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Sample records for 14c reservoir ages

  1. 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 ages14C) 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

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

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

  4. 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

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

    NASA Astrophysics Data System (ADS)

    Forman, Steven L.; Polyak, Leonid

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

  6. 87Sr/86Sr as a quantitative geochemical proxy for 14C reservoir age in dynamic, brackish waters: Assessing applicability and quantifying uncertainties

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

  7. 87Sr/86Sr as a quantitative geochemical proxy for 14C reservoir age in dynamic, brackish waters: assessing applicability and quantifying uncertainties.

    NASA Astrophysics Data System (ADS)

    Lougheed, Bryan; van der Lubbe, Jeroen; Davies, Gareth

    2016-04-01

    Accurate geochronologies are crucial for reconstructing the sensitivity of brackish and estuarine environments to rapidly changing past external impacts. A common geochronological method used for such studies is radiocarbon (14C) dating, but its application in brackish environments is severely limited by an inability to quantify spatiotemporal variations in 14C reservoir age, or R(t), due to dynamic interplay between river runoff and marine water. Additionally, old carbon effects and species-specific behavioural processes also influence 14C ages. Using the world's largest brackish water body (the estuarine Baltic Sea) as a test-bed, combined with a comprehensive approach that objectively excludes both old carbon and species-specific effects, we demonstrate that it is possible to use 87Sr/86Sr ratios to quantify R(t) in ubiquitous mollusc shell material, leading to almost one order of magnitude increase in Baltic Sea 14C geochronological precision over the current state-of-the-art. We propose that this novel proxy method can be developed for other brackish water bodies worldwide, thereby improving geochronological control in these climate sensitive, near-coastal environments.

  8. 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

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

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

  10. 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

  11. 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

  12. 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.

  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. 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

  15. 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

  16. 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.

  17. New 230Th/U and 14C ages from Lake Lahontan carbonates, Nevada, USA, and a discussion of the origin of initial thorium

    NASA Astrophysics Data System (ADS)

    Lin, J. C.; Broecker, W. S.; Anderson, R. F.; Hemming, S.; Rubenstone, J. L.; Bonani, G.

    1996-08-01

    Five sets of coeval lacustrine carbonate samples from Pleistocene Lake Lahontan in western Nevada were dated by both the AMS 14C and 230Th/U isochron methods. All five groups of samples were analyzed for U-Th isotopes by alpha spectrometry and one of the groups was additionally measured by thermal and secondary ionization mass spectrometry (TIMS and SIMS) for comparison. The 14C ages were corrected to calendar years using the calibration curve recommended by Bard et al. (1992) . Without local reservoir correction on the 14C ages, mean 230Th/U isochron ages of some sets are apparently older than their calendar-corrected 14C ages by up to 2300 years. Modern carbon contamination of these carbonate samples through recrystallization or deposition of secondary calcite is likely to be responsible for part of the age discrepancies. We explored additional biases associated with the isochron ages, maybe produced by the presence of initial Th coprecipitated from the lake water. It can be shown that if dissolved (hydrogenous) Th is directly incorporated into the pure carbonates, then the three-component mixing among (1) detrital Th, (2) hydrogenous Th adsorbed on detritus, and (3) hydrogenous Th incorporated by the carbonate can introduce a positive age bias. We have developed an approach to estimate the magnitude of this bias of the Lake Lahontan carbonates. The preliminary estimates suggest a positive age bias of 1000 to 2000 years for two sets of the samples.

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

    NASA Astrophysics Data System (ADS)

    Kirchner, James; Jasechko, Scott

    2016-04-01

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

  19. 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.

  20. 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.

  1. 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.

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

    USGS Publications Warehouse

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

    2010-01-01

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

  3. Spatial distribution and characterization of long-term aged 14C-labeled atrazine residues in soil.

    PubMed

    Jablonowski, Nicolai D; Koeppchen, Stephan; Hofmann, Diana; Schaeffer, Andreas; Burauel, Peter

    2008-10-22

    The long-term behavior of the herbicide atrazine and its metabolites in the environment is of continued interest in terms of risk assessment and soil quality monitoring. Aqueous desorption, detection, and quantification of atrazine and its metabolites from an agriculturally used soil were performed 22 years after the last atrazine application. A lysimeter soil containing long-term aged atrazine for >20 years was subdivided into 10 and 5 cm layers (at the lysimeter bottom: soil 0-50 and 50-55 cm; fine gravel 55-60 cm depth, implemented for drainage purposes) to identify the qualitative and quantitative differences of aged (14)C-labeled atrazine residues depending on the soil profile and chemico-physical conditions of the individual soil layers. Deionized water was used for nonexhaustive cold water shaking extraction of the soil. With increasing soil depth, the amount of previously applied (14)C activity decreased significantly from 8.8% to 0.7% at 55-60 cm depth whereas the percentage of desorbed (14)C residues in each soil layer increased from 2% to 6% of the total (14)C activity in the sample. The only metabolite detectable by means of LC-MS/MS was 2-hydroxyatrazine while most of the residual (14)C activity was bound to the soil and was not desorbed. The amount of desorbed 2-hydroxyatrazine decreased with increasing soil depth from 21% to 10% of the total desorbed (14)C residue fraction. The amount of (14)C residues in the soil layers correlated well with the carbon content in the soil and in the aqueous soil extracts ( p value = 0.99 and 0.97, respectively), which may provide evidence of the binding behavior of the aged atrazine residues on soil carbon. The lowest coarse layer (55-60 cm) showed increased residual (14)C activity leading to the assumption that most (14)C residues were leached from the soil column over time. PMID:18808141

  4. New {sup 230}Th/U and {sup 14}C ages from Lake Lahontan carbonates, Nevada, USA, and a discussion of the origin of initial thorium

    SciTech Connect

    Lin, J.C.; Broecker, W.S.; Anderson, R.F.

    1996-08-01

    Five sets of coeval lacustrine carbonate samples from Pleistocene Lake Lahontan in western Nevada were dated by both the AMS {sup 14}C and {sup 230}Th/U isochron methods. All five groups of samples were analyzed for U-Th isotopes by alpha spectrometry and one of the groups was additionally measured by thermal and secondary ionization mass spectrometry (TIMS and SIMS) for comparison. The {sup 14}C ages were corrected to calendar years using the calibration curve recommended by Bard et al. (1992). Without local reservoir correction on the {sup 14}C ages mean {sup 230}Th/U isochron ages of some sets are apparently older than their calendar-corrected {sup 14}C ages by up to 2300 years. Modern carbon contamination of these carbonate samples through recrystallization or deposition of secondary calcite is likely to be responsible for part of the age discrepancies. We explored additional biases associated with the isochron ages, maybe produced by the presence of initial Th coprecipitated from the lake water. It can be shown that if dissolved (hydrogenous) Th is directly incorporated into the pure carbonates, then the three-component mixing among (1) detrital Th, (2) hydrogenous Th adsorbed on detritus, and (3) hydrogenous Th incorporated by the carbonate can introduce a positive age bias. We have developed an approach to estimate the magnitude of this bias of the Lake Lahontan carbonates. The preliminary estimates suggest a positive age bias of 1000 to 2000 years for two sets of the samples. 49 refs., 10 figs., 9 tabs.

  5. Southwest Pacific Ocean surface reservoir ages since the last glaciation: Circulation insights from multiple-core studies

    NASA Astrophysics Data System (ADS)

    Sikes, Elisabeth L.; Guilderson, Thomas P.

    2016-02-01

    Radiocarbon (14C) in dissolved inorganic carbon in the ocean can trace the age of ocean water relative to the atmosphere and provide insight into climate-driven changes in ocean circulation since the last glaciation. Here we estimate surface radiocarbon ages from the last glaciation through the deglaciation into the Holocene in the southwestern Pacific by using tephras, both as stratigraphic tie points and for the availability of existing radiocarbon dates from terrestrial- based analyses of the organic carbon associated with them, as markers of past atmospheric Δ14C. The glacial surface reservoir age of subtropical waters was ~700 14C years older than the coeval atmosphere at ~25,000 cal yr B.P. This was significantly older (more 14C depleted) by ~ 300 14C years, than modern reservoir ages. At the same time, subantarctic surface water reservoir age was ~3200 14C years, almost 5 times the modern reservoir age, making the difference in age between subtropical and subantarctic surface water masses treble the modern difference. This pattern is attributed to the upwelling and exchange of very old deep waters from the glacial abyss in the Southern Ocean. In the early deglaciation, surface reservoir ages were ~600 to 700 14C years. Recent atmospheric Δ14C calibrations project that these surface reservoir ages were older than modern by 1.2-fold to 2-fold. This increased reservoir effect can be attributed to shallow circulation that differed from modern, delivering waters with lower 14C content to the region. Early Holocene surface reservoir ages of ~300 to 500 14C years, similar to recent, suggest modern circulation patterns were in place by that time.

  6. Discordant 14C ages from buried tidal-marsh soils in the Cascadia subduction zone, southern Oregon coast

    USGS Publications Warehouse

    Nelson, A.R.

    1992-01-01

    Peaty, tidal-marsh soils interbedded with estuarine mud in late Holocene stratigraphic sequences near Coos Bay, Oregon, may have been submerged and buried during great (M > 8) subduction earthquakes, smaller localized earthquakes, or by nontectonic processes. Radiocarbon dating might help distinguish among these alternatives by showing that soils at different sites were submerged at different times along this part of the Cascadia subduction zone. But comparison of conventional 14C ages for different materials from the same buried soils shows that they contain materials that differ in age by many hundreds of years. Errors in calibrated soil ages represent about the same length of time as recurrence times for submergence events (150-500 yr)-this similarity precludes using conventional 14C ages to distinguish buried soils along the southern Oregon coast. Accelerator mass spectrometer 14C ages of carefully selected macrofossils from the tops of peaty soils should provide more precise estimates of the times of submergence events. ?? 1992.

