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Sample records for radiocarbon 14c determination

  1. DEVELOPMENT & APPLICATION OF RADIOCARBON (14C)/ORGANIC DENUDER METHODS

    EPA Science Inventory

    The radiocarbon (14C) content of a sample measures the fraction of the sample's carbon originating from non-fossil-fuel (biogenic) sources. The most important of these sources are biomass burning (mostly winter, but wildfires can contribute in other seasons as well) and secondar...

  2. Growth rate determinations from radiocarbon in bamboo corals (genus Keratoisis)

    NASA Astrophysics Data System (ADS)

    Farmer, Jesse R.; Robinson, Laura F.; Hönisch, Bärbel

    2015-11-01

    Radiocarbon (14C) measurements are an important tool for determining growth rates of bamboo corals, a cosmopolitan group of calcitic deep-sea corals. Published growth rate estimates for bamboo corals are highly variable, with potential environmental or ecological drivers of this variability poorly constrained. Here we systematically investigate the application of 14C for growth rate determinations in bamboo corals using 55 14C dates on the calcite and organic fractions of six bamboo corals (identified as Keratoisis sp.) from the western North Atlantic Ocean. Calcite 14C measurements on the distal surface of these corals and five previously published bamboo corals exhibit a strong one-to-one relationship with the 14C of dissolved inorganic carbon (DI14C) in ambient seawater (r2=0.98), confirming the use of Keratoisis sp. calcite 14C as a proxy for seawater 14C activity. Radial growth rates determined from 14C age-depth regressions, 14C plateau tuning and bomb 14C reference chronologies range from 12 to 78 μm y-1, in general agreement with previously published radiometric growth rates. We document potential biases to 14C growth rate determinations resulting from water mass variability, bomb radiocarbon, secondary infilling (ontogeny), and growth rate nonlinearity. Radial growth rates for Keratoisis sp. specimens do not correlate with ambient temperature, suggesting that additional biological and/or environmental factors may influence bamboo coral growth rates.

  3. 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.

  4. Toward Radiocarbon Measurement of Individual Amino Acids in Marine Dissolved Organic Matter (DOM): Δ14C Blank Quantification for an HPLC Purification Method.

    NASA Astrophysics Data System (ADS)

    Bour, A. L.; Broek, T.; Walker, B. D.; Mccarthy, M. D.

    2014-12-01

    The presence of much of the marine dissolved organic nitrogen (DON) pool as uncharacterized, biologically recalcitrant molecules is a central mystery in the marine nitrogen cycle. Radiocarbon14C) isotopic measurements have been perhaps the most important data constraining the cycling of dissolved organic matter (DOM), but little Δ14C data specific to DON is available. Amino acids (AAs) are the major component of DON that can be isolated on a molecular level. Δ14C measurements for the operational "protein-like" fraction of DOM in the deep ocean indicate that this compound class has radiocarbon ages greater than several ocean mixing cycles, suggesting remarkable preservation of labile AAs exported from the surface. However, it is possible that the previously defined operational "protein-like" fraction may also contain non-AA material. Radiocarbon measurement of purified individual AAs would provide a more direct and reliable proxy for DON Δ14C age and cycling rate. We present here Δ14C blank characterization of an AA purification method based on HPLC, with on-line fraction collection. This method allows the recovery of unmodified AAs, but accurate measurement of small AA samples that can be extracted from DOM requires a system with extremely low Δ 14C blanks. Here we assess the impact of HPLC purification on the Δ14C age of known amino acids standards. Individual AA standards with contrasting (modern vs. dead) and well- characterized Δ14C ages were processed in a range of sample sizes. The eluted peaks were collected and dried, and measurement of their post-chromatography Δ14C content allowed for determination of the Δ14C blank by method of additions. The same protocol was applied to a mixture of six AA standards, to evaluate tailing effects in consecutive AA peaks of contrasting Δ14C age. AA standards were selected to include both Δ14C modern and dead AAs that elute both early and late in the chromatographic solvent program. We discuss implications

  5. Radiocarbon ( 14C) measurements to quantify sources of atmospheric carbon monoxide in urban air

    NASA Astrophysics Data System (ADS)

    Klouda, George A.; Connolly, Michael V.

    Atmospheric air samples were collected during the winter of 1989-1990 in Albuquerque, NM, U.S.A., for radiocarbon ( 14C) analysis of carbon monoxide (CO). An experimental sample design was prepared to target periods when the concentration of CO exceeds the 9 μl l-1 (volume fraction), 8 h National Ambient Air Quality Standard (NAAQS) and during periods of attainment. Sampling sites, time of day, sampling duration, and meteorology were carefully considered so that source impacts be optimal. A balanced sampling factorial design was used to yield maximum information from the constraints imposed; the number of samples was limited by the number of sample canisters available, time and resources. Radiocarbon measurements of urban CO, " clean-air" CO background from Niwot Ridge, Colorado, average (wood) logs and oxygenated-gasolines were used in a three-source model to calculate the contribution of wood burning to the total atmospheric CO burden in Albuquerque. Results show that the estimated fractional contribution of residential wood combustion (Θ' Rwc) ranged from 0 to 0.30 of CO concentrations corrected for " clean-air" background. For these same samples, the respective CO concentrations attributed to wood burning range from 0 to 0.90 μmol mol -1 (mole fraction), well below the NAAQS. In all cases, fossil CO is the predominant source of ambient CO concentrations ranging from 0.96 to 6.34 μmol mol -1 A final comment is made on the potential of fossil CO measurements as an indirect tracer of atmospheric benzene, relevant to exposure risk estimates of motor vehicle emissions and occupational health and safety standards.

  6. 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.

  7. Contemporary 14C radiocarbon levels of oxygenated polybrominated diphenyl ethers (O-PBDEs) isolated in sponge–cyanobacteria associations

    PubMed Central

    Guitart, Carlos; Slattery, Marc; Ankisetty, Sridevi; Radwan, Mohamed; Ross, Samir J.; Letcher, Robert J.; Reddy, Christopher M.

    2016-01-01

    Considerable debate surrounds the sources of oxygenated polybrominated diphenyl ethers (O-PBDEs) in wildlife as to whether they are naturally produced or result from anthropogenic industrial activities. Natural radiocarbon (14C) abundance has proven to be a powerful tool to address this problem as recently biosynthesized compounds contain contemporary (i.e. modern) amounts of atmospheric radiocarbon; whereas industrial chemicals, mostly produced from fossil fuels, contain no detectable 14C. However, few compounds isolated from organisms have been analyzed for their radiocarbon content. To provide a baseline, we analyzed the 14C content of four O-PBDEs. These compounds, 6-OH-BDE47, 2′-OHBDE68, 2′,6-diOH-BDE159, and a recently identified compound, 2′-MeO-6-OH-BDE120, were isolated from the tropical marine sponges Dysidea granulosa and Lendenfeldia dendyi. The modern radiocarbon content of their chemical structures (i.e. diphenyl ethers, C12H22O) indicates that they are naturally produced. This adds to a growing baseline on, at least, the sources of these unusual compounds. PMID:21276990

  8. Accumulation of Sellafield-derived radiocarbon ((14)C) in Irish Sea and West of Scotland intertidal shells and sediments.

    PubMed

    Tierney, Kieran M; Muir, Graham K P; Cook, Gordon T; MacKinnon, Gillian; Howe, John A; Heymans, Johanna J; Xu, Sheng

    2016-01-01

    The nuclear energy industry produces radioactive waste at various stages of the fuel cycle. In the United Kingdom, spent fuel is reprocessed at the Sellafield facility in Cumbria on the North West coast of England. Waste generated at the site comprises a wide range of radionuclides including radiocarbon ((14)C) which is disposed of in various forms including highly soluble inorganic carbon within the low level liquid radioactive effluent, via pipelines into the Irish Sea. This (14)C is rapidly incorporated into the dissolved inorganic carbon (DIC) reservoir and marine calcifying organisms, e.g. molluscs, readily utilise DIC for shell formation. This study investigated a number of sites located in Irish Sea and West of Scotland intertidal zones. Results indicate (14)C enrichment above ambient background levels in shell material at least as far as Port Appin, 265 km north of Sellafield. Of the commonly found species (blue mussel (Mytilus edulis), common cockle (Cerastoderma edule) and common periwinkle (Littorina littorea)), mussels were found to be the most highly enriched in (14)C due to the surface environment they inhabit and their feeding behaviour. Whole mussel shell activities appear to have been decreasing in response to reduced discharge activities since the early 2000s but in contrast, there is evidence of continuing enrichment of the carbonate sediment component due to in-situ shell erosion, as well as indications of particle transport of fine (14)C-enriched material close to Sellafield. PMID:26555367

  9. A survey of methane isotope abundance (14C, 13C, 2H) from five nearshore marine basins that reveals unusual radiocarbon levels in subsurface waters

    NASA Astrophysics Data System (ADS)

    Kessler, J. D.; Reeburgh, W. S.; Valentine, D. L.; Kinnaman, F. S.; Peltzer, E. T.; Brewer, P. G.; Southon, J.; Tyler, S. C.

    2008-12-01

    Methane (CH4) in the subsurface ocean is often supersaturated compared to equilibrium with the modern atmosphere. In order to investigate sources of CH4 to the subsurface ocean, isotope surveys (14C-CH4,δ13C-CH4, δ2H-CH4) were conducted at five locations: Skan Bay (SB), Santa Barbara Basin (SBB), Santa Monica Basin (SMB), Cariaco Basin (CB), and the Guaymas Basin (GB). Depth distributions of CH4 concentration and isotopic abundance were determined for both the sediment and water column at the SB, SBB, SMB, and CB sites; CH4 emitted from seeps on the continental shelf adjacent to the SBB as well as seeps and decomposing clathrate hydrates in the GB was also collected, purified, and analyzed. Methane isotope distributions in the sediments were consistent with known methanogenic and methanotrophic activity; seep- and clathrate-hydrate-derived CH4 was found to be depleted in radiocarbon. However, surprising results were obtained in the water column at all sites investigated. In SB the radiocarbon content of the subsurface CH4 concentration maximum was on average 41% less than its suspected sediment CH4 source, suggesting CH4 seepage in the bay. In the SBB, SMB, and CB, the 14C-CH4 contents in the subsurface ocean were 1.2 to 3.6 times greater than modern carbon quantities suggesting a source of 14C from atmospheric nuclear weapons testing, nuclear power plant effluents, or cosmogenic isotope production.

  10. RADIOCARBON 14C MEASUREMENTS ON ATMOSPHERIC SAMPLES OF PARTICULATE MATTER (& VOLATILE ORGANIC COMPOUNDS)

    EPA Science Inventory

    Following a brief history of radiocarbon work at EPA since the 1980's, the presentation focuses on recent non-winter measurements for PM-2.5 in the Southeastern U.S. (Houston, TX; Nashville, TN; and particularly, Tampa, FL) and what the measurements suggest about the importance o...

  11. Radiocarbon

    NASA Astrophysics Data System (ADS)

    Broecker, W. S.

    2003-12-01

    Willard Libby's invention of the radiocarbon dating method revolutionized the fields of archeology and Quaternary geology because it brought into being a means to correlate events that occurred during the past 3.5×104 years on a planet-wide scale (Libby et al., 1949). This contribution was recognized with the award of the Nobel Prize for Chemistry. In addition, radiocarbon measurements have been a boon to the quantification of many processes taking place in the environment, to name a few: the rate of "ventilation" of the deep ocean, the turnover time of humus in soils, the rate of growth of cave deposits, the source of carbon-bearing atmospheric particulates, the rates of gas exchange between the atmosphere and water bodies, the replacement time of carbon atoms in human tissue, and depths of bioturbation in marine sediment. Some of these applications have been greatly aided by the creation of excess 14C atoms as the result of nuclear tests conducted in the atmosphere. Since the 1960s, this so-called bomb radiocarbon has made its way into all of the Earth's active carbon reservoirs. To date, tens of thousands of radiocarbon measurements have been made in laboratories throughout the world.

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

    SciTech Connect

    Buchholz, B A; Spalding, K L

    2009-03-10

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

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

    PubMed Central

    Buchholz, B.A.; Spalding, K.L

    2010-01-01

    Radiocarbon dating is typically an archaeological tool rather than a forensic one. Recently however, we have shown that the amount of radiocarbon present in tooth enamel, as a result of nuclear bomb testing during the cold war, is a remarkably accurate indicator of when a person is born. Enamel isolated from human teeth is processed to form graphite and carbon-14 (14C) levels are measured using accelerator mass spectrometry. Since there is no turnover of enamel after it is formed, 14C levels in the enamel represent 14C levels in the atmosphere at the time of its formation. In this paper we describe the strategy used to determine the date of birth of an individual based on radiocarbon levels in tooth enamel, focusing on the methodology of this strategy. Year of birth information can significantly assist police investigators when the identity of a deceased individual is unknown. In such cases police will try to match particulars of the unidentified individual (which is often only gender and/or an estimate of age), with particulars from missing persons lists. PMID:20976120

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

    PubMed

    Buchholz, B A; Spalding, K L

    2010-05-01

    Radiocarbon dating is typically an archaeological tool rather than a forensic one. Recently however, we have shown that the amount of radiocarbon present in tooth enamel, as a result of nuclear bomb testing during the cold war, is a remarkably accurate indicator of when a person is born. Enamel isolated from human teeth is processed to form graphite and carbon-14 ((14)C) levels are measured using accelerator mass spectrometry. Since there is no turnover of enamel after it is formed, (14)C levels in the enamel represent (14)C levels in the atmosphere at the time of its formation. In this paper we describe the strategy used to determine the date of birth of an individual based on radiocarbon levels in tooth enamel, focusing on the methodology of this strategy. Year of birth information can significantly assist police investigators when the identity of a deceased individual is unknown. In such cases police will try to match particulars of the unidentified individual (which is often only gender and/or an estimate of age), with particulars from missing persons lists. PMID:20976120

  15. 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

  16. 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

  17. Redundant 230Th/ 234U/ 238U, 231Pa/ 235U and 14C dating of fossil corals for accurate radiocarbon age calibration

    NASA Astrophysics Data System (ADS)

    Chiu, Tzu-Chien; Fairbanks, Richard G.; Mortlock, Richard A.; Cao, Li; Fairbanks, Todd W.; Bloom, Arthur L.

    2006-09-01

    230Th/ 234U/ 238U dating of fossil corals by mass spectrometry is remarkably precise, but some samples exposed to freshwater over thousands of years may gain and/or lose uranium and/or thorium and consequently yield inaccurate ages. Although a δ 234U initial value equivalent to modern seawater and modern corals has been an effective quality control criterion, for samples exposed to freshwater but having δ 234U initial values indistinguishable from modern seawater and modern corals, there remains a need for additional age validation in the most demanding applications such as the 14C calibration (Fairbanks et al., 2005. Radiocarbon calibration curve spanning 0 to 50,000 years BP based on paired 230Th/ 234U/ 238U and 14C dates on pristine corals. Quaternary Science Reviews 24(16-17), 1781-1796). In this paper we enhance screening criteria for fossil corals older than 30,000 years BP in the Fairbanks0805 radiocarbon calibration data set (Fairbanks et al., 2005) by measuring redundant 230Th/ 234U/ 238U and 231Pa/ 235U dates via multi-collector magnetic sector inductively coupled plasma mass spectrometry (MC-MS-ICPMS) using techniques described in Mortlock et al. (2005. 230Th/ 234U/ 238U and 231Pa/ 235U ages from a single fossil coral fragment by multi-collector magnetic-sector inductively coupled plasma mass spectrometry. Geochimica et Cosmochimica Acta 69(3), 649-657.). In our present study, we regard paired 231Pa/ 235U and 230Th/ 234U/ 238U ages concordant when the 231Pa/ 235U age (±2 σ) overlaps with the associated 230Th/ 234U/ 238U age (±2 σ). Out of a representative set of 11 Fairbanks0805 (Fairbanks et al., 2005) radiocarbon calibration coral samples re-measured in this study, nine passed this rigorous check on the accuracy of their 230Th/ 234U/ 238U ages. The concordancy observed between 230Th/ 234U/ 238U and 231Pa/ 235U dates provides convincing evidence to support closed system behavior of these fossil corals and validation of their 230Th/ 234U/ 238U

  18. A Process-based Study of Speleothem 14C Variability: Climatic Controls and Prospects for Speleothem-based Radiocarbon Calibration

    NASA Astrophysics Data System (ADS)

    Johnson, K. R.; Magana, A. L.; Hu, C.; Ruan, J.

    2011-12-01

    Recent studies have shown that speleothems may be useful for improving the 14C calibration curve, primarily because: (1) they can be absolutely dated with the U-Th method, (2) they obtain the majority of their carbon directly from the atmosphere, and (3) the "dead carbon fraction" (DCF) obtained from the carbonate bedrock has been shown to be fairly constant over long time periods. In order to assess the stability of DCF, and hence the validity of speleothem based calibration curves, however, it is necessary to conduct detailed studies in modern cave systems and on well-dated stalagmites that overlap with the tree-ring 14C record. We will present results of a study at Heshang Cave, Hubei Province, China (30°27'N, 110°25'E; 294 m), the site of ongoing, extensive modern calibration and paleoclimate reconstruction efforts. We have conducted a detailed study of C cycling in the modern cave system through collection and analysis of the δ13C and Δ14C composition of soil CO2, dripwater DIC, and monthly modern calcite samples to investigate how seasonal environmental changes impact speleothem DCF and δ13C. In addition, we have investigated climatic controls on DCF on longer timescales through high-resolution 14C analysis of an annually laminated, U-Th dated Holocene stalagmite. Modern calcite from a site near the cave entrance shows significant seasonal Δ14C variability, ranging from 30 to 65%, which may reflect seasonal variability in atmospheric Δ14C. This suggests that cave dripwater DIC may sometimes equilibrate with cave air CO2, prior to calcite precipitation. Despite a large range in the Δ14C values of dripwater DIC samples collected from throughout the cave, individual speleothem DCF appears quite constant over the Holocene, at 9.3 ± 1.9%, with an average age offset of 838 ± 187 years. Applying this constant DCF correction over the Holocene yields an excellent correlation with the IntCal09 curve (r2 = 0.99). While minor DCF variability could introduce

  19. A reconstruction of radiocarbon production and total solar irradiance from the Holocene 14C and CO2 records: implications of data and model uncertainties

    NASA Astrophysics Data System (ADS)

    Roth, Raphael; Joos, Fortunat

    2013-04-01

    Past atmospheric CO2 concentrations reconstructed from polar ice cores [Monnin et al., 2004] combined with its Δ14C signature as conserved in tree-rings [Reimer et al., 2009] provide important information both on the cycling of carbon as well as the production of radiocarbon in the atmosphere. As the 14C production rate (Q) is modulated by changes in the strength of the magnetic field enclosed in solar wind, it serves as a valuable proxy for past changes in solar activity. Using the Bern3D-LPX, a fully featured Earth System Model of Intermediate Complexity (EMIC) with a 3D ocean and a dynamic vegetation model component, we perform transient carbon-cycle simulations spanning the past 21 kyr. By solving the atmospheric 14C budget, the radiocarbon production rate over the Holocene is reconstructed. Applying different deglacial forcings, as well as a control-simulation with constant climate, the sensitivity of Q to carbon-cycle changes is discussed. The error in the terrestrial 14C record is translated into an uncertainty in Q using a Monte-Carlo approach. In addition, uncertainties in the global carbon inventory, GPP and air-sea gas-exchange are taken into account. The estimated modern (1950-2005) production rate of 1.55±0.20 atoms/cm2/s is close to a recent theoretical calculations by Kovaltsov et al. (2012) yielding a modern production rate of 1.64 atoms/cm2/s but considerably lower than the estimated 2 atoms/cm2/s by Masarik and Beer (2009). The newly produced production rate record is then interpreted as a proxy for solar activity changes in the past 10 kyrs. To do so, we use published results from particle simulations [Masarik and Beer, 1999] together with the latest reconstruction of the geomagnetic dipole moment [Knudsen et al., 2008] to calculate the past history of the so-called solar modulation potential (Φ). The 14C based Φ is extended to 2005 A.D. with instrumental data [Usoskin et al., 2011]. In a subsequent step, Φ is translated into past

  20. A reconstruction of radiocarbon production and total solar irradiance from the Holocene 14C and CO2 records: implications of data and model uncertainties

    NASA Astrophysics Data System (ADS)

    Roth, R.; Joos, F.

    2013-03-01

    Past atmospheric CO2 concentrations reconstructed from polar ice cores combined with its Δ14C signature as conserved in tree-rings provide important information both on the cycling of carbon as well as the production of radiocarbon (Q) in the atmosphere. The latter is modulated by changes in the strength of the magnetic field enclosed in the solar wind and is a proxy for past changes in solar activity. We perform transient carbon-cycle simulations spanning the past 21 kyr using Bern3D-LPX, a fully featured Earth System Model of Intermediate Complexity (EMIC) with a 3-D ocean, sediment and a dynamic vegetation model. Using the latest atmospheric IntCal09/SHCal04 radiocarbon records, we reconstruct the Holocene radiocarbon fluxes and the total production rate. Our carbon-cycle based modern estimate of Q ≈ 1.7 atoms cm-2 s-1 is lower than previously reported by Masarik and Beer (2009) and more in line with Kovaltsov et al. (2012). Q is then translated into the solar modulation potential (Φ) using the latest geomagnetic field reconstruction and linked to a recent reanalysis of early instrumental data. In contrast to earlier reconstructions, our record suggests that periods of high solar activity (>600 MeV) were quite common not only in recent millennia but throughout the Holocene. Solar activity in our decadally-smoothed record is during 28% of the time higher than the modern average of 650 MeV during the past 9 ka. But due to considerable uncertainties in the normalization of Φ to instrumental data, the absolute value of Φ remains weakly constrained. Further, our simulations with a spatially resolved model (taking the interhemispheric Δ14C gradient into account) show that reconstructions that rely on the Northern Hemisphere 14C record only are biased towards low values during the Holocene. Notable deviations on decadal-to-centennial time scales are also found in comparison with earlier reconstructions. In a last step, past total solar irradiance (TSI) is

  1. Can UK fossil fuel emissions be determined by radiocarbon measurements?

    NASA Astrophysics Data System (ADS)

    Wenger, Angelina; O'Doherty, Simon; Rigby, Matthew; Manning, Alistair; Palmer, Paul

    2016-04-01

    The GAUGE project evaluates different methods to estimate UK emissions. However, estimating carbon dioxide emissions as a result of fossil fuel burning is challenging as natural fluxes in and out of the atmosphere are very large. Radiocarbon (14C) measurements offer a way to specifically measure the amount of recently added carbon dioxide from fossil fuel burning. This is possible as, due to their age, all the radiocarbon in fossil fuels has decayed. Hence the amount of recently added CO2 from fossil fuel burning can be measured as a depletion of the 14C content in air. While this method has been successfully applied by several groups on a city or a regional scale, this is the first attempt at using the technique for a national emission estimate. Geographically the UK, being an island, is a good location for such an experiment. But are 14CO2 measurements the ideal solution for estimating fossil fuel emissions as they are heralded to be? Previous studies have shown that 14CO2emissions from the nuclear industry mask the 14C depletion caused by fossil fuel burning and result in an underestimation of the fossil fuel CO2. While this might not be a problem in certain regions around the world, many countries like the UK have a substantial nuclear industry. A correction for this enhancement from the nuclear industry can be applied but are invariably difficult as 14CO2emissions from nuclear power plants have a high temporal variability. We will explain how our sampling strategy was chosen to minimize the influence form the nuclear industry and why this proved to be challenging. In addition we present the results from our ground based measurements to show why trying to estimate national emissions using radiocarbon measurements was overambitious, and how practical the technique is for the UK in general.

  2. PRIME Lab Radiocarbon Measurements

    NASA Astrophysics Data System (ADS)

    Hillegonds, D. J.; Mueller, K. A.; Ma, X.; Lipschutz, M. E.

    1996-03-01

    The Purdue Rare Isotope Measurement Laboratory (PRIME Lab) is one of three NSF national facilities for accelerator mass spectrometry (AMS), and is the only one capable of determining six cosmogenic radionuclides: 10Be, 14C, 26Al, 36Cl, 41Ca, and 129I. This abstract describes the current status of the radiocarbon analysis program at PRIME Lab.

  3. Accelerator Mass Spectrometric determination of radiocarbon in stratospheric CO2, retrieved from AirCore sampling.

    NASA Astrophysics Data System (ADS)

    Paul, Dipayan; Been, Henk A.; Chen, Huilin; Kivi, Rigel; Meijer, Harro A. J.

    2015-04-01

    In this decade, understanding the impact of human activities on climate is one of the key issues of discussion globally. The continuous rise in the concentration of greenhouse gases, e.g., CO2, CH4, etc. in the atmosphere, predominantly due to human activities, is alarming and requires continuous monitoring to understand the dynamics. Radiocarbon is an important atmospheric tracer and one of the many used in the understanding of the global carbon budget, which includes the greenhouse gases like CO2 and CH4. Measurement of 14C (or radiocarbon) in atmospheric CO2 generally requires collection of large air samples (few liters) from which CO2 is extracted and then the concentration of radiocarbon is determined. Currently, Accelerator Mass Spectrometry (AMS) is the most precise, reliable and widely used technique for atmospheric radiocarbon detection. However, the regular collection of air samples from troposphere and stratosphere, for example using aircraft, is prohibitively expensive. AirCore is an innovative atmospheric sampling system, developed by NOAA. It comprises of a long tube descending from a high altitude with one end open and the other closed, and has been demonstrated to be a reliable, cost-effective sampling system for high-altitude profile (up to ~ 30 km) measurements of CH4and CO2(Karion et al. 2010). In Europe, AirCore measurements are being performed on a regular basis near Sodankylä since September 2013. Here we describe the analysis of two such AirCore samples collected in July 2014, Finland, for determining the 14C concentration in stratospheric CO2. The two AirCore samples were collected on consecutive days. Each stratospheric AirCore sample was divided into six fractions, each containing ~ 35 μg CO2 (~9.5 μg C). Each fraction was separately trapped in 1 /4 inch coiled stainless steel tubing for radiocarbon measurements. The procedure for CO2 extraction from the stratospheric air samples; the sample preparation, with samples containing < 10

  4. 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. PMID:22717552

  5. Radiocarbon content of pre-bomb marine mollusks and variations in the 14C Reservoir age for coastal areas of the Barents and Kara Seas, Russia

    NASA Astrophysics Data System (ADS)

    Forman, Steven L.; Polyak, Leonid

    Fourteen mollusks, collected alive between 1900 and 1945 from the Russian Barents and Kara seas, were analyzed by AMS 14C dating to evaluate variations in the 14C marine reservoir for arctic coastal sites, which is important for correcting ages in paleoenvironmental time-series and advancing understanding of the exchange of carbon. The 14C ages on the mollusks reveal a range of marine reservoir values (R(t)) from 159 14C yr to 764 14C yr. The oldest R(t) values of 764 to 620 14C yr are for the bivalve Portlandia arctica, which often inhabit cold and low salinity waters and muddy substrates. The depleted 14C content for this bivalve reflects possibly the incorporation of old carbon from freshwater inputs and/or the consumption of old organic matter from the underlying sediments and pore waters. Other mollusks with sessile habitats and pelagic food sources gave significantly lower R(t) values between 159 and 344 14C yr. The youngest R(t) values indicate enrichment in 14C and may partially reflect enhanced transfer of 14C-enriched CO2 from the atmosphere to the ocean surface with wind-generated wave agitation. This study underscores that a variety of processes can lead to variable 14C depletion and enrichment of surface waters yielding a ca. 600 year age span for contemporaneous arctic mollusks. There may be added uncertainty in the 14C reservoir correction for deposit-feeder species such as Portlandia sp. and perhaps for certain benthic foraminifera (e.g. Nonion labradoricum) because these taxa often incorporate old organic matter from the substrate. A reservoir correction of ≥700 years may be more appropriate for infaunal, deposit-eater species, particularly in glacier-dominated environments. Mollusks and foraminifera with sessile habits and pelagic food sources should be selected preferentially for 14C dating, because their shells may more closely reflect the 14C content of the global-ocean mixed layer.

  6. 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.

  7. 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

  8. Holocene age of the Yuha burial: Direct radiocarbon determinations by accelerator mass spectrometry

    USGS Publications Warehouse

    Stafford, Thomas W., Jr.; Jull, A.J.T.; Zabel, T.H.; Donahue, D.J.; Duhamel, R.C.; Brendel, K.; Haynes, C.V., Jr.; Bischoff, J.L.; Payen, L.A.; Taylor, R.E.

    1984-01-01

    The view that human populations may not have arrived in the Western Hemisphere before about 12,000 radiocarbon yr BP1,2 has been challenged by claims of much greater antiquity for a small number of archaeological sites and human skeleton samples. One such site is the Homo sapiens sapiens cairn burial excavated in 1971 from the Yuha desert, Imperial County, California3-5. Radiocarbon analysis of caliche coating one of the bones of the skeleton yielded a radiocarbon age of 21,500??1,000 yr BP4, while radiocarbon and uranium series analyses of caliche coating a cairn boulder yielded ages of 22,125??400 and 19,000??3,000 yr BP, respectively5. The late Pleistocene age assignment to the Yuha burial has been challenged by comparing the cultural context of the burial with other cairn burials in the same region6, on the basis of the site's geomorphological context and from radiocarbon analyses of soil caliches. 7,8 In rebuttal, arguments in defence of the original age assignment have been presented9,10 as well as an amino acid racemization analysis on the Yuha skeleton indicating an age of 23,600??2,600 yr BP11. The tandem accelerator mass spectrometer at the University of Arizona has now been used to measure the ratio of 14C/13C in several organic and inorganic fractions of post-cranial bone from the Yuha H. sapiens sapiens skeleton. Isotope ratios from six chemical fractions all yielded radiocarbon ages for the skeleton of less than 4,000 yr BP. These results indicate that the Yuha skeleton is of Holocene age, in agreement with the cultural context of the burial, and in disagreement with the previously assigned Pleistocene age of 19,000-23,000 yr. ?? 1984 Nature Publishing Group.

