Science.gov

Sample records for 14c years bp

  1. Atmospheric deposition of silver and thallium since 12 370 14C years BP recorded by a Swiss peat bog profile, and comparison with lead and cadmium.

    PubMed

    Shotyk, William; Krachler, Michael

    2004-05-01

    A peat core from an ombrotrophic bog in Switzerland provides the first complete, long-term record (14 500 years) of atmospheric Ag and Tl deposition. The lack of enrichment of Ag and Tl in the basal peat layer shows that mineral dissolution in the underlying sediments has not contributed measurably to the Ag and Tl inventories in the peat column, and that Ag and Tl were supplied exclusively by atmospheric deposition. The temporal and spatial distribution of modern peaks in Ag and Tl concentrations are similar to those of Pb which is known to be immobile in peat profiles. Silver and Tl, therefore, are effectively immobile in the peat bog also, allowing an atmospheric deposition chronology to be reconstructed. Silver concentrations vary by up to 114x and Tl up to 241x. While Holocene climate change and land use history can explain the variation in metal concentrations and enrichment factors (EF) in ancient peats (i.e. pre-dating the Roman Period), anthropogenic sources have to be invoked to explain the very high EF values (up to 123 in the case of Ag and 12 in the case of Tl) in peat samples since the middle of the 19th Century. The "natural background" EF of Tl in ancient peats is remarkably close to unity, indicating a lack of significant enrichment of this element in atmospheric aerosols due to chemical weathering of crustal rocks. Silver, on the other hand, shows a pronounced enrichment from 8030 to 5230 (14)C years BP (12x compared to crustal rocks); this may be due to weathering phenomena or biological processes, both of which are driven by climate. Even compared to the natural enrichment of Ag during the mid-Holocene, however, the enrichments of Ag and Tl in modern peats from the Industrial Period are at least an order of magnitude greater. The Pb/Ag and Tl/Ag ratios show that Pb and Tl are preferentially released, compared to Ag, during smelting of argentiferous Pb ores mined during the Roman and Medieval Periods.

  2. Pollen-based biomes for Beringia 18,000, 6000 and 0 14C yr BP

    USGS Publications Warehouse

    Edwards, M.E.; Anderson, P.M.; Brubaker, L.B.; Ager, T.A.; Andreev, A.A.; Bigelow, N.H.; Cwynar, L.C.; Eisner, Wendy R.; Harrison, S.P.; Hu, F.-S.; Jolly, D.; Lozhkin, A.V.; MacDonald, G.M.; Mock, C.J.; Ritchie, J.C.; Sher, A.V.; Spear, R.W.; Williams, J.W.; Yu, G.

    2000-01-01

    The objective biomization method developed by Prentice et al. (1996) for Europe was extended using modern pollen samples from Beringia and then applied to fossil pollen data to reconstruct palaeovegetation patterns at 6000 and 18,000 14C yr BP. The predicted modern distribution of tundra, taiga and cool conifer forests in Alaska and north-western Canada generally corresponds well to actual vegetation patterns, although sites in regions characterized today by a mosaic of forest and tundra vegetation tend to be preferentially assigned to tundra. Siberian larch forests are delimited less well, probably due to the extreme under-representation of Larix in pollen spectra. The biome distribution across Beringia at 6000 14C yr BP was broadly similar to today, with little change in the northern forest limit, except for a possible northward-advance in the Mackenzie delta region. The western forest limit in Alaska was probably east of its modern position. At 18,000 14C yr BP the whole of Beringia was covered by tundra. However, the importance of the various plant functional types varied from site to site, supporting the idea that the vegetation cover was a mosaic of different tundra types.

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    duration of the Mystery Interval. Thus, a ~130% decrease in atmospheric Δ14C recorded by corals precedes the Mystery Interval and atmospheric CO2 rise. We observe a second, more abrupt (less than 800 years) ~100% decrease in Δ14C prior to the Bølling-Allerød period which appears as a plateau in the radiocarbon vs. calendar age relationship. An increase in atmospheric Δ14C between 20 and 18.5 kyr BP could be explained by increased production as a result of a weakening of the earth's magnetic field or from reduced deep-water formation. Paleointensity records from North Atlantic deep-sea cores suggest weakening in the magnetic field at about 20 kyr BP and magnetic data from Lake Bailkal, Biwa, and Hawaiian lavas also support a short term magnetic excursion centered at about 20 ka BP. The accumulation of cosmogenic nuclides (36Cl, 10Be) in Greenland ice, however, does not provide compelling evidence for significantly reduced field strength at this time.

  4. A 16,000 14C yr B.P. packrat midden series from the USA-Mexico Borderlands

    USGS Publications Warehouse

    Holmgren, C.A.; Penalba, M.C.; Rylander, K.A.; Betancourt, J.L.

    2003-01-01

    A new packrat midden chronology from Playas Valley, southwestern New Mexico, is the first installment of an ongoing effort to reconstruct paleovegetation and paleoclimate in the U.S.A.-Mexico Borderlands. Playas Valley and neighboring basins supported pluvial lakes during full and/or late glacial times. Plant macrofossil and pollen assemblages from nine middens in the Playas Valley allow comparisons of two time intervals: 16,000-10,000 and 4000-0 14C yr B.P. Vegetation along pluvial lake margins consisted of open pinyon-juniper communities dominated by Pinus edulis, Juniperus scopulorum, Juniperus cf. coahuilensis, and a rich understory of C4 annuals and grasses. This summer-flowering understory is also characteristic of modern desert grassland in the Borderlands and indicates at least moderate summer precipitation. P. edulis and J. scopulorum disappeared or were rare in the midden record by 10,670 14C yr B.P. The late Holocene is marked by the arrival of Chihuahuan desert scrub elements and few departures as the vegetation gradually became modern in character. Larrea tridentata appears as late as 2190 14C yr B.P. based on macrofossils, but may have been present as early as 4095 14C yr B.P. based on pollen. Fouquieria splendens, one of the dominant desert species present at the site today, makes its first appearance only in the last millennium. The midden pollen assemblages are difficult to interpret; they lack modern analogs in surface pollen assemblages from stock tanks at different elevations in the Borderlands. ?? 2003 University of Washington. Published by Elsevier Inc. All rights reserved.

  5. NotCal04 - Comparison / Calibration 14C records 26-50 cal kBP

    SciTech Connect

    der Plicht, J v; Beck, J; Bard, E; Baille, M

    2004-11-11

    The radiocarbon calibration curve, IntCal04, extends back to 26 cal kBP. While several high resolution records exist beyond this limit, these data sets exhibit discrepancies one to another of up to several millennia. As a result, no calibration curve for the time range 26-50 cal kBP can be recommended as yet, but in this paper the IntCal04 working group compares the available data sets and offers a discussion of the information that they hold.

  6. Biomes of western North America at 18,000, 6000 and 0 14C yr BP reconstructed from pollen and packrat midden data

    USGS Publications Warehouse

    Thompson, R.S.; Anderson, K.H.

    2000-01-01

    A new compilation of pollen and packrat midden data from western North America provides a refined reconstruction of the composition and distribution of biomes in western North America for today and for 6000 and 18,000 radiocarbon years before present (14C yr BP). Modern biomes in western North America are adequately portrayed by pollen assemblages from lakes and bogs. Forest biomes in western North America share many taxa in their pollen spectra and it can be difficult to discriminate among these biomes. Plant macrofossils from packrat middens provide reliable identification of modern biomes from arid and semiarid regions, and this may also be true in similar environments in other parts of the world. However, a weighting factor for trees and shrubs must be used to reliably reconstruct modern biomes from plant macrofossils. A new biome, open conifer woodland, which includes eurythermic conifers and steppe plants, was defined to categorize much of the current and past vegetation of the semiarid interior of western North America. At 6000 14C yr BP, the forest biomes of the coastal Pacific North-west and the desert biomes of the South-west were in near-modern positions. Biomes in the interior Pacific North-west differed from those of today in that taiga prevailed in modern cool/cold mixed forests. Steppe was present in areas occupied today by open conifer woodland in the northern Great Basin, while in the central and southern Rocky Mountains forests grew where steppe grows today. During the mid-Holocene, cool conifer forests were expanded in the Rocky Mountains (relative to today) but contracted in the Sierra Nevada. These differences from the forests of today imply different climatic histories in these two regions between 6000 14C yr BP and today. At 18,000 14C yr BP, deserts were absent from the South-west and the coverage of open conifer woodland was greatly expanded relative to today. Steppe and tundra were present in much of the region now covered by forests in

  7. Environmental history since 11,000 14C yr B.P. of the northeastern Pampas, Argentina, from alluvial sequences of the Luján River

    NASA Astrophysics Data System (ADS)

    Prieto, Aldo R.; Blasi, Adriana M.; De Francesco, Claudio G.; Fernández, Celina

    2004-09-01

    Sedimentological, malacological, and pollen analyses from 14C-dated alluvial sections from the Luján River provide a detailed record of environmental changes during the Holocene in the northeastern Pampas of Argentina. From 11,200 to 9000 14C yr B.P., both sedimentary and biological components suggest that the depositional environment was eutrophic, alkaline, and freshwater to brackish shallow water bodies without significant water circulation. During this time, bioclastic sedimentation was dominant and the shallow water bodies reached maximum development as the climate became more humid, suggesting an increase in precipitation. Short-term fluctuations in climate during the last stage of this interval may have been sufficient to initiate changes in the water bodies, as reduction of the volume alternated with periods of flooding. The beginning of the evolution of shallow swamps in the wide floodplain or huge wetlands was contemporaneous with a sea level lower than the present one. From 9000 and 7000 14C yr B.P., mesotrophic, alkaline, brackish, probably anoxic swamps existed. Between 7000 and 3000 14C yr B.P., anoxic calcareous swamps were formed, with subaerial exposure and development of the Puesto Berrondo Soil (3500-2900 14C yr B.P.). A trend to a reduction of water bodies is recorded from 9000 to ca. 3000 14C yr B.P., with a significant reduction after ca. 7000 14C yr B.P. A shift to subhumid-dry climate after 7000 14C yr B.P. appears to be the main cause. During this time, an additional external forcing toward higher groundwater levels was caused by Holocene marine transgression causing changes in the water bodies levels. The climate became drier during the late Holocene (ca. 3000 yr B.P.), when clastic sedimentation increased, under subhumid-dry conditions. Flood events increased in frequency during this time. From ca. A.D. 1790 to present, the pollen record reflects widespread disturbance of the vegetation during the European settlement.

  8. 14C activity and global carbon cycle changes over the past 50,000 years.

    PubMed

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

    2004-01-01

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

  9. Continuous lake-sediment records of glaciation in the Sierra Nevada between 52,600 and 12,500 14C yr B.P.

    USGS Publications Warehouse

    Benson, L.V.; May, Howard M.; Antweiler, R.C.; Brinton, T.I.; Kashgarian, Michaele; Smoot, J.P.; Lund, S.P.

    1998-01-01

    The chemistry of the carbonate-free clay-size fraction of Owens Lake sediments supports the use of total organic carbon and magnetic susceptibility as indicators of stadial-interstadial oscillations. Owens Lake records of total organic carbon, magnetic susceptibility, and chemical composition of the carbonate-free, clay-size fraction indicate that Tioga glaciation began ~24,500 and ended by ~13,600 14C yr B.P. Many of the components of glacial rock flour (e.g., TiO2, MnO, BaO) found in Owens Lake sediments achieved maximum values during the Tioga glaciation when valley glaciers reached their greatest extent. Total organic carbon and SiO2 (amorphous) concentrations reached minimum values during Tioga glaciation, resulting from decreases in productivity that accompanied the introduction of rock flour into the surface waters of Owens Lake. At least 20 stadial-interstadial oscillations occurred in the Sierra Nevada between 52,600 and 14,000 14C yr B.P. Total organic carbon data from a Pyramid Lake sediment core also indicate oscillations in glacier activity between >39,500 and ~13,600 14C yr B.P. Alpine glacier oscillations occurred on a frequency of ???1900 yr in both basins, suggesting that millennial-scale oscillations occurred in California and Nevada during most of the past 52,600 yr.

  10. 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

  11. Dynamics of the ca. 4965 yr 14C BP “Ochre Pumice” Plinian eruption of Popocatépetl volcano, México

    NASA Astrophysics Data System (ADS)

    Arana-Salinas, Lilia; Siebe, Claus; Macías, José Luis

    2010-05-01

    The Ochre Pumice (OP) Plinian fallout was produced by Popocatépetl volcano in central Mexico, during a major Plinian eruption that occurred 4965 ± 65 14C yr BP (3700 BC). The OP is part of the Ochre Pumice Sequence (OPS), that consists of surge, fall, and pyroclastic flow deposits. The OP Plinian fallout shows a bimodal grain size distribution with poor to moderate sorting that improves progressively towards the upper beds. The juvenile component is mainly pumice (>83 wt.%), whereas the accidental components consist of igneous, sedimentary, and metamorphic clasts from the walls of the magma chamber and/or conduit. The vesicularity of the pumice decreases from bottom to top of the stratigraphic sequence while the crystal and glass contents increase. This suggests increasing magma degassing prior and during the eruption. The chemical composition of the pumice varies insignificantly; at the base it is less evolved (SiO 2 = 61 wt.%) and it becomes slightly more silicic towards the top (SiO 2 = 63 wt.%). Pumice clasts have a crystallinity index that ranges between 10 and 25 vol.% and display a seriate texture with phenocrysts of euhedral plagioclase (Pl) + clinopyroxene (Cpx) + orthopyroxene (Opx) + olivine (Ol) ± oxide (Ox) ± apatite (Ap). The size of the maximum lithic (2.5 cm) at a horizontal distance of 19 km indicates an eruption column height of 37-41 km. The isopach map allows the recognition of a dispersal axis that points towards the NNE, where an area of ~ 300 km 2 was covered by >6 cm of pumice and ash. A minimum volume for the OP Plinian fallout deposit was calculated using a minimum thickness of 6 cm found at distal outcrops, and was estimated at ~ 4.9 km 3 which corresponds to 2 km 3 of dense rock equivalent (DRE). Stratigraphic relations indicate that the entire OPS was emplaced during a short time interval of a few days to weeks and consisted of three main different phases: phreato-magmatic, Plinian, and vulcanian. It started violently with the

  12. Arctic ground squirrels of the mammoth-steppe: paleoecology of Late Pleistocene middens (˜24 000 29 450 14C yr BP), Yukon Territory, Canada

    NASA Astrophysics Data System (ADS)

    Zazula, Grant D.; Froese, Duane G.; Elias, Scott A.; Kuzmina, Svetlana; Mathewes, Rolf W.

    2007-04-01

    This paper presents paleoecological analyses of 48 fossil arctic ground squirrel ( Spermophilus parryii) middens (nests and caches) recovered from ice-rich loess sediments in the Klondike region of west-central Yukon Territory. AMS radiocarbon dates and stratigraphic association of middens with Dawson tephra (˜25 300 14C yr BP), indicate these paleoecological data reflect the onset of glacial conditions of early Marine Isotope Stage (MIS) 2 and terminal MIS 3 (˜24 000-29 450 14C yr BP). Plant macrofossils include at least 60 plant taxa, including diverse graminoids ( Poa, Elymus trachycaulus, Kobresia myosuroides), steppe forbs ( Penstemon gormanii, Anemone patens var. multifida, Plantago cf. canescens), tundra forbs ( Draba spp., Bistorta vivipara), dwarf shrubs ( Salix cf. arctica, S. cf. polaris), sage ( Artemisia frigida) and rare trees ( Picea mariana). Many of these taxa identified in the middens represent the first recorded fossils for these plants in Eastern Beringia and add to our knowledge of the floristic composition of Pleistocene vegetation and biogeography in this region. Fossil beetles include typical members of the Eastern Beringian steppe-tundra fauna ( Lepidophorus lineaticollis and Connatichela artemisiae) and others suggesting predominantly dry, open habitats. Cache forage selection is suggested by some plant taxa which were particularly frequent and abundant in the middens ( Bistorta vivipara, Kobresia myosuroides, Ranunculus spp., Potentilla, Erysimum cf. cheiranthoides, Poa, Carex and Draba). Factors such as proximity of vegetation to burrows and abundance of fruits and seeds per plant were probably important in cache selection. Glacial conditions enabled arctic ground squirrels to form widespread and dense populations in regions such as the Klondike in which they are rare or absent at present. This fossil midden record supports previous hypotheses that suggest arctic ground squirrels evolved in and are well-adapted to the open, steppe

  13. A caldera-forming eruption ~ 14,100 14C yr BP at Popocatépetl volcano, México: Insights from eruption dynamics and magma mixing

    NASA Astrophysics Data System (ADS)

    Sosa-Ceballos, Giovanni; Gardner, James E.; Siebe, Claus; Macías, José L.

    2012-02-01

    Volcán Popocatépetl (México) erupted ~ 14,100 14 C yr BP (~ 17,000 cal yr BP) producing the Tutti Frutti Plinian Eruption (TFPE). The eruption tapped two different silicic magmas (GT and MT) that mixed just prior and during the eruption, resulting in the collapse of the reservoir and formation of a caldera. Two fall deposits (GT and MT) and two series of pyroclastic flows (P01 and P02) were emplaced during the eruption. These were studied at 91 sites, where thicknesses were measured, and at many sites the five coarsest lithics observed in each unit were measured. Several samples from deposits were sieved for component analysis. The eruption began with intermittent, short lived eruptions that deposited the GT unit at proximal sites around the volcano. Next, the main Plinian phase of the eruption started, and the MT unit and a pyroclastic flow were deposited to the northwest of the present-day cone. Overall, ~ 3 km3 of magma were erupted. The pyroclastic flow within MT separates two fall units characterized by different pumice color and lithic content. During deposition of the lower unit (milky pumice) eruptive intensity reached 3 × 108 kg s- 1, producing a Plinian column 37 ± 2 km in height. After emplacement of the pyroclastic flow, a lithic-rich upper unit (orange pumice) was deposited with a peak intensity of 5 × 108 kg s- 1, producing a Plinian column 44 ± 2 km in height. Lithics in the TFPE vary from only volcanic (~ 5 vol.%) in GT, to volcanic, granodiorite, and metamorphic (up to 50 vol.%) in MT. The shift in components and lithic content was produced by the collapse of the reservoir. We suggest that the reservoir was over-pressured because of mixing between GT and MT magmas, and then relaxed when all of GT, and part of MT magma were tapped, triggering collapse. The characteristics of mixing were elucidated by studying banded pumice and mixed populations of crystals found in pumice from both units. In addition, the occurrence of An-rich plagioclase, Mg

  14. Persistence of 14C-labeled atrazine and its residues in a field lysimeter soil after 22 years.

    PubMed

    Jablonowski, Nicolai D; Köppchen, Stephan; Hofmann, Diana; Schäffer, Andreas; Burauel, Peter

    2009-07-01

    Twenty-two years after the last application of ring-14C-labeled atrazine at customary rate (1.7 kg ha(-1)) on an agriculturally used outdoor lysimeter, atrazine is still detectable by means of accelerated solvent extraction and LC-MS/MS analysis. Extractions of the 0-10 cm soil layer yielded 60% of the residual 14C-activity. The extracts contained atrazine (1.0 microg kg(-1)) and 2-hydroxy-atrazine (42.5 microg kg(-1)). Extractions of the material of the lowest layer 55-60 cm consisting of fine gravel yielded 93% of residual 14C-activity, of which 3.4 microg kg(-1) was detected as atrazine and 17.7 microg kg(-1) was 2-hydroxy-atrazine. The detection of atrazine in the lowest layer was of almost four times higher mass than in the upper soil layer. These findings highlight the fact that atrazine is unexpectedly persistent in soil. The overall persistence of atrazine in the environment might represent a potential risk for successive groundwater contamination by leaching even after 22 years of environmental exposure.

  15. Two years since SSAMS: Status of 14C AMS at CAIS

    NASA Astrophysics Data System (ADS)

    Ravi Prasad, G. V.; Cherkinsky, Alexander; Culp, Randy A.; Dvoracek, Doug K.

    2015-10-01

    The NEC 250 kV single stage AMS accelerator (SSAMS) was installed two years ago at the Center for Applied Isotope Studies (CAIS), University of Georgia. The accelerator is primarily being used for radiocarbon measurements to test the authenticity of natural and bio-based samples while all other samples such as geological, atmospheric, marine and archaeological. are run on the 500 kV, NEC 1.5SDH-1 model tandem accelerator, which has been operating since 2001. The data obtained over a six months period for OXI, OXII, ANU sucrose and FIRI-D are discussed. The mean value of ANU sucrose observed to be slightly lower than the consensus value. The processed blanks on SSAMS produce lower apparent age compared to the tandem accelerator as expected.

  16. 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.

  17. Surface Water Processes in the Indonesian Throughflow as Documented by a 115-Year High-Resolution Coral Δ 14C Record

    NASA Astrophysics Data System (ADS)

    Fallon, S. J.; Guilderson, T. P.; Caldeira, K.; Moore, M.

    2003-12-01

    Radiocarbon has been used as a tracer to study global ocean circulation through the distribution of natural and bomb-derived 14C. In order to get a complete picture of the temporal variation of 14C, proxy records, such as those provided by corals are needed. Corals can provide time series of seasonal and interannual 14C variations of the surface ocean over time scales of hundreds of years. Bi-monthly radiocarbon values from a 115-year time series have been recovered from a coral in the Indonesian Seaway in order to better understand seasonal, interannual and decadal variability in the surface water masses that contribute to the Indonesian Throughflow. The radiocarbon time series occasionally displays a small seasonal signal (10-15 per mil) from 1890 to 1954, with the time period 1875-1880 displaying higher radiocarbon possibly due to a strong El Nino. After 1954 the radiocarbon record increases rapidly, a response to the increased atmospheric 14C caused by nuclear weapons testing. From 1954 to 1986 the record displays clear seasonal variability from 15 to 60 (per mil). The quick response to the increased atmospheric 14C and the high post-bomb peak (+160 per mil) indicate a North Pacific source to the waters entering the Indonesian Throughflow. Sensitivity tests were run to investigate the role of surface mixed layer depth and parameterization using an atmosphere/ocean coupled model (GFDL MOM) and compared to the coral radiocarbon time series. The model results exhibit a post-bomb peak that is too high and slightly early but displays the seasonal signal shown by the coral. The model also retains too much radiocarbon after the bomb-peak suggesting the model is exchanging too much CO2 and not mixing it through the water column rapidly enough.

  18. 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.

  19. Relative sea-level trends along the coast of Maine during the past 5,000 [sup 14]C years

    SciTech Connect

    Gehrels, W.R.; Belknap, D.F. . Dept. of Geological Sciences); Kelley, J.T. ); Gong, B.; Pearce, B.R. . Dept. of Civil Engineering)

    1993-03-01

    Holocene differential crustal movements in coastal regions are best inferred by comparing slopes of relative sea-level curves from different coastal localities. Sea-level indicators must have a narrow vertical range that is precisely established in the modern environment. Their age must be determined with the highest degree of certainty; Accelerator Mass Spectrometry (AMS) [sup 14]C dating of very small samples minimizes the changes of mixing older and younger materials. Finally, when indicators not related to Mean Tide Level are used, a correction should be applied to account for changes in paleotidal range. This study reports on sea-level chronologies from three salt marshes along the coast of Maine: Well(43[degree]17 minutes N, 70[degree]34 minutes W), Phippsburg (43[degree]45 minutes N, 69[degree]49 minutes W), and Machiasport (44[degree]41 minutes N, 67[degree]24 minutes W). Radiocarbon dates number 44 for Wells (23 new: 7 conventional basal, 2 AMS basal), 21 for Phippsburg (11 new: 5 conventional basal, 3 AMS basal), and 11 for Machiasport (all new: 7 conventional basal, 4 AMS basal). All newly collected [sup 14]C samples were analyzed for associated foraminiferal assemblages. These fossil assemblages were then compared with the modern vertical zonation of salt marsh foraminifera that was established along transects in each marsh. In agreement with earlier studies from Nova Scotia marshes, a 100% Trochammina macrescens zone occurs within a narrow (20 cm) vertical range along the edge of the marshes in Maine (level of Highest High Water). In addition, Tiphotrocha comprimata is abundantly observed in a 30 cm vertical zone between Mean High Water (MHW) and Mean Higher High Water. After elevations of sea-level indicators were adjusted to a common datum (MHW), a final correction was applied to account for changes in tidal range using a numerical tidal model for the Gulf of Maine.

  20. Paleoenvironment interpretation of a 1760 years B.P. old sediment in a mangrove area of the Bay of Guanabara, using pollen analysis.

    PubMed

    Barth, Ortrud M; São-Thiago, Luiz E U; Barros, Marcia A

    2006-06-01

    A sediment sample was obtained at 122 cm from the top of a drilling core in the Guapimirim mangrove, Bay of Guanabara, and analyzed using pollen analysis. This muddy core reached a sandy ground at 133 cm. 14C datation got the age of 1760 +/- 50 years B.P. The most frequent pollen grains were mangrove species of Rhizophora mangle, Laguncularia racemosa and Avicennia schaueriana. "Restinga" and tropical rain forest vegetation was recognized behind the mangrove. After the last sea transgression at 2500 years B.P., the water level lowered to its actual size, allowing the installation of this mangrove. PMID:16710562

  1. Year-round probing of soot carbon and secondary organic carbon contributions and sources to the South Asian Atmospheric Brown Cloud using radiocarbon (14C) measurements

    NASA Astrophysics Data System (ADS)

    Kirillova, Elena; Sheesley, Rebecca J.; Andersson, August; Krusâ, Martin; Safai, P. D.; Budhavant, Krishnakant; Rao, P. S. P.; Praveen, P. S.; Gustafsson, Örjan

    2010-05-01

    South Asia is one region of vital importance for assessing human impact on radiative forcing by atmospheric aerosols. Previous research in the region has indicated that black carbon is a significant component of the regional aerosol load. In contrast, there is more ambiguous information regarding the contribution of secondary organic aerosols (SOA) to the total carbonaceous (TC) aerosol composition. Here we primarily address the SOA component of the South Asian Atmospheric Brown Cloud (ABC) by a combination of measurements of SOA concentrations and the 14C signature of TC. Atmospheric particulate matter was collected during fourteen-month continuous sampling campaigns Jan 2008 - March 2009 at both the Maldives Climate Observatory at Hannimaadho (MCO-H) and at the Sinhagad hilltop sampling site of the Indian Institute of Tropical Meteorology (SIN) in central-western India. The radiocarbon method is an ideal approach to identify fossil sources (14C "dead") compared to biogenic and biomass combustion products (with a contemporary 14C signal). The radiocarbon source apportionment of TC revealed very similar contribution from biogenic/biomass combustion (60-70%) for Indian SIN site and the MCOH receptor regions for much of the year. However, during the summer monsoon season biomass contribution to TC at the Indian Ocean site increases to 70-80%, while it decreases to 40-50% at the Indian site. Source apportionment of a soot carbon (SC) isolate (CTO-375 method; a tracer of black carbon) shows a similar trend. According to preliminary data in summer biomass contribution is higher at the MCOH receptor site (70%) compared to the SIN background site (45%). These unique year-round 14C data will be interpreted in view of the SOA concentration and the varying origin of the air masses.

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

    PubMed

    Jöris, Olaf; Street, Martin

    2008-11-01

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

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

    NASA Astrophysics Data System (ADS)

    Raimund, Muscheler

    2010-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  5. Geoarchaeological evidence from Peru for a 5000 years B.P. onset of El Nino

    SciTech Connect

    Sandweiss, D.H.; Richardson, J.B. III; Rollins, H.B.

    1996-09-13

    For the tropical west coast of South America, where El Nino/Southern Oscillation (ENSO) is most pronounced, archaeological and associated paleontological deposits in northern Peru revealed a major climate change at about 5000 years before the present (yr B.P.). The data implied the presence of stable, warm tropical water as far south as 10{degrees}S during the early mid-Holocene (about 8000 to 5000 yr B.P.). These data suggest that ENSO did not occur for some millennia preceding 5000 yr B.P., when global and regional climate was warmer than today. 36 refs., 1 fig., 3 tabs.

  6. Study of the neutron and proton capture reactions 10,11B(n, γ), 11B(p, γ), 14C(p, γ), and 15N(p, γ) at thermal and astrophysical energies

    NASA Astrophysics Data System (ADS)

    Dubovichenko, Sergey; Dzhazairov-Kakhramanov, Albert

    2014-07-01

    We have studied the neutron-capture reactions 10,11B(n, γ) and the role of the 11B(n, γ) reaction in seeding r-process nucleosynthesis. The possibility of the description of the available experimental data for cross-sections of the neutron capture reaction on 10B at thermal and astrophysical energies, taking into account the resonance at 475 keV, was considered within the framework of the modified potential cluster model (MPCM) with forbidden states (FS) and accounting for the resonance behavior of the scattering phase shifts. In the framework of the same model, the possibility of describing the available experimental data for the total cross-sections of the neutron radiative capture on 11B at thermal and astrophysical energies were considered with taking into account the 21 and 430 keV resonances. Description of the available experimental data on the total cross-sections and astrophysical S-factor of the radiative proton capture on 11B to the GS of 12C was treated at astrophysical energies. The possibility of description of the experimental data for the astrophysical S-factor of the radiative proton capture on 14C to the GS of 15N at astrophysical energies, and the radiative proton capture on 15N at the energies from 50 to 1500 keV was considered in the framework of the MPCM with the classification of the orbital states according to Young tableaux. It was shown that, on the basis of the M1 and the E1 transitions from different states of the p15N scattering to the GS of 16O in the p15N channel, it is quite succeed to explain general behavior of the S-factor in the considered energy range in the presence of two resonances.

  7. The enigma of 3400 years BP coastal oolites in tropical northwest Western Australia… why then, why there?

    NASA Astrophysics Data System (ADS)

    Hearty, Paul; O'Leary, Michael; Donald, Andrew; Lachlan, Terry

    2006-05-01

    Oolites crop out along the northwestern coast of Western Australia at Port Smith, about 80 km SW of Broome. An oolitic coastal ridge truncated by marine erosion exposes subtidal, intertidal, and supratidal (aeolian) facies. The deposits are firmly indurated and composed of about 75% tangentially and moderately thickly layered, aragonitic ooid grains with over 90% quartz nuclei. Subtidal sedimentary structures are exposed about a metre above the present high tide mark, hinting that sea level may have been somewhat higher when the shoreline was formed. However, the macrotidal range of up to 7 m, and the possibility of cyclonic surges along the coast, precludes unequivocal determinations on this point. Whole-rock amino acid racemisation (AAR) geochronology (epimerisation of isoleucine: D-alloisoleucine/ L-isoleucine or A/I) on each facies of the oolite outcrop averaged 0.106 ± 0.013 ( N = 10). The modern beach contains fewer ooids (˜ 30%), and nearly half of these are stained brown, grey, or black, perhaps as a result of burial, reduction and/or mineralization. A higher (older) mean and large standard deviation in whole-rock amino acid ratio of 0.145 ± 0.067 ( N = 2) supports our inference that ooids on the modern beach were reworked from fossil deposits. Reverse phase chronostratigraphy (RPC) on individual ooid grains holds tremendous promise in this preliminary study. RPC results show a narrow variation of D/ L values (CV = 6-11%), and yield nearly identical D/ L Asp means from light coloured fossil ooids (0.307 ± 0.018 ( N = 17)); light (0.323 ± 0.026 ( N = 12)) and dark coloured ooids (0.298 ± 0.027 ( N = 10)) from the active beach face. When compared to A/I ratios from 14C dated mid-Holocene ooids in the Bahamas, the mean A/I from Port Smith reflects an age of ca. 3500-4500 years that is in agreement with a calibrated AMS 14C age of 3370 ± 50 calendar years BP on the same material. Thus, the ooids were formed, transported, emplaced, strongly cemented, and

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

    PubMed

    Shibata, Setsuko; Kawano, Eiko; Nakabayashi, Takeshige

    2005-08-01

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

  9. The Uwekahuna Ash Member of the Puna Basalt: product of violent phreatomagmatic eruptions at Kilauea volcano, Hawaii, between 2800 and 2100 14C years ago

    NASA Astrophysics Data System (ADS)

    Dzurisin, Daniel; Lockwood, John P.; Casadevall, Thomas J.; Rubin, Meyer

    1995-07-01

    Kilauea volcano's reputation for relatively gentle effusive eruptions belies a violent geologic past, including several large phreatic and phreatomagmatic eruptions that are recorded by Holocene pyroclastic deposits which mantle Kilauea's summit area and the southeast flank of adjacent Mauna Loa volcano. The most widespread of these deposits whose original distribution can be reconstructed is the Uwekahuna Ash Member of the Puna Basalt, a basaltic surge and fall deposit emplaced during two or more eruptive episodes separated by a few decades to several centuries. The first episode occurred between 2770 ± 70 and 2265 ± 50 14C yr ago. It included two major pyroclastic surges, each preceded by unusually vigorous lava fountaining from a vent near the volcano's summit. Before the second eruptive episode, 2110 ± 120 14C yr ago, plants had re-colonized the rainforest environment northeast of the summit, and at least two lava flows from Mauna Loa had buried parts of the first-episode deposits. The second episode also began with vigorous lava fountaining, followed by widespread lithic ashfall, a third major surge and finally a fourth fountaining event. Before the final pumice deposit could be significantly reworked, it was partly buried by picritic basalt flows that are unusual in Kilauea's summit area. In proximal areas, the Uwekahuna Ash Member is more than 1 m thick (locally > 5 m) and includes lithic blocks up to 0.8 m in diameter. Coarse, primarily lithic debris was deposited around the vent by laterally expanding surges; fallout deposits accumulated preferentially to the northeast under the influence of high-altitude counter-tradewinds. The area devastated by surges and originally buried by at least 15 cm of the Uwekahuna was about 420 km 2. The bulk volume of the deposits was approximately 0.3 km 3, including less than 0.1 km 3 of juvenile material. Juvenile constituents are olivine-tholeiitic basalts similar in major-element composition to typical Kilauea summit

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

    NASA Astrophysics Data System (ADS)

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

    2002-12-01

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

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

    PubMed Central

    Marcus, Joyce; Flannery, Kent V.

    2004-01-01

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

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

    PubMed

    Marcus, Joyce; Flannery, Kent V

    2004-12-28

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

  13. Variability of 14C reservoir age and air-sea flux of CO2 in the Peru-Chile upwelling region during the past 12,000 years

    NASA Astrophysics Data System (ADS)

    Carré, Matthieu; Jackson, Donald; Maldonado, Antonio; Chase, Brian M.; Sachs, Julian P.

    2016-01-01

    The variability of radiocarbon marine reservoir age through time and space limits the accuracy of chronologies in marine paleo-environmental archives. We report here new radiocarbon reservoir ages (ΔR) from the central coast of Chile (~ 32°S) for the Holocene period and compare these values to existing reservoir age reconstructions from southern Peru and northern Chile. Late Holocene ΔR values show little variability from central Chile to Peru. Prior to 6000 cal yr BP, however, ΔR values were markedly increased in southern Peru and northern Chile, while similar or slightly lower-than-modern ΔR values were observed in central Chile. This extended dataset suggests that the early Holocene was characterized by a substantial increase in the latitudinal gradient of marine reservoir age between central and northern Chile. This change in the marine reservoir ages indicates that the early Holocene air-sea flux of CO2 could have been up to five times more intense than in the late Holocene in the Peruvian upwelling, while slightly reduced in central Chile. Our results show that oceanic circulation changes in the Humboldt system during the Holocene have substantially modified the air-sea carbon flux in this region.

  14. 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

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

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

    PubMed

    Weninger, Bernhard; Jöris, Olaf

    2008-11-01

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

  17. 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.

  18. 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.

  19. 200-BP-1 Prototype Hanford Barrier -- 15 Years of Performance Monitoring

    SciTech Connect

    Ward, Anderson L.; Draper, Kathryn E.; Link, Steven O.; Clayton, Ray E.

    2011-09-30

    Monitoring is an essential component of engineered barrier system design and operation. A composite capacitive cover, including a capillary break and an evapotranspiration (ET) barrier at the Hanford Site, is generating data that can be used to help resolve these issues. The prototype Hanford barrier was constructed over the 216-B-57 Crib in 1994 to evaluate surface-barrier constructability, construction costs, and physical and hydrologic performance at the field scale. The barrier has been routinely monitored between November 1994 and September 1998 as part of a Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (CERCLA) treatability test of barrier performance for the 200 BP 1 Operable Unit. Since FY 1998, monitoring has focused on a more limited set of key water balance, stability, and biotic parameters. In FY 2009, data collection was focused on: (1) water-balance monitoring, consisting of precipitation, runoff, soil moisture storage, and drainage measurements with evapotranspiration calculated by difference; (2) stability monitoring, consisting of asphalt-layer-settlement, basalt-side-slope-stability, and surface-elevation measurements; (3) vegetation dynamics; and (4) animal use. September 2009 marked 15 years since the start of monitoring and the collection of performance data. This report describes the results of monitoring activities during the period October 1, 2008, through September 30, 2009, and summarizes the 15 years of performance data collected from September 1994 through September 2009.

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

    USGS Publications Warehouse

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

    1999-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

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

  2. 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.

  3. 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

  4. Using 14C and 3H to understand groundwater flow and recharge in an aquifer window

    NASA Astrophysics Data System (ADS)

    Atkinson, A. P.; Cartwright, I.; Gilfedder, B. S.; Cendón, D. I.; Unland, N. P.; Hofmann, H.

    2014-12-01

    Knowledge of groundwater residence times and recharge locations is vital to the sustainable management of groundwater resources. Here we investigate groundwater residence times and patterns of recharge in the Gellibrand Valley, southeast Australia, where outcropping aquifer sediments of the Eastern View Formation form an "aquifer window" that may receive diffuse recharge from rainfall and recharge from the Gellibrand River. To determine recharge patterns and groundwater flow paths, environmental isotopes (3H, 14C, δ13C, δ18O, δ2H) are used in conjunction with groundwater geochemistry and continuous monitoring of groundwater elevation and electrical conductivity. The water table fluctuates by 0.9 to 3.7 m annually, implying recharge rates of 90 and 372 mm yr-1. However, residence times of shallow (11 to 29 m) groundwater determined by 14C are between 100 and 10 000 years, 3H activities are negligible in most of the groundwater, and groundwater electrical conductivity remains constant over the period of study. Deeper groundwater with older 14C ages has lower δ18O values than younger, shallower groundwater, which is consistent with it being derived from greater altitudes. The combined geochemistry data indicate that local recharge from precipitation within the valley occurs through the aquifer window, however much of the groundwater in the Gellibrand Valley predominantly originates from the regional recharge zone, the Barongarook High. The Gellibrand Valley is a regional discharge zone with upward head gradients that limits local recharge to the upper 10 m of the aquifer. Additionally, the groundwater head gradients adjacent to the Gellibrand River are generally upwards, implying that it does not recharge the surrounding groundwater and has limited bank storage. 14C ages and Cl concentrations are well correlated and Cl concentrations may be used to provide a first-order estimate of groundwater residence times. Progressively lower chloride concentrations from 10

  5. 14C AMS dating Yongcheon cave

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

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

  6. 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 (

  7. 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.

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

    USGS Publications Warehouse

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

    2002-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  10. Environmental change in the Yangtze River delta since 12,000 years B.P.

    NASA Astrophysics Data System (ADS)

    Liu, Kam-Biu; Sun, Shuncai; Jiang, Xinhe

    1992-07-01

    A 52-m core from Qidong at the tip of the Yangtze River (Chang Jiang) delta provides a history of sea-level change, deltaic development, and vegetational and climatic changes during the last 12,000 yr. About 12,000 yr ago, when sea level was about 60 m below the present level, the coring site was situated in the innermost part of the exposed continental shelf. The late-Pleistocene vegetation on the uplands of the Lower Yangtze River valley was a mixed forest of deciduous and broadleaved evergreen trees in which Betula, Ulmus, Tsuga, and Cupressaceae were slightly more abundant than at present. Abies and Picea were probably present as relict populations on mountains bordering the region. Rapidly rising sea level converted the Qidong area to a coastal or estuarine environment between 11,000 and 10,800 yr B.P., leading to widespread development of wetlands dominated by Gramineae and Cyperaceae. During the next 2500 yr coastal erosion due to marine transgression obliterated the sedimentary record. Deltaic sedimentation predominated from 8300 to 3800 yr B.P., as the Yangtze River delta prograded by successively building a series of estuarine sand bars. During the mid-Holocene, the climate was slightly warmer and more humid than at present, allowing the subtropical broadleaved evergreen trees to increase their populations. Pinus and Quercus became more abundant after 3800 yr B.P. in response to climatic cooling. The present deltaic plain in Qidong formed less than 200 yr ago.

  11. Strong carbon release from the deep ocean induced a major atmospheric 14C drop over Heinrich Stadial 1

    NASA Astrophysics Data System (ADS)

    Sarnthein, M.; Grootes, P. M.; Schneider, B.

    2012-12-01

    Using the modern global distributions of apparent 14C ventilation ages and DIC we established a transfer function to trace past changes in the carbon storage of ocean waters >2000 m water depth. On this basis we concluded that the LGM carbon inventory was approximately 730-980 Gt larger than during pre-industrial times. This amount compares well with an estimated glacial transfer of 530-700 Gt from both the atmosphere and terrestrial biosphere in addition to a major DIC relocation from ocean intermediate waters. We consider that the LGM atmosphere contained 190 ppm CO2 (~375 Gt C) with a 14C concentration 1.4 times higher than that of the standard modern atmosphere (fMC) (Reimer et al. 2009). The LGM deep ocean had an average reservoir age of 2100 yr, which means that its 14C concentration was 0.77 times that of the LGM atmosphere, 1.08 times that of the modern atmosphere (fMC). During the subsequent early deglac¬ial Heinrich Stadial 1, a large portion of this 14C depleted carbon was released to the atmosphere and terrestrial biosphere (Monnin et al. 2001; Ciais et al. 2012). Our estimates suggest that the ocean-atmosphere exchange, producing this deglacial transfer of deep-ocean carbon, was sufficient to account for a 190-permil drop in atmospheric 14C. Thus an alleged major 'mystery' of last deglacial times, the source of 14C-depleted additional atmospheric carbon, appears solved. -- Ciais, P., Tagliabue, A., Cuntz, M., Bopp, L., et al. (2012), Large inert carbon pool in the terrestrial biosphere during the Last Glacial Maximum. Nature Geoscience 5, 74-79. Monnin, E., et al. (2001), Atmospheric CO2 concentrations over the last glacial termination. Science 291, 112-114. Reimer, P., et al. (2009), INTCAL09 and MARINE09 radiocarbon age calibration curves, 0-50,000 years cal. BP. Radiocarbon 51, 1111-1150.

  12. 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.