  7. Interspecies comparison of marine reservoir ages at the Kitakogane shell midden, Hokkaido, Japan

    NASA Astrophysics Data System (ADS)

    Yoneda, Minoru; Shibata, Yasuyuki; Morita, Masatoshi; Hirota, Masashi; Suzuki, Ryo; Uzawa, Kazuhiro; Ohshima, Naoyuki; Dodo, Yukio

    2004-08-01

    Apparent 14C ages of human and faunal remains from the Kitakogane shell midden assigned to the Early Jomon period were measured to estimate the reservoir effect on different species. In previous studies, northern fur seal and Japanese deer had showed significant age differences of 860 14C yr, in concordance with the large reservoir ages observed in pre-bomb shells from the western North Pacific. However, the present study suggests that other sedentary marine organisms, including porpoise, Japanese sea lion and scallop, show a smaller reservoir age-offset at 720 14C yr at the same site. The ethology of northern fur seal was probably responsible for this discrepancy because of a larger reservoir age in the Sea of Okhotsk into which they migrated. This suggests the reservoir effect on humans was more complicated than a simple linear mixing between marine and terrestrial reservoirs in the case of the NW Pacific coast. It was suggested that an interspecies comparison of 14C age-offsets could produce more precise estimation of the marine reservoir effect in the past.

  8. 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.

  9. 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.

  10. Bioaccessibility of environmentally aged 14C-atrazine residues in an agriculturally used soil and its particle-size aggregates.

    PubMed

    Jablonowski, Nicolai D; Modler, Janette; Schaeffer, Andreas; Burauel, Peter

    2008-08-15

    After 22 years of aging under natural conditions in an outdoor lysimeter the bioaccessibility of 14C-labeled atrazine soil residues to bacteria was tested. Entire soil samples as well as sand-sized, silt-sized, and clay-sized aggregates (>20, 20-2, and <2microm aggregate size, respectively) were investigated under slurried conditions. The mineralization of residual radioactivity in the outdoor lysimeter soil reached up to 4.5% of the total 14C-activity after 16 days, inoculated with Pseudomonas sp. strain ADP. The control samples without inoculated bacteria showed a mineralization maximum of only about 1% after 44 days of incubation. Mineralization increased in the clay-sized aggregates up to 6.2% of the total residual 14C-activity within 23 days. With decreasing soil aggregate sizes, residual 14C-activity increased per unit of weight, but only minor differences of the mineralization in the soil and soil size aggregates using mineral-media for incubation was observed. Using additional Na-citrate in the incubation, the extent of mineralization increased to 6.7% in soil after 23 days following incubation with Pseudomonas sp. strain ADP. These results show that long-term aged 14C-atrazine residues are still partly accessible to the atrazine degrading microorganism Pseudomonas sp. strain ADP. PMID:18767643

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

    NASA Astrophysics Data System (ADS)

    Kwicklis, Edward; Farnham, Irene

    2014-09-01

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

  12. Multidecadal variations in Southern Hemisphere atmospheric 14C: Evidence against a Southern Ocean sink at the end of the Little Ice Age CO2 anomaly

    NASA Astrophysics Data System (ADS)

    Turney, Chris S. M.; Palmer, Jonathan; Hogg, Alan; Fogwill, Christopher J.; Jones, Richard T.; Bronk Ramsey, Christopher; Fenwick, Pavla; Grierson, Pauline; Wilmshurst, Janet; O'Donnell, Alison; Thomas, Zoë A.; Lipson, Mathew

    2016-02-01

    Northern Hemisphere-wide cooling during the Little Ice Age (LIA; 1650-1775 Common Era, C.E.) was associated with a ~5 ppmv decrease in atmospheric carbon dioxide. Changes in terrestrial and ocean carbon reservoirs have been postulated as possible drivers of this relatively large shift in atmospheric CO2, potentially providing insights into the mechanisms and sensitivity of the global carbon cycle. Here we report decadally resolved radiocarbon (14C) levels in a network of tree-ring series spanning 1700-1950 C.E. located along the northern boundary of, and within, the Southern Ocean. We observe regional dilutions in atmospheric radiocarbon (relative to the Northern Hemisphere) associated with upwelling of 14CO2-depleted abyssal waters. We find the interhemispheric 14C offset approaches zero during increasing global atmospheric CO2 at the end of the LIA, with reduced ventilation in the Southern Ocean and a Northern Hemisphere source of old carbon (most probably originating from deep Arctic peat layers). The coincidence of the atmospheric CO2 increase and reduction in the interhemispheric 14C offset imply a common climate control. Possible mechanisms of synchronous change in the high latitudes of both hemispheres are discussed.

  13. 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.

  14. 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.

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed

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

    2015-01-01

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

  17. 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.

  18. 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.

  19. Ancient carbon from a melting glacier gives high 14C age in living pioneer invertebrates

    PubMed Central

    Hågvar, Sigmund; Ohlson, Mikael

    2013-01-01

    Glaciers are retreating and predatory invertebrates rapidly colonize deglaciated, barren ground. The paradox of establishing predators before plants and herbivores has been explained by wind-driven input of invertebrate prey. Here we present an alternative explanation and a novel glacier foreland food web by showing that pioneer predators eat locally produced midges containing 21,000 years old ancient carbon released by the melting glacier. Ancient carbon was assimilated by aquatic midge larvae, and terrestrial adults achieved a radiocarbon age of 1040 years. Terrestrial spiders, harvestmen and beetles feeding on adult midges had radiocarbon ages of 340–1100 years. Water beetles assumed to eat midge larvae reached radiocarbon ages of 1100–1200 years. Because both aquatic and terrestrial pioneer communities use ancient carbon, the term “primary succession” is questionable in glacier forelands. If our “old” invertebrates had been collected as subfossils and radiocarbon dated, their age would have been overestimated by up to 1100 years. PMID:24084623

  20. Probing organic matter transfer dynamics in river systems using lignin phenol 14C ages

    NASA Astrophysics Data System (ADS)

    Feng, X.; Vonk, J. E.; Gustafsson, O.; Galy, V.; Holmes, R. M.; Mann, P. J.; Montlucon, D.; Eglinton, T. I.

    2011-12-01

    As an important and ubiquitous component of terrestrial organic matter, lignin is widely dispersed by rivers during the land-ocean transfer. While the distribution and composition of lignin-derived phenols have been extensively investigated, little is known on their radiocarbon age, which carries information on the residence time and/or source of organic matter during fluvial transport. Recently, we have developed a high pressure liquid chromatography-based method of isolating individual lignin phenols for radiocarbon analysis. We employed compound-specific radiocarbon analysis to investigate the provenance and transport of lignin in sedimentary particles from several major river systems that span a range of latitudes spanning Arctic (Mackenzie, Kolyma, Indigirka, Lena, Yenisey, Ob, and Kalix), temperate (Columbia), to tropical regions (Congo and Ganges-Brahmaputra). The radiocarbon age of lignin phenols ranged from modern in the tropical (Congo and Ganges-Brahmaputra) rivers to approximately 4000 years in the Arctic (Kolyma and Indigirka). The latter, while clearly reflecting protracted storage of lignin within Arctic river drainage basins, is much younger than plant wax lipids isolated from the same sediments. This observation indicates that lignin is a relatively rapidly cycling component of the terrestrial organic matter transported by rivers. The general correlation between the radiocarbon age of lignin phenols and the latitude of rivers suggests climatic control over the preservation and storage of lignin within the river drainage basins. Individual lignin phenols were also isolated from the dissolved organic matter from several of these major rivers (including Congo, Fraser, Ganges-Brahmaputra, Mackenzie, and Yangtze, etc.) and compared their composition and radiocarbon age with those in the suspended particles collected from the same river system. Such comparison allows the assessment of lignin fractionation and degradation in the dissolved and particulate

  1. Episodic Neoglacial Cryosphere Expansion Reconstructed from 14C Ages of Ice-Entombed Plants on Svalbard

    NASA Astrophysics Data System (ADS)

    Miller, G. H.; Lehman, S.; Landvik, J. Y.

    2015-12-01

    The Northern Hemisphere cryosphere's response to the monotonic decline in summer insolation through the Holocene has been irregular expansion, interrupted by periods of retreat, culminating in the Little Ice Age, when most glaciers attained their maximum late Holocene dimensions. This non-linear response to near-linear forcing implies other factors modulate the radiative effects of the regular insolation decline. Understanding how the Earth system accomplishes this modulation is relevant to the development of reliable models for future climate change. Accurately dating the onset of persistent summer coolings across the Arctic is a first step toward developing this understanding. Here we report 52 precise radiocarbon dates on rooted plants emerging from beneath receding glaciers on Svalbard that define times when colder summers led to snowline depression and an expanded cryosphere. The earliest persistent depression of snowline documented by our dates occurred between 4.0 and 3.4 ka, but with little additional summer cooling until early in the first millennium AD. Episodes of subsequent summer cooling were centered on 240-340, 410-540 and 670-770 AD, followed by additional cooling between 1000 and 1230 AD, and between 1300 and 1470 AD. Cooling that occurred after 1470 AD, includes of the Little Ice Age when the Svalbard cryosphere reached its maximum Neoglacial dimensions. We suggest that in addition to insolation forcing, irregular reductions in the strength of the North Atlantic Current and expansions of Arctic Ocean sea ice were dominant factors that led to episodic snowline depression over Svalbard, but the extent to which these changes are linked to radiative forcing from volcanism or solar irradiance as opposed to unforced variability remains unclear. The widespread exposure of entombed plants dating from the first millennium AD suggests that Svalbard's average summer temperatures of the past century now exceed those of any century since at least 700 AD

  2. Stromatolite laminae (Lagoa Vermelha, Brasil) as archives for reservoir age changes

    NASA Astrophysics Data System (ADS)

