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Sample records for 14c ka bp

  1. 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.

  2. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  4. 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.

  5. 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.

  6. Records of the paleoclimate during the fast transgression period (13 ka BP-8 ka BP) from the mud area on the inner shelf of the East China Sea

    NASA Astrophysics Data System (ADS)

    Liu, S.

    2015-12-01

    A 35.30m-long core (MZ02) recovered from a water depth of 32.4m from the inner shelf mud deposit of the East China Sea was analyzed for sedimentary characteristics, color reflectance, clay mineral, and element geochemistry components as well as by AMS 14C dating to research the sedimentation rate, sediment provenance and paleocwan mountainous river and clay fralimate evolution during the fast transgression period in the study area. Rare earth element and clay mineral proxies indicated that the mixed provenance sediment accumulated in the foreshore-nearshore region at the beginning of the fast transgression period, with a higher sedimentation rate of 5.58m/ka. While from 9800-9500 a B.P., the sedimentation rate keep lower about 1.73m/ka, and the sediment provenance changed obviously, silt fraction were apt to Taiction prone to be transported from the Yangtze River. Multiple proxy system including sediment redness (a*), chemical index of alteration (CIA), clay mineral proxy (smectite/kaolinite), major and trace element proxy (CaO/MgO, Ba/Sr) also showed a good paleoclimate record during the fast transgression period, which could be divided into three units. All the proxies changed little during Unit I (13-11.3ka B.P.) and revealed the climate kept in a relative stable level. Obvious fluctuation happened in Unit II (11.3-10.1ka B.P.) and the temperature kept decreasing more than 1ka till the Younger Dryas event, showed a well regional response to global climate changes. While continuous warming trend resumed again in Unit III (10.1-8 ka B.P.), which may be the signal for Holocene warm period. In addition, we also found significant 80yr, 89yr and 100yr cycles in our CIA, CaO/MgO and Ba/Sr records that imply a possible solar influence on the regional climate changes during the fast transgression period. Keywords: East China Sea, provenance, transgression, mud deposit, late Pleistocene, paleoclimate

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

    NASA Astrophysics Data System (ADS)

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

    2003-12-01

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

  8. [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.

  9. 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.

  10. GIS-Based Paleotopographic Reconstructions of the Queen Elizabeth Islands at 8500 14C yr B.P

    NASA Astrophysics Data System (ADS)

    Calderon, S. C.; Leverington, D. W.

    2009-12-01

    Until ~11,000 14C yr B.P., the Queen Elizabeth Islands of the Canadian High Arctic were covered by the Innuitian Ice Sheet and by the northernmost extent of the Laurentide Ice Sheet. The loading of the crust by these ice masses resulted in glacio-isostatic subsidence, most notably in the eastern part of the archipelago. Gradual deglaciation of the region was accompanied by differential glacio-isostatic rebound, with areas of greatest rebound corresponding to areas of greatest prior loading and subsidence. Changes in the effects of glacial loading and unloading, combined with changes in the volume and loading effects of sea water, progressively transformed the paleogeography of the region during deglaciation. In this research, geographic information system (GIS) software was used to reconstruct the topography (including bathymetry) of the Queen Elizabeth Islands at 8500 14C yr B.P. Both moderate-resolution (1 arc minute per pixel) and high-resolution (3 arc seconds per pixel) databases of paleotopography were created by subtracting interpolated isobase data (derived from England et al., 2006) from databases of modern topography. These paleotopographic databases were used to generate cartographic visualizations and to quantify aspects of the forms and extents of straits and major islands. The greater elevations and steeper slopes of the peripheries of large eastern islands such as Ellesmere and Devon resulted in surface areas at 8500 14C yr B.P. that were only ~8% less than at present, despite the concentration of glacial loading here. The lower elevations and slopes of islands in the central part of the archipelago facilitated the substantial and even complete submergence of landmasses below sea level at 8500 14C yr B.P. For example, Bathurst Island had a surface area that was ~45% less than that of today, and islands including Loughheed, Graham, and Byam Martin were almost entirely submerged below the surface of an open sea at this time. The geometries of local

  11. 14C ages and activity for the past 50 ka at Volcán Galeras, Colombia

    USGS Publications Warehouse

    Banks, N.G.; Calvache, V.M.L.; Williams, S.N.

    1997-01-01

    Volcán Galeras is the southernmost Colombian volcano with well-recorded historic activity. The volcano is part of a large and complex volcanic center upon which 400,000 people live. Historic activity has centered on a small-volume cone inside the youngest of several large amphitheaters that breach the west flank of the volcano, away from the city of Pasto (population 300,000). Lava flows (SiO2 between 54.6 and 64.7 wt.%) have dominated activity for more than 1 Ma, but explosive events have also occurred. Joint studies by volcanologists from Colombia, Ecuador, Peru, Bolivia, Argentina, and the United States produced 24 new14C ages and more than 100 stratigraphic sections to interpret the past 50 ka of activity at Galeras, including sector collapse events. The youngest collapse event truncated 12.8 ka lava flows and may have occurred as recently as 8 to 10 ka. Tephra-fall material rapidly thins and becomes finer away from the vent area. The only widespread marker in the < 10 ka section is a biotite-bearing tephra deposited between 4.1 and 4.5 ka from a source south of Galeras. It separates cryoturbated from largely undisturbed layers on Galeras, and thus dates a stratigraphic horizon which is useful in the interpretation of other volcanoes and geotectonics in the equatorial Andes. Pyroclastic flows during the past 50 ka have been small to moderate in volume, but they have left numerous thin deposits on the north and east flanks where lava flows have been impeded by crater and amphitheater walls. Many of the pyroclastic-flow deposits are lithic rich, with fines and clasts so strongly altered by hydrothermal action before eruption that they, as well as the sector collapse deposits, resemble waste dumps of leached cappings from disseminated sulfide deposits more than volcanogenic deposits. This evidence of a long-lived hydrothermal system indicates susceptibility to mass failure and explosive events higher than expected for a volcano built largely by lava flows and

  12. 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.

  13. The WAIS Divide deep ice core WD2014 chronology - Part 2: Annual-layer counting (0-31 ka BP)

    NASA Astrophysics Data System (ADS)

    Sigl, M.; Fudge, T. J.; Winstrup, M.; Cole-Dai, J.; Ferris, D.; McConnell, J. R.; Taylor, K. C.; Welten, K. C.; Woodruff, T. E.; Adolphi, F.; Bisiaux, M.; Brook, E. J.; Buizert, C.; Caffee, M. W.; Dunbar, N. W.; Edwards, R.; Geng, L.; Iverson, N.; Koffman, B.; Layman, L.; Maselli, O. J.; McGwire, K.; Muscheler, R.; Nishiizumi, K.; Pasteris, D. R.; Rhodes, R. H.; Sowers, T. A.

    2015-07-01

    We present the WD2014 chronology for the upper part (0-2850 m, 31.2 ka BP) of the West Antarctic Ice Sheet (WAIS) Divide ice core. The chronology is based on counting of annual layers observed in the chemical, dust and electrical conductivity records. These layers are caused by seasonal changes in the source, transport, and deposition of aerosols. The measurements were interpreted manually and with the aid of two automated methods. We validated the chronology by comparing to two high-accuracy, absolutely dated chronologies. For the Holocene, the cosmogenic isotope records of 10Be from WAIS Divide and 14C for Intcal13 demonstrated WD2014 was consistently accurate to better than 0.5 % of the age. For the glacial period, comparisons to the Hulu Cave chronology demonstrated WD2014 had an accuracy of better than 1 % of the age at three abrupt climate change events between 27 and 31 ka. WD2014 has consistently younger ages than Greenland ice-core chronologies during most of the Holocene. For the Younger Dryas-Preboreal transition (11 546 ka BP, 24 years younger) and the Bølling-Allerød Warming (14 576 ka, 7 years younger) WD2014 ages are within the combined uncertainties of the timescales. Given its high accuracy, WD2014 can become a reference chronology for the Southern Hemisphere, with synchronization to other chronologies feasible using high quality proxies of volcanism, solar activity, atmospheric mineral dust, and atmospheric methane concentrations.

  14. Climate change at the 4.2 ka BP termination of the Indus valley civilization and Holocene south Asian monsoon variability

    NASA Astrophysics Data System (ADS)

    Staubwasser, M.; Sirocko, F.; Grootes, P. M.; Segl, M.

    2003-04-01

    Planktonic oxygen isotope ratios off the Indus delta reveal climate changes with a multi-centennial pacing during the last 6 ka, with the most prominent change recorded at 4.2 ka BP. Opposing isotopic trends across the northern Arabian Sea surface at that time indicate a reduction in Indus river discharge and suggest that later cycles also reflect variations in total annual rainfall over south Asia. The 4.2 ka event is coherent with the termination of urban Harappan civilization in the Indus valley. Thus, drought may have initiated southeastward habitat tracking within the Harappan cultural domain. The late Holocene drought cycles following the 4.2 ka BP event vary between 200 and 800 years and are coherent with the evolution of cosmogenic 14C production rates. This suggests that solar variability is one fundamental cause behind Holocene rainfall changes over south Asia.

  15. Lake-size variations in the Lahontan and Bonneville basins between 13,000 and 9000 14C yr B.P

    USGS Publications Warehouse

    Benson, L.; Currey, D.; Lao, Y.; Hostetler, S.

    1992-01-01

    Recessions of Lakes Lahontan and Bonneville that commenced ???13,500 14C yr B.P. were interrupted at {slanted equal to or greater-than}11,500 14C yr B.P. in the Lahontan basin and ???12,200 14C yr B.P. in the Bonneville basin by relatively large perturbations in lake level that persisted for ??? 2000 years. Minor glacial readvances in the Sierra Nevada and White Mountains of California-Nevada occurred during the latter half of this interval (between 11,000 and 9700 14C yr B.P.). The hydrologic response of Lakes Lahontan and Bonneville and the mountain glacial advances were concurrent with the Aller??d/Younger Dryas climatic intervals recorded in vegetational and glacial records of western and central Europe. ?? 1992.

  16. The evolution of a tropical rainforest/grassland mosaic in southeastern Brazil since 28,000 14C yr BP based on carbon isotopes and pollen records

    NASA Astrophysics Data System (ADS)

    Ruiz Pessenda, Luiz Carlos; De Oliveira, Paulo Eduardo; Mofatto, Milene; de Medeiros, Vanda Brito; Francischetti Garcia, Ricardo José; Aravena, Ramon; Bendassoli, José Albertino; Zuniga Leite, Acácio; Saad, Antonio Roberto; Lincoln Etchebehere, Mario

    2009-05-01

    The lack of paleoecological records from the montane Atlantic Rainforest of coastal Brazil, a hotspot of biological diversity, has been a major obstacle to our understanding of the vegetational changes since the last glacial cycle. We present carbon isotope and pollen records to assess the impact of the glaciation on the native vegetation of the Serra do Mar rainforest in São Paulo, Brazil. From ca. 28,000 to ˜ 22,000 14C yr BP, a subtropical forest with conifer trees is indicative of cool and humid conditions. In agreement carbon isotopic data on soil organic matter suggest the presence of C 3 plants and perhaps C 4 plants from ˜ 28,000 to ˜ 19,000 14C yr BP. The significant increase in the sedimentation rate and algal spores from ˜ 19,450 to ˜ 19,000 14C yr BP indicates increasing humidity, associated to an erosion process between ˜ 19,000 and ˜ 15,600 14C yr BP. From ˜ 15,600 14C yr BP to present there is a substantial increase in arboreal elements and herbs, indicating more humid and warmer climate. From ˜ 19,000 to ˜ 1000 14C yr BP, δ 13C values indicated the predominance of C 3 plants. These results are in agreement with studies in speleothems of caves, which suggest humid conditions during the last glacial maximum.

  17. A 22,000 14C year BP sediment and pollen record of climate change from Laguna Miscanti (23°S), northern Chile

    NASA Astrophysics Data System (ADS)

    Grosjean, M.; van Leeuwen, J. F. N.; van der Knaap, W. O.; Geyh, M. A.; Ammann, B.; Tanner, W.; Messerli, B.; Núñez, L. A.; Valero-Garcés, B. L.; Veit, H.

    2001-02-01

    Lake sediments and pollen, spores and algae from the high-elevation endorheic Laguna Miscanti (22°45'S, 67°45'W, 4140 m a.s.l., 13.5 km 2 water surface, 10 m deep) in the Atacama Desert of northern Chile provide information about abrupt and high amplitude changes in effective moisture. Although the lack of terrestrial organic macrofossils and the presence of a significant 14C reservoir effect make radiocarbon dating of lake sediments very difficult, we propose the following palaeoenvironmental history. An initial shallow freshwater lake (ca. 22,000 14C years BP) disappeared during the extremely dry conditions of the Last Glacial Maximum (LGM; 18,000 14C years BP). That section is devoid of pollen. The late-glacial lake transgression started around 12,000 14C years BP, peaked in two phases between ca. 11,000 and <9000 14C years BP, and terminated around 8000 14C years BP. Effective moisture increased more than three times compared to modern conditions (˜200 mm precipitation), and a relatively dense terrestrial vegetation was established. Very shallow hypersaline lacustrine conditions prevailed during the mid-Holocene until ca. 3600 14C years BP. However, numerous drying and wetting cycles suggest frequent changes in moisture, maybe even individual storms during the mid-Holocene. After several humid spells, modern conditions were reached at ca. 3000 14C years BP. Comparison between limnogeological data and pollen of terrestrial plants suggest century-scale response lags. Relatively constant concentrations of long-distance transported pollen from lowlands east of the Andes suggest similar atmospheric circulation patterns (mainly tropical summer rainfall) throughout the entire period of time. These findings compare favorably with other regional paleoenvironmental data.

  18. The WAIS Divide deep ice core WD2014 chronology - Part 2: Annual-layer counting (0-31 ka BP)

    NASA Astrophysics Data System (ADS)

    Sigl, Michael; Fudge, Tyler J.; Winstrup, Mai; Cole-Dai, Jihong; Ferris, David; McConnell, Joseph R.; Taylor, Ken C.; Welten, Kees C.; Woodruff, Thomas E.; Adolphi, Florian; Bisiaux, Marion; Brook, Edward J.; Buizert, Christo; Caffee, Marc W.; Dunbar, Nelia W.; Edwards, Ross; Geng, Lei; Iverson, Nels; Koffman, Bess; Layman, Lawrence; Maselli, Olivia J.; McGwire, Kenneth; Muscheler, Raimund; Nishiizumi, Kunihiko; Pasteris, Daniel R.; Rhodes, Rachael H.; Sowers, Todd A.

    2016-03-01

    We present the WD2014 chronology for the upper part (0-2850 m; 31.2 ka BP) of the West Antarctic Ice Sheet (WAIS) Divide (WD) ice core. The chronology is based on counting of annual layers observed in the chemical, dust and electrical conductivity records. These layers are caused by seasonal changes in the source, transport, and deposition of aerosols. The measurements were interpreted manually and with the aid of two automated methods. We validated the chronology by comparing to two high-accuracy, absolutely dated chronologies. For the Holocene, the cosmogenic isotope records of 10Be from WAIS Divide and 14C for IntCal13 demonstrated that WD2014 was consistently accurate to better than 0.5 % of the age. For the glacial period, comparisons to the Hulu Cave chronology demonstrated that WD2014 had an accuracy of better than 1 % of the age at three abrupt climate change events between 27 and 31 ka. WD2014 has consistently younger ages than Greenland ice core chronologies during most of the Holocene. For the Younger Dryas-Preboreal transition (11.595 ka; 24 years younger) and the Bølling-Allerød Warming (14.621 ka; 7 years younger), WD2014 ages are within the combined uncertainties of the timescales. Given its high accuracy, WD2014 can become a reference chronology for the Southern Hemisphere, with synchronization to other chronologies feasible using high-quality proxies of volcanism, solar activity, atmospheric mineral dust, and atmospheric methane concentrations.

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

    NASA Astrophysics Data System (ADS)

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

    2003-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  1. Changes in the Bathymetry and Volume of Glacial Lake Agassiz Between 11,000 and 9300 14C yr B.P.

    NASA Astrophysics Data System (ADS)

    Leverington, David W.; Mann, Jason D.; Teller, James T.

    2000-09-01

    The volume and surface area of glacial Lake Agassiz varied considerably during its 4000-year history. Computer models for seven stages of Lake Agassiz were used to quantify these variations over the lake's early history, between about 11,000 and 9300 14C yr B.P. (ca. 13,000 to 10,300 cal yr B.P.). Just after formation of the Herman strandlines (ca. 11,000 14C yr B.P.), the volume of Lake Agassiz appears to have decreased by >85% as a consequence of the abrupt rerouting of overflow to its eastern outlet from its southward routing into the Mississippi River basin. This drainage released about 9500 km3 of water into the North Atlantic Ocean via the Great Lakes and Gulf of St. Lawrence. Following closure of this eastern routing of overflow, the lake reached its maximum size at about 9400 14C yr B.P. with an area of >260,000 km2 and a volume of >22,700 km3. A second major reduction in volume occurred shortly after that, when its volume decreased >10% following the opening of the Kaiashk outlet to the east into the Great Lakes, and 2500-7000 km3 of water was released into the North Atlantic Ocean. These discharges may have affected ocean circulation and North Atlantic Deep Water production.

  2. 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.

  3. 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

  4. Nejapa Tephra: The youngest (c. 1 ka BP) highly explosive hydroclastic eruption in western Managua (Nicaragua)

    NASA Astrophysics Data System (ADS)

    Rausch, Juanita; Schmincke, Hans-Ulrich

    2010-05-01

    Nejapa Maar (2.5 × 1.4 km, c. 120 m deep), the largest maar along the 15-km-long Holocene Nejapa-Miraflores Lineament (NML), is the source vent of the youngest relatively widespread basaltic tholeiitic tephra blanket (Nejapa Tephra: NT) in western central Nicaragua, as shown by isopachs and isopleths (Rausch and Schmincke, 2008). The NT covers an area of > 10 km 2 in W/NW Managua. The minimum total magma volume erupted is estimated as 0.09 km 3. Juvenile, dominantly slightly vesicular (20-40 vol.%) basically tachylitic cauliflower-shaped lapilli with an average density of 2.1 g/cm 3, make up > 90 vol.% of the deposit, while lithoclasts comprise < 10 vol.% except proximally. This, the paucity of fine-grained tuffs and the dominant plane-parallel bedding all suggest fragmentation by shallow interaction of a rising magma starting to vesiculate and fragment pyroclastically with external water. The complex particles so generated erupted in moderately high eruption columns (at least 7-10 km) and were dominantly deposited as dry to damp, warm to cool fallout. Minor surge transport is inferred from fine-grained, locally cross-bedded tephra beds chiefly north of Nejapa and just west of Asososca Maars. Synvolcanic faulting along the NML is inferred. Faults in the study area indicate that activation of the N-S-trending Nejapa-Miraflores Fault (NMF), representing the western flank of Managua Graben, preceded deposition of NT and underlying Masaya Tuff (c.1.8 ka BP), Chiltepe Pumice (c. 1.9 ka BP) and Masaya Triple Layer (2.1 ka BP). The NT deposit is underlain regionally by a paleosol and topped by a soil. The basal paleosol contains pottery sherds made by the Usulután negative technique during the Late Formative period (700 BCE-300 CE) (2.7-1.7 ka BP). The soil overlying NT contains pottery related to the Ometepe technique dated as between 1350 and 1550 CE (650-450 a BP). These, and the radiocarbon dates of the pottery-bearing paleosols (1245 ± 125 and 535 ± 110 a BP

  5. 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.

  6. Beringian Megafaunal Extinctions at ~37 ka B.P.: Do Micrometeorites Embedded in Fossil Tusks and Skulls Indicate an Extraterrestial Precursor to the Younger Dryas Event?

    NASA Astrophysics Data System (ADS)

    Hagstrum, J. T.; Firestone, R. B.; West, A.

    2009-12-01

    Studies of Late Pleistocene megafaunal fossils and their ancient DNA from Beringia (eastern Siberia, Alaska, and the emerged Bering Strait) indicate sharp declines in steppe bison population diversity and horse body size, extinction of the Alaskan wild ass, and local extinctions of brown bear and woolly mammoth genetic lines beginning at about 37 ka B.P. Beringia is also well known for its remarkably preserved Late Pleistocene frozen animal mummies. 14C ages of these mummies are bimodally distributed, having peaks coincident with the earlier ~37 ka B.P., and ~13 ka B.P. Younger Dryas, onset extinction events. Associated with the ~37 ka B.P. event are, for example, the Berezovka mammoth, headless Selerikan horse, steppe bison “Blue Babe”, and baby mammoths “Dima” and “Lyuba”. Analyses of these and other mummies indicate that they died instantly, in mostly healthy condition, with gut contents and high fat reserves indicative of a late summer to autumn season. An assortment of uneaten limbs and other body parts from a variety of species have also been found. Uniformitarian death scenarios inadequately account for the lack of evidence of normal predation and scavenging. Extensive internal injuries (e.g. large bone fractures, hemorrhaging) and apparent rapid burial of the mummies also indicate that something truly unusual happened at the time of these extinction events. We have discovered what appear to be micrometeorites embedded in seven Alaskan mammoth tusks and a Siberian bison skull acquired from commercial sources. 14C ages for five of these fossils have a weighted mean age of 33 ± 2 ka B.P. Laser ablation ICP-MS and XRF analyses of the particles indicate high Fe contents with compositions enriched in Ni and depleted in Ti, similar to Fe meteorites and unlike any natural terrestrial sources. Microprobe analyses of a Fe-Ni sulfide grain from tusk 2 also show that it contains between 3 and 20 weight percent Ni. SEM images and XRF analyses of a bison

  7. Abrupt climate change around 4 ka BP: Role of the Thermohaline circulation as indicated by a GCM experiment

    NASA Astrophysics Data System (ADS)

    Wang, Shaowu; Zhou, Tianjun; Cai, Jingning; Zhu, Jinhong; Xie, Zhihui; Gong, Daoyi

    2004-04-01

    A great deal of palaeoenvironmental and palaeoclimatic evidence suggests that a predominant temperature drop and an aridification occurred at ca. 4.0 ka BP. Palaeoclimate studies in China support this dedution. The collapse of ancient civilizations at ca. 4.0 ka BP in the Nile Valley and Mesopotamia has been attributed to climate-induced aridification. A widespread alternation of the ancient cultures was also found in China at ca. 4.0 ka BP in concert with the collapse of the civilizations in the Old World. Palaeoclimatic studies indicate that the abrupt climate change at 4.0 ka BP is one of the realizations of the cold phase in millennial scale climate oscillations, which may be related to the modulation of the Thermohaline Circulation (THC) over the Atlantic Ocean. Therefore, this study conducts a numerical experiment of a GCM with SST forcing to simulate the impact of the weakening of the THC. Results show a drop in temperature from North Europe, the northern middle East Asia, and northern East Asia and a significant reduction of precipitation in East Africa, the Middle East, the Indian Peninsula, and the Yellow River Valley. This seems to support the idea that coldness and aridification at ca. 4.0 ka BP was caused by the weakening of the THC.

  8. Quantification of southwest China rainfall during the 8.2 ka BP event with response to North Atlantic cooling

    NASA Astrophysics Data System (ADS)

    Liu, Yuhui; Hu, Chaoyong

    2016-07-01

    The 8.2 ka BP event could provide important information for predicting abrupt climate change in the future. Although published records show that the East Asian monsoon area responded to the 8.2 ka BP event, there is no high-resolution quantitative reconstructed climate record in this area. In this study, a reconstructed 10-year moving average annual rainfall record in southwest China during the 8.2 ka BP event is presented by comparing two high-resolution stalagmite δ18O records from Dongge cave and Heshang cave. This decade-scale rainfall reconstruction is based on a central-scale model and is confirmed by inter-annual monitoring records, which show a significant positive correlation between the regional mean annual rainfall and the drip water annual average δ18O difference from two caves along the same monsoon moisture transport pathway from May 2011 to April 2014. Similar trends between the reconstructed rainfall and the stalagmite Mg / Ca record, another proxy of rainfall, during the 8.2 ka BP period further increase the confidence of the quantification of the rainfall record. The reconstructed record shows that the mean annual rainfall in southwest China during the central 8.2 ka BP event is less than that of present (1950-1990) by ˜ 200 mm and decreased by ˜ 350 mm in ˜ 70 years experiencing an extreme drying period lasting for ˜ 50 years. Comparison of the reconstructed rainfall record in southwest China with Greenland ice core δ18O and δ15N records suggests that the reduced rainfall in southwest China during the 8.2 ka BP period was coupled with Greenland cooling with a possible response rate of 110 ± 30 mm °C-1.

  9. 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

  10. Stratigraphic reconstruction of the 13 ka BP debris avalanche deposit at Colima volcano (Mexico): effect of climatic conditions on the flow mobility

    NASA Astrophysics Data System (ADS)

    Roverato, M.; Capra, L.

    2010-12-01

    Colima volcano is an andesitic stratovolcano located in the western part of the Trans-Mexican Volcanic Belt (TMVB) and at the southern end of the N-S trending Colima graben, about 70 km from the Pacific Ocean coast. It is probably the most active Mexican volcano in historic time and one of the most active of North America. Colima volcano yielded numerous partial edifice collapses with emplacement of debris avalanche deposits (DADs) of contrasting volume, morphology, texture and origin. This work has the aim to provide the evidences of how the climatic condition during the 13 ka flank collapse of the Colima volcano affected the textural characteristic and the mobility of the debris avalanche and debris flow originated from this event that occurred just after the Last Glacial Maximum in Mexico (18.4-14.5 ka 14C BP with snow line at 3600 m a.s.l. up to 13 ka BP). The 13,000 yrs old debris avalanche deposit, here named Tonila (TDAD) presents the typical debris avalanche textural characteristics (angular to sub-angular clasts, coarse matrix, jigsaw fit) but at approximately 13 km from the source, the deposit transforms to an hybrid phase with debris avalanche fragments imbedded in a finer, homogenous and indurated matrix more similar to a debris flow deposit. The debris avalanche deposit is directly overly by debris flows, often more than 10 m thick that contains large amount of logs from pine tree, mostly accumulated toward the base and imbricated down flow. Fluvial deposits also occur throughout all successions, representing periods of stream and river reworking highly localized and re-establishment. All these evidences point to the presence of water in the mass previous to the failure. The event here described represent an anomalous event between the previously described deposit associated to volcanic complex, and evidence as climatic condition can alter and modifies the depositional sequences incrementing the hazard.

  11. Orbital and millennial-scale environmental changes between 64 and 25 ka BP recorded in Black Sea sediments

    NASA Astrophysics Data System (ADS)

    Shumilovskikh, L. S.; Fleitmann, D.; Nowaczyk, N. R.; Behling, H.; Marret, F.; Wegwerth, A.; Arz, H. W.

    2013-09-01

    High-resolution pollen and dinoflagellate cyst records from marine sediment core 25-GC1 were used to reconstruct vegetation dynamics in Northern Anatolia and surface conditions of the Black Sea between 64 and 25 ka BP. During this period, the dominance of Artemisia in the pollen record indicates a steppe landscape and arid climate conditions. However, the presence of temperate and warm-temperate arboreal pollen suggests the existence of glacial refugia in Northern Anatolia. A general cooling trend towards 25 ka BP is evidenced by the decrease of Quercus and increase of Pinus. There is evidence of orbital-driven vegetation dynamics in Northern Anatolia during 64-25 ka BP with spread of steppe during precession minima (insolation maxima) and development of forests during precession maxima (insolation minima). Dansgaard-Oeschger (D-O) events are characterized by a marked increase in temperate tree pollen, indicating a spread of forests due to warm and wet conditions in Northern Anatolia. The dominance of Pyxidinopsis psilata and Spiniferites cruciformis in the dinocyst record indicates a rather brackish Black Sea during the last glacial period. The decrease of marine indicators (marine dinocysts, acritachs) at ~ 54 ka BP and increase of freshwater algae (Pediastrum, Botryococcus) from 32 to 25 ka BP reveals freshening of the Black Sea surface water, related to orbital-driven arid/humid phases in the region, influencing hydrology and level changes of the Black Sea. D-O interstadials are characterized by high dinocyst concentrations and calcium carbonate content, as a result of an increase in primary productivity in the Black Sea. Heinrich events show a similar impact on the environment in Northern Anatolia/Black Sea region as D-O stadials.

  12. Pelagic-benthic coupling within an upwelling system of the subtropical northeast Atlantic over the last 35 ka BP

    NASA Astrophysics Data System (ADS)

    McKay, C. L.; Filipsson, H. L.; Romero, O. E.; Stuut, J.-B. W.; Donner, B.

    2014-12-01

    We present a high resolution, multiproxy study of the relationship between pelagic and benthic environments of a coastal upwelling system in the subtropical NE Atlantic Ocean. Marine sediments corresponding to late MIS3 to the Holocene in the radiocarbon dated core GeoB7926, retrieved off Mauritania (21°N) were analysed to reconstruct productivity in surface waters and its linkage to deep waters during the last 35 ka BP. High latitude cold events and changes in atmospheric and oceanographic dynamics influenced upwelling intensity over this time period. Subsequently, this caused changes in primary productivity off this low-latitude coastal upwelling locality. The benthic foraminiferal fauna displays four main community shifts corresponding to fundamental climatic events, first of all during late MIS3 (35-28 ka BP), secondly from 28 to 19 ka BP (including Heinrich event 2 and the LGM), thirdly within Heinrich event 1, the Bølling Allerød and the Younger Dryas (18-11.5 ka BP) and finally during the Holocene (11.5-0 ka BP). In particular, strong pelagic-benthic coupling is apparent in MIS 3, as demonstrated by increased primary productivity, indicated by moderate DAR and the dominance of benthic foraminiferal species which prefer fresh phytodetritus. A decline in upwelling intensity and nutrient availability follows, which resulted in a proportionately larger amount of older, degraded matter, provoking a shift in the benthic foraminifera fauna composition. This rapid response of the benthic environment continues with a progressive increase in upwelling intensity due to sea level and oceanographic changes and according high surface production during the LGM. During Heinrich event 1 and the Younger Dryas, extreme levels of primary production actually hindered benthic environment through the development of low oxygen conditions. After this period, a final change in benthic foraminiferal community composition occurs which indicates a return to more oxygenated conditions

  13. Did the Toba volcanic eruption of ˜74 ka B.P. produce widespread glaciation?

    NASA Astrophysics Data System (ADS)

    Robock, Alan; Ammann, Caspar M.; Oman, Luke; Shindell, Drew; Levis, Samuel; Stenchikov, Georgiy

    2009-05-01

    It has been suggested that the Toba volcanic eruption, approximately 74 ka B.P., was responsible for the extended cooling period and ice sheet advance immediately following it, but previous climate model simulations, using 100 times the amount of aerosols produced by the 1991 Mount Pinatubo eruption, have been unable to produce such a prolonged climate response. Here we conduct six additional climate model simulations with two different climate models, the National Center for Atmospheric Research Community Climate System Model 3.0 (CCSM3.0) and National Aeronautics and Space Administration Goddard Institute for Space Studies ModelE, in two different versions, to investigate additional mechanisms that may have enhanced and extended the forcing and response from such a large supervolcanic eruption. With CCSM3.0 we include a dynamic vegetation model to explicitly calculate the feedback of vegetation death on surface fluxes in response to the large initial reduction in transmitted light, precipitation, and temperature. With ModelE we explicitly calculate the effects of an eruption on stratospheric water vapor and model stratospheric chemistry feedbacks that might delay the conversion of SO2 into sulfate aerosols and prolong the lifetime and radiative forcing of the stratospheric aerosol cloud. To span the uncertainty in the amount of stratospheric injection of SO2, with CCSM3.0 we used 100 times the Pinatubo injection, and with ModelE we used 33, 100, 300, and 900 times the Pinatubo injection without interactive chemistry, and 300 times Pinatubo with interactive chemistry. Starting from a roughly present-day seasonal cycle of insolation, CO2 concentration, and vegetation, or with 6 ka B.P. conditions for CCSM3.0, none of the runs initiates glaciation. The CCSM3.0 run produced a maximum global cooling of 10 K and ModelE runs produced 8-17 K of cooling within the first years of the simulation, depending on the injection, but in all cases, the climate recovers over a few

  14. 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

  15. Orbital- and millennial-scale environmental changes between 64 and 20 ka BP recorded in Black Sea sediments

    NASA Astrophysics Data System (ADS)

    Shumilovskikh, L. S.; Fleitmann, D.; Nowaczyk, N. R.; Behling, H.; Marret, F.; Wegwerth, A.; Arz, H. W.

    2014-05-01

    High-resolution pollen and dinoflagellate cyst records from sediment core M72/5-25-GC1 were used to reconstruct vegetation dynamics in northern Anatolia and surface conditions of the Black Sea between 64 and 20 ka BP. During this period, the dominance of Artemisia in the pollen record indicates a steppe landscape and arid climate conditions. However, the concomitant presence of temperate arboreal pollen suggests the existence of glacial refugia in northern Anatolia. Long-term glacial vegetation dynamics reveal two major arid phases ~64-55 and 40-32 ka BP, and two major humid phases ~54-45 and 28-20 ka BP, correlating with higher and lower summer insolation, respectively. Dansgaard-Oeschger (D-O) cycles are clearly indicated by the 25-GC1 pollen record. Greenland interstadials are characterized by a marked increase in temperate tree pollen, indicating a spread of forests due to warm/wet conditions in northern Anatolia, whereas Greenland stadials reveal cold and arid conditions as indicated by spread of xerophytic biomes. There is evidence for a phase lag of ~500 to 1500 yr between initial warming and forest expansion, possibly due to successive changes in atmospheric circulation in the North Atlantic sector. The dominance of Pyxidinopsis psilata and Spiniferites cruciformis in the dinocyst record indicates brackish Black Sea conditions during the entire glacial period. The decrease of marine indicators (marine dinocysts, acritarchs) at ~54 ka BP and increase of freshwater algae (Pediastrum, Botryococcus) from 32 to 25 ka BP reveals freshening of the Black Sea surface water. This freshening is possibly related to humid phases in the region, to connection between Caspian Sea and Black Sea, to seasonal freshening by floating ice, and/or to closer position of river mouths due to low sea level. In the southern Black Sea, Greenland interstadials are clearly indicated by high dinocyst concentrations and calcium carbonate content, as a result of an increase in primary

  16. Agriculture, Settlement, and Abrupt Climate Change: The 4.2ka BP event in Northern Mesopotamia

    NASA Astrophysics Data System (ADS)

    Ristvet, L.

    2003-12-01

    attendant villages. The survey records an 80% decline in settled hectares from the previous period. The only agricultural villages that remained occupied during this crisis were either concentrated along perennial wadis or located in areas with ample groundwater. Otherwise, the survey recorded the presence of a few temporary sites, probably camps belonging to semi-nomadic pastoralists, a lifestyle which may have begun in response to this event. The precipitation regime stabilized at approximately 1900 BC, allowing for a massive resettlement of the area. This resettlement did not, however, lead to a resumption of third millennium agricultural practices; instead, these villages embraced a flexible economic regime, which emphasized a reliance on pastoral as well as agricultural products, and as such, was well-adapted to the more marginal conditions of the early second millennium BC. This paper, therefore, attempts to quantify the effects of the 4.2 ka BP abrupt climate change event on ancient agricultural systems, settlement patterns, and societies through archaeological survey in northern Mesopotamia.

  17. Orbital and millennial-scale variability in the southernmost reaches of the South American summer monsoon during the last 50 ka BP

    NASA Astrophysics Data System (ADS)

    Chiessi, C. M.; Govin, A.; Mulitza, S.; Campos, M. D.

    2013-05-01

    The South American summer monsoon (SASM) and its related features (e.g., the South Atlantic Convergence Zone) deliver most of the precipitation for the Amazon and La Plata basins, the two largest drainage systems in South America. Marine, cave and lake records mainly from equatorial and tropical South America show that the strength of the SASM fluctuated on orbital and millennial time-scales, with a strong SASM during periods of high austral summer insolation. On millennial time-scales, precipitation in tropical South America to the south of the equator was increased during periods of a weak Atlantic meridional overturning circulation. Nevertheless, there is an almost complete lack of information about changes in precipitation in the subtropics and mid-latitudes of South America. This area comprises the transition from the southernmost reaches of the SASM to the semi-arid northern Patagonia, and is highly sensitive to changes in precipitation because: (i) it mainly receives precipitation during austral summer (related to the SASM); and (ii) it shows a steep gradient in total annual precipitation (going from ca. 1000 mm/yr around 30oS to ca. 200 mm/yr around 40oS). Here we present recently acquired data from the terrigenous fraction of marine sediment core GeoB6308-3 (39.30oS / 53.97oW / 3620 m water depth / 793 cm long) collected off southeastern South America. Our age model is based on 18 14C AMS ages while information about changes in continental climate comes from bulk sediment major element (i.e., Ca, Fe, Al, Si, Ti, K) proportions and Nd isotopes. The core recorded the last ca. 50 ka BP and its terrigenous sediment fraction shows a typical Central-West Argentinean / Patagonian isotopic signature. Through X-ray fluorescence scanning we were able to produce a record with mean temporal resolution of 35 yr. In our presentation, we will discuss changes in the southernmost reaches of the SASM and compare it to other records from South and Central America with the

  18. A Storegga age turbidite at Eirik Drift, South Greenland: evidence for synchronous turbidite deposition at 8.2 ka BP in the North Atlantic?