  13. 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

  14. Responses to the 2800 years BP climatic oscillation in shallow- and deep-basin sediments from the Dead Sea

    NASA Astrophysics Data System (ADS)

    Neugebauer, Ina; Brauer, Achim; Schwab, Markus; Dulski, Peter; Frank, Ute; Hadzhiivanova, Elitsa; Kitagawa, Hiroyuki; Litt, Thomas; Schiebel, Vera; Taha, Nimer; Waldmann, Nicolas

    2015-04-01

    Laminated lake sediments from the Dead Sea basin provide high-resolution records of climatic variability in the eastern Mediterranean region, which is considered being especially sensitive to changing climatic conditions. In the study presented here, we aim to reconstruct palaeoclimatic changes and their relation to the frequency of flood/erosion and dust deposition events as archived in the Dead Sea basin for the time interval from ca 3700 to 1700 years BP. A ca 4 m thick, mostly annually laminated (varved) sediment section from the western margin of the Dead Sea (shallow-water DSEn - Ein Gedi profile) was analysed and correlated to the new ICDP Dead Sea Deep Drilling Project core 5017-1 from the deep basin. To detect even single event layers, we applied a multi-proxy approach of high-resolution microscopic thin section analyses, µXRF element scanning and magnetic susceptibility measurements, supported by grain size and palynological analyses. Based on radiocarbon and varve dating two pronounced dry periods were detected at ~3500-3300 yrs BP and ~2900-2400 yrs BP that are characterized by a sand deposit during the older dry period and enhanced frequency of coarse detrital layers during the younger dry period in the shallow-water DSEn core, both interpreted as increased erosion processes. In the 5017-1 deep-basin core these dry periods are depicted by halite deposits. The timing of the younger dry period broadly coincides with the Homeric Minimum of solar activity at ca 2800 yrs BP. Our results suggest that during this period the Dead Sea region experienced a change in synoptic weather patterns leading to an increased occurrence of flash-flood events, overprinting the overall dry climatic conditions. Following this dry spell, a 250-yrs period of increased dust deposition is observed, coinciding with more regular aragonite precipitation during less arid climatic conditions.

  15. Using 14C and 3H to understand groundwater flow and recharge in an aquifer window

    NASA Astrophysics Data System (ADS)

    Atkinson, A. P.; Cartwright, I.; Gilfedder, B. S.; Cendón, D. I.; Unland, N. P.; Hofmann, H.

    2014-06-01

    Knowledge of groundwater residence times and recharge locations are vital to the sustainable management of groundwater resources. Here we investigate groundwater residence times and patterns of recharge in the Gellibrand Valley, southeast Australia, where outcropping aquifer sediments of the Eastern View Formation form an "aquifer window" that may receive diffuse recharge and recharge from the Gellibrand River. To determine recharge patterns and groundwater flowpaths, environmental isotopes (3H, 14C, δ13C, δ18O, δ2H) are used in conjunction with groundwater geochemistry and continuous monitoring of groundwater elevation and electrical conductivity. Despite the water table fluctuating by 0.9-3.7 m annually producing estimated recharge rates of 90 and 372 mm yr-1, residence times of shallow (11-29 m) groundwater determined by 14C ages are between 100 and 10 000 years. 3H activities are negligible in most of the groundwater and groundwater electrical conductivity in individual areas remains constant over the period of study. Although diffuse local recharge is evident, the depth to which it penetrates is limited to the upper 10 m of the aquifer. Rather, groundwater in the Gellibrand Valley predominantly originates from the regional recharge zone, the Barongarook High, and acts as a regional discharge zone where upward head gradients are maintained annually, limiting local recharge. Additionally, the Gellibrand River does not recharge the surrounding groundwater and has limited bank storage. 14C ages and Cl concentrations are well correlated and Cl concentrations may be used to provide a first-order estimate of groundwater residence times. Progressively lower chloride concentrations from 10 000 years BP to the present day are interpreted to indicate an increase in recharge rates on the Barongarook High.

  16. 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.

  17. Eastern Andean environmental and climate synthesis for the last 2000 years BP from terrestrial pollen and charcoal records of Patagonia

    NASA Astrophysics Data System (ADS)

    Sottile, G. D.; Echeverria, M. E.; Mancini, M. V.; Bianchi, M. M.; Marcos, M. A.; Bamonte, F. P.

    2015-06-01

    The Southern Hemisphere Westerly Winds (SWW) constitute an important zonal circulation system that dominates the dynamics of Southern Hemisphere mid-latitude climate. Little is known about climatic changes in the Southern South America in comparison to the Northern Hemisphere due to the low density of proxy records, and adequate chronology and sampling resolution to address environmental changes of the last 2000 years. Since 2009, new pollen and charcoal records from bog and lakes in northern and southern Patagonia at the east side of the Andes have been published with an adequate calibration of pollen assemblages related to modern vegetation and ecological behaviour. In this work we improve the chronological control of some eastern Andean previously published sequences and integrate pollen and charcoal dataset available east of the Andes to interpret possible environmental and SWW variability at centennial time scales. Through the analysis of modern and past hydric balance dynamics we compare these scenarios with other western Andean SWW sensitive proxy records for the last 2000 years. Due to the distinct precipitation regimes that exist between Northern (40-45° S) and Southern Patagonia (48-52° S) pollen sites locations, shifts on latitudinal and strength of the SWW results in large changes on hydric availability on forest and steppe communities. Therefore, we can interpret fossil pollen dataset as changes on paleohydric balance at every single site by the construction of paleohydric indices and comparison to charcoal records during the last 2000 cal yrs BP. Our composite pollen-based Northern and Southern Patagonia indices can be interpreted as changes in latitudinal variation and intensity of the SWW respectively. Dataset integration suggest poleward SWW between 2000 and 750 cal yrs BP and northward-weaker SWW during the Little Ice Age (750-200 cal yrs BP). These SWW variations are synchronous to Patagonian fire activity major shifts. We found an in phase

  18. AixMICADAS, the accelerator mass spectrometer dedicated to 14C recently installed in Aix-en-Provence, France

    NASA Astrophysics Data System (ADS)

    Bard, Edouard; Tuna, Thibaut; Fagault, Yoann; Bonvalot, Lise; Wacker, Lukas; Fahrni, Simon; Synal, Hans-Arno

    2015-10-01

    A compact AMS system dedicated to measuring 14C in ultra-small samples was installed at the CEREGE in Aix-en-Provence at the end of March 2014, together with an automated graphitization system. AixMICADAS operates at around 200 kV with carbon ion stripping in helium leading to a transmission of about 47%. The hybrid ion source works with graphite targets and CO2 gas. It is coupled to a versatile gas interface system that ensures stable gas measurements from different sources: a cracker for CO2 in glass ampoules, an elemental analyzer for combusting organic matter and an automated system to handle carbonate by wet chemistry. The analyses performed during the first half-year of operation show that a precision of about 2‰ is reached on modern samples of about 1 mg of carbon. Measurements of IAEA reference materials of various 14C ages show a good agreement with consensus values. Direct measurements of geological graphites indicate a machine background equivalent to an age of 68,000 years BP. AixMICADAS is thus limited solely by the 14C contamination of samples in the field and in the laboratory. The performances of the gas ion source and its gas interface system were tested with two CO2 production units: the elemental analyzer and the automated carbonate hydrolysis unit. These tests show that samples ranging between 10 and 100 μg C can produce a 12C- ion beam of the order of 10-15 μA during time spans ranging from 3 to 30 min depending on the sample mass. Coupling the automated hydrolysis system to the gas ion source of AixMICADAS, enables us to develop a method involving sequential leaching of carbonate samples with direct 14C measurements of the leached fractions and the residual sample. The main advantage is that all of steps leaching and hydrolysis are performed in the same vial for a particular sample. A sequential leaching was applied to a young carbonate sample (ca. 6600 years BP) whose 14C age agrees with previous determination and which shows no sign of

  19. 14C tebuconazole degradation in Colombian soils.

    PubMed

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

    2010-01-01

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

  20. 14C tebuconazole degradation in Colombian soils.

    PubMed

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

    2010-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-07-01

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

  2. A mid-european decadal isotope-climate record from 15,500 to 5000 years B.P

    PubMed

    von Grafenstein U; Erlenkeuser; Brauer; Jouzel; Johnsen

    1999-06-01

    Oxygen-isotope ratios of precipitation (delta18OP) inferred from deep-lake ostracods from the Ammersee (southern Germany) provide a climate record with decadal resolution. The record in detail shows many of the rapid climate shifts seen in central Greenland ice cores between 15,000 and 5000 years before the present (B.P.). Negative excursions in the estimated delta18OP from both of these records likely reflect short weakenings of the thermohaline circulation caused by episodic discharges of continental freshwater into the North Atlantic. Deviating millennial-scale trends, however, indicate that climate gradients between Europe and Greenland changed systematically, reflecting a gradual rearrangement of North Atlantic circulation during deglaciation.

  3. A mid-european decadal isotope-climate record from 15,500 to 5000 years B.P

    PubMed

    von Grafenstein U; Erlenkeuser; Brauer; Jouzel; Johnsen

    1999-06-01

    Oxygen-isotope ratios of precipitation (delta18OP) inferred from deep-lake ostracods from the Ammersee (southern Germany) provide a climate record with decadal resolution. The record in detail shows many of the rapid climate shifts seen in central Greenland ice cores between 15,000 and 5000 years before the present (B.P.). Negative excursions in the estimated delta18OP from both of these records likely reflect short weakenings of the thermohaline circulation caused by episodic discharges of continental freshwater into the North Atlantic. Deviating millennial-scale trends, however, indicate that climate gradients between Europe and Greenland changed systematically, reflecting a gradual rearrangement of North Atlantic circulation during deglaciation. PMID:10356392

  4. 200-BP-1 Prototype Hanford Barrier Annual Monitoring Report for Fiscal Year 2004

    SciTech Connect

    Ward, Andy L.; Linville, Jenifer K.; Keller, Jason M.; Seedahmed, Gamal H.

    2005-01-03

    In FY 2004, monitoring of the prototype Hanford barrier focused on barrier stability, vegetative cover, evidence of plant and animal intrusion, and the main components of the water balance. Monitored water-balance components included precipitation, runoff, storage, drainage, and deep percolation. Precipitation in FY 2004 was 26 percent less than in FY 2003 but was still higher than normal. The seasonal distribution in precipitation was also different from the previous year with a 43 percent reduction in spring precipitation and a 46 percent increase in summer precipitation. The cumulative amount of water received from October 1994, through September 2004, was 2,559.58 mm on the northern half of the barrier, which is the formerly irrigated treatment, and 1,886.71 mm on the southern non-irrigated treatments. Water storage continued to show a cyclic pattern, increasing in the winter and declining in the spring and summer to a lower limit of about 100 mm in response to evapotranspiration. The 600-mm design storage has never been exceeded. Total drainage from the soil-covered plots range from 2.9E-4 mm to 0.22 mm or 0.003 6 0.004 percent of precipitation. Side-slope drainage was much higher at 20.9 6 2.3 percent of precipitation from the gravel and 18.6 6 5.1 percent from the riprap. There was no runoff from the barrier, but runoff from the BY tank farm following a thunderstorm in May eroded a 45-inch-deep channel into the structural fill at the toe of the riprap slope. Above-asphalt and below-asphalt moisture measurements show no evidence of deep percolation of water. Topographic surveys were conducted on the barrier surface, including the two settlement gauges and 12 creep gauges on the riprap slope using aerial photogrammetry (AP) and a global positioning system (GPS). Comparing the aerial photogrammetry (AP) and global positioning system (GPS) surveys with the traditional survey shows the barrier and side slopes to be stable. Both AP and GPS show potential for

  5. 200-BP-1 Prototype Hanford Barrier - 15 Years of Performance Monitoring

    SciTech Connect

    Ward, Anderson L.; Link, Steven O.; Draper, Kathryn E.; Clayton, Ray E.

    2009-09-01

    barrier was burned to remove vegetation and study the effects of fire on barrier performance. The most immediate effects has been on water storage patterns with the bare surface showing a slower accumulation of water, a smaller peak storage and a delayed release relative to the unburned side due to evaporation . Nonetheless the residual storage at the end of the year was similar for the burned and unburned sides.

  6. 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.

  7. 200-BP-1 Prototype Hanford Barrier Annual Monitoring Report for Fiscal Years 2005 Through 2007

    SciTech Connect

    Ward, Andy L.; Link, Steven O.; Strickland, Christopher E.; Draper, Kathryn E.; Clayton, Ray E.

    2008-02-01

    in 1994 although species diversity on the soil cover continues to decrease, from 35 in 1997 to 12 in 2007. The formerly irrigated treatments continue to show greater cover of grasses and litter than the non-irrigated treatments. On the formerly irrigated treatments, the mean cover class was 25 to 50 percent for both grasses and shrubs. On the non-irrigated treatments, the mean cover class was 5 to 25 percent from grasses and 25 to 50 percent for shrubs. The western and northern side slopes of the barrier show less plant cover than the soil surface, but show higher species diversity. This may be due to the influence of windblown soil and seeds from adjacent land, or the lack of shrubs competing for resources. Insects and small mammals continue to use the barrier surface and several holes and mounds were observed during the last year. This suggests that the restored barrier surface is beginning to function like a recovering ecosystem. Small-mammal burrowing on the top and sides of the barrier is most prevalent on the finer-grained and disturbed soils while active ant mounds were observed on the northern and western slopes.

  8. A complete terrestrial radiocarbon record for 11.2 to 52.8 kyr B.P.

    PubMed

    Bronk Ramsey, Christopher; Staff, Richard A; Bryant, Charlotte L; Brock, Fiona; Kitagawa, Hiroyuki; van der Plicht, Johannes; Schlolaut, Gordon; Marshall, Michael H; Brauer, Achim; Lamb, Henry F; Payne, Rebecca L; Tarasov, Pavel E; Haraguchi, Tsuyoshi; Gotanda, Katsuya; Yonenobu, Hitoshi; Yokoyama, Yusuke; Tada, Ryuji; Nakagawa, Takeshi

    2012-10-19

    Radiocarbon ((14)C) provides a way to date material that contains carbon with an age up to ~50,000 years and is also an important tracer of the global carbon cycle. However, the lack of a comprehensive record reflecting atmospheric (14)C prior to 12.5 thousand years before the present (kyr B.P.) has limited the application of radiocarbon dating of samples from the Last Glacial period. Here, we report (14)C results from Lake Suigetsu, Japan (35°35'N, 135°53'E), which provide a comprehensive record of terrestrial radiocarbon to the present limit of the (14)C method. The time scale we present in this work allows direct comparison of Lake Suigetsu paleoclimatic data with other terrestrial climatic records and gives information on the connection between global atmospheric and regional marine radiocarbon levels.

  9. Evolutionary changes in the genome of Mycobacterium tuberculosis and the human genome from 9000 years BP until modern times.

    PubMed

    Spigelman, Mark; Donoghue, Helen D; Abdeen, Ziad; Ereqat, Suheir; Sarie, Issa; Greenblatt, Charles L; Pap, Ildikó; Szikossy, Ildikó; Hershkovitz, Israel; Bar-Gal, Gila Kahila; Matheson, Carney

    2015-06-01

    The demonstration of Mycobacterium tuberculosis DNA in ancient skeletons gives researchers an insight into its evolution. Findings of the last two decades sketched the biological relationships between the various species of tubercle bacilli, the time scale involved, their possible origin and dispersal. This paper includes the available evidence and on-going research. In the submerged Eastern Mediterranean Neolithic village of Atlit Yam (9000 BP), a human lineage of M. tuberculosis, defined by the TbD1 deletion in its genome, was demonstrated. An infected infant at the site provides an example of active tuberculosis in a human with a naïve immune system. Over 4000 years later tuberculosis was found in Jericho. Urbanization increases population density encouraging M. tuberculosis/human co-evolution. As susceptible humans die of tuberculosis, survivors develop genetic resistance to disease. Thus in 18th century Hungarian mummies from Vác, 65% were positive for tuberculosis yet a 95-year-old woman had clearly survived a childhood Ghon lesion. Whole genome studies are in progress, to detect changes over the millennia both in bacterial virulence and also host susceptibility/resistance genes that determine the NRAMP protein and Killer Cell Immunoglobulin-like Receptors (KIRs). This paper surveys present evidence and includes initial findings.

  10. Temporal variation in the interhemispheric 14C offset

    NASA Astrophysics Data System (ADS)

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

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

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

    SciTech Connect

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

    1984-06-01

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

  12. Factors Affecting 14C Ages of Lacustrine Carbonates: Timing and Duration of the Last Highstand Lake in the Lahontan Basin

    USGS Publications Warehouse

    Benson, L.

    1993-01-01

    Two processes contribute to inaccurate 14C age estimates of carbonates precipitated within the Lahontan basin, NevadaCalifornia: low initial 14C/C ratios in lake water (reservoir effect) and addition of modern carbon to calcium carbonate after its precipitation. The mast reliable set of 14C ages on carbonates from elevations > 1310 m in the Pyramid and Walker Lake subbasins indicate that lakes in all seven Lahontan subbasins coalesced ???14,200 14C yr B.P. forming Lake Lahontan. Lake Lahontan achieved its 1330-m highstand elevation by ???13,800 14 C yr B.P. and receded to 1310 m by ???13,700 14C yr B.P. Calculations, based on measured carbonate-accumulation rates, of the amount of time Lake Lahontan exceeded 1310 and 1330 m (500 and 50 yr) are consistent with this chronology. The timing of the Lake Lahontan highstand is of interest because of the linkage of highstand climates with proximity to the polar jet stream. The brevity of the Lahontan highstand is interpreted to indicate that the core of the southern branch of the polar jet stream remained only briefly over the Lahontan basin.

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

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

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

  14. Fossil beetle evidence for climatic change 18,000-10,000 years B.P. in south-central Chile

    USGS Publications Warehouse

    Hoganson, J.W.; Ashworth, A.C.

    1992-01-01

    Cold-adapted beetles colonized the lowlands of the Lake Region of south-central Chile following the retreat of glaciers from their maximum extent at about 19,500 yr B.P. The beetle fauna from 18,000 to 14,000 yr B.P. was characterized by species of moorland habitats. This fauna was species-poor compared to later faunas of the postglacial interval. By 14,000 yr B.P. arboreal species were replacing species of open habitats, reflecting a change toward a warmer climate. By about 12,500 yr B.P. fossil beetle assemblages consisted entirely of rain forest species. The fauna of the postglacial interval was about five times as species-rich as that of the glacial interval. The change in species composition and greater diversity of the beetle fauna was produced by an increase in mean annual temperature estimated to be about 4??-5??C. This was the last major climatic change to affect profoundly the biota of the middle latitudes of South America. The fossil beetle assemblages do not imply a reversal to a colder climate at the time of the European Younger Dryas interval between 11,000 and 10,000 yr B.P. ?? 1992.

  15. Extension of the Southern Hemisphere Atmospheric Radiocarbon Curve, 2120-850 years BP: Results from Tasmanian Huon Pine

    SciTech Connect

    Zimmerman, S R; P.Guilderson, T; Buckley, B M; Cook, E

    2010-02-12

    Decadal samples of dendrochronologically-dated pine (Lagorostrobos franklinii) from the Stanley River basin, Tasmania have been radiocarbon dated between 2120-850 yr BP. This data set overlaps and extends the current Southern Hemisphere record, which currently covers the period 110-995 yr BP. There is good agreement between the two records between 995-850 yr BP, between sample replicates and with consensus values for standards. As in the younger dataset, we find evidence for a distinct but variable offset between the southern hemisphere data and IntCal04; although this is likely due to real temporal variability in the interhemispheric offset, further work is planned to rule out possible laboratory or sample preparation differences.

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

    NASA Astrophysics Data System (ADS)

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

    2003-06-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

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

  18. Isotopic analyses (/sup 18/O, /sup 13/C, /sup 14/C) of two meromictic lakes in the Canadian Arctic Archipelago

    SciTech Connect

    Page, P.; Ouellet, M.; Hillaire-Marcel, C.; Dickman, M.

    1984-05-01

    Meromictic Lakes Garrow and Sophia in the Canadian Arctic Archipelago were sampled to establish the origin and age of their water by isotopic studies. /sup 18/O values reflect the permanent stratification of the water in both lakes. The mixolimnia contain waters with an isotopic signal between -13.16 and -21.98%, coherent with the values for precipitation in these high latitudes. In the chemoclines, the delta/sup 18/O values increase to -10% concomitantly with a rise in chloride content to 42 g.liter/sup -1/. In the monimolimnia, hypersaline waters (up to 2.5 times the salinity of seawater) show negative delta/sup 18/O values (ca. -.08%). These waters result from brine production during permafrost growth in the watershed, according to a Rayleigh process. /sup 14/C dating of total inorganic carbon in the Lake Garrow monimolimnion gave an age of 2580 +/- 260 years BP. In Lake Sophia, the deep waters exhibit recent /sup 14/C activity that suggests recent infiltration of seawater into the lake basin.

  19. A Model-based Interpretation of Low-frequency Changes in the Carbon Cycle during the Last 120,000 years and its Implications for the Reconstruction of Atmospheric (delta) 14-C

    NASA Technical Reports Server (NTRS)

    Koehler, Peter; Muscheler, Raimund; Fischer, Hubertus

    2006-01-01

    A main caveat in the interpretation of observed changes in atmospheric (Delta)C-l4 during the last 50,000 years is the unknown variability of the carbon cycle, which together with changes in the C-14 production rates determines the C-14 dynamics. A plausible scenario explaining glacial/interglacial dynamics seen in atmospheric CO2 and (delta)C-13 was proposed recently (Kohler et al., 2005a). A similar approach that expands its interpretation to the C-14 cycle is an important step toward a deeper understanding of (Delta)C-14 variability. This approach is based on an ocean/atmosphere/biosphere box model of the global carbon cycle (BICYCLE) to reproduce low-frequency changes in atmospheric CO2 as seen in Antarctic ice cores. The model is forced forward in time by various paleoclimatic records derived from ice and sediment cores. The simulation results of our proposed scenario match a compiled CO2 record from various ice cores during the last 120,000 years with high accuracy (r(sup 2) = 0.89). We analyze scenarios with different C-14 production rates, which are either constant or based on Be-10 measured in Greenland ice cores or the recent high-resolution geomagnetic field reconstruction GLOPIS-75 and compare them with the available (Delta)C-14 data covering the last 50,000 years. Our results suggest that during the last glacial cycle in general less than 110%0o f the increased atmospheric (Delta)C-14 is based on variations in the carbon cycle, while the largest part (5/6) of the variations has to be explained by other factors. Glacial atmospheric (Delta)C-14 larger than 700% cannot not be explained within our framework, neither through carbon cycle-based changes nor through variable C-14 production. Superimposed on these general trends might lie positive anomalies in atmospheric (Delta)C-14 of approx. 50% caused by millennial-scale variability of the northern deep water production during Heinrich events and Dansgaard/Oeschger climate fluctuations. According to our

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

    NASA Astrophysics Data System (ADS)

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

    2000-10-01

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

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

    PubMed Central

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

    2013-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

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

    SciTech Connect

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

    2004-10-11

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

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

    NASA Astrophysics Data System (ADS)

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

    2007-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    1995-03-01

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

  6. Marine04 Marine radiocarbon age calibration, 26 ? 0 ka BP

    SciTech Connect

    Hughen, K; Baille, M; Bard, E; Beck, J; Bertrand, C; Blackwell, P; Buck, C; Burr, G; Cutler, K; Damon, P; Edwards, R; Fairbanks, R; Friedrich, M; Guilderson, T; Kromer, B; McCormac, F; Manning, S; Bronk-Ramsey, C; Reimer, P; Reimer, R; Remmele, S; Southon, J; Stuiver, M; Talamo, S; Taylor, F; der Plicht, J v; Weyhenmeyer, C

    2004-11-01

    New radiocarbon calibration curves, IntCal04 and Marine04, have been constructed and internationally ratified to replace the terrestrial and marine components of IntCal98. The new calibration datasets extend an additional 2000 years, from 0-26 ka cal BP (Before Present, 0 cal BP = AD 1950), and provide much higher resolution, greater precision and more detailed structure than IntCal98. For the Marine04 curve, dendrochronologically dated tree-ring samples, converted with a box-diffusion model to marine mixed-layer ages, cover the period from 0-10.5 ka cal BP. Beyond 10.5 ka cal BP, high-resolution marine data become available from foraminifera in varved sediments and U/Th-dated corals. The marine records are corrected with site-specific {sup 14}C reservoir age information to provide a single global marine mixed-layer calibration from 10.5-26.0 ka cal BP. A substantial enhancement relative to IntCal98 is the introduction of a random walk model, which takes into account the uncertainty in both the calendar age and the radiocarbon age to calculate the underlying calibration curve. The marine datasets and calibration curve for marine samples from the surface mixed layer (Marine04) are discussed here. The tree-ring datasets, sources of uncertainty, and regional offsets are presented in detail in a companion paper by Reimer et al.

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

    SciTech Connect

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

    1988-06-15

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

  8. Groundwater residence time and palaeohydrology in the Otway Basin, South Australia: 2H, 18O and 14C data

    NASA Astrophysics Data System (ADS)

    Love, A. J.; Herczeg, A. L.; Leaney, F. W.; Stadter, M. F.; Dighton, J. C.; Armstrong, D.

    1994-01-01

    Stable isotopes (δ 2H, δ 18O and δ 13C) and radiocarbon ( 14C) have been used in conjunction with chemical data to evaluate recharge mechanisms, groundwater residence time and palaeohydrology within the confined Dilwyn sand aquifer in the Gambier Embayment of the Otway Basin. This aquifer does not receive recharge down-gradient of the hydraulic hinge-line and data have been interpreted along two discrete flow lines. The mean residence time of groundwater (determined by 14C) in the confined aquifer from the hydraulic hinge position to the sea (a distance of about 50 km) along an inferred flow path is approximately 12 800 years. The corresponding hydraulic travel time calculated from Darcy's law is approximately 49 000 years. The apparent discrepancy may be a result of eustatic sea-level lowering during the last glacial. Because the groundwater system is hydraulically connected to the sea, lower sea-level would result in increased gradients and a decrease in groundwater residence time. Variations in stable isotopic composition along flow lines suggest a number of recharge mechanisms. Stable isotope data indicate progressive depletion of 2H and 18O in the groundwaters over the past 30 000 years. Groundwaters older than about 10 000 years B.P. were recharged either during a cooler climate climatic regime (lower precipitation/evapotranspiration and temperature) and/or the vapour source(s) had travelled over greater continental mass than those recharged over the past 10 000 years. Lower chloride concentrations in some of the older groundwaters indicate lower evapotranspiration rates in the recharge areas before 10 000 years ago.

  9. 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

  10. 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.

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

    PubMed

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

    2010-02-01

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

  12. 14C release from a Soviet-designed pressurized water reactor nuclear power plant.

    PubMed

    Uchrin, G; Csaba, E; Hertelendi, E; Ormai, P; Barnabas, I

    1992-12-01

    The Paks Nuclear Power Plant in Hungary runs with four pressurized water reactors, each of 440-MWe capacity. Sampling systems have been developed and used to determine the 14C of various chemical forms (14CO2, 14CO, 14CnHm) in the airborne releases. The average normalized yearly discharge rates for the time period 1988-1991 are equal to 0.77 TBq GWe-1 y-1 for hydrocarbons and 0.05 TBq GWe-1 y-1 for CO2. The contribution of 14CO was less than 0.5% of the total emission. The 14C discharge rate is estimated to be four times higher than the corresponding mean data of Western European pressurized water reactors. The calculated effective dose equivalent to individuals living in the vicinity of the power plant, due to 14C release, was 0.64 microSv in 1991 while the effective dose equivalent due to the natural 14C level was 15 microSv y-1. The long-term global impact of the 14C release in the operational period of the plant (1982-1991) was 1,270 man-Sv. The 14C excess in the environmental air has been measured since 1989 by taking biweekly samples at a distance of 1.7 km from the nuclear power plant. The long-term average of radiocarbon excess coming from the power plant was 2 mBq m-3. The local 14C deposition was followed by tree ring analysis, too. No 14C increase higher than the uncertainty of the measurement (four per thousand = 0.17 mBq m-3) was observed.

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

    PubMed

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

    2013-05-01

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

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

    PubMed

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

    2003-10-01

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

  15. 17 CFR 240.14c-1 - Definitions.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

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

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

    PubMed

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

    1990-10-01

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

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

    SciTech Connect

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

    1990-02-01

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

  18. Variability in North Atlantic Bottom Water nutrients and carbonate ion during the last 467,000 years BP

    NASA Astrophysics Data System (ADS)

    Rashid, H.; Marchitto, T.; Boyle, E. A.; Smith, M. E.

    2009-12-01

    Understanding the meridional overturning circulation (MOC) is essential since it reorganizes heat and moisture between high and low latitudes and thus exerts control on the global climate. Boyle and Keigwin (1985/86) reconstructed the MOC of the last 215 ka BP using the sediment core CHN82-4PC from the subtropical northwestern Atlantic Ocean. The authors inferred that the net export of the nutrient-depleted North Atlantic Deep Water (NADW) was reduced by a factor of two relative to the inflow of the nutrient-rich Southern Ocean Waters (SOW) during the glacial marine isotope stages (MIS) 2, 4 and 6. In this study, we extend the records up to 467 ka BP (i.e. MIS 12) by patching CHN82-4PC records with IODP Site 1313 (41oN, 32.57oW; 3,425 mwd). We have measured the B/Ca, Cd/Ca and δ13C in benthic foraminifers. B/Ca ratios were converted to carbonate ion concentration using the newly developed equations of Yu and Elderfield (2007). We found that the Cd/Ca ratios were higher in glacial MISs 8.4, 9.2, 10 and 12 than in glacial MISs 2, 4 and 6. In general, we observe a mode shift to higher Cd/Ca ratios at around 225 ka BP. Furthermore, the lower bottom water carbonate ion concentrations were accompanied by higher Cd/Ca ratios. Enriched benthic δ18O values with the concomitant depleted δ13C in Cibicidoides wuellerstorfi were found in MISs 10 and 12 compared to MISs 2 and 6. However, the magnitude of differences in δ18O between MISs2/6 and MISs10/12 do not equate with the magnitude of changes in δ13C for the same period. The multi-proxy sea-surface temperature (SST) estimates at Site 1313 from the Mg/Ca ratios in Globigerina bulloides and alkenone (Uk37) concentrations show 3 and 4oC cooler SSTs in MISs 10 and 12, respectively, than in MIS 2. Given that there were no appreciable increases in atmospheric dust loading or decreases in pCO2 and CH4 in the EPICA records during MISs 10 and 12 compared to the preceding or subsequent ice ages, it can be inferred that there were

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

    PubMed

    Seago, A; Gorrod, J W

    1987-02-01

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

  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. 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

  2. TMEM14C is required for erythroid mitochondrial heme metabolism.

    PubMed

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

    2014-10-01

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

  3. TMEM14C is required for erythroid mitochondrial heme metabolism

    PubMed Central

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

    2014-01-01

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

  4. 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

  5. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

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

  7. 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

  8. The 14C age of glacial North Atlantic surface waters: Greenland Interstadial Events 2-13

    NASA Astrophysics Data System (ADS)

    Austin, William; Hibbert, Fiona; Bard, Edouard; Bryant, Charlotte

    2016-04-01

    We present an updated compilation of surface ocean (Globigerina bulloides) AMS 14C ages for Greenland Interstadials (GI) 2-13, spanning the interval 25,000 - 45,000 cal BP from the mid-latitude NE Atlantic Ocean. New data from two marine sediment cores located 83 km apart in the NE Atlantic are presented: MD95-2006 (Barra Fan; 57°01.82 N, 10°03.48 W; 2120m water depth) and MD04-2822 (Rockall Trough; 56°50.54 N, 11°22.96 W; 2344m water depth) as well as published data from core MD95-2042 (Iberian Margin; 37°45'N, 10°10'W, 3146 m water depth). Replicated sea surface temperature (SST) records show evidence for abrupt warming events; we correlate these directly to the D/O cycles of the Greenland (NGRIP) ice-core oxygen isotope record. We test the proposed synchronization of two of these records using three geochemically distinct tephra isochrones (NAAZ-1, Fugloyarbanki and NAAZ-2). Our data provide a potentially useful new surface ocean composite record of 14C age from the mid-latitude North Atlantic, suggesting broadly consistent interstadial 14C age data from all three records; and highlight the advantage of tuning mid-latitude SST records to Greenland (tested with tephra isochrones where possible) when constructing marine age-models through this time interval.

  9. Genetic variant rs16430 6bp > 0bp at the microRNA-binding site in TYMS and risk of sporadic breast cancer risk in non-Hispanic white women aged ≤ 55 years.

    PubMed

    Guan, Xiaoxiang; Liu, Hongliang; Ju, Jingfang; Li, Yangkai; Li, Peng; Wang, Li-E; Brewster, Abenaa M; Buchholz, Thomas A; Arun, Banu K; Wei, Qingyi; Liu, Zhensheng

    2015-04-01

    Thymidylate synthase (TYMS) is involved in the folate metabolism and provision of nucleotides needed for DNA synthesis and repair. Thus, functional genetic variants in TYMS may alter cancer risk. In the study, we evaluated associations of three germline variants (rs2790 A > G, rs16430 6 bp > 0 bp, and rs1059394 C > T) in the predicted miRNA-binding sites of TYMS with risk of sporadic breast cancer in non-Hispanic white women aged ≤ 55. We found that carriers of the rs16430 0 bp variant allele had an increased risk of breast cancer [adjusted odd ratio (OR) = 1.37, 95% confidence interval (CI): 1.08-1.73; P = 0.010], compared with carriers of the 6 bp/6 bp genotype. This increased risk was more evident in older subjects (OR = 1.47, 95% CI = 1.06-2.03, P = 0.022), never smokers (OR = 1.67, 95% CI = 1.23-2.25, P < 0.001), never drinkers (OR = 1.44, 95% CI = 1.01-2.05, P = 0.043), and estrogen receptor-positive patients (OR = 1.46, 95% CI = 1.11-1.92, P = 0.006), regardless of tumor stages. The results are consistent with the functional analyses of rs16430 as previously reported, which showed that the 0 bp allele had a decrease in both luciferase activity by ∼ 70% and mRNA levels by ∼ 50% compared with the 6bp allele. Additionally, the rs16430 variant was predicted to influence the binding activity of miR-561. Taken together, these findings indicate that the TYMS rs16430 may contribute to the etiology of sporadic breast cancer in non-Hispanic white women aged ≤ 55 yr. Further validation in large population-based or cohort studies is needed.

  10. Applications of environmental 14C measured by AMS as a carbon tracer

    NASA Astrophysics Data System (ADS)

    Nakamura, Toshio; Nakai, Nobuyuki; Ohishi, Shoji

    1987-11-01

    AMS techniques have been applied to measure 14C concentrations, or Δ 14C values, of annual tree rings (1945-1983) of a Kiso hinoki tree grown in Gifu prefecture, and of acid-insoluble carbonaceous compounds extracted from cored sediments (surface to 30 cm deep) of Lake Biwa in Shiga prefecture. An increase in Δ 14C values was found for both tree rings and cored sediments, resulting from 14C artificially produced by nuclear weapon tests. Activities of 210Pb and 214Pb were measured to estimate the sedimentation rate of the Lake Biwa sediments and to provide a temporal control. A primitive model of carbon exchange between the troposphere, surface ocean water, and the biosphere was applied to the annual changes in Δ 14C of the hinoki tree rings and also of coral rings from Florida, USA. The times required to transfer bomb-carbon from the troposphere to surface sea water and to the biosphere were estimated to be about 11 and 23 years, respectively.

  11. Abundance of (14)C in biomass fractions of wastes and solid recovered fuels.

    PubMed

    Fellner, Johann; Rechberger, Helmut

    2009-05-01

    In recent years thermal utilization of mixed wastes and solid recovered fuels has become of increasing importance in European waste management. Since wastes or solid recovered fuels are generally composed of fossil and biogenic materials, only part of the CO(2) emissions is accounted for in greenhouse gas inventories or emission trading schemes. A promising approach for determining this fraction is the so-called radiocarbon method. It is based on different ratios of the carbon isotopes (14)C and (12)C in fossil and biogenic fuels. Fossil fuels have zero radiocarbon, whereas biogenic materials are enriched in (14)C and reflect the (14)CO(2) abundance of the ambient atmosphere. Due to nuclear weapons tests in the past century, the radiocarbon content in the atmosphere has not been constant, which has resulted in a varying (14)C content of biogenic matter, depending on the period of growth. In the present paper (14)C contents of different biogenic waste fractions (e.g., kitchen waste, paper, wood), as well as mixtures of different wastes (household, bulky waste, and commercial waste), and solid recovered fuels are determined. The calculated (14)C content of the materials investigated ranges between 98 and 135pMC.

  12. 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

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

    PubMed Central

    Yin, Jinhui; Yang, Xue; Zheng, Yonggang

    2014-01-01

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

  14. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

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

  16. 14C age of the "Museum Breccia" (Campi Flegrei) and its relevance for the origin of the Campanian Ignimbrite

    USGS Publications Warehouse

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

    1991-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

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

    PubMed

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

    1978-04-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  20. 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

  1. Geomagnetic Secular Variation in Texas over the Last 17,000 Years: High-Intensity Geomagnetic Field 'Spike' Observed at ca. 3000 cal BP

    NASA Astrophysics Data System (ADS)

    Bourne, M. D.; Feinberg, J. M.; Waters, M. R.; Stafford, T. W., Jr.; Forman, S. L.; Lundelius, E. L.

    2015-12-01

    By observing the fluctuations in direction and intensity of the Earth's magnetic field through time, we increase our understanding of the fluid motions in the Earth's outer core that sustain the geomagnetic field, the geodynamo. Recent archaeomagnetic studies in the Near East have proposed extremely rapid increases - 'spikes' - in geomagnetic field intensity ca. 3000 years ago that have proved problematic for our current understanding of core-flow. However, until now, these geomagnetic spikes had not been observed outside of the Near East, where they have been found in metallurgical slag and mud brick walls. We present a new fully-oriented, geomagnetic secular variation and relative palaeointensity (RPI) record for the last 17,000 years from Hall's Cave, Texas. Sediment washed into the cave has formed a continuous stratigraphic sequence that is at least 3.5 m thick. Within the stable, cool climate of the cave, pedogenic and bioturbation processes are almost non-existent, thereby limiting post-depositional physical and geochemical alteration of the magnetic record. The sub-aerial and subterranean setting of the sedimentary sequence in Hall's Cave enabled us to collect oriented palaeomagnetic cubes from an excavated section through the sequence. The palaeomagnetic samples yielded high-quality vectors. An age model for the sequence, determined using 57 AMS 14C-dates on individual bones from microvertebrate, was combined with the palaeomagnetic data to construct a secular variation record. The record is in broad agreement with predictions by Holocene field models for the site's location. However, at ca. 3000 years ago, the RPI data indicate an almost four-fold increase in geomagnetic field intensity lasting several hundred years and contemporaneous with the more short-lived, decadal-scale spikes reported from the Near East. Evidence for this extreme intensity event outside of the Near East has major implications for our current understanding of core-dynamics.

  2. Uptake and transformation of soil [14C]-trinitrotoluene by cool-season grasses

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study investigated the fate and uptake of [14C]-TNT from soil into orchardgrass (Dactylis glomerata), perennial ryegrass (Lolium perenne) and tall fescue (Festuca arundinacea) over a one year period in a greenhouse-controlled environment. Pots (n=4 for each grass, containing 10 mg cold TNT/kg s...

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

    PubMed

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

    2008-08-01

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

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

    PubMed

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

    2008-08-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

    groundwater flow in the Tono area may be several tens of thousands of years, and the groundwater age calculated from the 4He and 14C ages appears to be consistent with geochemical information such as groundwater types, δD and δ18O.

  6. Carbon and 14C distribution in tropical and subtropical agricultural soils

    NASA Astrophysics Data System (ADS)

    Prastowo, Erwin; Grootes, Pieter; Nadeau, Marie

    2016-04-01

    Paddy soil management affects, through the alternating anoxic and oxic conditions it creates, the transport and stabilisation of soil organic matter (SOM). Irrigation water may percolate more organic materials - dissolved (DOM) and colloidal - into the subsoil during anoxic conditions. Yet a developed ploughpan tends to prevent C from going deeper in the subsoil and partly decouple C distribution in top and sub soil. We investigate the influence of different soil type and environment. We observed the C and 14C distribution in paddy and non-paddy soil profiles in three different soil types from four different climatic regions of tropical Indonesia, and subtropical China. Locations were Sukabumi (Andosol, ca. 850 m a.s.l), Bogor (clayey Alisol, ca. 240 m a.s.l), and Ngawi (Vertisol, ca. 70 m a.s.l) in Jawa, Indonesia, and Cixi (Alisol(sandy), ca. 4 - 6 m a.s.l) in Zhejiang Province, China. We compared rice paddies with selected neighbouring non-paddy fields and employed AMS 14C as a tool to study C dynamics from bulk, alkali soluble-humic, and insoluble humin samples, and macrofossils (plant remains, charcoal). Our data suggest that vegetation type determines the quantity and quality of biomass introduced as litter and root material in top and subsoil, and thus contributes to the soil C content and profile, which fits the 14C signal distribution, as well as 13C in Ngawi with C4 sugar cane as upland crop. 14C concentrations for the mobile humic acid fraction were generally higher than for bulk samples from the same depth, except when recent plant and root debris led to high 14C levels in near-surface samples. The difference in sampling, - averaged layer for bulk sample and 1-cm layer thickness for point sample - shows gradients in C and 14C across the layers, which could be a reason for discrepancies between the two. High 14C concentrations - in Andosol Sukabumi up to 111 pMC - exceed the atmospheric 14CO2concentration in the sampling year in 2012 (˜ 103 pMC) and

  7. 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.

  8. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2007-06-01

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

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

    SciTech Connect

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

    2005-09-08

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

  11. 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.

  12. Characterization of 14C in Neutron-Irradiated Graphite

    NASA Astrophysics Data System (ADS)

    LaBrier, Daniel Patrick

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

  13. 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.

  14. Search for exotic cluster configurations in 14C nucleus

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

  15. 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.

  16. (14)C levels in the vicinity of the Fukushima Dai-ichi Nuclear Power Plant prior to the 2011 accident.

    PubMed

    Xu, Sheng; Cook, Gordon T; Cresswell, Alan J; Dunbar, Elaine; Freeman, Stewart P H T; Hastie, Helen; Hou, Xiaolin; Jacobsson, Piotr; Naysmith, Philip; Sanderson, David C W; Tripney, Brian G; Yamaguchi, Katsuhiko

    2016-06-01

    A 50-year-old Japanese cedar (Cryptomeria japonica) from Okuma, ∼1 km southwest of the Fukushima Dai-ichi Nuclear Power Plant, was cored and each annual ring was analysed for (14)C. The (14)C specific activity values varied from 330.4 Bq kg(-1) C in the tree ring formed in 1971 to 231.2 Bq kg(-1) C in the 2014 ring. During the periods 1971-1976 and 2011-2014, the (14)C specific activities are indistinguishable from the ambient background values. However, compared with the ambient atmospheric levels, the (14)C specific activities between 1977 and 2010 are significantly elevated, clearly indicating (14)C discharges from the reactors during their normal operations. In addition, the specific activities are positively correlated with the annual electricity generation values. The excess (14)C specific activities were <36 Bq kg(-1) C, corresponding to an additional annual effective dose of <2 μSv via the food ingestion pathway in the study location. The primary wind direction is east-southeast/southeast with a frequency of ∼30%, in comparison to ∼20% frequency for the direction of the site under study (north-northeast/northeast). This would tend to indicate a similar magnitude of additional effective dose and consequently no significant radiological impact of atmospheric (14)C discharges from the FDNPP during the entire period of normal operations. Additionally, no (14)C pulse in activity can be observed in the year 2011 ring. This might be caused by a limited (14)C release from the damaged reactors during the accident or that the prevailing wind during the short period of release (11th-25th March 2011) was not in the direction of Okuma. PMID:27023156

  17. (14)C levels in the vicinity of the Fukushima Dai-ichi Nuclear Power Plant prior to the 2011 accident.