    Bruggmann, Sylvie; Vasconcelos, Crisogono; Hajdas, Irka

    2016-04-01

    As laminated biogenic or abiogenic sedimentary structures [1], stromatolites record environmental changes along growth profiles, revealing possible changes in reservoir ages due to input of older carbon. A modern stromatolite sample was collected in Lagoa Vermelha (100 km east of Rio de Janeiro, Brasil) an area known for upwelling of South Atlantic Central Water (SACW). 34 samples from a transect cutting the lamination were collected with a hand-driller for standard geochemistry and 14C AMS analyses. Shells collected in 2015 were analysed for estimation of the present-day reservoir age. 14C ages of laminae and the reservoir age were used to apply the age-depth model to the stromatolite transect with the OxCal depositional model (Marine13 calibration curve; [2]). Small-scale changes in the composition of laminae report environmental changes, e.g. upwelling. The well-laminated middle part (laminated boundstone; ca. 4cm) of the stromatolite transect was found to have grown in a short time period of less than 100 years (1163-1210 14C y BP), with four excursions towards older 14C ages (ca. 1200 14C y BP). To detect possible changes of marine 14C, calendar years assuming a stable modern reservoir age were used to simulate atmospheric 14C ages with the southern hemisphere IntCal13 atmospheric calibration curve [3]. The offset between the measured and simulated 14C ages indicates a variability of the reservoir age between -99 and 268 14C y with highest reservoir correction found for the layers with indication of environmental changes (e.g. upwelling). Thus, this simulation confirms the occurrence of older carbon and points out the sensitivity of stromatolites for changing reservoir ages. [1] M.A. Semikhatov, C.D. Gebelein, P. Cloud, S.M. Awramik, W.C. Benmore (1979). Stromatolite morphogenesis - progress and problems. Canadian Journal of Earth Sciences, 19:992-1015. [2] P.J. Reimer, E. Bard, A. Bayliss, J. W. Beck, P. G. Blackwell, C. Bronk Ramsey, C. E. Buck, H. Cheng, R

  3. A large drop in atmospheric [sup 14]C/[sup 12]C and reduced melting in the younger dryas, documented with [sup 230]Th ages of corals

    SciTech Connect

    Edwards, R.L.; Beck, J.W. ); Burr, G.S.; Donahue, D.J. ); Chappell, J.M.A. ); Bloom, A.L. ); Druffel, E.R.M. ); Taylor, F.W. )

    1993-05-14

    Paired carbon-14 ([sup 14]C) and thorium-230 ([sup 230]Th) ages were determined on fossil corals from the Huon Peninsula, Papua New Guinea. The ages were used to calibrate part of the [sup 14]C time scale and to estimate rates of sea-level rise during the last deglaciation. An abrupt offset between the [sup 14]C and [sup 230]Th ages suggests that the atmospheric [sup 14]C/[sup 12]C ratio dropped by 15 percent during the latter part of and after the Younger Dryas (YD). This prominent drop coincides with greatly reduced rates of sea-level rise. Reduction of melting because of cooler conditions during the YD may have caused an increase in the rate of ocean ventilation, which caused the atmospheric [sup 14]C/[sup 12]C ratio to fall. The record of sea-level rise also shows that globally averaged rates of melting were relatively high at the beginning of the YD. Thus, these measurements satisfy one of the conditions required by the hypothesis that the diversion of meltwater from the Mississippi to the St. Lawrence River triggered the YD event. 41 refs., 5 figs., 1 tab.

  4. The AMS 14C dating of Iron Age rice chaff ceramic temper from Ban Non Wat, Thailand: First results and its interpretation

    NASA Astrophysics Data System (ADS)

    Higham, Charles F. W.; Kuzmin, Yaroslav V.; Burr, G. S.

    2010-04-01

    Pottery tempered with rice chaff from the early Iron Age cemetery of Ban Non Wat site, northeast Thailand, has been subjected to direct AMS 14C dating, using low temperature combustion with oxygen as originally developed by authors. The carbon yield (0.2-0.5%) testifies the suitability of this pottery for dating. However, not all the results are in agreement with expected archaeological ages and other 14C dates from the studied site and neighboring site of Noen U-Loke. This calls for a thorough analysis and interpretation of pottery temper dates from the region.

  5. Low reservoir ages for the surface ocean from mid-Holocene Florida corals

    USGS Publications Warehouse

    Druffel, E.R.M.; Robinson, L.F.; Griffin, S.; Halley, R.B.; Southon, J.R.; Adkins, J.F.

    2008-01-01

    The 14C reservoir age of the surface ocean was determined for two Holocene periods (4908-4955 and 3008-3066 calendar (cal) B.P.) using U/Th-dated corals from Biscayne National Park, Florida, United States. We found that the average reservoir ages for these two time periods (294 ?? 33 and 291 ?? 27 years, respectively) were lower than the average value between A.D. 1600 and 1900 (390 ?? 60 years) from corals. It appears that the surface ocean was closer to isotopic equilibrium with CO2 in the atmosphere during these two time periods than it was during recent times. Seasonal ??18O measurements from the younger coral are similar to modern values, suggesting that mixing with open ocean waters was indeed occurring during this coral's lifetime. Likely explanations for the lower reservoir age include increased stratification of the surface ocean or increased ??14C values of subsurface waters that mix into the surface. Our results imply that a more correct reservoir age correction for radiocarbon measurements of marine samples in this location from the time periods ???3040 and ???4930 cal years B.P. is ???292 ?? 30 years, less than the canonical value of 404 ?? 20 years. Copyright 2008 by the American Geophysical Union.

  6. 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

  7. Influence of alternating soil drying and wetting on the desorption and distribution of aged 14C-labeled pesticide residues in soil organic fractions

    NASA Astrophysics Data System (ADS)

    Jablonowski, N. D.; Mucha, M.; Thiele, B.; Hofmann, D.; Burauel, P.

    2012-04-01

    A laboratory experiment was conducted to evaluate the effect of alternating soil drying and wetting on the release of aged 14C-labeled pesticide residues and their distribution in soil organic fractions (humic acids, fulvic acids, and humin substances). The used soils (gleyic cambisol; Corg 1.2%, pH 7.2) were obtained from the upper soil layer of two individual outdoor lysimeter studies containing either environmentally long-term aged 14C residues of the herbicide ethidimuron (ETD; 0-10 cm depth; time of aging: 9 years) or methabenzthiazuron (MBT; 0-30 cm depth; time of aging: 17 years). Triplicate soil samples (10 g dry soil equivalents) were (A=dry/wet) previously dried (45° C) or (B=wet/wet) directly mixed with pure water (1+2, w:w), shaken (150 rpm, 1 h), and centrifuged (~2000 g). The resulting supernatant was removed, filtered (0.45 μm) and subjected to 14C activity analysis via liquid scintillation counter (LSC), dissolved organic carbon (DOC) analysis, and LC-MS-MS analysis. This extraction procedure was repeated 15 individual times, for both setups (A) and (B). To determine the distribution of the aged 14C labelled pesticide residues in the soil organic matter fractions, the soil samples were subject to humic and fulvic acids fractionations at cycles 0, 4, 10, and 15. The residual pesticide 14C activity associated with the humic, fulvic, and humin substances (organic fraction remaining in the soil) fractions was determined via LSC. The water-extracted residual 14C activity was significantly higher in the extracts of the dry/wet, compared to the wet/wet soil samples for both pesticides. The total extracted 14C activity in the dry/wet soil extracts accounted for 51.0% (ETD) and 15.4% (MBT) in contrast to 19.0% (ETD) and 4.7% (MBT) in the wet/wet extracts after 15 water extractions. LC-MS-MS analysis revealed the parent compound ETD 27.9 μg kg-1 soil (dry/wet) and 10.7 μg kg-1 soil (wet/wet), accounting for 3.45 and 1.35% of total parent compound

  8. Influence of alternating soil drying and wetting on the desorption and distribution of aged 14C-labeled pesticide residues in soil organic fractions

    NASA Astrophysics Data System (ADS)

    Jablonowski, N. D.; Mucha, M.; Thiele, B.; Hofmann, D.; Burauel, P.

    2012-04-01

    A laboratory experiment was conducted to evaluate the effect of alternating soil drying and wetting on the release of aged 14C-labeled pesticide residues and their distribution in soil organic fractions (humic acids, fulvic acids, and humin substances). The used soils (gleyic cambisol; Corg 1.2%, pH 7.2) were obtained from the upper soil layer of two individual outdoor lysimeter studies containing either environmentally long-term aged 14C residues of the herbicide ethidimuron (ETD; 0-10 cm depth; time of aging: 9 years) or methabenzthiazuron (MBT; 0-30 cm depth; time of aging: 17 years). Triplicate soil samples (10 g dry soil equivalents) were (A=dry/wet) previously dried (45° C) or (B=wet/wet) directly mixed with pure water (1+2, w:w), shaken (150 rpm, 1 h), and centrifuged (~2000 g). The resulting supernatant was removed, filtered (0.45 μm) and subjected to 14C activity analysis via liquid scintillation counter (LSC), dissolved organic carbon (DOC) analysis, and LC-MS-MS analysis. This extraction procedure was repeated 15 individual times, for both setups (A) and (B). To determine the distribution of the aged 14C labelled pesticide residues in the soil organic matter fractions, the soil samples were subject to humic and fulvic acids fractionations at cycles 0, 4, 10, and 15. The residual pesticide 14C activity associated with the humic, fulvic, and humin substances (organic fraction remaining in the soil) fractions was determined via LSC. The water-extracted residual 14C activity was significantly higher in the extracts of the dry/wet, compared to the wet/wet soil samples for both pesticides. The total extracted 14C activity in the dry/wet soil extracts accounted for 51.0% (ETD) and 15.4% (MBT) in contrast to 19.0% (ETD) and 4.7% (MBT) in the wet/wet extracts after 15 water extractions. LC-MS-MS analysis revealed the parent compound ETD 27.9 μg kg-1 soil (dry/wet) and 10.7 μg kg-1 soil (wet/wet), accounting for 3.45 and 1.35% of total parent compound

  9. Functional age as an indicator of reservoir senescence

    USGS Publications Warehouse

    Miranda, Leandro E.; Krogman, R. M.