    NASA Astrophysics Data System (ADS)

    Watts, Millie; Taylor, Vicki; Talling, Peter; Hunt, James; Stanford, Jennifer

    2016-04-01

    Eirik Drift contains a high-resolution record of climatic and oceanic variability. In addition, it records several submarine landslides throughout the Holocene. Submarine landslides and associated tsunamis are potentially damaging, and have the potential to travel significant distances across the North Atlantic. Two cores taken from Eirik Drift (D298-P2) show an expanded Holocene section of hemipelagite and contain a fine grained turbidite dated to 8.17 ka BP (+/- 200 years). This event is coincident with both the 8.2 ka BP climatic anomaly, and the Storegga Slide. Paleoenvironmental proxies suggest this 8.2 ka BP turbidite was deposited during the coldest part of the 8.2 ka BP event, interpreted here as a longer duration cooling. This Holocene Storegga Slide triggered a major tsunami, evidence of which has been found across Northern European coastlines and the East Greenland coast. Here we show that the 8.2 ka BP turbidite has a different provenance both to other turbidites within the D298 core, and the main body of the Storegga Slide turbidite, and is unique within the Eirik Drift sequence. We interpret this event within the core as a distal deposit of a turbidite transported within the Western boundary Under Current, potentially related to a more northerly Greenland impact of the Storegga Tsunami. The fine-grained nature of the deposit suggests significant transport, supporting the hypothesis this event relates to a Greenland impact of the Storegga Tsunami.

  19. Oceanographic and climatic record for the last 18 ka cal BP in marine sediments from Pescadero Basin, Gulf of California

    NASA Astrophysics Data System (ADS)

    Escorza-Reyes, M.; Pérez-Cruz, L.; Urrutia-Fucugauchi, J.; Salas-de-León, D.

    2012-04-01

    In this study a marine sequence is analyzed in order to reconstruct the oceanographic and climatic conditions based on geochemical and magnetic data, in centennial to multi-decadal time scales during the past 18 ka in the southern Gulf of California. The gravity core DIPAL III-T2 was recovered in the eastern part of Pescadero Basin, at 577 m depth, in the Pacific Intermediate Water (PIW) and Oxygen Minimum Zone (OMZ), aboard the R/V "El Puma" of the National University of Mexico (UNAM). The core is 262 cm long. This core is characterized by clay sediments. It shows massive and homogeneous sediments from bottom to 200 cm, and from there to the top a well defined laminated structure. Light laminae exhibit high content of biogenic components (mainly diatoms, radiolarian and silicoflagellates remains), whereas dark laminae are formed mostly by terrigenous material. Age model is based on five AMS radiocarbon dating, calibrated applying the CALIB 6.1.0 radiocarbon program. The sedimentation rates estimated range from ~0.1 mm/yr to ~0.3 mm/yr (in the upper part); sedimentary sequence comprises approximately the past 18 ka cal BP. Samples were taken every cm and they were dried and grounded, and elemental chemical concentrations measured using an X-ray fluorescence analyzer (Niton XL3t GOLDD). For magnetic susceptibility, measurements were taken every 0.5 cm with a Bartington Susceptibilimeter with MS2B sensor. A sharp difference in concentrations of Fe, Ti, K, Si, Ca y V, also observed in magnetic susceptibility measurements, marks the transition between Holocene and Pleistocene epochs, suggesting deposition under different conditions of atmospheric and oceanic circulation. In particular, low Ti, Fe and K concentrations at ~ 8 ka cal BP, indicate a decrease in terrigenous input, indicating a decrease in rainfall and river discharges from mainland to the basin, suggesting dry and cold conditions. We propose that this signal correlate with the 8.2 ka cooling event, that

  20. Work More? The 8.2 kaBP Abrupt Climate Change Event and the Origins of Irrigation Agriculture and Surplus Agro-Production in Mesopotamia

    NASA Astrophysics Data System (ADS)

    Weiss, H.

    2003-12-01

    The West Asian archaeological record is of sufficient transparency and resolution to permit observation of the social responses to the major Holocene abrupt climate change events at 8.2, 5.2 and 4.2 kaBP. The 8.2kaBP abrupt climate change event in West Asia was a three hundred year aridification and cooling episode. During this period rain-fed agriculture, established for over a millennium in northern Mesopotamia, suddenly collapsed. Irrigation agriculture, pastoral nomadism, or migration were the only subsistence alternatives for populations previously supported by cereal dry-farming. Irrigation agriculture was not, however, possible along the northern alluvial plains of the Tigris and Euphrates Rivers, where incised riverbeds were several meters below plain level. Exploitable plain-level levees were only accessible in southern-most alluvial plain, at the head of the present-day Persian Gulf. The archaeological data from this region documents the first irrigation agriculture settlement of the plain during the 8.2 kaBP event. Irrigation agriculture provides about twice the yield of dry-farming in Mesopotamia, but at considerable labor costs relative to dry-farming. With irrigation agriculture surplus production was now available for deployment. But why work more? The 8.2 kaBP event provided the natural force for Mesopotamian irrigation agriculture and surplus production that were essential for the earliest class-formation and urban life.

  1. Paleotemperature reconstructions from speleothem fluid inclusions between 14 - 10 ka BP in Milandre cave (NW Switzerland)

    NASA Astrophysics Data System (ADS)

    Affolter, Stéphane; Häuselmann, Anamaria; Fleitmann, Dominik; Leuenberger, Markus

    2016-04-01

    In cave environments, speleothems constitute a well preserved and precisely dated continental climate archive that record past environmental changes such as paleotemperature or moisture source, namely through oxygen and hydrogen isotopes variations. Fluid inclusions are common in speleothems and they correspond to micrometric voids that often contain fossil liquid water representing past precipitation falling above the cave nearly at the time the inclusions were sealed. To measure the δD and δ18O isotopic composition of speleothem fluid inclusions, we extracted submicrolitre amounts of water from stalagmites (old and recent) coming from Milandre cave (Switzerland) using a new online method developed at the University of Bern (Affolter et al., 2014). The released water is then flushed directly to a Picarro L1102-i or L2140-i laser based instrument that allows to simultaneously monitor hydrogen and oxygen isotopes. At Milandre cave site, a two year isotope monitoring campaign has confirmed that isotopes in precipitation for northwestern Switzerland are principally controlled by air temperature (Affolter et al., 2015). Therefore, when combined with calcite δ18O, the fluid inclusion water isotopes can be used to calculate paleotemperatures. We reconstructed a cold season biased (roughly autumn - winter - spring) paleotemperature trend for the time interval covering the Allerød, the Younger Dryas cold interval and the early Holocene (13'900 - 9'900 BP). References: Affolter S., Fleitmann D., and Leuenberger M.: New online method for water isotope analysis of speleothem fluid inclusions using laser absorption spectroscopy (WS-CRDS), Clim. Past, 10, 1291-1304, doi:10.5194/cp-10-1291-2014, 2014. Affolter S., Häuselmann A.D., Fleitmann D., Häuselmann P., Leuenberger M.: Triple isotope (δD, δ17O, δ18O) study on precipitation, drip water and speleothem fluid inclusions for a Western Central European cave (NW Switzerland), Quat. Sci. Rev., 127, pp. 73-89, 2015.

  2. A critical evaluation of the 4.2 ka BP event using new high resolution evidence from stalagmites in the Middle East

    NASA Astrophysics Data System (ADS)

    Jones, Sarah; Fleitmann, Dominik; Black, Stuart

    2016-04-01

    The 4.2 ka BP event occurs during a period of rapid climate change (RCC), characterised by widespread aridity and has been used to explain the collapse of a number of Early Bronze Age societies in the Middle East. Although the 4.2 ka BP event has been recognised in a large number of palaeoenvironmental archives, the precise nature, chronology and extent remains controversial. This is mainly attributable to the paucity of precisely dated and highly resolved palaeoenvironmental records, which are essential when considering the nature of the 4.2 ka BP event which may have only persisted for several decades. The use of records with few dates and therefore poor chronologies means that synchronicity between events occurring during the RCC period (between 4.2 and 3.8 ka BP) and the nature and extent of climatic events are difficult to resolve. Therefore, high resolution records with precise and accurate chronologies are imperative to reduce the uncertainties when attempting to identify distinct events in palaeoclimatic records. Terrestrial carbonates, including speleothems, are able to be accurately and absolutely dated utilising U-series methods and, using different analyses, can be investigated for isotopic and elemental markers. This combination is essential for elucidating the precise nature, timing and extent of the 4.2 ka BP event. This research presents several highly resolved and well dated speleothem records from Sofular and Ovacik caves in northwestern Turkey and Qunf Cave in Oman, to investigate the exact timing, duration and magnitude of the 4.2 ka BP event in unprecedented detail. These sequences currently have 19 U-Th dates covering a 1000 year period, combined with stable isotope analyses at resolutions of ~0.8, ~2.5 and ~4 years respectively. Initial results from the high resolution Sofular record identify 3 excursions greater than two standard deviations from the mean, indicating rapid climatic change, but these are all associated with increased

  3. Tephrostratigraphy of the last 170 ka in sedimentary successions from the Adriatic Sea

    NASA Astrophysics Data System (ADS)

    Calanchi, Natale; Dinelli, Enrico

    2008-10-01

    In this study are discussed new SEM-EDS analyses performed on glass shards from five cores collected in the Central Adriatic Sea and two cores recovered from the South Adriatic Sea. A total of 26 tephra layers have been characterized and compared with the geochemical features of terrestrial deposits and other tephra archives in the area (South Adriatic Sea and Lago Grande di Monticchio, Vulture volcano). The compositions are compatible with either a Campanian or a Roman provenance. The cores, located on the Central Adriatic inner and outer shelf, recorded tephra referred to explosive events described in the literature: AP3 (sub-Plinian activity of the Somma-Vesuvius, 2710 ± 60 14C years BP); Avellino eruption (Somma-Vesuvius, 3548 ± 129 14C years BP); Agnano Monte Spina (Phlegrean Fields, 4100 ± 400 years BP); Mercato eruption (Somma-Vesuvius, 8010 ± 35 14C years BP; Agnano Pomici Principali eruption (Phlegrean Fields, 10,320 ± 50 14C years BP); Neapolitan Yellow Tuff (Phlegrean Fields, 12,100 ± 170 14C years BP). Some of these layers were also observed in the South Adriatic core IN68-9 in addition to younger ( AP2, sub-Plinian eruption, Somma-Vesuvius, 3225 ± 140 14C years BP), and older layers ( Pomici di Base eruption, Somma-Vesuvius, 18,300 ± 150 14C years BP). Significant is the tephra record of core RF95-7 that, for the first time in the Adriatic Sea, reports the occurrence of tephra layers older than 60 ka: the well known Mediterranean tephra layers X2 (ca. 70 ka), W1 (ca. 140 ka) and V2 (Roman origin, ca. 170 ka) as well as other tephra layers attributed, on the basis of geochemistry and biostratigraphy, to explosive eruptions occurred at Vico (138 ± 2 and 151 ± 3 ka BP) and Ischia (147-140 ka BP). Previous tephra correlations performed on other cores in the Central Adriatic Sea were also critically revised according to new available data, and integrated with the results of this study for a correlation at a regional scale. The most important key

  4. Surface nitrate utilization in the Bering sea since 180 kA BP: Insight from sedimentary nitrogen isotopes

    NASA Astrophysics Data System (ADS)

    Riethdorf, Jan-Rainer; Thibodeau, Benoit; Ikehara, Minoru; Nürnberg, Dirk; Max, Lars; Tiedemann, Ralf; Yokoyama, Yusuke

    2016-03-01

    We present high-resolution records of sedimentary nitrogen (δ15Nbulk) and carbon isotope ratios (δ13Cbulk) from piston core SO201-2-85KL located in the western Bering Sea. The records reflect changes in surface nitrate utilization and terrestrial organic matter contribution in submillennial resolution that span the last 180 kyr. The δ15Nbulk record is characterized by a minimum during the penultimate interglacial indicating low nitrate utilization (~62-80%) despite the relatively high export production inferred from opal concentrations along with a significant reduction in the terrestrial organic matter fraction (mterr). This suggests that the consumption of the nitrate pool at our site was incomplete and even more reduced than today (~84%). δ15Nbulk increases from Marine Isotope Stage (MIS) 5.4 and culminates during the Last Glacial Maximum, which indicates that nitrate utilization in the Bering Sea was raised during cold intervals (MIS 5.4, 5.2, 4) and almost complete during MIS 3 and 2 (~93-100%). This is in agreement with previous hypotheses suggesting that stronger glacial stratification reduced the nutrient supply from the subeuphotic zone, thereby increasing the iron-to-nutrient ratio and therefore the nitrate utilization in the mixed surface layer. Large variations in δ15Nbulk were also recorded from 180 to 130 ka BP (MIS 6), indicating a potential link to insolation and sea-level forcing and its related feedbacks. Millennial-scale oscillations were observed in δ15Nbulk and δ13Cbulk that might be related to Greenland interstadials.

  5. Glacial to paraglacial history and forest recovery in the Oglio glacier system (Italian Alps) between 26 and 15 ka cal BP

    NASA Astrophysics Data System (ADS)

    Ravazzi, Cesare; Badino, Federica; Marsetti, Diego; Patera, Glauco; Reimer, Paula J.

    2012-12-01

    The integrated stratigraphic, radiocarbon and palynological record from an end-moraine system of the Oglio valley glacier (Italian Alps), propagating a lobe upstream in a lateral reach, provided evidence for a complete cycle of glacial advance, culmination and withdrawal during the Last Glacial Maximum and early Lateglacial. The glacier culminated in the end moraine shortly after 25.8 ± 0.8 ka cal BP, and cleared the valley floor 18.3-17.2 ± 0.3 ka cal BP. A primary paraglacial phase is then recorded by fast progradation of the valley floor. As early as 16.7 ± 0.3 ka cal BP, early stabilization of alluvial fans and lake filling promoted expansion of cembran pine. This is an unprecedented evidence of direct tree response to depletion of paraglacial activity during the early Lateglacial, and also documents the cembran pine survival in the mountain belt of the Italian Alps during the last glaciation. Between 16.1 and 14.6 ± 0.5 ka cal BP, debris cones emplacement points to a moisture increase favouring tree Betula and Pinus sylvestris-mugo. A climate perturbation renewed paraglacial activity. According to cosmogenic ages on glacial deposits and AMS radiocarbon ages from lake records in South-Eastern Alps such phase compares favourably with the Gschnitz stadial and with the oscillations recorded at lakes Ragogna, Längsee and Jeserzersee, most probably forced by the latest freshening phases of the Heinrich Event 1. A further sharp pine rise marks the subsequent onset of Bølling interstadial. The chronology of the Oglio glacier compares closely with major piedmont glaciers on the Central and Eastern Alpine forelands. On the other hand, the results of the present study imply a chronostratigraphic re-assessment of the recent geological mapping of the Central Italian Alps.

  6. Oceanographic and climatic record of the last 47 ka B.P in marine sediments from the Gulf of Tehuantepec

    NASA Astrophysics Data System (ADS)

    Pavon-Moreno, J. A.; Perez-Cruz, L. L.; Fucugauchi, J. U.

    2013-05-01

    The aim of this study is reconstruct the paleoceanographic and paleoclimatic conditions in the northern Gulf of Tehuantepec, through the use of geochemical and magnetic proxies. The sediment core MD02-2523 was collected using a giant piston corer during the oceanographic campaign MD126 (IMAGES VIII - MONA) in the Gulf of Tehuantepec, on June 2002 aboard the R/V "Marion Dufresne". The core was collected at 202 m depth and it has an 18.19 m length; for this study we only use the first 700 cm. Age control is established with AMS radiocarbon dating on six samples, providing an age control for the core from 900 to 47,000 cal yr BP. Sediments in the core are composed mostly of silty clays, with some horizons containing fossil fragments presented as disarticulated bivalve shells with average sizes of 1 cm, as well as foraminifera and nannofossils. We observe a cream to white ash layer, with a thick of 2 cm. Mineral magnetic and XRF analyses were carried out along the core. For mineral magnetic analyses, standard 2.2 × 2.2 × 2.2 cm samples were taken throughout the core split. The low-field magnetic susceptibility was measured in all samples at low and high frequencies (0.465 kHz and 4.65 kHz) with the MS2 Bartington susceptibility instrument equipped with the MS2B dual-frequency sensor. For the geochemical study, samples were taken every 2 cm and elemental chemical concentration was measured using an X-ray fluorescence analyzer (Niton XL3t GOLDD). Few laminated intervals show a strong correlation between Mo and V, indicating less oxygenated conditions in the water column. Ti and Fe are used as proxies of terrigenous input. Changes in sedimentation rates are observed and could be associated to sea level fluctuations in the Gulf of Tehuantepec. Magnetic susceptibility shows a cyclic pattern with peaks along the core showing apparent increases in the amount of magnetic minerals. The peaks could be associated to (about 20 ka) precession cycles. According to the geochemical

  7. The latest explosive eruptions of Ciomadul (Csomád) volcano, East Carpathians - A tephrostratigraphic approach for the 51-29 ka BP time interval

    NASA Astrophysics Data System (ADS)

    Karátson, D.; Wulf, S.; Veres, D.; Magyari, E. K.; Gertisser, R.; Timar-Gabor, A.; Novothny, Á.; Telbisz, T.; Szalai, Z.; Anechitei-Deacu, V.; Appelt, O.; Bormann, M.; Jánosi, Cs.; Hubay, K.; Schäbitz, F.

    2016-06-01

    The most recent, mainly explosive eruptions of Ciomadul, the youngest volcano in the Carpatho-Pannonian Region, have been constrained by detailed field volcanological studies, major element pumice glass geochemistry, luminescence and radiocarbon dating, and a critical evaluation of available geochronological data. These investigations were complemented by the first tephrostratigraphic studies of the lacustrine infill of Ciomadul's twin craters (St. Ana and Mohoş) that received tephra deposition during the last eruptions of the volcano. Our analysis shows that significant explosive activity, collectively called EPPA (Early Phreatomagmatic and Plinian Activity), started at Ciomadul in or around the present-day Mohoş, the older crater, at ≥ 51 ka BP. These eruptions resulted in a thick succession of pyroclastic-fall deposits found in both proximal and medial/distal localities around the volcano, characterized by highly silicic (rhyolitic) glass chemical compositions (ca. 75.2-79.8 wt.% SiO2). The EPPA stage was terminated by a subplinian/plinian eruption at ≥ 43 ka BP, producing pumiceous pyroclastic-fall and -flow deposits of similar glass composition, probably from a "Proto-St. Ana" vent located at or around the younger crater hosting the present-day Lake St. Ana. After a quiescent period with a proposed lava dome growth in the St. Ana crater, a new explosive stage began, defined as MPA (Middle Plinian Activity). In particular, a significant two-phase eruption occurred at ~ 31.5 ka BP, producing pyroclastic flows from vulcanian explosions disrupting the preexisting lava dome of Sf. Ana, and followed by pumiceous fallout from a plinian eruption column. Related pyroclastic deposits show a characteristic, less evolved rhyolitic glass composition (ca. 70.2-74.5 wt.% SiO2) and occur both in proximal and medial/distal localities up to 21 km from source. The MPA eruptions, that may have pre-shaped a crater similar to, but possibly smaller than, the present-day St

  8. Cosmogenic 36Cl exposure ages reveal a 9.3 ka BP glacier advance and the Late Weichselian-Early Holocene glacial history of the Drangajökull region, northwest Iceland

    NASA Astrophysics Data System (ADS)

    Brynjólfsson, Skafti; Schomacker, Anders; Ingólfsson, Ólafur; Keiding, Jakob K.

    2015-10-01

    We present twenty-four new cosmogenic isotope (36Cl) surface exposure ages from erratic boulders, moraine boulders and glacially eroded bedrock that constrain the late Weichselian to Holocene glacial history of the Drangajökull region, northwest Iceland. The results suggest a topographically controlled ice sheet over the Vestfirðir (Westfjords) peninsula during the last glaciation. Cold based non-erosive sectors of the ice sheet covered most of the mountains while fjords and valleys were occupied with erosive, warm-based ice. Old36Cl exposure ages from highlands and mountain plateaux (L8; 76.5 ka and H1; 41.6 ka) in combination with younger erratic boulders (L7; 26.2 and K1-K4; 15.0-13.8 ka) superimposed on such surfaces suggest the presence of non-erosive ice over uplands and plateaux in the Vestfirðir peninsula during the last glaciation. Glacially scoured terrain and erratic boulders yielding younger exposure ages (L1-L6; 11.3-9.1 ka and R1, R6-R7; 10.6-9.4 ka) in the lowland areas indicate that the valleys and fjords of the Vestfirðir peninsula were occupied by warm-based, dynamic ice during the last glaciation. The deglaciation of mountain Leirufjall by 26.2 ka BP suggests that ice thinning and deglaciation of some mountains and plateaux preceded any significant lateral retreat of the ice sheet. Subsequently this initial ice thinning was followed by break-up of the shelf based ice sheet off Vestfirðir about 15 ka BP. Hence, the new exposure ages suggest a stepwise asynchronous deglaciation on land, following the shelf break-up with some valleys and most of the highlands, ice free by 14-15 ka BP. The outermost moraine at the mouth of Leirufjörður is dated to 9.3 ka BP, and we suggest the moraine to be formed by a glacier re-advance in response to a cooler climate forced by the reduced Atlantic Meridional Overturning Circulation at around 9.3 ka BP. A system of moraines proximal to the 9.3 ka moraine in Leirufjörður as well as a 9.4 ka deglaciation age

  9. Ostracods and sediment geochemistry as indicators of hydrologic and climatic variability in the central part of the Mexican Chihuahuan Desert over the last 27 ka cal BP

    NASA Astrophysics Data System (ADS)

    Chávez Lara, C. M.; Roy, P. D.; Lozano Santa Cruz, R.; López Balbiaux, N.

    2013-12-01

    The paleolake Santiaguillo (Durango State) is located in the central part of the Chihuahuan Desert (Mexico). The lacustrine basin covers an area of approximately 1,964 km2 and is surrounded by mountains up to ca. 2,700 masl. This basin was formed by tectonic processes and the basement is formed by volcanic felsic rocks of Tertiary age. Four sediment cores were obtained from central and western part of the basin to reconstruct hydrologic and climate variability during the late Pleistocene and Holocene. In this work, we present paleo-ecology of ostracods and sedimentary geochemistry from two sediment cores (300 cm and 200 cm long) collected from the western basin margin. The age model was constructed from 8 AMS radiocarbon dates and the longest profile represents the last 27 cal ka BP. The ostracode faunal content consists of 4 different species: Limnocythere bradburyi, Cadona patzcuaro, Cypridopsis vidua and Limnocythere ceriotuberosa (listed from highest to lowest abundance) and total abundance varies between 0 and 125 valves/g. Paleo-environmental conditions were reconstructed from the Total Organic Carbon (TOC), Total Inorganic Carbon (TIC), Carbon/Nitrogen ratios (C/N), Chemical Index of Alteration (CIA) and concentrations of Ti, Ca, Si and Al. The results were divided into two zones for interpretation. Zone 1 covers ca. 27-17 cal ka BP (300-191 cm) and is characterized by higher Ti concentrations and above average CIA values. This suggests greater interaction between water and sediment, lower evaporation and relatively higher lake level in the basin. During this interval of higher lakestand, the deposited organic matter was autochthonous (lacustrine origin) and ostracodes suggest presence of a warm and dilute water column (>13 °C and >100 ppm). Sediments of the last 17 cal ka BP (191-0 cm) (Zone 2) are characterized by below average water-sediment interaction, higher carbonate precipitation and deposition of allochthonous organic matter (terrestrial origin

  10. Decadal-scale Climate Variability on the Central Iranian Plateau Spanning the So-called 4.2 ka BP Drought Event

    NASA Astrophysics Data System (ADS)

    Carolin, S.; Walker, R. T.; Henderson, G. M.; Maxfield, L.; Ersek, V.; Sloan, A.; Talebian, M.; Fattahi, M.; Nezamdoust, J.

    2015-12-01

    The influence of climate on the growth and development of ancient civilizations throughout the Holocene remains a topic of heated debate. The 4.2 ka BP global-scale mid-to-low latitude aridification event (Walker et al., 2012) in particular has incited various correlation proposals. Some authors suggest that this event may have led to the collapse of the Akkadian empire in Mesopotamia, one of the first empires in human history, as well as to changes among other Early Bronze Age societies dependent on cereal agriculture (eg. Staubwasser and Weiss, 2006). Other authors remain doubtful of the impact of environmental factors on the collapse of past societies (eg. Middleton, 2012). While coincident timing of an environmental event with archeological evidence does not necessitate a causation, a comprehensive understanding of climate variability in the ancient Near East is nonetheless an essential component to resolving the full history of early human settlements. Paleoclimate data on the Central Iranian Plateau, a region rich with ancient history, is exceptionally sparse compared to other areas. Many karst locations are found throughout the region, however, setting the stage for the development of several high-resolution, accurate and precisely-dated climate proxy records if a correlation between the chemistry of semi-arid speleothem samples and climate is resolved. Here we present a 5.1-3.7 ka BP record of decadal-scale stalagmite stable isotope and trace metal variability. The stalagmite was collected in Gol-e zard cave (35.8oN, 52.0oE), ~100 km NE of Tehran on the southern flank of the Alborz mountain range (2530masl). The area currently receives ~270mm mean annual precipitation, with more than 90% of precipitation falling within the wet season (November-May). We use GNIP data from Tehran and local and regional meteorological data to resolve the large-scale mechanisms forcing isotopic variations in rainwater over Gol-e zard cave. We discuss possible transformation of

  11. Lake ecosystem dynamics and links to climate change inferred from a stable isotope and organic palaeorecord from a mountain lake in southwestern China (ca. 22.6-10.5 cal ka BP)

    NASA Astrophysics Data System (ADS)

    Cook, Charlotte G.; Leng, Melanie J.; Jones, Richard T.; Langdon, Peter G.; Zhang, Enlou

    2012-01-01

    A detailed understanding of long-term climatic and environmental change in southwestern China is hampered by a lack of long-term regional palaeorecords. Organic analysis (%TOC, %TN, C/N ratios and δ13C values) of a sediment sequence from Lake Shudu, Yunnan Province (ca. 22.6-10.5 cal ka BP) indicates generally low aquatic palaeoproductivity rates over millennial timescales in response to cold, dry climatic conditions. However, the record is punctuated by two marked phases of increased aquatic productivity from ca. 17.7 to 17.1 cal ka BP and from ca. 11.9 to 10.5 cal ka BP. We hypothesise that these shifts reflect a marked, stepwise lacustrine response to Asian summer monsoon strengthening during the last deglaciation.

  12. Paleoclimatic record of the last 18 ka cal BP in marine sediments from Pescadero Basin, southern Gulf of California

    NASA Astrophysics Data System (ADS)

    Escorza-Reyes, M.; Perez-Cruz, L. L.; Fucugauchi, J. U.

    2013-05-01

    In this study are presented the geochemical and magnetic records with a multi-decadal resolution from a marine sequence, in order to reconstruct the oceanographic and climatic conditions during the past 18 ka in the southern Gulf of California. A gravity core DIPAL III-T2 was recovered in the eastern part of Pescadero Basin, at 577 m depth, in the Pacific Intermediate Water (PIW) and Oxygen Minimum Zone (OMZ), aboard the R/V "El Puma" of the National University of Mexico (UNAM). The core is 263 cm long. Concentrations of chemical elements were measured every cm using an X-ray fluorescence analyzer (Niton XL3t 900S) and magnetic susceptibility measurements were taken every 0.5 cm with a Bartington Susceptibilimeter with MS2B sensor. Chronology is based on seven AMS radiocarbon dates calibrated and reservoir age corrected. According to the age model, the marine sequence comprises the last 18 ka and sedimentation rates range from ~0.05 mm/yr to ~0.29 mm/yr, increasing upward. The marine sequence consists of massive and homogeneous sediments from bottom to 200 cm, and from there to the top a well defined laminated structure is observed. Sediments are composed mainly of terrigenous (~80%) and in less amount silica and calcium carbonate biogenic remains (~15%). A sharp difference in concentrations of five elements (Ti, Zr, Ca, Ba and V), also observed in magnetic susceptibility measurements and sedimentary structures, marks four intervals of different oceanographic and atmospheric conditions in the southeastern Gulf of California, being the glacial-interglacial transition one of the most evident. Vanadium concentrations downcore show low values during Pleistocene, where sediments are massive, and high values during the Holocene, where laminated sediments are preserved. These conditions suggest a decrease in oxygen-levels in the water column during Holocene, probably due to productivity increase in surface waters related to intensification of NW winds, evidenced by high

  13. Development and comparison of layer-counted chronologies from the WAIS Divide and EDML ice cores, Antarctica, over the last glacial transition (10-15 ka BP)

    NASA Astrophysics Data System (ADS)

    Winstrup, Mai; Vinther, Bo M.; Sigl, Michael; McConnell, Joe; Svensson, Anders M.; Wegner, Anna

    2014-05-01

    Some ice cores can be very precisely dated far back in time by counting the annual layering in various impurity records, and the most robust chronologies rely on the parallel analysis of annual features expressed in multiple data sets. Layer-counted Antarctic ice-core chronologies are now emerging: Multi-parameter layer counting has been carried out for the Holocene and late glacial section of the EDML ice core, Dronning Maud Land (Vinther et al., in prep.), and a layer-counted timescale for the WAIS Divide core, West Antarctica, reaching back to 30 kyr BP, was recently completed (WDC06A-7; WAIS Divide Members, 2013). Beyond 24 kyr b2k, the main part of this timescale relies solely on electrical measurements on the core. We here use a novel statistical framework for automated annual layer counting (Winstrup et al., 2012) to extend and improve the two chronologies from EDML and WAIS Divide. Using this method, we have 1) revised the multi-parameter layer counts for the EDML ice core back to 15 kyr BP, and 2) employed high-resolution chemistry measurements from WAIS Divide to obtain a layer-counted multi-parameter timescale for WAIS Divide over the same period (10-15 ka b2k). The EDML and WAIS Divide ice cores have been tightly synchronized using volcanic marker horizons, thus allowing a detailed comparison of annual layer counts between tie points using the various approaches. The corresponding timescales are compared also to the EDML timescale from the flow-model based AICC2012 chronology (Veres, 2012). For the Holocene section of the period (10-11.7 ka BP), all timescales show very good agreement. The peculiar accumulation anomaly observed in the WAIS Divide layer thicknesses in the beginning of the Holocene is confirmed by the multi-parameter layer counts from both WAIS Divide and EDML. The transition into the Holocene has generally proven a difficult period to date by annual layer counting, since the appearance of an annual layer in the various records can change

  14. A compilation of Western European terrestrial records 60-8 ka BP: towards an understanding of latitudinal climatic gradients

    NASA Astrophysics Data System (ADS)

    Moreno, Ana; Svensson, Anders; Brooks, Stephen J.; Connor, Simon; Engels, Stefan; Fletcher, William; Genty, Dominique; Heiri, Oliver; Labuhn, Inga; Perşoiu, Aurel; Peyron, Odile; Sadori, Laura; Valero-Garcés, Blas; Wulf, Sabine; Zanchetta, Giovanni

    2014-12-01

    Terrestrial records of past climatic conditions, such as lake sediments and speleothems, provide data of great importance for understanding environmental changes. However, unlike marine and ice core records, terrestrial palaeodata are often not available in databases or in a format that is easily accessible to the non-specialist. As a consequence, many excellent terrestrial records are unknown to the broader palaeoclimate community and are not included in compilations, comparisons, or modelling exercises. Here we present a compilation of Western European terrestrial palaeo-records covering, entirely or partially, the 60-8-ka INTIMATE time period. The compilation contains 56 natural archives, including lake records, speleothems, ice cores, and terrestrial proxies in marine records. The compilation is limited to include records of high temporal resolution and/or records that provide climate proxies or quantitative reconstructions of environmental parameters, such as temperature or precipitation, and that are of relevance and interest to a broader community. We briefly review the different types of terrestrial archives, their respective proxies, their interpretation and their application for palaeoclimatic reconstructions. We also discuss the importance of independent chronologies and the issue of record synchronization. The aim of this exercise is to provide the wider palaeo-community with a consistent compilation of high-quality terrestrial records, to facilitate model-data comparisons, and to identify key areas of interest for future investigations. We use the compilation to investigate Western European latitudinal climate gradients during the deglacial period and, despite of poorly constrained chronologies for the older records, we summarize the main results obtained from NW and SW European terrestrial records before the LGM.

  15. 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.

  16. Early deglaciation (18.1 ka BP) of the southwest Scandinavian Ice Sheet and Late Glacial sea-level change reconstructed from isolation basins on Karmøy

    NASA Astrophysics Data System (ADS)

    Vasskog, Kristian; Svendsen, John-Inge; Mangerud, Jan; Svean, Arve; Lunnan, Eva Marie; Briner, Jason

    2016-04-01

    A series of cosmogenic exposure dates (10Be) suggest that the island Utsira off the SW coast of Norway became ice free as early as 20 ka years ago. Here we present a preliminary sea level curve that has been constructed for the island of Karmøy, which is situated at the mouth of Boknafjorden just a few km inside Utsira, based on coring and analyses of sediment sequences from isolation basins. A deglaciation age of 18.1±0.1 ka BP has been established for southern Karmøy based on radiocarbon dating of foraminifera from basal marine sediments in two basins; lake Grødheimsvatnet (15.5 m above present sea level) and the bog Kringlemyr (12.0 m above present sea level). Lithostratigraphic and microfossil analyses show that Grødheimsvatnet became isolated from the sea at 17.8±0.1 ka BP, while Kringlemyr emerged at 17.0±0.2 ka BP. The results from these basins give a mean rate of emergence of about 4.4 mm/yr during the first millennium after the area became ice-free. Relative sea level on Karmøy then fell more rapidly at the transition to the Bølling interstadial before levelling out some 3-4 m below present day sea level around 14 ka BP. Following this period of stillstand the sea level started to rise during the Allerød culminating at 6-7 m above present towards the end of Younger Dryas, after which another, more rapid regression phase started. We have combined the curve from Karmøy with far-field sea-level data in order to quantify the contributing factors (i.e. glacial isostatic adjustment and geoid changes) in the reconstructed shoreline displacement.

  17. Environmental Change recorded in Lacustrine Sediments from Tangra Yumco, Tibetan Plateau, at 16.5 ka cal BP and during the Younger Dryas Chronozone

    NASA Astrophysics Data System (ADS)

    Henkel, K.; Ahlborn, M.; Haberzettl, T.; Kasper, T.; Daut, G.; Ju, J.; Ma, Q.; Wang, J.; Zhu, L.; Maeusbacher, R.

    2013-12-01

    In the purpose of understanding the recent climate change on the Tibetan Plateau (TP) and beyond and to allow predictions for future climate scenarios it is imperative to investigate past climate changes. The numerous lake systems on the TP serve as ideal archives for past hydrological changes, which are assumed to be caused by variations in strength and extent of monsoonal air masses. By now, the spatial and temporal monsoonal evolution on the TP is intensively discussed. With the focus on a W-E lake transect on the southern TP we investigate lakes with a multi-dating and multi-proxy analyses approach, which has already been successfully carried out on Nam Co, the easternmost lake of the transect. In this study, we present results from a ~11.5 m long lacustrine sediment record from the terminal lake Tangra Yumco (4,540 m a.s.l., 31°13'N, 86°43'E), representing the center of the transect. Tangra Yumco is the deepest lake recorded on the TP so far. Via a hydro-acoustic survey observed submerged beach berms (45 m below recent lake level) and exposed lake level terraces up to ~205 m above lake level indicate large lake level fluctuations in the past. The record consists of an interbedding of fine grained silty sediments with a lamination of different thicknesses (sub-mm to cm) and partly intercalated blackish sandy layers. Homogeneous areas, which occur especially in the upper two thirds of the profile, represent turbidite deposits. Until now, color- and greyscale-, magnetic susceptibility- and XRF-scanning were applied. For age control 22 14C AMS-radiocarbon measurements were carried out on bulk organic matter. To determine a possible carbon reservoir effect, additional surface sediment samples were measured as well as one modern aquatic plant. The results indicate a reservoir effect of ~2,120 +110/-90 years. Assuming a constant reservoir effect, the base of the record reveals a corrected radiocarbon age of 17,270 +325/-310 cal BP. The sediment accumulation rate is

  18. 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.

  19. Highly explosive eruption of the monogenetic 8.6 ka BP La Vache et Lassolas scoria cone complex (Chaîne des Puys, France)

    NASA Astrophysics Data System (ADS)

    Jordan, S. C.; Le Pennec, J.-L.; Gurioli, L.; Roche, O.; Boivin, P.

    2016-03-01

    The eruption of the trachy-basaltic La Vache and Lassolas cone complex was the youngest eruption (ca. 8.6 ka BP) and one of the most violent in the Chaîne des Puys, France. Here we present field data and results of grain size, componentry and clast density measurements of different layers of the widespread tephra deposit that is associated with this cone-forming eruption. Our data indicates five main eruption phases comprising a vent-opening phase, a second sustained highly explosive phase, a third and fourth violent Strombolian phase and a fifth dominantly effusive phase. The layer formed by the opening phase is rich in lithic material, which was previously considered to be the result of phreatomagmatic activity. The data presented here on the componentry and textures of the pyroclastic material contradict this hypothesis. We propose instead that the material of the basal layer results from fragmentation caused by the explosion of a first arriving gas-dominated phase. The variations in eruption intensity during the main eruption phases are interpreted here to be the result of gas segregation within the plumbing system and fluxes in the magma ascent rate during the eruption. Significant amount of gas segregation is indicated by the deposition of both gas-poor and gas-rich material and by the presence of plate tephra. This is also supported by the simultaneous ejection of tephra and lava from both cones during most of the explosive activity. We suggest that gas segregation occurred within shallow intrusions and that fresh ascending material in the main conduit mixed with degassed material that flow back into the conduit from the intrusion before fragmentation. The interaction of the ascending magma and the opening of intrusions may have controlled the evolution and explosivity of the eruption. The high explosivity at the beginning of the eruption and the wide dispersal area, demonstrate that scoria cone eruptions in monogenetic fields can impose a major threat to

  20. Advection of Atlantic Water to the Western and Northern Svalbard Shelves Through the Last 17.5 ka cal yr BP

    NASA Astrophysics Data System (ADS)

    Slubowska, M. A.; Rasmussen, T. L.; Koc, N.; Kristensen, D. K.; Nilsen, F.; Solheim, A.