    PubMed

    Xu, Sheng; Cook, Gordon T; Cresswell, Alan J; Dunbar, Elaine; Freeman, Stewart P H T; Hastie, Helen; Hou, Xiaolin; Jacobsson, Piotr; Naysmith, Philip; Sanderson, David C W; Tripney, Brian G; Yamaguchi, Katsuhiko

    2016-06-01

    A 50-year-old Japanese cedar (Cryptomeria japonica) from Okuma, ∼1 km southwest of the Fukushima Dai-ichi Nuclear Power Plant, was cored and each annual ring was analysed for (14)C. The (14)C specific activity values varied from 330.4 Bq kg(-1) C in the tree ring formed in 1971 to 231.2 Bq kg(-1) C in the 2014 ring. During the periods 1971-1976 and 2011-2014, the (14)C specific activities are indistinguishable from the ambient background values. However, compared with the ambient atmospheric levels, the (14)C specific activities between 1977 and 2010 are significantly elevated, clearly indicating (14)C discharges from the reactors during their normal operations. In addition, the specific activities are positively correlated with the annual electricity generation values. The excess (14)C specific activities were <36 Bq kg(-1) C, corresponding to an additional annual effective dose of <2 μSv via the food ingestion pathway in the study location. The primary wind direction is east-southeast/southeast with a frequency of ∼30%, in comparison to ∼20% frequency for the direction of the site under study (north-northeast/northeast). This would tend to indicate a similar magnitude of additional effective dose and consequently no significant radiological impact of atmospheric (14)C discharges from the FDNPP during the entire period of normal operations. Additionally, no (14)C pulse in activity can be observed in the year 2011 ring. This might be caused by a limited (14)C release from the damaged reactors during the accident or that the prevailing wind during the short period of release (11th-25th March 2011) was not in the direction of Okuma.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

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

    SciTech Connect

    Brand, B.; Boos, W. )

    1989-09-01

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

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

    SciTech Connect

    Gomes, P. R. S.

    2007-10-26

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

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

    SciTech Connect

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

    1981-09-01

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

  2. 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

  3. 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

  4. Decomposition of [14C]Lignocelluloses of Spartina alterniflora and a Comparison with Field Experiments

    PubMed Central

    Wilson, John O.

    1985-01-01

    Decomposition of lignocelluloses from Spartina alterniflora in salt-marsh sediments was measured by using 14C-labeled compounds. Rates of decomposition were fastest in the first 4 days of incubation and declined later. Lignins labeled in side chains were mineralized slightly faster than uniformly labeled lignins; 12% of the [side chain-14C]lignin-labeled lignocellulose was mineralized after 816 h of incubation, whereas only 8% of the [U-14C]lignin-labeled lignocelluloses were degraded during this period. The carbohydrate moiety within the lignocellulose complex was degraded about four times faster than the lignin moiety; after 816 h of incubation, 29 to 37% of the carbohydrate moiety had been mineralized. Changes in concentration of lignin and cellulose in litter of S. alterniflora were followed over 2 years of decay. Cellulose disappeared from litter more rapidly than lignin; 50% of the initial content of cellulose was lost after 130 days, whereas lignin required 330 to 380 days for 50% loss. The slow loss of lignin compared with other litter components resulted in a progressive enrichment of litter in lignin content. The rates of mineralization of [14C]lignocelluloses in marsh sediments were similar to the rates of lignocellulose decomposition in litter on the marsh. PMID:16346741

  5. Differential induction of (/sup 14/C)benzo(a)pyrene metabolism in tissues of the rat placenta

    SciTech Connect

    Salhab, A.; James, M.O.; Wang, S.L.; Shiverick, K.T.

    1986-03-01

    The authors have previously reported the differential induction by ..beta..-naphthaflavone (..beta.. NF) of ethoxyresorufin-O-deethylase activity in the labyrinth (LA) tissue of the rat placenta. This study characterized the metabolism of (/sup 14/C)benzo(a)pyrene (BP) in microsomes prepared from the respective LA and basal zone (BZ) portions of the placenta. Pregnant rats (day 14 gestation) received ..beta.. NF (15 mg/kg, i.p.) or 3-methylcholanthrene (3 MC; 30 mg/kg, i.p.). On day 15 placental were dissected and microsomes were incubated with 16 ..mu.. M (/sup 14/C)BP and 10 mM NADPH. BP metabolites were separated by HPLC on a reverse phase column. Only trace BP metabolism occurred in BZ microsomes from control (C), ..beta.. NF- or 3MC- animals, or in LA microsomes from C animals. In contrast, LA microsomes from ..beta.. NF and 3MC rats actively converted BP to quinone (Q), phenolic (OH) and diol (D) products. Product formation in LA microsomes from 5 ..beta.. NF-animals was as follows: 1,6-Q, 0.86 +/- 0.18 pmoles/mg protein/min (X +/- SE); 3,6-Q, 0.80 +/- 0.21; 6,12-Q, 0.56 +/- 0.16; 9-OH, 0.44 +/- 0.13; 3-OH and 7-OH, 0.32 +/- 0.11; 4,5-D, 0.15 +/- 0.05; 7,8-D, 0.15 +/- 0.05; and 9,10-D, 0.04 +/- 0.01. The same pattern of BP metabolism was observed in LA microsomes from 3MC-animals, with quinones being the predominant product. Thus, data confirm that the labyrinth tissue is the major site of xenobiotic induction and metabolism in the rat placenta.

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

    PubMed Central

    Veen, Henk; Jacobs, William P.

    1969-01-01

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

  7. Recent chronologies for tree rings and terrestrial archives using 14C bomb fallout history

    NASA Astrophysics Data System (ADS)

    McGee, E. J.; Gallagher, D.; Mitchell, P. I.; Baillie, M.; Brown, D.; Keogh, S. M.

    2004-06-01

    Tree rings representing the period from the mid-1950s up to 2001 were studied as part of an investigation of anthropogenic radionuclide input to terrestrial systems. A live specimen of Pinus sylvestris from the east coast of Ireland was felled, sampled and analysed for comparison with a similar tree felled close to the Atlantic seaboard on the west coast of Ireland. Data for the tree ring sequences were examined relative to the radionuclide content of peat profiles sampled in close proximity to the locations of the studied Pine trees. The data indicate that 14C concentrations in tree ring sequences from the east and west coasts of Ireland are virtually identical. The sequences show maximum 14C concentrations (185 and 189 pMC at east and west coast sites, respectively) that correspond closely with published data for atmospheric levels during the height of the nuclear weapons test period (1945-1980). The tree ring count for the specimen from the east coast places the 14C peak precisely at 1964, the year following the known peak in atmospheric concentrations due to above ground testing of nuclear weapons. However, 14C data show that simple ring counting of the west coast tree did not provide an accurate chronology. The data demonstrate the importance of applying dendrodating techniques using replicated site chronologies, and the value of the 14C bomb fallout curve for the construction of recent chronologies. Data show no evidence of enhanced uptake at the east coast that might suggest incorporation of output from the Sellafield nuclear complex or from the release of radioactivity resulting from an accidental fire at the plant in 1957.

  8. Reconciling Change in Oi-Horizon 14C With Mass Loss for an Oak Forest

    SciTech Connect

    Hanson, P J; Swanston, C W; Garten, Jr., C T; Todd, D E; Trumbore, S E

    2005-06-27

    First-year litter decomposition was estimated for an upland-oak forest ecosystem using enrichment or dilution of the {sup 14}C-signature of the Oi-horizon. These isotopically-based mass-loss estimates were contrasted with measured mass-loss rates from past litterbag studies. Mass-loss derived from changes in the {sup 14}C-signature of the Oi-horizon suggested mean mass loss over 9 months of 45% which was higher than the corresponding 9-month rate extrapolated from litterbag studies ({approx}35%). Greater mass loss was expected from the isotopic approach because litterbags are known to limit mass loss processes driven by soil macrofauna (e.g., fragmentation and comminution). Although the {sup 14}C-isotope approach offers the advantage of being a non-invasive method, it exhibited high variability that undermined its utility as an alternative to routine litterbag mass loss methods. However, the {sup 14}C approach measures the residence time of C in the leaf litter, rather than the time it takes for leaves to disappear; hence radiocarbon measures are subject to C immobilization and recycling in the microbial pool, and do not necessarily reflect results from litterbag mass loss. The commonly applied two-compartment isotopic mixing model was appropriate for estimating decomposition from isotopic enrichment of near-background soils, but it produced divergent results for isotopic dilution of a multi-layered system with litter cohorts having independent {sup 14}C-signatures. This discrepancy suggests that cohort-based models are needed to adequately capture the complex processes involved in carbon transport associated with litter mass-loss. Such models will be crucial for predicting intra- and interannual differences in organic horizon decomposition driven by scenarios of climatic change.

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

    SciTech Connect

    Norris, D.M.

    1980-08-01

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

  10. Comparison of five soil organic matter decomposition models using data from a 14C and 15N labeling field experiment

    NASA Astrophysics Data System (ADS)

    Pansu, Marc; Bottner, Pierre; Sarmiento, Lina; Metselaar, Klaas

    2004-12-01

    Five alternatives of the previously published MOMOS model (MOMOS-2 to -6) are tested to predict the dynamics of carbon (C) and nitrogen (N) in soil during the decomposition of plant necromass. 14C and 15N labeled wheat straw was incubated over 2 years in fallow soils of the high Andean Paramo of Venezuela. The following data were collected: soil moisture, total 14C and 15N and microbial biomass (MB)-14C and -15N, daily rainfall, air temperature and total radiation. Daily soil moisture was predicted using the SAHEL model. MOMOS-2 to -4 (type 1 models) use kinetic constants and flow partitioning parameters. MOMOS-2 can be simplified to MOMOS-3 and further to MOMOS-4, with no significant changes in the prediction accuracy and robustness for total-14C and -15N as well as for MB-14C and -15N. MOMOS-5 (type 2 models) uses only kinetic constants: three MB-inputs (from labile and stable plant material and from humified compounds) and two MB-outputs (mortality and respiration constants). MOMOS-5 did not significantly change the total-14C and -15N predictions but markedly improved the predictive quality and robustness of MB-14C and -15N predictions (with a dynamic different from the predictions by other models). Thus MOMOS-5 is proposed as an accurate and ecologically consistent description of decomposition processes. MOMOS-6 extends MOMOS-5 by including a stable humus compartment for long-term simulations of soil native C and N. The improvement of the predictions is not significant for this 2-year experiment, but MOMOS-6 enables prediction of a sequestration in the stable humus compartment of 2% of the initially added 14C and 5.4% of the added 15N.

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

    PubMed

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

    2014-01-01

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

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

    PubMed Central

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

    2014-01-01

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

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

    PubMed

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

    2010-02-01

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

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

    PubMed Central

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

    1979-01-01

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

  15. Testing the 14C ages and conservative behavior of dissolved 14C in a carbonate aquifer in Yucca Flat, Nevada (USA), using 36Cl from groundwater and packrat middens

    NASA Astrophysics Data System (ADS)

    Kwicklis, Edward; Farnham, Irene

    2014-09-01

    Corrected groundwater 14C ages from the carbonate aquifer in Yucca Flat at the former Nevada Test Site (now the Nevada National Security Site), USA, were evaluated by comparing temporal variations of groundwater 36Cl/Cl estimated with these 14C ages with published records of meteoric 36Cl/Cl variations preserved in packrat middens (piles of plant fragments, fecal matter and urine). Good agreement between these records indicates that the groundwater 14C ages are reasonable and that 14C is moving with chloride without sorbing to the carbonate rock matrix or fracture coatings, despite opposing evidence from laboratory experiments. The groundwater 14C ages are consistent with other hydrologic evidence that indicates significant basin infiltration ceased 8,000 to 10,000 years ago, and that recharge to the carbonate aquifer is from paleowater draining through overlying tuff confining units along major faults. This interpretation is supported by the relative age differences as well as hydraulic head differences between the alluvial and volcanic aquifers and the carbonate aquifer. The carbonate aquifer 14C ages suggest that groundwater velocities throughout much of Yucca Flat are about 2 m/yr, consistent with the long-held conceptual model that blocking ridges of low-permeability rock hydrologically isolate the carbonate aquifer in Yucca Flat from the outlying regional carbonate flow system.

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

    PubMed

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

    2015-09-01

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

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

    NASA Astrophysics Data System (ADS)

    Ohkubo, S.; Hirabayashi, Y.

    2015-08-01

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

  18. 14C content in aerosols in Mexico City

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

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

    SciTech Connect

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

    1986-04-01

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

  20. 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

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

    SciTech Connect

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

    1995-12-31

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

  2. Analysis of Silicate Melt Inclusions in Plagioclase Phenocrysts in Prehistoric Tephra ˜1400 Years B.P. From Augustine Volcano, Alaska.

    NASA Astrophysics Data System (ADS)

    Tappen, C. M.; Webster, J. D.; Mandeville, C. W.

    2003-12-01

    Augustine volcano, located in southern Cook Inlet, Alaska, has been historically active, erupting 6 times in the last 200 years. Eruptions first began prior to 40,000 years B.P. (Begét and Kienle, 1992). There are a minimum of 6 prehistoric tephra layers, G (oldest), I, H, C, M and B (youngest), present on Augustine Island (Waitt et al, 1996). In this study, we analyzed glassy silicate melt inclusions in plagioclase phenocrysts from tephra layer H ( ˜1400 years B.P.) for major and minor and some trace elements (Cl, F, S, Ba, and Sr) by electron microprobe. We use the data to determine the chemical variation of melt inclusions in specific locations within zoned plagioclase phenocrysts. Plagioclase phenocrysts (0.5 to 4 mm long) exhibit unzoned, oscillatory or patchy zoned regions. Unzoned phenocryst cores lack melt inclusions. Patchy zonation occurs in cores and is sometimes found in intermediate zones between the core and rim. Planar oscillatory zones are distinguished in BSE images by light (An56-90) and dark (An46-55) bands. In some phenocrysts light and dark layers differ only by 1% An. Most phenocrysts show 2-3 repeated oscillating pairs of light and dark plagioclase compositional layers. Normal and reverse zoning are apparent in phenocrysts. Rims tend to be more calcic than the cores, varying from 1-5% An. Large melt inclusions (60 to 70 μ m long) are located in patchy zoned cores. Small melt inclusions (2 to 10 μ m long) are located at the contact of high calcic and low calcic oscillatory layers. All melt inclusions are trapped along compositional boundaries and occur in the more calcic plagioclase. Petrography suggests that melt inclusions may have been formed by partial dissolution of a less calcic plagioclase layer. The composition of the melt inclusions are rhyolitic (71 to 75% SiO2). The chlorine concentrations range from 3020 to 6100 ppm with the more chlorine enriched concentrations occurring in the outer rims of the phenocryst. Sr and Ba vary from

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

    SciTech Connect

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

    1983-11-01

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

  4. 17 CFR 240.14c-3 - Annual report to be furnished security holders.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

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

  5. 17 CFR 240.14c-3 - Annual report to be furnished security holders.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

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

  6. Tree-ring 14C and CO2 emissions at Mammoth Mountain and Yellowstone, USA

    NASA Astrophysics Data System (ADS)

    Bergfeld, D.; McGeehin, J. P.; King, J.; Heasler, H.; Evans, W. C.

    2010-12-01

    A large pulse of magmatic CO2 began venting through soils on the flanks of Mammoth Mountain CA within months of a local seismic swarm in 1989. Previous workers have shown that the CO2 efflux rate was large enough to kill ~0.5 km2 of forest and cause substantial depletion of 14C in the wood of surviving trees at the edges of the kill zones. CO2 efflux at Mammoth Mountain continues to be well-studied, in part because of the obvious link between the seismic swarm and the onset of outgassing. A somewhat similar event apparently occurred a decade previously in the Yellowstone caldera, where we see a record of 14C depletion of 10-25% in a tree at Cooking Hillside in the Mud Volcano area. The 14C levels in tree core data show that CO2 emissions began to increase during a local seismic swarm in 1978. A huge drop in 14C in the 1979 growth ring suggests that CO2 emissions increased about 5-fold over values earlier in the decade. The emissions spike persisted into 1980 but at greatly reduced levels. This event at Mud Volcano occurred in a thermal area long known to emit CO2 gas and was associated with a substantial increase in surface heating and steam emission, in contrast to the case of Mammoth Mountain. However, the two events share some important similarities: increased CO2 emissions began within months of the onset of shallow (<7 km) seismic swarms, emissions peaked within 1-2 years later, and peak emissions are estimated at ~1000 tonnes of CO2 per day. Seismicity in both cases was likely driven by CO2-rich hydrous fluids; intrusion of magma into the shallow crust seems unlikely, particularly at Yellowstone where the youngest intra-caldera lavas are 70 ka. These similarities imply that, while each event has unique attributes, both are more likely variants on a process that may be fairly common in areas of magmatism. Additional tree coring at Mammoth Mountain will allow a direct comparison between 14C depletion and annual CO2 flux surveys. Ongoing tree-core 14C studies at

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

    SciTech Connect

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

    1993-08-15

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

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

    SciTech Connect

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

    1999-03-25

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

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

    PubMed Central

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

    1973-01-01

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

  10. Ozone exposure alters temporal fluctuations of sup 14 C-labeled assimilate pools in leaves of Pinus taeda L

    SciTech Connect

    Friend, A.L. ); Tomlinson, P.T. )

    1991-05-01

    The effects of O{sub 3} on uptake and distribution of {sup 14}C within current-year foliage of 3-year-old loblolly pine (Pinus taeda L.) seedlings were studied using open-top exposure chambers that delivered ozone at three concentrations: sub-ambient O{sub 3} (charcoal-filtered air (CF)); ambient O{sub 3}(AMB); and twice-ambient O{sub 3} (2X). Seedlings were exposed to O{sub 3} from May to Oct. of 1987, 1988, and 1989. In July, Aug., and Sept. 1989, individual foliage fascicles were labeled with {sup 14}CO{sub 2}; harvested at 0, 0.5, 4, 24, and 48h after labeling; and analyzed for {sup 14}C in lipids and pigments, protein, starch, residue, sugars, organic acids, and amino acids. O{sub 3} affected initial (0 h) incorporation of {sup 14}C into different chemical fractions, and the relative distribution of {sup 14}C among fractions at specific points in time. Starch dynamics were particularly responsive to and negatively affected by O{sub 3}. In 2X treatments, only 39-46% of the initial (0 h) {sup 14}C incorporated into starch remained after 48h, compared with a range of 56-90% remaining in CF treatments. The percentage of {sup 14}C in the starch fraction after 48 h decreased by nearly three-fold in August from CF to 2X treatments (%total {sup 14}C in starch: 31% (CF), 17% (AMB), and 11% (2X)). The authors data indicated that foliar starch synthesis and/or retention was depressed by ozone exposure during late-season months, and supported the concept that O{sub 3} decreases growth by depleting carbohydrate reserves. Other findings will be discussed.

  11. Impacts of (14)C discharges from a nuclear fuel reprocessing plant on surrounding vegetation: Comparison between grass field measurements and TOCATTA-χ and SSPAM(14)C model computations.

    PubMed

    Limer, Laura M C; Le Dizès-Maurel, Séverine; Klos, Ryk; Maro, Denis; Nordén, Maria

    2015-09-01

    This article compares and discusses the ability of two different models to reproduce the observed temporal variability in grass (14)C activity in the vicinity of AREVA-NC La Hague nuclear fuel reprocessing plant in France. These two models are the TOCATTA-χ model, which is specifically designed for modelling transfer of (14)C (and tritium) in the terrestrial environment over short to medium timescales (days to years), and SSPAM(14)C, which has been developed to model the transfer of (14)C in the soil-plant-atmosphere with consideration over both short and long timescales (days to thousands of years). The main goal of this article is to discuss the strengths and weaknesses of the models studied, and to investigate if modelling could be improved through consideration of a much higher level of detail of plant physiology and/or higher number of plant compartments. These models have been applied here to the La Hague field data as it represents a medium term data set with both short term variation and a sizeable time series of measurements against which to compare the models. The two models have different objectives in terms of the timescales they are intended to be applied over, and thus incorporate biological processes, such as photosynthesis and plant growth, at different levels of complexity. It was found that the inclusion of seasonal dynamics in the models improved predictions of the specific activity in grass for such a source term of atmospheric (14)C. PMID:26063400

  12. Impacts of (14)C discharges from a nuclear fuel reprocessing plant on surrounding vegetation: Comparison between grass field measurements and TOCATTA-χ and SSPAM(14)C model computations.

    PubMed

    Limer, Laura M C; Le Dizès-Maurel, Séverine; Klos, Ryk; Maro, Denis; Nordén, Maria

    2015-09-01

    This article compares and discusses the ability of two different models to reproduce the observed temporal variability in grass (14)C activity in the vicinity of AREVA-NC La Hague nuclear fuel reprocessing plant in France. These two models are the TOCATTA-χ model, which is specifically designed for modelling transfer of (14)C (and tritium) in the terrestrial environment over short to medium timescales (days to years), and SSPAM(14)C, which has been developed to model the transfer of (14)C in the soil-plant-atmosphere with consideration over both short and long timescales (days to thousands of years). The main goal of this article is to discuss the strengths and weaknesses of the models studied, and to investigate if modelling could be improved through consideration of a much higher level of detail of plant physiology and/or higher number of plant compartments. These models have been applied here to the La Hague field data as it represents a medium term data set with both short term variation and a sizeable time series of measurements against which to compare the models. The two models have different objectives in terms of the timescales they are intended to be applied over, and thus incorporate biological processes, such as photosynthesis and plant growth, at different levels of complexity. It was found that the inclusion of seasonal dynamics in the models improved predictions of the specific activity in grass for such a source term of atmospheric (14)C.

  13. Evidence for stagnation of the Harvard sublobe (Lake Michigan lobe) in Northeastern Illinois, U.S.A., from 24 000 to 17 600 BP and subsequent tundra-like ice-marginal paleoenvironments from 17 600 to 15 700 BP

    USGS Publications Warehouse

    Curry, B. Brandon; Yansa, C.H.

    2004-01-01

    Glacial deposits of the last glaciation associated with the Harvard sublobe (Lake Michigan lobe) in northeastern Illinois, U.S.A., occur between sediment with dateable organics. The lower organics include fragments of Picea sp. as young as 24 000 ?? 270 BP. The supraglacial organics occur sparsely in laminated silt and fine sand in landforms that are positioned relatively high on the landscape, such as deposits from ice-walled lakes. These terrestrial organics yield ages that are 2500 to 1300 14C years older than organics at the base of sediment successions in nearby kettle basins. Basal 14C ages from four upland sites range from 17 610 ?? 270 to 16 120 ?? 80 BP. Our revised time-distance diagram of the Harvard sublobe now reflects a period of stagnation from 24 000 to about 17 600 BP. The supraglacial lacustrine silt yielded plant macrofossil assemblages of primarily tundra plants, including Salix herbacea and Dryas integrifolia. These plants likely grew in supraglacial and ice-marginal environments. The ostracode fauna include Cytherissa lacustris and Limnocythere friabilis. Geomorphic relations and ostracode ecology indicate that more than 17 m of ice buttressed some of the supraglacial lakes.

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  15. Crystallization conditions and petrogenesis of the lava dome from the ˜900 years BP eruption of Cerro Machín Volcano, Colombia

    NASA Astrophysics Data System (ADS)

    Laeger, Kathrin; Halama, Ralf; Hansteen, Thor; Savov, Ivan P.; Murcia, Hugo F.; Cortés, Gloria P.; Garbe-Schönberg, Dieter

    2013-12-01

    The last known eruption at Cerro Machín Volcano (CMV) in the Central Cordillera of Colombia occurred ˜900 years BP and ended with the formation of a dacitic lava dome. The dome rocks contain both normally and reversely zoned plagioclase (An24-54), unzoned and reversely zoned amphiboles of dominantly tschermakite and pargasite/magnesio-hastingsite composition and olivine xenocrysts (Fo = 85-88) with amphibole/clinopyroxene overgrowth, all suggesting interaction with mafic magma at depth. Plagioclase additionally exhibits complex oscillatory zoning patterns reflecting repeated replenishment, fractionation and changes in intrinsic conditions in the magma reservoir. Unzoned amphiboles and cores of the reversely zoned amphiboles give identical crystallization conditions of 910 ± 30 °C and 360 ± 70 MPa, corresponding to a depth of about 13 ± 2 km, at moderately oxidized conditions (f = +0.5 ± 0.2 ΔNNO). The water content in the melt, calculated based on amphibole chemistry, is 7.1 ± 0.4 wt.%. Rims of the reversely zoned amphiboles are relatively enriched in MgO and yield higher crystallization temperatures (T = 970 ± 25 °C), slightly lower melt H2O contents (6.1 ± 0.7 wt.%) and overlapping pressures (410 ± 100 MPa). We suggest that these rims crystallized following an influx of mafic melt into a resident magma reservoir at mid-crustal depths, further supported by the occurrence of xenocrystic olivine. Crystallization of biotite, albite-rich plagioclase and quartz occurred at comparatively low temperatures (probably <800 °C) during early stages of ascent or storage at shallower levels. Based on amphibole mineral chemistry, the felsic resident melt had a rhyolitic composition (71 ± 2 wt.% SiO2), whereas the hybrid magma, from which the amphibole rims crystallized, was dacitic (64 ± 3 wt.% SiO2). The bulk rock chemistry of the CMV lava dome dacites is homogenous. They have elevated (La/Nb)N ratios of 3.8-4.5, typical for convergent margin magmas, and display

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

    PubMed

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

    1982-05-01

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

  17. Flux of carbon from 14C-enriched leaf litter throughout a forest soil mesocosm

    SciTech Connect

    Froberg, Mats J.; Hanson, Paul J; Trumbore, Susan E.; Swanston, Christopher W.; Todd Jr, Donald E

    2009-01-01

    The role of DOC for the build-up of soil organic carbon pools is still not well known, but it is thought to play a role in the transport of carbon to a greater depth where it becomes more stable. The aim of this study was to elucidate within-year dynamics of carbon transport from litter to the O (Oe and Oa) and A horizons. Mesocosms with constructed soil profiles were used to study dynamics of C transport from 14C-enriched (about 1000 ) leaf litter to the Oe/Oa and A horizons as well as the mineralization of leaf litter. The mesocosms were placed in the field for 17 months during which time fluxes and 14C content of DOC and CO2 were measured. Changes in 14C in leaf litter and bulk soil C pools were also recorded. Significant simultaneous release and immobilization of DOC occurring in both the O and A horizons was hypothesized. Contrary to our hypothesis, DOC released from the labeled Oi horizon was not retained within the Oe/Oa layer. DOC originating in the unlabeled Oe/Oa layer was also released for transport. Extensive retention of DOC occurred in the A horizon. DOC leaching from A horizon consisted of a mix of DOC from different sources, with a main fraction originating in the A horizon and a smaller fraction leached from the overlaying horizons. The C and 14C budget for the litter layer also indicated a surprisingly large amount of carbon with ambient Δ14C-signature to be respired from this layer. Data for this site also suggested significant contributions from throughfall to dissolved organic carbon (DOC) transport into and respiration from the litter layer. The results from this study showed that DOC retentionwas low in the O horizon and therefore not important for the O horizon carbon budget. In the A horizon DOC retention was extensive, but annual DOC input was small compared to C stocks and therefore not important for changes in soil C on an annual timescale.

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

    SciTech Connect

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

    1990-03-01

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

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

    SciTech Connect

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

    1985-01-01

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

  20. 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

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

    PubMed

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

    2011-06-15

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

  2. 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

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

    SciTech Connect

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

    1990-10-01

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

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

    SciTech Connect

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

    1993-01-01

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

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

    EPA Science Inventory

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

  6. (14)C, delta(13)C and total C content in soils around a Brazilian PWR nuclear power plant.

    PubMed

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

    2009-04-01

    Nuclear power plants release (14)C during routine operation mainly as airborne gaseous effluents. Because of the long half-life (5730 years) and biological importance of this radionuclide (it is incorporated in plant tissue by photosynthesis), several countries have monitoring programs in order to quantify and control these emissions. This paper compares the activity of (14)C in soils taken within 1km from a Brazilian nuclear power plant with soils taken within a reference area located 50km away from the reactor site. Analyses of total carbon, delta(13)C and (137)Cs were also performed in order to understand the local soil dynamics. Except for one of the profiles, the isotopic composition of soil organic carbon reflected the actual forest vegetation present in both areas. The (137)Cs data show that the soils from the base of hills are probably allocthonous. The (14)C measurements showed that there is no accumulation due to the operation of the nuclear facility, although excess (14)C was found in the litter taken in the area close to power plant. This indicates that the anthropogenic signal observed in the litter fall has not been transferred yet to the soil. This study is part of an extensive research programme in which other samples including air, vegetation and gaseous effluents (taken in the vent stack of the Brazilian nuclear power reactors Angra I and II) were also analyzed. The present paper aimed to evaluate how (14)C emissions from the nuclear power plant are transferred and stored by soils present in the surroundings of the reactor site. This is the first study concerning anthropogenic (14)C in soils in Brazil.

  7. 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.

  8. Comparison of 14C ages of hydrothermal petroleums

    USGS Publications Warehouse

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

    1994-01-01

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

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

    SciTech Connect

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

    1990-11-01

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

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

    PubMed Central

    Andersen, Gidske L; Krzywinski, Knut

    2007-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  12. Whole Ecosystem Low-level 14C Pulse Labeling and CO2 Flux Measurements in a Boreal Forest

    NASA Astrophysics Data System (ADS)

    Carbone, M.; Trumbore, S.; Czimczik, C.; McDuffee, K.; McMillan, A.

    2004-12-01

    We developed a large volume, low level, 14C pulse-chase, field labeling method to determine the timing and contribution of recent photosynthetic products to total ecosystem respiration in a poorly drained black spruce forest stand in Manitoba, Canada. The site is part of a chronosequence of black spruce stands located in the BOREAS Northern Study Area (55N, 98W), and time since fire is 40 years. The radiocarbon addition was designed to produce a 14C signature of ~1500 times Modern for CO2 at ambient levels inside the ~37,000 L volume light chamber. At this level of labeling, the radioactivity in our 14C source (acidified sodium bicarbonate solution with specific activity of ~30 nCi/g) and in the chamber were well below levels that are regulated. We labeled two chambers in August 2004. The vegetation inside the first (37,000 L) chamber included black spruce trees (ranging from seedlings to 4 m tall) with feather moss and shrub understory. A second 14CO2 label was applied in a smaller chamber (500 L) containing only feather mosses. Both chambers were constructed from polyethylene plastic that allowed for 70 percent transmission of PAR. For seven days following the label, we measured the quantity and 14C content of soil respiration with small (10 L) dark chambers, above-ground respiration with branch bags, and total ecosystem respiration with a dark chamber. Live root and moss 14C content were measured by field incubations. Additionally, soil gas 14C content at two depths within the moss/organic layer was measured. Radiocarbon measurements are made using Accelerator Mass Spectrometry, which allows us to easily distinguish the presence of the label in small amounts (mg) of material. We will report the radiocarbon (delta 14C) signature of individual respiration sources. Preliminary results show that we can use these isotopic signatures to follow the labeled contribution of respiration from individual sources (moss, root/root exudates, and needle) to total ecosystem

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

    PubMed

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

    2010-03-01

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

  14. Molecular, 13C, and 14C evidence for the allochthonous and ancient origin of C 16C 18n-alkanes in modern soils

    NASA Astrophysics Data System (ADS)

    Lichtfouse, Éric; Bardoux, Gerard; Mariotti, Andre; Balesdent, Jerome; Ballentine, Donna C.; Macko, Stephen A.

    1997-05-01

    The heterogeneous isotopic composition of C 3 and C 4 plants can be used to to follow the fate of plant carbon into soil organic molecules. Thus, after 23 years of maize cropping (C 4) on a soil which was previously under C 3 vegetation, C 25C 33 soil n-alkanes are 13C-enriched up to 9ℵ. relatively to the initial C 3 soil, reflecting the input of 13C-enriched n-alkanes from maize waxes. In sharp contrast, C 16C 18 soil n-alkanes do not show any significant 13C/ 12C variation over the same time interval. This absence of isotopic variation, along with consideration of their relative concentration, absolute concentration, and biodegradability, demonstrate that these substances must represent a regular input from an external source. Evidence of a large contribution of an ancient source, amounting to more than 65% of the alkane fraction, is given by a 14C-age of 8510 yrs BP. Moreover, short-chain n-alkanes from soils, diesel fuel, diesel automobile exhaust, and petroleum products exhibit similar distributions and δ 13C values. These findings suggests that C 16C 18 soil n-alkanes represent a non-point source pollution of ancient hydrocarbons either carried by aerosols or entering the soil via continuous hydrocarbon seepage from the deep sedimentary rocks of the Paris basin.

  15. Accelerated degradation of 14C-atrazine in an atrazine adapted field soil from Belgium

    NASA Astrophysics Data System (ADS)

    Hamacher, Georg; Jablonowski, Nicolai David; Martinazzo, Rosane; Accinelli, Cesare; Köppchen, Stephan; Langen, Ulrike; Linden, Andreas; Krause, Martina; Burauel, Peter

    2010-05-01

    Atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] is one of the most widely used herbicides in the world. Atrazine is considered to be mobile in soil and has often been characterized as a rather recalcitrant compound in the environment. In the present study the accelerated atrazine degradation in an agriculturally used soil was examined. Soil samples were collected from a Belgian field which was used for corn-plantations and was regularly treated with atrazine during the last 30 years. The experiment was conducted under controlled laboratory conditions (GLP) using 14C-labelled and unlabelled atrazine in accordance to the reported field application dose of 1 mg kg-1. Triplicates of treated subsamples were incubated at 50% WHCmax and under slurry conditions (1:4 soil:solution ratio, using distilled water) in the dark at 20° C. Control samples were collected at an adjacent pear orchard where no atrazine or other triazine pesticides application was reported. After 92 days of incubation, the mineralized amount of atrazine reached 83% of the initially applied 14C-activity in the atrazine treated soil for the slurry setup. A maximum of atrazine mineralization was observed in the treated field soil between 6 and 7 days of incubation for both, 50% WHCmax and slurry setups. The total 14C-atrazine mineralization was equally high for 50% WHCmax in the atrazine treated soil. After an extended lag-phase in comparison to the treated soil the overall mineralization of 14C-atrazine of 81% was observed in the atrazine untreated soil under slurry conditions. This observation might be due to a possible cross adaption of the microflora. These results could be attributed to an atrazine drift during application since the control samples were taken in an adjacent pear orchard with no atrazine application history. These results demonstrate an adaption of the microflora to mineralize atrazine rapidly. The formation of desorbable metabolites as well as the formation of

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

    PubMed

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

    1992-04-01

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

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

    PubMed

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

    1992-04-01

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

  18. 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.

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

    SciTech Connect

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

    1989-03-01

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

  20. /sup 14/C distribution in roots following photosynthesis of the label in perennial plants in the northern Mojave Desert

    SciTech Connect

    Wallace, A.; Mueller, R.T.; Cha, J.W.; Romney, E.M.

    1980-01-01

    In April and May of 1973, 24 individual plants were exposed to /sup 14/CO/sub 2/ with techniques used in our other studies in the field. Seven to 8 months later, part of the plants were excavated and counted by plant part for /sup 14/C. The remainder of the plants were excavated at 13 months. The results indicated that from 3 to 20 percent of the carbon for leaves in the next year came from stems and roots of Grayia spinosa (Hook) Moq., Ceratoides lanata (Pursh) J. T. Howell, Atriplex confertifolia (Torr. and Frem.) S. Wats., Lycium pallidum Miers, Ambrosia dumosa (A. Gray) Payne, and Acamptopappus shockleyi A Gray. Nearly all of the root segments were labeled at sampling time; however, some of the roots were labeled at higher amounts than others. Some roots had very little /sup 14/C, and these are assumed to be very new roots rather than dead roots because of their small size. The roots with high levels of /sup 14/C are assumed to be formed near the time of labeling, and those with low levels to be formed after the time of labeling. From 17 to 65 percent of the /sup 14/C fixed was recovered after 7 to 13 months.

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

    NASA Astrophysics Data System (ADS)

    Kirchner, James; Jasechko, Scott

    2016-04-01

    "young" and "old" water fractions are therefore immune to the aggregation bias that afflicts MRT estimates. They are also relatively insensitive to the shape of the assumed residence time distribution. We apply this approach to 3H and 14C measurements from ˜5000 wells in ˜200 aquifers around the world. Our results show that even very old groundwaters, with 14C ages of thousands of years, often contain significant amounts of much younger water, with a substantial fraction of their age distributions younger than ˜100 years old. Thus despite being very old on average, these groundwaters may also be vulnerable to relatively recent contamination. [1] Kirchner J.W., Aggregation in environmental systems: Catchment mean transit times and young water fractions under hydrologic nonstationarity, Hydrology and Earth System Sciences, in press. [2] Kirchner J.W., Aggregation in environmental systems: Seasonal tracer cycles quantify young water fractions, but not mean transit times, in spatially heterogeneous catchments, Hydrology and Earth System Sciences, in press. [3] Jasechko S., Kirchner J.W., Welker J.M., and McDonnell J.J., Substantial young streamflow in global rivers, Nature Geoscience, in press.

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

    SciTech Connect

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

    1999-10-01

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

  3. 14C content in vegetation in the vicinities of Brazilian nuclear power reactors.

    PubMed

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

    2008-07-01

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

  4. Characterization of terrestrial organic matter transported through the Lena River Delta (NE Siberia) to its adjacent nearshore zone using lignin phenols, δ13C and ∆14C

    NASA Astrophysics Data System (ADS)

    Winterfeld, M.; Goni, M. A.; Just, J.; Hefter, J.; Han, P.; Mollenhauer, G.

    2014-12-01

    The Lena River in central Siberia is one of the major pathways translocating terrestrial organic matter (OMterr) from its southernmost reaches near Lake Baikal to the coastal zone of the Laptev Sea and the Arctic Ocean. Permafrost soils from its vast catchment area store huge amounts of pre-aged OM, which is expected to be remobilized due to climate warming. To characterize the composition and vegetation sources of OM discharged by the Lena River, we analyzed the lignin phenol and carbon isotopic composition (δ13C and ∆14C) in total suspended matter (TSM) from surface waters collected in spring and summer, surface sediments from the Buor Khaya Bay along with soils from the Lena Delta. A simple linear mixing model based on the lignin phenol distributions indicates OM in TSM samples from the delta and Buor Khaya Bay surface sediments contains comparable contributions from gymnosperm sources, which are primarily from the taiga forests south of the delta, and angiosperm material typical for tundra vegetation. Considering the small area covered by tundra (~12% of total catchment), the input of tundra-derived OM input is substantial and likely to increase in a warming Arctic. Radiocarbon compositions (∆14C) of bulk OM in TSM samples varied from -55 to -391‰, i.e. 14C ages of 395 to 3920 yrs BP. Using δ13C compositions to estimate the fraction of phytoplankton-derived OM and assuming that this material has a modern 14C signature, we inferred the ∆14C compositions of OMterr in TSM exported by the Lena River to range between -190 and -700‰. Such variability in the ages of OMTERR (i.e. 1640 to 9720 14C yrs BP) reflects the heterogeneous composition and residence time of OM in the Lena River catchment soils (Holocene to Pleistocene ages). Lignin phenol and ∆14C compositions of surface sediments from the adjacent Buor Khaya Bay suggest that OMTERR deposited there is older and more degraded than materials present in river particles and catchment soils. Stronger

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

    PubMed Central

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

    2006-01-01

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

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

    PubMed

    Stoker, Tammy E; Cooper, Ralph L

    2007-06-01

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

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

    SciTech Connect

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

    1987-01-01

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

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

    PubMed Central

    Turner, D. M.

    1971-01-01

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

  9. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

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

    PubMed

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

    2013-01-01

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

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

    PubMed Central

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

    2013-01-01

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

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

    PubMed

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

    1977-01-10

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

  14. 78 FR 60270 - BP America Inc., BP Corporation North America Inc., BP America Production Company, and BP Energy...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-01

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission BP America Inc., BP Corporation North America Inc., BP America Production Company, and BP Energy Company; Notice of Designation of Commission Staff as Non-Decisional With respect to an order issued by the Commission...

  15. Coral skeletal carbon isotopes (δ13C and Δ14C) record the delivery of terrestrial carbon to the coastal waters of Puerto Rico

    USGS Publications Warehouse

    Moyer, R.P.; Grottoli, A.G.

    2011-01-01

    Tropical small mountainous rivers deliver a poorly quantified, but potentially significant, amount of carbon to the world's oceans. However, few historical records of land-ocean carbon transfer exist for any region on Earth. Corals have the potential to provide such records, because they draw on dissolved inorganic carbon (DIC) for calcification. In temperate systems, the stable- (δ13C) and radiocarbon (Δ14C) isotopes of coastal DIC are influenced by the δ13C and Δ14C of the DIC transported from adjacent rivers. A similar pattern should exist in tropical coastal DIC and hence coral skeletons. Here, δ13C and Δ14C measurements were made in a 56-year-old Montastraea faveolata coral growing ~1 km from the mouth of the Rio Fajardo in eastern Puerto Rico. Additionally, the δ13C and Δ14C values of the DIC of the Rio Fajardo and its adjacent coastal waters were measured during two wet and dry seasons. Three major findings were observed: (1) synchronous depletions of both δ13C and Δ14C in the coral skeleton are annually coherent with the timing of peak river discharge, (2) riverine DIC was always more depleted in δ13C and Δ14C than seawater DIC, and (3) the correlation of δ13C and Δ14C was the same in both coral skeleton and the DIC of the river and coastal waters. These results indicate that coral skeletal δ13C and Δ14C are recording the delivery of riverine DIC to the coastal ocean. Thus, coral records could be used to develop proxies of historical land-ocean carbon flux for many tropical regions. Such information could be invaluable for understanding the role of tropical land-ocean carbon flux in the context of land-use change and global climate change.

  16. Coral skeletal carbon isotopes (δ13C and Δ14C) record the delivery of terrestrial carbon to the coastal waters of Puerto Rico

    USGS Publications Warehouse

    Moyer, R.P.; Grottoli, A.G.

    2011-01-01

    Tropical small mountainous rivers deliver a poorly quantified, but potentially significant, amount of carbon to the world's oceans. However, few historical records of land-ocean carbon transfer exist for any region on Earth. Corals have the potential to provide such records, because they draw on dissolved inorganic carbon (DIC) for calcification. In temperate systems, the stable- (??13C) and radiocarbon (??14C) isotopes of coastal DIC are influenced by the ??13C and ??14C of the DIC transported from adjacent rivers. A similar pattern should exist in tropical coastal DIC and hence coral skeletons. Here, ??13C and ??14C measurements were made in a 56-year-old Montastraea faveolata coral growing ~1 km from the mouth of the Rio Fajardo in eastern Puerto Rico. Additionally, the ??13C and ??14C values of the DIC of the Rio Fajardo and its adjacent coastal waters were measured during two wet and dry seasons. Three major findings were observed: (1) synchronous depletions of both ??13C and ??14C in the coral skeleton are annually coherent with the timing of peak river discharge, (2) riverine DIC was always more depleted in ??13C and ??14C than seawater DIC, and (3) the correlation of ??13C and ??14C was the same in both coral skeleton and the DIC of the river and coastal waters. These results indicate that coral skeletal ??13C and ??14C are recording the delivery of riverine DIC to the coastal ocean. Thus, coral records could be used to develop proxies of historical land-ocean carbon flux for many tropical regions. Such information could be invaluable for understanding the role of tropical land-ocean carbon flux in the context of land-use change and global climate change. ?? 2011 United States Geological Survey.

