C) encapsulated in phytoliths (phytC) is currently used in many Earth Science disciplines for absolute chronologies and paleoclimatic reconstructions; however, the usefulness of phytC has been hampered by inadequate extraction methods[1] and uncertainties regarding its origin as purely photosynthetic [2,3,4]. An early investigation measuring isotopes from Gramineae spp. grown in free-air C enrichment experiments (FACE), showed that part of of its phytC is from a non-photosynthetic source, thus indicating a dual origin[5]. To demonstrate that non-photosynthetic sources within phytC could be from soil C stocks, we measured 14C-AMS phytC extracted from a set of Sorghum bicolor growing on known 14C and d13C bulk substrates and hydroponic solutions. The phytolith concentrates and a silica blank were extracted at UCI, CEREGE and Wisconsin using an improved protocol [1,2]. We also measured CO2 fluxes and isotopic signatures of microbial respiration, percentage of biomass and phytolith extracts produced, and isotopic signatures of the local air and bulk-plant during the growing season of 2012. This allowed comparison of the belowground substrate and nutrient C contributions to phytC 14C results. Meanwhile, NanoSIMS analyses of phytolith polished sections was used to locate phytC in the phytolith siliceous structure [6]. These results will be shown and discussed. [1] Corbineau et al. 2013 R. Paleobot. Palyn. 197: 179 [2] Santos et al. 2010 T. Radiocarbon 52:113 [3] Santos et al. 2012a Biogeosci. 9:1873 [4] Santos et al. 2012b Biogeosci. Discussion 9:C6114 [5] Reyerson et al. 2013 AGU Fall meeting 2013 (Abstract ID: 1803125). [6] Alexandre, et al., submitted.

  14. First accelerator mass spectrometry {sup 14}C dates documenting contemporaneity of nonanalog species in late Pleistocene mammal communities

    SciTech Connect

    Stafford, T.W. Jr.; Semken, H.A. Jr.; Graham, R.W.; Klippel, W.F.; Markova, A.; Smirnov, N.G.; Southon, J.

    1999-10-01

    Worldwide late Pleistocene terrestrial mammal faunas are characterized by stratigraphic associations of species that now have exclusive geographic ranges. These have been interpreted as either taphonomically mixed or representative of communities that no longer exist. Accelerator mass spectrometry {sup 14}C dates (n = 60) on single bones of stratigraphically associated fossil micromammals from two American and two Russian sites document for the first time that currently allopatric mammals occurred together between 12,000 and 22,000 yr B.P. on two continents. The existence of mammal communities without modern analogs demonstrates that Northern Hemisphere biological communities are ephemeral and that many modern biomes are younger than 12 ka. Future climate change may result in new nonanalog communities.

  15. C:N:P Molar Ratios, Sources and 14C Dating of Surficial Sediments from the NW Slope of Cuba

    PubMed Central

    de la Lanza Espino, Guadalupe; Soto, Luis A.

    2015-01-01

    The surficial sediments recovered from 12 sites located near the channel axis of the Florida Straits and the lower slope off NW Cuba were analyzed for total organic carbon (TOC), nitrogen (TN), phosphorus (TP), elemental C:N:P ratios, C and N isotopic values, and 14C dating. The depth profiles of TOC, TN, and TP (0-18 cm) displayed a downcore trend and a significant variation. The TOC values were low (0.15 to 0.62%; 66 to 516 µmol g-1). Sites near the island’s lower slope had lower TOC average concentrations (158-333 µmol g-1) than those closer to the channel axis (averaging 341-516 µmol g-1; p <0.05). The TN concentrations near the lower slope attained 0.11% (80 µmol g-1), whereas, towards the channel axis, they decreased to 0.07% (55 µmol g-1; p<0.05). The C:N ratios ranged from 1.9 to 10.2. The mean molar C:N ratio (5.4) indicated a marine hemipelagic deposition. The TP was lower at sites near the lower slope (38.4 to 50.0 µmol g-1; 0.12% to 0.16%) than those near the channel axis (50.0 to 66 µmol g-1; 0.15 to 0.21%). C:P fluctuated from 7.7 to 14.1 in the surficial sediment layer. The bulk organic δ13Corg and δ15N values confirmed pelagic organic sources, and the 14C dating revealed that the sediments were deposited during the Holocene (1000-5000 yr BP). We suggest that the hydrodynamic conditions in the Straits influence vertical and advective fluxes of particulate organic material trapped in the mixed-layer, which reduces the particulate matter flux to the seabed. PMID:26110791

  16. C:N:P Molar Ratios, Sources and 14C Dating of Surficial Sediments from the NW Slope of Cuba.

    PubMed

    de la Lanza Espino, Guadalupe; Soto, Luis A

    2015-01-01

    The surficial sediments recovered from 12 sites located near the channel axis of the Florida Straits and the lower slope off NW Cuba were analyzed for total organic carbon (TOC), nitrogen (TN), phosphorus (TP), elemental C:N:P ratios, C and N isotopic values, and 14C dating. The depth profiles of TOC, TN, and TP (0-18 cm) displayed a downcore trend and a significant variation. The TOC values were low (0.15 to 0.62%; 66 to 516 µmol g(-1)). Sites near the island's lower slope had lower TOC average concentrations (158-333 µmol g(-1)) than those closer to the channel axis (averaging 341-516 µmol g(-1); p <0.05). The TN concentrations near the lower slope attained 0.11% (80 µmol g(-1)), whereas, towards the channel axis, they decreased to 0.07% (55 µmol g(-1); p<0.05). The C:N ratios ranged from 1.9 to 10.2. The mean molar C:N ratio (5.4) indicated a marine hemipelagic deposition. The TP was lower at sites near the lower slope (38.4 to 50.0 µmol gv; 0.12% to 0.16%) than those near the channel axis (50.0 to 66 µmol g(-1); 0.15 to 0.21%). C:P fluctuated from 7.7 to 14.1 in the surficial sediment layer. The bulk organic δ13Corg and δ15N values confirmed pelagic organic sources, and the 14C dating revealed that the sediments were deposited during the Holocene (1000-5000 yr BP). We suggest that the hydrodynamic conditions in the Straits influence vertical and advective fluxes of particulate organic material trapped in the mixed-layer, which reduces the particulate matter flux to the seabed.

  17. Holocene environmental changes of the Godavari Delta, east coast of India, inferred from sediment core analyses and AMS 14C dating

    NASA Astrophysics Data System (ADS)

    Nageswara Rao, Kakani; Saito, Yoshiki; Nagakumar, K. Ch. V.; Demudu, G.; Basavaiah, N.; Rajawat, A. S.; Tokanai, Fuyuki; Kato, Kazuhiro; Nakashima, Rei

    2012-11-01

    The Godavari delta in India is a major wave dominated delta of a tropical monsoon-fed river with one of the largest sediment deliveries in the world. While several earlier studies revealed the nature of landforms and progradation style of the delta plain during the Holocene, the present study attempts to reconstruct the depositional environment of the Godavari delta through the analysis of core sediment and accelerator mass spectrometry (AMS) 14C dating from three locations. The sediment core obtained from a 27.06 m deep borehole at Vilasavilli (VV) supported by 13 14C dates revealed the complete succession of the Holocene deposits unconformably overlying Pleistocene sediments. Textural analysis indicates the lower upward-fining and upper upward-coarsening units in the Holocene succession. Total organic carbon (TOC)/total nitrogen (TN) ratios of > 20; high content of TOC around 1.5-2.5%; and black to very dark colored sediment throughout the muddy part of the Holocene succession indicated a predominance of terrigenous material. The VV core and two other cores (DRP and SDG) with 14 14C dates indicated the thickness of the Holocene sediments in the Godavari delta plain is in the order of ~ 20-50 m, unconformably resting on a seaward sloping Pleistocene basement. Sediment facies and sediment accumulation of the three cores show the evolution of the Godavari delta. A transgressive phase is recognized as an upward-fining succession in the VV core, 8.4-8.0 cal ky BP, followed by a low accumulation period, 8.0-6.3 cal ky BP including the Holocene maximum transgression in the Godavari delta. After 6.3 cal ky BP, areas of high accumulation rates have changed laterally between the central part (VV site) and southwestern part (DRP and SDG sites), may be controlled by the location of river-mouths. Further analysis coupled with 11 more 14C dates compiled from earlier works indicated that the strandplain of the Godavari delta prograded seaward in three stages, and that the rate

  18. Solar modulation of cosmic ray intensity and solar flare events inferred from (14)C contents in dated tree rings

    NASA Technical Reports Server (NTRS)

    Fan, C. Y.; Chen, T. M.; Yun, S. X.; Dai, K. M.

    1985-01-01

    The delta 14C values in 42 rings of a white spruce grown in Mackenzie Delta was measured as a continuing effort of tracing the history of solar modulation of cosmic ray intensity. The delta 14C values in six rings were measured, in search of a 14C increase due to two large solar flares that occurred in 1942. The results are presented.

  19. Palaeomagnetic intensities from 14C-dated lava flows on the Big Island, Hawaii: 0-21 kyr

    USGS Publications Warehouse

    Pressling, Nicola; Laj, Carlo; Kissel, Catherie; Champion, Duane E.; Gubbins, David

    2006-01-01

    Thellier–Thellier experiments were carried out on 216 lava samples collected by the USGS on the Big Island. 35 individual flows from the Kilauea, Mauna Loa and Hualalai volcanoes are represented and independent radiocarbon dating of the flows yields absolute ages ranging from 290 to 20,240 yrs old. The palaeomagnetic analysis was carried out at the Laboratoire des Sciences du Climat et de l'Environnement in Gif-sur-Yvette, France, in two custom built, large capacity furnaces that have been specifically designed to minimise oxidation. The temperature steps were adapted to accommodate the characteristic loss of magnetisation at low temperatures seen in the Curie balance results and the use of half-size samples allowed secondary experiments to be carried out where necessary. The strict PICRIT-03 selection criteria were rigorously applied to the data and a high success rate of 53% has been achieved on a sample level. The flow averaged results almost double the existing 14C-dated palaeointensity dataset for this time window and confirm a period of high intensity over the past 4 kyr preceded by a period in which the dipole moment was weaker. However, the values attained in this study are on average higher than previously published data; reliability of these values is discussed.

  20. New insights into the radiocarbon calibration based on 14C and U-Th dating of corals drilled offshore Tahiti (IODP Expedition #310)

    NASA Astrophysics Data System (ADS)

    Durand, Nicolas; Deschamps, Pierre; Bard, Edouard; Hamelin, Bruno; Camoin, Gilbert; Thomas, Alexander L.; Henderson, Gideon M.; Yokoyama, Yusuke

    2010-05-01

    Beyond the high-precision tree-ring calibration, the fossil corals are the most reliable archive that can be used to calibrate the radiocarbon time scale. In this contribution, we present a new radiocarbon dataset based on paired 14C and U-Th dating of fossil shallow-water tropical corals drilled offshore Tahiti during the IODP Expedition 310 'Tahiti Sea-Level'. Before 14C and U-Th analyses, rigorous screening criteria have been applied in order to select pristine aragonitic coral skeletons and avoid those displaying any post-mortem diagenesis that alters original ages. In particular, we made a significant effort to improve detection and quantification of very small amount of secondary calcite in the aragonitic coral lattice using X-ray diffraction measurements [1]. In addition, we apply a strict screening criterion based on δ234U. However, the new Tahiti dataset allow to refine the previous tolerance ranges previously adopted. More than 60 radiocarbon dates were processed at the Laboratoire de Mesure du Carbone 14 (Saclay, France) with the ARTEMIS AMS facility. This new Tahiti record provides new data to the radiocarbon calibration for two distinct time windows: for the interval between 29,200 and 36,200 years BP and for the last deglaciation period, with especially, a higher resolution (40 data) for the 14,000 - 16,000 years BP time interval. These new data extend the previous Tahiti record beyond 13,900 years BP which was the oldest U-Th age obtained on cores drilled onshore in the modern Tahiti barrier reef [2, 3]. These new results are compared with 14C chronologies from other corals, those of Barbados [4, 5] and those from other Pacific islands (Mururoa, Vanuatu, Marquesas, Christmas), and from the Cariaco Basin sediment [6, 7], the Iberian Margin sediment [8, 9] and the Bahamian speleothem [10] records. The new 14C dataset from the corals drilled offshore Tahiti allows to validate the precision and accuracy of other records either directly dated by U-Th or

  1. Bayesian integration of radioisotope dating (210Pb, 137Cs, 241Am, 14C) and an 18-20th century mining history of Brotherswater, English Lake District

    NASA Astrophysics Data System (ADS)

    Schillereff, Daniel; Chiverrell, Richard; Macdonald, Neil; Hooke, Janet; Welsh, Katharine; Piliposyan, Gayane; Appleby, Peter

    2014-05-01

    ), pointing to a hillslope clearance event. A widespread concurrent hillslope gullying phase in northwest England triggering enhanced soil erosion is thus the most likely explanation, as the presence of old carbon is a known issue for lakes in the region at this time. Applying a Bayesian age-depth modelling protocol is able to account for these age-reversals with some success. However, the greatest uncertainty in the model occurs across the 1700 -1900 A.D. time window as the radiocarbon percentages offer multiple age solutions due to fluctuating atmospheric 14C concentrations from fossil fuel emissions. We address this issue by incorporating into the model geochemical markers in the sediment core related to local point-source Pb mining of known-age; the most-likely age-depth curve is subsequently much more definitively resolved. Usefully, these mining-derived chronological markers bridge the temporal gap between artificial radionuclide and conventional radiocarbon dating which is a common problem in palaeolimnology. These distinctive geochemical mining profiles (Pb, Zn, Cu) have been mapped across all cores, enabling precise core correlation and confident transferral of the age-depth model, and reveal highly spatially variable sediment accumulation rates. This has enabled more accurate sediment and carbon budgets to be calculated and some insight into palaeoflood frequency to be obtained from the Brotherswater sediment sequence.

  2. Dating and tracing groundwater resources in central Québec with noble gases, 14C and water chemistry

    NASA Astrophysics Data System (ADS)

    Vautour, G.; Pinti, D. L.; Castro, M. C.; Barbecot, F.; Larocque, M.; Hall, C. M.

    2011-12-01

    Canada water supply is derived mainly from lakes and rivers while groundwater accounts for less than 30% of the demand. Climatic and anthropogenic stress is endangering this natural resource. This study is part of a Quebec-funded program to characterize groundwater resources from major basins to ensure adequate water quality and management. The Bécancour River catchment area, 200 km NE of Montréal, is studied for this purpose. The region extends from the Appalachian Mts. down to the St. Lawrence River. Water chemistry shows the occurrence of Ca,Na-HCO3, Ca-HCO3, Na-HCO3 and NaCl waters, mainly recharged in the Appalachians and flowing to the St. Lawrence River. Aquifers are also recharged locally through Quaternary sandy deposits throughout the plain. Main aquifers are found both in unconfined and confined Quaternary sands intercalated with clays, and also locally in fractured Ordovician carbonates. To identify groundwater flow paths and to estimate water residence times, a multi-isotopic study involving noble gases, 14C and U, Th isotopes was initiated. Noble gas preliminary results were obtained on two transects, one along the downward flow path and the second perpendicular to the first, along a deeper sinclinorium with NaCl waters (TDS =170-705 mg/L). The 3He/4He ratios versus 4He/20Ne clearly points to mixing between three water bodies. The first has been recharged very recently displaying a near-atmospheric ratio of 0.79 Ra (Ra=atmospheric 3He/4He ratio of 1.386 x 10-6) and a 4He/20Ne of 0.2 close to the Air Saturated Water value, i.e. the ratio of atmospheric He and Ne dissolved in groundwater. The second water body is slightly older and shows the occurrence of tritiogenic 3He (3Hetri) excesses up to 1.07x10-13 ccSTP/g. These waters are found along the transect parallel to the main flow path. Using a local tritium decay curve and measured 3Hetri, an age of 19-20 years is suggested. The third water body contains large amounts of radiogenic 4He produced by U

  3. Validation of OSL and 14C dating of initial soils in Late-Holocene polycyclic drift-sand deposits (Weerterbergen, S.E. Netherlands)

    NASA Astrophysics Data System (ADS)

    van Mourik, J. M.; Schilder, M. L. M.; Wallinga, J.

    2009-04-01

    Late glacial aeolian coversand dominates the surface geology of the eastern part of the province Noord-Brabant (Netherlands). During prehistoric and early historic time, forest grazing, wood cutting and shifting cultivation gradually transformed natural forest into heath land. Subsequently the use of the heath for the production of organic manure during the period of plaggen agriculture (from early Middle Ages to the invention of chemical fertilizers around 1900 AD) resulted in the comeback of sand drifting and locally the coversand landscape transformed into a driftsand landscape with characteristic new landforms and soils. Polycyclic driftsand deposits are paleoecological records of alternating instable (sand drifting) and stable (soil formation) phases in landscape development. Interpretation of paleoecological information, derived from these records, requires accurate knowledge of the geochronology. Traditionally radiocarbon dating was applied on SOM (soil organic matter), extracted from humic AE horizons of buried initial soils (micropodzols), developed in driftsand beds. In polycyclic driftsand sequences, micropozols indicate a stable period in landscape development. One of the research questions in driftsand landscapes was related to the distribution and age of micropodzols: Are they the result of just local or more regional events in landscape evolution? The calibrated 14C ages of seven selected of extracted humic acids of micropozols range from 340 - 1950 AD. Based on these results, the alternation of instable and stable periods in landscape development seems to be controlled by local events. But to understand the development of polycyclic sequences, we need more information than just the 14C ages of micropodzols. Every cycle of a polycyclic sequence reflects a period of landscape instability (deposition) and landscape stability (soil development). A 14C based chronological framework does not allow the indicate the available time for deposition and for

  4. Using an independent geochronology based on palaeomagnetic secular variation (PSV) and atmospheric Pb deposition to date Baltic Sea sediments and infer 14C reservoir age

    NASA Astrophysics Data System (ADS)

    Lougheed, Bryan C.; Snowball, Ian; Moros, Matthias; Kabel, Karoline; Muscheler, Raimund; Virtasalo, Joonas J.; Wacker, Lukas

    2012-05-01

    Dating of sediment cores from the Baltic Sea has proven to be difficult due to uncertainties surrounding the 14C reservoir age and a scarcity of macrofossils suitable for dating. Here we present the results of multiple dating methods carried out on cores in the Gotland Deep area of the Baltic Sea. Particular emphasis is placed on the Littorina stage (8 ka ago to the present) of the Baltic Sea and possible changes in the 14C reservoir age of our dated samples. Three geochronological methods are used. Firstly, palaeomagnetic secular variations (PSV) are reconstructed, whereby ages are transferred to PSV features through comparison with varved lake sediment based PSV records. Secondly, lead (Pb) content and stable isotope analysis are used to identify past peaks in anthropogenic atmospheric Pb pollution. Lastly, 14C determinations were carried out on benthic foraminifera (Elphidium spec.) samples from the brackish Littorina stage of the Baltic Sea. Determinations carried out on smaller samples (as low as 4 μg C) employed an experimental, state-of-the-art method involving the direct measurement of CO2 from samples by a gas ion source without the need for a graphitisation step - the first time this method has been performed on foraminifera in an applied study. The PSV chronology, based on the uppermost Littorina stage sediments, produced ten age constraints between 6.29 and 1.29 cal ka BP, and the Pb depositional analysis produced two age constraints associated with the Medieval pollution peak. Analysis of PSV data shows that adequate directional data can be derived from both the present Littorina saline phase muds and Baltic Ice Lake stage varved glacial sediments. Ferrimagnetic iron sulphides, most likely authigenic greigite (Fe3S4), present in the intermediate Ancylus Lake freshwater stage sediments acquire a gyroremanent magnetisation during static alternating field (AF) demagnetisation, preventing the identification of a primary natural remanent magnetisation for

  5. Summed Probability Distribution of 14C Dates Suggests Regional Divergences in the Population Dynamics of the Jomon Period in Eastern Japan

    PubMed Central

    Habu, Junko; Kobayashi, Kenichi; Madella, Marco

    2016-01-01

    Recent advances in the use of summed probability distribution (SPD) of calibrated 14C dates have opened new possibilities for studying prehistoric demography. The degree of correlation between climate change and population dynamics can now be accurately quantified, and divergences in the demographic history of distinct geographic areas can be statistically assessed. Here we contribute to this research agenda by reconstructing the prehistoric population change of Jomon hunter-gatherers between 7,000 and 3,000 cal BP. We collected 1,433 14C dates from three different regions in Eastern Japan (Kanto, Aomori and Hokkaido) and established that the observed fluctuations in the SPDs were statistically significant. We also introduced a new non-parametric permutation test for comparing multiple sets of SPDs that highlights point of divergences in the population history of different geographic regions. Our analyses indicate a general rise-and-fall pattern shared by the three regions but also some key regional differences during the 6th millennium cal BP. The results confirm some of the patterns suggested by previous archaeological studies based on house and site counts but offer statistical significance and an absolute chronological framework that will enable future studies aiming to establish potential correlation with climatic changes. PMID:27128032

  6. Summed Probability Distribution of 14C Dates Suggests Regional Divergences in the Population Dynamics of the Jomon Period in Eastern Japan.

    PubMed

    Crema, Enrico R; Habu, Junko; Kobayashi, Kenichi; Madella, Marco

    2016-01-01

    Recent advances in the use of summed probability distribution (SPD) of calibrated 14C dates have opened new possibilities for studying prehistoric demography. The degree of correlation between climate change and population dynamics can now be accurately quantified, and divergences in the demographic history of distinct geographic areas can be statistically assessed. Here we contribute to this research agenda by reconstructing the prehistoric population change of Jomon hunter-gatherers between 7,000 and 3,000 cal BP. We collected 1,433 14C dates from three different regions in Eastern Japan (Kanto, Aomori and Hokkaido) and established that the observed fluctuations in the SPDs were statistically significant. We also introduced a new non-parametric permutation test for comparing multiple sets of SPDs that highlights point of divergences in the population history of different geographic regions. Our analyses indicate a general rise-and-fall pattern shared by the three regions but also some key regional differences during the 6th millennium cal BP. The results confirm some of the patterns suggested by previous archaeological studies based on house and site counts but offer statistical significance and an absolute chronological framework that will enable future studies aiming to establish potential correlation with climatic changes. PMID:27128032

  7. The necessity of sample quality assessment in 14C AMS dating: The case of Cova des Pas (Menorca - Spain)

    NASA Astrophysics Data System (ADS)

    Van Strydonck, Mark; Boudin, Mathieu; Guerrero Ayuso, Víctor M.; Calvo, Manuel; Fullola, Josep M.; Àngeles Petit, M.

    2010-04-01

    The Cova des Pas cave is a karstic cave in the cliffs of the Barranc (canyon) de Trebalúger. It is a small cave only 6.5 m deep, 4.5 m wide and 1.7 m high. Yet more than 70 burials, in foetal position, from the Early Iron Age were found in this small cave. The conservation of the archaeological remains was very unusual. Not only wood, ropes and other plant material was found, but also remains of body tissue, hair and leather. In spite of the remarkable preservation of the bodies and artefacts, the state of conservation of the bone material was very bad. The bones contained little and heavily deteriorated collagen and the organic plant material was very fragile. The special environmental conditions of the cave are the cause of these unusual preservation conditions. Although the cave is situated in a limestone cliff, the soil of the cave is very acid. Unexpectedly bad sample quality seemed to be the major drawback for AMS radiocarbon dating on hair, wood, ropes and bone collagen, as well as on bio-apatite.

  8. Multiple dating approach (14C, U/Th and 36Cl) of tsunami-transported reef-top megaclasts on Bonaire (Leeward Antilles) - potential and current limitations

    NASA Astrophysics Data System (ADS)

    Rixhon, Gilles; May, Simon Matthias; Engel, Max; Mechernich, Silke; Keulertz, Rebecca; Schroeder-Ritzrau, Andrea; Fohlmeister, Jens; Frank, Norbert; Dunai, Tibor; Brueckner, Helmut

    2016-04-01

    Coastal hazard assessment depends on reliable information on the magnitude and frequency of past high-energy wave events (EWE: tsunamis, storms). For this purpose onshore sedimentary records represent promising geo-archives for the mid- and late-Holocene EWE history. In comparison to fine-grained sediments which have been extensively studied in the recent past, supralittoral megaclasts are less investigated, essentially due to the difficulties related to the dating of corresponding depositional events, and thus their limited value for inferring the timing of major events. On Bonaire (Leeward Antilles, Caribbean), supratidal coarse-clast deposits form prominent landforms all around the island. Fields of large boulders (up to 150 t) are among the best-studied reef-top megaclasts worldwide. Transport by Holocene tsunamis is assumed at least for the largest boulders (Engel and May, 2012). Although a large dataset of 14C and electron spin resonance (ESR) ages is available for major coral rubble ridges and ramparts, showing some age clusters during the Late Holocene, it is still debated whether these data reflect the timing of major depositional/transport event(s), and how these data sets are biased by reworking of coral fragments. In addition, different processes may be responsible for the deposition of the coral rubble ridges and ramparts (storm) and the solitary megaclasts (tsunami). As an attempt to overcome the current challenges for dating the dislocation of the megaclasts, three distinct dating methods were implemented: (i) 14C dating of boring bivalves (Lithophaga) attached to the boulders; (ii) uranium-series (U/Th) dating of post-depositional, secondary calcitic flowstone at the underside of the boulders; and (iii) surface exposure dating of overturned boulders via 36Cl concentration measurements in corals. The three 14C datings yield age estimates >37 ka, i.e. most probably beyond the applicability of the method, which sheds doubt on the usefulness of this

  9. The Pech-de-l'Azé I Neandertal child: ESR, uranium-series, and AMS 14C dating of its MTA type B context.

    PubMed

    Soressi, M; Jones, H L; Rink, W J; Maureille, B; Tillier, A-M

    2007-04-01

    The Pech-de-l'Azé I skull and mandible are included in the juvenile Neandertal remains from Europe. However, some preserved features in the cranial skeleton seem to distinguish the specimen from other Neandertal children. Unfortunately, the stratigraphic position and dating of this child has never been clear. Our recent work on unpublished archives show that the Pech-de-l'Azé I Neandertal child was discovered at the bottom of layer 6, attributed to the Mousterian of Acheulean tradition type B. These skull and mandible are the first diagnostic human remains (aside from an isolated tooth) attributed to the Mousterian of Acheulian tradition (MTA) type B. Consequently, we confirm that Neandertals were the makers of this Mousterian industry, which is characterized by unusual high frequencies of Upper Paleolithic type tools, elongated blanks and blades. We were able to date the context of the hominid remains by dating layer 6 and the layers above and beneath it using ESR, coupled ESR/(230)Th/(234)U (coupled ESR/U-series), and AMS (14)C. Coupled ESR/U-series results on 16 mammalian teeth constrain the age of the uppermost layer 7 to 41-58ka, and layer 6 to 37-51ka. The wide spread in each age estimate results mainly from uncertainties in the gamma-dose rate. These ages are concordant with AMS (14)C ages of two bones coming from the top of layer 6, which provide dates of about 41.7-43.6ka cal BP. A combination of stratigraphic arguments and dating results for layers 6 and 7 show that the Neandertal child cannot be older than 51ka or younger than 41ka. The lowermost layer 4 is shown to be older than 43ka by the principle of superposition and ESR dating in the immediately overlying layer 5. This study shows that the MTA type B had been manufactured by Neandertals before the arrival of anatomically modern humans in the local region. Additionally, by providing a firm chronological framework for the specific morphometric the features of Pech-de-l'Azé I Neandertal child, this

  10. High Resolution δ18O and δ13C Records of AMS 14C Dated Stalagmites From Jinlun and Yilingyan Caves in Guangxi, China: Climate Variability and Controlling Factors in the Monsoonal Region During the Past 2300 Years

    NASA Astrophysics Data System (ADS)

    Li, H. C.; Lien, W. Y.; Mii, H. S.; Jiang, G. H.; Chou, C. Y.; Chou, P. J.

    2015-12-01

    Jinlun Cave in Mashan County and Yilingyan Cave in Wuming County are ~120km and ~60km north of Nanning in Guangxi Province under influence of both Indian Monsoon and North Western Pacific Monsoon. Several stalagmites have been dated by AMS 14C dating method since 230Th/U is not applicable due to very low U contents. Twenty (20) AMS 14C dates on Stalagmite JL20131005-10 (10-cm long) show "Bomb carbon curve", spanning the past 60 years. Lamination counting further confirms the chronology. Thirty nine (39) AMS 14C dates on Stalagmite JL20131005-12 (33-cm long) reveal 2300-year continuous growth. Stalagmite YLY20130727-12 (10-cm long) from Yilingyan Cave covers a continuous record of past 2300 years. All studied stalagmites in the caves contain low dead carbon fractions. The annual resolution δ18O and δ13C records obtained from the stalagmites allow us to compare the stalagmite δ18O records with the instrumental rainfall and temperature records, Pacific Decadal Oscillation (PDO), Southern Oscillation Index (SOI), and Sunspot variation, etc. The δ18O and δ13C records exhibit relatively good correlation throughout the time, indicating climatic control on vegetation change. Based on the high-resolution δ18O and δ13C records, we interpret that dry climatic conditions and poor vegetation coverage during periods of AD1880~1850, 1700~1600, 1460~1320, 1210~1280, 860~750, 540~420, 300~220, and AD100~0 shown by increased δ18O and δ13C. The δ18O and δ13C were strongly depleted during the Medieval Warm Period (MWP between AD900 and AD1100) and Current Warm Period (CWP, since AD1900), reflecting strongly increased East Asian Summer Monsoon. After AD1900, the δ13C decreased about 6‰, perhaps indicating human impact on surface vegetation. The δ18O records from the study area are comparable to the published WX42B δ18O record of Wanxiang Cave (Zhang et al., 2008) except for the period of AD1400~1850. Our study suggests that AMS 14C dating is an alternative method for

  11. Revised 14C dating of ice wedge growth in interior Alaska (USA) to MIS 2 reveals cold paleoclimate and carbon recycling in ancient permafrost terrain

    NASA Astrophysics Data System (ADS)

    Lachniet, Matthew S.; Lawson, Daniel E.; Sloat, Alison R.

    2012-09-01

    Establishing firm radiocarbon chronologies for Quaternary permafrost sequences remains a challenge because of the persistence of old carbon in younger deposits. To investigate carbon dynamics and establish ice wedge formation ages in Interior Alaska, we dated a late Pleistocene ice wedge, formerly assigned to Marine Isotope Stage (MIS) 3, and host sediments near Fairbanks, Alaska, with 24 radiocarbon analyses on wood, particulate organic carbon (POC), air-bubble CO2, and dissolved organic carbon (DOC). Our new CO2 and DOC ages are up to 11,170 yr younger than ice wedge POC ages, indicating that POC is detrital in origin. We conclude an ice wedge formation age between 28 and 22 cal ka BP during cold stadial conditions of MIS 2 and solar insolation minimum, possibly associated with Heinrich event 2 or the last glacial maximum. A DOC age for an ice lens in a thaw unconformity above the ice wedge returned a maximum age of 21,470 ± 200 cal yr BP. Our variable 14C data indicate recycling of older carbon in ancient permafrost terrain, resulting in radiocarbon ages significantly older than the period of ice-wedge activity. Release of ancient carbon with climatic warming will therefore affect the global 14C budget.

  12. 10Be, OSL/IRSL Luminescence and 14C Cross-Dating of a Series of Abandoned Alluvial Surfaces Laterally Offset by the Dead Sea Fault, Jordan

    NASA Astrophysics Data System (ADS)

    Le Beon, M.; Jaiswal, M.; Al-Qaryouti, M.; Moumani, K.; Burr, G. S.; Chen, Y.; Klinger, Y.; Abdelghafoor, M.; Suppe, J.

    2010-12-01

    Active tectonics studies are often limited by the uncertainties in accurately and precisely dating Late Quaternary deposits, especially alluvial deposits that often lack organic matter datable by 14C method. This is the case along the Wadi Araba Fault (WAF), the southernmost segment of the Dead Sea Fault, which delineates the 1000-km long plate boundary between the Arabia plate and the Sinai sub-plate. Geodetic, geomorphic and geologic studies converge to a fault slip rate of 5 ± 2 mm/a. Yet, long-term Late Pleistocene slip rates cover a wide range due to large uncertainties, mostly related to the dispersion of 10Be cosmogenic radionuclide (CRN) ages. The maximum slip rate since ~100 ka is up to a value of 11 mm/a, possibly suggesting significant variations in fault activity with time. In order to reduce the uncertainty on the Late Pleistocene slip rate and draw further conclusions regarding the seismic behavior of the WAF, we targeted one of the sites previously investigated for detailed morphotectonic analysis and 10Be CRN dating and we apply other chronometers, such as Optically stimulated luminescence (OSL) dating on quartz and feldspar minerals, and 14C dating when possible. The site consists in an abandoned bajada composed of four alluvial surface levels, offset by the WAF. We extensively sampled the terraces F2 and F4, which are offset by 160 ± 8 m and 626 ± 37 m, respectively. Our samples are collected from ~50-cm deep pits on the top of the terraces. On F2, we collected one OSL sample downstream from the fault and two upstream, where land snail shells were also found. Preliminary OSL ages agree on ~8 ± 2 ka upstream, also consistent with a 14C date, whereas the OSL age downstream is much older, ~41 ± 4 ka. On F4, we collected three samples downstream from the fault and two upstream. Preliminary OSL ages cluster between ~32 ± 4 ka and ~46 ± 5 ka. Five of the OSL samples have been collected at a similar location to surficial cobbles for 10Be, both on

  13. AMS 14 C dating controlled records of monsoon and Indonesian throughflow variability from the eastern Indian Ocean of the past 32,000 years

    NASA Astrophysics Data System (ADS)

    Li, Z. Y.; Chen, M. T.; Shi, X.; Liu, S.; Wang, H.

    2015-12-01

    Zi-Ye Li a, Min-Te Chen b, Hou-Jie Wang a, Sheng-Fa Liu c, Xue-Fa Shi ca College of Marine Geosciences, Ocean University of China, Qingdao 266100, P.R. Chinab Institute of Applied Geosciences, National Taiwan Ocean University, Keelung, Taiwan 20224, ROCc First Institute of Oceanography, SOA, Qingdao 266100, P.R. China Indonesian throughflow (ITF) is one of the most important currents responsible for transporting heat and moisture from the western Pacific to the Indian Oceans. The ITF is also well-known as effectively in modulating the global climate change with the interactions among ENSO and Asian monsoons. Here we present an AMS 14C dating controlled sea surface temperature (SST) record from core SO184-10043 (07°18.57'S, 105°03.53'E), which was retrieved from 2171m water depth at a north-south depression located at the southeastern offshore area of Sumatera in the eastern Indian Ocean. Based on our high-resolution SST using Mg/Ca analyses based on planktonic foraminifera shells of Globigerinoides ruber and alkenone index, U k'37-SST, oxygen isotope stratigraphy, and AMC 14C age-controls, our records show that, during the past 32,000 years, the SSTs were decreased which imply weaker ITF during Marine Isotope Stage (MIS) 2 and 3. The weaker UTF may respond to strengthened northeast monsoon during the boreal winter. During 21 to 15ka, the southeast monsoon had been stronger and the northeast monsoon was relatively weaker. During 15 to 8ka, rapid sea level rising may allow the opening of the gateways in the Makassar Strait and Lombok Strait that may have further strengthened the ITF. During the early Holocene, the northeast and southeast monsoons seem to be both strengthened. We will discuss the implications of the hydrographic variability and their age uncertainties in this paper during the meeting.

  14. 14C Analysis of protein extracts from Bacillus spores.

    PubMed

    Cappuccio, Jenny A; Falso, Miranda J Sarachine; Kashgarian, Michaele; Buchholz, Bruce A

    2014-07-01

    Investigators of bioagent incidents or interdicted materials need validated, independent analytical methods that will allow them to distinguish between recently made bioagent samples versus material drawn from the archives of a historical program. Heterotrophic bacteria convert the carbon in their food sources, growth substrate or culture media, into the biomolecules they need. The F(14)C (fraction modern radiocarbon) of a variety of media, Bacillus spores, and separated proteins from Bacillus spores was measured by accelerator mass spectrometry (AMS). AMS precisely measures F(14)C values of biological materials and has been used to date the synthesis of biomaterials over the bomb pulse era (1955 to present). The F(14)C of Bacillus spores reflects the radiocarbon content of the media in which they were grown. In a survey of commercial media we found that the F(14)C value indicated that carbon sources for the media were alive within about a year of the date of manufacture and generally of terrestrial origin. Hence, bacteria and their products can be dated using their (14)C signature. Bacillus spore samples were generated onsite with defined media and carbon free purification and also obtained from archived material. Using mechanical lysis and a variety of washes with carbon free acids and bases, contaminant carbon was removed from soluble proteins to enable accurate (14)C bomb-pulse dating. Since media is contemporary, (14)C bomb-pulse dating of isolated soluble proteins can be used to distinguish between historical archives of bioagents and those produced from recent media.

  15. A comparison between conventional and AMS [sup 14]C dates on basal salt marsh peats from coastal Maine. [Accelerator Mass Spectroscopy

    SciTech Connect

    Gehrels, R.W.; Belknap, D.F. . Dept. of Geological Sciences)

    1992-01-01

    This study reports AMS dates from four Maine salt marshes: Webbannet Marsh (Wells), Morse and Sprague River marshes (Phippsburg), and Sanborn Cove marsh (Machiasport). The AMS dates are compared with conventional dates on bulk samples obtained from either the same cores or from other cores at comparable depths. Four AMS dates from the Webhannet and Sanborn Cove marshes were considerably older than their conventional counterparts, by as much as 1,000 years. Three causes for this age discrepancy are suggested. First, under slow rates of marsh accretion, peats remain within the root zone of modern plants for a relatively long period, causing a continued input of younger carbon. Intruded roots are undetectable in the highly macerated, 4,000--5,000 C-14 year old peats. Another source of contamination is the percolation of mobile humic acids along the impermeable Pleistocene substrate. Finally, a date on a bulk peat of 10 cm vertical extent represents an average age for a portion of peat that spans a time interval possibly of several centuries. The age difference between the bulk date and the AMS date from the base of the peat increases with decreasing rates of marsh accretion. The forested steep slopes of the upland surrounding the marsh seem a likely source of old carbon that can easily be washed onto the marsh surface. The slow rate of late-Holocene sea-level rise in Maine, as well as the geologic and hydrologic setting of the salt marshes, make conventional C-14 dating of salt marsh peats in Maine a problematic affair. This study implies that AMS dates may be needed to verify Holocene sea-level curves from other coastal areas that have hitherto been based solely on conventional C-14 peat dates.

  16. A glacial chronology for post Little Ice Age glacier changes based on proglacial geomorphology, tree rings, OSL- and 14C-dating at Mt. Pulongu, southeastern Tibet

    NASA Astrophysics Data System (ADS)

    Loibl, David; Hochreuther, Philipp; Hülle, Daniela; Zhu, Haifeng; Lehmkuhl, Frank

    2014-05-01

    The remote eastern Nyainqêntanglha Range contains numerous temperate monsoonal glaciers which are highly sensitive to climate change. However, there is still a great lack of information on late Holocene glacier fluctuations and the factors driving these changes. We conducted field work at two large debris covered glaciers on the northern and southern slopes of Mt. Pulongu (~6,300 m a.s.l.). Detailed geomorphological mapping of the proglacial settings revealed similar patterns of two major and three minor/recessional glacial advances. At the northern glacier, tree ring dating for the moraines of the two major advances resulted in minimum ages of ~1670 AD and ~1745 AD, respectively. These Little Ice Age (LIA) ages are supported by geochemical measurements on glacial and glacio-fluvial sediments from these settings showing almost no signs of chemical weathering. Further evidence, including 14C-age and depositional characteristics of a buried tree, and moraine topography, suggest that the second advance was stronger but was hampered by a dead ice relict of the previous advance. At the northern glacier, this obstacle led to an ice tailback and subsequently to lateral moraine oversteepening and breaching, resulting in a large lateral glacier lobe. At the southern glacier, the valley is narrower and hence did not allow the formation of a lateral glacier lobe. However, the proglacial setting, i.e. pronounced push moraines, suggests a similar sequence of events. Furthermore, both settings contain two moraine-dammed lakes in similar positions. A combination of OSL-dating, tree ring based reconstruction of the local climate, and constraints from the proglacial geomorphological setting enabled the inclusion of the 3 minor moraine stages into the glacial chronology. This multiproxy-approach resulted in a well-established morphochronology with multiple direct and indirect dates that allow the reconstruction of the glacial fluctuations at Mt. Pulongu since the LIA. A regional

  17. Exploring the method of optical dating and comparison of optical and 14C ages of Late Weichselian coversands in the southern Netherlands

    NASA Astrophysics Data System (ADS)

    Vandenberghe, D.; Kasse, C.; Hossain, S. M.; de Corte, F.; van den Haute, P.; Fuchs, M.; Murray, A. S.

    2004-01-01

    A study was made of the applicability of three different techniques for equivalent dose (De) determination in the optical dating of quartz: the single-aliquot regenerative-dose technique (SAR), the single-aliquot additive-dose technique (SAAD) and the multiple-aliquot additive-dose technique (MAAD). For this purpose, quartz grains were extracted from a sequence of Upper Pleniglacial to Late-glacial coversands exposed at the locality of Ossendrecht in the southwestern Netherlands, a site for which both radiocarbon and earlier luminescence dates are available, providing independent age control.Upon testing the different assumptions underlying each of the three OSL techniques investigated, the SAR protocol was found to be the technique of choice. The optical ages obtained with this protocol were in good agreement with the chronostratigraphical position of the sediments investigated and with the available chronostratigraphical information on the same and equivalent deposits. This confirms the suitability of the SAR technique for dating coversands. Furthermore, a small laboratory intercomparison of SAR-based De determinations yielded results that were in fair overall agreement. Copyright

  18. 14C Analysis of Protein Extracts from Bacillus Spores

    PubMed Central

    Cappucio, Jenny A.; Sarachine Falso, Miranda J.; Kashgarian, Michaele; Buchholz, Bruce A.

    2014-01-01

    Investigators of bioagent incidents or interdicted materials need validated, independent analytical methods that will allow them to distinguish between recently made bioagent samples versus material drawn from the archives of a historical program. Heterotrophic bacteria convert the carbon in their food sources, growth substrate or culture media, into the biomolecules they need. The F14C (fraction modern radiocarbon) of a variety of media, Bacillus spores, and separated proteins from Bacillus spores was measured by accelerator mass spectrometry (AMS). AMS precisely measures F14C values of biological materials and has been used to date the synthesis of biomaterials over the bomb pulse era (1955 to present). The F14C of Bacillus spores reflects the radiocarbon content of the media in which they were grown. In a survey of commercial media we found that the F14C value indicated that carbon sources for the media were alive within about a year of the date of manufacture and generally of terrestrial origin. Hence, bacteria and their products can be dated using their 14C signature. Bacillus spore samples were generated onsite with defined media and carbon free purification and also obtained from archived material. Using mechanical lysis and a variety of washes with carbon free acids and bases, contaminant carbon was removed from soluble proteins to enable accurate 14C bomb-pulse dating. Since media is contemporary, 14C bomb-pulse dating of isolated soluble proteins can be used to distinguish between historical archives of bioagents and those produced from recent media. PMID:24814329

  19. Paleopedology plus TL, 10Be, and14C dating as tools in stratigraphic and paleoclimatic investigations, Mississippi River Valley, U.S.A.

    USGS Publications Warehouse

    Markewich, H.W.; Wysocki, D.A.; Pavich, M.J.; Rutledge, E.M.; Millard, H.T.; Rich, F.J.; Maat, P.B.; Rubin, M.; McGeehin, J.P.

    1998-01-01

    Thick ( ??? 35 m) loess deposits are present on ridges and high bluffs in the northern-half of the Lower Mississippi Valley (LMV), U.S.A. Detailed descriptions of the loess sections and pedologic, physiochemical, and mineralogic analyses and TL, 14C, and 10Be age determinations, allow preliminary paleoclimatic reconstructions for the late Quaternary of central North America. No age data are available for the oldest (Fifth) loess. 10Be and TL age data suggest a 250-200 ka age for the Fourth or Crowleys Ridge(?) Loess, and indicate that the Loveland or Third Loess is time equivalent to oxygen isotope stage 6, ??? 190-120 ka. A weakly developed paleosol is present in the basal-half of the Loveland. The Sangamon Geosol is present in the upper 5 m and represents all of oxygen isotope stage 5, ??? 130-60 ka. It formed in a climate as warm as, but drier and (or) with greater variation in precipitation, than the present. The Roxana Silt (second loess) was deposited during oxygen isotope stages 4 and 3, ??? 65-26 ka. The early Wisconsinan interglacial-glacial transition, represented by the Sangamon Geosol and the unnamed paleosol in the basal Roxana Silt, was slow. The paleoclimate during the 35 k yr of Roxana deposition was cool to cold and wet. Age and pedologic data indicate that deposition of the Peoria Loess (the youngest) began around 25 ka when the area's climate changed abruptly from cool or cold and wet to cold and dry, with periods of sustained high winds.

  20. Reconnaissance 14C Dating and the Evaluation of Mg/Li as a Temperature Proxy in Bamboo Corals from the California Margin

    NASA Astrophysics Data System (ADS)

    Freiberger, M. M.; LaVigne, M.; Miller, H.; Hill, T. M.; McNichol, A. P.; Lardie Gaylord, M.

    2015-12-01

    In the face of anthropogenically induced climate changes, it is becoming increasingly important to develop high-resolution paleoceanographic records that may elucidate how ocean conditions may shift in coming decades. Recently, bamboo corals (gorgonian octocorals) have been proposed as archives of intermediate ocean conditions. This study used 'reconnaissance' radiocarbon analysis to identify the nuclear bomb 14C spike in the proteinaceous nodes of bamboo corals and to quantify radial growth rates and ages of corals spanning the eastern Pacific oxygen minimum zone (OMZ) (790-2055 m). Preliminary data suggest that these corals exhibit a wide range of growth rates (9.4-350 μm/yr) that are non-linear over time and decrease with coral age and depth. Records of Mg/Li were investigated in these corals, given that previous studies have demonstrated positive correlations between Mg/Li and temperature in benthic foraminifera and surface and deep-sea aragonitic corals, with a reduced influence of vital effects over Mg/Ca. Intracoral reproducibility observed for replicate Mg/Li timeseries within each sample (p=0.6±0.2, n=6) and strong correlations between Mg/Ca and Li/Ca (0.9±0.1, n=6) indicate similar environmental or biological drivers of Mg and Li incorporation in bamboo corals. Given the strong positive correlations between Mg/Li and water temperature across a depth transect (r2=0.87, n=6), increasing Mg/Li observed over the growth history of each of the corals more likely reflects declining growth rates resulting in decreased Li incorporation over time rather than cooling of California Margin intermediate waters. Reductions in growth rate over the lifespan of each coral (~100+ years) may be a function of natural coral growth patterns or changes in carbonate chemistry, oxygen, or food supply in a sensitive OMZ coral ecosystem.

  1. AMS 14C and OSL/IRSL dating of the Dunaszekcső loess sequence (Hungary): chronology for 20 to 150 ka and implications for establishing reliable age-depth models for the last 40 ka

    NASA Astrophysics Data System (ADS)

    Újvári, Gábor; Molnár, Mihály; Novothny, Ágnes; Páll-Gergely, Barna; Kovács, János; Várhegyi, András

    2014-12-01

    As revealed by 18 AMS radiocarbon and 24 OSL/IRSL ages the Dunaszekcső loess-paleosol sequence is an excellent terrestrial record of paleoenvironmental change in the Carpathian Basin for the last 130 ka, with significant soil forming episodes during the Eemian interglacial (130-115 ka, MIS 5e) and in some subsequent MIS 5 stages, and distinct periods of loess accumulations during the MIS 4 and MIS 2. Charcoals from the sequence made it possible to test the accuracy of 14C ages from mollusc shells. This approach revealed that 14C ages from some gastropods having small shells (<10 mm) (Succinella oblonga, Vitrea crystallina) are statistically indistinguishable from the ages of charcoals, while others (Clausiliidae sp., Chondrula tridens) show age anomalies up to 600-800 years. OSL and pIRIR@290 ages are found to be consistently older, while post-IR OSL ages are younger than the 14C ages from charcoals and molluscs by some thousands of years, except for pIRIR@225 ages that match the radiocarbon ages quite well. OSL and IRSL ages have scatters up to 7-10 thousand years within 40 ka, while charcoals and small molluscs yield consistent ages with relatively low variability. Beyond the observation that some small molluscs seem to yield reliable 14C ages, calibrated 2σ age ranges of the radiocarbon data (ca 500-800 years for 20 to 30 ka) are an order of magnitude narrower than those of the OSL/IRSL methods (1800-4000 years for 25 to 35 ka). Thus, for establishing chronologies within 40 ka, which are both accurate and precise enough to address issues like synchroneity of millennial-scale paleoenvironmental events across regions (e.g. North Atlantic and Europe), AMS radiocarbon dating of shells of specific loess molluscs and charcoals may probably be a powerful chronological tool. However, additional work is definitely required involving 14C and OSL/IRSL dates from other loess sequences to further test the performance of these two supposedly robust chronometers.

  2. Timing and characteristics of Late Pleistocene and Holocene wetter periods in the Eastern Desert and Sinai of Egypt, based on 14C dating and stable isotope analysis of spring tufa deposits

    NASA Astrophysics Data System (ADS)

    Hamdan, Mohamed A.; Brook, George A.

    2015-12-01

    There is very little dated evidence on wet periods in the Eastern Desert and Sinai Peninsula of Egypt during the Late Pleistocene and Holocene. To obtain such information, we have studied the petrography, isotope geochemistry and AMS radiocarbon ages of mostly relict tufas deposited by springs draining perched ground water bodies in metamorphic and volcanic rocks. The tufas unconformably overly Precambrian basic igneous rocks (basalt, diabase and gabbro). As the ages of tufa carbonate are frequently older than the true ages of the deposits because of the incorporation of old, 14C-dead carbon, we have dated both the carbonate matrix and insoluble organic material of the tufas. These ages show that the tufas were largely formed during two broad time periods, the most recent from 12,058 to 6678 cal yr BP (African Humid Period), and the other from ˜31,200-22,500 cal yr BP, with preferential growth during the coldest times of this period namely during Heinrich Events 2 and 3 (H2 and H3) and the Last Glacial Maximum (LGM). The time span between 19,000-9000 cal yr BP, including the YD and H1, appears to have been relatively more arid than the earlier LGM or H2 periods or the later Holocene. The Late Pleistocene tufas are depleted in 18O relative to the Holocene tufas and were deposited at a lower temperature (˜14.0°-20.8 °C vs. 18.4°-23.4 °C). We believe that the Holocene tufas in the Sinai were formed by rainfall from the Mediterranean and those in the southern part of the Eastern Desert by African monsoon rainfall derived from the Red Sea-Gulf of Aden and Indian Ocean. In contrast, the moisture that fed the Late Pleistocene tufas, which are depleted in 18O relative to Holocene deposits, and progressively depleted from north to south, was probably brought by the Westerlies from the Atlantic-Mediterranean Sea when the Westerly circulation was pushed southwards during the coldest periods of the Late Pleistocene. Periods of tufa deposition correlate with major

  3. Age depth model construction of the upper section of ICDP Dead Sea Deep Drilling Project based on the high-resolution 14C dating

    NASA Astrophysics Data System (ADS)

    Kitagawa, H.; Nakamura, T.; Neugebauer, I.; Schwab, M. J.; Brauer, A.; Goldstein, S. L.; Stein, M.

    2014-12-01

    To reconstruct environmental, climatic and tectonic histories of the Levant, a deep drilling has been accomplished in the northern basin of the Dead Sea during the fall winter of 2010-2011 by the Dead Sea Deep Drilling Project (DSDDP) in the framework of the ICDP program. The sediment cores from site 5017-1 (water depth of ~300 m) recorded the paleoenvironmental and paleohydrological changes in the Dead Sea and the Levant during the last two glacial-interglacial cycles (Neugebauer et al., QSR in press). To provide precise timing of sedimentological - limnological events in the lake and its watershed, and more critically the relative timing of these events, radiocarbon dating of >70 well-preserved terrestrial plants and some carbonate deposits from the upper 150 m long section of the sediment core were performed. Based on the high-resolution radiocarbon dating, a statistical age-depth model was constructed with assumptions on the deposition condition and the radiocarbon age offset of carbonate samples. We discuss the practicality and the limitation of the age-depth model toward interpreting the high-resolution records of environmental, climatic and tectonic events recorded in the long sediment cores from site 5017-1.

  4. Detecting human presence at the border of the Northeastern Italian Pre-Alps. 14C dating at Rio Secco cave as expression of the first Gravettian and the late mousterian in the Northern Adriatic Region.

    PubMed

    Talamo, Sahra; Peresani, Marco; Romandini, Matteo; Duches, Rossella; Jéquier, Camille; Nannini, Nicola; Pastoors, Andreas; Picin, Andrea; Vaquero, Manuel; Weniger, Gerd-Christian; Hublin, Jean-Jacques

    2014-01-01

    In the northern Adriatic regions, which include the Venetian region and the Dalmatian coast, late Neanderthal settlements are recorded in few sites and even more ephemeral are remains of the Mid-Upper Palaeolithic occupations. A contribution to reconstruct the human presence during this time range has been produced from a recently investigated cave, Rio Secco, located in the northern Adriatic region at the foot of the Carnic Pre-Alps. Chronometric data make Rio Secco a key site in the context of recording occupation by late Neanderthals and regarding the diffusion of the Mid-Upper Palaeolithic culture in a particular district at the border of the alpine region. As for the Gravettian, its diffusion in Italy is a subject of on-going research and the aim of this paper is to provide new information on the timing of this process in Italy. In the southern end of the Peninsula the first occupation dates to around 28,000 14C BP, whereas our results on Gravettian layer range from 29,390 to 28,995 14C years BP. At the present state of knowledge, the emergence of the Gravettian in eastern Italy is contemporaneous with several sites in Central Europe and the chronological dates support the hypothesis that the Swabian Gravettian probably dispersed from eastern Austria.

  5. Detecting Human Presence at the Border of the Northeastern Italian Pre-Alps. 14C Dating at Rio Secco Cave as Expression of the First Gravettian and the Late Mousterian in the Northern Adriatic Region

    PubMed Central

    Talamo, Sahra; Peresani, Marco; Romandini, Matteo; Duches, Rossella; Jéquier, Camille; Nannini, Nicola; Pastoors, Andreas; Picin, Andrea; Vaquero, Manuel; Weniger, Gerd-Christian; Hublin, Jean-Jacques

    2014-01-01

    In the northern Adriatic regions, which include the Venetian region and the Dalmatian coast, late Neanderthal settlements are recorded in few sites and even more ephemeral are remains of the Mid-Upper Palaeolithic occupations. A contribution to reconstruct the human presence during this time range has been produced from a recently investigated cave, Rio Secco, located in the northern Adriatic region at the foot of the Carnic Pre-Alps. Chronometric data make Rio Secco a key site in the context of recording occupation by late Neanderthals and regarding the diffusion of the Mid-Upper Palaeolithic culture in a particular district at the border of the alpine region. As for the Gravettian, its diffusion in Italy is a subject of on-going research and the aim of this paper is to provide new information on the timing of this process in Italy. In the southern end of the Peninsula the first occupation dates to around 28,000 14C BP, whereas our results on Gravettian layer range from 29,390 to 28,995 14C years BP. At the present state of knowledge, the emergence of the Gravettian in eastern Italy is contemporaneous with several sites in Central Europe and the chronological dates support the hypothesis that the Swabian Gravettian probably dispersed from eastern Austria. PMID:24759802

  6. Forensic applications of 14C at CIRCE

    NASA Astrophysics Data System (ADS)

    Marzaioli, F.; Fiumano, V.; Capano, M.; Passariello, I.; Cesare, N. De.; Terrasi, F.

    2011-12-01

    The decreasing trend of the radiocarbon pulse produced during the atmospheric tests of nuclear weapons (bomb-carbon) coupled with high sensitivity accelerator mass spectrometry (AMS) measurements, drastically increased the precision of radiocarbon age determinations since the second part of the sixties, allowing the application of radiocarbon AMS to a wide range of studies previously not directly involving conventional radiocarbon dating (i.e. food authenticity, forensic, biochemistry). In the framework of authenticity evaluation of artworks, high precision radiocarbon ( 14C) AMS measurements (Δ R/ R < 0.3%) reduce the conventional uncertainty of the dating to few decades, allowing precise age estimation of materials containing carbon (C). The Centre for Isotopic Research on Cultural and Environmental heritage (CIRCE) during its activity on AMS 14C dating achieved high precision measurements opening the opportunity to these kinds of applications. This paper presents the main results obtained from radiocarbon measurements on a set of bone samples analyzed for the determination of the post-mortem interval in the framework of an unsolved case investigated by the Rome prosecutor office. The chronological characterization of the wooden support of the "Acerenza portrait" is also presented with the aim to evaluate its age and to further investigate the possibility to attribute this artwork to Leonardo da Vinci. Bomb- 14C dating on the lipid and collagen fractions of bones allows the evaluation of the year of the death of the individuals by means of ad hoc calibration data sheet with the typical few years precision and difference between collagen apparent age and the year of death appeared in agreement with the age of one individual estimated by dating of tooth collagen. Conventional radiocarbon dating on both wood and wood extracted cellulose leads to an estimation of the portrait wood board age (2σ) of 1459-1524 AD (57% relative probability), 1571-1631 AD interval (42

  7. 14C-carbaryl residues in hazelnut.

    PubMed

    Yücel, Ulkü; Ilim, Murat; Aslan, Nazife

    2006-01-01

    A hazelnut ocak (shrub growing form) in the field in Black Sea region of Turkey was treated with commercial carbaryl insecticide spiked with 14C-carbaryl. Three months later, the harvested hazelnuts were separated into husk, shell, and kernel components, then homogenized and analyzed. The total and unextractable (bound) 14C-residues were determined by combustion and the extractable 14C-residues were obtained by extracting the samples with methanol. Concentrated extracts were first analyzed by thin layer chromatography (TLC). The extracts were also subjected to a series of liquid-liquid extraction procedures for clean-up and the final extracts were analyzed by high performance liquid chromatography (HPLC). Crude hazelnut oil was also extracted with hexane and analyzed for total 14C-residue. A total of 1.3% of applied radioactivity was recovered from the total nut harvested, with 0.04%, 0.06%, and 1.2% present in shell, kernel, and husk, respectively. The results show that the inedible husk and shell contained 95.7% 14C, whereas the edible kernel contained 4.3% of the total 14C recovered. The terminal 14C-residue in hazelnut kernel and oil did not contain carbaryl and/or its metabolite naphthol.

  8. Life history of the individuals buried in the St. Benedict Cemetery (Prague, 15th-18th centuries): insights from (14)C dating and stable isotope (δ(13)C, δ(15)N, δ(18)O) analysis.

    PubMed

    Salesse, Kevin; Dufour, Élise; Castex, Dominique; Velemínský, Petr; Santos, Frédéric; Kuchařová, Hedvika; Jun, Libor; Brůžek, Jaroslav

    2013-06-01

    Funerary practices and bioarchaeological (sex and age) data suggest that a mortality crisis linked to an epidemic episode occurred during the fifth phase of the St. Benedict cemetery in Prague (Czech Republic). To identify this mass mortality episode, we reconstructed individual life histories (dietary and mobility factors), assessed the population's biological homogeneity, and proposed a new chronology through stable isotope analysis (δ(13)C, δ(18)O and δ(15)N) and direct radiocarbon dating. Stable isotope analysis was conducted on the bone and tooth enamel (collagen and carbonate) of 19 individuals from three multiple graves (MG) and 12 individuals from individual graves (IG). The δ(15)N values of collagen and the difference between the δ(13)C values of collagen and bone carbonate could indicate that the IG individuals had a richer protein diet than the MG individuals or different food resources. The human bone and enamel carbonate and δ(18)O values suggest that the majority of individuals from MG and all individuals from IG spent most of their lives outside of the Bohemian region. Variations in δ(18)O values also indicate that all individuals experienced residential mobility during their lives. The stable isotope results, biological (age and sex) data and eight (14)C dates clearly differentiate the MG and IG groups. The present work provides evidence for the reuse of the St. Benedict cemetery to bury soldiers despite the funeral protest ban (1635 AD). The Siege of Prague (1742 AD) by French-Bavarian-Saxon armies is identified as the cause of the St. Benedict mass mortality event.

  9. Life history of the individuals buried in the St. Benedict Cemetery (Prague, 15th-18th centuries): insights from (14)C dating and stable isotope (δ(13)C, δ(15)N, δ(18)O) analysis.

    PubMed

    Salesse, Kevin; Dufour, Élise; Castex, Dominique; Velemínský, Petr; Santos, Frédéric; Kuchařová, Hedvika; Jun, Libor; Brůžek, Jaroslav

    2013-06-01

    Funerary practices and bioarchaeological (sex and age) data suggest that a mortality crisis linked to an epidemic episode occurred during the fifth phase of the St. Benedict cemetery in Prague (Czech Republic). To identify this mass mortality episode, we reconstructed individual life histories (dietary and mobility factors), assessed the population's biological homogeneity, and proposed a new chronology through stable isotope analysis (δ(13)C, δ(18)O and δ(15)N) and direct radiocarbon dating. Stable isotope analysis was conducted on the bone and tooth enamel (collagen and carbonate) of 19 individuals from three multiple graves (MG) and 12 individuals from individual graves (IG). The δ(15)N values of collagen and the difference between the δ(13)C values of collagen and bone carbonate could indicate that the IG individuals had a richer protein diet than the MG individuals or different food resources. The human bone and enamel carbonate and δ(18)O values suggest that the majority of individuals from MG and all individuals from IG spent most of their lives outside of the Bohemian region. Variations in δ(18)O values also indicate that all individuals experienced residential mobility during their lives. The stable isotope results, biological (age and sex) data and eight (14)C dates clearly differentiate the MG and IG groups. The present work provides evidence for the reuse of the St. Benedict cemetery to bury soldiers despite the funeral protest ban (1635 AD). The Siege of Prague (1742 AD) by French-Bavarian-Saxon armies is identified as the cause of the St. Benedict mass mortality event. PMID:23588853

  10. Intracavity optogalvanic spectroscopy. An analytical technique for 14C analysis with subattomole sensitivity.

    PubMed

    Murnick, Daniel E; Dogru, Ozgur; Ilkmen, Erhan

    2008-07-01

    We show a new ultrasensitive laser-based analytical technique, intracavity optogalvanic spectroscopy, allowing extremely high sensitivity for detection of (14)C-labeled carbon dioxide. Capable of replacing large accelerator mass spectrometers, the technique quantifies attomoles of (14)C in submicrogram samples. Based on the specificity of narrow laser resonances coupled with the sensitivity provided by standing waves in an optical cavity and detection via impedance variations, limits of detection near 10(-15) (14)C/(12)C ratios are obtained. Using a 15-W (14)CO2 laser, a linear calibration with samples from 10(-15) to >1.5 x 10(-12) in (14)C/(12)C ratios, as determined by accelerator mass spectrometry, is demonstrated. Possible applications include microdosing studies in drug development, individualized subtherapeutic tests of drug metabolism, carbon dating and real time monitoring of atmospheric radiocarbon. The method can also be applied to detection of other trace entities.

  11. Antioxidant phenolic extracts obtained from secondary Tunisian date varieties (Phoenix dactylifera L.) by hydrothermal treatments.

    PubMed

    Mrabet, Abdessalem; Jiménez-Araujo, Ana; Fernández-Bolaños, Juan; Rubio-Senent, Fátima; Lama-Muñoz, Antonio; Sindic, Marianne; Rodríguez-Gutiérrez, Guillermo

    2016-04-01

    Three common non-commercial Tunisian date varieties were treated by two thermal systems, obtaining a liquid fraction which was characterized and its antioxidant capacity determined. The concentration of total phenols in the three varieties (Smeti, Garen Gazel, and Eguwa) was increased by steam explosion treatment up to 5311, 4680, and 3832 mg/kg of fresh dates, and their antioxidant activity up to 62.5, 46.5 and 43.1 mmol Trolox/kg of fresh date, respectively. Both thermal treatments increased the content of phenolic acids. Additionally, a long scale study was carried out in a pilot plant, with steam treatment at 140 °C and 160 °C for 30 min. The liquid phase was extracted and fractionated chromatographically using adsorbent or ionic resins. The phenolic profiles were determined for each fraction, yielding fractions with interesting antioxidant activities with EC50 values of up to 0.08 mg/L or values of TEAC of 0.67 mmol Trolox/g of extract.

  12. Antioxidant phenolic extracts obtained from secondary Tunisian date varieties (Phoenix dactylifera L.) by hydrothermal treatments.

    PubMed

    Mrabet, Abdessalem; Jiménez-Araujo, Ana; Fernández-Bolaños, Juan; Rubio-Senent, Fátima; Lama-Muñoz, Antonio; Sindic, Marianne; Rodríguez-Gutiérrez, Guillermo

    2016-04-01

    Three common non-commercial Tunisian date varieties were treated by two thermal systems, obtaining a liquid fraction which was characterized and its antioxidant capacity determined. The concentration of total phenols in the three varieties (Smeti, Garen Gazel, and Eguwa) was increased by steam explosion treatment up to 5311, 4680, and 3832 mg/kg of fresh dates, and their antioxidant activity up to 62.5, 46.5 and 43.1 mmol Trolox/kg of fresh date, respectively. Both thermal treatments increased the content of phenolic acids. Additionally, a long scale study was carried out in a pilot plant, with steam treatment at 140 °C and 160 °C for 30 min. The liquid phase was extracted and fractionated chromatographically using adsorbent or ionic resins. The phenolic profiles were determined for each fraction, yielding fractions with interesting antioxidant activities with EC50 values of up to 0.08 mg/L or values of TEAC of 0.67 mmol Trolox/g of extract. PMID:26593573

  13. 14C tebuconazole degradation in Colombian soils.

    PubMed

    Mosquera, C S; Martínez, M J; Guerrero, J A

    2010-01-01

    Tebuconazole is a fungicide used on onion crops (Allium Fistulosum L) in Colombia. Persistence of pesticides in soils is characterized by the half-life (DT50), which is influenced by their chemical structure, the physical and chemical properties of the soil and the previous soil history. Based on its structural and chemical properties, tebuconazole should be expected to be relatively persistent in soils. Laboratory incubation studies were conducted to evaluate persistence and bond residues of 14C tebuconazole in three soils, two inceptisol (I) and one histosol (H). Textural classifications were: loam (101), loamy sand (102) and loam (H03), respectively. Data obtained followed a first-order degradation kinetics (R2 > or = 0.899) with DT50 values between 158 and 198 days. The production of 14CO2 from the 14C-ring-labelled test chemicals was very low and increased slightly during 63 days in all cases. The methanol extractable 14C-residues were higher than aqueous ones and both decreased over incubation time for the three soils. The formation of bound 14C-residues increased with time and final values were 11.3; 5.55 and 7.87% for 101, 102 and H03 respectively. Soil 101 showed the lowest mineralization rate and the highest bound residues formation, which might be explained by the clay fraction content. In contrast, an inverse behavior was found for soils 102 and H03, these results might be explained by the higher soil organic carbon content. PMID:21542480

  14. 14C tebuconazole degradation in Colombian soils.

    PubMed

    Mosquera, C S; Martínez, M J; Guerrero, J A

    2010-01-01

    Tebuconazole is a fungicide used on onion crops (Allium Fistulosum L) in Colombia. Persistence of pesticides in soils is characterized by the half-life (DT50), which is influenced by their chemical structure, the physical and chemical properties of the soil and the previous soil history. Based on its structural and chemical properties, tebuconazole should be expected to be relatively persistent in soils. Laboratory incubation studies were conducted to evaluate persistence and bond residues of 14C tebuconazole in three soils, two inceptisol (I) and one histosol (H). Textural classifications were: loam (101), loamy sand (102) and loam (H03), respectively. Data obtained followed a first-order degradation kinetics (R2 > or = 0.899) with DT50 values between 158 and 198 days. The production of 14CO2 from the 14C-ring-labelled test chemicals was very low and increased slightly during 63 days in all cases. The methanol extractable 14C-residues were higher than aqueous ones and both decreased over incubation time for the three soils. The formation of bound 14C-residues increased with time and final values were 11.3; 5.55 and 7.87% for 101, 102 and H03 respectively. Soil 101 showed the lowest mineralization rate and the highest bound residues formation, which might be explained by the clay fraction content. In contrast, an inverse behavior was found for soils 102 and H03, these results might be explained by the higher soil organic carbon content.