    2005-12-01

    We have studied the distribution of benthic foraminifera species together with planktonic and benthic foraminifera abundances, stable oxygen isotopes and lithology in two cores: JM02-440 from the western (77° 22' N, 12° 48' E, 240 m water depth) and NP94-51 from the northern (80° 21' N and 16 ° 17' E, 400 m water depth) shelf of Svalbard. The purpose of the study was to reconstruct the changes in flow and character of the relatively warm Atlantic Water through the last 17.5 ka cal yr BP. The results from these two sites were compared with previously published records from the eastern Nordic Seas in order to follow the history of the advection of Atlantic Water as it moved northwards along the Norwegian coast and into the Arctic Ocean. Our results indicate that synchronous oceanographic changes occurred at the western and northern Svalbard shelves. The benthic foraminifera and oxygen isotope records indicate almost continuous presence of the Atlantic Water at the shelf areas since the deglaciation. The Bolling-Allerod period stands out as the warmest period in our records with the highest bottom waters temperatures indicating strong inflow of Atlantic Water. However, the warm Atlantic Water was isolated below cold and probably sea ice covered surface waters in contrast to the surface waters along the Norwegian coast, which experienced enhanced temperatures. During the Younger Dryas a freshening of the bottom waters occurred and the Polar Front was located in a proximal position to both sites. The strong inflow of saline, but chilled Atlantic Water happened during the Early Holocene. A distinct cooling and freshening of the bottom water masses occurred during the Mid- and Late Holocene, and was accompanied by glacier re-advances leading to the present-day conditions. During the last millennium, the inflow of Atlantic Water appears to increase, but the conditions turned unstable. The development of the paleoceanographic conditions at the western and northern

  1. A regional overview of the last glacial period in the temperate NE Atlantic: varying paleoproductivity centers over the last 50 ka BP

    NASA Astrophysics Data System (ADS)

    Penaud, Aurélie; Eynaud, Frédérique; Ganne, Axelle

    2015-04-01

    Recent palynological investigations carried out in the eastern Gulf of Cadiz (MD99-2339 core) over MIS 3 enable to consider dinoflagellate cyst assemblage patterns over the last 50 ka BP through a compilation of 6 cores from the NE subtropical Atlantic to the Northern Bay of Biscay (also including cores MD95-2042, MD95-2043, MD04-2805CQ, VK03-58bis). Dinocyst signals depict hydrological front latitudinal shifts over the last glacial and associated sea-surface consequences regarding past regimes of primary productivity. We show here new data clearly evidencing subtropical latitudes of Cadiz as being as productive areas over the last glacial as recorded today in the septentrional part of the Bay of Biscay, especially between GI 8 and GI 12. We especially focus on dinocyst-species Lingulodinium machaerophorum relative abundances and absolute concentrations that we first evidence as a powerful tool to reconstruct and discuss productivity shifts through time in the temperate North Atlantic. This spatio-temporal synthesis bring important evidences of fast migrating paleoproductiviy centers from the last glacial period to present, implying also large consequences on the biological pump through time. Regarding this specific session, 5 of the 6 cores discussed here were retrieved by the R/V Marion Dufresne through 3 different cruises: Core MD99-2339 (35.89°N, 7.53°W, 1170m water depth, 18.54m long) was retrieved in a contouritic field in the oriental part of the Gulf of Cadiz by the oceanographic R/V Marion Dufresne during the 1999 International Marine Global Change Studies V (IMAGES V) cruise (Labeyrie, Jansen and Cortijo, 2003). Cores MD95-2042 (37°48'N, 10°10'W, 3146m water depth, 39.56m long) and MD95-2043 (36°8.6'N, 2°37.3'W, 1841m water depth, 36m long) were retrieved from the SW Iberian margin and the central Alboran Sea, respectively, by the oceanographic R/V Marion Dufresne during the 1995 IMAGES I cruise (Bassinot and Labeyrie, 1996). Core MD04-2805 CQ (34

  2. Evaluation of iron and cobalt powders as catalysts for 14C-AMS target preparation

    NASA Astrophysics Data System (ADS)

    Santos, G. M.; Mazon, M.; Southon, J. R.; Rifai, S.; Moore, R.

    2007-06-01

    We present an evaluation of different brands of cobalt and iron powders used to catalyze CO2 reduction for 14C-AMS graphite targets at the KCCAMS/University of California, Irvine. The optimal catalyst is characterized by rapid graphitization, homogeneity and lack of sintering of the catalyst/carbon mixture, and contains minimal amounts of both "modern" and "dead" carbon. Fifteen catalyst powders were evaluated using these criteria. The results of this study indicate three good "catalyst-candidates" with backgrounds on processed coal (Argonne Premium coal POC#3) samples around 60 ka BP and modern and dead carbon contamination of ⩽0.2 μgC for 4-5 mg of catalyst.

  3. 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

  4. Radiocarbon variability during the Laschamp excursion (ca. 41 ka) based on Gulf of Mexico sediments

    NASA Astrophysics Data System (ADS)

    Williams, C. C.; Guilderson, T. P.

    2009-12-01

    The Laschamp excursion is a rapid (<2 ka) geomagnetic reversal approximately 41.25 ± 0.8 ka BP (based on the 2005 Greenland Ice Core Chronology (GICC05)) that is present in many terrestrial and marine sediment records. Due to changes in Earth’s magnetic field during geomagnetic excursions and reversals, atmospheric 14C production is variable and can subsequently make 14C dating and calendar year calibration difficult. Although paleointensity lows during the Laschamp interval are useful in correlating sediment and ice core records data to a common timescale, climate archives that lack these data require radiocarbon dating for temporal constraint. Yet, the 14C response during geomagnetic changes is not well understood. We present a new record of accelerator mass spectrometry (AMS) 14C dates combined with paleointensity data from core MD02-2551 from Orca Basin, Gulf of Mexico. High sedimentation rates (~60 cm/1000 yrs) allow for high-resolution sampling over the duration of the Laschamp interval. In this section of the core sediments are oxic and massive, consistent with a hemipelagic depositional environment. The comparison of paleogeomagnetic data to 14C ages during the Laschamp excursion allow us to further investigate the geochemical 14C signal during magnetic excursions. Results exhibit a plateau in 14C ages with high-frequency fluctuations superimposed during the Laschamp interval that supports the expectation of increased atmospheric 14C production during this geomagnetic excursion. We compare our results to a similar marine derived record from the oxic non-laminated interval of Cariaco Basin with a similar albeit slightly lower sedimentation rate (~30cm/1000 yrs).

  5. A coccolithophore based view on paleoenvironmental changes in the open ocean mid-latitude North Atlantic between 130 and 48 ka BP with special emphasis on MIS 5e

    NASA Astrophysics Data System (ADS)

    Schwab, C.; Kinkel, H.; Weinelt, M.; Repschläger, J.

    2013-12-01

    As oceanographic changes in the North Atlantic are known to modulate global climate, they are key to the understanding of past and future climate changes. Especially the mid-latitudes of the open ocean North Atlantic may be of interest, regarding the large area covered. We therefore reconstructed past changes in productivity and hydrography from a new sediment core (MD08-3179Cq) taken in the open ocean mid-latitude North Atlantic in the vicinity of the Azores Current System. Concomitant to the reorganizations of environmental conditions in the North Atlantic between 130 and 48 ka BP, changes in coccolithophore assemblages and changes in the abundance of siliceous plankton (diatoms) indicate a southward shift of the Azores Front (AzF), and hence a southward retreat of the North Atlantic subtropical gyre, as well as an increased productivity, during glacial Marine Isotope Stage (MIS) 4, Termination II and during cold substages of MIS 5. Furthermore we hypothesize that the ecological changes led to distinct evolutionary patterns of coccolithophores, resulting e.g. in a dominance of Gephyrocapsaornata between 76 and 105 ka BP. Additionally, high-resolution analysis of MIS 5e indicate a short reversal towards cool conditions during MIS 5e, corresponding to a basin-wide cooling event. Full interglacial conditions are reached only late in the Azores region. During MIS 5e an increased advection of Subantarctic Mode Water (SAMW), and/or the possibility to occupy new habitats after glacial conditions, result in a distinct coccolithophore productivity peak. As global temperature during MIS 5e are assumed to be similar to the expected future global climate change, MIS 5e serves as a possible scenario for future changes. Taking MIS 5e as a possible analogue for expected future climate change, our results indicate that an expected decrease in marine primary productivity, due to the expansion of the oligotrophic gyres, may be attenuated by increased coccolithophore productivity.

  6. 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.

  7. 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.

  8. 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.

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

    NASA Astrophysics Data System (ADS)

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

    1993-02-01

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

  10. 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

  11. 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.

  12. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-02-01

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

  14. 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.

  15. Measurement of fecal /sup 14/C excretion

    SciTech Connect

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

    1982-11-01

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

  16. 14C-carbaryl residues in hazelnut.

    PubMed

    Yücel, Ulkü; Ilim, Murat; Aslan, Nazife

    2006-01-01

    A hazelnut ocak (shrub growing form) in the field in Black Sea region of Turkey was treated with commercial carbaryl insecticide spiked with 14C-carbaryl. Three months later, the harvested hazelnuts were separated into husk, shell, and kernel components, then homogenized and analyzed. The total and unextractable (bound) 14C-residues were determined by combustion and the extractable 14C-residues were obtained by extracting the samples with methanol. Concentrated extracts were first analyzed by thin layer chromatography (TLC). The extracts were also subjected to a series of liquid-liquid extraction procedures for clean-up and the final extracts were analyzed by high performance liquid chromatography (HPLC). Crude hazelnut oil was also extracted with hexane and analyzed for total 14C-residue. A total of 1.3% of applied radioactivity was recovered from the total nut harvested, with 0.04%, 0.06%, and 1.2% present in shell, kernel, and husk, respectively. The results show that the inedible husk and shell contained 95.7% 14C, whereas the edible kernel contained 4.3% of the total 14C recovered. The terminal 14C-residue in hazelnut kernel and oil did not contain carbaryl and/or its metabolite naphthol. PMID:16785168

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

    PubMed

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

    1988-06-15

    Guinea pigs were exposed to [14C]methyl isocyanate (14CH3-NCO, 14C MIC) for periods of 1 to 6 hr at concentrations of 0.5 to 15 ppm. Arterial blood samples taken during exposure revealed immediate and rapid uptake of 14C. Clearance of 14C was then gradual over a period of 3 days. Similarly 14C was present in urine and bile immediately following exposure, and clearance paralleled that observed in blood. Guinea pigs fitted with a tracheal cannula and exposed while under anesthesia showed a reduced 14C uptake in blood indicating that most of the 14C MIC uptake in normal guinea pigs occurred from retention of this agent in the upper respiratory tract passages. In exposed guinea pigs 14C was distributed to all examined tissues. In pregnant female mice similarly exposed to 14C MIC, 14C was observed in all tissues examined following exposure including the uterus, placenta, and fetus. While the form of 14C distributed in blood and tissues has not yet been identified, these findings may help to explain the toxicity of MIC or MIC reaction products on organs other than the respiratory tract, as noted by several investigators. PMID:3376108

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

    PubMed

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

    2007-04-01

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

  19. 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.

  20. Evidence of resilience to past climate change in Southwest Asia: Early farming communities and the 9.2 and 8.2 ka events

    NASA Astrophysics Data System (ADS)

    Flohr, Pascal; Fleitmann, Dominik; Matthews, Roger; Matthews, Wendy; Black, Stuart

    2016-03-01

    Climate change is often cited as a major factor in social change. The so-called 8.2 ka event was one of the most pronounced and abrupt Holocene cold and arid events. The 9.2 ka event was similar, albeit of a smaller magnitude. Both events affected the Northern Hemisphere climate and caused cooling and aridification in Southwest Asia. Yet, the impacts of the 8.2 and 9.2 ka events on early farming communities in this region are not well understood. Current hypotheses for an effect of the 8.2 ka event vary from large-scale site abandonment and migration (including the Neolithisation of Europe) to continuation of occupation and local adaptation, while impacts of the 9.2 ka have not previously been systematically studied. In this paper, we present a thorough assessment of available, quality-checked radiocarbon (14C) dates for sites from Southwest Asia covering the time interval between 9500 and 7500 cal BP, which we interpret in combination with archaeological evidence. In this way, the synchronicity between changes observed in the archaeological record and the rapid climate events is tested. It is shown that there is no evidence for a simultaneous and widespread collapse, large-scale site abandonment, or migration at the time of the events. However, there are indications for local adaptation. We conclude that early farming communities were resilient to the abrupt, severe climate changes at 9250 and 8200 cal BP.

  1. 14C Analysis via Intracavity Optogalvanic Spectroscopy

    PubMed Central

    Murnick, Daniel; Dogru, Ozgur; Ilkmen, Erhan

    2010-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  3. 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

  4. 17 CFR 240.14c-1 - Definitions.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

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

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

    Code of Federal Regulations, 2012 CFR

    2012-04-01

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

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

    Code of Federal Regulations, 2013 CFR

    2013-04-01

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

  7. 17 CFR 240.14c-5 - Filing requirements.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

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

  8. 17 CFR 240.14c-1 - Definitions.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

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

  9. 17 CFR 240.14c-5 - Filing requirements.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

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

  10. 17 CFR 240.14c-1 - Definitions.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

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

  11. 17 CFR 240.14c-1 - Definitions.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

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

  12. 17 CFR 240.14c-1 - Definitions.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 17 Commodity and Securities Exchanges 3 2013-04-01 2013-04-01 false Definitions. 240.14c-1 Section 240.14c-1 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION (CONTINUED) GENERAL... Exchange Act of 1934 Regulation 14c: Distribution of Information Pursuant to Section 14(c) §...

  13. 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.

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

    PubMed Central

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

    1984-01-01

    Cultures of Fusarium roseium 'Gibbosum' on rice were treated with [14C]zearalenone, alpha[14C]zearalenol, or beta-[14C]zearalenol to determine whether a precursor-product relationship exists among these closely related fungal metabolites. Culture extracts were purified by silica gel column chromatography and fractionated by high-pressure liquid chromatography, and the level of radioactivity was determined. Within 7 days, the beta-[14C]zearalenol was converted to zearalenone, and no residual beta-[14C]zearalenol was detectable. Most of the alpha-[14C]zearalenol added was also converted into zearalenone with 14 days. In cultures treated with [14C]zearalenone, no radioactivity was noted in any other components. PMID:6742839

  15. Synthesis of. beta. -sitosterol-/sup 14/C

    SciTech Connect

    Askinazi, B.Z.; Kivokurtseva, L.N.; Bobrova, N.S.; Kozarinskaya, N.Ya.

    1986-08-01

    The method of synthesis of ..beta..-sitosterol-4-/sup 14/C starting with the enolactone 4-oxa-5-sitosten-3-one is discussed. Methyl-/sup 14/C magnesium iodide is utilized for the introduction of the label. The authors selected this method for the isolation of ..beta..-sitosterol-/sup 14/C, introducing a series of changes into the original method. The authors discuss obtaining sitostenone, the ketoacid of sitostenone, the enol-lactone of the ketoacid of sitostenone, sitostenone-4-/sup 14/C (by different methods), the enol-acetate of sitostenone-/sup 14/C, and ..beta.. sitosterol-4-/sup 14/C.

  16. 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

  17. 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

  18. 17 CFR 240.14c-101 - Schedule 14C. Information required in information statement.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...-101. Item 1. Information required by Items of Schedule 14A (17 CFR 240.14a-101). Furnish the information called for by all of the items of Schedule 14A of Regulation 14A (17 CFR 240.14a-101) (other than... 17 Commodity and Securities Exchanges 3 2011-04-01 2011-04-01 false Schedule 14C....

  19. 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

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

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

  2. 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.

  3. 17 CFR 240.14c-101 - Schedule 14C. Information required in information statement.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... required by Items of Schedule 14A (17 CFR 240.14a-101). Furnish the information called for by all of the items of Schedule 14A of Regulation 14A (17 CFR 240.14a-101) (other than Items 1(c). 2, 4 and 5 thereof... 17 Commodity and Securities Exchanges 3 2012-04-01 2012-04-01 false Schedule 14C....

  4. 17 CFR 240.14c-101 - Schedule 14C. Information required in information statement.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... required by Items of Schedule 14A (17 CFR 240.14a-101). Furnish the information called for by all of the items of Schedule 14A of Regulation 14A (17 CFR 240.14a-101) (other than Items 1(c). 2, 4 and 5 thereof... 17 Commodity and Securities Exchanges 4 2014-04-01 2014-04-01 false Schedule 14C....

  5. 17 CFR 240.14c-101 - Schedule 14C. Information required in information statement.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... required by Items of Schedule 14A (17 CFR 240.14a-101). Furnish the information called for by all of the items of Schedule 14A of Regulation 14A (17 CFR 240.14a-101) (other than Items 1(c). 2, 4 and 5 thereof... 17 Commodity and Securities Exchanges 3 2013-04-01 2013-04-01 false Schedule 14C....

  6. 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

  7. Geochemical properties and environmental impacts of seven Campanian tephra layers deposited between 40 and 38 ka BP in the varved lake sediments of Lago Grande di Monticchio, southern Italy

    NASA Astrophysics Data System (ADS)

    Wutke, Kristina; Wulf, Sabine; Tomlinson, Emma L.; Hardiman, Mark; Dulski, Peter; Luterbacher, Jürg; Brauer, Achim

    2015-06-01

    We present the results of new tephrostratigraphical and environmental impact studies of the 40-38 ka varved sediment section of Lago Grande di Monticchio (southern Italy). The sediments in this time zone are correlated with the Heinrich H4-stadial that occurred between Greenland Interstadials GI-9 and GI-8, and include the widespread Campanian Ignimbrite (CI, 39.3 ka) as a thick tephra layer in the middle of the H4 stadial. The CI in the Monticchio record is overlain by the Schiava tephra from Vesuvius, c. 1240 varve-years younger than the CI, and preceded by four tephras from small-scale eruptions of the Phlegrean Fields and by an Ischia-derived tephra. The four Phlegrean Field-derived tephras were deposited 600 varve-years or fewer prior to the deposition of the CI and show very similar major, minor, and trace element glass compositions to those of the CI. This close similarity in composition and age could compromise the accurate linking and synchronisation of palaeoenvironmental records in the central Mediterranean area. Microfacies analyses and μ-XRF core scanning were used to characterise primary and secondary depositional features of all seven tephra layers and to evaluate environmental and ecological responses after tephra deposition. Higher concentrations of tephra-derived material (mainly glass shards and pumices) in primary and reworked layers were detected by elevated K-counts in μ-XRF elemental core scans. Reworked tephra derives mainly from in-washing from the littoral zone and the catchment and occurs within five to 30 years, and up to 1240 varve years, after the deposition of thinner (1-5 mm) and thicker (5-230 mm) tephra fallout deposits, respectively. An obvious response of diatom population growth directly after the primary tephra deposition was observed for the thicker tephra layers (>1 mm) during the first 1-8 years after deposition of the primary deposit indicating that the additional input of potential nutrients (glass shards) temporarily

  8. 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.

  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. East Asian Summer Monsoon variations in the past 12.5 ka: High-resolution δ18O record from a precisely dated aragonite stalagmite in central China

    NASA Astrophysics Data System (ADS)

    Zhang, Hui-Ling; Yu, Ke-Fu; Zhao, Jian-Xin; Feng, Yue-Xing; Lin, Yu-Shi; Zhou, Wei; Liu, Guo-Hui

    2013-09-01

    stalagmite records from South China. The comparison among these records shows that the Holocene Optimum was synchronous across Asian continental region influenced by the EASM and Indian Summer Monsoon (ISM), lasting from ∼10.6 to 4.2 ka BP, as reflected by consistently lighter δ18O values among all these records regardless of their latitudinal difference. These records do not support previously reported asynchronism between EASM and ISM. In details, the long-term δ18O trend in LH2 is punctuated by a number of centennial fluctuations. For instance, two weak monsoon events occurred at 9232 ± 57 yr BP and 8137 ± 21 yr BP, correlating in time with cooling events in Greenland ice cores. The latest weak monsoon event centered at 302 ± 8 yr BP which is related to the Little Ice Age (LIA). In addition, the monsoon intensity derived from our record also shows a strong connection with latitudinal migration of the Inter-Tropical Convergence Zone (ITCZ) as recorded in the Cariaco Basin sediments. Spectral analysis of δ18O values shows that significant peaks match with solar periodicities of 208 yr (de Vries cycle), 86 yr (Gleissberg cycle) or related to Δ14C production suggesting shorter-term monsoon variations are forced by solar radiation. Overall, our study suggests that the δ18O record in the aragonite stalagmite is highly consistent with those derived from calcite stalagmites, suggesting that aragonite stalagmites are suitable for palaeoclimate reconstruction, especially for the Holocene period, as aragonite-calcite transformation has not occurred.

  11. Age and geomorphic history of Meteor Crater, Arizona, from cosmogenic 36Cl and 14C in rock varnish

    USGS Publications Warehouse

    Phillips, F.M.; Zreda, M.G.; Smith, S.S.; Elmore, D.; Kubik, P.W.; Dorn, R.I.; Roddy, D.J.

    1991-01-01

    Using cosmogenic 36Cl buildup and rock varnish radiocarbon, we have measured the exposure age of rock surfaces at Meteor Crater, Arizona. Our 36Cl measurements on four dolomite boulders ejected from the crater by the impact yield a mean age of 49.7 ?? 0.85 ka, which is in excellent agreement with an average age of 49 ?? 3 ka obtained from thermoluminescence studies on shock-metamorphosed dolomite and quartz. These ages are supported by undetectably low 14C in the oldest rock varnish sample. ?? 1991.

  12. Effects of insulin on the utilization of 14C-glycerol and 14C-glucose in hepatectomized nephrectomized rats.

    PubMed

    Mampel, T; Herrera, E

    1985-04-01

    Insulin (i.v.) administration to functionally hepatectomized-nephrectomized rats did not alter circulating levels of glycerol and only slightly affected plasma radioactivity when animals received (U-14C)-glycerol, whereas after (U-14C)-glucose administration insulin enhanced hypoglycemia and greatly accelerated the rate of radioactivity loss from plasma. At 15 min after i.v. injection of (U-14C)-glycerol, radioactivity in total lipids was reduced in heart and lungs by insulin administration and enhanced in carcass and brown adipose tissue. These effects involved the 14C-glyceride glycerol fraction in the case of heart and 14C-fatty acids in carcass and adipose tissue. When (U-14C)-glucose was administered, insulin enhanced the appearance of 14C-water-soluble material in heart and carcass and 14C-total lipids in heart, carcass, and both brown and white adipose tissue. The effect in heart corresponded mainly to the 14C-glyceride glycerol fraction whereas it corresponded to the 14C-fatty acids in the other tissues. Therefore, insulin effects on glycerol metabolism substantially differ from those on glucose. Opposite effects on heart and lung glycerol utilization as compared to those in carcass and brown adipose tissue may account for the difficulties in observing changes in plasma glycerol levels after insulin treatment. PMID:3891443

  13. Behaviour of (14)C-sulfadiazine and (14)C-difloxacin during manure storage.

    PubMed

    Lamshöft, Marc; Sukul, Premasis; Zühlke, Sebastian; Spiteller, Michael

    2010-03-01

    The persistence of sulfadiazine, difloxacin, and their metabolites has been investigated in stored manure. The manure collected from sulfadiazine ((14)C-SDZ) and difloxacin ((14)C-DIF) treated pigs contained N-acetylsulfadiazine (Ac-SDZ), 4-hydroxy-SDZ (4-OH-SDZ), and sarafloxacin (SARA) as the main metabolites, respectively along with their parent compounds. Manures were stored separately at 10 degrees C and 20 degrees C at various moisture levels. About 96-99% of the radioactivity remained in extractable parent compounds and their metabolites after 150d of storage. The formation of non-extractable residue and the rate of mineralization were both negligible in manure containing SDZ and DIF. During storage SDZ concentration increased as a result of the deacetylation of Ac-SDZ, whose concentration decreased proportionally. Hence the environmental effects may be underestimated if the parent compound alone is considered for environmental risk assessment. About 11% and 14% of 4-OH-SDZ were lost after 20 and 40d of storage; thereafter its concentration increased relatively, highlighting hydroxylation of SDZ. DIF degraded very slowly (7% loss after 150d) during the storage of manure; in contrast the concentration of SARA decreased rapidly (72-90% loss after 150d). Dilution of manure and storage at higher temperatures for a reasonable period of time enhanced the rate of reactions of SDZ, DIF and their related metabolites. PMID:20022355

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

    SciTech Connect

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

    1986-10-01

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

  15. Bound sup 14 C residues in stored wheat treated with ( sup 14 C)deltamethrin and their bioavailability in rats

    SciTech Connect

    Khan, S.U.; Kacew, S. ); Akhtar, M.H. )

    1990-04-01

    Wheat grains treated with radiolabeled deltamethrin ((S)-{alpha}-cyano-3-phenoxybenzyl (1R,3R)-cis-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropanecarboxylate) and stored in the laboratory for 168 days formed bound (nonextractable) {sup 14}C residues. The amount of bound {sup 14}C residues formed was about 11% of the total {sup 14}C in stored grain. Br{sub 2}CA (3-(2,2-dibromovinyl)-2,2-dimethylcyclopropanecarboxylic acid) and 3-PBacid (3-phenoxybenzoic acid) were present in the form of bound {sup 14}C residues in addition to some radiolabeled product of unknown composition. The stored wheat containing bound {sup 14}C was fed to rats. The {sup 14}C residues were excreted in urine and feces in nearly equal proportion. The {sup 14}C residues identified in urine were Br{sub 2}CA, 3-PBacid, and conjugated compounds of 4{prime}-OH-3-PBacid (3-(4-hydroxyphenoxy)benzoic acid). Most of the {sup 14}C residues excreted in feces were extractable with methanol. Trace amounts of {sup 14}C residues were also present in lungs, kidney, and liver. The results suggest that bound residues in stored wheat treated with deltamethrin when fed to rats are highly bioavailable.

  16. 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.

  17. 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

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

    NASA Astrophysics Data System (ADS)

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

    2006-12-01

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

  19. Transport of sup 14 C-IAA and sup 14 C-ACC within floral organs of Ipomoea nil

    SciTech Connect

    Kiss, H.G. ); Maurice, H.R. ); Koning, R.E. ); Daie, J. )

    1989-04-01

    The transport of {sup 14}C-IAA {sup 14}C-ACC from agarose donor blocks applied to I. nil filaments their recovery as {sup 14}C-accumulation into floral organs was examined. The accumulation of the isotopes in the corolla tissue was greater when {sup 14}C-ACC was applied than {sup 14}C-IAA in intact isolated flower buds. Greater levels of the isotopes accumulated in the pistil, with minimal levels in receptacle and calyx tissues from isolated buds. With intact buds, greater levels of the isotopes were recovered in pistil, calyx receptacle tissues. This study provides further evidence for the role of the filaments as transport vectors for IAA ACC for the production of ethylene.

  20. Inferring LGM sedimentary and climatic changes in the southern Eastern Alps foreland through the analysis of a 14C ages database (Brenta megafan, Italy)

    NASA Astrophysics Data System (ADS)

    Rossato, Sandro; Mozzi, Paolo

    2016-09-01

    The analysis of a database of radiocarbon ages is proposed as a tool for investigating major glaciofluvial systems of the Last Glacial Maximum (LGM) in the Alpine foreland, and their relations with glacier dynamics and climatic fluctuations. Our research concerns the Brenta megafan (NE Italy), where 110 radiocarbon dates integrate a robust regional stratigraphic and palaeoclimatic framework. Age-depth models allowed us to calculate sedimentation rates, while the time distribution of peat layers, which recurrently formed in this region during the LGM, were estimated through meta-analysis. The reliability of statistical results was carefully evaluated using Pearson and Spearman coefficients. Sedimentation rates in the Brenta megafan markedly fluctuated during LGM: ≈1.8 m/ka between 40 and 26.7 ka cal BP; ≈3 m/ka between 26.7 and 23.8 ka cal BP and ≈1.4 m/ka from 23.8 to 17.5 ka cal BP, when the distributary system deactivated due to fan-head trenching. This is evidence that sediment input and routing in the glaciofluvial distributary system was particularly efficient during the central part of LGM, when glaciers were stable at their outermost position. Meta-analysis indicates an increase in peat formation in correspondence with global (Heinrich Event 3 and/or the Greenland Interstadial 5.1 and 4 for the 30.5, 29.6 and 28.8 ka cal BP peaks) and regional (23.5 ka cal BP) wet events. Other peaks at 22.2, 21.8, 20.2 and 19 ka cal BP correlate with fluctuations of south-eastern Alpine glaciers. Significant peat formation continued until ≈18 ka cal BP, when the last peak occurred. A marked decrease in peat formation is recorded concomitantly with the onset of Heinrich Event 2 (i.e. the 26 ka cal BP trough). The good correspondence of sedimentary events in the Brenta glaciofluvial system with the dynamics of glaciers and glaciofluvial and lacustrine systems in the southern Eastern Alps suggests a common climatic forcing on the whole region during the LGM. Peat layer

  1. Volcanic history and 40Ar/39Ar and 14C geochronology of Terceira Island, Azores, Portugal

    USGS Publications Warehouse

    Calvert, A.T.; Moore, R.B.; McGeehin, J.P.; Rodrigues da Silva, A.M.

    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. ?? 2006.

  2. 14C and {Th}/{U} dating of Pleistocene and Holocene stromatolites from East African paleolakes

    NASA Astrophysics Data System (ADS)

    Hillaire-Marcel, Claude; Carro, Odette; Casanova, Joel

    1986-05-01

    During recent humid episodes, stromatolites were built along paleolake margins, some 60 m above the modern water level of Lakes Natron and Magadi (southern Gregory Rift Valley). Three generations of stromatolites are observed, the more recent ones frequently covering pebbles and boulders eroded from the older ones. The youngest one yielded 14C ages ranging from approximately 12,000 to 10,000 yr B.P. Their δ 13C values (≥2.6%) suggest isotopic equilibrium between the paleolake total inorganic dissolved carbon and the atmospheric CO 2, thereby lending credence to the reliability of the 14C. An initial {230Th }/{232Th } ratio in the detrital component was determined by {Th}/{U} measurements on the 14C dated stromatolites. Using this value a {230Th }/{234U } chronology for the older stromatolites was calculated. Ages of ≥240,000 and 135,000 ± 10,000 yr were obtained for the first and second generations, respectively. A humid episode apparently characterized eastern Africa during each glacial-interglacial transition. 18O and 13C measurements on stromatolites, when compared to values on modern waters and carbonates, provide paleohydrological information. Long residence time of the paleolake waters and less seasonally contrasted regimes are inferred.

  3. 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

  4. 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.

  5. From Pleniglacial to Holocene: a 14C chronostratigraphy of environmental changes in the Konya Plain, Turkey

    NASA Astrophysics Data System (ADS)

    Fontugne, M.; Kuzucuoǧlu, C.; Karabiyikoǧlu, M.; Hatté, C.; Pastre, J.-F.

    1999-04-01

    In the endoreic, semi-arid Konya basin on the central Anatolian plateaux, long-term hydrological evolution has left various landforms and lacustrine deposits reflecting the regional climatic evolution, as well as human influence on the local environments. This paper presents results from a cooperative programme grouping several institutes from Turkey and France, on lacustrine, marshy and aeolian sediment sequences of Upper Pleistocene and Holocene age. The detailed study of environmental evolution is based on the reconstruction as well as on the characterization of the extension and contraction phases of wetlands occupying the lowest parts of the Konya plain. A soil and a marsh layer are 14C dated ca. 28,000-25,000 yr BP. Three phases of Pleniglacial (from ca. 22,000 to 17,000 yr BP) high lake levels are distinguished. Complementary OSL dates on aeolian dunes confirm the occurrence of two drought periods: the first occurs around the start of the Late Glacial, the second after the Mid-Holocene climatic optimum, the latter being 'in phase' with a similar drought in other Eastern Mediterranean regions. After 17,000 yr BP, no lacustrine phase reached as high a level as the Pleniglacial lake. During the Late Glacial, a shallow freshwater lacustrine phase is identified from >12,500 to 11,000 yr BP. The Late Glacial to Holocene transition corresponds to a general absence of deposits and dateable material, thus suggesting a period of drought, to which no aeolian features have so far been related. The Holocene environmental evolution shows a period of marsh and shallow lake extansion from 6000 to 5500 yr BP; this wetter period is interrupted by the second drought (ca. 5500 yrs BP) as indicated by aeolian dune activity. During the Late Holocene, a renewal of marshes, as well as soil development on slopes, can be interpreted either as climatic changes or as impacts of human use of water and soil resources during prehistoric and historic times.

  6. 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.

  7. Towards radiocarbon calibration beyond 28 ka using speleothems from the Bahamas

    NASA Astrophysics Data System (ADS)

    Hoffmann, Dirk L.; Beck, J. Warren; Richards, David A.; Smart, Peter L.; Singarayer, Joy S.; Ketchmark, Tricia; Hawkesworth, Chris J.

    2010-01-01

    We present a new speleothem record of atmospheric Δ 14C between 28 and 44 ka that offers considerable promise for resolving some of the uncertainty associated with existing radiocarbon calibration curves for this time period. The record is based on a comprehensive suite of AMS 14C ages, using new low-blank protocols, and U-Th ages using high precision MC-ICPMS procedures. Atmospheric Δ 14C was calculated by correcting 14C ages with a constant dead carbon fraction (DCF) of 22.7 ± 5.9%, based on a comparison of stalagmite 14C ages with the IntCal04 ( Reimer et al., 2004) calibration curve between 15 and 11 ka. The new Δ 14C speleothem record shows similar structure and amplitude to that derived from Cariaco Basin foraminifera (Hughen et al., 2004, 2006), and the match is further improved if the latter is tied to the most recent Greenland ice core chronology ( Svensson et al., 2008). These data are however in conflict with a previously published 14C data set for a stalagmite record from the Bahamas — GB-89-24-1 ( Beck et al., 2001), which likely suffered from 14C analytical blank subtraction issues in the older part of the record. The new Bahamas speleothem ∆ 14C data do not show the extreme shifts between 44 and 40 ka reported in the previous study ( Beck et al., 2001). Causes for the observed structure in derived atmospheric Δ 14C variation based on the new speleothem data are investigated with a suite of simulations using an earth system model of intermediate complexity. Data-model comparison indicates that major fluctuations in atmospheric ∆ 14C during marine isotope stage 3 is primarily a function of changes in geomagnetic field intensity, although ocean-atmosphere system reorganisation also played a supporting role.

  8. 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

  9. 14-C-NAPHTHYL, 14-C-METHYL AND 14-C-CARBONYL CARBARYL DISTRIBUTION IN THE PREGNANT MOUSE AND RAT

    EPA Science Inventory

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

  10. Decay width measurements of excited states in 14C

    NASA Astrophysics Data System (ADS)

    Haigh, P.; Ashwood, N.; Bloxham, T.; Curtis, N.; Freer, M.; Price, D.; Ziman, V.; Bohlen, H.; Kokalova, T.; Schulz, C.; von Oertzen, W.; Weldon, C.; Catford, W.; Harlin, C.

    2008-05-01

    Various excited states in 14C, above the α-decay threshold, are believed to possess a geometric arrangement of three α-particles covalently bound by the two delocalised valence neutrons. The 12C(16O, 14O)14C* reaction was studied at a beam energy of 234 MeV, at the ISL facility at the Hahn-Meitner-Institut (HMI), Berlin. The 14O ejectile was detected by a Q3D spectrometer at forward angles. The energies and angles of the excited 14C recoil break-up fragments were measured in coincidence using a double sided silicon strip detector array comprised of four detectors at backwards angles. A complete kinematic reconstruction of the reaction was performed to reconstruct the 14C* → 10Be + α and 14C* → 13C + n decay channels and the branching ratios of these decays were calculated. Neutron emission was found to be favoured for the 12.96, 14.87, 16.72 and 18.6 MeV states. Evidence for α-decay was found for the 14.87, 18.6 and 21.4 MeV states; which are candidates for the three bodied molecular cluster structure of 14C.

  11. Distribution of tetraether lipids in the 25-ka sedimentary record of Lake Challa: extracting reliable TEX86 and MBT/CBT palaeotemperatures from an equatorial African lake

    NASA Astrophysics Data System (ADS)

    Sinninghe Damsté, Jaap S.; Ossebaar, Jort; Schouten, Stefan; Verschuren, Dirk

    2012-09-01

    The distribution of isoprenoid and branched glycerol dialkyl glycerol tetraether (GDGT) lipids was studied in the sedimentary record of Lake Challa, a permanently stratified, partly anoxic crater lake on the southeastern slope of Mt. Kilimanjaro (Kenya/Tanzania), to examine if the GDGTs could be used to reconstruct past variation in regional temperature. The study material comprised 230 samples from a continuous sediment sequence spanning the last 25 ka with excellent age control based on high-resolution AMS 14C dating. The distribution of GDGTs showed large variation through time. In some time intervals (i.e., from 20.4 to 15.9 ka BP and during the Younger Dryas, 12.9-11.7 ka BP) crenarchaeol was the most abundant GDGT, whereas at other times (i.e., during the Early Holocene) branched GDGTs and GDGT-0 were the major GDGT constituents. In some intervals of the sequence the relative abundance of GDGT-0 and GDGT-2 was too high to be derived exclusively from lacustrine Thaumarchaeota, suggesting a sizable contribution from methanogens and other archaea. This severely complicated application of TEX86 palaeothermometry in this lake, and limited reliable reconstruction of lake water temperature to the time interval 25-13 ka BP, i.e. the Last Glacial Maximum and the period of post-glacial warming. The TEX86-inferred timing of this warming is similar to that recorded previously in two of the large African rift lakes, while its magnitude is slightly or much higher than that recorded at these other sites, depending on which lake-based TEX86 calibration is used. Application of calibration models based on distributions of branched GDGTs developed for lakes inferred temperatures of 15-18 °C for the Last Glacial Maximum and 19-22 °C for the Holocene. However, the MBT/CBT palaeothermometer reconstructs temperatures as low as 12 °C for a Lateglacial period centred on 15 ka BP. Variation in down-core values of the BIT index are mainly determined by the varying production rate of

  12. 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

  13. 14C Analysis of protein extracts from Bacillus spores.