  17. Carbon transfer dynamics from bomb- 14C and δ 13C time series of a laminated stalagmite from SW France - modelling and comparison with other stalagmite records

    NASA Astrophysics Data System (ADS)

    Genty, Dominique; Massault, Marc

    1999-05-01

    Twenty-two AMS 14C measurements have been made on a modern stalagmite from SW France in order to reconstruct the 14C activity history of the calcite deposit. Annual growth laminae provides a chronology up to 1919 A.D. Results show that the stalagmite 14C activity time series is sensitive to modern atmosphere 14C activity changes such as those produced by the nuclear weapon tests. The comparison between the two 14C time series shows that the stalagmite time series is damped: its amplitude variation between pre-bomb and post-bomb values is 75% less and the time delay between the two time series peaks is 16 years ±3. A model is developed using atmosphere 14C and 13C data, fractionation processes and three soil organic matter components whose mean turnover rates are different. The linear correlation coefficient between modeled and measured activities is 0.99. These results, combined with two other stalagmite 14C time series already published and compared with local vegetation and climate, demonstrate that most of the carbon transfer dynamics are controlled in the soil by soil organic matter degradation rates. Where vegetation produces debris whose degradation is slow, the fraction of old carbon injected in the system increases, the observed 14C time series is much more damped and lag time longer than that observed under grassland sites. The same mixing model applied on the 13C shows a good agreement ( R2 = 0.78) between modeled and measured stalagmite δ 13C and demonstrates that the Suess Effect due to fossil fuel combustion in the atmosphere is recorded in the stalagmite but with a damped effect due to SOM degradation rate. The different sources of dead carbon in the seepage water are calculated and discussed.

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

    SciTech Connect

    Freer, M.

    2008-11-11

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

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

    SciTech Connect

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

    1986-03-01

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

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

    PubMed

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

    2013-07-17

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

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

    PubMed Central

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

    1993-01-01

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

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

    PubMed

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

    2013-07-17

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

  3. 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

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

    PubMed

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

    1992-01-01

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

  5. 14C BOMB-PULSE DATING AND STABLE ISOTOPE ANALYSIS FOR GROWTH RATE AND DIETARY INFORMATION IN BREAST CANCER?

    PubMed

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

    2016-06-01

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

  6. 14C BOMB-PULSE DATING AND STABLE ISOTOPE ANALYSIS FOR GROWTH RATE AND DIETARY INFORMATION IN BREAST CANCER?

    PubMed Central

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

    2016-01-01

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

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

    SciTech Connect

    Toggweiler, J.R. )

    1990-01-09

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

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

    PubMed

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

    1985-03-30

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

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

    PubMed

    Zezulka, Stěpán; Klemš, Marek; Kummerová, Marie

    2014-10-01

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

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

    SciTech Connect

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

    1980-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2007-06-01

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

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

    PubMed

    Hongo, Ryoko; Nakamura, Sadako; Oku, Tsuneyuki

    2010-01-01

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

  13. Reexposure and advection of 14C-depleted organic carbon from old deposits at the upper continental slope

    NASA Astrophysics Data System (ADS)

    Tesi, Tommaso; GoñI, Miguel A.; Langone, Leonardo; Puig, Pere; Canals, Miquel; Nittrouer, Charles A.; Durrieu de Madron, Xavier; Calafat, Antoni; Palanques, Albert; Heussner, Serge; Davies, Maureen H.; Drexler, Tina M.; Fabres, Joan; Miserocchi, Stefano

    2010-12-01

    Outcrops of old strata at the shelf edge resulting from erosive gravity-driven flows have been globally described on continental margins. The reexposure of old strata allows for the reintroduction of aged organic carbon (OC), sequestered in marine sediments for thousands of years, into the modern carbon cycle. This pool of reworked material represents an additional source of 14C-depleted organic carbon supplied to the ocean, in parallel with the weathering of fossil organic carbon delivered by rivers from land. To understand the dynamics and implications of this reexposure at the shelf edge, a biogeochemical study was carried out in the Gulf of Lions (Mediterranean Sea) where erosive processes, driven by shelf dense water cascading, are currently shaping the seafloor at the canyon heads. Mooring lines equipped with sediment traps and current meters were deployed during the cascading season in the southwestern canyon heads, whereas sediment cores were collected along the sediment dispersal system from the prodelta regions down to the canyon heads. Evidence from grain-size, X-radiographs and 210Pb activity indicate the presence in the upper slope of a shelly-coarse surface stratum overlying a consolidated deposit. This erosive discontinuity was interpreted as being a result of dense water cascading that is able to generate sufficient shear stress at the canyon heads to mobilize the coarse surface layer, eroding the basal strata. As a result, a pool of aged organic carbon (Δ14C = -944.5 ± 24.7‰; mean age 23,650 ± 3,321 ybp) outcrops at the modern seafloor and is reexposed to the contemporary carbon cycle. This basal deposit was found to have relatively high terrigenous organic carbon (lignin = 1.48 ± 0.14 mg/100 mg OC), suggesting that this material was deposited during the last low sea-level stand. A few sediment trap samples showed anomalously depleted radiocarbon concentrations (Δ14C = -704.4 ± 62.5‰) relative to inner shelf (Δ14C = -293.4 ± 134.0

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

    SciTech Connect

    Argiles, J.; Herrera, E.

    1989-02-01

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

  15. 14C as a tool for evaluating riverine POC sources and erosion of the Zhujiang (Pearl River) drainage basin, South China

    NASA Astrophysics Data System (ADS)

    Wei, Xiuguo; Yi, Weixi; Shen, Chengde; Yechieli, Yoseph; Li, Ningli; Ding, Ping; Wang, Ning; Liu, Kexin

    2010-04-01

    Radiocarbon can serve as a powerful tool for identifying sources of organic carbon and evaluating the erosion intensity in river drainage basins. In this paper we present 14C-AMS measurements of particulate organic carbon (POC) collected from the three major tributaries of the Zhujiang (Pearl River) system: the Xijiang (Western River), Beijiang (Northern River) and Dongjiang (Eastern River) rivers. Furthermore, we discuss the distribution of POC 14C apparent ages and the related watersheds erosion of these rivers. Results yield Δ 14C values of -425‰ to -65‰ which indicate that the 14C apparent ages of suspended POC in the entire area are in the range of 540-4445 years. The POC apparent ages from Xijiang are mostly between 2000 and 4000 years, while in Dongjiang they mostly range from 540 to 1010 years. These 14C apparent ages indicate that the watershed erosion of the Xijiang is more severe than that of the Dongjiang. This is in agreement with other data showing deeper erosion in Xijiang due to human activities.

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

    SciTech Connect

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

    1981-10-01

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

  17. Diverse Eruptions at Approximately 2,200 Years B.P. on the Great Rift, Idaho: Inferences for Magma Dynamics Along Volcanic Rift Zones

    NASA Technical Reports Server (NTRS)

    Hughes, S. S.; Nawotniak, S. E. Kobs; Borg, C.; Mallonee, H. C.; Purcell, S.; Neish, C.; Garry, W. B.; Haberle, C. W.; Lim, D. S. S.; Heldmann, J. L.

    2016-01-01

    Compositionally and morphologically diverse lava flows erupted on the Great Rift of Idaho approximately 2.2 ka (kilo-annum, 1000 years ago) during a volcanic "flare-up" of activity following an approximately 2 ky (kiloyear, 1000 years) hiatus in eruptions. Volcanism at Craters of the Moon (COTM), Wapi and Kings Bowl lava fields around this time included primitive and evolved compositions, separated over 75 kilometers along the approximately 85 kilometers-long rift, with striking variability in lava flow emplacement mechanisms and surface morphologies. Although the temporal associations may be coincidental, the system provides a planetary analog to better understand magma dynamics along rift systems, including that associated with lunar floor-fractured craters. This study aims to help bridge the knowledge gap between ancient rift volcanism evident on the Moon and other terrestrial planets, and active rift volcanism, e.g., at Hawai'i and Iceland.

  18. Allocation of 14C assimilated in late spring to tissue and biochemical stem components of cork oak (Quercus suber L.) over the seasons.

    PubMed

    Aguado, Pedro L; Curt, M Dolores; Pereira, Helena; Fernández, Jesús

    2012-03-01

    Carbon distribution in the stem of 2-year-old cork oak plants was studied by (14)CO(2) pulse labeling in late spring in order to trace the allocation of photoassimilates to tissue and biochemical stem components of cork oak. The fate of (14)C photoassimilated carbon was followed during two periods: the first 72 h (short-term study) and the first 52 weeks (long-term study) after the (14)CO(2) photosynthetic assimilation. The results showed that (14)C allocation to stem tissues was dependent on the time passed since photoassimilation and on the season of the year. In the first 3 h all (14)C was found in the polar extractives. After 3 h, it started to be allocated to other stem fractions. In 1 day, (14)C was allocated mostly to vascular cambium and, to a lesser extent, to primary phloem; no presence of (14)C was recorded for the periderm. However, translocation of (14)C to phellem was observed from 1 week after (14)CO(2) pulse labeling. The phellogen was not completely active in its entire circumference at labeling, unlike the vascular cambium; this was the tissue that accumulated most photoassimilated (14)C at the earliest sampling. The fraction of leaf-assimilated (14)C that was used by the stem peaked at 57% 1 week after (14)CO(2) plant exposure. The time lag between C photoassimilation and suberin accumulation was ∼8 h, but the most active period for suberin accumulation was between 3 and 7 days. Suberin, which represented only 1.77% of the stem weight, acted as a highly effective sink for the carbon photoassimilated in late spring since suberin specific radioactivity was much higher than for any other stem component as early as only 1 week after (14)C plant labeling. This trend was maintained throughout the whole experiment. The examination of microautoradiographs taken over 1 year provided a new method for quantifying xylem growth. Using this approach it was found that there was more secondary xylem growth in late spring than in other times of the year

  19. Allocation of 14C assimilated in late spring to tissue and biochemical stem components of cork oak (Quercus suber L.) over the seasons.

    PubMed

    Aguado, Pedro L; Curt, M Dolores; Pereira, Helena; Fernández, Jesús

    2012-03-01

    Carbon distribution in the stem of 2-year-old cork oak plants was studied by (14)CO(2) pulse labeling in late spring in order to trace the allocation of photoassimilates to tissue and biochemical stem components of cork oak. The fate of (14)C photoassimilated carbon was followed during two periods: the first 72 h (short-term study) and the first 52 weeks (long-term study) after the (14)CO(2) photosynthetic assimilation. The results showed that (14)C allocation to stem tissues was dependent on the time passed since photoassimilation and on the season of the year. In the first 3 h all (14)C was found in the polar extractives. After 3 h, it started to be allocated to other stem fractions. In 1 day, (14)C was allocated mostly to vascular cambium and, to a lesser extent, to primary phloem; no presence of (14)C was recorded for the periderm. However, translocation of (14)C to phellem was observed from 1 week after (14)CO(2) pulse labeling. The phellogen was not completely active in its entire circumference at labeling, unlike the vascular cambium; this was the tissue that accumulated most photoassimilated (14)C at the earliest sampling. The fraction of leaf-assimilated (14)C that was used by the stem peaked at 57% 1 week after (14)CO(2) plant exposure. The time lag between C photoassimilation and suberin accumulation was ∼8 h, but the most active period for suberin accumulation was between 3 and 7 days. Suberin, which represented only 1.77% of the stem weight, acted as a highly effective sink for the carbon photoassimilated in late spring since suberin specific radioactivity was much higher than for any other stem component as early as only 1 week after (14)C plant labeling. This trend was maintained throughout the whole experiment. The examination of microautoradiographs taken over 1 year provided a new method for quantifying xylem growth. Using this approach it was found that there was more secondary xylem growth in late spring than in other times of the year

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

    SciTech Connect

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

    1982-01-01

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

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

    SciTech Connect

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

    1989-09-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2001-07-01

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

  3. 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.

  4. Surface water processes in the Indonesian throughflow as documented by a high-resolution coral Δ14C record

    NASA Astrophysics Data System (ADS)

    Fallon, Stewart J.; Guilderson, Thomas P.

    2008-09-01

    To explore the seasonal to decadal variability in surface water masses that contribute to the Indonesian throughflow, we have generated a 115-year bimonthly 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‰). After 1954 the radiocarbon record increases rapidly, in response to the increased atmospheric 14C content caused by nuclear weapons testing. From 1957 to 1986 the record displays clear seasonal variability from 15 to 60‰ 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 the 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 14C peak in 1955 due to the bomb-14C water advected into this region from nuclear weapons tests in the Marshall Islands in 1954.

  5. Greenland ice cores tell tales on the extent of the Greenland Ice Sheet during the warm climate Eemian period 130.000 - 115.000 years BP.

    NASA Astrophysics Data System (ADS)

    Dahl-Jensen, D.

    2012-12-01

    A new Greenland ice core has been drilled. The first results from the NEEM ice core are presented and then combined with the results from the other deep ice cores from the Greenland Ice Sheet. All the ice cores drilled though the Greenland ice sheets have been analyzed and the results show that all the ice cores contain ice from the last interglacial, the Eemian, near the base. Is it thus clear that the Greenland Ice Sheet did exist 124.000 years ago in the previous warm climate period where it was more than 5 deg C warmer over Greenland. The difference between the Eemian and the Holocene stable oxygen isotope values have been combined with an ice sheet flow model constrained by the ice core results and internal radio echo sounding layers to estimate the volume of the Greenland Ice Sheet 124.000 years ago. The results show that South Greenland has not been ice free during the Eemian period and that the sea level contribution from the Greenland Ice Sheet has been 2.0 +-0.5 m.

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

    PubMed Central

    Beyer, Elmo M.

    1975-01-01

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

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

    SciTech Connect

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

    1990-08-01

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

  8. Does the 43 bp sequence from an 800,000 year old cretan dwarf elephantid really rewrite the textbook on mammoths?

    PubMed

    Orlando, Ludovic; Pagés, Marie; Calvignac, Sébastien; Hughes, Sandrine; Hänni, Catherine

    2007-02-22

    Pigmy elephants inhabited the islands from the Mediterranean region during the Pleistocene period but became extinct in the course of the Holocene. Despite striking distinctive anatomical characteristics related to insularity, some similarities with the lineage of extant Asian elephants have suggested that pigmy elephants could be most probably seen as members of the genus Elephas. Poulakakis et al (2006) have recently challenged this view by recovering a short mtDNA sequence from an 800 000 year old fossil of the Cretan pigmy elephant (Elephas creticus). According to the authors of this study, a deep taxonomic revision of Cretan dwarf elephants would be needed, as the sequence exhibits clear affinities with woolly mammoth haplotypes. However, we point here many aspects that seriously weaken the strength of the ancient DNA evidence reported.

  9. Does the 43 bp sequence from an 800,000 year old cretan dwarf elephantid really rewrite the textbook on mammoths?

    PubMed

    Orlando, Ludovic; Pagés, Marie; Calvignac, Sébastien; Hughes, Sandrine; Hänni, Catherine

    2007-02-22

    Pigmy elephants inhabited the islands from the Mediterranean region during the Pleistocene period but became extinct in the course of the Holocene. Despite striking distinctive anatomical characteristics related to insularity, some similarities with the lineage of extant Asian elephants have suggested that pigmy elephants could be most probably seen as members of the genus Elephas. Poulakakis et al (2006) have recently challenged this view by recovering a short mtDNA sequence from an 800 000 year old fossil of the Cretan pigmy elephant (Elephas creticus). According to the authors of this study, a deep taxonomic revision of Cretan dwarf elephants would be needed, as the sequence exhibits clear affinities with woolly mammoth haplotypes. However, we point here many aspects that seriously weaken the strength of the ancient DNA evidence reported. PMID:17443966

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

    SciTech Connect

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

    2004-10-29

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

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

    PubMed Central

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

    1965-01-01

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

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

    SciTech Connect

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

    1985-03-01

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

  13. Imprint of CO2 emission in atmosphere and biosphere on the basis of 14C and 13C measurements

    NASA Astrophysics Data System (ADS)

    Pazdur, Anna; Gabryś, Alicja; Kuc, Tadeusz; Pawełczyk, Sławomira; Piotrowska, Natalia; Rakowski, Andrzej; Różański, Kazimierz; Sensuła, Barbara

    2015-04-01

    component in CO2 in our region is rising. The measurements of 14C (by AMS method) and 13C isotopes have been carried out in atmospheric CO2 and plants in the Gliwice city centre. A high decrease of both isotopes contents and their short-term seasonal changes during the year caused by human impact during the year are observed.

  14. The 14C age of groundwater around saltwater-freshwater interface in deep coastal aquifer

    NASA Astrophysics Data System (ADS)

    Machida, I.; Ono, M.; Ikawa, R.; Koshigai, M.; Marui, A.

    2015-12-01

    This study is focused on determining the groundwater age in mixing zone around saltwater-freshwater interface in deep confined aquifer by 14C methods. A drilling up to 160m in depth was carried out with sampling geologic cores at a distance of 350m from coastal line. The elevation of the ground surface in the drilling site is about 4m, locates on the foot of Mt. Fuji, the highest mountain in Japan. The geology consists mainly of Quaternary, brittle volcanic rocks and fan deposits, and occasionally silt layers. The mixing zone of saltwater-freshwater was detected under 85m depth at the drilling site. A screen interval of the borehole was set from 151 to 157m depth and sampled the groundwater (hereafter called as FGB-water). The Cl- concentration of the FGB-water was 4,990 mg/L with NaCl type (approximately a quarter of salt water), indicating that FGB-water was taken from landward side of mixing zone around saltwater-freshwater interface. In addition to the drilling, the sampling of groundwater from more than 50 wells in the basin was carried out. The adjusted 14C age of FGB-water is estimated at approximately 10,000 years by fitting calculations. The ages of inland groundwater taken from almost same depth to FGB-water are 200-3,000 years. Although it is unclear why the FGB-water is much older than others, a likely explanation is due to the groundwater around saltwater-freshwater interface is moving upward roughly along the landward sloping interface (Cooper, 1964). Such movement would bring deeper and older groundwater to shallow zone. At the drilling site, the freshwater with low electric conductivity was obtained from surface to 84m depth. And they have much lighter stable isotopes (D and 18O) compared to those in inland. That is to say, the groundwater recharged at higher elevation distribute at shallow zone at the FGB. This result supports the upward moving of groundwater at the coastal area.

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed

    de la Lanza Espino, Guadalupe; Soto, Luis A

    2015-01-01

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

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

    SciTech Connect

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

    1989-11-01

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

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

    PubMed

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

    2008-07-01

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

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

    PubMed

    Ratner, S

    1983-12-01

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

  20. Exotic nuclear decay of /sup 223/Ra by emission of /sup 14/C nuclei

    SciTech Connect

    Gales, S.; Hourani, E.; Hussonnois, M.; Schapira, J.P.; Stab, L.; Vergnes, M.

    1984-08-20

    The exotic nuclear decay of /sup 223/Ra by emission of /sup 14/C nuclei has been investigated by use of an intense radioactive /sup 227/Ac source and a magnetic spectrometer with a large solid angle. After a run of 5 d, a group of eleven events was observed at the expected location of /sup 14/C in a ..delta..E-E telescope calibrated with a /sup 14/C beam. A branching ratio of (5.5 +- 2.0) x 10/sup -10/ was measured for the emission of /sup 14/C nuclei relative to ..cap alpha.. particles from /sup 223/Ra in agreement with the previously reported ratio of (8.5 +- 2.5) x 10/sup -10/. .AE

  1. Interpretation of the fine structure in the sup 14 C radioactive decay of sup 223 Ra

    SciTech Connect

    Sheline, R.K. ); Ragnarsson, I. )

    1991-03-01

    The experimental hindrance factors determined from the fine structure in the {sup 14}C decay of {sup 223}Ra are strikingly similar to the hindrance factors observed in the alpha decay of odd-{ital A} reflection-asymmetric deformed nuclei in spite of the deformed to spherical shape which occurs in the {sup 14}C decay. Calculations of the overlap between the reflection-asymmetric ground state of {sup 223}Ra and the spherical shell-model orbitals of {sup 209}Pb involved in the {sup 14}C decay are consistent with the experimental hindrance factors from the {sup 14}C fine structure except that the {ital j}{sub 15/2} orbital is more strongly populated experimentally than the calculations suggest.

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

    SciTech Connect

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

    1986-08-20

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  4. 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.

  5. 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.

  6. Fate of (14)C-organic pollutant residues in composted sludge after application to soil.

    PubMed

    Haudin, Claire-Sophie; Zhang, Yuhai; Dumény, Valérie; Lashermes, Gwenaëlle; Bergheaud, Valérie; Barriuso, Enrique; Houot, Sabine

    2013-08-01

    Organic micropollutants may be present in biosolids, leading to soil contamination when they are recycled in agriculture. A sludge spiked with (14)C-labelled glyphosate (GLY), sodium linear dodecylbenzene sulphonate (LAS), fluoranthene (FLT) or 4-n-nonylphenol (NP) was composted with green waste and the fate of the (14)C-micropollutant residues remaining after composting was assessed after the compost application to the soil. (14)C-residues were mineralised in the soil and represented after 140d 20-32% of the initial activity for LAS, 16-25% for GLY, 6-9% for FLT and 4-7% for NP. The (14)C-residues at the end of composting that could not be extracted with methanol or ammonia were minimally remobilised or even increased for FLT. After 140d, non-extractable residues represented 38-52% of all of the (14)C-residues remaining in the soil for FLT, 50-67% for GLY, 91-92% for NP and 94-97% for LAS and in most cases, less than 1% of the (14)C-residues were water soluble, suggesting a low direct availability for leaching and microbial or plant assimilation. FLT was identified as the main compound among the methanol-extractable (14)C-residues that may be potentially available. The fate of the (14)C-organic pollutant residues in composts after application to soil could be assessed through a sequential chemical extraction scheme and depended on the chemical nature of the pollutant.

  7. Seasonally Resolved Surface Water (delta)14C Variability in the Lombok Strait: A Coralline Perspective

    SciTech Connect

    Guilderson, T P; Fallon, S J; Moore, M D; Schrag, D P; Charles, C D

    2008-04-23

    We have explored surface water mixing in the Lombok Strait through a {approx}bimonthly resolved surface water {Delta}{sup 14}C time-series reconstructed from a coral in the Lombok Strait that spans 1937 through 1990. The prebomb surface water {Delta}{sup 14}C average is -60.5{per_thousand} and individual samples range from -72{per_thousand} to 134{per_thousand}. The annual average post-bomb maximum occurs in 1973 and is 122{per_thousand}. The timing of the post-bomb maximum is consistent with a primary subtropical source for the surface waters in the Indonesian Seas. During the post-bomb period the coral records regular seasonal cycles of 5-20{per_thousand}. Seasonal high {Delta}{sup 14}C occur during March-May (warm, low salinity), and low {Delta}{sup 14}C occur in September (cool, higher salinity). The {Delta}{sup 14}C seasonality is coherent and in phase with the seasonal {Delta}{sup 14}C cycle observed in Makassar Strait. We estimate the influence of high {Delta}{sup 14}C Makassar Strait (North Pacific) water flowing through the Lombok Strait using a two endmember mixing model and the seasonal extremes observed at the two sites. The percentage of Makassar Strait water varies between 16 and 70%, and between 1955 and 1990 it averages 40%. During La Nina events there is a higher percentage of Makassar Strait (high {Delta}{sup 14}C) water in the Lombok Strait.

  8. Fate of (14)C-organic pollutant residues in composted sludge after application to soil.

    PubMed

    Haudin, Claire-Sophie; Zhang, Yuhai; Dumény, Valérie; Lashermes, Gwenaëlle; Bergheaud, Valérie; Barriuso, Enrique; Houot, Sabine

    2013-08-01

    Organic micropollutants may be present in biosolids, leading to soil contamination when they are recycled in agriculture. A sludge spiked with (14)C-labelled glyphosate (GLY), sodium linear dodecylbenzene sulphonate (LAS), fluoranthene (FLT) or 4-n-nonylphenol (NP) was composted with green waste and the fate of the (14)C-micropollutant residues remaining after composting was assessed after the compost application to the soil. (14)C-residues were mineralised in the soil and represented after 140d 20-32% of the initial activity for LAS, 16-25% for GLY, 6-9% for FLT and 4-7% for NP. The (14)C-residues at the end of composting that could not be extracted with methanol or ammonia were minimally remobilised or even increased for FLT. After 140d, non-extractable residues represented 38-52% of all of the (14)C-residues remaining in the soil for FLT, 50-67% for GLY, 91-92% for NP and 94-97% for LAS and in most cases, less than 1% of the (14)C-residues were water soluble, suggesting a low direct availability for leaching and microbial or plant assimilation. FLT was identified as the main compound among the methanol-extractable (14)C-residues that may be potentially available. The fate of the (14)C-organic pollutant residues in composts after application to soil could be assessed through a sequential chemical extraction scheme and depended on the chemical nature of the pollutant. PMID:23545187

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

    SciTech Connect

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

    1984-03-01

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

  10. Disposition of [14C]methyl bromide in Fischer-344 rats after oral or intraperitoneal administration.

    PubMed

    Medinsky, M A; Bond, J A; Dutcher, J S; Birnbaum, L S

    1984-09-14

    Methyl bromide is used as a disinfectant to fumigate soil. The intent of our study was to determine the disposition of methyl bromide following a single acute administration. Male Fischer-344 rats were given 250 mumol of [14C] methyl bromide/kg body wt by either oral or i.p. administration. Urine, feces and expired air were collected and at the end of 72 h the rats were sacrificed and tissues analyzed to determine 14C excretion and tissue distribution. After i.p. administration of methyl bromide, the dominant route of excretion was exhalation of 14CO2, with 46% of the dose exhaled as 14CO2. In contrast, urinary excretion of 14C was the major route of elimination (43% of the dose) when methyl bromide was given orally. Very little of the 14C appeared in the feces (less than 3% of the dose) regardless of route of administration. In rats with bile duct cannulations, 46% of an oral dose appeared in the bile over a 24-h period. Collection of bile significantly decreased the exhalation of 14CO2 and 14C excreted in urine compared to controls. At 72 h after oral or i.p. administration, 14-17% of the 14C remained in the rats, with liver and kidney being the major organs of retention. Results indicate that route of administration can affect the pathways for excretion. In addition, excretion of 14C in bile, coupled with the low levels of radioactivity found in the feces, indicates that reabsorption of biliary metabolites from the gut plays a significant role in the disposition of [14C] methyl bromide.

  11. ( sup 14 C)urea breath test for diagnosis of Helicobacter pylori

    SciTech Connect

    Ormand, J.E.; Talley, N.J.; Carpenter, H.A.; Shorter, R.G.; Conley, C.R.; Wilson, W.R.; DiMagno, E.P.; Zinsmeister, A.R.; Phillips, S.F. )

    1990-07-01

    H. pylori is a potent urease producer, a characteristic that has been exploited in the development of the (14C)- and (13C)urea breath tests. The prevalence of H. pylori infection also is known to increase with advancing age; however, the individual patient's age has not routinely been considered when interpreting urea breath test results. The aim of this study was to validate a short, age-adjusted (14C)urea breath test for use in diagnosing H. pylori infections. Forty-one subjects (28 volunteers, 13 patients) underwent esophagogastroduodenoscopy with biopsies. Subjects were defined as being H. pylori-positive if histology or culture was positive. In addition, all subjects completed a 120-min (14C)urea breath test. A logistic regression analysis adjusting for age was used to estimate the probability of H. pylori positivity as a function of the 14C values generated. Sixteen subjects were H. pylori-positive, and 25 were H. pylori-negative. The 14C values generated between 15 and 80 min were found to be equally predictive in identifying H. pylori-positive subjects. Advancing age was associated with a higher probability of H. pylori-positivity. By taking advantage of the statistical probabilities, older patients could be accurately diagnosed with H. pylori at lower 14C values. We found that (14C)urea breath test to be both a sensitive and specific test that can be abbreviated to a 30-min examination (total test time). Moreover, our mathematical model indicates that a patient's age should be considered in order to optimize interpretation of the (14C)urea breath test, although further observations are needed to confirm this model.

  12. AMS studies of the long-term turnover of 14C-labelled fat in man

    NASA Astrophysics Data System (ADS)

    Gunnarsson, M.; Mattsson, S.; Stenström, K.; Leide-Svegborn, S.; Erlandsson, B.; Faarinen, M.; Hellborg, R.; Kiisk, M.; Nilsson, L.-E.; Nosslin, B.; Persson, P.; Skog, G.; Åberg, M.

    2000-10-01

    To estimate the biokinetics of 14C-labelled fatty acids and the associated radiation absorbed dose to man, long-term retention of 14C from oral intake of glycerol tri[1- 14C]oleate (triolein) has been studied using accelerator mass spectrometry (AMS). As a complement to earlier reported data for three individuals, we present here results for one person from measurements up to 4.6 yr after administration, now also including 14C-levels in fat, muscle and bone. In this subject, a total of 44% of the administered activity was recovered in the exhaled air. Fasting increased the exhalation of 14C. The "excess" 14CO2 due to fasting had a half-life of about 400 d. AMS measurements on fat, muscle and bone biopsies taken from the same subject 4.5 yr after ingestion indicated that a small fraction of the administered activity was still present in fat. Also, bone tissue had a higher 14C specific activity than the current environmental level. No significantly increased level was found in the muscle sample.

  13. Fate of 14C-ethyl prothiofos insecticide in canola seeds and oils.

    PubMed

    Abdel-Gawad, Hassan; Hegazi, Bahira

    2010-02-01

    Canola plants were treated with (14)C- prohiofos under conditions simulating local agricultural practices. (14)C-residues in seeds were determined at different time intervals. At harvest time about 32 % of (14)C-activity was associated with oil. The methanol soluble (14)C-residues accounted for 12 % of the total seed residues after further seeds extraction, while the cake contained about 49 % of the total residues. About 69 % of the (14)C-activity in the crude oil could be eliminated by simulated commercial processes locally used for oil refining. Chromatographic analysis of crude and refined oil revealed the presence of the parent compound together with three metabolites which were identified as prothiofos oxon, O-ethyl phosphorothioate and O-ethyl S-propyl phosphorothioate, besides one unknown compound. While methanol extract revealed the presence of despropylthio prothiofos and O-ethyl phosphoric acid as free metabolites acid hydrolysis of the conjugated metabolites in the methanol extract yielded 2, 4-dichlorophenole which was detected by color. When rats were fed the extracted cake for 72 hours, the bound residues were found to be bioavailable. The main excretion route was via the expired air (42 %), while the (14)C-residues excreted in urine and feces were 30 % and 11 %, respectively. The radioactivity detected among various organs accounted to 7.5 %.Chromatographic analysis of urine indicated the presence of prothiofos oxon, O-ethyl phosphoric acid and 2, 4-dichlorophenole as main degradation products of prothiofos in free and conjugated form.

  14. A simple method to determine mineralization of (14) C-labeled compounds in soil.

    PubMed

    Myung, Kyung; Madary, Michael W; Satchivi, Norbert M

    2014-06-01

    Degradation of organic compounds in soil is often determined by measuring the decrease of the parent compound and analyzing the occurrence of its metabolites. However, determining carbon species as end products of parent compound dissipation requires using labeled materials that allow more accurate determination of the environmental fate of the compound of interest. The current conventional closed system widely used to monitor degradation of (14) C-labeled compounds in soil is complex and expensive and requires a specialized apparatus and facility. In the present study, the authors describe a simple system that facilitates measurement of mineralization of (14) C-labeled compounds applied to soil samples. In the system, soda lime pellets to trap mineralized (14) C-carbon species, including carbon dioxide, were placed in a cup, which was then inserted above the treated soil sample in a tube. Mineralization of [(14) C]2,4-D applied to soil samples in the simple system was compared with that in the conventional system. The simple system provided an equivalent detection of (14) C-carbon species mineralized from the parent compound. The results demonstrate that this cost- and space-effective simple system is suitable for examining degradation and mineralization of (14) C-labeled compounds in soil and could potentially be used to investigate their mineralization in other biological matrices.

  15. Fine-root turnover patterns and their relationship to root diameter and soil depth in a 14C-labeled hardwood forest

    SciTech Connect

    Joslin, Jr., John D; Gaudinski, Julia B.; Torn, Margaret S.; Riley, W. J.; Hanson, Paul J

    2006-01-01

    Characterization of turnover times of fine roots is essential to understanding patterns of carbon allocation in plants and describing forest C cycling. We used the rate of decline in the ratio of 14C to 12C in a mature hardwood forest, enriched by an inadvertent 14C pulse, to investigate fine-root turnover and its relationship with fine-root diameter and soil depth. Biomass and ?14C values were determined for fine roots collected during three consecutive winters from four sites, by depth, diameter size classes (<0.5 or 0.5-2 mm), and live-or-dead status. Live-root pools retained significant 14C enrichment over 3 yr, demonstrating a mean turnover time on the order of years. However, elevated ?14C values in dead-root pools within 18 months of the pulse indicated an additional component of live roots with short turnover times (months). Our results challenge assumptions of a single live fine-root pool with a unimodal and normal age distribution. Live fine roots <0.5 mm and those near the surface, especially those in the O horizon, had more rapid turnover than 0.5-2 mm roots and deeper roots, respectively.

  16. Pre-bomb {Delta}{sup 14}C variability and the Suess Effect in Cariaco Basin Surface Waters as Recorded in Hermatypic Corals

    SciTech Connect

    Guilderson, T; Cole, J; Southon, J

    2004-10-28

    The {Delta}{sup 14}C content of surface waters in and around the Cariaco Basin were reconstructed from {sup 14}C measurements on sub-annually sampled coral skeletal material. During the late 1930s - early 1940s surface waters within and outside of the Cariaco Basin are similar. Within the Cariaco Basin at Islas Tortugas coral {Delta}{sup 14}C averages -51.9 {+-}3.3 {per_thousand}. Corals collected outside of the basin at Boca de Medio and Los Testigos have {Delta}{sup 14}C values of -53.4 {+-} 3.3 {per_thousand} and -54.3 {+-} 2.6 respectively. Additional {sup 14}C analyses on the Isla Tortugas coral document an {approx} 11 {per_thousand} decrease between {approx}1905 (-40.9 {+-}4.5 {per_thousand}) and {approx}1940. The implied Suess Effect trend (-3 {per_thousand}/decade) is nearly as large as that observed in the atmosphere over the same time period. If we assume that there is little to no fossil fuel {sup 14}CO{sub 2} signature in Cariaco surface waters in {approx}1905, the waters have an equivalent reservoir age of {approx}312 years.

  17. Fine-root turnover patterns and their relationship to root diameter and soil depth in a 14C-labeled hardwood forest.

    PubMed

    Joslin, J D; Gaudinski, J B; Torn, M S; Riley, W J; Hanson, P J

    2006-01-01

    Characterization of turnover times of fine roots is essential to understanding patterns of carbon allocation in plants and describing forest C cycling. We used the rate of decline in the ratio of 14C to 12C in a mature hardwood forest, enriched by an inadvertent 14C pulse, to investigate fine-root turnover and its relationship with fine-root diameter and soil depth. Biomass and Delta14C values were determined for fine roots collected during three consecutive winters from four sites, by depth, diameter size classes (< 0.5 or 0.5-2 mm), and live-or-dead status. Live-root pools retained significant 14C enrichment over 3 yr, demonstrating a mean turnover time on the order of years. However, elevated Delta14C values in dead-root pools within 18 months of the pulse indicated an additional component of live roots with short turnover times (months). Our results challenge assumptions of a single live fine-root pool with a unimodal and normal age distribution. Live fine roots < 0.5 mm and those near the surface, especially those in the O horizon, had more rapid turnover than 0.5-2 mm roots and deeper roots, respectively. PMID:17083682

  18. Observational infant exploratory [14C]-paracetamol pharmacokinetic microdose/therapeutic dose study with accelerator mass spectrometry bioanalysis

    PubMed Central

    Garner, Colin R; Park, Kevin B; French, Neil S; Earnshaw, Caroline; Schipani, Alessandro; Selby, Andrew M; Byrne, Lindsay; Siner, Sarah; Crawley, Francis P; Vaes, Wouter H J; van Duijn, Esther; deLigt, Rianne; Varendi, Heili; Lass, Jane; Grynkiewicz, Grzegorz; Maruszak, Wioletta; Turner, Mark A

    2015-01-01

    Aims The aims of the study were to compare [14C]-paracetamol ([14C]-PARA) paediatric pharmacokinetics (PK) after administration mixed in a therapeutic dose or an isolated microdose and to develop further and validate accelerator mass spectrometry (AMS) bioanalysis in the 0–2 year old age group. Methods [14C]-PARA concentrations in 10–15 µl plasma samples were measured after enteral or i.v. administration of a single [14C]-PARA microdose or mixed in with therapeutic dose in infants receiving PARA as part of their therapeutic regimen. Results Thirty-four infants were included in the PARA PK analysis for this study: oral microdose (n = 4), i.v. microdose (n = 6), oral therapeutic (n = 6) and i.v. therapeutic (n = 18). The respective mean clearance (CL) values (SDs in parentheses) for these dosed groups were 1.46 (1.00) l h–1, 1.76 (1.07) l h–1, 2.93 (2.08) l h–1 and 2.72 (3.10) l h–1, t1/2 values 2.65 h, 2.55 h, 8.36 h and 7.16 h and dose normalized AUC(0-t) (mg l–1 h) values were 0.90 (0.43), 0.84 (0.57), 0.7 (0.79) and 0.54 (0.26). Conclusions All necessary ethical, scientific, clinical and regulatory procedures were put in place to conduct PK studies using enteral and systemic microdosing in two European centres. The pharmacokinetics of a therapeutic dose (mg kg–1) and a microdose (ng kg–1) in babies between 35 to 127 weeks post-menstrual age. [14C]-PARA pharmacokinetic parameters were within a two-fold range after a therapeutic dose or a microdose. Exploratory studies using doses significantly less than therapeutic doses may offer ethical and safety advantages with increased bionalytical sensitivity in selected exploratory paediatric pharmacokinetic studies. PMID:25619398

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

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-09-01

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

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

    PubMed Central

    Habu, Junko; Kobayashi, Kenichi; Madella, Marco

    2016-01-01

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

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

    PubMed

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

    2016-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  4. Grand solar minima and maxima deduced from 10Be and 14C: magnetic dynamo configuration and polarity reversal

    NASA Astrophysics Data System (ADS)

    Inceoglu, F.; Simoniello, R.; Knudsen, M. F.; Karoff, C.; Olsen, J.; Turck-Chiéze, S.; Jacobsen, B. H.

    2015-05-01

    Aims: This study aims to improve our understanding of the occurrence and origin of grand solar maxima and minima. Methods: We first investigate the statistics of peaks and dips simultaneously occurring in the solar modulation potentials reconstructed using the Greenland Ice Core Project (GRIP) 10Be and IntCal13 14C records for the overlapping time period spanning between ~1650 AD to 6600 BC. Based on the distribution of these events, we propose a method to identify grand minima and maxima periods. By using waiting time distribution analysis, we investigate the nature of grand minima and maxima periods identified based on the criteria as well as the variance and significance of the Hale cycle during these kinds of events throughout the Holocene epoch. Results: Analysis of grand minima and maxima events occurring simultaneously in the solar modulation potentials, reconstructed based on the 14C and the 10Be records, shows that the majority of events characterized by periods of moderate activity levels tend to last less than 50 years: grand maxima periods do not last longer than 100 years, while grand minima can persist slightly longer. The power and the variance of the 22-year Hale cycle increases during grand maxima and decreases during grand minima, compared to periods characterized by moderate activity levels. Conclusions: We present the first reconstruction of the occurrence of grand solar maxima and minima during the Holocene based on simultaneous changes in records of past solar variability derived from tree-ring 14C and ice-core 10Be, respectively. This robust determination of the occurrence of grand solar minima and maxima periods will enable systematic investigations of the influence of grand solar minima and maxima episodes on Earth's climate.

  5. Metabolism of (2-14C)acetate and its use in assessing hepatic Krebs cycle activity and gluconeogenesis

    SciTech Connect

    Schumann, W.C.; Magnusson, I.; Chandramouli, V.; Kumaran, K.; Wahren, J.; Landau, B.R. )

    1991-04-15

    To examine the fate of the carbons of acetate and to evaluate the usefulness of labeled acetate in assessing intrahepatic metabolic processes during gluconeogenesis, (2-14C)acetate, (2-14C)ethanol, and (1-14C)ethanol were infused into normal subjects fasted 60 h and given phenyl acetate. Distributions of 14C in the carbons of blood glucose and glutamate from urinary phenylacetylglutamine were determined. With (2-14C)acetate and (2-14C)ethanol, carbon 1 of glucose had about twice as much 14C as carbon 3. Carbon 2 of glutamate had about twice as much 14C as carbon 1 and one-half to one-third as much as carbon 4. There was only a small amount in carbon 5. These distributions are incompatible with the metabolism of (2-14C)acetate being primarily in liver. Therefore, (2-14C)acetate cannot be used to study Krebs cycle metabolism in liver and in relationship to gluconeogenesis, as has been done. The distributions can be explained by: (a) fixation of 14CO2 from (2-14C)acetate in the formation of the 14C-labeled glucose and glutamate in liver and (b) the formation of 14C-labeled glutamate in a second site, proposed to be muscle. (1,3-14C)Acetone formation from the (2-14C)acetate does not contribute to the distributions, as evidenced by the absence of 14C in carbons 2-4 of glutamate after (1-14C)ethanol administration.

  6. Estimate of recharge of a rising water table in semiarid Niger from 3H and 14C modeling.

    PubMed

    Favreau, Guillaume; Leduc, Christian; Marlin, Christelle; Dray, Martial; Taupin, Jean-Denis; Massault, Marc; Le, GalLaSalleCorinne; Babic, Milanka

    2002-01-01

    A hydrodynamic survey carried out in semiarid southwest Niger revealed an increase in the unconfined ground water reserves of approximately 10% over the last 50 years due to the clearing of native vegetation. Isotopic samplings (3H, 18O, 2H for water and 14C, 13C for the dissolved inorganic carbon) were performed on about 3500 km2 of this silty aquifer to characterize recharge. Stable isotope analyses confirmed the indirect recharge process that had already been shown by hydrodynamic surveys and suggested the tracers are exclusively of atmospheric origin. An analytical model that takes into account the long-term rise in the water table was used to interpret 3H and 14C contents in ground water. The natural, preclearing median annual renewal rate (i.e., recharge as a fraction of the saturated aquifer volume) lies between 0.04% and 0.06%. For representative characteristics of the aquifer (30 m of saturated thickness, porosity between 10% and 25%), this implies a recharge of between 1 and 5 mm/year, which is much lower than the estimates of 20 to 50 mm/year for recent years, obtained using hydrological and hydrodynamic methods and the same aquifer parameters. Our study, therefore, reveals that land clearing in semiarid Niger increased ground water recharge by about one order of magnitude.