  15. Synthesis of [(14) C]omarigliptin.

    PubMed

    Ren, Sumei; Gauthier, Donald; Marques, Rosemary; Helmy, Roy; Hesk, David

    2016-08-01

    An efficient synthesis for [(14) C]Omarigliptin (MK-3102) is described. The initial synthesis of a key (14) C-pyrazole moiety did not work due to the lack of stability of (14) C-DMF-DMA reagent. Thus, a new radiolabeled synthon, (14) C-biphenylmethylformate, was synthesized from (14) C-sodium formate in one step in 92% yield and successfully used in construction of the key (14) C-pyrazole moiety. Regioselective N-sulfonation of the pyrazole moiety was achieved through a dehydration-sulfonation-isomerization sequence. [(14) C]MK 3102 was synthesized in five steps from (14) C-biphenylmethylformate with 25% overall yield. PMID:27334864

  16. A Multi-Isotope (B, Sr, O, H, C) and Age Dating (3H-3He, 14C) Study of Ground Water From Salinas Valley, California: Hydrochemistry, Dynamics, and Contamination Processes

    SciTech Connect

    Vengosh, A; Gill, J; Davisson, M L; Hudson, B G

    2001-08-01

    The chemical and isotopic ({sup 11}B/{sup 10}B, {sup 87}Sr/{sup 86}Sr, {sup 18}O/{sup 16}O, {sup 2}H/H, {sup 13}C/{sup 12}C, {sup 14}C, {sup 3}He/{sup 3}H) compositions of groundwater from the upper aquifer system of the Salinas Valley in coastal central California were investigated in order to delineate the origin and processes of groundwater contamination in this complex system. The Salinas Valley has a relatively deep, confined ''400-foot'' aquifer, overlain by a ''180-foot'' aquifer, and a shallower perched aquifer, all made up of alluvial sand, gravel, and clay deposits. Groundwater from the aquifers have different {sup 14}C ages; fossil ({sup 14}C = 21.3 pmc) for the 400-foot, and modern ({sup 14}C = 72.2 to 98.2 pmc) for the 180-foot. Fresh groundwater in all aquifers is recharged naturally and artificially and through the Salinas River. The two modes of recharge can be distinguished chemically. We identified several different saline components with distinguishable chemical and isotopic fingerprints. (1) Salt-water intrusion in the northern basin has Cl concentrations up to 1700 mg/l, a Na/Cl ratio seawater, {delta}{sup 11}B between +17 and +38 per mil, and {sup 87}Sr/{sup 86}Sr between 0.7088 and 0.7096. Excess dissolved Ca, relative to the expected concentration for simple dilution of seawater, correlates with {sup 87}Sr/{sup 86}Sr ratios, suggesting base exchange reaction with clay minerals. (2) Agriculture return flow is high in NO{sub 3} and SO{sub 4}, with a {sup 87}Sr/{sup 86}Sr = 0.7082, {delta}{sup 11}B = 19 per mil; and {delta}{sup 13}C between -23 and -17 per mil. The {sup 3}H-{sup 3}He ages (5-17 years) and {sup 14}C data suggest vertical infiltration rates of irrigation water of 3 to 10 m/yr. (3) Non-marine saline water in the southern part of the valley has high TDS up to 3800 mg/l, high SO{sub 4}, Na/Cl ratio >1, {delta}{sup 11}B between +24 and +30 per mil, and {sup 87}Sr/{sup 86}Sr = 0

  17. A high resolution method for 14C analysis of a coral from South China Sea: Implication for "AD 775" 14C event

    NASA Astrophysics Data System (ADS)

    Ding, Ping; Shen, Chengde; Yi, Weixi; Wang, Ning; Ding, Xingfang; Liu, Kexin; Fu, Dongpo; Liu, Weiguo; Liu, Yi

    2015-10-01

    A pre-heating method that improves the background and precision of 14C dating significantly was applied for fossil coral dating with high resolution in our lab in Guangzhou Institute of Geochemistry, Chinese Academy of Sciences (GIGCAS). The reaction tube is heated under 300 °C in a vacuum line before it is used for graphitization. The method can reduce the contamination absorbed in TiH2, Zn and Fe power placed in the graphitization tube. With the pre-heating and average drilling method, bi-weekly resolution 14C dating in a fossil coral is carried out to investigate the "AD 775 14C spike event". Different from the tree ring 14C archives with the 14C spike of ∼15‰ (Δ14C), the 14C spike in the coral shows an abrupt peak of 45‰ and two smaller spikes of Δ14C > 20‰ in half a year in AD 776. And then, the 14C content in coral decreases gradually in AD 777. The peak time of the 14C spike event likely occurs in the summer of AD 776 according to the δ18O variation in coral. High-resolution dating of 14C in coral provides not only a more detail process of the event than that from tree rings, but also the first report of the event from sea ecosystem. Both of them suggest an extraterrestrial origin of the event cause.

  18. Laboratory Experiments to Evaluate Diffusion of 14C into Nevada Test Site Carbonate Aquifer Matrix

    SciTech Connect

    Ronald L. Hershey; William Howcroft; Paul W. Reimus

    2003-03-01

    to published velocities. The lower end of the range of 14C correction factors falls within the range of reported velocities. From these results, future experimental studies (both laboratory and field scale) to support 14C groundwater age dating should focus on obtaining better estimates of aquifer properties including matrix and fracture porosities.

  19. Intramolecular labelling of sucrose made by leaves from [14C)carbon dioxide or [3-14C]serine.

    PubMed

    Bird, I F; Cornelius, M J; Keys, A J; Whittingham, C P

    1978-04-15

    Pea leaves were illuminated in air containing 150 or 1000p.p.m. of 14CO2 for various times. Alternatively, segments of wheat leaves were supplied with [3-14C]serine for 40 min in the light in air with 145, 326 or 944p.p.m. of 12CO2. Sucrose was extracted from the leaf material, hydrolysed with invertase, and 14C in the pairs of carbon atoms C-3+C-4, C-2+C-5 and C-1+C-6 in the glucose moiety was measured. The results obtained after metabolism of 14CO2 were consistent with the operation of the photosynthetic carbon-reduction cycle; the effects of CO2 concentration on distribution of 14C in the carbon chain of glucose after metabolism of [3-14C]serine is more easily explained by metabolism through the glycollate pathway than by the carbon-reduction cycle. PMID:656073

  20. Cellulose fibers obtained by organosolv process from date palm rachis (Phoenix dactylifera L.)

    NASA Astrophysics Data System (ADS)

    Ammar, H.; Abid, M.; Abid, S.

    2012-02-01

    In this preliminary study, the chemical composition of Tunisian DPR was established and discussed. The main characteristic of this agri-residue was its high lignin content in comparison with that of alfa plant. CIMV process was used to selectively separate cellulose fibres, hemicelluloses and lignin at atmospheric pressure. The obtained unbleached pulp was analysed in accordance with Kappa index and degree of polymerisation and then bleached by treating successively with peroxyacids and hydrogen peroxide in basic media.

  1. Radiocarbon Dating, Memories, and Hopes

    DOE R&D Accomplishments Database

    Libby, W. F.

    1972-10-01

    The history of radiocarbon dating from 1939 to the present is reviewed. The basic principles of radiocarbon dating are that cosmic rays make living things radioactive with {sup 14}C to a certain level fixed by the environment and that at death the intake of food stops so no replenishment of the {sup 14}C steadily lost by the immutable decay occurs. Therefore measurement of the degree of decay gives the time lapse since death, i.e., the radiocarbon age. The equipment developed and experiments performed to measure the specific activity of specimens to be dated are described. The results obtained by world-wide experimenters are discussed. These showed that on simultaneity radiocarbon dating is apparently reliable but that absolute dates may be incorrect by as much as 600 to 700 y. The value of radiocarbon dating to archaeologists, geologists, climatologists, and historians is stressed. (LCL)

  2. A new 14C calibration data set for the last deglaciation based on marine varves

    SciTech Connect

    Hughen, K A; Kashgarian, M; Lehman, S J; Overpeck, J T; Peterson, L C; Southon, J R

    1999-02-22

    Varved sediments of the tropical Cariaco basin provide a new {sup 14}C calibration data set for the period of deglaciation (10,000 to 14,500 years before present: 10-14.5 cal ka BP). Independent evaluations of the Cariasco Basin calendar and {sup 14}C chronologies were based on the agreement of varve ages with the GISP2 ice core layer chronology for similar high-resolution paleoclimate records, in addition to {sup 14}C age agreement with terrestrial {sup 14}C dates, even during large climatic changes. These assessments indicate that the Cariaco Basin {sup 14}C reservoir age remained stable throughout the Younger Dryas and late Alleroed climatic events and that the varve and {sup 14}C chronologies provide an accurate alternative to existing calibrations based on coral U/Th dates. The Cariaco Basin calibration generally agrees with coral-derived calibrations but is more continuous and resolves century-scale details of {sup 14}C change not seen in the coral records. {sup 14}C plateaus can be identified at 9.6, 11.4, and 11.7 {sup 14}C ka BP, in addition to a large, sloping plateau during the Younger Dryas ({approximately}10 to 11 {sup 14}C ka BP). Accounting for features such as these is crucial to determining the relative timing and rates of change during abrupt global climate changes of the last deglaciation.

  3. Temporal variation in the interhemispheric 14C offset

    NASA Astrophysics Data System (ADS)

    McCormac, F. G.; Hogg, A. G.; Higham, T. F. G.; Lynch-Stieglitz, J.; Broecker, W. S.; Baillie, M. G. L.; Palmer, J.; Xiong, L.; Pilcher, J. R.; Brown, D.; Hoper, S. T.

    Contemporaneous tree-ring dated wood, from trees in the northern and southern hemispheres, gives different 14C dates. Previous studies [Vogel et al., 1986; 1993] using wood from South Africa and The Netherlands have shown depletion's of -4.56 ± 0.85‰ and -5.12±0.62‰ respectively. This translates to age differences of 36±7 and 41±5 years (yrs) with the southern hemisphere giving the older dates. More recently, Stuiver and Braziunas [1998] have shown that an offset of 23±4 yrs exists between combined 19th century wood measurements from Tasmania and Chile in the southern hemisphere and the west coast of the U.S. (Washington) in the northern hemisphere. In this study measurements on contemporaneous decadal samples of oak from the British Isles and cedar from New Zealand over the period 1725 to 1885 AD show a depletion of -3.4±0.58‰ (27.2±4.7 yrs). However, data after 1895 AD has a mean offset of 0.66±1.06‰ (-5.3±8.5 yrs) with increased variance compared to 19th century data. This, we believe, is attributable to anthropogenic fossil fuel, which, due to its long residence time in the earth, has long since lost any 14C component and when burned preferentially depletes the northern hemisphere atmosphere of 14C.

  4. Comparison of 14C ages of hydrothermal petroleums

    USGS Publications Warehouse

    Simoneit, B.R.T.; Kvenvolden, K.A.

    1994-01-01

    In order to set limits on the time frame of formation of hydrothermal petroleum, we have obtained 14C ages on samples from three diverse regions; Gulf of California (Guaymas Basin), Northeast Pacific Ocean (Escanaba Trough and Middle Valley), and the East African Rift (Tanganyika Trough). The results date the source of carbon and therefore provide maximum ages for the formation and emplacement of the hydrothermal petroleums. The youngest petroleum occurs iin the Souther Trough of Guaymas Basin (3200-6600 yr, mean 4692 yr); in the Northern Trough the petroleum is slightly older (7400 yr). Significantly older hydrothermal petroleum occurs in Escanaba Trough (17,000 yr) and Middle Valley (29,000 yr). A continental example from the East African Rift has an age of 25,000 yr, comparable to the ages observed in the oceanic samples from the Northeast Pacific Ocean. These ages affirm that hydrothermal petroleum formation is a very rapid process and took place some time between the latest Pleistocene and the present in these active hydrothermal systems. ?? 1994.

  5. Search for exotic cluster configurations in 14C nucleus

    NASA Astrophysics Data System (ADS)

    Korotkova, L. Yu; Chernyshev, B. A.; Gurov, Yu B.; Karpuhin, V. S.; Lapushkin, S. V.; Pritula, R. V.; Schurenkova, T. D.

    2016-02-01

    The analysis of 2-dimentional Dalitz’ diagram, measured in 14C(π-, pd)X reaction, allowed to distinguish the pion absorption by p intranuclear cluster and to obtain an indication on the existence of 3p + 11Li configuration in 14C nucleus. Highly excited states of 12,13Be isotopes were found with the energy of Ex ≈ 30 MeV for the first time. It was shown that these states decay as follows 12Be*→p + 11Li and 13Be*→d + 11Li.

  6. Rapid, high-resolution 14C chronology of ooids

    NASA Astrophysics Data System (ADS)

    Beaupré, Steven R.; Roberts, Mark L.; Burton, Joshua R.; Summons, Roger E.

    2015-06-01

    Ooids are small, spherical to ellipsoidal grains composed of concentric layers of CaCO3 that could potentially serve as biogeochemical records of the environments in which they grew. Such records, however, must be placed in the proper temporal context. Therefore, we developed a novel acidification system and employed an accelerator mass spectrometer (AMS) with a gas accepting ion source to obtain radiocarbon (14C) chronologies extending radially through ooids within one 8-h workday. The method was applied to ooids from Highborne Cay, Bahamas and Shark Bay, Australia, yielding reproducible 14C chronologies, as well as constraints on the rates and durations of ooid growth and independent estimates of local 14C reservoir ages.

  7. Comparative radiocarbon dating of terrestrial plant macrofossils and aquatic moss from the ice-free corridor of western Canada

    SciTech Connect

    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.

  8. Radiocarbon to calendar date conversion: Calendrical band widths as a function of radiocarbon precision

    SciTech Connect

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

    1993-01-01

    Accurate high-precision [sup 14]C dating (i.e., [plus minus] 20 yr precision or less on the [sup 14]C date) provides the narrowest calendrical band width and, hence, the best age range determination possible. However, because of the structure in the [sup 14]C calibration curve, the calendar age range for a given [sup 14]C precision is not constant throughout the calibration range. In this study, they quantify the calendar band widths for a range of [sup 14]C precisions throughout the calibration range. They show that an estimate of the likely calendar band width in years can be obtained from the expression: Band width (yr) = 2.12 x [sup 14]C precision (1 [sigma]) + 54.6. They also show that calendar band widths are widest around 4000 Bp at the start of the Bronze Age, and become narrow through the later Bronze Age and Iron Age and back into the Neolithic.

  9. Natural Abundance 14C Content of Dibutyl Phthalate (DBP) from Three Marine Algae

    PubMed Central

    Namikoshi, Michio; Fujiwara, Takeshi; Nishikawa, Teruaki; Ukai, Kazuyo

    2006-01-01

    Analysis of the natural abundance 14C content of dibutyl phthalate (DBP) from two edible brown algae, Undaria pinnatifida and Laminaria japonica, and a green alga, Ulva sp., revealed that the DBP was naturally produced. The natural abundance 14C content of di-(2-ethylhexyl) phthalate (DEHP) obtained from the same algae was about 50–80% of the standard sample and the 14C content of the petrochemical (industrial) products of DBP and DEHP were below the detection limit.

  10. Using 10Be records to identify possible 14C calibration uncertainties during the Holocene

    NASA Astrophysics Data System (ADS)

    Raimund, Muscheler

    2010-05-01

    The Intcal04 and Intcal09 radiocarbon calibration records are based on multiple tree-ring 14C data sets for Holocene period (Reimer et al. 2004, Reimer et al. 2009). While the dendrochronolgical dating of the trees is supposedly free of errors there are differences between various 14C data sets that underlie the 14C calibration curve. Due to lack of knowledge about the reasons for the differences the Intcal04/09 calibration curves provide a smoothed average of the underlying 14C records. Therefore, problems in one or several of the underlying 14C records would translate directly into errors in the 14C age calibration. Additional knowledge about expected variations in the 14C production rate could help to improve the calibration record since it would allow us to assess how well the different 14C records represent the atmospheric 14C concentration. I propose that 10Be records could be used as additional criteria to chose which of the published 14C records should be preferred (or given stronger weight) for the construction of the calibration curve. Alternatively, 10Be records could point to periods where 14C data should be re-measured in order to improve the calibration curve. I will show for some case studies that the 10Be records from the Greenland ice cores (Muscheler et al. 2004, Vonmoos et al. 2006) indeed provide useful information to scrutinise the Intcal04/09 calibration curve, which could help to improve the 14C calibration curve during the Holocene. Especially shorter-term changes are strongly dampened in the Intcal04/09 calibration record. However, 10Be and some 14C records do exhibit more variability as compared to the calibration record. Therefore, the combined 10Be/14C approach could add confidence that these should be reflected in the 14C calibration record. References: Muscheler, R., Beer, J. et al., 2004. Changes in the carbon cycle during the last deglaciation as indicated by the comparison of 10Be and 14C records. Earth and Planetary Science Letters

  11. No evidence for a deglacial intermediate water Δ 14C anomaly in the SW Atlantic

    NASA Astrophysics Data System (ADS)

    Sortor, Rachel N.; Lund, David C.

    2011-10-01

    The last deglaciation was characterized by an increase in atmospheric pCO 2 and decrease in atmospheric radiocarbon activity. One hypothesis is that these changes were due to out-gassing of 14C-depleted carbon from the abyssal ocean. Reconstructions of foraminiferal Δ 14C from the eastern tropical Pacific, Arabian Sea, and high latitude North Atlantic show that severe depletions in 14C occurred at intermediate water depths during the last deglaciation. It has been suggested that 14C-depleted water from the abyss upwelled in the Southern Ocean and was then carried by Antarctic Intermediate Water (AAIW) to these sites. However, locations in the South Pacific in the direct path of modern-day AAIW do not exhibit the Δ 14C excursion and therefore cast doubt upon the AAIW mechanism ( De Pol-Holz et al., 2010; Rose et al., 2010). Here we evaluate whether or not a deglacial 14C anomaly occurred at intermediate depths in the Southwest Atlantic. We find that the deglacial benthic Δ 14C trend at our site is similar to the atmospheric Δ 14C trend. Our results are also largely consistent with results from U/Th-dated corals at shallower water depths on the Brazil Margin (Mangini et al., 2010). We find no evidence in the southwestern Atlantic of a ~ 300‰ decrease in intermediate water Δ 14C from 18 to 14 kyr BP like that observed in the eastern tropical Pacific ( Marchitto et al., 2007). When our results are paired with those from the South Pacific, it appears AAIW did not carry a highly 14C-depleted signal during the deglaciation. Another source of carbon is apparently required to explain the intermediate-depth Δ 14C anomalies in the North Atlantic, Indian, and Pacific Oceans.

  12. Carbon-14 wiggle-match dating of peat deposits: advantages and limitations

    NASA Astrophysics Data System (ADS)

    Blaauw, Maarten; van Geel, Bas; Mauquoy, Dmitri; van der Plicht, Johannes

    2004-02-01

    Carbon-14 wiggle-match dating (WMD) of peat deposits uses the non-linear relationship between 14C age and calendar age to match the shape of a series of closely spaced peat 14C dates with the 14C calibration curve. The method of WMD is discussed, and its advantages and limitations are compared with calibration of individual dates. A numerical approach to WMD is introduced that makes it possible to assess the precision of WMD chronologies. During several intervals of the Holocene, the 14C calibration curve shows less pronounced fluctuations. We assess whether wiggle-matching is also a feasible strategy for these parts of the 14C calibration curve. High-precision chronologies, such as obtainable with WMD, are needed for studies of rapid climate changes and their possible causes during the Holocene. Copyright

  13. Metabolism of small multiple doses of (14C) nicotine in the cat

    PubMed Central

    Turner, D. M.

    1971-01-01

    1. The distribution and metabolism of (2′-14C) nicotine given as a series of small intravenous injections (4 μg/kg every 60 s for 20 min) have been studied in the cat. 2. Blood concentrations of (14C) nicotine reached a maximum of 100 ng/ml at 20 min whereas blood concentrations of cotinine were maximal shortly afterwards. 3. The maximum concentration of nicotine in the blood was greater than that obtained by giving the same total dose as a continuous infusion ((4 μg/kg)/min for 20 min). 4. Urinary excretion accounted for 90% of the total multiple dose in 72 hours. After 24 h, however, only 2·5% of the radioactivity as (14C) nicotine and 0·05% as (14C) cotinine was excreted. 5. Gastric juice after 2 h contained significant amounts of activity which was almost entirely composed of (14C) nicotine and (14C) cotinine. 6. There were significant regional differences in the concentration of (14C) nicotine in the brain; amounts were greatest in cerebral hemispheres and smallest in the spinal cord. The hypothalamus and thalamus contained significantly higher concentrations of (14C) nicotine than the whole mid brain. (14C) Cotinine concentrations were highest in the cerebellum. PMID:5576257

  14. 14C content in aerosols in Mexico City

    NASA Astrophysics Data System (ADS)

    Gómez, V.; Solís, C.; Chávez, E.; Andrade, E.; Ortiz, M. E.; Huerta, A.; Aragón, J.; Rodríguez-Ceja, M.; Martínez, M. A.; Ortiz, E.

    2016-03-01

    14C-AMS of total carbon was determined in aerosols (PM10 fraction), collected in Mexico City during two weeks from 21 November to 3 December 2012. Other tracers such as total carbon (TC), organic carbon (OC), elemental carbon (EC) and trace element contents were also determined. F14C values varied from 0.39 to 0.48 with an average of 0.43. These values are slightly lower than those previously obtained for PM2.5 in 2003 and 2006 and reflect a high contribution of fossil CO2 to the carbonaceous matter in aerosols from Mexico City. In contrast, from 2006 to 2012 PM10 increased; EC, Ca, Ti and Fe concentrations remained constant, while OC, TC and K concentrations decreased. The use of potassium as an indicator of biomass burning showed that this source was negligible during this campaign. Combined analytical approaches allowed us to distinguish temporal variations of anthropogenic and natural inputs to the F14C.

  15. A Coral Based Reconstruction of Atmospheric Δ14C through the Mystery Interval (17.5 to 14.5 kyr BP)

    NASA Astrophysics Data System (ADS)

    Mortlock, R. A.; Abdul, N. A.; Wright, J. D.; Fairbanks, R. G.; Cao, L.

    2011-12-01

    Reconstructions of atmospheric Δ14C from various archives (speleothems, planktic foraminifera, surface corals) record a ~ 190 per mil (%) decrease in Δ14C during the Mystery Interval (17.5 to 14.5 kyr BP). It has been suggested that the decrease results from the injection of 14C depleted waters during the deglacial. Supporting evidence comes from benthic forams in sediment cores off Baja, CA that record a 300% decrease in the 14C content of intermediate waters at the same time ice core records display an increase in atmospheric CO2. Records of opal burial in Southern Ocean sediments suggest increased upwelling (and release of 14C depleted CO2 to the atmosphere) during the Mystery Interval. We have updated our previously published record of atmospheric Δ14C with an additional 60-paired radiocarbon and U-series dated surface corals. A unique advantage to using the fossil coral archive is that both radiocarbon and calendar ages can be obtained from the same sample, whereas atmospheric 14C reconstructions generated from deep sea core microfossils require assigned calendar ages which are based on proxies correlated to ice cores and are subject to proxy interpretations, correlation errors, and uncertainties in ice core chronologies. Unfortunately small inaccuracies in the estimated calendar ages lead to large Δ14C errors. The updated coral record adds considerable coverage to both the Mystery Interval (previously constrained by coral data only at the boundaries in INTCAL04 and 09), and for the time period 26 to 18 kyr BP. Our record permits a better estimate as to the timing, duration, and magnitude of the decrease in Δ14C during the Mystery Interval. We observe a break in the declining 27 to 21 kyr BP trend of Δ14C at about 20 kyr BP. From 20 to 18.5 kyr BP Δ14C increases by about 100% to a maximum value of about 430%. Δ14C decreases to 300% by about 17 kyr BP at which time the long term declining trend in Δ14C is re-established and continues throughout the

  16. Assessing open-system behavior of 14C in terrestrial gastropod shells

    USGS Publications Warehouse

    Rech, J.A.; Pigati, J.S.; Lehmann, S.B.; McGimpsey, C.N.; Grimley, D.A.; Nekola, J.C.

    2011-01-01

    In order to assess open-system behavior of radiocarbon in fossil gastropod shells, we measured the 14C activity on 10 aliquots of shell material recovered from Illinoian (~190-130 ka) and pre-Illinoian (~800 ka) loess and lacustrine deposits in the Midwestern USA. Eight of the 10 aliquots yielded measurable 14C activities that ranged from 0.25 to 0.53 percent modern carbon (pMC), corresponding to apparent 14C ages between 48.2 and 42.1 ka. This small level of open-system behavior is common in many materials that are used for 14C dating (e.g. charcoal), and typically sets the upper practical limit of the technique. Two aliquots of gastropod shells from the Illinoian-aged Petersburg Silt (Petersburg Section) in central Illinois, USA, however, yielded elevated 14C activities of 1.26 and 1.71 pMC, which correspond to apparent 14C ages of 35.1 and 32.7 ka. Together, these results suggest that while many fossil gastropods shells may not suffer from major (>1%) open-system problems, this is not always the case. We then examined the mineralogy, trace element chemistry, and physical characteristics of a suite of fossil and modern gastropod shells to identify the source of contamination in the Petersburg shells and assess the effectiveness of these screening techniques at identifying samples suitable for 14C dating. Mineralogical (XRD) and trace element analyses were inconclusive, which suggests that these techniques are not suitable for assessing open-system behavior in terrestrial gastropod shells. Analysis with scanning electron microscopy (SEM), however, identified secondary mineralization (calcium carbonate) primarily within the inner whorls of the Petersburg shells. This indicates that SEM examination, or possibly standard microscope examination, of the interior of gastropod shells should be used when selecting fossil gastropod shells for 14C dating. ?? 2011 by the Arizona Board of Regents on behalf of the University of Arizona.

  17. Assessing open-system behavior of 14C in terrestrial gastropod shells

    USGS Publications Warehouse

    Rech, Jason A.; Pigati, Jeffrey S.; Lehmann, Sophie B.; McGimpsey, Chelsea N.; Grimley, David A.; Nekola, Jeffrey C.

    2011-01-01

    In order to assess open-system behavior of radiocarbon in fossil gastropod shells, we measured the 14C activity on 10 aliquots of shell material recovered from Illinoian (~190-130 ka) and pre-Illinoian (~800 ka) loess and lacustrine deposits in the Midwestern USA. Eight of the 10 aliquots yielded measurable 14C activities that ranged from 0.25 to 0.53 percent modern carbon (pMC), corresponding to apparent 14C ages between 48.2 and 42.1 ka. This small level of open-system behavior is common in many materials that are used for 14C dating (e.g. charcoal), and typically sets the upper practical limit of the technique. Two aliquots of gastropod shells from the Illinoian-aged Petersburg Silt (Petersburg Section) in central Illinois, USA, however, yielded elevated 14C activities of 1.26 and 1.71 pMC, which correspond to apparent 14C ages of 35.1 and 32.7 ka. Together, these results suggest that while many fossil gastropods shells may not suffer from major (>1%) open-system problems, this is not always the case. We then examined the mineralogy, trace element chemistry, and physical characteristics of a suite of fossil and modern gastropod shells to identify the source of contamination in the Petersburg shells and assess the effectiveness of these screening techniques at identifying samples suitable for 14C dating. Mineralogical (XRD) and trace element analyses were inconclusive, which suggests that these techniques are not suitable for assessing open-system behavior in terrestrial gastropod shells. Analysis with scanning electron microscopy (SEM), however, identified secondary mineralization (calcium carbonate) primarily within the inner whorls of the Petersburg shells. This indicates that SEM examination, or possibly standard microscope examination, of the interior of gastropod shells should be used when selecting fossil gastropod shells for 14C dating.

  18. Effects of sample mass and macrofossil type on radiocarbon dating of arctic and boreal lake sediments

    SciTech Connect

    Oswald, W W; Anderson, P M; Brown, T A; Brubaker, L B; Hu, F S; Lozhkin, A V; Tinner, W; Kaltenrieder, P

    2006-05-29

    Dating lake sediments by accelerator mass spectrometry (AMS) {sup 14}C analysis of plant macrofossils overcomes one of the main problems associated with dating bulk sediment samples, the presence of old organic matter. Even so, many AMS dates from arctic and boreal sites appear to misrepresent the age of the sediment. To understand the nature of these apparent dating anomalies better, we conducted a series of {sup 14}C dating experiments using samples from Alaskan and Siberian lake-sediment cores. First, to test whether our analytical procedures introduced a sample-mass bias, we obtained {sup 14}C dates for different-sized pieces of single woody macrofossils. In these sample-mass experiments, sized statistically equivalent ages were found for samples as small as 0.05 mg C. Second, to assess whether macrofossil type influenced dating results, we conducted sample-type experiments in which {sup 14}C dates were obtained for different macrofossil types sieved from the same depth in the sediment. We dated materials from multiple levels in sediment cores from Upper Capsule Lake (North Slope, northern Alaska) and Grizzly Lake (Copper River Basin, southern Alaska), and from single depths in other records from northern Alaska. In several of the experiments there were significant discrepancies between dates for different plant tissues, and in most cases wood and charcoal were older than other macrofossil types, usually by several hundred years. This pattern suggests that {sup 14}C dates for woody macrofossils may misrepresent the age of the sediment by centuries, perhaps due to their longer terrestrial residence time and the potential in-built age of long-lived plants. This study identifies why some {sup 14}C dates appear to be inconsistent with the overall age-depth trend of a lake-sediment record, and it may guide the selection of {sup 14}C samples in future studies.

  19. The 14C Record in Bristlecone Pine Wood of the past 8000 Years Based on the Dendrochronology of the Late C. W. Ferguson

    NASA Astrophysics Data System (ADS)

    Suess, H. E.; Linick, T. W.

    1990-04-01

    When, in 1950, Willard Libby and his coworkers obtained their first radiocarbon (14C) dates, C. W. Ferguson at the University of Arizona Tree Ring Laboratory was working on establishing a continuous tree ring series for the newly discovered bristlecone pine Pinus aristata. Before his untimely death in 1986, he had extended the series nearly 8000 years into the past. From the Ferguson series I obtained for 14C determinations wood samples grown at various times. Also, two other laboratories obtained such samples. For B.C. times in particular, our measured 14C-values that deviated consistently from those calculated from tree rings, and the deviations increased with age. This general trend was observed by other laboratories, but the presence of deviations from these trends, of the so-called `wiggles', was questioned by other workers. To me these wiggles indicated the existence of a most interesting geophysical parameter valid for the whole terrestrial atmosphere. Fourier spectra obtained at my request by Kruse in 1972, and by Neftel, demonstrated the consistency of the results, and supported my contention that the secular variations of 14C in atmospheric CO2 are related to variations of solar activity.

  20. Bioconversion of. cap alpha. -(/sup 14/C)Zearalenol and. beta. -(/sup 14/C)Zearalenol into (/sup 14/C)Zearalenone by Fusarium roseum Gibbosum

    SciTech Connect

    Richardson, K.E.; Hagler, W.M. Jr.; Hamilton, P.B.

    1984-06-01

    Cultures of Fusarium roseum Gibbosum on rice were treated with (/sup 14/C)zearalenone, ..cap alpha..-(/sup 14/C)zearalenol, or ..beta..-(/sup 14/C)zearalenol to determine whether a precursor-product relationship exists among these closely related fungal metabolites. Culture extracts were purified by silica gel column chromatography and fractionated by high-pressure liquid chromatography, and the level of radioactivity was determined. Within 7 days, the ..beta..-(/sup 14/C)zearalenol was converted to zearalenone, and no residual ..beta..-(/sup 14/C)zearalenol was detectable. Most of the ..cap alpha..-(/sup 14/C)zearalenol added was also converted into zearalenone within 14 days. In cultures treated with (/sup 14/C)zearalenone, no radioactivity was noted in any other components.

  1. Bomb-pulse 14C analysis combined with 13C and 15N measurements in blood serum from residents of Malmö, Sweden.

    PubMed

    Georgiadou, Elisavet; Stenström, Kristina Eriksson; Uvo, Cintia Bertacchi; Nilsson, Peter; Skog, Göran; Mattsson, Sören

    2013-05-01

    The (14)C content of 60 human blood serum samples from residents of Malmö (Sweden) in 1978, obtained from a biobank, has been measured to estimate the accuracy of (14)C bomb-pulse dating. The difference between the date estimated using the Calibomb software and sampling date varied between -3 ± 0.4 and +0.2 ± 0.5 years. The average age deviation of all samples was -1.5 ± 0.7 years, with the delay between production and consumption of foodstuffs being probably the dominating cause. The potential influence of food habits on the (14)C date has been evaluated using stable isotope δ(13)C and δ(15)N analysis and information about the dietary habits of the investigated individuals. Although the group consisting of lacto-ovo vegetarians and vegans (pooled group) was not completely separated from the omnivores in a stable isotopic trophic level diagram, this analysis proved to add valuable information on probable dietary habits. The age deviation of the sampling date from the respective Calibomb date was found strongly correlated with the δ(13)C values, probably due to influence from marine diet components. For the omnivore individuals, there were indications of seasonal effects on δ(13)C and the age deviation. No significant correlation was found between the age deviation and the δ(15)N values of any dietary group. No influence of sex or year of birth was found on neither the (14)C nor the δ(13)C and δ(15)N values of the serum samples. The data were also divided into two groups (omnivores and pooled group), based on the level of δ(15)N in the samples. The consumption of high δ(15)N-valued fish and birds can be responsible for this clustering.

  2. Refined modeling and 14C plateau tuning reveal consistent patterns of glacial and deglacial 14C reservoir ages of surface waters in low-latitude Atlantic

    NASA Astrophysics Data System (ADS)

    Balmer, Sven; Sarnthein, Michael; Mudelsee, Manfred; Grootes, Pieter M.

    2016-08-01

    Modeling studies predict that changes in radiocarbon (14C) reservoir ages of surface waters during the last deglacial episode will reflect changes in both atmospheric 14C concentration and ocean circulation including the Atlantic Meridional Overturning Circulation. Tests of these models require the availability of accurate 14C reservoir ages in well-dated late Quaternary time series. We here test two models using plateau-tuned 14C time series in multiple well-placed sediment core age-depth sequences throughout the lower latitudes of the Atlantic Ocean. 14C age plateau tuning in glacial and deglacial sequences provides accurate calendar year ages that differ by as much as 500-2500 years from those based on assumed global reservoir ages around 400 years. This study demonstrates increases in local Atlantic surface reservoir ages of up to 1000 years during the Last Glacial Maximum, ages that reflect stronger trades off Benguela and summer winds off southern Brazil. By contrast, surface water reservoir ages remained close to zero in the Cariaco Basin in the southern Caribbean due to lagoon-style isolation and persistently strong atmospheric CO2 exchange. Later, during the early deglacial (16 ka) reservoir ages decreased to a minimum of 170-420 14C years throughout the South Atlantic, likely in response to the rapid rise in atmospheric pCO2 and Antarctic temperatures occurring then. Changes in magnitude and geographic distribution of 14C reservoir ages of peak glacial and deglacial surface waters deviate from the results of Franke et al. (2008) but are generally consistent with those of the more advanced ocean circulation model of Butzin et al. (2012).

  3. Distribution of photosynthetically fixed /sup 14/C in perennial plant species of the northern Mojave Desert

    SciTech Connect

    Wallace, A.; Cha, J.W.; Romney, E.M.

    1980-01-01

    The distribution of photosynthate among plant parts subsequent to its production is needed to fully understand behavior of vegetation in any ecosystem. The present study, undertaken primarily to obtain information on transport of assimilates into roots of desert vegetation, was conducted in the northern Mojave Desert, where the mean annual rainfall is about 10 cm. Shoots of Ambrosia dumosa (A. Gray) Payne plants were exposed to /sup 14/CO/sub 2/ in 1971, and the distribution of /sup 14/C in roots, stems, and leaves was subsequently measured at 1 week, 2 months, and 5 months. Only about 12 percent of the /sup 14/C photosynthate was stored in the root. Much of that stored in stems was available for new leaf growth. Photosynthate was labeled with /sup 14/C for 24 plants representing eight species in 1972. Results showed that after 127 days the mean percentage of /sup 14/C in roots as compared with the estimate of that originally fixed was 11.8; the percentage in stems was 43.8. To check the validity of the /sup 14/C data, root growth of eight perennial desert plants grown in the glasshouse was followed as plants increased in size. The mean percent of the whole plant that was root for eight species was 17.7 percent. The mean proportion of the increase in plant weights that went below ground for the eight species was 19.5 percent. This value is higher than the fraction of /sup 14/C found below ground, and therefore the /sup 14/C technique underestimates the movement of C to roots. Results of an experiment designed to test the value of the /sup 14/C-pulse technique for determining current root growth for some perennial species from the desert indicated that the transition part of roots where root growth continued after exposure to /sup 14/C was highly labeled. Old growth contained less /sup 14/C than new growth.

  4. Comparison of Varve and 14C Chronologies from Steel Lake, Minnesota, USA

    SciTech Connect

    Tian, J; Brown, T A; Hu, F S

    2004-12-29

    Annually laminated sediments (varves) offer an effective means of acquiring high-quality paleoenvironmental records. However, the strength of a varve chronology can be compromised by a number of factors, such as missing varves, ambiguous laminations, and human counting error. We assess the quality of a varve chronology for the last three millennia from Steel Lake, Minnesota, through comparisons with nine AMS {sup 14}C dates on terrestrial plant macrofossils from the same core. These comparisons revealed an overall 8.4% discrepancy, primarily because of missing/uncountable varves within two stratigraphic intervals characterized by low carbonate concentrations and obscure laminations. Application of appropriate correction factors to these two intervals results in excellent agreement between the varve and {sup 14}C chronologies. These results, together with other varve studies, demonstrate that an independent age-determination method, such as {sup 14}C dating, is usually necessary to verify, and potentially correct, varve chronologies.

  5. The distribution of Δ14C in Korea from 2010 to 2013

    NASA Astrophysics Data System (ADS)

    Park, J. H.; Hong, W.; Xu, X.; Park, G.; Sung, K. S.; Sung, Kilho; Lee, Jong-geol; Nakanishi, T.; Park, Hyo-Seok

    2015-10-01

    Δ14C values of leaves of a deciduous tree record to those of atmospheric CO2 within error and were used to map out Δ14C distribution in Korea. We collected ginkgo (Ginkgo biloba Linnaeus, a deciduous tree) leaf samples in mid-June to early July from 2009 to 2013 in Korea to obtain the regional distribution of Δ14C. Commonly CO2 emitted from fossil fuel consumption dilutes atmospheric 14C, while operations and accidents at nuclear power plants can increase it. The distribution maps of Δ14C from 2010 to 2013 in Korea shows that Δ14C values in the northwestern and southeastern parts of Korea are lower than those of the other parts of Korea, which is consistent with the population and industry patterns. Decrease rates of annually averaged Δ14C values in Korea over the study period are larger than those of Pt. Barrow, Alaska, USA (71.3°N, 156.5°W), so the difference between them and those of Pt. Barrow, Alaska, USA became larger annually. This may be due to the increase in fossil fuel consumption in Korea and China. The decrease rate between 2010 and 2011 was smaller than in other years. This could be the effect of the Fukushima power plant accident which occurred in March 11, 2011, but further study is needed to clarify it.

  6. Structure of ^27Na Using the ^14C(^14C,p) Reaction

    NASA Astrophysics Data System (ADS)

    Cooper, M. W.; Campbell, D. B.; Chandler, C.; Kemper, K. W.; Pipidis, A.; Riley, M. A.; Wiedeking, M.; Tabor, S. L.; Ragnarsson, I.

    2000-10-01

    Several new transitions in ^27Na were found using the ^14C(^14C,p) reaction at 22 MeV. The ^14C target was 0.28 mg/cm^2 thick and the beam was stopped in a 33.8 mg/cm^2 Au foil. γ-γ, particle-γ, and particle-γ-γ coincidences were measured using 2 four-crystal Eurogam type ``clover'' detectors, 7 Compton suppressed HPGe detectors, and a particle E-ΔE telescope at 0^circ.The 67, 1660, 1752, 1820, and 2222 keV transitions, which are in coincidence with the high energy protons, have been identified as transitions in ^27Na. Some of the resulting levels correspond to particle groups seen in an earlier ^26Mg(^18O, ^17F) reaction (L.K. Fifield et al.), Nucl. Phys. A437, 141 (1985).. The results will be discussed in terms of both the shell model and the cranked Nilsson-Strutinsky rotational model.

  7. Extraction of /sup 14/C-labeled photosynthate from aquatic plants with dimethyl sulfoxide (DMSO)

    SciTech Connect

    Filbin, G.J.; Hough, R.A.

    1984-03-01

    DMSO was tested as a solvent to extract /sup 14/C-labeled photosynthate from three species of aquatic plants in photosynthesis measurements and compared with the dry oxidation method for plant radioassay. Extraction efficiency was in the range of 96-99% of fixed /sup 14/C, and precision was comparable to, or better than, that obtained with dry oxidation. The method is simple and inexpensive, and for fresh tissue the same sample extracts can be used for chlorophyll analyses.

  8. Modelling of dead carbon fraction in speleothems: a step towards reliable speleothem 14C-chronologies

    NASA Astrophysics Data System (ADS)

    Lechleitner, Franziska A.; Jamieson, Robert A.; McIntyre, Cameron; Baldini, Lisa M.; Baldini, James U. L.; Eglinton, Timothy I.

    2015-04-01

    Over the past two decades, speleothems have become one of the most versatile and promising archives for the study of past continental climate. Very precise absolute dating is often possible using the U-Th method, resulting in paleoclimate records of exceptional resolution and accuracy. However, not all speleothems are amenable to this dating method for a variety of reasons (e.g. low U concentrations, high detrital Th etc). This has lead researchers to exclude many otherwise suitable speleothems and cave sites from further investigation. 14C-dating of speleothems has so far not been applicable, due to the 'dead carbon' problem. As drip water percolates through the karst, dissolving CaCO3, a variable amount of 14C-dead carbon is added to the solution. This results in a temporally variable and site-specific reservoir effect, ultimately undermining the development of speleothem 14C -chronologies. However, a number of recent studies have shown a clear link between karst hydrology and associated proxies (e.g., Mg/Ca and δ13C) and this 'dead carbon fraction' (DCF). We take advantage of this relationship to model DCF and its changes using Mg/Ca, δ13C and 14C data from published speleothem records. Using one record for calibration purposes, we build a transfer function for the DCF in relation to δ13C and Mg/Ca, which we then apply to other 14C records. Initial model results are promising; we are able to reconstruct general long-term average DCF within uncertainties of the calculated DCF from the U-Th chronology. Large shifts in DCF related to hydrology are also often detected. In a second step, we apply the model to a speleothem from southern Poland, which so far could not be dated, due to very low U-concentrations. To construct a 14C chronology, the stalagmite was sampled at 5 mm intervals. CaCO3 powders were graphitized and measured by Accelerator Mass Spectrometry (MICADAS) at ETH Zurich. Additional high-resolution (0.1 mm/sample) 14C measurements were performed on

  9. Atmospheric 14 C CO 2 variations in Japan during 1982--1999 based on 14 C measurements of rice grains.

    PubMed

    Shibata, Setsuko; Kawano, Eiko; Nakabayashi, Takeshige

    2005-08-01

    (14)C in rice grains is a useful tracer of atmospheric (14)C(CO(2)). (14)C measurement in rice grains for 17 years during 1982--1999 reveals the following. There is negative correlation between Delta(14)C and the population densities of localities in Japan. Under-populated areas in the northern area of Japan and Okinawa remained clean in the 1990s. The (14)C(CO(2)) decline rates at those areas are near to that of Shauinsland. A latitudinal effect due to Chinese nuclear tests is observed in 1982. Small Seuss effects is observed at the middle latitudes in East Asia after 1995.

  10. No evidence for a deglacial intermediate water Δ14C anomaly in the SW Atlantic

    NASA Astrophysics Data System (ADS)

    Sortor, R. N.; Lund, D. C.

    2011-12-01

    The last deglaciation was characterized by an increase in atmospheric pCO2 and decrease in atmospheric radiocarbon activity. One hypothesis is that these changes were due to out-gassing of 14C-depleted carbon from the abyssal ocean (Broecker and Barker, 2007). Reconstructions of foraminiferal Δ14C from the eastern tropical Pacific (Marchitto et al., 2007; Stott et al. 2009), Arabian Sea (Bryan et al., 2010), and high latitude North Atlantic (Thornalley et al., 2011) show that severe depletions in 14C occurred at intermediate water depths during the last deglaciation. It has been suggested that 14C-depleted water from the abyss upwelled in the Southern Ocean and was then carried by Antarctic Intermediate Water (AAIW) to these sites (Marchitto et al., 2007). On the South Icelandic Rise, Thornalley et al. (2011) find deglacial Δ14C values up to 600% lower than the atmosphere. Since North Atlantic deep waters are not believed to be old enough to cause such an anomaly (Robinson et al. 2005), one possible source is AAIW (Thornalley et al., 2011). Here we evaluate whether or not a large deglacial 14C anomaly occurred at intermediate depths in the Southwest Atlantic. We find that the deglacial Δ14C trend at our site is similar to the atmospheric Δ14C trend. Our results are also largely consistent with data from U/Th-dated corals at shallower water depths on the Brazil Margin (Mangini et al., 2010). We find no evidence in the southwestern Atlantic of large deglacial Δ14C anomalies like those observed in the high latitude North Atlantic (Thornalley et al., 2011). When our results are paired with those from the South Pacific (De Pol-Holz et al., 2010; Rose et al., 2010), it appears AAIW did not carry a highly 14C- depleted signal during the deglaciation. Another source of carbon is apparently required to explain the intermediate-depth Δ14C anomalies in the North Atlantic, Indian, and Pacific Oceans.

  11. Uptake and distribution of /sup 14/C during and following exposure to (/sup 14/C)methyl isocyanate

    SciTech Connect

    Ferguson, J.S.; Kennedy, A.L.; Stock, M.F.; Brown, W.E.; Alarie, Y.

    1988-06-15

    Guinea pigs were exposed to (/sup 14/C)methyl isocyanate (/sup 14/CH/sub 3/-NCO, /sup 14/C MIC) for periods of 1 to 6 hr at concentrations of 0.5 to 15 ppm. Arterial blood samples taken during exposure revealed immediate and rapid uptake of /sup 14/C. Clearance of /sup 14/C was then gradual over a period of 3 days. Similarly /sup 14/C was present in urine and bile immediately following exposure, and clearance paralleled that observed in blood. Guinea pigs fitted with a tracheal cannula and exposed while under anesthesia showed a reduced /sup 14/C uptake in blood indicating that most of the /sup 14/C MIC uptake in normal guinea pigs occurred from retention of this agent in the upper respiratory tract passages. In exposed guinea pigs /sup 14/C was distributed to all examined tissues. In pregnant female mice similarly exposed to /sup 14/C MIC, /sup 14/C was observed in all tissues examined following exposure including the uterus, placenta, and fetus. While the form of /sup 14/C distributed in blood and tissues has not yet been identified, these findings may help to explain the toxicity of MIC or MIC reaction products on organs other than the respiratory tract, as noted by several investigators.

  12. The metabolism of [14C]nicotine in the cat

    PubMed Central

    Turner, D. M.

    1969-01-01

    The metabolism of [2′-14C]nicotine given as an intravenous injection in small doses to anaesthetized and unanaesthetized cats has been studied. A method is described for the quantitative determination of [14C]nicotine and [14C]cotinine in tissues and body fluids. Nanogram amounts of these compounds have been detected. After a single dose of 40μg. of [14C]nicotine/kg., 55% of the injected radioactivity was excreted in the urine within 24hr., but only 1% of this radioactivity was unchanged nicotine. [14C]Nicotine is metabolized extremely rapidly, [14C]cotinine appearing in the blood within 2·5min. of intravenous injection. [14C]Nicotine accumulates rapidly in the brain and 15min. after injection 90% of the radioactivity still represents [14C]nicotine. Metabolites of [14C]nicotine have been identified in liver and urine extracts. [14C]Nicotine-1′-oxide has been detected in both liver and urine. PMID:5360723

  13. Enhancement of radioactivity of /sup 14/C-/sup 12/C mixtures via partial reduction

    SciTech Connect

    Stevenson, G.R.; Lauricella, T.L.

    1986-08-20

    The solution electron affinities of perdeuterated polyaromatics are less than those of the protiated materials. This observation prompted the investigation of the possibility of increasing the radioactivity of benzophenone-carbonyl-/sup 14/C (BZO-14C)-cold benzophenone (BZO-12C) mixtures via the partial reduction of these mixtures to the ketyls. The /sup 14/C-depleted benzophenones left in the reaction vessel in the form of Na/sup +/(NH/sub 3/)BZO/sup -/ can be recovered by simply adding a solution of I/sub 2/ in tetrahydrofuran to the solid salt. Further, there is no theoretical limit as to how much the radioactivity of the sample can be enhanced by passing /sup 14/C-enhanced material through this process consecutively, up to the point where the pure carbon-14 compound is obtained.

  14. Mannosyltransferase activity in calf pancreas microsomes. Formation of 14C-labeled lipid-linked oligosaccharides from GDP-D-[14C]mannose and pancreatic dolichyl beta-D-[14C]mannopyranosyl phosphate.

    PubMed

    Herscovics, A; Golovtchenko, A M; Warren, C D; Bugge, B; Jeanloz, R W

    1977-01-10

    Calf pancreas microsomes incorporated radioactive D-mannose from GDP-D-[14C]mannose into lipid-bound oligosaccharides extracted with chloroform/methanol/water (10/10/2.5, v/v). Several products, which probably differed in the size of the oligosaccharide moiety, were labeled. These could be partially resolved by thin layer chromatography and DEAE-cellulose chromatography. The labeled lipid-bound oligosaccharides were retained on DEAE-cellulose more strongly than synthetic dolichyl alpha-D-[14C]mannopyranosyl phosphate. They were stable to mild alkali, but labile to acid and hot alkali. Acid treatment yielded a neutral 14C-labeled oligosaccharide fraction which was estimated by gel filtration to have a minimum of 8 monosaccharide residues. Hot alkali treatment yielded a mixture of neutral and acidic 14C-labeled oligosaccharides which could be transformed into neutral products by alkaline phosphatase. The D-[14C]mannose residues were alpha-linked at the nonreducing terminus of the oligosaccharides since they could be removed completely with alpha-mannosidase. Most of the D-[14C]mannose-labeled oligosaccharides were retained on concanavalin A Sepharose and eluted with methyl alpha-D-mannopyranoside. Pancreatic dolichyl beta-D-[14C]mannopyranosyl phosphate incubated with calf pancreas microsomes in the presence of sodium taurocholate was efficiently utilized as donor of alpha-D-mannosyl residues in lipid-bound oligosaccharides. The products formed from dolichyl beta-D-[14C]mannopyranosyl phosphate were identical with those formed from GDP-D-[14C]mannose, and evidence was obtained to show that the dolichyl beta-D-[14C]mannopyranosyl phosphate was serving as donor without prior conversion to GDP-D-[14C]mannose. Transfer of mannose from dolichyl beta-D-[14C]mannopyranosyl phosphate to lipid-bound oligosaccharides took place at a pH optimum of 7.3, whereas transfer to the precipitate containing glycoproteins was greatest at pH 6.0 in Tris/maleate buffer. The addition of

  15. Metabolism of a new herbicide, [(14)c]pyribenzoxim, in rice.

    PubMed

    Chang, Hee-Ra; Keum, Young Soo; Koo, Suk-Jin; Moon, Joon-Kwan; Kim, Kyun; Kim, Jeong-Han

    2011-03-01

    The in vivo metabolism of a new herbicide pyribenzoxim (benzophenone Ο-[2,6-bis(4,6-dimethoxypyrimidin-2-yloxy)benzoyl]oxime) in rice was carried out using container trials. Two radiolabeled forms of [carbonyl-(14)C]pyribenzoxim (P1) and [ring-(14)C(U)]pyribenzoxim (P2) were treated separately as formulations for foliar treatment by single applications of 50 g of active ingredient (ai)/ha at the 4-6 leaves stage. At 0, 7, 30, and 60 days after treatment (DAT), samples of panicle, foliage/rest of plant, and roots were taken for analysis. Upon harvest (120 DAT), rice plants were separated into grain, husk, straw, and root parts. Total radioactive residues (TRRs) at each sampling date were determined to show that the final radioactive residues at harvest were low in grain, husk, straw, and roots, accounting for <17 ppb. The concentration of final residues in the rice plant decreased rapidly, and less than 0.1% of initial TRRs remained at harvest. At 7 DAT, metabolite 1 [M1, 2,6-bis(4,6-dimethoxypyrimidin-2-yloxy)benzoic acid] and two unknown compounds (other-1 and other-2) were detected in foliage extract, accounting for 3.5% TRRs (21.0 ppb), 3.1% TRRs (19.0 ppb), and 9.0% TRRs (54.3 ppb), respectively, while 26.1% of M1 was observed in solvent wash. Any other metabolites were not detected in the plant, including expected metabolite M3 (benzophenone oxime). On the basis of the results obtained, a metabolic pathway of pyribenzoxim in a rice plant was proposed. PMID:21309510

  16. Tracing terrestrial carbon: a novel application of ∆14C in a humic lake

    NASA Astrophysics Data System (ADS)

    Keaveney, Evelyn; Reimer, Paula J.; Foy, Robert H.

    2016-04-01

    Lakes play an important yet underrated role in global carbon cycles. Terrestrial carbon (C) is buried and/or remineralised in significant quantities, and lake function may also be affected by catchment inputs with potential feedbacks for regional and global C cycling. Changing deposition chemistry, land use and climate induced impacts on hydrology will affect soil biogeochemistry, terrestrial C export, and hence lake ecology. Autochthonous production in lakes is based on dissolved inorganic C (DIC). DIC in alkaline lakes is partially derived from weathering of carbonaceous bedrock, a proportion of which is 14C-free. The low 14C activity yields an artificial age offset leading samples to appear hundreds to thousands of years older than their actual age. Dissolved organic carbon (DOC) and particulate organic carbon (POC) can contain terrestrial inputs. The terrestrial inputs can be labile or detrital and their age depends to a first order on their depth in catchment soil/peat stocks. We present a pilot study that uses the radiocarbon (∆14C) method to determine the source of carbon buried in the surface sediment of Lower Lough Erne, a humic, alkaline lake in northwest Ireland. ∆14C, δ13C and δ15N values were measured from phytoplankton and other biota, dissolved inorganic, dissolved organic and particulate organic carbon. A novel radiocarbon method, Stepped Combustion1 was used to estimate the degree of the burial of terrestrial carbon in surface sediment, collected in 2011. The ∆14C values of the low temperature fractions were comparable to algal ∆14C, while the high temperature fractions were 14C-depleted (older than bulk sediment). The ∆14C end-member model indicated that ~64% of carbon in surface sediment was derived from detrital terrestrial carbon. The same proportion of detrital/labile carbon was found in surface sediment of Upper Lough Erne in 2014, despite the differences in lake type and collection date. The use of ∆14C in conjunction with

  17. 14C activity and global carbon cycle changes over the past 50,000 years.

    PubMed

    Hughen, K; Lehman, S; Southon, J; Overpeck, J; Marchal, O; Herring, C; Turnbull, J

    2004-01-01

    A series of 14C measurements in Ocean Drilling Program cores from the tropical Cariaco Basin, which have been correlated to the annual-layer counted chronology for the Greenland Ice Sheet Project 2 (GISP2) ice core, provides a high-resolution calibration of the radiocarbon time scale back to 50,000 years before the present. Independent radiometric dating of events correlated to GISP2 suggests that the calibration is accurate. Reconstructed 14C activities varied substantially during the last glacial period, including sharp peaks synchronous with the Laschamp and Mono Lake geomagnetic field intensity minimal and cosmogenic nuclide peaks in ice cores and marine sediments. Simulations with a geochemical box model suggest that much of the variability can be explained by geomagnetically modulated changes in 14C production rate together with plausible changes in deep-ocean ventilation and the global carbon cycle during glaciation.

  18. Large spatial variations in coastal 14C reservoir age - a case study from the Baltic Sea

    NASA Astrophysics Data System (ADS)

    Lougheed, B. C.; Filipsson, H. L.; Snowball, I.

    2013-05-01

    Coastal locations are highly influenced by input from freshwater river runoff, including sources of terrestrial carbon, which can be expected to modify the 14C reservoir age, or R (t), associated with marine water. In this Baltic Sea case study, pre-bomb museum collection mollusc shells of known calendar age, from 30 locations across a strategic salinity transect of the Baltic Sea, were analysed for 14C, δ13C and δ18O. R (t) was calculated for all 30 locations. Seven locations, of which six are within close proximity of the coast, were found to have relatively higher R (t) values, indicative of hard-water effects. Whenever possible, the Macoma genus of mollusc was selected from the museum collections, in order to exclude species specific reservoir age effects as much as possible. When the Macoma samples are exclusively considered, and samples from hard-water locations excluded, a statistically significant correlation between Macoma R (t) and average salinity is found, indicating a two end-member linear mixing model between 14Cmarine and 14Crunoff. A map of Baltic Sea Macoma aragonite R (t) for the late 19th and early 20th centuries is produced. Such a map can provide an estimate for contemporary Baltic Sea Macoma R (t), although one must exercise caution when applying such estimates back in time or to 14C dates obtained from different sample material. A statistically significant correlation is found between δ18Oaragonite and Macoma R (t), suggesting that δ18Oaragonite can be used to estimate Macoma palaeo-R (t), due to the δ18Oaragonite signal being dominated by the salinity gradient of the Baltic Sea. A slightly increased correlation can be expected when δ18Oaragonite is corrected for temperature fractionation effects. The results of this Baltic Sea case study, which show that R (t) is affected by hydrographic conditions and local carbon inputs, have important consequences for other coastal and estuarine locations, where R (t) is also likely to significantly

  19. Large spatial variations in coastal 14C reservoir age - a case study from the Baltic Sea

    NASA Astrophysics Data System (ADS)

    Lougheed, B. C.; Filipsson, H. L.; Snowball, I.

    2013-02-01

    Coastal locations are highly influenced by input from freshwater river runoff, including sources of terrestrial carbon, which can be expected to modify the 14C reservoir age, or R(t), associated with marine water. In this Baltic Sea case study, pre-bomb museum collection mollusc shells of known calendar age, from 30 locations across a strategic salinity transect of the Baltic Sea, were analysed for 14C, δ13C and δ18O. R(t) was calculated for all 30 locations. Seven locations, of which six are within close proximity of the coast, were found to have relatively higher R(t) values, indicative of hard-water effects. δ13Caragonite values were found to be indicative of hard-water influence only for certain locations, suggesting the possibility of different sources of old carbon in different locations. Whenever possible, the Macoma genus of mollusc was selected from the museum collections, in order to exclude species specific reservoir age effects as much as possible. When the Macoma samples are exclusively considered, and samples from hard-water locations excluded, a statistically significant correlation between Macoma R(t) and average salinity is found, indicating a two end-member linear mixing model between 14Cmarine and 14Crunoff. A map of Baltic Sea Macoma aragonite R(t) for the late 19th and early 20th centuries is produced. Such a map can provide an estimate for contemporary Baltic Sea Macoma R(t), although one must exercise caution when applying such estimates back in time or to 14C dates obtained from different sample material. A statistically significant correlation is also found between δ18Oaragonite and Macoma R(t), suggesting that δ18Oaragonite can be used to estimate Macoma palaeo-R(t). The results of this Baltic Sea case study, which show that R(t) is affected by hydrographic conditions and local carbon inputs, have important consequences for other coastal and estuarine locations, where R(t) is also likely to significantly vary on spatial and temporal

  20. Root-uptake of (14)C derived from acetic acid and (14)C transfer to rice edible parts.

    PubMed

    Ogiyama, Shinichi; Suzuki, Hiroyuki; Inubushi, Kazuyuki; Takeda, Hiroshi; Uchida, Shigeo

    2010-02-01

    Three types of culture experiments using paddy rice (Oryza sativa L.) were performed to examine root-uptake of (14)C in the form of acetic acid: double pot experiment (hydroponics), wet culture experiment (submerged sand medium), and chamber experiment (hydroponics and submerged sand medium). The (14)C radioactivity in the plant, mediums, and atmospheric carbon dioxide ((14)CO(2)) in the chamber were determined, and the distribution of (14)C in the plant was visualized using autoradiography. In the double pot experiment, the shoot of the plant and the lower root which was soaked in the culture solution had (14)C radioactivity, but the upper root which did not have contact with the solution had none. There were also (14)C radioactivity in the grains and roots in the wet culture experiment. Results of the chamber experiment showed that (14)CO(2) gas was released from the culture solution in both types of cultures. Results indicated that the (14)C-acetic acid absorbed by rice plant through its root would be very small. Most of the (14)C-acetic acid was transformed into gaseous forms either in the culture solution or rhizosphere. A relatively longer time would be needed to assimilate (14)C derived from acetic acid to grain parts after it was once absorbed by the shoot through the root. Availability of (14)C for the plant in sand culture was considered to be decreased compared with that for the plant in the hydroponics experiment. It was suggested that rice plant absorbed and assimilated (14)C through the plant roots not because of uptake of (14)C-acetic acid but because of uptake of (14)C in gaseous forms such as (14)CO(2). PMID:19962904

  1. 17 CFR 240.14c-1 - Definitions.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... to indicate a relationship with any person, means: (1) Any corporation or organization (other than..., addresses and securities positions of beneficial owners has been given pursuant to § 240.14c-7(b)(3... purposes of § 240.14c-7, the term “record holder” means any broker, dealer, voting trustee,...

  2. Percutaneous absorption of [14C]DDT and [14C]benzo[a]pyrene from soil.

    PubMed

    Wester, R C; Maibach, H I; Bucks, D A; Sedik, L; Melendres, J; Liao, C; DiZio, S

    1990-10-01

    The objective was to determine percutaneous absorption of DDT and benzo[a]pyrene in vitro and in vivo from soil into and through skin. Soil (Yolo County 65-California-57-8; 26% sand, 26% clay, 48% silt) was passed through 10-, 20-, and 48-mesh sieves. Soil then retained by 80-mesh was mixed with [14C]-labeled chemical at 10 ppm. Acetone solutions at 10 ppm were prepared for comparative analysis. Human cadaver skin was dermatomed to 500 microns and used in glass diffusion cells with human plasma as the receptor fluid (3 ml/hr flow rate) for a 24-hr skin application time. With acetone vehicle, DDT (18.1 +/- 13.4%) readily penetrated into human skin. Significantly less DDT (1.0 +/- 0.7%) penetrated into human skin from soil. DDT would not partition from human skin into human plasma in the receptor phase (less than 0.1%). With acetone vehicle, benzo[a]pyrene (23.7 +/- 9.7%) readily penetrated into human skin. Significantly less benzo[a]pyrene (1.4 +/- 0.9%) penetrated into human skin from soil. Benzo[a]pyrene would not partition from human skin into human plasma in the receptor phase (less than 0.1%). Substantivity (skin retention) was investigated by applying 14C-labeled chemical to human skin in vitro for only 25 min. After soap and water wash, 16.7 +/- 13.2% of DDT applied in acetone remained absorbed to skin. With soil only 0.25 +/- 0.11% of DDT remained absorbed to skin. After soap and water wash 5.1 +/- 2.1% of benzo[a]pyrene applied in acetone remained absorbed to skin. With soil only 0.14 +/- 0.13% of benzo[a]pyrene remained absorbed to skin.(ABSTRACT TRUNCATED AT 250 WORDS)

  3. Decay of sup 226 Ra by sup 14 C emission

    SciTech Connect

    Weselka, D.; Hille, P.; Chalupka, A. )

    1990-02-01

    Previous observation of heavy-ion emission from {sup 226}Ra has been confirmed. Charge and energy of the emitted fragment were measured using thin {sup 226}Ra sources and polycarbonate track-recording films. Decay by {sup 14}C emission could be identified unambiguously. The track-detector was calibrated with tandem-accelerated {sup 14}C and {sup 16}O ions and tested by observing the {sup 14}C emission from {sup 223}Ra yielding a branching ratio of (5.0{plus minus}1.0){times}10{sup {minus}10}. In the case of {sup 226}Ra our result for the {sup 14}C/{alpha} ratio is (2.3{plus minus}0.8){times}10{sup {minus}11}. Estimates of partial half-lives of Ra isotopes for {sup 14}C emission are discussed.

  4. Carbon cycling in a complex lake: a novel use of Δ14C

    NASA Astrophysics Data System (ADS)

    Keaveney, E. M.; Reimer, P. J.; Foy, R. H.

    2015-12-01

    Changing deposition chemistry, land use and climate induced impacts on hydrology will affect soil biogeochemistry and terrestrial C export and hence lake ecology with potential feedbacks for regional and global C cycling. Globally lakes bury and remineralise significant quantities of terrestrial C, and the associated flux of terrestrial C strongly influences their functioning. Primary production (autochthonous production) in lakes is based on dissolved inorganic C (DIC). DIC in alkaline lakes is partially derived from weathering of carbonaceous bedrock, a proportion of which is 14C-free. The low 14C activity yields an artificial age offset leading samples to appear hundreds to thousands of years older than their actual age. Dissolved organic carbon (DOC) and particulate organic carbon (POC) can contain terrestrial inputs. The terrestrial inputs can be labile or detrital; their age depends on their depth in catchment soil/peat stocks. We present a pilot study that uses the radiocarbon (∆14C) method to determine the source of carbon buried in the surface sediment of Lough Erne, a humic, alkaline lake in northwest Ireland. ∆14C, δ13C and δ15N values were measured from phytoplankton and other biota, dissolved inorganic, dissolved organic and particulate organic carbon. A novel radiocarbon method, Stepped Combustion1 was used to estimate the degree of the burial of terrestrial carbon in surface sediment. The ∆14C values of the low temperature fractions were comparable to algal ∆14C, while the high temperature fractions were 14C-depleted (older than bulk sediment). The ∆14C end-member model indicated that ~64% of carbon in surface sediment was derived from detrital terrestrial carbon. The use of ∆14C in conjunction with stepped combustion allows the quantification of the pathways of terrestrial carbon in the system, which has implications for regional and global carbon burial. 1McGeehin, J., Burr, G.S., Jull, A.J.T., Reines, D., Gosse, J., Davis, P.T., Muhs

  5. The in-vitro metabolism of [14C]pentobarbitone and [14C]phenobarbitone by hamster liver microsomes.

    PubMed

    Seago, A; Gorrod, J W

    1987-02-01

    The metabolism of [14C]pentobarbitone and [14C]phenobarbitone has been reinvestigated using an in-vitro hepatic microsomal system (Syrian hamsters, Aroclor 1254 induction). The incubation system was routinely supplemented with EDTA (1 mM) and a substrate concentration study revealed the metabolism of [14C]pentobarbitone to be concentration-dependent, with the greatest overall metabolism (greater than 50%) occurring at 0.054 mumol per 3.5 mL. With [14C]phenobarbitone as substrate, overall metabolism was extremely low (3%) and independent of substrate concentration. Addition of further cofactors to the incubation mixture at 20 min intervals over an extended period resulted in almost complete metabolism of [14C]pentobarbitone (100 min), 3'-hydroxypentobarbitone and 3'-oxopentobarbitone being identified as metabolites together with many minor, unidentified products. With [14C]phenobarbitone as the substrate, cofactor addition up to 120 min resulted in 8% overall metabolism; p-hydroxyphenobarbitone was identified as a product of metabolism; other minor products were unidentified. The metabolism studies failed to produce a metabolite having the properties of the N-hydroxylated product of either [14C]pentobarbitone or [14C]phenobarbitone within the detection limits available (0.02% of 0.5 mumol per incubate).

  6. 14C-age tracers in global ocean circulation models

    NASA Astrophysics Data System (ADS)

    Koeve, W.; Wagner, H.; Kähler, P.; Oschlies, A.

    2015-07-01

    The natural abundance of 14C in total CO2 dissolved in seawater (DIC) is a property applied to evaluate the water age structure and circulation in the ocean and in ocean models. In this study we use three different representations of the global ocean circulation augmented with a suite of idealised tracers to study the potential and limitations of using natural 14C to determine water age, which is the time elapsed since a body of water has been in contact with the atmosphere. We find that, globally, bulk 14C-age is dominated by two equally important components, one associated with ageing, i.e. the time component of circulation, and one associated with a "preformed 14C-age". The latter quantity exists because of the slow and incomplete atmosphere-ocean equilibration of 14C particularly in high latitudes where many water masses form. In the ocean's interior, preformed 14C-age behaves like a passive tracer. The relative contribution of the preformed component to bulk 14C-age varies regionally within a given model, but also between models. Regional variability in the Atlantic Ocean is associated with the mixing of waters with very different end members of preformed 14C-age. Here, variations in the preformed component over space and time mask the circulation component to an extent that its patterns are not detectable from bulk 14C-age. Between models, the variability of preformed 14C-age can also be considerable (factor of 2), related to the combination of physical model parameters, which influence circulation dynamics or gas exchange. The preformed component was found to be very sensitive to gas exchange and moderately sensitive to ice cover. In our model evaluation, the choice of the gas-exchange constant from within the currently accepted range of uncertainty had such a strong influence on preformed and bulk 14C-age that if model evaluation would be based on bulk 14C-age, it could easily impair the evaluation and tuning of a model's circulation on global and regional

  7. U-Pb Dating of CA/non-CA Treated Zircons Obtained by LA-ICP-MS and CA-TIMS Techniques: Impact for their Geological Interpretation

    NASA Astrophysics Data System (ADS)

    Von Quadt, A.; Gallhofer, D.; Guillong, M.; Peytcheva, I.