  9. Radiocarbon dating of terrestrial carbonates

    USGS Publications Warehouse

    Pigati, Jeffrey S.

    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.

  10. Accurate lacustrine and wetland sediment accumulation rates determined from 14c activity of bulk sediment fractions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In the absence of identifiable macrofossils in lacustrine sediments, 14C dating must rely on pollen or bulk sediment fractions. Bulk sediment fractions are not generally preferred because they contain an unknown mixture of organic material of variable age, they may contain dead carbon such as ligni...

  11. 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.

  12. 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.

  13. Complexities in the Use of Bomb-Curve Radiocarbon to Determine Time Since Death of Human Skeletal Remains

    SciTech Connect

    Ubelaker, D H; Buchholz, B A

    2005-04-26

    Atmospheric testing of nuclear weapons during the 1950s and early 1960s doubled the level of radiocarbon ({sup 14}C) in the atmosphere. From the peak in 1963, the level of {sup 14}CO{sub 2} has decreased exponentially with a mean life of about 16 years, not due to radioactive decay, but due to mixing with large marine and terrestrial carbon reservoirs. Since radiocarbon is incorporated into all living things, the bomb-pulse is an isotopic chronometer of the past half century. The absence of bomb radiocarbon in skeletonized human remains generally indicates a date of death before 1950. Comparison of the radiocarbon values with the post 1950 bomb-curve may also help elucidate when in the post 1950 era, the individual was still alive. Such interpretation however, must consider the age at death of the individual and the type of tissue sampled.

  14. Determination of transfer rate and nature of the residue(s) in milk from {sup 14}C-atrazine cows

    SciTech Connect

    Thalacker, F.W.; Ash, S.G.; Simoneaux, B.J.

    1996-10-01

    In order to determine the rate of transfer and the nature of the atrazine residues present in milk, lactating dairy cattle were treated with atrazine at three concentrations, 0.764 ppm, 0.0747 ppm and 0.0085 ppm (dry weight of food consumed). The concentrations were selected to bridge the gap between the concentration used for EPA metabolism studies (10 ppm) and the potential exposure level of dairy cattle to atrazine and its chlorotriazine metabolites through feed. The cattle were dosed following the morning milking for nine consecutive days with a single capsule bolus of {sup 14}C-atrazine. Milk was collected twice daily and aliquots of each milking and the individual cow`s daily pool of milk were analyzed by liquid scinitllation counting (LSC). The concentrations of {sup 14}C-residues in the milk plateaued on approximately day 3 and the mean {sup 14}C-atrazine levels in milk were 11.2 ppb, 1.13 ppb and 0.152 ppb for the high, middle and low dosed animals, respectively. The transfer of radioactive level of exposure to {sup 14}C-atrazine. The nature of the residues in milk were determined by extracting milk samples and analysis by HPLC, TLC or Aminex chromatography. Diaminchlorotriazine was the only chlorinated metabolite in the milk, constituting approximately 65% to 75% of the total radioactive residues (TRR).

  15. Determination of radiocarbon in stratospheric CO2, obtained through AirCore sampling.

    NASA Astrophysics Data System (ADS)

    Paul, Dipayan; Chen, Huilin; Been, Henk A.; Kivi, Rigel; Meijer, Harro A. J.

    2016-04-01

    The concentration of Greenhouse Gases (GHG), with carbon dioxide as the most prominent example, has been and still is increasing, predominantly due to emissions from fossil fuel combustion. CO2 is also the most important component of the global carbon cycle. Among other tracers, radiocarbon (Carbon-14) is a unique and an important atmospheric tracer used in the understanding of the global carbon cycle. Radiocarbon is a naturally occurring isotope (radioactive, t 1/2 = 5730 ± 40 years) of carbon produced through the interaction of thermalized neutrons and nitrogen in the upper atmosphere. Generally, for performing atmospheric radiocarbon measurements in the higher atmosphere, large samples (few liters of air) were collected using aircrafts and balloons. However, collecting stratospheric samples on a regular basis for radiocarbon analysis is extremely expensive. Here we describe the determination of radiocarbon concentrations in stratospheric CO2, collected using AirCore sampling. AirCore is an innovative sampling technique for obtaining vertical atmospheric profiles and, in Europe, is done on a regular basis at Sodankylä, Finland for CO2, CH4 and CO. The stratospheric parts of two such AirCore profiles were used in this study as a proof-of-principle. CO2 from the stratospheric air samples were extracted and converted to elemental carbon, which were then measured at the Accelerator Mass Spectrometric (AMS) facility of the Centre for Isotope Research (CIO) at the University of Groningen. The stratospheric part of the AirCore profile was divided into six sections, each contained approximately 10 μg C. A detailed description of the extraction, graphitization, AMS analysis and the derivation of the stratospheric radiocarbon profile will be the main focus. Through our results, we will show that AirCore is a viable sampling method for performing high-precision radiocarbon measurements of stratospheric CO2 with reasonably good spatial resolution on a regular basis

  16. 14C Analysis via Intracavity Optogalvanic Spectroscopy

    PubMed Central

    Murnick, Daniel; Dogru, Ozgur; Ilkmen, Erhan

    2010-01-01

    A new ultra sensitive laser-based analytical technique, intracavity optogalvanic spectroscopy (ICOGS), allowing extremely high sensitivity for detection of 14C-labeled carbon dioxide has recently been demonstrated. Capable of replacing accelerator mass spectrometers (AMS) for many applications, the technique quantifies zeptomoles of 14C in sub micromole CO2 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 14C/12C ratios have been obtained with theoretical limits much lower. Using a 15 W 14CO2 laser, a linear calibration with samples from 5 × 10−15 to >1.5 × 10−12 in 14C/12C ratios, as determined by AMS, was demonstrated. Calibration becomes non linear over larger concentration ranges due to interactions between CO2 and buffer gas, laser saturation effects and changes in equilibration time constants. The instrument is small (table top), low maintenance and can be coupled to GC or LC input. The method can also be applied to detection of other trace entities. Possible applications include microdosing studies in drug development, individualized sub therapeutic tests of drug metabolism, carbon dating and real time monitoring of atmospheric radiocarbon. PMID:20448803

  17. 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.

  18. Changes in the Radiocarbon Reservoir Age in Lake Xingyun, Southwestern China during the Holocene

    PubMed Central

    Zhou, Aifeng; He, Yuxin; Wu, Duo; Zhang, Xiaonan; Zhang, Can; Liu, Zhonghui; Yu, Junqing

    2015-01-01

    Chronology is a necessary component of paleoclimatology. Radiocarbon dating plays a central role in determining the ages of geological samples younger than ca. 50 ka BP. However, there are many limitations for its application, including radiocarbon reservoir effects, which may cause incorrect chronology in many lakes. Here we demonstrate temporal changes in the radiocarbon reservoir age of Lake Xingyun, Southwestern China, where radiocarbon ages based on bulk organic matter have been reported in previous studies. Our new radiocarbon ages, determined from terrestrial plant macrofossils suggest that the radiocarbon reservoir age changed from 960 to 2200 years during the last 8500 cal a BP years. These changes to the reservoir effect were associated with inputs from either pre-aged organic carbon or 14C-depleted hard water in Lake Xingyun caused by hydrological change in the lake system. The radiocarbon reservoir age may in return be a good indicator for the carbon source in lake ecosystems and depositional environment. PMID:25815508

  19. Changes in the radiocarbon reservoir age in Lake Xingyun, Southwestern China during the Holocene.

    PubMed

    Zhou, Aifeng; He, Yuxin; Wu, Duo; Zhang, Xiaonan; Zhang, Can; Liu, Zhonghui; Yu, Junqing

    2015-01-01

    Chronology is a necessary component of paleoclimatology. Radiocarbon dating plays a central role in determining the ages of geological samples younger than ca. 50 ka BP. However, there are many limitations for its application, including radiocarbon reservoir effects, which may cause incorrect chronology in many lakes. Here we demonstrate temporal changes in the radiocarbon reservoir age of Lake Xingyun, Southwestern China, where radiocarbon ages based on bulk organic matter have been reported in previous studies. Our new radiocarbon ages, determined from terrestrial plant macrofossils suggest that the radiocarbon reservoir age changed from 960 to 2200 years during the last 8500 cal a BP years. These changes to the reservoir effect were associated with inputs from either pre-aged organic carbon or 14C-depleted hard water in Lake Xingyun caused by hydrological change in the lake system. The radiocarbon reservoir age may in return be a good indicator for the carbon source in lake ecosystems and depositional environment. PMID:25815508

  20. 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.

  1. 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.

  2. 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

  3. Radiocarbon determinations for estimating groundwater flow velocities in central Florida

    USGS Publications Warehouse

    Hanshaw, B.B.; Back, W.; Rubin, M.

    1965-01-01

    Carbon-14 activity was determined from HCO3- in samples of groundwater obtained from the principal artesian aquifer in Florida. From these data the "age" of water obtained from a series of wells, each progressively farther down gradient on the piezometric surface, was established. Relative carbon-14 ages indicated a velocity of groundwater movement of 23 feet (7 meters) per year for about 85 miles (137 kilometers) of travel. A velocity of 23 feet per year was calculated independently from Darcy's law.

  4. Radiocarbon AMS determination of the biogenic component in CO 2 emitted from waste incineration

    NASA Astrophysics Data System (ADS)

    Calcagnile, L.; Quarta, G.; D'Elia, M.; Ciceri, G.; Martinotti, V.

    2011-12-01

    The thermal utilization of waste for energy production is gaining importance in European countries. Nevertheless, the combustion of waste leads to significant CO 2 emissions in the atmosphere which, depending on the fraction of biogenic and fossil materials, have to be only partially accounted for the national greenhouse gas inventory. For this reason the development of proper methodologies for the measurement of the biogenic fraction in the combusted waste is an active research field. In fact the determination of the radiocarbon concentration in the carbon dioxide stack emissions allows to have a direct indication of the biogenic component in the burned fuel. We present the results of the AMS radiocarbon analyses carried out on carbon dioxide sampled at the stack of three power plants located in Northern Italy burning natural gas, landfill biogas and SRF (Solid Recovered Fuel) derived from MSW (Municipal Solid Waste). The sampling apparatus and the applied processing protocols are described together with the calculation procedures used to determine, from the measured radiocarbon concentrations, the proportion of biogenic and fossil component in the flue gas and in the combusted fuel. The results confirm the high potentialities of this approach in the analysis of industrial CO 2 emissions.

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

    PubMed Central

    Graven, Heather D.

    2015-01-01

    Radiocarbon analyses are commonly used in a broad range of fields, including earth science, archaeology, forgery detection, isotope forensics, and physiology. Many applications are sensitive to the radiocarbon (14C) content of atmospheric CO2, which has varied since 1890 as a result of nuclear weapons testing, fossil fuel emissions, and CO2 cycling between atmospheric, oceanic, and terrestrial carbon reservoirs. Over this century, the ratio 14C/C in atmospheric CO2 (Δ14CO2) will be determined by the amount of fossil fuel combustion, which decreases Δ14CO2 because fossil fuels have lost all 14C from radioactive decay. Simulations of Δ14CO2 using the emission scenarios from the Intergovernmental Panel on Climate Change Fifth Assessment Report, the Representative Concentration Pathways, indicate that ambitious emission reductions could sustain Δ14CO2 near the preindustrial level of 0‰ through 2100, whereas “business-as-usual” emissions will reduce Δ14CO2 to −250‰, equivalent to the depletion expected from over 2,000 y of radioactive decay. Given current emissions trends, fossil fuel emission-driven artificial “aging” of the atmosphere is likely to occur much faster and with a larger magnitude than previously expected. This finding has strong and as yet unrecognized implications for many applications of radiocarbon in various fields, and it implies that radiocarbon dating may no longer provide definitive ages for samples up to 2,000 y old. PMID:26195757

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

    PubMed

    Graven, Heather D

    2015-08-01

    Radiocarbon analyses are commonly used in a broad range of fields, including earth science, archaeology, forgery detection, isotope forensics, and physiology. Many applications are sensitive to the radiocarbon ((14)C) content of atmospheric CO2, which has varied since 1890 as a result of nuclear weapons testing, fossil fuel emissions, and CO2 cycling between atmospheric, oceanic, and terrestrial carbon reservoirs. Over this century, the ratio (14)C/C in atmospheric CO2 (Δ(14)CO2) will be determined by the amount of fossil fuel combustion, which decreases Δ(14)CO2 because fossil fuels have lost all (14)C from radioactive decay. Simulations of Δ(14)CO2 using the emission scenarios from the Intergovernmental Panel on Climate Change Fifth Assessment Report, the Representative Concentration Pathways, indicate that ambitious emission reductions could sustain Δ(14)CO2 near the preindustrial level of 0‰ through 2100, whereas "business-as-usual" emissions will reduce Δ(14)CO2 to -250‰, equivalent to the depletion expected from over 2,000 y of radioactive decay. Given current emissions trends, fossil fuel emission-driven artificial "aging" of the atmosphere is likely to occur much faster and with a larger magnitude than previously expected. This finding has strong and as yet unrecognized implications for many applications of radiocarbon in various fields, and it implies that radiocarbon dating may no longer provide definitive ages for samples up to 2,000 y old. PMID:26195757

  7. Determination of the Prebomb Southern (Antartic) Ocean Radiocarbon in Organic Matter

    SciTech Connect

    Guilderson, T P

    2001-02-26

    The Southern Hemisphere is an important and unique region of the world's oceans for water-mass formation and mixing, upwelling, nutrient utilization, and carbon export. In fact, one of the primary interests of the oceanographic community is to decipher the climatic record of these processes in the source or sink terms for Southern Ocean surface waters in the CO{sub 2} balance of the atmosphere. Current coupled ocean-atmosphere modeling efforts to trace the input of CO{sub 2} into the ocean imply a strong sink of anthropogenic CO{sub 2} in the southern ocean. However, because of its relative inaccessibility and the difficulty in directly measuring CO{sub 2} fluxes in the Southern Ocean, these results are controversial at best. An accepted diagnostic of the exchange of CO{sub 2} between the atmosphere and ocean is the prebomb distribution of radiocarbon in the ocean and its time-history since atmospheric nuclear testing. Such histories of {sup 14}C in the surface waters of the Southern Ocean do not currently exist, primarily because there are few continuous biological archives (e.g., in corals) such as those that have been used to monitor the {sup 14}C history of the tropics and subtropics. One of the possible long-term archives is the scallop Adamussium collbecki. Although not independently confirmed, relatively crude growth rate estimates of A. collbecki indicate that it has the potential to provide continuous 100 year time-series. We are exploring the suitability of this potential archive.

  8. Decoloration and solubilization of plant tissue prior to determination of /sup 3/H, /sup 14/C, and /sup 35/S by liquid scintillation

    SciTech Connect

    Smith, I.K.; Lang, A.L.

    1987-08-01

    A method is described for the decoloration and partial solubilization of plant tissue with 2% sodium hypochlorite. Following treatment of the digest with ammonia, the samples are suitable for the determination of /sup 3/H, /sup 14/C, and /sup 35/S by liquid scintillation counting. The color quenching is negligible and counting efficiencies are high: 30-40% for /sup 3/H and 90-95% for /sup 14/C.

  9. 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)

  10. Age determination of mid-ocean ridge basalts by radiocarbon dating of lithified carbonate crusts

    SciTech Connect

    Kuptsov, V.M.; Bogdanov, Yu.A.; Palkina, A.M.; Lisitsyn, A.P.

    1986-01-01

    The processes that take place in the mid-ocean ridges are the key to their understanding of the evolution of the earth's crust and mantle. Mid-ocean ridge volcanism supplies vast masses of mantle material, forming new oceanic crust. In recent years, comprehensive study has been made of such processes. The problems of geochronology have an important place in these investigations, since only a study of the events in their time sequence will enable them to make a valid estimate of the intensity of these global processes. In 1980, crusts were obtained by the Pikar combined expedition in the Red Sea rift in the 18/sup 0/ study area on the lower tectonic terrace, in the axial zone, and in three deep water basins. Manned deep water submersible, dredges, trawls, bottom samplers, and impact tubes brought up basalts covered with lithified crusts, and also separate lithified crusts, collected from the basalt basement during sampling. The authors have dated the crusts by the radiocarbon method using the benzene technique. Results of the analysis give ages ranging from 2980 to 20,700 years. Results are discussed. The use of lithified carbonate crusts for determining the age of the basalts is effective within the range of the radiocarbon dating method (up to 40,000-45,000 years). This time interval is inaccessible for determinations by other methods of nuclear geochronology, which makes the method especially valuable. 1 reference, 2 figures, 1 table.

  11. Respiratory strategy is a major determinant of [3H]water and [14C]chlorpyrifos uptake in aquatic insects

    USGS Publications Warehouse

    Buchwalter, D.B.; Jenkins, J.J.; Curtis, L.R.

    2002-01-01

    Despite the extensive use of aquatic insects to evaluate freshwater ecosystem health, little is known about the underlying factors that result in sensitivity differences between taxa. Organismal characteristics (respiratory strategy and body size) were used to explore the rates of [3H]H2O and [14)C]chlorpyrifos accumulation in aquatic insects. Ten aquatic insect taxa, including ephemeropteran, trichopteran, dipteran, hemipteran, and coleopteran species, were exposed to [14C]chlorpyrifos (240 ng??L-1) and [3H]H2O for up to 12 h. Because exchange epithelial surfaces on the)integument are permeable to water, [3H]H2O was used as a quantitative surrogate for exposed cellular surface area.) [14C]Chlorpyrifos uptake rates were highly correlated with water permeability in all 10 taxa tested and largely covaried with body size and respiratory strategy. Rates were highest among smaller organisms on a per-weight basis and in taxa with relatively large external cellular surfaces such as gills. Air-breathing taxa were significantly less permeable to both [3)HH20 and [14C)C]chlorpyrifos. A method for labeling exposed epithelial surfaces with a fluorescent dye was developed. This technique allowed discrimination between exchange epithelium and barrier tissue on the integument. Fluorescent dye distributions on the body surface provided a rapid method for estimating exposed epithelium consistent with [3H]H2O and [14)C]chlorpyrifos accumulation.

  12. Age assessment of ivory by analysis of 14C and 90Sr to determine whether there is an antique on hand.

    PubMed

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

    2011-04-15

    A method is described to determine whether an elephant has died before 1955 or not. This is accomplished by determination of the radionuclides (14)C and (90)Sr in artifacts made of ivory. The reliability of this method is considerably increased by double nuclide analysis and therefore is applicable for judicial expert opinions. PMID:21371831

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    A partial skeleton of the extinct ground sloth, Megalonyx jeffersonii, recovered from a farm near Millersburg, Ohio in 1890, was radiocarbon dated for the first time. The ungual dated is part of a skeleton mounted for exhibit at the Orton Geological Museum at Ohio State University and was the first mounted skeleton of this animal. From its initial discovery the bones were treated with multiple organic compounds that had the potential to compromise the radiocarbon age and the specimen required special treatments in order to obtain a valid radiocarbon age. The 14C measurement on the ungual from this skeleton (11,235 ± 40 14C yr BP = 13,180-13,034 cal yr BP) is the youngest 14C age presently determined for M. jeffersonii.

  14. Comparison of the gravimetric, phenol red, and 14C-PEG-3350 methods to determine water absorption in the rat single-pass intestinal perfusion model.

    PubMed

    Sutton, S C; Rinaldi, M T; Vukovinsky, K E

    2001-01-01

    This study was undertaken to determine whether the gravimetric method provided an accurate measure of water flux correction and to compare the gravimetric method with methods that employ nonabsorbed markers (eg, phenol red and 14C-PEG-3350). Phenol red,14C-PEG-3350, and 4-[2-[[2-(6-amino-3-pyridinyl)-2-hydroxyethyl]amino]ethoxy]-, methyl ester, (R)-benzene acetic acid (Compound I) were co-perfused in situ through the jejunum of 9 anesthetized rats (single-pass intestinal perfusion [SPIP]). Water absorption was determined from the phenol red,14C-PEG-3350, and gravimetric methods. The absorption rate constant (ka) for Compound I was calculated. Both phenol red and 14C-PEG-3350 were appreciably absorbed, underestimating the extent of water flux in the SPIP model. The average +/- SD water flux microg/h/cm) for the 3 methods were 68.9 +/- 28.2 (gravimetric), 26.8 +/- 49.2 (phenol red), and 34.9 +/- 21.9 (14C-PEG-3350). The (average +/- SD) ka for Compound I (uncorrected for water flux) was 0.024 +/- 0.005 min(-1). For the corrected, gravimetric method, the average +/- SD was 0.031 +/- 0.001 min(-1). The gravimetric method for correcting water flux was as accurate as the 2 "nonabsorbed" marker methods. PMID:11741276

  15. Intracavity Optogalvanic Spectroscopy, A New Ultra-sensitive Analytical Technique for 14C Analysis

    PubMed Central

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

    2009-01-01

    We show a new ultra-sensitive laser based analytical technique, intracavity optogalvanic spectroscopy, allowing extremely high sensitivity for detection of 14C labeled carbon dioxide. Capable of replacing large accelerator mass spectrometers, the technique quantifies attomoles of 14C 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 14C:12C ratios are obtained. Using a 15W 14CO2 laser, a linear calibration with samples from 10-15 to >2 × 10-12 in 14C:12C ratios, as determined by accelerator mass spectrometry, is demonstrated. Possible applications include microdosing studies in drug development, individualized sub-therapeutic 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. PMID:18533685

  16. Radiocarbon in Tree STEM CO2 Efflux

    NASA Astrophysics Data System (ADS)

    Muhr, J.; Czimczik, C. I.; Angert, A.; Trumbore, S.

    2011-12-01

    Carbon dioxide efflux from tree stems can be a significant component of the stand-level carbon balance. Recent studies have demonstrated that tree stem CO2 efflux may reflect more than just in-situ respiration but also transport from other locations and it has been suggested that it may also include C originally respired in roots or even uptake of soil CO2. We report measurements of the radiocarbon signature of carbon emitted from a range of mature tree stems in tropical and temperate forest ecosystems. Comparison of the radiocarbon signature of respired CO2 with the observed rate of decline in atmsopheric 14C-CO2 provides a measure of the time elapsed between C fixation by the plant and its return to the atmosphere as stem CO2 efflux. In all investigated trees, we observed that stem CO2 efflux had higher radiocarbon signatures than the contemporary atmospheric 14C-CO2, and therefore was derived from C fixed one to several years earlier. In tropical forest trees, we found that the 14C signature of CO2 within the stem (~4-5 cm depth) had even higher radiocarbon signatures than the stem CO2 efflux. In one of the investigated tree species, the in-stem CO2 was derived from C sources fixed on average ~20 years previously. These results confirm observations of root-respired CO2 that also have shown contributions of C substrates older than recent photosynthetic products, and the presence of extracable C reserves in wood that reflect the presence of older C sources. Our results imply that stem CO2 efflux is not only derived from respiration of recent photosynthetic products but includes contributions from older, stored C pools. Ongoing investigations will enable us to compare CO2 efflux for trees subjected to experimental drought, and using different life strategies (deciduous versus evergreen oaks) to determine if the use of these older C stores varies with stress.

  17. Insulin and contraction increase nutritive blood flow in rat muscle in vivo determined by microdialysis of l-[14C]glucose

    PubMed Central

    Newman, John M B; Ross, Renee M; Richards, Stephen M; Clark, Michael G; Rattigan, Stephen

    2007-01-01

    In the present study, a mathematical model using the microdialysis outflow: inflow (O/I) ratio of the novel analogue l-[14C]glucose has been developed which allows the calculation of the nutritive (and non-nutritive) flow in muscle as a proportion of total blood flow. Anaesthetized rats had microdialysis probes carrying l-[14C]glucose inserted through a calf muscle group (tibialis/plantaris/gastrocnemius). The nutritive fraction of total blood flow was determined under basal conditions and in response to contraction (electrical field stimulation), insulin (hyperinsulinaemic euglycaemic clamp with 10 mU min−1 kg−1 insulin) or saline control from limb blood flow and the microdialysis O/I ratio of l-[14C]glucose. Both contraction and insulin infusion decreased the O/I ratio of l-[14C]glucose and increased total limb blood flow. Calculations based on mathematical models using l-[14C]glucose O/I and limb blood flow revealed that during basal conditions, the nutritive fraction of total flow was 0.38 ± 0.06, indicating that basal flow was predominantly non-nutritive. Contraction and insulin increased the nutritive fraction to 0.82 ± 0.24 (P < 0.05) and 0.52 ± 0.12 (P < 0.05). Thus the increase in limb blood flow from insulin was fully accommodated by nutritive flow, while contraction increased nutritive flow at the expense of non-nutritive flow. This novel method using microdialysis and the O/I ratio of l-[14C]glucose allows the determination of the nutritive fraction of total flow in muscle as well as the proportion of total flow that may be redistributed in response to contraction and insulin. PMID:17884927

  18. High-temporal resolution radiocarbon analyses of dissolved organic matter in soils from a mountainous and temperate ecosystem

    NASA Astrophysics Data System (ADS)

    van der Voort, Tessa Sophia; Graf Pannatier, Elisabeth; McIntyre, Cameron; Hagedorn, Frank; Eglinton, Timothy

    2016-04-01

    A better understanding of the stability and turnover of soil dissolved organic matter (DOM) is key in order to predict the behavior and response of this dynamic carbon pool to climate and land use change. Radiocarbon is increasingly used to determine carbon turnover in carbon cycle studies. However, due to the nature of radiocarbon measurement as well as complexity of in-situ DOM collection, little comprehensive radiocarbon and turnover data is currently available. This project combines a high-resolution temporal DOM sequence for a mountainous (podzol) and temperate (cambisol) forest ecosystem with additional bulk- and fraction-specific soil organic matter analyses. DOM was collected bi-weekly on two sites of the Long-Term Forest Ecosystem Research (LWF) program of the Swiss Federal Institute for Forest, Snow and Landscape research (WSL) at four depths, and measured for radiocarbon content. These initial results indicate bi-weekly variation in radiocarbon signatures over the summer season and a strong soil-type dependent pattern in DO14C trend. Overall, these initial radiocarbon results indicate that DOM dynamics are seasonally variable, and thus could potentially be sensitive to future climate change. Furthermore, the DO14C trend helps to better understand the trends as can be seen in the bulk 14C signature of the soil organic matter. Detailed radiocarbon investigations of soil DOM may yield key insights into the complex carbon transport dynamics in different soil systems and their potential behavior under climate change scenarios.

  19. Radiocarbon dating in groundwater systems: Chapter 4

    USGS Publications Warehouse

    Plummer, L.N.; Glynn, P.D.

    2013-01-01

    The radioactive isotope of carbon, radiocarbon (14C), was first produced artificially in 1940 by Martin Kamen and Sam Ruben, who bombarded graphite in a cyclotron at the Radiation Laboratory at Berkeley, CA, in an attempt to produce a radioactive isotope of carbon that could be used as a tracer in biological systems (Kamen (1963) [101]; Ruben and Kamen (1941) [102]). Carbon-14 of cosmogenic origin was discovered in atmospheric CO2 in 1946 by Willard F. Libby, who determined a half-life of 5568 a. Libby and his co-workers (Anderson et al. (1947) [103]; Libby et al. (1949) [104]) developed radiocarbon dating of organic carbon of biological origin, which revolutionized research in a number of fields, including archaeology and quaternary geology/climatology, by establishing ages and chronologies of events that have occurred over the past approximately 45 ka.

  20. The value of radiocarbon analysis in determining the forensic interest of human skeletal remains found in unusual circumstances.

    PubMed

    Cardoso, Hugo F V; Puentes, Katerina; Soares, António Monge; Santos, Agostinho; Magalhães, Teresa

    2012-02-01

    The case under analysis refers to the remains of a young adult female found in a shallow grave during the construction work of a hospital in Northern Portugal. The forensic interest of the finding could not be ruled out since distinguishing features pointing to an archaeological grave were lacking. For example, absence of archaeological artefacts could not establish its forensic significance with certainty, together with the absence of modern objects, such as remnants of clothing or personal objects. In addition, although the remains were badly preserved, the condition may not have resulted from a long post-depositional period, but instead could be explained by the geology of the site and the presence of plant roots. The radiocarbon analysis of the remains was meant to establish the death of the individual to before or after the mid-1950s, from comparison with bomb-curve content values. A value of 0.9789 ± 0.0044 for F(14)C (pmC = 97.19 ± 0.44% Modern or Δ(14)C = -28.1 ± 4.4‰) was obtained, which placed the death of the individual in the pre-mod-1950s period. This report illustrates the use of radiocarbon analysis in establishing whether the human remains are contemporary or not and describes evidence for what appears to be an historic clandestine grave. PMID:22281219

  1. Application of compound-specific radiocarbon dating for Antarctic margin sediments

    NASA Astrophysics Data System (ADS)

    Ohkouchi, N.; Koizumi, M.; Anderson, J. B.; Eglinton, T. I.; Miura, H.; Yokoyama, Y.