    PubMed

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

    2014-07-01

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

  14. 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

  15. 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

  16. 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.

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

    USGS Publications Warehouse

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

    2003-01-01

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

  18. Calculation of the compounded uncertainty of 14C AMS measurements

    NASA Astrophysics Data System (ADS)

    Nadeau, Marie-Josée; Grootes, Pieter M.

    2013-01-01

    The correct method to calculate conventional 14C ages from the carbon isotopic ratios was summarised 35 years ago by Stuiver and Polach (1977) and is now accepted as the only method to calculate 14C ages. There is, however, no consensus regarding the treatment of AMS data, mainly of the uncertainty of the final result. The estimation and treatment of machine background, process blank, and/or in situ contamination is not uniform between laboratories, leading to differences in 14C results, mainly for older ages. As Donahue (1987) and Currie (1994), among others, mentioned, some laboratories find it important to use the scatter of several measurements as uncertainty while others prefer to use Poisson statistics. The contribution of the scatter of the standards, machine background, process blank, and in situ contamination to the uncertainty of the final 14C result is also treated in different ways. In the early years of AMS, several laboratories found it important to describe their calculation process in details. In recent years, this practise has declined. We present an overview of the calculation process for 14C AMS measurements looking at calculation practises published from the beginning of AMS until present.

  19. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2003-11-01

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

  1. Changes in brain glucose use and extracellular ions associated with kainic acid-induced seizures: (/sup 14/C)-2-deoxyglucose and intracranial

    SciTech Connect

    Chastain, J.E Jr.

    1986-01-01

    The effect of kainic acid (KA) on brain glucose use with coadministration of diazepam, and the effect of KA on brain extracellular (K/sup +/), Ca/sup 2 +/), and (Na/sup +/) was investigated in rats by means of (/sup 14/C)-2-deoxyglucose (2-DG) and intracranial microdialysis, respectively. Also, the impact of intracranial microdialysis on brain regional metabolic function was studied. Co-treatment with KA and diazepam attenuated KA-induced 3 hr increases and prevented 48 hr decreases in glucose use within all structures measured, particularly the piriform cortex and amygdala. Hippocampal CA/sub 3/, CA/sub 4/, and CA/sub 1/-ventral were least affected by diazepam. The results suggest that diazepam suppresses KA seizure spread from its focus, proposed to be CA/sub 3/. KA-induced ions changes were studied by intracranial microdialysis. Dialysis fibers were implanted within the hippocampus or piriform cortex and perfused 24 hr later. Samples, collected before and after KA, were analyzed for (K/sup +/), (Ca/sup 2 +/), and (Na/sup +/). KA caused an early and prolonged increase in extracellular (K/sup +/) and a negligible decrease in (Ca/sup 2 +/) within the hippocampus. In the piriform cortex, both (K/sup +/) and (Na/sup +/) increase during a period of early seizure signs. The results indicate that ion homostatic control of ion levels is better maintained during parenteral KA-induced seizures than when the brain is activated locally or during ischemia/hypoxia. The effect of intracranial microdialysis was studied by means of 2-DG in control state and KA-induced seizure state. The results indicate that intracranial microdialysis alters brain metabolic function during KA-induced seizures, but not in the control state. At 3 hr post KA, seizure metabolic activity was enhanced within the piriform cortex, and attenuated within the hippocampus.

  2. 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

  3. 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.

  4. 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.

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

    PubMed

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

    2001-01-01

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

  6. 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.

  7. Study of Rainbow Scattering in 16O + 14C System

    NASA Astrophysics Data System (ADS)

    Demyanova, A. S.; Glukhov, Yu. A.; Ogloblin, A. A.; Trzaska, W.; Bohlen, H. G.; Oertzen, W. Von; Goncharov, S. A.; Izadpanakh, A.; Maslov, V. A.; Penionzhkevich, Yu. E.; Sobolev, Yu. G.; Khlebnikov, S. V.; Tyurin, G. P.

    2005-09-01

    We carried out new measurements of the 16O+14C differential cross-sections at the 16O energy 281 MeV in the large angles interval at the Jyvaskyla University cyclotron and at the smallest angles at the cyclotron of Hahn-Meitner institute. The results of the experiment showed that clear rainbow structure in 16O + 14C scattering really takes place. The observed position of the main Airy minimum predicted but not observed in previous measurements fits well to the empirical systematization "angle - inverse energy", obtained for the system 16O + 12C.

  8. 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.

  9. 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.

  10. Origin of the Anomalous Long Lifetime of 14C

    SciTech Connect

    Dean, David Jarvis; Nam, Hai Ah; Maris, Pieter; Vary, J. P.; Navratil, Petr; Ormand, W. Erich

    2011-01-01

    We report the microscopic origins of the anomalously suppressed beta decay of 14C to 14N using the ab initio no-core shell model with the Hamiltonian from the chiral effective field theory including three-nucleon force terms. The three-nucleon force induces unexpectedly large cancellations within the p shell between contributions to beta decay, which reduce the traditionally large contributions from the nucleon-nucleon interactions by an order of magnitude, leading to the long lifetime of 14C.

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

    SciTech Connect

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

    1991-05-01

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

  12. 17 CFR 240.14c-3 - Annual report to be furnished security holders.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

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  13. 17 CFR 240.14c-7 - Providing copies of material for certain beneficial owners.

    Code of Federal Regulations, 2012 CFR

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  14. 17 CFR 240.14c-4 - Presentation of information in information statement.

    Code of Federal Regulations, 2014 CFR

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  15. 17 CFR 240.14c-7 - Providing copies of material for certain beneficial owners.

    Code of Federal Regulations, 2011 CFR

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    ... for certain beneficial owners. 240.14c-7 Section 240.14c-7 Commodity and Securities Exchanges... Rules and Regulations Under the Securities Exchange Act of 1934 Regulation 14c: Distribution of Information Pursuant to Section 14(c) § 240.14c-7 Providing copies of material for certain beneficial...

  16. 17 CFR 240.14c-6 - False or misleading statements.

    Code of Federal Regulations, 2014 CFR

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  17. 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... Under the Securities Exchange Act of 1934 Regulation 14c: Distribution of Information Pursuant to Section 14(c) § 240.14c-3 Annual report to be furnished security holders. (a) If the information...

  18. 17 CFR 240.14c-6 - False or misleading statements.

    Code of Federal Regulations, 2013 CFR

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  19. 17 CFR 240.14c-7 - Providing copies of material for certain beneficial owners.

    Code of Federal Regulations, 2014 CFR

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  20. 17 CFR 240.14c-4 - Presentation of information in information statement.

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  1. 17 CFR 240.14c-3 - Annual report to be furnished security holders.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... security holders. 240.14c-3 Section 240.14c-3 Commodity and Securities Exchanges SECURITIES AND EXCHANGE... Under the Securities Exchange Act of 1934 Regulation 14c: Distribution of Information Pursuant to Section 14(c) § 240.14c-3 Annual report to be furnished security holders. (a) If the information...

  2. 17 CFR 240.14c-6 - False or misleading statements.

    Code of Federal Regulations, 2010 CFR

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  3. 17 CFR 240.14c-6 - False or misleading statements.

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    .... 240.14c-6 Section 240.14c-6 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION... Securities Exchange Act of 1934 Regulation 14c: Distribution of Information Pursuant to Section 14(c) § 240.14c-6 False or misleading statements. (a) No information statement shall contain any statement...

  4. 17 CFR 240.14c-7 - Providing copies of material for certain beneficial owners.

    Code of Federal Regulations, 2013 CFR

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    ... for certain beneficial owners. 240.14c-7 Section 240.14c-7 Commodity and Securities Exchanges... Rules and Regulations Under the Securities Exchange Act of 1934 Regulation 14c: Distribution of Information Pursuant to Section 14(c) § 240.14c-7 Providing copies of material for certain beneficial...

  5. 17 CFR 240.14c-4 - Presentation of information in information statement.

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  6. 17 CFR 240.14c-3 - Annual report to be furnished security holders.

    Code of Federal Regulations, 2014 CFR

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    ... security holders. 240.14c-3 Section 240.14c-3 Commodity and Securities Exchanges SECURITIES AND EXCHANGE... Under the Securities Exchange Act of 1934 Regulation 14c: Distribution of Information Pursuant to Section 14(c) § 240.14c-3 Annual report to be furnished security holders. (a) If the information...

  7. 17 CFR 240.14c-6 - False or misleading statements.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    .... 240.14c-6 Section 240.14c-6 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION... Securities Exchange Act of 1934 Regulation 14c: Distribution of Information Pursuant to Section 14(c) § 240.14c-6 False or misleading statements. (a) No information statement shall contain any statement...

  8. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  10. 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.

  11. 14C-urea breath test in C pylori gastritis.

    PubMed Central

    Rauws, E A; Royen, E A; Langenberg, W; Woensel, J V; Vrij, A A; Tytgat, G N

    1989-01-01

    14C-urea breath test was used to detect Campylobacter pylori colonisation in 129 consecutive non-ulcer dyspepsia patients. Fasting patients were given 3 microCi (110 kBq) of 14C-labelled urea after a test meal. Breath samples were collected at 10 minute intervals for 90 minutes and the C-14 activity was counted on a liquid scintillation analyser. Urea derived 14CO2 appears in the exhaled breath of Campylobacter pylori culture positive individuals within 20-30 minutes. Likelihood analysis revealed a most favourable cut off level of [0.07% dose 14C-urea/mmol CO2] multiplied by body weight at t = 40 minutes, to separate culture positive from culture negative subjects. Using this upper limit of normal, a positive likelihood ratio of 50 and a negative likelihood ratio of 0.05 was calculated. Sensitivity of the test was 95% and specificity 98%. The 14C-urea breath test is a simple, sensitive and non-invasive test, that detects viable C pylori microorganism and semiquantitatively assesses the bacterial load of C pylori colonisation. Administration of a single dose of colloidal bismuth subcitrate resulted in a rapid decrease in 14CO2 excretion, so this test can be used to confirm eradication of the bacterium in therapeutic trials without endoscopy, or need for culture. PMID:2753404

  12. 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.

  13. 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.

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

    EPA Science Inventory

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

  15. Advances in cosmogenic surface exposure dating: Using combined in situ 14C-10Be analysis for deglaciation scenarios

    NASA Astrophysics Data System (ADS)

    Hippe, Kristina; Ivy-Ochs, Susan; Kober, Florian; Christl, Marcus; Fogwill, Christopher; Turney, Chris; Rood, Dylan; Lupker, Maarten; Schlücher, Christian; Wieler, Rainer

    2016-04-01

    combined with in situ 14C and 10Be analysis. While modelling results revealed a major reorganization of the ice streams over the last 20 ka, cosmogenic nuclide data from glacial erratics were used to reconstruct past terrestrial ice surface elevations. Consistently younger in situ 14C ages compared to 10Be ages, are interpreted as evidence for complex exposure histories. Different exposure scenarios created from the in situ 14C-10Be nuclide inventory agree on the occurrence of an extended ice cover on the dated erratics after initial deposition, followed by subsequent re-exposure. References: [1] Hippe et al. (2014), Quat. Geochronol. 19, 14-26. [2] Fogwill et al. (2014), Antarct. Sci. 26, 674-686.

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

    SciTech Connect

    Kashgarian, M; Guilderson, T P

    2001-02-23

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

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

    PubMed Central

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

    1972-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    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.

  19. Complete Genome Sequence of the Thermophilic, Piezophilic, Heterotrophic Bacterium Marinitoga piezophila KA3

    SciTech Connect

    Lucas, Susan; Han, James; Lapidus, Alla L.; Cheng, Jan-Fang; Goodwin, Lynne A.; Pitluck, Sam; Peters, Lin; Mikhailova, Natalia; Teshima, Hazuki; Detter, J. Chris; Han, Cliff; Tapia, Roxanne; Land, Miriam L; Hauser, Loren John; Kyrpides, Nikos C; Ivanova, N; Pagani, Ioanna; Vannier, Pauline; Oger, Phil; Bartlett, Douglas; Noll, Kenneth M; Woyke, Tanja; Jebbar, Mohamed

    2012-01-01

    Marinitoga piezophila KA3 is a thermophilic, anaerobic, chemoorganotrophic, sulfur-reducing bacterium isolated from the Grandbonum deep-sea hydrothermal vent site at the East Pacific Rise (13 degrees N, 2,630-m depth). The genome of M. piezophila KA3 comprises a 2,231,407-bp circular chromosome and a 13,386-bp circular plasmid. This genome was sequenced within Department of Energy Joint Genome Institute CSP 2010.

  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 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

  2. 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.

  3. 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. PMID:26095095

  4. 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.

  5. Bioproduction of [14C]ochratoxin A in submerged culture.

    PubMed Central

    Lillehoj, E B; Aalund, O; Hald, B

    1978-01-01

    A number of Aspergillus and Penicillium species were tested for production of ochratoxin A (OA) in several media. After 8 days of static incubations of submerged cultures at 28 degrees C, toxin yields of 25 and 30 micrograms/ml were obtained with Aspergillus alliaceus NRRL 4181 in Ferreirás and 2% yeast extract-4% sucrose media, respectively. However, the largest production observed in the preliminary screening was 54 micrograms/ml; this highest level was produced by A. sulphureus NRRL 4077 in a modified Czapek solution. The medium contained the basal salts and sucrose of Czapek plus urea (3%) and corn steep liquor (0.5% solids). A time study of toxin production demonstrated maximum yield of 350 micrograms/ml by the A. sulphureus isolate in the modified Czapek medium after 11 days of static incubation at 28 degrees C. The optimal production conditions were employed in additional tests designed to measure the efficiency of 14C incorporation from sodium [1-14C]-acetate into OA. Samples (20 microCi) of sodium acetate were added to separate culture flasks at 24-h intervals during the initial 9 days of the fermentation. Addition of [14C]acetate on day 4 of incubation provided the maximum yield of labeled OA. The highest specific activity of labeled toxin obtained was 0.07 microCi/mg of OA and the maximum incorporation rate of labeled acetate was 5.3%. PMID:727787

  6. 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.

  7. 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.

  8. 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.

  9. Reconstruction of the Late Quaternary Glaciation of the Macha Khola valley (Gorkha Himal, Nepal) using relative and absolute ( 14C, 10Be, dendrochronology) dating techniques

    NASA Astrophysics Data System (ADS)

    Zech, W.; Glaser, B.; Abramowski, U.; Dittmar, C.; Kubik, P. W.

    2003-11-01

    Late Quaternary glacier fluctuations in the Macha Khola valley (Gorkha Himal, Nepal) were reconstructed using relative and absolute dating techniques. Our results indicate that younger moraine complexes were left by Late Holocene (<1.7 cal. ka BP), mid-Holocene (ca 3 cal. ka BP), and Lateglacial (ca 13 cal. ka BP) ice advances. Older Late Quaternary glacier advances occurred during Marine Oxygen Isotope Stages (MIS) 2 and 3-4. No relics of Middle or Early Pleistocene glaciations could be found. During MIS 3-4, glaciers advanced down to an altitude of at least 2150 m a.s.l., corresponding to an ELA depression of approximately 1300 m. At about 3500 m a.s.l., the MIS 2 Macha Khola glacier reached almost the thickness of the former MIS 3-4 glacier and retreated some time before 17.9 cal. ka BP. The Lateglacial glacier advanced again several times to altitudes between 2450 and 3400 m a.s.l. The mid-Holocene glaciers extended much farther down-valley than the Late Holocene ones. Dendrochronological data of Abies spectabilis suggested several periods of unfavourable growth conditions especially at the beginning of the 19th (1820) and 20th (1905) centuries.

  10. 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.

  11. 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.

  12. Low-level (submicromole) environmental 14C metrology

    NASA Astrophysics Data System (ADS)

    Currie, L. A.; Kessler, J. D.; Marolf, J. V.; McNichol, A. P.; Stuart, D. R.; Donoghue, J. C.; Donahue, D. J.; Burr, G. S.; Biddulph, D.

    2000-10-01

    Accelerator mass spectrometry (AMS) measurements of environmental 14C have been employed during the past decade at the several micromole level (tens of μg carbon), but advanced research in the atmospheric and marine sciences demands still higher (μg) sensitivity, an extreme example being the determination of 14C in elemental or "black" carbon (BC) at levels of 2-10 μg per kg of Greenland snow and ice (Currie et al., 1998). A fundamental limitation for 14C AMS is Poisson counting statistics, which sets in at about 1 μg modern-C. Using the small sample (25 μg) AMS target preparation facility at NOSAMS (Pearson et al., 1998), and the microsample combustion-dilution facility at NIST, we have demonstrated an intrinsic modern-C quantification limit ( mQ) of ca. 0.9 μg, based on a 1-parameter fit to the empirical AMS variance function. (For environmental 14C, the modern carbon quantification limit is defined as that mass ( mQ) corresponding to 10% relative standard deviation (rsd) for the fraction of modern carbon, σ( fM)/ fM.) Stringent control, required for quantitative dilution factors (DL), is achieved with the NIST on-line manometric/mass spectrometry facility that compensates also for unsuspected trace impurities from vigorous chemical processing (e.g., acid digestion). Our current combustion blank is trivial (mean: 0.16 ± 0.02 μg C, n=13) but lognormally distributed (dispersion [σ]: 0.07 ± 0.01 μg). An iterative numerical expression is introduced to assess the quantitative impacts of fossil and modern carbon blank components on mQ; and a new "clean chemistry" BC processing system is described for the minimization of such blanks. For the assay of soot carbon in Greenland snow/ice, the overall processing blank has been reduced from nearly 7 μg total carbon to less than 1 μg, and is undetectable for BC.

  13. 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

  14. 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.

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

    PubMed

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

    2006-11-01

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

  16. 14C Concentrations in the Northern Atlantic and Nordic Seas

    NASA Astrophysics Data System (ADS)

    Nadeau, M.-J.; Grootes, P. M.; Erlenkeuser, H.

    2003-04-01

    We report here more than 450 new Δ14C results from water samples from the North Atlantic and the Nordic Seas measured at the Leibniz-Labor, Christian-Albrechts Universität, Kiel, using accelerator mass spectrometry. The water samples were collected during three cruises of the RV Meteor: M36 in 1996 (65 measurements, 6 stations), M39 in 1997 (217 measurements, 11 stations) and M50 in 2001 (189 measurements, 10 stations). These results are compared to those of previous sampling campaigns: GEOSECS (1972) and TTO (1981) and of samples obtained from previous cruises of the RV Meteor (M18 in 1991 and M30 in 1994) measured by decay counting at the Institut für Umweltphysik in Heidelberg. Several stations from the cruise M50 are located along the WOCE A02 line from the western entrance of the English Channel to the tip of Newfoundland/Grand Banks. This transect also analysed during the M30 (1994) campaign provides the evolution of the penetration of atmospheric bomb 14C into these waters over a seven year period. Other samples were taken in the Labrador Sea, and North and South of Iceland. Comparison with CFC measurements, for some of the stations, also provides an insight in the penetration of both tracers into the ocean.

  17. 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.

  18. Cholestyramine-enhanced fecal elimination of carbon-14 in rats after administration of ammonium (/sup 14/C)perfluorooctanoate or potassium (/sup 14/C)perfluorooctanesulfonate

    SciTech Connect

    Johnson, J.D.; Gibson, S.J.; Ober, R.E.

    1984-12-01

    After a single intravenous dose of ammonium (/sup 14/C)perfluorooctanoate (( /sup 14/C)PFO, 13.3 mg/kg) or of potassium (/sup 14/C)perfluorooctanesulfonate (( /sup 14/C)PFOS, 3.4 mg/kg) to rats, cholestyramine fed daily as a 4% mixture in feed was shown to increase the total carbon-14 eliminated via feces and to decrease liver concentration of carbon-14. Rats were fed cholestyramine in feed for 14 days after administration of (/sup 14/C)PFO and for 21 days after administration of (/sup 14/C)PFOS. Control rats were administered radiolabeled fluorochemical but were not treated with cholestyramine. Cholestyramine treatment increased mean cumulative carbon-14 elimination in feces by 9.8-fold for rats administered (/sup 14/C)PFO and by 9.5-fold for rats administered (/sup 14/C)PFOS. After (/sup 14/C)PFO, a mean of 4% of the dose of carbon-14 was in liver of cholestyramine-treated rats at 14 days versus 7.6% in control rats; after (/sup 14/C)PFOS, 11.3% of the dose was in liver at 21 days versus 40.3% in control rats. After administration of either radiolabeled compound, plasma and red blood cell carbon-14 concentrations, which were relatively lower than liver concentrations, were also significantly reduced by cholestyramine treatment.

  19. 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

  20. The distribution of 14c from [U-14c]glucose in mice using whole-body autoradiography.

    PubMed

    Shimada, M; Kihara, T; Watanabe, M; Kurimoto, K

    1976-04-01

    Tissue distribution of radioactive carbon from [U-14C]glucose in the mouse in vivo was studied by whole-body autoradiography. The mice were frozen with Dry-Ice-acetone at 0.5, 1, 5 and 30 min, 1 and 24 hr and 1 and 3 weeks after intraperitoneal injection of [U-14C]glucose. Whole-sagittal sections of the frozen mouse, obtained by using a microtome in a cryostat, were dried in a cryostat and autoradiographed. The resulting dry autoradiographs are called untreated autoradiographs in the present work. The sections were then fixed in cold 6% (w/v) HClO4, dried at room temperature and again autoradiographed. Autoradiographs that have undergone this process are referred to as treated autoradiographs. In both untreated and treated autoradiographs, within 1 min following injection of the labeled glucose, the abdominal cavity had the highest autoradiographic density. At 1 hr, density became highest in Harder's, sublingual and duodenal glands, large intestinal mucosa and tongue, and after 3 weeks, no autoradiographic denisty was present. PMID:1270794

  1. Optical Dating of Marine Sediment From ODP Core 658B - An Intercomparison With an Independent AMS 14C Chronology

    NASA Astrophysics Data System (ADS)

    Armitage, S. J.; Stokes, S.; Henderson, G.

    2004-12-01

    We demonstrate the potential of optical dating of detrital quartz silt from marine sediments via a chronological intercomparison for samples from ODP Site 658, which range in age from 0 to 140ka. ODP Site 658 is located off Cap Blanc, Mauritania. It has a high sedimentation rate (18 cm/ka), due to high regional surface productivity and large inputs of windblown Africa dust. This windblown dust provides both the substrate for optical dating and a proxy for North African aridity. The AMS 14C chronology is based on monospecific foraminiferal (Globigerinoides bulloides) samples. This is the first large-scale, systematic application of optical dating to marine sediment, and demonstrates that the technique has considerable potential for the age estimation of otherwise undateable deep-sea material. Optical dating techniques measure the total ionising radiation dose that a mineral grain has received since its last exposure to sunlight (i.e. during burial). The resulting optical age is essentially calibrated via a knowledge of the environmental dose rate, yielding the burial period. The environmental dose rate is derived from the decay of radioisotopes in the sediment (K, U and Th). In terrestrial sediments, the uranium and thorium decay chains can be assumed to be in equilibrium. In the marine realm this assumption is not valid, and unsupported uranium decay series exist on deposition. Consequently, the environmental dose rate changes with sample age. This problem was circumvented by quantifying U and Th decay series disequilibrium, using an MC-ICP-MS. The evolution of the environmental dose rate during burial was modelled, and ages for each sample calculated. The 14C and optical ages are generally in good agreement, indicating that the latter technique can provide equally robust chronologies for marine sediments. Although the maximum age attainable using optical dating is sample specific, the dose rate and luminescence characteristics of the samples analysed in this study

  2. 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

  3. Structure of 19O from 9Be + 14C

    NASA Astrophysics Data System (ADS)

    Dungan, R.; Tabor, S. L.; Vonmoss, J.; Morrow, S.; Abromeit, B.; Kravvaris, K.; Parker, J. J., IV; Tai, P. L.; Tripathi, Vandana; Volya, A.

    2015-10-01

    The 9Be(14C, α γ) reaction at ELab = 30 and 35 MeV was used to study excited states of 19O. The Florida State University (FSU) γ detector array was used to detect γ radiation in coincidence with charged particles detected and identified with a silicon ΔE-E particle telescope. From α- γ- γ coincidences five new states of 19O have been identified and an additional three new γ transitions among known states have been observed. An additional previously unobserved state has been marked tentative from α- γ coincidences. These results are compared to shell model calculations using the USDA, WBP, and PSDU interactions. This work was supported in part by U.S. National Science Foundation Grant NSF-14-01574.

  4. 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.

  5. 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.

  6. Sedimentation history of the northern North Sea Margin during the last 150 ka

    NASA Astrophysics Data System (ADS)

    Lekens, W. A. H.; Haflidason, H.; Sejrup, H. P.; Nygard, A.; Richter, T.; Vogt, C.; Frederichs, T.

    2009-03-01

    The Norwegian Channel Ice Stream (NCIS) is one the defining features of the Fennoscandian icesheet. Still little is known of the detailed dynamics of this ice stream in relation to regional changes in ice cover, paleoceanographic and climatic changes. Sedimentological data from core MD99-2283 in combination with seismic data allow a detailed chronological reconstruction of the outbuilding of the margin and the ice extent in southern Scandinavia through the last 150 ka. An integrated stratigraphy of the margin is presented and compared to the glacial history. Changes in the regional ice cover are reflected in the accumulation rates, the clay mineralogy, the coarse chalk fraction and the number of IRD >2 mm in core MD99-2283, while the sedimentation on the North Sea Fan as derived from seismic data provides direct evidence for the glacial activity at the shelf edge. Tentative evidence was found for two Early Weichselian glacial advances in southern Scandinavia and possibly Scotland at around 110 and 80 ka BP. From 42 cal ka BP the ice cover expanded in southern Fennoscandia and led to increased deposition on the margin and the occurrence of local melt water outbursts. Significantly increased accumulation rates, coarse chalk, local meltwater output and smectite occur during the ice expansion in the North Sea from around 34 cal ka BP. The main outbuilding phase of the NSF during the last glacial cycle occurred after 30 cal ka BP. From around 24 cal ka BP the NCIS became highly active and advanced at least three times prior to the final retreat from the shelf edge around 19.0 cal ka BP.

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

    SciTech Connect

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

    1990-10-01

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

  8. 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...

  9. 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.

  10. Pollen-based biome reconstructions for Colombia at 3000, 6000, 9000, 12 000, 15 000 and 18 000 14C yr ago: Late Quaternary tropical vegetation dynamics

    NASA Astrophysics Data System (ADS)

    Marchant, Robert; Behling, Hermann; Berrio, Juan-Carlos; Cleef, Antoine; Duivenvoorden, Joost; Hooghiemstra, Henry; Kuhry, Peter; Melief, Bert; Schreve-Brinkman, Elisabeth; van Geel, Bas; van der Hammen, Thomas; van Reenen, Guido; Wille, Michael

    2002-02-01

    Colombian biomes are reconstructed at 45 sites from the modern period extending to the Last Glacial Maximum (LGM). The basis for our reconstruction is pollen data assigned to plant functional types and biomes at six 3000-yr intervals. A reconstruction of modern biomes is used to check the treatment of the modern pollen data set against a map of potential vegetation. This allows the biomes reconstructed at past periods to be assessed relative to the modern situation. This process also provides a check on the a priori assignment of pollen taxa to plant functional types and biomes. For the majority of the sites, the pollen data accurately reflect the potential vegetation, even though much of the original vegetation has been transformed by agricultural practices. At 18 000 14C yr BP, a generally cool and dry environment is reflected in biome, assignments of cold mixed forests, cool evergreen forests and cool grassland-shrub; the latter extending to lower altitudes than presently recorded. This signal is strongly recorded at 15 000 and 12 000 14C yr BP, the vegetation at these times also reflecting a relatively cool and dry environment. At 9000 14C yr BP there is a shift to biomes thought to result from slightly cooler environmental conditions. This trend is reversed by 6000 14C yr BP; most sites, within a range of different environmental settings, recording a shift to more xeric biome types. There is an expansion of steppe and cool mixed-forest biomes, replacing tropical dry forest and cool grassland-shrub biomes, respectively. These changes in biome assignments from the modern situation can be interpreted as a biotic response to mid-Holocene climatic aridity. At 3000 14C yr BP the shift is mainly to biomes characteristic of slightly more mesic environmental conditions.There are a number of sites that do not change biome assignment relative to the modern reconstruction, although the affinities that these sites have to a specific biome do change. These anomalies are

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

    NASA Astrophysics Data System (ADS)

    Michalska, Danuta; Czernik, Justyna

    2015-10-01

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

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

    SciTech Connect

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

    1989-08-01

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

  13. 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.

  14. Elevated BP after AKI.

    PubMed

    Hsu, Chi-Yuan; Hsu, Raymond K; Yang, Jingrong; Ordonez, Juan D; Zheng, Sijie; Go, Alan S

    2016-03-01

    The connection between AKI and BP elevation is unclear. We conducted a retrospective cohort study to evaluate whether AKI in the hospital is independently associated with BP elevation during the first 2 years after discharge among previously normotensive adults. We studied adult members of Kaiser Permanente Northern California, a large integrated health care delivery system, who were hospitalized between 2008 and 2011, had available preadmission serum creatinine and BP measures, and were not known to be hypertensive or have BP>140/90 mmHg. Among 43,611 eligible patients, 2451 experienced AKI defined using observed changes in serum creatinine concentration measured during hospitalization. Survivors of AKI were more likely than those without AKI to have elevated BP-defined as documented BP>140/90 mmHg measured during an ambulatory, nonemergency department visit-during follow-up (46.1% versus 41.2% at 730 days; P<0.001). This difference was evident within the first 180 days (30.6% versus 23.1%; P<0.001). In multivariable models, AKI was independently associated with a 22% (95% confidence interval, 12% to 33%) increase in the odds of developing elevated BP during follow-up, with higher adjusted odds with more severe AKI. Results were similar in sensitivity analyses when elevated BP was defined as having at least two BP readings of >140/90 mmHg or those with evidence of CKD were excluded. We conclude that AKI is an independent risk factor for subsequent development of elevated BP. Preventing AKI during a hospitalization may have clinical and public health benefits beyond the immediate hospitalization. PMID:26134154

  15. Photolysis of 14C-sulfadiazine in water and manure.

    PubMed

    Sukul, Premasis; Lamshöft, Marc; Zühlke, Sebastian; Spiteller, Michael

    2008-03-01

    Photolysis of 14C-sulfadiazine in aqueous solution under simulated sunlight followed first-order kinetics. The impact of H2O2, humic acid, fulvic acid and acetone to enhance the photodegradation of sulfadiazine (SDZ) was studied. Six photoproducts, 4-OH-SDZ, 5-OH-SDZ, N-formyl-SDZ, 4-[2-iminopyrimidine-1(2H)-yl] aniline, 2-aminopyrimidine, and aniline were identified. Extrusion of SO2 was found to be the main degradation process during irradiation. These photoproducts can occur in water and soil upon sunlight exposure, when soil is treated with SDZ contained in manure. Due to photodegradation the experimental half-life of the SDZ in water was 32h and in the presence of photosensitizers the half-life values were 19.3-31.4h, 17.2-31.4h, 12.6-29.8h, and 3.8-30.7h for H2O2, humic acid, fulvic acid, and acetone, respectively depending on the concentration of the photosensitizers. The presence of photosensitizers markedly reduced SDZ persistence, indicating that indirect photolytic processes are important factors governing the photodegradation of SDZ in aqueous environments. Investigation revealed further persistence behavior of SDZ in manure. The half-life value of SDZ in manure was 158h. PMID:18076971

  16. 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.

  17. 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.

  18. Degredation of [{sup 14}C]-propargite in soil

    SciTech Connect

    Comezoglu, S.N.; Ly, V.T.; Wu, J.

    1996-10-01

    The degradation of {sup 14}C-labeled propargite in soil was investigated in three different test conditions, namely, aerobic soil, anaerobic soil, aerobic aquatic, and anaerobic aquatic. All studies were conducted at {approximately}25{degrees}C in the dark with treatment rates of either 5 ppm or 6 ppm and were conducted for a period of one year except the anaerobic soil and aerobic aquatic study which were conducted for two months and one month, respectively. The apparent T{sub 1/2} values observed were {approximately}38 days, {approximately}47 days, {approximately}67 days and {approximately}64 days for aerobic aquatic, anaerobic aquatic, aerobic soil and anaerobic soil studies, respectively. The soil and test systems were extracted with organic solvent followed by radiocounting and chromatographic analysis. Major metabolites were isolated and identified by co-chromatography as well as mass spectrometry (GC/MS and/or LC/MS). A number of products were detected which included p-tertiary butylphenoxy cyclohexanol (TBPC), 2-[4-(2-hydroxycyclohexoxy) phenyl]-2,2-dimethyl acetic acid (TBPC-acid), p-tertiarybutyl phenol (PTBP), and 2-(p-tertiarybutyl phenoxy) cyclohexanol sulfuric acid as the identified major products. The averaged overall recoveries for the test substance in all studies were excellent (>90%). Data indicated that the propargite degraded at a moderate rate in hydrosoils either aerobically or anaerobically while in terrestrial soil, the degradation was slowed down after several months of incubation.

  19. Distribution of 14C cylindrospermopsin in vivo in the mouse.

    PubMed

    Norris, R L; Seawright, A A; Shaw, G R; Smith, M J; Chiswell, R K; Moore, M R

    2001-01-01

    Radiolabelled 14C cylindrospermopsin (CYN) has been prepared and used to investigate the distribution and excretion of CYN in vivo in male Quackenbush mice. At a dose of 0.2 mg/kg (i.e., approx. median lethal dose) the following mean (SD) urinary and faecal recoveries (cumulative) were obtained, respectively: (0-6 hours, n = 4) 48.2 (29.3)%, 11.9 (21.4)%; (0-12 hours, n = 12) 66.0 (27.1)%, 5.7 (5.6)%; (0-24 hours, n = 12) 68.4 (26.7)%, 8.5 (8.1)%. Mean (SD) recoveries from livers at 6 hours were 20.6 (6.4)% (n = 4), at 48 hours 13.1 (7.7)% (n = 8), and 5-7 days were 2.1 (2.1)% (n = 8). A substantial amount (up to 23%) can be retained in the liver for up to 48 hours with a lesser amount retained in the kidneys. The excretion patterns show substantial interindividual variability between predominantly faecal or urinary excretion, but these patterns are not related in any simple manner to the outcome in terms of toxicity. There is at least one methanol-extractable metabolite as well as a nonmethanol-extractable metabolite in the liver. The methanol-extractable metabolite was not found in the kidney and is more hydrophilic than CYN itself on reverse phase. PMID:11769247

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  1. 14C-labeled substrate catabolism by human diploid fibroblasts derived from infants and adults

    SciTech Connect

    Rhead, W.J.; Moon, A.; Roettger, V.; Henkle, K.

    1985-10-01

    Untransformed diploid skin fibroblasts from eight normal adults, aged 24 to 74 years, catabolized several 14C-labeled substrates less effectively than cells from ten normal male infants. 14C-labeled substrate metabolism was quantitated either by measuring the evolution of 14CO2 from the 14C-labeled compounds or the incorporation of 14C into cellular protein via transamination of tricarboxylic acid cycle intermediates derived from the 14C-labeled substrates. With these methods, adult cells catabolized (1-14C)butyrate, (1-14C)octanoate, and 1-(2-14C)leucine at rates 44 to 64% of those found in infant cells. The oxidation of (1,4-14C)succinate and (U-14C)malate was identical in both infant and adult cells, while (2,3-14C)succinate catabolism was mildly decreased in adult cells (65-80% of control). These observations parallel those made in rat tissues and confirm that the same phenomenon occurs in cultured human fibroblasts.