    2014-12-01

    Chemical Abrasion Isotope-Dilution Thermal Ionization Mass Spectrometry (CA-ID-TIMS) is known as a high precision technique for resolving lead loss and improving the interpretation of U-Pb zircon age data. We argue that combining CA with the widely applied Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) improves the precision and accuracy of zircon dates, while removing the substantial parts with lead loss, reducing data scatter, and providing meaningful geological interpretations. The samples are magmatic rocks chosen from different geological time periods (Paleozoic, Mesozoic and Cenozoic time). All zircon separates are analysed by LA-ICP-MS before and after CA, and all age data are compared with CA-ID-TIMS 206Pb/238U dates that are considered as the most accurately age. All CA-treated zircon crystals show up to 50% less data scatter compared to the non-CA treated zircon grains and thus a reduction of the calculated uncertainties is apparent. The obtained wt average LA-ICP-MS 206Pb/238U ages of the CA-treated zircon grains are up to 4-6% higher than those of the non-CA treated crystals, exceeding the analytical uncertainties of the LA-ICP-MS dating technique of 1-2%. The damaged crystal parts, caused by U-decay, with lead loss are removed, so that we can exclude younging from the possible geological scenarios. CA-LA-ICP-MS age data are in good agreement with the CA-ID-TIMS dates and suggest advantages of using CA-LA-ICP-MS in order to define accurate ages. The use of the CA technique for very young zircons (~0.2 Ma, Kos rhyolitic tuff, Greece) seems optional; as the obtained mean 206Pb/238U ages of non-CA and CA treated zircons coincide within the uncertainty. The negligible time to produce the lattice damage (based on alpha decay or spontaneous fission) makes lead loss less important for age dating and data interpretation of very young zircons (<1 Ma). Von Quadt, A. et al., 2014, JAAS, doi: 10.1039/c4ja00102h.

  8. TMEM14C is required for erythroid mitochondrial heme metabolism.

    PubMed

    Yien, Yvette Y; Robledo, Raymond F; Schultz, Iman J; Takahashi-Makise, Naoko; Gwynn, Babette; Bauer, Daniel E; Dass, Abhishek; Yi, Gloria; Li, Liangtao; Hildick-Smith, Gordon J; Cooney, Jeffrey D; Pierce, Eric L; Mohler, Kyla; Dailey, Tamara A; Miyata, Non; Kingsley, Paul D; Garone, Caterina; Hattangadi, Shilpa M; Huang, Hui; Chen, Wen; Keenan, Ellen M; Shah, Dhvanit I; Schlaeger, Thorsten M; DiMauro, Salvatore; Orkin, Stuart H; Cantor, Alan B; Palis, James; Koehler, Carla M; Lodish, Harvey F; Kaplan, Jerry; Ward, Diane M; Dailey, Harry A; Phillips, John D; Peters, Luanne L; Paw, Barry H

    2014-10-01

    The transport and intracellular trafficking of heme biosynthesis intermediates are crucial for hemoglobin production, which is a critical process in developing red cells. Here, we profiled gene expression in terminally differentiating murine fetal liver-derived erythroid cells to identify regulators of heme metabolism. We determined that TMEM14C, an inner mitochondrial membrane protein that is enriched in vertebrate hematopoietic tissues, is essential for erythropoiesis and heme synthesis in vivo and in cultured erythroid cells. In mice, TMEM14C deficiency resulted in porphyrin accumulation in the fetal liver, erythroid maturation arrest, and embryonic lethality due to profound anemia. Protoporphyrin IX synthesis in TMEM14C-deficient erythroid cells was blocked, leading to an accumulation of porphyrin precursors. The heme synthesis defect in TMEM14C-deficient cells was ameliorated with a protoporphyrin IX analog, indicating that TMEM14C primarily functions in the terminal steps of the heme synthesis pathway. Together, our data demonstrate that TMEM14C facilitates the import of protoporphyrinogen IX into the mitochondrial matrix for heme synthesis and subsequent hemoglobin production. Furthermore, the identification of TMEM14C as a protoporphyrinogen IX importer provides a genetic tool for further exploring erythropoiesis and congenital anemias.

  9. TMEM14C is required for erythroid mitochondrial heme metabolism

    PubMed Central

    Yien, Yvette Y.; Robledo, Raymond F.; Schultz, Iman J.; Takahashi-Makise, Naoko; Gwynn, Babette; Bauer, Daniel E.; Dass, Abhishek; Yi, Gloria; Li, Liangtao; Hildick-Smith, Gordon J.; Cooney, Jeffrey D.; Pierce, Eric L.; Mohler, Kyla; Dailey, Tamara A.; Miyata, Non; Kingsley, Paul D.; Garone, Caterina; Hattangadi, Shilpa M.; Huang, Hui; Chen, Wen; Keenan, Ellen M.; Shah, Dhvanit I.; Schlaeger, Thorsten M.; DiMauro, Salvatore; Orkin, Stuart H.; Cantor, Alan B.; Palis, James; Koehler, Carla M.; Lodish, Harvey F.; Kaplan, Jerry; Ward, Diane M.; Dailey, Harry A.; Phillips, John D.; Peters, Luanne L.; Paw, Barry H.

    2014-01-01

    The transport and intracellular trafficking of heme biosynthesis intermediates are crucial for hemoglobin production, which is a critical process in developing red cells. Here, we profiled gene expression in terminally differentiating murine fetal liver-derived erythroid cells to identify regulators of heme metabolism. We determined that TMEM14C, an inner mitochondrial membrane protein that is enriched in vertebrate hematopoietic tissues, is essential for erythropoiesis and heme synthesis in vivo and in cultured erythroid cells. In mice, TMEM14C deficiency resulted in porphyrin accumulation in the fetal liver, erythroid maturation arrest, and embryonic lethality due to profound anemia. Protoporphyrin IX synthesis in TMEM14C-deficient erythroid cells was blocked, leading to an accumulation of porphyrin precursors. The heme synthesis defect in TMEM14C-deficient cells was ameliorated with a protoporphyrin IX analog, indicating that TMEM14C primarily functions in the terminal steps of the heme synthesis pathway. Together, our data demonstrate that TMEM14C facilitates the import of protoporphyrinogen IX into the mitochondrial matrix for heme synthesis and subsequent hemoglobin production. Furthermore, the identification of TMEM14C as a protoporphyrinogen IX importer provides a genetic tool for further exploring erythropoiesis and congenital anemias. PMID:25157825

  10. Determination of 14C residue in eggs of laying hens administered orally with [14C] sulfaquinoxaline.

    PubMed

    Shaikh, B; Rummel, N; Smith, D

    2004-06-01

    Ten layer hens were dosed for 5 consecutive days with 6.2 mg kg(-1) [14C] sulfaquinoxaline (SQX). Eggs were collected from the hens during the 5-day dosing period and during a 10-day post-dose withdrawal period. Egg yolk and albumen were separated and assayed for total radioactive residues (TRR) using a combustion oxidizer and liquid scintillation counting techniques. Significant amounts of radioactivity were detected on the second day of dosing (greater than 24h after the initial dose) in both egg yolk and albumen. First eggs were collected about 8 h after dosing; the second-day eggs were collected during 8-h period after the second dose. Radioactive residues reached a maximum on the fifth day of dosing in albumen, whereas on the second day of withdrawal in egg yolk, the peak TRR levels in albumen were about threefold higher than in yolk. Thereafter, the TRR levels declined rapidly in albumen and were detectable up to withdrawal day 6, whereas the TRR levels in egg yolk declined more slowly and were detectable up to withdrawal day 10. High-performance liquid chromatography analysis indicated that the parent drug sulfaquinoxaline was the major component in both the egg albumen and yolk. Additionally, this work suggests that egg yolk is the appropriate matrix for monitoring SQX residues PMID:15204532

  11. Current perspectives of 14C-isotope measurement in biomedical accelerator mass spectrometry.

    PubMed

    Lappin, Graham; Garner, R Colin

    2004-01-01

    Accelerator mass spectrometry (AMS) is an extremely sensitive nuclear physics technique developed in the mid-70's for radiocarbon dating of historical artefacts. The technique centres round the use of a tandem Van de Graaff accelerator to generate the potential energy to permit separation of elemental isotopes at the single atom level. AMS was first used in the early 90's for the analysis of biological samples containing enriched 14C for toxicology and cancer research. Since that time biomedical AMS has been used in the study of (1) metabolism of xenobiotics in animals and humans (2) pathways of drug metabolism (3) biomarkers (4) metabolism of endogenous molecules including vitamins (5) DNA and protein binding studies and (6) clinical diagnosis. A new drug development concept which relies on the ultrasensitivity of AMS known as human microdosing (Phase 0) is being used to obtain early human metabolism information of candidate drugs arising out of discovery. These various aspects of AMS are reviewed in this article and a perspective on future applications of AMS provided.

  12. Fine structure in sup 14 C emission from sup 223 Ra and sup 224 Ra

    SciTech Connect

    Hourani, E.; Rosier, L.; Berrier-Ronsin, G.; Elayi, A.; Mueller, A.C.; Rappenecker, G.; Rotbard, G.; Renou, G.; Liebe, A.; Stab, L. ); Ravn, H.L. )

    1991-10-01

    The measurement of the energy spectrum of {sup 14}C nuclei emitted in the spontaneous radioactivity of {sup 223}Ra and {sup 224}Ra has been carried out, using thin and intense sources (480 MBq for {sup 223}Ra and 3550 MBq for {sup 224}Ra). The sources were obtained by implanting mass-separated beams into Al and vitreous C catchers. The measurement was performed with a superconducting solenoidal spectrometer. Our discovery, previously reported, of fine structure in the energy spectrum of {sup 14}C emission from {sup 223}Ra, which is analogous to the one known for {alpha} emission, is confirmed. Only 13% of the branching ratio in {sup 14}C decay leads to the ground state of the residual nucleus, while 81% to the first excited state. For {sup 14}C emission from {sup 224}Ra, a lower limit of 2 for the hindrance factor has been measured for the transition to the first excited state in the residual nucleus. Also, a precise identification in {ital Z} with an {ital E}{times}{Delta}{ital E} telescope has been performed for the radiation from the {sup 223}Ra source. Our measurements of fine structure in {sup 14}C emissions open this field to nuclear structure studies.

  13. Release of aged 14C-atrazine residues from soil facilitated by dry-wet cycles

    NASA Astrophysics Data System (ADS)

    Jablonowski, N. D.; Yu, K.; Koeppchen, S.; Burauel, P.

    2012-04-01

    Intermittent dry-wet cycles may have an important effect on soil structure and aged pesticide residues release (1). A laboratory study was conducted to assess the maximum potential of water extractable aged atrazine residues influenced by soil drying and wetting. The used soil was obtained from an outdoor lysimeter (gleyic cambisol; Corg: 1.45%), containing environmentally aged (22 years) 14C-atrazine residues. For the experiment, soil from 0-10 cm depth was used since most residual 14C activity was previously found in this layer (2,3). Triplicate soil samples with a residual water content of approx. 8% were either dried (45° C) prior water addition or directly mixed with distilled water (soil+water: 1+2, w:w). The samples were shaken (150 rmp, 60 min, at 21° C), centrifuged (approx. 2000 g), and the supernatants were filtered. Water-extracted residual 14C activity was detected via liquid scintillation counter. The total water-extracted 14C activity (the amount of residual 14C activity in a sample equals 100%) was significantly higher (p

  14. Progress report on a novel in situ14C extraction scheme at the University of Cologne

    NASA Astrophysics Data System (ADS)

    Fülöp, R.-H.; Wacker, L.; Dunai, T. J.

    2015-10-01

    We present initial results of in situ14C system blank and calibration sample measurements obtained using the in situ14C extraction scheme developed at the University of Cologne. The 14C extraction scheme specifically exploits the phase transformation of quartz to cristobalite in order to quantitatively extract the carbon as CO2 and follows a scheme that is different to that of existing extraction systems. Features are offline furnace extraction, single pass catalytic oxidation using mixed copper (I,II) oxide as catalyst, the use of UHV-compatible components and of vacuum annealed copper tubing. The design allows a relatively rapid sample throughput - two samples per day as opposed to the current 2 days per sample that can be done on other lines - and can accommodate samples ranging between 0.5 and 4 g of clean quartz. Following extraction and cleaning, the CO2 gas is measured using the gas ion source of the MICADAS AMS facility at ETH Zurich. The extraction system yields low systems blanks (10 +16/-10 × 103 atoms 14C, ±1 σ) and the initial results indicate that further improvements are achievable. Measurements of the CRONUS-A standard sample show a good reproducibility and results are consistent with published values. We also present the first in situ14C results for the CRONUS-R standard material.

  15. Cutaneous uptake of 14C-HD vapor by the hairless guinea pig.

    PubMed

    Logan, T P; Millard, C B; Shutz, M; Schulz, S M; Lee, R B; Bongiovanni, R

    1999-05-01

    The hairless guinea pig (HGP) is used by our laboratory to model the human cutaneous response to sulfur mustard (HD), bis(2-chloroethylsulfide), exposure. We determined the HD content in the skin of HGP after a 7-min exposure to vapors saturated with a mixture of HD and 14C-HD. Concentration/time (CT) values in the range of 2 micrograms/cm2/min were determined by counting skin 14C disintegrations per min (dpm) in animals euthanized immediately after exposure. These values are similar to human penetration rates obtained by other investigators. A rate curve monitoring the reduction in skin 14C dpm was developed for animals euthanized between 0 and 24 hr post- exposure. This curve showed the greatest change after 1 hr. The epidermal (62%) to dermal (38%) ratio of 14C at 24 hr was measured for two animals. We saw no site preference for HD penetration among the 8 sites used. The 14C content of template adhesive tape was determined to follow HD distribution. These results contribute to a better understanding of the cutaneous response to HD in the HGP model.

  16. Liquid scintillation counting of /sup 14/C for differentiation of synthetic ethanol from ethanol of fermentation

    SciTech Connect

    Martin, G.E.; Noakes, J.E.; Alfonso, F.C.; Figert, D.M.

    1981-09-01

    Samples containing ethanol are fractionated on a column so that the resultant ethanol content is > 93%. Determination of /sup 14/C by liquid scintillation counting on the ethanol fraction differentiates ethanol produced by fermentation from synthetic ethanol produced from fossil fuel sources. Twenty-seven samples were fractionated and analyzed for the /sup 14/C isotope. Six samples were synthetic ethanol derived from ethylene gas (direct and indirect process), and yielded a mean value for /sup 14/C isotope of 0.167 dpm/g carbon with a standard deviation (SD) of 0.066 dpm/g carbon (disintegrations per minute per gram of carbon). The remaining samples were ethanol derived from the fermentation of natural materials, such as corn, pear, sugar cane, grape, cherry, and blackberry, and yielded a mean value for /sup 14/C isotope of 16.11 dpm/g carbon with an SD of 1.27. The /sup 14/C values for specific mixtures of a synthetic and a natural ethanol compare favorably with the analytical values obtained by this procedure.

  17. At the end of the 14C time scale--the Middle to Upper Paleolithic record of western Eurasia.

    PubMed

    Jöris, Olaf; Street, Martin

    2008-11-01

    The dynamics of change underlying the demographic processes that led to the replacement of Neandertals by Anatomically Modern Humans (AMH) and the emergence of what are recognized as Upper Paleolithic technologies and behavior can only be understood with reference to the underlying chronological framework. This paper examines the European chronometric (mainly radiocarbon-based) record for the period between ca. 40 and 30 ka 14C BP and proposes a relatively rapid transition within some 2,500 years. This can be summarized in the following falsifiable hypotheses: (1) final Middle Paleolithic (FMP) "transitional" industries (Uluzzian, Chatelperronian, leaf-point industries) were made by Neandertals and date predominantly to between ca. 41 and 38 ka 14C BP, but not younger than 35/34 ka 14C BP; (2) initial (IUP) and early (EUP) Upper Paleolithic "transitional" industries (Bachokirian, Bohunician, Protoaurignacian, Kostenki 14) will date to between ca. 39/38 and 35 ka 14C BP and document the appearance of AMH in Europe; (3) the earliest Aurignacian (I) appears throughout Europe quasi simultaneously at ca. 35 ka 14C BP. The earliest appearance of figurative art is documented only for a later phase ca. 33.0/32.5-29.2 ka 14C BP. Taken together, the Middle to Upper Paleolithic transition appears to be a cumulative process involving the acquisition of different elements of "behavioral modernity" through several "stages of innovation."

  18. 14C-age tracers in global ocean circulation models

    NASA Astrophysics Data System (ADS)

    Koeve, W.; Wagner, H.; Kähler, P.; Oschlies, A.

    2014-10-01

    The natural abundance of 14C in total CO2 dissolved in seawater is a property applied to evaluate the water age structure and circulation in the ocean and in ocean models. In this study we use three different representations of the global ocean circulation augmented with a suite of idealised tracers to study the potential and limitations of using natural 14C to determine water age, the time elapsed since a body of water had contact with the atmosphere. We find that, globally, bulk 14C-age is dominated by two equally important components, one associated with aging, i.e. the time component of circulation and one associated with a "preformed 14C-age". This latter quantity exists because of the slow and incomplete atmosphere/ocean equilibration of 14C in particular in high latitudes where many water masses form. The relative contribution of the preformed component to bulk 14C-age varies regionally within a given model, but also between models. Regional variability, e.g. in the Atlantic Ocean is associated with the mixing of waters with very different end members of preformed 14C-age. In the Atlantic, variations in the preformed component over space and time mask the circulation component to an extent that its patterns are not detectable from bulk 14C-age alone. Between models the variability of age can also be considerable (factor of 2), related to the combinations of physical model parameters, which influence circulation dynamics, and gas exchange in the models. The preformed component was found to be very sensitive to gas exchange and moderately sensitive to ice cover. In our model evaluation exercise, the choice of the gas exchange constant from within the current range of uncertainty had such a strong influence on preformed and bulk 14C-age that if model evaluation would be based on bulk 14C-age it could easily impair the evaluation and tuning of a models circulation on global and regional scales. Based on the results of this study, we propose that considering

  19. The influence of Bacillus subtilis RB14-C on the development of Rhizoctonia solani and indigenous microorganisms in the soil.

    PubMed

    Szczech, Magdalena; Shoda, Makoto

    2005-05-01

    The effect of soil inoculation with an antagonistic strain Bacillus subtilis RB14-C on the development of Rhizoctonia solani and changes occurring in soil and rhizosphere microbial communities were studied. RB14-C was added to the soil as a water suspension of the cells or as a broth culture. Application of cell suspensions to non-planted soil reduced the number of culturable bacteria. The density of R. solani and the number of filamentous fungi were not significantly affected by RB14-C. A similar effect was observed in the rhizosphere of tomato plants growns in bacterized soil. Broth cultures of RB14-C suppressed R. solani 1 d after inoculation, but after 3 d there was no difference in the pathogen density between soil amended with broth culture and control soil. In microcosm studies, cell suspensions of RB14-C also did not inhibit growth of R. solani on filters buried in soil. However, an inhibitory effect was obtained when a broth culture of the bacterium was used. The effect of RB14-C on fungal biomass was also estimated by measurement of ergosterol concentration in soil. It was found that ergosterol was mostly derived from R. solani and that there were no significant differences in its content between untreated soil and soil treated with RB14-C. The results suggest that suppression of Rhizoctonia damping-off by B. subtilis RB14-C probably is not related to the reduction of the pathogen population in the soil.

  20. Distribution of 14C-TNT and derivatives in different biochemical compartments of Phaseolus vulgaris.

    PubMed

    Sens, C; Scheidemann, P; Klunk, A; Werner, D

    1998-01-01

    (14)C-TNT was used to quantify the uptake rate and metabolic turnover of TNT in Phaseolus vulgaris. Seventeen plants were analysed by a special cell fractionation method with polar and nonpolar solvents and enzymes. We obtained three cytoplasmic fractions and five cell wall derived fractions. The recovery rate was 72% as measured by liquid scintillation counting. (14)C partitioned almost in equal amounts with approximately 50% in the cytoplasm and in the cell wall. The majority of the TNT-metabolites are present in the cytoplasm as was shown by GC/ECD and thin layer chromatography. The(14)C in the cell wall is bound probably resulting in long-term immobilisation of these metabolites. We conclude that plants may also be a model for nitroaromatic turnover and immobilisation in soil components. PMID:19002633

  1. No evidence for a deglacial intermediate water Δ14C anomaly in the SW Atlantic

    NASA Astrophysics Data System (ADS)

    Sortor, R. N.; Lund, D. C.

    2010-12-01

    Reconstructions of Δ14C from the eastern tropical Pacific show that severe depletions in 14C occurred at intermediate depths during the last deglaciation (Marchitto et al. 2007; Stott et al. 2009). Marchitto et al. (2007) suggested that old radiocarbon from an isolated abyssal reservoir was injected via the Southern Ocean, and that this anomaly was then carried by Antarctic Intermediate Water (AAIW) to the tropical Pacific. However, a core from the southeastern Pacific Ocean near Chile, which is in the direct path of modern-day AAIW, does not exhibit the excursion and therefore casts doubts upon the AAIW mechanism (De Pol-Holz et al. 2010). Here we evaluate whether or not a deglacial 14C anomaly similar to that in the eastern tropical Pacific occurred at intermediate depths in the South Atlantic. We reconstructed Δ14C using planktonic and benthic foraminifera from core KNR159-5-36GGC on the Brazil Margin (27○31’S and 46○28’W, 1268 m depth). In the modern ocean, the hydrography near this core site is heavily influenced by AAIW (Oppo & Horowitz, 2000). Benthic Δ14C values were determined using raw benthic 14C ages and calendar-calibrated planktonic ages. The deglacial benthic Δ14C trend at this site is similar to the atmospheric Δ14C trend, and is consistent with U/Th-dated corals from intermediate depths on the Brazil Margin (Mangini et al. 2010). The amplitude and timing of Δ14C changes in the foraminiferal and coral records are especially congruous during the Mystery Interval. We find no evidence in the southwestern Atlantic of a ~300‰ decrease in intermediate water Δ14C beginning at 18 kyr BP. Changes in reservoir age of ~1000 years are required to create a Baja-like Δ14C anomaly off Brazil, an implausible increase for a subtropical gyre location. Furthermore, the resulting sedimentation rates would be up to ~145 cm/kyr during the deglaciation, an order of magnitude higher than the average sedimentation rate for 36GGC. When our results are

  2. The application of in situ 14C to Holocene terrestrial Antarctic ice-sheet reconstruction

    NASA Astrophysics Data System (ADS)

    Fogwill, Christopher; Turney, Christian; Hippe, Kristina; Rood, Dylan; Golledge, Nick; Wacker, Lukas; Wieler, Rainer

    2013-04-01

    Determining detailed Holocene ice-sheet behaviour in Antarctica is critical for understanding and predicting likely dynamic responses of ice sheets to future climate change. However, to date terrestrial studies using in situ cosmogenic isotopes have struggled to overcome inheritance issues in this cold-based ice setting. Here we present new terrestrial geological constraints that take advantage of recent technological developments in the extraction and measurement of in situ cosmogenic radiocarbon (14C)- a cosmogenic nuclide with a considerably shorter half-life than that of 10Be (10Be: 1.36x103 kyr; 14C: 5.73 kyr) - to assess the potential influence of prior exposure or recycling of glacial erratics and therefore improve reconstructions of past ice-sheet surface profile changes. Glacial erratics were sampled from steep exposed bedrock surfaces in the Ellsworth Mountains overlooking the Weddell Sea, serving as 'dipsticks' that allow us to reconstruct past surface elevation changes in the Rutford Ice Stream as it decayed through the Holocene. Our in situ 14C analysis reveals a complex relationship, reflecting inheritance and burial, in samples that record anomalously 'old' apparent 10Be exposure ages from previous exposure. Our results enable us to test and refine previous interpretations and thereby reduce chronological uncertainties in Holocene ice-sheet change in this sector of Antarctica, demonstrating the exiting potential of in situ 14C in ice-sheet reconstruction.

  3. 14C determination in different bio-based products

    NASA Astrophysics Data System (ADS)

    Santos Arévalo, Francisco-Javier; Gómez Martínez, Isabel; Agulló García, Lidia; Reina Maldonado, María-Teresa; García León, Manuel

    2015-10-01

    Radiocarbon determination can be used as a tool to investigate the presence of biological elements in different bio-based products, such as biodiesel blends. These products may also be produced from fossil materials obtaining the same final molecules, so that composition is chemically indistinguishable. The amount of radiocarbon in these products can reveal how much of these biological elements have been used, usually mixed with petrol derived components, free of 14C. Some of these products are liquid and thus the handling at the laboratory is not as straightforward as with solid samples. At Centro Nacional de Aceleradores (CNA) we have tested the viability of these samples using a graphitization system coupled to an elemental analyzer used for combustion of the samples, thus avoiding any vacuum process. Samples do not follow any chemical pre-treatment procedure and are directly graphitized. Specific equipment for liquid samples related to the elemental analyzer was tested. Measurement of samples was performed by low-energy AMS at the 1 MV HVEE facility at CNA, paying special attention to background limits and reproducibility during sample preparation.

  4. Radiocarbon dating of terrestrial carbonates

    USGS Publications Warehouse

    Pigati, Jeffrey S.; Rink, W. Jack; Thompson, Jeroen

    2014-01-01

    Terrestrial carbonates encompass a wide range of materials that potentially could be used for radiocarbon (14C) dating. Biogenic carbonates, including shells and tests of terrestrial and aquatic gastropods, bivalves, ostracodes, and foraminifera, are preserved in a variety of late Quaternary deposits and may be suitable for 14C dating. Primary calcareous deposits (marls, tufa, speleothems) and secondary carbonates (rhizoliths, fracture fill, soil carbonate) may also be targeted for dating when conditions are favorable. This chapter discusses issues that are commonly encountered in 14C dating of terrestrial carbonates, including isotopic disequilibrium and open-system behavior, as well as methods used to determine the reliability of ages derived from these materials. Recent methodological advancements that may improve the accuracy and precision of 14C ages of terrestrial carbonates are also highlighted.

  5. Using Dissolved Organic Carbon Isotopes for Groundwater Age Dating in Southern Nevada, USA

    NASA Astrophysics Data System (ADS)

    Thomas, James; Hershey, Ronald; Fereday, Wyatt

    2016-04-01

    Dissolved organic carbon (DOC) 14C offers a method to calculate groundwater ages that is more straightforward than dissolved inorganic carbon (DIC) 14C. To obtain corrected DIC 14C groundwater ages requires models that account for chemical and physical processes that affect both 13C and 14C. This is especially true in carbonate-rock aquifers where a fair amount of dissolution and precipitation of carbonate minerals can occur. A first important step in calculating 14C DOC groundwater ages is to determine the initial 14C DOC (A0) values of the groundwater recharge. For this study, recharge area groundwater samples of DOC 14C, collected from 14 different sites, were used to determine the recharge DOC 14C values. These values ranged from 96 to 120 percent modern carbon (pmc), with an average value of 106.2 pmc. These 14C A0 values support the use of a 100 pmc 14C A0 pre-bomb value to calculate DOC 14C groundwater ages for southern Nevada. Several conditions to successfully use DOC 14C to date groundwater need to be met. First, soluble organic carbon content of aquifers needs to be low, so that little DOC is added to the groundwater as it flows from recharge areas down gradient in an aquifer. For this study, volcanic and carbonate aquifer outcrop rocks showed that these rocks contained low soluble organic carbon. Second, it is important that the DOC does not change character down a flow path, which could indicate transformation of DOC along a flow path and/or addition of DOC to the groundwater. Although specific DOC compounds could not be identified for samples collected at four sites, all four groundwater sample spectra show the same general shape over the duration of the HPLC run indicating that the DOC compound composition of groundwater does not significantly change from up-gradient to down-gradient. Third, another factor that could greatly affect DOC 14C groundwater age calculations is matrix diffusion/adsorption of DOC 14C. Laboratory experiments showed that

  6. Characterization of 14C in Swedish light water reactors.

    PubMed

    Magnusson, Asa; Aronsson, Per-Olof; Lundgren, Klas; Stenström, Kristina

    2008-08-01

    This paper presents the results of a 4-y investigation of 14C in different waste streams of both boiling water reactors (BWRs) and pressurized water reactors (PWRs). Due to the potential impact of 14C on human health, minimizing waste and releases from the nuclear power industry is of considerable interest. The experimental data and conclusions may be implemented to select appropriate waste management strategies and practices at reactor units and disposal facilities. Organic and inorganic 14C in spent ion exchange resins, process water systems, ejector off-gas and replaced steam generator tubes were analyzed using a recently developed extraction method. Separate analysis of the chemical species is of importance in order to model and predict the fate of 14C within process systems as well as in dose calculations for disposal facilities. By combining the results of this investigation with newly calculated production rates, mass balance assessments were made of the 14C originating from production in the coolant. Of the 14C formed in the coolant of BWRs, 0.6-0.8% was found to be accumulated in the ion exchange resins (core-specific production rate in the coolant of a 2,500 MWth BWR calculated to be 580 GBq GW(e)(-1) y(-1)). The corresponding value for PWRs was 6-10% (production rate in a 2,775 MWth PWR calculated to be 350 GBq GW(e)(-1) y(-1)). The 14C released with liquid discharges was found to be insignificant, constituting less than 0.5% of the production in the coolant. The stack releases, routinely measured at the power plants, were found to correspond to 60-155% of the calculated coolant production, with large variations between the BWR units.

  7. Characterization of 14C in Swedish light water reactors.

    PubMed

    Magnusson, Asa; Aronsson, Per-Olof; Lundgren, Klas; Stenström, Kristina

    2008-08-01

    This paper presents the results of a 4-y investigation of 14C in different waste streams of both boiling water reactors (BWRs) and pressurized water reactors (PWRs). Due to the potential impact of 14C on human health, minimizing waste and releases from the nuclear power industry is of considerable interest. The experimental data and conclusions may be implemented to select appropriate waste management strategies and practices at reactor units and disposal facilities. Organic and inorganic 14C in spent ion exchange resins, process water systems, ejector off-gas and replaced steam generator tubes were analyzed using a recently developed extraction method. Separate analysis of the chemical species is of importance in order to model and predict the fate of 14C within process systems as well as in dose calculations for disposal facilities. By combining the results of this investigation with newly calculated production rates, mass balance assessments were made of the 14C originating from production in the coolant. Of the 14C formed in the coolant of BWRs, 0.6-0.8% was found to be accumulated in the ion exchange resins (core-specific production rate in the coolant of a 2,500 MWth BWR calculated to be 580 GBq GW(e)(-1) y(-1)). The corresponding value for PWRs was 6-10% (production rate in a 2,775 MWth PWR calculated to be 350 GBq GW(e)(-1) y(-1)). The 14C released with liquid discharges was found to be insignificant, constituting less than 0.5% of the production in the coolant. The stack releases, routinely measured at the power plants, were found to correspond to 60-155% of the calculated coolant production, with large variations between the BWR units. PMID:18617793

  8. {sup 14}C depth profiles in Apollo 15 and 17 cores and lunar rock 68815

    SciTech Connect

    Jull, A.J.T.; Cloudt, S.; Donahue, D.J.; Sisterson, J.M.; Reedy, R.C.; Masarik, J.

    1998-09-01

    Accelerator mass spectrometry (AMS) was used to measure the activity vs. depth profiles of {sup 14}C produced by both solar cosmic rays (SCR) and galactic cosmic rays (GCR) in Apollo 15 lunar cores 15001-6 and 15008, Apollo 17 core 76001, and lunar rock 68815. Calculated GCR production rates are in good agreement with {sup 14}C measurements at depths below {approximately}10 cm. Carbon-14 produced by solar protons was observed in the top few cm of the Apollo 15 cores and lunar rock 68815, with near-surface values as high as 66 dpm/kg in 68815. Only low levels of SCR-produced {sup 14}C were observed in the Apollo 17 core 76001. New cross sections for production of {sup 14}C by proton spallation on O, Si, Al, Mg, Fe, and Ni were measured using AMS. These cross sections are essential for the analysis of the measured {sup 14}C depth profiles. The best fit to the activity-depth profiles for solar-proton-produced {sup 14}C measured in the tops of both the Apollo 15 cores and 68815 was obtained for an exponential rigidity spectral shape R{sub 0} of 110--115 MV and a 4 {pi} flux (J{sub 10}, Ep > 10 MeV) of 103--108 protons/cm{sup 2}/s. These values of R{sub 0} are higher, indicating a harder rigidity, and the solar-proton fluxes are higher than those determined from {sup 10}Be, {sup 26}Al, and {sup 53}Mn measurements.

  9. Measuring the 14C content in liquid scintillators

    NASA Astrophysics Data System (ADS)

    Enqvist, T.; Barabanov, I. R.; Bezrukov, L. B.; Gangapshev, A. M.; Gavrilyuk, Y. M.; Grishina, V. Yu; Gurentsov, V. I.; Hissa, J.; Joutsenvaara, J.; Kazalov, V. V.; Krokhaleva, S.; Kutuniva, J.; Kuusiniemi, P.; Kuzminov, V. V.; Kurlovich, A. S.; Loo, K.; Lubsandorzhiev, B. K.; Lubsandorzhiev, S.; Morgalyuk, V. P.; Novikova, G. Y.; Pshukov, A. M.; Sinev, V. V.; Słupecki, M.; Trzaska, W. H.; Umerov, Sh I.; Veresnikova, A. V.; Virkajärvi, A.; Yanovich, Y. A.; Zavarzina, V. P.

    2016-05-01

    We are going to perform a series of measurements where the 14C/12 C ratio will be measured from several liquid scintillator samples with a dedicated setup. The setup is designed with the aim of measuring ratios smaller than 10-18. Measurements take place in two underground laboratories: in the Baksan Neutrino Observatory, Russia and in the Pyhäsalmi mine, Finland. In Baksan the measurements started in 2015 and in Pyhäsalmi they start in the beginning of 2015. In order to fully understand the operation of the setup and its background contributions a development of simulation packages has also been started. Low-energy neutrino detection with a liquid scintillator requires that the intrinsic 14C content in the liquid is extremely low. In the Borexino CTF detector at Gran Sasso, Italy the 14C/12C ratio of 2 × 10-18 has been achieved being the lowest 14C concentration ever measured. In principle, the older the oil or gas source that the liquid scintillator is derived of and the deeper it situates, the smaller the 14C/12C ratio is supposed to be. This, however, is not generally the case, and the ratio is probably determined by the U and Th content of the local environment.

  10. AMS radiocarbon dating of mortar: The case study of the medieval UNESCO site of Modena

    NASA Astrophysics Data System (ADS)

    Carmine, Lubritto; Caroselli, Marta; Lugli, Stefano; Marzaioli, Fabio; Nonni, Sara; Marchetti Dori, S.; Terrasi, Filippo

    2015-10-01

    The carbon dioxide contributing to binder formation during the set of a lime mortar reflects the atmospheric 14C content at the time of construction of a building. For this reason, the 14C dating of mortars is used with increasing frequencies in archaeological and architectural research. Mortars, however, may also contain carbonaceous contaminants potentially affecting radiocarbon dating. The Centre for Isotopic Research on Cultural and Environmental heritage (CIRCE) of the Second University of Naples (SUN) has recently obtained some promising results in mortar radiocarbon dating thanks to the development of a procedure (i.e. CryoSoniC/Cryo2SoniC) aiming to eliminate exogenous C contamination that may occur in a mortar. The construction history of the UNESCO World Heritage Site of Modena (Italy) is still controversial and represents a challenging case study for the application of absolute dating methodologies for different reasons. From the point of view of 14C dating, for example, given the high percentage of carbonate aggregates composing these samples, Modena mortars represent an experimental test particularly indicative of exogenous carbon sources suppression ensuring methodology accuracy. In this paper several AMS Radiocarbon dates were carried out on lime lumps with the aim to: (i) verify procedure accuracy by a comparison of the results obtainable from lime lumps dated after different treatments (i.e. bulk lime lumps vs. CryoSoniC purified lime lumps); (ii) compare different building phases absolute chronology for the medieval UNESCO site of Modena, with that assumed by historical sources in order to assess preliminary the 14C dating feasibility for of the site. Historical temporal constraints and mortar clustering, based on petrography, have been applied to define a temporal framework of the analyzed structure. Moreover, a detailed petrographic characterization of mortars was used both as a preliminary tool for the choice of samples and to infer about the

  11. Low-level 14C measurements and Accelerator Mass Spectrometry

    SciTech Connect

    Litherland, A.E.; Beukens, R.P.; Zhao, X.-L.; Kieser, W.E.; Gove, H.E.

    2005-09-08

    Accelerator Mass Spectrometry (AMS) and isotope enrichment were used in 1991 to estimate that the 14C content of methane in natural gas was {<=}1.6x10-18 of the total carbon. The low content of 14C in underground hydrocarbons was verified later in the remarkable results from the Borexino test scintillation counter for solar neutrino studies. Since then studies of the 14C background problem have demonstrated that much of the background originally observed in the AMS measurements can, in principle, be eliminated. However, many difficulties and other backgrounds are to be faced as the limit for AMS is pushed still further towards possibly a ratio of < 10-21. These will be discussed.

  12. The direct absorption method of 14C assay—historical perspective and future potential

    NASA Astrophysics Data System (ADS)

    Vita-Finzi, Claudio; Leaney, Fred

    2006-05-01

    Radiocarbon dating by liquid scintillation counting of 14CO 2 absorbed into an alkaline liquid was first developed for groundwater research. In the 1980s it was applied to molluscs, barnacles, corals and other carbonates, and yielded dependable results within a few hours, with standard errors of ˜10% for ages <14 000 yr, at about 1/200 the price of commercial 14C dates. Although its cost has risen fivefold, the first-order approach remains useful in coastal neotectonics, where numerous low-precision determinations are often more useful than a few high-precision dates. Direct absorption (DA) 14C dating has now been improved and extended to include wood and charcoal samples, and provides ages in a variety of environments with standard errors similar to those reported by conventional radiometric laboratories and for ages spanning the last 30 000 years. The unit cost for a 'state of the art' DA determination is close to 50% of that by benzene synthesis, but the method is favoured in many hydrological and archaeological applications because it is robust and rapid.

  13. Characterization of 14C in Neutron-Irradiated Graphite

    NASA Astrophysics Data System (ADS)

    LaBrier, Daniel Patrick

    A long-term radiological concern regarding irradiated graphite waste is the presence of the radionuclide 14C. Recent studies suggest that a significant portion of 14C contamination present in reactor-irradiated graphite is concentrated on the surface and within near-surface layers. Methods for treating irradiated graphite waste (e.g. pyrolysis, oxidation) in order to remove 14C-bearing species from the bulk graphite are being investigated to lend guidance in optimizing long-term disposal strategies. Characterization studies were performed in order to determine the chemical nature of 14C on irradiated graphite surfaces. Samples of the nuclear-grade graphite NBG-25 were irradiated in a neutron flux of 10 14 n/cm2-s for 360 days at the Advanced Test Reactor (at the Idaho National Laboratory). Surface-sensitive analysis techniques (XPS, ToF-SIMS, SEM/EDS and Raman) were employed to determine the type, location and quantity of specific chemical species and bonds that were present on the surfaces of irradiated graphite samples. Several 14C precursor species were identified on the surfaces of irradiated NBG-25; the quantities of these species decrease at sub-surface depths, which, is consistent with the observation of high concentrations of 14C on the surfaces of graphite reactor components. The elevated presence of surface oxide complexes on irradiated NBG-25 surfaces was attributed directly to neutron irradiation. Pathways for the release of 14C were identified for irradiated NBG-25: carboxyls and lactones (14CO 2), and carbonyls, ethers and quinones (14CO). Increased amounts of C-O and C=O bonding were observed on irradiated NBG-25 surfaces (when compared to unirradiated samples) in the form of interlattice (e.g. ether) and dangling (e.g. carboxyl or quinone) bonds; the quantities of these bond types also decrease at sub-surface depths. The results of this study are consistent with thermal treatment studies that indicate that the primary candidates for the release of

  14. A simplified In Situ cosmogenic 14C extraction system

    USGS Publications Warehouse

    Pigati, J.S.; Lifton, N.A.; Timothy, Jull A.J.; Quade, Jay

    2010-01-01

    We describe the design, construction, and testing of a new, simplified in situ radiocarbon extraction system at the University of Arizona. Blank levels for the new system are low ((234 ?? 11) ?? 103 atoms (1 ??; n = 7)) and stable. The precision of a given measurement depends on the concentration of 14C, but is typically <5% for concentrations of 100 ?? 103 atoms g-1 or more. The new system is relatively small and easy to construct, costs significantly less than the original in situ 14C extraction system at Arizona, and lends itself to future automation. ?? 2010 by the Arizona Board of Regents on behalf of the University of Arizona.

  15. Direct measurement of stellar neutron capture rates of 14C and comparison with the Coulomb breakup method

    NASA Astrophysics Data System (ADS)

    Reifarth, Rene; Heil, M.; Plag, R.; Besserer, U.; Couture, A.; Dababneh, S.; Dörr, L.; Forssén, C.; Görres, J.; Haight, R. C.; Mengoni, A.; O'Brien, S.; Patronis, N.; Rundberg, R. S.; Uberseder, E.; Wiescher, M.; Wilhelmy, J. B.

    The neutron capture cross section of 14 C has been shown to be important for several neutron driven nucleosynthesis scenarios. Due to the high neutron abundance it is expected that the 14 C(n,γ) reaction competes strongly with other neutron-induced reactions on 14 C. The 14 C(n,γ) reaction is also important to validate (n,γ) cross sections obtained via the inverse reaction by the Coulomb breakup method. In principle, 14 C belongs to the few cases where this correspondence can be validated in a convincingly clean way. So far, the example of 14 C is obscured, however, by discrepancies between several experiments and theory. In this contribution we report on a re- analysis of the direct measurements of the 14 C(n,γ) reaction presented on the last NIC conference (Vancouver, 2004). The neutron energies used during the experiment ranged from 30 to 800 keV. The earlier presented disagreement between the direct measurements and the Coulomb breakup method has been resolved.

  16. Comment on "Radiocarbon Calibration Curve Spanning 0 to 50,000 Years B.P. Based on Paired 230Th/234U/238U and 14C Dates on Pristine Corals" by R.G. Fairbanks, R. A. Mortlock, T.-C. Chiu, L. Cao, A. Kaplan, T. P. Guilderson, T. W. Fairbanks, A. L. Bloom, P

    SciTech Connect

    Reimer, P J; Baillie, M L; Bard, E; Beck, J W; Blackwell, P G; Buck, C E; Burr, G S; Edwards, R L; Friedrich, M; Guilderson, T P; Hogg, A G; Hughen, K A; Kromer, B; McCormac, G; Manning, S; Reimer, R W; Southon, J R; Stuiver, M; der Plicht, J v; Weyhenmeyer, C E

    2005-10-02

    Radiocarbon calibration curves are essential for converting radiocarbon dated chronologies to the calendar timescale. Prior to the 1980's numerous differently derived calibration curves based on radiocarbon ages of known age material were in use, resulting in ''apples and oranges'' comparisons between various records (Klein et al., 1982), further complicated by until then unappreciated inter-laboratory variations (International Study Group, 1982). The solution was to produce an internationally-agreed calibration curve based on carefully screened data with updates at 4-6 year intervals (Klein et al., 1982; Stuiver and Reimer, 1986; Stuiver and Reimer, 1993; Stuiver et al., 1998). The IntCal working group has continued this tradition with the active participation of researchers who produced the records that were considered for incorporation into the current, internationally-ratified calibration curves, IntCal04, SHCal04, and Marine04, for Northern Hemisphere terrestrial, Southern Hemisphere terrestrial, and marine samples, respectively (Reimer et al., 2004; Hughen et al., 2004; McCormac et al., 2004). Fairbanks et al. (2005), accompanied by a more technical paper, Chiu et al. (2005), and an introductory comment, Adkins (2005), recently published a ''calibration curve spanning 0-50,000 years''. Fairbanks et al. (2005) and Chiu et al. (2005) have made a significant contribution to the database on which the IntCal04 and Marine04 calibration curves are based. These authors have now taken the further step to derive their own radiocarbon calibration extending to 50,000 cal BP, which they claim is superior to that generated by the IntCal working group. In their papers, these authors are strongly critical of the IntCal calibration efforts for what they claim to be inadequate screening and sample pretreatment methods. While these criticisms may ultimately be helpful in identifying a better set of protocols, we feel that there are also several erroneous and misleading

  17. Extracting in situ cosmogenic 14C from olivine: significance for the CRONUS-Earth project

    NASA Astrophysics Data System (ADS)

    Pigati, J. S.; Lifton, N. A.; Quade, J.; Jull, A. T.

    2005-12-01

    One of the main goals of the Cosmic-Ray-prOduced NUclide Systematics on Earth (CRONUS-Earth) project is to compare production rates of in situ cosmogenic nuclides (CNs) at several well-dated locations in various rock types. Quartz is the most commonly used target mineral for several CNs (e.g., 10Be, 26Al, 21Ne, 14C), but is generally absent in mafic volcanic terrains, where flows of different ages can constrain temporal variations in CN production at a given location. Because of its short half-life (5.73 ka), in situ cosmogenic 14C (in situ 14C) can be particularly useful for elucidating temporal variations in CN production over much shorter time scales than other CNs. While CNs such as 36Cl and 21Ne can be measured in both mafic and felsic rocks, clearly it would be advantageous to measure in situ 14C in mafic rocks as well. As such, we have worked to develop reliable protocols to extract in situ 14C from olivine. We conducted numerous stepped combustion experiments testing the efficacy of various chemical pretreatments. We were able to extract a stable and reproducible in situ 14C component from olivine using a LiBO2 flux, following pretreatment with dilute HNO3. However, measured concentrations in olivine (normalized to SiO2 composition) from two known-age basalt flows, the Tabernacle Hill flow (17.3+/-0.4 ka in age) in central Utah and the McCarty's flow (3.0+/-0.2 ka in age) in western New Mexico, were 3 to 5 times lower than predicted in situ 14C concentrations based on measurements in quartz. This discrepancy appears to arise from (1) a synthetic spinel-like mineral formed during our extraction process by the chemical interaction of the Al2O3 sample boat and olivine dissolved within the LiBO2 flux, and (2) undissolved pyroxene phenocrysts (difficult to separate in quantity from olivines). Although we do not fully understand how the formation of the synthetic mineral may affect carbon atoms liberated from olivine, the concentration of in situ 14C atoms that

  18. Accelerator mass spectrometry measurements of the 13C (n ,γ )14C and 14N(n ,p )14C cross sections

    NASA Astrophysics Data System (ADS)

    Wallner, A.; Bichler, M.; Buczak, K.; Dillmann, I.; Käppeler, F.; Karakas, A.; Lederer, C.; Lugaro, M.; Mair, K.; Mengoni, A.; Schätzel, G.; Steier, P.; Trautvetter, H. P.

    2016-04-01

    The technique of accelerator mass spectrometry (AMS), offering a complementary tool for sensitive studies of key reactions in nuclear astrophysics, was applied for measurements of the 13C (n ,γ )14C and the 14N(n ,p )14C cross sections, which act as a neutron poison in s -process nucleosynthesis. Solid samples were irradiated at Karlsruhe Institute of Technology with neutrons closely resembling a Maxwell-Boltzmann distribution for k T =25 keV, and also at higher energies between En=123 and 182 keV. After neutron irradiation the produced amount of 14C in the samples was measured by AMS at the Vienna Environmental Research Accelerator (VERA) facility. For both reactions the present results provide important improvements compared to previous experimental data, which were strongly discordant in the astrophysically relevant energy range and missing for the comparably strong resonances above 100 keV. For 13C (n ,γ ) we find a four times smaller cross section around k T =25 keV than a previous measurement. For 14N(n ,p ), the present data suggest two times lower cross sections between 100 and 200 keV than had been obtained in previous experiments and data evaluations. The effect of the new stellar cross sections on the s process in low-mass asymptotic giant branch stars was studied for stellar models of 2 M⊙ initial mass, and solar and 1 /10th solar metallicity.

  19. Enzymatic aryl-O-methyl-/sup 14/C labeling of model lignin monomers

    SciTech Connect

    Frazer, A.C.; Bossert, I.; Young, L.Y.

    1986-01-01

    Aryl-O-methyl ethers are abundant in aerobic and anaerobic environments. In particular, lignin is composed of units of this type. Lignin monomers specifically radiolabeled in methoxy, side chain, and ring carbons have been synthesized by chemical procedures and are important in studies of lignin synthesis and degradation, humus formation, and microbial O-demethylation. In this paper attention is drawn to an enzymatic procedure for preparing O-methyl-/sup 14/C-labeled aromatic lignin monomers which has not previously been exploited in microbial ecology and physiology studies and which has several advantages compared with chemical synthesis procedures. O-(methyl-/sup 14/C)vanillic and O-(methyl-/sup 14/C)ferulic acids were prepared with S-(methyl-/sup 14/C)adenosyl-L-methionine as the methyl donor, using commercially obtained porcine liver catechol-O-methyltransferase (EC 2.1.1.6). The specific activity of the methylated products was the same as that of the methyl donor, a maximum of about 58 ..mu..Ci/..mu..mol, and the yields were 42% (vanillate) and 35% (ferulate). Thus lignin monomers are readily prepared as O-methylated products of the catechol-O-methyltransferase reaction and, with this enzyme method of preparation, would be more widely available than labeled compounds which require chemical synthesis.

  20. Convenient preparative synthesis of ( sup 14 C)trehalose from ( sup 14 C)glucose by intact Escherichia coli cells

    SciTech Connect

    Brand, B.; Boos, W. )

    1989-09-01

    At high osmolarity, Escherichia coli synthesizes trehalose intracellularly, irrespective of the nature of the carbon source. Synthesis proceeds via the transfer of UDP-glucose to glucose 6-phosphate, yielding trehalose 6-phosphate, followed by its dephosphorylation to trehalose. This reaction was exploited to preparatively synthesize ({sup 14}C)trehalose from exogenous ({sup 14}C)glucose by using intact bacteria of a mutant (DF214) that could not metabolize glucose. The total yield of radiochemically pure trehalose from glucose was routinely more than 50%.

  1. Applications of AMS {sup 14}C on Climate and Archaeology

    SciTech Connect

    Gomes, P. R. S.

    2007-10-26

    We describe the Accelerator Mass Spectrometry (AMS) technique and two distinct applications of its use with {sup 14}C to study environmental problems in Brazil, such as forest fires and climate changes in the Amazon region and archaeological studies on the early settlements in the Southeast Brazilian coast.

  2. Excretion of radioactivity following the intraperitoneal administration of /sup 14/C-DDT, /sup 14/C-DDD, /sup 14/C-DDE and /sup 14/C-DDMU to the rat and Japanese Quail

    SciTech Connect

    Fawcett, S.C.; Bunyan, P.J.; Huson, L.W.; King, L.J.; Stanley, P.I.

    1981-09-01

    A study in progress to examine the metabolic fate of DDT in birds and mammals is discussed. The first phase of the study, which is reported in this article, has been to establish the rate of excretion of ratioactivity following the intraperitoneal administrations of /sup 14/C-DDT, /sup 14/C-DDE, /sup 14/C-DDD, and /sup 14/C-DDMU to male rats and male Japanese quail. The mean values from the three animals in each experimental group for the amount of radioactivity excreted daily are given, and it was found that the rats excreted the radioactivity administered as DDT, DDD, and DDE substantially faster than did the quail. DDMU was excreted relatively rapidly and at similar rates. This finding suggests that apparent differences in the rates of excretion of DDT by birds and mammals probably arise from differences in the conversion of DDT to DDD or DDE or in the degradation of these metabolites to DDMU. The Japanese quail differ from the rats in excreting substantial amounts of unchanged DDT, DDE, and DDD, which probably reflects the inability of the Japanese quail to readily metabolise these compounds.

  3. Extraction of in situ cosmogenic 14C from olivine

    USGS Publications Warehouse

    Pigati, J.S.; Lifton, N.A.; Timothy, Jull A.J.; Quade, Jay

    2010-01-01

    Chemical pretreatment and extraction techniques have been developed previously to extract in situ cosmogenic radiocarbon (in situ 14C) from quartz and carbonate. These minerals can be found in most environments on Earth, but are usually absent from mafic terrains. To fill this gap, we conducted numerous experiments aimed at extracting in situ 14C from olivine ((Fe,Mg)2SiO4). We were able to extract a stable and reproducible in situ 14C component from olivine using stepped heating and a lithium metaborate (LiBO2) flux, following treatment with dilute HNO3 over a variety of experimental conditions. However, measured concentrations for samples from the Tabernacle Hill basalt flow (17.3 ?? 0.3 ka4) in central Utah and the McCarty's basalt flow (3.0 ?? 0.2 ka) in western New Mexico were significantly lower than expected based on exposure of olivine in our samples to cosmic rays at each site. The source of the discrepancy is not clear. We speculate that in situ 14C atoms may not have been released from Mg-rich crystal lattices (the olivine composition at both sites was ~Fo65Fa35). Alternatively, a portion of the 14C atoms released from the olivine grains may have become trapped in synthetic spinel-like minerals that were created in the olivine-flux mixture during the extraction process, or were simply retained in the mixture itself. Regardless, the magnitude of the discrepancy appears to be inversely proportional to the Fe/(Fe+Mg) ratio of the olivine separates. If we apply a simple correction factor based on the chemical composition of the separates, then corrected in situ 14C concentrations are similar to theoretical values at both sites. At this time, we do not know if this agreement is fortuitous or real. Future research should include measurement of in situ 14C concentrations in olivine from known-age basalt flows with different chemical compositions (i.e. more Fe-rich) to determine if this correction is robust for all olivine-bearing rocks. ?? 2010 by the Arizona

  4. Reconstructing Ocean Circulation using Coral (triangle)14C Time Series

    SciTech Connect

    Kashgarian, M; Guilderson, T P

    2001-02-23

    We utilize monthly {sup 14}C data derived from coral archives in conjunction with ocean circulation models to address two questions: (1) how does the shallow circulation of the tropical Pacific vary on seasonal to decadal time scales and (2) which dynamic processes determine the mean vertical structure of the equatorial Pacific thermocline. Our results directly impact the understanding of global climate events such as the El Nino-Southern Oscillation (ENSO). To study changes in ocean circulation and water mass distribution involved in the genesis and evolution of ENSO and decadal climate variability, it is necessary to have records of climate variables several decades in length. Continuous instrumental records are limited because technology for continuous monitoring of ocean currents (e.g. satellites and moored arrays) has only recently been available, and ships of opportunity archives such as COADS contain large spatial and temporal biases. In addition, temperature and salinity in surface waters are not conservative and thus can not be independently relied upon to trace water masses, reducing the utility of historical observations. Radiocarbon in sea water is a quasi-conservative water mass tracer and is incorporated into coral skeletal material, thus coral {sup 14}C records can be used to reconstruct changes in shallow circulation that would be difficult to characterize using instrumental data. High resolution {Delta}{sup 14}C timeseries such as ours, provide a powerful constraint on the rate of surface ocean mixing and hold great promise to augment one time oceanographic surveys. {Delta}{sup 14}C timeseries such as these, not only provide fundamental information about the shallow circulation of the Pacific, but can also be directly used as a benchmark for the next generation of high resolution ocean models used in prognosticating climate. The measurement of {Delta}{sup 14}C in biological archives such as tree rings and coral growth bands is a direct record of

  5. Tips and traps in the 14C Bio-AMS preparation laboratory (WSam 7)

    SciTech Connect

    Buchholz, B A; Haack, K W; Stewart, P H; Vogel, J S

    1999-10-12

    Maintaining a contamination free sample preparation lab for biological 14 C AMS requires the same or more diligence as a radiocarbon dating prep lab. Isotope ratios of materials routinely range over 4-8 orders of magnitude in a single experiment, dosing solutions contain thousands of DPM and gels used to separate proteins possess 14 C ratios of 1pMC. Radiocarbon contamination is a legacy of earlier tracer work in most biological laboratories, even if they were never hot labs. Removable surface contamination can be found and monitored using swipes. Contamination can be found on any surface routinely touched: door knobs, light switches, drawer handles, water faucets. In general, all surfaces routinely touched need to be covered with paper, foil, or plastic that can be changed frequently. Shared air supplies can also present problems by distributing hot aerosols throughout a building. Aerosols can be monitored for 14 C content using graphitized coal or fullerene soot mixed with metal powder as an absorber. The monitors can be set out in work spaces for 1-2 weeks and measured by AMS with regular samples. Frequent air changes help minimize aerosol contamination in many cases. Cross contamination of samples can be minimized by using disposable plastic or glassware in the prep lab, isolating samples from the air when possible and using positive displacement pipetters.

  6. Movement and Metabolism of Kinetin-14C and of Adenine-14C in Coleus Petiole Segments of Increasing Age 1

    PubMed Central

    Veen, Henk; Jacobs, William P.

    1969-01-01

    To see if polar movement was typical of growth-regulators other than auxins, the movement of adenine-8-14C and of kinetin-8-14C was studied in segments cut from petioles of increasing age. No polarity was found. In time-course experiments lasting 24 hr, kinetin showed a progressive increase of radioactivity in receiver blocks, while adenine showed a maximum at 8 hr with a decline thereafter. More kinetin moved through older segments than through younger ones. There was no difference in net loss as far as the position of the donor block is concerned. However, the loss of radioactivity from adenine donor blocks was much higher than the loss of radioactivity from kinetin donor blocks. The radioactivity in receiver blocks after 24 hr treatment with kinetin-14C was still with kinetin, judging by location on chromatograms. By the same criterion, adenine and a smaller amount of some other compound were in receiver blocks after a 6 hr transport with adenine-14C in the donors. By contrast, more zones of radioactivity were extracted from petiole segments to which kinetin or adenine had been added. For both purine derivatives the original compound represented no more than 20% of the total radioactivity extracted from the tissue after a transport period of 24 hr. PMID:16657203

  7. Degradation of /sup 14/C-labeled lignins and /sup 14/C-labeled aromatic acids by fusarium solani

    SciTech Connect

    Norris, D.M.

    1980-08-01

    Abilities of isolate AF-W1 of Fusarium solani to degrade the side chain and the ring structure of synthetic dehydrogenative polymerizates, aromatic acids, or lignin in sound wood were investigated under several conditions of growth substrate or basal medium and pH. Significant transformations of lignins occurred in 50 days in both unextracted and extracted sound wood substrances with 3% malt as the growth substrate and the pH buffered initially at 4.0 with 2,2-dimethylsuccinate. Degradation of lignin in such woods also occurred under unbuffered pH conditions when a basal medium of either 3% malt or powdered cellulose in deionized water was present. Decomposition of the lignin in these woods did not occur in cultures where D-glucose was present as a growth substrate. F. solani significantly transformed, as measured as evolved /sup 14/CO/sub 2/, both synthetic side chain (beta, gamma)-/sup 14/C- and U-ring-/sup 14/C-labeled lignins in 30 days under liquid culture conditions of only distilled deionized water and no pH adjustment. Degradation of dehydrogenative polymerizates by F. solani was reduced drastically when D2 was the liquid medium. AF-W1 also cleaved the alpha-/sup 14/C from p- hydroxybenzoic acid and evolved /sup 14/CO/sub 2/ from the substrace, (3-/sup 14/C) cinnamic acid. Thus, the fungus cleaved side chain carbon from substrate that originally lacked hydroxyl substitution on the aromatic nucleus. Surprisingly, small amounts of /sup 14/C cleaved from aromatic acids by F. solani were incorporated into cell mass. Initial buffering of the culture medium to pH 4.0 or 5.0 with 0.1 M2,2-dimethylsuccinate significantly increased F. solani degradation of all lignins or aromatic acids. Results indicated that AF-W1 used lignin as a sole carbon source.

  8. Migration of (14)C in the paddy soil-to-rice plant system after (14)C-acetic acid breakdown by microorganisms below the plow layer.

    PubMed

    Ogiyama, Shinichi; Takeda, Hiroshi; Ishii, Nobuyoshi; Uchida, Shigeo

    2010-02-01

    Migration of (14)C derived from (14)C-acetic acid was examined by using soils sampled from paddies in four administrative areas in Japan (Aomori, Yamanashi, Ehime and Okinawa) and rice plant in a tracer experiment to understand the fate of (14)C in the paddy soil-to-rice plant system. The loss of (14)C radioactivity levels derived from (14)C-acetic acid was caused by soil microorganism breakdown. A part of the (14)C fixation to soil was caused by microbial assimilation into the fatty acid fraction. (14)C moved upward via two different types of (14)C dynamics in soil: quick movement upward; and constant but slow movement upward. (14)C was highly assimilated into the plant panicle and that was caused by the root-uptake and the transfer of (14)C. Migration of (14)C derived from (14)C-acetic acid relied heavily upon changes of chemical forms and characteristics of (14)C-compound as caused by microorganisms in soil.

  9. The metabolism of [14C]-debrisoquine in man.

    PubMed Central

    Idle, J R; Mahgoub, A; Angelo, M M; Dring, L G; Lancaster, R; Smith, R L

    1979-01-01

    1 The synthesis of [14C]-debrisoquine hydrochloride and 4-hydroxy-debrisoquine sulphate is described. 2 The metabolic fate and excretion profile in both urine and faeces of 14C-labelled debrisoquine was studied in five healthy human subjects. 3 Investigations showed that the drug is well-absorbed after a single oral dose of 32 mg and quantitatively eliminated from the body within three days. 4 4-Hydroxy-debrisoquine is the major metabolite of debrisoquine, although significant amounts of 5-,6-, 7- and 8-hydroxy-debrisoquine are also formed. 5 Electron-capture gas chromatography is a useful method for measuring debrisoquine and its five hydroxylated metabolites in urine at the pg level. PMID:371651

  10. Pediatric microdose and microtracer studies using 14C in Europe.

    PubMed

    Turner, M A; Mooij, M G; Vaes, W H J; Windhorst, A D; Hendrikse, N H; Knibbe, C A J; Kõrgvee, L T; Maruszak, W; Grynkiewicz, G; Garner, R C; Tibboel, D; Park, B K; de Wildt, S N

    2015-09-01

    Important information gaps remain on the efficacy and safety of drugs in children. Pediatric drug development encounters several ethical, practical, and scientific challenges. One barrier to the evaluation of medicines for children is a lack of innovative methodologies that have been adapted to the needs of children. This article presents our successful experience of pediatric microdose and microtracer studies using (14) C-labeled probes in Europe to illustrate the strengths and limitations of these approaches.

  11. Airy structure in 16O+14C nuclear rainbow scattering

    NASA Astrophysics Data System (ADS)

    Ohkubo, S.; Hirabayashi, Y.

    2015-08-01

    The Airy structure in 16 O +14 C rainbow scattering is studied with an extended double-folding (EDF) model that describes all the diagonal and off-diagonal coupling potentials derived from the microscopic realistic wave functions for 16 O by using a density-dependent nucleon-nucleon force. The experimental angular distributions at EL=132 , 281, and 382.2 MeV are well reproduced by the calculations. By studying the energy evolution of the Airy structure, the Airy minimum around θ =76∘ in the angular distribution at EL=132 MeV is assigned as the second-order Airy minimum A 2 in contrast to the recent literature which assigns it as the third order A 3 . The Airy minima in the 90∘ excitation function is investigated in comparison with well-known 16 O +16 O and 12 C +12 C systems. Evolution of the Airy structure into the molecular resonances with the 16 O +14 C cluster structure in the low-energy region around Ec .m .=30 MeV is discussed. It is predicted theoretically for the first time for a non-4 N 16O +14 C system that Airy elephants in the 90∘ excitation function are present.

  12. Disposition of (/sup 14/C)dimercaptosuccinic acid in mice

    SciTech Connect

    Liang, Y.Y.; Marlowe, C.; Waddell, W.J.

    1986-04-01

    Dimercaptosuccinic acid labeled with /sup 14/C ((/sup 14/C)DMSA) was administered to mice iv; the mice were frozen by immersion in dry ice/hexane at 6 and 20 min and 1, 3, 9, and 24 hr after injection. The frozen mice were sectioned and processed for whole-body autoradiography for soluble substances. The radioactivity was highly localized in extracellular fluids such as the subcutaneous, intrapleural, intraperitoneal, and periosteal spaces. There was a pronounced accumulation in the periosteal fluid above that in other fluids during the first hour after injection. Most of the radioactivity was eliminated by the kidney and liver. Pretreatment of a mouse with HgCl/sub 2/ subcutaneously 1 hr before (/sup 14/C)DMSA produced an increase in radioactivity in the liver and a decrease in the lungs. A high concentration of radioactivity was seen at the subcutaneous site of injection of the HgCl/sub 2/. The results are interpreted to indicate that most of the DMSA is in the extracellular space but that it can cross cellular membranes to some extent. The pronounced accumulation in periosteal fluid may be an interaction of DMSA with Ca2+ in this space. No tissue had a pronounced retention of the compound, but the lungs retained more than most other tissues.

  13. The fate of {sup 14}C-pyrene and {sup 14}C-chrysene in soils amended with a PAH mixture

    SciTech Connect

    Guthrie, E.; Thompkins, J.; Pfaender, F.

    1995-12-31

    Polycyclic Aromatic Hydrocarbons (PAH) are ubiquitous environmental contaminants at many hazardous waste sites. Microbial processes are known to influence the fate of PAH in soils and can effect PAH structure, toxicity, bioavailability, and association with soil organic matter (SOM). Experiments were conducted to determine the extent of {sup 14}C-pyrene or {sup 14}C-chrysene associations with soil organic matter (SOM) in soils amended with a PAH mixture and either a [4,5,9,10-{sup 14}C]pyrene or [5,6,11,12-{sup 14}C] chrysene tracer. Changes in microbial respiration ({sup 14}CO{sub 2} efflux), {sup 14}C-volatile organics, {sup 14}C-water soluble metabolites, and {sup 14}C-SOM were measured over time in continuously, aerated microcosms. The bioavailability of {sup 14}C-products in SOM fractions was determined using a mineralization endpoint assay. Extracts of {sup 14}C products in SOM fractions were tested for acute and chronic toxicity using Microtox{trademark}. The {sup 14}C-products associated with residual soil fractions were further extracted with HF/HCI and methylene chloride and then analyzed with LC-MS. The presence of a PAH mixture enhanced {sup 14}C-pyrene mineralization in non-adapted, pristine soils to a greater extent than {sup 14}C-pyrene mineralization observed in pristine soils amended with a known PAH-mineralizing, microbial community. Mineralization of {sup 14}C-chrysene in non-adapted, pristine soils was greater than NaN{sup 3} abiotic, control soils, but significantly less than {sup 14}C-chrysene mineralization in pristine soils amended with a known PAH-mineralizing, microbial community. The major fate of {sup 14}C-pyrene, {sup 14}C-chrysene, and PAH mixtures is association with SOM.

  14. Microdose 14C-urea breath test in detection of Helicobacter pylori.

    PubMed

    Bielański, W; Konturek, S J; Dobrzańska, M J; Pytko-Polończyk, J; Sito, E; Marshall, B J

    1996-03-01

    Etiologic role for Helicobacter pylori (Hp) seems to be well established in gastric pathology. The high urease activity of Hp can be used to detect this bacterium by non-invasive urea breath tests (UBT). We validated the microdose version of the test in which 37 kBq 14C-urea is given orally in capsule. With the cut off value > 100 DPM as positive, UBT results correlated highly significant with combined results for invasive methods i.e. CLOtest + histology score. The reproducibility of the test was 100%. The results obtained for the breath test performed locally were almost identical with that read at remote laboratory. The data found for fasting and fed states of subjects agreed in 87%. When 14C-urea was confined in the mouth of both Hp positive and Hp negative patients UBT showed the presence of urease activity in the mouth cavity. 14C-urea capsule based breath test is highly reliable, safe, and reproducible for detection of Hp in the stomach. Results can be obtained within 15 min if a scintilation counter is nearby, or breath samples can be mailed to a testing laboratory for analysis.

  15. Behavior of sup 14 C aflatoxin M1 during camembert cheese making

    SciTech Connect

    Fremy, J.M.; Roiland, J.C.; Gaymard, A. )

    1990-05-01

    Camembert cheeses are made from raw milk spiked with aflatoxin M1. Three aflatoxin M1 levels (7.5 micrograms/L, 3 micrograms/L, and 0.3 micrograms/L) are used. In curds 35.6, 47.1, and 57.7% of aflatoxin M1, respectively, are recovered, and in wheys 64.4, 52.9, and 42.3%, respectively, are recovered. During the first 15 days of storage, the aflatoxin M1 content of different cheeses decreases 25, 55, and 75%, respectively. A similar experiment is made with milk contaminated with {sup 14}C labeled aflatoxin M1. The same results are obtained, except for the behavior of aflatoxin M1 in cheese; the same 14C activity is recovered during storage for 30 days.

  16. Autoradiographic disposition of (1-methyl-/sup 14/C)- and (2-/sup 14/C)caffeine in mice

    SciTech Connect

    Lachance, M.P.; Marlowe, C.; Waddell, W.J.