    2008-12-01

    Radiocarbon dating has been extensively applied for the development of chronologies of Antarctic margin sediments deposited during the late Quaternary. However, the problems are 1) the DIC reservoir age in the surface mixed layer is much older than that of the other oceans, 2) Antarctic margin sediments generally lack calcareous foraminifera conventionally used for radiocarbon dating and as stratigraphic tool, and 3) the sediments are subjected to significant "contamination" of relict organic matter eroded from the Antarctic continent, leading to substantially older radiocarbon ages of bulk sedimentary organic matter. Ohkouchi et al. (2003) first applied compound-specific radiocarbon dating to the surface sediments collected from Ross Sea, Antarctica for resolving the problem. They reported that the radiocarbon ages of solvent-extractable, short-chain (C14, C16, and C18) fatty acids are consistent with the modern DIC reservoir age (Pre-bomb: 14C -150, Post-bomb: 14C -100). Furthermore, the radiocarbon ages of these fatty acids at five down-core intervals progressively increase with the core depth. These results clearly show a utility of the compound- specific radiocarbon dating for developing sediment chronologies in Antarctic margin sediments. We also determined radiocarbon ages of the fatty acids from a core recovered in the NW Ross Sea to reconstruct sediment chronologies. Furthermore, we determined hydrogen isotopic compositions of sedimentary biomarkers in the core. Around 6.8, 5.7, 4.1, 2.5, and 1.5 kyr ago, the reconstructed D values of paleo- seawater were -200 or lower, suggesting a large amount of meltwater influx to the Ross Sea. Currently, we are applying the method to more sediment samples collected from wider area of Ross Sea to investigate the timing and pattern of retreat of West Antarctic Ice Sheet in the Holocene. I will present the up-dated results in my talk.

  2. The synthesis of [(14) C]AZD5122. Incorporation of an IV (14) C-microtracer dose into a first in human study to determine the absolute oral bioavailability of AZD5122.

    PubMed

    Hickey, Michael J; Allen, Paul H; Kingston, Lee P; Wilkinson, David J

    2016-05-30

    AZD5122, N-(2-(2,3-difluorobenzylthio)-6-((2R,3R)-3,4-dihydroxybutan-2-ylamino)pyrimidin-4-yl)azetidine-1-sulfonamide was under investigation as a potential chemokine receptor CXCR2 antagonist for the treatment for inflammatory diseases. To gain a better understanding of the human pharmacokinetic profile, an exploratory phase I IV microtracer study was conducted using carbon-14 radiolabelled AZD5122. [(14) C]AZD5122 was carbon-14 labelled in the pyrimidine ring in five steps in an overall radiochemical yield of 19% from [(14) C]thiourea. The absolute oral bioavailability of AZD5122 was assessed in healthy subjects by an oral administration of AZD5122, followed by a concomitant intravenous [(14) C]AZD5122 microdose. PMID:27169760

  3. Deglacial 14C plateau suites recalibrated by Suigetsu atmospheric 14C record - Revised 14C reservoir ages from three ocean basins corroborate extreme surface water variations

    NASA Astrophysics Data System (ADS)

    Sarnthein, M.; Balmer, S.; Grootes, P. M.

    2013-12-01

    Radiocarbon (14C) reservoir/ventilation ages (Δ14C) provide unique insights into the dynamics of ocean water masses over LGM and deglacial times. The 14C plateau-tuning technique enables us to derive both an absolute chronology for marine sediment records and a high-resolution record of changing Δ14C values for deglacial surface and deep waters (Sarnthein et al., 2007; AGU Monogr. 173, 175). We designate as 14C plateau a sediment section in the age-depth profile with several almost constant planktic 14C ages - variation less than ×100 to ×300 yr - which form a plateau-shaped scatter band that extends over ~5 to 50 and up to 200 cm in sediment cores with sedimentation rates of >10 cm/ky. Previously, a suite of >15 plateau boundary ages were calibrated to a joint reference record of U/Th-dated 14C time series measured on coral samples, the Cariaco sediment record, and speleothems (Fairbanks et al., 2005, QSR 24; Hughen et al., 2006, QSR 25; Beck et al., 2001, Science 292). We now used the varve-counted atmospheric 14C record of Lake Suigetsu (Ramsey et al., 2012, Science 338, 370) to recalibrate the boundary ages and average ages of 14C plateaus and apply the amended plateau-tuning technique to a dozen Δ14C records from the Atlantic and Indo-Pacific. Main results are: (1) The Suigetsu atmospheric 14C record reflects all 14C plateaus, their internal structures and relative length previously identified, but implies a rise in the average plateau age by <200 14C yr during the LGM, >700 yr at its end, and <200 yr in the Bølling-Allerød. (2) Based on different 14C ages of coeval atmospheric and planktic 14C plateaus surface water Δ14C may have temporarily dropped to an equivalent of 200 yr in low-latitude stratified waters, such as off northwestern South America, and in turn reached values corresponding to an age difference of >2500 14C yr in stratified subpolar regions and upwelled waters such as in the South China Sea, values that differ significantly from a

  4. Radiocarbon age of waters in the deep Atlantic revisited

    SciTech Connect

    Broecker, W.S.; Virgilio, A. ); Peng, T.H. )

    1991-01-01

    The authors use a simple box model to evaluate the impact of temporal changes of the atmosphere's {sup 14}C/C on ventilation fluxes for the deep Atlantic calculated from radiocarbon measurements. The conclusion is that despite the fact that over the 300 year period from 1650 to 1950 the atmosphere's radiocarbon content declined at the same rate as radiocarbon decays, this temporal change has a relatively small impact (10-15%) on radiocarbon-based estimates of the ventilation rate of the deep Atlantic. The reason is that the radiocarbon content of the source waters for deep Atlantic are reasonably well buffered against changes in atmospheric {sup 14}C/C.

  5. 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

  6. Preventing and Removing Contamination in a Natural Radiocarbon Sample Preparation Laboratory

    SciTech Connect

    Zermeno, P; Kurdyla, D K; Buchholz, B A; Heller, S J; Frantz, B R; Brown, T A; Kashgarian, M

    2002-10-25

    The introduction of elevated {sup 14}C contamination into a natural radiocarbon sample preparation laboratory can occur through many different pathways. The most difficult to control is the introduction of contaminated samples from outside labs. Laboratories can remain {sup 14}C contaminated as a result of earlier tracer based research, even if ''hot'' work has not occurred in the laboratories in decades. Prior to accepting samples from outside collaborators, it is recommended that the collaborators test their labs for {sup 14}C contamination. Any surface in a lab that has high use by multiple people has the potential to be contaminated. The standard procedure for determining whether a collaborator's lab is contaminated consists of swiping lab surfaces with small glass fiber filters wetted with alcohol and measuring them for {sup 14}C content using AMS. Volatile {sup 14}C can be detected by using aerosol monitors consisting of fine soot that is depleted in {sup 14}C. These monitors can be set out in the laboratory in question to check for volatile {sup 14}C contamination. In the event that a hot sample is introduced in the natural radiocarbon sample prep laboratory, all sample submission should be stopped until the lab is declared clean. Samples already being processed should be completed along with {sup 14}C depleted material and measured by AMS. This will help determine if the contaminated samples have affected other samples in the laboratory. After a contamination event, the laboratory and associated equipment requires cleaning or disposal. All surfaces and equipment should be wiped down with acetone or ethanol. All chemicals in use should be disposed of in the appropriate waste containers and those waste containers removed from the lab. Once the natural radiocarbon laboratory has been thoroughly ''cleaned'', several background samples consisting of {sup 14}C depleted material should be processed through the lab and measured by AMS before unknown samples are

  7. 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

  8. Projections of atmospheric radiocarbon content to 2100

    NASA Astrophysics Data System (ADS)

    Graven, Heather

    2014-05-01

    The radiocarbon content of atmospheric CO2 has undergone dramatic changes over the past century. Radiocarbon in CO2 has been diluted by the combustion of 14C-free fossil fuels since the industrial revolution, causing a slow decline in the relative abundance of 14C to total carbon (Δ14C) in the early 1900s. This decline was interrupted by nuclear weapons testing in the 1950s and 60s, which nearly doubled the atmospheric inventory of 14C. Following the extraordinary rise in radiocarbon content, a quasi-exponential decrease was observed as excess radiocarbon was assimilated by carbon reservoirs in the ocean and on land. Recently, fossil fuel emissions have once again become the dominant influence on the long-term trend in Δ14C of CO2. This presentation will investigate the trajectory of atmospheric Δ14C to 2100 in relation to the Representative Concentration Pathways (RCPs) using a simple carbon cycle model. In all scenarios, Δ14C of CO2 is projected to drop below the zero per mil level in the next decade. Simulated atmospheric Δ14C is lower than -200 per mil in 2100 in the scenario with the largest growth in fossil fuel emissions, while the most ambitious emission reductions are projected to sustain Δ14C near zero per mil. The presentation will discuss the implications of these changes in atmospheric composition on isotopic disequilibria and net fluxes of radiocarbon between different reservoirs, including the sensitivity of atmospheric Δ14C to fossil fuel emissions on global and regional scales.

  9. Recent AMS measurements of {sup 14}C in soil organic matter: Understanding controls of carbon storage and turnover in soils

    SciTech Connect

    Trumbore, S.E.; Torn, M.S.; Chadwick, O.A.

    1996-10-01

    Radiocarbon measurements are one of the best tools available for determining the rates of carbon and turnover of in soil organic matter. AMS measurements of radiocarbon are essential they allow measurement of {sup 14}C in archived soils with very low carbon content, in physically or chemically fractionated soil organic matter, in dissolved organic carbon leached from soils, as well as in CO{sub 2} and CH{sub 4} produced during decomposition. We report recent results demonstrating the importance of applying AMS soil radiocarbon measurements to questions of soil C dynamics. We used the increase in {open_quote}bomb{close_quote} {sup 14}C between archived an modem soil profiles sampled along an elevation transect in the Sierra Nevada mountains, California, to determine the role of temperature in determining the rate of turnover of fast-cycling soil organic matter. To study the role of soil mineralogy in determining how carbon is stabilized in {open_quote}passive{close_quote} soil organic matter pools, we compare soil mineralogy and C and {sup 14}C storage in soils along a chronosequence in the Hawaiian islands. Implications for the global C cycle will be discussed.

  10. Utility of radiocarbon-dated stratigraphy in determining late Holocene earthquake recurrence intervals, upper Cook Inlet region, Alaska

    USGS Publications Warehouse

    Bartsch-Winkler, S.; Schmoll, H.R.

    1992-01-01

    During the great 1964 earthquake, parts of coastal southern Alaska subsided tectonically as much as 2 m, and this led to burial of high-intertidal organic-rich marshes by low-intertidal and tidal silt. In the tectonically active parts of upper Cook Inlet, the presence of stratigraphic sections containing numerous prehistoric interbedded layers of peat and silt suggests that such stratigraphy resulted when marshes and forests were similarly inundated and buried by intertidal and tidal sediment as a result of great, prehistoric earthquakes. This study tests the feasibility of using buried, radiocarbon-dated, late Holocene peat layers that are exposed in the intertidal zone of upper Cook Inlet to determine earthquake recurrence intervals. Because of problems associated with conventional radiocarbon dating, the complex stratigraphy of the study area, the tectonic setting, and regional changes in sea level, conclusions from the study do not permit precise identification of the timing and recurrence of paleoseismic events. -from Authors

  11. 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

  12. Radiocarbon dating of fossil mollusk shells in the Yucca Mountain region

    SciTech Connect

    Brennan, R.; Quade, J.

    1995-12-01

    Fossil mollusk shells from late Quaternary deposits in Southern Nevada were radiocarbon dated to determine the age of paleogroundwater discharge events and to establish minimum {sup 14}C ages of paleogroundwater. Shells of the terrestrial taxa Vallonia sp. and Succineidae returned {sup 14}C dates consistent with those on organic material in the same stratigraphic position. The aquatic taxa Gyraulus parvus and Gyraulus circumstratus returned the oldest dates within each unit samples. These results show that (1) fossil Vallonia and Succineidae are useful in dating deposits in which no other radiocarbon-datable material is available, and (2) Gyraulus sp. select micro habitats with the most {sup 14}C deficient water, providing minimum ages of groundwater in the area during the last glacial period.

  13. 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

  14. Influence of matrix diffusion and exchange reactions on radiocarbon ages in fissured carbonate aquifers

    SciTech Connect

    Maloszewski, P. ); Zuber, A. )

    1991-08-01

    The parallel fissure model coupled with the equation of diffusion into the matrix and with exchange reaction equations has been used to derive a simple formula for estimating the influence of matrix porosity and reaction parameters on the determination of radiocarbon ages in fissured carbonate rocks. Examples of evidently too great radiocarbon ages in carbonate formations, which are not explainable by models for the initial {sup 14}C corrections, can easily be explained by this formula. Parameters obtained for a chalk formation from a known multitracer experiment combined with a pumping test suggest a possibility of {sup 14}C ages more than three orders of magnitude greater than the ages which would be observed if the radiocarbon transport took place only in the mobile water in the fissures. It is shown that contrary to the solute movement on a small scale and with a variable input, the large-scale movement, characteristic for the {sup 14}C dating, does not necessarily require the knowledge of kinetic parameters, because they may be replaced by the distribution coefficient. Discordant tritium and {sup 14}C concentrations are commonly interpreted as a proof of mixing either in the aquifer or at the discharge site. For fissured carbonate formations, however, an alternative explanation is given by the derived model showing a considerable delay of {sup 14}C with respect to nonsorbable tracers.

  15. Radiocarbon in otoliths of yelloweye rockfish (Sebastes ruberrimus): a reference time series for the coastal waters of southeast Alaska

    SciTech Connect

    Kerr-Ferrey, L A; Andrews, A H; Frantz, B R; Coale, K H; Brown, T A; Cailliet, G M

    2003-10-14

    Atmospheric testing of thermonuclear devices during the 1950s and 1960s created a global radiocarbon ({sup 14}C) signal in the environment that has provided a useful tracer and chronological marker in oceanic systems and organisms. The bomb-generated {sup 14}C signal retained in fish otoliths can be used as a permanent, time-specific recorder of the 14C present in ambient seawater, making it a useful tool in age validation of fishes. The goal of this study was to determine {sup 14}C levels in otoliths of the age-validated yelloweye rockfish (Sebastes ruberrimus) to establish a reference time series for the coastal waters of southeast Alaska. Radiocarbon values from the first year's growth of 43 yelloweye rockfish otoliths were plotted against estimated birth year to produce a 14C time series for these waters spanning 1940 to 1990. The time series shows the initial rise of bomb 14C occurred in 1958 in coastal southeast Alaskan waters and {sup 14}C levels rose relatively rapidly to peak {Delta}{sup 14}C values (60-70%) between 1966 and 1971, with a subsequent declining trend through the end of the record in 1990 (-3.2%). In addition, the radiocarbon data, independent of the radiometric study, confirms the longevity of the yelloweye rockfish up to a minimum of 44 years and strongly supports higher age estimates. The yelloweye rockfish record provides a {sup 14}C chronology that will be useful for the interpretation of {sup 14}C accreted in biological samples from these waters and in future rockfish age validation studies.

  16. 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

  17. 14C dating of small archaeological samples: neolithic to iron age in the central alpine region

    NASA Astrophysics Data System (ADS)

    Bill, J.; Keller, W. A.; Erne, R.; Bonani, G.; Wölfli, W.

    1984-11-01

    Accelerator mass spectrometry (AMS) radiocarbon 14C dating will widen enormously the range and scope of archaeological investigations. This is due mainly to 100- to 1000-fold sample size reduction over conventional dating. In order to determine the size and the quality of samples that can be accepted for AMS 14C dating, we have selected archaeological samples relating to the Neolithic to Iron Age. The basis of our AMS target preparations is the coking (pyrolysis) of organic matter after elimination of impurities by various physical and chemical treatments. The effect of the morphology as well as of the grain size distribution of the charcoal particles was determined in order to achieve optimal conditions for accelerator dating.

  18. 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.

  19. Age validation of quillback rockfish (Sebastes maliger) using bomb radiocarbon

    SciTech Connect

    Kerr, L A; Andrews, A H; Munk, K; Coale, K H; Frantz, B R; Cailliet, G M; Brown, T A

    2005-01-05

    Rockfishes (Sebastes spp.) support one of the most economically important fisheries of the Pacific Northwest and it is essential for sustainable management that age estimation procedures be validated for these species. Atmospheric testing of thermonuclear devices during the 1950s and 1960s created a global radiocarbon ({sup 14}C) signal in the ocean environment that scientists have identified as a useful tracer and chronological marker in natural systems. In this study, we first demonstrated that fewer samples are necessary for age validation using the bomb-generated {sup 14}C signal by emphasizing the utility of the time-specific marker created by the initial rise of bomb-{sup 14}C. Second, the bomb-generated {sup 14}C signal retained in fish otoliths was used to validate the age and age estimation methodology of the quillback rockfish (Sebastes maliger) in the waters of southeast Alaska. Radiocarbon values from the first year's growth of quillback rockfish otoliths were plotted against estimated birth year producing a {sup 14}C time series spanning 1950 to 1985. The initial rise of bomb-{sup 14}C from pre-bomb levels ({approx} -90 {per_thousand}) occurred in 1959 {+-} 1 year and {sup 14}C levels rose relatively rapidly to peak {Delta}{sup 14}C values in 1967 (+105.4 {per_thousand}), with a subsequent declining trend through the end of the record in 1985 (+15.4 {per_thousand}). The agreement between the year of initial rise of {sup 14}C levels from the quillback rockfish record and the chronometer determined for the waters of southeast Alaska from yelloweye rockfish (S. ruberrimus) otoliths validated the ageing methodology for the quillback rockfish. The concordance of the entire quillback rockfish {sup 14}C record with the yelloweye rockfish time series demonstrated the effectiveness of this age validation technique, confirmed the longevity of the quillback rockfish up to a minimum of 43 years, and strongly supports higher age estimates of up to 90 years.

  20. Radiocarbon variability in modern deep-sea bamboo coral skeletons from the North Atlantic

    NASA Astrophysics Data System (ADS)

    Farmer, J. R.; Hoenisch, B.; Robinson, L. F.

    2013-12-01

    Geochemical records from modern and recent deep-sea corals can provide new opportunities for understanding how changes in intermediate to deep ocean chemistry and circulation relate to climatic changes during the Common Era. Of critical importance for such comparisons are well-constrained coral growth rates (and hence chronology). Bamboo coral specimens of the genus Keratoisis are widely distributed in the modern oceans, but their calcitic skeletons exhibit open system U-Th behavior and many specimens show obscure growth banding, limiting available techniques for growth rate determinations. We measured radial transects of radiocarbon across the skeletons of six Keratoisis specimens that were live-collected in the northwestern North Atlantic Ocean between 1879 and 2005. Initial results show that Δ14C from the outer surface of three modern corals is within error of seawater Δ14C estimates at the site of coral collection from GLODAP. Most specimens show increasing 14C age toward the coral center, implying near-linear growth rates of 40 to 60 μm/14C year that are consistent with growth rates for North Atlantic Keratoisis specimens established by skeletal 210Pb and organic (gorgonian) 14C measurements. However, other specimens show radiocarbon variability that precludes accurate growth rate determinations for parts of the skeleton. In particular, multiple specimens exhibit systematic radiocarbon age reversals within 1-3 mm of the central growth axis, which is assumed to be the ontogenetically oldest part of the skeleton. This observation is consistent with previously published records of elevated unsupported 210Pb around the central growth axis of some North Atlantic Keratoisis specimens. We discuss potential physical and biological causes for the observed radiocarbon variability and implications for accurate growth rate determinations for bamboo coral skeletons.

  1. Disposition of [14C]ruboxistaurin in humans.

    PubMed

    Burkey, Jennifer L; Campanale, Kristina M; Barbuch, Robert; O'Bannon, Douglas; Rash, James; Benson, Charles; Small, David

    2006-11-01

    Ruboxistaurin is a potent and specific inhibitor of the beta isoforms of protein kinase C (PKC) that is being developed for the treatment of diabetic microvascular complications. The disposition of [(14)C]ruboxistaurin was determined in six healthy male subjects who received a single oral dose of 64 mg of [(14)C]ruboxistaurin in solution. There were no clinically significant adverse events during the study. Whole blood, urine, and feces were collected at frequent intervals after dosing. Metabolites were profiled by high performance liquid chromatography with radiometric detection. The total mean recovery of the radioactive dose was approximately 87%, with the majority of the radioactivity (82.6 +/- 1.1%) recovered in the feces. Urine was a minor pathway of elimination (4.1 +/- 0.3%). The major route of ruboxistaurin metabolism was to the N-desmethyl ruboxistaurin metabolite (LY338522), which has been shown to be active and equipotent to ruboxistaurin in the inhibition of PKC(beta). In addition, multiple hydroxylated metabolites were identified by liquid chromatography-mass spectrometry in all matrices. Pharmacokinetics were conducted for both ruboxistaurin and LY338522 (N-desmethyl ruboxistaurin, 1). These moieties together accounted for approximately 52% of the radiocarbon measured in the plasma. The excreted radioactivity was profiled using radiochromatography, and approximately 31% was structurally characterized as ruboxistaurin or N-desmethyl ruboxistaurin. These data demonstrate that ruboxistaurin is metabolized primarily to N-desmethyl ruboxistaurin (1) and multiple other oxidation products, and is excreted primarily in the feces. PMID:16896067

  2. Grass material as process standard for compound-specific radiocarbon analysis

    NASA Astrophysics Data System (ADS)

    Cisneros-Dozal, Malu; Xu, Xiaomei; Bryant, Charlotte; Pearson, Emma; Dungait, Jennifer

    2015-04-01

    Compound-specific radiocarbon analysis (CSRA) is a powerful tool to study the carbon cycle and/or as a dating technique in paleoclimate reconstructions. The radiocarbon value of individual compounds can provide insight into turnover times, organic matter sources and in specific cases can be used to establish chronologies when traditional dating materials (e.g. macrofossils, pollen, charcoal) are not available. The isolation of compounds (or group of compounds) from parent material (e.g. soil, plant) for radiocarbon analysis can, however, introduce carbon contamination through chemical separation steps and preparative capillary gas chromatography (PCGC). In addition, the compounds of interest are often in low abundance which amplifies the contamination effect. The extraneous carbon can be of modern 14C age and/or 14C -free and its amount and 14C value must be determined for a given system/isolation procedure in order to report accurate 14C values. This can be achieved by using adequate standard materials but, by contrast with traditional radiocarbon dating, there are not established reference standards for CSRA work, in part because the type of standard material depends on the compounds of interest and the isolation procedure. Here we evaluate the use of n-alkanes extracted from single-year growth grass as modern process standard material for CSRA using PCGC isolation. The grass material has a known 14C value of 1.224 ± 0.006 fraction modern (FM) and the individual n-alkanes are expected to have a similar 14C value. In order to correct for the addition of extraneous carbon during PCGC isolation of the n-alkanes, we used commercially available compounds of modern 14C content and 14C -free (adipic acid, FM= 0.0015 ± 0.0001 and docosane, FM=1.059 ± 0.003) to evaluate our PCGC procedure. The corrected 14C values of the isolated n-alkanes extracted from the modern grass are within one sigma of the grass bulk 14C value for n-C29 and within two sigma for n-C23-C27, C31

  3. Measurement of fecal /sup 14/C excretion

    SciTech Connect

    Kumaran, K.A.; Wiener, N.S.; Katz, J.B.

    1982-11-01

    Simultaneous measurements of fecal /sup 14/C and expired /sup 14/CO/sub 2/ in the breath are necessary to evaluate patients with various ileal abnormalities and bile salt malabsorption. Following the oral ingestion of the labeled bile acid, glycine-(I-/sup 14/C)cholic acid, detection of increased fecal /sup 14/C without abnormal expiration of /sup 14/CO/sub 2/ identifies patients with ileal resection. This contrasts with the normal fecal /sup 14/C content and abnormal expired /sup 14/CO/sub 2/ found in patients with bacterial overgrowth. Fecal /sup 14/C content was determined by utilizing Van Slyke combustion of the specimen and trapping the liberated /sup 14/CO/sub 2/ with Scintisorb C. The method is simple, rapid, and accurate, and expands the diagnostic usefulness of the bile salt absorption test.

  4. Comparison of bone collagen and osteocalcin for determination of radiocarbon ages and paleodietary reconstruction

    NASA Astrophysics Data System (ADS)

    Ajie, Henry O.; Hauschka, Peter V.; Kaplan, Isaac R.; Sobel, Harry

    1991-11-01

    Osteocalcin, a gamma-carboxyglutamic acid containing bone protein, is tightly bound to the hydroxyapatite matrix of bone, and as a consequence it is relatively more stable than the dominant protein, collagen. Its distribution in nature is limited to vertebrates. Osteocalcin and collagen have been isolated from modern and fossil bone samples of different organisms in different depositional environments for analysis of their δ 13C , δ 15N and 14C content. Whereas collagen is susceptible t aqueous weathering, hydrolysis, solubilization and removal, as well as contamination by soil amino acids or peptides, osteocalcin is more strongly bonded to the apatite matrix of the bone and hence less prone to loss or replacement by contaminants. We present evidence suggesting that osteocalcin may be a more suitable protein fraction for obtaining accurate 14C age estimates and/or δ 13C and δ 15N for paleodietary reconstruction from bone samples.

  5. Radiocarbon-based source apportionment of black carbon (BC) in PM 10 aerosols from residential area of suburban Tokyo

    NASA Astrophysics Data System (ADS)

    Uchida, Masao; Kumata, Hidetoshi; Koike, Yasuyo; Tsuzuki, Mikio; Uchida, Tatsuya; Fujiwara, Kitao; Shibata, Yasuyuki

    2010-04-01

    The AMS technique was applied to analyse black carbon (BC), total organic carbon (TOC), and previously reported polycyclic aromatic hydrocarbons (PAHs) in PM 10 aerosols from a residential area, suburban Tokyo, to determine natural abundance of radiocarbon ( 14C), an ideal tracer to distinguish fossil fuel ( 14C-free) from modern biomass combustion sources of pyrolytic products. The 14C concentrations in BC, isolated using the CTO-375 method, were 42% and 30% pMC (in terms of percent Modern Carbon: pMC) in summer and winter, respectively. The 14C concentrations in BC were also compared with those of compound-class specific 14C content of PAHs previously reported for the same samples: they were 45% and 33% pMC in summer and winter, respectively. The 14C signals of BC were identical to those of high molecular weight (MW ⩾ 226, 5-6 rings) PAHs. The resemblance between 14C signals of BC and PAHs can be referred as a 'certificate' for the validity of the BC isolation method employed in this study. Also, it suggests that 14C-BC approach can be a surrogate for PAHs specific 14C analyses to monitor seasonal source variation of combustion-derived pyrolytic products. On the other hand, 14C contents of total organic carbon in 2004 were 61% and 42% pMC in summer and winter, respectively. This is likely attributed to higher contribution of plant activity in summer.

  6. Extraneous carbon assessment in ultra-microscale radiocarbon analysis using benzene polycarboxylic acids (BPCA)

    NASA Astrophysics Data System (ADS)

    Hanke, Ulrich M.; McIntyre, Cameron P.; Schmidt, Michael W. I.; Wacker, Lukas; Eglinton, Timothy I.

    2016-04-01

    Measurements of the natural abundance of radiocarbon (14C) concentrations in inorganic and organic carbon-containing materials can be used to investigate their date of origin. Particularly, the biogeochemical cycling of specific compounds in the environment may be investigated applying molecular marker analyses. However, the isolation of specific molecules from environmental matrices requires a complex processing procedure resulting in small sample sizes that often contain less than 30 μg C. Such small samples are sensitive to extraneous carbon (Cex) that is introduced during the purification of the compounds (Shah and Pearson, 2007). We present a thorough radiocarbon blank assessment for benzene polycarboxylic acids (BPCA), a proxy for combustion products that are formed during the oxidative degradation of condensed polyaromatic structures (Wiedemeier et al, in press). The extraneous carbon assessment includes reference material for (1) chemical extraction, (2) preparative liquid chromatography (3) wet chemical oxidation which are subsequently measured with gas ion source AMS (Accelerator Mass Spectrometer, 5-100 μg C). We always use pairs of reference materials, radiocarbon depleted (14Cfossil) and modern (14Cmodern) to determine the fraction modern (F14C) of Cex.Our results include detailed information about the quantification of Cex in radiocarbon molecular marker analysis using BPCA. Error propagation calculations indicate that ultra-microscale samples (20-30 μg) are feasible with uncertainties of less than 10 %. Calculations of the constant contamination reveal important information about the source (F14C) and mass (μg) of Cex (Wacker and Christl, 2011) for each sub procedure. An external correction of compound specific radiocarbon data is essential for robust results that allow for a high degree of confidence in the 14C results. References Shah and Pearson, 2007. Ultra-microscale (5-25μg C) analysis of individual lipids by 14C AMS: Assessment and

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

    NASA Astrophysics Data System (ADS)

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

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

  8. Construction of reliable radiocarbon-based chronologies for speleothems

    NASA Astrophysics Data System (ADS)

    Lechleitner, Franziska; Fohlmeister, Jens; McIntyre, Cameron; Baldini, Lisa M.; Jamieson, Robert A.; Hercman, Helena; Gasiorowski, Michal; Pawlak, Jacek; Stefaniak, Krzysztof; Socha, Pawel; Eglinton, Timothy I.; Baldini, James U. L.

    2016-04-01

    Speleothems have become one of the most widely applied archives for paleoclimate research. One of their key advantages is their amenability for U-series dating, often producing excellent high precision chronologies. However, stalagmites with high detrital Th or very low U concentrations are problematic to date using U-series, and sometimes need to be discarded from further paleoclimate analysis. Radiocarbon chronologies could present an alternative for stalagmites that cannot be dated using U-series, if offsets from the "dead carbon fraction" (DCF) can be resolved. The DCF is a variable reservoir effect introduced by the addition of 14C-dead carbon from host rock dissolution and soil organic matter. We present a novel age modeling technique that provides accurate 14C-based chronologies for stalagmites. As this technique focuses on the long-term decay pattern of 14C, it is only applicable on stalagmites that show no secular variability in their 14C-depth profiles, but is independent of short-term DCF variations. In order to determine whether a stalagmite is suitable for this method without direct knowledge of long-term trends in the DCF, we highlight how other geochemical proxies (δ13C, Mg/Ca) can provide additional information on changes in karst hydrology, soil conditions, and climate that would affect DCF. We apply our model on a previously published U-Th dated stalagmite 14C dataset from Heshang Cave, China with excellent results, followed by a previously 'undateable' stalagmite from southern Poland.