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

    USGS Publications Warehouse

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

    1989-01-01

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

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

    SciTech Connect

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

    2003-03-01

    Determination of groundwater flow velocities at the Nevada Test Site is important since groundwater is the principal transport medium of underground radionuclides. However, 14C-based groundwater velocities in the carbonate aquifers of the Nevada Test Site are several orders of magnitude slower than velocities derived from the Underground Test Area regional numerical model. This discrepancy has been attributed to the loss or retardation of 14C from groundwater into the surrounding aquifer matrix making 14C-based groundwater ages appear much older. Laboratory experiments were used to investigate the retardation of 14C in the carbonate aquifers at the Nevada Test Site. Three sets of experiments were conducted evaluating the diffusion of 14C into the carbonate aquifer matrix, adsorption and/or isotopic exchange onto the pore surfaces of the carbonate matrix, and adsorption and/or isotopic exchange onto the fracture surfaces of the carbonate aquifer. Experimental results a nd published aquifer matrix and fracture porosities from the Lower Carbonate Aquifer were applied to a 14C retardation model. The model produced an extremely wide range of retardation factors because of the wide range of published aquifer matrix and fracture porosities (over three orders of magnitude). Large retardation factors suggest that groundwater with very little measured 14C activity may actually be very young if matrix porosity is large relative to the fracture porosity. Groundwater samples collected from highly fractured aquifers with large effective fracture porosities may have relatively small correction factors, while samples from aquifers with a few widely spaced fractures may have very large correction factors. These retardation factors were then used to calculate groundwater velocities from a proposed flow path at the Nevada Test Site. The upper end of the range of 14C correction factors estimated groundwater velocities that appear to be at least an order of magnitude too high compared

  9. Measuring chlorophyll. cap alpha. and /sup 14/C-labeled photosynthate in aquatic angiosperms by the use of a tissue solubilizer. [/sup 14/C-labelled photosynthate

    SciTech Connect

    Beer, S.; Stewart, A.J.; Wetzel, R.G.

    1982-01-01

    A compound that quantitatively correlated with chlorophyll ..cap alpha.. could be measured fluorometrically in the extracts of leaves of three aquatic angiosperms (Myriophyllum heterophyllum Michx., Potamogeton crispus L., Elodea canadensis Michx.) treated with the tissue solubilizer BTS-450. Fluorescent characteristics of the solubilized plant tissues were stable for several weeks in the dark at temperatures up to 60/sup 0/C but rapidly degraded in sunlight or when acidified. /sup 14/C-Labeled photosynthate, which had been fixed by leaf discs during 1- to 10-hour exposure to H/sup 14/CO/sub 3/, was also readily extracted by the tissue solubilizer. Solubilizer extraction can, therefore, be used to determine both chlorophyll ..cap alpha.. content and /sup 14/C incorporation rates in the same leaf sample. The method is practical, because no grinding is required, the fluorescent characteristics of the extracts are stable, and analyses can be performed with very little plant material (about 3 milligrams).

  10. Persistence of the herbicides (/sup 14/C)chlorsulfuron and (/sup 14/C)metsulfuron methyl in prairie soils under laboratory conditions

    SciTech Connect

    Smith, A.E.

    1986-11-01

    Metsulfuron methyl, whose structure is closely related to that of chlorsulfuron, is currently being evaluated on the Canadian prairies as a postemergence treatment for the control of broadleaf weeds in cereal crops, in non-crop land and for brush control. Although applied postemergence, some of the herbicide will come into contact with the soil making it necessary to determine the fate of metsulfuron methyl in the soil. These studies were undertaken to investigate the rate of breakdown and the fate of (/sup 14/C)metsulfuron methyl in three soils under laboratory conditions where no leaching could occur. The rate of breakdown of (/sup 14/C)chlorsulfuron was also investigated in one of the soils.

  11. The effects of the oral administration of fish oil concentrate on the release and the metabolism of (/sup 14/C)arachidonic acid and (/sup 14/C)eicosapentaenoic acid by human platelets

    SciTech Connect

    Hirai, A.; Terano, T.; Hamazaki, T.; Sajiki, J.; Kondo, S.; Ozawa, A.; Fujita, T.; Miyamoto, T.; Tamura, Y.; Kumagai, A.

    1982-11-01

    It has been suggested by several investigators that eicosapentaenoic acid (C20:5 omega 3, EPA) might have anti-thrombotic effects. In this experiment, the effect of the oral administration of EPA rich fish oil concentrate on platelet aggregation and the release and the metabolism of (/sup 1 -14/C)arachidonic acid and ((U)-/sup 14/C)eicosapentaenoic acid by human platelets was studied. Eight healthy male subjects ingested 18 capsules of fish oil concentrate (EPA 1.4 g) per day for 4 weeks. Plasma and platelet concentrations of EPA markedly increased, while those of arachidonic acid (C20:4 omega 6, AA) and docosahexaenoic acid (C22:6 omega 3, DHA) did not change. Platelet aggregation induced by collagen and ADP was reduced. Collagen induced (/sup 14/C)thromboxane B2 (TXB2) formation from (/sup 14/C)AA prelabeled platelets decreased. There was no detectable formation of (/sup 14/C)TXB3 from (/sup 14/C)EPA prelabeled platelets, and the conversion of exogenous (/sup 14/C)EPA to (/sup 14/C)TXB3 was lower than that of (/sup 14/C)AA to (/sup 14/C)TXB2. The release of (/sup 14/C)AA from (/sup 14/C)AA prelabeled platelets by collagen was significantly decreased. These observations raise the possibility that the release of arachidonic acid from platelet lipids might be affected by the alteration of EPA content in platelets.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  13. Changes in the 14C-Labeled Cell Wall Components with Chase Time after Incorporation of UDP[14C]Glucose by Intact Cotton Fibers 1

    PubMed Central

    Dugger, W. M.; Palmer, Raymond L.

    1988-01-01

    Intact, in vitro-grown cotton fibers will incorporate [14C]glucose from externally supplied UDP[14C]glucose into a variety of cell wall components including cellulose; this labeled fraction will continue to increase up to 4 hours chase time. In the fraction soluble in hot water there was no significant change in total label; however, the largest fraction after the 30 minute pulse with UDP[14C]glucose was chloroform-methanol soluble (70%) and showed a significant decrease with chase. The lipids that make up about 85% of this fraction were identified by TLC as steryl glucosides, acylated steryl glucosides, and glucosyl-phosphoryl-polyprenol. Following the pulse, the loss of label from acylated steryl glucosides and glucosylphophoryl-polyprenol was almost complete within 2 hours of chase; steryl glucosides made up about 85% of the fraction at that chase time. The total loss in the lipid fraction (about 100 picomoles per milligram dry weight of fiber) with chase times of 4 hours approximates the total gain in the total glucans. PMID:16666066

  14. Effect of cytochalasin B on 3-O-[(14)C]-methyl-D-glucose or D-[U-(14)C]glucose handling by BRIN-BD11 cells.

    PubMed

    Cetik, Sibel; Rzajeva, Aigun; Malaisse, Willy J; Sener, Abdullah

    2014-07-01

    The present study aimed to investigate the effects of cytochalasin B (20 μM) on the uptake of 3-O-[(14)C]-methyl-D-glucose or D-[U-(14)C]glucose (8.3 mM each) by BRIN-BD11 cells. Taking into account the distribution space of tritiated water ((3)HOH), which was unexpectedly increased shortly after exposure of the cells to cytochalasin B and then progressively returned to its control values, and that of L-[1-(14)C]glucose, used as an extracellular marker, it was demonstrated that cytochalasin B caused a modest, but significant inhibition of the uptake of D-glucose and its non-metabolized analog by the BRIN-BD11 cells. These findings resemble those observed in acinar or ductal cells of the rat submaxillary gland and displayed a relative magnitude comparable to that found for the inhibition of D-glucose metabolism by cytochalasin B in purified pancreatic islet B cells. These findings reinforce the view that the primary site of action of cytochalasin B is located at the level of the plasma membrane.

  15. 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.

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

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

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

  17. High-intensity geomagnetic field 'spike' observed at ca. 3000 cal BP in Texas, USA

    NASA Astrophysics Data System (ADS)

    Bourne, Mark D.; Feinberg, Joshua M.; Stafford, Thomas W.; Waters, Michael R.; Lundelius, Ernest; Forman, Steven L.

    2016-05-01

    By observing the fluctuations in direction and intensity of the Earth's magnetic field through time, we increase our understanding of the fluid motions of the Earth's outer core that sustain the geomagnetic field, the geodynamo. Recent archaeomagnetic studies in the Near East have found extremely rapid increases - 'spikes' - in geomagnetic field intensity at ca. 3000 yr cal BP. These observations have proved problematic for our current understanding of core-flow. However, until now, these geomagnetic spikes had not been observed outside of the Near East, where they have been preserved in metallurgical slag and fired, mud brick walls. We present a new, fully oriented, geomagnetic secular variation and relative palaeointensity (RPI) record for the last 17,000 yr from Hall's Cave, Texas, whose complete, >3.8 m thick sedimentary sequence spans from the present to 16 , 850 ± 110 RC yr BP (Modern to 20,600 cal BP). Within the stable, cool climate of the cave, pedogenic and bioturbation processes are negligible to non-existent, thereby limiting post-depositional physical and geochemical alteration of the magnetic record. The sub-aerial and subterranean setting of the sedimentary sequence in Hall's Cave enabled us to collect oriented palaeomagnetic cubes from a previously excavated stratigraphic section. The palaeomagnetic samples yielded high-quality vectors. An age model for the sequence, determined using 15 AMS 14C-dates on individual bones from microvertebrates, was combined with the palaeomagnetic data to construct a secular variation record. The record is in broad agreement with predictions by Holocene field models for the site's location. However, starting ca. 3000 yr ago, the RPI data indicate an almost four-fold increase in geomagnetic field intensity lasting several hundred years. This record presents well-dated evidence, obtained using conventional techniques, for the existence of a geomagnetic intensity spike in North America that is contemporaneous with the

  18. Low-level 14C methane oxidation rate measurements modified for remote field settings

    NASA Astrophysics Data System (ADS)

    Pack, M. A.; Pohlman, J.; Ruppel, C. D.; Xu, X.

    2012-12-01

    Aerobic methane oxidation limits atmospheric methane emissions from degraded subsea permafrost and dissociated methane hydrates in high latitude oceans. Methane oxidation rate measurements are a crucial tool for investigating the efficacy of this process, but are logistically challenging when working on small research vessels in remote settings. We modified a low-level 14C-CH4 oxidation rate measurement for use in the Beaufort Sea above hydrate bearing sediments during August 2012. Application of the more common 3H-CH4 rate measurement that uses 106 times more radioactivity was not practical because the R/V Ukpik cannot accommodate a radiation van. The low-level 14C measurement does not require a radiation van, but careful isolation of the 14C-label is essential to avoid contaminating natural abundance 14C measurements. We used 14C-CH4 with a total activity of 1.1 μCi, which is far below the 100 μCi permitting level. In addition, we modified field procedures to simplify and shorten sample processing. The original low-level 14C-CH4 method requires 6 steps in the field: (1) collect water samples in glass serum bottles, (2) inject 14C-CH4 into bottles, (3) incubate for 24 hours, (4) filter to separate the methanotrophic bacterial cells from the aqueous sample, (5) kill the filtrate with sodium hydroxide (NaOH), and (6) purge with nitrogen to remove unused 14C-CH4. Onshore, the 14C-CH4 respired to carbon dioxide or incorporated into cell material by methanotrophic bacteria during incubation is quantified by accelerator mass spectrometry (AMS). We conducted an experiment to test the possibility of storing samples for purging and filtering back onshore (steps 4 and 6). We subjected a series of water samples to steps 1-3 & 5, and preserved with mercuric chloride (HgCl2) instead of NaOH because HgCl2 is less likely to break down cell material during storage. The 14C-content of the carbon dioxide in samples preserved with HgCl2 and stored for up to 2 weeks was stable

  19. Reconstructing the Vertical 14C Gradient of the Baja Margin during the Last Deglaciation

    NASA Astrophysics Data System (ADS)

    Lindsay, C. M.; Lehman, S. J.; Marchitto, T. M.; Ortiz, J. D.; van Geen, A.

    2011-12-01

    The radiocarbon activity (Δ14C) of the atmosphere decreased in two steps during the last deglaciation, coinciding with the well-known Heinrich 1 (H1) and Younger Dryas (YD) stadials. A leading explanation for these periods of decline involves the release of 14C-depleted carbon from a deep, isolated ocean reservoir- a mechanism that may also help to explain the deglacial rise in atmospheric CO2. Reconstructions of intermediate water Δ14C near Baja California, Mexico (Marchitto et al., 2007 Science) and in the Arabian Sea (Bryan et al., 2010 Earth Planet. Sci. Lett.) document two intervals of extreme depletion relative to the coeval atmosphere during H1 and the YD that are interpreted as evidence of the return of this aged carbon from the deep reservoir to the upper ocean and atmosphere. Here we report on 14C measurements in additional cores from the Baja margin that expand the depth range of our observations and enable reconstruction of the vertical Δ14C gradient. Calendar ages were determined by (1) correlation of diffuse spectral reflectance (DSR, a proxy related to local productivity) with the layer-counted age model in the GISP2 ice core and (2) correlation of raw planktic G. ruber 14C ages to new measurements in core PC08 previously studied by Marchitto et al. (2007). Together these provide a common and consistent calendar age model for margin core PCO8 (depth 705 m), core PC13 from Soledad Basin (sill depth 290 m) and margin core GC38 (depth 1270 m). In preliminary results, G. ruber Δ14C data from PC08 exhibit a record of deglacial depletion events that is consistent with partial upward mixing of the intermediate-depth signal to the surface. Δ14C at 1270 meters showed relatively little change during H1 and YD, indicating that anomalously depleted water did not penetrate to this depth. The vertical gradient collapsed to within observational uncertainties at the start of the Bølling-Allerød/Antarctic Climate Reversal. Taken together the results support

  20. Intestinal absorption and tissue distribution of ( sup 14 C)pyrroloquinoline quinone in mice

    SciTech Connect

    Smidt, C.R.; Unkefer, C.J.; Houck, D.R.; Rucker, R.B. )

    1991-05-01

    Pyrroloquinoline quinone (PQQ) functions as a cofactor for prokaryotic oxidoreductases, such as methanol dehydrogenase and membrane-bound glucose dehydrogenase. In animals fed chemically defined diets, PQQ improves reproductive outcome and neonatal growth. Consequently, the present study was undertaken to determine the extent to which PQQ is absorbed by the intestine, its tissue distribution, and route of excretion. About 28 micrograms of PQQ (0.42 microCi/mumol), labeled with {sup 14}C derived from L-tyrosine, was administered orally to Swiss-Webster mice (18-20 g) to estimate absorption. PQQ was readily absorbed (62%, range 19-89%) in the lower intestine, and was excreted by the kidneys (81% of the absorbed dose) within 24 hr. The only tissues that retained significant amounts of ({sup 14}C)PQQ at 24 hr were skin and kidney. For kidney, it was assumed that retention of ({sup 14}C)PQQ represented primarily PQQ destined for excretion. For skin, the concentration of ({sup 14}C)PQQ increased from 0.3% of the absorbed dose at 6 hr to 1.3% at 24 hr. Furthermore, most of the ({sup 14}C)PQQ in blood (greater than 95%) was associated with the blood cell fraction, rather than plasma.

  1. In vitro synthesis and purification of UDP-( sup 14 C) galacturonate

    SciTech Connect

    Mitcham, E.J. ); Gross, K.C. ); Wasserman, B.P. )

    1989-04-01

    Pectins comprise a major component of the cell wall and much research has focused on degradation of pectins during ripening and senescence. However, little research has been conducted on pectin synthesis, partly due to a lack of commercial availability of UDP-({sup 14}C)galacturonic acid for use as a substrate in assaying galacturonan synthase. We report on the modification and integration of several procedures to synthesize UDP-({sup 14}C) galacturonic acid from commercially available UDP-({sup 14}C)glucuronic acid. A microsomal pellet containing UDP-D-glucuronate-4-epimerase was extracted from 5-day-old mung bean hypocotyls (Phaseolus aureus) and radish roots (Raphanus sativus L.) by ultracentrifugation at 30,000 rpm for 50 min. The UDP-({sup 14}C)galacturonic acid produced was separated from remaining UDP-({sup 14}C)glucuronic acid and other products by electrophoresis in pyridine:acetate:H{sub 2}O on silica gel. Spots were detected by autoradiography, eluted with 80% ethanol, and purified using anion exchange chromatography.

  2. Bioavailability of the Nano-Unit 14C-Agrochemicals Under Various Water Potential.

    PubMed

    Jung, S C; Kim, H G; Kuk, Y I; Ahn, H G; Senseman, S A; Lee, D J

    2015-08-01

    The study was conducted to investigate the effects of water potential on bioavailability of the nano-unit 14C-cafenstrole, 14C-pretilachlor, 14C-benfuresate, 14C-simetryn and 14C-oxyfluorfen applied with or without dimepiperate or daimuron under various water potential conditions. The highest bioavailable concentration in soil solution (BCSS) was found at 60% soil moisture, while the lowest occurred at 50% soil moisture for soil-applied alone or in combination. All water potential conditions differed significantly from each other with variations in total bioavailable amount in soil solution (TBSS) when either dimepiperate or daimuron were added to the soil, and changes were directly proportional to variations in water potential. Across all treatments, TBSS at 80% soil moisture was three to four times greater than that at 50% soil moisture when applied alone or in combination with dimepiperate or daimuron. Cafenstrole and simetryn had distribution coefficient (Kd) values <64 ml g-1 and a TBSS ranging from 10 to 44 ng g-1 soil, regardless of water potential conditions applied alone or in combination. Pretilachlor and benfuresate had Kd values <15 ml g-1 and a TBSS range of 38 to 255 ng g-1 soil when applied with or without dimepiperate or daimuron.

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

    SciTech Connect

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

    1991-10-01

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

  4. Modulation of (14) C-labeled glucose metabolism by zinc during aluminium induced neurodegeneration.

    PubMed

    Singla, Neha; Dhawan, D K

    2015-09-01

    Aluminium (Al) is one of the most prominent metals in the environment and is responsible for causing several neurological disorders, including Alzheimer's disease. On the other hand, zinc (Zn) is an essential micronutrient that is involved in regulating brain development and function. The present study investigates the protective potential of Zn in the uptake of (14) C-labeled amino acids and glucose and their turnover in rat brain slices during Al intoxication. Male Sprague Dawley rats (140-160 g) were divided into four different groups: normal control, Al treated (100 mg/kg body weight/day via oral gavage), Zn treated (227 mg/liter in drinking water), and Al + Zn treated. Radiorespirometric assay revealed an increase in glucose turnover after Al exposure that was attenuated after Zn treatment. Furthermore, the uptake of (14) C-labeled glucose was increased after Al treatment but was appreciably decreased upon Zn supplementation. In addition, the uptakes of (14) C-lysine, (14) C-leucine, and (14) C-aspartic acid were also found to be elevated following Al exposure but were decreased after Zn treatment. Al treatment also caused alterations in the neurohistoarchitecture of the brain, which were improved after Zn coadministration. Therefore, the present study suggests that Zn provides protection against Al-induced neurotoxicity by regulating glucose and amino acid uptake in rats, indicating that Zn could be a potential candidate for the treatment of various neurodegenerative disorders.

  5. An Inverse Method to Infer the Global Ocean Paleoventilation from the Atmospheric 14C Record

    NASA Astrophysics Data System (ADS)

    Marchal, O.; Hughen, K. A.; Muscheler, R.

    2001-12-01

    We present an inverse method to infer a record of global ocean ventilation (GOV) from records of atmospheric 14C activity (Δ 14C) and production. The method is based on the assimilation of activity and production data in a box model of the 14C cycle in the ocean-atmosphere-land biosphere system using the variational (adjoint) technique. It includes three components: (1) the model code that yields the value of the cost function (a measure of the misfit between observed and modelled Δ 14C); (2) the adjoint code that yields the partial derivatives of the cost function with respect to the parameters describing the temporal evolution of the GOV; and (3) an optimization procedure that yields the parameter values minimizing the cost function. Lagrange multipliers are introduced to simplify the calculation of the partial derivatives of the cost function and to construct the adjoint code directly from the model code. First we describe the method, outlining the formal similarities with the calculus of variation in analytical mechanics. Second we verify the method through the capability to recover a variety of GOV evolutions from the assimilation of artificial data ("twin experiments"). Third we apply the method to the Younger Dryas, using recent high-resolution records of Δ 14C from the Cariaco basin and of 10Be flux from Greenland ice cores. Our results give new insight into the role of the deep ocean circulation during this dramatic and rapid climate change in the circum North Atlantic area.

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

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

    PubMed

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

    1999-05-01

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

  8. Uptake and metabolism of (14C)-aspartate by developing kernels of maize (Zea mays L. )

    SciTech Connect

    Muhitch, M.J. )

    1990-05-01

    Pulse-chase experiments were performed to determine the metabolic fate of (14C)-aspartate in the pedicel region and subsequent uptake into the endosperm. Kernels were removed from the cob, leaving the pedicel attached but removing glumes, palea, and lemma. The basal tips were incubated in (14C)-aspartate for 0.5 h, followed by a 2 h chase period with unlabeled aspartate. In contrast to a previous study in which 70% of the 14C from aspartate was recovered in the organic acid fraction (Lyznik, et al., Phytochemistry 24: 425, 1985), only 20 to 25% of the radioactivity found in the 2 h chase period. While a small amount of the 14C transiently appeared in alanine at the beginning of the chase period, the most heavily labeled non-fed amino acid was glutamine, which accounted for 21% of the radioactivity within the pedicel amino acid fraction by 0.5 h into the chase period. There was no evidence for asparagine synthesis within the pedicel region of the kernel. 14C recovered from the endosperm in the form of amino acids were aspartate (60%), glutamine (20%), glutamate (15%), and alanine (5%). These results suggest that some of the maternally supplied amino acids undergo metabolic conversion to other amino acids before being taken up by the endosperm.

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

    SciTech Connect

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

    1981-09-01

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

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

    SciTech Connect

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

    2004-12-29

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

  11. Uptake and transfer of14C-simetryne through the laboratory freshwater food chain

    NASA Astrophysics Data System (ADS)

    Xu, Ying; Lay, J. P.; Zhang, Yongyuan

    1989-03-01

    This paper deals with the bioconcentration of14C-simetryne from water by aquatic test organisms: green algae— Monoraphidium minutum, rotifers— Brachionus rubens, daphnids— Daphnia magna, and fish— Brachydanio rerio. The chemical was bioconcentrated rapidly in all test species during the first 48 hours of experiment. The BCF values (bioconcentration factor) from all uptake studies show that simetryne has higher accumulation in algae than in rotifers, daphnids and zebra fish. The logarithm of the n-octanol/water partition coefficient of simetryne measured as 2.06±0.05 was correlated with the BCFs in the organisms as based on the lipid contents. 14C-simetryne uptake via the food-chain amounted to only 22% to 42% of the bioconcentration from water. Clearance of14C-derived residues from fish was rapid with a half-life of 2.1 days.

  12. Mobility Studies of (14)C-Chlorpyrifos in Malaysian Oil Palm Soils.

    PubMed

    Halimah, Muhamad; Ismail, B Sahid; Nashriyah, Mat; Maznah, Zainol

    2016-01-01

    The mobility of (14)C-chlorpyrifos using soil TLC was investigated in this study. It was found that chlorpyrifos was not mobile in clay, clay loam and peat soil. The mobility of (14)C-chlorpyrifos and non-labelled chlorpyrifos was also tested with silica gel TLC using three types of developing solvent hexane (100%), hexane:ethyl acetate (95:5, v/v); and hexane:ethyl acetate (98:2, v/v). The study showed that both the (14)C-labelled and non-labelled chlorpyrifos have the same Retardation Factor (Rf) for different developing solvent systems. From the soil column study on mobility of chlorpyrifos, it was observed that no chlorpyrifos residue was found below 5 cm depth in three types of soil at simulation rainfall of 20, 50 and 100 mm. Therefore, the soil column and TLC studies have shown similar findings in the mobility of chlorpyrifos.

  13. Mobility Studies of (14)C-Chlorpyrifos in Malaysian Oil Palm Soils.

    PubMed

    Halimah, Muhamad; Ismail, B Sahid; Nashriyah, Mat; Maznah, Zainol

    2016-01-01

    The mobility of (14)C-chlorpyrifos using soil TLC was investigated in this study. It was found that chlorpyrifos was not mobile in clay, clay loam and peat soil. The mobility of (14)C-chlorpyrifos and non-labelled chlorpyrifos was also tested with silica gel TLC using three types of developing solvent hexane (100%), hexane:ethyl acetate (95:5, v/v); and hexane:ethyl acetate (98:2, v/v). The study showed that both the (14)C-labelled and non-labelled chlorpyrifos have the same Retardation Factor (Rf) for different developing solvent systems. From the soil column study on mobility of chlorpyrifos, it was observed that no chlorpyrifos residue was found below 5 cm depth in three types of soil at simulation rainfall of 20, 50 and 100 mm. Therefore, the soil column and TLC studies have shown similar findings in the mobility of chlorpyrifos. PMID:26546229

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

    PubMed

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

    1998-01-01

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

  15. 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.

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

    SciTech Connect

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

    1998-09-01

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

  17. An analytical method for 14C in environmental water based on a wet-oxidation process.

    PubMed

    Huang, Yan-Jun; Guo, Gui-Yin; Wu, Lian-Sheng; Zhang, Bing; Chen, Chao-Feng; Zhang, Hai-Ying; Qin, Hong-Juan; Shang-Guan, Zhi-Hong

    2015-04-01

    An analytical method for (14)C in environmental water based on a wet-oxidation process was developed. The method can be used to determine the activity concentrations of organic and inorganic (14)C in environmental water, or total (14)C, including in drinking water, surface water, rainwater and seawater. The wet-oxidation of the organic component allows the conversion of organic carbon to an inorganic form, and the extraction of the inorganic (14)C can be achieved by acidification and nitrogen purging. Environmental water with a volume of 20 L can be used for the wet-oxidation and extraction, and a detection limit of about 0.02 Bq/g(C) can be achieved for water with carbon content above 15 mg(C)/L, obviously lower than the natural level of (14)C in the environment. The collected carbon is sufficient for measurement with a low level liquid scintillation counter (LSC) for typical samples. Extraction or recovery experiments for inorganic carbon and organic carbon from typical materials, including analytical reagents of organic benzoquinone, sucrose, glutamic acid, nicotinic acid, humic acid, ethane diol, et cetera., were conducted with excellent results based on measurement on a total organic carbon analyzer and LSC. The recovery rate for inorganic carbon ranged tween 98.7%-99.0% with a mean of 98.9(± 0.1)%, for organic carbon recovery ranged between 93.8% and 100.0% with a mean of 97.1(± 2.6)%. Verification and an uncertainty budget of the method are also presented for a representative environmental water. The method is appropriate for (14)C analysis in environmental water, and can be applied also to the analysis of liquid effluent from nuclear facilities. PMID:25590997

  18. Effect of foliar treatments on distribution of /sup 14/C-glyphosate in Convolvulus arvensis L

    SciTech Connect

    Lauridson, T.C.

    1986-01-01

    Field bindweed is a perennial weed which produces shoots from buds on its roots. Herbicides, such as glyphosate (N-(phosphonomethyl)glycine) used for control of field bindweed usually do not kill all shoot buds on the roots, thus field bindweed often reinfests areas within 3 to 6 weeks of treatment. This dissertation deals with the development of a technique to change glyphosate distribution in field bindweed roots and could result in less shoot regrowth after glyphosate application. In field studies eight plant growth regulators were applied in September, 3 days before 2.24 kg/ha of 2.4-D((2,4-dichlorophenoxy) acetic acid) or 1.68 kg/ha of glyphosate. Eight months later, regrowth of shoots was least where glyphosate was applied at 0.028 kg/ha as a pretreatment, followed by a standard rate of 1.68 kg/ha. In subsequent greenhouse studies, typical patterns of shoot growth and /sup 14/C-glyphosate distribution in isolated root sections taken from 15-week-old intact plants were determined. In subsequent growth chamber studies, plants were decapitated to observe the effect of shoot apical dominance on /sup 14/C-glyphosate translocation. After /sup 14/C-glyphosate was applied, intact plants had about twice as much /sup 14/C in distal root sections as in proximal or middle root sections. Decapitated plants had more /sup 14/C in proximal and middle root sections than in distal sections, and about twice as much /sup 14/C was translocated to roots of decapitated plants than intact plants. Eight concentrations of 2,4,-D or glyphosate from 1 to 5000 ppm were applied in logarithmic series to 6-week old plants.

  19. An analytical method for 14C in environmental water based on a wet-oxidation process.

    PubMed

    Huang, Yan-Jun; Guo, Gui-Yin; Wu, Lian-Sheng; Zhang, Bing; Chen, Chao-Feng; Zhang, Hai-Ying; Qin, Hong-Juan; Shang-Guan, Zhi-Hong

    2015-04-01

    An analytical method for (14)C in environmental water based on a wet-oxidation process was developed. The method can be used to determine the activity concentrations of organic and inorganic (14)C in environmental water, or total (14)C, including in drinking water, surface water, rainwater and seawater. The wet-oxidation of the organic component allows the conversion of organic carbon to an inorganic form, and the extraction of the inorganic (14)C can be achieved by acidification and nitrogen purging. Environmental water with a volume of 20 L can be used for the wet-oxidation and extraction, and a detection limit of about 0.02 Bq/g(C) can be achieved for water with carbon content above 15 mg(C)/L, obviously lower than the natural level of (14)C in the environment. The collected carbon is sufficient for measurement with a low level liquid scintillation counter (LSC) for typical samples. Extraction or recovery experiments for inorganic carbon and organic carbon from typical materials, including analytical reagents of organic benzoquinone, sucrose, glutamic acid, nicotinic acid, humic acid, ethane diol, et cetera., were conducted with excellent results based on measurement on a total organic carbon analyzer and LSC. The recovery rate for inorganic carbon ranged tween 98.7%-99.0% with a mean of 98.9(± 0.1)%, for organic carbon recovery ranged between 93.8% and 100.0% with a mean of 97.1(± 2.6)%. Verification and an uncertainty budget of the method are also presented for a representative environmental water. The method is appropriate for (14)C analysis in environmental water, and can be applied also to the analysis of liquid effluent from nuclear facilities.

  20. Application and detection of (14)c-hd in two mouse models.

    PubMed

    Logan, Thomas P; Shutz, Michael; Schulz, Susan M; Railer, Roy; Ricketts, Karen M; Casillas, Robert P

    2002-01-01

    The CD1-haired mouse and the SKH-hairless mouse are two animal models that have been used to evaluate sulfur mustard (HD) exposure and protection in our laboratory. In a recent study we observed that a substance P inhibitor protected the haired mouse ear against an HD solution, but the same drug was not successful in protecting the hairless mouse against HD vapor. This experiment prompted us to compare HD exposures between these models. We determined the (14)C content in the skin after exposures to HD containing (14)C-HD. Rate curves were generated for applications of (1) HD in methylene chloride to the haired mouse ear; (2) HD in methylene chloride to the hairless mouse dorsal skin; and (3) saturated HD vapor to the hairless mouse dorsal skin for 6 min. The curves showed a reduction in (14)C disintegrations per min in animals euthanized 0 to 2 h postexposure. The largest percentage of decrease of (14)C content in skin occurred within 30 min of HD challenge for all exposures. An 8-mm skin-punch biopsy and a 14-mm annular skin section surrounding the region of the 8-mm skin punch were taken from the hairless mouse dorsal skin exposed to HD in methylene chloride. The ratio of the (14)C content in the 8-mm skin punch to that in the surrounding 14-mm annular skin section was 7.3, demonstrating that the HD application spreads beyond the initially biopsied site. A concentration/time value of 6.3 mug/cm(2)/min was determined by counting skin (14)C disintegrations per minute in animals euthanized immediately after exposure to saturated HD vapor. Determinations of the amount of HD showed that similar quantities of HD, 0.4 mg, were detected on each model. These results contribute to a better quantitative understanding of HD application in the haired and hairless mouse models.

  1. A study of placental transfer mechanisms in nonhuman primates using (/sup 14/C)phenylalanine

    SciTech Connect

    Pueschel, S.M.; Boylan, J.M.; Jackson, B.T.; Piasecki, G.J.

    1982-02-01

    Placental transfer mechanisms were investigated in pregnant Macaca Fascicularis and Macaca mulatta during the gestational age of 120 to 130 days. These primates underwent an operative procedure that allowed continuous fetal blood sampling. The administration of (/sup 14/C)phenylalanine into the maternal circulation revealed a significant increase of radioactive material in the fetal circulation, indicating an active placental transport mechanism unidirectional to the fetus. When (/sup 14/C)phenylalanine was injected into the fetus, radioactive aromatic amino acids in the maternal circulation increased only slightly over time, resembling a simple diffusion process.

  2. In vivo survival of (14C)sucrose-loaded porcine carrier erythrocytes

    SciTech Connect

    DeLoach, J.R.

    1983-06-01

    Porcine carrier erythrocyte survival was measured in adult pigs. (14C)Sucrose-loaded erythrocytes had a biphasic survival curve, with as much as 50% of the cells removed from circulation in the first 24 hours. The remaining cells had a 35-day half-life. Encapsulation values were measured for porcine erythrocytes and entrapment of (14C)sucrose was greater than 45%. Addition of inosine and glucose to the dialyzed cells and to the final wash buffer before reinjection of autologous cells did not improve their survival.

  3. Variations of 14C around AD 775 and AD 1795 - due to solar activity

    NASA Astrophysics Data System (ADS)

    Neuhäuser, R.; Neuhäuser, D. L.

    2015-12-01

    The motivation for our study is the disputed cause for the strong variation of 14C around AD 775. Our method is to compare the 14C variation around AD 775 with other periods of strong variability. Our results are: (a) We see three periods, where 14C varied over 200 yr in a special way showing a certain pattern of strong secular variation: after a Grand Minimum with strongly increasing 14C, there is a series of strong short-term drop(s), rise(s), and again drop(s) within 60 yr, ending up to 200 yr after the start of the Grand Minimum. These three periods include the strong rises around BC 671, AD 775, and AD 1795. (b) We show with several solar activity proxies (radioisotopes, sunspots, and aurorae) for the AD 770s and 1790s that such intense rapid 14C increases can be explained by strong rapid decreases in solar activity and, hence, wind, so that the decrease in solar modulation potential leads to an increase in radioisotope production. (c) The strong rises around AD 775 and 1795 are due to three effects, (i) very strong activity in the previous cycles (i.e. very low 14C level), (ii) the declining phase of a very strong Schwabe cycle, and (iii) a phase of very weak activity after the strong 14C rise - very short and/or weak cycle(s) like the suddenly starting Dalton minimum. (d) Furthermore, we can show that the strong change at AD 1795 happened after a pair of two packages of four Schwabe cycles with certain hemispheric leadership (each package consists of two Gnevyshev-Ohl pairs, respectively two Hale-Babcock pairs). We show with several additional arguments that the rise around AD 775 was not that special. We conclude that such large, short-term rises in 14C (around BC 671, AD 775, and 1795) do not need to be explained by highly unlikely solar super-flares nor other rare events, but by extra-solar cosmic rays modulated due to solar activity variations.

  4. A rapid phospholipase A2 bioassay using 14C-oleate-labelled E. coli bacterias.

    PubMed

    Meyer, T; von Wichert, P; Weins, D

    1989-02-01

    Two methods of phospholipase A2 determination using 14C-labelled E. coli bacterias as substrate were compared. One method works with a filter membrane for separation of cleaved 14C-oleate from remaining phospholipids, the other uses the well-known thin-layer chromatography for lipid analysis. Some features of human serum phospholipase A2 regarding pH and Ca2+ dependency were investigated. Possible sources of errors were discussed. It was shown that either method can differentiate between normal and pathologically elevated phospholipase A2 levels, but that the filter method is superior in terms of sensitivity and workload.

  5. Disposition of [14C]methyl bromide in rats after inhalation.

    PubMed

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

    1985-04-01

    Methyl bromide is used as a disinfectant to fumigate soil and a wide range of stored food commodities in warehouses and mills. Human exposure occurs during the manufacture and use of the chemical. The purpose of this investigation was to determine the disposition and metabolism of [14C]methyl bromide in rats after inhalation. Male Fischer-344 rats were exposed nose only to a vapor concentration of 337 nmol [14C]methyl bromide/liter air (9.0 ppm, 25 degrees C, 620 torr) for 6 hr. Urine, feces, expired air, and tissues were collected for up to 65 hr after exposure. Elimination of 14C as 14CO2 was the major route of excretion with about 47% (3900 nmol/rat) of the total [14C]methyl bromide absorbed excreted by this route. CO2 excretion exhibited a biphasic elimination pattern with 85% of the 14CO2 being excreted with a half-time of 3.9 +/- 0.1 hr (means +/- SE) and 15% excreted with a half-time of 11.4 +/- 0.2 hr. Half-times for elimination of 14C in urine and feces were 9.6 +/- 0.1 and 16.1 +/- 0.1 hr, respectively. By 65 hr after exposure, about 75% of the initial radioactivity had been excreted with 25% remaining in the body. Radioactivity was widely distributed in tissues immediately following exposure with lung (250 nmol equivalents/g), adrenal (240 nmol equivalents/g), kidney (180 nmol equivalents/g), liver (130 nmol equivalents/g), and nasal turbinates (110 nmol equivalents/g) containing the highest concentrations of 14C. Radioactivity in livers immediately after exposure accounted for about 17% of the absorbed methyl bromide. Radioactivity in all other tissues examined accounted for about 10% of the absorbed methyl bromide. Elimination half-times of 14C from tissues were on the order of 1.5 to 8 hr. In all tissues examined, over 90% of the 14C in the tissues was methyl bromide metabolites. The data from this study indicate that after inhalation methyl bromide is rapidly metabolized in tissues and readily excreted.

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  7. Percutaneous absorption of (7. 10-/sup 14/C)benzo(a)pyrene and (7,12-/sup 14/C)dimethylbenz(a)anthracene in mice

    SciTech Connect

    Sanders, C.L.; Skinner, C.; Gelman, R.A.

    1984-04-01

    The percutaneous penetration, tissue distribution, and excretion of /sup 14/C-labeled benzo(a)pyrene (BaP) and dimethylbenz(a)anthracene (DMBA) were studied in mice. Both BaP and DMBA rapidly penetrated the skin and were excreted more in the feces than in the urine. The proportion of BaP or DMBA absorbed was less with increasing applied dose due to apparent saturation of the uptake process. Uptake from the dorsal skin of the nose was similar to uptake from the dorsal nuchal skin. 24 references.

  8. Sorption and degradation of 14C-Atrazine in oat straw and in Brazilian Acrisol under no-tillage

    NASA Astrophysics Data System (ADS)

    Barbosa, D.; Dick, D.; Burauel, P.; Langen, U.; Koeppchen, S.

    2012-04-01

    The worldwide use of the herbicide atrazine (ATZ) resulted in its distribution in soil and aquatic systems, which lead to its prohibition by the European Union Member States. In Brazil, ATZ is still widely applied for broadleaf control in maize, soybean and sugar cane crops. Due to changing agricultural management systems from tillage to no-tillage or conservation tillage systems, information on the environmental fate (sorption/desorption and degradation) and behavior of ATZ is needed when this herbicide is applied to the straw cover in no-tillage systems. Our study evaluates the pattern of ATZ degradation in a Brazilian Acrisol used for agricultural purposes under no-tillage treatment. The incubation experiments were conducted for 85 days in order to compare the mineralization, formation of metabolites and nonextractable residues of ATZ in two soils with a different ATZ application and soil management history: cultivated soil - the soil was exposed to ATZ application for more than 10 years; native soil - the soil was collected at an adjacent area with no history of ATZ application. An incubation experiment using a layer of oat straw on the soil surface was conducted to evaluate the sorption, the mineralization, formation of metabolites and nonextractable residues formation of ATZ in the straw compared to the soil alone. First results showed higher 14C-ATZ mineralization in cultivated soil (around 86% of the total amount of 14C activity applied) in comparison to the native soil (around 8% of the amount applied) after 68 days of incubation. The water-extractable amount of 14C-ATZ directly after its application was >60% of the amount applied and it decreased during the time in both soils. However, the water-extractable amount of 14C-ATZ in the cultivated soil was lower than in the native soil due to its higher mineralization. The water-extractable metabolites detected were hydroxyatrazine and deethylatrazine. The water-extractable amount of deethylatrazine was higher

  9. Distribution of root exudates and mucilage in the rhizosphere: combining 14C imaging with neutron radiography

    NASA Astrophysics Data System (ADS)

    Holz, Maire; Carminati, Andrea; Kuzyakov, Yakov

    2015-04-01

    Water and nutrients will be the major factors limiting food production in future. Plant roots employ various mechanisms to increase the access to limited soil resources. Low molecular weight organic substances released by roots into the rhizosphere increase nutrient availability by interactions with microorganisms, while mucilage improves water availability under low moisture conditions. Though composition and quality of these substances have intensively been investigated, studies on the spatial distribution and quantification of exudates in soil are scarce. Our aim was to quantify and visualize root exudates and mucilage distribution around growing roots using neutron radiography and 14C imaging depending on drought stress. Plants were grown in rhizotrons well suited for neutron radiography and 14C imaging. Plants were exposed to various soil water contents experiencing different levels of drought stress. The water content in the rhizosphere was imaged during several drying/wetting cycles by neutron radiography. The radiographs taken a few hours after irrigation showed a wet region around the root tips showing the allocation and distribution of mucilage. The increased water content in the rhizosphere of the young root segments was related to mucilage concentrations by parameterization described in Kroener et al. (2014). In parallel 14C imaging of root after 14CO2 labeling of shoots (Pausch and Kuzyakov 2011) showed distribution of rhizodeposits including mucilage. Three days after setting the water content, plants were labeled in 14CO2 atmosphere. Two days later 14C distribution in soil was imaged by placing a phosphor-imaging plate on the rhizobox. To quantify rhizodeposition, 14C activity on the image was related to the absolute 14C activity in the soil and root after destructive sampling. By comparing the amounts of mucilage (neutron radiography) with the amount of total root derived C (14C imaging), we were able to differentiate between mucilage and root

  10. Human (Clovis)-gomphothere (Cuvieronius sp.) association ∼ 13,390 calibrated yBP in Sonora, Mexico.

    PubMed

    Sanchez, Guadalupe; Holliday, Vance T; Gaines, Edmund P; Arroyo-Cabrales, Joaquín; Martínez-Tagüeña, Natalia; Kowler, Andrew; Lange, Todd; Hodgins, Gregory W L; Mentzer, Susan M; Sanchez-Morales, Ismael

    2014-07-29

    The earliest known foragers to populate most of North America south of the glaciers [∼ 11,500 to ≥ ∼ 10,800 (14)C yBP; ∼ 13,300 to ∼ 12,800 calibrated (Cal) years] made distinctive "Clovis" artifacts. They are stereotypically characterized as hunters of Pleistocene megamammals (mostly mammoth) who entered the continent via Beringia and an ice-free corridor in Canada. The origins of Clovis technology are unclear, however, with no obvious evidence of a predecessor to the north. Here we present evidence for Clovis hunting and habitation ∼ 11,550 yBP (∼ 13,390 Cal years) at "El Fin del Mundo," an archaeological site in Sonora, northwestern Mexico. The site also includes the first evidence to our knowledge for gomphothere (Cuvieronius sp.) as Clovis prey, otherwise unknown in the North American archaeological record and terminal Pleistocene paleontological record. These data (i) broaden the age and geographic range for Clovis, establishing El Fin del Mundo as one of the oldest and southernmost in situ Clovis sites, supporting the hypothesis that Clovis had its origins well south of the gateways into the continent, and (ii) expand the make-up of the North American megafauna community just before extinction. PMID:25024193

  11. Human (Clovis)-gomphothere (Cuvieronius sp.) association ∼ 13,390 calibrated yBP in Sonora, Mexico.

    PubMed

    Sanchez, Guadalupe; Holliday, Vance T; Gaines, Edmund P; Arroyo-Cabrales, Joaquín; Martínez-Tagüeña, Natalia; Kowler, Andrew; Lange, Todd; Hodgins, Gregory W L; Mentzer, Susan M; Sanchez-Morales, Ismael

    2014-07-29

    The earliest known foragers to populate most of North America south of the glaciers [∼ 11,500 to ≥ ∼ 10,800 (14)C yBP; ∼ 13,300 to ∼ 12,800 calibrated (Cal) years] made distinctive "Clovis" artifacts. They are stereotypically characterized as hunters of Pleistocene megamammals (mostly mammoth) who entered the continent via Beringia and an ice-free corridor in Canada. The origins of Clovis technology are unclear, however, with no obvious evidence of a predecessor to the north. Here we present evidence for Clovis hunting and habitation ∼ 11,550 yBP (∼ 13,390 Cal years) at "El Fin del Mundo," an archaeological site in Sonora, northwestern Mexico. The site also includes the first evidence to our knowledge for gomphothere (Cuvieronius sp.) as Clovis prey, otherwise unknown in the North American archaeological record and terminal Pleistocene paleontological record. These data (i) broaden the age and geographic range for Clovis, establishing El Fin del Mundo as one of the oldest and southernmost in situ Clovis sites, supporting the hypothesis that Clovis had its origins well south of the gateways into the continent, and (ii) expand the make-up of the North American megafauna community just before extinction.