    1983-11-01

    Male, C57B1/6J mice received either (1-methyl-14C)caffeine or (2-14C)caffeine via the tail vein at a dose of 0.7 or 11 mg/kg, respectively. At 0.1, 0.33, 1, 3, 9, and 24 hr after treatment, the mice were anesthetized with ether and frozen by immersion in dry ice/hexane. The mice were processed for whole-body autoradiography by the Ullberg technique; this procedure does not allow thawing or contact with solvents. All autoradiographs revealed some retention of radioactivity at early time intervals in the lacrimal glands, seminal vesicle fluid, nasal and olfactory epithelium, and retinal melanocytes. The remaining portion of the animal was densitometrically uniform except for the lower levels noted in the CNS and adipose tissues. Excretion of radioactivity by the liver and kidneys seems to be the major routes of elimination. Localization in the liver at late time intervals was confined principally to the centrilobular region. Late sites of retention, observed only after (1-methyl-14C)caffeine administration, included the pancreas, minor and major salivary glands, splenic red pulp, thymal cortex, bone marrow, and gastrointestinal epithelium. Sites of localization present in both studies included the olfactory epithelium, lacrimal glands, hair follicles, and retinal melanocytes. Further studies are needed to determine whether the localization at these various sites is due to metabolic degradation, active transport, or possibly a specific receptor interaction.

  17. Weathering of ordinary chondrites from Oman: Correlation of weathering parameters with 14C terrestrial ages and a refined weathering scale

    NASA Astrophysics Data System (ADS)

    Zurfluh, Florian J.; Hofmann, Beda A.; Gnos, Edwin; Eggenberger, Urs; Jull, A. J. Timothy

    2016-09-01

    We have investigated 128 14C-dated ordinary chondrites from Oman for macroscopically visible weathering parameters, for thin section-based weathering degrees, and for chemical weathering parameters as analyzed with handheld X-ray fluorescence. These 128 14C-dated meteorites show an abundance maximum of terrestrial age at 19.9 ka, with a mean of 21.0 ka and a pronounced lack of samples between 0 and 10 ka. The weathering degree is evaluated in thin section using a refined weathering scale based on the current W0 to W6 classification of Wlotzka (1993), with five newly included intermediate steps resulting in a total of nine (formerly six) steps. We find significant correlations between terrestrial ages and several macroscopic weathering parameters. The correlation of various chemical parameters including Sr and Ba with terrestrial age is not very pronounced. The microscopic weathering degree of metal and sulfides with newly added intermediate steps shows the best correlation with 14C terrestrial ages, demonstrating the significance of the newly defined weathering steps. We demonstrate that the observed 14C terrestrial age distribution can be modeled from the abundance of meteorites with different weathering degrees, allowing the evaluation of an age-frequency distribution for the whole meteorite population.

  18. 17 CFR 240.14c-3 - Annual report to be furnished security holders.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... security holders. 240.14c-3 Section 240.14c-3 Commodity and Securities Exchanges SECURITIES AND EXCHANGE... Section 14(c) § 240.14c-3 Annual report to be furnished security holders. (a) If the information statement... such meeting, of security holders at which directors of the registrant, other than an...

  19. 17 CFR 240.14c-3 - Annual report to be furnished security holders.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... security holders. 240.14c-3 Section 240.14c-3 Commodity and Securities Exchanges SECURITIES AND EXCHANGE... Section 14(c) § 240.14c-3 Annual report to be furnished security holders. (a) If the information statement... such meeting, of security holders at which directors of the registrant, other than an...

  20. Premises and physical mechanisms to explain plateau boundaries in marine planktic 14C records as absolute age markers

    NASA Astrophysics Data System (ADS)

    Sarnthein, Michael; Grootes, Pieter M.

    2010-05-01

    Changes in marine planktic reservoir age variations hamper severely our ability to age calibrate and use marine records as atmospheric 14C records. Genuine atmospheric 14C changes may overlap with changes induced by massive changes in surface ocean hydrography. However, the deglacial Cariaco Basin record (tuned to U/Th ages of the Hulu record) forms a rare case, where the near-surface ocean and its planktic foraminifera may be in reasonably good exchange with the atmosphere, undisturbed by upwelled old deepwater masses. Accordingly, this core was used to connect IntCal09 with the marine record. High-density dating of this core resolved a suite of ~8 sediment sections over glacial-to-interglacial intervals of 400-1500 yr, where planktic 14C ages stay largely constant ("plateaus"), interspersed with sections, where 14C ages rapidly increase with depth ("jumps"). In harmony with IntCal09 we don't discard this pattern and its potentially important information as mere noise but accept it as real, per analogy to 14C plateaus and jumps established for the tree ring calibrated Holocene. This plateau suite was used for plateau tuning in 8 other high-sedimentation rate and high sampling rate (75-200 yr) deep-sea cores. Here, the plateaus with their characteristic internal structure can hardly be ascribed to irregular pulses of extremely high hemipelagic sedimentation rates leading to 5-50 cm long but otherwise undisturbed sediment sections with constant 14C age. The favored explanation is varying atmospheric 14C concentrations reflected in the near-surface ocean. The age difference between locally measured and atmospheric plateau ages in the reference record serves for deducing local planktic reservoir ages. However, occasional but rare millennial-scale events of changing admixture of old deep-ocean waters may disrupt the atmospheric plateaus in deep-sea cores. The latter influence is distinguished by evaluating the complete deglacial plateau suite in each core, keeping

  1. Human folate metabolism using 14C-accelerator mass spectrometry

    SciTech Connect

    Clifford, A. J.; Arjomand, A.; Duecker, S. R.; Johnson, H.; Schneider, P. D.; Zulim, R. A.; Bucholz, B. A.; Vogel, J. S.

    1999-03-25

    Folate is a water soluble vitamin required for optimal health, growth and development. It occurs naturally in various states of oxidation of the pteridine ring and with varying lengths to its glutamate chain. Folates function as one-carbon donors through methyl transferase catalyzed reactions. Low-folate diets, especially by those with suboptimal methyltransferase activity, are associated with increased risk of neural tube birth defects in children, hyperhomocysteinemic heart disease, and cancer in adults. Rapidly dividing (neoplastic) cells have a high folate need for DNA synthesis. Chemical analogs of folate (antifolates) that interfere with folate metabolism are used as therapeutic agents in cancer treatment. Although much is known about folate chemistry, metabolism of this vitamin in vivo in humans is not well understood. Since folate levels in blood and tissues are very low and methods to measure them are inadequate, the few previous studies that have examined folate metabolism used large doses of radiolabeled folic acid in patients with Hodgkin's disease and cancer (Butterworth et al. 1969, Krumdieck et al. 1978). A subsequent protocol using deuterated folic acid was also insufficiently sensitive to trace a physiologic folate dose (Stites et al. 1997). Accelerator mass spectrometry (AMS) is an emerging bioanalytical tool that overcomes the limitations of traditional mass spectrometry and of decay counting of long lived radioisotopes (Vogel et al. 1995). AMS can detect attomolar concentrations of 14 C in milligram-sized samples enabling in vivo radiotracer studies in healthy humans. We used AMS to study the metabolism of a physiologic 80 nmol oral dose of 14 C-folic acid (1/6 US RDA) by measuring the 14 C-folate levels in serial plasma, urine and feces samples taken over a 150-day period after dosing a healthy adult volunteer.

  2. Assessment of the 14C-Glycocholic Acid Breath Test

    PubMed Central

    James, O. F. W.; Agnew, J. E.; Bouchier, I. A. D.

    1973-01-01

    The 1-(14C)-glycine-glycocholic-acid breath test has been performed on 104 subjects and a normal range established. Abnormal results due to bacterial deconjugation of bile salts were found not only in patients with the “contaminated bowel” syndrome and in those with ileal resection but also in a third group, patients with cholangitis. Abnormal results were also found in patients with gastrocolic fistula and staphylococcal enterocolitis, while mildly abnormal results were also found in some patients with liver disease. PMID:4718834

  3. Urea recycling from the renal pelvis in sheep: A study with ( sup 14 C)urea

    SciTech Connect

    Cirio, A.; Boivin, R. )

    1990-05-01

    To test the hypothesis that urea can be recycled from the renal pelvis, (14C)urea diluted in native urine (1 microCi/ml) was perfused (0.5 ml/min) into one of the pelvises of sheep fed either normal (NP) or low (LP)-protein diets. Blood samples were obtained from the ipsilateral renal vein and from the carotid artery throughout the perfusions. 14C activity determinations in urine and plasma demonstrated a flux of (14C)urea from the pelvis to renal vein blood (40,000 in NP and 130,000 disintegrations/min in LP sheep, P less than 0.01). The corresponding flux of native urea was only 1.5 times higher in NP than in LP sheep (6.8 +/- 1.1 vs. 4.7 +/- 2.9 mumol/min, not significant) despite their 8 times higher urinary concentration of urea. The fraction of filtered urea that was reabsorbed in the pelvis was larger in LP sheep (7.5 +/- 3.7 vs. 1.9 +/- 0.7% in NP sheep, P less than 0.05). A fraction of urea is thus actually recycled from the renal pelvis in sheep, and this pelvic retention is enhanced in LP animals. The importance of this phenomenon in the nitrogen economy is discussed.

  4. sup 14 C-urea breath test for the detection of Helicobacter pylori

    SciTech Connect

    Veldhuyzen van Zanten, S.J.; Tytgat, K.M.; Hollingsworth, J.; Jalali, S.; Rshid, F.A.; Bowen, B.M.; Goldie, J.; Goodacre, R.L.; Riddell, R.H.; Hunt, R.H. )

    1990-04-01

    The high urease activity of Helicobacter pylori can be used to detect this bacterium by noninvasive breath tests. We have developed a {sup 14}C-urea breath test which uses 5 microCi {sup 14}C with 50 mg nonradioactive urea. Breath samples are collected at baseline and every 30 min for 2 h. Our study compared the outcome of the breath test to the results of histology and culture of endoscopically obtained gastric biopsies in 84 patients. The breath test discriminated well between the 50 positive patients and the 34 patients negative for Helicobacter pylori: the calculated sensitivity was 100%, specificity 88%, positive predictive value 93%, and negative predictive value 100%. Treatment with bismuth subsalicylate and/or ampicillin resulted in lower counts of exhaled {sup 14}CO{sub 2} which correlated with histological improvement in gastritis. The {sup 14}C-urea breath test is a better gold standard for the detection of Helicobacter pylori than histology and/or culture.

  5. Incorporation of UDP-( sup 14 C)glucose into xyloglucan by pea membranes

    SciTech Connect

    Gordon, R.; Maclachlan, G. )

    1989-09-01

    The water-insoluble 1,4-{beta}-linked products formed from UDP-({sup 14}C)glucose by pea membranes were dissolved in hot dimethylsulfoxide/paraformaldehyde and fractionated on columns of controlled pore glass beads calibrated with dextran standards. The products eluted with a peak size close to 70 kilodaltons in dextran equivalents. Similar elution profiles were obtained for products formed in brief or extended incubations and at high or low substrate concentrations. Methylation analysis indicated that only a few ({sup 14}C)glucose units had been added to an endogenous acceptor to form this product. In the presence of UDP-xylose at concentrations equal to or less than UDP-({sup 14}C)glucose, incorporation from the latter was enhanced and the products elongated with time to a size range where the major components eluted between dextran 264 and 500 kilodaltons. Treatment with endo-1,4-{beta}-glucanase resulted in a mixture of oligosaccharides, including the xyloglucan subunit Glc{sub 4}Xyl{sub 3}, which were hydrolyzed further by mixed glycosidases to labeled glucose and isoprimeverose (xylosyl-1,6-{alpha}-D-glucose). In pulse-chase experiments, low molecular weight product formed from UDP-({sup 14}C)glucose alone was clearly a precursor for high molecular weight products formed subsequently in the presence of both UDP-glucose and UDP-xylose. It is concluded that the 1,4-{beta}-transglucosylation activity detected in these tests was due to an enzyme that is required for biosynthesis of the backbone of xyloglucan.

  6. Incorporation of UDP-[14C]Glucose into Xyloglucan by Pea Membranes 1

    PubMed Central

    Gordon, Ruth; Maclachlan, Gordon

    1989-01-01

    The water-insoluble 1,4-β-linked products formed from UDP-[14C]glucose by pea membranes were dissolved in hot dimethyl-sulfoxide/paraformaldehyde and fractionated on columns of controlled pore glass beads calibrated with dextran standards. The products eluted with a peak size close to 70 kilodaltons in dextran equivalents. Similar elution profiles were obtained for products formed in brief or extended incubations and at high or low substrate concentrations. Methylation analysis indicated that only a few [14C]glucose units had been added to an endogenous acceptor to form this product. In the presence of UDP-xylose at concentrations equal to or less than UDP-[14C]glucose, incorporation from the latter was enhanced and the products elongated with time to a size range where the major components eluted between dextran 264 and 500 kilodaltons. Treatment with endo-1,4-β-glucanase resulted in a mixture of oligosaccharides, including the xyloglucan subunit Glc4Xyl3, which were hydrolyzed further by mixed glycosidases to labeled glucose and isoprimeverose (xylosyl-1,6-α-d-glucose). In pulse-chase experiments, the low molecular weight product formed from UDP-[14C]glucose alone was clearly a precursor for high molecular weight products formed subsequently in the presence of both UDP-glucose and UDP-xylose. It is concluded that the 1,4-β-transglucosylation activity detected in these tests was due to an enzyme that is required for biosynthesis of the backbone of xyloglucan. Images Figure 2 PMID:16667028

  7. A shell-derived time history of bomb {sup 14}C on Georges Bank and its Labrador Sea implications

    SciTech Connect

    Weidman, C.R.; Jones, G.A.

    1993-08-15

    Bomb-produced radiocarbon has been used in the past as an important tracer of ocean circulation and as a valuable tool for calculating CO{sub 2} air-sea exchange. However, previous studies of the ocean`s time-varying bomb {sup 14}C record have been confined exclusively to analyzing banded corals, and thus their application has been limited to the lower latitudes. The first time history of bomb {sup 14}C from the high-latitude North Atlantic Ocean is obtained from a 54-year-old mollusc specimen, (Bivalvia) Arctica islandica, which was collected live from Georges Bank (41{degrees}N) in 1990. The annual growth bands of its shell were analyzed for {Delta}{sup 14}C using accelerator mass spectrometry, producing a {Delta}{sup 14}C time history from 1939 to 1990. The depleted condition of the Georges Bank bomb {sup 14}C signal relative to two coral-derived North Atlantic {Delta}{sup 14}C time histories suggests a significant deepwater source for the waters on Georges Bank. Supported by previous work linking the origin of waters on Georges Bank to the Labrador Sea, the {Delta}{sup 14}C budget on Georges Bank is modeled as Labrador Sea water, which largely becomes confined to the shelf and partially equilibrates with the atmosphere during a 1-year transit time from the Labrador Sea to Georges Bank. This model is also used to estimate a time history of bomb {sup 14}C for the Labrador Sea. Prebomb {Delta}{sup 14}C values calculated for the surface Labrador Sea suggest that a greater inventory of bomb {sup 14}C has accumulated here than has previously been reported. Deduced variations in the ventilation and/or {sup 14}CO{sub 2} uptake rates in the Labrador Sea correspond with observed changes in surface salinity of the Labrador Sea, suggesting a reduction in deepwater formation during the late 1960s and 1970s. 59 refs., 11 figs., 2 tabs.

  8. Longevity and growth of Acacia tortilis; insights from 14C content and anatomy of wood

    PubMed Central

    Andersen, Gidske L; Krzywinski, Knut

    2007-01-01

    Background Acacia tortilis is a keystone species across arid ecosystems in Africa and the Middle East. Yet, its life-history, longevity and growth are poorly known, and consequently ongoing changes in tree populations cannot be managed in an appropriate manner. In other arid areas parenchymatic bands marking growth zones in the wood have made dendrochronological studies possible. The possibilities for using pre- and post-bomb 14C content in wood samples along with the presence of narrow marginal parenchymatic bands in the wood is therefore tested to gain further insight into the age, growth and growth conditions of A. tortilis in the hyper-arid Eastern Desert of Egypt. Results Based on age scenarios and the Gompertz growth equation, the age of trees studied seems to be from 200 up to 650 years. Annual radial growth estimated from calibrated dates based on the post-bomb 14C content of samples is up to 2.4 mm, but varies both spatially and temporally. Parenchymatic bands are not formed regularly. The correlation in band pattern among trees is poor, both among and within sites. Conclusion The post-bomb 14C content of A. tortilis wood gives valuable information on tree growth and is required to assess the age scenario approach applied here. This approach indicates high longevities and slow growth of trees. Special management measures should therefore be taken at sites where the trend in tree population size is negative. The possibilities for dendrochronological studies based on A. tortilis from the Eastern Desert are poor. However, marginal parenchymatic bands can give insight into fine scale variation in growth conditions and the past management of trees. PMID:17573964

  9. Low-Charge State AMS for High Throughput 14C Quantification

    SciTech Connect

    Ognibene, T.J.; Roberts, M.L.; Southon, J.R.; Vogel, J.S.

    2000-06-16

    Accelerator mass spectrometry (AMS) quantifies attomole (10{sup -18}) amounts of {sup 14}C in milligram sized samples. This sensitivity is used to trace nutrients, toxins and therapeutics in humans and animals at less than {micro}g/kg doses containing 1-100 nCi of {sup 14}C. Widespread use of AMS in pharmaceutical development and biochemical science has been hampered by the size and expense of the typical spectrometer that has been developed for high precision radiocarbon dating. The precision of AMS can be relaxed for biochemical tracing, but sensitivity, accuracy and throughput are important properties that must be maintained in spectrometers designed for routine quantification. We are completing installation of a spectrometer that will maintain the high throughput of our primary spectrometer but which requires less than 20% of the floor space and of the cost. Sensitivity and throughput are kept high by using the LLNL intense cesium sputter ion source with solid graphitic samples. Resultant space-charge effects are minimized by careful modeling to find optimal ion transport in the spectrometer. A long charge-changing ''stripper gas'' volume removes molecular isobars at potentials of a few hundred kiloVolts, reducing the size of the accelerating component. Fast ion detectors count at high rates to keep a wide dynamic range for 14 C concentrations. Solid sample presentation eliminates the sample cross contamination that degrades accuracy and the effects of ''memory'' in the ion source. Automated processes are under development for conversion of liquid and solid biological samples to the preferred graphitic form for the ion source.

  10. Determination of Natural 14C Abundances in Dissolved Organic Carbon in Organic-Rich Marine Sediment Porewaters by Thermal Sulfate Reduction

    NASA Astrophysics Data System (ADS)

    Johnson, L.; Komada, T.

    2010-12-01

    The abundances of natural 14C in dissolved organic carbon (DOC) in the marine environment hold clues regarding the processes that influence the biogeochemical cycling of this large carbon reservoir. At present, UV irradiation is the widely accepted method for oxidizing seawater DOC for determination of their 14C abundances. This technique yields precise and accurate values with low blanks, but it requires a dedicated vacuum line, and hence can be difficult to implement. As an alternative technique that can be conducted on a standard preparatory vacuum line, we modified and tested a thermal sulfate reduction method that was previously developed to determine δ13C values of marine DOC (Fry B. et al., 1996. Analysis of marine DOC using a dry combustion method. Mar. Chem., 54: 191-201.) to determine the 14C abundances of DOC in marine sediment porewaters. In this method, the sample is dried in a 100 ml round-bottom Pyrex flask in the presence of excess oxidant (K2SO4) and acid (H3PO4), and combusted at 550 deg.C. The combustion products are cryogenically processed to collect and quantify CO2 using standard procedures. Materials we have oxidized to date range from 6-24 ml in volume, and 95-1500 μgC in size. The oxidation efficiency of this method was tested by processing known amounts of reagent-grade dextrose and sucrose (as examples of labile organic matter), tannic acid and humic acid (as examples of complex natural organic matter), and porewater DOC extracted from organic-rich nearshore sediments. The carbon yields for all of these materials averaged 99±4% (n=18). The 14C abundances of standard materials IAEA C-6 and IAEA C-5 processed by this method using >1mgC aliquots were within error of certified values. The size and the isotopic value of the blank were determined by a standard dilution technique using IAEA C-6 and IAEA C-5 that ranged in size from 150 to 1500 μgC (n=4 and 2, respectively). This yielded a blank size of 6.7±0.7 μgC, and a blank isotopic

  11. Accelerator mass spectrometry analysis of 14C-oxaliplatin concentrations in biological samples and 14C contents in biological samples and antineoplastic agents

    NASA Astrophysics Data System (ADS)

    Toyoguchi, Teiko; Kobayashi, Takeshi; Konno, Noboru; Shiraishi, Tadashi; Kato, Kazuhiro; Tokanai, Fuyuki

    2015-10-01

    Accelerator mass spectrometry (AMS) is expected to play an important role in microdose trials. In this study, we measured the 14C concentration in 14C-oxaliplatin-spiked serum, urine and supernatant of fecal homogenate samples in our Yamagata University (YU) - AMS system. The calibration curves of 14C concentration in serum, urine and supernatant of fecal homogenate were linear (the correlation coefficients were ⩾0.9893), and the precision and accuracy was within the acceptance criteria. To examine a 14C content of water in three vacuum blood collection tubes and a syringe were measured. 14C was not detected from water in these devices. The mean 14C content in urine samples of 6 healthy Japanese volunteers was 0.144 dpm/mL, and the intra-day fluctuation of 14C content in urine from a volunteer was little. The antineoplastic agents are administered to the patients in combination. Then, 14C contents of the antineoplastic agents were quantitated. 14C contents were different among 10 antineoplastic agents; 14C contents of paclitaxel injection and docetaxel hydrate injection were higher than those of the other injections. These results indicate that our quantitation method using YU-AMS system is suited for microdosing studies and that measurement of baseline and co-administered drugs might be necessary for the studies in low concentrations.

  12. Cutaneous uptake of 14C-HD vapor by the hairless guinea pig. Technical report, December 1992-June 1993

    SciTech Connect

    Logan, T.P.; Bongiovanni, R.; Millard, C.B.; Shutz, M.B.; Schultz, S.M.

    1996-10-01

    The hairless guinea pig (HGP) is used by our laboratory to model the human cutaneous response to sulfur mustard (HD) exposure. We have determined the HD content in the skin of HOP after 7-minute exposures to vapors saturated with a mixture of HD and 14C-HD. Concentration/time (C1) values in the range of 2 mg/sq cm/min were determined by counting skin 14C disintegrations per minute (dpm) in animals euthanized immediately after exposure. These values are similar to human penetration rates obtained by other investigators. A direct relationship between C1 and relative humidity was demonstrated in 5 of 6 studies. A rate curve monitoring the reduction in skin 14C dpm was developed for animals euthanized between 0 and 24 hours post exposure. This curve showed the greatest change after 1 hour. Epidermal and dermal distribution of 14C at 24 hours was measured for two animals. Site preference for HD penetration, multiple use of a vapor cap containing HD, and 14C content of adhesive tape were also investigated with radiolabeled HD to evaluate other aspects of the experimental model. These results contribute to a better understanding of the cutaneous response to HD in the HGP model.

  13. A 14C age calibration curve for the last 60 ka: the Greenland-Hulu U/Th timescale and its impact on understanding the Middle to Upper Paleolithic transition in Western Eurasia.

    PubMed

    Weninger, Bernhard; Jöris, Olaf

    2008-11-01

    This paper combines the data sets available today for 14C-age calibration of the last 60 ka. By stepwise synchronization of paleoclimate signatures, each of these sets of 14C-ages is compared with the U/Th-dated Chinese Hulu Cave speleothem records, which shows global paleoclimate change in high temporal resolution. By this synchronization we have established an absolute-dated Greenland-Hulu chronological framework, against which global paleoclimate data can be referenced, extending the 14C-age calibration curve back to the limits of the radiocarbon method. Based on this new, U/Th-based Greenland(Hulu) chronology, we confirm that the radiocarbon timescale underestimates calendar ages by several thousand years during most of Oxygen Isotope Stage 3. Major atmospheric 14C variations are observed for the period of the Middle to Upper Paleolithic transition, which has significant implications for dating the demise of the last Neandertals. The early part of "the transition" (with 14C ages > 35.0 ka 14C BP) coincides with the Laschamp geomagnetic excursion. This period is characterized by highly-elevated atmospheric 14C levels. The following period ca. 35.0-32.5 ka 14C BP shows a series of distinct large-scale 14C age inversions and extended plateaus. In consequence, individual archaeological 14C dates older than 35.0 ka 14C BP can be age-calibrated with relatively high precision, while individual dates in the interval 35.0-32.5 ka 14C BP are subject to large systematic age-'distortions,' and chronologies based on large data sets will show apparent age-overlaps of up to ca. 5,000 cal years. Nevertheless, the observed variations in past 14C levels are not as extreme as previously proposed ("Middle to Upper Paleolithic dating anomaly"), and the new chronological framework leaves ample room for application of radiocarbon dating in the age-range 45.0-25.0 ka 14C BP at high temporal resolution.

  14. Carbon cycle dynamics and solar activity embedded in a high-resolution 14C speleothem record from Belize, Central America

    NASA Astrophysics Data System (ADS)

    Lechleitner, Franziska A.; Breitenbach, Sebastian F. M.; McIntyre, Cameron; Asmerom, Yemane; Prufer, Keith M.; Polyak, Victor; Culleton, Brendan J.; Kennett, Douglas J.; Eglinton, Timothy I.; Baldini, James U. L.

    2015-04-01

    Speleothem 14C has recently emerged as a potentially powerful proxy for climate reconstruction. Several studies have highlighted the link between karst hydrology and speleothem 14C content, and a number of possible causes for this relationship have been proposed, such as dripwater flow dynamics in the karst and changes in soil organic matter (SOM) turnover time (e.g. Griffiths et al., 2012). Here we present a high resolution 14C record for a stalagmite (YOK-I) from Yok Balum cave in southern Belize, Central America. YOK-I grew continuously over the last 2000 years, and has been dated very precisely with the U-Th method (40 dates, mean uncertainty < 10 years). The excellent chronological control for this stalagmite allows us to calculate 14C activity (a14C) at the time of speleothem deposition (a14Cinit), as well as the dead carbon fraction (DCF), predominantly a measure of the reservoir effect introduced by limestone dissolution in the karst (Genty et al., 2001). Both records show striking similarities to atmospheric a14C (IntCal13) and reconstructions of solar activity and 14C production rate. We infer close coupling between cave environment and atmosphere, with minimal signal dampening, an observation supported by monitoring data (Ridley et al., in press). DCF fluctuates between approximately 10% and 16% over the entire record, with distinctly lower DCF values and higher a14Cinit during a period of reduced rainfall between ca. 700-1100 AD (linked to the Classic Maya Collapse). This behavior is consistent with observations made elsewhere, and suggests that DCF responds to karst hydrological variability, specifically open-closed system transitions. YOK-I a14Cinit typically lags atmospheric values by 10-100 cal years. A shorter lag appears to be linked to periods of drought, suggesting a response of SOM dynamics above the cave to rainfall reduction. Specifically, drought is inferred to lead to reduced bioproductivity and soil carbon turnover, lowering contributions

  15. Luminescence dating of ancient Darhad basin, Mongolia

    NASA Astrophysics Data System (ADS)

    Cheul Kim, Jin; Yi, Sangheon; Lim, Jaesoo; Kim, Ju-Yong

    2016-04-01

    Darhad basin is located in the northern Mongolia, in the western end of the Baikal Rift Zone. In contrast to the neighboring Lake Hovsgol, Mongolia's largest and deepest lake, the Darhad is a drained lake basin. It is ~100 km long (north-south), 20-40 km wide and covered by sediments which locally exceed 500 m thickness (Zorin et al., 1989). Darhad basin is characterized by alternating episodes of expansion and desiccation that are closely related with the Pleistocene damming events. Previous studies of the Darhad Basin suggest that the last paleolake was dammed by a large glacier or the sediments (Selivanov, 1967, 1968; Krivonogov et al., 2005; Gillespie et al., 2008). Especially, recent expansion of the paleolake might be caused by the two glacial maxima during MIS 4 and 2. However, glacier-dammed lakes might be short-lived, dried up and permafrost occurred in the drained basin during the Holocene period. The uppermost paleolake sediments (13.2 m depth) are exposed following the curvature of the meandering river (called "Hodon outcrop"). It is considered the most likely site for the youngest paleolake sediments because it is distributed in the northern middle part of the paleolake. Krivonogov et al. 2012 described the Hodon outcrop with the sedimentological and chronological data. Age dating of 16 samples (11 mollusk shells, 5 wood fragments) indicated that Hodon outcrop sediments were deposited between 10.1±7 and 4.9±5 ka. However, the ages obtained on shells much older dates than the matched wood samples because of ingestion of old carbon by mollusks. The age difference between shells and wood fragments is a minimum of 1.73 ka and a maximum of 3.41 ka (average 2.5 ka). In this case, 14C ages from shells should be corrected with appropriate correction factor. However, the old carbon effects could vary temperally and spatially in the Darhad paleolake. The limited number of the 14C ages from wood fragments result in a simple linear trend in the depth-age curve

  16. Tritium and 14C background levels in pristine aquatic systems and their potential sources of variability.

    PubMed

    Eyrolle-Boyer, Frédérique; Claval, David; Cossonnet, Catherine; Zebracki, Mathilde; Gairoard, Stéphanie; Radakovitch, Olivier; Calmon, Philippe; Leclerc, Elisabeth

    2015-01-01

    Tritium and (14)C are currently the two main radionuclides discharged by nuclear industry. Tritium integrates into and closely follows the water cycle and, as shown recently the carbon cycle, as does (14)C (Eyrolle-Boyer et al., 2014a, b). As a result, these two elements persist in both terrestrial and aquatic environments according to the recycling rates of organic matter. Although on average the organically bound tritium (OBT) activity of sediments in pristine rivers does not significantly differ today (2007-2012) from the mean tritiated water (HTO) content on record for rainwater (2.4 ± 0.6 Bq/L and 1.6 ± 0.4 Bq/L, respectively), regional differences are expected depending on the biomass inventories affected by atmospheric global fallout from nuclear testing and the recycling rate of organic matter within watersheds. The results obtained between 2007 and 2012 for (14)C show that the levels varied between 94.5 ± 1.5 and 234 ± 2.7 Bq/kg of C for the sediments in French rivers and across a slightly higher range of 199 ± 1.3 to 238 ± 3.1 Bq/kg of C for fish. This variation is most probably due to preferential uptake of some organic carbon compounds by fish restraining (14)C dilution with refractory organic carbon and/or with old carbonates both depleted in (14)C. Overall, most of these ranges of values are below the mean baseline value for the terrestrial environment (232.0 ± 1.8 Bq/kg of C in 2012, Roussel-Debet, 2014a) in relation to dilution by the carbonates and/or fossil organic carbon present in aquatic systems. This emphasises yet again the value of establishing regional baseline value ranges for these two radionuclides in order to account for palaeoclimatic and lithological variations. Besides, our results obtained from sedimentary archive investigation have confirmed the delayed contamination of aquatic sediments by tritium from the past nuclear tests atmospheric fallout, as recently demonstrated from data chronicles (Eyrolle

  17. Accelerator mass spectrometry 14C determination in CO2 produced from laser decomposition of aragonite.

    PubMed

    Rosenheim, Brad E; Thorrold, Simon R; Roberts, Mark L

    2008-11-01

    The determination of (14)C in aragonite (CaCO(3)) decomposed thermally to CO(2) using an yttrium-aluminum-garnet doped neodymium laser is reported. Laser decomposition accelerator mass spectrometry (LD-AMS) measurements reproduce AMS determinations of (14)C from the conventional reaction of aragonite with concentrated phosphoric acid. The lack of significant differences between these sets of measurements indicates that LD-AMS radiocarbon dating can overcome the significant fractionation that has been observed during stable isotope (C and O) laser decomposition analysis of different carbonate minerals. The laser regularly converted nearly 30% of material removed into CO(2) despite it being optimized for ablation, where laser energy breaks material apart rather than chemically altering it. These results illustrate promise for using laser decomposition on the front-end of AMS systems that directly measure CO(2) gas. The feasibility of such measurements depends on (1) the improvement of material removal and/or CO(2) generation efficiency of the laser decomposition system and (2) the ionization efficiency of AMS systems measuring continuously flowing CO(2).

  18. AMS 14C chronology of the world's southernmost woolly mammoth ( Mammuthus primigenius Blum.)

    NASA Astrophysics Data System (ADS)

    Takahashi, Keiichi; Wei, Guangbiao; Uno, Hikaru; Yoneda, Minoru; Jin, Changzhu; Sun, Chengkai; Zhang, Sheng; Zhong, Bei

    2007-04-01

    The world's definite southernmost woolly mammoth record is a molar from Ji'nan (around 36°N), Shandong Province, China. AMS 14C dating of the specimen, gave a conventional 14C age of 33,150±250 BP. The period of 40-30 ka BP corresponds to the later phase of the Marine Oxygen Isotope Stage 3 (MIS 3a), recognized as the global interstadial of the last glacial period. However, it is known that the winter monsoon strengthened in Asia during the period 35-33 ka BP, and the age of the woolly mammoth specimen from Ji'nan corresponds to that age. The specimen suggests that this area became cold and dry in 33 ka BP, and grassland or open forest, suitable habitat for woolly mammoths, developed during this short time span. This age is similar to the age of the southernmost woolly mammoth record in Europe, therefore supporting a hypothesis by Porter and An [1995. Correlation between climate events in the North Atlantic and China during the last glaciation. Nature 375, 305-308] that an important component of Chinese palaeoclimates may be linked to changes in North Atlantic oceanic conditions.

  19. Metabolism and excretion of [14C] verruculogen in a sheep.

    PubMed

    Perera, K P; Mantle, P G; Penny, R H

    1982-05-01

    [14C] Verruculogen (75 micrograms/kg) was given intravenously to a sheep under barbiturate anaesthesia to prevent the severe tremor and convulsions which would otherwise have occurred. Two hours later 28 per cent of the tremorgenic mycotoxin was detected in the liver, bile and small intestine. Approximately 0.5 per cent was excreted in the urine. Trace amounts of radiolabel were detected in the cortex and corpus striatum of the brain. Verruculogen was metabolised by the liver and converted completely to four more polar products, including two isomeric forms of desoxy-verruculogen and the weakly tremorgenic mycotoxin TR-2. The principal and most polar metabolite excreted is probably an isomer of TR-2. PMID:7100651

  20. {sup 223}Ra nuclear spectroscopy in {sup 14}C cluster radioactivity

    SciTech Connect

    Hourany, E.; Berrier-Ronsin, G.; Elayi, A.; Hoffmann-Rothe, P.; Mueller, A.C.; Rosier, L.; Rotbard, G.; Renou, G.; Liebe, A.; Poenaru, D.N.

    1995-07-01

    The energy spectrum of {sup 14}C ions emitted from {sup 223}Ra sources implanted at ISOLDE has been measured with the spectrometer SOLENO. The highest statistics (899 events) and the best energy resolution (90 keV) obtained so far in cluster decay allow a real spectroscopic study. Hindrance factors for transitions to the ground state and first excited state in {sup 209}Pb, and limits for the next three low-lying states, hae been determined. The data can be explained by a parent wave function containing mainly a {ital i}{sub 11/2} spherical component.

  1. Radiocarbon dating of VIRI bone samples using ultrafiltration

    NASA Astrophysics Data System (ADS)

    Minami, Masayo; Yamazaki, Kana; Omori, Takayuki; Nakamura, Toshio

    2013-01-01

    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 14C dates of bones. However, ultrafiltration may introduce new contaminants to bone gelatins, mainly from ultrafilters used. To study the effects of ultrafiltration on 14C age, we analyzed the C/N ratio, δ13CPDB and δ15NAIR values, and 14C 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, δ13CPDB and δ15NAIR 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™ 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 14C ages than did those filtered for shorter durations. The results in this study indicate that 14C ages of unfiltered gelatin extracted from well-preserved bones can be sufficiently accurate, and that care should be taken not to

  2. 14C age of the "Museum Breccia" (Campi Flegrei) and its relevance for the origin of the Campanian Ignimbrite

    USGS Publications Warehouse

    Lirer, L.; Rolandi, G.; Rubin, M.

    1991-01-01

    Field stratigraphic investigations and AMS 14C dating of carbon particles in paleosols has resulted in a framework of the sequence and age of the pyroclastic products in the Campi Flegrei area of Southern Italy. The Museum Breccia cannot be the early phase of the Campanian Ignimbrite, as was previously believed, but is from a smaller and later eruption with an age of approximately 17,900 y B.P. This date also precludes its correlation with the Neapolitan Yellow Tuff (12,000 y B.P.). ?? 1991.

  3. Source apportionment of carbonaceous aerosol in Sao Paulo using 13C and 14C measurements

    NASA Astrophysics Data System (ADS)

    Oyama, Beatriz; Andrade, Maria de Fatima; Holzinger, Rupert; Röckmann, Thomas; Meijer, Harro A. J.; Dusek, Ulrike

    2016-04-01

    The Metropolitan Area of Sao Paulo is affected by high aerosol concentrations, which contain a large fraction of organic material. Up to date, not much is known about the composition and origin of the organic aerosol in this city. We present the first source apportionment of the carbonaceous aerosol fraction in Sao Paulo, using stable (13C) and radioactive carbon isotopes (14C). 14C provides a clear-cut distinction between fossil sources, which contain no 14C, and contemporary sources such as biofuels, biomass burning, or biogenic sources, which contain a typical contemporary 14C/12C ratio. 13C can be used to distinguish C3 plants, such as maize and sugarcane, from C4 plants. This can help to identify a possible impact of sugarcane field burning in the rural areas of Sao Paulo State on the aerosol carbon in the city. In the first part of the study, we compare two tunnel studies: Tunnel 1 is frequented only by light duty vehicles, which run mainly on mixtures of gasoline with ethanol (gasohol, 25% ethanol and 85% gasoline) or hydrated ethanol (5% water and 95% ethanol). Tunnel 2 contains a significant fraction of heavy-duty diesel vehicles, and therefore the fraction of biofuels in the average fleet is lower. Comparison of 14C in organic and elemental carbon (OC and EC) shows that in both tunnels there is no significant contribution of biofuels to EC. Combusting ethanol-gasoline fuels in a vehicle engine does apparently not result in significant EC formation from ethanol. Biofuels contribute around 45% to OC in Tunnel 1 an only 20% in Tunnel 2, reflecting a strong impact of diesel vehicles in Tunnel 2. In the second part of the study we conduct a source apportionment of ambient aerosol carbon collected in a field study during winter (July-August) 2012. Ambient EC has two main sources, vehicular emissions and biomass burning. We estimate a contribution of vehicular sources to EC of roughly 90% during weekdays and 80% during weekends, using the 14C values measured in

  4. Measurements of 14C in ancient ice from Taylor Glacier, Antarctica constrain in situ cosmogenic 14CH4 and 14CO production rates

    NASA Astrophysics Data System (ADS)

    Petrenko, Vasilii V.; Severinghaus, Jeffrey P.; Schaefer, Hinrich; Smith, Andrew M.; Kuhl, Tanner; Baggenstos, Daniel; Hua, Quan; Brook, Edward J.; Rose, Paul; Kulin, Robb; Bauska, Thomas; Harth, Christina; Buizert, Christo; Orsi, Anais; Emanuele, Guy; Lee, James E.; Brailsford, Gordon; Keeling, Ralph; Weiss, Ray F.

    2016-03-01

    Carbon-14 (14C) is incorporated into glacial ice by trapping of atmospheric gases as well as direct near-surface in situ cosmogenic production. 14C of trapped methane (14CH4) is a powerful tracer for past CH4 emissions from "old" carbon sources such as permafrost and marine CH4 clathrates. 14C in trapped carbon dioxide (14CO2) can be used for absolute dating of ice cores. In situ produced cosmogenic 14C in carbon monoxide (14CO) can potentially be used to reconstruct the past cosmic ray flux and past solar activity. Unfortunately, the trapped atmospheric and in situ cosmogenic components of 14C in glacial ice are difficult to disentangle and a thorough understanding of the in situ cosmogenic component is needed in order to extract useful information from ice core 14C. We analyzed very large (≈1000 kg) ice samples in the 2.26-19.53 m depth range from the ablation zone of Taylor Glacier, Antarctica, to study in situ cosmogenic production of 14CH4 and 14CO. All sampled ice is >50 ka in age, allowing for the assumption that most of the measured 14C originates from recent in situ cosmogenic production as ancient ice is brought to the surface via ablation. Our results place the first constraints on cosmogenic 14CH4 production rates and improve on prior estimates of 14CO production rates in ice. We find a constant 14CH4/14CO production ratio (0.0076 ± 0.0003) for samples deeper than 3 m, which allows the use of 14CO for correcting the 14CH4 signals for the in situ cosmogenic component. Our results also provide the first unambiguous confirmation of 14C production by fast muons in a natural setting (ice or rock) and suggest that the 14C production rates in ice commonly used in the literature may be too high.

  5. Effect of endomycorrhizae on the bioavailability of bound sup 14 C residues to onion plants from an organic soil treated with ( sup 14 C)fonofos

    SciTech Connect

    Nelson, S.D.; Khan, S.U. )

    1990-03-01

    Uptake of bound {sup 14}C residues from an organic soil treated with radiolabeled fonofos (O-ethyl S-phenyl ethylphosphonodithioate) by selected Glomus endomycorrhiza and onion roots was studied. The hyphae of endomycorrhizal associations were capable of removing {sup 14}C residues from the soil and transporting them to onion plants. Bioavailability of soil-bound {sup 14}C residues, as measured by {sup 14}C residue content in onion, was increased 32 and 40% over that of nonmycorrhizal plants by hyphae of Glomus intraradices and Glomus vesiculiferium, respectively. The data suggest that under field conditions endomycorrhizal infection may greatly increase the bioavailability of soil-bound pesticide residues to plants.

  6. Defective (U-14 C) palmitic acid oxidation in Duchenne muscular dystrophy

    SciTech Connect

    Carroll, J.E.; Norris, B.J.; Brooke, M.H.

    1985-01-01

    Compared with normal skeletal muscle, muscle from patients with Duchenne dystrophy had decreased (U-14 C) palmitic acid oxidation. (1-14 C) palmitic acid oxidation was normal. These results may indicate a defect in intramitochondrial fatty acid oxidation.

  7. Percutaneous absorption of ( sup 14 C)DDT and ( sup 14 C)benzo(a)pyrene from soil

    SciTech Connect

    Wester, R.C.; Maibach, H.I.; Bucks, D.A.; Sedik, L.; Melendres, J.; Liao, C.; DiZio, S. )

    1990-10-01

    The objective was to determine percutaneous absorption of DDT and benzo(a)pyrene in vitro and in vivo from soil into and through skin. Soil (Yolo County 65-California-57-8; 26% sand, 26% clay, 48% silt) was passed through 10-, 20-, and 48-mesh sieves. Soil then retained by 80-mesh was mixed with (14C)-labeled chemical at 10 ppm. Acetone solutions at 10 ppm were prepared for comparative analysis. Human cadaver skin was dermatomed to 500 microns and used in glass diffusion cells with human plasma as the receptor fluid (3 ml/hr flow rate) for a 24-hr skin application time. With acetone vehicle, DDT (18.1 +/- 13.4%) readily penetrated into human skin. Significantly less DDT (1.0 +/- 0.7%) penetrated into human skin from soil. DDT would not partition from human skin into human plasma in the receptor phase (less than 0.1%). With acetone vehicle, benzo(a)pyrene (23.7 +/- 9.7%) readily penetrated into human skin. Significantly less benzo(a)pyrene (1.4 +/- 0.9%) penetrated into human skin from soil. Benzo(a)pyrene would not partition from human skin into human plasma in the receptor phase (less than 0.1%). Substantivity (skin retention) was investigated by applying 14C-labeled chemical to human skin in vitro for only 25 min. After soap and water wash, 16.7 +/- 13.2% of DDT applied in acetone remained absorbed to skin. With soil only 0.25 +/- 0.11% of DDT remained absorbed to skin. After soap and water wash 5.1 +/- 2.1% of benzo(a)pyrene applied in acetone remained absorbed to skin. With soil only 0.14 +/- 0.13% of benzo(a)pyrene remained absorbed to skin.

  8. Effect of pretreatment with pentobarbital on the extent of (/sup 14/C) incorporation from (U-/sup 14/C)glucose into various rat brain glycolytic intermediates: relevance to regulation at hexokinase and phosphofructokinase

    SciTech Connect

    Miller, L.P.; Mayer, S.; Braun, L.D.; Geiger, P.; Oldendorf, W.H.

    1988-04-01

    In the present investigation we monitored the incorporation of (14C) from (U-14C)glucose into various rat brain glycolytic intermediates of conscious and pentobarbital-anesthetized animals. Labeled glucose was delivered to brain by single bolus intracarotid injection and brain tissue was subsequently prepared at 15, 30, and 45 sec by freeze-blowing. Glycolytic intermediates were then separated by column chromatography. Our results showed a gradual decrease with time of 14C-labeled glucose which gave a calculated rate for glucose metabolism of 0.86 mumol/min/g and 0.56 mumol/min/g in conscious and anesthetized animals, respectively. Compared to the results obtained using conscious animals the administration of pentobarbital not only resulted in a significant attenuation of the rate of glucose metabolism but also caused a similar reduction in the amount of 14C incorporated into several glycolytic intermediates. These intermediates included: glucose 6-phosphate, fructose 6-phosphate, fructose 1,6 diphosphate, dihydroxyacetone phosphate and post glycolytic compounds. In addition, pretreatment with pentobarbital resulted in a 75% increase in the endogenous concentration of glucose, 10% increase in glucose 6-phosphate, no change in fructose 6-phosphate and 42% decrease in lactate compared to levels in brains obtained from conscious animals. These results are discussed in relation to control of glycolysis through coupled regulation at hexokinase-phosphofructokinase.

  9. Temporal variations in 13C and 14C concentrations in particulate organic matter from the southern North Sea

    NASA Astrophysics Data System (ADS)

    Megens, L.; van der Plicht, J.; de Leeuw, J. W.

    2001-09-01

    As a new approach for the characterization and determination of the origin of particulate organic matter (POM) in coastal waters, we measured the 14C activity and 13C/ 12C isotope ratios and applied molecular analysis by means of AMS, IRMS and pyrolysis-GCMS for both bulk samples and isolated fractions of POM from the North Sea off the Dutch coast. The fractions were obtained by a sequence of chemical treatments separating polysaccharides, proteins, lipids and non-hydrolysable resistant compounds. The 13C/ 12C and 14C/ 12C isotope ratios, the 14C activities and the polysaccharide/protein contents were high in the spring and summer samples and significantly lower in the autumn and winter samples. This is explained by the high amount of marine phytoplankton in summer and spring, and the presence of detrital material in autumn and winter. It was noted that phytoplankton as found in the spring and summer samples was ca. 20% enriched in 14C with respect to natural values, very likely caused by 14C contamination of the water from the English Channel by the nuclear fuel reprocessing plant at La Hague, Normandy, France. The 13C/ 12C isotope ratios and 14C activity data show that the winter sample was not a simple mixture of relatively recent marine phytoplankton and POM from the rivers Rhine and Meuse. The main source of both terrestrial and marine organic matter in POM in winter is resuspended organic matter derived from eroded sea floor deposits with relatively low contributions of polysaccharides and proteins.

  10. DISTRIBUTION OF 14C-ATRAZINE FOLLOWING AN ACUTE LACTATIONAL EXPOSURE IN THE WISTAR RAT.

    EPA Science Inventory

    The purpose of the present study was to examine the distribution of atrazine in the lactating dam and suckling neonate following an acute exposure to either 2 or 4 mg/kg 14C-atrazine (14C-ATR) by gavage. 14C-ATR was administered to the nursing dam on postnatal day 3 by oral gavag...

  11. Effects of Pseudomonas species on the release of bound sup 14 C residues from soil treated with ( sup 14 C)atrazine

    SciTech Connect

    Khan, S.U.; Behki, R.M. )

    1990-11-01

    The release of bound (nonextractable) {sup 14}C residues from soil previously treated with ({sup 14}C)atrazine was investigated by incubation of the solvent-extracted soil with two species of Pseudomonas capable of metabolizing atrazine. The two species, 192 and 194, released bound {sup 14}C residues from the soil. Addition of glucose, known to increase microbiological activities, to the incubated soil appeared to enhance the release of soil-bound {sup 14}C residues, in particular in the presence of Pseudomonas species 192. The {sup 14}C bound residues in soil, mainly present as the parent compound and its hydroxy and monodealkylated analogues, were released into the incubation mixture and were subsequently metabolized by the two species involving dechlorination and dealkylation.

  12. The use of hair as an indicator of occupational 14C contamination.

    PubMed

    Stenström, Kristina; Unkel, Ingmar; Nilsson, Carl Magnus; Rääf, Christopher; Mattsson, Sören

    2010-03-01

    This paper presents a study in which the specific activity of (14)C in hair has been investigated as an easily determined bio-indicator of the integrated (14)C exposure (over several months). The study includes 28 Swedish workers handling (14)C-labelled compounds, or working in a (14)C-enriched environment. Hair samples from personnel at a Swedish nuclear power plant showed very low levels of (14)C contamination, if any. In contrast, personnel at the investigated research departments showed (14)C levels in hair of up to 60% above the natural specific activity of (14)C. Much higher levels, up to 80 times the natural specific activity of (14)C, were found in hair from individuals working at a pharmaceutical research laboratory. This contamination was, however, not solely an internal contamination. There were indications that most of the (14)C in the hair originated from airborne (14)C-compounds, which were adsorbed onto the hair. The difficulties in removing this external (14)C contamination prior to analysis are discussed, as are the possibilities of using accelerator mass spectrometry to analyse various types of samples for retrospective dose assessment.

  13. Percutaneous absorption of [14C]chlordane from soil.

    PubMed

    Wester, R C; Maibach, H I; Sedik, L; Melendres, J; Liao, C L; DiZio, S

    1992-04-01

    The objective was to determine percutaneous absorption of chlordane in vitro and in vivo from soil into and through skin. The data are needed to calculate the absorbed dose of chlordane from soil, which is then used to assess the toxicity risk. Chlordane, an insecticide for which residues exist in soil, is restricted currently to use for termite control. Chlordane is highly lipophilic with little or no movement out of soil. Soil (Yolo County 65-California-57-8; 26% sand, 26% clay, 48% silt, 0.9% organic) was passed through 10-, 20-, and 48-mesh sieves. Soil then retained by 80-mesh was mixed with 14C-labeled chemical at 67 ppm. Acetone solutions were prepared for comparative analysis. Human cadaver skin was dermatomed to 500 microns and used in glass diffusion cells with human plasma as the receptor fluid (3 ml/h flow rate) for a 24-h skin application time. Chlordane concentration within skin from in vitro studies was 0.34 +/- 0.31% from soil and 10.8 +/- 8.2% from acetone vehicle (p less than .01). Individual variation from human skin sources was evident (p less than .008). Chlordane accumulation in human plasma receptor fluid was the same for soil (0.04 +/- 0.05%) and acetone (0.07% +/- 0.06%) formulations. Most of the remaining chlordane was recovered in the soap and water skin surface wash. In contrast, in vivo percutaneous absorption of chlordane in the rhesus monkey was the same for soil (4.2 +/- 1.8%) and acetone (6.0 +/- 2.8%) formulations (p = .29, nonsignificant). Multiple soap and water washings were necessary to remove chlordane from skin, suggesting that a single wash may not adequately remove all the chlordane. PMID:1578510

  14. Percutaneous absorption of [14C]chlordane from soil.

    PubMed

    Wester, R C; Maibach, H I; Sedik, L; Melendres, J; Liao, C L; DiZio, S

    1992-04-01

    The objective was to determine percutaneous absorption of chlordane in vitro and in vivo from soil into and through skin. The data are needed to calculate the absorbed dose of chlordane from soil, which is then used to assess the toxicity risk. Chlordane, an insecticide for which residues exist in soil, is restricted currently to use for termite control. Chlordane is highly lipophilic with little or no movement out of soil. Soil (Yolo County 65-California-57-8; 26% sand, 26% clay, 48% silt, 0.9% organic) was passed through 10-, 20-, and 48-mesh sieves. Soil then retained by 80-mesh was mixed with 14C-labeled chemical at 67 ppm. Acetone solutions were prepared for comparative analysis. Human cadaver skin was dermatomed to 500 microns and used in glass diffusion cells with human plasma as the receptor fluid (3 ml/h flow rate) for a 24-h skin application time. Chlordane concentration within skin from in vitro studies was 0.34 +/- 0.31% from soil and 10.8 +/- 8.2% from acetone vehicle (p less than .01). Individual variation from human skin sources was evident (p less than .008). Chlordane accumulation in human plasma receptor fluid was the same for soil (0.04 +/- 0.05%) and acetone (0.07% +/- 0.06%) formulations. Most of the remaining chlordane was recovered in the soap and water skin surface wash. In contrast, in vivo percutaneous absorption of chlordane in the rhesus monkey was the same for soil (4.2 +/- 1.8%) and acetone (6.0 +/- 2.8%) formulations (p = .29, nonsignificant). Multiple soap and water washings were necessary to remove chlordane from skin, suggesting that a single wash may not adequately remove all the chlordane.

  15. Insights from 14C into C loss pathways in degraded peatlands

    NASA Astrophysics Data System (ADS)

    Evans, Martin; Evans, Chris; Allott, Tim; Stimson, Andrew; Goulsbra, Claire

    2016-04-01

    Peatlands are important global stores of terrestrial carbon. Lowered water tables due to changing climate and direct or indirect human intervention produce a deeper aerobic zone and have the potential to enhance loss of stored carbon from the peat profile. The quasi continuous accumulation of organic matter in active peatlands means that the age of fluvial dissolved organic carbon exported from peatland systems is related to the source depth in the peat profile. Consequently 14C analysis of DOC in waters draining peatlands has the potential not only to tell us about the source of fluvial carbon and the stability of the peatland but also about the dominant hydrological pathways in the peatland system. This paper will present new radiocarbon determinations from peatland streams draining the heavily eroded peatlands of the southern Pennine uplands in the UK. These blanket peatland systems are highly degraded, with extensive bare peat and gully erosion resulting from air pollution during the industrial revolution, overgrazing, wildfire and climatic changes. Deep and extensive gullying has significantly modified the hydrology of these systems leading to local and more widespread drawdown of water table. 14C data from DOC in drainage waters are presented from two catchments; one with extensive gully erosion and the other with a combination of gully erosion and sheet erosion of the peat. At the gully eroded site DOC in drainage waters is as old as 160 BP but at the site with extensive sheet erosion dates of up to 1069 BP are amongst the oldest recorded from blanket peatland globally These data indicate significant degradation of stored carbon from the eroding peatlands. Initial comparisons of the 14C data with modelled water table for the catchments and depth-age curves for catchment peats suggests that erosion of the peat surface, allowing decomposition of exposed older organic material is a potential mechanism producing aged carbon from the eroded catchment. This

  16. Determining the biomass fraction of mixed waste fuels: A comparison of existing industry and {sup 14}C-based methodologies

    SciTech Connect

    Muir, G.K.P.; Hayward, S.; Tripney, B.G.; Cook, G.T.; Naysmith, P.; Herbert, B.M.J.; Garnett, M.H; Wilkinson, M.

    2015-01-15

    Highlights: • Compares industry standard and {sup 14}C methods for determining bioenergy content of MSW. • Differences quantified through study at an operational energy from waste plant. • Manual sort and selective dissolution are unreliable measures of feedstock bioenergy. • {sup 14}C methods (esp. AMS) improve precision and reliability of bioenergy determination. • Implications for electricity generators and regulators for award of bio-incentives. - Abstract: {sup 14}C analysis of flue gas by accelerator mass spectrometry (AMS) and liquid scintillation counting (LSC) were used to determine the biomass fraction of mixed waste at an operational energy-from-waste (EfW) plant. Results were converted to bioenergy (% total) using mathematical algorithms and assessed against existing industry methodologies which involve manual sorting and selective dissolution (SD) of feedstock. Simultaneous determinations using flue gas showed excellent agreement: 44.8 ± 2.7% for AMS and 44.6 ± 12.3% for LSC. Comparable bioenergy results were obtained using a feedstock manual sort procedure (41.4%), whilst a procedure based on selective dissolution of representative waste material is reported as 75.5% (no errors quoted). {sup 14}C techniques present significant advantages in data acquisition, precision and reliability for both electricity generator and industry regulator.

  17. A Novel 14C-Postlabeling Assay Using Accelerator Mass Spectrometry For the Detection of O6-Methyldeoxyguanosine Adducts

    SciTech Connect

    Thompkins, E M; Farmer, P B; Lamb, J H; Jukes, R; Dingley, K; Ubick, E A; Turteltaub, K W; Martin, E A; Brown, K

    2005-11-17

    Accelerator mass spectrometry (AMS) is currently one of the most sensitive methods available for the trace detection of DNA adducts and is particularly valuable for measuring adducts in humans or animal models. However, the standard approach requires administration of a radiolabeled compound. As an alternative, we have developed a preliminary {sup 14}C-postlabeling assay for detection of the highly mutagenic O{sup 6}-MedG, by AMS. Procedures were developed for derivatizing O{sup 6}-MedG using unlabeled acetic anhydride. Using conventional LC-MS analysis, the limit of detection for the major product, triacetylated O{sup 6}-MedG, was 10 fmoles. On reaction with {sup 14}C-acetic anhydride, using a specially designed enclosed system, the predominant product was {sup 14}C-di-acetyl O{sup 6}-MedG. This change in reaction profile was due to a modification of the reaction procedure, introduced as a necessary safety precaution. The limit of detection for {sup 14}C-diacetyl O{sup 6}-MedG by AMS was determined as 79 attomoles, {approx}18,000 fold lower than that achievable by LSC. Although the assay has so far only been carried out with labeled standards, the degree of sensitivity obtained illustrates the potential of this assay for measuring O{sup 6}-MedG levels in humans.

  18. Radiocarbon dating of charred human bone remains preserved in urns excavated from medieval Buddhist cemetery in Japan

    NASA Astrophysics Data System (ADS)

    Nakamura, Toshio; Sagawa, Shinichi; Yamada, Tetsuya; Kanehara, Masaaki; Tsuchimoto, Norio; Minami, Masayo; Omori, Takayuki; Okuno, Mitsuru; Ohta, Tomoko

    2010-04-01

    For a preliminary test of 14C dating of cremated human remains, we have collected charred bone and wood-charcoal fragments from cremated remains contained in cinerary urns that had been excavated from medieval Buddhist cemetery at the Hoenji temple in Aichi prefecture, central Japan. More than 230 urn vessels were discovered from the excavated area of ca. 14 m wide and 14 m long. The identification of charred bone or charcoal fragments among the remains was performed by observation of surface appearance, inspection of fine structures by a microscope, bubble formation during the HCl treatments in preparing target material for AMS 14C dating, carbon and nitrogen contents, δ13C and δ15N values of the fragments. All 14C ages obtained for the samples that were identified as charred bone remains were almost consistent with the archeological age estimated based on typological analysis of respective urns. On the other hand, some 14C ages for the remains identified as wood charcoal, which had been produced from firewood or a wooden coffin during the cremation, were not consistent with archeological estimation, shifting toward older 14C ages, most probably as the result of old wood effect.

  19. Metabolism of ( sup 14 C)cholesterol to C-20 isomeric ( sup 14 C)pregn-5-ene-3,20-diols in the tobacco hornworm, Manduca sexta

    SciTech Connect

    Lozano, R.; Thompson, M.J.; Svoboda, J.A.; Lusby, W.R.; Wilzer, K.R. Jr. )

    1989-03-01

    After injection into male and female fifth-instar larvae of Manduca sexta, ({sup 14}C)cholesterol was converted to C21 steroids, ({sup 14}C)pregn-5-ene-3 beta,20-diols. These metabolites were isolated from 8-day-old pupae and were identified by TLC, HPLC, and GC-MS as the C-20 isomers of pregnene-3 beta,20-diol. They also were isolated from male and female meconium fluid (of 16-day-old pupae) following injection of ({sup 14}C)cholesterol into 14-day-old pupae.

  20. Radiocarbon dating using electrostatic accelerators: negative ions provide the key.

    PubMed

    Bennett, C L; Beukens, R P; Clover, M R; Gove, H E; Liebert, R B; Litherland, A E; Purser, K H; Sondheim, W E

    1977-11-01

    Mass spectrometric methods have long been suggested as ways of measuring (14)C/(12)C ratios for carbon dating. One problem has been to distinguish between (14)N and (14)C. With negative ions and a tandem electrostatic accelerator, the (14)N background is virtually absent and fewer than three (14)C atoms in 10(16) atoms of (12)C have been easily measured.

  1. Semi-synthetic preparation of 1-O-(1'-/sup 14/C)hexadecyl-2-acetyl-sn-glycero-3-phosphocholine (platelet activating factor) using plant cell cultures

    SciTech Connect

    Weber, N.; Mangold, H.K.

    1985-04-01

    Incubation of photomixotrophic cell suspension cultures of rape (Brassica napus) and heterotrophic cell suspension cultures of soya (Glycine max) with 1-O-(1'-/sup 14/C)hexadecyl-sn-glycerol or rac-1-O-(1'-/sup 14/C)hexadecylglycerol leads in high yield (up to 78%) to labeled 1-O-hexadecyl-2-acyl-sn-glycero-3-phosphocholines. Alkaline hydrolysis of the choline glycerophospholipids yields pure 1-O-(1'-/sup 14/C)hexadecyl-sn-glycero-3-phosphocholine. 1-O-(1'-14C)Hexadecyl-2-acetyl-sn-glycero-3-phosphocholine (platelet activating factor) is obtained by acetylating the lyso compound. The semi-synthetic preparation described leads to labeled platelet activating factor in an overall yield of 50-60% without loss of specific activity.

  2. 14C/C measurements support Andreev's internode method to determine lichen growth rates in Cladina stygia (Fr.) Ahti

    SciTech Connect

    Holt, E; Bench, G

    2007-12-05

    Growth rates and the ability to date an organism can greatly contribute to understanding its population biology and community dynamics. 1n 1954, Andreev proposed a method to date Cladina, a fruticose lichen, using total thallus length and number of internodes. No research, however, has demonstrated the reliability of this technique or compared its estimates to those derived by other means. In this study, we demonstrate the utility of {sup 14}C/C ratios to determine lichen age and growth rate in Cladina stygia (Fr.) Ahti collected from northwestern Alaska, USA. The average growth rate using {sup 14}C/C ratios was 6.5 mm {center_dot} yr{sup -1}, which was not significantly different from growth rates derived by Andreev's internode method (average = 6.2 mm {center_dot} yr{sup -1}); thus, suggesting the reliability of Andreev's simple field method for dating lichens. In addition, we found lichen growth rates appeared to differ with geographic location, yet did not seem related to ambient temperature and total precipitation.

  3. Threshold groundwater ages and young water fractions estimated from 3H, 3He, and 14C

    NASA Astrophysics Data System (ADS)

    Kirchner, James; Jasechko, Scott

    2016-04-01

    It is widely recognized that a water sample taken from a running stream is not described by a single age, but rather by a distribution of ages. It is less widely recognized that the same principle holds true for groundwaters, as indicated by the commonly observed discordances between model ages obtained from different tracers (e.g., 3H vs 14C) in the same sample. Water age distributions are often characterized by their mean residence times (MRT's). However, MRT estimates are highly uncertain because they depend on the shape of the assumed residence time distribution (in particular on the thickness of the long-time tail), which is difficult or impossible to constrain with data. Furthermore, because MRT's are typically nonlinear functions of age tracer concentrations, they are subject to aggregation bias. That is, MRT estimates derived from a mixture of waters with different ages (and thus different tracer concentrations) will systematically underestimate the mixture's true mean age. Here, building on recent work with stable isotope tracers in surface waters [1-3], we present a new framework for using 3H, 3He and 14C to characterize groundwater age distributions. Rather than describing groundwater age distributions by their MRT, we characterize them by the fraction of the distribution that is younger or older than a threshold age. The threshold age that separates "young" from "old" water depends on the characteristics of the specific tracer, including its history of atmospheric inputs. Our approach depends only on whether a given slice of the age distribution is younger or older than the threshold age, but not on how much younger or older it is. Thus our approach is insensitive to the tails of the age distribution, and is therefore relatively unaffected by uncertainty in the distribution's shape. Here we show that concentrations of 3H, 3He, and 14C are almost linearly related to the fractions of water that are younger or older than specified threshold ages. These

  4. 14C content in vegetation in the vicinities of Brazilian nuclear power reactors.

    PubMed

    Dias, Cíntia Melazo; Santos, Roberto Ventura; Stenström, Kristina; Nícoli, Iêda Gomes; Skog, Göran; da Silveira Corrêa, Rosangela

    2008-07-01

    (14)C specific activities were measured in grass samples collected around Brazilian nuclear power reactors. The specific activity values varied between 227 and 299 Bq/kg C. Except for two samples which showed (14)C specific activities 22% above background values, half of the samples showed background specific activities, and the other half had a (14)C excess of 1-18%. The highest specific activities were found close to the nuclear power plants and along the main wind directions (NE and NNE). The activity values were found to decrease with increasing distance from the reactors. The unexpectedly high (14)C excess values found in two samples were related to the local topography, which favors (14)C accumulation and limits the dispersion of the plume. The results indicate a clear (14)C anthropogenic signal within 5 km around the nuclear power plants which is most prominent along northeastwards, the prevailing wind direction.

  5. Atmospheric 14C variations derived from tree rings during the early Younger Dryas

    NASA Astrophysics Data System (ADS)

    Hua, Quan; Barbetti, Mike; Fink, David; Kaiser, Klaus Felix; Friedrich, Michael; Kromer, Bernd; Levchenko, Vladimir A.; Zoppi, Ugo; Smith, Andrew M.; Bertuch, Fiona

    2009-12-01

    Atmospheric radiocarbon variations over the Younger Dryas interval, from ˜13,000 to 11,600 cal yr BP, are of immense scientific interest because they reveal crucial information about the linkages between climate, ocean circulation and the carbon cycle. However, no direct and reliable atmospheric 14C records based on tree rings for the entire Younger Dryas have been available. In this paper, we present (1) high-precision 14C measurements on the extension of absolute tree-ring chronology from 12,400 to 12,560 cal yr BP and (2) high-precision, high-resolution atmospheric 14C record derived from a 617-yr-long tree-ring chronology of Huon pine from Tasmania, Australia, spanning the early Younger Dryas. The new tree-ring 14C records bridge the current gap in European tree-ring radiocarbon chronologies during the early Younger Dryas, linking the floating Lateglacial Pine record to the absolute tree-ring timescale. A continuous and reliable atmospheric 14C record for the past 14,000 cal yr BP including the Younger Dryas is now available. The new records indicate that the abrupt rise in atmospheric Δ 14C associated with the Younger Dryas onset occurs at ˜12,760 cal yr BP, ˜240 yrs later than that recorded in Cariaco varves, with a smaller magnitude of ˜40‰ followed by several centennial Δ 14C variations of 20-25‰. Comparing the tree-ring Δ 14C to marine-derived Δ 14C and modelled Δ 14C based on ice-core 10Be fluxes, we conclude that changes in ocean circulation were mainly responsible for the Younger Dryas onset, while a combination of changes in ocean circulation and 14C production rate were responsible for atmospheric Δ 14C variations for the remainder of the Younger Dryas.

  6. Distribution of 14C-atrazine following an acute lactational exposure in the Wistar rat.

    PubMed

    Stoker, Tammy E; Cooper, Ralph L

    2007-06-01

    The purpose of the present study was to examine the distribution of atrazine in the lactating dam and suckling neonate following an acute exposure to either 2 or 4mg/kg 14C-atrazine (14C-ATR) by gavage. 14C-ATR was administered to the nursing dam on postnatal day 3 by oral gavage. Two and a half hours after exposure of the mother to 14C-ATR, the pups were allowed to nurse for 30min. At the end of the nursing period, radiolabelled residues of 14C-ATR [or 14C-chlorotriazines (14C-ClTRI)] were measured in the organs and tissues of the perfused dam and in the stomachs and brains of the rat pups. Both the 2 and the 4mg atrazine treatments resulted in a transfer of approximately 0.007% of 14C-ClTRI to the stomach (indicator of milk content) and 0.0002% to the brains of the offspring following the 30-min nursing period. Three hours following the dose of 14C-ATR, there was a distribution of 14C-ClTRI to the organs of the dam, with the highest amounts in the liver and kidney (1.1 and 0.3% of the administered dose, respectively). Approximately 0.003% of the administered dose was present in three different brain sections of the dam following both doses of 14C-ATR. The results of this study demonstrate that 14C-ClTRI are present in small concentrations in the brain and tissues of the dam (adult female) and provide evidence that atrazine or the metabolites can have direct effects on neuroendrocrine function. The results also provide information for postnatal distribution into the suckling neonate during early lactation.

  7. (/sup 14/C)chloroacetylcholine as an advantageous affinity label of the acetylcholine receptor

    SciTech Connect

    Bodmer, D.M.; Sin-Ren, A.C.; Waser, P.G.

    1987-01-01

    The alkylating agent (/sup 14/C)chloroacetylcholine perchlorate ((/sup 14/C) ClACh) was synthesized and used for affinity labelling of the nicotinic acetylcholine receptor from Torpedo marmorata. Solubilized and affinity-purified receptor proteins were reduced and alkylated according to the bromoacetylcholine-method. Covalent binding of (/sup 14/C) ClACh to the cholinergic receptor proved to be specific and saturable, and occurred exclusively to the alpha-subunit. Halogen substitution of acetylcholine by chlorine and insertion of a /sup 14/C-isotope instead of the widely used /sup 3/H resulted in favorable properties of the affinity label.