  9. Anomalous elevated radiocarbon measurements of PM2.5

    NASA Astrophysics Data System (ADS)

    Buchholz, Bruce A.; Fallon, Stewart J.; Zermeño, Paula; Bench, Graham; Schichtel, Bret A.

    2013-01-01

    Two-component models are often used to determine the contributions made by fossil fuel and natural sources of carbon in airborne particulate matter (PM). The models reduce thousands of actual sources to two end members based on isotopic signature. Combustion of fossil fuels produces PM free of carbon-14 (14C). Wood or charcoal smoke, restaurant fryer emissions, and natural emissions from plants produce PM with the contemporary concentration of 14C approximately 1.2 × 10-1214C/C. Such data can be used to estimate the relative contributions of fossil fuels and biogenic aerosols to the total aerosol loading and radiocarbon analysis is becoming a popular source apportionment method. Emissions from incinerators combusting medical or biological wastes containing tracer 14C can skew the 14C/C ratio of PM, however, so critical analysis of sampling sites for possible sources of elevated PM needs to be completed prior to embarking on sampling campaigns. Results are presented for two ambient monitoring sites in different areas of the United States where 14C contamination is apparent. Our experience suggests that such contamination is uncommon but is also not rare (∼10%) for PM sampling sites.

  10. 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. PMID:16785168

  11. 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.

  12. New Radiocarbon Dates on Upper Mid-West Proboscideans: Determining Date Robustness

    NASA Astrophysics Data System (ADS)

    Hodgins, G.; Widga, C.; Lengyel, S. N.; Saunders, J.; Walker, J. D.

    2013-12-01

    With the objective of refining the picture of Megafaunal extinction patterns in the upper Midwest in the terminal Pleistocene, we have assembled for radiocarbon dating specimens from more than 80 distinct Mammut and Mammuthus remains from potentially late sites. So far, we have measurements for 65 bones, tusks and teeth, nearly double the extant number of published dates . These new specimens were all from museums rather than excavation sites, and 60% were known to be coated with a consolidant. The predominant consolidant was Butvar B-76, however shellac, Elmer's Glue, Glyptol were also noted in the conservation records, or deduced from knowledge of a particular museum's practices. Given the objective of the project is to identify extinction patterns, coupled with the wide prevalence of consolidants amongst the specimen set, it was imperative that testing be carried out to confirm that radiocarbon laboratory protocols removed the consolidants, so that ultimately the dates can be considered robust. To this end, key specimens were dated three times using different sample preparation protocols. These were 1) a solvent extraction followed by a modified Longin-plus -Base continuous flow collagen extraction method used in the NSF-Arizona AMS facility, 2) the solvent/modified Longin method plus ultrafiltration, and 3) solvent/modified Longin method plus hydroxyproline single amino acid dating. Among the specimens subjected to triplicate testing were some of the youngest late Wisconsin proboscidean specimens from the Upper Midwest Region. The data reveal general agreement between the different protocols, and suggested either limited penetration of consolidants into the specimens, or that the standard laboratory cleaning protocols were sufficient to remove traces from deep within bone, tooth or tusk tissue. The preservation of each specimen, recorded in terms of collagen content, C/N ratio and stable isotope values, indicated that most were actually well preserved, implying

  13. Slip rate determination along the Southern Dead Sea fault: optically stimulated luminescence, 10Be cosmogenic radionuclide, and 14C ages brought face to face

    NASA Astrophysics Data System (ADS)

    Le Beon, Maryline; Jaiswal, Manoj; Kunz, Alexander; Al-Qaryouti, Mahmoud; Burr, George; Klinger, Yann; Moumani, Khaled; Chen, Yue-Gau; Abdelghafoor, Mohammed; Suppe, John

    2014-05-01

    Active tectonics studies are often limited by difficulties in accurately and precisely dating Late Quaternary alluvial deposits that commonly lack organic matter or date beyond the 14C dating limit. This is illustrated at a site called Fidan, in arid southern Jordan, where a series of alluvial fans are laterally offset by the southern Dead Sea fault. Geodetic, geomorphic and geologic studies converge to a fault slip rate of 5 ± 2 mm/a. Yet, Late Pleistocene slip rate at Fidan cover a wide range due 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 fault seismic behavior, we implement complementary dating using optically stimulated luminescence (OSL) techniques on both quartz and K-feldspar minerals and using 14C when possible. OSL measurements include a newly developed technique called post-infra-red infra-red stimulated luminescence at 290°C (pIR290). We extensively sampled surface levels F2 and F4, digging ~50-cm deep pits into the geomorphic surfaces. Annual dose rates were determined in the laboratory from both geochemical analysis of the sediment and gamma-ray spectrometry. Due to sediment heterogeneity, we consider gamma-ray spectrometry as more reliable because it is based on a larger volume of sediment. Quartz OSL ages and preliminary pIR290 results on K-feldspars give consistent Early Holocene ages of 9-14 ka for F2, also in agreement with a 14C age of 13 ka from a landsnail shell. 10Be CRN exposure ages on F2 were significantly older, with 37 ± 4 ka, probably due to inheritance. On F4, 10Be CRN exposure ages showed a scattered distribution, from ~50 ka to ~120 ka, with most samples comprised in the mean interval of 87 ± 26 ka. Quartz OSL ages from 5 locations on F4 are comprised between 32 ± 3

  14. 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

  15. 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.

  16. Blade-order-dependent radiocarbon variability in brown seaweed (Undaria pinnatifida) reflected a cold Oyashio water intrusion event in an embayment of the Sanriku coast, northeastern Japan

    NASA Astrophysics Data System (ADS)

    Satoh, N.; Fukuda, H.; Miyairi, Y.; Yokoyama, Y.; Nagata, T.

    2015-12-01

    Radiocarbon in dissolved inorganic carbon (DIC) in seawater varies greatly, both geographically and with depth. This "reservoir effect" is thought to be reflected in the radiocarbon content (∆14C) of marine organisms, via DIC fixation by primary producers and subsequent trophic transfer. The ∆14C of marine organismal soft tissues might thus provide unique information about their habitats, diets, migration and other environmental histories. However, the effectiveness of this approach has yet to be extensively explored, with data on ∆14C variability in soft tissues of marine organisms being markedly limited. Here we examined whether ∆14C values of individual pinnate blades (leaf-like structures) of brown seaweed (Undaria pinnatifida) reflect the ∆14C of DIC in the water current prevailing at the time of blade formation. The study was conducted in Otsuchi Bay located in the Sanriku coastal region, northeastern Japan, where 14C-depleted cold Oyashio current and warm Tsugaru current (high ∆14C) converge, affecting the physiology and growth of marine organisms growing there. U. pinnatifida individuals cultured in the bay (length of saprophytes, 140-215 cm) were harvested in April 2014 and ∆14C of blades were determined by accelerator mass spectrometry. Younger blades formed after the Oyashio water intrusion had significantly lower ∆14C values compared to older blades formed before the event. The ∆14C values of younger and older blades were generally consistent with the ∆14C of DIC in Oyashio (-60.5 ‰) and Tsugaru (24.9 ‰) waters, respectively. Thus, despite possible turnover of organic carbon in seaweed soft tissues, blade-order-dependent ∆14C variability appeared to strongly reflect the Oyashio intrusion event (radiocarbon shift) in the bay.

  17. 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

  18. Bioconversion of alpha-[14C]zearalenol and beta-[14C]zearalenol into [14C]zearalenone by Fusarium roseum 'Gibbosum'.

    PubMed Central

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

    1984-01-01

    Cultures of Fusarium roseium 'Gibbosum' on rice were treated with [14C]zearalenone, alpha[14C]zearalenol, or beta-[14C]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-[14C]zearalenol was converted to zearalenone, and no residual beta-[14C]zearalenol was detectable. Most of the alpha-[14C]zearalenol added was also converted into zearalenone with 14 days. In cultures treated with [14C]zearalenone, no radioactivity was noted in any other components. PMID:6742839

  19. 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. PMID:24814329

  20. 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

  1. Intermediate water radiocarbon off west Sumatra during the last 45,000 years

    NASA Astrophysics Data System (ADS)

    De Pol-Holz, R.; Mohtadi, M.; Southon, J.

    2012-04-01

    Radiocarbon content of intermediate waters originating from the Southern Ocean is held as the likely smoking gun of the events that triggered the atmospheric CO2 rise and its radiocarbon content decline during the last glacial-interglacial transition. Extremely depleted radiocarbon has been found off the coast of Baja California, the Galapagos and the Arabian Sea, but not unequivocally elsewhere. Knowing the route of the old water is therefore central for the mechanistic linkage of Southern Ocean processes and the atmospheric response. Here, we present high-resolution radiocarbon content of intermediate depth waters off west Sumatra in the attempt to trace the hypothetical route of old water emanating near Antarctica. Sediment core SO189-39KL (0°47'S, 99°55'E, 517 m) resulted in a 1350 cm hemipelagic sedimentary sequence that spans the last 45,000 years and it was sampled for planktonic and benthic foraminifera radiocarbon determinations at a centennial time resolution. Besides the planktonic radiocarbon age control points, we attempted an independent stratigraphy based on the Mg/Ca sea surface temperature evolution and its apparent similarity with Antarctic Ice core records. This allowed us to infer surface reservoir ages as well as the D14C of the intermediate waters. Our results show that throughout the LGM and the entire deglaciation, radiocarbon content at 500 m depth off west Sumatra remained in equilibrium with the contemporaneous atmosphere, discarding this area as a probable route for the spreading of the old water along its way to northern latitudes. These results add up to increasing evidence that the radiocarbon content of intermediate waters originating from the Southern Ocean was not influenced by the upwelling of a large abyssal old water reservoir, as it has been hypothesized in order to explain the atmospheric deglacial records.

  2. 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

  3. Carbonates in leaching reactions in context of 14C dating

    NASA Astrophysics Data System (ADS)

    Michalska, Danuta; Czernik, Justyna

    2015-10-01

    Lime mortars as a mixture of binder and aggregate may contain carbon of various origins. If the mortars are made of totally burnt lime, radiocarbon dating of binder yields the real age of building construction. The presence of carbonaceous aggregate has a significant influence on the 14C measurements results and depending on the type of aggregate and fraction they may cause overaging. Another problem, especially in case of hydraulic mortars that continue to be chemically active for a very long time, is the recrystallization usually connected with rejuvenation of the results but also, depending on local geological structures, with so called reservoir effect yielding apparent ages. An attempt in separating the binder from other carbonaceous components successfully was made for samples from Israel by Nawrocka-Michalska et al. (2007). The same preparation procedure, after taking into account the petrographic composition, was used for samples coming from Poland, Nawrocka et al. (2009). To verify the procedure used previously for non-hydraulic samples determination an experimental tests on carbonaceous mortars with crushed bricks from Novae in Bulgaria were made. Additionally, to identify different carbonaceous structures and their morphology, a cathodoluminescence and scanning electron microscope with electron dispersive spectrometer were applied. The crushed bricks and brick dust used in mortars production process have been interpreted as an alternative use to other pozzolanic materials. The reaction between lime and pozzolanic additives take place easily and affects the rate and course of carbonates decomposition in orthophosphric acid, during the samples pretreatment for dating. The composition of the Bulgarian samples together with influence of climate conditions on mortar carbonates do not allow for making straightforward conclusions in chronology context, but gives some new guidelines in terms of hydraulic mortars application for dating. This work has mainly

  4. 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.

  5. Excursions in the 14C record at A.D. 774-775 in tree rings from Russia and America

    NASA Astrophysics Data System (ADS)

    Jull, A. J. Timothy; Panyushkina, Irina P.; Lange, Todd E.; Kukarskih, Vladimir V.; Myglan, Vladimir S.; Clark, Kelley J.; Salzer, Matthew W.; Burr, George S.; Leavitt, Steven W.

    2014-04-01

    The calibration of radiocarbon dates by means of a master calibration curve has been invaluable to Earth, environmental and archeological sciences, but the fundamental reason for calibration is that atmospheric radiocarbon content varies because of changes in upper atmosphere production and global carbon cycling. Improved instrumentation has contributed to high-resolution (interannual) radiocarbon activity measurements, which have revealed sudden and anomalous activity shifts previously not observed at the common resolution of 5-10 years of most of the calibration scale. One such spike has been recently reported from tree rings from Japan and then again in Europe at A.D. 774-775, for which we report here our efforts to both replicate its existence and determine its spatial extent using tree rings from larch at high latitude (northern Siberia) and bristlecone pine from lower latitude (the White Mountains of California). Our results confirm an abrupt ~ 15‰ 14C activity increase from A.D. 774 to 776, the size and now the hemispheric extent of which suggest that an extraterrestrial influence on radiocarbon production is most likely responsible.

  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. Determination of shell deposition rates of Arctica islandica from the New York Bight using natural /sup 228/Ra and /sup 228/Th and bomb-produced /sup 14/C

    SciTech Connect

    Turekian, K.K.; Cochran, J.K.; Nozaki, Y.; Thompson, I.; Jones, D.S.

    1982-01-01

    Shell deposition rates of specimens of Arctica islandica (Mollusca: Bivalvia) from the New York Bight were determined using natural /sup 228/Ra and /sup 228/Th and bomb /sup 14/C. The specimens from deep (>55 m) offshore waters show annual growth banding. A shell obtained from the inner bight at <30-m depth seems to be younger than indicated by band counting.

  8. Astronomical evidence relating to the observed 14C increases in A.D. 774-5 and 993-4 as determined from tree rings

    NASA Astrophysics Data System (ADS)

    Stephenson, F. Richard

    2015-03-01

    A detailed study is made of celestial observations recorded in East Asian and European history around A.D. 774-5 and 993-4. These include reports of supernovae, comets, sunspots and aurorae. The aim is to attempt to provide astronomical evidence in support of the measured 14C increases in tree rings at these dates. However, the results prove to be far from convincing, leaving the physical cause of the increases still in doubt.

  9. Degradation of 4-fluorobiphenyl by mycorrhizal fungi as determined by {sup 19}F nuclear magnetic resonance spectroscopy and {sup 14}C radiolabelling analysis

    SciTech Connect

    Green, N.A.; Meharg, A.A.; Till, C.; Troke, J.; Nicholson, J.K.

    1999-09-01

    The pathways of biotransformation of 4-fluorobiphenyl (4FBP) by the ectomycorrhizal fungus Tylospora fibrilosa and several other mycorrhizal fungi were investigated by using {sup 19}F nuclear magnetic resonance (NMR) spectroscopy in combination with {sup 14}C radioisotope-detected high-performance liquid chromatography ({sup 14}C-HPLC). Under the conditions used in this study T. fibrillosa and some other species degraded 4FBP. {sup 14}C-HPLC profiles indicated that there were four major biotransformation products, whereas {sup 19}F NMR showed that there were six major fluorine-containing products. The authors confirmed that 4-fluorobiphen-4{prime}-ol and 4-fluorobiphen-3{prime}-ol were two of the major products formed, but no other products were conclusively identified. There was no evidence for the expected biotransformation pathway (namely, meta cleavage of the less halogenated ring), as none of the expected products of this route were found. To the best of their knowledge, this is the first report describing intermediates formed during mycorrhizal degradation of halogenated biphenyls.

  10. Effects of polyacrylamide, biopolymer, and biochar on decomposition of soil organic matter and 14C-labeled plant residues as determined by enzyme activities

    NASA Astrophysics Data System (ADS)

    Mahmoud Awad, Yasser; Ok, Young Sik; Kuzyakov, Yakov

    2014-05-01

    Application of polymers for the improvement of aggregate structure and reduction of soil erosion may alter the availability and decomposition of plant residues. In this study, we assessed the effects of anionic polyacrylamide (PAM), synthesized biopolymer (BP), and biochar (BC) on the decomposition of 14C-labeled maize residue in sandy and sandy loam soils. Specifically, PAM and BP with or without 14C-labeled plant residue were applied at 400 kg ha-1, whereas BC was applied at 5000 kg ha-1, after which the soils were incubated for 80 days at 22 oC. Initially, plant residue decomposition was much higher in untreated sandy loam soil than in sandy soil. Nevertheless, the stimulating effects of BP and BC on the decomposition of plant residue were more pronounced in sandy soil, where it accounted for 13.4% and 23.4% of 14C input, respectively, whereas in sandy loam soil, the acceleration of plant residue decomposition by BP and BC did not exceed 2.6% and 14.1%, respectively, compared to untreated soil with plant residue. The stimulating effects of BP and BC on the decomposition of plant residue were confirmed based on activities of β-cellobiohydrolase, β-glucosidase, and chitinase in both soils. In contrast to BC and BP, PAM did not increase the decomposition of native or added C in both soils.

  11. Limitations in the use of /sup 14/C-glycocholate breath and stool bile acid determinations in patients with chronic diarrhea

    SciTech Connect

    Ferguson, J.; Walker, K.; Thomson, A.B.

    1986-06-01

    Analysis of a modified /sup 14/C-glycocholate breath test on 165 consecutive in-patients being investigated for chronic diarrhea showed that the measurement of /sup 14/CO/sub 2/ between 3 and 6 h after oral dosing of 5 microCi of /sup 14/C-glycocholic acid was of only limited use to distinguish between patients with Crohn's disease (CD), idiopathic bile salt wastage (IBW), or ileal resection (IR) from those with the irritable bowel syndrome (IBS). Continuing /sup 14/CO/sub 2/ collections for up to 24 h was of little more help in establishing the presence of bacterial overgrowth syndrome (BOS) and in distinguishing between BOS and CD. Stool bile acid measurements were of use in differentiating between IBW and IBS, but did not distinguish between CD and BOS or between CD and IR. Since the range of normal values was defined by measurements in the IBS group, a positive test was specific for an organic cause of chronic diarrhea. Even so, the sensitivity of the test was relatively low: CD, 53%; IR, 23%; IBW, /sup 14/%; and BOS, 10%. We believe that the 24-h /sup 14/C-glycocholic breath test combined with the measurement of stool bile acids represents a screening test of only limited use for the identification of organic causes of chronic diarrhea.

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

    To explore the transport of carbon into water masses from the surface ocean to depths of ∼ 1000 m in the southwest Pacific Ocean, we generated time series of radiocarbon14C) from fish otoliths. Otoliths (carbonate earstones) from long-lived fish provide an indirect method to examine the "bomb pulse" of radiocarbon that originated in the 1950s and 1960s, allowing identification of changes to distributions of 14C that has entered and mixed within the ocean. We micro-sampled ocean perch (Helicolenus barathri) otoliths, collected at ∼ 400- 500 m in the Tasman Sea, to obtain measurements of Δ14C for those depths. We compared our ocean perch Δ14C series to published otolith-based marine surface water Δ14C values (Australasian snapper (Chrysophrys auratus) and nannygai (Centroberyx affinis)) and to published deep-water values (800-1000 m; orange roughy (Hoplostethus atlanticus)) from the southwest Pacific to establish a mid-water Δ14C series. The otolith bomb 14C results from these different depths were consistent with previous water mass results in the upper 1500 m of the southwest Pacific Ocean (e.g. World Ocean Circulation Experiment and Geochemical Ocean Sections Study). A comparison between the initial Δ14C bomb pulse rise at 400-500 m suggested a ventilation lag of 5 to 10 yr, whereas a comparison of the surface and depths of 800-1000 m detailed a 10 to 20 yr lag in the time history of radiocarbon invasion at this depth. Pre-bomb reservoir ages derived from otolith 14C located in Tasman Sea thermocline waters were ∼ 530 yr, while reservoir ages estimated for Tasman Antarctic intermediate water were ∼ 730 yr.

  13. Holocene sea-level determination relative to the Australian continent: U/Th (TIMS) and 14C (AMS) dating of coral cores from the Abrolhos Islands

    NASA Astrophysics Data System (ADS)

    Eisenhauer, A.; Wasserburg, G. J.; Chen, J. H.; Bonani, G.; Collins, L. B.; Zhu, Z. R.; Wyrwoll, K. H.

    1993-02-01

    U/Th (TIMS) and 14C (AMS) measurements are presented from two coral cores from the Easter group of the Houtman Abrolhos Islands between 28°S and 29°S on the western continental margin of Australia. The U/Th measurements on the Morley core from Morley Island cover a depth interval from 0.2 m above present sea level to 24.4 m below present sea level and comprise eleven samples. The ages vary between 6320 ± 50 a, at 0.2 m above sea level, and 9809 ± 95 a, at 24.4 m below sea level (all errors are 2σ). The mean growth rate is 7.1 ± 0.9 m/ka. The 14C dates of selected Morley core corals show that the 14C ages are ˜ 1000 a younger than their corresponding U/Th ages, which agrees with previous results. The main purpose of our 14C measurements is to be able to compare them precisely with other coral cores where no U/Th measurements are available. The U/Th measurements of the Suomi core from Suomi Island cover a depth interval from 0.05 m to 14.2 m below present sea level and consist of four samples. The ages vary between 4671 ± 40 a, at 0.05 m below sea level, and 7102 ± 82 a, at 14.2 m below sea level, with a mean growth rate of 5.8 ± 0.2 m/ka. The growth history of both cores is explained by a simple model in which the growth rates of the Morley core can be interpreted as reflecting local rates of sea level rise, whereas the Suomi core is interpreted as reflecting lateral growth during the past ˜ 6000 a. Our results indicate that sea level relative to the western margins of the Australian continent was about 24 m lower than present at about 9800 a B.P. ( 14C gives a date of 8500 a B.P.). Sea level then rose and reached a highstand, slightly higher than the present position at about 6300 a B.P ( 14C date: 5500 a). This highstand declined but was still higher than present at 4600 a B.P. This is in agreement with previous observations along the Australian coastal margins and with observations from the Huon peninsula (Papua New Guinea). Our results are very

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

    NASA Astrophysics Data System (ADS)

    Miyata, Y.; Minami, M.; Onbe, S.; Sakamoto, M.; Nakamura, T.; Imamura, M.

    2013-01-01

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

  15. Radiocarbon ages of pre-bomb clams and the hard-water effect in Lakes Michigan and Huron

    USGS Publications Warehouse

    Rea, David K.; Colman, Steven M.

    1995-01-01

    Five radiocarbon ages, all determined by accelerator mass spectrometry, have been obtained for two pre-bomb bivalves from Lake Michigan and one from Lake Huron. After correcting those ages for the fractionation of14C in calcite and for the radioactively inert CO2 in the atmosphere, we find residual ages, caused by the hard water effect, of about 250 years for Lake Michigan and 440 years for Lake Huron.

  16. 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.

  17. 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.

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

    NASA Astrophysics Data System (ADS)

    Wang, Hong; Hackley, Keith C.; Panno, Samuel V.; Coleman, Dennis D.; Liu, Jack Chao-li; Brown, Johnie

    2003-11-01

    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 (δ 13C) was heavier in the Py-V fractions, suggesting a greater abundance of carbohydrate- and protein-related constituents, and δ 13C was lighter in the Py-R fractions, suggesting more lignin- and lipid-related constituents. The combination of 14C dates and δ 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.

  19. 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

  20. Differential extraction of radiocarbon associated with soil biomass and humus

    SciTech Connect

    Tsao, C.W.; Bartha, R. . Cook Coll.)

    1999-04-01

    To detect the humification of organic compounds in soil that bypasses biomass incorporation, selective extraction procedures for radiocarbon from soil biomass and humus were evaluated. Following the incubation of [sup 14]C-glucose and [sup 14]C-benzoate in soil, fumigation--0.5 M K[sub 2]SO[sub 4] extraction and 0.15 M Na[sub 4]P[sub 2]O[sub 7] extraction selectively removed biomass-associated and humus-associated radiocarbon, respectively. Applying the recovery correction of 3.4[times] to biomass and 3.5[times] to humus, radiocarbon balances of 95 to 107% were obtained during a time window following the degradation of these substrates. Negligible overlap between the extractions renders the technique suitable for investigating the fate of organics that, through cometabolism, attain unusual radiocarbon distributions in soil.

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

    NASA Astrophysics Data System (ADS)

    Culp, Randy

    2013-01-01

    Compound-specific isotope analysis (CSIA) is a powerful tool in organic geochemistry by providing detailed information about an individual organic compound’s history with regard to its source and process of formation. Most CSIA involves measurement of the stable isotope ratio of carbon (13C/12C) and hydrogen (D/H) following separation by gas or liquid chromatography. New applications are being developed using compound-specific radiocarbon (14C) content for delineating age of materials, rates of decomposition and residence time in various environments. This paper details the isotopic work on specific lignin monomers derived from terrestrial plants transported and deposited within the Altamaha River, estuary and off-shore Georgia in the Atlantic Ocean. By using gas chromatographic separation and identification of selected lignin oxidation products (LOP), the harvesting of these compounds using preparative fraction collection, and measurement of their 14C content using accelerator mass spectrometry, details of the age and presence of specific biomarkers unique to a given terrestrial source are revealed. Radiocarbon ages determined from water-column particulate organic carbon and sediment LOPs indicate a range of ages from modern to well over 5,000 years for the former and latter respectively. Transport mechanisms and particle size associations on mineral grains may play a significant role in 14C distribution in estuary and near-shore coastal environments. This data indicates higher than modern 14C activities in large particle-size sediment fractions in contrast to older LOP 14C ages found associated with the same coarse grain sediments. Individual LOP ages substantiate older terrestrial materials persist in the off-shore environment even though in the presence of modern marine 14C sources.

  2. Developing inorganic carbon-based radiocarbon chronologies for Holocene lake sediments in arid NW China

    NASA Astrophysics Data System (ADS)

    Zhang, Jiawu; Ma, Xueyang; Qiang, Mingrui; Huang, Xiaozhong; Li, Shuang; Guo, Xiaoyan; Henderson, Andrew C. G.; Holmes, Jonathan A.; Chen, Fahu

    2016-07-01

    Inorganic carbonates are often used to establish radiocarbon (14C) chronologies for lake sediments when terrestrial plant remains (TPR) are rare or when bulk organic matter is insufficient for dating, a problem that is common for many lakes in arid regions. However, the reservoir effect (RE), as well as old carbon contributed from the lakes catchment make it difficult to establish reliable chronologies. Here we present a systematic study of inorganic 14C ages of two lake-sediment sequences, one from a small-enclosed saline lake - Lake Gahai in Qaidam Basin, and the other from a large freshwater lake - Lake Bosten in Xinjiang. Modern dissolved inorganic carbon (DIC) of the lakes, paleo-lake sediments exposed in the catchment, and mollusk shells in core sediments from Lake Gahai were dated to assess the RE and the contribution of pre-aged carbon to the old ages in the cores. We propose a statistical regression to assess more than one RE for the 14C carbonate ages within our sedimentary sequences. Old radiocarbon ages contributed by detrital carbonates were assessed by comparing the ages of mollusk shells with those of carbonates at the same sediment depths. We established the RE of the authigenic component and assessed detrital old carbon contributions to our two sites, and this was used to correct the 14C ages. Based on this approach, we developed age models for both cores, and tested them using 210Pb ages in both cores and TPR-based 14C-ages recovered from Lake Bosten. We further tested our age models by comparing carbonate-based oxygen isotope (δ18O) records from both lakes to an independently-dated regional speleothem δ18O record. Our results suggest if sedimentary sequences are densely dated and the RE and the contribution of old carbon from detrital carbonates can be ascertained, robust chronological frameworks based on carbonate-based 14C determinations can be established.

  3. 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 (

  4. A Column Experiment To Determine Black Shale Degradation And Colonization By Means of δ13C and 14C Analysis Of Phospholipid Fatty Acids And DNA Extraction

    NASA Astrophysics Data System (ADS)

    Seifert, A.; Gleixner, G.

    2008-12-01

    We investigated the degradation of black shale organic matter by microbial communities. We inoculated two columns respectively, with the fungi Schizophyllum commune, the gram-positive bacterium Pseudomonas putida and the gram-negative bacteria Streptomyces griseus and Streptomyces chartreusis. These microorganisms are known to degrade a wide variety of organic macromolecules. Additionally, we had two sets of control columns. To one set the same nutrient solution was added as to the inoculated columns and to the other set only sterile deionised water was supplied. All columns contained 1.5 kg of freshly crushed not autoclaved black shale material with a particle size of 0.63-2 mm. The columns were incubated at 28° C and 60% humidity in the dark. The aim was to investigate, which microorganisms live on black shales and if these microorganisms are able to degrade ancient organic matter. We used compound specific stable isotope measurement techniques and compound specific 14C-dating methods. After 183 days PLFAs were extracted from the columns to investigate the microbial community, furthermore we extracted on one hand total-DNA of column material and on the other hand DNA from pure cultures isolates which grew on Kinks-agar B, Starch-casein-nitrate-agar (SCN) and on complete-yeast-medium-agar (CYM). According to the PLFA analysis bacteria dominated in the columns, whereas in pure cultures more fungi were isolated. A principal component analysis revealed differences between the columns in accordance with the inoculation, but it seems that the inoculated microorganisms were replaced by the natural population. For AMS measurements palmitic acid (C 16:0) was re-isolated from total-PLFA-extract with a preparative fraction collector (PFC). Preliminary results of the study revealed that microorganisms are able to degrade black shale material and that PLFA analysis are useful methods to be combined with analysis of stable isotope and 14C measurements to study microbial

  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. Understanding the production and retention of in situ cosmogenic 14C in polar firn

    NASA Astrophysics Data System (ADS)

    Hmiel, B.; Petrenko, V. V.; Smith, A.; Buizert, C.; Harth, C. M.; Beaudette, R.; Place, P., Jr.; Hua, Q.; Yang, B.; Vimont, I.; Weiss, R. F.; Severinghaus, J. P.; Brook, E.; White, J. W. C.