  12. Human (Clovis)–gomphothere (Cuvieronius sp.) association ∼13,390 calibrated yBP in Sonora, Mexico

    PubMed Central

    Sanchez, Guadalupe; Holliday, Vance T.; Gaines, Edmund P.; Arroyo-Cabrales, Joaquín; Martínez-Tagüeña, Natalia; Kowler, Andrew; Lange, Todd; Hodgins, Gregory W. L.; Mentzer, Susan M.; Sanchez-Morales, Ismael

    2014-01-01

    The earliest known foragers to populate most of North America south of the glaciers [∼11,500 to ≥ ∼10,800 14C yBP; ∼13,300 to ∼12,800 calibrated (Cal) years] made distinctive “Clovis” artifacts. They are stereotypically characterized as hunters of Pleistocene megamammals (mostly mammoth) who entered the continent via Beringia and an ice-free corridor in Canada. The origins of Clovis technology are unclear, however, with no obvious evidence of a predecessor to the north. Here we present evidence for Clovis hunting and habitation ∼11,550 yBP (∼13,390 Cal years) at “El Fin del Mundo,” an archaeological site in Sonora, northwestern Mexico. The site also includes the first evidence to our knowledge for gomphothere (Cuvieronius sp.) as Clovis prey, otherwise unknown in the North American archaeological record and terminal Pleistocene paleontological record. These data (i) broaden the age and geographic range for Clovis, establishing El Fin del Mundo as one of the oldest and southernmost in situ Clovis sites, supporting the hypothesis that Clovis had its origins well south of the gateways into the continent, and (ii) expand the make-up of the North American megafauna community just before extinction. PMID:25024193

  13. Human (Clovis)-gomphothere (Cuvieronius sp.) association ∼13,390 calibrated yBP in Sonora, Mexico

    NASA Astrophysics Data System (ADS)

    Sanchez, Guadalupe; Holliday, Vance T.; Gaines, Edmund P.; Arroyo-Cabrales, Joaquín; Martínez-Tagüeña, Natalia; Kowler, Andrew; Lange, Todd; Hodgins, Gregory W. L.; Mentzer, Susan M.; Sanchez-Morales, Ismael

    2014-07-01

    The earliest known foragers to populate most of North America south of the glaciers [∼11,500 to ≥ ∼10,800 14C yBP; ∼13,300 to ∼12,800 calibrated (Cal) years] made distinctive "Clovis" artifacts. They are stereotypically characterized as hunters of Pleistocene megamammals (mostly mammoth) who entered the continent via Beringia and an ice-free corridor in Canada. The origins of Clovis technology are unclear, however, with no obvious evidence of a predecessor to the north. Here we present evidence for Clovis hunting and habitation ∼11,550 yBP (∼13,390 Cal years) at "El Fin del Mundo," an archaeological site in Sonora, northwestern Mexico. The site also includes the first evidence to our knowledge for gomphothere (Cuvieronius sp.) as Clovis prey, otherwise unknown in the North American archaeological record and terminal Pleistocene paleontological record. These data (i) broaden the age and geographic range for Clovis, establishing El Fin del Mundo as one of the oldest and southernmost in situ Clovis sites, supporting the hypothesis that Clovis had its origins well south of the gateways into the continent, and (ii) expand the make-up of the North American megafauna community just before extinction.

  14. [sup 14]C and [sup 10]Be evidence for no incursion of the Lake Michigan lobe in northern Illinois from ca. 170 to 25 ka

    SciTech Connect

    Curry, B.B. ); Pavich, M.J. )

    1994-04-01

    Uncorrected [sup 10]Be inventories of a 2.7 m-long section of core indicate surface exposure lasting 115 ka during development of the Sangamon Geosol and 30 ka for a soil complex developed in overlying loessial sediment (Robein Silt). The latter estimate is in agreement with [sup 14]C assays in the region. Taking into account the age of overlying late Wisconsin drift, the new data indicate an age of about 170 ka for the onset of Sangamon pedogenesis in northern Illinois. Previous to this study, there have been no numerical-age determinations for the start of the last interglacial in northern IL. The data confirm a previous hypothesis that the Lake Michigan Lobe did not invade IL contemporaneous with deposition of Roxana Silt, or during the other period of midcontinental loess deposition suggest by TL ages of ca. 70 to 85 ka. The core was collected immediately south of the IL-WI border (42[degree] 30 minutes N, 88[degree] 30 minutes W) near Hebron, IL. Buried by 14 m of late Wisconsin drift, and the interval assayed for [sup 10]Be included 2.0 m of pedogenically-altered Illinoian sand and gravel, and 0.7 m of Wisconsin silt. One AMS [sup 14]C assay of carbonized fragments from the A-horizon of the Sangamon Geosol yielded an age of 38,500 [+-] 5,000 yr B.P.; conventional [sup 14]C ages for the overlying silt are from wood fragments (24,780 [times] 360 yr B.P.) and a bulk soil sample (26,030 [+-] 450 yr B.P.). The range of ages is typical for this stratigraphic sequence in IL. The [sup 10]Be concentration in the lowest part of the silt is 600 atoms/gm. This value is three times greater than the concentration typical of calcareous Mississippi River valley loess and of the C-horizon of the Sangamon Geosol in the core. High concentration of [sup 10]Be in the Robein Silt likely was caused by redeposition of [sup 10]Be-rich B-horizon material eroded from soil profiles elsewhere in the paleobasin.

  15. 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.

  16. Fate of organochlorine 14C-dicofol in a lab-scale wastewater treatment

    PubMed Central

    Oliveira, Jaime L. M.; Langenbach, Tomaz; Dezotti, Márcia

    2008-01-01

    The fate of organochlorine 14C-dicofol in activated sludge process was investigated. Results showed that the major part of radioactivity remained adsorbed on biological sludge. Consequently, its final disposal deserves special attention. The small amounts of dicofol, biotransformed or not, which remained in the treated effluent could contaminate receiving bodies. PMID:24031222

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

    USGS Publications Warehouse

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

    2004-01-01

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

  18. 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.

  19. 14C-most-probable-number method for enumeration of active heterotrophic microorganisms in natural waters.

    PubMed Central

    Lehmicke, L G; Williams, R T; Crawford, R L

    1979-01-01

    A most-probable-number method using 14C-labeled substrates is described for the enumeration of aquatic populations of heterotrophic microorganisms. Natural populations of microorganisms are inoculated into dilution replicates prepared from the natural water from which the organisms originated. The natural water is supplemented with a 14C-labeled compound added so as to approximate a true environmental concentration. 14CO2 evolved by individual replicates is trapped in NaOH and counted by liquid scintillation techniques for use in scoring replicates as positive or negative. Positives (14CO2 evolution) are easily distinguished from negatives (no 14CO2 evolution). The results from a variety of environments using the 14CO2 procedure agreed well with previously described methods, in most instances. The 14C-most-probable-number method described here reduces handling procedures over previously described most-probable-number procedures using 14C-labeled substrates. It also appears to have advantages over other enumeration methods in its attempt to approximate natural conditions more closely. PMID:120133

  20. Disposition of 14C-derived residues in tissues of pigs fed radiolabelled fumonisin B1.

    PubMed

    Prelusky, D B; Miller, J D; Trenholm, H L

    1996-01-01

    The uptake and distribution of radioactive material-derived residues were determined in tissues of growing pigs consuming 14C-labelled fumonisin B1 (FB1) in the diet. Animals were fed 3.0 mg (3.0 microCi) 14C-FB1/kg feed from days 1-12, followed by 2.0 mg (2.0 microCi) 14C-FB1/kg feed during days 13-24, followed by a 9-day withdrawal period where pigs received clean feed only. Of the tissues analysed, residues were found to accumulate only in liver and kidney. Radioactivity was detected at the first sampling time (day 3), and continued to increase until the 14C-toxin was removed from the diet. Peak tissue levels (dpm/g tissue +/- SD, N = 2) in liver and kidney were 347 +/- 28 and 146 +/- 14, respectively, on day 24, which were equivalent to about 160 and 65 ng FB1 and/or metabolites per g tissue, respectively. Once pigs were placed on clean feed, tissue levels declined rapidly; down to approximately 35% of peak levels after 3 days, and only marginally above detection limits (approximately 25 dpm/g) after 9 days. Delayed recovery of the radioactive material consumed indicated a persistence within the body of FB1-derived residues, which could be eliminated only upon removal of the contaminated diet. PMID:9064240

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

    USGS Publications Warehouse

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

    1992-01-01

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

  2. Kinetics of the uptake of sup 14 C-labeled chlorinated benzenes from soil by plants

    SciTech Connect

    Topp, E.; Scheunert, I.; Korte, F. )

    1989-04-01

    ({sup 14}C)Benzene, ({sup 14}C)1,2,4-trichlorobenzene, ({sup 14}C)pentachlorobenzene, and ({sup 14}C)hexachlorobenzene were applied to soils in outdoor lysimeters to a 10-cm depth (2 mg/kg dry soil); barley and cress plants were grown for one vegetation period and analyzed after varying time intervals. The bioaccumulation factors (concentration of radioactive substances in plants divided by that in soils) of barley were higher than those of cress, except for hexachlorobenzene. In barley, bioaccumulation factors increased with decreasing chlorine content of the molecules, except for benzene, whereas in cress hexachlorobenzene exhibited the highest bioaccumulation factor. The conversion ratios of chlorinated benzenes (percentage of conversion products based on total radioactivity in plants) were negatively correlated to the chlorine content of the molecules and, in barley, positively correlated with time; in general, they were higher in barley than in cress. The concentration of radioactive substances in the plants, as well as bioaccumulation factors, decreased with time, except for a slight increase in benzene-derived residues in barley after 125 days. This effect is due to growth dilution. The percentage of radioactivity in barley seeds, based on that in the whole plant, was negatively correlated to the chlorine content of the molecule.

  3. 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.

  4. Pharmacodynamic behavior of (/sup 14/C)acridine in the cricket Acheta domesticus (L. )

    SciTech Connect

    Walton, B.T.; Maggart, E.F. Jr.

    1981-11-01

    Cuticular and gastrointestinal penetration, in vivo metabolism, and excretion of (/sup 14/C)acridine were investigated in the nymphal cricket Acheta domesticus (L.) to find a pharmacodynamic basis for this insect's differential susceptibility to acridine at different life stages. Topically applied (/sup 14/C)acridine readily penetrated the cuticular exoskeleton of nymphs (half-time of penetration, 48 min). Radiolabeled compounds appeared in the hemolymph within 0.5 h after ingestion of (/sup 14/C)acridine and continued to move across the gut wall for 7.5 h. The biological half-time was 18 h and the rate constant for elimination was 0.039 h/sup -1/ after ingestion. Within 5 d after dosing, 97% of the dose was excreted. Several metabolites were present in the feces of nymphs fed (/sup 14/C)acridine, and less than 13% of the extractable radioactivity was parent compound. The cuticule and the gastrointestinal tract proved to be ineffective barriers to acridine entry in A. domesticus. However, the ability to readily metabolize and excrete acridine probably contributes to the higher acridine tolerance observed in the nymphs and adults than in the eggs, which are susceptible to toxic effects. Acridine is found in many coal and synthetic fuel by-products.

  5. Anaerobic oxidation of [1,2-14C]dichloroethene under Mn(IV)-reducing conditions

    USGS Publications Warehouse

    Bradley, P.M.; Landmeyer, J.E.; Dinicola, R.S.

    1998-01-01

    Anaerobic oxidation of [1,2-14C]dichloroethene to14CO2 under Mn(IV)-reducing conditions was demonstrated. The results indicate that oxidative degradation of partially chlorinated solvents like dichloroethene can be significant even under anoxic conditions and demonstrate the potential importance of Mn(IV) reduction for remediation of chlorinated groundwater contaminants.

  6. Investigation of {sup 14}C release in an engineered low-level waste disposal facility

    SciTech Connect

    Yim, M.S.; Simonson, S.A.; Sullivan, T.M.

    1996-05-01

    Atmospheric releases of {sup 14}C from a generic engineered low-level waste (LLW) disposal facility and its radiological impacts are investigated. A computer model that describes microbial gas generation and the transport has been developed and used to analyze the generation of {sup 14}C contaminated gases and subsequent migration in a facility. Models are based on a chemical kinetic description of aerobic and anaerobic decomposition of organic materials coupled with attending models of oxygen transport and consumption within waste containers in a facility. Effects of radiolysis on gas generation are addressed based on the estimated dose rate for class B and C wastes. Estimates predict that annual atmospheric release of {sup 14}C due to atmospheric pressure variations could range between {approximately}2.6 {times} 10{sup 8} and 5.5 {times} 10{sup 11} Bq as a result of microbial gas generation based on a volume of 48 000 m{sup 3} LLW disposed in a facility. The associated dose to a maximally exposed individual is estimated to be dominated by ingestion pathway and strongly depends on the fraction of the food imported from an uncontaminated outside area. Dose rates are expected to be <0.04 mSv/yr, considering a reasonable distance between the facility and the exposed population. The depletion through airborne releases of {sup 14}C inventory that is available for transport through other pathways is not expected to be a significant issue.

  7. 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

  8. Movement of 14C-labeled Sugars into Kernels of Wheat (Triticum aestivum L.) 1

    PubMed Central

    Sakri, Faisal A. K.; Shannon, Jack C.

    1975-01-01

    An anatomical study of wheat (Triticum aestivum L.) kernels 14 days after anthesis revealed that the tracheary elements of the pericarp vascular bundle are not in direct continuity with those of the rachilla. The phloem was continuous from the rachilla into the crease of the pericarp. Shortly after exposure of the flag leaf to 14CO2, relatively high proportion of the 14C extracted from the pericarp and endosperm was found in glucose and fructose. With additional time, the percentage of 14C in the monosaccharides declined and that in sucrose increased to a maximum 3 hours after 14CO2 exposure. The monosaccharides comprised about one-half of the soluble sugars extracted from the pericarp. Based on these observations, it appeared that sucrose hydrolysis might be prerequisite to sugar movement from the terminal phloem elements in the pericarp and into the endosperm. However, when 14C-fructosyl-sucrose was injected into the peduncle, there was little additional randomization of the 14C between the glucose and fructose moieties of sucrose extracted from the pericarp and endosperm compared to the rachis sucrose. If we assume that injected sucose was transported to the kernels via the phloem, then either sucrose moves out of the terminal phloem elements in the pericarp and into the endosperm unaltered, or if hydrolysis and resynthesis are a prerequisite to transport into the endosperm, the products of hydrolysis are not freely available for isomerization. Images PMID:16659185

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

    SciTech Connect

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

    1986-01-01

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

  10. Synthetic Studies toward the C14-C29 Fragment of Mirabalin.

    PubMed

    Cornil, Johan; Echeverria, Pierre-Georges; Reymond, Sébastien; Phansavath, Phannarath; Ratovelomanana-Vidal, Virginie; Guérinot, Amandine; Cossy, Janine

    2016-09-16

    A convergent synthesis of one isomer of the C14-C29 fragment of mirabalin is disclosed. The key steps include a Marshall allenylation, a Mukaiyama aldol reaction and a Crimmins aldolization, which allow the control of 10 out of 25 stereogenic centers present in the molecule. PMID:27602486

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

  12. Metabolism of U/sup 14/C palmitic and 1-/sup 14/C caproic acids by lettuce seeds during early germination

    SciTech Connect

    Salon, C.; Raymond, P.; Pradet, A.

    1986-04-01

    Germinating lettuce embryos (before radicule emergence) were fed with either U/sup 14/C palmitic acid or 1/sup 14/C caproic acid until a metabolic steady state was reached. The bulk of labelled caproate was evolved as respiratory CO/sub 2/ (52%) and incorporated into organic and amino acids (38%) and only a small part incorporated into lipids whereas most of labelled palmitic acid was found into lipids (92%) and only 8% evolved as CO/sub 2/ and incorporated into organic and amino acids. The label distribution at steady state in intermediates linked to the T.C.A. cycle was interpreted using a metabolic model. They found that the two fatty acids were degraded by ..beta..-oxidation and incorporated into the T.C.A. cycle as acetylCoA suggesting that ..beta..-oxidation is located in the mitochondria. The results also indicate that lipids contribute for at least 90% to the carbon supply to respiration.

  13. Using 14C to investigate Methane Production and DOC Reactivity in Northern Peatlands

    NASA Astrophysics Data System (ADS)

    Corbett, J.; Chanton, J.; Glaser, P.; Burdige, D.; Siegel, D.; Cooper, W.

    2008-12-01

    We found a consistent distribution pattern for radiocarbon in dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), and methane replicated across spatial and temporal scales in northern peatlands from Minnesota to Alaska. The 14C content of DOC is relatively modern throughout the peat column, to depths of 3 meters. In sedge-dominated peatlands, the 14C content of the products of respiration, CH4 and DIC are essentially the same, and are similar to that of DOC. In Sphagnum-woody plant dominated peatlands with few sedges, however, the respiration products are similar but intermediate between the 14C content of the solid-phase peat and the DOC. Preliminary data indicates qualitative differences in the pore-water DOC depending on the extent of sedge cover, consistent with the hypothesis that the DOC in sedge-dominated peatlands is more reactive than DOC in peatlands where Sphagnum or other vascular plants dominate. These data are supported by molecular-level analysis of DOC by ultrahigh resolution mass spectrometry which suggests dramatic changes with depth in the composition of DOC in the sedge-dominated peatland porewaters but not in porewaters where Sphagnum dominates. The higher reactivity of DOC from sedge- dominated peatlands may be a function of either different source materials or environmental factors that are related to the abundance of sedges in peatlands. To further investigate the reactivity of peat DOC in anaerobic methane producing environments, we are conducting size fractionation experiments for both the bog and fen samples. We will analyze resulting size fractions of DOC for radiocarbon. Previous research has shown that microorganisms tend to prefer HMW DOC to LMW DOC. Due to this, we believe that LMW DOC from both the bogs and the fens will result in radiocarbon values that are more depleted in 14C relative to HMW DOC. We hypothesize that the HMW DOC from the bogs will show depletion in 14C relative to HMW DOC in the fens. We further

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

    NASA Astrophysics Data System (ADS)

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

    2005-12-01

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

  15. Formation of Bound Residues during Microbial Degradation of [14C]Anthracene in Soil

    PubMed Central

    Kästner, M.; Streibich, S.; Beyrer, M.; Richnow, H. H.; Fritsche, W.

    1999-01-01

    Carbon partitioning and residue formation during microbial degradation of polycyclic aromatic hydrocarbons (PAH) in soil and soil-compost mixtures were examined by using [14C]anthracenes labeled at different positions. In native soil 43.8% of [9-14C]anthracene was mineralized by the autochthonous microflora and 45.4% was transformed into bound residues within 176 days. Addition of compost increased the metabolism (67.2% of the anthracene was mineralized) and decreased the residue formation (20.7% of the anthracene was transformed). Thus, the higher organic carbon content after compost was added did not increase the level of residue formation. [14C]anthracene labeled at position 1,2,3,4,4a,5a was metabolized more rapidly and resulted in formation of higher levels of residues (28.5%) by the soil-compost mixture than [14C]anthracene radiolabeled at position C-9 (20.7%). Two phases of residue formation were observed in the experiments. In the first phase the original compound was sequestered in the soil, as indicated by its limited extractability. In the second phase metabolites were incorporated into humic substances after microbial degradation of the PAH (biogenic residue formation). PAH metabolites undergo oxidative coupling to phenolic compounds to form nonhydrolyzable humic substance-like macromolecules. We found indications that monomeric educts are coupled by C-C- or either bonds. Hydrolyzable ester bonds or sorption of the parent compounds plays a minor role in residue formation. Moreover, experiments performed with 14CO2 revealed that residues may arise from CO2 in the soil in amounts typical for anthracene biodegradation. The extent of residue formation depends on the metabolic capacity of the soil microflora and the characteristics of the soil. The position of the 14C label is another important factor which controls mineralization and residue formation from metabolized compounds. PMID:10223966

  16. Characteristics of 14C and 13C of carbonate aerosols in dust storm events in China

    NASA Astrophysics Data System (ADS)

    Chen, Bing; Jie, Dongmei; Shi, Meinan; Gao, Pan; Shen, Zhenxing; Uchida, Masao; Zhou, Liping; Liu, Kexin; Hu, Ke; Kitagawa, Hiroyuki

    2015-10-01

    In contrast with its decrease in western China deserts, the dust storm event in eastern China, Korea, and Japan shows an increase in frequency. Although the drylands in northeastern China have been recognized as an important dust source, the relative contributions of dust transport from the drylands and deserts are inconclusive, thus the quantification of dust storm sources in downwind area remains a challenge. We measured the 14C and 13C contents in carbonates of dust samples from six sites in China, which were collected for the duration of dust storm events in drylands, deserts, and urban areas. The δ13C of the dryland dust samples considerably varied in a range of - 9.7 to - 5.0‰, which partly overlapped the desert dust carbonate δ13C ranges. The 14C content of the dryland dust carbonates showed a narrow range of 60.9 ± 4.0 (as an average and 1 SD of five samples) percent modern carbon (pMC), indicating the enrichment of modern carbonate. Dust samples in desert regions contained relatively aged carbonates with the depleting 14C showing of 28.8 ± 3.3 pMC. After the long-range transport of the western China desert dust plume, the carbonates collected at the southern China remained the depletion of 14C (33.5 ± 5.3 pMC) as in the desert regions. On the other hand, the samples of dust storm events at the urban areas of eastern China showed an enrichment of 14C contents (46.2 ± 5.0 pMC, n = 7), which might be explained by the stronger contribution of modern-carbonate-rich dryland dust.

  17. The Fate of Inhaled 14C-labelled PCB11 and its Metabolites In Vivo1

    PubMed Central

    Hu, Xin; Adamcakova-Dodd, Andrea; Thorne, Peter S.

    2014-01-01

    Background The production ban of polychlorinated biphenyl (PCB) technical mixtures has left the erroneous impression that PCBs exist only as legacy pollutants. Some lower-chlorinated PCBs are still being produced and contaminate both indoor and ambient air. Objectives To inform PCB risk assessment, we characterized lung uptake, distribution, metabolism and excretion of PCB11 as a signature compound for these airborne non-legacy PCBs. Methods After delivering [14C]PCB11 to the lungs of male rats, radioactivity in 34 major tissues and 5 digestive matter compartments was measured at 12, 25, 50, 100, 200 and 720 min postexposure, during which time the excreta and exhaled air were also collected. [14C]PCB11 and metabolites in liver, blood, digestive matter, urine and adipose tissues were extracted separately to establish the metabolic profile of the disposition. Results [14C]PCB11 was distributed rapidly to all tissues after 99.8% pulmonary uptake and quickly underwent extensive metabolism. The major tissue deposition of [14C]PCB11 and metabolites translocated from liver, blood and muscle to skin and adipose tissue 200 min postexposure, while over 50% of administered dose was discharged via urine and feces within 12 h. Elimination of the [14C]PCB11 and metabolites consisted of an initial fast phase (t½ = 9-33 min) and a slower clearance phase to low concentrations. Phase II metabolites dominated in liver, blood and excreta after 25 min postexposure. Conclusions This study shows that PCB11 is completely absorbed after inhalation exposure and is rapidly eliminated from most tissues. Phase II metabolites dominated with a slower elimination rate than the PCB11 or phase I metabolites and thus can best serve as urine biomarkers of exposure. PMID:24275706

  18. Formation of bound residues during microbial degradation of [{sup 14}C]anthracene in soil

    SciTech Connect

    Kaestner, M.; Streibich, S.; Beyrer, M.; Fritsche, W.; Richnow, H.H.

    1999-05-01

    Carbon partitioning and residue formation during microbial degradation of polycyclic aromatic hydrocarbons (PAH) in soil and soil-compost mixtures were examined by using [{sup 14}C]anthracenes labeled at different positions. In native soil 43.8% of [9-{sup 14}C]anthracene was mineralized by the autochthonous microflora and 45.4% was transformed into bound residues within 176 days. Addition of compost increased the metabolism and decreased the residue formation (20.7% of the anthracene was transformed). Thus, the higher organic carbon content after compost was added did not increase the level of residue formation. [{sup 14}C]anthracene labeled at position 1,2,3,4,4a,5a was metabolized more rapidly and resulted in formation of higher levels of residues (28.5%) by the soil-compost mixture than [{sup 14}C]anthracene radiolabeled at position C-9 (20.7%). Two phases of residue formation were observed in the experiments. In the first phase the original compound was sequestered in the soil, as indicated by its limited extractability. In the second phase metabolites were incorporated into humic substances after microbial degradation of the PAH (biogenic residue formation). PAH metabolites undergo oxidative coupling to phenolic compounds to form nonhydrolyzable humic substance-like macromolecules. The authors found indications that monomeric educts are coupled by C-C- or either bonds. Hydrolyzable ester bonds or sorption of the parent compounds plays a minor role in residue formation. Moreover, experiments performed with {sup 14}CO{sub 2} revealed that residues may arise from CO{sub 2} in the soil in amounts typical for anthracene biodegradation. The extent of residue formation depends on the metabolic capacity of the soil microflora and the characteristics of the soil. The position of the {sup 14}C label is another important factor which controls mineralization and residue formation from metabolized compounds.

  19. Pharmacokinetics and excretion of (14)C-omacetaxine in patients with advanced solid tumors.

    PubMed

    Nijenhuis, Cynthia M; Hellriegel, Edward; Beijnen, Jos H; Hershock, Diane; Huitema, Alwin D R; Lucas, Luc; Mergui-Roelvink, Marja; Munteanu, Mihaela; Rabinovich-Guilatt, Laura; Robertson, Philmore; Rosing, Hilde; Spiegelstein, Ofer; Schellens, Jan H M

    2016-10-01

    Background Omacetaxine mepesuccinate is indicated in adults with chronic myeloid leukemia resistant and/or intolerant to ≥ 2 tyrosine kinase inhibitor treatments. This phase I study assessed the disposition, elimination, and safety of (14)C-omacetaxine in patients with solid tumors. Methods The study comprised a 7-days pharmacokinetic assessment followed by a treatment period of ≤ six 28-days cycles. A single subcutaneous dose of 1.25 mg/m(2) (14)C-omacetaxine was administered to six patients. Blood, urine, and feces were collected through 168 h or until radioactivity excreted within 24 h was <1 % of the dose. Total radioactivity (TRA) was measured in all matrices and concentrations of omacetaxine, 4'-desmethylhomoharringtonine (4'-DMHHT), and cephalotaxine were measured in plasma and urine. For each treatment cycle, patients received 1.25 mg/m(2) omacetaxine twice daily for 7 days. Results Mean TRA recovered was approximately 81 % of the dose, with approximately half of the radioactivity recovered in feces and half in urine. Approximately 20 % of the dose was excreted unchanged in urine; cephalotaxine (0.4 % of dose) and 4' DMHHT (9 %) were also present. Plasma concentrations of TRA were higher than the sum of omacetaxine and known metabolites, suggesting the presence of other (14)C-omacetaxine-derived compounds. Fatigue and anemia were common, consistent with the known toxicity profile of omacetaxine. Conclusion Renal and hepatic processes contribute to the elimination of (14)C-omacetaxine-derived radioactivity in cancer patients. In addition to omacetaxine and its known metabolites, other (14)C-omacetaxine-derived materials appear to be present in plasma and urine. Omacetaxine was adequately tolerated, with no new safety signals. PMID:27221729

  20. Role of higher-multipole deformations in exotic {sup 14}C cluster radioactivity

    SciTech Connect

    Sawhney, Gudveen; Sharma, Manoj K.; Gupta, Raj K.

    2011-06-15

    We have studied nine cases of spontaneous emission of {sup 14}C clusters in the ground-state decays of the same number of parent nuclei from the trans-lead region, specifically from {sup 221}Fr to {sup 226}Th, using the preformed cluster model (PCM) of Gupta and collaborators, with choices of spherical, quadrupole deformation ({beta}{sub 2}) alone, and higher-multipole deformations ({beta}{sub 2}, {beta}{sub 3}, {beta}{sub 4}) with cold ''compact'' orientations {theta}{sup c} of decay products. The calculated {sup 14}C cluster decay half-life times are found to be in nice agreement with experimental data only for the case of higher-multipole deformations ({beta}{sub 2}-{beta}{sub 4}) and {theta}{sup c} orientations of cold elongated configurations. In other words, compared to our earlier study of clusters heavier than {sup 14}C, where the inclusion of {beta}{sub 2} alone, with ''optimum'' orientations, was found to be enough to give the best comparison with data, here for {sup 14}C cluster decay the inclusion of higher-multipole deformations (up to hexadecapole), together with {theta}{sup c} orientations, is found to be essential on the basis of the PCM. Interestingly, whereas both the penetration probability and assault frequency work simply as scaling factors, the preformation probability is strongly influenced by the order of multipole deformations and orientations of nuclei. The possible role of Q value and angular-momentum effects are also considered in reference to {sup 14}C cluster radioactivity.

  1. Substrate metabolism in isolated rat jejunal epithelium. Analysis using /sup 14/C-radioisotopes

    SciTech Connect

    Mallet, R.T.

    1986-01-01

    The jejunal epithelium absorbs nutrients from the intestinal lumen and is therefore the initial site for metabolism of these compounds. The purpose of this investigation is to analyze substrate metabolism in a preparation of jejunal epithelium relatively free of other tissues. Novel radioisotopic labelling techniques allow quantitation of substrate metabolism in the TCA cycle, Embden-Meyerhof (glycolytic) pathway, and hexose monophosphate shunt. For example, ratios of /sup 14/CO/sub 2/ production from pairs of /sup 14/C-pyruvate, and /sup 14/C-succinate radioisotopes (CO/sub 2/ ratios) indicate the probability of TCA cycle intermediate efflux to generate compounds other than CO/sub 2/. With (2,3-/sup 14/C)succinate as tracer, the ratio of /sup 14/C in carbon 4 + 5 versus carbon 2 + 3 of citrate, the citrate labelling ratio, equals the probability of TCA intermediate flux to the acetyl CoA-derived portion of citrate versus flux to the oxaloacetate-derived portion. The principal metabolic substrates for the jejunal epithelium are glucose and glutamine. CO/sub 2/ ratios indicate that glutamine uptake and metabolism is partially Na/sup +/-independent, and is saturable, with a half-maximal rate at physiological plasma glutamine concentrations. Glucose metabolism in the jejunal epithelium proceeds almost entirely via the Embden-Meyerhof pathway. Conversion of substrates to multi-carbon products in this tissue allows partial conservation of reduced carbon for further utilization in other tissues. In summary, metabolic modeling based on /sup 14/C labelling ratios is a potentially valuable technique for analysis of metabolic flux patterns in cell preparations.

  2. [Quantifying rice (Oryza sativa L.) photo-assimilated carbon input into soil organic carbon pools following continuous 14C labeling].

    PubMed

    Nie, San-An; Zhou, Ping; Ge, Ti-Da; Tong, Cheng-Li; Xiao, He-Ai; Wu, Jin-Shui; Zhang, Yang-Zhu

    2012-04-01

    The microcosm experiment was carried out to quantify the input and distribution of photo-assimilated C into soil C pools by using a 14C continuous labeling technique. Destructive samplings of rice (Oryza sativa) were conducted after labeling for 80 days. The allocation of 14C-labeled photosynthates in plants and soil C pools such as dissolved organic C (DOC) and microbial biomass C (MBC) in rice-planted soil were examined over the 14C labeling span. The amounts of rice shoot and root biomass C was ranged from 1.86 to 5.60 g x pot(-1), 0.46 to 0.78 g x pot(-1) in different tested paddy soils after labeling for 80 days, respectively. The amount of 14C in the soil organic C (14C-SOC) was also dependent on the soils, ranged from 114.3 to 348.2 mg x kg(-1), accounting for 5.09% to 6.62% of the rice biomass 14C, respectively. The amounts of 14C in the dissolved organic C (14C-DOC) and in the microbial biomass C(14C-MBC), as proportions of 14C-SOC, were 2.21%-3.54% and 9.72% -17.2%, respectively. The 14C-DOC, 14C-MBC, and 14C-SOC as proportions of total DOC, MBC, and SOC, respectively, were 6.72% -14.64%, 1.70% -7.67%, and 0.73% -1.99%, respectively. Moreover, the distribution and transformation of root-derived C had a greater influence on the dynamics of DOC and MBC than on the dynamics of SOC. Further studies are required to ascertain the functional significance of soil microorganisms (such as C-sequestering bacteria and photosynthetic bacteria) in the paddy system. PMID:22720588

  3. Changes in the level of ( sup 14 C)indole-3-acetic acid and ( sup 14 C)indoleacetylaspartic acid during root formation in mung bean cuttings. [Vigna radiata

    SciTech Connect

    Norcini, J.G.; Heuser, C.W. )

    1988-04-01

    Changes in the levels of ({sup 14}C)indole-3-acetic acid (IAA) and ({sup 14}C)indoleacetylaspartic acid (IAAsp) were examined during adventitious root formation in mung bean (Vigna radiata (L.) R. Wilcz. Berken) stem cuttings. IAAsp was identified by GC-MS as the primary conjugate in IAA-treated cuttings. During root formation in IAA-treated cuttings, the level of ({sup 14}C)IAAsp increased rapidly the first day and then declined; ({sup 14}C)IAA was rapidly metabolized and not detected after 12 hours.

  4. Depth-dependence of the production rate of in-situ 14-C in quartz

    NASA Astrophysics Data System (ADS)

    Lupker, Maarten; Hippe, Kristina; Kober, Florian; Wacker, Lukas; Braucher, Régis; Bourlès, Didier; Vidal Romani, Juan; Wieler, Rainer

    2013-04-01

    Terrestrial cosmogenic nuclides provide a means to document and quantify the rates of changes of the landscape at the Earth's surface and have therefore received an increasing attention over the past decade. The short lived in-situ produced 14-C has recently emerged as a complement to other longer lived cosmogenic nuclides such as 10-Be or 26-Al. The short half-life (5730 yr) of 14-C makes it suitable to investigate surface processes such as denudation rates or sediment residence times on ka scales. The wide application of in-situ 14-C for quantitative studies is however bound to the proper calibration of its production mechanisms and rates. As other cosmogenic nuclides, 14-C is produced at the Earth's surface by nuclear reactions with incoming neutrons and muons. The production rate of 14-C has been determined for quartz exposed at the surface where neutrons dominate the overall production [1]. At depth, however, the muon production pathway starts to dominate, because the mean attenuation length of muons is considerably longer than that of neutrons. So far, the muon derived in-situ 14-C production rate is solely based on theoretical and experimental work [2] that has not been tested on natural objects. We measured the 14-C concentration in quartz along the Leymon High core (42.065 N, 7.014 E - alt: 1277 m; Northwestern Spain) using the ETH 14-C extraction line [3] and the MICADAS gas source AMS [4]. This core has been drilled down to 20 m in a quartz dyke and has already been used to refine the depth-dependent production rate of 10-Be and 26-Al [5]. Our results on 14 samples of this core spanning a depth range from 1 to 1545 cm allow us to estimate the muogenic contribution to the overall 14-C concentrations measured along the core. This data set yields a local surface muon production rate of 3.9 (+3.1, -0.6) at.g-1.yr-1, which translates into a surface Sea Level High Latitude muon production rate of 2.2 (+1.8, -0.4) at.g-1.yr-1. This is ca. 17 % of the SLHL

  5. Pollen-based biome reconstructions for Latin America at 0, 6000 and 18 000 radiocarbon years

    USGS Publications Warehouse

    Marchant, R.; Harrison, S.P.; Hooghiemstra, H.; Markgraf, Vera; Van Boxel, J. H.; Ager, T.; Almeida, L.; Anderson, R.; Baied, C.; Behling, H.; Berrio, J.C.; Burbridge, R.; Bjorck, S.; Byrne, R.; Bush, M.B.; Cleef, A.M.; Duivenvoorden, J.F.; Flenley, J.R.; De Oliveira, P.; Van Geel, B.; Graf, K.J.; Gosling, W.D.; Harbele, S.; Van Der Hammen, T.; Hansen, B.C.S.; Horn, S.P.; Islebe, G.A.; Kuhry, P.; Ledru, M.

    2009-01-01

    The biomisation method is used to reconstruct Latin American vegetation at 6000±500 and 18 000±1000 radiocarbon years before present (14C yr BP) from pollen data. Tests using modern pollen data from 381 samples derived from 287 locations broadly reproduce potential natural vegetation. The strong temperature gradient associated with the Andes is recorded by a transition from high altitude cool grass/shrubland and cool mixed forest to mid-altitude cool temperate rain forest, to tropical dry, seasonal and rain forest at low altitudes. Reconstructed biomes from a number of sites do not match the potential vegetation due to local factors such as human impact, methodological artefacts and mechanisms of pollen representivity of the parent vegetation. At 6000±500 14C yr BP 255 samples are analysed from 127 sites. Differences between the modern and the 6000±500 14C yr BP reconstruction are comparatively small. Patterns of change relative to the modern reconstruction are mainly to biomes characteristic of drier climate in the north of the region with a slight more mesic shift in the south. Cool temperate rain forest remains dominant in western South America. In northwestern South America a number of sites record transitions from tropical seasonal forest to tropical dry forest and tropical rain forest to tropical seasonal forest. Sites in Central America also show a change in biome assignment to more mesic vegetation, indicative of greater plant available moisture, e.g. on the Yucat??n peninsula sites record warm evergreen forest, replacing tropical dry forest and warm mixed forest presently recorded. At 18 000±1000 14C yr BP 61 samples from 34 sites record vegetation that reflects a generally cool and dry environment. Cool grass/shrubland prevalent in southeast Brazil, Amazonian sites record tropical dry forest, warm temperate rain forest and tropical seasonal forest. Southernmost South America is dominated by cool grass/shrubland, a single site retains cool temperate

  6. Pollen-based biome reconstructions for Latin America at 0, 6000 and 18 000 radiocarbon years

    USGS Publications Warehouse

    Marchant, R.; Harrison, S.P.; Hooghiemstra, H.; Markgraf, Vera; Van Boxel, J. H.; Ager, T.; Almeida, L.; Anderson, R.; Baied, C.; Behling, H.; Berrio, J.C.; Burbridge, R.; Bjorck, S.; Byrne, R.; Bush, M.B.; Cleef, A.M.; Duivenvoorden, J.F.; Flenley, J.R.; De Oliveira, P.; Van Geel, B.; Graf, K.J.; Gosling, W.D.; Harbele, S.; Van Der Hammen, T.; Hansen, B.C.S.; Horn, S.P.; Islebe, G.A.; Kuhry, P.; Ledru, M.-P.; Mayle, F.E.; Leyden, B.W.; Lozano-Garcia, S.; Melief, A.B.M.; Moreno, P.; Moar, N.T.; Prieto, A.; Van Reenen, G. B.; Salgado-Labouriau, M. L.; Schasignbitz, F.; Schreve-Brinkman, E. J.; Wille, M.

    2009-01-01

    The biomisation method is used to reconstruct Latin American vegetation at 6000±500 and 18 000±1000 radiocarbon years before present (14C yr BP) from pollen data. Tests using modern pollen data from 381 samples derived from 287 locations broadly reproduce potential natural vegetation. The strong temperature gradient associated with the Andes is recorded by a transition from high altitude cool grass/shrubland and cool mixed forest to mid-altitude cool temperate rain forest, to tropical dry, seasonal and rain forest at low altitudes. Reconstructed biomes from a number of sites do not match the potential vegetation due to local factors such as human impact, methodological artefacts and mechanisms of pollen representivity of the parent vegetation.

    At 6000±500 14C yr BP 255 samples are analysed from 127 sites. Differences between the modern and the 6000±500 14C yr BP reconstruction are comparatively small. Patterns of change relative to the modern reconstruction are mainly to biomes characteristic of drier climate in the north of the region with a slight more mesic shift in the south. Cool temperate rain forest remains dominant in western South America. In northwestern South America a number of sites record transitions from tropical seasonal forest to tropical dry forest and tropical rain forest to tropical seasonal forest. Sites in Central America also show a change in biome assignment to more mesic vegetation, indicative of greater plant available moisture, e.g. on the Yucat??n peninsula sites record warm evergreen forest, replacing tropical dry forest and warm mixed forest presently recorded.

    At 18 000±1000 14C yr BP 61 samples from 34 sites record vegetation that reflects a generally cool and dry environment. Cool grass/shrubland prevalent in southeast Brazil, Amazonian sites record tropical dry forest, warm temperate rain forest and tropical seasonal forest. Southernmost South America is dominated by cool grass/shrubland, a single site

  7. Transformation of (sup14)C-Lignin-Labeled Cell Walls of Wheat by Syntrophococcus sucromutans, Eubacterium oxidoreducens, and Neocallimastix frontalis

    PubMed Central

    Bernard-Vailhe, M. A.; Besle, J. M.; Dore, J.

    1995-01-01

    Wheat cell walls, saponified or not, labeled with [U-(sup14)C]phenylalanine or [O-methyl-(sup14)C]sinapate were fermented by Neocallimastix frontalis or Syntrophococcus sucromutans plus Eubacterium oxidoreducens or a mixed culture. Phenolics were less solubilized but more transformed by bacteria than by the fungus, and mineralization was slight. S. sucromutans O-demethylated [O-methyl-(sup14)C]syringyl lignins, yielding labeled acetate. PMID:16534916

  8. Modeling of irradiated graphite (14)C transfer through engineered barriers of a generic geological repository in crystalline rocks.

    PubMed

    Poskas, Povilas; Grigaliuniene, Dalia; Narkuniene, Asta; Kilda, Raimondas; Justinavicius, Darius

    2016-11-01

    There are two RBMK-1500 type graphite moderated reactors at the Ignalina nuclear power plant in Lithuania, and they are under decommissioning now. The graphite cannot be disposed of in a near surface repository, because of large amounts of (14)C. Therefore, disposal of the graphite in a geological repository is a reasonable solution. This study presents evaluation of the (14)C transfer by the groundwater pathway into the geosphere from the irradiated graphite in a generic geological repository in crystalline rocks and demonstration of the role of the different components of the engineered barrier system by performing local sensitivity analysis. The speciation of the released (14)C into organic and inorganic compounds as well as the most recent information on (14)C source term was taken into account. Two alternatives were considered in the analysis: disposal of graphite in containers with encapsulant and without it. It was evaluated that the maximal fractional flux of inorganic (14)C into the geosphere can vary from 10(-11)y(-1) (for non-encapsulated graphite) to 10(-12)y(-1) (for encapsulated graphite) while of organic (14)C it was about 10(-3)y(-1) of its inventory. Such difference demonstrates that investigations on the (14)C inventory and chemical form in which it is released are especially important. The parameter with the highest influence on the maximal flux into the geosphere for inorganic (14)C transfer was the sorption coefficient in the backfill and for organic (14)C transfer - the backfill hydraulic conductivity.