  8. 87Sr/86Sr as a quantitative geochemical proxy for 14C reservoir age in dynamic, brackish waters: Assessing applicability and quantifying uncertainties

    NASA Astrophysics Data System (ADS)

    Lougheed, Bryan C.; Lubbe, H. J. L.; Davies, Gareth R.

    2016-01-01

    Accurate geochronologies are crucial for reconstructing the sensitivity of brackish and estuarine environments to dynamic external impacts of the past. Radiocarbon (14C) dating is commonly used for palaeoclimate studies, but its application in brackish environments is severely limited by an inability to quantify spatiotemporal variations in 14C reservoir age, or R(t), due to dynamic interplay between river runoff and marine water. Additionally, old carbon effects and species-specific behavioral processes also influence 14C ages. Using the world's largest brackish water body (the estuarine Baltic Sea) as a test bed, combined with a comprehensive approach that objectively excludes both old carbon (using GIS) and species-specific 14C effects, we demonstrate the use of 87Sr/86Sr ratios for quantifying R(t) in ubiquitous mollusc shell material, leading to almost an order of magnitude increase in Baltic Sea 14C geochronological precision over the current state of the art. We propose that similar proxy methods can be developed for other brackish water bodies worldwide.

  9. Determining the biomass fraction of mixed waste fuels: A comparison of existing industry and (14)C-based methodologies.

    PubMed

    Muir, G K P; Hayward, S; Tripney, B G; Cook, G T; Naysmith, P; Herbert, B M J; Garnett, M H; Wilkinson, M

    2015-01-01

    (14)C analysis of flue gas by accelerator mass spectrometry (AMS) and liquid scintillation counting (LSC) were used to determine the biomass fraction of mixed waste at an operational energy-from-waste (EfW) plant. Results were converted to bioenergy (% total) using mathematical algorithms and assessed against existing industry methodologies which involve manual sorting and selective dissolution (SD) of feedstock. Simultaneous determinations using flue gas showed excellent agreement: 44.8 ± 2.7% for AMS and 44.6 ± 12.3% for LSC. Comparable bioenergy results were obtained using a feedstock manual sort procedure (41.4%), whilst a procedure based on selective dissolution of representative waste material is reported as 75.5% (no errors quoted). (14)C techniques present significant advantages in data acquisition, precision and reliability for both electricity generator and industry regulator.

  10. Structure of 14C and 14B from the C,1514(d ,3He)B,1413 reactions

    NASA Astrophysics Data System (ADS)

    Bedoor, S.; Wuosmaa, A. H.; Albers, M.; Alcorta, M.; Almaraz-Calderon, Sergio; Back, B. B.; Bertone, P. F.; Deibel, C. M.; Hoffman, C. R.; Lighthall, J. C.; Marley, S. T.; Mcneel, D. G.; Pardo, R. C.; Rehm, K. E.; Schiffer, J. P.; Shetty, D. V.

    2016-04-01

    We have studied the C,1514(d ,3He)B,1413 proton-removing reactions in inverse kinematics. The (d ,3He ) reaction probes the proton occupation of the target ground state, and also provides spectroscopic information about the final states in B,1413. The experiments were performed using C,1514 beams from the ATLAS accelerator at Argonne National Laboratory. The reaction products were analyzed with the HELIOS device. Angular distributions were obtained for transitions from both reactions. The 14C-beam data reveal transitions to excited states in 13B that suggest configurations with protons outside the π (0 p3 /2) orbital, and some possibility of proton cross-shell 0 p -1 s 0 d excitations, in the 14C ground state. The 15C-beam data confirm the existence of a broad 2- excited state in 14B. The experimental data are compared to the results of shell-model calculations.

  11. Using Methane 14C to Determine the Origin of the Rapid Methane Rise at the End of the Younger Dryas 11,600 Years Ago: Increased Wetland Production or Methane Hydrates? A Progress Report.

    NASA Astrophysics Data System (ADS)

    Petrenko, V. V.; Severinghaus, J.; Brook, E.; Reeh, N.

    2002-12-01

    The atmospheric methane concentration rose from about 500 parts per billion (ppb) to about 750 ppb over a period of just 150 years at the termination of the Younger Dryas cold period 11,600 years ago, as indicated by Greenland ice core records. The start of this rapid methane increase was synchronous with an even more rapid climate warming -- Greenland ice core nitrogen and argon isotope records indicate that temperatures rose 5 - 10 ?C over just a few decades. There has been considerable debate about the source of this methane rise. Currently, the two main hypotheses attribute the methane rise either to increased bacterial methane production in wetlands, or to the dissociation of large quantities of methane hydrates on the ocean floor. Here we describe the progress of a project whose aim is to determine the origin of this methane rise. Our approach involves using 14C of ancient methane (derived from air bubbles in glacial ice) to determine its source. Methane hydrates are hundreds of thousands to millions of years old, and should contain virtually no 14C, whereas wetland-derived methane will have 14C content identical to that of atmospheric CO2 at the time of production. Obtaining enough ancient methane for a 14C measurement requires very large samples -- about 2 cubic meters. We have been able to locate a site on the western margin of the Greenland ice sheet where large amounts of uncontaminated ancient ice are available at the surface. Furthermore, our measurements of oxygen isotopes in the ice, as well as measurements of methane and oxygen and nitrogen isotopes in the air trapped in this ice have allowed us to date the ice and precisely locate the ice that contains the end-of-Younger-Dryas methane increase signal. Our data also demonstrate that the methane record in this ice is uncontaminated and suitable for methane 14C analysis. During the past year, we also constructed and are testing a device for melting and extracting air from large volumes of glacial ice.

  12. Constraints on the sedimentation history of San Francisco Bay from 14C and 10Be

    USGS Publications Warehouse

    VanGeen, A.; Valette-Silver, N. J.; Luoma, S.N.; Fuller, C.C.; Baskaran, M.; Tera, F.; Klein, J.

    1999-01-01

    Industrialization and urbanization around San Francisco Bay as well as mining and agriculture in the watersheds of the Sacramento and San Joaquin rivers have profoundly modified sedimentation patterns throughout the estuary. We provide some constraints on the onset of these erosional disturbances with 10Be data for three sediment cores: two from Richardson Bay, a small embayment near the mouth of San Francisco Bay, and one from San Pablo Bay, mid-way between the river delta and the mouth. Comparison of pre-disturbance sediment accumulation determined from three 14C-dated mollusk shells in one Richardson Bay core with more recent conditions determined from the distribution of 210Pb and 234Th [Fuller, C.C., van Geen, A., Baskaran, M, Anima, R.J., 1999. Sediment chronology in San Francisco Bay, California, defined by 210Pb, 234Th, 239,240Pu.] shows that the accumulation rate increased by an order of magnitude at this particular site. All three cores from San Francisco Bay show subsurface maxima in 10Be concentrations ranging in magnitude from 170 to 520 x 106 atoms/g. The transient nature of the increased 10Be input suggests that deforestation and agricultural develop- ment caused basin-wide erosion of surface soils enriched in 10Be. probably before the turn of the century.

  13. Free flow electrophoresis separation and AMS quantitation of 14C-naphthalene-protein adducts

    PubMed Central

    Buchholz, Bruce A.; Haack, Kurt W.; Sporty, Jennifer L.; Buckpitt, Alan R.; Morin, Dexter

    2009-01-01

    Naphthalene is a volatile aromatic hydrocarbon to which humans are exposed from a variety of sources including mobile air sources and cigarette smoke. Naphthalene produces dose- (concentration) dependent injury to airway epithelial cells of murine lung which is observed at concentrations well below the current occupational exposure standard. Toxicity is dependent upon the cytochrome P450 mediated metabolic activation of the parent substrate to unstable metabolites which become bound covalently to tissue proteins. Nearly 70 proteins have been identified as forming adducts with reactive naphthalene metabolites using in vitro systems but very little work has been conducted in vivo because reasonably large amounts (100 μCi) of 14C labeled parent compound must be administered to generate detectable adduct levels on storage phosphor screens following separation of labeled proteins by 2 D gel electrophoresis. The work described here was done to provide proof of concept that protein separation by free flow electrophoresis followed by AMS detection of protein fractions containing protein bound reactive metabolites would provide adducted protein profiles in animals dosed with trace quantities of labeled naphthalene. Mice were administered 200 mg/kg naphthalene intraperitoneally at a calculated specific activity of 2 DPM/nmol (1 pCi/nmol) and respiratory epithelial tissue was obtained by lysis lavage 4 hr post injection. Free flow electrophoresis (FFE) separates proteins in the liquid phase over a large pH range (2.5–11.5) using low molecular weight acids and bases to modify the pH. The apparatus separates fractions into standard 96-well plates that can be used in other protein analysis techniques. The buffers of the fractions have very high carbon content, however, and need to be dialyzed to yield buffers compatible with 14C-AMS. We describe the processing techniques required to couple FFE to AMS for quantitation of protein adducts. PMID:20454606

  14. Refined masses and distance of the young binary Haro 1-14 C

    NASA Astrophysics Data System (ADS)

    Le Bouquin, J.-B.; Monin, J.-L.; Berger, J.-P.; Prato, L.; Benisty, M.; Schaefer, G.

    2014-01-01

    Aims: We aim to refine the dynamical masses of the individual component of the low-mass pre-main sequence binary Haro 1-14C. Methods: We combine the data of the preliminary orbit presented previously with new interferometric observations obtained with the four 8 m telescopes of the Very Large Telescope Interferometer. Results: The derived masses are Ma = 0.905 ± 0.043 M⊙ and Mb = 0.308 ± 0.011 M⊙ for the primary and secondary components, respectively. This is about five times better than the uncertainties of the preliminary orbit. Moreover, the possibility of larger masses is now securely discarded. The new dynamical distance, d = 96 ± 9 pc, is smaller than the distance to the Ophiuchus core with a significance of 2.6σ. Fitting the spectral energy distribution yields apparent diameters of φa = 0.13 ± 0.01 mas and φb = 0.10 ± 0.01 mas (corresponding to Ra = 1.50 R⊙ and Rb = 1.13 R⊙) and a visual extinction of Av ≈ 1.75. Although the revised orbit has a nearly edge-on geometry, the system is unlikely to be a long-period eclipsing binary. Conclusions: The secondary in Haro 1-14C is one of the few low-mass, pre-main sequence stars with an accurately determined dynamical mass and distance. Based on observations collected under program 091.C-0093(A) with the PIONIER/VLTI instrument at the European Southern Observatory, Paranal, Chile.

  15. Free flow electrophoresis separation and AMS quantitation of 14C-naphthalene-protein adducts

    NASA Astrophysics Data System (ADS)

    Buchholz, Bruce A.; Haack, Kurt W.; Sporty, Jennifer L.; Buckpitt, Alan R.; Morin, Dexter

    2010-04-01

    Naphthalene is a volatile aromatic hydrocarbon to which humans are exposed from a variety of sources including mobile air sources and cigarette smoke. Naphthalene produces dose-(concentration)dependent injury to airway epithelial cells of murine lung which is observed at concentrations well below the current occupational exposure standard. Toxicity is dependent upon the cytochrome P450 mediated metabolic activation of the parent substrate to unstable metabolites which become bound covalently to tissue proteins. Nearly 70 proteins have been identified as forming adducts with reactive naphthalene metabolites using in vitro systems but very little work has been conducted in vivo because reasonably large amounts (100 μCi) of 14C labeled parent compound must be administered to generate detectable adduct levels on storage phosphor screens following separation of labeled proteins by 2D gel electrophoresis. The work described here was done to provide proof of concept that protein separation by free flow electrophoresis followed by AMS detection of protein fractions containing protein bound reactive metabolites would provide adducted protein profiles in animals dosed with trace quantities of labeled naphthalene. Mice were administered 200 mg/kg naphthalene intraperitoneally at a calculated specific activity of 2 DPM/nmol (1 pCi/nmol) and respiratory epithelial tissue was obtained by lysis lavage 4 h post injection. Free flow electrophoresis (FFE) separates proteins in the liquid phase over a large pH range (2.5-11.5) using low molecular weight acids and bases to modify the pH. The apparatus separates fractions into standard 96-well plates that can be used in other protein analysis techniques. The buffers of the fractions have very high carbon content, however, and need to be dialyzed to yield buffers compatible with 14C-AMS. We describe the processing techniques required to couple FFE to AMS for quantitation of protein adducts.

  16. Collagen Fingerprinting: A New Screening Technique for Radiocarbon Dating Ancient Bone.

    PubMed

    Harvey, Virginia L; Egerton, Victoria M; Chamberlain, Andrew T; Manning, Phillip L; Buckley, Michael

    2016-01-01

    Collagen is the dominant organic component of bone and is intimately locked within the hydroxyapatite structure of this ubiquitous biomaterial that dominates archaeological and palaeontological assemblages. Radiocarbon analysis of extracted collagen is one of the most common approaches to dating bone from late Pleistocene or Holocene deposits, but dating is relatively expensive compared to other biochemical techniques. Numerous analytical methods have previously been investigated for the purpose of screening out samples that are unlikely to yield reliable dates including histological analysis, UV-stimulated fluorescence and, most commonly, the measurement of percentage nitrogen (%N) and ratio of carbon to nitrogen (C:N). Here we propose the use of collagen fingerprinting (also known as Zooarchaeology by Mass Spectrometry, or ZooMS, when applied to species identification) as an alternative screening method for radiocarbon dating, due to its ability to provide information on collagen presence and quality, alongside species identification. The method was tested on a series of sub-fossil bone specimens from cave systems on Cayman Brac (Cayman Islands), chosen due to the observable range in diagenetic alteration, and in particular, the extent of mineralisation. Six (14)C dates, of 18 initial attempts, were obtained from remains of extinct hutia, Capromys sp. (Rodentia; Capromyidae), recovered from five distinct caves on Cayman Brac, and ranging from 393 ± 25 to 1588 ± 26 radiocarbon years before present (yr BP). All of the bone samples that yielded radiocarbon dates generated excellent collagen fingerprints, and conversely those that gave poor fingerprints also failed dating. Additionally, two successfully fingerprinted bone samples were screened out from a set of 81. Both subsequently generated (14)C dates, demonstrating successful utilisation of ZooMS as an alternative screening mechanism to identify bone samples that are suitable for 1(4)C analysis.

  17. Collagen Fingerprinting: A New Screening Technique for Radiocarbon Dating Ancient Bone

    PubMed Central

    Harvey, Virginia L.; Egerton, Victoria M.; Chamberlain, Andrew T.; Manning, Phillip L.; Buckley, Michael

    2016-01-01

    Collagen is the dominant organic component of bone and is intimately locked within the hydroxyapatite structure of this ubiquitous biomaterial that dominates archaeological and palaeontological assemblages. Radiocarbon analysis of extracted collagen is one of the most common approaches to dating bone from late Pleistocene or Holocene deposits, but dating is relatively expensive compared to other biochemical techniques. Numerous analytical methods have previously been investigated for the purpose of screening out samples that are unlikely to yield reliable dates including histological analysis, UV-stimulated fluorescence and, most commonly, the measurement of percentage nitrogen (%N) and ratio of carbon to nitrogen (C:N). Here we propose the use of collagen fingerprinting (also known as Zooarchaeology by Mass Spectrometry, or ZooMS, when applied to species identification) as an alternative screening method for radiocarbon dating, due to its ability to provide information on collagen presence and quality, alongside species identification. The method was tested on a series of sub-fossil bone specimens from cave systems on Cayman Brac (Cayman Islands), chosen due to the observable range in diagenetic alteration, and in particular, the extent of mineralisation. Six 14C dates, of 18 initial attempts, were obtained from remains of extinct hutia, Capromys sp. (Rodentia; Capromyidae), recovered from five distinct caves on Cayman Brac, and ranging from 393 ± 25 to 1588 ± 26 radiocarbon years before present (yr BP). All of the bone samples that yielded radiocarbon dates generated excellent collagen fingerprints, and conversely those that gave poor fingerprints also failed dating. Additionally, two successfully fingerprinted bone samples were screened out from a set of 81. Both subsequently generated 14C dates, demonstrating successful utilisation of ZooMS as an alternative screening mechanism to identify bone samples that are suitable for 14C analysis. PMID:26938469

  18. Collagen Fingerprinting: A New Screening Technique for Radiocarbon Dating Ancient Bone.

    PubMed

    Harvey, Virginia L; Egerton, Victoria M; Chamberlain, Andrew T; Manning, Phillip L; Buckley, Michael

    2016-01-01

    Collagen is the dominant organic component of bone and is intimately locked within the hydroxyapatite structure of this ubiquitous biomaterial that dominates archaeological and palaeontological assemblages. Radiocarbon analysis of extracted collagen is one of the most common approaches to dating bone from late Pleistocene or Holocene deposits, but dating is relatively expensive compared to other biochemical techniques. Numerous analytical methods have previously been investigated for the purpose of screening out samples that are unlikely to yield reliable dates including histological analysis, UV-stimulated fluorescence and, most commonly, the measurement of percentage nitrogen (%N) and ratio of carbon to nitrogen (C:N). Here we propose the use of collagen fingerprinting (also known as Zooarchaeology by Mass Spectrometry, or ZooMS, when applied to species identification) as an alternative screening method for radiocarbon dating, due to its ability to provide information on collagen presence and quality, alongside species identification. The method was tested on a series of sub-fossil bone specimens from cave systems on Cayman Brac (Cayman Islands), chosen due to the observable range in diagenetic alteration, and in particular, the extent of mineralisation. Six (14)C dates, of 18 initial attempts, were obtained from remains of extinct hutia, Capromys sp. (Rodentia; Capromyidae), recovered from five distinct caves on Cayman Brac, and ranging from 393 ± 25 to 1588 ± 26 radiocarbon years before present (yr BP). All of the bone samples that yielded radiocarbon dates generated excellent collagen fingerprints, and conversely those that gave poor fingerprints also failed dating. Additionally, two successfully fingerprinted bone samples were screened out from a set of 81. Both subsequently generated (14)C dates, demonstrating successful utilisation of ZooMS as an alternative screening mechanism to identify bone samples that are suitable for 1(4)C analysis. PMID:26938469

  19. Low energy cyclotron for radiocarbon dating

    SciTech Connect

    Welch, J.J.

    1985-01-01

    The author built and tested a low energy cyclotron for radiocarbon dating similar 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 /sup 14/C measurements that are now done at accelerator facilities. The author found that no significant background is present when the cyclotron is tuned to accelerate /sup 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 /sup 14/C directly at modern concentrations. The author shows how a conventional carbon negative ion source located outside the cyclotron magnet, would produce sufficient beam and provide for quick sample changing to make radiocarbon dating milligram samples with a modest laboratory instrument feasible.

  20. Dilute Nuclear States: {sup 12}C, {sup 10}Be and {sup 14}C

    SciTech Connect

    Freer, M.

    2008-11-11

    The experimental evidence for dilute {alpha}-particle states in {sup 12}C, {sup 10}Be and {sup 14}C is discussed. The question of the location of the 2{sup +} excitation of the 7.65 MeV {sup 12}C state remains unresolved, as does the existence of possible analogue states in {sup 14}C.

  1. Disposition of /sup 14/C tolrestat in laboratory animals and man

    SciTech Connect

    Ferdinandi, E.S.; Hicks, D.R.; Cayen, M.N.

    1986-03-01

    The disposition of the aldose reductase inhibitor tolrestat (T) was determined in the mouse, rat, dog, assemensis monkey, and man. Serum T and radioactivity ratios, and % of dose excreted after p.o. administration of /sup 14/C-T at a dose of 10 mk/kg (100 mg to man), are presented. Except for the rat and monkey, 55 to 95% of the urinary /sup 14/C was due to T and oxo-tolrestat (oxo-T, N-((5-(trifluoromethyl)-6-methoxy-1-napthalenyl)oxo-methyl)-N-methylglycine). Oxo-T is formed, in part, non-enzymatically from T; a potential intermediate in this transformation was detected in all the urine samples. In man and monkey, about 15% and 68%, respectively, of the urinary /sup 14/C was due to T-glucuronide. In rat urine, >90% of the /sup 14/C was due to polar metabolites; in bile, about 66% of the /sup 14/C was due to T. The composition of the serum /sup 14/C in the mouse and rat was determined. In conclusion, /sup 14/C-T was rapidly and well absorbed by all species. Except for the rat and dog, urine was the main excretion route for /sup 14/C. Urine/sup 14/ comprised mainly T, t-glucuronide of oxo-T in all the species except the rat.

  2. Soil metabolism of [14C]methiozolin under aerobic and anaerobic flooded conditions.

    PubMed

    Hwang, Ki-Hwan; Lim, Jong-Soo; Kim, Sung-Hun; Chang, Hee-Ra; Kim, Kyun; Koo, Suk-Jin; Kim, Jeong-Han

    2013-07-17

    Methiozolin is a new turf herbicide controlling annual bluegrass in various cool- and warm-season turfgrasses. This study was conducted to investigate the fate of methiozolin in soil under aerobic and anaerobic flooded conditions using two radiolabeled tracers, [benzyl-(14)C]- and [isoxazole-(14)C]methiozolin. The mass balance of applied radioactivity ranged from 91.7 to 104.5% in both soil conditions. In the soil under the aerobic condition, [(14)C]methiozolin degraded with time to remain by 17.9 and 15.9% of the applied in soil at 120 days after treatment (DAT). [(14)C]Carbon dioxide and the nonextractable radioactivity increased as the soil aged to reach up to 41.5 and 35.7% for [benzyl-(14)C]methiozolin at 120 DAT, respectively, but 36.1 and 39.8% for [isoxazole-(14)C]methiozolin, respectively, during the same period. The nonextractable residue was associated more with humin and fulvic acid fractions under the aerobic condition. No significant volatile products or metabolites were detected during this study. The half-life of [(14)C]methiozolin was approximately 49 days in the soil under the aerobic condition; however, it could not be estimated in the soil under the anaerobic flooded condition because [(14)C]methiozolin degradation was limited. On the basis of these results, methiozolin is considered to undergo fast degradation by aerobic microbes, but not by anaerobic microbes in soil. PMID:23772889

  3. Production of [14C]fumonisin B1 by Fusarium moniliforme MRC 826 in corn cultures.

    PubMed Central

    Alberts, J F; Gelderblom, W C; Vleggaar, R; Marasas, W F; Rheeder, J P

    1993-01-01

    Kinetics of growth and fumonisin production by Fusarium moniliforme MRC 826 in corn "patty" cultures were investigated, and a technique was developed for the production of [14C]fumonisin B1 ([14C]FB1) by using L-[methyl-14C]methionine as the precursor. A significant (P < 0.01) correlation exists between fungal growth and FB1 (r = 0.89) and FB2 (r = 0.87) production in corn patties, beginning after 2 days and reaching the stationary phase after 14 days of incubation. [14C]FB1 was produced by adding L-[methyl-14C]methionine daily to cultures during the logarithmic phase of production. Incorporation of the isotope occurred at C-21 and C-22 of the fumonism molecule and was enhanced in the presence of unlabeled L-methionine. Although the concentration of exogenous unlabeled methionine is critical for incorporation of the 14C label, optimum incorporation was achieved by adding 50 mg of unlabeled L-methionine and 200 mu Ci of L-[methyl-14C]methionine to a corn patty (30 g) over a period of 9 days, yielding [14C]FB1 with a specific activity of 36 mu Ci/mmol. PMID:8368853

  4. Soil metabolism of [14C]methiozolin under aerobic and anaerobic flooded conditions.

    PubMed

    Hwang, Ki-Hwan; Lim, Jong-Soo; Kim, Sung-Hun; Chang, Hee-Ra; Kim, Kyun; Koo, Suk-Jin; Kim, Jeong-Han

    2013-07-17

    Methiozolin is a new turf herbicide controlling annual bluegrass in various cool- and warm-season turfgrasses. This study was conducted to investigate the fate of methiozolin in soil under aerobic and anaerobic flooded conditions using two radiolabeled tracers, [benzyl-(14)C]- and [isoxazole-(14)C]methiozolin. The mass balance of applied radioactivity ranged from 91.7 to 104.5% in both soil conditions. In the soil under the aerobic condition, [(14)C]methiozolin degraded with time to remain by 17.9 and 15.9% of the applied in soil at 120 days after treatment (DAT). [(14)C]Carbon dioxide and the nonextractable radioactivity increased as the soil aged to reach up to 41.5 and 35.7% for [benzyl-(14)C]methiozolin at 120 DAT, respectively, but 36.1 and 39.8% for [isoxazole-(14)C]methiozolin, respectively, during the same period. The nonextractable residue was associated more with humin and fulvic acid fractions under the aerobic condition. No significant volatile products or metabolites were detected during this study. The half-life of [(14)C]methiozolin was approximately 49 days in the soil under the aerobic condition; however, it could not be estimated in the soil under the anaerobic flooded condition because [(14)C]methiozolin degradation was limited. On the basis of these results, methiozolin is considered to undergo fast degradation by aerobic microbes, but not by anaerobic microbes in soil.

  5. Bacterial uptake of 14C-chlorhexidine diacetate and 14C-benzyl alcohol and the influence of phenoxyethanol and azolectin: studies with gram-negative bacteria.

    PubMed

    Fitzgerald, K A; Davies, A; Russell, A D

    1992-01-01

    The uptake of 14C-chlorhexidine (14C-CHA) by Pseudomonas aeruginosa and smooth, rough and deep rough strains of Escherichia coli was very rapid with maximum uptake occurring within 20 s. Despite the rapid binding, the lethal action of CHA, although concentration-dependent, is comparatively slow and occurs in minutes rather than seconds. This indicates that the initial rapid binding is followed by a second slower action, responsible for the lethal effects of CHA. The lethal action could be accelerated, particularly at modest concentrations of CHA, by the simultaneous presence of phenoxyethanol (POE) or benzyl alcohol (BZA), although the magnitude of the effect was small. Both alcohols had little effect on the binding of 14C-CHA, which does not explain the enhanced bactericidal action of CHA. Uptake of 14C-benzyl alcohol (14C-BZA) by the same strains showed very different patterns with slower and time-related binding. CHA had a marked effect on BZA absorption but no direct link was established between binding patterns and cell death. The CHA neutraliser, azolectin, removed bound CHA (in the presence or absence of POE) very efficiently even at contact times of only 20 s.

  6. Will there be a 14C minimum in the tropical Pacific in the 1990s

    SciTech Connect

    Toggweiler, J.R. )

    1990-01-09

    14C distributions measured during GEOSECS showed large minima in bomb 14C levels in the tropical belts of the major ocean basins. Broecker et al. (1978, JGR, 83) attributed the minima to upwelling of deep water which was free of bomb 14C. Wyrtki (1981, JPO, 11) countered that heat budgets constrain the water upwelling the the equator to be from the upper themocline. Druffel (1987, JMR, 45) built a model of the Pacific upwelling system incorporating Wyrtki's description of the upwelling system. Druffel showed that the GEOSECS 14C minimum could be reproduced with upwelled upper thermocline water because bomb 14C levels were still relatively low in the tropical thermocline at the time of GEOSECS. Druffel went on to predict that mid latitude and tropical surface 14C levels would approach a common value before the 1990s and upper thermocline water masses acquired more bomb 14C and atmospheric 14C levels declined. By studying pre-bomb coral 14C records and a model simulation in Toggweiler et al. (1989, JGR, 94), I have found confirmation that some older and colder water upwells in the tropical Pacific. Upper thermocline (22-24C) water has about the same pre-bomb 14C content as pre-bomb surface waters and cannot generate a low 14C singal prior to the bomb test. The appearance of the oldest upwelled water in the coral data is correlated in time with the cold phase of the ENSO cycle. Most of the low 14C water moves southward into the South Pacific. I will argue that intensified upwelling during the cold phase of ENSO pulls up 12-14C water from the lower layers of the Equatorial Undercurrent. Upwelling from this layer may represent an important closure mechanism for mode waters formed in the subantarctic. A source of older water makes it certain that the tropical 14C minimum will persist through the 1990s and the remainder of the post-bomb era.

  7. Disposition and metabolism of 2,3-[14C]dichloropropene in rats after inhalation.

    PubMed

    Bond, J A; Medinsky, M A; Dutcher, J S; Henderson, R F; Cheng, Y S; Mewhinney, J A; Birnbaum, L S

    1985-03-30

    2,3-Dichloropropene (2,3-DCP) is a constituent of some commercially available preplant soil fumigants for the control of plant parasitic nematodes. Human exposure potential exists during manufacture of the chemicals or during bulk handling activities. The purpose of this investigation was to determine the disposition and metabolism of 2,3-[14C]DCP in rats after inhalation. Male Fischer-344 rats were exposed nose-only to a vapor concentration of 250 nmol 2,3-[14C]DCP/liter air (7.5 ppm; 25 degrees C, 620 Torr) for 6 hr. Blood samples were taken during exposure, and urine, feces, expired air, and tissues were collected for up to 65 hr after exposure. Urinary excretion was the major route of elimination of 14C (55% of estimated absorbed 2,3-DCP). Half-time for elimination of 14C in urine was 9.8 +/- 0.05 hr (means +/- SE). Half-time for elimination of 14C feces (17% of absorbed 2,3-DCP) was 12.9 +/- 0.14 hr (means +/- SE). Approximately 1 and 3% of the estimated absorbed 2,3-[14C]DCP were exhaled as either 2,3-[14C]DCP or 14CO2, respectively. Concentrations of 14C in blood increased during 240 min of exposure, after which no further increases in blood concentration of 14C were seen. 14C was widely distributed in tissues analyzed after a 6-hr exposure of rats to 2,3-[14C]DCP. Urinary bladder (150 nmol/g), nasal turbinates (125 nmol/g), kidneys (84 nmol/g), small intestine (61 nmol/g), and liver (35 nmol/g) were tissues with the highest concentrations of 14C immediately after exposure. Over 90% of the 14C in tissues analyzed was 2,3-DCP metabolites. Half-times for elimination of 14C from tissues examined ranged from 3 to 11 hr. The data from this study indicate that after inhalation 2,3-DCP is metabolized in tissues and readily excreted.

  8. Surrogate gas prediction model as a proxy for Δ14C-based measurements of fossil fuel CO2

    NASA Astrophysics Data System (ADS)

    Coakley, Kevin J.; Miller, John B.; Montzka, Stephen A.; Sweeney, Colm; Miller, Ben R.

    2016-06-01

    The measured 14C:12C isotopic ratio of atmospheric CO2 (and its associated derived Δ14C value) is an ideal tracer for determination of the fossil fuel derived CO2 enhancement contributing to any atmospheric CO2 measurement (Cff). Given enough such measurements, independent top-down estimation of U.S. fossil fuel CO2 emissions should be possible. However, the number of Δ14C measurements is presently constrained by cost, available sample volume, and availability of mass spectrometer measurement facilities. Δ14C is therefore measured in just a small fraction of samples obtained by flask air sampling networks around the world. Here we develop a projection pursuit regression (PPR) model to predict Cff as a function of multiple surrogate gases acquired within the NOAA/Earth System Research Laboratory (ESRL) Global Greenhouse Gas Reference Network (GGGRN). The surrogates consist of measured enhancements of various anthropogenic trace gases, including CO, SF6, and halocarbon and hydrocarbon acquired in vertical airborne sampling profiles near Cape May, NJ and Portsmouth, NH from 2005 to 2010. Model performance for these sites is quantified based on predicted values corresponding to test data excluded from the model building process. Chi-square hypothesis test analysis indicates that these predictions and corresponding observations are consistent given our uncertainty budget which accounts for random effects and one particular systematic effect. However, quantification of the combined uncertainty of the prediction due to all relevant systematic effects is difficult because of the limited range of the observations and their relatively high fractional uncertainties at the sampling sites considered here. To account for the possibility of additional systematic effects, we incorporate another component of uncertainty into our budget. Expanding the number of Δ14C measurements in the NOAA GGGRN and building new PPR models at additional sites would improve our understanding of

  9. Root and foliar uptake, translocation, and distribution of [14C] fluoranthene in pea plants (Pisum sativum).

    PubMed

    Zezulka, Stěpán; Klemš, Marek; Kummerová, Marie

    2014-10-01

    Uptake of (14)C-labeled fluoranthene ([(14)C]FLT) via both roots and leaves of Pisum sativum seedlings and distribution of [(14) C] in plants by both acropetal and basipetal transport was evaluated. The highest [(14)C] level was found in the root base (≈270 × 10(4) dpm/g dry wt) and the lowest level in the stem apex (<2 × 10(4) dpm/g dry wt) after just 2 h of root exposure. For foliar uptake, the highest level of [(14)C] was found in the stem and root apex (both ≈2 × 10(4) dpm/g dry wt) (except for treated leaves), while the lowest level was found in the root base (<0.6 × 10(4) dpm/g dry wt).

  10. Radiocarbon dating of silica sinter deposits in shallow drill cores from the Upper Geyser Basin, Yellowstone National Park

    USGS Publications Warehouse

    Lowenstern, Jacob B.; Hurwitz, Shaul; McGeehin, John

    2016-01-01

    To explore the timing of hydrothermal activity at the Upper Geyser Basin (UGB) in Yellowstone National Park, we obtained seven new accelerator mass spectrometry (AMS) radiocarbon 14C ages of carbonaceous material trapped within siliceous sinter. Five samples came from depths of 15–152 cm within the Y-1 well, and two samples were from well Y-7 (depths of 24 cm and 122 cm). These two wells, at Black Sand and Biscuit Basins, respectively, were drilled in 1967 as part of a scientific drilling program by the U.S. Geological Survey (White et al., 1975). Even with samples as small as 15 g, we obtained sufficient carbonaceous material (a mixture of thermophilic mats, pollen, and charcoal) for the 14C analyses. Apparent time of deposition ranged from 3775 ± 25 and 2910 ± 30 14C years BP at the top of the cores to about 8000 years BP at the bottom. The dates are consistent with variable rates of sinter formation at individual sites within the UGB over the Holocene. On a basin-wide scale, though, these and other existing 14C dates hint that hydrothermal activity at the UGB may have been continuous throughout the Holocene.

  11. Radiocarbon dating of silica sinter deposits in shallow drill cores from the Upper Geyser Basin, Yellowstone National Park

    NASA Astrophysics Data System (ADS)

    Lowenstern, Jacob B.; Hurwitz, Shaul; McGeehin, John P.

    2016-01-01

    To explore the timing of hydrothermal activity at the Upper Geyser Basin (UGB) in Yellowstone National Park, we obtained seven new accelerator mass spectrometry (AMS) radiocarbon 14C ages of carbonaceous material trapped within siliceous sinter. Five samples came from depths of 15-152 cm within the Y-1 well, and two samples were from well Y-7 (depths of 24 cm and 122 cm). These two wells, at Black Sand and Biscuit Basins, respectively, were drilled in 1967 as part of a scientific drilling program by the U.S. Geological Survey (White et al., 1975). Even with samples as small as 15 g, we obtained sufficient carbonaceous material (a mixture of thermophilic mats, pollen, and charcoal) for the 14C analyses. Apparent time of deposition ranged from 3775 ± 25 and 2910 ± 30 14C years BP at the top of the cores to about 8000 years BP at the bottom. The dates are consistent with variable rates of sinter formation at individual sites within the UGB over the Holocene. On a basin-wide scale, though, these and other existing 14C dates hint that hydrothermal activity at the UGB may have been continuous throughout the Holocene.

  12. Disposition of 14C-β-carotene following delivery with autologous triacylglyceride-rich lipoproteins

    NASA Astrophysics Data System (ADS)

    Dueker, Stephen R.; Vuong, Le Thuy; Faulkner, Brian; Buchholz, Bruce A.; Vogel, John S.

    2007-06-01

    Following ingestion, a fraction of β-carotene is cleaved into vitamin A in the intestine, while another is absorbed intact and distributed among tissues and organs. The extent to which this absorbed β-carotene serves as a source of vitamin A is unknown in vivo. In the present study we use the attomole sensitivity of accelerator mass spectrometry (AMS) for 14C to quantify the disposition of 14C-β-carotene (930 ng; 60.4 nCi of activity) after intravenous injection with an autologous triacylglyceride-rich lipoprotein fraction in a single volunteer. Total 14C was quantified in serial plasma samples and also in triglyceride-rich, and low density lipoprotein, subfractions. The appearance of 14C-retinol, the circulating form of vitamin A in plasma, was determined by chromatographic separation of plasma retinol extracts prior to AMS analysis. The data showed that 14C concentrations rapidly decayed within the triglyceride-rich lipoprotein fractions after injection, whereas low density lipoprotein 14C began a significant rise in 14C 5 h post dose. Plasma 14C-retinol also appeared at 5 h post dose and its concentrations were maintained above baseline for >88 days. Based upon comparisons of 14C-retinol concentrations following an earlier study with orally dosed 14C-β-carotene, a molar vitamin A value of the absorbed β-carotene of 0.19 was derived, meaning that 1 mole of absorbed β-carotene provides 0.19 moles of vitamin A. This is the first study to show that infused β-carotene contributes to the vitamin A economy in humans in vivo.

  13. Utilization of orally administered D-[14C]mannitol via fermentation by intestinal microbes in rats.

    PubMed

    Hongo, Ryoko; Nakamura, Sadako; Oku, Tsuneyuki

    2010-01-01

    To investigate the available energy of orally administered [(14)C]mannitol via intestinal microbes, [(14)C]mannitol (222 kBq, 105 mg) or [(14)C]glucose (222 kBq, 105 mg) was administered to conventional rats and antibiotics-treated rats whose intestinal microbes were depleted by drinking water containing antibiotics, respectively. The exhausted CO(2), feces and urine were then separately collected at 2, 4, 6, 8, 10, 12 and 24 h after administration of the test solution. In the conventional rats, 45% of administered radioactivity was recovered as (14)CO(2) in the administration of [(14)C]mannitol, while 57% of administered radioactivity was recovered as (14)CO(2) following the administration of [(14)C]glucose for 24 h. The time sequence for the (14)CO(2) excretion from [(14)C]mannitol was delayed as compared to [(14)C]glucose by about 4-6 h (p<0.05). However, when [(14)C]mannitol was orally administered to antibiotics-treated rats, only 3% of administered radioactivity was excreted as (14)CO(2) for 24 h. The total radioactivity of the gastrointestinal contents and feces for 24 h after administration was over 70%, much higher than those of the conventional rats (p<0.05). When a half dose (222 kBq, 52.5 mg) of [(14)C]mannitol was administered to conventional rats, the recovery as (14)CO(2) for 24 h (%) was significantly higher than that of a regular dose of [(14)C]mannitol (105 mg). When cold mannitol (105 mg) was orally administered to the antibiotics-treated rats, about 9% of intact mannitol was excreted in feces within 48 h after administration. However, no intact mannitol was detected in the conventional rats. These results demonstrate that more than 95% of mannitol administered orally is utilized via fermentation by intestinal microbes.

  14. Appearance of circulating and tissue /sup 14/C-lipids after oral /sup 14/C-tripalmitate administration in the late pregnant rat

    SciTech Connect

    Argiles, J.; Herrera, E.

    1989-02-01

    Studies were performed to determine whether and/or how dietary lipids participate in maternal hypertriglyceridemia during late gestation in the rat. After oral administration of glycerol-tri(1-14C)-palmitate, total radioactivity in plasma increased more rapidly in 20-day pregnant rats than in either 19-day pregnant rats or virgin controls. At the peak of plasma radioactivity, four hours after the tracer was administered, most of the plasma label corresponded to 14C-lipids in triglyceride-rich lipoproteins (d less than 1.006), and when expressed per micromol of triglyceride, values were higher in pregnant than in virgin rats. The difference was less after 24 hours, although at this time the level of 14C-lipids in d less than 1.006 lipoproteins was still higher in 20-day pregnant rats than in virgins. Tissue 14C-lipids, as expressed per gram of fresh weight, were similar in pregnant and virgin rats, but the values in mammary glands were much higher in the former group. Estimated recovery of administered radioactivity four hours after tracer in total white adipose tissue, mammary glands, and plasma lipids was higher in pregnant than in virgin rats. No difference was found between 20-day pregnant and virgin rats either in the label retained in the gastrointestinal tract or in that exhaled as 14C-CO2 during the first four hours following oral administration of 14C-tripalmitate. These findings plus the known maternal hyperphagia, indicate that in the rat at late pregnancy triglyceride intestinal absorption is unchanged or even enhanced and that dietary lipids actively contribute to both maternal hypertriglyceridemia and lipid uptake by the mammary gland.

  15. The effect of 6-aminonicotinamide on the levels of brain amino acids and glucose, and their labeling with 14C after injection of (U-14C) glucose

    SciTech Connect

    Gaitonde, M.K.; Lewis, L.P.; Evans, G.; Clapp, A.

    1981-10-01

    The brains of rats paralysed at 4 hr after the administration of 6-aminonicotinamide were found to contain decreased levels of glutamate and gamma-aminobutyrate. The glucose content of the brain of the treated rats was several fold higher than in controls. The incorporation of 14C into brain amino acids at 30 min after the injection of (U-14C)glucose was decreased by 16%: this was attributed to mainly decreased labeling of glutamate and associated amino acids. The results are discussed in the light of previous findings that the administration of 6-aminonicotinamide resulted in the blockade of the direct oxidation of glucose by the pentose phosphate pathway.

  16. Dissolved Organic Carbon in Marginal, Damaged Peatlands: Using 14C to Understand DOC Losses

    NASA Astrophysics Data System (ADS)

    Luscombe, D.; Grand-Clement, E.; Garnett, M.; Anderson, K.; Gatis, N.; Benaud, P.; Brazier, R.

    2013-12-01

    Peatlands are widely represented throughout the world and act as an important store of carbon, as well as providing society with a range of other ecosystem services, such as drinking water or the support of rare habitats. However, the combination of historical management practices, and the predicted impact of climate change means that they are now largely under threat. In the shallow peatlands of Exmoor National Park (South West UK), peat cutting and intensive drainage in the 19th and 20th century for agricultural reclamation have changed the hydrological behaviour of the peat. This damage has dried out the upper layers, causing oxidation, erosion and vegetation change. In addition, their location on the southernmost limit of peatlands geographical extent in northern Europe makes them particularly vulnerable to the predicted changes in rainfall and temperature. Recent modelling work has shown that such marginal peatlands may disappear as early as 2050. Restoration programs are currently in place, aiming to restore the hydrological functioning of the peat. However, current dissolved organic carbon (DOC) losses from damaged peatlands are especially of concern, because of the contribution of the aquatic pathways in the C flux, and because of the impact on water quality. DOC has been shown to originate from the drainage of highly-aged organic matter. In stream waters, DOC from low flow tends to contain a larger component of older C compared to that of high flow. Both the impact of extensive drainage on where DOC is originating from and the effect of peatland restoration on this process remain poorly understood. We used 14C dating of DOC from streams and pore water, as well as from damaged peat, in order to gain a better understanding of the process and origin of DOC loss in drained shallow peatlands. This will further help us understand the potential for peatland restoration. Work was carried out in a small intensively monitored catchment in Exmoor. Samples were taken

  17. Human urinary excretion profile after smoking and oral administration of ( sup 14 C)delta 1-tetrahydrocannabinol

    SciTech Connect

    Johansson, E.; Gillespie, H.K.; Halldin, M.M. )

    1990-05-01

    The urinary excretion profiles of delta 1-tetrahydrocannabinol (delta 1-THC) metabolites have been evaluated in two chronic and two naive marijuana users after smoking and oral administration of ({sup 14}C)delta 1-THC. Urine was collected for five days after each administration route and analyzed for total delta 1-THC metabolites by radioactivity determination, for delta 1-THC-7-oic acid by high-performance liquid chromatography, and for cross-reacting cannabinoids by the EMIT d.a.u. cannabinoid assay. The average urinary excretion half-life of {sup 14}C-labeled delta 1-THC metabolites was calculated to be 18.2 +/- 4.9 h (+/- SD). The excretion profiles of delta 1-THC-7-oic acid and EMIT readings were similar to the excretion profile of {sup 14}C-labeled metabolites in the naive users. However, in the chronic users the excretion profiles of delta 1-THC-7-oic acid and EMIT readings did not resemble the radioactive excretion due to the heavy influence from previous Cannabis use. Between 8-14% of the radioactive dose was recovered in the urine in both user groups after oral administration. Lower urinary recovery was obtained both in the chronic and naive users after smoking--5 and 2%, respectively.

  18. Kinetics for the synthetic bile acid 75selenohomocholic acid-taurine in humans: comparison with [14C]taurocholate.

    PubMed

    Jazrawi, R P; Ferraris, R; Bridges, C; Northfield, T C

    1988-07-01

    The "apparent" fractional turnover rate of the gamma-labeled bile acid analogue 75selenohomocholic acid-taurine (75SeHCAT) was assessed from decline in radioactivity over the gallbladder area on 4 successive days using a gamma-camera, and was compared in the same subjects with the fractional turnover rate of the corresponding natural bile acid, cholic acid-taurine, labeled with 14C ([14C]CAT) using the classical Lindstedt technique. Very similar results were obtained in 5 healthy individuals (coefficient of variation 4.8%, medians 0.35 and 0.34, respectively). By contrast, the fractional deconjugation rate assessed from zonal scanning of glycine- and taurine-conjugated bile acids on thin-layer chromatography was much less for 75SeHCAT than for [14C]CAT (0.02 and 0.13, respectively; p less than 0.05). The fractional rate for deconjugation plus dehydroxylation was also determined by zonal scanning, and gave lower values for 75SeHCAT than for [14C]CAT (0.02 and 0.12, respectively; p less than 0.05). There was a striking similarity between the fractional rate for deconjugation alone and that for deconjugation plus dehydroxylation for both bile acids in individual samples (r = 0.999, p less than 0.001), suggesting that these two processes might occur simultaneously and probably involve the same bacteria. We conclude that our scintiscanning technique provides an accurate, noninvasive method of measuring fractional turnover rate of a bile acid in humans, and that the finding that 75SeHCAT remains conjugated with taurine during enterohepatic recycling means that absorption should be specific for the ileal active transport site, thus rendering it an ideal substance for assessing ileal function.

  19. Kinetics for the synthetic bile acid 75-selenohomocholic acid-taurine in humans: comparison with (/sup 14/C)taurocholate

    SciTech Connect

    Jazrawi, R.P.; Ferraris, R.; Bridges, C.; Northfield, T.C.

    1988-07-01

    The apparent fractional turnover rate of the gamma-labeled bile acid analogue 75-selenohomocholic acid-taurine (75-SeHCAT) was assessed from decline in radioactivity over the gallbladder area on 4 successive days using a gamma-camera, and was compared in the same subjects with the fractional turnover rate of the corresponding natural bile acid, cholic acid-taurine, labeled with 14C ((14C)CAT) using the classical Lindstedt technique. Very similar results were obtained in 5 healthy individuals (coefficient of variation 4.8%, medians 0.35 and 0.34, respectively). By contrast, the fractional deconjugation rate assessed from zonal scanning of glycine- and taurine-conjugated bile acids on thin-layer chromatography was much less for 75-SeHCAT than for (14C)CAT (0.02 and 0.13, respectively; p less than 0.05). The fractional rate for deconjugation plus dehydroxylation was also determined by zonal scanning, and gave lower values for 75-SeHCAT than for (14C)CAT (0.02 and 0.12, respectively; p less than 0.05). There was a striking similarity between the fractional rate for deconjugation alone and that for deconjugation plus dehydroxylation for both bile acids in individual samples (r = 0.999, p less than 0.001), suggesting that these two processes might occur simultaneously and probably involve the same bacteria. We conclude that our scintiscanning technique provides an accurate, noninvasive method of measuring fractional turnover rate of a bile acid in humans, and that the finding that 75SeHCAT remains conjugated with taurine during enterohepatic recycling means that absorption should be specific for the ileal active transport site, thus rendering it an ideal substance for assessing ileal function.

  20. Lack of tissue renewal in human adult Achilles tendon is revealed by nuclear bomb 14C

    PubMed Central

    Heinemeier, Katja Maria; Schjerling, Peter; Heinemeier, Jan; Magnusson, Stig Peter; Kjaer, Michael

    2013-01-01

    Tendons are often injured and heal poorly. Whether this is caused by a slow tissue turnover is unknown, since existing data provide diverging estimates of tendon protein half-life that range from 2 mo to 200 yr. With the purpose of determining life-long turnover of human tendon tissue, we used the 14C bomb-pulse method. This method takes advantage of the dramatic increase in atmospheric levels of 14C, produced by nuclear bomb tests in 1955–1963, which is reflected in all living organisms. Levels of 14C were measured in 28 forensic samples of Achilles tendon core and 4 skeletal muscle samples (donor birth years 1945–1983) with accelerator mass spectrometry (AMS) and compared to known atmospheric levels to estimate tissue turnover. We found that Achilles tendon tissue retained levels of 14C corresponding to atmospheric levels several decades before tissue sampling, demonstrating a very limited tissue turnover. The tendon concentrations of 14C approximately reflected the atmospheric levels present during the first 17 yr of life, indicating that the tendon core is formed during height growth and is essentially not renewed thereafter. In contrast, 14C levels in muscle indicated continuous turnover. Our observation provides a fundamental premise for understanding tendon function and pathology, and likely explains the poor regenerative capacity of tendon tissue.—Heinemeier, K. M., Schjerling, P., Heinemeier, J., Magnusson, S. P., Kjaer, M. Lack of tissue renewal in human adult Achilles tendon is revealed by nuclear bomb 14C. PMID:23401563

  1. Discussion: Reporting and calibration of post-bomb 14C data

    SciTech Connect

    Reimer, P J; Brown, T A; Reimer, R W

    2004-10-11

    The definitive paper by Stuiver and Polach (1977) established the conventions for reporting of {sup 14}C data for chronological and geophysical studies based on the radioactive decay of {sup 14}C in the sample since the year of sample death or formation. Several ways of reporting {sup 14}C activity levels relative to a standard were also established, but no specific instructions were given for reporting nuclear weapons testing (post-bomb) {sup 14}C levels in samples. Because the use of post-bomb {sup 14}C is becoming more prevalent in forensics, biology, and geosciences, a convention needs to be adopted. We advocate the use of fraction modern with a new symbol F{sup 14}C to prevent confusion with the previously used Fm, which may or may not have been fractionation corrected. We also discuss the calibration of post-bomb {sup 14}C samples and the available datasets and compilations, but do not give a recommendation for a particular dataset.

  2. Secretin enhances (/sup 14/C)erythritol clearance in unanesthetized dogs

    SciTech Connect

    Lewis, M.H.; Baker, A.L.; Dhorajiwala, J.; Moossa, A.R.

    1982-01-01

    To determine the effect of secretin infusion on clearance of inert markers into bile, unanesthetized dogs fitted with Thomas cannulas received continuous infusions of (/sup 14/C)erythritol and (/sup 3/H)inulin throughout study. Taurocholic acid administered sequentially at 9.0, 20.0, and 40.0 mumol/min enhanced (/sup 14/C)erythritol clearance, and GIH secretin (3 units/min) administered along with TCA (40.0 mumol/min) increased (/sup 14/C)erythritol clearance from 4.9 +/- 1.2 ml/10 min to 6.8 +/- 1.3 ml/10 min (P less than 0.001), but simultaneously measured (/sup 3/H)inulin clearance was unaltered. Secretin alone also increased (/sup 14/C)erythritol clearance but did not alter (/sup 3/H)inulin clearance. The increase in (/sup 14/C)erythritol clearance per unit increase in bile flow was less during secretin infusion than TCA. Thus, secretin increases (/sup 14/C)erythritol transport through restricted channels, probably distal to the canaliculi. (/sup 14/C)Erythritol may not be an accurate marker for canalicular bile flow in dogs during secretin infusion.

  3. The biological fate of sup 14 C-dimercaptosuccinic acid in monkeys and rabbits

    SciTech Connect

    Tillotson, J.A.; Boswell, G.; Kincannon, L.; Speckman, C.L.

    1989-09-01

    The biological fate of {sup 14}C-labeled dimercaptosuccinic acid (DMSA) in monkeys and rabbits was determined by measuring the {sup 14}C activity in their urine, feces, and expired air ({sup 14}CO{sub 2}). Monkeys absorbed less than 20% DMSA from three oral dose levels (0.082, 0.16, and 0.5 mmol/kg) of {sup 14}C-DMSA, and the rabbits absorbed 32% DMSA or less from an oral dose of {sup 14}C-DMSA (0.5 mmol/kg). Although the bioavailability of DMSA was limited in either species, DMSA was detected in the blood of both species within minutes after oral dosing. In either species, most of the radiolabel from the absorbed {sup 14}C-DMSA was detected in the urine within 12 hours. We also developed a sensitive assay for directly measuring levels of DMSA (as free thiols) in blood. Intact DMSA was not detected in the blood of the monkeys or the rabbits more than 200 minutes after oral or intravenous dosing at 0.5 mmol DMSA/kg body weight. However, {sup 14}C activity in blood and urine of the monkeys was measurable 72 hours after this dose. Differences between measured {sup 14}C concentrations and intact DMSA concentrations in the blood suggest the presence of DMSA metabolites that have longer half-lives than DMSA. Consequently, until the biological activities of these compounds are identified, the pharmacokinetic analysis of DMSA may be incomplete.

  4. Biokinetic and dosimetric investigations of 14C-labeled substances in man using AMS

    NASA Astrophysics Data System (ADS)

    Mattsson, Sören; Gunnarsson, Mikael; Svegborn, Sigrid Leide; Nosslin, Bertil; Nilsson, Lars-Erik; Thorsson, Ola; Valind, Sven; Åberg, Magnus; Östberg, Henrik; Hellborg, Ragnar; Stenström, Kristina; Erlandsson, Bengt; Faarinen, Mikko; Kiisk, Madis; Magnusson, Carl-Erik; Persson, Per; Skog, Göran

    2001-07-01

    Up to now, radiation dose estimates from radiopharmaceuticals, labeled with pure β-emitting radionuclides, e.g., 14C or 3H have been very uncertain. Using accelerator mass spectrometry (AMS) we have derived new and improved data for 14C-triolein and 14C-urea and are currently running a program related to the biokinetics and dosimetry of 14C-glycocholic acid and 14C-xylose. The results of our investigations have made it possible to widen the indications for the clinical use of the 14C-urea test for Helicobacter pylori infection in children. The use of ultra-low activities, which is possible with AMS (down to 1/1000 of that used for liquid scintillation counting), has opened the possibility for metabolic investigations on children as well as on other sensitive patient groups like new-borns, and pregnant or breast-feeding women. Using the full potential of AMS, new 14C-labeled drugs could be tested on humans at a much earlier stage than today, avoiding uncertain extrapolations from animal models.

  5. Microscale radiocarbon dating of paintings

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

    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. 14C 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 14C 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.

  6. 14C2H4: Its Incorporation and Metabolism by Pea Seedlings under Aseptic Conditions 1

    PubMed Central

    Beyer, Elmo M.

    1975-01-01

    The effects of various treatments on the recently reported system in pea (Pisum sativum cv. Alaska), which results in (a) the incorporation of 14C2H4 into the tissue and (b) the conversion of 14C2H4 to 14CO2, was investigated using 2-day-old etiolated seedlings which exhibit a maximum response. Heat treatment (80 C, 1 min) completely inhibited both a and b, whereas homogenization completely inhibited b but only partially inhibited a. Detaching the cotyledons from the root-shoot axis immediately before exposing the detached cotyledons together with the root-shoot axis to 14C2H4 markedly reduced both a and b. Increasing the 14C2H4 concentration from 0.14 to over 100 μl/l progressively increased the rate of a and b with tissue incorporation being greater than 14C2H4 to 14CO2 conversion only below 0.3 μl/l 14C2H4. Reduction of the O2 concentration reduced both a and b, with over 99% inhibition occurring under anaerobic conditions. The addition of CO2 (5%) severely inhibited 14C2H4 to 14CO2 conversion without significantly affecting tissue incorporation. Exposure of etiolated seedlings to fluorescent light during 14C2H4 treatment was without effect. Similarly, indoleacetic acid, gibberellic acid, benzyladenine, abscisic acid, and dibutyryl cyclic adenosine monophosphate had no significant effect on either a or b. The possibilities that the incorporation of 14C2H4 into pea tissues and its conversion to 14CO2 is linked to ethylene action, or that it represents a means of reducing the endogenous ethylene level, are discussed. Several problems encountered with the use of polyethylene vials, rubber serum stoppers, Clorox, and microbial contamination are also described. Images PMID:16659286

  7. Possible cluster preformation in the sup 14 C decay of sup 223 Ra

    SciTech Connect

    Hussonnois, M.; Le Du, J.F.; Brillard, L.; Ardisson, G. )

    1990-08-01

    A recent experiment on the {sup 14}C fine structure has shown that the branching ratio to {sup 209}Pb ground state is quite different from the one predicted by the various models of cluster emission. Assuming that the {sup 14}C is preformed in the {sup 223}Ra nucleus, we have calculated the hindrance factor {ital F}{sup 14}C of the three {sup 14}C branches to {sup 209}Pb states with a barrier penetrability approximated by a square-well Coulomb potential. The {ital F}{sup 14}C=3.9 and 4.6 values found for the {sup 14}C transitions to the two excited states at 779 keV ({ital I}{sup {pi}}=11/2{sup +}) and 1423 keV ({ital I}{sup {pi}}=15/2{sup {minus}}), respectively, reveal that the cluster formation amplitudes in both transitions are close to those of the {sup 222}Ra and {sup 224}Ra {sup 14}C decays. Such values could be the result of {vert bar}{ital nlj}{r angle} shell-model components common to both the wave functions of the octupole deformed {sup 223}Ra nucleus and of the two first excited states of {sup 209}Pb spherical nucleus. The high hindrance factor {ital F}{sup 14}C=583 of the {sup 14}C branch to the {sup 209}Pb ground state ({ital I}{sup {pi}}=9/2{sup +}) could reveal the absence of {vert bar}1{ital g}{sub 9/2}{r angle} shell-model component in the {sup 223}Ra wave function.

  8. Dating human bone: is racemization dating species-specific?

    PubMed

    Moini, Mehdi; Rollman, Christopher M; France, Christine A M

    2013-12-01

    Our recently developed dating technique based on the racemization rate of aspartic acid was applied to dating human bone, as well as that of other mammals, utilizing capillary electrophoresis mass spectrometry. First, several well-dated (mostly (14)C-dated and with strong archeological evidence) human bones ranging in age from 150 to ~10,000 years were used to develop a calibration curve for human bone. The D/L ratio of aspartic acid for these specimens ranged from 2.4% to ~10%, with a correlation coefficient of better than 0.99, indicating a strong linear relationship between the d/l ratio of aspartic acid and the age of the specimens. This calibration curve can now be used to date human archeological specimens of unknown age, up to ~10,000 years. However, when the technique was applied to well-dated mixed species of larger mammal bones such as bison, whale, llama, etc., the calibration curve showed a slower rate of racemization with a lower correlation (0.88). As additional large mammal bones with less certain age (i.e., using archeological evidence alone with no (14)C-dating) were dated the correlation coefficient decreased to 0.70. The correlation coefficient decreased further to 0.58 when the racemization data from all mammals (including human) were added to the calibration curve, indicating the importance of using well-dated, species-specific specimens for forming a calibration curve. This conclusion is consistent with our previously published calibration curve for a single species of silk (Bombyx mori), which followed the expected reversible first-order kinetics. These results support species specificity of amino acid racemization dating.

  9. Timing is Everything:The Boon and Bane of 14C Geochronology

    SciTech Connect

    Guilderson, T; Guilderson, T; Reimer, P J; Brown, T

    2004-10-29

    There are underappreciated limitations of the conversion of {sup 14}C-ages to the fixed, calendrical time-scale that bear directly upon our understanding of the dynamic climate system, or the relationship between the collapse of one civilization and it's neighbor's. In this paper we present a quantitative assessment of the limits of {sup 14}C-geochronology and calibration onto the absolute calendrical time-scale over the Holocene. We take into account not only the inherent limitations of the {sup 14}C-calendar calibration curve, but also analytical uncertainties.

  10. The incorporation of isotopic carbon (14C) into the cerebral glycogen of rabbits

    PubMed Central

    Coxon, R. V.; Gordon-Smith, E. C.; Henderson, J. R.

    1965-01-01

    1. The incorporation of 14C into the brain glycogen of conscious rabbits with labelled glucose, bicarbonate and glutamate as precursors has been studied. 2. Substantial incorporation from all these precursors was demonstrated after an interval of 5hr. from their injection. 3. With [14C]glucose maximal incorporation occurred at about 8hr. from the time of injection. 4. Hydrocortisone led to increased incorporation of 14C from labelled glucose. 5. Some comparisons between the turnover of brain glycogen and that of skeletal and cardiac muscle are reported. PMID:5881665

  11. Synthesis, storage, and stability of (4-/sup 14/C)oxaloacetic acid

    SciTech Connect

    Hatch, M.D.; Heldt, H.W.

    1985-03-01

    A simple procedure for preparing (4-/sup 14/C)oxaloacetic acid based on the reaction between (/sup 14/C)HCO-3 and phosphoenolpyruvate catalyzed by phosphoenolpyruvate carboxylase is described. A simple method for preparing highly purified phosphoenolpyruvate carboxylase from maize leaves is described and the degradation of oxaloacetate under conditions of varying pH and divalent metal ion concentration is reported. (4-/sup 14/C)Oxaloacetic acid is stable for several months in 0.1 M HCl solution at -80 degrees C.

  12. The dynamics of folic acid metabolism in an adult given a small tracer dose of 14C-folic acid.

    PubMed

    Clifford, A J; Arjomand, A; Dueker, S R; Schneider, P D; Buchholz, B A; Vogel, J S

    1998-01-01

    Folate is an essential nutrient that is involved in many metabolic pathways, including amino acid interconversions and nucleotide (DNA) synthesis. In genetically susceptible individuals and populations, dysfunction of folate metabolism is associated with severe illness. Despite the importance of folate, major gaps exist in our quantitative understanding of folate metabolism in humans. The gaps exist because folate metabolism is complex, a suitable animal model that mimics human folate metabolism has not been identified, and suitable experimental protocols for in vivo studies in humans are not developed. In general, previous studies of folate metabolism have used large doses of high specific activity tritium and 14C-labeled folates in clinical patients. While stable isotopes such as deuterium and 13C-labeled folate are viewed as ethical alternatives to radiolabeled folates for studying metabolism, the lack of sensitive mass spectrometry methods to quantify them has impeded advancement of the field using this approach. In this chapter, we describe a new approach that uses a major analytical breakthrough, Accelerator Mass Spectrometry (AMS). Because AMS can detect attomole concentrations of 14C, small radioactive dosages (nCi) can be safely administered to humans and traced over long periods of time. The needed dosages are sufficiently small that the total radiation exposure is only a fraction of the natural annual background radiation of Americans, and the generated laboratory waste may legally be classified non-radioactive in many cases. The availability of AMS has permitted the longest (202 d) and most detailed study to date of folate metabolism in a healthy adult human volunteer. Here we demonstrate the feasibility of our approach and illustrate its potential by determining empirical kinetic values of folate metabolism. Our data indicate that the mean sojourn time for folate is in the range of 93 to 120 d. It took > or = 350 d for the absorbed portion of small

  13. Systemic distribution of sup 14 C-labeled formaldehyde applied in the root canal following pulpectomy

    SciTech Connect

    Hata, G.I.; Nishikawa, I.; Kawazoe, S.; Toda, T.

    1989-11-01

    The systemic distribution of {sup 14}C-labeled formaldehyde which had been placed in the root canals of the canines of cats following pulpectomies was studied using liquid scintillation counting and whole-body autoradiographic technique. Radioactive {sup 14}C which had been placed in the canals was found in the plasma 30 min after the root canal procedure. The recovery of systemic {sup 14}C radioactivity increased with time. In addition, it seemed that approximately 3% of the dose placed in the teeth was excreted in the urine within 36 h. Whole-body autoradiograms indicated extensive concentration of {sup 14}C radioactivity in tissues other than those analyzed with the liquid scintillation technique.

  14. A radiochemical assay for argininosuccinate synthetase with [U-14C]aspartate.

    PubMed

    Ratner, S

    1983-12-01

    A simple and sensitive radiochemical procedure to assay argininosuccinate synthetase activity in crude tissue homogenates and lysates of cultured cells is described. The new method depends on the location of 14C, uniformly, in the four carbons of aspartate. On incubation in the presence of excess of L-[U-14C]aspartate, L-citrulline, ATP, and an ATP-generating system, argininosuccinase and arginase, the [14C]fumarate formed is measured as the sum of malate and fumarate. After acidification the latter two acids are separated from [14C]aspartate on a small Dowex-50 column by elution with a few milliliters of water; the unutilized amino acid substrates remain on the column. With a specific radioactivity of 9 X 10(4) cpm, 1 to 2 nmol of product can be accurately measured under kinetically optimum conditions. PMID:6660522

  15. Exotic nuclear decay of /sup 223/Ra by emission of /sup 14/C nuclei

    SciTech Connect

    Gales, S.; Hourani, E.; Hussonnois, M.; Schapira, J.P.; Stab, L.; Vergnes, M.

    1984-08-20

    The exotic nuclear decay of /sup 223/Ra by emission of /sup 14/C nuclei has been investigated by use of an intense radioactive /sup 227/Ac source and a magnetic spectrometer with a large solid angle. After a run of 5 d, a group of eleven events was observed at the expected location of /sup 14/C in a ..delta..E-E telescope calibrated with a /sup 14/C beam. A branching ratio of (5.5 +- 2.0) x 10/sup -10/ was measured for the emission of /sup 14/C nuclei relative to ..cap alpha.. particles from /sup 223/Ra in agreement with the previously reported ratio of (8.5 +- 2.5) x 10/sup -10/. .AE

  16. Interpretation of the fine structure in the sup 14 C radioactive decay of sup 223 Ra

    SciTech Connect

    Sheline, R.K. ); Ragnarsson, I. )

    1991-03-01

    The experimental hindrance factors determined from the fine structure in the {sup 14}C decay of {sup 223}Ra are strikingly similar to the hindrance factors observed in the alpha decay of odd-{ital A} reflection-asymmetric deformed nuclei in spite of the deformed to spherical shape which occurs in the {sup 14}C decay. Calculations of the overlap between the reflection-asymmetric ground state of {sup 223}Ra and the spherical shell-model orbitals of {sup 209}Pb involved in the {sup 14}C decay are consistent with the experimental hindrance factors from the {sup 14}C fine structure except that the {ital j}{sub 15/2} orbital is more strongly populated experimentally than the calculations suggest.

  17. Online coupling of pure O2 thermo-optical methods - 14C AMS for source apportionment of carbonaceous aerosols

    NASA Astrophysics Data System (ADS)

    Agrios, Konstantinos; Salazar, Gary; Zhang, Yan-Lin; Uglietti, Chiara; Battaglia, Michael; Luginbühl, Marc; Ciobanu, Viorela Gabriela; Vonwiller, Matthias; Szidat, Sönke

    2015-10-01

    This paper reports on novel separation methods developed for the direct determination of 14C in organic carbon (OC) and elemental carbon (EC), two sub-fractions of total carbon (TC) of atmospheric air particulate matter. Until recently, separation of OC and EC has been performed off-line by manual and time-consuming techniques that relied on the collection of massive CO2 fractions. We present here two on-line hyphenated techniques between a Sunset OC/EC analyzer and a MICADAS (MIni radioCArbon DAting System) accelerator mass spectrometer (AMS) equipped with a gas ion source. The first implementation facilitates the direct measurement in the low sample size range (<10 μg C) with high throughput on a routine basis, while the second explores the potential for a continuous-flow real-time CO2 gas feed into the ion source. The performance achieved with reference materials and real atmospheric samples will be discussed to draw conclusions on the improvement offered in the field of 14C aerosol source apportionment.

  18. Isotopic analyses (/sup 18/O, /sup 13/C, /sup 14/C) of two meromictic lakes in the Canadian Arctic Archipelago

    SciTech Connect

    Page, P.; Ouellet, M.; Hillaire-Marcel, C.; Dickman, M.

    1984-05-01

    Meromictic Lakes Garrow and Sophia in the Canadian Arctic Archipelago were sampled to establish the origin and age of their water by isotopic studies. /sup 18/O values reflect the permanent stratification of the water in both lakes. The mixolimnia contain waters with an isotopic signal between -13.16 and -21.98%, coherent with the values for precipitation in these high latitudes. In the chemoclines, the delta/sup 18/O values increase to -10% concomitantly with a rise in chloride content to 42 g.liter/sup -1/. In the monimolimnia, hypersaline waters (up to 2.5 times the salinity of seawater) show negative delta/sup 18/O values (ca. -.08%). These waters result from brine production during permafrost growth in the watershed, according to a Rayleigh process. /sup 14/C dating of total inorganic carbon in the Lake Garrow monimolimnion gave an age of 2580 +/- 260 years BP. In Lake Sophia, the deep waters exhibit recent /sup 14/C activity that suggests recent infiltration of seawater into the lake basin.