    2014-12-01

    Radiocarbon in CO2, CO and CH4 trapped in polar ice is of interest for dating of ice cores, studies of past solar activity and cosmic ray flux, as well as studies of the paleoatmospheric CH4 budget. The major difficulty with interpreting 14C measurements in ice cores stems from the fact that the measured 14C represents a combination of trapped paleoatmospheric 14C and 14C that is cosmogenically produced within the ice matrix. This in situ cosmogenic 14C component in ice is at present poorly understood. Prior ice core 14C studies show conflicting results with regard to the retention of cosmogenic 14C in polar firn and partitioning of this 14C among CO2, CO and CH4. Our new study aims to comprehensively characterize the 14C of CO2, CO, and CH4 in both the air and the ice matrix throughout the firn column at Summit, Greenland. We will present new measurements of 14C in Summit firn air (the first phase of this study) and discuss the implications for in situ cosmogenic 14C production and retention.

  7. Dermal penetration of 14C-labeled diisopropyl methylphosphonate in swine. Toxicological study

    SciTech Connect

    Snodgrass, H.L.; Metker, L.W.

    1991-10-01

    DIMP is a water contaminant resulting from the manufacture of the chemical warfare agent GB. To determine its potential contribution to human exposure, its dermal penetration was assessed in swine. Pigs received a single dermal application of 14C-labeled DIMP at one of three exposure levels, i.e., 400, 40, or 4 micro g/cm2 of skin. Absorption was quantitated by measuring radiocarbon in the urine or feces through 7 days and in tissues collected at necropsy. It was concluded that DIMP is a minimal skin penetrant to pigs and absorption by man would be expected to be less than 10% of a dermal exposure. Absorbed dose would be rapidly metabolized in the body, primarily to isopropyl methyl phosphonic acid, and excreted in the urine within 24 to 48 hours. No bioaccumulation would be anticipated. Significant evaporation from the skin surface would predictably occur within 1 to 3 hours.

  8. 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

  9. Stalagmite Based Reconstruction of Atmospheric Radiocarbon Levels during Deglaciation: Implications for Radiocarbon Calibration

    NASA Astrophysics Data System (ADS)

    Glynn, S.; Southon, J.; Sinha, A.

    2006-12-01

    Radiocarbon measurements on dendrochronologically dated tree rings provide the most definitive record of atmospheric changes in radiocarbon concentration (14C). However, the tree ring portion of the current radiocarbon calibration curve (INTCAL04) only extends to 12.4 thousand years Before Present (kyr BP). Efforts to extend radiocarbon calibration timescale beyond 12.4 kyr BP have focused on using 14C measurements in marine varves, lake sediments, corals, and a floating tree ring sequence, but significant disagreements exist among these marine and terrestrial 14C data sets. Speleothems (e.g., stalagmites), which are secondary calcite deposits, form by slow degassing of CO2 enriched cave waters, and can be used to generate records of past atmospheric 14C concentration. Furthermore, stalagmites can be precisely dated by U-Th, and the stable isotopic composition of carbon and oxygen in stalagmites offer an opportunity to assess the atmospheric 14C variations in terms of regional climate change. However, a necessary pre-requisite in using stalagmites for radiocarbon calibration purposes is to quantify the dead carbon fraction or DCF. The DCF is the fraction of `old'14C-free carbon derived from host limestone rocks that is incorporated in a given stalagmite, and must be corrected for in order to extract a true atmospheric 14C record. Here, we present results of Accelerator Mass Spectrometry (AMS) 14C measurements in a stalagmite recovered from Timta cave in the western Himalayas in India. The absolute ages of this stalagmite are constrained by 24 230Th dates, which show that it grew from 14.5 to 11.5 kyr BP. The comparison between stalagmite 14C ages with the atmospheric 14C values from the tree ring portion of INTCAL 04 curve (11.5 to 12.4 kyr B.P.) suggest a small but variable DCF that ranges from 2% to 6%. We observe a surprisingly strong inverse correlation between δ13C, a proxy for vegetation changes overlying the cave, and the DCF, perhaps due to pH changes in

  10. Late Holocene Radiocarbon Variability in Northwest Atlantic Slope Waters

    SciTech Connect

    Sherwood, O; Edinger, E; Guilderson, T P; Ghaleb, B; Risk, M J; Scott, D B

    2008-08-15

    Deep-sea gorgonian corals secrete a 2-part skeleton of calcite, derived from dissolved inorganic carbon at depth, and gorgonin, derived from recently fixed and exported particulate organic matter. Radiocarbon contents of the calcite and gorgonin provide direct measures of seawater radiocarbon at depth and in the overlying surface waters, respectively. Using specimens collected from Northwest Atlantic slope waters, we generated radiocarbon records for surface and upper intermediate water layers spanning the pre- and post bomb-{sup 14}C eras. In Labrador Slope Water (LSW), convective mixing homogenizes the pre-bomb {Delta}{sup 14}C signature (-67 {+-} 4{per_thousand}) to at least 1000 m depth. Surface water bomb-{sup 14}C signals were lagged and damped (peaking at {approx} +45{per_thousand} in the early 1980s) relative to other regions of the northwest Atlantic, and intermediate water signals were damped further. Off southwest Nova Scotia, the vertical gradient in {Delta}{sup 14}C is much stronger. In surface water, pre-bomb {Delta}{sup 14}C averaged -75 {+-} 5{per_thousand}. At 250-475 m depth, prebomb {Delta}{sup 14}C oscillated quasi-decadally between -80 and -100{per_thousand}, likely reflecting interannual variability in the presence of Labrador Slope Water vs. Warm Slope Water (WSW). Finally, subfossil corals reveal no systematic changes in vertical {Delta}{sup 14}C gradients over the last 1200 years.

  11. 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.

  12. Bomb-curve radiocarbon measurement of recent biologic tissues and applications to wildlife forensics and stable isotope (paleo)ecology

    NASA Astrophysics Data System (ADS)

    Uno, Kevin T.; Quade, Jay; Fisher, Daniel C.; Wittemyer, George; Douglas-Hamilton, Iain; Andanje, Samuel; Omondi, Patrick; Litoroh, Moses; Cerling, Thure E.

    2013-07-01

    Above-ground thermonuclear weapons testing from 1952 through 1962 nearly doubled the concentration of radiocarbon (14C) in the atmosphere. As a result, organic material formed during or after this period may be radiocarbon-dated using the abrupt rise and steady fall of the atmospheric 14C concentration known as the bomb-curve. We test the accuracy of accelerator mass spectrometry radiocarbon dating of 29 herbivore and plant tissues collected on known dates between 1905 and 2008 in East Africa. Herbivore samples include teeth, tusks, soft tissue, hair, and horn. Tissues formed after 1955 are dated to within 0.3-1.3 y of formation, depending on the tissue type, whereas tissues older than ca. 1955 have high age uncertainties (>17 y) due to the Suess effect. 14C dating of tissues has applications to stable isotope (paleo)ecology and wildlife forensics. We use data from 41 additional samples to determine growth rates of tusks, molars, and hair, which improve interpretations of serial stable isotope data for (paleo)ecological studies. 14C dating can also be used to calculate the time interval represented in periodic histological structures in dental tissues (i.e., perikymata), which in turn may be used as chronometers in fossil teeth. Bomb-curve 14C dating of confiscated animal tissues (e.g., ivory statues) can be used to determine whether trade of the item is legal, because many Convention of International Trade of Endangered Species restrictions are based on the age of the tissue, and thus can serve as a powerful forensic tool to combat illegal trade in animal parts.

  13. Bomb-curve radiocarbon measurement of recent biologic tissues and applications to wildlife forensics and stable isotope (paleo)ecology.

    PubMed

    Uno, Kevin T; Quade, Jay; Fisher, Daniel C; Wittemyer, George; Douglas-Hamilton, Iain; Andanje, Samuel; Omondi, Patrick; Litoroh, Moses; Cerling, Thure E

    2013-07-16

    Above-ground thermonuclear weapons testing from 1952 through 1962 nearly doubled the concentration of radiocarbon ((14)C) in the atmosphere. As a result, organic material formed during or after this period may be radiocarbon-dated using the abrupt rise and steady fall of the atmospheric (14)C concentration known as the bomb-curve. We test the accuracy of accelerator mass spectrometry radiocarbon dating of 29 herbivore and plant tissues collected on known dates between 1905 and 2008 in East Africa. Herbivore samples include teeth, tusks, soft tissue, hair, and horn. Tissues formed after 1955 are dated to within 0.3-1.3 y of formation, depending on the tissue type, whereas tissues older than ca. 1955 have high age uncertainties (>17 y) due to the Suess effect. (14)C dating of tissues has applications to stable isotope (paleo)ecology and wildlife forensics. We use data from 41 additional samples to determine growth rates of tusks, molars, and hair, which improve interpretations of serial stable isotope data for (paleo)ecological studies. (14)C dating can also be used to calculate the time interval represented in periodic histological structures in dental tissues (i.e., perikymata), which in turn may be used as chronometers in fossil teeth. Bomb-curve (14)C dating of confiscated animal tissues (e.g., ivory statues) can be used to determine whether trade of the item is legal, because many Convention of International Trade of Endangered Species restrictions are based on the age of the tissue, and thus can serve as a powerful forensic tool to combat illegal trade in animal parts. PMID:23818577

  14. Bomb-curve radiocarbon measurement of recent biologic tissues and applications to wildlife forensics and stable isotope (paleo)ecology

    PubMed Central

    Uno, Kevin T.; Quade, Jay; Fisher, Daniel C.; Wittemyer, George; Douglas-Hamilton, Iain; Andanje, Samuel; Omondi, Patrick; Litoroh, Moses; Cerling, Thure E.

    2013-01-01

    Above-ground thermonuclear weapons testing from 1952 through 1962 nearly doubled the concentration of radiocarbon (14C) in the atmosphere. As a result, organic material formed during or after this period may be radiocarbon-dated using the abrupt rise and steady fall of the atmospheric 14C concentration known as the bomb-curve. We test the accuracy of accelerator mass spectrometry radiocarbon dating of 29 herbivore and plant tissues collected on known dates between 1905 and 2008 in East Africa. Herbivore samples include teeth, tusks, soft tissue, hair, and horn. Tissues formed after 1955 are dated to within 0.3–1.3 y of formation, depending on the tissue type, whereas tissues older than ca. 1955 have high age uncertainties (>17 y) due to the Suess effect. 14C dating of tissues has applications to stable isotope (paleo)ecology and wildlife forensics. We use data from 41 additional samples to determine growth rates of tusks, molars, and hair, which improve interpretations of serial stable isotope data for (paleo)ecological studies. 14C dating can also be used to calculate the time interval represented in periodic histological structures in dental tissues (i.e., perikymata), which in turn may be used as chronometers in fossil teeth. Bomb-curve 14C dating of confiscated animal tissues (e.g., ivory statues) can be used to determine whether trade of the item is legal, because many Convention of International Trade of Endangered Species restrictions are based on the age of the tissue, and thus can serve as a powerful forensic tool to combat illegal trade in animal parts. PMID:23818577

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

    SciTech Connect

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

    2009-11-02

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

  17. 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.

  18. Focal cerebral ischaemia in the rat: 2. Regional cerebral blood flow determined by (14C)iodoantipyrine autoradiography following middle cerebral artery occlusion

    SciTech Connect

    Tamura, A.; Graham, D.I.; McCulloch, J.; Teasdale, G.M.

    1981-01-01

    Local cerebral blood flow has been measured by quantitative autoradiography, employing (14C)iodoantipyrine as tracer, in rats killed half an hour after occlusion of the middle cerebral artery. The results were compared with pattern of local cerebral blood flow (CBF) in sham-operated rats and with neuropathological findings. In every animal there was a profound reduction (to 13% of control levels)in blood flow in the neocortex previously by the occluded artery. The level of blood flow in the areas in which ischaemic brain damage occurred was 0.24 +/- 0.03 ml g-1 min-1 (mean +/- SEM). this level of CBF is considerably greater than that reported following a similar surgical procedure in cats and primates. Moderate reductions in blood flow were also seen outside the territory of the occluded artery and in parts of the opposite hemisphere. Absolute increases in blood flow (hyperaemia) were seen only in the substantia nigra and globus pallidus ipsilateral to the occlusion. It is of the middle cerebral artery are reflections of alterations in neuronal function and metabolic activity secondary to the ischaemic lesion.

  19. The impact of soil organic matter and soil sterilisation on the bioaccessibility of 14C-azoxystrobin determined by desorption kinetics.

    PubMed

    Clegg, Helen; Riding, Matthew J; Oliver, Robin; Jones, Kevin C; Semple, Kirk T

    2014-08-15

    As soils represent a major sink for most pesticides, factors influencing pesticide degradation are essential in identifying their potential environmental risk. Desorption of (14)C-azoxystrobin was investigated over time in two soils under sterile and non-sterile conditions using exhaustive (solvent) and non-exhaustive (aqueous) methods. Desorption data were fitted to a two-compartment model, differentiating between fast and slow desorbing fractions. With increased ageing, rapid desorption (Frap) (bioaccessibility) decreased with corresponding increases in slowly desorbing fractions (F(slow)). The rapid desorption rate constant (k(fast)) was not affected by ageing, sterility or extraction solvent. The non-exhaustive extractions had similar desorption profiles; whereas exhaustive extractions in aged soils had the highest F(rap). In non-sterile soil, F(rap) was lower resulting in higher F(slow), while desorption rates remained unaffected. Organic matter (OM) reduces F(rap); but not desorption rates. Microorganisms and OM enhanced ageing effects, reducing the fraction of fast desorbing chemicals and potentially the bioaccessibility of pesticides in soil. PMID:24997252

  20. Calibration of the radiocarbon time scale at 37ka BP

    SciTech Connect

    Southon, J.R.; Deino, A.L.; Orsi, G.

    1995-12-01

    Results from radiocarbon and U-Th measurements on corals have provided a radiocarbon calibration beyond the range covered by tree ring series, but the uncertainties in the measurements beyond 20ka BP are very large. We have obtained new calibration data from radiocarbon dates on material associated with the catastrophic Campanian Ignimbrite eruption from the Phlegrean Fields near Naples. The eruption has been well dated by {sup 40}Ar/{sup 39}Ar to 37ka BP. Radiocarbon measurements were carried out on charcoal from a carbonized branch exposed within the ignimbrite tuff on the wall of an active quarry. The sample was split and analyzed at both the Naples and Lawrence Livermore AMS facilities. The offset between the Ar-Ar data and the radiocarbon results (recalculated using the true 5730-year half life for {sup 14}C) is consistent with predictions from paleomagnetic data and carbon cycle modeling.

  1. 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.

  2. Enzymatic method for the synthesis of (/sup 14/C)pyridoxal 5-phosphate from (/sup 14/C)pyridoxine

    SciTech Connect

    Yagi, T.; Takasugi, M.; Yamamoto, S.; Nozaki, M.

    1986-10-01

    A new enzymatic method for the synthesis of (/sup 14/C)pyridoxal 5-phosphate is presented. (/sup 14/C)Pyridoxal 5'-phosphate was synthesized from (/sup 14/C)pyriodoxine through the successive actions of pyridoxal kinase and pyrdoxamine 5'-phosphate oxidase in a reaction mixture containing ATP, (/sup 14/C)pyridoxine, and both enzymes. (/sup 14/C)Pyridoxal 5'-phosphate was isolated by omega-aminohexyl-Sepharose 6B column chromatography. The overall yield of the product was more than 60%, starting from 550 nmol of (/sup 14/C)pyridoxine. The radiochemical purity of the products, as determined by thin-layer and ion-exchange chromatography, was greater than 98%.

  3. Chlorophyll a-specific Δ14C, δ13C and δ15N values in stream periphyton: implications for aquatic food web studies

    NASA Astrophysics Data System (ADS)

    Ishikawa, N. F.; Yamane, M.; Suga, H.; Ogawa, N. O.; Yokoyama, Y.; Ohkouchi, N.

    2015-11-01

    Periphytic algae attached to a streambed substrate (periphyton) are an important primary producer in stream ecosystems. We determined the isotopic composition of chlorophyll a in periphyton collected from a stream flowing on limestone bedrock in the Seri River, central Japan. Stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) and natural radiocarbon abundances (Δ14C) were measured in chlorophyll a (δ13Cchl, δ15Nchl and Δ14Cchl) and bulk (δ13Cbulk, δ15Nbulk and Δ14Cbulk) for periphyton, a pure aquatic primary producer (Cladophora sp.) and a terrestrial primary producer (Quercus glauca). Periphyton δ13Cbulk and δ13Cchl values did not necessarily correspond to δ13Cbulk for an algal-grazing specialist (Epeorus latifolium). Periphyton Δ14Cchl values (-258 ‰ in April and -190 ‰ in October) were slightly lower than Δ14Cbulk values (-228 ‰ in April and -179 ‰ in October) but were close to the Δ14C value for dissolved inorganic carbon (DIC; -217 ± 31 ‰), which is a mixture of weathered carbonates (Δ14C = -1000 ‰), CO2 derived from aquatic and terrestrial organic matters (variable Δ14C) and dissolved atmospheric CO2 (Δ14C approximately +30 ‰ in 2013). Δ14Cchl values were also close to Δ14Cbulk for E. latifolium (-215 ‰ in April and -199 ‰ in October) and Cladophora sp. (-210 ‰), whereas the Δ14Cbulk value for Q. glauca (+27 ‰) was closer to Δ14C for atmospheric CO2. Although the bulk isotopic composition of periphyton is recognised as a surrogate for the photosynthetic algal community, natural periphyton is a mixture of aquatic and terrestrial organic materials. Our results indicate that the bulk periphyton matrix at the study site consists of 89 to 95 % algal carbon (derived from 14C-depleted DIC) and 5 to 11 % terrestrial organic carbon (derived from 14C-enriched atmospheric CO2).

  4. 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.

  5. Radiocarbon in dissolved organic carbon of the Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Druffel, E. R. M.; Griffin, S.; Coppola, A. I.; Walker, B. D.

    2016-05-01

    Marine dissolved organic carbon (DOC) is produced in the surface ocean though its radiocarbon (14C) age in the deep ocean is thousands of years old. Here we show that ≥10% of the DOC in the deep North Atlantic is of postbomb origin and that the 14C age of the prebomb DOC is ≥4900 14C year, ~900 14C year older than previous estimates. We report 14C ages of DOC in the deep South Atlantic that are intermediate between values in the North Atlantic and the Southern Ocean. Finally, we conclude that prebomb DOC 14C ages are older and a portion of deep DOC is more dynamic than previously reported.

  6. Sea Water Radiocarbon Evolution in the Gulf of Alaska: 2002 Observations

    SciTech Connect

    Guilderson, T P; Roark, E B; Quay, P D; Flood-Page, S R; Moy, C

    2005-04-08

    Oceanic uptake and transport of bomb radiocarbon as {sup 14}CO{sub 2} created by atmospheric nuclear weapons testing in the 1950s and 1960s has been a useful diagnostic to determine the carbon transfer between the ocean and atmosphere. In addition, the distribution of radiocarbon in the ocean can be used as a tracer of oceanic circulation. Results obtained from samples collected in the Gulf of Alaska in the summer of 2002 provide a direct comparison with results in the 1970s during GEOSECS and in the early 1990s during WOCE. The open gyre values are 20-40{per_thousand} more negative than those documented in 1991 and 1993 (WOCE) although the general trends as a function of latitude are reproduced. Surface values are still significantly higher than pre-bomb levels ({approx}-105{per_thousand} or lower). In the central gyre, we observe {Delta}{sup 14}C-values that are lower in comparison to GEOSECS (stn 218) and WOCE P16/P17 to a density of {approx}26.8{sigma}t. This observation is consistent with the overall decrease in surface {Delta}{sup 14}C values, and reflects the erosion of the bomb-{sup 14}C transient. We propose that erosion of the bomb-{sup 14}C transient is accomplished by entrainment of low {sup 14}C water via vertical exchange within the Gulf of Alaska and replenishment of surface and sub-thermocline waters with waters derived from the far northwest Pacific.

  7. Observation of 23 Supernovae that Exploded <300 pc from Earth During the Past 300 kyr in the Radiocarbon and 10Be Cosmogenic Isotope Record

    NASA Astrophysics Data System (ADS)

    Firestone, R. B.

    2014-12-01

    The global excess radiocarbon abundance record for the past 50 kyr can be entirely explained by the explosion of four supernovae 44, 37, 32, and 22 kyr ago less than 250 pc from Earth. Each supernova left a nearly identical signature beginning with a sudden increase at the time of the explosion, followed by a hiatus of 1500 years, and continuing with a sustained, 2000 year increase in radiocarbon from gamma rays produced by diffusive shock in the supernova remnant. For the past 18 kyr excess radiocarbon from SN22kyrBP, identified as the Vela supernova, has decayed with the 5700 year half-life of 14C. The absolute scale for radiocarbon abundance has been determined from the decay curve as Δ14C=5±2% in 1950. Small oscillations in the decay curve are shown to coincide with variations in Earth's Virtual Axial Dipole Moment (VADM). SN44kyrBP exploded approximately 110 pc from Earth doubling the radiocarbon abundance. These supernovae are confirmed in the 10Be, 26Al, 36Cl and nitrate geological records. An additional 19 supernovae are observed 50-300 kyr ago in the 10Be record. Using the Earth as a calorimeter I have determined that approximated 2×1049 ergs were released at the time of each supernova explosion and 1049-50 ergs afterwards, consistent with theoretical predictions. The background rate of radiocarbon productions from more distant sources was determined as 1.61 atoms/cm2s at the top of the atmosphere. Although little danger to life on Earth is expected from these supernovae, each of the recent events were shown to correlate with concurrent global warming of 3-4°C.

  8. RADIOCARBON MEASUREMENTS ON PM-2.5 AMBIENT AEROSOL

    EPA Science Inventory

    Radiocarbon (14C) measurements provide an estimate of the fraction of carbon in a sample that is biogenic. The methodology has been extensively used in past wintertime studies to quantify the contribution of wood smoke to ambient aerosol. In summertime such measurements can p...

  9. VOC RADIOCARBON MEASUREMENTS DURING SCOS97 AND EMISSIONS INVENTORY VALIDATION

    EPA Science Inventory

    Radiocarbon (14C) measurements provide an estimate of the fraction of carbon in a sample that is biogenic. In September 1997 during SCOS97 a series of 3-h canister samples of ambient air were collected at the Azusa air monitoring station during morning and afternoon periods. ...

  10. 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

  11. 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

  12. Chlorophyll a specific Δ14C, δ13C and δ15N values in stream periphyton: implications for aquatic food web studies

    NASA Astrophysics Data System (ADS)

    Ishikawa, N. F.; Yamane, M.; Suga, H.; Ogawa, N. O.; Yokoyama, Y.; Ohkouchi, N.

    2015-07-01

    We determined the isotopic composition of chlorophyll a in periphytic algae attached to a streambed substrate (periphyton). The samples were collected from a stream flowing on limestone bedrock in the Seri River, central Japan. Stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) and natural radiocarbon abundances (Δ14C) were measured in chlorophyll a (δ13Cchl, δ15Nchl and Δ14Cchl) and bulk (δ13Cbulk, δ15Nbulk and Δ14Cbulk) for periphyton, pure aquatic primary producer (Cladophora sp.) and terrestrial primary producer (Quercus glauca). Periphyton δ13Cbulk and δ13Cchl values did not necessarily correspond to δ13Cbulk for an algal-grazing specialist (Mayfly larva, Epeorus latifolium), suggesting that periphyton δ13C values do not faithfully trace carbon transfer between primary producers and primary consumers. Periphyton Δ14Cchl values (-258 ‰ in April and -190 ‰ in October) were slightly lower than Δ14Cbulk values (-228 ‰ in April and -179 ‰ in October), but were close to the Δ14C value for dissolved inorganic carbon (DIC) (-217 ± 31 ‰), which is a mixture of weathered carbonates (Δ14C = -1000 ‰) and dissolved atmospheric CO2 (Δ14C approximately +30 ‰ in 2013). Δ14Cchl values were also close to Δ14Cbulk for E. latifolium (-215 ‰ in April and -199 ‰ in October) and Cladophora sp. (-210 ‰), whereas the Δ14Cbulk value for Q. glauca (+27 ‰) was closer to Δ14C for atmospheric CO2. Although the bulk isotopic composition of periphyton is recognised as a surrogate for the photosynthetic algal community, natural periphyton is a mixture of aquatic and terrestrial organic materials. Our results indicate that the bulk periphyton matrix at the study site consists of 89 to 95 % algal carbon (derived from 14C-depleted DIC) and 5 to 11 % terrestrial organic carbon (derived from 14C-enriched atmospheric CO2).

  13. Single-stage accelerator mass spectrometer radiocarbon-interference identification and positive-ionisation characterisation

    NASA Astrophysics Data System (ADS)

    Wilcken, K. M.; Freeman, S. P. H. T.; Xu, S.; Dougans, A.

    2013-01-01

    A single-stage accelerator mass spectrometer (SSAMS) is a good alternative to conventional spectrometers based on tandem electrostatic acceleration for radiocarbon measurement and permits experimentation with both negative and positive carbon ions. However, such 14C AMS of either polarity ions is limited by an interference. In the case of anion acceleration we have newly determined this to be summed 13C and 16O by improvising an additional Wien filter on our SSAMS deck. Also, 14C AMS might be improved by removing its dependency on negative-ionisation in a sputter ion source. This requires negative-ionisation of sample atoms elsewhere to suppress the 14N interference, which we accomplish by transmitting initially positive ions through a thin membrane. The ionisation dependence on ion-energy is found to be consistent with previous experimentation with vapours and thicker foils.

  14. Fate of (/sup 14/C)xanthotoxin (8-methoxypsoralen) in a goat and in bovine ruminal fluid

    SciTech Connect

    Ivie, G.W.; Beier, R.C.; Bull, D.L.; Oertli, E.H.

    1986-04-01

    A lactating Nubian goat was treated with (/sup 14/C)xanthotoxin, a photosensitizing psoralen that occurs naturally in some phototoxic range plants, as a single oral dose equivalent to 10.0 mg of xanthotoxin/kg of body weight. The radiochemical was rapidly absorbed, metabolized, and excreted. Although expired air was not monitored for the presence of volatile radiocarbon, the data indicated that greater than 50% of the administered (/sup 14/C)xanthotoxin was metabolized by cleavage of the O-(/sup 14/C)methyl moiety, with subsequent loss of the label as, presumably, (/sup 14/C)CO/sub 2/. Studies with bovine ruminal fluid in vitro indicated that cleavage of the O-methyl moiety of xanthotoxin could occur rapidly in the rumen. In the goat, nonmetabolized xanthotoxin was not excreted in urine, and of several metabolites in urine extracts, 3 were identified as resulting from opening of the furan or lactone ring. Only about 2% of the dose was recovered in the feces, and this consisted mainly of unmetabolized xanthotoxin. Although appreciable amounts of radiocarbon were secreted into milk, this radiocarbon was not in the form of xanthotoxin or any identifiable metabolites. The radiocarbon in milk likely resulted from the biosynthetic incorporation of (/sup 14/C)CO/sub 2/ into normal milk components.

  15. Insights into soil carbon dynamics across climatic and geologic gradients from time-series and fraction-specific radiocarbon analysis

    NASA Astrophysics Data System (ADS)

    van der Voort, Tessa Sophia; Hagedorn, Frank; Zell, Claudia; McIntyre, Cameron; Eglinton, Tim

    2016-04-01

    Understanding the interaction between soil organic matter (SOM) and climatic, geologic and ecological factors is essential for the understanding of potential susceptibility and vulnerability to climate and land use change. Radiocarbon constitutes a powerful tool for unraveling SOM dynamics and is increasingly used in studies of carbon turnover. The complex and inherently heterogeneous nature of SOM renders it challenging to assess the processes that govern SOM stability by solely looking at the bulk signature on a plot-scale level. This project combines bulk radiocarbon measurements on a regional-scale spanning wide climatic and geologic gradients with a more in-depth approach for a subset of locations. For this subset, time-series and carbon pool-specific radiocarbon data has been acquired for both topsoil and deeper soils. These well-studied sites are part of the Long-Term Forest Ecosystem Research (LWF) program of the Swiss Federal Institute for Forest, Snow and Landscape research (WSL). Statistical analysis was performed to examine relationships of radiocarbon signatures with variables such as temperature, precipitation and elevation. Bomb-curve modeling was applied determine carbon turnover using time-series data. Results indicate that (1) there is no significant correlation between Δ14C signature and environmental conditions except a weak positive correlation with mean annual temperature, (2) vertical gradients in Δ14C signatures in surface and deeper soils are highly similar despite covering disparate soil-types and climatic systems, and (3) radiocarbon signatures vary significantly between time-series samples and carbon pools. Overall, this study provides a uniquely comprehensive dataset that allows for a better understanding of links between carbon dynamics and environmental settings, as well as for pool-specific and long-term trends in carbon (de)stabilization.

  16. Calibration of radiocarbon dates: tables based on the consensus data of the workshop on calibrating the radiocarbon time scale

    SciTech Connect

    Klein, J.; Lerman, J.C.; Damon, P.E.; Ralph, E.K.

    1982-01-01

    A calibration is presented for conventional radiocarbon ages ranging from 10 to 7240 years BP and thus covering a calendric range of 8000 years from 6050 BC to AD 1950. Distinctive features of this calibration include: (1) an improved data set consisting of 1154 radiocarbon measurements on samples of known age, (2) an extended range over which radiocarbon ages may be calibrated (an additional 530 years), (3) separate 95% confidence intervals (in tubular form) for six different radiocarbon uncertainties (20, 50, 100, 150, 200, 300 years), and (4) an estimate of the non-Poisson errors related to radiocarbon determinations, including an estimate of the systematic errors between laboratories.

  17. Radiocarbon Content of Intermediate Waters off West Sumatra During the Last 45,000 Years

    NASA Astrophysics Data System (ADS)

    De Pol-Holz, R.; Mohtadi, M.; Southon, J. R.