    2015-01-01

    It has been conjectured that reservoirs differ in the rate at which they manifest senescence, but no attempt has been made to find an indicator of senescence that performs better than chronological age. We assembled an indicator of functional age by creating a multimetric scale consisting of 10 metrics descriptive of reservoir environments that were expected to change directionally with reservoir senescence. In a sample of 1,022 U.S. reservoirs, chronological age was not correlated with functional age. Functional age was directly related to percentage of cultivated land in the catchment and inversely related to reservoir depth. Moreover, aspects of reservoir fishing quality and fish population characteristics were related to functional age. A multimetric scale to indicate reservoir functional age presents the possibility for management intervention from multiple angles. If a reservoir is functionally aging at an accelerated rate, action may be taken to remedy the conditions contributing most to functional age. Intervention to reduce scores of selected metrics in the scale can potentially reduce the rate of senescence and increase the life expectancy of the reservoir. This leads to the intriguing implication that steps can be taken to reduce functional age and actually make the reservoir grow younger.

  10. 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.

  11. 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.

  12. "Groundwater ages" of the Lake Chad multi-layer aquifers system inferred from 14C and 36Cl data

    NASA Astrophysics Data System (ADS)

    Bouchez, Camille; Deschamps, Pierre; Goncalves, Julio; Hamelin, Bruno; Seidel, Jean-Luc; Doumnang, Jean-Claude

    2014-05-01

    Assessment of recharge, paleo-recharge and groundwater residence time of aquifer systems of the Sahel is pivotal for a sustainable management of this vulnerable resource. Due to its stratified aquifer system, the Lake Chad Basin (LCB) offers the opportunity to assess recharge processes over time and to link climate and hydrology in the Sahel. Located in north-central Africa at the fringe between the Sahel and the Sahara, the lake Chad basin (LCB) is an endorheic basin of 2,5.106 km2. With a monsoon climate, the majority of the rainfall occurs in the southern one third of the basin, the Chari/Logone River system transporting about 90% of the runoff generated within the drainage basin. A complex multi-layer aquifer system is located in the central part of the LCB. The Quaternary unconfined aquifer, covering 500 000 km2, is characterized by the occurrence of poorly understood piezometric depressions. Artesian groundwaters are found in the Plio-Pleistocene lacustrine and deltaic sedimentary aquifers (early Pliocene and Continental Terminal). The present-day lake is in hydraulic contact with the Quaternary Aquifer, but during past megalake phases, most of the Quaternary aquifer was submerged and may experience major recharge events. To identify active recharge area and assess groundwater dynamics, one hundred surface and groundwater samples of all layers have been collected over the southern part of the LCB. Major and trace elements have been analyzed. Measurements of 36Cl have been carried out at CEREGE, on the French 5 MV AMS National Facility ASTER and 14C activities have been analyzed for 17 samples on the French AMS ARTEMIS. Additionally, the stable isotopic composition was measured on the artesian aquifer samples. In the Quaternary aquifer, results show a large scatter with waters having very different isotopic and geochemical signature. In its southern part and in the vicinity of the surface waters, groundwaters are predominantly Ca-Mg-HCO3 type waters with very

  13. 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.

  14. Export of pre-aged, labile DOM from a central California coastal upwelling system: Insights from D/L amino acids and Δ14C signatures

    NASA Astrophysics Data System (ADS)

    Walker, B. D.; Shen, Y.; Benner, R. H.; Druffel, E. R. M.

    2014-12-01

    Coastal upwelling zones are among the most productive regions in the world and play a major role in global carbon and nitrogen cycles. Recent research suggests that a substantial fraction of newly fixed organic matter is exported offshore in the form of dissolved organic matter (DOM). However, to date only a few studies have examined DOM composition in the context of production and export from upwelling systems. The ultimate fate and geochemical impact of coastal DOM exported to offshore and mesopelagic ecosystems also remains largely unknown. Between 2007-2009 we conducted a high-resolution biogeochemical time series at the Granite Canyon Marine Pollution Studies Lab in part to evaluate the seasonal production and export of DOM from the Central CA coast. Our previous work demonstrated substantial, albeit disparate, seasonal production of dissolved organic carbon and nitrogen (DOC, DON) - with high DON (and low C:N ratios) produced during upwelling and high DOC produced during summer/fall water column stratification (Walker and McCarthy, 2012). Here we present new total dissolved D/L amino acid (TDAA) and UV-oxidizable DOC radiocarbon (Δ14C) data with the goal of determining the relative sources (heterotrophic vs. autotrophic), bioavailability, microbial processing and 14C-ages of C-rich vs. N-rich DOM exported from this upwelling system. Our results suggest that C-rich DOM produced during water column stratification carries a large microbial signature (i.e. high D/L AA ratios and non-protein AA abundance), whereas N-rich DOM produced during upwelling appears to be fresh, autotrophic DOM (i.e. lowest D/L AA ratios and highest TDAA abundance). DOM Δ14C signatures also did not approximate in situ dissolved inorganic carbon (DIC), and instead were far more negative and highly correlated to water mass density. Together our results indicate a previously unrecognized source of highly labile yet pre-aged DOM potentially impacting offshore and mesopelagic ecosystems.

  15. 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

  16. 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

  17. 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.

  18. The aging of America's reservoirs: In-reservoir and downstream physical changes and habitat implications

    USGS Publications Warehouse

    Juracek, Kyle E.

    2015-01-01

    Reservoirs are important for various purposes including flood control, water supply, power generation, and recreation. The aging of America's reservoirs and progressive loss of water storage capacity resulting from ongoing sedimentation, coupled with increasing societal needs, will cause the social, economic, environmental, and political importance of reservoirs to continually increase. The short- and medium-term (<50 years) environmental consequences of reservoir construction and operation are well known and include an altered flow regime, lost connectivity (longitudinal, floodplain), an altered sediment regime, substrate compositional change, and downstream channel degradation. In general, reservoir-related changes have had adverse consequences for the natural ecosystem. Longer term (>50 years) environmental changes as reservoirs enter “old” age are less understood. Additional research is needed to help guide the future management of aging reservoir systems and support the difficult decisions that will have to be made. Important research directions include assessment of climate change effects on aging and determination of ecosystem response to ongoing aging and various management actions that may be taken with the intent of minimizing or reversing the physical effects of aging.

  19. Validating Annual Growth Bands of Deep-Sea Black Corals and Calculating Ocean Reservoir Ages in the Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Roark, E. B.; Mohon, M. L.; Prouty, N.; Guillemette, R. N.; Fallon, S.; Ross, S. W.

    2015-12-01

    Deep-sea black corals (Leiopathes sp.) are long-lived (up to 4,000 yrs old), and grow in a tree-like fashion depositing growth rings in their skeleton. Scanning electron microscopy at 900x magnification was used to image thin sections and identify peaks in iodine intensity using energy dispersive x-ray spectroscopy in three specimens from the Gulf of Mexico. Age determination by counting visual growth bands and iodine peaks were compared to both radiocarbon and U/Th-derived ages. The first specimen (GOM-JSL04-4734-BC1) has an iodine peak count age of 695 ±70, and growth band age of 785 ± 80 which compare quite well to the radiocarbon age of 670 ±40 years and a U/Th age of 780 ±16 years. There was similar agreement between the radiocarbon ages (1399 ±30 and 670 ±35 years) and the iodine peak count ages (1240 ±125 and 715±70 years) for the remaining two specimens with growth rates ranging from 11 ±3 to 16 ±2 µm yr-1 for all 3 specimens. Using the independent (iodine derived) age models in conjunction with the radiocarbon data, a high resolution ocean reservoir age record was developed for the last 600 years. Reservoir ages varied from 120 to 550 14C years on decadal to centennial time scales. The modern reservoir age in the GOM is 235 ±11 14C years. The preferred explanation for the variability found in these reservoir ages is related to changes in the strength of the Yucatan Current. This novel approach combines the identification of growth bands captured in high-resolution SEM in combination with synchronous peaks in skeleton iodine composition and is the first to validate that both can be used as annual chronometers. Using the independent iodine age models in conjunction with the radiocarbon records, ocean reservoir age records can be developed for the last ~500 to 1000 years.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  1. Assessing sedimentation issues within aging of flood-control reservoirs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Flood control reservoirs designed and built by federal agencies have been extremely effective in reducing the ravages of floods nationwide. Yet some structures are being removed for a variety of reasons, while other structures are aging rapidly and require either rehabilitation or decommissioning. ...

  2. Independent 40Ar/39Ar and 14C age constraints on the last five glacial terminations from the aggradational successions of the Tiber River, Rome (Italy)

    NASA Astrophysics Data System (ADS)

    Marra, F.; Rohling, E. J.; Florindo, F.; Jicha, B.; Nomade, S.; Pereira, A.; Renne, P. R.

    2016-09-01

    We use 13 new 40Ar/39Ar and 4 new 14C datings of volcanic deposits and organic material found within near-coastal aggradational successions deposited by the Tiber River near Rome, Italy, to integrate a larger dataset previously achieved in order to offer independent age constraints to the sea-level fluctuations associated with Late Quaternary glacial cycles during the last 450 ka. Results are compared with the chronologically independently constrained Red Sea relative sea-level curve, and with the astronomically tuned deep-sea benthic δ18O record. We find good agreements for the timings of change, and in several cases for both the amplitudes and timings of change during glacial terminations T-1, T-2, T-3, and T-5. There is one striking exception, namely for glacial termination T-4 that led into interglacial Marine Isotope Stage (MIS) 9. T-4 in our results is dated a full 18 ka earlier than in the Red Sea and deep-sea benthic δ18O records (which are in good agreement with each other in spite of their independent chronological constraints). The observed discrepancy is beyond the scale of the combined age uncertainties. One possible explanation is that the documented aggradation represents an early phase, triggered by a smaller event in the sea-level record, but the thickness of the aggradational sediment sequence then suggests that the amplitude of this earlier sea-level rise is underestimated in the Red Sea and benthic δ18O records. Also, this would imply that the aggradational succession of the main T-4 deglaciation has not yet been located in the study region, which is hard to reconcile with our extensive fieldwork and borehole coverage, unless unlikely non-deposition or complete erosion. Resolving this discrepancy will improve understanding of the timing of deglaciations relative to the orbitally modulated insolation forcing of climate and will require further focused research, both into the nature and chronology of the Tiber sequences of this period, and into

  3. North Atlantic surface ocean radiocarbon reservoir age variation: links to rapid global climate change

    NASA Astrophysics Data System (ADS)

    Austin, W. E. N.; Brown, L.; Telford, R. J.; Ninnemann, U. S.; Wilson, L. J.; Bryant, C. L.