  2. Review: Bilirubin pKa studies; new models and theories indicate high pKa values in water, dimethylformamide and DMSO

    PubMed Central

    2010-01-01

    Background Correct aqueous pKa values of unconjugated bilirubin (UCB), a poorly-soluble, unstable substance, are essential for understanding its functions. Our prior solvent partition studies, of unlabeled and [14C] UCB, indicated pKa values above 8.0. These high values were attributed to effects of internal H-bonding in UCB. Many earlier and subsequent studies have reported lower pKa values, some even below 5.0, which are often used to describe the behavior of UCB. We here review 18 published studies that assessed aqueous pKa values of UCB, critically evaluating their methodologies in relation to essential preconditions for valid pKa measurements (short-duration experiments with purified UCB below saturation and accounting for self-association of UCB). Results These re-assessments identified major deficiencies that invalidate the results of all but our partition studies. New theoretical modeling of UCB titrations shows remarkable, unexpected effects of self-association, yielding falsely low pKa estimates, and provides some rationalization of the titration anomalies. The titration behavior reported for a soluble thioether conjugate of UCB at high aqueous concentrations is shown to be highly anomalous. Theoretical re-interpretations of data in DMSO and dimethylformamide show that those indirectly-derived aqueous pKa values are unacceptable, and indicate new, high average pKa values for UCB in non-aqueous media (>11 in DMSO and, probably, >10 in dimethylformamide). Conclusions No reliable aqueous pKa values of UCB are available for comparison with our partition-derived results. A companion paper shows that only the high pKa values can explain the pH-dependence of UCB binding to phospholipids, cyclodextrins, and alkyl-glycoside and bile salt micelles. PMID:20350304

  3. Molecular Paleoclimate Reconstructions over the Last 9 ka from a Peat Sequence in South China

    PubMed Central

    Wang, Xinxin; Huang, Xianyu; Sachse, Dirk; Ding, Weihua; Xue, Jiantao

    2016-01-01

    To achieve a better understanding of Holocene climate change in the monsoon regions of China, we investigated the molecular distributions and carbon and hydrogen isotope compositions (δ13C and δD values) of long-chain n-alkanes in a peat core from the Shiwangutian (SWGT) peatland, south China over the last 9 ka. By comparisons with other climate records, we found that the δ13C values of the long-chain n-alkanes can be a proxy for humidity, while the δD values of the long-chain n-alkanes primarily recorded the moisture source δD signal during 9–1.8 ka BP and responded to the dry climate during 1.8–0.3 ka BP. Together with the average chain length (ACL) and the carbon preference index (CPI) data, the climate evolution over last 9 ka in the SWGT peatland can be divided into three stages. During the first stage (9–5 ka BP), the δ13C values were depleted and CPI and Paq values were low, while ACL values were high. They reveal a period of warm and wet climate, which is regarded as the Holocene optimum. The second stage (5–1.8 ka BP) witnessed a shift to relatively cool and dry climate, as indicated by the more positive δ13C values and lower ACL values. During the third stage (1.8–0.3 ka BP), the δ13C, δD, CPI and Paq values showed marked increase and ACL values varied greatly, implying an abrupt change to cold and dry conditions. This climate pattern corresponds to the broad decline in Asian monsoon intensity through the latter part of the Holocene. Our results do not support a later Holocene optimum in south China as suggested by previous studies. PMID:27505008

  4. Molecular Paleoclimate Reconstructions over the Last 9 ka from a Peat Sequence in South China.

    PubMed

    Wang, Xinxin; Huang, Xianyu; Sachse, Dirk; Ding, Weihua; Xue, Jiantao

    2016-01-01

    To achieve a better understanding of Holocene climate change in the monsoon regions of China, we investigated the molecular distributions and carbon and hydrogen isotope compositions (δ13C and δD values) of long-chain n-alkanes in a peat core from the Shiwangutian (SWGT) peatland, south China over the last 9 ka. By comparisons with other climate records, we found that the δ13C values of the long-chain n-alkanes can be a proxy for humidity, while the δD values of the long-chain n-alkanes primarily recorded the moisture source δD signal during 9-1.8 ka BP and responded to the dry climate during 1.8-0.3 ka BP. Together with the average chain length (ACL) and the carbon preference index (CPI) data, the climate evolution over last 9 ka in the SWGT peatland can be divided into three stages. During the first stage (9-5 ka BP), the δ13C values were depleted and CPI and Paq values were low, while ACL values were high. They reveal a period of warm and wet climate, which is regarded as the Holocene optimum. The second stage (5-1.8 ka BP) witnessed a shift to relatively cool and dry climate, as indicated by the more positive δ13C values and lower ACL values. During the third stage (1.8-0.3 ka BP), the δ13C, δD, CPI and Paq values showed marked increase and ACL values varied greatly, implying an abrupt change to cold and dry conditions. This climate pattern corresponds to the broad decline in Asian monsoon intensity through the latter part of the Holocene. Our results do not support a later Holocene optimum in south China as suggested by previous studies. PMID:27505008

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    Active tectonics studies are often limited by difficulties in accurately and precisely dating Late Quaternary alluvial deposits that commonly lack organic matter or date beyond the 14C dating limit. This is illustrated at a site called Fidan, in arid southern Jordan, where a series of alluvial fans are laterally offset by the southern Dead Sea fault. Geodetic, geomorphic and geologic studies converge to a fault slip rate of 5 ± 2 mm/a. Yet, Late Pleistocene slip rate at Fidan cover a wide range due to the dispersion of 10Be cosmogenic radionuclide (CRN) ages. The maximum slip rate since ~100 ka is up to a value of 11 mm/a, possibly suggesting significant variations in fault activity with time. In order to reduce the uncertainty on the Late Pleistocene slip rate and draw further conclusions regarding the fault seismic behavior, we implement complementary dating using optically stimulated luminescence (OSL) techniques on both quartz and K-feldspar minerals and using 14C when possible. OSL measurements include a newly developed technique called post-infra-red infra-red stimulated luminescence at 290°C (pIR290). We extensively sampled surface levels F2 and F4, digging ~50-cm deep pits into the geomorphic surfaces. Annual dose rates were determined in the laboratory from both geochemical analysis of the sediment and gamma-ray spectrometry. Due to sediment heterogeneity, we consider gamma-ray spectrometry as more reliable because it is based on a larger volume of sediment. Quartz OSL ages and preliminary pIR290 results on K-feldspars give consistent Early Holocene ages of 9-14 ka for F2, also in agreement with a 14C age of 13 ka from a landsnail shell. 10Be CRN exposure ages on F2 were significantly older, with 37 ± 4 ka, probably due to inheritance. On F4, 10Be CRN exposure ages showed a scattered distribution, from ~50 ka to ~120 ka, with most samples comprised in the mean interval of 87 ± 26 ka. Quartz OSL ages from 5 locations on F4 are comprised between 32 ± 3

  6. 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

  7. 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. PMID:18308434

  8. The fate of 14C in glucose 6-phosphate synthesized from [1-14C]Ribose 5-phosphate by enzymes of rat liver.

    PubMed Central

    Williams, J F; Clark, M G; Blackmore, P F

    1978-01-01

    1. Glucose 5-phosphate was synthesized from ribose 5-phosphate by an enzyme extract prepared from an acetone-dried powder of rat liver. Three rates of ribose 5-phosphate utilization were observed during incubation for 17 h. An analysis of intermediates and products formed throughout the incubation revealed that as much as 20% of the substrate carbon could not be accounted for. 2. With [1-14C]ribose 5-phosphate as substrate, the specific radioactivity of [14C]glucose 6-phosphate formed was determined at 1, 2, 5 and 30 min and 3, 8 and 17 h. It increased rapidly to 1.9-fold the initial specific radioactivity of [1-14C]ribose 5-phosphate at 3 h and then decreased to a value approximately equal to that of the substrate at 6 h, and finally at 17 h reached a value 0.8-fold that of the initial substrate [1-14C]ribose 5-phosphate. 3. The specific radioactivity of [14C]ribose 5-phosphate decreased to approx. 50% of its inital value during the first 3 h of the incubation and thereafter remained unchanged. 4. The distribution of 14C in the six carbon atoms of [14C]glucose 6-phosphate formed from [1-14C]ribose 5-phosphate at 1, 2, 5 and 30 min and 3, 8 and 17 h was determined. The early time intervals (1--30 min) were characterized by large amounts of 14C in C-2 and in C-6 and with C-1 and C-3 being unlabelled. In contrast, the later time intervals (3--17 h) were characterized by the appearance of 14C in C-1 and C-3 and decreasing amounts of 14C in C-2 and C-6. 5. It is concluded that neither the currently accepted reaction sequence for the non-oxidative pentose phosphate pathway nor the 'defined' pentose phosphate-cycle mechanism can be reconciled with the labelling patterns observed in glucose 6-phosphate formed during the inital 3 h of the incubation. PMID:728109

  9. Impact of climate variability on terrestrial environment in Western Europe between 45 and 9 kyr cal. BP: vegetation dynamics recorded by the Bergsee Lake (Black Forest, Germany).

    NASA Astrophysics Data System (ADS)

    Duprat-Oualid, Fanny; Begeot, Carole; Rius, Damien; Millet, Laurent; Magny, Michel

    2016-04-01

    Between 9 and 45 kyr cal. BP, two great transitions lead the global climate system to evolve from the Last-Glacial period (115-14.7 kyr cal. BP), to two successive warmer periods, the Late-Glacial Interstadial (14.7-11.7 kyr cal. BP) and the Holocene (11.7-0 kyr cal. BP). δ18O variations recorded in Greenland ice cores (GRIP & NGRIP) revealed high frequency climate variability within the Last Glacial. These reference isotopic records highlighted a succession of centennial-to-millennial warm/cold events, the so-called Greenland Interstadials (GI) and Greenland Stadials (GS). The number continental records about the period 14.7-0 kyr cal. BP is substantial. This allowed to understand the vegetation dynamics in response to climate changes this period at the North-Atlantic scale. However, sequences covering the glacial period (beyond 20 kyr cal.BP) remain rare, because of hiatuses mostly due to local glaciers. Therefore, sedimentary continuous records of vegetation dynamics are still needed to better understand climate changes during the Last Glacial in Western Europe (Heiri et al. 2014). Here we present a new high-resolution pollen record from Lake Bergsee (47°34'20''N, 7°56'11''E, 382 m a.s.l). This lake is located south of Black Forest and north of the Alps, beyond the zone of glaciers maximal extension. Therefore it could have recorded the whole last climatic cycle, i.e. 120-0 kyr cal. BP. In 2013, a 29 m long core was extracted from the Bergsee. According to the depth-age model based on 14C AMS dating and the Laacher See Tephra (LST), the record spans continuously at least the last 45 kyrs. The first series of pollen analysis, focused on the 45-9 kyr cal. BP time window, allows us to reconstruct a precise, faithful and continuous vegetation history at the centennial scale. This high temporal resolution enabled to assess the response of vegetation to secular climate events (e.g. GI-4 = 200 yrs). First, our results show that vegetation responded to climate

  10. 14C AMS measurements of the bomb pulse in N- and S-hemisphere tropical trees

    NASA Astrophysics Data System (ADS)

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

    1997-03-01

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

  11. Absorption, distribution and excretion of 14C-pilocarpine following oral administration to rats.

    PubMed

    Omori, Yasuhiro; Endo, Takuro; Hara, Yoshiki; Nishiyama, Masahiko; Midgley, Ian; Smart, Clair I; John, Alexandra J; Chasseaud, Leslie F; McBurney, Alan; John, Brian A

    2004-01-01

    The absorption, distribution and excretion of pilocarpine (CAS 92-13-7) were studied after single oral doses of 14C-pilocarpine hydrochloride (CAS 54-71-7) to the Sprague-Dawley rat, administered in aqueous solution mainly at a dose level of 0.3 mg/kg. Rats also received single intravenous doses at 0.3 mg/kg so as to compare 14C pharmacokinetics and excretion. The oral 14C-dose was rapidly and almost completely absorbed from the duodenum and small intestine within 30 min in the male rat and 14C concentrations in plasma declined biexponentially with a terminal half-life of about 9 h. Over the oral dosage range studied, i.e. 0.1-1.0 mg/kg, there was no evidence of significant non-proportionality for Cmax of 14C, whereas there was some such evidence for AUG24. Tissue 14C concentrations in male and pregnant female (Day 18) rats peaked at 0.5 h and mostly declined in parallel with those in the plasma. Excluding tissues concerned with drug absorption and elimination, 14C concentrations in most tissues were similar to, or lower than, those in the plasma. The extent of placental transfer of 14C was small and less than 0.09% of a maternal dose reached a foetus. 14C diffused into maternal milk at concentrations similar to those in the plasma. The 14C-dose was rapidly excreted in male rats, mostly in the urine (about 80%) during 6 h post dose. Recoveries of 14C in mass balance (excretion) studies were in the range 96-100%. There were no apparent gender differences in the disposition of 14C-pilocarpine in the rat. PMID:15112864

  12. (/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.

  13. (14C)acetate assimilation by a type I obligate methylotroph, Methylococcus capsulatus.

    PubMed Central

    Patel, R N; Hoare, S L; Hoare, D S; Taylor, B F

    1977-01-01

    Methanol and formate oxidation supported the assimilation of [14C]acetate by cell suspensions of Methylococcus capsulatus; oxidation of other primary alcohols, except ethanol, did not. The extent of [1-14C]acetate assimilation supported by methanol oxidation was decreased in the presence of primary alcohols, except ethanol. Potassium cyanide (0.33 mM) completely inhibited the oxidation of formate and its stimulation of [1-14C]acetate assimilation. The amount of [1-14C]acetate assimilation supported by methanol oxidation was significantly inhibited by cyanide. PMID:412469

  14. Ka Band Objects: Observation and Monitoring (KaBOOM)

    NASA Astrophysics Data System (ADS)

    Geldzahler, B.

    2012-09-01

    NASA has embarked on a path that will enable the implementation of a high power, high resolution X/Ka band radar system using widely spaced 12m antennas to better track and characterize near Earth objects and orbital debris. This radar system also has applications for cost effective space situational awareness. We shall demonstrate Ka band coherent uplink arraying with real-time atmospheric compensation using three 12m antennas at the Kennedy Space Center (KSC). Our proposed radar system can complement and supplement the activities of the Space Fence. The proposed radar array has the advantages of filling the gap between dusk and dawn and offers the possibility of high range resolution (4 cm) and high spatial resolution (?10 cm at GEO) when used in a VLBI mode. KSC was chosen because [a] of reduced implementation costs, [b] there is a lot of water vapor in the air (not Ka band friendly), and [c] the test satellites have a low elevation adding more attenuation and turbulence to the demonstration. If Ka band coherent uplink arraying can be made to work at KSC, it will work anywhere. We expect to rebaseline X-band in 2013, and demonstrate Ka band uplink arraying in 2014.

  15. 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...

  16. 17 CFR 240.14c-4 - Presentation of information in information statement.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 17 Commodity and Securities Exchanges 3 2010-04-01 2010-04-01 false Presentation of information in information statement. 240.14c-4 Section 240.14c-4 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION (CONTINUED) GENERAL RULES AND REGULATIONS, SECURITIES EXCHANGE ACT OF 1934 Rules and Regulations Under the Securities...

  17. 17 CFR 240.14c-4 - Presentation of information in information statement.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 17 Commodity and Securities Exchanges 3 2011-04-01 2011-04-01 false Presentation of information in... Section 14(c) § 240.14c-4 Presentation of information in information statement. (a) The information... type except that to the extent necessary for convenient presentation, financial statements and...

  18. 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.

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

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... COMMISSION (CONTINUED) GENERAL RULES AND REGULATIONS, SECURITIES EXCHANGE ACT OF 1934 Rules and Regulations... 17 Commodity and Securities Exchanges 3 2010-04-01 2010-04-01 false Annual report to be furnished... Section 14(c) § 240.14c-3 Annual report to be furnished security holders. (a) If the information...

  20. 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

  1. 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.

  2. Anatomically modern human in Southeast Asia (Laos) by 46 ka

    PubMed Central

    Demeter, Fabrice; Shackelford, Laura L.; Bacon, Anne-Marie; Duringer, Philippe; Westaway, Kira; Sayavongkhamdy, Thongsa; Braga, José; Sichanthongtip, Phonephanh; Khamdalavong, Phimmasaeng; Ponche, Jean-Luc; Wang, Hong; Lundstrom, Craig; Patole-Edoumba, Elise; Karpoff, Anne-Marie

    2012-01-01

    Uncertainties surround the timing of modern human emergence and occupation in East and Southeast Asia. Although genetic and archeological data indicate a rapid migration out of Africa and into Southeast Asia by at least 60 ka, mainland Southeast Asia is notable for its absence of fossil evidence for early modern human occupation. Here we report on a modern human cranium from Tam Pa Ling, Laos, which was recovered from a secure stratigraphic context. Radiocarbon and luminescence dating of the surrounding sediments provide a minimum age of 51–46 ka, and direct U-dating of the bone indicates a maximum age of ∼63 ka. The cranium has a derived modern human morphology in features of the frontal, occipital, maxillae, and dentition. It is also differentiated from western Eurasian archaic humans in aspects of its temporal, occipital, and dental morphology. In the context of an increasingly documented archaic–modern morphological mosaic among the earliest modern humans in western Eurasia, Tam Pa Ling establishes a definitively modern population in Southeast Asia at ∼50 ka cal BP. As such, it provides the earliest skeletal evidence for fully modern humans in mainland Southeast Asia. PMID:22908291

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

  4. Ka-band study: 1988

    NASA Technical Reports Server (NTRS)

    Layland, J. W.; Horttor, R. L.; Clauss, R. C.; Wilcher, J. H.; Wallace, R. J.; Mudgway, D. J.

    1989-01-01

    The Ka-band study team was chartered in late 1987 to bring together all the planning elements for establishing 32 GHz (Ka-band) as the primary downlink frequency for deep-space operation, and to provide a stable baseline from which to pursue that development. This article summarizes the results of that study at its conclusion in mid-1988, and corresponds to material presented to NASA's Office of Space Operations on July 14, 1988. For a variety of reasons, Ka-band is the right next major step in deep-space communications. It offers improved radio metric accuracy through reduced plasma sensitivity and increased bandwidth. Because of these improvements, it offers the opportunity to reduce costs in the flight radio system or in the DSN by allocating part of the overall benefits of Ka-band to this cost reduction. A mission scenario is being planned that can drive at least two and possibly all three of the DSN subnets to provide a Ka-band downlink capability by the turn of the century. The implementation scenario devised by the study team is believed to be feasible within reasonable resource expectations, and capable of providing the needed upgrade as a natural follow-on to the technology development which is already underway.

  5. 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.

  6. Excretion of 14C-edrophonium and its metabolites in bile

    PubMed Central

    Back, D. J.; Calvey, T. N.

    1972-01-01

    1. The metabolism and biliary excretion of 14C-edrophonium chloride was studied in Wistar rat. 2. Approximately 5% of the dose was recovered from bile in 6 hours. Most of the radioactivity was eliminated as 14C-edrophonium glucuronide. Small amounts of the unchanged drug were also detected in bile, particularly during the first hour after administration of the drug. 3. The concentration of 14C-edrophonium glucuronide in bile was approximately 15-20 times its concentration in plasma. 4. In contrast, the concentration of unchanged 14C-edrophonium was similar in bile and plasma. 5. Evidence is presented that unchanged 14C-edrophonium is transferred from plasma to bile via the peribiliary vascular plexus. PMID:5040663

  7. 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.

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

    USGS Publications Warehouse

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

    1998-01-01

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

  9. Early Holocene (8.6 ka) rock avalanche deposits, Obernberg valley (Eastern Alps): Landform interpretation and kinematics of rapid mass movement

    PubMed Central

    Ostermann, Marc; Sanders, Diethard; Ivy-Ochs, Susan; Alfimov, Vasily; Rockenschaub, Manfred; Römer, Alexander

    2012-01-01

    In the Obernberg valley, the Eastern Alps, landforms recently interpreted as moraines are re-interpreted as rock avalanche deposits. The catastrophic slope failure involved an initial rock volume of about 45 million m³, with a runout of 7.2 km over a total vertical distance of 1330 m (fahrböschung 10°). 36Cl surface-exposure dating of boulders of the avalanche mass indicates an event age of 8.6 ± 0.6 ka. A 14C age of 7785 ± 190 cal yr BP of a palaeosoil within an alluvial fan downlapping the rock avalanche is consistent with the event age. The distal 2 km of the rock-avalanche deposit is characterized by a highly regular array of transverse ridges that were previously interpreted as terminal moraines of Late-Glacial. ‘Jigsaw-puzzle structure’ of gravel to boulder-size clasts in the ridges and a matrix of cataclastic gouge indicate a rock avalanche origin. For a wide altitude range the avalanche deposit is preserved, and the event age of mass-wasting precludes both runout over glacial ice and subsequent glacial overprint. The regularly arrayed transverse ridges thus were formed during freezing of the rock avalanche deposits. PMID:24966447

  10. Early Holocene (8.6 ka) rock avalanche deposits, Obernberg valley (Eastern Alps): Landform interpretation and kinematics of rapid mass movement.

    PubMed

    Ostermann, Marc; Sanders, Diethard; Ivy-Ochs, Susan; Alfimov, Vasily; Rockenschaub, Manfred; Römer, Alexander

    2012-10-15

    In the Obernberg valley, the Eastern Alps, landforms recently interpreted as moraines are re-interpreted as rock avalanche deposits. The catastrophic slope failure involved an initial rock volume of about 45 million m³, with a runout of 7.2 km over a total vertical distance of 1330 m (fahrböschung 10°). (36)Cl surface-exposure dating of boulders of the avalanche mass indicates an event age of 8.6 ± 0.6 ka. A (14)C age of 7785 ± 190 cal yr BP of a palaeosoil within an alluvial fan downlapping the rock avalanche is consistent with the event age. The distal 2 km of the rock-avalanche deposit is characterized by a highly regular array of transverse ridges that were previously interpreted as terminal moraines of Late-Glacial. 'Jigsaw-puzzle structure' of gravel to boulder-size clasts in the ridges and a matrix of cataclastic gouge indicate a rock avalanche origin. For a wide altitude range the avalanche deposit is preserved, and the event age of mass-wasting precludes both runout over glacial ice and subsequent glacial overprint. The regularly arrayed transverse ridges thus were formed during freezing of the rock avalanche deposits. PMID:24966447

  11. Blood pressure (BP) assessment-from BP level to BP variability.

    PubMed

    Feber, Janusz; Litwin, Mieczyslaw

    2016-07-01

    The assessment of blood pressure (BP) can be challenging in children, especially in very young individuals, due to their variable body size and lack of cooperation. In the absence of data relating BP with cardiovascular outcomes in children, there is a need to convert absolute BP values (in mmHg) into age-, gender- and height appropriate BP percentiles or Z-scores in order to compare a patient's BP with the BP of healthy children of the same age, but also of children of different ages. Traditionally, the interpretation of BP has been based mainly on the assessment of the BP level obtained by office, home or 24-h BP monitoring. Recent studies suggest that it is not only BP level (i.e. average BP) but also BP variability that is clinically important for the development of target organ damage, including the progression of chronic kidney disease. In this review we describe current methods to evaluate of BP level, outline available methods for BP variability assessment and discuss the clinical consequences of BP variability, including its potential role in the management of hypertension. PMID:26201477

  12. 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.

  13. A ˜25 ka Indian Ocean monsoon variability record from the Andaman Sea

    NASA Astrophysics Data System (ADS)

    Rashid, H.; Flower, B. P.; Poore, R. Z.; Quinn, T. M.

    2007-10-01

    Recent paleoclimatic work on terrestrial and marine deposits from Asia and the Indian Ocean has indicated abrupt changes in the strength of the Asian monsoon during the last deglaciation. Comparison of marine paleoclimate records that track salinity changes from Asian rivers can help evaluate the coherence of the Indian Ocean monsoon (IOM) with the larger Asian monsoon. Here we present paired Mg/Ca and δ 18O data on the planktic foraminifer Globigerinoides ruber (white) from Andaman Sea core RC12-344 that provide records of sea-surface temperature (SST) and δ 18O of seawater (δ 18O sw) over the past 25,000 years (ka) before present (BP). Age control is based on nine accelerator mass spectrometry (AMS) dates on mixed planktic foraminifera. Mg/Ca-SST data indicate that SST was ˜3 °C cooler during the last glacial maximum (LGM) than the late Holocene. Andaman Sea δ 18O sw exhibited higher than present values during the Lateglacial interval ca 19-15 ka BP and briefly during the Younger Dryas ca 12 ka BP. Lower than present δ 18O sw values during the BØlling/AllerØd ca 14.5-12.6 ka BP and during the early Holocene ca 10.8-5.5 ka BP are interpreted to indicate lower salinity, reflect some combination of decreased evaporation-precipitation (E-P) over the Andaman Sea and increased Irrawaddy River outflow. Our results are consistent with the suggestion that IOM intensity was stronger than present during the BØlling/AllerØd and early Holocene, and weaker during the late glaciation, Younger Dryas, and the late Holocene. These findings support the hypothesis that rapid climate change during the last deglaciation and Holocene included substantial hydrologic changes in the IOM system that were coherent with the larger Asian monsoon.

  14. Fate of ( sup 14 C)monolinuron in potatoes and soil under outdoor conditions

    SciTech Connect

    Freitag, D.; Scheunert, I. )

    1990-12-01

    (phenyl-{sup 14}C)Monolinuron was applied (2.5 and 1.9 kg/ha) to the soil surface of an outdoor lysimeter in two successive years: then, potatoes were grown. Total recovery of {sup 14}C in soil, plants, and leached water was about 55% (of {sup 14}C applied) after the first growing period and about 43% after the second growing period. Radioactivity in soil contained 77.1% (based on total {sup 14}C recovered in soil) bound residues, 15% monolinuron, and the following conversion products: N-(4-hydroxyphenyl)-N'-methoxy-N'-methylurea, N-(4-chlorophenyl)-N'-methylurea. N-(4-chlorophenyl)methylcarbamate, N-(4-chlorophenyl)-N-methyl-methylcarbamate, and 4-chloroformanilide. The leachate contained 0.8% (based on total {sup 14}C recovered in leachate) N-(4-hydroxyphenyl)-N'-methoxy-N'-methylurea. Potato plants contained 0.106 mg/kg radioactive residues in peeled tubers after one growing period and 15.94 mg/kg in the tops; after two growing periods, peeled tubers contained 0.091 mg/kg and tops contained 18.87 mg/kg radioactive residues. These residues consisted of bound {sup 14}C (57.9% of total {sup 14}C recovered in plants), N-(4-hydroxyphenyl)-N'-methoxy-N'-methylurea, N-(4-chlorophenyl)-N'-methylurea, N-(4-chlorophenyl)methylcarbamate, N-(4-chlorophenyl)-N-methyl-methylcarbamate, and 4,4'-dichlorozobenzene.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. Respiration of [14C]alanine by the ectomycorrhizal fungus Paxillus involutus.

    PubMed

    Chalot, M; Brun, A; Finlay, R D; Söderström, B

    1994-08-01

    The ectomycorrhizal fungus Paxillus involutus efficiently took up exogenously supplied [14C]alanine and rapidly converted it to pyruvate, citrate, succinate, fumarate and to CO2, thus providing direct evidence for the utilisation of alanine as a respiratory substrate. [14C]alanine was further actively metabolised to glutamate, glutamine and aspartate. Exposure to aminooxyacetate completely suppressed 14CO2 evolution and greatly reduced the flow of carbon from [14C]alanine to tricarboxylic acid cycle intermediates and amino acids, suggesting that alanine aminotransferase plays a pivotal role in alanine metabolism in Paxillus involutus. PMID:8082830

  20. 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.

  1. Comparison of (14)C liquid scintillation counting at NIST and NRC Canada.

    PubMed

    Bergeron, Denis E; Galea, Raphael; Laureano-Pérez, Lizbeth; Zimmerman, Brian E

    2016-03-01

    An informal bilateral comparison of (14)C liquid scintillation (LS) counting at the National Research Council of Canada (NRC) and the National Institute of Standards and Technology (NIST) has been completed. Two solutions, one containing (14)C-labeled sodium benzoate and one containing (14)C-labeled n-hexadecane, were measured at both laboratories. Despite observed LS cocktail instabilities, the two laboratories achieved accord in their standardizations of both solutions. At the conclusion of the comparison, the beta spectrum used for efficiency calculations was identified as inadequate and the data were reanalyzed with different inputs, improving accord. PMID:26585641

  2. 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.

  3. Distribution of /sup 14/C after oral administration of (1-/sup 14/C)linoleic acid in rats fed different levels of essential fatty acids

    SciTech Connect

    Becker, W.

    1984-09-01

    Rats from an inbred Sprague-Dawley strain were fed semisynthetic diets with a low (0.3 energy percent (en %)), normal (3 en %) or high (10 en %) content of essential fatty acids (EFA) for at least three generations. Twenty-nine- to 33-day-old male rats were given a single intragastric dose of (1-14C)linoleic acid in olive oil, and the respiratory CO2, urine and feces were collected for 46 hours (expt 1) or 20 hours (expt 2). The 14C activity in respiratory CO2, feces, urine and the carcass was determined in both experiments. In experiment 2 it was also measured in samples of the brown fat, liver, adrenals, white fat, skeletal muscles and brain. In both experiments the rats fed the low EFA diet retained significantly more 14C activity than the rats fed the normal or high EFA diets. In all groups the concentration of label was highest in the brown fat and the adrenals, but the above differences among the groups with respect to 14C retention were mainly observed in the liver, skeletal muscles and brain.

  4. New insights on water level variability for Lake Turkana for the past 15 ka and at 150 ka from relict beaches

    NASA Astrophysics Data System (ADS)

    Forman, S. L.; Wright, D.

    2015-12-01

    Relict beaches adjacent to Lake Turkana provide a record of water level variability for the Late Quaternary. This study focused on deciphering the geomorphology, sedimentology, stratigraphy and 14C chronology of strand plain sequences in the Kalokol and Lothagam areas. Nine >30 m oscillations in water level were documented between ca. 15 and 4 ka. The earliest oscillation between ca. 14.5 and 13 ka is not well constrained with water level to at least 70 m above the present surface and subsequently fell to at least 50 m. Lake level increased to ~ 90 m between ca. 11.2 and 10.4 ka, post Younger Dryas cooling. Water level fell by >30 m by 10.2 ka, with another potential rise at ca. 8.5 ka to >70 m above current level. Lake level regressed by > 40 m at 8.2 ka coincident with cooling in the equatorial Eastern Atlantic Ocean. Two major >70 m lake level oscillations centered at 6.6 and 5.2 ka may reflect enhanced convection with warmer sea surface temperatures in the Western Indian Ocean. The end of the African Humid Period occurred from ca. 8.0 to 4.5 ka and was characterized by variable lake level (± > 40 m), rather than one monotonic fall in water level. This lake level variability reflects a complex response to variations in the extent and intensity of the East and West African Monsoons near geographic and topographic limits within the catchment of Lake Turkana. Also, for this closed lake basin excess and deficits in water input are amplified with a cascading lake effect in the East Rift Valley and through the Chew Bahir Basin. The final regression from a high stand of > 90 m began at. 5.2 ka and water level was below 20 m by 4.5 ka; and for the remainder of the Holocene. This sustained low stand is associated with weakening of the West African Monsoon, a shift of the mean position of Congo Air Boundary west of the Lake Turkana catchment and with meter-scale variability in lake level linked to Walker circulation across the Indian Ocean. A surprising observation is

  5. 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

  6. Impact of liming and drying municipal sewage sludge on the amount and availability of (14)C-acetyl sulfamethoxazole and (14)C-acetaminophen residues.

    PubMed

    Geng, Chunnu; Bergheaud, Valérie; Garnier, Patricia; Zhu, Yong-Guan; Haudin, Claire-Sophie

    2016-01-01

    Acetyl Sulfamethoxazole (AC-SMX) and acetaminophen (ACM) can be found in municipal sewage sludge, and their content and availability may be influenced by sludge treatments, such as drying and liming. A sludge similarly centrifuged with/without a flocculant was spiked with (14)C-labelled AC-SMX or ACM. Then, it was either limed (20% CaO) or/and dried under different laboratory conditions (1 week at ambient temperature; and 48 h at 40 or 80 °C). The total amount and distribution of the (14)C-compounds among several chemical fractions, based on the sludge floc definition, were assessed at the end of the treatments. All the (14)C-activity brought initially was recovered in the limed and/or dried sludges for AC-SMX but only between 44.4 and 84.9% for ACM, with the highest rate obtained for the limed sludge. Drying at 80 °C or liming increased the percentage of the sludge total organic carbon recovered in the extracts containing soluble extracellular polymeric substances (S-EPS) and the percentage of the total (14)C-activity extracted simultaneously. The non-extractable residues represented only 3.9-11.6% of the total (14)C-activity measured in the treated sludges for AC-SMX and 16.9-21.8% for ACM. The presence of AC-SMX and ACM residues in the treated sludges, after liming and drying under different conditions, was shown using some (14)C-labelled molecules. At this time scale and according to the extraction method selected, most of the (14)C-residues remained soluble and easily extractable for both compounds. This result implies that certain precautions should be taken when storing sludges before being spread on the field. Sludge piles, particularly the limed sludge, should be protected from rain to limit the production of lixiviates, which may contain residues of AC-SMX and ACM. PMID:26492342

  7. The new Section 23 of DO160C/ED14C lightning testing of externally mounted electrical equipment

    NASA Technical Reports Server (NTRS)

    Burrows, B. J. C.

    1991-01-01

    The new Section 23 is introduced which has only very recently been fully approved by the RTCA for incorporation into the first revision of DO160C/ED14C. Full threat lightning direct effects testing of equipment is entirely new to DO160, the only existing lightning testing is transient testing for LRU's (Line Replaceable Units) by pin or cable bundle injection methods, for equipment entirely contained within the airframe and assumed to be unaffected by direct effects. This testing required transients of very low amplitude compared with lightning itself, whereas the tests now to be described involve full threat lightning testing, that is using the previously established severe parameters of lightning appropriate to the Zone, such as 200 kA for Zone 1A as in AC20-136. Direct effects (i.e., damage) testing involves normally the lightning current arc attaching to the object under test (or very near to it) so submitting it to full potential for the electric, mechanical, thermal and shock damage which is caused by high current arcing. Since equipment for any part of the airframe require qualification, tests to demonstrate safety of equipment in fuel vapor regions of the airframe are also included.

  8. The new Section 23 of DO160C/ED14C lightning testing of externally mounted electrical equipment

    NASA Astrophysics Data System (ADS)

    Burrows, B. J. C.

    1991-08-01

    The new Section 23 is introduced which has only very recently been fully approved by the RTCA for incorporation into the first revision of DO160C/ED14C. Full threat lightning direct effects testing of equipment is entirely new to DO160, the only existing lightning testing is transient testing for LRU's (Line Replaceable Units) by pin or cable bundle injection methods, for equipment entirely contained within the airframe and assumed to be unaffected by direct effects. This testing required transients of very low amplitude compared with lightning itself, whereas the tests now to be described involve full threat lightning testing, that is using the previously established severe parameters of lightning appropriate to the Zone, such as 200 kA for Zone 1A as in AC20-136. Direct effects (i.e., damage) testing involves normally the lightning current arc attaching to the object under test (or very near to it) so submitting it to full potential for the electric, mechanical, thermal and shock damage which is caused by high current arcing. Since equipment for any part of the airframe require qualification, tests to demonstrate safety of equipment in fuel vapor regions of the airframe are also included.

  9. 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

  10. 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

  11. 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

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

    PubMed Central

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

    2009-01-01

    We show a new ultra-sensitive laser based analytical technique, intracavity optogalvanic spectroscopy, allowing extremely high sensitivity for detection of 14C labeled carbon dioxide. Capable of replacing large accelerator mass spectrometers, the technique quantifies attomoles of 14C in submicrogram samples. Based on the specificity of narrow laser resonances coupled with the sensitivity provided by standing waves in an optical cavity and detection via impedance variations, limits of detection near 10-15 14C:12C ratios are obtained. Using a 15W 14CO2 laser, a linear calibration with samples from 10-15 to >2 × 10-12 in 14C:12C ratios, as determined by accelerator mass spectrometry, is demonstrated. Possible applications include microdosing studies in drug development, individualized sub-therapeutic tests of drug metabolism, carbon dating and real time monitoring of atmospheric radiocarbon. The method can also be applied to detection of other trace entities. PMID:18533685

  13. Diffusion of /sup 14/C-labeled formocresol and glutaraldehyde in tooth structures

    SciTech Connect

    Wemes, J.C.; Purdell-Lewis, D.; Jongebloed, W.; Vaalburg, W.

    1982-09-01

    /sup 14/C-Formocresol and /sup 14/C-glutaraldehyde were placed in the root canals of freshly extracted human teeth. The outward diffusion of labeled aldehydes was then measured and autoradiograms of cross-sections taken. No diffusion of glutaraldehyde was detectable within 72 hours, whereas there was a rapidly increasing outflow of formocresol during the same period. In a separate group normal root canal treatment was completed until 2 mm. short of the roentgenologic apex with glutaraldehyde as an irrigant. The walls of the root canals of some of the specimens were examined with electron microscopy and the outflow of /sup 14/C-formocresol which was later placed in some specimens was counted. The use of glutaraldehyde as an irrigant resulted in closure of the apical third of the root canal as indicated by the absence of /sup 14/C-formocresol diffusion.

  14. 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.

  15. Metabolism of 14C-urea by T-strain mycoplasma.

    PubMed

    Ford, D K; McCandlish, K L; Gronlund, A F

    1970-05-01

    When (14)C-labeled urea was metabolized by T-strain mycoplasma, 94 to 95% of the radioactivity was recovered as (14)CO(2), and significant radioactivity was not incorporated into cellular material. PMID:5419267

  16. Fate of ( sup 14 C)arsanilic acid in pigs and chickens

    SciTech Connect

    Aschbacher, P.W.; Feil, V.J. )

    1991-01-01

    Arsanilic acid uniformly labeled with {sup 14}C in the benzene ring was used to determine the metabolic fate of oral arsanilic acid in pigs and chickens. Arsanilic acid was well absorbed in both species, and urine was the predominant route of excretion. The bile was a minor (< 5% of the dose) route of excretion in pigs; however, biliary excretion was not measured in roosters. Arsanilic acid, N-acetylarsanilic acid, and (4-acetamidophenyl)dimethylarsine oxide were isolated from pig urine (17-39%, 15-29%, and < 5% of urinary {sup 14}C, respectively). Only 25% of the {sup 14}C in pig feces was extractable, and no metabolites could be isolated. Arsanilic acid was the only radioactive compound isolated from urine of colostomized roosters, and there was no suggestion of other metabolites from the isolation scheme employed. No attempt was made to isolate {sup 14}C compounds in feces from colostomized roosters or in excreta from normal roosters.

  17. Use of [14C]lysine to detect microbial contamination in liquid foods.

    PubMed Central

    Mafart, P; Bourgeois, C; Duteurtre, B; Moll, M

    1978-01-01

    A radiometric method for microbiological control in food industries is suggested. This method, based on the labeling of cells by [14C]lysine, was tested by using nine species of yeast and two species of bacteria. PMID:354531

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

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

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

  19. Metabolism of L-(guanidinooxy-/sup 14/C)canavanine in the rat

    SciTech Connect

    Thomas, D.A.; Rosenthal, G.A.

    1987-12-01

    The metabolism of L-canavanine, a nonprotein amino acid with significant antitumor effects, was investigated. L-Canavanine, provided at 2.0 g/kg, was supplemented with 5 microCi of L-(guanidinooxy-/sup 14/C)canavanine (58 microCi/mumol) and administered iv, sc, or orally to female Sprague-Dawley rats weighing approximately 200 g. /sup 14/C recovery in the urine at 24 hr was 83, 68, or 61%, respectively, of the administered dose. Another 5-8% of the /sup 14/C was expired as /sup 14/CO/sub 2/. The gastrointestinal tract contained 21% of orally administered /sup 14/C. Serum, feces, tissues, and de novo synthesized proteins only accounted for a few percent of the original dose by any administrative route. Analysis of the /sup 14/C-containing urinary metabolites revealed that (/sup 14/C) urea accounted for 88% of the urinary radioactivity for an iv injection, 75% for sc administration, and 50% following an oral dose. By all routes of administration, (/sup 14/C)guanidine represented 5% of the radioactivity in the urine and (/sup 14/C)guanidinoacetic acid accounted for 2%. Serum and urine amino acid analysis showed a markedly elevated ornithine level. Basic amino acids such as histidine, lysine, and arginine were also higher in the urine. Plasma ammonia levels were determined following oral canavanine doses of 1.0, 2.0, and 4.0 g/kg. A rapid but transient elevation in plasma ammonia was observed only at the 4.0 g/kg dose. This indicates that elevated plasma ammonia is not a likely cause of canavanine toxicity at the drug concentrations used in this study.