    2014-12-01

    Radiocarbon content of intermediate waters originating from the Southern Ocean is held as a likely smoking gun of the events that triggered the atmospheric CO2 rise and its radiocarbon decline during the last glacial-interglacial transition. Late Glacial depleted radiocarbon water masses have been found at intermediate depths off the coast of Baja California, the Galapagos, the Arabian Sea, but not unequivocally elsewhere. Knowing the route of the old water is therefore central for the required mechanistic linkage of Southern Ocean processes and the atmospheric response. A common approach to search for the old water reservoir is the radiocarbon difference between planktonic and benthic foraminifera or 'apparent ventilation age'. Caveats of this approach are due to the fact that it relies strongly on the knowledge of the surface water reservoir age. In this study, we present a high-resolution radiocarbon difference between surface and intermediate depth waters off west Sumatra in the attempt to elucidate a possible route of the old water from its hypothetical source in the high latitudes near Antarctica on its way to the lower latitude sites where it has been observed. Samples come from core SO189-39KL (0°47'S, 99°55'E, 517 m), a 1350 cm hemipelagic sedimentary sequence that spans the last 45,000 years. Radiocarbon determinations were made at centennial time resolution on both planktonic and benthic species. Calibration of the planktonic radiocarbon as age control points allowed us to infer the Δ14C of the intermediate waters. Our results show that throughout the LGM and the entire deglaciation, radiocarbon content of intermediate depths in the area remained with an almost constant age difference with the contemporaneous atmosphere. Unless we have grossly underestimated the local planktonic reservoir age, our results discard this area as a probable route for the spreading of the old water along its way to northern latitudes. In light of recent evidence from the

  18. Simple determination of the CO sub 2 /O sub 2 specificity of Ribulose-1,5-bisphosphate carboxylase/oxygenase by the specific radioactivity of ( sup 14 C) glycerate 3-phosphate

    SciTech Connect

    Genhai Zhu; Jensen, R.G.; Hallick, R.B.; Wildner, G.F. )

    1992-02-01

    A new method is presented for measurement of the CO{sub 2}/O{sub 2} specificity factor of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). The ({sup 14}C)3-phosphoglycerate (PGA) from the Rubisco carboxylase reaction and its dilution by the Rubisco oxygenase reaction was monitored by directly measuring the specific radioactivity of PGA. {sup 14}CO{sub 2} fixation with Rubisco occurred under two reaction conditions: carboxylase with oxygenase with 40 micromolar CO{sub 2} in O{sub 2}-saturated water and carboxylase only with 160 micromolar CO{sub 2} under N{sub 2}. Detection of the specific radioactivity used the amount of PGA as obtained from the peak area, which was determined by pulsed amperometry following separation by high-performance anion exchange chromatography and the radioactive counts of the ({sup 14}C)PGA in the same peak. The specificity factor of Rubisco from spinach (Spinacia oleracea L.) (93 {plus minus} 4), from the green alga Chlamydomonas reinhardtii (66 {plus minus} 1), and from the photosynthetic bacterium Rhodospirillum rubrum (13) were comparable with the published values measured by different methods.

  19. An update on in situ cosmogenic 14C analysis at ETH Zürich

    NASA Astrophysics Data System (ADS)

    Hippe, K.; Kober, F.; Wacker, L.; Fahrni, S. M.; Ivy-Ochs, S.; Akçar, N.; Schlüchter, C.; Wieler, R.

    2013-01-01

    We present the improved performance of the modified in situ cosmogenic 14C extraction system at ETH Zürich. Samples are now processed faster (2 days in total) and are measured with a high analytical precision of usually <2% using the gas ion source of the MICADAS AMS facility. Measurements of the PP-4 standard sample show a good reproducibility and consistency with published values. Procedural blanks are very low at currently ∼4.0 × 10414C atoms. Analyses of samples from a ∼300 year old rock avalanche prove that we can successfully apply in situ14C exposure dating to very young surfaces. Additionally, we present a modified calculation scheme for in situ14C concentrations which differs from that used for conventional radiocarbon dating. This new approach explicitly accounts for the characteristics of in situ14C production.

  20. 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

  1. 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.

  2. A high-resolution record of atmospheric 14C based on Hulu Cave speleothem H82

    NASA Astrophysics Data System (ADS)

    Southon, John; Noronha, Alexandra L.; Cheng, Hai; Edwards, R. Lawrence; Wang, Yongjin

    2012-02-01

    The development of a calibration of atmospheric radiocarbon (∆14C) is a significant scientific goal because it provides the means to link the numerous 14C dated paleoclimate records to a common timescale with absolutely dated records, and thereby improve our understanding the relationships between the carbon cycle and climate change. Currently, few calibration datasets that directly sample the atmospheric 14C reservoir are available beyond the end of the dendro-dated Holocene tree ring record at 12.6 kyr BP (Before 1950 AD). In the absence of suitable true atmospheric records, 14C calibrations beyond this age limit are based largely on marine data, that are complicated by the marine reservoir effect, which may have varied over the glacial cycle. In this paper, we present a high-resolution record of U-Th series and 14C measurements from Hulu Cave speleothem H82, spanning 10.6-26.8 kyr BP. Corrections for detrital 230Th are negligible, and the contribution of 14C-free geologic carbon to the speleothem calcite is small (5-6%) and is stable across major climate shifts. The time series provides a 16 kyr record of atmospheric ∆14C as well as an updated age model for the existing Hulu Cave δ18O record. The 14C data are in good overall agreement with existing marine and terrestrial 14C records, but comparisons with the Cariaco Basin marine ∆14C record through the deglacial interval reveal that the Cariaco reservoir age appears to have varied during parts of the Younger Dryas and Heinrich Stadial 1 cold events. This highlights the importance of developing extended high-resolution marine and terrestrial 14C records as a means of detecting changes in ocean circulation over the glacial cycle.

  3. Bringing AMS radiocarbon into the Anthropocene: Potential and drawbacks in the determination of the bio-fraction in industrial emissions and in carbon-based products

    NASA Astrophysics Data System (ADS)

    Quarta, Gianluca; Ciceri, Giovanni; Martinotti, Valter; D'Elia, Marisa; Calcagnile, Lucio

    2015-10-01

    In the frame of the general efforts to reduce atmospheric CO2 emissions different efforts are being carried out to stimulate the use of non-fossil energy sources and raw materials. Among these a significant role is played by the use of waste in Waste to Energy (WTE) plants. In this case a relevant problem is related to the determination of the proportion between the bio and the fossil derived fraction in CO2 atmospheric emissions since only the share of energy derived from the bio-fraction combustion can be labelled as "renewable". We discuss the potential of radiocarbon in this field by presenting the results of different campaigns carried out by analysing CO2 sampled at the stack of different power plants in Italy with different expected bio-content of the released carbon dioxide. The still open issues related to the calculation procedures and the achievable precision and accuracy levels are discussed.

  4. 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.

  5. Towards constraining the stratosphere-troposphere exchange of radiocarbon: strategies of stratospheric 14CO2 measurements using AirCore

    NASA Astrophysics Data System (ADS)

    Chen, Huilin; Paul, Dipayan; Meijer, Harro; Miller, John; Kivi, Rigel; Krol, Maarten

    2016-04-01

    Radiocarbon (14C) plays an important role in the carbon cycle studies to understand both natural and anthropogenic carbon fluxes, but also in atmospheric chemistry to constrain hydroxyl radical (OH) concentrations in the atmosphere. Apart from the enormous 14C emissions from nuclear bomb testing in the 1950s and 1960s, radiocarbon is primarily produced in the stratosphere due to the cosmogenic production. To this end, better understanding the stratospheric radiocarbon source is very useful to advance the use of radiocarbon for these applications. However, stratospheric 14C observations have been very limited so that there are large uncertainties on the magnitude and the location of the 14C production as well as the transport of radiocarbon from the stratosphere to the troposphere. Recently we have successfully made stratospheric 14C measurements using AirCore samples from Sodankylä, Northern Finland. AirCore is an innovative atmospheric sampling system, which passively collects atmospheric air samples into a long piece of coiled stainless steel tubing during the descent of a balloon flight. Due to the relatively low cost of the consumables, there is a potential to make such AirCore profiling in other parts of the world on a regular basis. In this study, we simulate the 14C in the atmosphere and assess the stratosphere-troposphere exchange of radiocarbon using the TM5 model. The Sodankylä radiocarbon measurements will be used to verify the performance of the model at high latitude. Besides this, we will also evaluate the influence of different cosmogenic 14C production scenarios and the uncertainties in the OH field on the seasonal cycles of radiocarbon and on the stratosphere-troposphere exchange, and based on the results design a strategy to set up a 14C measurement program using AirCore.

  6. The radiocarbon hydroxyl technique

    NASA Technical Reports Server (NTRS)

    Campbell, Malcolm J.; Sheppard, John C.

    1994-01-01

    The Radiocarbon Technique depends upon measuring the rate of oxidation of CO in an essentially unperturbed sample of air. The airborne technique is slightly different. Hydroxyl concentrations can be calculated directly; peroxyl concentrations can be obtained by NO doping.

  7. Analysis and Characterization of Organic Carbon in Early Holocene Wetland Paleosols using Ramped Pyrolysis 14C and Biomarkers

    NASA Astrophysics Data System (ADS)

    Vetter, L.; Schreiner, K. M.; Fernandez, A.; Rosenheim, B. E.; Tornqvist, T. E.

    2014-12-01

    Radiocarbon analyses are a key tool for quantifying the dynamics of carbon cycling and storage in both modern soils and Quaternary paleosols. Frequently, bulk 14C dates of paleosol organic carbon provide ages older than the time of soil burial, and 14C dates of geochemical fractions such as alkali and acid extracts (operationally defined as humic acids) can provide anomalously old ages when compared to coeval plant macrofossil dates. Ramped pyrolysis radiocarbon analysis of sedimentary organic material has been employed as a tool for investigating 14C age spectra in sediments with multiple organic carbon sources. Here we combine ramped pyrolysis 14C analysis and biomarker analysis (lignin-phenols and other cupric oxide products) to provide information on the source and diagenetic state of the paleosol organic carbon. We apply these techniques to immature early Holocene brackish wetland entisols from three sediment cores in southeastern Louisiana, along with overlying basal peats. Surprisingly, we find narrow 14C age spectra across all thermal aliquots from both paleosols and peats. The weighted bulk 14C ages from paleosols and overlying peats are within analytical error, and are comparable to independently analyzed 14C AMS dates from charcoal fragments and other plant macrofossils from each peat bed. Our results suggest high turnover rates of carbon in soils relative to input of exogenous carbon sources. These data raise broader questions about processes within the active soil and during pedogenesis and burial of paleosols that can effectively homogenize radiocarbon content in soils across the thermochemical spectrum. The concurrence of paleosol and peat 14C ages also suggests that, in the absence of peats with identifiable plant macrofossils, ramped pyrolysis 14C analyses of paleosols may be used to provide ages for sea-level indicators.

  8. Blank corrections for ramped pyrolysis radiocarbon dating of sedimentary and soil organic carbon.

    PubMed

    Fernandez, Alvaro; Santos, Guaciara M; Williams, Elizabeth K; Pendergraft, Matthew A; Vetter, Lael; Rosenheim, Brad E

    2014-12-16

    Ramped pyrolysis (RP) targets distinct components of soil and sedimentary organic carbon based on their thermochemical stabilities and allows the determination of the full spectrum of radiocarbon ((14)C) ages present in a soil or sediment sample. Extending the method into realms where more precise ages are needed or where smaller samples need to be measured involves better understanding of the blank contamination associated with the method. Here, we use a compiled data set of RP measurements of samples of known age to evaluate the mass of the carbon blank and its associated (14)C signature, and to assess the performance of the RP system. We estimate blank contamination during RP using two methods, the modern-dead and the isotope dilution method. Our results indicate that during one complete RP run samples are contaminated by 8.8 ± 4.4 μg (time-dependent) of modern carbon (MC, fM ∼ 1) and 4.1 ± 5.5 μg (time-independent) of dead carbon (DC, fM ∼ 0). We find that the modern-dead method provides more accurate estimates of uncertainties in blank contamination; therefore, the isotope dilution method should be used with caution when the variability of the blank is high. Additionally, we show that RP can routinely produce accurate (14)C dates with precisions ∼100 (14)C years for materials deposited in the last 10,000 years and ∼300 (14)C years for carbon with (14)C ages of up to 20,000 years. PMID:25375178

  9. The Distribution Coefficients and Gasification Ratios of [1,2-{sup 14}C] Sodium Acetate for Various Paddy Soils in Japan

    SciTech Connect

    Ishii, N.; Takeda, H.; Uchida, S.

    2008-07-01

    For appropriate safety assessment of the disposal of TRU waste, distribution coefficients (K{sub d}) and gasification ratios of {sup 14}C labeled [1, 2-{sup 14}C] sodium acetate ({sup 14}C-NaOAc) were determined by batch sorption tests for 85 Japanese paddy soil samples. The soil studied were from four soil types: Andsol; Gley; Gray lowland; and Yellow. The range of K{sub d} values for all soil samples was from 7.5 to 295.2 mL g{sup -1}, and the mean value was 105.6 mL g{sup -1}. This mean value was higher than that of previous study (1). The high K{sub d} values of the present study could be a result of the properties of the paddy soils. The comparison of K{sub d} values by each soil type revealed statistically significant difference between Andsol and Gray lowland soils (P < 0.05). The soil type was one of the factors affecting partitioning of {sup 14}C-NaOAc. Gasification ratios ranged from 29.1% to 83.3%, and its mean value was 66.4% of the total {sup 14}C-NaOAc added. These results suggest that most of the radiocarbon in {sup 14}C-NaOAc will be released from soil into the air as gases. The gasification ratio between soil types was also compared, but no statistically significant difference was found. Gas production may be controlled by other than physicochemical properties of soil, for example by factors such as bacterial community. In addition, both the K{sub d} values and the gasification ratios for Gley soil were decreased according to the increase in pH although the underlaying mechanisms for this observation are not clear. (authors)

  10. Pre to Post-Bomb Seawater 14C History in the Gulf of Alaska Inferred From a Deep Sea Coral: Isididae sp.

    NASA Astrophysics Data System (ADS)

    Roark, B.; Guilderson, T. P.; Fallon, S.; Dunbar, R. B.; McCulloch, M.

    2006-12-01

    Deep-sea corals are an important archive of intermediate and deep-water variability, and provide the means to explore decadal to century-scale ocean dynamics in regions and time periods heretofore unexplored. We present a reconstruction of pre to post-bomb surface and interior water Δ14C based on analysis of deep-sea Isididae (bamboo) corals collected live at ~700 meters in June 2002 at Warwick Seamount, Gulf of Alaska. Concurrent isotope analyses of polyp/tissue and outermost portion of the hard horny proteinaceous gorgonin nodes compared with in situ dissolved inorganic carbon indicates that the gorgonin portion is derived exclusively from recently fixed/exported particulate organic carbon and thus a record of the surface water 14C/12C history. This is in contrast to the carbonate internode portion which is primarily derived from in situ dissolved inorganic carbon, and thus a record of the in situ 14C/12C. Radiocarbon analysis of gorgonin nodal sections captures the surface water D14C evolution. Pre-bomb values are -105‰ reaching a maximum of 100‰ before decreasing to collection values of 20‰. We anticipate that the post-bomb maximum will be in the early 1970s consistent with other mid to high latitude records and that the pre/post bomb transition initiates near 1956. If we utilize the gorgonin pre/post bomb transition as a tie-point and assume a linear growth rate the Isididae used in this study are 75- 125 years old. Carbonate Δ14C shows a 25‰ increase from -215 to -190‰ reflecting the penetration of bomb-14C in the sub-polar North Pacific. To place the carbonate time-series on a fixed timescale we determined the minor element chemistry and tested the inter-species reproducibility. The distribution of Sr is quite homogenous whereas Mg is not with higher Mg concentrations associated with centers of calcification. Age estimates using what appear to be annual Sr/Ca cycles, which we hypothesize are related to biomineralization cycles associated with a

  11. RADIOCARBON MEASUREMENT OF THE BIOGENIC CONTRIBUTION TO SUMMERTIME PM 2.5 AMBIENT AEROSOL IN NASHVILLE, TN

    EPA Science Inventory

    Radiocarbon (14C) measurements performed on PM-2.5 samples collected near Nashville, TN from June 21 to July 13, 1999, showed high levels of modern carbon, ranging from 56 to 80% of the total carbon in the samples. Radiocarbon measurements performed on dichloromethane extracts of...

  12. Time since death and decay rate constants of Norway spruce and European larch deadwood in subalpine forests determined using dendrochronology and radiocarbon dating

    NASA Astrophysics Data System (ADS)

    Petrillo, Marta; Cherubini, Paolo; Fravolini, Giulia; Marchetti, Marco; Ascher-Jenull, Judith; Schärer, Michael; Synal, Hans-Arno; Bertoldi, Daniela; Camin, Federica; Larcher, Roberto; Egli, Markus

    2016-03-01

    100 years in larch CWD. Consequently, the decay of Picea abies and Larix decidua is very low. Several uncertainties, however, remain: 14C dating of CWD from decay classes 4 and 5 and having a pre-bomb age is often difficult (large age range due to methodological constraints) and fall rates of both European larch and Norway spruce are missing.

  13. Radiocarbon dating and compositional analysis of pre-Columbian human bones

    NASA Astrophysics Data System (ADS)

    Andrade, E.; Solís, C.; Canto, C. E.; de Lucio, O. G.; Chavez, E.; Rocha, M. F.; Villanueva, O.; Torreblanca, C. A.

    2014-08-01

    Analysis of ancient human bones found in "El Cóporo", an archaeological site in Guanajuato, Mexico; were performed using a multi techniques scheme: 14C radiocarbon dating, IBA (Ion Beam Analysis), SEM-EDS (Scanning Electron Microscope Energy Dispersive X-ray Spectroscopy). We measured the elemental composition of the bones, especially some with a superficial black pigmentation. Soil samples collected from the burial place were also analyzed. The 14C dating was performed with a new High Voltage Europe 1 MV Tandentron Accelerator Mass Spectrometer (AMS) recently installed in the IFUNAM (Instituto de Física, Universidad Nacional Autónoma de México). The radiocarbon dating allowed us to determine the date of death of the individual in a period between the year 890 and 975 AD, which is consistent with the late period of the Cóporo civilization. The element sample analysis of bones with the surface black pigmentation show higher levels of Fe, Mn and Ba compared when bone's black surface was mechanically removed. These three elements were found in soil samples from the skeleton burial place. These results indicate more likely that the bone black coloration is due to a postmortem alteration occurring in the burial environment.

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

    SciTech Connect

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

    2006-01-13

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

  15. Radiocarbon dating of open systems with bomb effect

    SciTech Connect

    McKay, C.P.; Long, A.; Friedmann, E.I.

    1986-03-10

    The application of radiocarbon dating is extended to include systems that are slowly exchanging carbon with the atmosphere. Simple formulae are derived that relate the true age and the exchange rate of carbon to the apparent radiocarbon age. A radiocarbon age determination does not give a unique true age and exchange rate but determines a locus of values bounded by a minimum age and a minimum exchange rate. It is found that for radiocarbon ages as large as 10,000 years it is necessary to correct for the anthropogenic radiocarbon produced in the atmosphere by nuclear weapons testing. A one-term exponential approximation, with an e-folding time of 14.43 years, is used to model this effect and is shown to be accurate to within 3% for exchange time constants of 100 years and greater. The approach developed here is not specific to radiocarbon and can be applied to other radioisotopes in open systems.

  16. Radiocarbon dating of open systems with bomb effect

    NASA Technical Reports Server (NTRS)

    Mckay, C. P.; Long, A.; Friedmann, E. I.

    1986-01-01

    The application of radiocarbon dating is extended to include systems that are slowly exchanging carbon with the atmosphere. Simple formulae are derived that relate the true age and the exchange rate of carbon to the apparent radiocarbon age. A radiocarbon age determination does not give a unique true age and exchange rate but determines a locus of values bounded by a minimum age and a minimum exchange rate. It is found that for radiocarbon ages as large as 10,000 years it is necessary to correct for the anthropogenic radiocarbon produced in the atmosphere by nuclear weapons testing. A one-term exponential approximation, with an e-folding time of 14.43 years, is used to model this effect and is shown to be accurate to within 3 percent for exchange time constants of 100 years and greater. The approach developed here is not specific to radiocarbon and can be applied to other radioisotopes in open systems.

  17. 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

  18. Radiocarbon-based assessments of the role of fungal species in decomposition

    NASA Astrophysics Data System (ADS)

    Treseder, K. K.; Lansing, J. L.; Choi, N.

    2004-12-01

    We used natural radiocarbon signatures to determine if species of decomposer fungi specialize on different pools of organic matter in the soil. Specifically, we examined natural radiocarbon signatures of mushrooms to estimate the average integrated age of C compounds metabolized by individual species. This method takes advantage of rapid changes in atmospheric radiocarbon signatures of carbon dioxide since the early 1960s, when several years of above-ground weapons testing produced a spike in atmospheric Δ 14C. This signature has been rapidly declining since then. Therefore, we can measure radiocarbon signatures of tissues and determine the time at which their component C was originally photosynthesized. We conducted our study in a fire chronosequence in boreal forests near Delta Junction, Alaska. The chronosequence includes sites burned in severe fires during the summers of 1999, 1987, and 1956. A "control" site was established in a neighboring 80 yr old black spruce forest. In 2002, we collected mushrooms each week from six 50 m long transects in each site. Mushrooms were weighed and assigned to species based on morphological and molecular analyses (i.e. typing by restriction fragment length polymorphism). Saprotrophic species could be distinguished from ectomycorrhizal species based on 15N and 13C signatures. Specifically, saprotrophic mushrooms had δ 15N values less than 4.66\\permil and δ 13C values greater than -23.1\\permil. We then measured the Δ 14C values of mushrooms from 20 of the most abundant saprotrophic species. Radiocarbon signatures varied widely among species, implying that species take up C from compounds that range in turnover time. For example, fungi of the Polyporaceae often grow on woody debris in our sites, and their Δ 14C signatures (-65.1 to 15.0\\permil) indicate the use of several decades-old, recalcitrant C. These fungi are known to possess the necessary enzymes for lignin degradation, so lignocellulose is a likely C source. In

  19. 14-C-NAPHTHYL, 14-C-METHYL AND 14-C-CARBONYL CARBARYL DISTRIBUTION IN THE PREGNANT MOUSE AND RAT

    EPA Science Inventory

    The distribution of carbaryl labeled with 14C in the ring, methyl or carbonyl groups was determined in pregnant mice and rats. Three identical concurrent experiments were performed using each of the three radiolabeled compounds in each of the species so that the different moietie...

  20. Rapid increase in cosmogenic 14C in AD 775 measured in New Zealand kauri trees indicates short-lived increase in 14C production spanning both hemispheres

    NASA Astrophysics Data System (ADS)

    Güttler, D.; Adolphi, F.; Beer, J.; Bleicher, N.; Boswijk, G.; Christl, M.; Hogg, A.; Palmer, J.; Vockenhuber, C.; Wacker, L.; Wunder, J.

    2015-02-01

    In 2012, Miyake et al. reported a sudden and strong increase of the atmospheric radiocarbon (14C) content in Japanese cedar trees of 1.2% between AD 774 and 775. While their findings were quickly confirmed by a German oak chronology for the Northern Hemisphere (NH), the question remained if the effect was seen in both hemispheres. Here we present the first annually resolved Southern Hemisphere (SH) 14C record spanning the interval AD 760-787, using New Zealand kauri (Agathis australis) chronology wood. An almost identical distinct increase compared to Northern Hemisphere data was observed, suggesting a cosmic event with globally uniform impact as a potential cause for the increase. Deploying a carbon cycle box model a worldwide averaged net 14C production of 2.2 ×108 14C atoms cm-2 was estimated, which is 3.7 times higher than the average annual 14C production. The immediate appearance of the event in tree rings on both hemispheres suggests a short duration event of significantly less than 1 yr.

  1. Detection of radiocarbon in the cyclotrino

    SciTech Connect

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

    1990-04-01

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

  2. 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

  3. 14C Activity and Global Carbon Cycle Changes over the Past 50,000 Years

    NASA Astrophysics Data System (ADS)

    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.

  4. Changes in Atmospheric 14C Between 55 and 42 ky BP Recorded in a Stalagmite From Socotra Island, Indian Ocean

    NASA Astrophysics Data System (ADS)

    Weyhenmeyer, C. E.; Burns, S. J.; Fleitmann, D.; Kramers, J. D.; Matter, A.; Waber, H. N.; Reimer, P. J.

    2003-12-01

    A record of atmospheric radiocarbon (14C) variations for a part of the last glacial period was obtained from a 1.7 m long stalagmite, M1-2, from Socotra Island in the Indian Ocean. The stalagmite radiocarbon values were corrected for 14C-free carbon added by water-rock interaction (dead carbon fraction), by using del 13C values of the calcite as a constraint. An age-depth model was developed from 25 high-precision U/Th measurements. The base of the stalagmite dates to 54.7 ky BP and it stopped growing around 42.2 ky BP. The difference between U/Th and 14C ages shows a smooth, steady increase from about 5,000 years at the base of the stalagmite to about 8,000 years at its top. Correspondingly, Delta 14C values increase from 500 per mil to about 1300 per mil, which indicates that concentrations of atmospheric 14C steadily increased between 55 and 42 yr BP. The record from Socotra Island does not show the large and rapid D14C changes previously recorded in a stalagmite from the Bahamas (Beck et al, Science 2001). The D14C values estimated from M1-2 are significantly higher than those estimated from a marine 14C record (foraminifera) from Cariaco Basin for the same time period (Hughen et al. in prep). In the latter, D14C values decrease to near 0 at about 44 ky BP. The most likely reason for this discrepancy are the two different time scales used; the Cariaco Basin is matched to the GISP2 timescale, which is approximately 5000 years younger than indicated by the stalagmite U/Th chronology (Burns et al, Science 2003). When the Cariaco basin record is adjusted to the M1-2 timescale, the D14C values for both datasets are similar.

  5. Impact of the Bohunice Nuclear Power Plant on atmospheric radiocarbon.

    PubMed

    Povinec, P P; Sivo, A; Simon, J; Holý, K; Chudý, M; Richtáriková, M; Morávek, J

    2008-11-01

    Radiocarbon variations in the atmospheric CO(2) have been observed at two localities in Slovakia (Bratislava and Zlkovce). Zlkovce is situated about 60 km NE from Bratislava, and only 5 km from the Bohunice Nuclear Power Plant (NPP). The observed Delta(14)C levels provide a unique evidence of the long-term impact of the Bohunice NPP on the Bratislava region, as well as on the decreased fossil fuel CO(2) emissions. The radiation doses estimated to the local public have been around 3 microSv/year, 20% of the dose from global fallout (14)C present in the environment. PMID:18534859

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

    USGS Publications Warehouse

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

    2010-01-01

    Mollusk shells provide brief (<5 yr per shell) records of past marine conditions, including marine radiocarbon reservoir age (R) and upwelling. We report 21 14C ages and R calculations on small (~2 mg) samples from 2 Mesodesma donacium (surf clam) shells. These shells were excavated from a semi-subterranean house floor stratum 14C dated to 7625 ?? 35 BP at site QJ-280, Quebrada Jaguay, southern Peru. The ranges in marine 14C ages (and thus R) from the 2 shells are 530 and 170 14C yr; R from individual aragonite samples spans 130 ?? 60 to 730 ?? 170 14C yr. This intrashell 14C variability suggests that 14C dating of small (time-slice much less than 1 yr) marine samples from a variable-R (i.e. variable-upwelling) environment may introduce centuries of chronometric uncertainty. ?? 2010 by the Arizona Board of Regents on behalf of the University of Arizona.

  7. The radiocarbon budget for Mono Lake: an unsolved mystery

    USGS Publications Warehouse

    Broecker, W.S.; Wanninkhof, R.; Mathieu, G.; Peng, T.-H.; Stine, S.; Robinson, S.; Herczeg, A.; Stuiver, M.

    1988-01-01

    Since 1957 the 14C C ratio of the dissolved inorganic carbon in Mono Lake has risen by about 60???. The magnitude of this increase is about four times larger than that expected from the invasion of bomb-produced 14C from the atmosphere. We have eliminated the following explanations: (1) measurement error, (2) an unusually high physical exchange rate for non-reactive gases, (3) inorganic enhancement of the CO2 exchange rate, and (4) biological enhancement of the CO2 exchange rate. Clandestine disposal of waste radiocarbon remains a dark-horse explanation. In the course of our investigations we have uncovered evidence for at least one episodic input of radiocarbon-free carbon to the lake over the last 1000 years. We speculate that this injection was related to a hydrothermal event resulting from sublacustrine volcanic activity. ?? 1988.

  8. Challenges faced when using radiocarbon measurements to estimate fossil fuel emissions in the UK.

    NASA Astrophysics Data System (ADS)

    Wenger, A.; O'Doherty, S.; Rigby, M. L.; Ganesan, A.; Manning, A.; Allen, G.

    2015-12-01

    Estimating the anthropogenic component of carbon dioxide emissions from direct atmospheric measurements is difficult, due to the large natural carbon dioxide fluxes. One way of determining the fossil fuel component of atmospheric carbon dioxide is the use of radiocarbon measurements. Whilst carbon reservoirs with a reasonably fast carbon exchange rate all have a similar radiocarbon content, fossil fuels are completely devoid of radiocarbon due to their age. Previous studies have 14CO2 (UK) this approach is compromised by the high density of 14CO2 emitting nuclear power plants. Of the 16 nuclear reactors in the UK, 14 are advanced gas cooled reactors, which have one of the highest 14CO2 emission rates of all reactor types. These radiocarbon emissions not only lead to a serious underestimation of the recently added fossil fuel CO2, by masking the depletion of 14C in CO2, but can in fact overshadow the depletion by a factor of 2 or more. While a correction for this enhancement can be applied, the emissions from the nuclear power plants are highly variable, and an accurate correction is therefore not straightforward. We present the first attempt to quantify UK fossil fuel CO2 emissions through the use of 14CO2. We employ a sampling strategy that makes use of a Lagrangian particle dispersion model, in combination with nuclear industry emission estimates, to forecast "good" sampling times, in an attempt to minimize the correction due to emissions from the nuclear industry. As part of the Greenhouse gAs Uk and Global Emissions (GAUGE) project, 14CO2measurements are performed at two measurement sites in the UK and Ireland, as well as during science flights around the UK. The measurement locations have been chosen with a focus on high emitting regions such as London and the Midlands. We discuss the unique challenges that face the determination of fossil fuel emissions through radiocarbon measurements in the UK and our sampling strategy to deal with them. In addition we

  9. 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.