    2009-04-01

    High resolution palaeoclimate records show that the overall warming throughout the late glacial period to the present has been punctuated by repeated cooling events on decadal to centennial timescales. Reorganisation of the North Atlantic's deep water thermohaline circulation is often considered an important factor in triggering or controlling these abrupt climate change intervals. During the Younger Dryas (YD), the most significant of these late glacial climatic coolings, a large, positive anomaly in atmospheric radiocarbon concentration (Δ14Catm) is observed, which is not fully accounted for by changes in the production rate of 14C. Another potential source of Δ14Catm variation is the extent of carbon exchange between the atmosphere and other reservoirs, such as the deep ocean, and it has been suggested that the circulation changes which drove the YD cooling were also partially responsible for limiting air-sea CO2 exchange and hence increasing Δ14Catm. Reconstructions of North Atlantic surface ocean radiocarbon reservoir ages (Rt) during the Younger Dryas, based on known-age markers such as tephra horizons, demonstrate an increase in Rt from modern values of 400 y to >800 y, widely believed to be indicative of reduced carbon exchange between the atmosphere and the deep ocean. However, the limited temporal resolution of these measurements has thus far been insufficient to fully explore the connection between changing Rt and rapid, ocean circulation-induced climate change. Here we present a detailed reconstruction of changing Rt in the late glacial period, from a high resolution marine sediment record north of 50° N. Stable isotope records and radiocarbon chronologies from cores collected in the St Kilda Basin, Hebridean shelf, containing highly-expanded late glacial records, will be used to assess the importance and controlling mechanisms of reservoir age variation in the NE Atlantic.

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

    PubMed

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

    2011-04-15

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

  5. 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.

  6. 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.

  7. A reservoir landscape for age-0 largemouth bass

    USGS Publications Warehouse

    Irwin, E.R.; Jackson, J.R.; Noble, R.L.

    2002-01-01

    Landscape ecology is concerned with how ecological processes are affected by spatial patterns. Identification of heterogeneity in littoral zones has expanded the conceptual framework of aquatic landscapes. Long-term study of a reservoir largemouth bass population indicated that the amount and arrangement of habitat regulated the population processes. The distribution of age-0 largemouth bass was quantified in relation to littoral habitat and relations between landscape features and population parameters on scales from embayment to microhabitat were determined. At the embayment scale, shoreline slope and amount of gravel substratum predicted fivefold variability in abundance among four reservoir embayments. Within an embayment, these habitat features explained between 37 and 88 percent of variation in shoreline distribution of age-0 largemouth bass. At the microhabitat scale, age-0 largemouth bass exhibited patchy distributions in relation to gravel substratum at 40 percent of sites. These results indicate that the landscape scale domain for young largemouth bass is large; whereas, specific patterns explained processes across multiple scales. Distributions of age-0 largemouth bass in relation to habitat, however, were apparent on a fine scale (10 m) and these data, coupled with limited movement behavior of young largemouth bass, indicate that the ecological neighborhood of this life stage is small. Our data also suggested that some habitats may be source habitats because embayments with hypothesized higher source/sink ratios were more productive. Although patch arrangement critical to young largemouth bass ecology was not quantified, it was apparent that embayments with more complex habitats likely provided the extent of the landscape for age-0 largemouth bass in Jordan Lake. Identification of scale of patchiness (of fish distributions and habitats) for this life stage will assist in making inferences regarding complex ecological processes that can affect year

  8. Ramped pyrolysis 14C age spectra of riverine particulate organic matter through a record hydrograph - the Great Atchafalaya Flood of 2011

    NASA Astrophysics Data System (ADS)

    Rosenheim, B. E.; Roberts, B. J.; Williams, E. K.

    2014-12-01

    Episodic flood events can have major effects on biogeochemistry of estuary and deltaic systems. In 2011, the Great Flood event that transpired in the Missouri-Mississippi River watershed resulted in likely the highest discharge of water and sediments at the Atchafalaya outflow in several thousand years (since the last time the mainstem discharge flowed through this area). We sampled the event hydrograph starting near the peak and measuring through the falling leg of the flood event. Here we describe particulate organic carbon (POC) age spectra from these samples referenced to selected samples from a >60 month time series of samples from several sites along the Atchafalaya outlet and building submarine delta. Similar to past work on high-water events, age spectra become older during the flood event. However, this flood event did not return ages as old as previous events analyzed, suggesting a provenance control on age spectra. Age spectra showed relatively youngest ages during the return to baseline conditions immediately following the flood hydrograph and then returned to intermediate ages afterwards. Our response to the event missed the early rising limb of the event, when sediment transport was highest, however the peak and falling limb of the Atchafalaya hydrograph were well-represented in our time series. We hypothesize that during the initial pulse of sediment, age spectra may have been older, but subsequent discharge at near bank-full and over bank flow at some river reaches carried more recent POC than initial erosion of bank deposits during the rising limb of the flood. Still, the age spectra observed in an extreme event do not approach the breadth of the spectra observed in more erosive and steep mountainous river systems.

  9. Associated terrestrial and marine fossils in the late-glacial Presumpscot Formation, southern Maine, USA, and the marine reservoir effect on radiocarbon ages

    NASA Astrophysics Data System (ADS)

    Thompson, Woodrow B.; Griggs, Carol B.; Miller, Norton G.; Nelson, Robert E.; Weddle, Thomas K.; Kilian, Taylor M.

    2011-05-01

    Excavations in the late-glacial Presumpscot Formation at Portland, Maine, uncovered tree remains and other terrestrial organics associated with marine invertebrate shells in a landslide deposit. Buds of Populus balsamifera (balsam poplar) occurred with twigs of Picea glauca (white spruce) in the Presumpscot clay. Tree rings in Picea logs indicate that the trees all died during winter dormancy in the same year. Ring widths show patterns of variation indicating responses to environmental changes. Fossil mosses and insects represent a variety of species and wet to dry microsites. The late-glacial environment at the site was similar to that of today's Maine coast. Radiocarbon ages of 14 tree samples are 11,907 ± 31 to 11,650 ± 50 14C yr BP. Wiggle matching of dated tree-ring segments to radiocarbon calibration data sets dates the landslide occurrence at ca. 13,520 + 95/-20 cal yr BP. Ages of shells juxtaposed with the logs are 12,850 ± 65 14C yr BP ( Mytilus edulis) and 12,800 ± 55 14C yr BP ( Balanus sp.), indicating a marine reservoir age of about 1000 yr. Using this value to correct previously published radiocarbon ages reduces the discrepancy between the Maine deglaciation chronology and the varve-based chronology elsewhere in New England.

  10. A Reassessment of U-Th and 14C Ages for Late-Glacial High-Frequency Hydrological Events at Searles Lake, California

    USGS Publications Warehouse

    Lin, J.C.; Broecker, W.S.; Hemming, S.R.; Hajdas, I.; Anderson, Robert F.; Smith, G.I.; Kelley, M.; Bonani, G.

    1998-01-01

    U-Th isochron ages of tufas formed on shorelines suggest that the last pluvial event in Lake Lahontan and Searles Lake was synchronous at about 16,500 cal yr B.P. (equivalent to a radiocarbon age of between 14,000 and 13,500 yr B.P.), whereas the timing of this pluvial event determined by radiocarbon dating is on the order of 1000 yr younger. The timing of seven distinct periods of near desiccation in Searles Lake during late-glacial time has been reinvestigated for U-Th age determination by mass spectrometry. U-Th dating of evaporite layers in the interbedded mud and salt unit called the Lower Salt in Searles Lake was hampered by the uncertainty in assessing the initial 230Th/232Th of the samples. The resulting ages, corrected by a conservative range of initial 230Th/ 232Th ratios, suggest close correlation of the abrupt changes recorded in Greenland ice cores (Dansgaard-Oeschger events) and wet-dry conditions in Searles Lake between 35,000 and 24,000 Cal yr B.P. ?? 1998 University of Washington.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

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

    SciTech Connect

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

    2001-08-01

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

  13. 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

  14. Refining age estimates for three historic ground rupturing earthquakes in the Santa Cruz Mountains: 14C Wiggle-matching and Non-Native Pollen as age indicators (or not!)

    NASA Astrophysics Data System (ADS)

    Streig, A. R.; Weldon, R. J.; Dawson, T. E.; Guilderson, T.; Gavin, D. G.; Reidy, L.

    2013-12-01

    The Hazel Dell site provides the first definitive paleoseismic evidence of two pre-1906 19th century events on the Santa Cruz Mountains section based on the presence of anthropogenic artifacts. Hundreds of pieces of cut redwood chips were found in a stratigraphic horizon just below the ante-penultimate (E3) earthquake surface, suggesting that redwood trees at the site were cut down right before earthquake E3. We correlate our paleoseismic findings with the historic record and the onset of redwood logging in the area by determining the felling date of a buried redwood tree stump at the site and the age of the woodchips. We wiggle match 14 radiocarbon dates sampled from annual growth rings taken from the stump and the known interval between growth rings, with the intercepts of the INTCAL04 terrestrial 14C calibration curve. Pending 13C measurements, we find that the youngest ring we have identified in the tree is A.D. 1800. We also wiggle match 2 radiocarbon dates from inner and outer growth rings from two wood chips (with bark); their ages are consistent with the tree and the youngest woodchip ring is dated to 1813 A.D. There are no known ethnographic or historical accounts of pre-contact native people felling large trees in the way that European colonists did. The first record of European land use was for pasture in 1803. The property became a Spanish land grant in 1827, soon after which a whip-saw lumber mill is documented to have begun operation in the upper Corralitos area. We combine these paleoseismic results with historical earthquake accounts for the area and conclude that the San Andreas fault ruptured in 1838, 1890 and 1906. The Hazel Dell results are in contrast with findings from earlier paleoseismic studies in the Santa Cruz Mountains. The Grizzly Flat site, 6 km to the north, found evidence of 1906 and one 17th century earthquake. Two historic earthquakes were observed at the Mill Canyon site 8 km to the south and at the Arano Flat site 9.5 km south of