  19. Imprint of CO2 emission in atmosphere and biosphere on the basis of 14C and 13C measurements

    NASA Astrophysics Data System (ADS)

    Pazdur, Anna; Gabryś, Alicja; Kuc, Tadeusz; Pawełczyk, Sławomira; Piotrowska, Natalia; Rakowski, Andrzej; Różański, Kazimierz; Sensuła, Barbara

    2015-04-01

    As is shown in the IPCC (Intergovernmental Panel on Climate Change) report, the observed climate changes are caused, among others, by human activity. Mainly emission of CO2 to the atmosphere coming from the burning of fossil fuels, can have dire consequences for life on Earth and development of humankind. The report uses, among others, data obtained from isotopic measurements in the biosphere. Measurements of 14C and 13C concentration in modern atmospheric carbon dioxide and biosphere allow the determination of the decrease of the concentration of this isotope. Furthermore, the magnitude of emission to the atmosphere of carbon dioxide not containing the isotope 14C can be estimated on this basis. Such emission stems from fossil fuel combustion - petroleum, natural gas and black coal. A sensitive bioindicator of the emission are annual tree rings. The measurements of 14C concentration in tree ring material using AMS allow to see its seasonal changes. Trees, treated as an archive of changes in conjunction with information about the isotopic composition of carbon can be used for monitoring of environment as sensitive bioindicators on local, as well as on the global scale. Regular investigations of isotopic composition of carbon in trees have been carried out in the GADAM Centre for the urban areas of both Poland and worldwide. This method can be applied in the study of the emission of CO2 to the atmosphere and its spatial and temporal distribution connected with the production of energy by power plants based on fossil fuel combustion for the area of southern Poland. Modelling of CO2 emission using both 14C and 13C carbon isotopes measured in pine tree rings on the background of climatic changes will be presented. The national ecological policy in the era of global warming requires the manufacturers of energy to get involved in the development of methods suitable for monitoring the state of the environment. Hence, the interest in the area of monitoring the fossil fuel

  20. Environmental history since 11,000 14C yr B.P. of the northeastern Pampas, Argentina, from alluvial sequences of the Luján River

    NASA Astrophysics Data System (ADS)

    Prieto, Aldo R.; Blasi, Adriana M.; De Francesco, Claudio G.; Fernández, Celina

    2004-09-01

    Sedimentological, malacological, and pollen analyses from 14C-dated alluvial sections from the Luján River provide a detailed record of environmental changes during the Holocene in the northeastern Pampas of Argentina. From 11,200 to 9000 14C yr B.P., both sedimentary and biological components suggest that the depositional environment was eutrophic, alkaline, and freshwater to brackish shallow water bodies without significant water circulation. During this time, bioclastic sedimentation was dominant and the shallow water bodies reached maximum development as the climate became more humid, suggesting an increase in precipitation. Short-term fluctuations in climate during the last stage of this interval may have been sufficient to initiate changes in the water bodies, as reduction of the volume alternated with periods of flooding. The beginning of the evolution of shallow swamps in the wide floodplain or huge wetlands was contemporaneous with a sea level lower than the present one. From 9000 and 7000 14C yr B.P., mesotrophic, alkaline, brackish, probably anoxic swamps existed. Between 7000 and 3000 14C yr B.P., anoxic calcareous swamps were formed, with subaerial exposure and development of the Puesto Berrondo Soil (3500-2900 14C yr B.P.). A trend to a reduction of water bodies is recorded from 9000 to ca. 3000 14C yr B.P., with a significant reduction after ca. 7000 14C yr B.P. A shift to subhumid-dry climate after 7000 14C yr B.P. appears to be the main cause. During this time, an additional external forcing toward higher groundwater levels was caused by Holocene marine transgression causing changes in the water bodies levels. The climate became drier during the late Holocene (ca. 3000 yr B.P.), when clastic sedimentation increased, under subhumid-dry conditions. Flood events increased in frequency during this time. From ca. A.D. 1790 to present, the pollen record reflects widespread disturbance of the vegetation during the European settlement.

  1. 14C release from a Soviet-designed pressurized water reactor nuclear power plant.

    PubMed

    Uchrin, G; Csaba, E; Hertelendi, E; Ormai, P; Barnabas, I

    1992-12-01

    The Paks Nuclear Power Plant in Hungary runs with four pressurized water reactors, each of 440-MWe capacity. Sampling systems have been developed and used to determine the 14C of various chemical forms (14CO2, 14CO, 14CnHm) in the airborne releases. The average normalized yearly discharge rates for the time period 1988-1991 are equal to 0.77 TBq GWe-1 y-1 for hydrocarbons and 0.05 TBq GWe-1 y-1 for CO2. The contribution of 14CO was less than 0.5% of the total emission. The 14C discharge rate is estimated to be four times higher than the corresponding mean data of Western European pressurized water reactors. The calculated effective dose equivalent to individuals living in the vicinity of the power plant, due to 14C release, was 0.64 microSv in 1991 while the effective dose equivalent due to the natural 14C level was 15 microSv y-1. The long-term global impact of the 14C release in the operational period of the plant (1982-1991) was 1,270 man-Sv. The 14C excess in the environmental air has been measured since 1989 by taking biweekly samples at a distance of 1.7 km from the nuclear power plant. The long-term average of radiocarbon excess coming from the power plant was 2 mBq m-3. The local 14C deposition was followed by tree ring analysis, too. No 14C increase higher than the uncertainty of the measurement (four per thousand = 0.17 mBq m-3) was observed.

  2. Fate of (14)C-organic pollutant residues in composted sludge after application to soil.

    PubMed

    Haudin, Claire-Sophie; Zhang, Yuhai; Dumény, Valérie; Lashermes, Gwenaëlle; Bergheaud, Valérie; Barriuso, Enrique; Houot, Sabine

    2013-08-01

    Organic micropollutants may be present in biosolids, leading to soil contamination when they are recycled in agriculture. A sludge spiked with (14)C-labelled glyphosate (GLY), sodium linear dodecylbenzene sulphonate (LAS), fluoranthene (FLT) or 4-n-nonylphenol (NP) was composted with green waste and the fate of the (14)C-micropollutant residues remaining after composting was assessed after the compost application to the soil. (14)C-residues were mineralised in the soil and represented after 140d 20-32% of the initial activity for LAS, 16-25% for GLY, 6-9% for FLT and 4-7% for NP. The (14)C-residues at the end of composting that could not be extracted with methanol or ammonia were minimally remobilised or even increased for FLT. After 140d, non-extractable residues represented 38-52% of all of the (14)C-residues remaining in the soil for FLT, 50-67% for GLY, 91-92% for NP and 94-97% for LAS and in most cases, less than 1% of the (14)C-residues were water soluble, suggesting a low direct availability for leaching and microbial or plant assimilation. FLT was identified as the main compound among the methanol-extractable (14)C-residues that may be potentially available. The fate of the (14)C-organic pollutant residues in composts after application to soil could be assessed through a sequential chemical extraction scheme and depended on the chemical nature of the pollutant.

  3. Seasonally Resolved Surface Water (delta)14C Variability in the Lombok Strait: A Coralline Perspective

    SciTech Connect

    Guilderson, T P; Fallon, S J; Moore, M D; Schrag, D P; Charles, C D

    2008-04-23

    We have explored surface water mixing in the Lombok Strait through a {approx}bimonthly resolved surface water {Delta}{sup 14}C time-series reconstructed from a coral in the Lombok Strait that spans 1937 through 1990. The prebomb surface water {Delta}{sup 14}C average is -60.5{per_thousand} and individual samples range from -72{per_thousand} to 134{per_thousand}. The annual average post-bomb maximum occurs in 1973 and is 122{per_thousand}. The timing of the post-bomb maximum is consistent with a primary subtropical source for the surface waters in the Indonesian Seas. During the post-bomb period the coral records regular seasonal cycles of 5-20{per_thousand}. Seasonal high {Delta}{sup 14}C occur during March-May (warm, low salinity), and low {Delta}{sup 14}C occur in September (cool, higher salinity). The {Delta}{sup 14}C seasonality is coherent and in phase with the seasonal {Delta}{sup 14}C cycle observed in Makassar Strait. We estimate the influence of high {Delta}{sup 14}C Makassar Strait (North Pacific) water flowing through the Lombok Strait using a two endmember mixing model and the seasonal extremes observed at the two sites. The percentage of Makassar Strait water varies between 16 and 70%, and between 1955 and 1990 it averages 40%. During La Nina events there is a higher percentage of Makassar Strait (high {Delta}{sup 14}C) water in the Lombok Strait.

  4. Fate of (14)C-organic pollutant residues in composted sludge after application to soil.

    PubMed

    Haudin, Claire-Sophie; Zhang, Yuhai; Dumény, Valérie; Lashermes, Gwenaëlle; Bergheaud, Valérie; Barriuso, Enrique; Houot, Sabine

    2013-08-01

    Organic micropollutants may be present in biosolids, leading to soil contamination when they are recycled in agriculture. A sludge spiked with (14)C-labelled glyphosate (GLY), sodium linear dodecylbenzene sulphonate (LAS), fluoranthene (FLT) or 4-n-nonylphenol (NP) was composted with green waste and the fate of the (14)C-micropollutant residues remaining after composting was assessed after the compost application to the soil. (14)C-residues were mineralised in the soil and represented after 140d 20-32% of the initial activity for LAS, 16-25% for GLY, 6-9% for FLT and 4-7% for NP. The (14)C-residues at the end of composting that could not be extracted with methanol or ammonia were minimally remobilised or even increased for FLT. After 140d, non-extractable residues represented 38-52% of all of the (14)C-residues remaining in the soil for FLT, 50-67% for GLY, 91-92% for NP and 94-97% for LAS and in most cases, less than 1% of the (14)C-residues were water soluble, suggesting a low direct availability for leaching and microbial or plant assimilation. FLT was identified as the main compound among the methanol-extractable (14)C-residues that may be potentially available. The fate of the (14)C-organic pollutant residues in composts after application to soil could be assessed through a sequential chemical extraction scheme and depended on the chemical nature of the pollutant. PMID:23545187

  5. Disposition of [14C]methyl bromide in Fischer-344 rats after oral or intraperitoneal administration.

    PubMed

    Medinsky, M A; Bond, J A; Dutcher, J S; Birnbaum, L S

    1984-09-14

    Methyl bromide is used as a disinfectant to fumigate soil. The intent of our study was to determine the disposition of methyl bromide following a single acute administration. Male Fischer-344 rats were given 250 mumol of [14C] methyl bromide/kg body wt by either oral or i.p. administration. Urine, feces and expired air were collected and at the end of 72 h the rats were sacrificed and tissues analyzed to determine 14C excretion and tissue distribution. After i.p. administration of methyl bromide, the dominant route of excretion was exhalation of 14CO2, with 46% of the dose exhaled as 14CO2. In contrast, urinary excretion of 14C was the major route of elimination (43% of the dose) when methyl bromide was given orally. Very little of the 14C appeared in the feces (less than 3% of the dose) regardless of route of administration. In rats with bile duct cannulations, 46% of an oral dose appeared in the bile over a 24-h period. Collection of bile significantly decreased the exhalation of 14CO2 and 14C excreted in urine compared to controls. At 72 h after oral or i.p. administration, 14-17% of the 14C remained in the rats, with liver and kidney being the major organs of retention. Results indicate that route of administration can affect the pathways for excretion. In addition, excretion of 14C in bile, coupled with the low levels of radioactivity found in the feces, indicates that reabsorption of biliary metabolites from the gut plays a significant role in the disposition of [14C] methyl bromide.

  6. ( sup 14 C)urea breath test for diagnosis of Helicobacter pylori

    SciTech Connect

    Ormand, J.E.; Talley, N.J.; Carpenter, H.A.; Shorter, R.G.; Conley, C.R.; Wilson, W.R.; DiMagno, E.P.; Zinsmeister, A.R.; Phillips, S.F. )

    1990-07-01

    H. pylori is a potent urease producer, a characteristic that has been exploited in the development of the (14C)- and (13C)urea breath tests. The prevalence of H. pylori infection also is known to increase with advancing age; however, the individual patient's age has not routinely been considered when interpreting urea breath test results. The aim of this study was to validate a short, age-adjusted (14C)urea breath test for use in diagnosing H. pylori infections. Forty-one subjects (28 volunteers, 13 patients) underwent esophagogastroduodenoscopy with biopsies. Subjects were defined as being H. pylori-positive if histology or culture was positive. In addition, all subjects completed a 120-min (14C)urea breath test. A logistic regression analysis adjusting for age was used to estimate the probability of H. pylori positivity as a function of the 14C values generated. Sixteen subjects were H. pylori-positive, and 25 were H. pylori-negative. The 14C values generated between 15 and 80 min were found to be equally predictive in identifying H. pylori-positive subjects. Advancing age was associated with a higher probability of H. pylori-positivity. By taking advantage of the statistical probabilities, older patients could be accurately diagnosed with H. pylori at lower 14C values. We found that (14C)urea breath test to be both a sensitive and specific test that can be abbreviated to a 30-min examination (total test time). Moreover, our mathematical model indicates that a patient's age should be considered in order to optimize interpretation of the (14C)urea breath test, although further observations are needed to confirm this model.

  7. [The effect of calcium pantothenate and homopantothenate on [14C]-GABA absorption by slices of rat cerebral cortex].

    PubMed

    Reĭtarova, T E; Rozanov, V A; Kovler, M A; Kopelevich, V M; Totskiĭ, V N

    1988-01-01

    Calcium D-pantothenate (Ca D-P) and calcium D-homopantothenate (Ca D-HP) (pantogam) exhibiting antagonism in a number tests of pharmacological screening were shown to inhibit the absorption of [14C]-GABA (0.2 microM) by the rat brain cortex slices (3 mm) incubated in calcium-free medium. The effect of Ca D-HP manifests at its low concentrations (10(-6) M) and that of Ca D-P at high concentrations (10(-6) M). The data obtained are discussed in relation to the possible influence of the anion and cation components of the studied compounds. PMID:3191967

  8. Age and geomorphic history of Meteor Crater, Arizona, from cosmogenic 36Cl and 14C in rock varnish

    USGS Publications Warehouse

    Phillips, F.M.; Zreda, M.G.; Smith, S.S.; Elmore, D.; Kubik, P.W.; Dorn, R.I.; Roddy, D.J.

    1991-01-01

    Using cosmogenic 36Cl buildup and rock varnish radiocarbon, we have measured the exposure age of rock surfaces at Meteor Crater, Arizona. Our 36Cl measurements on four dolomite boulders ejected from the crater by the impact yield a mean age of 49.7 ?? 0.85 ka, which is in excellent agreement with an average age of 49 ?? 3 ka obtained from thermoluminescence studies on shock-metamorphosed dolomite and quartz. These ages are supported by undetectably low 14C in the oldest rock varnish sample. ?? 1991.

  9. The 14C age of groundwater around saltwater-freshwater interface in deep coastal aquifer

    NASA Astrophysics Data System (ADS)

    Machida, I.; Ono, M.; Ikawa, R.; Koshigai, M.; Marui, A.

    2015-12-01

    This study is focused on determining the groundwater age in mixing zone around saltwater-freshwater interface in deep confined aquifer by 14C methods. A drilling up to 160m in depth was carried out with sampling geologic cores at a distance of 350m from coastal line. The elevation of the ground surface in the drilling site is about 4m, locates on the foot of Mt. Fuji, the highest mountain in Japan. The geology consists mainly of Quaternary, brittle volcanic rocks and fan deposits, and occasionally silt layers. The mixing zone of saltwater-freshwater was detected under 85m depth at the drilling site. A screen interval of the borehole was set from 151 to 157m depth and sampled the groundwater (hereafter called as FGB-water). The Cl- concentration of the FGB-water was 4,990 mg/L with NaCl type (approximately a quarter of salt water), indicating that FGB-water was taken from landward side of mixing zone around saltwater-freshwater interface. In addition to the drilling, the sampling of groundwater from more than 50 wells in the basin was carried out. The adjusted 14C age of FGB-water is estimated at approximately 10,000 years by fitting calculations. The ages of inland groundwater taken from almost same depth to FGB-water are 200-3,000 years. Although it is unclear why the FGB-water is much older than others, a likely explanation is due to the groundwater around saltwater-freshwater interface is moving upward roughly along the landward sloping interface (Cooper, 1964). Such movement would bring deeper and older groundwater to shallow zone. At the drilling site, the freshwater with low electric conductivity was obtained from surface to 84m depth. And they have much lighter stable isotopes (D and 18O) compared to those in inland. That is to say, the groundwater recharged at higher elevation distribute at shallow zone at the FGB. This result supports the upward moving of groundwater at the coastal area.

  10. AMS studies of the long-term turnover of 14C-labelled fat in man

    NASA Astrophysics Data System (ADS)

    Gunnarsson, M.; Mattsson, S.; Stenström, K.; Leide-Svegborn, S.; Erlandsson, B.; Faarinen, M.; Hellborg, R.; Kiisk, M.; Nilsson, L.-E.; Nosslin, B.; Persson, P.; Skog, G.; Åberg, M.

    2000-10-01

    To estimate the biokinetics of 14C-labelled fatty acids and the associated radiation absorbed dose to man, long-term retention of 14C from oral intake of glycerol tri[1- 14C]oleate (triolein) has been studied using accelerator mass spectrometry (AMS). As a complement to earlier reported data for three individuals, we present here results for one person from measurements up to 4.6 yr after administration, now also including 14C-levels in fat, muscle and bone. In this subject, a total of 44% of the administered activity was recovered in the exhaled air. Fasting increased the exhalation of 14C. The "excess" 14CO2 due to fasting had a half-life of about 400 d. AMS measurements on fat, muscle and bone biopsies taken from the same subject 4.5 yr after ingestion indicated that a small fraction of the administered activity was still present in fat. Also, bone tissue had a higher 14C specific activity than the current environmental level. No significantly increased level was found in the muscle sample.

  11. Lack of tissue renewal in human adult Achilles tendon is revealed by nuclear bomb (14)C.

    PubMed

    Heinemeier, Katja Maria; Schjerling, Peter; Heinemeier, Jan; Magnusson, Stig Peter; Kjaer, Michael

    2013-05-01

    Tendons are often injured and heal poorly. Whether this is caused by a slow tissue turnover is unknown, since existing data provide diverging estimates of tendon protein half-life that range from 2 mo to 200 yr. With the purpose of determining life-long turnover of human tendon tissue, we used the (14)C bomb-pulse method. This method takes advantage of the dramatic increase in atmospheric levels of (14)C, produced by nuclear bomb tests in 1955-1963, which is reflected in all living organisms. Levels of (14)C were measured in 28 forensic samples of Achilles tendon core and 4 skeletal muscle samples (donor birth years 1945-1983) with accelerator mass spectrometry (AMS) and compared to known atmospheric levels to estimate tissue turnover. We found that Achilles tendon tissue retained levels of (14)C corresponding to atmospheric levels several decades before tissue sampling, demonstrating a very limited tissue turnover. The tendon concentrations of (14)C approximately reflected the atmospheric levels present during the first 17 yr of life, indicating that the tendon core is formed during height growth and is essentially not renewed thereafter. In contrast, (14)C levels in muscle indicated continuous turnover. Our observation provides a fundamental premise for understanding tendon function and pathology, and likely explains the poor regenerative capacity of tendon tissue.

  12. Fate of 14C-ethyl prothiofos insecticide in canola seeds and oils.

    PubMed

    Abdel-Gawad, Hassan; Hegazi, Bahira

    2010-02-01

    Canola plants were treated with (14)C- prohiofos under conditions simulating local agricultural practices. (14)C-residues in seeds were determined at different time intervals. At harvest time about 32 % of (14)C-activity was associated with oil. The methanol soluble (14)C-residues accounted for 12 % of the total seed residues after further seeds extraction, while the cake contained about 49 % of the total residues. About 69 % of the (14)C-activity in the crude oil could be eliminated by simulated commercial processes locally used for oil refining. Chromatographic analysis of crude and refined oil revealed the presence of the parent compound together with three metabolites which were identified as prothiofos oxon, O-ethyl phosphorothioate and O-ethyl S-propyl phosphorothioate, besides one unknown compound. While methanol extract revealed the presence of despropylthio prothiofos and O-ethyl phosphoric acid as free metabolites acid hydrolysis of the conjugated metabolites in the methanol extract yielded 2, 4-dichlorophenole which was detected by color. When rats were fed the extracted cake for 72 hours, the bound residues were found to be bioavailable. The main excretion route was via the expired air (42 %), while the (14)C-residues excreted in urine and feces were 30 % and 11 %, respectively. The radioactivity detected among various organs accounted to 7.5 %.Chromatographic analysis of urine indicated the presence of prothiofos oxon, O-ethyl phosphoric acid and 2, 4-dichlorophenole as main degradation products of prothiofos in free and conjugated form.

  13. A simple method to determine mineralization of (14) C-labeled compounds in soil.

    PubMed

    Myung, Kyung; Madary, Michael W; Satchivi, Norbert M

    2014-06-01

    Degradation of organic compounds in soil is often determined by measuring the decrease of the parent compound and analyzing the occurrence of its metabolites. However, determining carbon species as end products of parent compound dissipation requires using labeled materials that allow more accurate determination of the environmental fate of the compound of interest. The current conventional closed system widely used to monitor degradation of (14) C-labeled compounds in soil is complex and expensive and requires a specialized apparatus and facility. In the present study, the authors describe a simple system that facilitates measurement of mineralization of (14) C-labeled compounds applied to soil samples. In the system, soda lime pellets to trap mineralized (14) C-carbon species, including carbon dioxide, were placed in a cup, which was then inserted above the treated soil sample in a tube. Mineralization of [(14) C]2,4-D applied to soil samples in the simple system was compared with that in the conventional system. The simple system provided an equivalent detection of (14) C-carbon species mineralized from the parent compound. The results demonstrate that this cost- and space-effective simple system is suitable for examining degradation and mineralization of (14) C-labeled compounds in soil and could potentially be used to investigate their mineralization in other biological matrices.

  14. 87Sr/86Sr as a quantitative geochemical proxy for 14C reservoir age in dynamic, brackish waters: assessing applicability and quantifying uncertainties.

    NASA Astrophysics Data System (ADS)

    Lougheed, Bryan; van der Lubbe, Jeroen; Davies, Gareth

    2016-04-01

    Accurate geochronologies are crucial for reconstructing the sensitivity of brackish and estuarine environments to rapidly changing past external impacts. A common geochronological method used for such studies is radiocarbon (14C) dating, but its application in brackish environments is severely limited by an inability to quantify spatiotemporal variations in 14C reservoir age, or R(t), due to dynamic interplay between river runoff and marine water. Additionally, old carbon effects and species-specific behavioural processes also influence 14C ages. Using the world's largest brackish water body (the estuarine Baltic Sea) as a test-bed, combined with a comprehensive approach that objectively excludes both old carbon and species-specific effects, we demonstrate that it is possible to use 87Sr/86Sr ratios to quantify R(t) in ubiquitous mollusc shell material, leading to almost one order of magnitude increase in Baltic Sea 14C geochronological precision over the current state-of-the-art. We propose that this novel proxy method can be developed for other brackish water bodies worldwide, thereby improving geochronological control in these climate sensitive, near-coastal environments.

  15. Metabolism of (2-14C)acetate and its use in assessing hepatic Krebs cycle activity and gluconeogenesis

    SciTech Connect

    Schumann, W.C.; Magnusson, I.; Chandramouli, V.; Kumaran, K.; Wahren, J.; Landau, B.R. )

    1991-04-15

    To examine the fate of the carbons of acetate and to evaluate the usefulness of labeled acetate in assessing intrahepatic metabolic processes during gluconeogenesis, (2-14C)acetate, (2-14C)ethanol, and (1-14C)ethanol were infused into normal subjects fasted 60 h and given phenyl acetate. Distributions of 14C in the carbons of blood glucose and glutamate from urinary phenylacetylglutamine were determined. With (2-14C)acetate and (2-14C)ethanol, carbon 1 of glucose had about twice as much 14C as carbon 3. Carbon 2 of glutamate had about twice as much 14C as carbon 1 and one-half to one-third as much as carbon 4. There was only a small amount in carbon 5. These distributions are incompatible with the metabolism of (2-14C)acetate being primarily in liver. Therefore, (2-14C)acetate cannot be used to study Krebs cycle metabolism in liver and in relationship to gluconeogenesis, as has been done. The distributions can be explained by: (a) fixation of 14CO2 from (2-14C)acetate in the formation of the 14C-labeled glucose and glutamate in liver and (b) the formation of 14C-labeled glutamate in a second site, proposed to be muscle. (1,3-14C)Acetone formation from the (2-14C)acetate does not contribute to the distributions, as evidenced by the absence of 14C in carbons 2-4 of glutamate after (1-14C)ethanol administration.

  16. Breath /sup 14/CO2 after intravenous administration of (/sup 14/C)aminopyrine in liver diseases

    SciTech Connect

    Pauwels, S.; Geubel, A.P.; Dive, C.; Beckers, C.

    1982-01-01

    The determination of of /sup 14/CO2 in breath after oral administration of (/sup 14/C)aminopyrine has been proposed as a quantitative liver function test. In order to shorten the procedure and avoid misinterpretations related to variable rates of intestinal absorption, the (/sup 14/C)aminopyrine breath test (ABT) was performed after intravenous administration of (/sup 14/C)aminopyrine in 21 controls and 89 patients with biopsy-proven liver disease. The specific activity of the first hour sample corrected for body weight (SA1) was the most discriminant expression of breath data. The SA1 value, expressed as the percentage of the administered dose, was 0.86 +/- 0.1% (mean +/- SD) in controls and significantly less in patients (0.46 +/- 0.31%). Low values were observed in patients with untreated chronic active hepatitis (0.16 +/- 0.13%), alcoholic cirrhosis (0.2 +/ 0.15%0, and untreated postnecrotic cirrhosis (0.47 +/- 0.17%). In contrast, normal values were obtained in chronic persistent hepatitis (0.86 +/- 0.13%) and 58% of noncirrhotic alcoholic liver diseases (0.83 +/- 0.27%). The results of duplicate studies were reproducible and SA1 correlated with other conventional liver function tests, including 45-min BSP retention. Among these, ABT was the most sensitive screening test for the presence of cirrhosis, especially in alcoholic patients, where it allowed a sharp distinction between cirrhotic and noncirrhotic cases. The results obtained in chronic hepatitis suggested that ABT may provide a reliable index of the activity of the disease. In our hands, intravenous ABT, performed over a 1-hr period, was a fast, sensitive, and discriminant liver function test.

  17. Radiocarbon dating of ancient rock paintings

    SciTech Connect

    Ilger, W.A.; Hyman, M.; Rowe, M.W.; Southon, J.

    1995-06-20

    This report presents progress made on a technique for {sup 14}C dating pictographs. A low-temperature oxygen plasma is used coupled with high-vacuum technologies to selectively remove C-containing material in the paints without contamination from inorganic carbon from rock substrates or accretions.

  18. Dating Violence

    MedlinePlus

    ... Parents of Teens Crime, Teens, and Trauma Assault Bullying and Harassment Child Sexual Abuse Dating Violence Sexual ... Parents of Teens Crime, Teens, and Trauma Assault Bullying and Harassment Child Sexual Abuse Dating Violence Sexual ...

  19. Measuring chlorophyll. cap alpha. and /sup 14/C-labeled photosynthate in aquatic angiosperms by the use of a tissue solubilizer. [/sup 14/C-labelled photosynthate

    SciTech Connect

    Beer, S.; Stewart, A.J.; Wetzel, R.G.

    1982-01-01

    A compound that quantitatively correlated with chlorophyll ..cap alpha.. could be measured fluorometrically in the extracts of leaves of three aquatic angiosperms (Myriophyllum heterophyllum Michx., Potamogeton crispus L., Elodea canadensis Michx.) treated with the tissue solubilizer BTS-450. Fluorescent characteristics of the solubilized plant tissues were stable for several weeks in the dark at temperatures up to 60/sup 0/C but rapidly degraded in sunlight or when acidified. /sup 14/C-Labeled photosynthate, which had been fixed by leaf discs during 1- to 10-hour exposure to H/sup 14/CO/sub 3/, was also readily extracted by the tissue solubilizer. Solubilizer extraction can, therefore, be used to determine both chlorophyll ..cap alpha.. content and /sup 14/C incorporation rates in the same leaf sample. The method is practical, because no grinding is required, the fluorescent characteristics of the extracts are stable, and analyses can be performed with very little plant material (about 3 milligrams).

  20. Persistence of the herbicides (/sup 14/C)chlorsulfuron and (/sup 14/C)metsulfuron methyl in prairie soils under laboratory conditions

    SciTech Connect

    Smith, A.E.

    1986-11-01

    Metsulfuron methyl, whose structure is closely related to that of chlorsulfuron, is currently being evaluated on the Canadian prairies as a postemergence treatment for the control of broadleaf weeds in cereal crops, in non-crop land and for brush control. Although applied postemergence, some of the herbicide will come into contact with the soil making it necessary to determine the fate of metsulfuron methyl in the soil. These studies were undertaken to investigate the rate of breakdown and the fate of (/sup 14/C)metsulfuron methyl in three soils under laboratory conditions where no leaching could occur. The rate of breakdown of (/sup 14/C)chlorsulfuron was also investigated in one of the soils.

  1. The effects of the oral administration of fish oil concentrate on the release and the metabolism of (/sup 14/C)arachidonic acid and (/sup 14/C)eicosapentaenoic acid by human platelets

    SciTech Connect

    Hirai, A.; Terano, T.; Hamazaki, T.; Sajiki, J.; Kondo, S.; Ozawa, A.; Fujita, T.; Miyamoto, T.; Tamura, Y.; Kumagai, A.

    1982-11-01

    It has been suggested by several investigators that eicosapentaenoic acid (C20:5 omega 3, EPA) might have anti-thrombotic effects. In this experiment, the effect of the oral administration of EPA rich fish oil concentrate on platelet aggregation and the release and the metabolism of (/sup 1 -14/C)arachidonic acid and ((U)-/sup 14/C)eicosapentaenoic acid by human platelets was studied. Eight healthy male subjects ingested 18 capsules of fish oil concentrate (EPA 1.4 g) per day for 4 weeks. Plasma and platelet concentrations of EPA markedly increased, while those of arachidonic acid (C20:4 omega 6, AA) and docosahexaenoic acid (C22:6 omega 3, DHA) did not change. Platelet aggregation induced by collagen and ADP was reduced. Collagen induced (/sup 14/C)thromboxane B2 (TXB2) formation from (/sup 14/C)AA prelabeled platelets decreased. There was no detectable formation of (/sup 14/C)TXB3 from (/sup 14/C)EPA prelabeled platelets, and the conversion of exogenous (/sup 14/C)EPA to (/sup 14/C)TXB3 was lower than that of (/sup 14/C)AA to (/sup 14/C)TXB2. The release of (/sup 14/C)AA from (/sup 14/C)AA prelabeled platelets by collagen was significantly decreased. These observations raise the possibility that the release of arachidonic acid from platelet lipids might be affected by the alteration of EPA content in platelets.

  2. Radiocarbon Dating

    SciTech Connect

    Buchholz, B A

    2007-12-20

    Radiocarbon dating can be used to determine the age of objects that contain components that were once alive. In the case of human remains, a radiocarbon date can distinguish between a crime scene and an archeological site. Documents, museum artifacts and art objects can be dated to determine if their age is correct for the historical context. A radiocarbon date does not confirm authenticity, but it can help identify a forgery.

  3. Relative sea-level trends along the coast of Maine during the past 5,000 [sup 14]C years

    SciTech Connect

    Gehrels, W.R.; Belknap, D.F. . Dept. of Geological Sciences); Kelley, J.T. ); Gong, B.; Pearce, B.R. . Dept. of Civil Engineering)

    1993-03-01

    Holocene differential crustal movements in coastal regions are best inferred by comparing slopes of relative sea-level curves from different coastal localities. Sea-level indicators must have a narrow vertical range that is precisely established in the modern environment. Their age must be determined with the highest degree of certainty; Accelerator Mass Spectrometry (AMS) [sup 14]C dating of very small samples minimizes the changes of mixing older and younger materials. Finally, when indicators not related to Mean Tide Level are used, a correction should be applied to account for changes in paleotidal range. This study reports on sea-level chronologies from three salt marshes along the coast of Maine: Well(43[degree]17 minutes N, 70[degree]34 minutes W), Phippsburg (43[degree]45 minutes N, 69[degree]49 minutes W), and Machiasport (44[degree]41 minutes N, 67[degree]24 minutes W). Radiocarbon dates number 44 for Wells (23 new: 7 conventional basal, 2 AMS basal), 21 for Phippsburg (11 new: 5 conventional basal, 3 AMS basal), and 11 for Machiasport (all new: 7 conventional basal, 4 AMS basal). All newly collected [sup 14]C samples were analyzed for associated foraminiferal assemblages. These fossil assemblages were then compared with the modern vertical zonation of salt marsh foraminifera that was established along transects in each marsh. In agreement with earlier studies from Nova Scotia marshes, a 100% Trochammina macrescens zone occurs within a narrow (20 cm) vertical range along the edge of the marshes in Maine (level of Highest High Water). In addition, Tiphotrocha comprimata is abundantly observed in a 30 cm vertical zone between Mean High Water (MHW) and Mean Higher High Water. After elevations of sea-level indicators were adjusted to a common datum (MHW), a final correction was applied to account for changes in tidal range using a numerical tidal model for the Gulf of Maine.

  4. Dating Violence

    ERIC Educational Resources Information Center

    Stader, David L.

    2011-01-01

    Dating violence is a form of student-on-student victimization and is a serious school safety issue. Research indicates that at a minimum, 10 percent of high school students are victims of dating violence in one form or another. Among female high school students that date, some data indicate that as many as 30 percent may be victims of dating…

  5. Changes in the 14C-Labeled Cell Wall Components with Chase Time after Incorporation of UDP[14C]Glucose by Intact Cotton Fibers 1

    PubMed Central

    Dugger, W. M.; Palmer, Raymond L.

    1988-01-01

    Intact, in vitro-grown cotton fibers will incorporate [14C]glucose from externally supplied UDP[14C]glucose into a variety of cell wall components including cellulose; this labeled fraction will continue to increase up to 4 hours chase time. In the fraction soluble in hot water there was no significant change in total label; however, the largest fraction after the 30 minute pulse with UDP[14C]glucose was chloroform-methanol soluble (70%) and showed a significant decrease with chase. The lipids that make up about 85% of this fraction were identified by TLC as steryl glucosides, acylated steryl glucosides, and glucosyl-phosphoryl-polyprenol. Following the pulse, the loss of label from acylated steryl glucosides and glucosylphophoryl-polyprenol was almost complete within 2 hours of chase; steryl glucosides made up about 85% of the fraction at that chase time. The total loss in the lipid fraction (about 100 picomoles per milligram dry weight of fiber) with chase times of 4 hours approximates the total gain in the total glucans. PMID:16666066

  6. Effect of cytochalasin B on 3-O-[(14)C]-methyl-D-glucose or D-[U-(14)C]glucose handling by BRIN-BD11 cells.

    PubMed

    Cetik, Sibel; Rzajeva, Aigun; Malaisse, Willy J; Sener, Abdullah

    2014-07-01

    The present study aimed to investigate the effects of cytochalasin B (20 μM) on the uptake of 3-O-[(14)C]-methyl-D-glucose or D-[U-(14)C]glucose (8.3 mM each) by BRIN-BD11 cells. Taking into account the distribution space of tritiated water ((3)HOH), which was unexpectedly increased shortly after exposure of the cells to cytochalasin B and then progressively returned to its control values, and that of L-[1-(14)C]glucose, used as an extracellular marker, it was demonstrated that cytochalasin B caused a modest, but significant inhibition of the uptake of D-glucose and its non-metabolized analog by the BRIN-BD11 cells. These findings resemble those observed in acinar or ductal cells of the rat submaxillary gland and displayed a relative magnitude comparable to that found for the inhibition of D-glucose metabolism by cytochalasin B in purified pancreatic islet B cells. These findings reinforce the view that the primary site of action of cytochalasin B is located at the level of the plasma membrane.

  7. Retrospective Birth Dating of Cells

    SciTech Connect

    L.Spalding, K; Bhardwaj, R D; Buchholz, B A; Druid, H; Frisen, J

    2005-04-19

    The generation of cells in the human body has been difficult to study and our understanding of cell turnover is limited. Extensive testing of nuclear weapons resulted in a dramatic global increase in the levels of the isotope {sup 14}C in the atmosphere, followed by an exponential decrease after the test ban treaty in 1963. We show that the level of {sup 14}C in genomic DNA closely parallels atmospheric levels, and can be used to establish the time point when the DNA was synthesized and cells were born. We use this strategy to determine the age of cells in the cortex of the adult human brain, and show that whereas non-neuronal cells are exchanged, occipital neurons are as old as the individual, supporting the view that postnatal neurogenesis does not take place in this region. Retrospective birth dating is a generally applicable strategy that can be used to measure cell turnover in man under physiological and pathological conditions.

  8. Low-level 14C methane oxidation rate measurements modified for remote field settings

    NASA Astrophysics Data System (ADS)

    Pack, M. A.; Pohlman, J.; Ruppel, C. D.; Xu, X.

    2012-12-01

    Aerobic methane oxidation limits atmospheric methane emissions from degraded subsea permafrost and dissociated methane hydrates in high latitude oceans. Methane oxidation rate measurements are a crucial tool for investigating the efficacy of this process, but are logistically challenging when working on small research vessels in remote settings. We modified a low-level 14C-CH4 oxidation rate measurement for use in the Beaufort Sea above hydrate bearing sediments during August 2012. Application of the more common 3H-CH4 rate measurement that uses 106 times more radioactivity was not practical because the R/V Ukpik cannot accommodate a radiation van. The low-level 14C measurement does not require a radiation van, but careful isolation of the 14C-label is essential to avoid contaminating natural abundance 14C measurements. We used 14C-CH4 with a total activity of 1.1 μCi, which is far below the 100 μCi permitting level. In addition, we modified field procedures to simplify and shorten sample processing. The original low-level 14C-CH4 method requires 6 steps in the field: (1) collect water samples in glass serum bottles, (2) inject 14C-CH4 into bottles, (3) incubate for 24 hours, (4) filter to separate the methanotrophic bacterial cells from the aqueous sample, (5) kill the filtrate with sodium hydroxide (NaOH), and (6) purge with nitrogen to remove unused 14C-CH4. Onshore, the 14C-CH4 respired to carbon dioxide or incorporated into cell material by methanotrophic bacteria during incubation is quantified by accelerator mass spectrometry (AMS). We conducted an experiment to test the possibility of storing samples for purging and filtering back onshore (steps 4 and 6). We subjected a series of water samples to steps 1-3 & 5, and preserved with mercuric chloride (HgCl2) instead of NaOH because HgCl2 is less likely to break down cell material during storage. The 14C-content of the carbon dioxide in samples preserved with HgCl2 and stored for up to 2 weeks was stable

  9. Reconstructing the Vertical 14C Gradient of the Baja Margin during the Last Deglaciation

    NASA Astrophysics Data System (ADS)

    Lindsay, C. M.; Lehman, S. J.; Marchitto, T. M.; Ortiz, J. D.; van Geen, A.

    2011-12-01

    The radiocarbon activity (Δ14C) of the atmosphere decreased in two steps during the last deglaciation, coinciding with the well-known Heinrich 1 (H1) and Younger Dryas (YD) stadials. A leading explanation for these periods of decline involves the release of 14C-depleted carbon from a deep, isolated ocean reservoir- a mechanism that may also help to explain the deglacial rise in atmospheric CO2. Reconstructions of intermediate water Δ14C near Baja California, Mexico (Marchitto et al., 2007 Science) and in the Arabian Sea (Bryan et al., 2010 Earth Planet. Sci. Lett.) document two intervals of extreme depletion relative to the coeval atmosphere during H1 and the YD that are interpreted as evidence of the return of this aged carbon from the deep reservoir to the upper ocean and atmosphere. Here we report on 14C measurements in additional cores from the Baja margin that expand the depth range of our observations and enable reconstruction of the vertical Δ14C gradient. Calendar ages were determined by (1) correlation of diffuse spectral reflectance (DSR, a proxy related to local productivity) with the layer-counted age model in the GISP2 ice core and (2) correlation of raw planktic G. ruber 14C ages to new measurements in core PC08 previously studied by Marchitto et al. (2007). Together these provide a common and consistent calendar age model for margin core PCO8 (depth 705 m), core PC13 from Soledad Basin (sill depth 290 m) and margin core GC38 (depth 1270 m). In preliminary results, G. ruber Δ14C data from PC08 exhibit a record of deglacial depletion events that is consistent with partial upward mixing of the intermediate-depth signal to the surface. Δ14C at 1270 meters showed relatively little change during H1 and YD, indicating that anomalously depleted water did not penetrate to this depth. The vertical gradient collapsed to within observational uncertainties at the start of the Bølling-Allerød/Antarctic Climate Reversal. Taken together the results support

  10. Applications of environmental 14C measured by AMS as a carbon tracer

    NASA Astrophysics Data System (ADS)

    Nakamura, Toshio; Nakai, Nobuyuki; Ohishi, Shoji

    1987-11-01

    AMS techniques have been applied to measure 14C concentrations, or Δ 14C values, of annual tree rings (1945-1983) of a Kiso hinoki tree grown in Gifu prefecture, and of acid-insoluble carbonaceous compounds extracted from cored sediments (surface to 30 cm deep) of Lake Biwa in Shiga prefecture. An increase in Δ 14C values was found for both tree rings and cored sediments, resulting from 14C artificially produced by nuclear weapon tests. Activities of 210Pb and 214Pb were measured to estimate the sedimentation rate of the Lake Biwa sediments and to provide a temporal control. A primitive model of carbon exchange between the troposphere, surface ocean water, and the biosphere was applied to the annual changes in Δ 14C of the hinoki tree rings and also of coral rings from Florida, USA. The times required to transfer bomb-carbon from the troposphere to surface sea water and to the biosphere were estimated to be about 11 and 23 years, respectively.

  11. Abundance of (14)C in biomass fractions of wastes and solid recovered fuels.

    PubMed

    Fellner, Johann; Rechberger, Helmut

    2009-05-01

    In recent years thermal utilization of mixed wastes and solid recovered fuels has become of increasing importance in European waste management. Since wastes or solid recovered fuels are generally composed of fossil and biogenic materials, only part of the CO(2) emissions is accounted for in greenhouse gas inventories or emission trading schemes. A promising approach for determining this fraction is the so-called radiocarbon method. It is based on different ratios of the carbon isotopes (14)C and (12)C in fossil and biogenic fuels. Fossil fuels have zero radiocarbon, whereas biogenic materials are enriched in (14)C and reflect the (14)CO(2) abundance of the ambient atmosphere. Due to nuclear weapons tests in the past century, the radiocarbon content in the atmosphere has not been constant, which has resulted in a varying (14)C content of biogenic matter, depending on the period of growth. In the present paper (14)C contents of different biogenic waste fractions (e.g., kitchen waste, paper, wood), as well as mixtures of different wastes (household, bulky waste, and commercial waste), and solid recovered fuels are determined. The calculated (14)C content of the materials investigated ranges between 98 and 135pMC.

  12. Intestinal absorption and tissue distribution of ( sup 14 C)pyrroloquinoline quinone in mice

    SciTech Connect

    Smidt, C.R.; Unkefer, C.J.; Houck, D.R.; Rucker, R.B. )

    1991-05-01

    Pyrroloquinoline quinone (PQQ) functions as a cofactor for prokaryotic oxidoreductases, such as methanol dehydrogenase and membrane-bound glucose dehydrogenase. In animals fed chemically defined diets, PQQ improves reproductive outcome and neonatal growth. Consequently, the present study was undertaken to determine the extent to which PQQ is absorbed by the intestine, its tissue distribution, and route of excretion. About 28 micrograms of PQQ (0.42 microCi/mumol), labeled with {sup 14}C derived from L-tyrosine, was administered orally to Swiss-Webster mice (18-20 g) to estimate absorption. PQQ was readily absorbed (62%, range 19-89%) in the lower intestine, and was excreted by the kidneys (81% of the absorbed dose) within 24 hr. The only tissues that retained significant amounts of ({sup 14}C)PQQ at 24 hr were skin and kidney. For kidney, it was assumed that retention of ({sup 14}C)PQQ represented primarily PQQ destined for excretion. For skin, the concentration of ({sup 14}C)PQQ increased from 0.3% of the absorbed dose at 6 hr to 1.3% at 24 hr. Furthermore, most of the ({sup 14}C)PQQ in blood (greater than 95%) was associated with the blood cell fraction, rather than plasma.

  13. Abundance of (14)C in biomass fractions of wastes and solid recovered fuels.

    PubMed

    Fellner, Johann; Rechberger, Helmut

    2009-05-01

    In recent years thermal utilization of mixed wastes and solid recovered fuels has become of increasing importance in European waste management. Since wastes or solid recovered fuels are generally composed of fossil and biogenic materials, only part of the CO(2) emissions is accounted for in greenhouse gas inventories or emission trading schemes. A promising approach for determining this fraction is the so-called radiocarbon method. It is based on different ratios of the carbon isotopes (14)C and (12)C in fossil and biogenic fuels. Fossil fuels have zero radiocarbon, whereas biogenic materials are enriched in (14)C and reflect the (14)CO(2) abundance of the ambient atmosphere. Due to nuclear weapons tests in the past century, the radiocarbon content in the atmosphere has not been constant, which has resulted in a varying (14)C content of biogenic matter, depending on the period of growth. In the present paper (14)C contents of different biogenic waste fractions (e.g., kitchen waste, paper, wood), as well as mixtures of different wastes (household, bulky waste, and commercial waste), and solid recovered fuels are determined. The calculated (14)C content of the materials investigated ranges between 98 and 135pMC. PMID:19157836

  14. In vitro synthesis and purification of UDP-( sup 14 C) galacturonate

    SciTech Connect

    Mitcham, E.J. ); Gross, K.C. ); Wasserman, B.P. )

    1989-04-01

    Pectins comprise a major component of the cell wall and much research has focused on degradation of pectins during ripening and senescence. However, little research has been conducted on pectin synthesis, partly due to a lack of commercial availability of UDP-({sup 14}C)galacturonic acid for use as a substrate in assaying galacturonan synthase. We report on the modification and integration of several procedures to synthesize UDP-({sup 14}C) galacturonic acid from commercially available UDP-({sup 14}C)glucuronic acid. A microsomal pellet containing UDP-D-glucuronate-4-epimerase was extracted from 5-day-old mung bean hypocotyls (Phaseolus aureus) and radish roots (Raphanus sativus L.) by ultracentrifugation at 30,000 rpm for 50 min. The UDP-({sup 14}C)galacturonic acid produced was separated from remaining UDP-({sup 14}C)glucuronic acid and other products by electrophoresis in pyridine:acetate:H{sub 2}O on silica gel. Spots were detected by autoradiography, eluted with 80% ethanol, and purified using anion exchange chromatography.

  15. Bioavailability of the Nano-Unit 14C-Agrochemicals Under Various Water Potential.

    PubMed

    Jung, S C; Kim, H G; Kuk, Y I; Ahn, H G; Senseman, S A; Lee, D J

    2015-08-01

    The study was conducted to investigate the effects of water potential on bioavailability of the nano-unit 14C-cafenstrole, 14C-pretilachlor, 14C-benfuresate, 14C-simetryn and 14C-oxyfluorfen applied with or without dimepiperate or daimuron under various water potential conditions. The highest bioavailable concentration in soil solution (BCSS) was found at 60% soil moisture, while the lowest occurred at 50% soil moisture for soil-applied alone or in combination. All water potential conditions differed significantly from each other with variations in total bioavailable amount in soil solution (TBSS) when either dimepiperate or daimuron were added to the soil, and changes were directly proportional to variations in water potential. Across all treatments, TBSS at 80% soil moisture was three to four times greater than that at 50% soil moisture when applied alone or in combination with dimepiperate or daimuron. Cafenstrole and simetryn had distribution coefficient (Kd) values <64 ml g-1 and a TBSS ranging from 10 to 44 ng g-1 soil, regardless of water potential conditions applied alone or in combination. Pretilachlor and benfuresate had Kd values <15 ml g-1 and a TBSS range of 38 to 255 ng g-1 soil when applied with or without dimepiperate or daimuron.

  16. Abundance of {sup 14}C in biomass fractions of wastes and solid recovered fuels

    SciTech Connect

    Fellner, Johann Rechberger, Helmut

    2009-05-15

    In recent years thermal utilization of mixed wastes and solid recovered fuels has become of increasing importance in European waste management. Since wastes or solid recovered fuels are generally composed of fossil and biogenic materials, only part of the CO{sub 2} emissions is accounted for in greenhouse gas inventories or emission trading schemes. A promising approach for determining this fraction is the so-called radiocarbon method. It is based on different ratios of the carbon isotopes {sup 14}C and {sup 12}C in fossil and biogenic fuels. Fossil fuels have zero radiocarbon, whereas biogenic materials are enriched in {sup 14}C and reflect the {sup 14}CO{sub 2} abundance of the ambient atmosphere. Due to nuclear weapons tests in the past century, the radiocarbon content in the atmosphere has not been constant, which has resulted in a varying {sup 14}C content of biogenic matter, depending on the period of growth. In the present paper {sup 14}C contents of different biogenic waste fractions (e.g., kitchen waste, paper, wood), as well as mixtures of different wastes (household, bulky waste, and commercial waste), and solid recovered fuels are determined. The calculated {sup 14}C content of the materials investigated ranges between 98 and 135 pMC.

  17. Modulation of (14) C-labeled glucose metabolism by zinc during aluminium induced neurodegeneration.

    PubMed

    Singla, Neha; Dhawan, D K

    2015-09-01

    Aluminium (Al) is one of the most prominent metals in the environment and is responsible for causing several neurological disorders, including Alzheimer's disease. On the other hand, zinc (Zn) is an essential micronutrient that is involved in regulating brain development and function. The present study investigates the protective potential of Zn in the uptake of (14) C-labeled amino acids and glucose and their turnover in rat brain slices during Al intoxication. Male Sprague Dawley rats (140-160 g) were divided into four different groups: normal control, Al treated (100 mg/kg body weight/day via oral gavage), Zn treated (227 mg/liter in drinking water), and Al + Zn treated. Radiorespirometric assay revealed an increase in glucose turnover after Al exposure that was attenuated after Zn treatment. Furthermore, the uptake of (14) C-labeled glucose was increased after Al treatment but was appreciably decreased upon Zn supplementation. In addition, the uptakes of (14) C-lysine, (14) C-leucine, and (14) C-aspartic acid were also found to be elevated following Al exposure but were decreased after Zn treatment. Al treatment also caused alterations in the neurohistoarchitecture of the brain, which were improved after Zn coadministration. Therefore, the present study suggests that Zn provides protection against Al-induced neurotoxicity by regulating glucose and amino acid uptake in rats, indicating that Zn could be a potential candidate for the treatment of various neurodegenerative disorders.

  18. An Inverse Method to Infer the Global Ocean Paleoventilation from the Atmospheric 14C Record

    NASA Astrophysics Data System (ADS)

    Marchal, O.; Hughen, K. A.; Muscheler, R.

    2001-12-01

    We present an inverse method to infer a record of global ocean ventilation (GOV) from records of atmospheric 14C activity (Δ 14C) and production. The method is based on the assimilation of activity and production data in a box model of the 14C cycle in the ocean-atmosphere-land biosphere system using the variational (adjoint) technique. It includes three components: (1) the model code that yields the value of the cost function (a measure of the misfit between observed and modelled Δ 14C); (2) the adjoint code that yields the partial derivatives of the cost function with respect to the parameters describing the temporal evolution of the GOV; and (3) an optimization procedure that yields the parameter values minimizing the cost function. Lagrange multipliers are introduced to simplify the calculation of the partial derivatives of the cost function and to construct the adjoint code directly from the model code. First we describe the method, outlining the formal similarities with the calculus of variation in analytical mechanics. Second we verify the method through the capability to recover a variety of GOV evolutions from the assimilation of artificial data ("twin experiments"). Third we apply the method to the Younger Dryas, using recent high-resolution records of Δ 14C from the Cariaco basin and of 10Be flux from Greenland ice cores. Our results give new insight into the role of the deep ocean circulation during this dramatic and rapid climate change in the circum North Atlantic area.

  19. Uptake and metabolism of (14C)-aspartate by developing kernels of maize (Zea mays L. )

    SciTech Connect

    Muhitch, M.J. )

    1990-05-01

    Pulse-chase experiments were performed to determine the metabolic fate of (14C)-aspartate in the pedicel region and subsequent uptake into the endosperm. Kernels were removed from the cob, leaving the pedicel attached but removing glumes, palea, and lemma. The basal tips were incubated in (14C)-aspartate for 0.5 h, followed by a 2 h chase period with unlabeled aspartate. In contrast to a previous study in which 70% of the 14C from aspartate was recovered in the organic acid fraction (Lyznik, et al., Phytochemistry 24: 425, 1985), only 20 to 25% of the radioactivity found in the 2 h chase period. While a small amount of the 14C transiently appeared in alanine at the beginning of the chase period, the most heavily labeled non-fed amino acid was glutamine, which accounted for 21% of the radioactivity within the pedicel amino acid fraction by 0.5 h into the chase period. There was no evidence for asparagine synthesis within the pedicel region of the kernel. 14C recovered from the endosperm in the form of amino acids were aspartate (60%), glutamine (20%), glutamate (15%), and alanine (5%). These results suggest that some of the maternally supplied amino acids undergo metabolic conversion to other amino acids before being taken up by the endosperm.

  20. Uptake and transfer of14C-simetryne through the laboratory freshwater food chain

    NASA Astrophysics Data System (ADS)

    Xu, Ying; Lay, J. P.; Zhang, Yongyuan

    1989-03-01

    This paper deals with the bioconcentration of14C-simetryne from water by aquatic test organisms: green algae— Monoraphidium minutum, rotifers— Brachionus rubens, daphnids— Daphnia magna, and fish— Brachydanio rerio. The chemical was bioconcentrated rapidly in all test species during the first 48 hours of experiment. The BCF values (bioconcentration factor) from all uptake studies show that simetryne has higher accumulation in algae than in rotifers, daphnids and zebra fish. The logarithm of the n-octanol/water partition coefficient of simetryne measured as 2.06±0.05 was correlated with the BCFs in the organisms as based on the lipid contents. 14C-simetryne uptake via the food-chain amounted to only 22% to 42% of the bioconcentration from water. Clearance of14C-derived residues from fish was rapid with a half-life of 2.1 days.

  1. Mobility Studies of (14)C-Chlorpyrifos in Malaysian Oil Palm Soils.

    PubMed

    Halimah, Muhamad; Ismail, B Sahid; Nashriyah, Mat; Maznah, Zainol

    2016-01-01

    The mobility of (14)C-chlorpyrifos using soil TLC was investigated in this study. It was found that chlorpyrifos was not mobile in clay, clay loam and peat soil. The mobility of (14)C-chlorpyrifos and non-labelled chlorpyrifos was also tested with silica gel TLC using three types of developing solvent hexane (100%), hexane:ethyl acetate (95:5, v/v); and hexane:ethyl acetate (98:2, v/v). The study showed that both the (14)C-labelled and non-labelled chlorpyrifos have the same Retardation Factor (Rf) for different developing solvent systems. From the soil column study on mobility of chlorpyrifos, it was observed that no chlorpyrifos residue was found below 5 cm depth in three types of soil at simulation rainfall of 20, 50 and 100 mm. Therefore, the soil column and TLC studies have shown similar findings in the mobility of chlorpyrifos.

  2. Mobility Studies of (14)C-Chlorpyrifos in Malaysian Oil Palm Soils.

    PubMed

    Halimah, Muhamad; Ismail, B Sahid; Nashriyah, Mat; Maznah, Zainol

    2016-01-01

    The mobility of (14)C-chlorpyrifos using soil TLC was investigated in this study. It was found that chlorpyrifos was not mobile in clay, clay loam and peat soil. The mobility of (14)C-chlorpyrifos and non-labelled chlorpyrifos was also tested with silica gel TLC using three types of developing solvent hexane (100%), hexane:ethyl acetate (95:5, v/v); and hexane:ethyl acetate (98:2, v/v). The study showed that both the (14)C-labelled and non-labelled chlorpyrifos have the same Retardation Factor (Rf) for different developing solvent systems. From the soil column study on mobility of chlorpyrifos, it was observed that no chlorpyrifos residue was found below 5 cm depth in three types of soil at simulation rainfall of 20, 50 and 100 mm. Therefore, the soil column and TLC studies have shown similar findings in the mobility of chlorpyrifos. PMID:26546229

  3. An analytical method for 14C in environmental water based on a wet-oxidation process.

    PubMed

    Huang, Yan-Jun; Guo, Gui-Yin; Wu, Lian-Sheng; Zhang, Bing; Chen, Chao-Feng; Zhang, Hai-Ying; Qin, Hong-Juan; Shang-Guan, Zhi-Hong

    2015-04-01

    An analytical method for (14)C in environmental water based on a wet-oxidation process was developed. The method can be used to determine the activity concentrations of organic and inorganic (14)C in environmental water, or total (14)C, including in drinking water, surface water, rainwater and seawater. The wet-oxidation of the organic component allows the conversion of organic carbon to an inorganic form, and the extraction of the inorganic (14)C can be achieved by acidification and nitrogen purging. Environmental water with a volume of 20 L can be used for the wet-oxidation and extraction, and a detection limit of about 0.02 Bq/g(C) can be achieved for water with carbon content above 15 mg(C)/L, obviously lower than the natural level of (14)C in the environment. The collected carbon is sufficient for measurement with a low level liquid scintillation counter (LSC) for typical samples. Extraction or recovery experiments for inorganic carbon and organic carbon from typical materials, including analytical reagents of organic benzoquinone, sucrose, glutamic acid, nicotinic acid, humic acid, ethane diol, et cetera., were conducted with excellent results based on measurement on a total organic carbon analyzer and LSC. The recovery rate for inorganic carbon ranged tween 98.7%-99.0% with a mean of 98.9(± 0.1)%, for organic carbon recovery ranged between 93.8% and 100.0% with a mean of 97.1(± 2.6)%. Verification and an uncertainty budget of the method are also presented for a representative environmental water. The method is appropriate for (14)C analysis in environmental water, and can be applied also to the analysis of liquid effluent from nuclear facilities. PMID:25590997

  4. Effect of foliar treatments on distribution of /sup 14/C-glyphosate in Convolvulus arvensis L

    SciTech Connect

    Lauridson, T.C.

    1986-01-01

    Field bindweed is a perennial weed which produces shoots from buds on its roots. Herbicides, such as glyphosate (N-(phosphonomethyl)glycine) used for control of field bindweed usually do not kill all shoot buds on the roots, thus field bindweed often reinfests areas within 3 to 6 weeks of treatment. This dissertation deals with the development of a technique to change glyphosate distribution in field bindweed roots and could result in less shoot regrowth after glyphosate application. In field studies eight plant growth regulators were applied in September, 3 days before 2.24 kg/ha of 2.4-D((2,4-dichlorophenoxy) acetic acid) or 1.68 kg/ha of glyphosate. Eight months later, regrowth of shoots was least where glyphosate was applied at 0.028 kg/ha as a pretreatment, followed by a standard rate of 1.68 kg/ha. In subsequent greenhouse studies, typical patterns of shoot growth and /sup 14/C-glyphosate distribution in isolated root sections taken from 15-week-old intact plants were determined. In subsequent growth chamber studies, plants were decapitated to observe the effect of shoot apical dominance on /sup 14/C-glyphosate translocation. After /sup 14/C-glyphosate was applied, intact plants had about twice as much /sup 14/C in distal root sections as in proximal or middle root sections. Decapitated plants had more /sup 14/C in proximal and middle root sections than in distal sections, and about twice as much /sup 14/C was translocated to roots of decapitated plants than intact plants. Eight concentrations of 2,4,-D or glyphosate from 1 to 5000 ppm were applied in logarithmic series to 6-week old plants.

  5. An analytical method for 14C in environmental water based on a wet-oxidation process.

    PubMed

    Huang, Yan-Jun; Guo, Gui-Yin; Wu, Lian-Sheng; Zhang, Bing; Chen, Chao-Feng; Zhang, Hai-Ying; Qin, Hong-Juan; Shang-Guan, Zhi-Hong

    2015-04-01

    An analytical method for (14)C in environmental water based on a wet-oxidation process was developed. The method can be used to determine the activity concentrations of organic and inorganic (14)C in environmental water, or total (14)C, including in drinking water, surface water, rainwater and seawater. The wet-oxidation of the organic component allows the conversion of organic carbon to an inorganic form, and the extraction of the inorganic (14)C can be achieved by acidification and nitrogen purging. Environmental water with a volume of 20 L can be used for the wet-oxidation and extraction, and a detection limit of about 0.02 Bq/g(C) can be achieved for water with carbon content above 15 mg(C)/L, obviously lower than the natural level of (14)C in the environment. The collected carbon is sufficient for measurement with a low level liquid scintillation counter (LSC) for typical samples. Extraction or recovery experiments for inorganic carbon and organic carbon from typical materials, including analytical reagents of organic benzoquinone, sucrose, glutamic acid, nicotinic acid, humic acid, ethane diol, et cetera., were conducted with excellent results based on measurement on a total organic carbon analyzer and LSC. The recovery rate for inorganic carbon ranged tween 98.7%-99.0% with a mean of 98.9(± 0.1)%, for organic carbon recovery ranged between 93.8% and 100.0% with a mean of 97.1(± 2.6)%. Verification and an uncertainty budget of the method are also presented for a representative environmental water. The method is appropriate for (14)C analysis in environmental water, and can be applied also to the analysis of liquid effluent from nuclear facilities.

  6. Application and detection of (14)c-hd in two mouse models.

    PubMed

    Logan, Thomas P; Shutz, Michael; Schulz, Susan M; Railer, Roy; Ricketts, Karen M; Casillas, Robert P

    2002-01-01

    The CD1-haired mouse and the SKH-hairless mouse are two animal models that have been used to evaluate sulfur mustard (HD) exposure and protection in our laboratory. In a recent study we observed that a substance P inhibitor protected the haired mouse ear against an HD solution, but the same drug was not successful in protecting the hairless mouse against HD vapor. This experiment prompted us to compare HD exposures between these models. We determined the (14)C content in the skin after exposures to HD containing (14)C-HD. Rate curves were generated for applications of (1) HD in methylene chloride to the haired mouse ear; (2) HD in methylene chloride to the hairless mouse dorsal skin; and (3) saturated HD vapor to the hairless mouse dorsal skin for 6 min. The curves showed a reduction in (14)C disintegrations per min in animals euthanized 0 to 2 h postexposure. The largest percentage of decrease of (14)C content in skin occurred within 30 min of HD challenge for all exposures. An 8-mm skin-punch biopsy and a 14-mm annular skin section surrounding the region of the 8-mm skin punch were taken from the hairless mouse dorsal skin exposed to HD in methylene chloride. The ratio of the (14)C content in the 8-mm skin punch to that in the surrounding 14-mm annular skin section was 7.3, demonstrating that the HD application spreads beyond the initially biopsied site. A concentration/time value of 6.3 mug/cm(2)/min was determined by counting skin (14)C disintegrations per minute in animals euthanized immediately after exposure to saturated HD vapor. Determinations of the amount of HD showed that similar quantities of HD, 0.4 mg, were detected on each model. These results contribute to a better quantitative understanding of HD application in the haired and hairless mouse models.

  7. Radiocarbon Dating.

    PubMed

    Van Strydonck, Mark

    2016-04-01

    Although most historians and art historians consider the radiocarbon dating technique not to be very precise by their criteria, the method has gained much importance over the last decades. Radiocarbon dating is increasingly used in the field of textile research and old polychrome statues, but also objects made of ivory, stucco, paper, and parchment are dated with the technique. Especially after the introduction of the AMS technique, a boom of this type of research has been noticed.

  8. Radiocarbon Dating.

    PubMed

    Van Strydonck, Mark

    2016-04-01

    Although most historians and art historians consider the radiocarbon dating technique not to be very precise by their criteria, the method has gained much importance over the last decades. Radiocarbon dating is increasingly used in the field of textile research and old polychrome statues, but also objects made of ivory, stucco, paper, and parchment are dated with the technique. Especially after the introduction of the AMS technique, a boom of this type of research has been noticed. PMID:27573138

  9. Mass spectrometric detection of radiocarbon for dating applications

    NASA Astrophysics Data System (ADS)

    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.

  10. Carbon and 14C distribution in tropical and subtropical agricultural soils

    NASA Astrophysics Data System (ADS)

    Prastowo, Erwin; Grootes, Pieter; Nadeau, Marie

    2016-04-01

    Paddy soil management affects, through the alternating anoxic and oxic conditions it creates, the transport and stabilisation of soil organic matter (SOM). Irrigation water may percolate more organic materials - dissolved (DOM) and colloidal - into the subsoil during anoxic conditions. Yet a developed ploughpan tends to prevent C from going deeper in the subsoil and partly decouple C distribution in top and sub soil. We investigate the influence of different soil type and environment. We observed the C and 14C distribution in paddy and non-paddy soil profiles in three different soil types from four different climatic regions of tropical Indonesia, and subtropical China. Locations were Sukabumi (Andosol, ca. 850 m a.s.l), Bogor (clayey Alisol, ca. 240 m a.s.l), and Ngawi (Vertisol, ca. 70 m a.s.l) in Jawa, Indonesia, and Cixi (Alisol(sandy), ca. 4 - 6 m a.s.l) in Zhejiang Province, China. We compared rice paddies with selected neighbouring non-paddy fields and employed AMS 14C as a tool to study C dynamics from bulk, alkali soluble-humic, and insoluble humin samples, and macrofossils (plant remains, charcoal). Our data suggest that vegetation type determines the quantity and quality of biomass introduced as litter and root material in top and subsoil, and thus contributes to the soil C content and profile, which fits the 14C signal distribution, as well as 13C in Ngawi with C4 sugar cane as upland crop. 14C concentrations for the mobile humic acid fraction were generally higher than for bulk samples from the same depth, except when recent plant and root debris led to high 14C levels in near-surface samples. The difference in sampling, - averaged layer for bulk sample and 1-cm layer thickness for point sample - shows gradients in C and 14C across the layers, which could be a reason for discrepancies between the two. High 14C concentrations - in Andosol Sukabumi up to 111 pMC - exceed the atmospheric 14CO2concentration in the sampling year in 2012 (˜ 103 pMC) and

  11. A study of placental transfer mechanisms in nonhuman primates using (/sup 14/C)phenylalanine

    SciTech Connect

    Pueschel, S.M.; Boylan, J.M.; Jackson, B.T.; Piasecki, G.J.

    1982-02-01

    Placental transfer mechanisms were investigated in pregnant Macaca Fascicularis and Macaca mulatta during the gestational age of 120 to 130 days. These primates underwent an operative procedure that allowed continuous fetal blood sampling. The administration of (/sup 14/C)phenylalanine into the maternal circulation revealed a significant increase of radioactive material in the fetal circulation, indicating an active placental transport mechanism unidirectional to the fetus. When (/sup 14/C)phenylalanine was injected into the fetus, radioactive aromatic amino acids in the maternal circulation increased only slightly over time, resembling a simple diffusion process.

  12. In vivo survival of (14C)sucrose-loaded porcine carrier erythrocytes

    SciTech Connect

    DeLoach, J.R.

    1983-06-01

    Porcine carrier erythrocyte survival was measured in adult pigs. (14C)Sucrose-loaded erythrocytes had a biphasic survival curve, with as much as 50% of the cells removed from circulation in the first 24 hours. The remaining cells had a 35-day half-life. Encapsulation values were measured for porcine erythrocytes and entrapment of (14C)sucrose was greater than 45%. Addition of inosine and glucose to the dialyzed cells and to the final wash buffer before reinjection of autologous cells did not improve their survival.

  13. Variations of 14C around AD 775 and AD 1795 - due to solar activity

    NASA Astrophysics Data System (ADS)

    Neuhäuser, R.; Neuhäuser, D. L.

    2015-12-01

    The motivation for our study is the disputed cause for the strong variation of 14C around AD 775. Our method is to compare the 14C variation around AD 775 with other periods of strong variability. Our results are: (a) We see three periods, where 14C varied over 200 yr in a special way showing a certain pattern of strong secular variation: after a Grand Minimum with strongly increasing 14C, there is a series of strong short-term drop(s), rise(s), and again drop(s) within 60 yr, ending up to 200 yr after the start of the Grand Minimum. These three periods include the strong rises around BC 671, AD 775, and AD 1795. (b) We show with several solar activity proxies (radioisotopes, sunspots, and aurorae) for the AD 770s and 1790s that such intense rapid 14C increases can be explained by strong rapid decreases in solar activity and, hence, wind, so that the decrease in solar modulation potential leads to an increase in radioisotope production. (c) The strong rises around AD 775 and 1795 are due to three effects, (i) very strong activity in the previous cycles (i.e. very low 14C level), (ii) the declining phase of a very strong Schwabe cycle, and (iii) a phase of very weak activity after the strong 14C rise - very short and/or weak cycle(s) like the suddenly starting Dalton minimum. (d) Furthermore, we can show that the strong change at AD 1795 happened after a pair of two packages of four Schwabe cycles with certain hemispheric leadership (each package consists of two Gnevyshev-Ohl pairs, respectively two Hale-Babcock pairs). We show with several additional arguments that the rise around AD 775 was not that special. We conclude that such large, short-term rises in 14C (around BC 671, AD 775, and 1795) do not need to be explained by highly unlikely solar super-flares nor other rare events, but by extra-solar cosmic rays modulated due to solar activity variations.