  10. Very long solar periods and the radiocarbon record

    NASA Technical Reports Server (NTRS)

    Sonett, C. P.

    1984-01-01

    It is pointed out that radiocarbon is produced in the earth's atmosphere by the nuclear reaction N-14(n,p)C-14. The photosynthesis by trees of carbon in the form of CO2 provides an estimate of the C-14/C-12 ratio and, therefore, the atmospheric inventory of C-14 at the time of take-up. The existence of periodicities in the radiocarbon record has been considered by Suess (1965, 1971, 1980). The present investigation is concerned with these periodicities. Periodicities in the radiocarbon record are related to variability in the modulation of the galactic component of the incoming cosmic ray flux, mediated by the oceanic and atmospheric reservoirs. The long periods observed are an indicator of corresponding changes in the hydromagnetic output of the sun, which might be caused by changes in the intensity of the magnetic field escaping from the solar atmosphere.

  11. Radiocarbon Dating: An Annotated Bibliography.

    ERIC Educational Resources Information Center

    Fortine, Suellen

    This selective annotated bibliography covers various sources of information on the radiocarbon dating method, including journal articles, conference proceedings, and reports, reflecting the most important and useful sources of the last 25 years. The bibliography is divided into five parts--general background on radiocarbon, radiocarbon dating,…

  12. Methane sources in gas hydrate-bearing cold seeps: Evidence from radiocarbon and stable isotopes

    USGS Publications Warehouse

    Pohlman, J.W.; Bauer, J.E.; Canuel, E.A.; Grabowski, K.S.; Knies, D.L.; Mitchell, C.S.; Whiticar, Michael J.; Coffin, R.B.

    2009-01-01

    Fossil methane from the large and dynamic marine gas hydrate reservoir has the potential to influence oceanic and atmospheric carbon pools. However, natural radiocarbon (14C) measurements of gas hydrate methane have been extremely limited, and their use as a source and process indicator has not yet been systematically established. In this study, gas hydrate-bound and dissolved methane recovered from six geologically and geographically distinct high-gas-flux cold seeps was found to be 98 to 100% fossil based on its 14C content. Given this prevalence of fossil methane and the small contribution of gas hydrate (??? 1%) to the present-day atmospheric methane flux, non-fossil contributions of gas hydrate methane to the atmosphere are not likely to be quantitatively significant. This conclusion is consistent with contemporary atmospheric methane budget calculations. In combination with ??13C- and ??D-methane measurements, we also determine the extent to which the low, but detectable, amounts of 14C (~ 1-2% modern carbon, pMC) in methane from two cold seeps might reflect in situ production from near-seafloor sediment organic carbon (SOC). A 14C mass balance approach using fossil methane and 14C-enriched SOC suggests that as much as 8 to 29% of hydrate-associated methane carbon may originate from SOC contained within the upper 6??m of sediment. These findings validate the assumption of a predominantly fossil carbon source for marine gas hydrate, but also indicate that structural gas hydrate from at least certain cold seeps contains a component of methane produced during decomposition of non-fossil organic matter in near-surface sediment.

  13. Uptake and distribution of 14C during and following exposure to [14C]methyl isocyanate.

    PubMed

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

    1988-06-15

    Guinea pigs were exposed to [14C]methyl isocyanate (14CH3-NCO, 14C 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 14C. Clearance of 14C was then gradual over a period of 3 days. Similarly 14C 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 14C uptake in blood indicating that most of the 14C MIC uptake in normal guinea pigs occurred from retention of this agent in the upper respiratory tract passages. In exposed guinea pigs 14C was distributed to all examined tissues. In pregnant female mice similarly exposed to 14C MIC, 14C was observed in all tissues examined following exposure including the uterus, placenta, and fetus. While the form of 14C 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. PMID:3376108

  14. Variability in 14C contents of soil organic matter at the plot and regional scale across climatic and geologic gradients

    NASA Astrophysics Data System (ADS)

    van der Voort, Tessa Sophia; Hagedorn, Frank; McIntyre, Cameron; Zell, Claudia; Walthert, Lorenz; Schleppi, Patrick; Feng, Xiaojuan; Eglinton, Timothy Ian

    2016-06-01

    Soil organic matter (SOM) forms the largest terrestrial pool of carbon outside of sedimentary rocks. Radiocarbon is a powerful tool for assessing soil organic matter dynamics. However, due to the nature of the measurement, extensive 14C studies of soil systems remain relatively rare. In particular, information on the extent of spatial and temporal variability in 14C contents of soils is limited, yet this information is crucial for establishing the range of baseline properties and for detecting potential modifications to the SOM pool. This study describes a comprehensive approach to explore heterogeneity in bulk SOM 14C in Swiss forest soils that encompass diverse landscapes and climates. We examine spatial variability in soil organic carbon (SOC) 14C, SOC content and C : N ratios over both regional climatic and geologic gradients, on the watershed- and plot-scale and within soil profiles. Results reveal (1) a relatively uniform radiocarbon signal across climatic and geologic gradients in Swiss forest topsoils (0-5 cm, Δ14C = 130 ± 28.6, n = 12 sites), (2) similar radiocarbon trends with soil depth despite dissimilar environmental conditions, and (3) micro-topography dependent, plot-scale variability that is similar in magnitude to regional-scale variability (e.g., Gleysol, 0-5 cm, Δ14C 126 ± 35.2, n = 8 adjacent plots of 10 × 10 m). Statistical analyses have additionally shown that Δ14C signature in the topsoil is not significantly correlated to climatic parameters (precipitation, elevation, primary production) except mean annual temperature at 0-5 cm. These observations have important consequences for SOM carbon stability modelling assumptions, as well as for the understanding of controls on past and current soil carbon dynamics.

  15. Large Variations of Atmospheric 14C Associated With Dansgaard-Oeschger Cycles 10- 13

    NASA Astrophysics Data System (ADS)

    Weyhenmeyer, C. E.; Burns, S. J.; Fleitmann, D.; Mangini, A.; Matter, A.; Guilderson, T.; Reimer, P. J.

    2006-12-01

    A 1.7 m long stalagmite from Moomi Cave, Socotra Island in the Indian Ocean provides a continuous, high- resolution record of climate change between 53 and 41 kyr BP. In the northern high-latitude regions, this time period is characterized by several rapid climate change events, corresponding to Dansgaard-Oeschger (D/O) cycles 10-13. It has been suggested that these D/O cycles may be global events but high-resolution data from the low-latitude regions are scarce. As a result, the driving and feedback mechanisms of these rapid changes remain poorly understood. The presented stalagmite data of U/Th, stable isotopes (del 18O, del 13C) and radiocarbon (14C) provide unique information regarding the nature and timing of rapid climate changes in the tropics. A depth-age model for the Moomi Cave stalagmite was developed from 25 high-precision U/Th measurements, providing a solid chronology for this record. Oxygen isotope measurements of the stalagmite calcite reveal several large variations that are believed to reflect changes in the amount of precipitation, rather than temperature. A comparison to the Greenland Ice Core records shows a remarkable similarity to D/O cycles 10- 13 with warmer periods in the high-latitude regions being associated with increased precipitation in the tropics and vice versa. The stalagmite radiocarbon (14C) values from over 100 individual measurements reveal an almost identical cyclic pattern, tracing all four D/O cycles. Assuming no changes in the carbonate chemistry of the precipitating fluid, the radiocarbon values of the stalagmite calcite directly reflect changes in global atmospheric 14C concentrations. There are three possible explanations for these cyclic variations of 14C values: 1) changes in the carbonate chemistry of the drip water resulting in changes of the dead carbon fraction (DCF); 2) changes in the solar activity and/or Earth's magnetic field resulting in direct variations of atmospheric 14C concentrations; and 3) changes in

  16. 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.

  17. Surface water processes in the Indonesian Throughflow as documented by a high-resolution coral (Delta)14C record

    SciTech Connect

    Fallon, S J; Guilderson, T P

    2008-04-23

    To explore the seasonal to decadal variability in surface water masses that contribute to the Indonesian Throughflow we have generated a 115-year bi-monthly coral-based radiocarbon time-series from a coral in the Makassar Straits. In the pre-bomb (pre-1955) era from 1890 to 1954, the radiocarbon time series occasionally displays a small seasonal signal (10-15{per_thousand}). After 1954 the radiocarbon record increases rapidly, in response to the increased atmospheric {sup 14}C content caused by nuclear weapons testing. From 1957 to 1986 the record displays clear seasonal variability from 15 to 60{per_thousand} and the post-bomb peak (163 per mil) occurred in 1974. The seasonal cycle of radiocarbon can be attributed to variations of surface waters passing through South Makassar Strait. Southern Makassar is under the influence of the Northwest Monsoon, which is responsible for the high Austral summer radiocarbon (North Pacific waters) and the Southeast Monsoon that flushes back a mixture of low (South Pacific and upwelling altered) radiocarbon water from the Banda Sea. The coral record also shows a significant {sup 14}C peak in 1955 due to bomb {sup 14}C water advected into this region in the form of CaCO{sub 3} particles (this implies that the particles were advected intact and then become entrapped in the coral skeleton--is this what we really mean? Wouldn't even fine particles settle out over the inferred transit time from Bikini to MAK?) or water particles with dissolved labeled CO{sub 2} produced during fallout from the Castle tests in 1954.

  18. 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.

  19. 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.

  20. 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.

  1. Radiocarbon in the Weddell Sea as observed in a deep-sea coral and in krill

    SciTech Connect

    Michel, R.L.; Druffel, E.M.

    1983-03-01

    Radiocarbon mesurements were performed on krill and coral samples collected from the Weddell Sea during IWSOE '80. These are the first radiocarbon measurements available from this area since 1973. These data reveal carbon-14 levels for Weddell surface water and southern Weddell Shelf water. These data indicate that the radiocarbon levels in surface waters in 1980 were the same or slightly lower than those present in 1973. In addition, an unusually low ..delta../sup 14/C value for shelf water (from coral) at 500 m is evidence that Warm Deep Water (WDW) may penetrate much further and more frequently onto the shelf region than had previously been expected.

  2. Wine ethanol 14C as a tracer for fossil fuel CO2 emissions in Europe: Measurements and model comparison

    NASA Astrophysics Data System (ADS)

    Palstra, Sanne W. L.; Karstens, Ute; Streurman, Harm-Jan; Meijer, Harro A. J.

    2008-11-01

    14C (radiocarbon) in atmospheric CO2 is the most direct tracer for the presence of fossil-fuel-derived CO2 (CO2-ff). We demonstrate the 14C measurement of wine ethanol as a way to determine the relative regional atmospheric CO2-ff concentration compared to a background site ("regional CO2-ff excess") for specific harvest years. The carbon in wine ethanol is directly back traceable to the atmospheric CO2 that the plants assimilate. An important advantage of using wine is that the atmosphere can be monitored annually back in time. We have analyzed a total of 165 wines, mainly from harvest years 1990-1993 and 2003-2004, among which is a semicontinuous series (1973-2004) of wines from one vineyard in southwest Germany. The results show clear spatial and temporal variations in the regional CO2-ff excess values. We have compared our measured regional CO2-ff excess values of 2003 and 2004 with those simulated by the REgional MOdel (REMO). The model results show a bias of almost +3 parts per million (ppm) CO2-ff compared with those of the observations. The modeled differences between 2003 and 2004, however, which can be used as a measure for the variability in atmospheric mixing and transport processes, show good agreement with those of the observations all over Europe. Correcting for interannual variations using modeled data produces a regional CO2-ff excess signal that is potentially useful for the verification of trends in regional fossil fuel consumption. In this fashion, analyzing 14C from wine ethanol offers the possibility to observe fossil fuel emissions back in time on many places in Europe and elsewhere.

  3. 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

  4. Radiocarbon evidence for a smaller oceanic carbon dioxide sink than previously believed

    NASA Astrophysics Data System (ADS)

    Hesshaimer, Vago; Heimann, Martin; Levin, Ingeborg

    1994-07-01

    RADIOCARBON produced naturally in the upper atmosphere or arti-ficially during nuclear weapons testing is the main tracer used to validate models of oceanic carbon cycling, in particular the exchange of carbon dioxide with the atmosphere1-3 and the mixing parameters within the ocean itself4-7. Here we test the overall consistency of exchange fluxes between all relevant compartments in a simple model of the global carbon cycle, using measurements of the long-term tropospheric CO2 concentration8 and radiocarbon composition9-12, the bomb 14C inventory in the stratosphere13,14 and a compilation of bomb detonation dates and strengths15. We find that to balance the budget, we must invoke an extra source to account for 25% of the generally accepted uptake of bomb 14C by the oceans3. The strength of this source decreases from 1970 onwards, with a characteristic timescale similar to that of the ocean uptake. Significant radiocarbon transport from the remote high stratosphere and significantly reduced uptake of bomb 14C by the biosphere can both be ruled out by observational constraints. We therefore conclude that the global oceanic bomb 14C inventory should be revised downwards. A smaller oceanic bomb 14C inventory also implies a smaller oceanic radiocarbon penetration depth16, which in turn implies that the oceans take up 25% less anthropogenic CO2 than had previously been believed.

  5. Geomagnetic field intensity, North Atlantic Deep Water circulation and atmospheric Δ 14C during the last 50 kyr

    NASA Astrophysics Data System (ADS)

    Laj, Carlo; Kissel, Catherine; Mazaud, Alain; Michel, Elisabeth; Muscheler, Raimund; Beer, Juerg

    2002-06-01

    We present simulated records of past changes in the atmospheric Δ 14C for the last 50 kyr due to changes in geomagnetic field intensity and in the strength of the North Atlantic Deep Water (NADW). A new geomagnetic record was used, largely based on the NAPIS-75 record [Laj et al., Phil. Trans. R. Soc. London A 358 (2000) 1009-1025] which has been extended for the 0-20 kyr interval using archeomagnetic and volcanic data. Past changes of the NADW were derived from a mineral magnetic study of the cores used in the construction of NAPIS-75. Two box models of different complexity (4 and 17 boxes) were used to simulate the carbon cycle. Calculated records of Δ 14C are consistent with experimental determinations for the last 24 kyr. For older ages, the records calculated with variable oceanic circulation conditions reach values as high as 600‰ (with an average of 500‰) between 20 and 40 kyr with maxima around 21, 30 and 38 kyr (GISP2 age model), while low values are observed prior to 42 kyr. Although large inconsistencies in experimental data preclude precise comparison, the average record simulated with the 17-box model is overall consistent with the Icelandic Sea record [Voelker et al., Radiocarbon 40 (1998) 517-534; 42 (2000) 437-452], except for the extremely high peak observed in this record at 40.5 kyr. On the other hand, the results recently reported from a stalagmite recovered from a submerged cave in the Bahamas [Beck et al., Science 292 (2001) 2453-2458] are inconsistent with all our model simulations. In the 20-45 kyr interval, the improved geomagnetic record combined with the new NADW profile allows us to give a modeled evaluation of the relative contribution of these factors to changes in atmospheric Δ 14C. The average simulation provides a first order modeled correction for conventional radiocarbon ages older than 25 kyr for which no calibration curve is available as yet.

  6. A procedure for batch separation of sup 14 C-hexose from sup 14 C-sucrose

    SciTech Connect

    Tarpley, L.; Vietor, D.M. )

    1991-05-01

    This presentation describes a method for separating {sup 14}C-hexose from {sup 14}C-sucrose in extracts of plant tissue. Portions of ethanol extracts are treated with activated charcoal in microcentrifuge tubes. Aliquots are removed, ethanol evaporated and replaced with reaction mixture that phosphorylates hexose (HEPPS, K{sub 2}HPO{sub 4}, Mg(C{sub 2}H{sub 3}O{sub 2}){sub 2}, ovalbumen, Na{sub 2}ATP, yeast hexokinase). After a time course, the hexokinase reaction is stopped (slowed considerably) to minimize effects of contamination enzyme activities. The stopping agent used is lyxose, a nonphosphorylable analogue of glucose. The strong anionic charge of phosphate introduced through the hexokinase action results in binding (> 95%) of hexose-phosphate to anion-exchange resin. Sucrose remains unbound (> 95%) in solution. This batch ion-exchange is performed in microcentrifuge tubes to allow many samples to be processed simultaneously. Recovery of radiolabel in extracts is complete (99%), and determinations are repeatable (cv = 23%). This method for routinely separating and quantifying {sup 14}C-hexose and {sup 14}C-sucrose in plant tissue extracts can contribute to the economy and feasibility of studies of {sup 14}C-photoassimilate partitioning to soluble sugars within and among plant tissues.

  7. Efficient Collection of Methane from Extremely Large Volumes of Water for Natural Radiocarbon Analysis

    NASA Astrophysics Data System (ADS)

    Sparrow, K. J.; Kessler, J. D.

    2014-12-01

    Collecting sufficient amounts of natural methane sample for a high precision radiocarbon (14C-CH4) analysis was previously unfeasible when sampling from low methane concentration waters like the open ocean. A new method incorporating dissolved gas extraction technology (Liqui-Cel® membrane contactors) has been developed to circumvent the challenges that natural 14C-CH4 sampling presents. With this method, adequate amounts of methane-carbon for a traditional 14C-accelerator mass spectrometry (AMS) analysis can be cleanly and efficiently extracted from 1000s L water in a few hours. This technique is currently being improved to enable sampling from > 11,000 L water in less than 1 hr. For transport from the field to the laboratory, each extracted gas sample is compressed into a small (1.68 L) high-pressure aluminum cylinder using an oil-free compressor pump. Due to the small size and portability of the sample cylinders, high resolution sampling plans composed of 30+ samples are possible even in remote locations. The laboratory preparation of these methane samples for 14C-AMS analyses is carried out on a new flow-through vacuum line. While the bulk water vapor and carbon dioxide (CO2) are removed before the sample is compressed in the field, the residual trace amounts of these constituents are cryogenically removed from the sample in the initial phase of the vacuum line. Carbon monoxide in the sample is quantitatively oxidized at 290°C to CO2 and cryogenically removed. Finally, the sample methane is quantitatively oxidized at 950°C to products CO2 and water and then cryogenically isolated. The new vacuum line technique achieves low blanks and purifies and oxidizes the methane contained in the extracted gas sample with high efficiency. At an AMS facility, an aliquot of the methane-produced CO2 is graphitized and analyzed for radiocarbon content using traditional 14C-AMS. Supporting dual-inlet isotope ratio mass spectrometry measurements are conducted to determine both

  8. Linking high resolution 14C records to ice core time scales by means of Bayesian wiggle-matching

    NASA Astrophysics Data System (ADS)

    Adolphi, F.; Muscheler, R.; Friedrich, M.; Güttler, D.; Wacker, L.; Kromer, B.

    2014-12-01

    Radiocarbon dating is the key method for obtaining chronological information of paleoclimate records covering the last ~45,000 years. The wealth of paleoclimatic information reconstructed from Greenland and Antarctic ice cores are often used as blue-prints to place these radiocarbon dated records into a wider context. However, while layer counted ice core time scales from Greenland provide high precision on the duration of events, the absolute age uncertainty increases back in time. This poses limitations on the possible detail and robustness of comparisons between radiocarbon dated, and ice core records. Cosmogenic radionuclide records, i.e. based on 14C and 10Be, provide a unique tool for synchronizing different time scales from various archives. They carry the common production rate signal which is modulated by variations in the strength of the helio- and geo- magnetic fields, which are climate-independent processes and global. We will present a method for synchronizing radiocarbon and Greenland ice core time scales back to 16,000 years ago based on Bayesian wiggle matching of cosmogenic radionuclide records. The method utilizes the strength of the high relative precision of ice core time scales as well as the small absolute age uncertainty from tree-ring chronologies and U/Th dated speleothems. The method provides combined error estimates and allows testing i) the accuracy of ice core time scales, ii) the quality of 14C records underlying the radiocarbon calibration curve as well as iii) assumptions of synchronicity of rapid climate changes. Furthermore, we will illustrate how this method can be used for high-precision radiocarbon wiggle-match dating of floating tree ring chronologies beyond 14,000 years ago, and potentially improve the radiocarbon calibration curve.

  9. Radiocarbon signal of a low and intermediate level radioactive waste disposal facility in nearby trees.

    PubMed

    Janovics, R; Kelemen, D I; Kern, Z; Kapitány, S; Veres, M; Jull, A J T; Molnár, M

    2016-03-01

    Tree ring series were collected from the vicinity of a Hungarian radioactive waste treatment and disposal facility and from a distant control background site, which is not influenced by the radiocarbon discharge of the disposal facility but it represents the natural regional (14)C level. The (14)C concentration of the cellulose content of tree rings was measured by AMS. Data of the tree ring series from the disposal facility was compared to the control site for each year. The results were also compared to the (14)C data of the atmospheric (14)C monitoring stations at the disposal facility and to international background measurements. On the basis of the results, the excess radiocarbon of the disposal facility can unambiguously be detected in the tree from the repository site. PMID:26704325

  10. IntCal04: A New Consensus Radiocarbon Calibration Dataset from 0-26 ka BP

    NASA Astrophysics Data System (ADS)

    Reimer, P. J.; Baillie, M. G.; Bard, E.; Beck, J. W.; Buck, C. E.; Blackwell, P. G.; Burr, G. S.; Cutler, K. B.; Damon, P. E.; Edwards, R. L.; Fairbanks, R. G.; Friedrich, M.; Guilderson, T. P.; Hogg, A. G.; Hughen, K. A.; Kromer, B.; McCormac, G.; Ramsey, C. B.; Reimer, R. W.; Remmele, S.; Southon, J. R.; Stuiver, M.; Taylor, F. W.; van der Plicht, J.; Weyhenmeyer, C. E.

    2003-12-01

    Because atmosphere 14C levels have not been constant through time, it is necessary to calibrate radiocarbon dates with known age radiocarbon datasets in order to compare paleorecords based on 14C ages and those based on other timescales. The need for a consensus calibration dataset was acknowledged by the radiocarbon community as a way of preventing confusion and the subjective use of selected datasets (1). Since then, radiocarbon calibration datasets have been developed by international collaborations and presented for ratification at the International Radiocarbon Conference (2-4). The IntCal04 Radiocarbon Calibration/Comparison Working Group has put together a dataset which incorporates existing and new measurements of tree-ring records, foraminifera from varved sediments, and corals that meet a strict set of acceptance criteria (5). Uncertainties for both the calendar time scale and the radiocarbon ages have been quantified and included in the dataset combination using a statistical technique based on the ideas of Christen and Nicholls (6) and Gomez Portugal Aguilar (7). The IntCal04 dataset, which covers the range of 0 to 26 ka BP, was presented for ratification at the 19th International Radiocarbon Conference in Wellington, New Zealand, in September, 2003. This paper will highlight the differences between IntCal98 and the new IntCal04 dataset and give an example showing the effect on the calibrated age for a Younger Dryas age sample. 1. J. Klein, J. C. Lerman, P. E. Damon, E. K. Ralph, Radiocarbon 24, 103-150 (1982). 2. M. Stuiver, Radiocarbon 28, R2-R2 (1986). 3. M. Stuiver et al., Radiocarbon 40, 1041-1083 (1998). 4. M. Stuiver, P. J. Reimer, Radiocarbon 35, 215-230 (1993). 5. P. J. Reimer et al., Radiocarbon 44, 653-661. (2002). 6. J. A. Christen, G. Nicholls, "Random-walk radiocarbon calibration." (Mathematics Department, University of Auckland, 2000). 7.D. G. P. Aguilar, C. D. Litton, A. O'Hagan, Radiocarbon 44, 195-212 (2002).

  11. 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.

  12. Coral radiocarbon constraints on the source of the Indonesian throughflow

    SciTech Connect

    Moore, M.D.; Schrag, D.P.; Kashgarian, M.

    1997-06-01

    Radiocarbon variability in {ital Porites} spp. corals from Guam and the Makassar Strait (Indonesian Seaway) was used to identify the source waters contributing to the Indonesian throughflow. Time series with bimonthly resolution were constructed using accelerator mass spectrometry. The seasonal variability ranges from 15 to 60{per_thousand}, with large interannual variability. {Delta}{sup 14}C values from Indonesia and Guam have a nearly identical range. Annual mean {Delta}{sup 14}C values from Indonesia are 50 to 60{per_thousand} higher than in corals from Canton in the South Equatorial Current [{ital Druffel}, 1987]. These observations support a year-round North Pacific source for the Indonesian throughflow and imply negligible contribution by South Equatorial Current water. The large seasonality in {Delta}{sup 14}C values from both sites emphasizes the dynamic behavior of radiocarbon in the surface ocean and suggests that {Delta}{sup 14}C time series of similar resolution can help constrain seasonal and interannual changes in ocean circulation in the Pacific over the last several decades.{copyright} 1997 American Geophysical Union

  13. Radiocarbon Dating the Anthropocene

    NASA Astrophysics Data System (ADS)

    Chaput, M. A.; Gajewski, K. J.

    2015-12-01

    The Anthropocene has no agreed start date since current suggestions for its beginning range from Pre-Industrial times to the Industrial Revolution, and from the mid-twentieth century to the future. To set the boundary of the Anthropocene in geological time, we must first understand when, how and to what extent humans began altering the Earth system. One aspect of this involves reconstructing the effects of prehistoric human activity on the physical landscape. However, for global reconstructions of land use and land cover change to be more accurately interpreted in the context of human interaction with the landscape, large-scale spatio-temporal demographic changes in prehistoric populations must be known. Estimates of the relative number of prehistoric humans in different regions of the world and at different moments in time are needed. To this end, we analyze a dataset of radiocarbon dates from the Canadian Archaeological Radiocarbon Database (CARD), the Palaeolithic Database of Europe and the AustArch Database of Australia, as well as published dates from South America. This is the first time such a large quantity of dates (approximately 60,000) has been mapped and studied at a global scale. Initial results from the analysis of temporal frequency distributions of calibrated radiocarbon dates, assumed to be proportional to population density, will be discussed. The utility of radiocarbon dates in studies of the Anthropocene will be evaluated and potential links between population density and changes in atmospheric greenhouse gas concentrations, climate, migration patterning and fire frequency coincidence will be considered.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  15. 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.

  16. Coral Radiocarbon Records of Indian Ocean Water Mass Mixing and Wind-Induced Upwelling Along the Coast of Sumatra, Indonesia

    SciTech Connect

    Guilderson, T P; Grumet, N S; Abram, N J; Beck, J W; Dunbar, R B; Gagan, M K; Hantoro, W S; Suwargadi, B W

    2004-02-06

    Radiocarbon ({sup 14}C) in the skeletal aragonite of annually banded corals track radiocarbon concentrations in dissolved inorganic carbon (DIC) in surface seawater. As a result of nuclear weapons testing in the 1950s, oceanic uptake of excess {sup 14}C in the atmosphere has increased the contrast between surface and deep ocean {sup 14}C concentrations. We present accelerator mass spectrometric (AMS) measurements of radiocarbon isotope ({Delta}{sup 14}C) in Porites corals from the Mentawai Islands, Sumatra (0 S, 98 E) and Watamu, Kenya (3 S, 39 E) to document the temporal and spatial evolution of the {sup 14}C gradient in the tropical Indian Ocean. The rise in {Delta}{sup 14}C in the Sumatra coral, in response to the maximum in nuclear weapons testing, is delayed by 2-3 years relative to the rise in coral {Delta}{sup 14}C from the coast of Kenya. Kenya coral {Delta}{sup 14}C values rise quickly because surface waters are in prolonged contact with the atmosphere. In contrast, wind-induced upwelling and rapid mixing along the coast of Sumatra entrains {sup 14}C-depleted water from the subsurface, which dilutes the effect of the uptake of bomb-laden {sup 14}C by the surface-ocean. Bimonthly AMS {Delta}{sup 14}C measurements on the Mentawai coral reveal mainly interannual variability with minor seasonal variability. The interannual signal may be a response to changes in the Walker circulation, the development of easterly wind anomalies, shoaling of the eastern thermocline, and upwelling of {sup 14}C-depleted water along the coast of Sumatra. Singular spectrum analysis of the Sumatra coral {Delta}{sup 14}C record reveals a significant 3-year periodicity. The results lend support to the concept that ocean atmosphere interactions between the Pacific and Indian Oceans operate in concert with the El Ni{tilde n}o-Southern Oscillation (ENSO).

  17. Pre- and post-bomb radiocarbon in fish otoliths

    NASA Astrophysics Data System (ADS)

    Kalish, John M.

    1993-02-01

    Measurements of radiocarbon in seawater dissolved inorganic carbon (DIC), or suitable proxies such as hermatypic corals, are a valuable source of information on carbon flux and ocean circulation. However, knowledge of the global distribution of both pre- and post-bomb radiocarbon is limited due to the sources of these data. Suitable hermatypic corals are restricted to shallow tropical and subtropical waters and oceanographic collections of seawater are prohibitively expensive. What is needed is a proxy for ocean radiocarbon that can be collected at most latitudes and depths, and which can be reliably aged. Here I report accelerator mass spectrometry analyses of radiocarbon from selected regions of fish otoliths and show that such measurements are suitable for determining both pre- and post-bomb radiocarbon in all oceans and at most depths. Radiocarbon data obtained from otoliths can extend our knowledge of carbon flux in the oceans and atmosphere and help to develop further understanding of the fate of atmospheric CO 2 and ocean circulation. The data presented here represent the first pre- and post-bomb time series of radiocarbon levels from temperate waters. Furthermore, I demonstrate that the dramatic increase in radiocarbon in the atmosphere and oceans, attributable to the atmospheric testing of thermonuclear bombs during the 1950's and 1960's, provides a chemical mark on fish otoliths that is suitable for the validation of age in fishes.