  15. 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

  16. Improving estimates of surface water radiocarbon reservoir ages in the northeastern Atlantic Ocean.

    NASA Astrophysics Data System (ADS)

    Greenop, Rosanna; Burke, Andrea; Rae, James; Austin, William; Reimer, Paula; Blaauw, Maarten; Crocker, Anya; Chalk, Thomas; Barker, Stephen; Knutz, Paul; Hall, Ian

    2016-04-01

    Radiocarbon measurements from foraminifera in marine sediment cores are widely used to constrain age models and the timing of paleoceanographic events, as well as past changes in ocean circulation and carbon cycling. However, the use of radiocarbon for both dating and palaeoceanographic applications is limited in sediment cores by a lack of knowledge about the surface ocean radiocarbon reservoir age and how it varies in both space and time. Typically, to convert a planktic radiocarbon age into a calendar age, an assumed constant reservoir age is applied. However, there is mounting evidence to suggest that this assumption of constant reservoir age through time is an oversimplification, particularly for the high latitude oceans during the cold climates of the last glacial and deglacial periods. Here we present new high-resolution radiocarbon records together with tephra tie points and 230-thorium (230Th) constrained sedimentation rates to improve estimates of radiocarbon reservoir age in the Northeast Atlantic Ocean. In addition we will explore the impact of the new reservoir ages for both the age models of the cores studied, as well as the palaeoceanographic implications of these reservoir age changes during intervals of rapid climate change over the past 40,000 years.

  17. Mediterranean Sea surface radiocarbon reservoir age changes since the last glacial maximum.

    PubMed

    Siani, G; Paterne, M; Michel, E; Sulpizio, R; Sbrana, A; Arnold, M; Haddad, G

    2001-11-30

    Sea surface reservoir ages must be known to establish a common chronological framework for marine, continental, and cryospheric paleoproxies, and are crucial for understanding ocean-continent climatic relationships and the paleoventilation of the ocean. Radiocarbon dates of planktonic foraminifera and tephra contemporaneously deposited over Mediterranean marine and terrestrial regions reveal that the reservoir ages were similar to the modern one (approximately 400 years) during most of the past 18,000 carbon-14 years. However, reservoir ages increased by a factor of 2 at the beginning of the last deglaciation. This is attributed to changes of the North Atlantic thermohaline circulation during the massive ice discharge event Heinrich 1. PMID:11729315

  18. Final Report: Drop Testing of Aged Stems on the SP981 Reservoir

    SciTech Connect

    White, M.B.

    1999-08-11

    Free fall drop testing of unloaded SP981 reservoirs was conducted by Savannah River Technology Center in the Materials Test Facility. The testing consisted of dropping eight aged and two unaged reservoirs on their stems at impact angles of 88 degrees and 70 degrees from heights of approximately 4 and 6 foot above a hardened steel surface.

  19. 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

  20. 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

  1. Upper Intermediate Water Reservoir Ages in the Northeastern Atlantic During the Past 11000 Years: New Evidence for Mid Holocene Freshening of the North Atlantic

    NASA Astrophysics Data System (ADS)

    Frank, N.; Paterne, M.; Blamart, D.; Colin, C.; Tisnerat-Laborde, N.; van Weering, T.; Henriet, J.

    2006-12-01

    Deep-water corals such as Lophelia pertusa and Madrepora occulata construct reef like structures along the slopes of Rockall Trough and within the Porcupine Seabight between 500 and 1000m depth, so called carbonate mounds. The hydrography is complex, with upper intermediate and surface water originating in the temperate North Atlantic and water masses from the sub-polar gyre and Labrador Sea circulating at depth within the Rockall Trough. Moreover, Norwegian Sea deep-water returns southward over the sill close to Rosemary Bank and move along the western slope of Rockall Bank. In addition, strong winter mixing of up to 1000m depth causes a significant contribution of surface water at depth and vise versa. Sediment coring on carbonate mounds and subsequent U series dating of coral skeletons has revealed up to 5m thick Holocene coral reef structures. Combined U series and 14C dating on those corals allows reconstructing upper intermediate water reservoir ages almost continuously for the entire Holocene. Here we present a compilation of 40 reservoir ages from western Rockall Bank and Porcupine Seabight that span from 400 years PB to ~11000 years BP representing water masses between 610 and 750m depth. Reservoir ages vary remarkably between as low as 150 years to up to 800 years throughout the Holocene. Variable reservoir ages are recorded at the beginning of the Holocene having mean values of about 450-500 years. The Mid-Holocene warm phase between 8500 and 6000 years BP revealed stunningly small and constant reservoir ages of about 200±150 years indicating extremely well ventilated upper intermediate waters. Than reservoir ages rise towards values as high as 700 years and drop down again to about 500 years at 4000 years BP. During the past 4000 years reservoir ages remain far more stable at 450- 500 years. Such changes in upper intermediate water ventilation agree with changes in Northern Hemisphere climate and oceanography recorded by other sedimentary proxies such

  2. 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.

  3. Age-related changes in reservoir and excess components of central aortic pressure in asymptomatic adults.

    PubMed

    Bia, Daniel; Cymberknop, Leandro; Zócalo, Yanina; Farro, Ignacio; Torrado, Juan; Farro, Federico; Pessana, Franco; Armentano, Ricardo L

    2011-01-01

    Study of humans aging has presented difficulties in separating the aging process from concomitant disease and/or in defining normality and abnormality during its development. In accordance with this, aging associates structural and functional changes evidenced in variations in vascular parameters witch suffer alterations during atherosclerosis and have been proposed as early markers of the disease. The absence of adequate tools to differentiate the expected (normal) vascular changes due to aging from those related with a vascular disease is not a minor issue. For an individual, an early diagnosis of a vascular disease should be as important as the diagnosis of a healthy vascular aging. Recent studies have proposed that the capacitive or reservoir function of the aorta and large elastic arteries plays a major role in determining the pulse wave morphology. The arterial pressure waveform can be explained in terms of a reservoir pressure, related to the arterial system compliance, and an "excess" or wave-related pressure, associated with the traveling waves. The aim of this study was to evaluate, by means of a mathematical approach, age-related changes in measured, reservoir and excess central aortic pressure in order to determine if age-related changes are concentrated in particular decades of life. Central aortic pressure waveform was non-invasively obtained in healthy subjects (age range: 20-69 years old). Age-related profiles in measured, reservoir and excess pressure were calculated. PMID:22255816

  4. 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

  5. Size of age-0 crappies (Pomoxis spp.) relative to reservoir habitats and water levels

    USGS Publications Warehouse

    Kaczka, Levi J.; Miranda, Leandro E.

    2014-01-01

    Variable year-class strength is common in crappie Pomoxis spp. populations in many reservoirs, yet the mechanisms behind this variability are poorly understood. Size-dependent mortality of age-0 fishes has long been recognized in the population ecology literature; however, investigations about the effects of environmental factors on age-0 crappie size are lacking. The objective of this study was to determine if differences existed in total length of age-0 crappies between embayment and floodplain habitats in reservoirs, while accounting for potential confounding effects of water level and crappie species. To this end, we examined size of age-0 crappies in four flood-control reservoirs in northwest Mississippi over 4years. Age-0 crappies inhabiting uplake floodplain habitats grew to a larger size than fish in downlake embayments, but this trend depended on species, length of time a reservoir was dewatered in the months preceding spawning, and reservoir water level in the months following spawning. The results from our study indicate that water-level management may focus not only on allowing access to quality nursery habitat, but that alternating water levels on a multiyear schedule could increase the quality of degraded littoral habitats.

  6. 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

  7. 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.

  8. Increased reservoir ages and poorly ventilated deep waters inferred in the glacial Eastern Equatorial Pacific

    PubMed Central

    de la Fuente, Maria; Skinner, Luke; Calvo, Eva; Pelejero, Carles; Cacho, Isabel

    2015-01-01

    Consistent evidence for a poorly ventilated deep Pacific Ocean that could have released its radiocarbon-depleted carbon stock to the atmosphere during the last deglaciation has long been sought. Such evidence remains lacking, in part due to a paucity of surface reservoir age reconstructions required for accurate deep-ocean ventilation age estimates. Here we combine new radiocarbon data from the Eastern Equatorial Pacific (EEP) with chronostratigraphic calendar age constraints to estimate shallow sub-surface reservoir age variability, and thus provide estimates of deep-ocean ventilation ages. Both shallow- and deep-water ventilation ages drop across the last deglaciation, consistent with similar reconstructions from the South Pacific and Southern Ocean. The observed regional fingerprint linking the Southern Ocean and the EEP is consistent with a dominant southern source for EEP thermocline waters and suggests relatively invariant ocean interior transport pathways but significantly reduced air–sea gas exchange in the glacial southern high latitudes. PMID:26137976

  9. Increased reservoir ages and poorly ventilated deep waters inferred in the glacial Eastern Equatorial Pacific

    NASA Astrophysics Data System (ADS)

    de La Fuente, Maria; Skinner, Luke; Calvo, Eva; Pelejero, Carles; Cacho, Isabel

    2015-07-01

    Consistent evidence for a poorly ventilated deep Pacific Ocean that could have released its radiocarbon-depleted carbon stock to the atmosphere during the last deglaciation has long been sought. Such evidence remains lacking, in part due to a paucity of surface reservoir age reconstructions required for accurate deep-ocean ventilation age estimates. Here we combine new radiocarbon data from the Eastern Equatorial Pacific (EEP) with chronostratigraphic calendar age constraints to estimate shallow sub-surface reservoir age variability, and thus provide estimates of deep-ocean ventilation ages. Both shallow- and deep-water ventilation ages drop across the last deglaciation, consistent with similar reconstructions from the South Pacific and Southern Ocean. The observed regional fingerprint linking the Southern Ocean and the EEP is consistent with a dominant southern source for EEP thermocline waters and suggests relatively invariant ocean interior transport pathways but significantly reduced air-sea gas exchange in the glacial southern high latitudes.