  20. 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

  1. 17 CFR 240.14c-2 - Distribution of information statement.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... Regulation S-K (17 CFR 229.901(c)) and is registered (or authorized to be registered) on Form S-4 (17 CFR 229.25) or Form F-4 (17 CFR 229.34), the information statement must be distributed to security holders no... statement. 240.14c-2 Section 240.14c-2 Commodity and Securities Exchanges SECURITIES AND EXCHANGE...

  2. ( 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.

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

    SciTech Connect

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

    2008-04-23

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

  4. 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.

  5. 17 CFR 240.14c-2 - Distribution of information statement.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... Regulation S-K (17 CFR 229.901(c)) and is registered (or authorized to be registered) on Form S-4 (17 CFR 229.25) or Form F-4 (17 CFR 229.34), the information statement must be distributed to security holders no... statement. 240.14c-2 Section 240.14c-2 Commodity and Securities Exchanges SECURITIES AND EXCHANGE...

  6. 17 CFR 240.14c-2 - Distribution of information statement.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... Regulation S-K (17 CFR 229.901(c)) and is registered (or authorized to be registered) on Form S-4 (17 CFR 229.25) or Form F-4 (17 CFR 229.34), the information statement must be distributed to security holders no... statement. 240.14c-2 Section 240.14c-2 Commodity and Securities Exchanges SECURITIES AND EXCHANGE...

  7. 17 CFR 240.14c-2 - Distribution of information statement.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... Regulation S-K (17 CFR 229.901(c)) and is registered (or authorized to be registered) on Form S-4 (17 CFR 229.25) or Form F-4 (17 CFR 229.34), the information statement must be distributed to security holders no... statement. 240.14c-2 Section 240.14c-2 Commodity and Securities Exchanges SECURITIES AND EXCHANGE...

  8. Fate of 14C-acrylamide in roasted and ground coffee during storage.

    PubMed

    Baum, Matthias; Böhm, Nadine; Görlitz, Jessica; Lantz, Ingo; Merz, Karl Heinz; Ternité, Rüdiger; Eisenbrand, Gerhard

    2008-05-01

    Acrylamide (AA) is formed during heating of carbohydrate rich foods in the course of the Maillard reaction. AA has been classified as probably carcinogenic to humans. Storage experiments with roasted coffee have shown that AA levels decrease depending on storage time and temperature. In the present study the fate of AA lost during storage of roasted and ground (R&G) coffee was studied, using 14C-labeled AA as radiotracer. Radiolabel was measured in coffee brew, filter residue, and volatiles. In the brew, total (14)C-label decreased during storage of R&G coffee, while activity in the filter residue built up concomitantly. [2,3-14C]-AA (14C-AA) was the only 14C-related water extractable low molecular compound in the brew detected by radio-HPLC. No formation of volatile 14C-AA-related compounds was detected during storage and coffee brewing. Close to 90% of the radiolabel in the filter residue (spent R&G coffee, spent grounds) remained firmly bound to the matrix, largely resisting extraction by aqueous ammonia, ethyl acetate, chloroform, hexane, and sequential polyenzymatic digest. Furanthiols, which are abundant as aroma components in roasted coffee, have not been found to be involved in the formation of covalent AA adducts and thus do not contribute substantially to the decrease of AA during storage. PMID:18435440

  9. 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.

  10. 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. PMID:23401563

  11. 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.

  12. Disposition of 14C-alpha-cyclodextrin in germ-free and conventional rats.

    PubMed

    Van Ommen, B; De Bie, A T H J; Bär, A

    2004-06-01

    The absorption, disposition, metabolism, and excretion of uniformly (14)C-labeled alpha-cyclodextrin ((14)C-alpha-CD) was examined in four separate experiments with Wistar rats. In Experiment 1, (14)C-alpha-CD (25 microCi, 50 mg/kg bw) was administered intravenously to four male and four female conventional rats. In Experiment 2, (14)C-alpha-CD (25 microCi, 200 mg/kg bw) was given by gavage to four male and four female germ-free rats. In Experiments 3 and 4, (14)C-alpha-CD was given to groups of four male and four female conventional rats by gavage at different dose levels (100 microCi, 200 mg/kg bw; 25 microCi, 200 and 100 mg/kg bw). In all experiments, (14)C was measured in respiratory CO(2), urine, and feces over periods of 24-48 h, and in the contents of the gastrointestinal tract, blood, main organs, and residual carcass at termination of the experiments. The chemical identity of the (14)C-labeled compounds was examined by HPLC in blood (Experiment 1), urine (Experiments 1-4), feces (Experiments 2-4), and samples of intestinal contents (Experiments 2 and 4). Recovered (14)C was expressed as percentage of the administered dose. Experiment 1 showed that intravenously administered alpha-CD is excreted rapidly with urine. During the first 2h after dosing, plasma (14)C levels decreased rapidly (t(1/2), 26 and 21 min in male and female rats, respectively). About 13% of the administered (14)C dose (range 4.6-30.6) was detected in the feces, respiratory CO(2), organs, and carcass at the end of the experiment, i.e., 24 h after dosing. The presence of about 1.9% in the intestinal contents and feces suggests that a certain fraction of systemic alpha-CD is eliminated with the bile or saliva. Conclusive evidence, either positive or negative, for a hydrolysis and further metabolism of a small fraction of the administered alpha-CD by the enzymes of the mammalian body could not be gained from this experiment. Upon oral administration of (14)C-alpha-CD to germ-free rats

  13. 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

  14. 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.

  15. 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).

  16. 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.

  17. Progress in automated extraction and purification of in situ 14C from quartz: Results from the Purdue in situ 14C laboratory

    NASA Astrophysics Data System (ADS)

    Lifton, Nathaniel; Goehring, Brent; Wilson, Jim; Kubley, Thomas; Caffee, Marc

    2015-10-01

    Current extraction methods for in situ 14C from quartz [e.g., Lifton et al., (2001), Pigati et al., (2010), Hippe et al., (2013)] are time-consuming and repetitive, making them an attractive target for automation. We report on the status of in situ 14C extraction and purification systems originally automated at the University of Arizona that have now been reconstructed and upgraded at the Purdue Rare Isotope Measurement Laboratory (PRIME Lab). The Purdue in situ 14C laboratory builds on the flow-through extraction system design of Pigati et al. (2010), automating most of the procedure by retrofitting existing valves with external servo-controlled actuators, regulating the pressure of research purity O2 inside the furnace tube via a PID-based pressure controller in concert with an inlet mass flow controller, and installing an automated liquid N2 distribution system, all driven by LabView® software. A separate system for cryogenic CO2 purification, dilution, and splitting is also fully automated, ensuring a highly repeatable process regardless of the operator. We present results from procedural blanks and an intercomparison material (CRONUS-A), as well as results of experiments to increase the amount of material used in extraction, from the standard 5 g to 10 g or above. Results thus far are quite promising with procedural blanks comparable to previous work and significant improvements in reproducibility for CRONUS-A measurements. The latter analyses also demonstrate the feasibility of quantitative extraction of in situ 14C from sample masses up to 10 g. Our lab is now analyzing unknowns routinely, but lowering overall blank levels is the focus of ongoing research.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  19. 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.

  20. A Minute Dose of 14C-b-Carotene is Absorbed and Converted to Retinoids in Humans

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We dosed 8 adults with 14C-all-trans [10,10',11,11'-14C]-B-carotene (1.01 nmol) to quantify its absorption and metabolism. We used accelerator mass spectrometry (AMS) to measure 14C eliminated in feces over 14 days, in urine over 30 days, and that was retained in plasma over 166 days since dose. We...

  1. 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

  2. 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

  3. 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

  4. 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.

  5. 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

  6. 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.

  7. 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

  8. 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

  9. 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. PMID:26369226

  10. 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.

  11. 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.

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

    SciTech Connect

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

    1991-05-01

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

  13. Special Analysis: Revised 14C Disposal Limits for the Saltstone Disposal Facility

    SciTech Connect

    Kaplan, D.I.

    2004-03-19

    The Saltstone Special Analysis calculated a limit for 14C based on the atmospheric pathway of 52 pCi/mL using some very conservative assumptions. This was compared to the estimated Low Curie Salt concentration of 0.45 pCi/mL and since the limit was two orders of magnitude greater than the estimated concentration, the decision was made that no further analysis was needed. The 14C concentration in Tank 41 has been found to be much greater than the estimated concentration and to exceed the limit derived in the Special Analysis. A rigorous analysis of the release of 14C via the air pathway that considers the chemical effects of the Saltstone system has shown that the flux of 14C is significantly less than that assumed in the Special Analysis. The net result is an inventory limit for 14C that is significantly higher than that derived in the Special Analysis that will also meet the performance objectives of DOE Order 435.1.

  14. 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.

  15. 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.

  16. 14C Activity and Global Carbon Cycle Changes over the Past 50,000 Years

    NASA Astrophysics Data System (ADS)

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

    2004-01-01

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

  17. 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.

  18. 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.

  19. 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

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

    PubMed

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

    1998-01-01

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

  1. Systemic exposure to parabens: pharmacokinetics, tissue distribution, excretion balance and plasma metabolites of [14C]-methyl-, propyl- and butylparaben in rats after oral, topical or subcutaneous administration.

    PubMed

    Aubert, Nicolas; Ameller, Thibault; Legrand, Jean-Jacques

    2012-03-01

    Parabens (PB) are preservatives used in food, drugs and personal care products preventing microbial and fungal contamination. We investigated ADME profiles of [14C]-methyl-, propyl- or butylparaben (MP, PP, BP) following single oral, dermal or subcutaneous (BP) doses at 100 mg/kg to Sprague-Dawley rats. Plasma Cmax and AUC values after oral or subcutaneous doses were 4- to 10-fold higher relative to respective values after dermal administration. tmax ranged from 0.5, 2 or 8 h after oral, subcutaneous or dermal administration, respectively. MP produced higher blood Cmax and AUC levels relative to those after PP or BP. Following oral or subcutaneous administration, urinary excretion was predominant (>70%, mainly during the first 24 h), less than 4% were eliminated in the feces, 2% were retained in the tissues and carcasses. Following dermal application, >50% of the dose was unabsorbed, 14-27% or <2% were respectively excreted in the urine or feces, respectively. Overall, parabens were well absorbed after oral and subcutaneous, and partially absorbed after dermal administration. All administration routes produced a single peak in the plasma, corresponding to that of para-hydroxybenzoic acid (PHBA) suggesting that PB produce no significant systemic exposure of mammalian organisms after oral, topical or subcutaneous administration. PMID:22265941

  2. sup 14 C ages of hydrothermal petroleum and carbonate in Guaymas Basin, Gulf of California: implications for oil generation, expulsion, and migration

    SciTech Connect

    Peter, J.M.; Peltonen, P.; Scott, S.D. ); Simoneit, B.R.T.; Kawka, O.E. )

    1991-03-01

    {sup 14}C dates have been obtained by accelerator mass spectrometry and by conventional techniques from hydrothermally derived petroleum, calcite, and vent water from the southern trough of Guaymas Basin, Gulf of California. The ages for petroleum range from 4240 to 5705 B.P., whereas those for calcite range from 7340 to 33,168 B.P. The CO{sub 2} in a sample of hydrothermal vent fluid (24% end member) yielded an apparent age of 14,820 B.P., which is within the calcite age range. These are not true ages, but rather they reflect the age of carbon within these materials. The data indicate that the conversion of sedimentary organic matter to petroleum occurs very rapidly and that the petroleum is mobilized from sedimentary organic matter in the upper 30 m of the sediment column ({le}500 m thick) underlying the sea-floor deposits. The large difference in ages between the petroleum and most of the calcites indicates that the carbon source in the calcites is more complex. The inorganic carbon pool probably originates from the dissolution of older detrital carbonates and autochthonous biogenic carbonates in the shallow sediments, and/or the decarboxylation of organic matter at greater depth, with a magmatic component of dead carbon.

  3. {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.

  4. 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

  5. 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.

  6. 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).

  7. Distributions and Transformations of Natural Abundance 14C and 13C in Dissolved and Particulate Lipids in a Major Temperate Estuary

    NASA Astrophysics Data System (ADS)

    Bauer, J. E.; Canuel, E. A.; McIntosh, H.; Barrett, A.; Ferer, E.; Hossler, K.

    2013-12-01

    Limited previous studies have shown major differences in the natural 14C and 13C isotopic signatures and radiocarbon ages of different biochemical classes (e.g., proteins, carbohydrates, lipid, etc.) in river, estuarine and marine dissolved and particulate organic matter (DOM and POM, respectively). Of particular note are the much greater radiocarbon ages of lipophilic materials than other compound classes. Possible explanations for these findings include greater-than-expected inputs of fossil and highly aged lipid-containing organic matter to rivers and estuaries, extended sorptive-protection of lipophilic materials from degradation and/or lower overall reactivities of lipids vs. other major biochemical classes. We measured the Delta 14C and del 13C signatures and 14C ages of lipid classes in DOM and POM in a major temperate estuary, Delaware Bay (USA) over two years. Changes in DOM were also followed during large volume dark and light incubations to assess the microbial and photochemical reactivity and processing of DOM and lipids. Neutral lipids in DOM were among the most highly aged (> 30,000 yrs BP) of any materials measured in natural waters to date, and were significantly older than co-occurring polar lipids (~4,000-5,000 yrs BP). In general, DOM lipid ages were significantly greater than POM lipid ages across the river-estuary transect, arguing against sorptive protection as the major factor explaining greater ages of lipid than those of other compound classes. Both dark and light incubations of DOM resulted in losses of very highly aged material (30-50,000 y BP), with the remnant exported lipids being correspondingly younger. The microbial and photochemical alterations were most pronounced for lipids from freshwater reaches of the system (i.e., the Delaware River). These findings suggest that a) dissolved vs. particulate lipids have fundamentally different sources and/or physico-chemical partitioning, b) different lipid classes (e.g., neutral vs. polar

  8. 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.

  9. 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

  10. In situ 14C depth profile of subsurface vein quartz samples from Macraes Flat New Zealand

    NASA Astrophysics Data System (ADS)

    Kim, K. J.; Lal, D.; Englert, P. A. J.; Southon, J.

    2007-06-01

    We present results of measurements of cosmogenic in situ 14C produced in a quartz vein from Macraes Flat, East Otago, New Zealand, where concentrations of in situ produced 10Be and 26Al were previously studied by Kim and Englert [Earth Planet. Sci. Lett. 223 (2004) 113]. 14C was extracted from the quartz samples up to depths of 400 g cm-2 using a low temperature wet extraction method [D. Lal, A.J.T. Jull, Nucl. Instr. and Meth. B 92 (1994) 291]. Based on the results for 10Be and 26Al, we expected that the 14C activity in the samples would be at saturation levels, in equilibrium with erosion. The surface exposure age of this site was found to be about 25 000 years using 10Be and 26Al at the surface, with a surface erosion rate of at least 10-3 cm/y [K.J. Kim, P.A.J. Englert, Earth Planet. Sci. Lett. 223 (2004) 113]. The measured 14C activities were compared with those expected from spallation of Si and O in quartz by energetic neutrons and fast muons, and from capture of negative muons in O in quartz [B. Heisinger, A.J.T. Jull, D. Lal, P. Kubik, S. Ivy-Ochs, K. Knie, E. Nolte, Earth Planet. Sci. Lett. 200 (2002) 357; B. Heisinger, D. Lal, A.J.T. Jull, P. Kubik, S. Ivy-Ochs, S. Neumaier, K. Knie, V. Lazarev, E. Nolte, Earth Planet. Sci. Lett. 200 (2002) 345]. Surprisingly, we found that the 14C activities were significantly greater than those expected, by factors of 2 3, especially in samples of depths <200 g cm-2. We suspect that the excess 14C probably resulted from capture of thermal neutrons in nitrogen present in the fluid inclusions in quartz. This study shows that great care has to be taken in measurements of in situ 14C in quartz, especially in samples exposed near sea level and greater depths, where rates of spallation produced 14C are low.

  11. 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.

  12. 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.

  13. 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

  14. Synthesis of 14C-labeled perfluorooctanoic and perfluorodecanoic acids; Purification of perfluorodecanoic acid

    SciTech Connect

    Reich, I.L.; Reich, H.J.; Menahan, L.A.; Peterson, R.E.

    1987-01-01

    Perfluorooctanoic and -decanoic acids are representative of a series of perfluorinated acids that have been used for a variety of industrial purposes primarily due to their surfactant properties. The toxicity of these compounds is being investigated in a number of laboratories. 14C-labeled materials would be useful in these studies but are not commercially available. Johncock prepared unlabeled PFOA in low yield by carbonation of the unstable perfluoroheptyllithium at -90 degrees Centigrade. We anticipated several problems in applying this procedure to the synthesis of the 14C-labeled material. Johncock's procedure was run on a fairly large scale (10 mmol) with excess CO2.

  15. Thermoluminescence and new 14C age estimates for late quaternary loesses in southwestern Nebraska

    USGS Publications Warehouse

    Maat, P.B.; Johnson, W.C.

    1996-01-01

    Loess of late Quaternary age mantles most of Nebraska south of the Platte River Valley. At least five late Quaternary loesses are recognized: from oldest to youngest, one or more undifferentiated pre-lllinoian loesses, the Loveland Loess, the Gilman Canyon Loess, which exhibits a well developed soil and rests unconformably on the Sangamon soil, the Peoria Loess capped by the Brady soil, and the Bignell Loess, which is distributed discontinuously. Previous research shows that the Loveland Loess is Illinoian. the Gilman Canyon Loess and Peoria Loess are Wisconsin, and the Bignell Loess is Holocene. We present here the first thermoluminescence (TL) age estimates and new C ages for these late Quaternary loesses at two key sections in southwestern Nebraska, the Eustis ash pit and the Bignell Hill road cut. TL age estimates from all samples collected from Eustis ash pit and Bignell Hill were internally consistent. TL and C age estimates from these two sections generally agree and support previous age determinations. The TL age estimate on Loveland Loess indicates deposition at 163 ka. TL and radiocarbon age estimates indicate that Oilman Canyon Loess, believed to be deposited during the Farmdale interstade, first began to accumulate at about 40 ka: the lower part of the Gilman Canyon Loess is 36 ka at Eustis and the middle of the unit is 30 ka at Bignell Hill. The lower and upper parts of the Peoria Loess give age estimates of 24 ka and 17 ka, respectively. TL age estimates for deposition of the Bignell Loess are 9 ka near the base, in agreement with radiocarbon age estimates, and 6 ka immediately below the modern soil, substantiating its Holocene age. Comparisons of TL age estimates with ??18O and insolation curves which show loess deposition during interglacial and interstadial as well as glacial periods, indicate that loess deposition on the Great Plains can occur under a variety of climatic conditions.

  16. Carbon-14 ages of the past 20 ka of eruptive activity of Teide volcano, Canary Islands

    NASA Astrophysics Data System (ADS)

    Carracedo, J. C.; Guillou, H.; Paterne, M.; Pérez Torrado, F. J.; Paris, R.; Badiola, E. R.

    2003-04-01

    Teide volcano, the highest volcano on earth (3718 m a.s.l., >7 Km high) after Mauna Loa and Mauna Kea in the Hawaiian Islands, forms a volcanic complex in the centre of the Island of Tenerife. Its most recent eruptive activity (last 20 Ka) is associated with the very active NW branch of the 120º triple rift system of the island. Most of the eruptions of Tenerife during the past 20 ka have occurred along this volcanic feature, frequently in the production of extensive mafic and felsic lava flows, many of which reached the coast, crossing what is now one of the most densely populated areas of Tenerife and of any oceanic island in the world. However, despite numerous previous studies, very important basic geological information is still lacking, in particular dating of these flows to construct a geochronological framework for the evolution of the Teide-NW rift system, and a scientifically based, much needed volcanic hazard assessment. New carbon-14 ages, obtained via coupled mass spectrometer, and others in process, provide important time constraints on the evolution of Teide's volcanic system, the frequency and distribution of its eruptions, and the associated volcanic hazards. Most of the eruptions are not related to the Teide stratovolcano, which apparently had only one eruption in the last 20 Ka about 1240 ± 60 years BP, but to the Pico Viejo volcano (17570 ± 150 years BP), flank parasitic vents (Mña. Abejera upper vent, 5170 ± 110 years BP; Mña. Abejera lower vent, 4790 ± 70 years BP; Mancha Ruana, 2420 ± 70 years BP; Mña. La Angostura, 2010 ± 60 years BP and Roques Blancos, 1790 ± 60 years BP) and the NW rift (Mña. Chío, 3620 ± 70 years BP). Although the volcanic activity during the past 20 ka included the involvement of at least 7 voluminous phonolitic flank vents in the northern, more unstable slopes of the Teide, it took place without any apparent response of the volcano; on the contrary, these eruptions seemed to progressively buttress and

  17. 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.

  18. 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

  19. Ka-band MMIC subarray technology program (Ka-Mist)

    NASA Technical Reports Server (NTRS)

    Pottenger, Warren

    1995-01-01

    The broad objective of this program was to demonstrate a proof of concept insertion of Monolithic Microwave Integrated Circuit (MMIC) device technology into an innovative (tile architecture) active phased array antenna application supporting advanced EHF communication systems. Ka-band MMIC arrays have long been considered as having high potential for increasing the capability of space, aircraft, and land mobile communication systems in terms of scan performance, data rate, link margin, and flexibility while offering a significant reduction in size, weight, and power consumption. Insertion of MMIC technology into antenna systems, particularly at millimeter wave frequencies using low power and low noise amplifiers in close proximity to the radiating elements, offers a significant improvement in the array transmit efficiency, receive system noise figure, and overall array reliability. Application of active array technology also leads to the use of advanced beamforming techniques that can improve beam agility, diversity, and adaptivity to complex signal environments.

  20. Evaluation of Calendar Values of the Climatostratigraphic Borders on the Base of Large Sets of 14C Dates

    NASA Astrophysics Data System (ADS)

    Michczynska, D. J.; Michczynski, A.; Pazdur, A.; Starkel, L.

    2009-04-01

    Two large sets of radiocarbon dates (785 dates for peat samples and 331 dates for fluvial sediments) were used to establish calendar values of the climatostratigraphic borders for the last 16 ka. All samples were collected from the territory of Poland and dated in Gliwice Radiocarbon Laboratory. For both sets Probability Density Functions (PDFs) were constructed by summing the probability distributions of individual 14C dates after the calibration. In the previous analysis (Michczynska and Pazdur, 2004; Michczynski and Michczynska, 2006) authors noticed and discussed the presence of high narrow peaks of the PDFs. Their appearance is caused by two facts: 1. Calibration curve is a record of the environmental changes in the past. The steep slope sections of the calibration curve work as an amplifier and increase the height of the PDF. 2. Environmental changes are indirectly recorded in the frequency of radiocarbon dates because of preferential sampling - the general rule of taking samples from places of visible sedimentation changes (e.g. from the top and bottom of the peat layer) may be the reason that samples from the border of the Late Quaternary climatostratigraphic subdivisions are collected essentially frequently. The high, narrow peaks of the PDFs are produced both by preferential sampling and through the influence of the calibration curve shape. This fact may be useful to establish the border of the Late Quaternary subdivision on the calendar scale for the analyzed geographical area. References: Michczyński A., Michczyńska D.J., 2006. The efect of pdf peaks' height increase during calibration of radiocarbon date sets. Geochronometria, 25: 1-4. Michczyńska D.J., Pazdur A., 2004. A shape analysis of cumulative probability density function of radiocarbon dates set in the study of climate change in Late Glacial and Holocene. Radiocarbon, 46(2): 733-744.

  1. The 100-133 ka record of Italian explosive volcanism and revised tephrochronology of Lago Grande di Monticchio

    NASA Astrophysics Data System (ADS)

    Wulf, Sabine; Keller, Jörg; Paterne, Martine; Mingram, Jens; Lauterbach, Stefan; Opitz, Stephan; Sottili, Gianluca; Giaccio, Biagio; Albert, Paul G.; Satow, Chris; Tomlinson, Emma L.; Viccaro, Marco; Brauer, Achim

    2012-12-01

    Laminated sediments of the maar lake Lago Grande di Monticchio in southern Italy exhibit a unique sequence of numerous primary tephra events that provide both insights into the Late Quaternary eruptive history of Italian volcanoes and an archive of essential marker horizons for dating and linking palaeoclimate records throughout the Central and Eastern Mediterranean. The acquisition of new sediment cores from this lake now extends the existing 100 ka-tephra record back to 133 ka BP, the end of the penultimate Glacial. The additional ca 30 m of sediments host a total number of 52 single tephra layers forming 21 tephra clusters that have been characterised on the basis of detailed geochemical and petrographical examinations. Tephras can be assigned to hitherto poorly known Plinian to sub-Plinian eruptive events of the nearby Campanian (Ischia Island, Phlegrean Fields), Roman (Sabatini volcanic district) and Aeolian-Sicilian volcanoes (Etna, Stromboli, Salina) and are dated according to the varve and sedimentation rate chronology of Monticchio sediments. The most prominent tephra layers within the interval of investigation - TM-25 and TM-27 - can be firmly correlated with Ionian Sea tephras X-5 (ca 105 ka BP) and X-6 (ca 108-110 ka BP). In addition, a further 26 tephra layers are correlated with radiometrically and radioisotopically dated volcanic events providing the basis for a robust revised tephrochronology of the entire Monticchio sediment sequence for the last 133 ka.

  2. Kinetic study of benzyl [1-14C]acetate as a potential probe for astrocytic energy metabolism in the rat brain: Comparison with benzyl [2-14C]acetate.

    PubMed

    Okada, Maki; Yanamoto, Kazuhiko; Kagawa, Tomohiko; Yoshino, Keiko; Hosoi, Rie; Abe, Kohji; Zhang, Ming-Rong; Inoue, Osamu

    2016-02-01

    Brain uptake of [(14)C]acetate has been reported to be a useful marker of astrocytic energy metabolism. In addition to uptake values, the rate of radiolabeled acetate washout from the brain appears to reflect CO2 exhaustion and oxygen consumption in astrocytes. We measured the time-radioactivity curves of benzyl [1-(14)C]acetate ([1-(14)C]BA), a lipophilic probe of [1-(14)C]acetate, and compared it with that of benzyl [2-(14)C]acetate ([2-(14)C]BA) in rat brains. The highest brain uptake was observed immediately after injecting either [1-(14)C]BA or [2-(14)C]BA, and both subsequently disappeared from the brain in a single-exponential manner. Estimated [1-(14)C]BA washout rates in the cerebral cortex and cerebellum were higher than those of [2-(14)C]BA. These results suggested that [1-(14)C]BA could be a useful probe for estimating the astrocytic oxidative metabolism. The [1-(14)C]BA washout rate in the cerebral cortex of immature rats was lower than that of mature rats. An autoradiographic study showed that the washout rates of [1-(14)C]BA from the rat brains of a lithium-pilocarpine-induced status epilepticus model were not significantly different from the values in control rat brains except for the medial septal nucleus. These results implied that the enhancement of amino acid turnover rate rather than astrocytic oxidative metabolism was increased in status epilepticus. PMID:26661153

  3. Keratoacanthoma (KA): An update and review.

    PubMed

    Kwiek, Bartlomiej; Schwartz, Robert A

    2016-06-01

    Keratoacanthoma (KA) is a common but underreported tumor of the skin. Two striking features of KA are its clinical behavior with spontaneous regression after rapid growth and its nosological position on the border between benignity and malignancy. We review current knowledge on the clinical, histopathological, and dermoscopic features of KA to ensure a proper diagnosis and describe its variants, including different types of multiple KAs. We highlight current concepts of KA ethiopathogenesis with special emphasis on the genetic background of multiple familial KA, the role of Wnt signaling pathway, and induction of KA by BRAF inhibitors and procedures of esthetic dermatology. Finally, treatment strategies are presented with surgical excision as a first option, followed by other modalities, including intralesional chemotherapy, topical and systemic agents, lasers, cryotherapy, and photodynamic therapy. PMID:26853179

  4. Tephra record from the Sea of Marmara for the last 70 ka and its paleoceanographic implications

    NASA Astrophysics Data System (ADS)

    Cagatay, M.; Wulf, S.; Guichard, F.; Ozmaral, A.; Sancar; Akçer-Ön, S.; Henry, P.; Gasperini, L.

    2013-12-01

    Sea of Marmara (SoM) is a gateway between the Mediterraean and Black seas, and a tectonically active basin located on a transform plate boundary. Tephra record in the SoM is therefore very important for dating palaeoceanographic, paleoclimatic and tectonic events. We report three tephra units in cores from the SoM extending back to ca 70 ka BP and including an upper marine and a lower lacustrine units separated by a 12 ka (uncalib.) boundary. The uppermost tephra unit is up to 8 mm thick layer in the marine unit. It is heterogenous phonolitic with high total alkali content of 12.4-15.7 wt % and K2O/Na2O of 0.9 to 1.2. The middle and lower tephra layers occur in the lacustrine unit in ca 29 m-long Core MD-01-2430. The middle tephra (MT-1) is a 70 mm-thick homogeneously rhyolitic layer. The lower tephra (MT-2) is 140 mm thick and has a phonolitic-trachytic composition with CaO content of 1.7-1.9 wt % and bimodal K2O/Na2O of 1.0-1.4. Using their geochemical composition and stratigraphic analysis, we assign the tephra units, from top to bottom, to Vesuvius AP2 Pumice, Santorini Cape Riva and Campanian Ignimbrite, which have been previously dated at 3.5 ka BP, 21.95 ka BP, and 39.3 ka BP (all calender ka). The continuous sedimentary record in the Core MD-01-2430 covering the last ca 70 ka indicates that the SoM was lacustrine, disconnected from the Mediterraean Sea during MIS4, MIS3 and most of MIS2. This implies that the sill depth of the Çanakkale Strait (Dardanelles) was shallower than the present-day -65 m sill depth during MIS3 and MIS4. Figure 1: Morphotectonic map of the Sea of Marmara showing location of the studied cores (red stars). Figure 2: Geochemical biplots of tephra glass composition. a) Total alkali silica diagram b) FeO versus total alkalies for allocating cryptotephras from core MNTKS34 and ML01 to the AP2 tephra from Vesuvius. c) FeO versus CaO for correlating tephra MT1 with the Y-2 tephra from Santorini. d) SiO2 versus CaO for discriminating the

  5. Fade Mitigation Techniques at Ka-Band

    NASA Technical Reports Server (NTRS)

    Dissanayake, Asoka (Editor)

    1996-01-01

    Rain fading is the dominant propagation impairment affecting Ka-band satellite links and rain fade mitigation is a key element in the design of Ka-band satellite networks. Some of the common fade mitigation techniques include: power control, diversity, adaptive coding, and resource sharing. The Advanced Communications Technology Satellite (ACTS) provides an excellent opportunity to develop and test Ka-band rain impairment amelioration techniques. Up-link power control and diversity are discussed in this paper.

  6. 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.

  7. Kinetic Distribution of 14C-Metsulfuron-methyl Residues in Paddy Soils under Different Moisture Conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rice paddy soils undergo several cycles of drying and wetting during a growing season. A laboratory study was conducted to determine the effect of soil moisture conditions on the distribution and kinetics of extractable and bound residues of 14C-metsulfuron-methyl in six Chinese paddy soils during 8...

  8. Anaerobic oxidation of [1,2-14C]dichloroethene under Mn(IV)-reducing conditions

    USGS Publications Warehouse

    Bradley, P.M.; Landmeyer, J.E.; Dinicola, R.S.

    1998-01-01

    Anaerobic oxidation of [1,2-14C]dichloroethene to14CO2 under Mn(IV)-reducing conditions was demonstrated. The results indicate that oxidative degradation of partially chlorinated solvents like dichloroethene can be significant even under anoxic conditions and demonstrate the potential importance of Mn(IV) reduction for remediation of chlorinated groundwater contaminants.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  10. 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.

  11. 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

  12. Astrophysical S-Factor of Radiative T 14C Capture at Low Energies

    NASA Astrophysics Data System (ADS)

    Dubovichenko, S. B.; Burtebaev, N.; Dzhazairov-Kakhramanov, A. V.; Alimov, D. K.

    2016-04-01

    The possibility of describing the available experimental data on the astrophysical S-factor for the reaction of p14C capture to the ground state of 15N at astrophysical energies within the framework of the modified potential cluster model is considered.

  13. 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.

  14. Quantitative Identification of Biogenic Nonextractable Pesticide Residues in Soil by (14)C-Analysis.

    PubMed

    Poßberg, Claudia; Schmidt, Burkhard; Nowak, Karolina; Telscher, Markus; Lagojda, Andreas; Schaeffer, Andreas

    2016-06-21

    Quantification of nonextractable residues (NER) of pesticides in soil is feasible by use of radioactively labeled compounds, but structural information on these long-term stabilized residues is usually lacking. Microorganisms incorporate parts of the radiolabeled ((14)C-) carbon from contaminants into microbial biomass, which after cell death enters soil organic matter, thus forming biogenic nonextractable residues (bioNER). The formation of bioNER is not yet determinable in environmental fate studies due to a lack of methodology. This paper focuses on the development of a feasible analytical method to quantify proteinaceous carbon, since proteins make up the largest mass portion of bacterial cells. The test substance (14)C-bromoxynil after 56 days forms more than 70% of NER in soil. For further characterization of NER the amino acids were extracted, purified, and separated by two-dimensional thin-layer chromatography (TLC). Visualization of the (14)C-amino acids was performed by bioimaging, unambiguous identification by GC-MS and LC-MS/MS. Our analysis revealed that after 56 days of incubation about 14.5% of the (14)C-label of bromoxynil was incorporated in amino acids. Extrapolating this content based on the amount of proteins in the biomass (55%), in total about 26% of the NER is accounted for by bioNER and thus is not environmentally relevant. PMID:27192605

  15. Astrophysical S-Factor of Radiative p 14C Capture at Low Energies

    NASA Astrophysics Data System (ADS)

    Dubovichenko, S. B.; Burtebaev, N.; Dzhazairov-Kakhramanov, A. V.; Alimov, D. K.

    2016-04-01

    The possibility of describing the available experimental data on the astrophysical S-factor for the reaction of p14C capture to the ground state of 15N at astrophysical energies within the framework of the modified potential cluster model is considered.

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

    PubMed

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

    2012-09-10

    A method is described to determine the time of death of elephants. This is accomplished by analysis of the radionuclides 14C, 90Sr and 228/232Th in known samples of ivory, and in samples of unknown age. The reliability of this method is considerably increased by multi nuclide analysis. PMID:22717552

  17. 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.

  18. 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

  19. A kinetic and microautoradiographic study of sup 14 C-sucrose translocation into developing wheat grains

    SciTech Connect

    Ning Wang; Fisher, D.B. )

    1991-05-01

    The kinetics of {sup 14}C-photosynthate import by developing wheat grains was followed after pulse-labeling the flag leaf with {sup 14}CO{sub 2}. Samples were collected from four successive points along the transport pathway to and within the grain: exuding aphid stylets on the peduncle, exuding grain pedicels, the grain crease tissues, and the liquid contents of the endosperm cavity. In addition, microautoradiographs were prepared of the grain crease tissues during movement of the {sup 14}C pulse into the grain. At all times, sucrose accounted for 93 to 97% of the total {sup 14}C present at all four sampling sites. The main features of the {sup 14}C kinetics could be accounted for by a simple compartmental model consisting of sucrose pools in series. Microautoradiographs of the crease tissues showed fairly uniform labeling of vascular parenchyma at all times, with a sharp gradient in labeling across the chalaza to the nucellus. Thus the principal resistance to post-phloem solute transport through the maternal tissues appears to be in the symplastic pathway across the chalaza.

  20. 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.

  1. Measurement of 14C emission rates from a pressurised heavy water reactor.

    PubMed

    Joshi, M L; Ramamirtham, B; Soman, S D

    1987-06-01

    Carbon-14 is produced in pressurised heavy water reactors (PHWR), mainly as an activation product in the fuel. It is also produced in the heavy water used as the primary coolant and moderator, and is produced in the air in the annular space between the pressure tube and calandria tubes as well as in the free space in the calandria vault. The production rates in different systems of a PHWR are calculated on the basis of design parameters. During a period of 3 y, 14C released through the gaseous route has been measured at Rajasthan Atomic Power Station, Kota, India, a PHWR unit. These releases have been found to be mainly 14CO2. This reduced form of 14C is less than 5% of the releases. The normalised releases of 14C have a geometric mean of 5.17 TBq GWe-1 y-1 and a geometric standard deviation of 1.52. The 14C present in the form of carbonates in liquid effluents has also been measured and is 0.14% of the gaseous releases. PMID:3583743

  2. 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.

  3. Estimation of whole body protein synthesis from oxidation of infused [1-14C]leucine.

    PubMed

    Yagi, M; Walser, M

    1990-01-01

    In rats infused with NaH14CO3, 14CO2 exhalation approached an asymptotic rate equal to 96.0 +/- 1.3 (SD) % of the infusion rate of 14C in a monoexponential manner with a half-time of 20 min. In rats infused with [1-14C]leucine, 14CO2 exhalation (/0.96) approached an asymptotic value, (1-F), of 16-25% of 14C infusion rate (mean 20.4%) in a monoexponential manner with a half-time of approximately 31 min. Whole body protein synthesis (S) was calculated from 1-F and urea N plus ammonia N excretion (C) as S = CF/(1-F). S was a uniform function of body weight in these rats, in six additional rats in which S was measured 6 h after single intravenous injection of [1-14C]leucine and also in previously reported rats given single injections. The relationship was S (mg.100 g-1.h-1) = 11-0.143 body wt (g) +/- 8.3. In six of these rats, S was also estimated from the plateau specific activity of plasma leucine or plasma 2-ketoisocaproate (KIC); the former estimate of S was significantly lower (by an average of 17%), but S was the same when specific activity of KIC was employed. These results support the validity of the expired 14CO2 technique for measuring S. PMID:2154116

  4. DETECTION OF FECAL COLIFORMS IN WATER USING 14C-MANNITOL

    EPA Science Inventory

    Interest in rapid bacterial detection methods for sanitary indicator bacteria in water prompted a study of the use of 14C-mannitol (UL) to detect fecal coliforms (FC). implemethod was developed using m-FC broth, membrane filtration, and two-temperature incubation (35oC for 2 h, f...