  18. Observation-based global biospheric excess radiocarbon inventory 1963-2005

    NASA Astrophysics Data System (ADS)

    Naegler, Tobias; Levin, Ingeborg

    2009-09-01

    For the very first time, we present an observation-based estimate of the temporal development of the biospheric excess radiocarbon (14C) inventory IB14,E, i.e., the change in the biospheric 14C inventory relative to prebomb times (1940s). IB14,E was calculated for the period 1963-2005 with a simple budget approach as the difference between the accumulated excess 14C production by atmospheric nuclear bomb tests and the nuclear industry and observation-based reconstructions of the excess 14C inventories in the atmosphere and the ocean. IB14,E increased from the late 1950s onward to maximum values between 126 and 177 × 1026 atoms 14C between 1981 and 1985. In the early 1980s, the biosphere turned from a sink to a source of excess 14C. Consequently, IB14,E decreased to values of 108-167 × 1026 atoms 14C in 2005. The uncertainty of IB14,E is dominated by uncertainties in the total bomb 14C production and the oceanic excess 14C inventory. Unfortunately, atmospheric Δ14CO2 from the early 1980s lack the necessary precision to reveal the expected small change in the amplitude and phase of atmospheric Δ14C seasonal cycle due to the sign flip in the biospheric net 14C flux during that time.

  19. Comparison of sampling methods for radiocarbon dating of carbonyls in air samples via accelerator mass spectrometry

    NASA Astrophysics Data System (ADS)

    Schindler, Matthias; Kretschmer, Wolfgang; Scharf, Andreas; Tschekalinskij, Alexander

    2016-05-01

    Three new methods to sample and prepare various carbonyl compounds for radiocarbon measurements were developed and tested. Two of these procedures utilized the Strecker synthetic method to form amino acids from carbonyl compounds with either sodium cyanide or trimethylsilyl cyanide. The third procedure used semicarbazide to form crystalline carbazones with the carbonyl compounds. The resulting amino acids and semicarbazones were then separated and purified using thin layer chromatography. The separated compounds were then combusted to CO2 and reduced to graphite to determine 14C content by accelerator mass spectrometry (AMS). All of these methods were also compared with the standard carbonyl compound sampling method wherein a compound is derivatized with 2,4-dinitrophenylhydrazine and then separated by high-performance liquid chromatography (HPLC).

  20. Biological Removal of Radiocarbon-14 from Irradiated Graphite

    SciTech Connect

    Molokwane, P.E.; Chirwa, E.M.N.

    2008-07-01

    This paper reports on the preliminary study on the bioseparation of radiocarbon-14 (C-14) using a mixed-culture of microorganisms. The bioseparation principle is critically analyzed and is benchmarked against existing C-14 separation methods using physical chemical processes. The preliminary study indicated probable bio-separate of C-14 from solution prepared from a nuclear graphite mixture, even though the findings need to be verified. The current experiment consisted of a growth vessel and a bio-filter operated in a closed loop. The bio-filter was not installed for the purpose of treatment but rather as a method of isolation of microorganisms for further processing. Significant amounts of C-14 were detected in the trapped cells in the bio-filter, significantly higher than in controls taken before adding carbon sources containing C-14. The microorganisms were grown under micro-aerobic conditions with graphite carbon and commercially purchased powdered carbon as the predominant supplied carbon sources. Small amounts of sucrose (500 mg/L) were added at 48 hour intervals to maintain culture balance. A proof of concept study is underway to determine the C-14 mass balance, characterize the microorganisms in the reactor, and establish the presence or absence of processes that might have affected the preliminary observations. This research represents an exploration into a new field using a new philosophy for treatment of C-14 in low-level waste. (authors)

  1. Radiocarbon dates on bones of extinct birds from Hawaii

    SciTech Connect

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

    1987-04-01

    Bones from a stratified sedimentary deposit in the Puu Naio Cave site on Maui, Hawaiian Islands, reveal the late Holocene extinction of 19 species of birds. The age of the sediment and associated fauna was determined by direct radiocarbon dating (tandem particle accelerator-mass spectrometer; TAMS) of amino acids extracted from bones weighing as little as 450 mg. The /sup 14/C dates indicate that sediment has been accumulating in the lava tube for at least the last 7750 years, a suitable time frame for testing the hypothesis that Holocene extinction on islands began after human colonization. Despite growing evidence that a worldwide wave of extinctions coincided with human colonization of oceanic islands, little radiometric data have been available to date the extinction of most small fossil vertebrates on islands. The TAMS technique of dating purified collagen from the bones of small vertebrates could lead to vastly improved chronologies of extinction for oceanic islands where catastrophic mid- to late-Holocene extinction is expected or known to have occurred. Chronologies derived from nonarcheological sites that show continuous sedimentation, such as the Puu Naio Cave deposit, may also yield key evidence on the timing of earliest human settlement of Oceania.

  2. 14C AMS measurements of the bomb pulse in N- and S-hemisphere tropical trees

    NASA Astrophysics Data System (ADS)

    Murphy, J. O.; Lawson, E. M.; Fink, D.; Hotchkis, M. A. C.; Hua, Q.; Jacobsen, G. E.; Smith, A. M.; Tuniz, C.

    1997-03-01

    The 14C bomb-pulse signature has been measured by AMS on cross-dateable teak samples from N- and S-hemisphere locations in the tropics. Excellent agreement is found with the atmospheric 14C content in the period 1955 to 1980 for the respective hemispheres. These results demonstrate that 14C measurements can be used to facilitate growth rate determinations in tropical trees.

  3. 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.

  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. Application of 14C analyses to source apportionment of carbonaceous PM 2.5 in the UK

    NASA Astrophysics Data System (ADS)

    Heal, Mathew R.; Naysmith, Philip; Cook, Gordon T.; Xu, Sheng; Duran, Teresa Raventós; Harrison, Roy M.

    2011-05-01

    Determination of the radiocarbon ( 14C) content of airborne particulate matter yields insight into the proportion of the carbonaceous material derived from fossil and contemporary carbon sources. Daily samples of PM 2.5 were collected by high-volume sampler at an urban background site in Birmingham, UK, and the fraction of 14C in both the total carbon, and in the organic and elemental carbon fractions, determined by two-stage combustion to CO 2, graphitisation and quantification by accelerator mass spectrometry. OC and EC content was also determined by Sunset Analyzer. The mean fraction contemporary TC in the PM 2.5 samples was 0.50 (range 0.27-0.66, n = 26). There was no seasonality to the data, but there was a positive trend between fraction contemporary TC and magnitude of SOC/TC ratio and for the high values of these two parameters to be associated with air-mass back trajectories arriving in Birmingham from over land. Using a five-compartment mass balance model on fraction contemporary carbon in OC and EC, the following average source apportionment for the TC in these PM 2.5 samples was derived: 27% fossil EC; 20% fossil OC; 2% biomass EC; 10% biomass OC; and 41% biogenic OC. The latter category will comprise, in addition to BVOC-derived SOC, other non-combustion contemporary carbon sources such as biological particles, vegetative detritus, humic material and tyre wear. The proportion of total PM 2.5 at this location estimated to derive from BVOC-derived secondary organic aerosol was 9-29%. The findings from this work are consistent with those from elsewhere in Europe and support the conclusion of a significant and ubiquitous contribution from non-fossil biogenic sources to the carbon in terrestrial aerosol.

  6. 14C in cropland soil of a long-term field trial - experimental variability and implications for estimating carbon turnover

    NASA Astrophysics Data System (ADS)

    Leifeld, J.; Mayer, J.

    2015-07-01

    Because of their controlled nature, the presence of independent replicates, and their known management history, long-term field experiments are key to the understanding of factors controlling soil carbon. Together with isotope measurements, they provide profound insight into soil carbon dynamics. For soil radiocarbon, an important tracer for understanding these dynamics, experimental variability across replicates is usually not accounted for; hence, a relevant source of uncertainty for quantifying turnover rates is missing. Here, for the first time, radiocarbon measurements of five independent field replicates, and for different layers, of soil from the 66-year-old controlled field experiment ZOFE in Zurich, Switzerland, are used to address this issue. 14C variability was the same across three different treatments and for three different soil layers between the surface and 90 cm depths. On average, experimental variability in 14C content was 12 times the analytical error but still, on a relative basis, smaller than variability in soil carbon concentration. Despite a relative homogeneous variability across the field and along the soil profile, the curved nature of the relationship between radiocarbon content and modelled carbon mean residence time implies that the absolute error of calculated soil carbon turnover time increases with soil depth. In our field experiment findings on topsoil carbon turnover variability would, if applied to subsoil, tend to underweight turnover variability even if experimental variability in the subsoil isotope concentration is the same. Together, experimental variability in radiocarbon is an important component in an overall uncertainty assessment of soil carbon turnover.

  7. Vulcanism and Radiocarbon Dates

    DOE R&D Accomplishments Database

    Libby, L. M.; Libby, W. F.

    1972-10-01

    We consider whether the long term perturbation of radiocarbon dates, which is known to be approximately a sin function of period about 8000 years and amplitude of about 8% peak-to-peak, could have been caused in any major part by vulcanism. We conclude that this is not the case. On the contrary, present day volcanoes are a far less important source of inert CO{sub 2} (about 100 fold less) than is man's burning of fossil fuels which has caused the Suess dilution of about 2%. (auth)

  8. Temporal and spatial variations in bomb-produced radiocarbon along BEAGLE2003 lines—Revisits of WHP P06, A10, and I03/I04 in the Southern Hemisphere Oceans

    NASA Astrophysics Data System (ADS)

    Kumamoto, Yuichiro; Murata, Akihiko; Watanabe, Shuichi; Fukasawa, Masao

    2011-04-01

    Radiocarbon ( 14C) in dissolved inorganic carbon was measured during revisit cruises along World Ocean Circulation Experiment-Hydrographic Programme (WHP) lines A10 in the South Atlantic, I03/I04 in the Indian, and P06 in the South Pacific Oceans from August 2003 to January 2004, during the Blue Earth Global Expedition 2003 (BEAGLE2003). Zonal means of the water-column inventory of bomb-produced 14C in 2003/2004 in the South Atlantic, Indian, and South Pacific Oceans were about 180, 128, and 159 × 10 12 atoms m -2, respectively. The smallest zonal inventory along the I03 line among the three lines was primarily due to a sampling bias, because the I03 line in the Indian Ocean was along 20°S, which is more equatorward than the other two lines along approximately 30°S in the South Atlantic and South Pacific Oceans. The I03 line in the Indian Ocean had the smallest zonal inventory of bomb-produced 14C and the largest of bomb-produced 137Cs, suggesting that the distribution of bomb 14C in the Indian Ocean is determined primarily by the thermocline ventilation within the Indian Ocean. The history of bomb 14C over time suggests that the bomb 14C inventory in the southern subtropical regions increased steadily up to the early 1990s. The rate of increase then slowed between the early 1990s and 2003/2004 because of a decrease in the bomb 14C influx from the atmosphere to the surface ocean. The highest bomb 14C inventory among the southern subtropical regions was in the subtropical Indian Ocean. However, the contribution of the Indonesian throughflow from the North Pacific and Indian Oceans to this large inventory in the Indian Ocean is not clear. The 14C data along the BEAGLE2003 lines in 2003/2004 were compared with those obtained during WHP in the 1990s and during the South Atlantic Ventilation Experiment in the late 1980s. The zonal averages of the decadal changes in 14C revealed that bomb 14C continued to increase between the late 1980s/1990s and 2003/2004 in the

  9. Comparison of Radiocarbon Ages for Multiproxy Paleoclimate Reconstruction of the Great Salt Lake, Utah

    NASA Astrophysics Data System (ADS)

    Nielson, K. E.; Bowen, G. J.; Eglinton, T. I.

    2008-12-01

    Multiproxy paleoclimate reconstructions from high sedimentation-rate systems offer promising opportunities to deconvolve multiple aspects climate system response to past forcing. However, the time-equivalence of proxies must be established before such reconstructions can be usefully interpreted. Differences in source ages, transport pathways, and surface residence times for substrates may lead to differences in lag times between proxy formation and deposition, compromising comparative analysis of data from multiple proxies. We used multi-substrate radiocarbon dating to investigate the potential for multi-proxy reconstruction of Holocene changes in the volume of the Great Salt Lake (GSL), Utah, based on the stable isotope composition of organic and inorganic substrates in lake sediment cores. Among potential substrates for this work are normal alkanes of vascular higher plant and algal origin, fossil cysts of lake-dwelling brine shrimp (Artemia), and micritic aragonite. Radiocarbon ages for all organic substrates (alkanes, cysts) sampled at any given core depth are concordant within analytical uncertainty and are similar to ages determined on land-plant debris and filamentous algae isolated from the sediment. Inorganic carbonate, in contrast, is depleted in 14C compare to the organic proxies, giving ages that were apparently 2000 to 3000 years older, likely due to winnowing and re-deposition of carbonate at the core site. These results suggest that the maximum temporal resolution achievable through analysis of mineral substrates is on the order of several millennia. Although the limited precision of the radiocarbon analysis precludes precise determination of the maximum potential resolution of organic-proxy based climate reconstructions, the relatively high sedimentation rates (50--150 cm/kyr) and age-equivalence of the substrates analyzed implies that sub- centennial scale resolution should be achievable throughout much of the Holocene portion of the GSL

  10. Urinary metabolites of 14C-labeled thyroxine in man

    PubMed Central

    Pittman, Constance S.; Buck, Melvin W.; Chambers, Joseph B.

    1972-01-01

    Studies were carried out to determine the chemical structures of thyroxine metabolites after total deiodination. Normal subjects were given thyroxine labeled with 14C on the nonphenolic ring and the alanine side chain, 8-11 μg/day for 10 days. By paper chromatography of fresh urine, six or more 14C-labeled compounds were separated. The 14C-labeled metabolites were concentrated by passing the urine through a nonionic polymeric adsorbent. Two major thyroxine metabolites were identified. The identification was made by three different methods: (a) chromatography, (b) synthesis of derivatives, and (c) recrystallization to constant specific activity. One 14C-labeled metabolite was identified as thyroacetic acid or 4-phenoxy-(4′-hydroxy) phenyl-acetic acid. Another one was identified as thyronine. Of the total urinary 14C radioactivity, 43.7% was recovered as thyroacetic acid and 19.8% was recovered as thyronine. Approximately one-fifth of each of these metabolites was present in the urine in bound form which released the free metabolites during acid hydrolysis. The average daily excretion of thyroacetic acid was 13.7% of the renal disposal rate of thyroxine, or approximately 7.5 μg/day. The average daily excretion of thyronine was 6.5% of the renal disposal rate of thyroxine or approximately 3.9 μg/day while the urinary iodide made up 64.7% of the renal disposal rate of thyroxine. Our findings provide the needed proof that the major metabolic pathways of thyroxine remove the iodine atoms by substituting hydrogen for iodine and leave the diphenyl ether nucleus intact. PMID:5032524

  11. 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.

  12. Microflora distributions in paleosols: a method for calculating the validity of radiocarbon-dated surfaces

    SciTech Connect

    Mahaney, W.C.; Boyer, M.G.

    1986-08-01

    Microflora (bacteria and fungi) distributions in several paleosols from Mount Kenya, East Africa, provide important information about contamination of buried soil horizons dated by radiocarbon. High counts of bacteria and fungi in buried soils provide evidence for contamination by plant root effects or ground water movement. Profiles with decreasing counts versus depth appear to produce internally consistent and accurate radiocarbon dates. Profiles with disjunct or bimodal distributions of microflora at various depths produce internally inconsistent chronological sequences of radiocarbon-dated buried surfaces. Preliminary results suggest that numbers up to 5 x 10/sup 2/ g/sup -1/ for bacteria in buried A horizons do not appear to affect the validity of /sup 14/C dates. Beyond this threshold value, contamination appears to produce younger dates, the difference between true age and /sup 14/C age increasing with the amount of microflora contamination.

  13. A graphical method to evaluate predominant geochemical processes occurring in groundwater systems for radiocarbon dating

    USGS Publications Warehouse

    Han, Liang-Feng; Plummer, L. Niel; Aggarwal, Pradeep

    2012-01-01

    A graphical method is described for identifying geochemical reactions needed in the interpretation of radiocarbon age in groundwater systems. Graphs are constructed by plotting the measured 14C, δ13C, and concentration of dissolved inorganic carbon and are interpreted according to specific criteria to recognize water samples that are consistent with a wide range of processes, including geochemical reactions, carbon isotopic exchange, 14C decay, and mixing of waters. The graphs are used to provide a qualitative estimate of radiocarbon age, to deduce the hydrochemical complexity of a groundwater system, and to compare samples from different groundwater systems. Graphs of chemical and isotopic data from a series of previously-published groundwater studies are used to demonstrate the utility of the approach. Ultimately, the information derived from the graphs is used to improve geochemical models for adjustment of radiocarbon ages in groundwater systems.

  14. Retrospective study of 14C concentration in the vicinity of NPP Jaslovské Bohunice using tree rings and the AMS technique

    NASA Astrophysics Data System (ADS)

    Ješkovský, Miroslav; Povinec, Pavel P.; Steier, Peter; Šivo, Alexander; Richtáriková, Marta; Golser, Robin

    2015-10-01

    Atmospheric radiocarbon has been monitored around the Nuclear Power Plant (NPP) Jaslovské Bohunice (Slovakia) using CO2 absorption in NaOH solution since 1969. In 2012, tree ring samples were collected from Tilia cordata using an increment borer at Žlkovce monitoring station situated close to the Bohunice NPP. Each tree ring was identified and graphite targets were produced for 14C analysis by accelerator mass spectrometry. The 14C concentrations obtained from the tree-ring samples have been in a reasonable agreement with the averaged annual 14C concentrations in atmospheric CO2.

  15. Radiocarbon evidence for annual growth rings in a deep sea octocoral (Primnoa resedaeformis)

    SciTech Connect

    Sherwood, O A; Scott, D B; Risk, M J; Guilderson, T P

    2005-04-05

    The deep-sea gorgonian octocoral Primnoa resedaeformis is distributed throughout the Atlantic and Pacific Oceans at depths of 65-3200 m. It has a two-part skeleton of calcite and gorgonin. Towards the inside of the axial skeleton gorgonin and calcite are deposited in concentric growth rings, similar to tree rings. Colonies were collected from the Northeast Channel (northwest Atlantic Ocean, southwest of Nova Scotia, Canada) from depths of 250-475 m. Radiocarbon was measured in individual rings isolated from sections of each colony, after dissolution of calcite. Each {Delta}{sup 14}C measurement was paired with a ring age determined by three amateur ring counters. The precision of ring counts averaged better than {+-} 2 years. Accurate reconstruction of 20th century bomb-radiocarbon shows that (1) the growth rings are formed annually, (2) the gorgonin is derived from surface particulate organic matter (POM) and (3) useful environmental data are recorded in the organic endoskeletons of deep-sea octocorals. These results support the use of Primnoa resedaeformis as a long-term, high resolution monitor of surface ocean conditions, particularly in temperate and boreal environments where proxy data are lacking.

  16. Fossil and biogenic CO{sub 2} from waste incineration based on a yearlong radiocarbon study

    SciTech Connect

    Mohn, J.; Szidat, S.; Zeyer, K.; Emmenegger, L.

    2012-08-15

    Highlights: Black-Right-Pointing-Pointer Yearlong radiocarbon study on the share of biogenic CO{sub 2} from waste incineration. Black-Right-Pointing-Pointer Direct approach combining temporal integrating gas sampling and {sup 14}CO{sub 2} analysis by AMS. Black-Right-Pointing-Pointer Significant differences between incinerators with 43% and 54%Fos C. Black-Right-Pointing-Pointer No annual cycle of fossil CO{sub 2} for all, except one, of the included incinerators. - Abstract: We describe the first long-term implementation of the radiocarbon ({sup 14}C) method to study the share of biogenic (%Bio C) and fossil (%Fos C) carbon in combustion CO{sub 2}. At five Swiss incinerators, a total of 24 three-week measurement campaigns were performed over 1 year. Temporally averaged bag samples were analyzed for {sup 14}CO{sub 2} by accelerator mass spectrometry. Significant differences between the plants in the share of fossil CO{sub 2} were observed, with annual mean values from 43.4 {+-} 3.9% to 54.5 {+-} 3.1%. Variations can be explained by the waste composition of the respective plant. Based on our dataset, an average value of 48 {+-} 4%Fos C was determined for waste incineration in Switzerland. No clear annual trend in %Fos C was observed for four of the monitored incinerators, while one incinerator showed considerable variations, which are likely due to the separation and temporary storage of bulky goods.

  17. Characterization of hemoglobin adduct formation in mice and rats after administration of ( sup 14 C)butadiene or ( sup 14 C)isoprene

    SciTech Connect

    Sun, J.D.; Dahl, A.R.; Bond, J.A.; Birnbaum, L.S.; Henderson, R.F. )

    1989-08-01

    Occupational exposures to 1,3-butadiene or isoprene occur through their use in the manufacture of rubber and other related polymer products. The purpose of this study was to determine if butadiene or isoprene administration would result in the formation of adducts with blood hemoglobin (Hb), and if such adducts can be used as a measure of previous exposure(s). Male B6C3F1 mice and male Sprague-Dawley rats were injected intraperitoneally with 1, 10, 100, or 1000 mumol (14C)butadiene or 0.3, 3.0, 300, 1000, or 3000 mumol (14C)isoprene per kilogram body weight. Animals were killed 24 hr later. Globin was isolated from blood samples and was analyzed for 14C by liquid scintillation spectroscopy. Hb adduct formation was linearly related to administered doses up to 100 mumol (14C)butadiene or 500 mumol (14C)isoprene per kilogram body weight for mice and rats, respectively. For (14C)butadiene, the efficiency of Hb adduct formation in mice and rats within the linear response range was 0.177 +/- 0.003 and 0.407 +/- 0.019 (pmol of 14C-adducts/mg globin)/(mumol of retained (14C)butadiene/kg body wt), respectively (mean +/- SE; n = 18). For (14C)isoprene, these values for mice and rats were 0.158 +/- 0.035 and 0.079 +/- 0.016 (pmol of 14C-adducts/mg globin)/(mumol of retained (14C)isoprene/kg body wt), respectively (mean +/- SE; n = 12). Hb adducts also accumulated linearly after repeated daily administration of 100 mumol (14C)butadiene or 500 mumol (14C)isoprene per kilogram body wt to mice and rats, respectively, for 3 days. (14C)Butadiene-derived Hb adducts in blood showed lifetimes of approximately 24 and approximately 65 days for mice and rats, respectively, which correlate with the reported lifetimes for red blood cells in these rodent species. Thus, levels of butadiene- or isoprene-derived adducts on Hb in circulating blood may be a useful measure of prior repeated exposures to these compounds.

  18. Determination of tritium and 14C concentration in two hydrostratigraphic units below the University of California, Davis, waste burial holes at the Laboratory for Energy-Related Health Research/South Campus Disposal Site (LEHR/SCDS).

    PubMed

    Pay, Stephen

    2003-08-01

    The Laboratory for Energy-Related Health Research site at the University of California at Davis was used as a disposal site for tritium and 14C waste generated by campus related research. This low-level radioactive waste was disposed of by shallow land burial from 1956 to 1974 in waste burial holes and resulted in extensive contamination of soils and groundwater at the LEHR/SCDS. In part, due to this contamination, the LEHR/SCDS was placed on the National Priority List in May of 1994. In 1999, soils in the vicinity of the waste burial holes were subject to a CERCLA Removal Action. To this day elevated tritium and 14C concentrations are found in two groundwater monitoring wells that are located down gradient from the waste burial holes. The Bioscreen, Natural Attenuation Decision Support System software program was used, along with site-specific hydrogeologic conditions, to estimate the maximum source zone concentrations in the water bearing intervals below the waste burial holes. The first order decay process, and assumptions of horizontal flow provided reasonably accurate estimates of contaminant concentrations in the unconfined portion of the water bearing interval, but results for the confined portion of the water bearing intervals were mixed. Dose estimates for the time period of maximum contaminant concentration in the aquifer below the waste burial holes, predicted by modeling, suggested that the 4 mrem drinking water standard had not been exceeded at this site. PMID:12865745

  19. Status of mass spectrometric radiocarbon detection at ETHZ

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

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

    SciTech Connect

    Taylor, R.E.

    1991-08-20

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

  1. Radiocarbon pollution and self-purification of humus in chernozems of the East-European plain in 1900-2008

    NASA Astrophysics Data System (ADS)

    Ivanov, I. V.; Khokhlova, O. S.; Galitskii, V. V.; Chichagova, O. A.; Zazovskaya, E. P.

    2012-08-01

    The dynamics of the 14C content in the humus of chernozems in 1900-2008 are considered. The elevated 14C content in the atmosphere because of nuclear weapons tests has led to the contamination of humus with bomb radiocarbon. In 1966-1968, the 14C reserves in the profiles of chernozems exceeded the background ones by 15%; in 1978, by 12%; and, in 1998, by 2%. By the year of 2008, its reserves became equal to the background ones. The 14C distribution along the soil profiles changed. By 1978, the 0- to 30-cm-thick soil layer became free from radiocarbon due to its self-purification; however, at depths of 40-70 and 100-115 cm, its weak accumulation was registered. By 2008, the whole soil profile was free from 14C. The main mechanism of the soil self-purification from radiocarbon is suggested to be the constant substitution of fragments of humus compound structures for those of fresh organic matter entering the soils with the 14C content being in equilibrium with the atmospheric one, i.e., due to the renewal of the carbon in the humus. The rate of the carbon renewal and its migration in the soils are assed based on the 14C concentrations in the humus.

  2. A comparison of the Greenland Ice-Core and IntCal timescales through the Laschamp geomagnetic excursion, utilising new 14c data from Tenaghi Philippon, Greece

    NASA Astrophysics Data System (ADS)

    Staff, Richard A.; Hardiman, Mark; Bronk Ramsey, Christopher; Koutsodendris, Andreas; Pross, Jörg

    2016-04-01

    Cosmogenic radionuclides, such as 10Be and 14C, share a common production signal, with their formation in the Earth's upper atmosphere modulated by changes to the geomagnetic field, as well as variations in the intensity of the solar wind. Here, we present 54 new 14C measurements from a terrestrial fen peat core extracted from the classical site of Tenaghi Philippon, NE Greece, contiguously spanning the time period between ~48,000 and 39,000 cal. BP. Utilising the most pronounced cosmogenic production peak of the last 100,000 years - that associated with the Laschamp geomagnetic excursion circa 41,000 years ago - we exploit this common production signal, comparing Greenland 10Be with our Tenaghi Philippon 14C record, thereby providing a means to assess the concordance between the radiocarbon (IntCal) and Greenland ice-core (GICC05) timescales themselves for this, the oldest portion of the radiocarbon technique.

  3. 17 CFR 240.14c-1 - Definitions.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 17 Commodity and Securities Exchanges 3 2011-04-01 2011-04-01 false Definitions. 240.14c-1 Section 240.14c-1 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION (CONTINUED) GENERAL... Exchange Act of 1934 Regulation 14c: Distribution of Information Pursuant to Section 14(c) §...

  4. 17 CFR 240.14c-5 - Filing requirements.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 17 Commodity and Securities Exchanges 3 2012-04-01 2012-04-01 false Filing requirements. 240.14c-5 Section 240.14c-5 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION (CONTINUED... Exchange Act of 1934 Regulation 14c: Distribution of Information Pursuant to Section 14(c) §...

  5. 17 CFR 240.14c-5 - Filing requirements.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 17 Commodity and Securities Exchanges 3 2013-04-01 2013-04-01 false Filing requirements. 240.14c-5 Section 240.14c-5 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION (CONTINUED... Exchange Act of 1934 Regulation 14c: Distribution of Information Pursuant to Section 14(c) §...

  6. 17 CFR 240.14c-5 - Filing requirements.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 17 Commodity and Securities Exchanges 3 2011-04-01 2011-04-01 false Filing requirements. 240.14c-5 Section 240.14c-5 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION (CONTINUED... Exchange Act of 1934 Regulation 14c: Distribution of Information Pursuant to Section 14(c) §...

  7. 17 CFR 240.14c-1 - Definitions.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 17 Commodity and Securities Exchanges 3 2012-04-01 2012-04-01 false Definitions. 240.14c-1 Section 240.14c-1 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION (CONTINUED) GENERAL... Exchange Act of 1934 Regulation 14c: Distribution of Information Pursuant to Section 14(c) §...

  8. 17 CFR 240.14c-5 - Filing requirements.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 17 Commodity and Securities Exchanges 4 2014-04-01 2014-04-01 false Filing requirements. 240.14c-5 Section 240.14c-5 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION (CONTINUED... Exchange Act of 1934 Regulation 14c: Distribution of Information Pursuant to Section 14(c) §...

  9. 17 CFR 240.14c-1 - Definitions.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 17 Commodity and Securities Exchanges 4 2014-04-01 2014-04-01 false Definitions. 240.14c-1 Section 240.14c-1 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION (CONTINUED) GENERAL... Exchange Act of 1934 Regulation 14c: Distribution of Information Pursuant to Section 14(c) §...

  10. 17 CFR 240.14c-1 - Definitions.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 17 Commodity and Securities Exchanges 3 2010-04-01 2010-04-01 false Definitions. 240.14c-1 Section 240.14c-1 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION (CONTINUED) GENERAL... Exchange Act of 1934 Regulation 14c: Distribution of Information Pursuant to Section 14(c) §...