  10. Backwaters in the upper reaches of reservoirs produce high densities of age-0 crappies

    USGS Publications Warehouse

    Dagel, Jonah D.; Miranda, Leandro E.

    2012-01-01

    Reservoir backwaters are aquatic habitats in floodplains of reservoir tributaries that are permanently or periodically flooded by the reservoir. Like many reservoir arms, backwaters are commonly shallow, littoral habitats, but they differ from arms in various respects, including their support of primarily wetland plant assemblages that are tolerant to flooding. Elsewhere, the reservoir floods mainly upland plants that are less tolerant to flooding, producing a band of barren shoreline along the fluctuation zone. We investigated differences in relative abundance of age-0 crappies Pomoxis spp. in backwaters and arms of widely fluctuating flood control reservoirs, examined the effect of water level, and estimated the likelihood and timing with which these habitats are flooded annually. Higher catch rates of age-0 crappies were obtained in backwater habitats than in arm habitats. When inundated during the crappie spawning season, backwaters provided vegetated habitat at lower water levels than arms. Backwaters flooded earlier than arms and remained flooded longer to provide prolonged nursery habitat. Whereas vegetated habitat was inundated almost yearly in backwaters and arms, inundation that was timed to the onset of spawning occurred less regularly. Because of differences in water elevation, vegetated habitats were flooded in time for crappie spawning about every other year in backwaters but only every third year in arms. Recruitment of age-0 crappies was inversely correlated with high water levels during the months preceding the spawning period, perhaps because early flooding degraded the vegetation. Our results suggest that water levels may be managed during late winter and spring to regularly flood wetland vegetation communities in backwaters; however, water levels should be maintained at or below normal pool and should only irregularly flood upland vegetation in reservoir arms to promote the preservation of such vegetation. Furthermore, management efforts to

  11. Modern Tasman Sea surface reservoir ages from deep-sea black corals

    NASA Astrophysics Data System (ADS)

    Komugabe, Aimée F.; Fallon, Stewart J.; Thresher, Ronald E.; Eggins, Stephen M.

    2014-01-01

    Marine reservoir ages are a key element in calculating and constraining uncertainty in radiocarbon age estimates and are also essential to better understand regional ocean circulation. In this study, we present a new method to reconstruct long-term, high-resolution sea surface reservoir ages based on analysis of the organic skeleton of deep-sea (560 m) black coral (Anthozoa, Antipatharia). Our results confirm that antipatharians are extremely slow growing (typical radial growth rate for a South Pacific specimen around 0.03 mm/yr). Coupled uranium series and radiocarbon measurements were made on black coral collected live from the Norfolk Ridge (north Tasman Sea) to provide the first modern reservoir ages for this region. At the Norfolk Ridge, the average reservoir age between 1790 AD and 1900 AD was ∼330 years. This was followed by a steep decrease over time of about 70 years to 1950 AD (our most modern value). This indicates an increase in surface ocean ventilation of water masses in this region. These results are consistent with observational studies for the early twentieth century, which suggest significant changes in regional circulation of the southwest pacific.

  12. 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.

  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. 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

  15. Do predators influence the distribution of age-0 kokanee in a Colorado Reservoir?

    USGS Publications Warehouse

    Hardiman, J.M.; Johnson, B.M.; Martinez, P.J.

    2004-01-01

    Seasonal changes in reservoir conditions such as productivity, light, and temperature create spatiotemporal variation in habitat that may segregate or aggregate predators and prey, producing implications for the distribution, growth, and survival of fishes. We used hydroacoustics to document the diel vertical distribution of age-0 kokanee Oncorhynchus nerka relative to environmental gradients at Blue Mesa Reservoir, Colorado, during May-August of 2002. Temperature, light, and zooplankton density profiles were examined relative to foraging conditions for kokanee and their primary predator, lake trout Salvelinus namaycush. Age-0 kokanee displayed large diel vertical migrations in May despite the lack of an energetic advantage before reservoir stratification. Age-0 kokanee minimized near-surface foraging at this time, perhaps to avoid predation by visual predators, such as lake trout, in the well-lit surface waters. Strong reservoir stratification in midsummer appeared to provide a thermal refuge from lake trout that the kokanee exploited. By August vertical migrations were shallow and most kokanee remained in the epilimnion throughout the day. Although the energetic implications of the late-summer strategy are unclear, it appears that kokanee were responding to changes in their predator environment. A robust model for kokanee diel vertical migration across a range of systems should include a predator avoidance component.

  16. 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

  17. 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.

  18. Transit times and age distributions for reservoir models represented as nonlinear non-autonomuous systems

    NASA Astrophysics Data System (ADS)

    Müller, Markus; Meztler, Holger; Glatt, Anna; Sierra, Carlos

    2016-04-01

    We present theoretical methods to compute dynamic residence and transit time distributions for non-autonomous systems of pools governed by coupled nonlinear differential equations. Although transit time and age distributions have been used to describe reservoir models for a long time, a closer look to their assumptions reveals two major restrictions of generality in previous studies. First, the systems are assumed to be in equilibrium; and second, the equations under consideration are assumed to be linear. While both these assumptions greatly ease the computation and interpretation of transit time and age distributions they are not applicable to a wide range of problems. Moreover, the transfer of previous results learned from linear systems in steady state to the more complex nonlinear non-autonomous systems that do not even need to have equilibria, can be dangerously misleading. Fortunately the topic of time dependent age and transit time distributions has received some attention recently in hydrology, we aim to compute these distributions for systems of multiple reservoirs. We will discuss how storage selection functions can augment the information represented in an ODE system describing a system of reservoirs. We will present analytical and numerical algorithms and a Monte Carlo simulator to compute solutions for system transit time and age distributions for system-wide storage selection functions including the most simple, but important case of well mixed pools.

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

    SciTech Connect

    Guilderson, T; Cole, J; Southon, J

    2004-10-28

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

  20. Tracking Crystals Within Magma Reservoirs: U-series Crystal Ages and Diffusion

    NASA Astrophysics Data System (ADS)

    Cooper, K. M.

    2004-05-01

    U-series crystal ages can be used as tracers of crystal populations within a magma reservoir system, as well as providing information on the timescales of crystal and/or magma storage within reservoirs. 226Ra-230Th crystal ages in recent lavas from Mt St Helens (MSH), and Mt Shasta are several (2-5) ka. Similar ages were found by other workers for lavas from Tonga and the Lesser Antilles (Turner et al., 2003, EPSL 214 p. 279). However, Ra-Th and Th-U ages in seven of these thirteen samples are discordant, with Th-U ages of tens of ka. This pattern likely indicates progressive and/or episodic crystal growth where the Th-U ages more closely represent average ages while Ra-Th ages are weighted toward recent crystallization. This in turn suggests that crystals in arc lavas may in general reside within the crust for tens of ka, whereas the liquids may be much more transient features of the reservoir system. Diffusive equilibration of trace elements within zoned crystals and between crystals and liquids is a function of the duration of crystal residence at high temperatures. Therefore, the combination of crystal ages and trace element zoning patterns can potentially provide information about the temperature conditions of storage of these crystals. In addition, although Th-U diffusion in pyroxene and plagioclase is slow enough that ages will be robust at magmatic temperatures, Ra diffusion at high temperature could potentially modify Ra-Th ages. Ra-Th apparent ages could be either younger or older than the crystallization ages, considering that a chemical potential could be produced by introduction of crystals into an unrelated magma and also by in-situ decay. Measurement of Ba zoning in the same crystals can provide a test of the extent of Ra diffusion, thus making it possible to distinguish diffusive effects from aging. For the MSH samples (with one exception), preservation of Ba disequilibrium within individual crystals indicates that diffusion cannot have modified the

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  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. Aging Reservoirs in a Changing Climate: Examining Storage Loss of Large Reservoirs and Variability of Sedimentation Rate in a Dominant Cropland Region

    NASA Astrophysics Data System (ADS)

    Rahmani, V.; Kastens, J.; deNoyelles, F.; Huggins, D.; Martinko, E.

    2015-12-01

    Dam construction has multiple environmental and hydrological consequences including impacts on upstream and downstream ecosystems, water chemistry, and streamflow. Behind the dam the reservoir can trap sediment from the stream and fill over time. With increasing population and drinking and irrigation water demands, particularly in the areas that have highly variable weather and extended drought periods such as the United States Great Plains, reservoir sedimentation escalates water management concerns. Under nearly all projected climate change scenarios we expect that reservoir water storage and management will come under intense scrutiny because of the extensive use of interstate river compacts in the Great Plains. In the state of Kansas, located in the Great Plains, bathymetric surveys have been completed during the last decade for many major lakes by the Kansas Biological Survey, Kansas Water Office, and the U.S. Army Corps of Engineers. In this paper, we studied the spatial and temporal changes of reservoir characteristics including sedimentation yield, depletion rate, and storage capacity loss for 24 federally-operated reservoirs in Kansas. These reservoirs have an average age of about 50 years and collectively have lost approximately 15% of their original capacity, with the highest annual observed single-reservoir depletion rate of 0.84% and sedimentation yield of 1,685 m3 km-2 yr-1.

  4. 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

  5. 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

  6. Investigating the influence of regional climate and oceanography on marine radiocarbon reservoir ages in southwest New Zealand

    NASA Astrophysics Data System (ADS)

    Hinojosa, Jessica L.; Moy, Christopher M.; Prior, Christine A.; Eglinton, Timothy I.; McIntyre, Cameron P.; Stirling, Claudine H.; Wilson, Gary S.