  14. A rapid phospholipase A2 bioassay using 14C-oleate-labelled E. coli bacterias.

    PubMed

    Meyer, T; von Wichert, P; Weins, D

    1989-02-01

    Two methods of phospholipase A2 determination using 14C-labelled E. coli bacterias as substrate were compared. One method works with a filter membrane for separation of cleaved 14C-oleate from remaining phospholipids, the other uses the well-known thin-layer chromatography for lipid analysis. Some features of human serum phospholipase A2 regarding pH and Ca2+ dependency were investigated. Possible sources of errors were discussed. It was shown that either method can differentiate between normal and pathologically elevated phospholipase A2 levels, but that the filter method is superior in terms of sensitivity and workload.

  15. Disposition of [14C]methyl bromide in rats after inhalation.

    PubMed

    Bond, J A; Dutcher, J S; Medinsky, M A; Henderson, R F; Birnbaum, L S

    1985-04-01

    Methyl bromide is used as a disinfectant to fumigate soil and a wide range of stored food commodities in warehouses and mills. Human exposure occurs during the manufacture and use of the chemical. The purpose of this investigation was to determine the disposition and metabolism of [14C]methyl bromide in rats after inhalation. Male Fischer-344 rats were exposed nose only to a vapor concentration of 337 nmol [14C]methyl bromide/liter air (9.0 ppm, 25 degrees C, 620 torr) for 6 hr. Urine, feces, expired air, and tissues were collected for up to 65 hr after exposure. Elimination of 14C as 14CO2 was the major route of excretion with about 47% (3900 nmol/rat) of the total [14C]methyl bromide absorbed excreted by this route. CO2 excretion exhibited a biphasic elimination pattern with 85% of the 14CO2 being excreted with a half-time of 3.9 +/- 0.1 hr (means +/- SE) and 15% excreted with a half-time of 11.4 +/- 0.2 hr. Half-times for elimination of 14C in urine and feces were 9.6 +/- 0.1 and 16.1 +/- 0.1 hr, respectively. By 65 hr after exposure, about 75% of the initial radioactivity had been excreted with 25% remaining in the body. Radioactivity was widely distributed in tissues immediately following exposure with lung (250 nmol equivalents/g), adrenal (240 nmol equivalents/g), kidney (180 nmol equivalents/g), liver (130 nmol equivalents/g), and nasal turbinates (110 nmol equivalents/g) containing the highest concentrations of 14C. Radioactivity in livers immediately after exposure accounted for about 17% of the absorbed methyl bromide. Radioactivity in all other tissues examined accounted for about 10% of the absorbed methyl bromide. Elimination half-times of 14C from tissues were on the order of 1.5 to 8 hr. In all tissues examined, over 90% of the 14C in the tissues was methyl bromide metabolites. The data from this study indicate that after inhalation methyl bromide is rapidly metabolized in tissues and readily excreted.

  16. Percutaneous absorption of (7. 10-/sup 14/C)benzo(a)pyrene and (7,12-/sup 14/C)dimethylbenz(a)anthracene in mice

    SciTech Connect

    Sanders, C.L.; Skinner, C.; Gelman, R.A.

    1984-04-01

    The percutaneous penetration, tissue distribution, and excretion of /sup 14/C-labeled benzo(a)pyrene (BaP) and dimethylbenz(a)anthracene (DMBA) were studied in mice. Both BaP and DMBA rapidly penetrated the skin and were excreted more in the feces than in the urine. The proportion of BaP or DMBA absorbed was less with increasing applied dose due to apparent saturation of the uptake process. Uptake from the dorsal skin of the nose was similar to uptake from the dorsal nuchal skin. 24 references.

  17. Distribution of root exudates and mucilage in the rhizosphere: combining 14C imaging with neutron radiography

    NASA Astrophysics Data System (ADS)

    Holz, Maire; Carminati, Andrea; Kuzyakov, Yakov

    2015-04-01

    Water and nutrients will be the major factors limiting food production in future. Plant roots employ various mechanisms to increase the access to limited soil resources. Low molecular weight organic substances released by roots into the rhizosphere increase nutrient availability by interactions with microorganisms, while mucilage improves water availability under low moisture conditions. Though composition and quality of these substances have intensively been investigated, studies on the spatial distribution and quantification of exudates in soil are scarce. Our aim was to quantify and visualize root exudates and mucilage distribution around growing roots using neutron radiography and 14C imaging depending on drought stress. Plants were grown in rhizotrons well suited for neutron radiography and 14C imaging. Plants were exposed to various soil water contents experiencing different levels of drought stress. The water content in the rhizosphere was imaged during several drying/wetting cycles by neutron radiography. The radiographs taken a few hours after irrigation showed a wet region around the root tips showing the allocation and distribution of mucilage. The increased water content in the rhizosphere of the young root segments was related to mucilage concentrations by parameterization described in Kroener et al. (2014). In parallel 14C imaging of root after 14CO2 labeling of shoots (Pausch and Kuzyakov 2011) showed distribution of rhizodeposits including mucilage. Three days after setting the water content, plants were labeled in 14CO2 atmosphere. Two days later 14C distribution in soil was imaged by placing a phosphor-imaging plate on the rhizobox. To quantify rhizodeposition, 14C activity on the image was related to the absolute 14C activity in the soil and root after destructive sampling. By comparing the amounts of mucilage (neutron radiography) with the amount of total root derived C (14C imaging), we were able to differentiate between mucilage and root

  18. Discovering forgeries of modern art by the 14C Bomb Peak

    NASA Astrophysics Data System (ADS)

    Caforio, L.; Fedi, M. E.; Mandò, P. A.; Minarelli, F.; Peccenini, E.; Pellicori, V.; Petrucci, F. C.; Schwartzbaum, P.; Taccetti, F.

    2014-01-01

    Exploiting the anomalous behaviour of the atmospheric radiocarbon concentration in the years after 1955 (so-called "Bomb Peak"), an alleged painting by Fernard Léger was unambiguously proven to be a fake just by dating the canvas support. Some art historians had questioned the authenticity of the painting, and their suspicions were fuelled by some scientific examinations of the paint materials (X-ray radiography, SEM-EDS), compared to those of another work unquestionably attributed to Léger. The decisive argument to prove that it was a fake was provided by the radiocarbon date obtained from a sample of canvas of the painting, using Accelerator Mass Spectrometry at the INFN-Labec laboratory in Florence. Beyond any doubt, the cotton plant from which the canvas was produced was cut no earlier than 1959, i.e. four years after Léger's death, thus definitely confirming the concerns of a fake.

  19. Estimate of recharge of a rising water table in semiarid Niger from 3H and 14C modeling.

    PubMed

    Favreau, Guillaume; Leduc, Christian; Marlin, Christelle; Dray, Martial; Taupin, Jean-Denis; Massault, Marc; Le, GalLaSalleCorinne; Babic, Milanka

    2002-01-01

    A hydrodynamic survey carried out in semiarid southwest Niger revealed an increase in the unconfined ground water reserves of approximately 10% over the last 50 years due to the clearing of native vegetation. Isotopic samplings (3H, 18O, 2H for water and 14C, 13C for the dissolved inorganic carbon) were performed on about 3500 km2 of this silty aquifer to characterize recharge. Stable isotope analyses confirmed the indirect recharge process that had already been shown by hydrodynamic surveys and suggested the tracers are exclusively of atmospheric origin. An analytical model that takes into account the long-term rise in the water table was used to interpret 3H and 14C contents in ground water. The natural, preclearing median annual renewal rate (i.e., recharge as a fraction of the saturated aquifer volume) lies between 0.04% and 0.06%. For representative characteristics of the aquifer (30 m of saturated thickness, porosity between 10% and 25%), this implies a recharge of between 1 and 5 mm/year, which is much lower than the estimates of 20 to 50 mm/year for recent years, obtained using hydrological and hydrodynamic methods and the same aquifer parameters. Our study, therefore, reveals that land clearing in semiarid Niger increased ground water recharge by about one order of magnitude.

  20. Radiocarbon dating organic detritus: Implications for studying ice sheet dynamics

    SciTech Connect

    Punning, J.; Rajamaee, R. . Inst. of Ecology)

    1993-01-01

    They present here a description of the [sup 14]C dating method used at the Institute of Geology, Estonian Academy of Science. They discuss results of geochronological studies of several stratigraphic sections, from which one estimates the age of the Late Weichselian (Late Valdaian) glacial maximum. [sup 14]C and paleobotanical data indicate that biodetrital materials comprise organic debris from various sources and suggests only a maximum age of investigated strata (16,000 BP).

  1. Sun, Ocean, Nuclear Bombs, and Fossil Fuels: Radiocarbon Variations and Implications for High-Resolution Dating

    NASA Astrophysics Data System (ADS)

    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.

  2. Determination of the Tissue Distribution and Excretion by Accelerator Mass Spectrometry of the Nonadecapeptide 14C-Moli1901 in Beagle dogs after Intratracheal Instillation

    SciTech Connect

    Rickert, D E; Dingley, K H; Ubick, E; Dix, K J; Molina, L

    2004-07-02

    Administration of {sup 14}C-Moli1901 (duramycin, 2622U90), a 19 amino acid polycyclic peptide by intratracheal instillation (approximately 100 {micro}g) into the left cranial lobe of the lung of beagle dogs resulted in retention of 64% of the dose in the left cranial lobe for up to 28 days. In this study, we used accelerator mass spectrometry (AMS) to quantify Moli901 following administration of only 0.045 {micro}Ci of {sup 14}C-Moli901 per dog. Limits of quantitation of AMS were 0.03 (urine) to 0.3 (feces) ng equiv. Moli1901/g. Whole blood and plasma concentrations of {sup 14}C were <5ng/ml at all times after the dose. Concentrations of {sup 14}C in whole blood and plasma declined over the first day after the dose and rose thereafter, with the rise in plasma concentrations lagging behind those in whole blood. During the first 3 days after the dose, plasma accounted for the majority of {sup 14}C in whole blood, but after that time, plasma accounted for only 25-30% of the {sup 14}C in whole blood. Tissue (left and right caudal lung lobe, liver, kidney, spleen, brain) and bile concentrations were low, always less than 0.25% the concentrations found in the left cranial lung lobe. Approximately 13% of the dose was eliminated in urine and feces in 28 days, with fecal elimination accounting for about 10% of the dose. The data presented here are consistent with that obtained in other species. Moli1901 is slowly absorbed and excreted from the lung, and it does not accumulate in other tissues. Moli1901 is currently in the clinic and has proven to be safe in single dose studies in human volunteers and cystic fibrosis patients by the inhalation route. No information on the disposition of the compound in humans is available. This study in dogs demonstrates the feasibility of obtaining that information using {sup 14}C-Moli1901 and AMS.

  3. Fate of organochlorine 14C-dicofol in a lab-scale wastewater treatment

    PubMed Central

    Oliveira, Jaime L. M.; Langenbach, Tomaz; Dezotti, Márcia

    2008-01-01

    The fate of organochlorine 14C-dicofol in activated sludge process was investigated. Results showed that the major part of radioactivity remained adsorbed on biological sludge. Consequently, its final disposal deserves special attention. The small amounts of dicofol, biotransformed or not, which remained in the treated effluent could contaminate receiving bodies. PMID:24031222

  4. 14C-most-probable-number method for enumeration of active heterotrophic microorganisms in natural waters.

    PubMed Central

    Lehmicke, L G; Williams, R T; Crawford, R L

    1979-01-01

    A most-probable-number method using 14C-labeled substrates is described for the enumeration of aquatic populations of heterotrophic microorganisms. Natural populations of microorganisms are inoculated into dilution replicates prepared from the natural water from which the organisms originated. The natural water is supplemented with a 14C-labeled compound added so as to approximate a true environmental concentration. 14CO2 evolved by individual replicates is trapped in NaOH and counted by liquid scintillation techniques for use in scoring replicates as positive or negative. Positives (14CO2 evolution) are easily distinguished from negatives (no 14CO2 evolution). The results from a variety of environments using the 14CO2 procedure agreed well with previously described methods, in most instances. The 14C-most-probable-number method described here reduces handling procedures over previously described most-probable-number procedures using 14C-labeled substrates. It also appears to have advantages over other enumeration methods in its attempt to approximate natural conditions more closely. PMID:120133

  5. Disposition of 14C-derived residues in tissues of pigs fed radiolabelled fumonisin B1.

    PubMed

    Prelusky, D B; Miller, J D; Trenholm, H L

    1996-01-01

    The uptake and distribution of radioactive material-derived residues were determined in tissues of growing pigs consuming 14C-labelled fumonisin B1 (FB1) in the diet. Animals were fed 3.0 mg (3.0 microCi) 14C-FB1/kg feed from days 1-12, followed by 2.0 mg (2.0 microCi) 14C-FB1/kg feed during days 13-24, followed by a 9-day withdrawal period where pigs received clean feed only. Of the tissues analysed, residues were found to accumulate only in liver and kidney. Radioactivity was detected at the first sampling time (day 3), and continued to increase until the 14C-toxin was removed from the diet. Peak tissue levels (dpm/g tissue +/- SD, N = 2) in liver and kidney were 347 +/- 28 and 146 +/- 14, respectively, on day 24, which were equivalent to about 160 and 65 ng FB1 and/or metabolites per g tissue, respectively. Once pigs were placed on clean feed, tissue levels declined rapidly; down to approximately 35% of peak levels after 3 days, and only marginally above detection limits (approximately 25 dpm/g) after 9 days. Delayed recovery of the radioactive material consumed indicated a persistence within the body of FB1-derived residues, which could be eliminated only upon removal of the contaminated diet. PMID:9064240

  6. Kinetics of the uptake of sup 14 C-labeled chlorinated benzenes from soil by plants

    SciTech Connect

    Topp, E.; Scheunert, I.; Korte, F. )

    1989-04-01

    ({sup 14}C)Benzene, ({sup 14}C)1,2,4-trichlorobenzene, ({sup 14}C)pentachlorobenzene, and ({sup 14}C)hexachlorobenzene were applied to soils in outdoor lysimeters to a 10-cm depth (2 mg/kg dry soil); barley and cress plants were grown for one vegetation period and analyzed after varying time intervals. The bioaccumulation factors (concentration of radioactive substances in plants divided by that in soils) of barley were higher than those of cress, except for hexachlorobenzene. In barley, bioaccumulation factors increased with decreasing chlorine content of the molecules, except for benzene, whereas in cress hexachlorobenzene exhibited the highest bioaccumulation factor. The conversion ratios of chlorinated benzenes (percentage of conversion products based on total radioactivity in plants) were negatively correlated to the chlorine content of the molecules and, in barley, positively correlated with time; in general, they were higher in barley than in cress. The concentration of radioactive substances in the plants, as well as bioaccumulation factors, decreased with time, except for a slight increase in benzene-derived residues in barley after 125 days. This effect is due to growth dilution. The percentage of radioactivity in barley seeds, based on that in the whole plant, was negatively correlated to the chlorine content of the molecule.

  7. Pharmacodynamic behavior of (/sup 14/C)acridine in the cricket Acheta domesticus (L. )

    SciTech Connect

    Walton, B.T.; Maggart, E.F. Jr.

    1981-11-01

    Cuticular and gastrointestinal penetration, in vivo metabolism, and excretion of (/sup 14/C)acridine were investigated in the nymphal cricket Acheta domesticus (L.) to find a pharmacodynamic basis for this insect's differential susceptibility to acridine at different life stages. Topically applied (/sup 14/C)acridine readily penetrated the cuticular exoskeleton of nymphs (half-time of penetration, 48 min). Radiolabeled compounds appeared in the hemolymph within 0.5 h after ingestion of (/sup 14/C)acridine and continued to move across the gut wall for 7.5 h. The biological half-time was 18 h and the rate constant for elimination was 0.039 h/sup -1/ after ingestion. Within 5 d after dosing, 97% of the dose was excreted. Several metabolites were present in the feces of nymphs fed (/sup 14/C)acridine, and less than 13% of the extractable radioactivity was parent compound. The cuticule and the gastrointestinal tract proved to be ineffective barriers to acridine entry in A. domesticus. However, the ability to readily metabolize and excrete acridine probably contributes to the higher acridine tolerance observed in the nymphs and adults than in the eggs, which are susceptible to toxic effects. Acridine is found in many coal and synthetic fuel by-products.

  8. Anaerobic oxidation of [1,2-14C]dichloroethene under Mn(IV)-reducing conditions

    USGS Publications Warehouse

    Bradley, P.M.; Landmeyer, J.E.; Dinicola, R.S.

    1998-01-01

    Anaerobic oxidation of [1,2-14C]dichloroethene to14CO2 under Mn(IV)-reducing conditions was demonstrated. The results indicate that oxidative degradation of partially chlorinated solvents like dichloroethene can be significant even under anoxic conditions and demonstrate the potential importance of Mn(IV) reduction for remediation of chlorinated groundwater contaminants.

  9. Uptake and transformation of soil [14C]-trinitrotoluene by cool-season grasses

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study investigated the fate and uptake of [14C]-TNT from soil into orchardgrass (Dactylis glomerata), perennial ryegrass (Lolium perenne) and tall fescue (Festuca arundinacea) over a one year period in a greenhouse-controlled environment. Pots (n=4 for each grass, containing 10 mg cold TNT/kg s...

  10. Decomposition of [14C]Lignocelluloses of Spartina alterniflora and a Comparison with Field Experiments

    PubMed Central

    Wilson, John O.

    1985-01-01

    Decomposition of lignocelluloses from Spartina alterniflora in salt-marsh sediments was measured by using 14C-labeled compounds. Rates of decomposition were fastest in the first 4 days of incubation and declined later. Lignins labeled in side chains were mineralized slightly faster than uniformly labeled lignins; 12% of the [side chain-14C]lignin-labeled lignocellulose was mineralized after 816 h of incubation, whereas only 8% of the [U-14C]lignin-labeled lignocelluloses were degraded during this period. The carbohydrate moiety within the lignocellulose complex was degraded about four times faster than the lignin moiety; after 816 h of incubation, 29 to 37% of the carbohydrate moiety had been mineralized. Changes in concentration of lignin and cellulose in litter of S. alterniflora were followed over 2 years of decay. Cellulose disappeared from litter more rapidly than lignin; 50% of the initial content of cellulose was lost after 130 days, whereas lignin required 330 to 380 days for 50% loss. The slow loss of lignin compared with other litter components resulted in a progressive enrichment of litter in lignin content. The rates of mineralization of [14C]lignocelluloses in marsh sediments were similar to the rates of lignocellulose decomposition in litter on the marsh. PMID:16346741

  11. Investigation of {sup 14}C release in an engineered low-level waste disposal facility

    SciTech Connect

    Yim, M.S.; Simonson, S.A.; Sullivan, T.M.

    1996-05-01

    Atmospheric releases of {sup 14}C from a generic engineered low-level waste (LLW) disposal facility and its radiological impacts are investigated. A computer model that describes microbial gas generation and the transport has been developed and used to analyze the generation of {sup 14}C contaminated gases and subsequent migration in a facility. Models are based on a chemical kinetic description of aerobic and anaerobic decomposition of organic materials coupled with attending models of oxygen transport and consumption within waste containers in a facility. Effects of radiolysis on gas generation are addressed based on the estimated dose rate for class B and C wastes. Estimates predict that annual atmospheric release of {sup 14}C due to atmospheric pressure variations could range between {approximately}2.6 {times} 10{sup 8} and 5.5 {times} 10{sup 11} Bq as a result of microbial gas generation based on a volume of 48 000 m{sup 3} LLW disposed in a facility. The associated dose to a maximally exposed individual is estimated to be dominated by ingestion pathway and strongly depends on the fraction of the food imported from an uncontaminated outside area. Dose rates are expected to be <0.04 mSv/yr, considering a reasonable distance between the facility and the exposed population. The depletion through airborne releases of {sup 14}C inventory that is available for transport through other pathways is not expected to be a significant issue.

  12. Movement of 14C-labeled Sugars into Kernels of Wheat (Triticum aestivum L.) 1

    PubMed Central

    Sakri, Faisal A. K.; Shannon, Jack C.

    1975-01-01

    An anatomical study of wheat (Triticum aestivum L.) kernels 14 days after anthesis revealed that the tracheary elements of the pericarp vascular bundle are not in direct continuity with those of the rachilla. The phloem was continuous from the rachilla into the crease of the pericarp. Shortly after exposure of the flag leaf to 14CO2, relatively high proportion of the 14C extracted from the pericarp and endosperm was found in glucose and fructose. With additional time, the percentage of 14C in the monosaccharides declined and that in sucrose increased to a maximum 3 hours after 14CO2 exposure. The monosaccharides comprised about one-half of the soluble sugars extracted from the pericarp. Based on these observations, it appeared that sucrose hydrolysis might be prerequisite to sugar movement from the terminal phloem elements in the pericarp and into the endosperm. However, when 14C-fructosyl-sucrose was injected into the peduncle, there was little additional randomization of the 14C between the glucose and fructose moieties of sucrose extracted from the pericarp and endosperm compared to the rachis sucrose. If we assume that injected sucose was transported to the kernels via the phloem, then either sucrose moves out of the terminal phloem elements in the pericarp and into the endosperm unaltered, or if hydrolysis and resynthesis are a prerequisite to transport into the endosperm, the products of hydrolysis are not freely available for isomerization. Images PMID:16659185

  13. Synthetic Studies toward the C14-C29 Fragment of Mirabalin.

    PubMed

    Cornil, Johan; Echeverria, Pierre-Georges; Reymond, Sébastien; Phansavath, Phannarath; Ratovelomanana-Vidal, Virginie; Guérinot, Amandine; Cossy, Janine

    2016-09-16

    A convergent synthesis of one isomer of the C14-C29 fragment of mirabalin is disclosed. The key steps include a Marshall allenylation, a Mukaiyama aldol reaction and a Crimmins aldolization, which allow the control of 10 out of 25 stereogenic centers present in the molecule. PMID:27602486

  14. Metabolism of U/sup 14/C palmitic and 1-/sup 14/C caproic acids by lettuce seeds during early germination

    SciTech Connect

    Salon, C.; Raymond, P.; Pradet, A.

    1986-04-01

    Germinating lettuce embryos (before radicule emergence) were fed with either U/sup 14/C palmitic acid or 1/sup 14/C caproic acid until a metabolic steady state was reached. The bulk of labelled caproate was evolved as respiratory CO/sub 2/ (52%) and incorporated into organic and amino acids (38%) and only a small part incorporated into lipids whereas most of labelled palmitic acid was found into lipids (92%) and only 8% evolved as CO/sub 2/ and incorporated into organic and amino acids. The label distribution at steady state in intermediates linked to the T.C.A. cycle was interpreted using a metabolic model. They found that the two fatty acids were degraded by ..beta..-oxidation and incorporated into the T.C.A. cycle as acetylCoA suggesting that ..beta..-oxidation is located in the mitochondria. The results also indicate that lipids contribute for at least 90% to the carbon supply to respiration.

  15. Using 14C to investigate Methane Production and DOC Reactivity in Northern Peatlands

    NASA Astrophysics Data System (ADS)

    Corbett, J.; Chanton, J.; Glaser, P.; Burdige, D.; Siegel, D.; Cooper, W.

    2008-12-01

    We found a consistent distribution pattern for radiocarbon in dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), and methane replicated across spatial and temporal scales in northern peatlands from Minnesota to Alaska. The 14C content of DOC is relatively modern throughout the peat column, to depths of 3 meters. In sedge-dominated peatlands, the 14C content of the products of respiration, CH4 and DIC are essentially the same, and are similar to that of DOC. In Sphagnum-woody plant dominated peatlands with few sedges, however, the respiration products are similar but intermediate between the 14C content of the solid-phase peat and the DOC. Preliminary data indicates qualitative differences in the pore-water DOC depending on the extent of sedge cover, consistent with the hypothesis that the DOC in sedge-dominated peatlands is more reactive than DOC in peatlands where Sphagnum or other vascular plants dominate. These data are supported by molecular-level analysis of DOC by ultrahigh resolution mass spectrometry which suggests dramatic changes with depth in the composition of DOC in the sedge-dominated peatland porewaters but not in porewaters where Sphagnum dominates. The higher reactivity of DOC from sedge- dominated peatlands may be a function of either different source materials or environmental factors that are related to the abundance of sedges in peatlands. To further investigate the reactivity of peat DOC in anaerobic methane producing environments, we are conducting size fractionation experiments for both the bog and fen samples. We will analyze resulting size fractions of DOC for radiocarbon. Previous research has shown that microorganisms tend to prefer HMW DOC to LMW DOC. Due to this, we believe that LMW DOC from both the bogs and the fens will result in radiocarbon values that are more depleted in 14C relative to HMW DOC. We hypothesize that the HMW DOC from the bogs will show depletion in 14C relative to HMW DOC in the fens. We further

  16. Bicarbonate exchange through the human red cell membrane determined with [14C] bicarbonate.

    PubMed

    Wieth, J O

    1979-09-01

    1. Bicarbonate transport across human red cell membranes was studied between 0 and 10 degrees C at alkaline pH values by determining the efflux of 14C-labelled bicarbonate from resealed erythrocyte ghosts. Transfer of labelled CO2 was eliminated as a source of error, when formation of intracellular 14CO2 was inhibited with carbonic anhydrase inhibitors. The study showed that there are no fundamental differences between the characteristics of bicarbonate and of chloride self-exchange as has been inferred from previous studies of chloride-bicarbonate exchange. 2. Efflux of radioactivity could be reduced more than 99% by reversible and irreversible inhibitors of anion transport. Inhibition of both chloride and bicarbonate self-exchange was linearly related to the binding of 4,4'-diisothiocyanostilbene-2,2'-disulphonic acid (DIDS) to the membranes. Complete (i.e. greater than 99%) inhibition was obtained after binding of 1.2 x 10(6) DIDS molecules per cell. 3. Bicarbonate self-exchange proved a saturable function of bicarbonate concentration, with a maximum at external and internal concentrations of approximately 100 mM, showing self-depression at higher bicarbonate concentrations, and half-maximum exchange flux at a concentration of 10 mM. The results were consistent with the hypothesis that the exchange mechanism has two anion binding sites, one mediating ion transport and the other causing transport inhibition. 4. Maximum exchange flux of bicarbonate was about 30% larger thant that of chloride, and the affinity of bicarbonate for the transport site was about three times larger than that of chloride. The apparent activation energy of bicarbonate exchange was 28 kcal/mole, the same order of magnitude as found for other inorganic anions between 0 and 10 degrees C. 5. The ability of other inorganic anions to exchange with bicarbonate decreased in the sequence Cl greater than NO3 greater than F greater than Br greater than or equal to I, corresponding to the sequence of

  17. Formation of Bound Residues during Microbial Degradation of [14C]Anthracene in Soil

    PubMed Central

    Kästner, M.; Streibich, S.; Beyrer, M.; Richnow, H. H.; Fritsche, W.

    1999-01-01

    Carbon partitioning and residue formation during microbial degradation of polycyclic aromatic hydrocarbons (PAH) in soil and soil-compost mixtures were examined by using [14C]anthracenes labeled at different positions. In native soil 43.8% of [9-14C]anthracene was mineralized by the autochthonous microflora and 45.4% was transformed into bound residues within 176 days. Addition of compost increased the metabolism (67.2% of the anthracene was mineralized) and decreased the residue formation (20.7% of the anthracene was transformed). Thus, the higher organic carbon content after compost was added did not increase the level of residue formation. [14C]anthracene labeled at position 1,2,3,4,4a,5a was metabolized more rapidly and resulted in formation of higher levels of residues (28.5%) by the soil-compost mixture than [14C]anthracene radiolabeled at position C-9 (20.7%). Two phases of residue formation were observed in the experiments. In the first phase the original compound was sequestered in the soil, as indicated by its limited extractability. In the second phase metabolites were incorporated into humic substances after microbial degradation of the PAH (biogenic residue formation). PAH metabolites undergo oxidative coupling to phenolic compounds to form nonhydrolyzable humic substance-like macromolecules. We found indications that monomeric educts are coupled by C-C- or either bonds. Hydrolyzable ester bonds or sorption of the parent compounds plays a minor role in residue formation. Moreover, experiments performed with 14CO2 revealed that residues may arise from CO2 in the soil in amounts typical for anthracene biodegradation. The extent of residue formation depends on the metabolic capacity of the soil microflora and the characteristics of the soil. The position of the 14C label is another important factor which controls mineralization and residue formation from metabolized compounds. PMID:10223966

  18. Characteristics of 14C and 13C of carbonate aerosols in dust storm events in China

    NASA Astrophysics Data System (ADS)

    Chen, Bing; Jie, Dongmei; Shi, Meinan; Gao, Pan; Shen, Zhenxing; Uchida, Masao; Zhou, Liping; Liu, Kexin; Hu, Ke; Kitagawa, Hiroyuki

    2015-10-01

    In contrast with its decrease in western China deserts, the dust storm event in eastern China, Korea, and Japan shows an increase in frequency. Although the drylands in northeastern China have been recognized as an important dust source, the relative contributions of dust transport from the drylands and deserts are inconclusive, thus the quantification of dust storm sources in downwind area remains a challenge. We measured the 14C and 13C contents in carbonates of dust samples from six sites in China, which were collected for the duration of dust storm events in drylands, deserts, and urban areas. The δ13C of the dryland dust samples considerably varied in a range of - 9.7 to - 5.0‰, which partly overlapped the desert dust carbonate δ13C ranges. The 14C content of the dryland dust carbonates showed a narrow range of 60.9 ± 4.0 (as an average and 1 SD of five samples) percent modern carbon (pMC), indicating the enrichment of modern carbonate. Dust samples in desert regions contained relatively aged carbonates with the depleting 14C showing of 28.8 ± 3.3 pMC. After the long-range transport of the western China desert dust plume, the carbonates collected at the southern China remained the depletion of 14C (33.5 ± 5.3 pMC) as in the desert regions. On the other hand, the samples of dust storm events at the urban areas of eastern China showed an enrichment of 14C contents (46.2 ± 5.0 pMC, n = 7), which might be explained by the stronger contribution of modern-carbonate-rich dryland dust.

  19. The Fate of Inhaled 14C-labelled PCB11 and its Metabolites In Vivo1

    PubMed Central

    Hu, Xin; Adamcakova-Dodd, Andrea; Thorne, Peter S.

    2014-01-01

    Background The production ban of polychlorinated biphenyl (PCB) technical mixtures has left the erroneous impression that PCBs exist only as legacy pollutants. Some lower-chlorinated PCBs are still being produced and contaminate both indoor and ambient air. Objectives To inform PCB risk assessment, we characterized lung uptake, distribution, metabolism and excretion of PCB11 as a signature compound for these airborne non-legacy PCBs. Methods After delivering [14C]PCB11 to the lungs of male rats, radioactivity in 34 major tissues and 5 digestive matter compartments was measured at 12, 25, 50, 100, 200 and 720 min postexposure, during which time the excreta and exhaled air were also collected. [14C]PCB11 and metabolites in liver, blood, digestive matter, urine and adipose tissues were extracted separately to establish the metabolic profile of the disposition. Results [14C]PCB11 was distributed rapidly to all tissues after 99.8% pulmonary uptake and quickly underwent extensive metabolism. The major tissue deposition of [14C]PCB11 and metabolites translocated from liver, blood and muscle to skin and adipose tissue 200 min postexposure, while over 50% of administered dose was discharged via urine and feces within 12 h. Elimination of the [14C]PCB11 and metabolites consisted of an initial fast phase (t½ = 9-33 min) and a slower clearance phase to low concentrations. Phase II metabolites dominated in liver, blood and excreta after 25 min postexposure. Conclusions This study shows that PCB11 is completely absorbed after inhalation exposure and is rapidly eliminated from most tissues. Phase II metabolites dominated with a slower elimination rate than the PCB11 or phase I metabolites and thus can best serve as urine biomarkers of exposure. PMID:24275706

  20. Recent chronologies for tree rings and terrestrial archives using 14C bomb fallout history

    NASA Astrophysics Data System (ADS)

    McGee, E. J.; Gallagher, D.; Mitchell, P. I.; Baillie, M.; Brown, D.; Keogh, S. M.

    2004-06-01

    Tree rings representing the period from the mid-1950s up to 2001 were studied as part of an investigation of anthropogenic radionuclide input to terrestrial systems. A live specimen of Pinus sylvestris from the east coast of Ireland was felled, sampled and analysed for comparison with a similar tree felled close to the Atlantic seaboard on the west coast of Ireland. Data for the tree ring sequences were examined relative to the radionuclide content of peat profiles sampled in close proximity to the locations of the studied Pine trees. The data indicate that 14C concentrations in tree ring sequences from the east and west coasts of Ireland are virtually identical. The sequences show maximum 14C concentrations (185 and 189 pMC at east and west coast sites, respectively) that correspond closely with published data for atmospheric levels during the height of the nuclear weapons test period (1945-1980). The tree ring count for the specimen from the east coast places the 14C peak precisely at 1964, the year following the known peak in atmospheric concentrations due to above ground testing of nuclear weapons. However, 14C data show that simple ring counting of the west coast tree did not provide an accurate chronology. The data demonstrate the importance of applying dendrodating techniques using replicated site chronologies, and the value of the 14C bomb fallout curve for the construction of recent chronologies. Data show no evidence of enhanced uptake at the east coast that might suggest incorporation of output from the Sellafield nuclear complex or from the release of radioactivity resulting from an accidental fire at the plant in 1957.

  1. Formation of bound residues during microbial degradation of [{sup 14}C]anthracene in soil

    SciTech Connect

    Kaestner, M.; Streibich, S.; Beyrer, M.; Fritsche, W.; Richnow, H.H.

    1999-05-01

    Carbon partitioning and residue formation during microbial degradation of polycyclic aromatic hydrocarbons (PAH) in soil and soil-compost mixtures were examined by using [{sup 14}C]anthracenes labeled at different positions. In native soil 43.8% of [9-{sup 14}C]anthracene was mineralized by the autochthonous microflora and 45.4% was transformed into bound residues within 176 days. Addition of compost increased the metabolism and decreased the residue formation (20.7% of the anthracene was transformed). Thus, the higher organic carbon content after compost was added did not increase the level of residue formation. [{sup 14}C]anthracene labeled at position 1,2,3,4,4a,5a was metabolized more rapidly and resulted in formation of higher levels of residues (28.5%) by the soil-compost mixture than [{sup 14}C]anthracene radiolabeled at position C-9 (20.7%). Two phases of residue formation were observed in the experiments. In the first phase the original compound was sequestered in the soil, as indicated by its limited extractability. In the second phase metabolites were incorporated into humic substances after microbial degradation of the PAH (biogenic residue formation). PAH metabolites undergo oxidative coupling to phenolic compounds to form nonhydrolyzable humic substance-like macromolecules. The authors found indications that monomeric educts are coupled by C-C- or either bonds. Hydrolyzable ester bonds or sorption of the parent compounds plays a minor role in residue formation. Moreover, experiments performed with {sup 14}CO{sub 2} revealed that residues may arise from CO{sub 2} in the soil in amounts typical for anthracene biodegradation. The extent of residue formation depends on the metabolic capacity of the soil microflora and the characteristics of the soil. The position of the {sup 14}C label is another important factor which controls mineralization and residue formation from metabolized compounds.

  2. Reconciling Change in Oi-Horizon 14C With Mass Loss for an Oak Forest

    SciTech Connect

    Hanson, P J; Swanston, C W; Garten, Jr., C T; Todd, D E; Trumbore, S E

    2005-06-27

    First-year litter decomposition was estimated for an upland-oak forest ecosystem using enrichment or dilution of the {sup 14}C-signature of the Oi-horizon. These isotopically-based mass-loss estimates were contrasted with measured mass-loss rates from past litterbag studies. Mass-loss derived from changes in the {sup 14}C-signature of the Oi-horizon suggested mean mass loss over 9 months of 45% which was higher than the corresponding 9-month rate extrapolated from litterbag studies ({approx}35%). Greater mass loss was expected from the isotopic approach because litterbags are known to limit mass loss processes driven by soil macrofauna (e.g., fragmentation and comminution). Although the {sup 14}C-isotope approach offers the advantage of being a non-invasive method, it exhibited high variability that undermined its utility as an alternative to routine litterbag mass loss methods. However, the {sup 14}C approach measures the residence time of C in the leaf litter, rather than the time it takes for leaves to disappear; hence radiocarbon measures are subject to C immobilization and recycling in the microbial pool, and do not necessarily reflect results from litterbag mass loss. The commonly applied two-compartment isotopic mixing model was appropriate for estimating decomposition from isotopic enrichment of near-background soils, but it produced divergent results for isotopic dilution of a multi-layered system with litter cohorts having independent {sup 14}C-signatures. This discrepancy suggests that cohort-based models are needed to adequately capture the complex processes involved in carbon transport associated with litter mass-loss. Such models will be crucial for predicting intra- and interannual differences in organic horizon decomposition driven by scenarios of climatic change.

  3. Pharmacokinetics and excretion of (14)C-omacetaxine in patients with advanced solid tumors.

    PubMed

    Nijenhuis, Cynthia M; Hellriegel, Edward; Beijnen, Jos H; Hershock, Diane; Huitema, Alwin D R; Lucas, Luc; Mergui-Roelvink, Marja; Munteanu, Mihaela; Rabinovich-Guilatt, Laura; Robertson, Philmore; Rosing, Hilde; Spiegelstein, Ofer; Schellens, Jan H M

    2016-10-01

    Background Omacetaxine mepesuccinate is indicated in adults with chronic myeloid leukemia resistant and/or intolerant to ≥ 2 tyrosine kinase inhibitor treatments. This phase I study assessed the disposition, elimination, and safety of (14)C-omacetaxine in patients with solid tumors. Methods The study comprised a 7-days pharmacokinetic assessment followed by a treatment period of ≤ six 28-days cycles. A single subcutaneous dose of 1.25 mg/m(2) (14)C-omacetaxine was administered to six patients. Blood, urine, and feces were collected through 168 h or until radioactivity excreted within 24 h was <1 % of the dose. Total radioactivity (TRA) was measured in all matrices and concentrations of omacetaxine, 4'-desmethylhomoharringtonine (4'-DMHHT), and cephalotaxine were measured in plasma and urine. For each treatment cycle, patients received 1.25 mg/m(2) omacetaxine twice daily for 7 days. Results Mean TRA recovered was approximately 81 % of the dose, with approximately half of the radioactivity recovered in feces and half in urine. Approximately 20 % of the dose was excreted unchanged in urine; cephalotaxine (0.4 % of dose) and 4' DMHHT (9 %) were also present. Plasma concentrations of TRA were higher than the sum of omacetaxine and known metabolites, suggesting the presence of other (14)C-omacetaxine-derived compounds. Fatigue and anemia were common, consistent with the known toxicity profile of omacetaxine. Conclusion Renal and hepatic processes contribute to the elimination of (14)C-omacetaxine-derived radioactivity in cancer patients. In addition to omacetaxine and its known metabolites, other (14)C-omacetaxine-derived materials appear to be present in plasma and urine. Omacetaxine was adequately tolerated, with no new safety signals. PMID:27221729

  4. Role of higher-multipole deformations in exotic {sup 14}C cluster radioactivity

    SciTech Connect

    Sawhney, Gudveen; Sharma, Manoj K.; Gupta, Raj K.

    2011-06-15

    We have studied nine cases of spontaneous emission of {sup 14}C clusters in the ground-state decays of the same number of parent nuclei from the trans-lead region, specifically from {sup 221}Fr to {sup 226}Th, using the preformed cluster model (PCM) of Gupta and collaborators, with choices of spherical, quadrupole deformation ({beta}{sub 2}) alone, and higher-multipole deformations ({beta}{sub 2}, {beta}{sub 3}, {beta}{sub 4}) with cold ''compact'' orientations {theta}{sup c} of decay products. The calculated {sup 14}C cluster decay half-life times are found to be in nice agreement with experimental data only for the case of higher-multipole deformations ({beta}{sub 2}-{beta}{sub 4}) and {theta}{sup c} orientations of cold elongated configurations. In other words, compared to our earlier study of clusters heavier than {sup 14}C, where the inclusion of {beta}{sub 2} alone, with ''optimum'' orientations, was found to be enough to give the best comparison with data, here for {sup 14}C cluster decay the inclusion of higher-multipole deformations (up to hexadecapole), together with {theta}{sup c} orientations, is found to be essential on the basis of the PCM. Interestingly, whereas both the penetration probability and assault frequency work simply as scaling factors, the preformation probability is strongly influenced by the order of multipole deformations and orientations of nuclei. The possible role of Q value and angular-momentum effects are also considered in reference to {sup 14}C cluster radioactivity.

  5. Substrate metabolism in isolated rat jejunal epithelium. Analysis using /sup 14/C-radioisotopes

    SciTech Connect

    Mallet, R.T.

    1986-01-01

    The jejunal epithelium absorbs nutrients from the intestinal lumen and is therefore the initial site for metabolism of these compounds. The purpose of this investigation is to analyze substrate metabolism in a preparation of jejunal epithelium relatively free of other tissues. Novel radioisotopic labelling techniques allow quantitation of substrate metabolism in the TCA cycle, Embden-Meyerhof (glycolytic) pathway, and hexose monophosphate shunt. For example, ratios of /sup 14/CO/sub 2/ production from pairs of /sup 14/C-pyruvate, and /sup 14/C-succinate radioisotopes (CO/sub 2/ ratios) indicate the probability of TCA cycle intermediate efflux to generate compounds other than CO/sub 2/. With (2,3-/sup 14/C)succinate as tracer, the ratio of /sup 14/C in carbon 4 + 5 versus carbon 2 + 3 of citrate, the citrate labelling ratio, equals the probability of TCA intermediate flux to the acetyl CoA-derived portion of citrate versus flux to the oxaloacetate-derived portion. The principal metabolic substrates for the jejunal epithelium are glucose and glutamine. CO/sub 2/ ratios indicate that glutamine uptake and metabolism is partially Na/sup +/-independent, and is saturable, with a half-maximal rate at physiological plasma glutamine concentrations. Glucose metabolism in the jejunal epithelium proceeds almost entirely via the Embden-Meyerhof pathway. Conversion of substrates to multi-carbon products in this tissue allows partial conservation of reduced carbon for further utilization in other tissues. In summary, metabolic modeling based on /sup 14/C labelling ratios is a potentially valuable technique for analysis of metabolic flux patterns in cell preparations.

  6. Integration of radiocarbon dating in the hydrodynamic scheme of north western Sahara aquifer system

    NASA Astrophysics Data System (ADS)

    Ould Baba Sy, M.; Besbes, M.

    2003-04-01

    Radiocarbon dating methods can be applied to obtain the age of ground water. Carbon exists in several naturally occurring isotopes, l2C, 13C, and 14C. Carbon 14 is formed in the atmosphere by the bombardment of 14N by cosmic radiation (DeVries 1959). The l4C forms CO2, so that the atmospheric CO2 has a constant radioactivity due to modern 14C. If the CO2 is incorporated into a form in which it is isolated from modern 14C, age determinations can be made from the 14C radioactivity as a percent of the original. The half-life of l4C is 5730 y, so that if one-fourth of the original activity is present, two half-lives, or 11,460 y, have elapsed. When precipitation soaks into the ground, it is saturated with respect to CO2, with a known 14C activity. Once the water has entered the soil, additional carbon may come from soil CO2 and the solution of carbonate minerals. The modern carbon is diluted by the inactive carbon from carbonate minerals. The raw dates obtained must be adjusted for this dilution. In the present research, we present a contribution of radiocarbon dating in the North Western Sahara Aquifer System, the NWSAS, shared by three countries (Algeria, Libya and Tunisia). This will be done while showing the utility of the log-linear function gotten by regression of some values representing the age of water by the activity of the carbon 14. This function has permitted to estimate the age of water for a sample of 72 water points. It leads, by interpolation on a cartographic support, to the distribution of the carbon 14 activities measured to the wells, translated in equivalent ages of water in the Continental Intercalaire aquifer, which is part of NWSAS and extends over one million square km. The reading of this ages map shows well the hydaulic behavior of the aquifer system.

  7. [Quantifying rice (Oryza sativa L.) photo-assimilated carbon input into soil organic carbon pools following continuous 14C labeling].

    PubMed

    Nie, San-An; Zhou, Ping; Ge, Ti-Da; Tong, Cheng-Li; Xiao, He-Ai; Wu, Jin-Shui; Zhang, Yang-Zhu

    2012-04-01

    The microcosm experiment was carried out to quantify the input and distribution of photo-assimilated C into soil C pools by using a 14C continuous labeling technique. Destructive samplings of rice (Oryza sativa) were conducted after labeling for 80 days. The allocation of 14C-labeled photosynthates in plants and soil C pools such as dissolved organic C (DOC) and microbial biomass C (MBC) in rice-planted soil were examined over the 14C labeling span. The amounts of rice shoot and root biomass C was ranged from 1.86 to 5.60 g x pot(-1), 0.46 to 0.78 g x pot(-1) in different tested paddy soils after labeling for 80 days, respectively. The amount of 14C in the soil organic C (14C-SOC) was also dependent on the soils, ranged from 114.3 to 348.2 mg x kg(-1), accounting for 5.09% to 6.62% of the rice biomass 14C, respectively. The amounts of 14C in the dissolved organic C (14C-DOC) and in the microbial biomass C(14C-MBC), as proportions of 14C-SOC, were 2.21%-3.54% and 9.72% -17.2%, respectively. The 14C-DOC, 14C-MBC, and 14C-SOC as proportions of total DOC, MBC, and SOC, respectively, were 6.72% -14.64%, 1.70% -7.67%, and 0.73% -1.99%, respectively. Moreover, the distribution and transformation of root-derived C had a greater influence on the dynamics of DOC and MBC than on the dynamics of SOC. Further studies are required to ascertain the functional significance of soil microorganisms (such as C-sequestering bacteria and photosynthetic bacteria) in the paddy system. PMID:22720588

  8. Influence of alternating soil drying and wetting on the desorption and distribution of aged 14C-labeled pesticide residues in soil organic fractions

    NASA Astrophysics Data System (ADS)

    Jablonowski, N. D.; Mucha, M.; Thiele, B.; Hofmann, D.; Burauel, P.

    2012-04-01

    A laboratory experiment was conducted to evaluate the effect of alternating soil drying and wetting on the release of aged 14C-labeled pesticide residues and their distribution in soil organic fractions (humic acids, fulvic acids, and humin substances). The used soils (gleyic cambisol; Corg 1.2%, pH 7.2) were obtained from the upper soil layer of two individual outdoor lysimeter studies containing either environmentally long-term aged 14C residues of the herbicide ethidimuron (ETD; 0-10 cm depth; time of aging: 9 years) or methabenzthiazuron (MBT; 0-30 cm depth; time of aging: 17 years). Triplicate soil samples (10 g dry soil equivalents) were (A=dry/wet) previously dried (45° C) or (B=wet/wet) directly mixed with pure water (1+2, w:w), shaken (150 rpm, 1 h), and centrifuged (~2000 g). The resulting supernatant was removed, filtered (0.45 μm) and subjected to 14C activity analysis via liquid scintillation counter (LSC), dissolved organic carbon (DOC) analysis, and LC-MS-MS analysis. This extraction procedure was repeated 15 individual times, for both setups (A) and (B). To determine the distribution of the aged 14C labelled pesticide residues in the soil organic matter fractions, the soil samples were subject to humic and fulvic acids fractionations at cycles 0, 4, 10, and 15. The residual pesticide 14C activity associated with the humic, fulvic, and humin substances (organic fraction remaining in the soil) fractions was determined via LSC. The water-extracted residual 14C activity was significantly higher in the extracts of the dry/wet, compared to the wet/wet soil samples for both pesticides. The total extracted 14C activity in the dry/wet soil extracts accounted for 51.0% (ETD) and 15.4% (MBT) in contrast to 19.0% (ETD) and 4.7% (MBT) in the wet/wet extracts after 15 water extractions. LC-MS-MS analysis revealed the parent compound ETD 27.9 μg kg-1 soil (dry/wet) and 10.7 μg kg-1 soil (wet/wet), accounting for 3.45 and 1.35% of total parent compound

  9. Influence of alternating soil drying and wetting on the desorption and distribution of aged 14C-labeled pesticide residues in soil organic fractions

    NASA Astrophysics Data System (ADS)

    Jablonowski, N. D.; Mucha, M.; Thiele, B.; Hofmann, D.; Burauel, P.

    2012-04-01

    A laboratory experiment was conducted to evaluate the effect of alternating soil drying and wetting on the release of aged 14C-labeled pesticide residues and their distribution in soil organic fractions (humic acids, fulvic acids, and humin substances). The used soils (gleyic cambisol; Corg 1.2%, pH 7.2) were obtained from the upper soil layer of two individual outdoor lysimeter studies containing either environmentally long-term aged 14C residues of the herbicide ethidimuron (ETD; 0-10 cm depth; time of aging: 9 years) or methabenzthiazuron (MBT; 0-30 cm depth; time of aging: 17 years). Triplicate soil samples (10 g dry soil equivalents) were (A=dry/wet) previously dried (45° C) or (B=wet/wet) directly mixed with pure water (1+2, w:w), shaken (150 rpm, 1 h), and centrifuged (~2000 g). The resulting supernatant was removed, filtered (0.45 μm) and subjected to 14C activity analysis via liquid scintillation counter (LSC), dissolved organic carbon (DOC) analysis, and LC-MS-MS analysis. This extraction procedure was repeated 15 individual times, for both setups (A) and (B). To determine the distribution of the aged 14C labelled pesticide residues in the soil organic matter fractions, the soil samples were subject to humic and fulvic acids fractionations at cycles 0, 4, 10, and 15. The residual pesticide 14C activity associated with the humic, fulvic, and humin substances (organic fraction remaining in the soil) fractions was determined via LSC. The water-extracted residual 14C activity was significantly higher in the extracts of the dry/wet, compared to the wet/wet soil samples for both pesticides. The total extracted 14C activity in the dry/wet soil extracts accounted for 51.0% (ETD) and 15.4% (MBT) in contrast to 19.0% (ETD) and 4.7% (MBT) in the wet/wet extracts after 15 water extractions. LC-MS-MS analysis revealed the parent compound ETD 27.9 μg kg-1 soil (dry/wet) and 10.7 μg kg-1 soil (wet/wet), accounting for 3.45 and 1.35% of total parent compound

  10. Changes in the level of ( sup 14 C)indole-3-acetic acid and ( sup 14 C)indoleacetylaspartic acid during root formation in mung bean cuttings. [Vigna radiata

    SciTech Connect

    Norcini, J.G.; Heuser, C.W. )

    1988-04-01

    Changes in the levels of ({sup 14}C)indole-3-acetic acid (IAA) and ({sup 14}C)indoleacetylaspartic acid (IAAsp) were examined during adventitious root formation in mung bean (Vigna radiata (L.) R. Wilcz. Berken) stem cuttings. IAAsp was identified by GC-MS as the primary conjugate in IAA-treated cuttings. During root formation in IAA-treated cuttings, the level of ({sup 14}C)IAAsp increased rapidly the first day and then declined; ({sup 14}C)IAA was rapidly metabolized and not detected after 12 hours.

  11. Study of the formation of biogenic speleothems found in submarine caves at the cape of Otranto, Italy, by 14C AMS

    NASA Astrophysics Data System (ADS)

    D'Elia, M.; Quarta, G.; Calcagnile, L.; Belmonte, G.

    2007-06-01

    Submarine caves at the Cape of Otranto, Italy, contain eccentric stalactites that were recently identified as entirely biogenic. One of these stalactites was sectioned along its longitudinal axis in order to select samples for radiocarbon dating. 14C AMS measurements provided fundamental information for the interpretation of the biogenic process and revealed that the formation of the stalactite continued for approximately 5000 years with a decrease in the longitudinal growth rate over time. Measurements of modern organisms were performed to assess the accuracy of the radiocarbon determinations, calibrated in calendar years by measuring the local marine reservoir age.

  12. Depth-dependence of the production rate of in-situ 14-C in quartz

    NASA Astrophysics Data System (ADS)

    Lupker, Maarten; Hippe, Kristina; Kober, Florian; Wacker, Lukas; Braucher, Régis; Bourlès, Didier; Vidal Romani, Juan; Wieler, Rainer

    2013-04-01

    Terrestrial cosmogenic nuclides provide a means to document and quantify the rates of changes of the landscape at the Earth's surface and have therefore received an increasing attention over the past decade. The short lived in-situ produced 14-C has recently emerged as a complement to other longer lived cosmogenic nuclides such as 10-Be or 26-Al. The short half-life (5730 yr) of 14-C makes it suitable to investigate surface processes such as denudation rates or sediment residence times on ka scales. The wide application of in-situ 14-C for quantitative studies is however bound to the proper calibration of its production mechanisms and rates. As other cosmogenic nuclides, 14-C is produced at the Earth's surface by nuclear reactions with incoming neutrons and muons. The production rate of 14-C has been determined for quartz exposed at the surface where neutrons dominate the overall production [1]. At depth, however, the muon production pathway starts to dominate, because the mean attenuation length of muons is considerably longer than that of neutrons. So far, the muon derived in-situ 14-C production rate is solely based on theoretical and experimental work [2] that has not been tested on natural objects. We measured the 14-C concentration in quartz along the Leymon High core (42.065 N, 7.014 E - alt: 1277 m; Northwestern Spain) using the ETH 14-C extraction line [3] and the MICADAS gas source AMS [4]. This core has been drilled down to 20 m in a quartz dyke and has already been used to refine the depth-dependent production rate of 10-Be and 26-Al [5]. Our results on 14 samples of this core spanning a depth range from 1 to 1545 cm allow us to estimate the muogenic contribution to the overall 14-C concentrations measured along the core. This data set yields a local surface muon production rate of 3.9 (+3.1, -0.6) at.g-1.yr-1, which translates into a surface Sea Level High Latitude muon production rate of 2.2 (+1.8, -0.4) at.g-1.yr-1. This is ca. 17 % of the SLHL

  13. Auxin Transport in Zea mays Coleoptiles II. Influence of Light on the Transport of Indoleacetic Acid-2-14C

    PubMed Central

    Naqvi, S. M.; Gordon, S. A.

    1967-01-01

    The effect of bilateral irradiation with white light (1000 Meter Candle Sec) on the basipetal transport of auxin has been investigated. Illumination of either the intact shoot or the excised coleoptile tip of the Zea seedling, decreased the amount of diffusible auxin obtained from the tip, and decreased Avena curvature response to unilaterally applied indoleacetic acid. Irradiation of the intact Zea seedling did not affect the absorption of 14C-labeled indoleacetic acid from an agar block subsequently placed on the decapitated coleoptile. However, light caused a significant decrease in the amount of labeled auxin basipetally transported, without affecting materially the velocity of that transport. These and other observations are interpreted as support for the hypothesis that the primary hormonal phenomenon in first-positive phototropism is a light-induced impairment in the basipetal transport of auxin. PMID:16656477

  14. The impact of geomagnetic spikes on the production rates of cosmogenic 14C and 10Be in the Earth's atmosphere

    NASA Astrophysics Data System (ADS)

    Fournier, Alexandre; Gallet, Yves; Usoskin, Ilya; Livermore, Philip W.; Kovaltsov, Gennady A.

    2015-04-01

    We seek corroborative evidence of the geomagnetic spikes detected in the Near East ca. 980 BC and 890 BC in the records of the past production rates of the cosmogenic nuclides 14C and 10Be. Our forward modeling strategy rests on global, time-dependent, geomagnetic spike field models feeding state-of-the-art models of cosmogenic nuclide production. We find that spike models with an energy budget in line with presently inferred large-scale flow at Earth's core surface fail to produce a visible imprint in the nuclide record. Spike models able to reproduce the intensity changes reported in the Near East require an unaccountably high-magnitude core flow, yet their computed impact on cosmogenic isotope production rates remains ambiguous. No simple and unequivocal agreement is obtained between the observed and modeled nuclide records at the epochs of interest. This indicates that cosmogenic nuclides cannot immediately be used to confirm the occurrence of these two geomagnetic spikes.

  15. Tree-ring 14C and CO2 emissions at Mammoth Mountain and Yellowstone, USA

    NASA Astrophysics Data System (ADS)

    Bergfeld, D.; McGeehin, J. P.; King, J.; Heasler, H.; Evans, W. C.

    2010-12-01

    A large pulse of magmatic CO2 began venting through soils on the flanks of Mammoth Mountain CA within months of a local seismic swarm in 1989. Previous workers have shown that the CO2 efflux rate was large enough to kill ~0.5 km2 of forest and cause substantial depletion of 14C in the wood of surviving trees at the edges of the kill zones. CO2 efflux at Mammoth Mountain continues to be well-studied, in part because of the obvious link between the seismic swarm and the onset of outgassing. A somewhat similar event apparently occurred a decade previously in the Yellowstone caldera, where we see a record of 14C depletion of 10-25% in a tree at Cooking Hillside in the Mud Volcano area. The 14C levels in tree core data show that CO2 emissions began to increase during a local seismic swarm in 1978. A huge drop in 14C in the 1979 growth ring suggests that CO2 emissions increased about 5-fold over values earlier in the decade. The emissions spike persisted into 1980 but at greatly reduced levels. This event at Mud Volcano occurred in a thermal area long known to emit CO2 gas and was associated with a substantial increase in surface heating and steam emission, in contrast to the case of Mammoth Mountain. However, the two events share some important similarities: increased CO2 emissions began within months of the onset of shallow (<7 km) seismic swarms, emissions peaked within 1-2 years later, and peak emissions are estimated at ~1000 tonnes of CO2 per day. Seismicity in both cases was likely driven by CO2-rich hydrous fluids; intrusion of magma into the shallow crust seems unlikely, particularly at Yellowstone where the youngest intra-caldera lavas are 70 ka. These similarities imply that, while each event has unique attributes, both are more likely variants on a process that may be fairly common in areas of magmatism. Additional tree coring at Mammoth Mountain will allow a direct comparison between 14C depletion and annual CO2 flux surveys. Ongoing tree-core 14C studies at

  16. Transformation of (sup14)C-Lignin-Labeled Cell Walls of Wheat by Syntrophococcus sucromutans, Eubacterium oxidoreducens, and Neocallimastix frontalis

    PubMed Central

    Bernard-Vailhe, M. A.; Besle, J. M.; Dore, J.

    1995-01-01

    Wheat cell walls, saponified or not, labeled with [U-(sup14)C]phenylalanine or [O-methyl-(sup14)C]sinapate were fermented by Neocallimastix frontalis or Syntrophococcus sucromutans plus Eubacterium oxidoreducens or a mixed culture. Phenolics were less solubilized but more transformed by bacteria than by the fungus, and mineralization was slight. S. sucromutans O-demethylated [O-methyl-(sup14)C]syringyl lignins, yielding labeled acetate. PMID:16534916

  17. Modeling of irradiated graphite (14)C transfer through engineered barriers of a generic geological repository in crystalline rocks.

    PubMed

    Poskas, Povilas; Grigaliuniene, Dalia; Narkuniene, Asta; Kilda, Raimondas; Justinavicius, Darius

    2016-11-01

    There are two RBMK-1500 type graphite moderated reactors at the Ignalina nuclear power plant in Lithuania, and they are under decommissioning now. The graphite cannot be disposed of in a near surface repository, because of large amounts of (14)C. Therefore, disposal of the graphite in a geological repository is a reasonable solution. This study presents evaluation of the (14)C transfer by the groundwater pathway into the geosphere from the irradiated graphite in a generic geological repository in crystalline rocks and demonstration of the role of the different components of the engineered barrier system by performing local sensitivity analysis. The speciation of the released (14)C into organic and inorganic compounds as well as the most recent information on (14)C source term was taken into account. Two alternatives were considered in the analysis: disposal of graphite in containers with encapsulant and without it. It was evaluated that the maximal fractional flux of inorganic (14)C into the geosphere can vary from 10(-11)y(-1) (for non-encapsulated graphite) to 10(-12)y(-1) (for encapsulated graphite) while of organic (14)C it was about 10(-3)y(-1) of its inventory. Such difference demonstrates that investigations on the (14)C inventory and chemical form in which it is released are especially important. The parameter with the highest influence on the maximal flux into the geosphere for inorganic (14)C transfer was the sorption coefficient in the backfill and for organic (14)C transfer - the backfill hydraulic conductivity.

  18. Utilization of [14C]phenylalanine derived from arylphorin or free amino acid in Manduca sexta pharate adults

    NASA Technical Reports Server (NTRS)

    Wu, M.; Tischler, M. E.

    1995-01-01

    The role of arylphorin as a storage protein was studied using 14C-arylphorin. 14C-arylphorin was produced optimally by incubating one-half fat body from Manduca sexta fifth instar larvae at 22 degrees C for 24 h, in 1 ml of medium containing amino acids at 25% of their physiological concentration with [U-14C]-phenylalanine (phe) provided initially without nonlabeled phenylalanine. Nonlabeled phe was provided after 1 h at 16% of its physiological concentration. The specific activity of 14C-arylphorin produced in vitro was 30 times greater than that generated in vivo. Injection of 14C-arylphorin into pharate adults was used to study the distribution of 14C-phe derived from this protein into 14CO2 and tissues for comparison with injection of free 14C-phe during the middle (days 6 to 12 pharate adult) and late (days 12 to 17 pharate adult) stages of adult development. Appearance of 14CO2 from 14C-arylphorin as compared to 14C-phenylalanine showed a slower time course during both the middle and late stages of development, in keeping with the time needed for degradation of the protein. In accord with faster phe turnover near the end of adult development, total 14CO2 production was greater and the retention of 14C in hemolymph and fat body was less compared to the middle stage of development regardless of whether 14C-arylphorin or 14C-phe was injected. In the middle stage of development, the appearance of 14C in the cuticle and head parts was greater, whereas incorporation into abdomen and thorax was less than during the late stage of development. Since the pattern of 14C distribution from 14C-arylphorin and 14C-phe was similar, one major function of arylphorin must be as a storage protein replenishing the supply of free amino acids used for synthesis of adult tissues. These results also suggest a limited contribution of M. sexta arylphorin to formation of the cuticle subsequent to day-6 pharate adult.

  19. Remarkable increase in 14C-acetate uptake in an epilepsy model rat brain induced by lithium-pilocarpine.

    PubMed

    Hosoi, Rie; Kitano, Daisuke; Momosaki, Sotaro; Kuse, Kenji; Gee, Antony; Inoue, Osamu

    2010-01-22

    The present study demonstrates changes in rat brain glial metabolism during the acute phase of epilepsy. Status epilepticus (SE) was induced using the lithium-pilocarpine model. Glial metabolism was measured with (14)C-acetate. Local cerebral blood flow and glucose metabolism were also measured using (14)C-N-isopropyl-p-iodoamphetamine (IMP) and (14)C-2-deoxyglucose (2DG), respectively. At the initiation of the seizure, (14)C-acetate uptake did not change significantly. However, a marked increase was observed 2 h after the pilocarpine injection in all brain regions studied. The increase of brain uptake was transient, and the maximum enhancement was seen at 2 h after the pilocarpine injection. The increase of (14)C-acetate uptake was almost to the same degree in all regions, whereas (14)C-IMP and (14)C-2DG uptakes showed a heterogeneous increase. In the case of (14)C-IMP, the highest increase was observed in the thalamus (280%), and a moderate increase (120 to 150%) was seen in the orbital cortex, cingulate cortex and pyriform cortex. (14)C-2DG uptake increased by 130 to 240% in most regions of the brain, however, an increase of only 40 and 20% was observed in the cerebellum and pons-medulla, respectively. These results demonstrated that glial energy metabolism was markedly enhanced during a prolonged seizure. To our knowledge, this study is the first observation showing large and widespread glial metabolic increases in the rat brain during status epilepticus.

  20. The metabolism of [14C]beta-carotene and the presence of other carotenoids in rats and monkeys.

    PubMed

    Krinsky, N I; Mathews-Roth, M M; Welankiwar, S; Sehgal, P K; Lausen, N C; Russett, M

    1990-01-01

    The metabolism of beta-carotene has been studied in both rats and Rhesus monkeys, following the oral administration of [14C]beta-carotene in olive oil supplemented with 1 mg/mL alpha-tocopherol. In the rats, peak serum accumulation of [14C]retinol occurred 4 h after a single oral dose, but we were not able to detect [14C]beta-carotene in rat sera at any time up to 72 h after dosing. Small amounts of [14C]beta-carotene were found in the livers, although 88-94% of the recovered radioactivity was localized in the retinol fraction after saponification. Although radioactivity was also found in fractions other than beta-carotene and retinol, the amounts were too small to allow characterization. In the monkeys, peak accumulation of [14C]retinol in serum occurred between 8 and 24 h after supplementation. Some [14C]beta-carotene was also present. Most of the absorbed radioactivity was stored in the liver as [14C]retinol, although 2-8% was present as [14C]beta-carotene. Other organs also contained [14C]beta-carotene, confirming the ability of the monkey to absorb intact beta-carotene. In addition, monkey livers and other organs were found to contain lutein, zeaxanthin, alpha-cryptoxanthin, beta-cryptoxanthin and beta-carotene, presumably arising from dietary sources. PMID:2303914

  1. Laboratory for Radiokrypton Dating

    NASA Astrophysics Data System (ADS)

    Zappala, J. C.; Jiang, W.; Bailey, K. G.; Lu, Z. T.; Mueller, P.; O'Connor, T. P.

    2015-12-01

    Due to its simple production and transport in the terrestrial environment, 81Kr (half-life = 230,000 yr) is the ideal tracer for old water and ice with mean residence times in the range of 105-106 years, a range beyond the reach of 14C. 81Kr-dating is now available to the earth science community at large thanks to the development of an efficient and selective atom counter based on the Atom Trap Trace Analysis (ATTA) method. ATTA is a laser-based atom counting method where individual neutral atoms of the desired isotope are selectively captured by laser beams, and their fluorescence detected via a CCD camera. ATTA is unique among trace analysis techniques in that it is free of interferences from any other isotopes, isobars, atomic or molecular species. The ATTA instrument at Argonne's Laboratory for Radiokrypton Dating is capable of measuring both 81Kr/Kr and 85Kr/Kr ratios of environmental samples in the range of 10-14-10-10. For 81Kr-dating in the age range of 150 kyr - 1500 kyr, the required sample size is 5 micro-L STP of krypton gas, which can be extracted from approximately 100 kg of water or 40 kg of ice. For 85Kr/Kr analysis, the sample size can be smaller by an order of magnitude. We are continually developing the method towards higher counting efficiency, smaller sample sizes requirements, and higher sample throughput rates. In the past four years, we have performed radiokrypton analysis of over 150 groundwater and ice samples extracted by collaborators from all seven continents. Sample collection and purification was performed by groups including the University of Chicago, the University of Illinois at Chicago, the University of Bern, and the International Atomic Energy Agency. This work is supported by the U.S. DOE, Office of Nuclear Physics, under contract DE-AC02-06CH11357.

  2. Adult Human Pancreatic Islet Beta-Cells Display Limited Turnover and Long Lifespan as Determined by In-Vivo Thymidine Analog Incorporation and Radiocarbon Dating

    SciTech Connect

    Perl, S; Kushner, J A; Buchholz, B A; Meeker, A K; Stein, G M; Hsieh, M; Kirby, M; Pechhold, S; Liu, E H; Harlan, D M; Tisdale, J F

    2010-03-15

    Diabetes mellitus results from an absolute or relative deficiency of insulin producing pancreatic beta-cells. The adult human beta-cell's turnover rate remains unknown. We employed novel techniques to examine adult human islet beta-cell turnover and longevity in vivo. Subjects enrolled in NIH clinical trials received thymidine analogues [iododeoxyuridine (IdU) or bromodeoxyuridine (BrdU)] 8-days to 4-years prior to death. Archival autopsy samples from ten patients (aged 17-74 years) were employed to assess beta-cell turnover by scoring nuclear analog labeling within insulin staining cells. Human adult beta-cell longevity was determined by estimating the cells genomic DNA integration of atmospheric carbon-14 ({sup 14}C). DNA was purified from pancreatic islets isolated from cadaveric donors; whole islet prep DNA was obtained from a 15 year old donor, and purified beta-cell DNA was obtained from two donors (age 48 and 80 years). {sup 14}C levels were then determined using accelerator mass spectrometry (AMS). Cellular 'birth date' was determined by comparing the subject's DNA {sup 14}C content relative to a well-established {sup 14}C atmospheric prevalence curve. In the two subjects less than age 20 years, 1-2% of the beta-cell nuclei co-stained for BrdU/IdU. No beta-cell nuclei co-stained in the eight patients more than 30 years old. Consistent with the BrdU/IdU turnover data, beta-cell DNA {sup 14}C content indicated the cells 'birth date' occurred within the subject's first 30 years of life. Under typical circumstances, adult human beta-cells and their cellular precursors are established by young adulthood.

  3. The LLNL Accelerator Mass Spectrometry System for Biochemical 14C-Measurements

    SciTech Connect

    Ognibene, T J; Bench, G; Brown, T A; Vogel, J S

    2002-10-31

    We report on recent improvements made to our 1 MV accelerator mass spectrometry system that is dedicated to {sup 14}C quantification of biochemical samples. Increased vacuum pumping capacity near the high voltage terminal has resulted in a 2-fold reduction of system backgrounds to 0.04 amol {sup 14}C/mg carbon. Carbon ion transmission through the accelerator has also improved a few percent. We have also developed tritium measurement capability on this spectrometer. The {sup 3}H/{sup 1}H isotopic ratio of a milligram-sized processed tap water sample has been measured at 4 {+-} 1 x 10{sup -16} (430 {+-} 110 {micro}Bq/mg H). Measurement throughput for a typical biochemical {sup 3}H sample is estimated to be {approx}10 minutes/sample.