  5. 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.

  6. DERMAL PENETRATION OF [14C] CAPTAN IN YOUNG AND ADULT RATS

    EPA Science Inventory

    Dermal penetration of [14C] Captan was determined in young (33 day old) and adult (82 day old) female Fischer 344 rats by an in vivo method and two in vitro methods. ermal penetration in vivo at 72 hours was about 9% of the dose in both young and adult rats. o significant differe...

  7. 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...

  8. 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

  9. 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.

  10. Indian Ocean Summer Monsoon (IOSM)-dynamics within the past 4 ka recorded in the sediments of Lake Nam Co, central Tibetan Plateau (China)

    NASA Astrophysics Data System (ADS)

    Kasper, Thomas; Haberzettl, Torsten; Doberschütz, Stefan; Daut, Gerhard; Wang, Junbo; Zhu, Liping; Nowaczyk, Norbert; Mäusbacher, Roland

    2012-04-01

    In September 2008 several cores (68 cm-115 cm length) (water depth: 93 m) were retrieved from Lake Nam Co (southern-central Tibetan Plateau; 4718 m a.s.l.). This study focuses on the interpretation of high-resolution (partly 0.2 cm) data from three gravity cores and the upper part of a 10.4 m long piston core, i.e., the past 4000 cal BP in terms of lake level changes, hydrological variations in the catchment area and consequently variations in monsoon strength. A wide spectrum of sedimentological, geochemical and mineralogical investigations was carried out. Results are presented for XRF core-scans, grain size distribution, XRD-measurements and SEM-image analyses. These data are complemented by an age-depth model using 210Pb and 137Cs analyses as well as eleven AMS-14C-ages. This model is supported by excellent agreement between secular variations determined on one of the gravity cores to geomagnetic field models. This is a significant improvement of the chronology as most catchments of lacustrine systems on the Tibetan Plateau contain carbonates resulting in an unknown reservoir effect for radiocarbon dates. The good correlation of our record to the geomagnetic field models confirms our age-depth model and indicates only insignificant changes in the reservoir effect throughout the last 4 ka. High (summer-) monsoonal activity, i.e. moist environmental conditions, was detected in our record between approximately 4000 and 1950 cal BP as well as between 1480 and 1200 cal BP. Accordingly, lower monsoon activity prevails in periods between the two intervals and thereafter. This pattern shows a good correlation to the variability of the Indian Ocean Summer Monsoon (IOSM) as recorded in a peat bog ˜1000 km in NE direction from Lake Nam Co. This is the first time that such a supra regional homogenous monsoon activity is shown on the Tibetan Plateau and beyond. Finally our data show a significant lake level rise after the Little Ice Age (LIA) in Lake Nam Co which is

  11. Mechanisms controlling the distribution and transport of {sup 14}C in a clay-rich till aquitard

    SciTech Connect

    Wassenaar, L.I.; Hendry, M.J.

    2000-06-01

    The distribution and transport of radiocarbon in dissolved inorganic carbon (DIC) in a thick clay-rich till aquitard was investigated. Radiocarbon activities decreased with depth from 109 percent modern carbon (pmC) in the surficial oxidized and fractured zone through the thick underlying unoxidized and nonfractured aquitard, reaching minimum values of between 3 and 5 pmC at between 29 and 37 m depth. Numerical simulations of diffusive transport of radiocarbon from the oxidized zone into the unoxidized zone during the Holocene closely approximated the measured values and showed that diffusive transport and radioactive decay fully described the transport of radiocarbon in the aquitard. The lack of geochemical reactions involving DIE permitted the age of DIC in the pore water deposited with the till to be estimated at 25 to 31 ka BP. Results of this study showed that the use of radiocarbon in the study of solute transport in aquitards provides age information that cannot be obtained from natural conservative tracers such as {delta}{sup 2}H and {delta}{sup 18}O. Their results also showed that the application of conventional radiocarbon age-dating models based on piston-flow transport assumptions, is inappropriate in diffusion-dominated environments and considerably overestimates the age of the ground water.

  12. [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

  13. KaVA ESTEMA project

    NASA Astrophysics Data System (ADS)

    Oyadomari, Miyako; Imai, Hiroshi; Cho, Se-Hyung; Asaki, Yoshiharu; Choi, Yoon-Kyong; Kim, Jaeheon; Yun, Youngjoo; Matsumoto, Naoko; Min, Cheul-Hong; Oyama, Tomoaki; Yoon, Sung-Chul; Yoon, Dong-Hwan; Kim, Dong-Jin; Dodson, Richard; Rioja, Maria; Burns, Ross; Orosz, Gabor; Nakagawa, Akiharu; Chibueze O, James; Nakashima, Jun-ichi; Sobolev, Andrey

    2016-07-01

    The ESTEMA (Expanded Study on Stellar Masers) project is one of three Large Programs of the KaVA (the combined array of the Korean VLBI Network and Japanese VLBI Exploration of Radio Astrometry), and conducted in 2015-2016. It aims to publish a database of the largest sample of VLBI images of circumstellar water (H2O) and silicon-monoxide (SiO) maser sources towards circumstellar envelopes (CSEs) of 80 evolved stars in late AGB to early post-AGB phase. Here we present the specifications of the ESTEMA observations and the planned scientific goals in order to share the basic information of the ESTEMA with astronomical community and encourage future collaborations with the ESTEMA and future follow-up observations for the targeted stars.

  14. 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

  15. 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.

  16. Metabolism of [14C]methamphetamine in man, the guinea pig and the rat

    PubMed Central

    Caldwell, J.; Dring, L. G.; Williams, R. T.

    1972-01-01

    1. The metabolites of (±)-2-methylamino-1-phenyl[1-14C]propane ([14C]methamphetamine) in urine were examined in man, rat and guinea pig. 2. In two male human subjects receiving the drug orally (20mg per person) about 90% of the 14C was excreted in the urine in 4 days. The urine of the first day was examined for metabolites, and the main metabolites were the unchanged drug (22% of the dose) and 4-hydroxymethamphetamine (15%). Minor metabolites were hippuric acid, norephedrine, 4-hydroxyamphetamine, 4-hydroxynorephedrine and an acid-labile precursor of benzyl methyl ketone. 3. In the rat some 82% of the dose of 14C (45mg/kg) was excreted in the urine and 2–3% in the faeces in 3–4 days. In 2 days the main metabolites in the urine were 4-hydroxymethamphetamine (31% of dose), 4-hydroxynorephedrine (16%) and unchanged drug (11%). Minor metabolites were amphetamine, 4-hydroxyamphetamine and benzoic acid. 4. The guinea pig was injected intraperitoneally with the drug at two doses, 10 and 45mg/kg. In both cases nearly 90% of the 14C was excreted, mainly in the urine after the lower dose, but in the urine (69%) and faeces (18%) after the higher dose. The main metabolites in the guinea pig were benzoic acid and its conjugates. Minor metabolites were unchanged drug, amphetamine, norephedrine, an acid-labile precursor of benzyl methyl ketone and an unknown weakly acidic metabolite. The output of norephedrine was dose-dependent, being about 19% on the higher dose and about 1% on the lower dose. 5. Marked species differences in the metabolism of methamphetamine were observed. The main reaction in the rat was aromatic hydroxylation, in the guinea pig demethylation and deamination, whereas in man much of the drug, possibly one-half, was excreted unchanged. PMID:4646771

  17. The search for cluster structure in 14C with the prototype AT-TPC

    NASA Astrophysics Data System (ADS)

    Fritsch, Adam Louis

    Certain light nuclei are known to have inherent cluster structuring, and the nature of the triple-alpha structure of carbon isotopes is a subject of active discussion in nuclear physics. Clustering in neutron-rich nuclei is of particular interest as such work could shed light on how neutrons affect alpha clustering, making 14C a logical candidate for such a study. Cluster structure in 14C was investigated at the University of Notre Dame with the prototype Active Target-Time Projection Chamber (AT-TPC). A 38.2 MeV secondary beam of 10Be was incident on an active target volume containing He:CO2 90:10 gas at 1 atm, in which trajectories of beam particles and reaction products were measured using the tracking capabilities of the prototype AT-TPC. Angular correlations of 10Be and alpha particles were used to reconstruct kinematics of scattering. Excitation functions and angular distributions were measured in both elastic and inelastic channels, which unraveled a number of resonances in 14C. Spin-parity assignments have been made for the elastic resonances by R-matrix analysis. Evidence of a positive-parity rotational band has been indicated by the 14C resonances. The proposed level scheme and the strong resonance strength observed in the inelastic channel are in line with the prediction by the antisymmetrized molecular dynamics (AMD) method indicating linear-chain structure in 14C. The results also demonstrate unique and powerful potentials of active-target technology in radioactive-beam experiments and are an important step toward the construction of the full-scale AT-TPC for the ReA3 facility at NSCL.

  18. Characteristics of 14C and 13C of carbonate aerosols in dust storm events in China

    NASA Astrophysics Data System (ADS)

    Chen, Bing; Jie, Dongmei; Shi, Meinan; Gao, Pan; Shen, Zhenxing; Uchida, Masao; Zhou, Liping; Liu, Kexin; Hu, Ke; Kitagawa, Hiroyuki

    2015-10-01

    In contrast with its decrease in western China deserts, the dust storm event in eastern China, Korea, and Japan shows an increase in frequency. Although the drylands in northeastern China have been recognized as an important dust source, the relative contributions of dust transport from the drylands and deserts are inconclusive, thus the quantification of dust storm sources in downwind area remains a challenge. We measured the 14C and 13C contents in carbonates of dust samples from six sites in China, which were collected for the duration of dust storm events in drylands, deserts, and urban areas. The δ13C of the dryland dust samples considerably varied in a range of - 9.7 to - 5.0‰, which partly overlapped the desert dust carbonate δ13C ranges. The 14C content of the dryland dust carbonates showed a narrow range of 60.9 ± 4.0 (as an average and 1 SD of five samples) percent modern carbon (pMC), indicating the enrichment of modern carbonate. Dust samples in desert regions contained relatively aged carbonates with the depleting 14C showing of 28.8 ± 3.3 pMC. After the long-range transport of the western China desert dust plume, the carbonates collected at the southern China remained the depletion of 14C (33.5 ± 5.3 pMC) as in the desert regions. On the other hand, the samples of dust storm events at the urban areas of eastern China showed an enrichment of 14C contents (46.2 ± 5.0 pMC, n = 7), which might be explained by the stronger contribution of modern-carbonate-rich dryland dust.

  19. 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.

  20. 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.

  1. 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.

  2. SARAL/AltiKa Project Overview

    NASA Astrophysics Data System (ADS)

    Picot, Nicolas; Sengenes, Pierre; Lambin, Juliette; Noubel, Jocelyne; Mazeau, Sophie; Verron, Jacques

    2015-04-01

    The SARAL-AltiKa satellite mission is an India-France ISRO-CNES joint project. The satellite has been put into orbit by a PSLV vehicle supplied by ISRO, and launched from Sriharikota, the main ISRO launch base, on Feb. 25, 2013. The SARAL (Satellite for ARgos and ALtika) payload consists of an ARGOS instrument, and an altimetry payload including the AltiKa radiometer-altimeter. SARAL/AltiKa is intended to be a gap filler mission between the RA-2 on-board ENVISAT and Sentinel-3. As such, SARAL/AltiKa is flying on the same orbit as ENVISAT. The special feature of SARAL/AltiKa is mainly related to a wideband Ka-band altimeter (35.75 GHz, 500 MHz), which is the very first satellite altimeter dedicated to oceanography to operate at such a high frequency. The AltiKa instrument consists in a Ka-band altimeter based on already developed subsystems inherited from Siral (CRYOSAT) and Poseidon-3 (JASON-2) in particular, and an embedded dual frequency radiometer. The altimeter and the radiometer share the same antenna. Due to the single frequency Ka-band altimeter, the enhanced bandwidth leads to a better vertical resolution. The spatial resolution is also improved, thanks to the Ka-band smaller footprint and the increased PRF. This talk will present the main characteristics of the mission and the main outcome regarding the data availability and overall quality after 2 years of mission. In particular, we will focus on the main advantages and/or drawbacks of the Ka band frequency compared to the classical Ku band used on other missions like Jason-2. A specific point will be performed on the rain attenuation and corresponding impacts on the altimeter data quality.

  3. 14C Terrestrial Ages of Meteorites from Desert Regions: Algeria and Australia

    NASA Astrophysics Data System (ADS)

    Jull, A. J. T.; Wlotzka, F.; Bevan, A. W. R.; Brown, S. T.; Donahue, D. J.

    1993-07-01

    The terrestrial age or residence time on the Earth's surface is important in determining the history of a meteorite. Carbon-14 has been used for a terrestrial-age indicator since 1962 [1,2]. Since 1984, small samples of meteorites of 0.1 to 0.5 g have been dated using accelerator mass spectrometry [3-5]. The precision of terrestrial age estimates is limited by the accuracy to which the saturated activity of ^14C in the meteorite is known. Jull et al. [4,5] used Bruderheim and some other chondrites to establish a saturated activity reference level. It is important to be aware that ^14C can vary with the depth and size of the object, and ^14C as a function of accurate depth has so far been measured only for one object, Knyahinya [7]. Carbon-14 is of particular interest in warmer climatic regions, where the storage time before a meteorite weathers away is expected to be much less than other locations, for example, Antarctica. This view was originally based on the work of Boeckl [7], who determined a "weathering half life" of some 3500 yr for chondrites from the southwestern U.S. This work was reinvestigated [5] and it was determined that the ^14C age distribution of the meteorites was longer than the earlier report. We have studied ^14C ages of meteorites from Roosevelt County, New Mexico [8], and from the western Libyan desert [9]. In both these areas meteorites of ages as old as 35,000 yr are observed, and the mean survival time at both locations is well over 10,000 yr. We have studied the ^14C age distribution of a large number of meteorites from Acfer, Algeria, and the Nullarbor Plain, Australia. Figure 1 presents the ^14C age distribution of Acfer samples compared to some other locations where a substantial number of ^14C ages have been obtained. The Algerian site shows a simple exponential dependence of terrestrial age vs. time, and no meteorites of >25 K.y. age. This is in contrast to the results from the southwestern U.S. [7] and from Roosevelt County [8]. One

  4. Seasonal variations of 14C and δ13C for cave drip waters in Ryugashi Cave, Shizuoka Prefecture, central Japan

    NASA Astrophysics Data System (ADS)

    Minami, Masayo; Kato, Tomomi; Horikawa, Keiji; Nakamura, Toshio

    2015-11-01

    Speleothem 14C has recently emerged as a potentially powerful proxy for hydrology changes in comparison with atmospheric 14C calibration curve, rather than as a direct dating tool, apart from a time marker using bomb peak of 14C. Some possible causes for the relationship between speleothem 14C content (or dead carbon fraction: DCF) and karst hydrology have been proposed, such as changes in temperature, precipitation, drip water flow dynamics, cave air ventilation, soil air pCO2. In this study, we investigated seasonal variation in 14C and δ13C of drip water in Ryugashi Cave, Shizuoka Prefecture, central Japan, to examine the causes of the 14C and δ13C variations in a speleothem. The results show that different 14C concentrations and δ13C values of drip water from the Ryugashi Cave, were exhibited at different sites of the Caves No. 1, No. 3, and No. 4, which have different temperature, air pCO2, and flow paths. Further, the 14C and δ13C of drip waters showed seasonal variations at all sites, which were lower in fall and winter, and higher in spring and summer, though the extent of the variations was different among the sites. The 14C in drip waters tended to be correlated with the drip rates: 14C tended to be higher in drip waters with higher drip rates, and also correlated with rainfall amount around the Ryugashi Cave, especially for the drip waters in Cave No. 3, which are considered to have simpler flow paths. The increase in rainfall amount could bring the increase in drip rate of drip water, and then the decrease in interaction between solution and karst, resulting in 14C increase (DCF decrease) in drip water. Accordingly, the reconstruction of precipitation could be performed using 14C variation in a speleothem formed by drip water with simple flow dynamics.

  5. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2006-09-01

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

  7. 14C dating of small archaeological samples: neolithic to iron age in the central alpine region

    NASA Astrophysics Data System (ADS)

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

    1984-11-01

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

  8. The dynamic transfer of 3H and 14C in mammals: a proposed generic model.

    PubMed

    Galeriu, D; Melintescu, A; Beresford, N A; Takeda, H; Crout, N M J

    2009-02-01

    Associated with the present debate regarding the potential revival of nuclear energy there is an increased interest in assessing the radiological risk to the public and also the environment. Tritium and (14)C are key radionuclides of interest in many circumstances (e.g. heavy water reactors, waste storage and fusion reactors). Because the stable analogues of these two radionuclides are integral to most biological compounds, their modelling should follow general principles from life sciences. In this paper, a model of the dynamics of (14)C and (3)H in mammals is proposed on the basis of metabolic understanding and of, as far as possible, readily available data (e.g. for organ composition and metabolism). The model is described together with validation tests (without calibration) for a range of farm animals. Despite simplifications, the model tests are encouraging for a range of animal types and products (tissues and milk), and further improvements are suggested. PMID:18830702

  9. 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.

  10. 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.

  11. Effect of chlorphentermine on incorporation of (/sup 14/C)choline in the rat lung phospholipids

    SciTech Connect

    Gonmori, K.; Morita, T.; Mehendale, H.M.

    1986-03-01

    The effect of chlorphentermine (CP) treatment (50 mg/kg/day, per os (po)) on the incorporation of (/sup 14/C)choline into rat lung phospholipid was studied. Total phospholipid content was increased 2.0-fold and 1.7-fold after seven and /sup 14/ days, respectively, compared with the pair-fed rats. The incorporation of (14C)choline into phosphatidylcholine (PC) was significantly inhibited by either seven or 14 days of CP treatment. Nevertheless, the PC content was significantly increased by day 7 and stayed elevated at day 14 of CP treatment. Choline and phosphorylcholine contents were significantly decreased by the CP treatment. These results suggest that the higher accumulation of PC is due to inhibition of enzymes involved in the hydrolysis of phospholipids rather than to a stimulation of the phospholipid synthesis.

  12. 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).

  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. The hardwater effect in AMS 14C dating of food crusts on pottery

    NASA Astrophysics Data System (ADS)

    Philippsen, Bente; Kjeldsen, Henrik; Hartz, Sönke; Paulsen, Harm; Clausen, Ingo; Heinemeier, Jan

    2010-04-01

    The pottery investigated in this study comes from late mesolithic inland sites next to rivers in Northern Germany. The first AMS 14C datings of food crusts from these sites showed surprisingly high ages, which could be caused by the hardwater effect. Modern samples from the rivers have ages of several hundred 14C years, and a modern food crust prepared from fish with a certain reservoir age shows the same age as the fish. Surprisingly, there was a large age difference between water samples and fish/mollusc shell from the same river. Associated archaeological samples of terrestrial and fluvial origin show age differences of several hundred and up to 3000 years. These high age differences are only to a limited extent transferred to the archaeological food crusts.

  16. Distribution of N-methyl-(14)C-labeled selegiline in the rat.

    PubMed

    Tekes, Kornélia; Pöstényi, Zita; Faigl, Erzsébet B; Magyar, Kálmán; Polyák, András; Trencsényi, György; Balogh, Lajos; Kalász, Huba

    2015-01-01

    Tissue distribution of selegiline including N-methyl-(14)C-selegiline was studied with three different techniques. Whole body autoradiography of labeled selegiline in rats completed the former results obtained in mice. Counting radioactivity by liquid scintillation method in various body compartments gave an in-depth numerical estimation of distribution, while RP-HPLC determination of selegiline determined the fate of intact, non-metabolized parent compound. Whole body autoradiography following 15 and 60 min of intraperitoneal application of N-methyl-(14)C-selegiline verified definite and time-dependent blood-brain penetration of selegiline. Quantitative determination of tissue concentrations by liquid scintillation and RP-HPLC methods following 5, 15, 60 and 180 min of intraperitoneal administration of selegiline unanimously verified both blood-brain and blood-testis penetration of the compound through the barrier. PMID:25886391

  17. {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.

  18. 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 of ca. 300 mg of fresh or rehydrated dry plant tissue samples in 10 ml of reagent-grade DMSO for 8h at 65/sup 0/C resulted in a stable, nonviscous solution with excellent liquid scintillation counting characteristics. 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.

  19. Hydrogen bond disruption in DNA base pairs from (14)C transmutation.

    PubMed

    Sassi, Michel; Carter, Damien J; Uberuaga, Blas P; Stanek, Christopher R; Mancera, Ricardo L; Marks, Nigel A

    2014-09-01

    Recent ab initio molecular dynamics simulations have shown that radioactive carbon does not normally fragment DNA bases when it decays. Motivated by this finding, density functional theory and Bader analysis have been used to quantify the effect of C → N transmutation on hydrogen bonding in DNA base pairs. We find that (14)C decay has the potential to significantly alter hydrogen bonds in a variety of ways including direct proton shuttling (thymine and cytosine), thermally activated proton shuttling (guanine), and hydrogen bond breaking (cytosine). Transmutation substantially modifies both the absolute and relative strengths of the hydrogen bonding pattern, and in two instances (adenine and cytosine), the density at the critical point indicates development of mild covalent character. Since hydrogen bonding is an important component of Watson-Crick pairing, these (14)C-induced modifications, while infrequent, may trigger errors in DNA transcription and replication. PMID:25127298

  20. Resonances in 14C observed in the 4He(10Be ,α )10Be reaction

    NASA Astrophysics Data System (ADS)

    Freer, M.; Malcolm, J. D.; Achouri, N. L.; Ashwood, N. I.; Bardayan, D. W.; Brown, S. M.; Catford, W. N.; Chipps, K. A.; Cizewski, J.; Curtis, N.; Jones, K. L.; Munoz-Britton, T.; Pain, S. D.; Soić, N.; Wheldon, C.; Wilson, G. L.; Ziman, V. A.

    2014-11-01

    The α (10Be,α )10Be resonant scattering reaction has been measured at nine 10Be beam energies from 25 to 48 MeV, scanning out resonances in 14C from excitation energies of 13 to 24 MeV. Angular distribution measurements were used to assign the spin and parity of 5- to resonances at Ex=18.82 (2 ) and 19.67(2) MeV and 6+ at Ex=20.80 (2 ) MeV. The data also strongly indicate a 3- resonance at 17.32(2) MeV. The systematic uncertainty on the excitation energies is 175 keV. An R -matrix analysis has been performed for the excitation energy range 16.5 to 22 MeV. The data are discussed in terms of cluster bands in 14C.

  1. Measurement of choline acetyltransferase with (/sup 14/C)acetate by a cycling procedure

    SciTech Connect

    O'Neill, J.J.; Hruschak, K.A.

    1987-06-01

    A multiple enzyme and multisubstrate cycling system is described for the radiometric determination of cholineacetyltransferase (ChAT) activity in crude tissue homogenates. The methods employs (/sup 14/C)acetate coupled with the enzymes acetate kinase (AK) and phosphotransacetylase (PTA) for the generation of (/sup 14/C)acetyl CoA. By recycling it was possible to avoid product inhibition of ChAT by CoA, ATP was maintained constant by rephosphorylation of ADP. Kinetics of the individual enzyme reactions were studied and the parameters obtained were used to select appropriate conditions to maintain linearity of varying amounts ChAT activity over a sixty minute time course. The sensitivity of the method is limited only by the specific activity of commercially available isotope labeled acetate.

  2. Behavior of 14C aflatoxin M1 during camembert cheese making.

    PubMed

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

    1990-01-01

    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 14C 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. PMID:2123931

  3. A low cost optical radiocarbon (14C) sensor for greenhouse gas source attribution

    NASA Astrophysics Data System (ADS)

    Long, D.; Fleisher, A. J.; Liu, Q.; Hodges, J. T.

    2015-12-01

    Radiocarbon (14C) provides a convenient means for the attribution of atmospheric greenhouse gases between anthropogenic and biogenic sources. Unfortunately, routine measurements are costly and require extensive sample preparation to meet sensitivity goals only achievable at large accelerator mass spectrometer facilities. We describe an alternate approach in which a laser is used to selectively record the absorption signatures of the 14C isotope of CO2. The designed instrument will allow for bench-top measurements of 14CO2 at and below ambient levels (~1.2 parts-per-trillion). The use of a commercially available mid-infrared quantum cascade laser as the optical source greatly reduces the cost of the instrument over more complicated sources and should allow for routine inline measurements.

  4. ( 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.

  5. A ~25 ka Indian Ocean monsoon variability record from the Andaman Sea

    USGS Publications Warehouse

    Rashid, H.; Flower, B.P.; Poore, R.Z.; Quinn, T.M.

    2007-01-01

    Recent paleoclimatic work on terrestrial and marine deposits from Asia and the Indian Ocean has indicated abrupt changes in the strength of the Asian monsoon during the last deglaciation. Comparison of marine paleoclimate records that track salinity changes from Asian rivers can help evaluate the coherence of the Indian Ocean monsoon (IOM) with the larger Asian monsoon. Here we present paired Mg/Ca and δ18O data on the planktic foraminifer Globigerinoides ruber (white) from Andaman Sea core RC12-344 that provide records of sea-surface temperature (SST) and δ18O of seawater (δ18Osw) over the past 25,000 years (ka) before present (BP). Age control is based on nine accelerator mass spectrometry (AMS) dates on mixed planktic foraminifera. Mg/Ca-SST data indicate that SST was ∼3 °C cooler during the last glacial maximum (LGM) than the late Holocene. Andaman Sea δ18Osw exhibited higher than present values during the Lateglacial interval ca 19–15 ka BP and briefly during the Younger Dryas ca 12 ka BP. Lower than present δ18Osw values during the BØlling/AllerØd ca 14.5–12.6 ka BP and during the early Holocene ca 10.8–5.5 ka BP are interpreted to indicate lower salinity, reflect some combination of decreased evaporation–precipitation (E–P) over the Andaman Sea and increased Irrawaddy River outflow. Our results are consistent with the suggestion that IOM intensity was stronger than present during the BØlling/AllerØd and early Holocene, and weaker during the late glaciation, Younger Dryas, and the late Holocene. These findings support the hypothesis that rapid climate change during the last deglaciation and Holocene included substantial hydrologic changes in the IOM system that were coherent with the larger Asian monsoon.

  6. Paleomagnetism and Mineralogy of Unusual Silicate Glasses and Baked Soils on the Surface of the Atacama Desert of Northern Chile: A Major Airburst Impact ~12ka ago?.

    NASA Astrophysics Data System (ADS)

    Roperch, P. J.; Blanco, N.; Valenzuela, M.; Gattacceca, J.; Devouard, B.; Lorand, J. P.; Tomlinson, A. J.; Arriagada, C.; Rochette, P.

    2015-12-01

    Unusual silicate glasses were found in northern Chile in one of the driest place on earth, the Atacama Desert. The scoria-type melted rocks are littered on the ground at several localities distributed along a longitudinal band of about 50km. The silicate glasses have a stable natural remanent magnetization carried by fine-grained magnetite and acquired during cooling. At one locality, fine-grained overbank sediments were heated to form a 10 to 20 cm-thick layer of brick-type samples. Magnetic experiments on oriented samples demonstrate that the baked clays record a thermoremanent magnetization acquired in situ above 600°C down to more than 10cm depth and cooled under a normal polarity geomagnetic field with a paleointensity of 40μT. In some samples of the silicate glass, large grains of iron sulphides (troilite) are found in the glass matrix with numerous droplets of native iron, iron sulphides and iron phosphides indicating high temperature and strong redox conditions during melting. The paleomagnetic record of the baked clays and the unusual mineralogy of the silicate glasses indicate a formation mainly by in situ high temperature radiation. Paleomagnetic experiments and chemical analyses indicate that the silicate glasses are not fulgurite type rocks due to lightning events, nor volcanic glasses or even metallurgical slags related to mining activity. The existence of a well-developped baked clay layer indicates that the silicate glasses are not impact-related ejectas. The field, paleomagnetic and mineralogical observations support evidence for a thermal event likely related to a major airburst. The youngest calibrated 14C age on a charcoal sample closely associated with the glass indicates that the thermal event occurred around 12 to 13 ka BP. The good conservation of the surface effects of this thermal event in the Atacama Desert could provide a good opportunity to further estimate the threats posed by large asteroid airbursts.

  7. Ka-band MMIC subarray technology program (Ka-Mist)

    NASA Astrophysics Data System (ADS)

    Pottinger, W.

    1995-09-01

    Ka-band monolithic microwave integrated circuit (MMIC) arrays have been considered as having high potential for increasing the capability of space, aircraft, and land mobile communication systems in terms of scan performance, data rate, link margin, and flexibility while offering a significant reduction in size, weight, and power consumption. Insertion of MMIC technology into antenna systems, particularly at millimeter wave frequencies using low power and low noise amplifiers in closed proximity to the radiating elements, offers a significant improvement in the array transmit efficiency, receive system noise figure, and overall array reliability. Application of active array technology also leads to the use of advanced beamforming techniques that can improve beam agility, diversity, and adaptivity to complex signal environments. The objective of this program was to demonstrate the technical feasibility of the 'tile' array packaging architecture at EHF via the insertion of 1990 MMIC technology into a functional tile array or subarray module. The means test of this objective was to demonstrate and deliver to NASA a minimum of two 4 x 4 (16 radiating element) subarray modules operating in a transmit mode at 29.6 GHz. Available (1990) MMIC technology was chosen to focus the program effort on the novel interconnect schemes and packaging requirements rather than focusing on MMIC development. Major technical achievements of this program include the successful integration of two 4 x 4 subarray modules into a single antenna array. This 32 element array demonstrates a transmit EIRP of over 300 watts yielding an effective directive power gain in excess of 55 dB at 29.63 GHz. The array has been actively used as the transmit link in airborne/terrestrial mobile communication experiments accomplished via the ACTS satellite launched in August 1993.

  8. Ka-Band MMIC Subarray Technology Program (Ka-Mist)

    NASA Technical Reports Server (NTRS)

    Pottinger, W.

    1995-01-01

    Ka-band monolithic microwave integrated circuit (MMIC) arrays have been considered as having high potential for increasing the capability of space, aircraft, and land mobile communication systems in terms of scan performance, data rate, link margin, and flexibility while offering a significant reduction in size, weight, and power consumption. Insertion of MMIC technology into antenna systems, particularly at millimeter wave frequencies using low power and low noise amplifiers in closed proximity to the radiating elements, offers a significant improvement in the array transmit efficiency, receive system noise figure, and overall array reliability. Application of active array technology also leads to the use of advanced beamforming techniques that can improve beam agility, diversity, and adaptivity to complex signal environments. The objective of this program was to demonstrate the technical feasibility of the 'tile' array packaging architecture at EHF via the insertion of 1990 MMIC technology into a functional tile array or subarray module. The means test of this objective was to demonstrate and deliver to NASA a minimum of two 4 x 4 (16 radiating element) subarray modules operating in a transmit mode at 29.6 GHz. Available (1990) MMIC technology was chosen to focus the program effort on the novel interconnect schemes and packaging requirements rather than focusing on MMIC development. Major technical achievements of this program include the successful integration of two 4 x 4 subarray modules into a single antenna array. This 32 element array demonstrates a transmit EIRP of over 300 watts yielding an effective directive power gain in excess of 55 dB at 29.63 GHz. The array has been actively used as the transmit link in airborne/terrestrial mobile communication experiments accomplished via the ACTS satellite launched in August 1993.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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

  14. Release of ( sup 14 C)5-hydroxytryptamine from human platelets by red wine

    SciTech Connect

    Jarman, J.; Glover, V.; Sandler, M. )

    1991-01-01

    Red wine, at a final dilution of 1/50, caused released of ({sup 14}C)5-hydroxytryptamine (5-HT) from preloaded platelets, an effect which was not observed with any white wines or beers tested. Since 5-HT, is probably released from body stores during migraine attacks and red wine is known to provoke migraine episodes in susceptible individuals, release of 5-HT, possibly from central stores, could represent a plausible mechanism for its mode of action.

  15. Long-term persistence of various 14C-labeled pesticides in soils.

    PubMed

    Jablonowski, Nicolai D; Linden, Andreas; Köppchen, Stephan; Thiele, Björn; Hofmann, Diana; Mittelstaedt, Werner; Pütz, Thomas; Burauel, Peter

    2012-09-01

    The fate of the 14C-labeled herbicides ethidimuron (ETD), methabenzthiazuron (MBT), and the fungicide anilazine (ANI) in soils was evaluated after long-term aging (9-17 years) in field based lysimeters subject to crop rotation. Analysis of residual 14C activity in the soils revealed 19% (ETD soil; 0-10 cm depth), 35% (MBT soil; 0-30), and 43% (ANI soil; 0-30) of the total initially applied. Accelerated solvent extraction yielded 90% (ETD soil), 26% (MBT soil), and 41% (ANI soil) of residual pesticide 14C activity in the samples. LC-MS/MS analysis revealed the parent compounds ETD and MBT, accounting for 3% and 2% of applied active ingredient in the soil layer, as well as dihydroxy-anilazine as the primary ANI metabolite. The results for ETD and MBT were matching with values obtained from samples of a 12 year old field plot experiment. The data demonstrate the long-term persistence of these pesticides in soils based on outdoor trials. PMID:22591787

  16. 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

  17. Enantioselective absorption and transformation of a novel chiral neonicotinoid [(14)C]-cycloxaprid in rats.

    PubMed

    Wu, Chengchen; Huang, Lei; Tang, Shenghua; Li, Zhong; Ye, Qingfu

    2016-06-01

    Neonicotinoid pesticides caused hazardous effects on pollinators and aquatic ecosystem. The new developed chiral cis-neonicotinoid cycloxaprid(CYC) is a highly potent substitute for low toxicity to bees and high efficiency on target-insects, but little is known about the metabolic dynamics of racemic CYC and its 2 enantiomers(SR and RS) in animal models. In this study, chiral separation of (14)C-labeled racemic CYC was performed in high-performance liquid chromatography under optimal conditions. For the first time that the stereoselectivity of the chiral neonicotinoid insecticide CYC was exhibited in rats after single dose oral administration using (14)C-labeled isotope trace technique. Enantioselective behaviors of racemic CYC, SR and RS were observed in blood metabolism, tissue distribution and excretion. The major deposition of (14)C were found in liver, lung, kidney and heart. After 24 h, skin and fat showed a strong bioaccumulation effect, and total excreted urine and feces of CYC, SR and RS were 50.4%, 59.7% and 74.5%, respectively. Enantiomer RS had the fastest absorption and elimination rates, and it was least bioaccumulated in rats. The results provide scientific basis and practical techniques for environmental risk assessment of chiral pesticides, especially neonicotinoids. PMID:27038208

  18. Histamine metabolism in cluster headache and migraine. Catabolism of 14C histamine.

    PubMed

    Sjaastad, O; Sjaastad, O V

    1977-09-12

    Various parameters of histamine metabolism were studied in patients with migraine, cluster headache and chronic paroxysmal hemicrania. These included urinary excretion of radioactivity and of 14C histamine and its metabolites, exhaled 14CO2 and fecal radioactivity after oral as well as subcutaneous administration of radioactive histamine. No marked deviation from the normal was found except in one patient with the cluster headache variant, chronic paroxysmal hemicrania, in whom an aberration in 14C histamine degradation seemed to be present. Only minute quantities of the 14C histamine metabolite C14 imidazoleacetic acid riboside seemed to be formed during a period with severe paroxysms. During a symptom-free period no deviation from normal was observed. The most likely explanation for this finding seems to be a defect in the conversion of imidazoleacetic acid to its riboside. This defect may possibly explain the increased urinary excretion of histamine in this particular patient. The relationship of this metabolic aberration to the production of headache still remains dubious for various reasons. PMID:72800

  19. 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.

  20. 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.

  1. 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.

  2. In vitro covalent binding of 3-(/sup 14/C)methylindole metabolites in goat tissues

    SciTech Connect

    Bray, T.M.; Carlson, J.R.; Nocerini, M.R.

    1984-05-01

    Covalent binding of 3-(/sup 14/C)methylindole (3(/sup 14/C)MI) in crude microsomal preparations of goat lung, liver, and kidney was measured to determine if a reactive intermediate was formed during the in vitro metabolism of 3-methylindole (3MI). The bound radioactivity was highest in lung compared to liver and kidney. The amount of bound radioactivity per nanomole of cytochrome P-450 was approximately 10 times higher in the lung compared to the liver. No detectable bound radioactivity was found when 3-(/sup 3/H)methyloxindole was used as the substrate. Cofactor requirements and the effects of inhibitors indicate that a mixed function oxidase (MFO) system is involved in formation of a reactive intermediate. Inhibitors and conjugating agents that are known to reduce the severity of 3MI-induced lung injury such as piperonyl butoxide (MFO inhibitor) and glutathione (conjugating agent) significantly decreased the in vitro binding of 3(/sup 14/C)MI. The results indicate that a reactive intermediate is produced during the metabolism of 3MI by the MFO system. The organ specificity in binding suggests that covalent binding by lung microsomes may be related to the mechanism of 3MI-induced lung injury.

  3. 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.

  4. 14C dating of the Early to Late Bronze Age stratigraphic sequence of Aegina Kolonna, Greece

    NASA Astrophysics Data System (ADS)

    Wild, E. M.; Gauß, W.; Forstenpointner, G.; Lindblom, M.; Smetana, R.; Steier, P.; Thanheiser, U.; Weninger, F.