  9. Utilization of [14C]phenylalanine derived from arylphorin or free amino acid in Manduca sexta pharate adults

    NASA Technical Reports Server (NTRS)

    Wu, M.; Tischler, M. E.

    1995-01-01

    The role of arylphorin as a storage protein was studied using 14C-arylphorin. 14C-arylphorin was produced optimally by incubating one-half fat body from Manduca sexta fifth instar larvae at 22 degrees C for 24 h, in 1 ml of medium containing amino acids at 25% of their physiological concentration with [U-14C]-phenylalanine (phe) provided initially without nonlabeled phenylalanine. Nonlabeled phe was provided after 1 h at 16% of its physiological concentration. The specific activity of 14C-arylphorin produced in vitro was 30 times greater than that generated in vivo. Injection of 14C-arylphorin into pharate adults was used to study the distribution of 14C-phe derived from this protein into 14CO2 and tissues for comparison with injection of free 14C-phe during the middle (days 6 to 12 pharate adult) and late (days 12 to 17 pharate adult) stages of adult development. Appearance of 14CO2 from 14C-arylphorin as compared to 14C-phenylalanine showed a slower time course during both the middle and late stages of development, in keeping with the time needed for degradation of the protein. In accord with faster phe turnover near the end of adult development, total 14CO2 production was greater and the retention of 14C in hemolymph and fat body was less compared to the middle stage of development regardless of whether 14C-arylphorin or 14C-phe was injected. In the middle stage of development, the appearance of 14C in the cuticle and head parts was greater, whereas incorporation into abdomen and thorax was less than during the late stage of development. Since the pattern of 14C distribution from 14C-arylphorin and 14C-phe was similar, one major function of arylphorin must be as a storage protein replenishing the supply of free amino acids used for synthesis of adult tissues. These results also suggest a limited contribution of M. sexta arylphorin to formation of the cuticle subsequent to day-6 pharate adult.

  10. Remarkable increase in 14C-acetate uptake in an epilepsy model rat brain induced by lithium-pilocarpine.

    PubMed

    Hosoi, Rie; Kitano, Daisuke; Momosaki, Sotaro; Kuse, Kenji; Gee, Antony; Inoue, Osamu

    2010-01-22

    The present study demonstrates changes in rat brain glial metabolism during the acute phase of epilepsy. Status epilepticus (SE) was induced using the lithium-pilocarpine model. Glial metabolism was measured with (14)C-acetate. Local cerebral blood flow and glucose metabolism were also measured using (14)C-N-isopropyl-p-iodoamphetamine (IMP) and (14)C-2-deoxyglucose (2DG), respectively. At the initiation of the seizure, (14)C-acetate uptake did not change significantly. However, a marked increase was observed 2 h after the pilocarpine injection in all brain regions studied. The increase of brain uptake was transient, and the maximum enhancement was seen at 2 h after the pilocarpine injection. The increase of (14)C-acetate uptake was almost to the same degree in all regions, whereas (14)C-IMP and (14)C-2DG uptakes showed a heterogeneous increase. In the case of (14)C-IMP, the highest increase was observed in the thalamus (280%), and a moderate increase (120 to 150%) was seen in the orbital cortex, cingulate cortex and pyriform cortex. (14)C-2DG uptake increased by 130 to 240% in most regions of the brain, however, an increase of only 40 and 20% was observed in the cerebellum and pons-medulla, respectively. These results demonstrated that glial energy metabolism was markedly enhanced during a prolonged seizure. To our knowledge, this study is the first observation showing large and widespread glial metabolic increases in the rat brain during status epilepticus.

  11. The metabolism of [14C]beta-carotene and the presence of other carotenoids in rats and monkeys.

    PubMed

    Krinsky, N I; Mathews-Roth, M M; Welankiwar, S; Sehgal, P K; Lausen, N C; Russett, M

    1990-01-01

    The metabolism of beta-carotene has been studied in both rats and Rhesus monkeys, following the oral administration of [14C]beta-carotene in olive oil supplemented with 1 mg/mL alpha-tocopherol. In the rats, peak serum accumulation of [14C]retinol occurred 4 h after a single oral dose, but we were not able to detect [14C]beta-carotene in rat sera at any time up to 72 h after dosing. Small amounts of [14C]beta-carotene were found in the livers, although 88-94% of the recovered radioactivity was localized in the retinol fraction after saponification. Although radioactivity was also found in fractions other than beta-carotene and retinol, the amounts were too small to allow characterization. In the monkeys, peak accumulation of [14C]retinol in serum occurred between 8 and 24 h after supplementation. Some [14C]beta-carotene was also present. Most of the absorbed radioactivity was stored in the liver as [14C]retinol, although 2-8% was present as [14C]beta-carotene. Other organs also contained [14C]beta-carotene, confirming the ability of the monkey to absorb intact beta-carotene. In addition, monkey livers and other organs were found to contain lutein, zeaxanthin, alpha-cryptoxanthin, beta-cryptoxanthin and beta-carotene, presumably arising from dietary sources. PMID:2303914

  12. The LLNL Accelerator Mass Spectrometry System for Biochemical 14C-Measurements

    SciTech Connect

    Ognibene, T J; Bench, G; Brown, T A; Vogel, J S

    2002-10-31

    We report on recent improvements made to our 1 MV accelerator mass spectrometry system that is dedicated to {sup 14}C quantification of biochemical samples. Increased vacuum pumping capacity near the high voltage terminal has resulted in a 2-fold reduction of system backgrounds to 0.04 amol {sup 14}C/mg carbon. Carbon ion transmission through the accelerator has also improved a few percent. We have also developed tritium measurement capability on this spectrometer. The {sup 3}H/{sup 1}H isotopic ratio of a milligram-sized processed tap water sample has been measured at 4 {+-} 1 x 10{sup -16} (430 {+-} 110 {micro}Bq/mg H). Measurement throughput for a typical biochemical {sup 3}H sample is estimated to be {approx}10 minutes/sample.

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

    SciTech Connect

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

    1990-05-01

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

  14. 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.

  15. 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.

  16. {sup 14}C-AMS quantification of biomolecular interactions using microbore and plate separations

    SciTech Connect

    Creek, M.R.; Frantz, C.E.; Fultz, E.; Haack, K.; Redwine, K.; Shen, N.; Turteltaub, K.W.; Vogel, J.S.

    1993-10-20

    AMS sensitivity arises from the direct counting of radioisotopes without interference from molecular isobars. No chemical or physical information other than a bulk isotope ratio is available from the usual AMS instrument. Chemical or biological significance of the isotope ratio depends on the definition of the sample prior to conversion to material used in the ion source. The authors use AMS to quantify biochemical interactions between labeled xenobiotics and their potential targets of toxicity. These potential target molecules are separated and defined by various types of plate and microbore separations, including thin layer chromatography (TLC), high performance liquid chromatography (HPLC) and gel electrophoresis (GE) in quantifying the binding of {sup 14}C-labeled compounds to specific DNA and protein fragments. They discuss their methods of using these microbore and plate separations of biomolecules while controlling contamination from {sup 14}C in laboratory equipment and give examples.

  17. Astrophysical S-factor of the radiative proton capture on 14C at low energies

    NASA Astrophysics Data System (ADS)

    Dubovichenko, Sergey; Burtebaev, Nasurlla; Dzhazairov-Kakhramanov, Albert; Alimov, Dilshod

    2014-07-01

    The phase shift analysis for position location of the 2S1/2 resonance at 1.5 MeV was carried out on the basis of the known experimental measurements of the excitation functions of the p14C elastic scattering at four angles from 90° to 165° and more than 100 energy values in the range from 600-800 keV to 2200-2400 keV. Also, the possibility to describe the available experimental data on the astrophysical S-factor for the proton capture reaction on 14C to the ground state (GS) of 15N at astrophysical energies was considered in the frame of modified potential cluster model (MPCM).

  18. Detection of an azido-(/sup 14/C)-atrazine labeled protein transferred to nitrocellulose paper

    SciTech Connect

    Ivey, S.; Metz, J.G.; Berg, S.P.

    1986-04-01

    An electrophoretically similar protein in spinach and maize can be covalently labeled with azido-(/sup 14/C)-atrazine and separated by 10-18% gradient LDS-PAGE. The protein profile can be transferred to nitrocellulose paper (ncp) by western blotting. The ncp containing the protein profile is sliced into 2 mm slices and counted with liquid scintillation. The labeled protein migrates as a diffuse band with a Mr of 34 kD. This band migrates at a higher Mr (40 kD) under different gel conditions. The ncp dissolves in the organic scintillation cocktail thus providing a more sensitive and quantitative detection of the /sup 14/C. This technique allows the simultaneous immunological and radiochemical identification of many electrophoretically separable proteins.

  19. ( sup 14 C)-Sucrose uptake by guard cell protoplasts of pisum sativum, argenteum mutant

    SciTech Connect

    Rohrig, K.; Raschke, K. )

    1991-05-01

    Guard cells rely on import for their supply with reduced carbon. The authors tested by silicone oil centrifugation the ability of guard cell protoplasts to accumulated ({sup 14}C)-sucrose. Uptake rates were corrected after measurement of {sup 14}C-sorbitol and {sup 3}H{sub 2}O spaces. Sucrose uptake followed biphasic kinetics, with a high-affinity component below 1 mM external sucrose (apparent K{sub m} 0.8 mM at 25C) and a low-affinity nonsaturable component above. Uptake depended on pH (optimum at pH 5.0). Variations in the concentrations of external KCl, CCCP, and valinomycin indicated that about one-half of the sucrose uptake rate could be related to an electrochemical gradient across the plasmalemma. Total uptake rates measured at 5 mM external sucrose seem to be sufficient to replenish emptied plastids with starch within a few hours.

  20. Temperature and Oxygen Effects on 14C-Photosynthate Unloading and Accumulation in Developing Soybean Seeds

    PubMed Central

    Thorne, John H.

    1982-01-01

    The environmental sensitivity of the processes associated with the import of photosynthate by developing soybean seeds was investigated within intact fruit and with excised, immature embryos. Intact pods of field-grown (Glycine max [L.] Merr.) Amsoy 71 soybeans were subjected to localized regimes of 0, 21, or 100% O2 and 15, 25, or 35°C during pulsechase translocation experiments and, 2.5 hours later, the uptake and distribution of 14C-photosynthate among dissected fruit tissues determined. In other experiments, excised embryos were incubated in [14C]sucrose solutions under various experimental conditions to separate the effects of these treatments on accumulation by the embryos from those which may operate on phloem unloading in the maternal seedcoat. Import of 14C-photosynthate by intact soybean fruit was both temperature- and O2-dependent. This dependency was shown to occur only within the seeds; import by the pod walls was essentially insensitive to fruit temperature or O2 treatments. The embryos of anaerobic fruit were completely unlabeled, regardless of fruit temperature. But under anaerobic in vitro incubation conditions, uptake of [14C]sucrose in excised embryos was only 30% less than that in aerobic in vitro conditions. The data suggest that, within intact fruit, anoxia prevented sucrose efflux from the seed coat phloem and any subsequent uptake by the embryo. The demonstrated energy dependence of phloem unloading may reflect requirements for membrane integrity or energy metabolism in the companion cell-sieve element complex, consistent with a facilitated unloading process. Collectively, these data characterize the environmental sensitivity of photosynthate import in developing soybean fruit. They imply that environmental regulation of import may occur at both the embryo level and at the phloem terminals within the seed coat. PMID:16662182

  1. Goldenrod ball gall effects on Solidago altissima: /sup 14/C translocation and growth. [Eurosta solidaginis

    SciTech Connect

    McCrea, K.D.; Abrahamson, W.G.; Weis, A.E.

    1985-12-01

    Individual leaves of S. altissima were labeled with carbon-14 introduced as CO/sub 2/. The /sup 14/C was introduced into ramets that had ball galls caused by the fly Eurosta solidaginis and into ungalled control ramets; gall size (large vs. small) and point of introduction of the label (above vs. below the gall) were experimental factors. After 5 d the ramets were harvested and their component organs were assayed for /sup 14/C using liquid scintillation. In addition, a field cohort of 359 galled and ungalled ramets was followed during the period of gall growth to determine the effect of the gall on stem height growth. Gall size and labeling position had no effect on the percent of /sup 14/C translocated out of the labeled leaf but did affect the distribution of translocated /sup 14/C. Translocation to underground organs was reduced when the label was introduced above the gall, the reduction being related to gall size. Large galls reduced translocation to the apical bud when the label was introduced below the gall, but small galls did not. Translocation to underground organs was not affected by the gall when the label was introduced below the gall and translocation to the apical bud was not affected by the gall when the label was introduced above the gall; these results indicate that the goldenrod ball gall is a nonmobilizing gall. The presence of a gall did not significantly affect final stem height but did slow the growth of ramets during the period of most rapid gall growth.

  2. Product inhibition of cellulases studied with 14C-labeled cellulose substrates

    PubMed Central

    2013-01-01

    Background As a green alternative for the production of transportation fuels, the enzymatic hydrolysis of lignocellulose and subsequent fermentation to ethanol are being intensively researched. To be economically feasible, the hydrolysis of lignocellulose must be conducted at a high concentration of solids, which results in high concentrations of hydrolysis end-products, cellobiose and glucose, making the relief of product inhibition of cellulases a major challenge in the process. However, little quantitative information on the product inhibition of individual cellulases acting on cellulose substrates is available because it is experimentally difficult to assess the hydrolysis of the heterogeneous polymeric substrate in the high background of added products. Results The cellobiose and glucose inhibition of thermostable cellulases from Acremonium thermophilum, Thermoascus aurantiacus, and Chaetomium thermophilum acting on uniformly 14C-labeled bacterial cellulose and its derivatives, 14C-bacterial microcrystalline cellulose and 14C-amorphous cellulose, was studied. Cellulases from Trichoderma reesei were used for comparison. The enzymes most sensitive to cellobiose inhibition were glycoside hydrolase (GH) family 7 cellobiohydrolases (CBHs), followed by family 6 CBHs and endoglucanases (EGs). The strength of glucose inhibition followed the same order. The product inhibition of all enzymes was relieved at higher temperatures. The inhibition strength measured for GH7 CBHs with low molecular-weight model substrates did not correlate with that measured with 14C-cellulose substrates. Conclusions GH7 CBHs are the primary targets for product inhibition of the synergistic hydrolysis of cellulose. The inhibition must be studied on cellulose substrates instead of on low molecular-weight model substrates when selecting enzymes for lignocellulose hydrolysis. The advantages of using higher temperatures are an increase in the catalytic efficiency of enzymes and the relief of

  3. Release of ( sup 14 C)5-hydroxytryptamine from human platelets by red wine

    SciTech Connect

    Jarman, J.; Glover, V.; Sandler, M. )

    1991-01-01

    Red wine, at a final dilution of 1/50, caused released of ({sup 14}C)5-hydroxytryptamine (5-HT) from preloaded platelets, an effect which was not observed with any white wines or beers tested. Since 5-HT, is probably released from body stores during migraine attacks and red wine is known to provoke migraine episodes in susceptible individuals, release of 5-HT, possibly from central stores, could represent a plausible mechanism for its mode of action.

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

    SciTech Connect

    Gordon, R.; Maclachlan, G. )

    1989-09-01

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

  5. Kernel abortion in maize. II. Distribution of /sup 14/C among kernel carboydrates

    SciTech Connect

    Hanft, J.M.; Jones, R.J.

    1986-06-01

    This study was designed to compare the uptake and distribution of /sup 14/C among fructose, glucose, sucrose, and starch in the cob, pedicel, and endosperm tissues of maize (Zea mays L.) kernels induced to abort by high temperature with those that develop normally. Kernels cultured in vitro at 309 and 35/sup 0/C were transferred to (/sup 14/C)sucrose media 10 days after pollination. Kernels cultured at 35/sup 0/C aborted prior to the onset of linear dry matter accumulation. Significant uptake into the cob, pedicel, and endosperm of radioactivity associated with the soluble and starch fractions of the tissues was detected after 24 hours in culture on atlageled media. After 8 days in culture on (/sup 14/C)sucrose media, 48 and 40% of the radioactivity associated with the cob carbohydrates was found in the reducing sugars at 30 and 35/sup 0/C, respectively. Of the total carbohydrates, a higher percentage of label was associated with sucrose and lower percentage with fructose and glucose in pedicel tissue of kernels cultured at 35/sup 0/C compared to kernels cultured at 30/sup 0/C. These results indicate that sucrose was not cleaved to fructose and glucose as rapidly during the unloading process in the pedicel of kernels induced to abort by high temperature. Kernels cultured at 35/sup 0/C had a much lower proportion of label associated with endosperm starch (29%) than did kernels cultured at 30/sup 0/C (89%). Kernels cultured at 35/sup 0/C had a correspondingly higher proportion of /sup 14/C in endosperm fructose, glucose, and sucrose.

  6. In vitro uptake of /sup 14/C-praziquantel by cestodes, trematodes, and a nematode

    SciTech Connect

    Andrews, P.; Thomas, H.; Weber, H.

    1980-12-01

    /sup 14/C-praziquantel was rapidly taken up by Schistosoma mansoni, Fasciola hepatica, Hymenolepis nana, and isolated strobilocerci of Taenia taeniaeformis. Schistosoma mansoni lost praziquantel rapidly to drug-free medium. Chromatography of extracts prepared after incubation of S. mansoni and H. nana yielded no indication that praziquantel was metabolized. Autoradiography revealed a uniform distribution of praziquantel throughout the tissues of S. mansoni and H. nana. Uptake was considerably slower in the nematode Heterakis spumosa and apparently via the oral route.

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

    PubMed Central

    Gordon, Ruth; Maclachlan, Gordon

    1989-01-01

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

  8. Theoretical estimates of the rates of radioactive decay of radium isotopes by /sup 14/C emission

    SciTech Connect

    Shi, Y.; Swiatecki, W.J.

    1985-01-28

    The measured branching ratios for the decays of /sup 222,223,224/Ra by alpha or /sup 14/C emissions can be accounted for within a factor of 10 in terms of the ratios of Gamow penetrabilities through potential-energy barriers consisting of a Coulomb repulsion, the nuclear proximity attraction, and an interpolation between the configuration of tangent fragments and the configuration of the parent nucleus.

  9. Biosynthesis of riboflavin. Enzymatic formation of the xylene moiety from [14C]ribulose 5-phosphate.

    PubMed

    Nielsen, P; Neuberger, G; Floss, H G; Bacher, A

    1984-02-14

    We have studied the enzymatic formation of the xylene ring of riboflavin using cell extracts from the flavinogenic yeast Candida guilliermondii. 5-Amino-6-ribitylamino-2,4(1H,3H)-pyrimidinedione or its 5'-phosphate could serve as substrates. In addition, a pentose phosphate or pentulose phosphate was required. Experiments with [14C]ribulose 5-phosphate gave evidence for the incorporation of the ribulose carbon atoms except C-4 into the xylene ring of the vitamin. PMID:6546684

  10. A New {sup 14}C-AMS Facility at UFF- Niteroi, Brazil

    SciTech Connect

    Gomes, P. R. S.; Macario, K. D.; Anjos, R. M.; Linares, R.; Carvalho, C.; Queiroz, E.

    2010-08-04

    We report a new Accelerator Mass Spectrometry facility at the Physics Institute of Fluminense Federal University in Brazil, the Nuclear Chronology Laboratory - LACRON. The sample preparation laboratory is ready to perform chemical treatment through graphitization and the acquisition of a Single Stage Accelerator Mass Spectrometry System is in progress. LACRON will be the first independent laboratory to perform the {sup 14}C-AMS technique not only in Brazil but in Latin America.

  11. Polymorphism of 14C vitamin D3 binding protein in cattle and water buffalo serum.

    PubMed

    Masina, P; Ramunno, L; Iannelli, D

    1978-01-01

    Cattle and water buffalo sera labelled with vitamin D3[14C] (300 and 480 individual samples respectively) were subjected to starch gel electrophoresis followed by autoradiography in an attempt to identify a possible polymorphism of the proteins capable of binding this vitamin. Three phenotypes controlled by two codominant autosomal alleles were identified in cattle while in water buffalo six phenotypes controlled by three codominant autosomal alleles were observed.

  12. Towards a global understanding of vertical soil carbon dynamics: meta-analysis of soil 14C data

    NASA Astrophysics Data System (ADS)

    hatte, C.; Balesdent, J.; Guiot, J.

    2012-12-01

    Soil represents the largest terrestrial storage mechanism for atmospheric carbon from photosynthesis, with estimates ranging from 1600 Pg C within the top 1 meter to 2350 Pg C for the top 3 meters. These values are at least 2.5 times greater than atmospheric C pools. Small changes in soil organic carbon storage could result in feedback to atmospheric CO2 and the sensitivity of soil organic matter to changes in temperature, and precipitation remains a critical area of research with respect to the global carbon cycle. As an intermediate storage mechanism for organic material through time, the vertical profile of carbon generally shows an age continuum with depth. Radiocarbon provides critical information for understanding carbon exchanges between soils and atmosphere, and within soil layers. Natural and "bomb" radiocarbon has been used to demonstrate the importance and nature of the soil carbon response to climatic and human impacts on decadal to millennial timescales. Radiocarbon signatures of bulk, or chemically or physically fractionated soil, or even of specific organic compounds, offer one of the only ways to infer terrestrial carbon turnover times or test ecosystem carbon models. We compiled data from the literature on radiocarbon distribution on soil profiles and characterized each study according to the following categories: soil type, analyzed organic fraction, location (latitude, longitude, elevation), climate (temperature, precipitation), land use and sampling year. Based on the compiled data, soil carbon 14C profiles were reconstructed for each of the 226 sites. We report here partial results obtained by statistical analyses of portion of this database, i.e. bulk and bulk-like organic matter and sampling year posterior to 1980. We highlight here 14C vertical pattern in relationship with external parameters (climate, location and land use).

  13. Influence of alternating soil drying and wetting on the desorption and distribution of aged 14C-labeled pesticide residues in soil organic fractions

    NASA Astrophysics Data System (ADS)

    Jablonowski, N. D.; Mucha, M.; Thiele, B.; Hofmann, D.; Burauel, P.

    2012-04-01

    A laboratory experiment was conducted to evaluate the effect of alternating soil drying and wetting on the release of aged 14C-labeled pesticide residues and their distribution in soil organic fractions (humic acids, fulvic acids, and humin substances). The used soils (gleyic cambisol; Corg 1.2%, pH 7.2) were obtained from the upper soil layer of two individual outdoor lysimeter studies containing either environmentally long-term aged 14C residues of the herbicide ethidimuron (ETD; 0-10 cm depth; time of aging: 9 years) or methabenzthiazuron (MBT; 0-30 cm depth; time of aging: 17 years). Triplicate soil samples (10 g dry soil equivalents) were (A=dry/wet) previously dried (45° C) or (B=wet/wet) directly mixed with pure water (1+2, w:w), shaken (150 rpm, 1 h), and centrifuged (~2000 g). The resulting supernatant was removed, filtered (0.45 μm) and subjected to 14C activity analysis via liquid scintillation counter (LSC), dissolved organic carbon (DOC) analysis, and LC-MS-MS analysis. This extraction procedure was repeated 15 individual times, for both setups (A) and (B). To determine the distribution of the aged 14C labelled pesticide residues in the soil organic matter fractions, the soil samples were subject to humic and fulvic acids fractionations at cycles 0, 4, 10, and 15. The residual pesticide 14C activity associated with the humic, fulvic, and humin substances (organic fraction remaining in the soil) fractions was determined via LSC. The water-extracted residual 14C activity was significantly higher in the extracts of the dry/wet, compared to the wet/wet soil samples for both pesticides. The total extracted 14C activity in the dry/wet soil extracts accounted for 51.0% (ETD) and 15.4% (MBT) in contrast to 19.0% (ETD) and 4.7% (MBT) in the wet/wet extracts after 15 water extractions. LC-MS-MS analysis revealed the parent compound ETD 27.9 μg kg-1 soil (dry/wet) and 10.7 μg kg-1 soil (wet/wet), accounting for 3.45 and 1.35% of total parent compound

  14. Influence of alternating soil drying and wetting on the desorption and distribution of aged 14C-labeled pesticide residues in soil organic fractions

    NASA Astrophysics Data System (ADS)

    Jablonowski, N. D.; Mucha, M.; Thiele, B.; Hofmann, D.; Burauel, P.

    2012-04-01

    A laboratory experiment was conducted to evaluate the effect of alternating soil drying and wetting on the release of aged 14C-labeled pesticide residues and their distribution in soil organic fractions (humic acids, fulvic acids, and humin substances). The used soils (gleyic cambisol; Corg 1.2%, pH 7.2) were obtained from the upper soil layer of two individual outdoor lysimeter studies containing either environmentally long-term aged 14C residues of the herbicide ethidimuron (ETD; 0-10 cm depth; time of aging: 9 years) or methabenzthiazuron (MBT; 0-30 cm depth; time of aging: 17 years). Triplicate soil samples (10 g dry soil equivalents) were (A=dry/wet) previously dried (45° C) or (B=wet/wet) directly mixed with pure water (1+2, w:w), shaken (150 rpm, 1 h), and centrifuged (~2000 g). The resulting supernatant was removed, filtered (0.45 μm) and subjected to 14C activity analysis via liquid scintillation counter (LSC), dissolved organic carbon (DOC) analysis, and LC-MS-MS analysis. This extraction procedure was repeated 15 individual times, for both setups (A) and (B). To determine the distribution of the aged 14C labelled pesticide residues in the soil organic matter fractions, the soil samples were subject to humic and fulvic acids fractionations at cycles 0, 4, 10, and 15. The residual pesticide 14C activity associated with the humic, fulvic, and humin substances (organic fraction remaining in the soil) fractions was determined via LSC. The water-extracted residual 14C activity was significantly higher in the extracts of the dry/wet, compared to the wet/wet soil samples for both pesticides. The total extracted 14C activity in the dry/wet soil extracts accounted for 51.0% (ETD) and 15.4% (MBT) in contrast to 19.0% (ETD) and 4.7% (MBT) in the wet/wet extracts after 15 water extractions. LC-MS-MS analysis revealed the parent compound ETD 27.9 μg kg-1 soil (dry/wet) and 10.7 μg kg-1 soil (wet/wet), accounting for 3.45 and 1.35% of total parent compound

  15. In vitro covalent binding of 3-(/sup 14/C)methylindole metabolites in goat tissues

    SciTech Connect

    Bray, T.M.; Carlson, J.R.; Nocerini, M.R.

    1984-05-01

    Covalent binding of 3-(/sup 14/C)methylindole (3(/sup 14/C)MI) in crude microsomal preparations of goat lung, liver, and kidney was measured to determine if a reactive intermediate was formed during the in vitro metabolism of 3-methylindole (3MI). The bound radioactivity was highest in lung compared to liver and kidney. The amount of bound radioactivity per nanomole of cytochrome P-450 was approximately 10 times higher in the lung compared to the liver. No detectable bound radioactivity was found when 3-(/sup 3/H)methyloxindole was used as the substrate. Cofactor requirements and the effects of inhibitors indicate that a mixed function oxidase (MFO) system is involved in formation of a reactive intermediate. Inhibitors and conjugating agents that are known to reduce the severity of 3MI-induced lung injury such as piperonyl butoxide (MFO inhibitor) and glutathione (conjugating agent) significantly decreased the in vitro binding of 3(/sup 14/C)MI. The results indicate that a reactive intermediate is produced during the metabolism of 3MI by the MFO system. The organ specificity in binding suggests that covalent binding by lung microsomes may be related to the mechanism of 3MI-induced lung injury.

  16. An approach toward automatic graphitization of CO2 samples for AMS 14C measurements

    NASA Astrophysics Data System (ADS)

    Nagasawa, Shigenobu; Kitagawa, Hiroyuki; Nakanishi, Toshimichi; Tanabe, Susumu; Hong, Wan

    2013-01-01

    To improve the throughput of sample preparation for AMS 14C measurements, we made improvements to a manually operated system for CO2 reduction at the Graduate School of Environmental Studies, Nagoya University. Most of the processes of the CO2 reduction procedure were automated, and a CO2 sample containing 0.3-1 mg carbon was credibly reduced to graphite within a few hours by hydrogen gas with catalytic iron powder in a 7.4 ml reactor consisting of a quartz reduction tube, a pressure transducer gauge and a cold finger trap equipped with a temperature-controllable trap device for trapping CO2 and H2O. The improved system has the potential to easily carry out graphitization of more than 100 CO2 samples per week. The 14C values of graphite produced from 14C-free CO2 (>0.3 mg C) were 0.0028 ± 0.0010 fraction modern carbon (FMC) on average (n = 8, 1std), which are almost the same as the black level of 1-MV HVEE Tandetron installed at the Korea Institute of Geoscience and Mineral Resources (KIGAM).

  17. Incorporation of l-[14C]leucine into egg proteins by liver slices from cod

    PubMed Central

    Plack, P. A.; Fraser, N. W.

    1971-01-01

    1. Liver slices from cod (Gadus morhua L.) were incubated with l-[14C]leucine and the incorporation of label into total protein, precipitated with trichloroacetic acid, and into egg proteins, precipitated with an antibody after addition of carrier egg proteins, was measured. 2. Liver slices from immature male or female cod, and from male fish with developing testes, did not incorporate significant amounts of l-[14C]leucine into egg proteins, whereas with slices from female cod with developing ovaries the rate of incorporation into egg proteins was 8% of the rate of incorporation into total protein. 3. Liver slices from immature male or female fish that had received an intramuscular injection of oestradiol benzoate (1mg/kg) 5–8 days previously incorporated l-[14C]leucine into egg proteins at about 26% of the rate of incorporation into total protein. 4. Incorporation into total protein and into egg proteins was inhibited by puromycin, and 1.2 and 0.13μg of puromycin/mg of tissue protein, respectively, gave 50% inhibition. PMID:16742749

  18. Role of biotransformation, sorption and mineralization of (14)C-labelled sulfamethoxazole under different redox conditions.

    PubMed

    Alvarino, T; Nastold, P; Suarez, S; Omil, F; Corvini, P F X; Bouju, H

    2016-01-15

    (14)C-sulfamethoxazole biotransformation, sorption and mineralization was studied with heterotrophic and autotrophic biomass under aerobic and anoxic conditions, as well as with anaerobic biomass. The (14)C-radiolabelled residues distribution in the solid, liquid and gas phases was closely monitored along a total incubation time of 190 h. Biotransformation was the main removal mechanism, mineralization and sorption remaining below 5% in all the cases, although the presence of a carbon source exerted a positive effect on the mineralization rate by the aerobic heterotrophic bacteria. In fact, an influence of the type of primary substrate and the redox potential was observed in all cases on the biotransformation and mineralization rates, since an enhancement of the removal rate was observed when an external carbon source was used as a primary substrate under aerobic conditions, while a negligible effect was observed under nitrifying conditions. In the liquid phases collected from all assays, up to three additional peaks corresponding to (14)C-radiolabelled residues were detected. The highest concentration was observed under anaerobic conditions, where two radioactive metabolites were detected representing each around 15% of the total applied radioactivity after 180 h incubation. One of the metabolites detected under anoxic and anaerobic conditions, is probably resulting from ring cleavage of the isoxazole ring. PMID:26546766

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

    PubMed

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

    1996-03-01

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

  20. The fate of dermally applied [14C]d-limonene in rats and humans.

    PubMed

    Api, Anne Marie; Ritacco, Gretchen; Hawkins, David R

    2013-01-01

    The fate of dermally applied [(14)C]d-limonene was evaluated in humans and Long-Evans rats. In rats, 5 mg/kg body weight of [(14)C]d-limonene applied dermally to the shaved back under occlusion, resulted in the absorption of approximately 12% of the dose. The absorbed d-limonene was completely metabolized and excreted rapidly, primarily from the urine (80%) with a small fraction (20%) excreted in the feces. There was no long-term retention of the test material in body tissues. In humans, following dermal application of 12 mg of [(14)C]d-limonene in ethanol (1 mL) to the back under nonocclusive conditions (for 1 h after application to allow the material to dry, thereafter under occlusion), only 0.16% of the dose was absorbed and the radioactivity was recovered from the urine. Radioactivity in human feces was below the limit of detection. These results indicate that under conditions of simulated use of fragrances and cosmetics, d-limonene has a low potential for dermal absorption and tissue accumulation, and the d-limonene that is absorbed is rapidly excreted in the urine. Based upon these findings and the knowledge that d-limonene possesses a low-systemic toxicity profile, it is reasonable to conclude that dermal exposure to d-limonene from fragrance and cosmetic applications is highly unlikely to result in any clinically significant human toxicity.

  1. A compact 14C Isotope Ratio Mass Spectrometer for biomedical applications

    NASA Astrophysics Data System (ADS)

    Mous, D. J. W.; Purser, K. H.; Fokker, W.; van den Broek, R.; Koopmans, R. B.

    1997-03-01

    During the last two decades the unparalleled sensitivity of accelerator mass spectrometry (AMS) has allowed major developments in many areas of geoscience and archeology. It is projected that in the near future a similar potential for AMS expansion is likely in the field of biomedical research leading, ultimately, to clinical applications. As an example of the growth of this new field, at the Lawrence Livermore National Laboratory Center for AMS the number of biomedical 14C measurements already represents a significant fraction of the total for all 14C. Widespread adoption of AMS in the biomedical field does require, however, the availability of instruments that are small in comparison with existing AMS systems and that will operate in a manner that is simple and user-friendly. To meet this demand, High Voltage Engineering Europa (HVEE) has developed a miniature, high-efficiency AMS instrument designed to provide for biomedical samples {14C}/{12C} ratios with an accuracy better than 2% and with backgrounds limitations below 0.1 Modern. The current status of this program will be presented in the present paper.

  2. 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.

  3. The impact of biochar on the bioaccessibility of (14)C-phenanthrene in aged soil.

    PubMed

    Ogbonnaya, O U; Adebisi, O O; Semple, K T

    2014-11-01

    Biochar is a carbon rich product from the incomplete combustion of biomass and it has been shown to reduce bioavailability of organic contaminants through adsorption. This study investigated the influence of 0%, 1%, 5% and 10% of two different particle sized wood biochars (≤2 mm and 3-7 mm) on the bioaccessibility of (14)C-phenanthrene (10 mg kg(-1)) in aged soil. The extent of (14)C-phenanthrene mineralisation by phenanthrene-degrading Pseudomonas sp. inoculum was monitored over a 14 day period in respirometric assays and compared to hydroxypropyl-β-cyclodextrin (HPCD) aqueous extraction. Notably, biochar amendments showed significant reduction in extents of mineralisation and HPCD extraction. Linear correlations between HPCD extractability and the total amount mineralised revealed good correlations, with 2 mm biochar showing a best fit (r(2) = 0.97, slope = 1.11, intercept = 1.72). Biochar reduced HPCD extractability and bioaccessibility of (14)C-phenanthrene to microorganisms in a similar manner. Biochar can aid risk reduction to phenanthrene exposure to biota in soil and HPCD can serve as a useful tool to assess the extent of exposure in biochar-amended soils.

  4. Na/sup +/-dependent transport of /sup 14/C-L-lysine across bullfrog alveolar epithelium

    SciTech Connect

    Kim, K.J.; Crandall, E.D.

    1986-03-01

    Transepithelial transport of the basic amino acid L-lysine has been studied utilizing the isolated intact bullfrog lung mounted in the Ussing chamber. Lungs were excised from doubly pithed bullfrogs and sandwiched between two hemichambers. /sup 14/C-(U)-L-lysine was added to the upstream reservoir of amphibian Ringer solution, while the tissue was short-circuited. Two lungs from the same animal were used simultaneously to determine the two opposite unidirectional fluxes. Downstream and upstream radioactivities were assayed and used to estimate the apparent permeability (P) of the labeled lysine. Results indicate that the apparent P of /sup 14/C-L-lysine measured in the alveolar (M) to the pleural (S) direction is 19.06 (+- 2.84) x 10/sup -7/ cm/s and P in the S to M direction is 3.29 (+- 0.02) x 10/sup -7/ cm/s. When the 100 mM NaCl in the bath was replaced by 110 mM choline chloride, the flux of /sup 14/C-L-lysine from the alveolar to the pleural side decreased to the same value as that in the opposite direction. The flux from the pleural to the alveolar direction in the absence of Na/sup +/ did not change. These results suggest that the alveolar epithelium exhibits Na/sup +/-dependent amino acid (L-lysine) transport in the M->S, but not in the S->M, direction.

  5. Soil metabolism of a new herbicide, [14C]Pyribenzoxim, under flooded conditions.

    PubMed

    Chang, Hee-Ra; Koo, Suk-Jin; Kim, Kyun; Ro, Hee-Myong; Moon, Joon-Kwan; Kim, Yong-Hwa; Kim, Jeong-Han

    2007-07-25

    To elucidate the fate of a new pyrimidinyloxybenzoic herbicide, pyribenzoxim, a soil metabolism study was carried out with [14C]pyribenzoxim applied to a sandy loam soil under flooded conditions. The material balance of applied radioactivity ranged from 96.4 to 104.4% and from 96.1 to 101.9% for nonsterile and sterile soils, respectively. The half-life of [14C]pyribenzoxim was calculated to be approximately 1.3 and 9.4 days for nonsterile and sterile soils, respectively. The metabolites identified during the study were 2,6-bis(4,6-dimethoxypyrimidin-2-yloxy)benzoic acid (M1) and 2-hydroxy-6-(4,6-dimethoxypyrimidin-2-yloxy)benzoic acid (M2), resulting from the cleavage of the ester bond and subsequent hydrolysis. The nonextractable radioactivity levels increased to 37.8% for nonsterile conditions at 50 days after treatment and to 38.2% for sterile conditions at 60 days after treatment. Fractionation of the nonextractable soil residues indicated that bound radioactivity was associated mainly with humin fraction. No significant volatile products or [14C]carbon dioxide was observed during the study. On the basis of these results, pyribenzoxim is considered to undergo rapid degradation in soil by microbial and chemical reactions, mainly hydrolysis, which limits its transfer to and accumulation in lower soil layers and groundwater. Therefore, the possibility of environmental contamination from the use of pyribenzoxim is expected to be very low.

  6. Measurement of local cerebral blood flow with (/sup 14/C)iodoantipyrine in the mouse

    SciTech Connect

    Jay, T.M.; Lucignani, G.; Crane, A.M.; Jehle, J.; Sokoloff, L.

    1988-02-01

    Local cerebral blood flow was measured in the mouse by means of the (/sup 14/C)iodoantipyrine method. This method has been previously used in the monkey, dog, cat, and rat, but its application to small mammals such as the mouse requires special attention to potential sources of error. The small size of the mouse brain requires special attention to the rapid removal and freezing of the brain to minimize effects of postmortem diffusion of tracer in the tissue. Because of the relatively low diameter/length ratios of the catheters needed for arterial sampling in small animals, substantial errors can occur in the determination of the time course of the (/sup 14/C)iodoantipyrine concentration in the arterial blood unless corrections for lag time and dead space washout in the catheter are properly applied. Local cerebral blood flow was measured in seven awake mice with appropriate care to minimize these sources of error. The values were found to vary from 48 ml/100 g/min in the corpus callosum to 198 ml/100 g/min in the inferior colliculus. The results demonstrate that the (/sup 14/C)iodoantipyrine method can be used to measure local cerebral blood flow in the mouse and that the values in that species are, in general, somewhat higher than those in the rat.

  7. Methods for high precision 14C AMS measurement of atmospheric CO2 at LLNL

    SciTech Connect

    Graven, H D; Guilderson, T P; Keeling, R F

    2006-10-18

    Development of {sup 14}C analysis with precision better than 2{per_thousand} has the potential to expand the utility of {sup 14}CO{sub 2} measurements for carbon cycle investigations as atmospheric gradients currently approach traditional measurement precision of 2-5{per_thousand}. The AMS facility at the Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, produces high and stable beam currents that enable efficient acquisition times for large numbers of {sup 14}C counts. One million {sup 14}C atoms can be detected in approximately 25 minutes, suggesting that near 1{per_thousand} counting precision is economically feasible at LLNL. The overall uncertainty in measured values is ultimately determined by the variation between measured ratios in several sputtering periods of the same sample and by the reproducibility of replicate samples. Experiments on the collection of one million counts on replicate samples of CO{sub 2} extracted from a whole air cylinder show a standard deviation of 1.7{per_thousand} in 36 samples measured over several wheels. This precision may be limited by the reproducibility of Oxalic Acid I standard samples, which is considerably poorer. We outline the procedures for high-precision sample handling and analysis that have enabled reproducibility in the cylinder extraction samples at the <2{per_thousand} level and describe future directions to continue increasing measurement precision at LLNL.

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

    SciTech Connect

    Cirio, A.; Boivin, R. )

    1990-05-01

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

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

    SciTech Connect

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

    1990-04-01

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

  10. Characterization of nonexchangeable radioactivity in L1210 cells incubated with ( sup 14 C)thiotepa: Labeling of phosphatidylethanolamine

    SciTech Connect

    Egorin, M.J.; Snyder, S.W. )

    1990-07-01

    N,N',N''-Triethylenethiophosphoramide ((14C)thiotepa) accumulation by L1210 cells is a biphasic process. A very rapid initial phase is followed by a much slower second phase that reflects accumulation of radioactivity in a form that is not lost or exchanged when cells are resuspended and incubated in drug-free medium for up to 8 h. In this study we attempted to characterize this nonexchangeable radioactivity. Nuclei (10(7)) isolated from L1210 cells and incubated with (14C)thiotepa did not accumulate 14C during incubations of up to 5 h. Similarly, nuclei isolated from 10(7) L1210 cells that had been shown to accumulate nonexchangeable 14C after incubation with (14C)thiotepa did not show an increase in nuclear-associated 14C. Eighty to 85% of nonexchangeable 14C in L1210 cells incubated with (14C)thiotepa was soluble in ethanol or chloroform:methanol (2:1, v/v), and although most of this cell-associated nonexchangeable 14C was precipitated by trichloroacetic acid, subsequent treatment of that precipitate with methanol solubilized most of the 14C so that only 15 to 20% remained with the final precipitate. When chloroform:methanol-soluble nonexchangeable 14C was analyzed with thin-layer chromatography systems suitable for thiotepa or simple lipids, all radioactivity remained at the origin. In contrast, when analyzed with one- and two-dimensional thin-layer chromatographic systems suitable for complex lipids, all chloroform:methanol-soluble radioactivity was associated with a single lipid spot. This lipid cochromatographed with phosphatidylethanolamine, reacted with ninhydrin but not with 4-(p-nitrobenzyl)pyridine or the Dragendorff choline reagent, and was digested by phospholipases C and D, all of which lead to its identification as phosphatidylethanolamine.

  11. [Quantifying soil autotrophic microbes-assimilated carbon input into soil organic carbon pools following continuous 14C labeling].