  4. Changes in14c activity over time during vacuum distillation of carbon from rock pore water

    USGS Publications Warehouse

    Davidson, G.R.; Yang, I.C.

    1999-01-01

    The radiocarbon activity of carbon collected by vacuum distillation from a single partially saturated tuff began to decline after approximately 60% of the water and carbon had been extracted. Disproportionate changes in 14C activity and ??13C during distillation rule out simple isotopic fractionation as a causative explanation. Additional phenomena such as matrix diffusion and ion exclusion in micropores may play a role in altering the isotopic value of extracted carbon, but neither can fully account for the observed changes. The most plausible explanation is that distillation recovers carbon from an adsorbed phase that is depleted in 14C relative to DIC in the bulk pore water. ?? 1999 by the Arizona Board of Regents on behalf of the University of Arizona.

  5. A low cost optical radiocarbon (14C) sensor for greenhouse gas source attribution

    NASA Astrophysics Data System (ADS)

    Long, D.; Fleisher, A. J.; Liu, Q.; Hodges, J. T.

    2015-12-01

    Radiocarbon (14C) provides a convenient means for the attribution of atmospheric greenhouse gases between anthropogenic and biogenic sources. Unfortunately, routine measurements are costly and require extensive sample preparation to meet sensitivity goals only achievable at large accelerator mass spectrometer facilities. We describe an alternate approach in which a laser is used to selectively record the absorption signatures of the 14C isotope of CO2. The designed instrument will allow for bench-top measurements of 14CO2 at and below ambient levels (~1.2 parts-per-trillion). The use of a commercially available mid-infrared quantum cascade laser as the optical source greatly reduces the cost of the instrument over more complicated sources and should allow for routine inline measurements.

  6. {sup 14}C-AMS quantification of biomolecular interactions using microbore and plate separations

    SciTech Connect

    Creek, M.R.; Frantz, C.E.; Fultz, E.; Haack, K.; Redwine, K.; Shen, N.; Turteltaub, K.W.; Vogel, J.S.

    1993-10-20

    AMS sensitivity arises from the direct counting of radioisotopes without interference from molecular isobars. No chemical or physical information other than a bulk isotope ratio is available from the usual AMS instrument. Chemical or biological significance of the isotope ratio depends on the definition of the sample prior to conversion to material used in the ion source. The authors use AMS to quantify biochemical interactions between labeled xenobiotics and their potential targets of toxicity. These potential target molecules are separated and defined by various types of plate and microbore separations, including thin layer chromatography (TLC), high performance liquid chromatography (HPLC) and gel electrophoresis (GE) in quantifying the binding of {sup 14}C-labeled compounds to specific DNA and protein fragments. They discuss their methods of using these microbore and plate separations of biomolecules while controlling contamination from {sup 14}C in laboratory equipment and give examples.

  7. Astrophysical S-factor of the radiative proton capture on 14C at low energies

    NASA Astrophysics Data System (ADS)

    Dubovichenko, Sergey; Burtebaev, Nasurlla; Dzhazairov-Kakhramanov, Albert; Alimov, Dilshod

    2014-07-01

    The phase shift analysis for position location of the 2S1/2 resonance at 1.5 MeV was carried out on the basis of the known experimental measurements of the excitation functions of the p14C elastic scattering at four angles from 90° to 165° and more than 100 energy values in the range from 600-800 keV to 2200-2400 keV. Also, the possibility to describe the available experimental data on the astrophysical S-factor for the proton capture reaction on 14C to the ground state (GS) of 15N at astrophysical energies was considered in the frame of modified potential cluster model (MPCM).

  8. Detection of an azido-(/sup 14/C)-atrazine labeled protein transferred to nitrocellulose paper

    SciTech Connect

    Ivey, S.; Metz, J.G.; Berg, S.P.

    1986-04-01

    An electrophoretically similar protein in spinach and maize can be covalently labeled with azido-(/sup 14/C)-atrazine and separated by 10-18% gradient LDS-PAGE. The protein profile can be transferred to nitrocellulose paper (ncp) by western blotting. The ncp containing the protein profile is sliced into 2 mm slices and counted with liquid scintillation. The labeled protein migrates as a diffuse band with a Mr of 34 kD. This band migrates at a higher Mr (40 kD) under different gel conditions. The ncp dissolves in the organic scintillation cocktail thus providing a more sensitive and quantitative detection of the /sup 14/C. This technique allows the simultaneous immunological and radiochemical identification of many electrophoretically separable proteins.

  9. ( sup 14 C)-Sucrose uptake by guard cell protoplasts of pisum sativum, argenteum mutant

    SciTech Connect

    Rohrig, K.; Raschke, K. )

    1991-05-01

    Guard cells rely on import for their supply with reduced carbon. The authors tested by silicone oil centrifugation the ability of guard cell protoplasts to accumulated ({sup 14}C)-sucrose. Uptake rates were corrected after measurement of {sup 14}C-sorbitol and {sup 3}H{sub 2}O spaces. Sucrose uptake followed biphasic kinetics, with a high-affinity component below 1 mM external sucrose (apparent K{sub m} 0.8 mM at 25C) and a low-affinity nonsaturable component above. Uptake depended on pH (optimum at pH 5.0). Variations in the concentrations of external KCl, CCCP, and valinomycin indicated that about one-half of the sucrose uptake rate could be related to an electrochemical gradient across the plasmalemma. Total uptake rates measured at 5 mM external sucrose seem to be sufficient to replenish emptied plastids with starch within a few hours.

  10. Dating a small impact crater: An age of Kaali crater (Estonia) based on charcoal emplaced within proximal ejecta

    NASA Astrophysics Data System (ADS)

    Losiak, A.; Wild, E. M.; Geppert, W. D.; Huber, M. S.; Jõeleht, A.; Kriiska, A.; Kulkov, A.; Paavel, K.; Pirkovic, I.; Plado, J.; Steier, P.; VäLja, R.; Wilk, J.; Wisniowski, T.; Zanetti, M.

    2016-04-01

    The estimates of the age of the Kaali impact structure (Saaremaa Island, Estonia) provided by different authors vary by as much as 6000 years, ranging from ~6400 to ~400 before current era (BCE). In this study, a new age is obtained based on 14C dating charred plant material within the proximal ejecta blanket, which makes it directly related to the impact structure, and not susceptible to potential reservoir effects. Our results show that the Kaali crater was most probably formed shortly after 1530-1450 BCE (3237 ± 10 14C yr BP). Saaremaa was already inhabited when the bolide hit the Earth, thus, the crater-forming event was probably witnessed by humans. There is, however, no evidence that this event caused significant change in the material culture (e.g., known archeological artifacts) or patterns of human habitation on Saaremaa.

  11. Temperature and Oxygen Effects on 14C-Photosynthate Unloading and Accumulation in Developing Soybean Seeds

    PubMed Central

    Thorne, John H.

    1982-01-01

    The environmental sensitivity of the processes associated with the import of photosynthate by developing soybean seeds was investigated within intact fruit and with excised, immature embryos. Intact pods of field-grown (Glycine max [L.] Merr.) Amsoy 71 soybeans were subjected to localized regimes of 0, 21, or 100% O2 and 15, 25, or 35°C during pulsechase translocation experiments and, 2.5 hours later, the uptake and distribution of 14C-photosynthate among dissected fruit tissues determined. In other experiments, excised embryos were incubated in [14C]sucrose solutions under various experimental conditions to separate the effects of these treatments on accumulation by the embryos from those which may operate on phloem unloading in the maternal seedcoat. Import of 14C-photosynthate by intact soybean fruit was both temperature- and O2-dependent. This dependency was shown to occur only within the seeds; import by the pod walls was essentially insensitive to fruit temperature or O2 treatments. The embryos of anaerobic fruit were completely unlabeled, regardless of fruit temperature. But under anaerobic in vitro incubation conditions, uptake of [14C]sucrose in excised embryos was only 30% less than that in aerobic in vitro conditions. The data suggest that, within intact fruit, anoxia prevented sucrose efflux from the seed coat phloem and any subsequent uptake by the embryo. The demonstrated energy dependence of phloem unloading may reflect requirements for membrane integrity or energy metabolism in the companion cell-sieve element complex, consistent with a facilitated unloading process. Collectively, these data characterize the environmental sensitivity of photosynthate import in developing soybean fruit. They imply that environmental regulation of import may occur at both the embryo level and at the phloem terminals within the seed coat. PMID:16662182

  12. Goldenrod ball gall effects on Solidago altissima: /sup 14/C translocation and growth. [Eurosta solidaginis

    SciTech Connect

    McCrea, K.D.; Abrahamson, W.G.; Weis, A.E.

    1985-12-01

    Individual leaves of S. altissima were labeled with carbon-14 introduced as CO/sub 2/. The /sup 14/C was introduced into ramets that had ball galls caused by the fly Eurosta solidaginis and into ungalled control ramets; gall size (large vs. small) and point of introduction of the label (above vs. below the gall) were experimental factors. After 5 d the ramets were harvested and their component organs were assayed for /sup 14/C using liquid scintillation. In addition, a field cohort of 359 galled and ungalled ramets was followed during the period of gall growth to determine the effect of the gall on stem height growth. Gall size and labeling position had no effect on the percent of /sup 14/C translocated out of the labeled leaf but did affect the distribution of translocated /sup 14/C. Translocation to underground organs was reduced when the label was introduced above the gall, the reduction being related to gall size. Large galls reduced translocation to the apical bud when the label was introduced below the gall, but small galls did not. Translocation to underground organs was not affected by the gall when the label was introduced below the gall and translocation to the apical bud was not affected by the gall when the label was introduced above the gall; these results indicate that the goldenrod ball gall is a nonmobilizing gall. The presence of a gall did not significantly affect final stem height but did slow the growth of ramets during the period of most rapid gall growth.

  13. Product inhibition of cellulases studied with 14C-labeled cellulose substrates

    PubMed Central

    2013-01-01

    Background As a green alternative for the production of transportation fuels, the enzymatic hydrolysis of lignocellulose and subsequent fermentation to ethanol are being intensively researched. To be economically feasible, the hydrolysis of lignocellulose must be conducted at a high concentration of solids, which results in high concentrations of hydrolysis end-products, cellobiose and glucose, making the relief of product inhibition of cellulases a major challenge in the process. However, little quantitative information on the product inhibition of individual cellulases acting on cellulose substrates is available because it is experimentally difficult to assess the hydrolysis of the heterogeneous polymeric substrate in the high background of added products. Results The cellobiose and glucose inhibition of thermostable cellulases from Acremonium thermophilum, Thermoascus aurantiacus, and Chaetomium thermophilum acting on uniformly 14C-labeled bacterial cellulose and its derivatives, 14C-bacterial microcrystalline cellulose and 14C-amorphous cellulose, was studied. Cellulases from Trichoderma reesei were used for comparison. The enzymes most sensitive to cellobiose inhibition were glycoside hydrolase (GH) family 7 cellobiohydrolases (CBHs), followed by family 6 CBHs and endoglucanases (EGs). The strength of glucose inhibition followed the same order. The product inhibition of all enzymes was relieved at higher temperatures. The inhibition strength measured for GH7 CBHs with low molecular-weight model substrates did not correlate with that measured with 14C-cellulose substrates. Conclusions GH7 CBHs are the primary targets for product inhibition of the synergistic hydrolysis of cellulose. The inhibition must be studied on cellulose substrates instead of on low molecular-weight model substrates when selecting enzymes for lignocellulose hydrolysis. The advantages of using higher temperatures are an increase in the catalytic efficiency of enzymes and the relief of

  14. Release of ( sup 14 C)5-hydroxytryptamine from human platelets by red wine

    SciTech Connect

    Jarman, J.; Glover, V.; Sandler, M. )

    1991-01-01

    Red wine, at a final dilution of 1/50, caused released of ({sup 14}C)5-hydroxytryptamine (5-HT) from preloaded platelets, an effect which was not observed with any white wines or beers tested. Since 5-HT, is probably released from body stores during migraine attacks and red wine is known to provoke migraine episodes in susceptible individuals, release of 5-HT, possibly from central stores, could represent a plausible mechanism for its mode of action.

  15. Kernel abortion in maize. II. Distribution of /sup 14/C among kernel carboydrates

    SciTech Connect

    Hanft, J.M.; Jones, R.J.

    1986-06-01

    This study was designed to compare the uptake and distribution of /sup 14/C among fructose, glucose, sucrose, and starch in the cob, pedicel, and endosperm tissues of maize (Zea mays L.) kernels induced to abort by high temperature with those that develop normally. Kernels cultured in vitro at 309 and 35/sup 0/C were transferred to (/sup 14/C)sucrose media 10 days after pollination. Kernels cultured at 35/sup 0/C aborted prior to the onset of linear dry matter accumulation. Significant uptake into the cob, pedicel, and endosperm of radioactivity associated with the soluble and starch fractions of the tissues was detected after 24 hours in culture on atlageled media. After 8 days in culture on (/sup 14/C)sucrose media, 48 and 40% of the radioactivity associated with the cob carbohydrates was found in the reducing sugars at 30 and 35/sup 0/C, respectively. Of the total carbohydrates, a higher percentage of label was associated with sucrose and lower percentage with fructose and glucose in pedicel tissue of kernels cultured at 35/sup 0/C compared to kernels cultured at 30/sup 0/C. These results indicate that sucrose was not cleaved to fructose and glucose as rapidly during the unloading process in the pedicel of kernels induced to abort by high temperature. Kernels cultured at 35/sup 0/C had a much lower proportion of label associated with endosperm starch (29%) than did kernels cultured at 30/sup 0/C (89%). Kernels cultured at 35/sup 0/C had a correspondingly higher proportion of /sup 14/C in endosperm fructose, glucose, and sucrose.

  16. In vitro uptake of /sup 14/C-praziquantel by cestodes, trematodes, and a nematode

    SciTech Connect

    Andrews, P.; Thomas, H.; Weber, H.

    1980-12-01

    /sup 14/C-praziquantel was rapidly taken up by Schistosoma mansoni, Fasciola hepatica, Hymenolepis nana, and isolated strobilocerci of Taenia taeniaeformis. Schistosoma mansoni lost praziquantel rapidly to drug-free medium. Chromatography of extracts prepared after incubation of S. mansoni and H. nana yielded no indication that praziquantel was metabolized. Autoradiography revealed a uniform distribution of praziquantel throughout the tissues of S. mansoni and H. nana. Uptake was considerably slower in the nematode Heterakis spumosa and apparently via the oral route.

  17. Theoretical estimates of the rates of radioactive decay of radium isotopes by /sup 14/C emission

    SciTech Connect

    Shi, Y.; Swiatecki, W.J.

    1985-01-28

    The measured branching ratios for the decays of /sup 222,223,224/Ra by alpha or /sup 14/C emissions can be accounted for within a factor of 10 in terms of the ratios of Gamow penetrabilities through potential-energy barriers consisting of a Coulomb repulsion, the nuclear proximity attraction, and an interpolation between the configuration of tangent fragments and the configuration of the parent nucleus.

  18. Using 14C and 3H to understand groundwater flow and recharge in an aquifer window

    NASA Astrophysics Data System (ADS)

    Atkinson, A. P.; Cartwright, I.; Gilfedder, B. S.; Cendón, D. I.; Unland, N. P.; Hofmann, H.

    2014-12-01

    Knowledge of groundwater residence times and recharge locations is vital to the sustainable management of groundwater resources. Here we investigate groundwater residence times and patterns of recharge in the Gellibrand Valley, southeast Australia, where outcropping aquifer sediments of the Eastern View Formation form an "aquifer window" that may receive diffuse recharge from rainfall and recharge from the Gellibrand River. To determine recharge patterns and groundwater flow paths, environmental isotopes (3H, 14C, δ13C, δ18O, δ2H) are used in conjunction with groundwater geochemistry and continuous monitoring of groundwater elevation and electrical conductivity. The water table fluctuates by 0.9 to 3.7 m annually, implying recharge rates of 90 and 372 mm yr-1. However, residence times of shallow (11 to 29 m) groundwater determined by 14C are between 100 and 10 000 years, 3H activities are negligible in most of the groundwater, and groundwater electrical conductivity remains constant over the period of study. Deeper groundwater with older 14C ages has lower δ18O values than younger, shallower groundwater, which is consistent with it being derived from greater altitudes. The combined geochemistry data indicate that local recharge from precipitation within the valley occurs through the aquifer window, however much of the groundwater in the Gellibrand Valley predominantly originates from the regional recharge zone, the Barongarook High. The Gellibrand Valley is a regional discharge zone with upward head gradients that limits local recharge to the upper 10 m of the aquifer. Additionally, the groundwater head gradients adjacent to the Gellibrand River are generally upwards, implying that it does not recharge the surrounding groundwater and has limited bank storage. 14C ages and Cl concentrations are well correlated and Cl concentrations may be used to provide a first-order estimate of groundwater residence times. Progressively lower chloride concentrations from 10

  19. Biosynthesis of riboflavin. Enzymatic formation of the xylene moiety from [14C]ribulose 5-phosphate.

    PubMed

    Nielsen, P; Neuberger, G; Floss, H G; Bacher, A

    1984-02-14

    We have studied the enzymatic formation of the xylene ring of riboflavin using cell extracts from the flavinogenic yeast Candida guilliermondii. 5-Amino-6-ribitylamino-2,4(1H,3H)-pyrimidinedione or its 5'-phosphate could serve as substrates. In addition, a pentose phosphate or pentulose phosphate was required. Experiments with [14C]ribulose 5-phosphate gave evidence for the incorporation of the ribulose carbon atoms except C-4 into the xylene ring of the vitamin. PMID:6546684

  20. A New {sup 14}C-AMS Facility at UFF- Niteroi, Brazil

    SciTech Connect

    Gomes, P. R. S.; Macario, K. D.; Anjos, R. M.; Linares, R.; Carvalho, C.; Queiroz, E.

    2010-08-04

    We report a new Accelerator Mass Spectrometry facility at the Physics Institute of Fluminense Federal University in Brazil, the Nuclear Chronology Laboratory - LACRON. The sample preparation laboratory is ready to perform chemical treatment through graphitization and the acquisition of a Single Stage Accelerator Mass Spectrometry System is in progress. LACRON will be the first independent laboratory to perform the {sup 14}C-AMS technique not only in Brazil but in Latin America.

  1. Polymorphism of 14C vitamin D3 binding protein in cattle and water buffalo serum.

    PubMed

    Masina, P; Ramunno, L; Iannelli, D

    1978-01-01

    Cattle and water buffalo sera labelled with vitamin D3[14C] (300 and 480 individual samples respectively) were subjected to starch gel electrophoresis followed by autoradiography in an attempt to identify a possible polymorphism of the proteins capable of binding this vitamin. Three phenotypes controlled by two codominant autosomal alleles were identified in cattle while in water buffalo six phenotypes controlled by three codominant autosomal alleles were observed.

  2. In vitro covalent binding of 3-(/sup 14/C)methylindole metabolites in goat tissues

    SciTech Connect

    Bray, T.M.; Carlson, J.R.; Nocerini, M.R.

    1984-05-01

    Covalent binding of 3-(/sup 14/C)methylindole (3(/sup 14/C)MI) in crude microsomal preparations of goat lung, liver, and kidney was measured to determine if a reactive intermediate was formed during the in vitro metabolism of 3-methylindole (3MI). The bound radioactivity was highest in lung compared to liver and kidney. The amount of bound radioactivity per nanomole of cytochrome P-450 was approximately 10 times higher in the lung compared to the liver. No detectable bound radioactivity was found when 3-(/sup 3/H)methyloxindole was used as the substrate. Cofactor requirements and the effects of inhibitors indicate that a mixed function oxidase (MFO) system is involved in formation of a reactive intermediate. Inhibitors and conjugating agents that are known to reduce the severity of 3MI-induced lung injury such as piperonyl butoxide (MFO inhibitor) and glutathione (conjugating agent) significantly decreased the in vitro binding of 3(/sup 14/C)MI. The results indicate that a reactive intermediate is produced during the metabolism of 3MI by the MFO system. The organ specificity in binding suggests that covalent binding by lung microsomes may be related to the mechanism of 3MI-induced lung injury.

  3. An approach toward automatic graphitization of CO2 samples for AMS 14C measurements

    NASA Astrophysics Data System (ADS)

    Nagasawa, Shigenobu; Kitagawa, Hiroyuki; Nakanishi, Toshimichi; Tanabe, Susumu; Hong, Wan

    2013-01-01

    To improve the throughput of sample preparation for AMS 14C measurements, we made improvements to a manually operated system for CO2 reduction at the Graduate School of Environmental Studies, Nagoya University. Most of the processes of the CO2 reduction procedure were automated, and a CO2 sample containing 0.3-1 mg carbon was credibly reduced to graphite within a few hours by hydrogen gas with catalytic iron powder in a 7.4 ml reactor consisting of a quartz reduction tube, a pressure transducer gauge and a cold finger trap equipped with a temperature-controllable trap device for trapping CO2 and H2O. The improved system has the potential to easily carry out graphitization of more than 100 CO2 samples per week. The 14C values of graphite produced from 14C-free CO2 (>0.3 mg C) were 0.0028 ± 0.0010 fraction modern carbon (FMC) on average (n = 8, 1std), which are almost the same as the black level of 1-MV HVEE Tandetron installed at the Korea Institute of Geoscience and Mineral Resources (KIGAM).

  4. Incorporation of l-[14C]leucine into egg proteins by liver slices from cod

    PubMed Central

    Plack, P. A.; Fraser, N. W.

    1971-01-01

    1. Liver slices from cod (Gadus morhua L.) were incubated with l-[14C]leucine and the incorporation of label into total protein, precipitated with trichloroacetic acid, and into egg proteins, precipitated with an antibody after addition of carrier egg proteins, was measured. 2. Liver slices from immature male or female cod, and from male fish with developing testes, did not incorporate significant amounts of l-[14C]leucine into egg proteins, whereas with slices from female cod with developing ovaries the rate of incorporation into egg proteins was 8% of the rate of incorporation into total protein. 3. Liver slices from immature male or female fish that had received an intramuscular injection of oestradiol benzoate (1mg/kg) 5–8 days previously incorporated l-[14C]leucine into egg proteins at about 26% of the rate of incorporation into total protein. 4. Incorporation into total protein and into egg proteins was inhibited by puromycin, and 1.2 and 0.13μg of puromycin/mg of tissue protein, respectively, gave 50% inhibition. PMID:16742749

  5. Role of biotransformation, sorption and mineralization of (14)C-labelled sulfamethoxazole under different redox conditions.

    PubMed

    Alvarino, T; Nastold, P; Suarez, S; Omil, F; Corvini, P F X; Bouju, H

    2016-01-15

    (14)C-sulfamethoxazole biotransformation, sorption and mineralization was studied with heterotrophic and autotrophic biomass under aerobic and anoxic conditions, as well as with anaerobic biomass. The (14)C-radiolabelled residues distribution in the solid, liquid and gas phases was closely monitored along a total incubation time of 190 h. Biotransformation was the main removal mechanism, mineralization and sorption remaining below 5% in all the cases, although the presence of a carbon source exerted a positive effect on the mineralization rate by the aerobic heterotrophic bacteria. In fact, an influence of the type of primary substrate and the redox potential was observed in all cases on the biotransformation and mineralization rates, since an enhancement of the removal rate was observed when an external carbon source was used as a primary substrate under aerobic conditions, while a negligible effect was observed under nitrifying conditions. In the liquid phases collected from all assays, up to three additional peaks corresponding to (14)C-radiolabelled residues were detected. The highest concentration was observed under anaerobic conditions, where two radioactive metabolites were detected representing each around 15% of the total applied radioactivity after 180 h incubation. One of the metabolites detected under anoxic and anaerobic conditions, is probably resulting from ring cleavage of the isoxazole ring. PMID:26546766

  6. The fate of dermally applied [14C]d-limonene in rats and humans.

    PubMed

    Api, Anne Marie; Ritacco, Gretchen; Hawkins, David R

    2013-01-01

    The fate of dermally applied [(14)C]d-limonene was evaluated in humans and Long-Evans rats. In rats, 5 mg/kg body weight of [(14)C]d-limonene applied dermally to the shaved back under occlusion, resulted in the absorption of approximately 12% of the dose. The absorbed d-limonene was completely metabolized and excreted rapidly, primarily from the urine (80%) with a small fraction (20%) excreted in the feces. There was no long-term retention of the test material in body tissues. In humans, following dermal application of 12 mg of [(14)C]d-limonene in ethanol (1 mL) to the back under nonocclusive conditions (for 1 h after application to allow the material to dry, thereafter under occlusion), only 0.16% of the dose was absorbed and the radioactivity was recovered from the urine. Radioactivity in human feces was below the limit of detection. These results indicate that under conditions of simulated use of fragrances and cosmetics, d-limonene has a low potential for dermal absorption and tissue accumulation, and the d-limonene that is absorbed is rapidly excreted in the urine. Based upon these findings and the knowledge that d-limonene possesses a low-systemic toxicity profile, it is reasonable to conclude that dermal exposure to d-limonene from fragrance and cosmetic applications is highly unlikely to result in any clinically significant human toxicity.

  7. A compact 14C Isotope Ratio Mass Spectrometer for biomedical applications

    NASA Astrophysics Data System (ADS)

    Mous, D. J. W.; Purser, K. H.; Fokker, W.; van den Broek, R.; Koopmans, R. B.

    1997-03-01

    During the last two decades the unparalleled sensitivity of accelerator mass spectrometry (AMS) has allowed major developments in many areas of geoscience and archeology. It is projected that in the near future a similar potential for AMS expansion is likely in the field of biomedical research leading, ultimately, to clinical applications. As an example of the growth of this new field, at the Lawrence Livermore National Laboratory Center for AMS the number of biomedical 14C measurements already represents a significant fraction of the total for all 14C. Widespread adoption of AMS in the biomedical field does require, however, the availability of instruments that are small in comparison with existing AMS systems and that will operate in a manner that is simple and user-friendly. To meet this demand, High Voltage Engineering Europa (HVEE) has developed a miniature, high-efficiency AMS instrument designed to provide for biomedical samples {14C}/{12C} ratios with an accuracy better than 2% and with backgrounds limitations below 0.1 Modern. The current status of this program will be presented in the present paper.

  8. Pollen-based biomes for Beringia 18,000, 6000 and 0 14C yr BP

    USGS Publications Warehouse

    Edwards, M.E.; Anderson, P.M.; Brubaker, L.B.; Ager, T.A.; Andreev, A.A.; Bigelow, N.H.; Cwynar, L.C.; Eisner, Wendy R.; Harrison, S.P.; Hu, F.-S.; Jolly, D.; Lozhkin, A.V.; MacDonald, G.M.; Mock, C.J.; Ritchie, J.C.; Sher, A.V.; Spear, R.W.; Williams, J.W.; Yu, G.

    2000-01-01

    The objective biomization method developed by Prentice et al. (1996) for Europe was extended using modern pollen samples from Beringia and then applied to fossil pollen data to reconstruct palaeovegetation patterns at 6000 and 18,000 14C yr BP. The predicted modern distribution of tundra, taiga and cool conifer forests in Alaska and north-western Canada generally corresponds well to actual vegetation patterns, although sites in regions characterized today by a mosaic of forest and tundra vegetation tend to be preferentially assigned to tundra. Siberian larch forests are delimited less well, probably due to the extreme under-representation of Larix in pollen spectra. The biome distribution across Beringia at 6000 14C yr BP was broadly similar to today, with little change in the northern forest limit, except for a possible northward-advance in the Mackenzie delta region. The western forest limit in Alaska was probably east of its modern position. At 18,000 14C yr BP the whole of Beringia was covered by tundra. However, the importance of the various plant functional types varied from site to site, supporting the idea that the vegetation cover was a mosaic of different tundra types.

  9. The impact of biochar on the bioaccessibility of (14)C-phenanthrene in aged soil.

    PubMed

    Ogbonnaya, O U; Adebisi, O O; Semple, K T

    2014-11-01

    Biochar is a carbon rich product from the incomplete combustion of biomass and it has been shown to reduce bioavailability of organic contaminants through adsorption. This study investigated the influence of 0%, 1%, 5% and 10% of two different particle sized wood biochars (≤2 mm and 3-7 mm) on the bioaccessibility of (14)C-phenanthrene (10 mg kg(-1)) in aged soil. The extent of (14)C-phenanthrene mineralisation by phenanthrene-degrading Pseudomonas sp. inoculum was monitored over a 14 day period in respirometric assays and compared to hydroxypropyl-β-cyclodextrin (HPCD) aqueous extraction. Notably, biochar amendments showed significant reduction in extents of mineralisation and HPCD extraction. Linear correlations between HPCD extractability and the total amount mineralised revealed good correlations, with 2 mm biochar showing a best fit (r(2) = 0.97, slope = 1.11, intercept = 1.72). Biochar reduced HPCD extractability and bioaccessibility of (14)C-phenanthrene to microorganisms in a similar manner. Biochar can aid risk reduction to phenanthrene exposure to biota in soil and HPCD can serve as a useful tool to assess the extent of exposure in biochar-amended soils.

  10. Na/sup +/-dependent transport of /sup 14/C-L-lysine across bullfrog alveolar epithelium

    SciTech Connect

    Kim, K.J.; Crandall, E.D.

    1986-03-01

    Transepithelial transport of the basic amino acid L-lysine has been studied utilizing the isolated intact bullfrog lung mounted in the Ussing chamber. Lungs were excised from doubly pithed bullfrogs and sandwiched between two hemichambers. /sup 14/C-(U)-L-lysine was added to the upstream reservoir of amphibian Ringer solution, while the tissue was short-circuited. Two lungs from the same animal were used simultaneously to determine the two opposite unidirectional fluxes. Downstream and upstream radioactivities were assayed and used to estimate the apparent permeability (P) of the labeled lysine. Results indicate that the apparent P of /sup 14/C-L-lysine measured in the alveolar (M) to the pleural (S) direction is 19.06 (+- 2.84) x 10/sup -7/ cm/s and P in the S to M direction is 3.29 (+- 0.02) x 10/sup -7/ cm/s. When the 100 mM NaCl in the bath was replaced by 110 mM choline chloride, the flux of /sup 14/C-L-lysine from the alveolar to the pleural side decreased to the same value as that in the opposite direction. The flux from the pleural to the alveolar direction in the absence of Na/sup +/ did not change. These results suggest that the alveolar epithelium exhibits Na/sup +/-dependent amino acid (L-lysine) transport in the M->S, but not in the S->M, direction.

  11. Soil metabolism of a new herbicide, [14C]Pyribenzoxim, under flooded conditions.

    PubMed

    Chang, Hee-Ra; Koo, Suk-Jin; Kim, Kyun; Ro, Hee-Myong; Moon, Joon-Kwan; Kim, Yong-Hwa; Kim, Jeong-Han

    2007-07-25

    To elucidate the fate of a new pyrimidinyloxybenzoic herbicide, pyribenzoxim, a soil metabolism study was carried out with [14C]pyribenzoxim applied to a sandy loam soil under flooded conditions. The material balance of applied radioactivity ranged from 96.4 to 104.4% and from 96.1 to 101.9% for nonsterile and sterile soils, respectively. The half-life of [14C]pyribenzoxim was calculated to be approximately 1.3 and 9.4 days for nonsterile and sterile soils, respectively. The metabolites identified during the study were 2,6-bis(4,6-dimethoxypyrimidin-2-yloxy)benzoic acid (M1) and 2-hydroxy-6-(4,6-dimethoxypyrimidin-2-yloxy)benzoic acid (M2), resulting from the cleavage of the ester bond and subsequent hydrolysis. The nonextractable radioactivity levels increased to 37.8% for nonsterile conditions at 50 days after treatment and to 38.2% for sterile conditions at 60 days after treatment. Fractionation of the nonextractable soil residues indicated that bound radioactivity was associated mainly with humin fraction. No significant volatile products or [14C]carbon dioxide was observed during the study. On the basis of these results, pyribenzoxim is considered to undergo rapid degradation in soil by microbial and chemical reactions, mainly hydrolysis, which limits its transfer to and accumulation in lower soil layers and groundwater. Therefore, the possibility of environmental contamination from the use of pyribenzoxim is expected to be very low.

  12. The 14C age of glacial North Atlantic surface waters: Greenland Interstadial Events 2-13

    NASA Astrophysics Data System (ADS)

    Austin, William; Hibbert, Fiona; Bard, Edouard; Bryant, Charlotte

    2016-04-01

    We present an updated compilation of surface ocean (Globigerina bulloides) AMS 14C ages for Greenland Interstadials (GI) 2-13, spanning the interval 25,000 - 45,000 cal BP from the mid-latitude NE Atlantic Ocean. New data from two marine sediment cores located 83 km apart in the NE Atlantic are presented: MD95-2006 (Barra Fan; 57°01.82 N, 10°03.48 W; 2120m water depth) and MD04-2822 (Rockall Trough; 56°50.54 N, 11°22.96 W; 2344m water depth) as well as published data from core MD95-2042 (Iberian Margin; 37°45'N, 10°10'W, 3146 m water depth). Replicated sea surface temperature (SST) records show evidence for abrupt warming events; we correlate these directly to the D/O cycles of the Greenland (NGRIP) ice-core oxygen isotope record. We test the proposed synchronization of two of these records using three geochemically distinct tephra isochrones (NAAZ-1, Fugloyarbanki and NAAZ-2). Our data provide a potentially useful new surface ocean composite record of 14C age from the mid-latitude North Atlantic, suggesting broadly consistent interstadial 14C age data from all three records; and highlight the advantage of tuning mid-latitude SST records to Greenland (tested with tephra isochrones where possible) when constructing marine age-models through this time interval.

  13. Measurement of local cerebral blood flow with (/sup 14/C)iodoantipyrine in the mouse

    SciTech Connect

    Jay, T.M.; Lucignani, G.; Crane, A.M.; Jehle, J.; Sokoloff, L.

    1988-02-01

    Local cerebral blood flow was measured in the mouse by means of the (/sup 14/C)iodoantipyrine method. This method has been previously used in the monkey, dog, cat, and rat, but its application to small mammals such as the mouse requires special attention to potential sources of error. The small size of the mouse brain requires special attention to the rapid removal and freezing of the brain to minimize effects of postmortem diffusion of tracer in the tissue. Because of the relatively low diameter/length ratios of the catheters needed for arterial sampling in small animals, substantial errors can occur in the determination of the time course of the (/sup 14/C)iodoantipyrine concentration in the arterial blood unless corrections for lag time and dead space washout in the catheter are properly applied. Local cerebral blood flow was measured in seven awake mice with appropriate care to minimize these sources of error. The values were found to vary from 48 ml/100 g/min in the corpus callosum to 198 ml/100 g/min in the inferior colliculus. The results demonstrate that the (/sup 14/C)iodoantipyrine method can be used to measure local cerebral blood flow in the mouse and that the values in that species are, in general, somewhat higher than those in the rat.

  14. Methods for high precision 14C AMS measurement of atmospheric CO2 at LLNL

    SciTech Connect

    Graven, H D; Guilderson, T P; Keeling, R F

    2006-10-18

    Development of {sup 14}C analysis with precision better than 2{per_thousand} has the potential to expand the utility of {sup 14}CO{sub 2} measurements for carbon cycle investigations as atmospheric gradients currently approach traditional measurement precision of 2-5{per_thousand}. The AMS facility at the Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, produces high and stable beam currents that enable efficient acquisition times for large numbers of {sup 14}C counts. One million {sup 14}C atoms can be detected in approximately 25 minutes, suggesting that near 1{per_thousand} counting precision is economically feasible at LLNL. The overall uncertainty in measured values is ultimately determined by the variation between measured ratios in several sputtering periods of the same sample and by the reproducibility of replicate samples. Experiments on the collection of one million counts on replicate samples of CO{sub 2} extracted from a whole air cylinder show a standard deviation of 1.7{per_thousand} in 36 samples measured over several wheels. This precision may be limited by the reproducibility of Oxalic Acid I standard samples, which is considerably poorer. We outline the procedures for high-precision sample handling and analysis that have enabled reproducibility in the cylinder extraction samples at the <2{per_thousand} level and describe future directions to continue increasing measurement precision at LLNL.

  15. Characterization of nonexchangeable radioactivity in L1210 cells incubated with ( sup 14 C)thiotepa: Labeling of phosphatidylethanolamine

    SciTech Connect

    Egorin, M.J.; Snyder, S.W. )

    1990-07-01

    N,N',N''-Triethylenethiophosphoramide ((14C)thiotepa) accumulation by L1210 cells is a biphasic process. A very rapid initial phase is followed by a much slower second phase that reflects accumulation of radioactivity in a form that is not lost or exchanged when cells are resuspended and incubated in drug-free medium for up to 8 h. In this study we attempted to characterize this nonexchangeable radioactivity. Nuclei (10(7)) isolated from L1210 cells and incubated with (14C)thiotepa did not accumulate 14C during incubations of up to 5 h. Similarly, nuclei isolated from 10(7) L1210 cells that had been shown to accumulate nonexchangeable 14C after incubation with (14C)thiotepa did not show an increase in nuclear-associated 14C. Eighty to 85% of nonexchangeable 14C in L1210 cells incubated with (14C)thiotepa was soluble in ethanol or chloroform:methanol (2:1, v/v), and although most of this cell-associated nonexchangeable 14C was precipitated by trichloroacetic acid, subsequent treatment of that precipitate with methanol solubilized most of the 14C so that only 15 to 20% remained with the final precipitate. When chloroform:methanol-soluble nonexchangeable 14C was analyzed with thin-layer chromatography systems suitable for thiotepa or simple lipids, all radioactivity remained at the origin. In contrast, when analyzed with one- and two-dimensional thin-layer chromatographic systems suitable for complex lipids, all chloroform:methanol-soluble radioactivity was associated with a single lipid spot. This lipid cochromatographed with phosphatidylethanolamine, reacted with ninhydrin but not with 4-(p-nitrobenzyl)pyridine or the Dragendorff choline reagent, and was digested by phospholipases C and D, all of which lead to its identification as phosphatidylethanolamine.

  16. [Quantifying soil autotrophic microbes-assimilated carbon input into soil organic carbon pools following continuous 14C labeling].

    PubMed

    Shi, Ran; Chen, Xiao-Juan; Wu, Xiao-Hong; Jian, Yan; Yuan, Hong-Zhao; Ge, Ti-Da; Sui, Fang-Gong; Tong, Cheng-Li; Wu, Jin-Shui

    2013-07-01

    Soil autotrophic microbe has been found numerous and widespread. However, roles of microbial autotrophic processes and the mechanisms of that in the soil carbon sequestration remain poorly understood. Here, we used soils incubated for 110 days in a closed, continuously labeled 14C-CO2 atmosphere to measure the amount of labeled C incorporated into the microbial biomass. The allocation of 14C-labeled assimilated carbon in variable soil C pools such as dissolved organic C (DOC) and microbial biomass C (MBC) were also examined over the 14C labeling span. The results showed that significant amounts of 14C-SOC were measured in paddy soils, which ranged from 69.06-133.81 mg x kg(-1), accounting for 0.58% to 0.92% of the total soil organic carbon (SOC). The amounts of 14C in the dissolved organic C (14C-DOC) and in the microbial biomass C (14C-MBC) were dependent on the soils, ranged from 2.54 to 8.10 mg x kg(-1), 19.50 to 49.16 mg x kg(-1), respectively. There was a significantly positive linear relationship between concentrations of 14C-SOC and 14C-MBC (R2 = 0.957**, P < 0.01). The 14C-DOC and 14C-MBC as proportions of total DOC, MBC, were 5.65%-24.91% and 4.23%-20.02%, respectively. Moreover, the distribution and transformation of microbes-assimilated-derived C had a greater influence on the dynamics of DOC and MBC than that on the dynamics of SOC. These data provide new insights into the importance of microorganisms in the fixation of atmospheric CO2 and of the potentially significant contributions made by microbial autotrophy to terrestrial C cycling.

  17. Progress in radiocarbon dating with the Chalk River MP tandem accelerator

    SciTech Connect

    Andrews, H.R.; Ball, G.C.; Brown, R.M.; Davies, W.G.; Imahori, Y.; Milton, J.C.D.

    1980-01-01

    The evolution of a tandem accelerator /sup 14/C dating system at Chalk River is recounted. Background problems and sources of instability are discussed and solutions are described. Details of sample chemistry and source preparation are presented.

  18. Does the 14C method estimate net photosynthesis? II. Implications from cyclostat studies of marine phytoplankton

    NASA Astrophysics Data System (ADS)

    Pei, Shaofeng; Laws, Edward A.

    2014-09-01

    Two species of marine phytoplankton, Isochrysis galbana and Chlorella kessleri, were grown in a continuous culture system on a 12-h:12-h light:dark cycle of illumination under nitrate-limited growth conditions. At growth rates of ~1 d-1, production rates estimated from 14C uptake were not significantly different from production rates estimated from changes in particulate organic carbon (POC) and total organic carbon (TOC). At growth rates of ~0.35 d-1, however, production rates based on uptake of 14C significantly (p<0.05) overestimated production rates based on changes in POC and TOC in all cases for C. kessleri and after 24 h for I. galbana. The ratio of production based on 14C uptake to production based on changes in POC and TOC concentrations was in all cases higher after 24 h than after 12 h. The extent of overestimation after a 24-h incubation at ~0.35 d-1 was about 23 and 40% in the cases of I. galbana and C. kessleri, respectively. Dark respiration rates estimated from changes in 14C activity during the dark period were lower than the rates estimated from changes of POC and TOC concentrations during the 12 h of darkness because only about 73% of the carbon respired during the dark period had been fixed during the previous 12-h photoperiod. The fact that the 14C method tends to overestimate net carbon assimilation by a greater percentage at low growth rates than at high growth rates probably reflects the greater efficiency of intracellular recycling of respired CO2 at high growth rates. The fact that the extent of overestimation is greater when cells are grown on a light:dark cycle probably reflects the fact that not all carbon respired in the dark was fixed during the previous photoperiod and that intracellular recycling of respired CO2 during the photoperiod is inefficient during some phases of the synchronized growth that tends to be entrained by light:dark cycles.

  19. Metabolic disposition of the anti-cancer agent [14C]laromustine in male rats

    PubMed Central

    Nassar, Ala F.; Wisnewski, Adam; King, Ivan

    2015-01-01

    Laromustine (VNP40101M, also known as Cloretazine) is a novel sulfonylhydrazine alkylating (anticancer) agent. This article describes the use of quantitative whole-body autoradiography (QWBA) and mass balance to study the tissue distribution, the excretion mass balance and pharmacokinetics after intravenous administration of [14C]VNP40101M to rats. A single 10 mg/kg IV bolus dose of [14C]VNP40101M was given to rats. The recovery of radioactivity from the Group 1 animals over a 7-day period was an average of 92.1% of the administered dose, which was accounted for in the excreta and carcass. Most of the radioactivity was eliminated within 48 h via urine (48%), with less excreted in feces (5%) and expired air accounted for (11%). The plasma half-life of [14C]laromustine was approximately 62 min and the peak plasma concentration (Cmax) averaged 8.3 μg/mL The QWBA study indicated that the drug-derived radioactivity was widely distributed to tissues through 7 days post-dose after a single 10 mg/kg IV bolus dose of [14C]VNP40101M to male pigmented Long–Evans rats. The maximum concentrations were observed at 0.5 or 1 h post-dose for majority tissues (28 of 42). The highest concentrations of radioactivity were found in the small intestine contents at 0.5 h (112.137 μg equiv/g), urinary bladder contents at 3 h (89.636 μg equiv/g) and probably reflect excretion of drug and metabolites. The highest concentrations in specific organs were found in the renal cortex at 1 h (28.582 μg equiv/g), small intestine at 3 h (16.946 μg equiv/g), Harderian gland at 3 h (12.332 μg equiv/g) and pancreas at 3 h (12.635 μg equiv/g). Concentrations in the cerebrum (1.978 μg equiv/g), cerebellum (2.109 μg equiv/g), medulla (1.797 μg equiv/g) and spinal cord (1.510 μg equiv/g) were maximal at 0.5 h post-dose and persisted for 7 days. The predicted total body and target organ exposures for humans given a single 100μCi IV dose of [14C]VNP40101M were well within the medical guidelines

  20. Flux of carbon from 14C-enriched leaf litter throughout a forest soil mesocosm

    SciTech Connect

    Froberg, Mats J.; Hanson, Paul J; Trumbore, Susan E.; Swanston, Christopher W.; Todd Jr, Donald E

    2009-01-01

    The role of DOC for the build-up of soil organic carbon pools is still not well known, but it is thought to play a role in the transport of carbon to a greater depth where it becomes more stable. The aim of this study was to elucidate within-year dynamics of carbon transport from litter to the O (Oe and Oa) and A horizons. Mesocosms with constructed soil profiles were used to study dynamics of C transport from 14C-enriched (about 1000 ) leaf litter to the Oe/Oa and A horizons as well as the mineralization of leaf litter. The mesocosms were placed in the field for 17 months during which time fluxes and 14C content of DOC and CO2 were measured. Changes in 14C in leaf litter and bulk soil C pools were also recorded. Significant simultaneous release and immobilization of DOC occurring in both the O and A horizons was hypothesized. Contrary to our hypothesis, DOC released from the labeled Oi horizon was not retained within the Oe/Oa layer. DOC originating in the unlabeled Oe/Oa layer was also released for transport. Extensive retention of DOC occurred in the A horizon. DOC leaching from A horizon consisted of a mix of DOC from different sources, with a main fraction originating in the A horizon and a smaller fraction leached from the overlaying horizons. The C and 14C budget for the litter layer also indicated a surprisingly large amount of carbon with ambient Δ14C-signature to be respired from this layer. Data for this site also suggested significant contributions from throughfall to dissolved organic carbon (DOC) transport into and respiration from the litter layer. The results from this study showed that DOC retentionwas low in the O horizon and therefore not important for the O horizon carbon budget. In the A horizon DOC retention was extensive, but annual DOC input was small compared to C stocks and therefore not important for changes in soil C on an annual timescale.

  1. A Brief Review of the Application of 14C in Terrestrial Carbon Cycle Studies

    SciTech Connect

    Guilderson, T; Mcfarlane, K

    2009-10-22

    An over-arching goal of the DOE TCP program is to understand the mechanistic controls over the fate, transport, and residence time of carbon in the terrestrial biosphere. Many of the modern process and modeling studies focus on seasonal to interannual variability. However, much of the carbon on the landscape and in soils is in separate reservoirs with turnover times that are multi-decadal to millennial. It is the controls on these longer term pools or reservoirs that is a critical unknown in the face of rising GHGs and climate change and uncertainties of the terrestrial biosphere as a future global sink or source of atmospheric CO{sub 2} [eg., Friedlingstein et al., 2006; Govindasamy et al., 2005; Thompson et al., 2004]. Radiocarbon measurements, in combination with other data, can provide insight into, and constraints on, terrestrial carbon cycling. Radiocarbon (t{sub 1/2} 5730yrs) is produced naturally in the stratosphere when secondary neutrons generated by cosmic rays collide with {sup 14}N atoms [Libby 1946; Arnold and Libby, 1949]. Upon formation, {sup 14}C is rapidly oxidized to CO and then to CO{sub 2}, and is incorporated into the carbon cycle. Due to anthropogenic activities, the amount of {sup 14}C in the atmosphere doubled in the mid/late 1950s and early 1960s from its preindustrial value of {sup 14}C/{sup 12}C ratio of 1.18 x 10{sup -12} [eg., Nydal and Lovseth, 1983]. Following the atmospheric weapons test ban in 1963, the {sup 14}C/{sup 12}C ratio, has decreased due to the net isotopic exchange between the ocean and terrestrial biosphere [eg., Levin and Hessheimer, 2000] and a dilution effect due to the burning of {sup 14}C-free fossil fuel carbon, the 'Suess Effect' [Suess, 1955]. In the carbon cycle literature, radiocarbon measurements are generally reported as {Delta}{sup 14}C, which includes a correction for mass dependent fractionation [Stuiver and Polach, 1977]. In the context of carbon cycle studies radiocarbon measurements can be used to

  2. Towards a global understanding of vertical soil carbon dynamics: meta-analysis of soil 14C data

    NASA Astrophysics Data System (ADS)

    hatte, C.; Balesdent, J.; Guiot, J.

    2012-12-01

    Soil represents the largest terrestrial storage mechanism for atmospheric carbon from photosynthesis, with estimates ranging from 1600 Pg C within the top 1 meter to 2350 Pg C for the top 3 meters. These values are at least 2.5 times greater than atmospheric C pools. Small changes in soil organic carbon storage could result in feedback to atmospheric CO2 and the sensitivity of soil organic matter to changes in temperature, and precipitation remains a critical area of research with respect to the global carbon cycle. As an intermediate storage mechanism for organic material through time, the vertical profile of carbon generally shows an age continuum with depth. Radiocarbon provides critical information for understanding carbon exchanges between soils and atmosphere, and within soil layers. Natural and "bomb" radiocarbon has been used to demonstrate the importance and nature of the soil carbon response to climatic and human impacts on decadal to millennial timescales. Radiocarbon signatures of bulk, or chemically or physically fractionated soil, or even of specific organic compounds, offer one of the only ways to infer terrestrial carbon turnover times or test ecosystem carbon models. We compiled data from the literature on radiocarbon distribution on soil profiles and characterized each study according to the following categories: soil type, analyzed organic fraction, location (latitude, longitude, elevation), climate (temperature, precipitation), land use and sampling year. Based on the compiled data, soil carbon 14C profiles were reconstructed for each of the 226 sites. We report here partial results obtained by statistical analyses of portion of this database, i.e. bulk and bulk-like organic matter and sampling year posterior to 1980. We highlight here 14C vertical pattern in relationship with external parameters (climate, location and land use).

  3. Estimation of groundwater residence time using environmental radioisotopes (14C,T) in carbonate aquifers, southern Poland.

    PubMed

    Samborska, Katarzyna; Różkowski, Andrzej; Małoszewski, Piotr

    2013-01-01

    Triassic carbonate aquifers in the Upper Silesia region, affected by intense withdrawal, have been investigated by means of isotopic analyses of (14)C, δ(13)C, δ(2)H, δ(18)O and (3)H. The isotopic examinations were carried out in the 1970s and in the early 1980s, and it was the first application of tracers to estimate age and vulnerability for the contamination of groundwater in this region. Similar isotopic analyses were conducted in 2007 and 2008 with the same Triassic carbonate formation. The isotopic examinations were performed within the confined part of the carbonate formation, wherein aquifers are covered by semi-permeable deposits. The direct recharge of the aquifer occurs in the outcrop areas, but it mainly takes place due to percolation of the water through aquitards and erosional windows. The Triassic aquifer has been intensively drained by wells and by lead-zinc mines. Nowadays, the declining water demand and closure of some mines have induced a significant increase in the water table level. The detailed analysis of the results, including the radiocarbon age corrections and the comparison of radioisotope activities, has made it possible to estimate the range of residence time within the carbonate Triassic aquifer. This range from several tens to several tens of thousands indicates that the recharge of aquifers might have occurred between modern times and the Pleistocene. The apparent age of the water estimated on the basis of (14)C activity was corrected considering the carbon isotope exchange and the diffusion between mobile water in fractures and stagnant water in micropores. The obtained corrected period of recharge corresponds to the result of investigations of noble gases, which were carried out in the 1990s. In almost half of the cases, groundwater is a mixture of young and old water. The mixing processes occur mainly in areas of heavy exploitation of the aquifer. PMID:22607326

  4. Estimation of groundwater residence time using environmental radioisotopes (14C,T) in carbonate aquifers, southern Poland.

    PubMed

    Samborska, Katarzyna; Różkowski, Andrzej; Małoszewski, Piotr

    2013-01-01

    Triassic carbonate aquifers in the Upper Silesia region, affected by intense withdrawal, have been investigated by means of isotopic analyses of (14)C, δ(13)C, δ(2)H, δ(18)O and (3)H. The isotopic examinations were carried out in the 1970s and in the early 1980s, and it was the first application of tracers to estimate age and vulnerability for the contamination of groundwater in this region. Similar isotopic analyses were conducted in 2007 and 2008 with the same Triassic carbonate formation. The isotopic examinations were performed within the confined part of the carbonate formation, wherein aquifers are covered by semi-permeable deposits. The direct recharge of the aquifer occurs in the outcrop areas, but it mainly takes place due to percolation of the water through aquitards and erosional windows. The Triassic aquifer has been intensively drained by wells and by lead-zinc mines. Nowadays, the declining water demand and closure of some mines have induced a significant increase in the water table level. The detailed analysis of the results, including the radiocarbon age corrections and the comparison of radioisotope activities, has made it possible to estimate the range of residence time within the carbonate Triassic aquifer. This range from several tens to several tens of thousands indicates that the recharge of aquifers might have occurred between modern times and the Pleistocene. The apparent age of the water estimated on the basis of (14)C activity was corrected considering the carbon isotope exchange and the diffusion between mobile water in fractures and stagnant water in micropores. The obtained corrected period of recharge corresponds to the result of investigations of noble gases, which were carried out in the 1990s. In almost half of the cases, groundwater is a mixture of young and old water. The mixing processes occur mainly in areas of heavy exploitation of the aquifer.

  5. Unsaturated zone 14CO2: implications for groundwater dating

    NASA Astrophysics Data System (ADS)

    Wood, C.; Cook, P. G.; Harrington, G. A.; Meredith, K.; Kipfer, R.

    2013-12-01

    depths). Several scenarios have been run to assess the effect of changes in recharge rate and watertable depth on unsaturated zone 14C. This helps us understand under what hydrogeological conditions the influence of unsaturated zone processes on 14C becomes significant, which has important implications for using 14C in groundwater dating projects. The results of this work are particularly important in arid environments where groundwater residence time is typically long (>1,000 years old), recharge is low and unsaturated zones may be deep (>10m).

  6. Proton production cross sections of {sup 14}C from silicon and oxygen: Implications for cosmic-ray studies

    SciTech Connect

    Sisterson, J.M.; Jull, A.J.T.; Beverding, A.

    1993-12-31

    The production rates of {sup 14}C from proton spallation of silicon, and oxygen have been measured over a wide range of energies from 31 to 450 MeV. {sup 14}C was measured by accelerator mass spectrometry (AMS) after extraction of carbon from the samples by melting in a flow of oxygen.

  7. Accuracy and precision of 14C-based source apportionment of organic and elemental carbon in aerosols using the Swiss_4S protocol

    NASA Astrophysics Data System (ADS)

    Mouteva, G. O.; Fahrni, S. M.; Santos, G. M.; Randerson, J. T.; Zhang, Y.-L.; Szidat, S.; Czimczik, C. I.

    2015-09-01

    , based on multiple measurements of ultra-small samples. The extraction procedure (Swiss_4S protocol and cryo-trapping only) contributed 0.37 ± 0.18 μg of modern carbon and 0.13 ± 0.07 μg of fossil carbon to the total blank of our system, with consistent estimates obtained for the two laboratories. There was no difference in the background correction between the OC and EC fractions. Our setup allowed us to efficiently isolate and trap each carbon fraction with the Swiss_4S protocol and to perform 14C analysis of ultra-small OC and EC samples with high accuracy and low 14C blanks.

  8. Accuracy and precision of 14C-based source apportionment of organic and elemental carbon in aerosols using the Swiss_4S protocol

    NASA Astrophysics Data System (ADS)

    Mouteva, G. O.; Fahrni, S. M.; Santos, G. M.; Randerson, J. T.; Zhang, Y. L.; Szidat, S.; Czimczik, C. I.

    2015-04-01

    , based on multiple measurements of ultra-small samples. The Swiss_4S protocol and the cryo-trapping contributed 0.37 ± 0.18 μg of modern carbon and 0.13 ± 0.07 μg of fossil carbon to the estimated blanks, with consistent estimates obtained for the two laboratories. There was no difference in the background correction between the OC and EC fractions. Our set-up allowed us to efficiently isolate and trap each carbon fraction with the Swiss_4S protocol and to perform 14C analysis of ultra-small OC and EC samples with high accuracy and low 14C blanks.

  9. Low energy cyclotron for radiocarbon dating

    SciTech Connect

    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 /sup 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 /sup 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 /sup 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.

  10. Use of an intravenous microdose of 14C-labeled drug and accelerator mass spectrometry to measure absolute oral bioavailability in dogs; cross-comparison of assay methods by accelerator mass spectrometry and liquid chromatography-tandem mass spectrometry.

    PubMed

    Miyaji, Yoshihiro; Ishizuka, Tomoko; Kawai, Kenji; Hamabe, Yoshimi; Miyaoka, Teiji; Oh-hara, Toshinari; Ikeda, Toshihiko; Kurihara, Atsushi

    2009-01-01

    A technique utilizing simultaneous intravenous microdosing of (14)C-labeled drug with oral dosing of non-labeled drug for measurement of absolute bioavailability was evaluated using R-142086 in male dogs. Plasma concentrations of R-142086 were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and those of (14)C-R-142086 were measured by accelerator mass spectrometry (AMS). The absence of metabolites in the plasma and urine was confirmed by a single radioactive peak of the parent compound in the chromatogram after intravenous microdosing of (14)C-R-142086 (1.5 microg/kg). Although plasma concentrations of R-142086 determined by LC-MS/MS were approximately 20% higher than those of (14)C-R-142086 as determined by AMS, there was excellent correlation (r=0.994) between both concentrations after intravenous dosing of (14)C-R-142086 (0.3 mg/kg). The oral bioavailability of R-142086 at 1 mg/kg obtained by simultaneous intravenous microdosing of (14)C-R-142086 was 16.1%, this being slightly higher than the value (12.5%) obtained by separate intravenous dosing of R-142086 (0.3 mg/kg). In conclusion, on utilizing simultaneous intravenous microdosing of (14)C-labeled drug in conjunction with AMS analysis, absolute bioavailability could be approximately measured in dogs, but without total accuracy. Bioavailability in humans may possibly be approximately measured at an earlier stage and at a lower cost. PMID:19430168

  11. Uptake of (/sup 14/C)deoxyglucose into brain of young rats with inherited hydrocephalus

    SciTech Connect

    Richards, H.K.; Bucknall, R.M.; Jones, H.C.; Pickard, J.D.

    1989-02-01

    The effect of hydrocephalus on cerebral glucose utilization as reflected by deoxyglucose uptake has been examined in rats with inherited hydrocephalus at 10, 20, and 28 days after birth using a semiquantitative method. Injection of (14C)deoxyglucose intraperitoneally was followed by freezing the brain, sectioning, and quantitative autoradiography of 10 brain regions. Brain (14C) concentration, cortical thickness, and plasma glucose concentrations were measured. Maximal thinning of the cerebral cortex had already occurred by 10 days after birth, although obvious symptoms such as gait disturbance developed after 20 days. In control rats, the cerebral isotope concentration was lower and more homogeneous at 10 days than at 20 or 28 days, which may be a reflection of the use of metabolic substrates other than glucose in younger animals. In order to make comparisons between control and hydrocephalic groups, tissue isotope concentrations were normalized to cerebellar cortex which was not affected by the hydrocephalus at any age. In hydrocephalic rats at 10 and 20 days, the concentration of (14C) was lower in all areas except the inferior colliculi and pons but the reduction was only significant in the sensory-motor cortex at 10 days and in the caudate nuclei at 20 days. By 28 days after birth, all areas except the cerebellum (six cortical regions, inferior colliculi, pons, and caudate) had significantly lower isotope concentrations in the hydrocephalic group. It is concluded that cerebral glucose metabolism is significantly reduced by 28 days after birth in H-Tx rats with congenital hydrocephalus and that less marked reductions occur prior to 28 days.

  12. Concentrations and 14C age of nonstructural carbon in California oaks

    NASA Astrophysics Data System (ADS)

    Czimczik, C. I.; Druffel-Rodriguez, K.; Trumbore, S. E.

    2008-12-01

    Plants store photosynthetic assimilates as nonstructural carbon (NSC), mainly glucose, fructose, sucrose, and starch. NSC fuels processes such as respiration and growth. Research suggests that NSC represents a significant fraction of a plant's annual C budget, but temporal dynamics of NSC are poorly understood. We used concentration and radiocarbon (14C) measurements of NSC to investigate how temporal dynamics of NSC vary with life strategy and throughout a species' range. In Mediterranean environments, oaks have developed two strategies (evergreen and deciduous) to cope with drought. Within California, the uncertainty of annual winter rain increases from north to south. We compared two evergreen and deciduous species: Coastal and Interior live oak (Quercus agrifolia and wislizenii) and Valley and Blue oak (Q. lobata and douglasii). Samples (4 mm cores to 20 cm depth at dbh) were taken in 2008 before leaf-out and fall at five sites which represent an inland to coast temperature gradient from high to low summer temperatures as well as a north- south precipitation gradient. Sugars were isolated by shaking in methanol-water and quantified using a spectrometric micro-plate technique. Starch was isolated by boiling in ethanol followed by HCl digestion and quantified manometrically. 14C contents were measured by AMS. Preliminary findings indicate that in live oaks, winter sugar concentrations are constant throughout the tree and across sites, while 14C concentrations increase towards a tree's center. This suggests that the NSC pool oaks is not well mixed. Future work will elucidate whether plants can access these older NSC stores.

  13. Using 14C and 3H to understand groundwater flow and recharge in an aquifer window

    NASA Astrophysics Data System (ADS)

    Atkinson, A. P.; Cartwright, I.; Gilfedder, B. S.; Cendón, D. I.; Unland, N. P.; Hofmann, H.

    2014-06-01

    Knowledge of groundwater residence times and recharge locations are vital to the sustainable management of groundwater resources. Here we investigate groundwater residence times and patterns of recharge in the Gellibrand Valley, southeast Australia, where outcropping aquifer sediments of the Eastern View Formation form an "aquifer window" that may receive diffuse recharge and recharge from the Gellibrand River. To determine recharge patterns and groundwater flowpaths, environmental isotopes (3H, 14C, δ13C, δ18O, δ2H) are used in conjunction with groundwater geochemistry and continuous monitoring of groundwater elevation and electrical conductivity. Despite the water table fluctuating by 0.9-3.7 m annually producing estimated recharge rates of 90 and 372 mm yr-1, residence times of shallow (11-29 m) groundwater determined by 14C ages are between 100 and 10 000 years. 3H activities are negligible in most of the groundwater and groundwater electrical conductivity in individual areas remains constant over the period of study. Although diffuse local recharge is evident, the depth to which it penetrates is limited to the upper 10 m of the aquifer. Rather, groundwater in the Gellibrand Valley predominantly originates from the regional recharge zone, the Barongarook High, and acts as a regional discharge zone where upward head gradients are maintained annually, limiting local recharge. Additionally, the Gellibrand River does not recharge the surrounding groundwater and has limited bank storage. 14C ages and Cl concentrations are well correlated and Cl concentrations may be used to provide a first-order estimate of groundwater residence times. Progressively lower chloride concentrations from 10 000 years BP to the present day are interpreted to indicate an increase in recharge rates on the Barongarook High.

  14. Binding of mescaline with subcellular fractions upon incubation of brain cortex slices with [14C] mescaline.

    PubMed

    Datta, R K; Antopol, W; Ghosh, J J

    1977-01-01

    Incubation of brain cortex slices in the presence of glucose resulted in the permeation of about 65% of [14C] mescaline into slices. Of this, about one-third radioactivity was bound with nuclei, mitochondria, microsomes, and ribosomes. Dialysis of subcellular fractions did not markedly reduce the amounts of radioactivity bound to the fractions. The permeation into slices and the binding of mescaline to subcellular fractions were fairly time-dependent, but were inhibited by the presence of potassium cyanide, or by the absence of glucose and by heating to 80 degrees C for 1 min.

  15. Searching For A Suitable Gas Ion Source For 14C Accelerator Mass Spectrometry

    SciTech Connect

    Reden, Karl von; Roberts, Mark; Han, Baoxi; Schneider, Robert; Wills, John

    2007-08-10

    This paper describes the challenges facing 14C Accelerator Mass Spectrometry (AMS) in the effort to directly analyze the combusted effluent of a chromatograph (or any other continuous source of sample material). An efficient, low-memory negative gas ion source would greatly simplify the task to make this a reality. We discuss our tests of a microwave ion source charge exchange canal combination, present an improved design, and hope to generate more interest in the negative ion source community to develop a direct-extraction negative carbon gas ion source for AMS.

  16. A batch preparation method for graphite targets with low background for AMS [sup 14]C measurements

    SciTech Connect

    Kitagawa, Hiroyuki International Research Center for Japanese Studies, Nishikyp-ku, Kyoto ); Masuzawa, Toshiyuki; Matsumoto, Eiji ); Makamura, Toshio )

    1993-01-01

    The authors have developed a method of graphitization from CO[sub 2] samples for accurate [sup 14]C measurements by accelerator mass spectrometry. Their batch method, using a sealed Vycor tube, reduces the risk of contamination during graphitization and makes it possible to prepare many samples in a short time (typically 20 samples per day). They also describe details of the target-preparation method involving carbon isotopic fractionation during graphitization, yield of graphite from CO[sub 2], ion-beam intensity of the target, and background (or blank) level estimated using bituminous coal.

  17. Transformation of (14)C-pyrimidynyloxybenzoic herbicide ZJ0273 in aerobic soils.

    PubMed

    Haiyan, Wang; Zhiyang, Yu; Ling, Yue; Ailiang, Han; Yanfei, Zhang; Juying, Li; Qingfu, Ye; Zhengmin, Yang; Long, Lu

    2010-04-15

    A soil metabolism study of propyl 4-(2-(4,6-dimethoxypyrimidin-2-yloxy)benzylamino)benzoate (ZJ0273), a novel broad-spectrum herbicide, was carried out using (14)C labeled on two different rings, i.e., [pyrimidine-4,6-(14)C] ZJ0273 and [benzyl-U-(14)C] ZJ0273. Ultralow liquid scintillation counting and LC-MS/MS were used to identify the degradation intermediates and quantify their dynamics in aerobic soils. Four aromatic intermediates, 4-(2-(4,6-dimethoxypyrimidin-2-yloxy)benzylamino)benzoic acid (M1), 4-(2-(4,6-dimethoxypyrimidin-2-yloxy)benzamido)benzoic acid (M2), 2-(4,6-dimethoxypyrimidin-2-yloxy)benzoic acid (M3), and 4,6-dimethoxypyrimidin-2-ol (M4), were identified and their identity was further confirmed against authentic standards. Analysis of metabolites suggested two degradation pathways: (1) Upon loss of the propyl group, M1 was produced via hydrolysis of propyl 4-(2-(4,6-dimethoxypyrimidin-2-yloxy)benzylamino)benzoate after which the C-N bond between rings A and B was cleaved by oxidation and biochemical degradation to yield M3, which was further converted into M4 and finally mineralized to CO(2); and (2) the first step was the same as in pathway 1, but M1 first underwent a carbonylation to form M2. The C-N bond between rings A and B of M2 was cleaved by hydrolysis to yield M3. Dynamic changes in the four metabolites in aerobic soils were also investigated by HPLC coupled analysis of radioactivity of isolated peaks. After a 100-day incubation, 1.7-9.7% of applied (14)C was found as M1, 0.3-1.1% as M2, 14.5-20.9% as M3, and 3.7-6.7% as M4 in the soils, and pH appeared to be the most influential soil property affecting the formation and dissipation of these metabolites.

  18. Excised barley root uptake of several /sup 14/C labeled organic compounds

    SciTech Connect

    McFarlane, C.; Wickliff, C.

    1985-01-01

    Many organic pollutants potentially are available for uptake by plants and thus bioaccumulation and food contamination. One method of studying uptake is with excised roots, a technique extensively used with plant nutrients. A similar method was developed and used to evaluate uptake patterns of several /sup 14/C-labeled organic chemicals. Uptake rate constants for the chemicals tested occurred in the following order: captan approx. phenol > aniline > ethanol approx. indole approx. trifluralin approx. propanil > 1,2,4-trichlorobenzene(TCB) > nitrobenzene approx. atrazine > bromacil > simazine > monuron.

  19. [The auditory pathway in guinea pigs. A [14C]2-deoxyglucose study (author's transl)].

    PubMed

    Strutz, J; Beck, C; Schmidt, C L

    1981-01-01

    The auditory pathway of guinea pigs was labeled with [14C]-deoxyglucose after mon- or binaural stimulation with farfield white noise in a sound-proof chamber. In the autoradiographs, all auditory nuclei were labeled. The highest metabolic effects were seen in the dorsal cochlear nucleus, the lateral superior olivary nucleus, and in the inferior colliculus. No selective labeling was observed in the auditory cortex. Monaural stimulation depressed the metabolic activity contralaterally in the ventral cochlear nucleus and ipsilaterally in the medial nucleus of the trapezoid body, the dorsomedial periolivary nucleus, and in the inferior colliculus. PMID:7213192

  20. Accelerated degradation of 14C-atrazine in an atrazine adapted field soil from Belgium

    NASA Astrophysics Data System (ADS)