    2010-04-01

    Aegina Kolonna, located in the center of the Saronic Gulf in the Aegean Mediterranean (Greece), is one of the major archaeological sites of the Aegean Bronze Age with a continuous stratigraphic settlement sequence from the Late Neolithic to the Late Bronze Age. Due to its position next to the maritime cross roads between central mainland Greece, the northeast Peloponnese, the Cyclades and Crete, the island played an important role in the trade between these regions. In the course of new excavations, which focused on the exploration of the Early, Middle and Late Bronze Age at Kolonna, several short lived samples from different settlement phases have been 14C-dated with the AMS method at the VERA laboratory. Bayesian sequencing of the 14C data according to the stratigraphic position of the samples in the profile was performed to enable estimates of the transition time between the cultural phases. The Aegina Kolonna 14C sequence is one of the longest existing so far for the Aegean Bronze Age, and therefore of major importance for the absolute Bronze Age chronology in this region. Preliminary results indicate that the Middle Helladic period seems to have started earlier and lasted longer than traditionally assumed. Further, at the present stage of our investigation we can give also a very tentative time frame for the Santorini volcanic eruption which seems to be in agreement with the science derived VDL date.

  5. 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.

  6. Revalidation and rationale for high pKa values of unconjugated bilirubin

    PubMed Central

    Ostrow, J Donald; Mukerjee, Pasupati

    2007-01-01

    Background Our prior solvent partition analysis, published in 1992, yielded pKa values for unconjugated bilirubin of about 8.1 and 8.4, but these results have been challenged and studies by other methods have suggested pKa values below 5.0. Methods We repeated our published solvent partition studies, using 14C-unconjugated bilirubin highly purified by extraction of residual labeled impurities from CHCl3 into an aqueous buffer, pH 7.0. Partition ratios at six pH values from 5.0 to 9.0 were determined by radioassay and compared with our prior values obtained by diazo assay. Results At pH values ranging from 4.8 to 9.2, stable aqueous/chloroform 14C-partition ratios did not differ significantly from our published partition ratios based on diazo assay. Conclusion These results support the high pKa values of unconjugated bilirubin, above 8.0, derived from our earlier solvent partition study. In both studies, our measurements were based on the rapid analysis of clearly under-saturated solutions of highly-purified bilirubin over a wide pH range, using properly purified and preserved solvents. No previous direct estimate of the aqueous pKa values of unconjugated bilirubin meets all these preconditions. Three theoretical factors acting in combination, each related to the unique, extensive internal H-bonding of the -COOH groups, are proposed to support high pKa values of unconjugated bilirubin in water: a) donation of an H-bond from the -OH moiety of the -COOH group, which is broken on ionization; b) hindered solvation of the -COO- group after ionization; and c) restricted rotation of the -COO- and -COOH groups. Our findings and rationale rebut methodological and theoretical criticisms leveled against our prior work. High pKa values for unconjugated bilirubin dictate that: a) bilirubin diacid, which readily diffuses across membranes and can cause neurotoxicity, is the dominant unbound bilirubin species of unconjugated bilirubin in plasma at physiological pH; b) at the near

  7. 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.

  8. Metabolic fate of the (14)C-labeled herbicide clodinafop-propargyl in soil.

    PubMed

    Jaquet, Jasmin; Weitzel, Pascal; Junge, Thorsten; Schmidt, Burkhard

    2014-01-01

    The metabolic fate of (14)C-phenyl-labeled herbicide clodinafop-propargyl (CfP) was studied for 28 days in lab assays using a soil from Germany (Ap horizon, silt loam, and cambisol). Mineralization amounted to 12.40% of applied (14)C after 28 days showing a distinct lag phase until day 7 of incubation. Portions of radioactivity extractable by means of 0.01 M CaCl2 solution (bioavailable fraction) decreased rapidly and were 4.41% after 28 days. Even immediately after application, only 57.31% were extracted with the aqueous solvent. Subsequent extraction using accelerated solvent extraction (ASE; acetonitrile/water 4:1, v/v) released 39.91% of applied (14)C with day 0 and 26.16% with day 28 of incubation from the samples. Non-extractable portions of radioactivity thus, increased with time amounting to 11.99% (day 0) and 65.00% (day 28). A remarkable increase was observed between 14 and 28 days correlating with the distinct increase of mineralization. No correlation was found throughout incubation with general microbial activity as determined by DMSO reduction. Analysis of the CaCl2 and ASE extracts by radio-TLC, radio-HPLC and GC/MS revealed that CfP was rapidly cleaved to free acid clodinafop (Cf), which was further (bio-) transformed; DT50 values (based on radio-TLC detection of the parent compound) were far below 1 day (CfP) and about 7 days (Cf). TLC analysis pointed to 2-(4-hydroxyphenoxy)-propionic acid as further metabolite. Due to fractionation of non-extractable residues, most of the (14)C was associated with fulvic and humic acids, portions in humin fractions and non-humics were moderate and low, respectively. Using a special strategy, which included pre-incubation of the soil with CfP and then mineralization of (14)C-CfP as criterion, a microorganism was isolated from the soil examined. The microorganism grew using CfP as sole carbon source with concomitant evolution of (14)CO2. The bacterium was characterized by growth on commonly used carbon

  9. 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.

  10. 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.

  11. 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

  12. 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

  13. 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

  14. Studies on the metabolism of [1-14C]5.8.11-eicosatrienoic (Mead) acid in rat hepatocytes.

    PubMed

    Retterstøl, K; Woldseth, B; Christophersen, B O

    1995-10-26

    The oxidation, esterification and formation of chain elongated and desaturated products of [1-14C]5,8,11-eicosatrienoic (Mead) acid was studied. Liver cells from essentially fatty acid deficient (EFAD) and control rats were used. The metabolism of [1-14C]20:4, n-6 and [1-14C]20:5, n-3 were studied under the same experimental conditions. More 20:3, n-9 than 20:4, n-6 and 20:5, n-3 was oxidised both in EFAD and control cells. 20:3, n-9 was elongated to [14C]22:3, n-9 in both cell types and significant amounts of [14C]22:4, n-9 were formed in EFAD cells. Less 20:3, n-9 was esterified in phospholipids and more in triacylglycerol than observed with 20:4, n-6 and 20:5, n-3 in both cell types. 20:3, n-9 was mainly esterified in phosphatidylcholine and little was esterified in phosphatidylethanolamine compared to 20:4, n-6 and 20:5, n-3. In comparison, 20:3, n-9 was rather efficiently esterified in phosphatidylinositol as 18:0-20:3. [14C]22:4, n-9 formed from 20:3, n-9 in EFAD hepatocytes was esterified in triacylglycerol, not in phospholipids, unlike [14C]22:5, n-6 and [14C]22:6, n-3 which were mainly esterified in phospholipids. PMID:7492619

  15. 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. PMID:16088336

  16. The Asteroid 2015 KA122

    NASA Astrophysics Data System (ADS)

    Vodniza, Alberto Quijano; Pereira, Mario Rojas

    2015-11-01

    The Asteroid “2015 KA122” was discovered on May 25/2015 by the Catalina Sky Survey. This object is not well known. Its absolute magnitude, of 23.2, indicates a diameter of about 70 meters. The asteroid was at aproximately 3.3 lunar distances from the Earth, on June 6/2015. It has an orbital period of 2.11 years. From our Observatory, located in Pasto-Colombia, we captured several pictures, videos and astrometry data during three days. Our data was published by the Minor Planet Center (MPC) and also appears at the web page of NEODyS. Our observatory’s code at the MPC is “H78”. Pictures of the asteroid were captured with the following equipment: 14” LX200 GPS MEADE (f/10 Schmidt-Cassegrain Telescope) and STL-1001 SBIG camera. Astrometry was carried out, and we calculated the orbital elements. We obtained the following orbital parameters: eccentricity = 0.4089630 +/- 0.00189, semi-major axis = 1.64254884 +/- 0.00505 A.U, orbital inclination = 12.68490 +/- 0.039 deg, longitude of the ascending node = 73.14715 +/- 0.0013 deg, argument of perihelion = 214.82393 +/- 0.007 deg, orbital period = 2.11 years (768.90 days), mean motion = 0.46819485 +/- 0.00216 deg/d, perihelion distance = 0.97080706 +/- 0.000119 A.U, aphelion distance = 2.31429061 +/- 0.0103 A.U. The parameters were calculated based on 81 observations (2015 June 3-5) with mean residual = 0.343 arcseconds. Our videos appear in the following links:http://spaceweathergallery.com/indiv_upload.php?upload_id=113197http://spaceweathergallery.com/indiv_upload.php?upload_id=113238&PHPSESSID=f2lkigjogsfgcmi1rscc9jil36http://spaceweathergallery.com/indiv_upload.php?upload_id=113257

  17. A 75 ka Stalagmite Paleoclimate Record from Northern Venezuela

    NASA Astrophysics Data System (ADS)

    Retrum, J. B.; Gonzalez, L. A.; Edwards, R.; Tincher, S. M.; Cheng, H.; Urbani, F.

    2011-12-01

    A stalagmite collected from Cueva Zarraga in the northern Venezuelan Andes was analyzed to determine local paleoclimatic history and help examine climate change in the Caribbean. Ages were determined by U/Th disequilibrium and the stalagmite shows a nearly complete record for ~ 75 ka. Two significant periods of non-deposition have been identified. The first period ranges between the Last Glacial Maximum at 19,820 ± 149 cal yr BP and a brief resumption of stalagmite growth at 15,409 ± 747 cal yr BP, likely representing the Bølling-Allerød interstadial. After the brief period of deposition, growth does not resume unil the Holocene at 10,408 ± 78 cal yr BP. Carbon and oxygen isotopes show a major depletion shift from the last glacial period to the Holocene, suggesting warmer and wetter conditions during the Holocene. The oxygen isotope depletion shift is also seen in the Cariaco Basin foraminifera record off the northern coast of Venezuela. While tempting to attribute δ13C depletion to decrease of the C4 plant contribution, there is no evidence that the area experience major vegetation changes. We attribute the δ13C depletion to enhanced recycling of soil CO2 resulting from canopy effects. Today, Cueva Zarraga is at the northern extent of the Inter-Tropical Convergence Zone (ITCZ). The cooler and drier conditions of the last glacial period suggest a southern displacement of the ITCZ. The close proximity of Cueva Zarraga to Cariaco Basin may allow for a high resolution tropical terrestrial and oceanic climatic response comparison.

  18. 50 CFR Table 14c to Part 679 - At-sea Operation Type Codes To Be Used as Port Codes for Vessels Matching This Type of Operation

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 50 Wildlife and Fisheries 13 2014-10-01 2014-10-01 false At-sea Operation Type Codes To Be Used as Port Codes for Vessels Matching This Type of Operation 14c Table 14c to Part 679 Wildlife and Fisheries... COMMERCE (CONTINUED) FISHERIES OF THE EXCLUSIVE ECONOMIC ZONE OFF ALASKA Pt. 679, Table 14c Table 14c...

  19. 50 CFR Table 14c to Part 679 - At-sea Operation Type Codes To Be Used as Port Codes for Vessels Matching This Type of Operation

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 13 2012-10-01 2012-10-01 false At-sea Operation Type Codes To Be Used as Port Codes for Vessels Matching This Type of Operation 14c Table 14c to Part 679 Wildlife and Fisheries... COMMERCE (CONTINUED) FISHERIES OF THE EXCLUSIVE ECONOMIC ZONE OFF ALASKA Pt. 679, Table 14c Table 14c...

  20. 50 CFR Table 14c to Part 679 - At-sea Operation Type Codes To Be Used as Port Codes for Vessels Matching This Type of Operation

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 13 2013-10-01 2013-10-01 false At-sea Operation Type Codes To Be Used as Port Codes for Vessels Matching This Type of Operation 14c Table 14c to Part 679 Wildlife and Fisheries... COMMERCE (CONTINUED) FISHERIES OF THE EXCLUSIVE ECONOMIC ZONE OFF ALASKA Pt. 679, Table 14c Table 14c...

  1. Variability of the northeast Atlantic sea surface Δ 14C and marine reservoir age and the North Atlantic Oscillation (NAO)

    NASA Astrophysics Data System (ADS)

    Tisnérat-Laborde, Nadine; Paterne, Martine; Métivier, Bernard; Arnold, Maurice; Yiou, Pascal; Blamart, Dominique; Raynaud, Stéphane

    2010-09-01

    We compiled new 14C analyses of mollusc shells (bivalves and gastropods) of known age from the collection of the Muséum National d'Histoire Naturelle de Paris and previously published data to investigate changes in the sea surface Δ 14C and reservoir age in the northeast Atlantic sector (NEA) between 1823 and 1952 AD. The mollusc shells are mainly located off the Atlantic margin between 45°N and 60°N downstream of the North Atlantic Current (NAC). We show that the temporal variability of the NEA Δ 14C is independent of the mollusc species, depth habitat, diet and latitudinal distribution. The quasi-null difference between mollusc Δ 14C and the marine model indicate that the mollusc Δ 14C reflects the Δ 14C values of open marine conditions. Between 1823 and 1850 AD, the pre-anthropogenic mean of Δ 14C is -45 ± 5‰, corresponding to a reservoir age of 380 ± 60 years and a Δ R value of -7 ± 50 years, in agreement with previous estimates. The Δ 14C values show a significant long-term decrease of ˜12‰ from 1823 to 1952 AD attributed to changes in 14C production between 1823 and 1900 AD and the Suess effect between 1900 and 1952 AD. Between 1885 and 1950 AD, Δ 14C fluctuations of ˜10‰ up to 18‰ occurred in the northeast Atlantic, corresponding to reservoir age variations of ˜90 years up to 170 years. These fluctuations are very similar to changes of Δ 14C in the southern Norwegian Sea. Spectral analyses of the NEA Δ 14C exhibit quasi-periodic cycles of about 7.4 years, almost equivalent to the quasi-periodic cycles of the winter index of the North Atlantic Oscillation (NAO) with a period around 6.5 years. We find that changes of NEA Δ 14C cannot be attributed to changes in river runoff or the precipitation/evaporation budget. The Δ 14C lows (or high reservoir ages) correspond to the more intense phase of the winter NAO, with a time lag of ˜1-3 years. Such a time lag may reflect the eastward transit time of upstream changes originating in the

  2. Combining 14C/U-Th Series Geochronology and Stable/Clumped Isotope Geochemistry of MIS 2 Lake Tufas of Lake Chewaucan, Oregon, USA to Reconstruct Deglacial Climate in the Pacific Northwest

    NASA Astrophysics Data System (ADS)

    Hudson, A. M.; Quade, J.; Ali, G.; Boyle, D. P.; Bassett, S.; Huntington, K. W.

    2015-12-01

    Shoreline deposits surrounding closed-basin lake remnants in the Great Basin of North America have been critical to defining the timing and extent of lake highstands during Marine Isotope Stage 2, recording the wettest climate conditions during the last glacial cycle. We present 14C and U-Th series ages and stable and clumped isotope results from MIS 2 microbialite tufas of pluvial Lake Chewaucan, southern Oregon. At ~42.5°N latitude, the Chewaucan basin is the one of the northernmost lake systems in the Great Basin, a critical location for investigating regional climate. Dating of modern tufa and DIC indicates no 14C reservoir effect. Low lake depth is observed for peak LGM conditions (21.0 ka, +11 m above modern), consistent with regional records and climate model results. In contrast with other Great Basin lake reconstructions for deglacial MIS 2, Lake Chewaucan was deepest during the Bølling/Ållerod (B/A; 14.5-13.0 ka, +50 m) and early Holocene (10.9-9.5 ka +15 m) warm periods, with lowstands during Heinrich Event 1 (+0-1 m) and Younger Dryas cold periods (+0 m). This supports previous evidence for wet interstadials in the Pacific Northwest (PNW) during MIS 2-3, the opposite of the central/southern Great Basin, where stadials correlate with wet conditions. δ18O values of tufas (-0.9 to -4.4‰ PDB) reflect high evaporation relative to inflowing meteoric water (-13.6‰ SMOW), and lake water (-6.7 SMOW). δ13C values (+1.7 to +4.5‰ PDB) are consistent with equilibrium with lake DIC (+1.5‰ PDB) and atmospheric CO2, supporting atmospheric 14C equilibrium. Clumped isotope temperatures for modern tufa (20±7°C) are consistent with summer lake surface temperature for modern lake remnant, Abert Lake (17.7-22.0°C), supporting previous clumped isotope results for tufas as summer temperature indicators. Clumped temperatures for the B/A highstand are 19±4°C, indicating near modern lake temperatures during deepest lake conditions. 13±4°C is indicated for the

  3. Δ14C level of annual plants and fossil fuel derived CO2 distribution across different regions of China

    NASA Astrophysics Data System (ADS)

    Xi, X. T.; Ding, X. F.; Fu, D. P.; Zhou, L. P.; Liu, K. X.

    2013-01-01

    The 14C level in annual plants is a sensitive tracer for monitoring fossil fuel derived CO2 in the atmosphere. Corn leave samples were selected from different regions of China, including high mountains in the Tibetan Plateau, grassland in Inner Mongolia, and inland and coastal cities during the summer of 2010. The 14C/12C ratio of the samples was measured with the NEC compact AMS system at the Institute of Heavy Ion Physics, Peking University. The fossil fuel derived CO2 was estimated by comparing the measured Δ14C values of corn leave samples to background atmospheric Δ14C level. The influences of topography, meteorological conditions and carbon cycling processes on the fossil fuel derived CO2 concentration are considered when interpreting the data. Our results show a clear association of the low Δ14C values with regions where human activities are intensive.

  4. 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.

  5. Prediction of [3-(14)C]phenyldodecane biodegradation in cable insulating oil-spiked soil using selected extraction techniques.

    PubMed

    Dew, Nadia M; Paton, Graeme I; Semple, Kirk T

    2005-11-01

    This study investigated the use of an aqueous hydroxypropyl-beta-cyclodextrin (HPCD) shake extraction in predicting microbial mineralisation and total loss of [3-(14)C]phenyldodecane associated activity in soils spiked with cable insulating oil; phenyldodecane represents a major constituent of cable insulating oil. Direct comparisons were made between freshly spiked and aged soils, and following composting. Soil was spiked with [3-(14)C]phenyldodecane (10mg kg(-1)) and stored in microcosms and aged for 1, 23, 44, 65, 90 and 153 d. At each sample time point, a variety of analyses were performed to assess the relationship between chemical and biological techniques in determining mineralisation and loss of (14)C-activity in soils under composting and non-composting conditions. Methods included determination of total (14)C-activity remaining, dichloromethane (DCM) and HPCD extractions. Mineralisation assays were also carried out to quantify the fraction of (14)C-phenyldodecane associated activity available for degradation in the soil at each time point. DCM and HPCD extractability were compared to contaminant mineralisation and to total loss of (14)C-phenyldodecane associated activity from the microcosms, after 153 d incubation. Poor relationships were found between (i) the amount of (14)C-activity mineralised and the fraction removed from the soils using DCM extraction and (ii) DCM extraction and total loss of [(14)C]phenyldodecane associated activity from the soil systems. Good relationships were observed between (i) the amount of (14)C-activity mineralised and the fraction removed from the soils using the HPCD extraction and (ii) HPCD extraction and total loss of [(14)C]phenyldodecane associated activity from the soil systems. The results of this study indicate that an aqueous HPCD extraction may be a useful tool in assessing the microbial availability of phenyldodecane in freshly and aged spiked soils. PMID:15949878

  6. BP details new recycling process

    SciTech Connect

    Chynoweth, E.

    1992-04-22

    BP Chemicals (London) is developing a preprocessing thermal cracker for recycling mixed plastics waste as an add-on to existing petrochemicals or refinery complexes. The company is currently discussing the technology with other plastic producers to {open_quotes}move forward together,{close_quotes} say Serge Huybrechts, branch R&D manager at BP Chemicals at Grangemouth. He says the unit would be able to deliver an intermediate feed of similar composition to chemical naphtha for chemical or refinery processes including steam cracking, catalytic cracking, coking, gasification, and hydrocracking. In comparison, pyrolysis gives a range of products, from light gas to heavy aromatics, that are difficult to integrate into existing equipment.

  7. 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

  8. Feasibility study of a Ka-/Ka-band dichroic plate with stepped rectangular apertures

    NASA Technical Reports Server (NTRS)

    Chen, J. C.

    1993-01-01

    For the Cassini spacecraft mission, a dichroic plate is needed to pass Ka-band uplink (34.2 to 34.7 GHz) and to reflect Ka-band downlink (31.8 to 32.3 GHz) for dual-frequency operation in the Deep Space Network. The special characteristic of the Ka-/Ka-band dichroic plate is that the pass band and the reflective band are only 1.9 GHz (5.7 percent) apart. A thick dichroic plate with stepped rectangular apertures that function as resonator filters was chosen for the Ka-/Ka-band dichroic plate design. The results of the feasibility study are presented in this article.

  9. 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

  10. 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.

  11. Uptake of (/sup 14/C)deoxyglucose into brain of young rats with inherited hydrocephalus

    SciTech Connect

    Richards, H.K.; Bucknall, R.M.; Jones, H.C.; Pickard, J.D.

    1989-02-01

    The effect of hydrocephalus on cerebral glucose utilization as reflected by deoxyglucose uptake has been examined in rats with inherited hydrocephalus at 10, 20, and 28 days after birth using a semiquantitative method. Injection of (14C)deoxyglucose intraperitoneally was followed by freezing the brain, sectioning, and quantitative autoradiography of 10 brain regions. Brain (14C) concentration, cortical thickness, and plasma glucose concentrations were measured. Maximal thinning of the cerebral cortex had already occurred by 10 days after birth, although obvious symptoms such as gait disturbance developed after 20 days. In control rats, the cerebral isotope concentration was lower and more homogeneous at 10 days than at 20 or 28 days, which may be a reflection of the use of metabolic substrates other than glucose in younger animals. In order to make comparisons between control and hydrocephalic groups, tissue isotope concentrations were normalized to cerebellar cortex which was not affected by the hydrocephalus at any age. In hydrocephalic rats at 10 and 20 days, the concentration of (14C) was lower in all areas except the inferior colliculi and pons but the reduction was only significant in the sensory-motor cortex at 10 days and in the caudate nuclei at 20 days. By 28 days after birth, all areas except the cerebellum (six cortical regions, inferior colliculi, pons, and caudate) had significantly lower isotope concentrations in the hydrocephalic group. It is concluded that cerebral glucose metabolism is significantly reduced by 28 days after birth in H-Tx rats with congenital hydrocephalus and that less marked reductions occur prior to 28 days.

  12. 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.

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

    NASA Astrophysics Data System (ADS)

    Roth, R.; Joos, F.

    2013-03-01

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

  14. Double labeling autoradiography. Cell kinetic studies with /sup 3/H- and /sup 14/C-thymidine

    SciTech Connect

    Schultze, B.

    1981-01-01

    Examples of the multiple applicability of the double labeling method with /sup 3/H- and /sup 14/C-TdR are demonstrated. Double labeling with /sup 3/H- and /sup 14/C-TdR makes it possible to determine the cycle and its phases with high precision by modifying the usual percent labeled mitoses method with a single injection of /sup 3/H-TdR. In addition, data is provided on the variances of the transit times through the cycle phases. For example, in the case of the jejunal crypt cells of the mouse, the transit times through successive cycle phases are uncorrelated. In the case of glial cells the double labeling method provides cell kinetic parameters despite the paucity of proliferating glial cells. In the adult untreated animal, glial cell mitoses are so rare that the percent labeled mitoses method can not be utilized. However, the S-phase duration can be measured by double labeling and the cycle time can be determined by the so-called method of labeled S phases. With the latter method the passage through the S phase of the /sup 3/H-TdR-labeled S phase cells can be registered by injecting /sup 14/C-TdR at different time intervals following /sup 3/H-TdR application. In this way an S-phase duration of about 10 hr and a cycle time of about 20 hr was found for glial cells in the adult untreated mouse. An exchange of glial cells between the growth fraction and the nongrowth fraction has also been shown by double labeling. A quite different application of the double labeling method with 3H- and /sup 14/C-TdR is the in vivo study of the cell cycle phase-specific effect of drugs used in chemotherapy of tumors. The effect of vincristine on these cells has been studied. Vincristine affects cells in S and G2 in such a manner that they are arrested during the next metaphase and subsequently become necrotic. It has no effect on G1 cells.

  15. Magmatic CO2 emissions at Mammoth Mountain, California, tracked by 14C in tree core

    NASA Astrophysics Data System (ADS)

    Evans, B.; Mangan, M.; McGeehin, J. P.; King, J.; Lewicki, J. L.; Hilley, G. E.

    2011-12-01

    Magmatic CO2 efflux to the atmosphere causes persistent depletion of 14C in the wood of trees that grow in areas of strong emissions. The record of 14C depletion in core from a surviving tree at the Horseshoe Lake tree-kill area, on the S flank of Mammoth Mountain volcano, has been updated to cover the time period 1984 to 2010. The amount of depletion was reasonably stable in annual growth rings for years 1995-2009 and indicates that the magmatic CO2 component in air at canopy height was 31±7 ppmv. Depletion increased sharply in the 2010 ring, yielding a magmatic CO2 concentration of 56 ppmv. This observation is consistent with accumulation chamber and eddy covariance measurements from the area, which indicate that magmatic CO2 effluxes and near-surface atmospheric concentrations increased during 2010. The agreement between tree-core and direct gas measurements suggests that the selected tree may be suitable for constraining the long-term record of CO2 emission strength at Horseshoe Lake, but the ability of a single tree to constrain total CO2 discharge from a broad region of diffuse emissions needs investigation. New concentration source-area modeling based on local atmospheric data measured by a 3-m tall eddy covariance tower suggests that the 13-m tall tree cored may provide a weighted integration of CO2 emission strength over an area at least as large as the Horseshoe Lake gas anomaly (0.3 km2). If the tree-core record accurately reflects total CO2 discharge, then emission strength in 2010 approached that in 1990, when anomalous gas efflux began in the aftermath of a 6-month seismic swarm linked to upflow of magmatic fluids. The apparent increase in emission strength in 2010 may correlate with a recent resurgence in seismicity beneath Mammoth Mountain and an increase in the 3He/4He ratio in fumarolic emissions near the summit, both of which began in 2009. If so, a correlative increase in 14C depletion is likely to exist in trees at other areas around the

  16. 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. PMID:20189632

  17. 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.

  18. 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.

  19. Tritium and(14)C counting in tissue samples by using liquid scintillation method.

    PubMed

    Parekh, C K; Eigen, E

    1968-05-01

    The combustion method has been modified to increase the recovery of tritiated water after combustion of a tritium-labeled tissue sample. This was accomplished by cooling the bottom of the combustion flask in a dry ice-acetone bath while irradiating the top with an infrared lamp. The procedure resulted in at least 92% to 102% recovery of the tritiated water. The NCS solubilizer was found to be superior to hyamine for solubilizing(14)C labeled tissue samples. The samples yielded light yellow-colored solutions when incubated for 15 hr at 50-55C. The counting efficiency of this solution was 75% or higher. PMID:17805860

  20. 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.

  1. 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)

  2. 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

  3. Using 14C and 3H to delineate a recharge 'window' into the Perth Basin aquifers, North Gnangara groundwater system, Western Australia.

    PubMed

    Meredith, Karina; Cendón, Dioni I; Pigois, Jon-Philippe; Hollins, Suzanne; Jacobsen, Geraldine

    2012-01-01

    The Gnangara Mound and the underlying Perth Basin aquifers are the largest source of groundwater for the southwest of Australia, supplying between 35 and 50% of Perth's potable water (2009-2010). However, declining health of wetlands on the Mound coupled with the reduction in groundwater levels from increased irrigation demands and drier climatic conditions means this resource is experiencing increased pressures. The northern Gnangara is an area where the Yarragadee aquifer occurs at shallow depths (~50 m) and is in direct contact with the superficial aquifer, suggesting the possibility of direct recharge into a generally confined aquifer. Environmental isotopes ((14)C and (3)H) and hydrochemical modelling were used to assess the presence of a recharge 'window' as well as understand the groundwater residence time within different aquifers. Forty-nine groundwater samples were collected from depths ranging from 11 to 311 m below ground surface. The isotopic variation observed in the superficial aquifer was found to be controlled by the different lithologies present, i.e. quartz-rich Bassendean Sand and carbonate-rich sediments of the Ascot Formation. Rainfall recharge into the Bassendean Sand inherits its dissolved inorganic carbon from the soil CO(2). Organic matter throughout the soil profile is degraded by oxidation leading to anoxic/acidic groundwater, which if in contact with the Ascot Formation leads to enhanced dissolution of carbonates. Hydrochemical mass balance modelling showed that carbonate dissolution could contribute 1-2 mmol kg(-1) of carbon to groundwaters recharged through the Ascot Formation. The corrected groundwater residence times of the Yarragadee aquifer in the northern part of the study area ranged from 23 to 35 ka, while waters in the southeastern corner ranged from sub-modern to 2 ka. Groundwater ages increase with distance radiating from the recharge 'window'. This study delineates a recharge 'window' into the commonly presumed confined

  4. Timing of wet episodes in Atacama Desert over the last 15 ka. The Groundwater Discharge Deposits (GWD) from Domeyko Range at 25°S.

    NASA Astrophysics Data System (ADS)

    Sáez, Alberto; Godfrey, Linda V.; Herrera, Christian; Chong, Guillermo; Pueyo, Juan J.

    2016-08-01

    A chronologically robust reconstruction of timing and dynamics of millennial time scale wet episodes encompassing the entire Atacama Desert during the last 15 ka has been constructed. To accomplish this, a new composite paleoclimatic record from Groundwater Discharge Deposits (GWD) in the Sierra de Varas (Domeyko Range, southern Atacama in Chile at 25°S) has been compiled and compared with other published paleohydrologic records from the Atacama region. In Sierra de Varas (SV), three millennial timescale wet climate phases have been characterized: around 14.5 ka cal BP, 12.2-9.8 ka cal BP, and 4.7 ka cal BP to the present day. These wet phases are interpreted from intervals of GWD facies formed during periods when the springs were active. GWD facies include: (1) black organic peat, rooted mudstones and sandstones formed in local wetland environments, and (2) gypsum-carbonate rich layers formed by interstitial growth. GWD intervals alternate with gravelly alluvial material deposited during arid phases. A trend towards less humid conditions during the Late Holocene wet episode characterizes GWD sedimentary series in Sierra the Varas, suggesting the onset of a dry episode over the last few centuries. Around 0.7 ka BP a very short wet episode is recorded in the central part of the desert suggesting this was the time of maximum humidity for the entire late Holocene wet period. A brief arid phase occurred between 1.5 and 2.0 ka BP indicated by the absence of GWD in the Domeyko Range. The paleoclimatic reconstruction encompassing the entire Atacama region shows that both the intensity and occurrence of wetter conditions were governed mainly by the distance to the source of moisture, and secondarily by the elevation of the sites. In the northern Atacama (16-20°S), four wet phases fed by N-NE summer monsoon precipitations have been proposed: Tauca phase (18-14 ka cal BP) and Coipasa phase (13-10 ka cal BP) during the Late Glacial, followed by Early Holocene and Late

  5. A prototype Ka-/Ka-band dichroic plate with stepped rectangular apertures

    NASA Technical Reports Server (NTRS)

    Chen, J. C.; Stanton, P. H.; Reilly, H. F., Jr.

    1996-01-01

    A prototype five-layer Ka-/Ka-band dichroic plate was fabricated and measured. This dichroic plate was designed to pass Ka-band uplink (34.2-34.7 GHz) and to reflect Ka-band downlink (31.8-32.3 GHz) for dual-frequency operation in the Deep Space Network to support the future Cassini mission. The theoretical calculation and the experimental measurement of the reflected resonant frequencies were within 0.24 percent for circular polarization. The computer program, which was used to design the dichroic plate with stepped apertures, was then verified.

  6. Retention of 14C-Labeled Tuberculin Purified Protein Derivative in the Skin of Sensitized and Nonsensitized Animals

    PubMed Central

    Landi, Silvio; Tseng, Men C.; Held, Hans R.

    1974-01-01

    Tuberculin purified protein derivative labeled with 14C ([14C]PPD) with a biological potency equivalent to the International Standard for tuberculin PPD was used to study the retention of tuberculin PPD in the skin of sensitized and nonsensitized animals. We found that [14C]PPD was almost entirely cleared from the skin test site during the first 18 to 24 h after injection and that when approximately 5% of the initial concentration of [14C]PPD was present in the skin test site, the size of the tuberculin skin reaction in sensitized guinea pigs was at its maximum. Furthermore, the addition of 5 or 50 μg of Tween 80 per ml to a solution of PPD did not change either the rate of clearance of PPD from the skin test sites of sensitized guinea pigs or the size of the tuberculin skin reactions. There was no difference in the rate of clearance of [14C]PPD from the skin test sites between sensitized and nonsensitized guinea pigs and between guinea pigs of different age. However, there was a significant difference in the rate of clearance of [14C]PPD between the guinea pig and the mouse. Finally, the percentage of [14C]PPD retained in the site of injection at 24 h was in the neighborhood of 5% of the initial concentration of the solution of PPD injected. The significance of these phenomena is discussed. Images PMID:4208638

  7. Energy metabolism used as a tool to model the transfer of 14C and 3H in animals.

    PubMed

    Melintescu, A; Galeriu, D

    2010-11-01

    The transfer through the environment of (3)H and (14)C must be modelled differently than that of other radionuclides released from nuclear reactors because hydrogen and carbon enter straight into the life cycle. A solid understanding of the behaviour of (3)H and (14)C in the food chain is essential because (3)H may be released in large quantities from future thermonuclear reactors, and (14)C accumulates in the environment because of its long half-life. For the present study, the hypothesis that both (3)H and (14)C metabolism in mammals can be modelled based on the understanding of energy metabolism has been tested. Recently published results demonstrate that the loss rate of organically bound tritium and (14)C from tissues of laboratory and farm animals can be assessed based upon their specific metabolic rates and enthalpy of combustion; the same is true for human beings. The improved model presented here relates the dynamics of organically bound tritium and (14)C within organs to the whole body and has been expanded to account for the growth of ruminants. The improved model has been expanded and applied for (14)C transfer in wild mammals and has been modified to apply to birds. PMID:20532542

  8. Distribution of aged atrazine related 14C-residues in natural soil following incubation with the earthworm Apporectodea caliginosa.

    NASA Astrophysics Data System (ADS)

    Andreou, K.; Jablonowski, N.; Jones, K.; Burauel, P.; Semple, K.

    2009-04-01

    The distribution and localisation of atrazine related 14C-residues into the different physical fractions of soil may reveal information on processes taking place in soil. Soils amended with 14C-atrazine, were aged for 22 years under environmental conditions in a lysimeter in Germany. The soil was sampled and subjected to physical and chemical fractionation before and after incubation for 7 days with the earthworm Apporectodea caliginosa. No significant change in the soil physical and chemical fractionation of the atrazine related 14C-residues and organic carbon was observed in this study due to the activity of the A. caliginosa. The smaller size soil fractions (Microaggregates and Colloids) were highly enriched with aged atrazine 14C-residues equivalents and organic carbon. Also the humic acid extracted using a simple alkaline extraction have were also enriched with aged atrazine 14C-residues equivalents. The low organic carbon content of the soil, the absence of relatively fresh organic matter and the long ageing time might explain the limited bioavailability of the atrazine related 14C-residues to the earthworm. This finding is of particular importance given that the soil used here was aged under natural environmental conditions compared to laboratory studies. Earthworms are important species in soil ecology and thus, the question of the bioavailability of aged pesticide residues to such organism is critical. The bioavalability of the atrazine 14C-residues equivalent was absent in the current study illustrating that those aged residues posed minimal risk to earthworms.

  9. Distribution of aged atrazine related 14C-residues in natural soil following incubation with the earthworm Apporectodea caliginosa

    NASA Astrophysics Data System (ADS)

    Andreou, Kostas; Semple, Kirk; Jones, Kevin

    2010-05-01

    The distribution and localisation of atrazine related 14C-residues into the different physical fractions of soil may reveal information on processes taking place in soil. Soils amended with 14C-atrazine, were aged for 22 years under environmental conditions in a lysimeter in Germany. The soil was sampled and subjected to physical and chemical fractionation before and after incubation for 7 days with the earthworm Apporectodea caliginosa. No significant change in the soil physical and chemical fractionation of the atrazine related 14C-residues and organic carbon was observed in this study due to the activity of the A. caliginosa. The smaller size soil fractions (Microaggregates and Colloids) were highly enriched with aged atrazine 14C-residues equivalents and organic carbon. Also the humic acid extracted using a simple alkaline extraction have were also enriched with aged atrazine 14C-residues equivalents. The low organic carbon content of the soil, the absence of relatively fresh organic matter and the long ageing time might explain the limited bioavailability of the atrazine related 14C-residues to the earthworm. This finding is of particular importance given that the soil used here was aged under natural environmental conditions compared to laboratory studies. Earthworms are important species in soil ecology and thus, the question of the bioavailability of aged pesticide residues to such organism is critical. The bioavalability of the atrazine 14C-residues equivalent was absent in the current study illustrating that those aged residues posed minimal risk to earthworms.

  10. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    Radiocarbon analyses are a key tool for quantifying the dynamics of carbon cycling and storage in both modern soils and Quaternary paleosols. Frequently, bulk 14C dates of paleosol organic carbon provide ages older than the time of soil burial, and 14C dates of geochemical fractions such as alkali and acid extracts (operationally defined as humic acids) can provide anomalously old ages when compared to coeval plant macrofossil dates. Ramped pyrolysis radiocarbon analysis of sedimentary organic material has been employed as a tool for investigating 14C age spectra in sediments with multiple organic carbon sources. Here we combine ramped pyrolysis 14C analysis and biomarker analysis (lignin-phenols and other cupric oxide products) to provide information on the source and diagenetic state of the paleosol organic carbon. We apply these techniques to immature early Holocene brackish wetland entisols from three sediment cores in southeastern Louisiana, along with overlying basal peats. Surprisingly, we find narrow 14C age spectra across all thermal aliquots f