    PubMed

    Shi, Ran; Chen, Xiao-Juan; Wu, Xiao-Hong; Jian, Yan; Yuan, Hong-Zhao; Ge, Ti-Da; Sui, Fang-Gong; Tong, Cheng-Li; Wu, Jin-Shui

    2013-07-01

    Soil autotrophic microbe has been found numerous and widespread. However, roles of microbial autotrophic processes and the mechanisms of that in the soil carbon sequestration remain poorly understood. Here, we used soils incubated for 110 days in a closed, continuously labeled 14C-CO2 atmosphere to measure the amount of labeled C incorporated into the microbial biomass. The allocation of 14C-labeled assimilated carbon in variable soil C pools such as dissolved organic C (DOC) and microbial biomass C (MBC) were also examined over the 14C labeling span. The results showed that significant amounts of 14C-SOC were measured in paddy soils, which ranged from 69.06-133.81 mg x kg(-1), accounting for 0.58% to 0.92% of the total soil organic carbon (SOC). The amounts of 14C in the dissolved organic C (14C-DOC) and in the microbial biomass C (14C-MBC) were dependent on the soils, ranged from 2.54 to 8.10 mg x kg(-1), 19.50 to 49.16 mg x kg(-1), respectively. There was a significantly positive linear relationship between concentrations of 14C-SOC and 14C-MBC (R2 = 0.957**, P < 0.01). The 14C-DOC and 14C-MBC as proportions of total DOC, MBC, were 5.65%-24.91% and 4.23%-20.02%, respectively. Moreover, the distribution and transformation of microbes-assimilated-derived C had a greater influence on the dynamics of DOC and MBC than that on the dynamics of SOC. These data provide new insights into the importance of microorganisms in the fixation of atmospheric CO2 and of the potentially significant contributions made by microbial autotrophy to terrestrial C cycling.

  12. Does the 14C method estimate net photosynthesis? II. Implications from cyclostat studies of marine phytoplankton

    NASA Astrophysics Data System (ADS)

    Pei, Shaofeng; Laws, Edward A.

    2014-09-01

    Two species of marine phytoplankton, Isochrysis galbana and Chlorella kessleri, were grown in a continuous culture system on a 12-h:12-h light:dark cycle of illumination under nitrate-limited growth conditions. At growth rates of ~1 d-1, production rates estimated from 14C uptake were not significantly different from production rates estimated from changes in particulate organic carbon (POC) and total organic carbon (TOC). At growth rates of ~0.35 d-1, however, production rates based on uptake of 14C significantly (p<0.05) overestimated production rates based on changes in POC and TOC in all cases for C. kessleri and after 24 h for I. galbana. The ratio of production based on 14C uptake to production based on changes in POC and TOC concentrations was in all cases higher after 24 h than after 12 h. The extent of overestimation after a 24-h incubation at ~0.35 d-1 was about 23 and 40% in the cases of I. galbana and C. kessleri, respectively. Dark respiration rates estimated from changes in 14C activity during the dark period were lower than the rates estimated from changes of POC and TOC concentrations during the 12 h of darkness because only about 73% of the carbon respired during the dark period had been fixed during the previous 12-h photoperiod. The fact that the 14C method tends to overestimate net carbon assimilation by a greater percentage at low growth rates than at high growth rates probably reflects the greater efficiency of intracellular recycling of respired CO2 at high growth rates. The fact that the extent of overestimation is greater when cells are grown on a light:dark cycle probably reflects the fact that not all carbon respired in the dark was fixed during the previous photoperiod and that intracellular recycling of respired CO2 during the photoperiod is inefficient during some phases of the synchronized growth that tends to be entrained by light:dark cycles.

  13. Metabolic disposition of the anti-cancer agent [14C]laromustine in male rats

    PubMed Central

    Nassar, Ala F.; Wisnewski, Adam; King, Ivan

    2015-01-01

    Laromustine (VNP40101M, also known as Cloretazine) is a novel sulfonylhydrazine alkylating (anticancer) agent. This article describes the use of quantitative whole-body autoradiography (QWBA) and mass balance to study the tissue distribution, the excretion mass balance and pharmacokinetics after intravenous administration of [14C]VNP40101M to rats. A single 10 mg/kg IV bolus dose of [14C]VNP40101M was given to rats. The recovery of radioactivity from the Group 1 animals over a 7-day period was an average of 92.1% of the administered dose, which was accounted for in the excreta and carcass. Most of the radioactivity was eliminated within 48 h via urine (48%), with less excreted in feces (5%) and expired air accounted for (11%). The plasma half-life of [14C]laromustine was approximately 62 min and the peak plasma concentration (Cmax) averaged 8.3 μg/mL The QWBA study indicated that the drug-derived radioactivity was widely distributed to tissues through 7 days post-dose after a single 10 mg/kg IV bolus dose of [14C]VNP40101M to male pigmented Long–Evans rats. The maximum concentrations were observed at 0.5 or 1 h post-dose for majority tissues (28 of 42). The highest concentrations of radioactivity were found in the small intestine contents at 0.5 h (112.137 μg equiv/g), urinary bladder contents at 3 h (89.636 μg equiv/g) and probably reflect excretion of drug and metabolites. The highest concentrations in specific organs were found in the renal cortex at 1 h (28.582 μg equiv/g), small intestine at 3 h (16.946 μg equiv/g), Harderian gland at 3 h (12.332 μg equiv/g) and pancreas at 3 h (12.635 μg equiv/g). Concentrations in the cerebrum (1.978 μg equiv/g), cerebellum (2.109 μg equiv/g), medulla (1.797 μg equiv/g) and spinal cord (1.510 μg equiv/g) were maximal at 0.5 h post-dose and persisted for 7 days. The predicted total body and target organ exposures for humans given a single 100μCi IV dose of [14C]VNP40101M were well within the medical guidelines

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

    PubMed

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

    2013-05-01

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

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

    NASA Astrophysics Data System (ADS)

    van Mourik, J. M.

    2009-04-01

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

  16. 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

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

    PubMed

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

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-05-01

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

  19. Proton production cross sections of {sup 14}C from silicon and oxygen: Implications for cosmic-ray studies

    SciTech Connect

    Sisterson, J.M.; Jull, A.J.T.; Beverding, A.

    1993-12-31

    The production rates of {sup 14}C from proton spallation of silicon, and oxygen have been measured over a wide range of energies from 31 to 450 MeV. {sup 14}C was measured by accelerator mass spectrometry (AMS) after extraction of carbon from the samples by melting in a flow of oxygen.

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

    PubMed

    Szczech, Magdalena; Shoda, Makoto

    2005-05-01

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

  1. Effects of mesoscale eddies on global ocean distributions of CFC-11, CO2 and Δ14C

    NASA Astrophysics Data System (ADS)

    Lachkar, Z.; Orr, J. C.; Dutay, J.-C.; Delecluse, P.

    2006-07-01

    Global-scale tracer simulations are typically made at coarse resolution without explicitly modeling eddies. Here we ask what role do eddies play in ocean uptake, storage, and meridional transport of transient tracers. We made global anthropogenic transient-tracer simulations in non-eddying (2°cosφ×2°, ORCA2) and eddying (½°cosφ×½°, ORCA05) versions of the ocean general circulation model OPA9. We focus on the Southern Ocean where tracer air-sea fluxes are largest. Eddies have little effect on global and regional bomb Δ14C uptake and storage. Yet for anthropogenic CO2 and CFC-11, increased eddy activity reduces southern extratropical uptake by 28% and 25% respectively. There is a similar decrease in corresponding inventories, which provides better agreement with observations. With higher resolution, eddies strengthen upper ocean vertical stratification and reduce excessive ventilation of intermediate waters by 20% between 60° S and 40° S. By weakening the Residual Circulation, i.e., the sum of Eulerian mean flow and the opposed eddy-induced flow, eddies reduce the supply of tracer-impoverished deep waters to the surface near the Antarctic divergence, thus reducing the air-sea tracer flux. Consequently, inventories for both CFC-11 and anthropogenic CO2 decrease because their mixed layer concentrations in that region equilibrate with the atmosphere on relatively short time scales (15 days and 6 months, respectively); conversely, the slow air-sea equilibration of bomb Δ14C of 6 years, gives surface waters little time to exchange with the atmosphere before they are subducted.

  2. Comparison of circulation times of thermal waters discharging from the Idaho batholith based on geothermometer temperatures, helium concentrations, and 14C measurements

    USGS Publications Warehouse

    Mariner, R.H.; Evans, William C.; Young, H.W.

    2006-01-01

    Circulation times of waters in geothermal systems are poorly known. In this study, we examine the thermal waters of the Idaho batholith to verify whether maximum system temperatures, helium concentrations, and 14C values are related to water age in these low-to-moderate temperature geothermal systems. He/N2 values of gas collected from thermal waters that circulate solely through distinct units of the Idaho batholith correlate linearly with Na-K-(4/3)Ca geothermometer temperatures, showing that both variables are excellent indicators of relative water age. Thermal waters that circulate in early Tertiary (45-50 Ma) granite of the Sawtooth batholith have 3.5 times more helium than thermal waters of the same aquifer temperature that circulate through the main Cretaceous granite (average 91 Ma). Hot spring waters circulating in hydrothermally altered parts of the batholith have very little dissolved helium and no correlation between He/N2 values and geothermometer temperatures. Thermal waters discharging from the Idaho batholith are more depleted in deuterium than modern precipitation in the area. Recharge to these geothermal systems occurred from at least 10,000 BP for the cooler systems up to about 33,000 BP for the hotter systems.

  3. Volcanic history and 40Ar/39Ar and 14C geochronology of Terceira Island, Azores, Portugal

    USGS Publications Warehouse

    Calvert, Andrew T.; Moore, Richard B.; McGeehin, John P.; Rodrigues da Silva, Antonio

    2006-01-01

    Seven new 40Ar/39Ar and 23 new radiocarbon ages of eruptive units, in support of new geologic mapping, improve the known chronology of Middle to Late Pleistocene and Holocene volcanic activity on the island of Terceira, Azores and define an east-to-west progression in stratovolcano growth. The argon ages indicate that Cinco Picos Volcano, the oldest on Terceira, completed its main subaerial cone building activity by about 370–380 ka. Collapse of the upper part of the stratovolcanic edifice to form a 7 × 9 km caldera occurred some time after 370 ka. Postcaldera eruptions of basalt from cinder cones on and near the caldera floor and trachytic pyroclastic flow and pumice fall deposits from younger volcanoes west of Cinco Picos have refilled much of the caldera. The southern portion of Guilherme Moniz Volcano, in the central part of the island, began erupting prior to 270 ka and produced trachyte domes, flows, and minor pyroclastic deposits until at least 111 ka. The northern part of Guilherme Moniz Caldera is less well exposed than the southern part, but reflects a similar age range. The northwest portion of the caldera was formed sometime after 44 ka. Several well-studied ignimbrites that blanket much of the island likely erupted from Guilherme Moniz Volcano. The Pico Alto Volcanic Center, a tightly spaced cluster of trachyte domes and short flows, is a younger part of Guilherme Moniz Volcano. Stratigraphic studies and our new radiocarbon ages suggest that most of the Pico Alto eruptions occurred during the period from about 9000 to 1000 years BP. Santa Barbara Volcano is the youngest stratovolcano on Terceira, began erupting prior to 29 ka, and has been active historically.

  4. Pollen-based biome reconstructions for Latin America at 0, 6000 and 18 000 radiocarbon years ago

    USGS Publications Warehouse

    Marchant, R.; Cleef, A.; Harrison, S.P.; Hooghiemstra, H.; Markgraf, Vera; Van Boxel, J.; Ager, T.; Almeida, L.; Anderson, R.; Baied, C.; Behling, H.; Berrio, J.C.; Burbridge, R.; Bjorck, S.; Byrne, R.; Bush, M.; Duivenvoorden, J.; Flenley, J.; De Oliveira, P.; Van Gee, B.; Graf, K.; Gosling, W.D.; Harbele, S.; Van Der Hammen, T.; Hansen, B.; Horn, S.; Kuhry, P.; Ledru, M.-P.; Mayle, F.; Leyden, B.; Lozano-Garcia, S.; Melief, A.M.; Moreno, P.; Moar, N.T.; Prieto, A.; Van Reenen, G.; Salgado-Labouriau, M.; Schabitz, F.; Schreve-Brinkman, E. J.; Wille, M.

    2009-01-01

    The biomisation method is used to reconstruct Latin American vegetation at 6000??500 and 18 000??1000 radiocarbon years before present ( 14C yr BP) from pollen data. Tests using modern pollen data from 381 samples derived from 287 locations broadly reproduce potential natural vegetation. The strong temperature gradient associated with the Andes is recorded by a transition from high altitude cool grass/shrubland and cool mixed forest to mid-altitude cool temperate rain forest, to tropical dry, seasonal and rain forest at low altitudes. Reconstructed biomes from a number of sites do not match the potential vegetation due to local factors such as human impact, methodological artefacts and mechanisms of pollen representivity of the parent vegetation. At 6000??500 14C yr BP 255 samples are analysed from 127 sites. Differences between the modern and the 6000??500 14C yr BP reconstruction are comparatively small; change relative to the modern reconstruction are mainly to biomes characteristic of drier climate in the north of the region with a slight more mesic shift in the south. Cool temperate rain forest remains dominant in western South America. In northwestern South America a number of sites record transitions from tropical seasonal forest to tropical dry forest and tropical rain forest to tropical seasonal forest. Sites in Central America show a change in biome assignment, but to more mesic vegetation, indicative of greater plant available moisture, e.g. on the Yucat??n peninsula sites record warm evergreen forest, replacing tropical dry forest and warm mixed forest presently recorded. At 18 000??1000 14C yr BP 61 samples from 34 sites record vegetation reflecting a generally cool and dry environment. Cool grass/shrubland is prevalent in southeast Brazil whereas Amazonian sites record tropical dry forest, warm temperate rain forest and tropical seasonal forest. Southernmost South America is dominated by cool grass/shrubland, a single site retains cool temperate rain

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  6. Uptake of (/sup 14/C)deoxyglucose into brain of young rats with inherited hydrocephalus

    SciTech Connect

    Richards, H.K.; Bucknall, R.M.; Jones, H.C.; Pickard, J.D.

    1989-02-01

    The effect of hydrocephalus on cerebral glucose utilization as reflected by deoxyglucose uptake has been examined in rats with inherited hydrocephalus at 10, 20, and 28 days after birth using a semiquantitative method. Injection of (14C)deoxyglucose intraperitoneally was followed by freezing the brain, sectioning, and quantitative autoradiography of 10 brain regions. Brain (14C) concentration, cortical thickness, and plasma glucose concentrations were measured. Maximal thinning of the cerebral cortex had already occurred by 10 days after birth, although obvious symptoms such as gait disturbance developed after 20 days. In control rats, the cerebral isotope concentration was lower and more homogeneous at 10 days than at 20 or 28 days, which may be a reflection of the use of metabolic substrates other than glucose in younger animals. In order to make comparisons between control and hydrocephalic groups, tissue isotope concentrations were normalized to cerebellar cortex which was not affected by the hydrocephalus at any age. In hydrocephalic rats at 10 and 20 days, the concentration of (14C) was lower in all areas except the inferior colliculi and pons but the reduction was only significant in the sensory-motor cortex at 10 days and in the caudate nuclei at 20 days. By 28 days after birth, all areas except the cerebellum (six cortical regions, inferior colliculi, pons, and caudate) had significantly lower isotope concentrations in the hydrocephalic group. It is concluded that cerebral glucose metabolism is significantly reduced by 28 days after birth in H-Tx rats with congenital hydrocephalus and that less marked reductions occur prior to 28 days.

  7. Concentrations and 14C age of nonstructural carbon in California oaks

    NASA Astrophysics Data System (ADS)

    Czimczik, C. I.; Druffel-Rodriguez, K.; Trumbore, S. E.

    2008-12-01

    Plants store photosynthetic assimilates as nonstructural carbon (NSC), mainly glucose, fructose, sucrose, and starch. NSC fuels processes such as respiration and growth. Research suggests that NSC represents a significant fraction of a plant's annual C budget, but temporal dynamics of NSC are poorly understood. We used concentration and radiocarbon (14C) measurements of NSC to investigate how temporal dynamics of NSC vary with life strategy and throughout a species' range. In Mediterranean environments, oaks have developed two strategies (evergreen and deciduous) to cope with drought. Within California, the uncertainty of annual winter rain increases from north to south. We compared two evergreen and deciduous species: Coastal and Interior live oak (Quercus agrifolia and wislizenii) and Valley and Blue oak (Q. lobata and douglasii). Samples (4 mm cores to 20 cm depth at dbh) were taken in 2008 before leaf-out and fall at five sites which represent an inland to coast temperature gradient from high to low summer temperatures as well as a north- south precipitation gradient. Sugars were isolated by shaking in methanol-water and quantified using a spectrometric micro-plate technique. Starch was isolated by boiling in ethanol followed by HCl digestion and quantified manometrically. 14C contents were measured by AMS. Preliminary findings indicate that in live oaks, winter sugar concentrations are constant throughout the tree and across sites, while 14C concentrations increase towards a tree's center. This suggests that the NSC pool oaks is not well mixed. Future work will elucidate whether plants can access these older NSC stores.

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

    SciTech Connect

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

    2000-06-16

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

  9. Binding of mescaline with subcellular fractions upon incubation of brain cortex slices with [14C] mescaline.

    PubMed

    Datta, R K; Antopol, W; Ghosh, J J

    1977-01-01

    Incubation of brain cortex slices in the presence of glucose resulted in the permeation of about 65% of [14C] mescaline into slices. Of this, about one-third radioactivity was bound with nuclei, mitochondria, microsomes, and ribosomes. Dialysis of subcellular fractions did not markedly reduce the amounts of radioactivity bound to the fractions. The permeation into slices and the binding of mescaline to subcellular fractions were fairly time-dependent, but were inhibited by the presence of potassium cyanide, or by the absence of glucose and by heating to 80 degrees C for 1 min.

  10. Searching For A Suitable Gas Ion Source For 14C Accelerator Mass Spectrometry

    SciTech Connect

    Reden, Karl von; Roberts, Mark; Han, Baoxi; Schneider, Robert; Wills, John

    2007-08-10

    This paper describes the challenges facing 14C Accelerator Mass Spectrometry (AMS) in the effort to directly analyze the combusted effluent of a chromatograph (or any other continuous source of sample material). An efficient, low-memory negative gas ion source would greatly simplify the task to make this a reality. We discuss our tests of a microwave ion source charge exchange canal combination, present an improved design, and hope to generate more interest in the negative ion source community to develop a direct-extraction negative carbon gas ion source for AMS.

  11. A batch preparation method for graphite targets with low background for AMS [sup 14]C measurements

    SciTech Connect

    Kitagawa, Hiroyuki International Research Center for Japanese Studies, Nishikyp-ku, Kyoto ); Masuzawa, Toshiyuki; Matsumoto, Eiji ); Makamura, Toshio )

    1993-01-01

    The authors have developed a method of graphitization from CO[sub 2] samples for accurate [sup 14]C measurements by accelerator mass spectrometry. Their batch method, using a sealed Vycor tube, reduces the risk of contamination during graphitization and makes it possible to prepare many samples in a short time (typically 20 samples per day). They also describe details of the target-preparation method involving carbon isotopic fractionation during graphitization, yield of graphite from CO[sub 2], ion-beam intensity of the target, and background (or blank) level estimated using bituminous coal.

  12. Transformation of (14)C-pyrimidynyloxybenzoic herbicide ZJ0273 in aerobic soils.

    PubMed

    Haiyan, Wang; Zhiyang, Yu; Ling, Yue; Ailiang, Han; Yanfei, Zhang; Juying, Li; Qingfu, Ye; Zhengmin, Yang; Long, Lu

    2010-04-15

    A soil metabolism study of propyl 4-(2-(4,6-dimethoxypyrimidin-2-yloxy)benzylamino)benzoate (ZJ0273), a novel broad-spectrum herbicide, was carried out using (14)C labeled on two different rings, i.e., [pyrimidine-4,6-(14)C] ZJ0273 and [benzyl-U-(14)C] ZJ0273. Ultralow liquid scintillation counting and LC-MS/MS were used to identify the degradation intermediates and quantify their dynamics in aerobic soils. Four aromatic intermediates, 4-(2-(4,6-dimethoxypyrimidin-2-yloxy)benzylamino)benzoic acid (M1), 4-(2-(4,6-dimethoxypyrimidin-2-yloxy)benzamido)benzoic acid (M2), 2-(4,6-dimethoxypyrimidin-2-yloxy)benzoic acid (M3), and 4,6-dimethoxypyrimidin-2-ol (M4), were identified and their identity was further confirmed against authentic standards. Analysis of metabolites suggested two degradation pathways: (1) Upon loss of the propyl group, M1 was produced via hydrolysis of propyl 4-(2-(4,6-dimethoxypyrimidin-2-yloxy)benzylamino)benzoate after which the C-N bond between rings A and B was cleaved by oxidation and biochemical degradation to yield M3, which was further converted into M4 and finally mineralized to CO(2); and (2) the first step was the same as in pathway 1, but M1 first underwent a carbonylation to form M2. The C-N bond between rings A and B of M2 was cleaved by hydrolysis to yield M3. Dynamic changes in the four metabolites in aerobic soils were also investigated by HPLC coupled analysis of radioactivity of isolated peaks. After a 100-day incubation, 1.7-9.7% of applied (14)C was found as M1, 0.3-1.1% as M2, 14.5-20.9% as M3, and 3.7-6.7% as M4 in the soils, and pH appeared to be the most influential soil property affecting the formation and dissipation of these metabolites.

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

    SciTech Connect

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

    1995-07-01

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

  14. Excised barley root uptake of several /sup 14/C labeled organic compounds

    SciTech Connect

    McFarlane, C.; Wickliff, C.

    1985-01-01

    Many organic pollutants potentially are available for uptake by plants and thus bioaccumulation and food contamination. One method of studying uptake is with excised roots, a technique extensively used with plant nutrients. A similar method was developed and used to evaluate uptake patterns of several /sup 14/C-labeled organic chemicals. Uptake rate constants for the chemicals tested occurred in the following order: captan approx. phenol > aniline > ethanol approx. indole approx. trifluralin approx. propanil > 1,2,4-trichlorobenzene(TCB) > nitrobenzene approx. atrazine > bromacil > simazine > monuron.

  15. [The auditory pathway in guinea pigs. A [14C]2-deoxyglucose study (author's transl)].

    PubMed

    Strutz, J; Beck, C; Schmidt, C L

    1981-01-01

    The auditory pathway of guinea pigs was labeled with [14C]-deoxyglucose after mon- or binaural stimulation with farfield white noise in a sound-proof chamber. In the autoradiographs, all auditory nuclei were labeled. The highest metabolic effects were seen in the dorsal cochlear nucleus, the lateral superior olivary nucleus, and in the inferior colliculus. No selective labeling was observed in the auditory cortex. Monaural stimulation depressed the metabolic activity contralaterally in the ventral cochlear nucleus and ipsilaterally in the medial nucleus of the trapezoid body, the dorsomedial periolivary nucleus, and in the inferior colliculus. PMID:7213192

  16. Accumulation and elimination of (9-/sup 14/C)phenanthrene in the calico clam (Macrocallista maculata)

    SciTech Connect

    Solbakken, J.E.; Jeffrey, F.M.H.; Knap, A.H.; Palmork, K.H.

    1982-05-01

    The accumulation and elimination of radoactivity is studied after exposure of (9-/sup 14/C) phenanthrene in various tissues in the calico clam (Macrocallista maculata). Results show that accumulation is highest in the lipid-rich hepatopancreas, and the elimination is very efficient compared to the horse mussel. The calico clam, which is a sand-dwelling organism, can easily come in contact with hydrocarbon contaminated sedments and might accumulate the hydrocarbons at different extents in various tissues. The efficient elimination, however, will prevent a lasting accumulation. (JMT)

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

    NASA Astrophysics Data System (ADS)

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

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-04-01

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

  19. Effects of biochar and the geophagous earthworm Metaphire guillelmi on fate of (14)C-catechol in an agricultural soil.

    PubMed

    Shan, Jun; Wang, Yongfeng; Gu, Jianqiang; Zhou, Wenqiang; Ji, Rong; Yan, Xiaoyuan

    2014-07-01

    Both biochar and earthworms can exert influence on behaviors of soil-borne monomeric phenols in soil; however, little was known about the combined effects of biochar and earthworm activities on fate of these chemicals in soil. Using (14)C-catechol as a representative, the mineralization, transformation and residue distribution of phenolic humus monomer in soil amended with different amounts of biochar (0%, 0.05%, 0.5%, and 5%) without/with the geophagous earthworm Metaphire guillelmi were investigated. The results showed biochar at amendment rate <0.5% did not affect (14)C-catechol mineralization, whereas 5% biochar amendment significantly inhibited the mineralization. Earthworms did not affect the mineralization of (14)C-catechol in soil amended with <0.5% biochar, but significantly enhanced the mineralization in 5% biochar amended soil when they were present in soil for 9 d. When earthworms were removed from the soil, the mineralization of (14)C-catechol was significantly lower than that of in earthworm-free soil indicating that (14)C-catecholic residues were stabilized during their passage through earthworm gut. The assimilation of (14)C by earthworms was low (1.2%), and was significantly enhanced by biochar amendment, which was attributed to the release of biochar-associated (14)C-catecholic residues during gut passage of earthworm.

  20. ED 03-2 HOME BLOOD PRESSURE MONITORING IS BETTER THAN OFFICE BP AND AMBULATORY BP: UPDATE.

    PubMed

    Kario, Kazuomi

    2016-09-01

    Out-of-office blood pressure (BP) measured by home BP monitoring (HBPM) or ambulatory BP monitoring (ABPM) was demonstrated to be superior to office BP for the prediction of cardiovascular events. The ABPM is superior to HBPM for detecting the all the BP-related risks throughout 24-hr, and the self-measured HBPM underestimates the risk of daytime stress hypertension and nocturnal hypertension. However, ABPM cannot always be provided in clinical practice, and home BP monitoring can be superior to ABPM as part of a home BP-guided antihypertension strategy in clinical practice. In clinical practice, we should use both ABPM and HBPM considering these device properties. We have developed the new ABPM device which is alternatively used as self-measure HBPM (Kario. Prog Cardiovasc Dis 2016, in press).The importance of on-treatment HBPM for the cardiovascular prognosis of hypertensive individuals was recently revealed in the largest real-world prospective study held to date, the Home blood pressure measurement with Olmesartan Naive patients to Establish Standard Target blood pressure (HONEST) study. That study of more than 21 000 hypertensive patients used HBPM, and the results demonstrated that when morning home systolic BP was well-controlled during the 2-year follow-up at < 125 mmHg, there was no increase in cardiovascular events even among the patients whose office systolic BP was ≥150 mmHg, compared with those with office systolic BP < 130 mmHg and morning home systolic BP < 125 mmHg. On the other hand, even when the office systolic BP of the HONEST study's hypertensive patients was well controlled at < 130 mmHg, the hazard ratio of cardiovascular events was 2.5 in the masked uncontrolled hypertension patients with morning systolic BP ≥145 mmHg compared with the well-controlled patients with morning systolic BP < 125 mmHg (Kario, et al. Hypertension 2014;64:989-996). The threshold of on-treatment morning BP for a significant increase in

  1. Plasma, cerebrospinal fluid, and brain distribution of /sup 14/C-melatonin in rat: a biochemical and autoradiographic study

    SciTech Connect

    Vitte, P.A.; Harthe, C.; Lestage, P.; Claustrat, B.; Bobillier, P.

    1988-01-01

    The distribution of 14C-Melatonin (14C-MT) after systemic injection was studied in the plasma, cerebrospinal fluid (CSF), and brain of rats. Chromatographic analysis (thin-layer chromatography and high-performance liquid chromatography) indicated that the radioactivity from biological samples taken at various times following the injection of label was mainly associated with 14C-MT. Computer analysis of plasma 14C-MT kinetics showed a three-compartment system with half-lives of 0.21 +/- 0.05, 5.97 +/- 1.11, and 47.52 +/- 8.86 min. The volume of distribution and the clearance were 1,736 +/- 349 ml.kg-1 and 25.1 +/- 1.7 ml.min-1.kg-1 respectively. The entry of 14C-MT into the CSF was rapid and reached a maximum at 5 min. The decay followed a two-compartment system with half-lives of 16.5 +/- 2.9 and 47.3 +/- 8.6 min. The CSF/plasma concentration ratio was 0.38 at the steady state (30 min). At 2 min the level of 14C-MT in the brain was 3.8 higher than in the CSF. Representative autoradiograms revealed an heterogeneous localization of 14C-MT in the grey matter. The highest regional values, as evaluated by the permeability area product technique, were found in cortex, thalamic nuclei, medial geniculate nucleus, anterior pretectal area, paraventricular nucleus of the hypothalamus, choroid plexuses, and bulb-pons. Thirty minutes later 14C-MT was still detected in most of the brain regions analyzed. These results point to a low but rapid penetration of circulating MT into the brain and the CSF. The heterogeneous distribution and the partial retention of 14C-MT in the brain are compatible with the hypothesis of a central action of this hormone mediated via binding sites.

  2. Modeling of irradiated graphite (14)C transfer through engineered barriers of a generic geological repository in crystalline rocks.

    PubMed

    Poskas, Povilas; Grigaliuniene, Dalia; Narkuniene, Asta; Kilda, Raimondas; Justinavicius, Darius

    2016-11-01

    There are two RBMK-1500 type graphite moderated reactors at the Ignalina nuclear power plant in Lithuania, and they are under decommissioning now. The graphite cannot be disposed of in a near surface repository, because of large amounts of (14)C. Therefore, disposal of the graphite in a geological repository is a reasonable solution. This study presents evaluation of the (14)C transfer by the groundwater pathway into the geosphere from the irradiated graphite in a generic geological repository in crystalline rocks and demonstration of the role of the different components of the engineered barrier system by performing local sensitivity analysis. The speciation of the released (14)C into organic and inorganic compounds as well as the most recent information on (14)C source term was taken into account. Two alternatives were considered in the analysis: disposal of graphite in containers with encapsulant and without it. It was evaluated that the maximal fractional flux of inorganic (14)C into the geosphere can vary from 10(-11)y(-1) (for non-encapsulated graphite) to 10(-12)y(-1) (for encapsulated graphite) while of organic (14)C it was about 10(-3)y(-1) of its inventory. Such difference demonstrates that investigations on the (14)C inventory and chemical form in which it is released are especially important. The parameter with the highest influence on the maximal flux into the geosphere for inorganic (14)C transfer was the sorption coefficient in the backfill and for organic (14)C transfer - the backfill hydraulic conductivity. PMID:27387810

  3. Fate of the naphthenic acid, U-{sup 14}C-palmitic acid, in constructed wetlands; A microcosm study

    SciTech Connect

    Wood, A.; Barjaktarovic, L.; Moore, M.; Kennedy, C.; Farrell, A.P.; Bendell-Young, L.I.

    1995-12-31

    This study represents part of an overall initiative to assess the ecological viability of constructed wetlands for the treatment of oil sands wastewater. To determine the fate of naphthenic acids (C{sub n}H{sub 2n+z}O{sub 2}), the most toxic component of oil sands wastewater, in constructed wetlands, a representative naphthenic acid (NA), U-{sup 14}C-palmitic acid was added to microcosms placed within three control and three treatment wetlands. Treatment wetlands receive wastewater typical of effluent resulting from the oil sands extraction process. In each of the 6 microcosms, biotic compartments measured for {sup 14}C at t = 0, 1, 3, 5, 7, 14 and 21 days were: mineralized palmitic acid (evolved {sup 14}C-CO{sub 2}), water, suspended sediments, bottom sediments, cattail, chironomid larvae, and sticklebacks (liver, muscle and skin). The fate of the {sup 14}C-palmitic acid was similar between the control versus treatment microcosms. Exceptions were greater amounts of {sup 14}C-palmitic acid detected in water and suspended sediments of treatment versus control microcosms. Of the biotic compartments, at t = 21 days, the majority of the {sup 14}C-palmitic acid was found in chironomids and fish tissues. Mineralization and partitioning of {sup 14}C-palmitic acid onto sediments also represented important fates. From the initial addition of the labelled compound, with the exception of bottom sediments, by t = 1 day {sup 14}C was detected in ail biotic compartments. {sup 14}C was detected in bottom sediments by t = 7 days. These results indicate that in addition to mineralization being an important process influencing the fate palmitic acid within the wetlands, partitioning into biotic compartments such as chironomids and fish are also important fates. Hence, when considering the use of constructed wetlands for the treatment of oil sands effluent, the adverse effects of naphthenic acids on the biota needs to be fully addressed.

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

    PubMed

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

    2008-11-01

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

  5. The disposition of /sup 14/C-trimethyltin in the pregnant rat and fetus

    SciTech Connect

    Lipscomb, J.C.; Paule, M.G.; Slikker, W. Jr.

    1989-03-01

    Trimethyltin (TMT) is a potent neurotoxicant. For unknown reasons, age at exposure to TMT may dramatically influence the severity of TMT-induced neuropathology. We have demonstrated previously that radiolabel derived from (/sup 14/C)-TMT given to pregnant dams on gestational day (GD) 17 is found in fetal brain and blood. The present study was designed to determine the distribution of radiolabel derived from (14C)-TMT to brain and other tissue in fetuses from dams dosed on either GD 12 or 17 with 7.0 mg/kg TMT chloride. Radioactivity in GD 12 and GD 17 maternal whole blood peaked 1 hour after IP treatment. Whole blood elimination half-lives were 12-15 days. Peak radiolabel concentrations in GD 12 maternal and fetal brain were only 11-30% of those from GD 17 animals, however, peak fetal brain concentrations of radiolabel were not different from their respective maternal brain concentrations. Radiolabel concentrations in liver, kidney, and adrenal of GD 17 dams were higher than those in corresponding GD 12 tissues. Combined urinary and fecal elimination of radiolabel for two weeks after dosing accounted for 31 and 22% of the GD 12 and 17 doses, respectively. It appears that gestational age influences the distribution and elimination of TMT in the rat.

  6. Myocardial metabolism of free fatty acids. Studies with /sup 14/C-labeled substrates in humans

    SciTech Connect

    Wisneski, J.A.; Gertz, E.W.; Neese, R.A.; Mayr, M.

    1987-02-01

    Free fatty acids are considered to be the major energy source for the myocardium. To investigate the metabolic fate of this substrate in humans, 24 subjects underwent coronary sinus and arterial catheterization. 13 subjects were healthy volunteers and 11 subjects had symptoms of ischemic heart disease. (1-/sup 14/C)oleate or (1-/sup 14/C)palmitate bound to albumin was infused at a constant rate of 25 microCi/h. Oxidation was determined by measuring the /sup 14/CO/sub 2/ production. The data demonstrated that a high percentage (84 +/- 17%) of the palmitate and oleate extracted by the myocardium underwent rapid oxidation. A highly significant correlation was present between the arterial level and the amount oxidized (r = 0.82, P less than 0.001 for palmitate; r = 0.77, P less than 0.001 for oleate). The isotope extraction ratio was greater than the chemical extraction ratio. This difference of 6 +/- 2 nmol/ml of blood in the young normal subjects was significantly less than the 12 +/- 4 nmol/ml observed in the ischemic heart disease patients (P less than 0.001).

  7. Mechanisms of subglacial groundwater recharge as derived from noble gas, 14C, and stable isotopic data

    NASA Astrophysics Data System (ADS)

    Grundl, Tim; Magnusson, Nathan; Brennwald, Matthias S.; Kipfer, Rolf

    2013-05-01

    Noble gas, stable isotope and 14C data from samples collected along groundwater flow path within a confined Paleozoic aquifer in northeastern Wisconsin, USA are used to deduce the effect of the Laurentide Ice Sheet (LIS) on the underlying groundwater and its recharge dynamics. During the last glacial maximum the investigated area was near the center of the Green Bay Lobe of the LIS. 14C ages that extend to 26 k.a. and low δ18O derived temperatures during the time that the LIS was present indicate that aquifer recharge continued when ice covered the area. δ18O values as low as -17.5‰ and δ2H values as low as -127.7‰ indicate that a significant portion of aquifer recharge was derived from glacial meltwater that maintained its glacial isotopic signature during melting and subsequent recharge. Noble gas temperatures that remain above freezing at a constant ~3 °C, unusually high excess air (ΔNe) values and noble gas fractionation patterns indicate that recharge occurred across a very dynamic water table located within the ice sheet. This englacial hydrologic system experienced recharge heads of as much as 7.8 m. Evidence for direct recharge of basal meltwater into the aquifer is not seen. To the authors' knowledge this is the first time that noble gas and isotope tracers have been used to deduce the provenance of aquifer water beneath continental ice sheets.

  8. Distribution of [(14)C]imidacloprid in sunflowers (Helianthus annuus L.) following seed treatment.

    PubMed

    Laurent, François M; Rathahao, Estelle

    2003-12-31

    Imidacloprid, a neonicotinic insecticide, has been used as a seed dressing (Gaucho) to protect crops against soil and aerial insects. However, French beekeepers observed abnormal behavior of bees foraging on sunflowers and suspected a link between the imidacloprid seed treatment and the observed bee syndrome. This work studies the distribution of [(14)C-imidazolidin]imidacloprid (1 mg/seed) in three stages of Gaucho-treated sunflowers grown in an outdoor lysimeter. Plants absorbed <10% of [(14)C]imidacloprid spiked on seeds, and 75% of that absorbed radioactivity was found in cotyledons. Concentrations in the upper leaves were 20 times lower than in the first leaves. From the extracted radioactivity, imidacloprid accounted for 50% and metabolites for the other 50%. Four major metabolites can be detected, in variable concentrations, among which the hydroxy- and olefin-imidacloprid have toxicities equivalent to that of imidacloprid. In pollen, concentrations of imidacloprid were 13 ng x g(-1). Thus, imidacloprid residues from Gaucho seed treatment contaminated sunflower pollen, involving the translocation of imidacloprid within the plant.

  9. 14C-[lignin]-lignocellulose biodegradation by bacteria isolated from polluted soil.

    PubMed

    Kumar, L; Rathore, V; Srivastava, H

    2001-06-01

    Four bacterial species [Branhamella catarrhalis (gram -ve), Brochothrix species (gram -ve), Micrococcus luteus (gram +ve) and Bacillus firmus (gram +ve)], isolated from the soil polluted with cane sugar factory effluents, were found capable of growing on solid media supplemented with indulin AT (a polymeric industrial lignin) as sole C source. All the four species could metabolize cinnamic acid (a non-hydroxylated phenylpropanoid) as sole carbon source with significant suppression on addition of readily metabolizable carbon source (glucose). However, Br. catarrhalis and Brochothrix sp. were capable of metabolizing ferulic acid, but could not do so on addition of glucose. Of the four species, Br. catarrhalis could evolve significant amount of 14CO2 from U-14C (lignin)-lignocellulose prepared from rice stalks (ca. 10% of the added radioactivity in 3 weeks), in addition to solubilization of another 11.7% radioactivity in culture filtrate. The other three species could not significantly evolve 14CO2, though a significant fraction of added 14C-lignin (6.1 to 11.2%) could be solubilized into culture filtrate, suggesting lack of ring-cleavage or other CO2 evolving mechanisms in these species.

  10. Factors affecting the uptake of 14C-labeled organic chemicals by plants from soil

    SciTech Connect

    Topp, E.; Scheunert, I.; Attar, A.; Korte, F.

    1986-04-01

    The uptake of /sup 14/C from various /sup 14/C-labeled organic chemicals from different chemical classes by barley and cress seedlings from soil was studied for 7 days in a closed aerated laboratory apparatus. Uptake by roots and by leaves via the air was determined separately. Although comparative long-term outdoor studies showed that an equilibrium is not reached within a short time period, plant concentration factors after 7 days could be correlated to some physicochemical and structural substance properties. Barley root concentration factors due to root uptake, expressed as concentration in roots divided by concentration in soil, gave a fairly good negative correlation to adsorption coefficients based on soil organic carbon. Barley root concentration factors, expressed as concentration in roots divided by concentration in soil liquid, gave a positive correlation to the n-octanol/water partition coefficients. Uptake of chemicals by barley leaves via air was strongly positively correlated to volatilization of chemicals from soil. Both root and foliar uptake by barley could be correlated well to the molecular weight of 14 chemicals. Uptake of chemicals by cress differed from that by barley, and correlations to physicochemical substance properties mostly were poor.

  11. Implications of the 14C(α,γ)18O reaction for nonstandard big bang nucleosynthesis

    NASA Astrophysics Data System (ADS)

    Gai, Moshe

    1992-06-01

    The thermonuclear burning rates for the 14C(α,γ)18O radiative capture reaction are calculated at temperatures (0.314C(α,γ)18O cross section. The gamma widths of the proposed broad state is estimated using the Alhassid, Gai, and Bertsch sum rule, and an experimental study is proposed.

  12. Effect of protein quality on /sup 14/C glucose utilization in isolated rat mammary acini

    SciTech Connect

    Masor, M.L.; Grundleger, M.L.; Jansen, G.R.

    1986-03-01

    Poor protein quality has a deleterious effect on lactation in rats. Dams consuming a 13% wheat gluten (WG) diet are unable to maintain litters. Glucose utilization in isolated mammary acini taken from dams at either day 20 of gestation (G20) or day 4 of lactation (L4) was examined in dams consuming 13% WG vs 13% casein-methionine (CM) diets from day of breeding. Dams consuming WG had significantly smaller inguinal-abdominal mammary glands than CM dams at both G20 and L4, and mammary glands of CM but not WG dams were larger at L4 than G20. Both average pup weight and pup daily gain were smaller in WG litters. Basal levels of /sup 14/C glucose oxidation (GO) and /sup 14/C glucose incorporation into lipid (GL) and lactose were examined. A large significant increase in GO and GL occurred in CM dams from G20 to L4 but not in WG dams. Both GO and GL were higher in CM dams on L4 but not at G20. The ratio of GO:GO+GL changed at parturition in CM but not WG dams. The normal changes in glucose utilization by mammary epithelial cells which occur at parturition were impaired by the WG diet.

  13. Translocation of 14C Sucrose in Sugar Beet during Darkness 1

    PubMed Central

    Geiger, D. R.; Batey, J. W.

    1967-01-01

    The time-course of arrival of 14C translocate in a sink leaf was studied in sugar beet (Beta vulgaris L. cultivar Klein Wanzleben) for up to 480 minutes of darkness. Following darkening of the source leaf, translocation rapidly declined, reaching a rate approximately 25% of the light period rate by 150 minutes. Comparison of data from plants that were girdled 1 cm below the crown with data from ungirdled plants indicates that after about 150 minutes darkness the beet root becomes a source of translocate to the sink leaf. After about 90 minutes darkness, starch-like reserve polysaccharide from the source leaf begins to contribute 14C to ethanol soluble pools in that leaf. Because of a 15% isotope mass effect, sucrose, at isotopic saturation, reaches a specific activity which is about 85% of the level of the supplied CO2. The source leaf sucrose specific activity remains at the isotopic saturation level for about 150 minutes of darkness, after which time input from polysaccharide reserves causes the specific activity to drop to about 55% of that of the supplied CO2. Sucrose specific activity determinations, polysaccharide dissolution measurements, and pulse labeling experiments indicate that following partial depletion of the sucrose pool, source leaf polysaccharide contributes to dark translocation. Respired CO2 from the source leaf appears to be derived from a pool which, unlike sucrose, remains at a uniform specific activity. PMID:16656714

  14. Study of the formation of biogenic speleothems found in submarine caves at the cape of Otranto, Italy, by 14C AMS

    NASA Astrophysics Data System (ADS)

    D'Elia, M.; Quarta, G.; Calcagnile, L.; Belmonte, G.

    2007-06-01

    Submarine caves at the Cape of Otranto, Italy, contain eccentric stalactites that were recently identified as entirely biogenic. One of these stalactites was sectioned along its longitudinal axis in order to select samples for radiocarbon dating. 14C AMS measurements provided fundamental information for the interpretation of the biogenic pr