    2015-12-01

    The New Zealand fjords are located at a latitude where distinct oceanic and atmospheric fronts separate carbon reservoirs of varying residence time. The marine radiocarbon reservoir age in this region is likely to deviate from the global average reservoir age over space and time as frontal boundaries migrate north and south. Here we present new estimates of modern radiocarbon reservoir age using the radiocarbon content of bivalve shells collected live before 1950. Multiple measurements from hydrographically distinct sites support the use of a ΔR, defined as the regional offset between measured and modeled marine radiocarbon reservoir age, of 59 ± 35 years for the New Zealand fjords. We also assess the radiocarbon content of bulk surface sediments throughout the fjord region. Sediment with a higher proportion of marine organic carbon has relatively less radiocarbon than more terrestrial sediment, suggesting a short residence time of organic carbon on land before deposition in the fjords. Additionally, we constrain reservoir age variability throughout the Holocene using coeval terrestrial and marine macrofossils. Although our modern results suggest spatial consistency in ΔR throughout the fjords, large deviations from the global average marine radiocarbon reservoir age exist in the paleo record. We find four ancient ΔR values, extending back to ˜10.2 cal kyr BP, to be negative or near zero. A likely cause of younger radiocarbon reservoir ages at select intervals throughout the Holocene is the increased influence of the Southern Hemisphere westerly winds, which cause extreme precipitation in the region that delivers terrestrial carbon, enriched in radiocarbon, to fjord basins. However, bivalve depth habitat may also influence radiocarbon content due to a stratified water column containing distinct carbon pools. This work highlights the need for thorough assessment of local radiocarbon cycling in similar regions of dynamic ocean/atmosphere frontal zones

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

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

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

  8. 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).

  9. 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.

  10. 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) §...

  11. 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) §...

  12. 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) §...

  13. 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) §...

  14. 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) §...

  15. 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) §...

  16. 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) §...

  17. 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) §...

  18. 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) §...

  19. INTEGRATED OUTCROP AND SUBSURFACE STUDIES OF THE INTERWELL ENVIRONMENT OF CARBONATE RESERVOIRS: CLEAR FORK (LEONARDIAN-AGE) RESERVOIRS, WEST TEXAS AND NEW MEXICO

    SciTech Connect

    F. Jerry Lucia

    2002-01-31

    This is the final report of the project ''Integrated Outcrop and Subsurface Studies of the Interwell Environment of Carbonate Reservoirs: Clear Fork (Leonardian-Age) Reservoirs, West Texas and New Mexico'', Department of Energy contract no. DE-AC26-98BC15105 and is the third in a series of similar projects funded jointly by the U.S. Department of Energy and The University of Texas at Austin, Bureau of Economic Geology, Reservoir Characterization Research Laboratory for Carbonates. All three projects focus on the integration of outcrop and subsurface data for the purpose of developing improved methods for modeling petrophysical properties in the interwell environment. The first project, funded by contract no. DE-AC22-89BC14470, was a study of San Andres outcrops in the Algerita Escarpment, Guadalupe Mountains, Texas and New Mexico, and the Seminole San Andres reservoir, Permian Basin. This study established the basic concepts for constructing a reservoir model using sequence-stratigraphic principles and rock-fabric, petrophysical relationships. The second project, funded by contract no. DE-AC22-93BC14895, was a study of Grayburg outcrops in the Brokeoff Mountains, New Mexico, and the South Cowden Grayburg reservoir, Permian Basin. This study developed a sequence-stratigraphic succession for the Grayburg and improved methods for locating remaining hydrocarbons in carbonate ramp reservoirs. The current study is of the Clear Fork Group in Apache Canyon, Sierra Diablo Mountains, West Texas, and the South Wasson Clear Fork reservoir, Permian Basin. The focus was on scales of heterogeneity, imaging high- and low-permeability layers, and the impact of fractures on reservoir performance. In this study (1) the Clear Fork cycle stratigraphy is defined, (2) important scales of petrophysical variability are confirmed, (3) a unique rock-fabric, petrophysical relationship is defined, (4) a porosity method for correlating high-frequency cycles and defining rock-fabric flow layers

  20. ( 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.

  1. 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

  2. Age structure and mortality of walleyes in Kansas reservoirs: Use of mortality caps to establish realistic management objectives

    USGS Publications Warehouse

    Quist, M.C.; Stephen, J.L.; Guy, C.S.; Schultz, R.D.

    2004-01-01

    Age structure, total annual mortality, and mortality caps (maximum mortality thresholds established by managers) were investigated for walleye Sander vitreus (formerly Stizostedion vitreum) populations sampled from eight Kansas reservoirs during 1991-1999. We assessed age structure by examining the relative frequency of different ages in the population; total annual mortality of age-2 and older walleyes was estimated by use of a weighted catch curve. To evaluate the utility of mortality caps, we modeled threshold values of mortality by varying growth rates and management objectives. Estimated mortality thresholds were then compared with observed growth and mortality rates. The maximum age of walleyes varied from 5 to 11 years across reservoirs. Age structure was dominated (???72%) by walleyes age 3 and younger in all reservoirs, corresponding to ages that were not yet vulnerable to harvest. Total annual mortality rates varied from 40.7% to 59.5% across reservoirs and averaged 51.1% overall (SE = 2.3). Analysis of mortality caps indicated that a management objective of 500 mm for the mean length of walleyes harvested by anglers was realistic for all reservoirs with a 457-mm minimum length limit but not for those with a 381-mm minimum length limit. For a 500-mm mean length objective to be realized for reservoirs with a 381-mm length limit, managers must either reduce mortality rates (e.g., through restrictive harvest regulations) or increase growth of walleyes. When the assumed objective was to maintain the mean length of harvested walleyes at current levels, the observed annual mortality rates were below the mortality cap for all reservoirs except one. Mortality caps also provided insight on management objectives expressed in terms of proportional stock density (PSD). Results indicated that a PSD objective of 20-40 was realistic for most reservoirs. This study provides important walleye mortality information that can be used for monitoring or for inclusion into

  3. 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.

  4. 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.

  5. 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....

  6. Sequestration of atmospheric CO2 in a weathering-derived, serpentinite-hosted magnesite deposit: 14C tracing of carbon sources and age constraints for a refined genetic model

    NASA Astrophysics Data System (ADS)

    Oskierski, H. C.; Dlugogorski, B. Z.; Jacobsen, G.

    2013-12-01

    geochemical signatures indicate that weathering is the integral magnesite mineralisation process at Attunga. Conventional radiocarbon ages of about 50 ka represent a maximum age constraint for the formation of the magnesite deposit during Quaternary weathering. A significant amount of atmospheric CO2 has been sequestered via the biosphere and carbonation of serpentinite at Attunga.

  7. Age at Virologic Control Influences Peripheral Blood HIV Reservoir Size and Serostatus in Perinatally-Infected Adolescents

    PubMed Central

    Persaud, Deborah; Patel, Kunjal; Karalius, Brad; Rainwater-Lovett, Kaitlin; Ziemniak, Carrie; Ellis, Angela; Chen, Ya Hui; Richman, Douglas; Siberry, George K.; Van Dyke, Russell B.; Burchett, Sandra; Seage, George R.; Luzuriaga, Katherine

    2014-01-01

    Importance Combination antiretroviral therapy (cART) initiated within several weeks of HIV infection in adults limits proviral reservoirs that preclude HIV cure. Biomarkers of restricted proviral reservoirs may aid in the monitoring of HIV remission or cure. Objectives To quantify peripheral blood proviral reservoir size in perinatally HIV-infected adolescents and to identify correlates of limited proviral reservoirs. Design, Setting, and Participants A cross-sectional study including 144 perinatally HIV-infected (PHIV+) youth (median age: 14.3 years), enrolled in the US-based Pediatric HIV/AIDS Cohort Study, on durable (median: 10.2 years) cART, stratified by age at virologic control. Main Outcome and Measures The primary endpoint was peripheral blood mononuclear cell (PBMC) proviral load following virologic control at different ages. Correlations between proviral load and markers of active HIV production (HIV-specific antibodies, 2-long terminal repeat (2-LTR) circles), and markers of immune activation and inflammation were also assessed. Results Proviral reservoir size was markedly reduced in the PHIV+ youth who achieved virologic control by age 1 year (4.2 [interquartile range, 2.6-8 6] copies per 1 million PBMCs) compared to those who achieved virologic control between 1-5 years of age (19.4 [interquartile range, 5.5-99.8] copies per 1 million PBMCs) or after age 5 years (−(70.7 [interquartile range, 23.2-209.4] copies per 1 million PBMCs; P < .00l). A proviral burden <10 copies/million PBMCs was measured in 11 (79%), 20 (40%), and 13 (18%) participants with virologic control at ages <1 year, 1-5 years, and >5 years, respectively (p<0.001). Lower proviral load was associated with undetectable 2-LTR circles (p<0.001) and HIV negative or indeterminate serostatus (p<0.001), but not with concentrations of soluble immune activation markers CD14 and CD163. Conclusions and Relevance Early effective cART along with prolonged virologic suppression after perinatal HIV

  8. 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.

  9. 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.

  10. 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

  11. 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....

  12. 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....

  13. 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....

  14. 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.

  15. 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

  16. Constraints on the Origin of Sedimentary Organic Carbon in the Beaufort Sea from Coupled Molecular 13C and 14C Measurements

    NASA Astrophysics Data System (ADS)

    Drenzek, N.; Montlucon, D.; Yunker, M.; MacDonald, R.; Eglinton, T.

    2005-12-01

    The type and flux of organic carbon (OC) delivered from the continents to the sea can both influence, and be influenced by, climate change on regional and global scales. In order to develop a more complete view of OC delivery in the climatically sensitive Arctic region, we measured the stable carbon and radiocarbon isotopic signatures of individual lipid biomarkers and products of kerogen pyrolysis from the surficial sediments of several sites on the Mackenzie Shelf and adjacent slope of the Beaufort Sea. Even carbon numbered fatty acids exhibit a trend of increasing radiocarbon age with increasing chain length, from modern values for shorter homologues (nC18 or below) to several thousand years old for their longer counterparts (nC24 or greater). Such depleted Δ14C values for longer-chain fatty acids likely reflect supply of vascular plant OC that has been `pre-' on the continents for several millennia prior to delivery to the Beaufort Sea. Their concomitant stable carbon isotopic compositions support a C3 land plant source. The molecular distributions and corresponding δ13C and Δ14C signatures of solvent-extractable alkanes point to at least two sources: higher plant leaf waxes and a 14C-`dead' component likely derived from erosion of organic-rich sedimentary rocks exposed within the Mackenzie River drainage basin. The stable carbon and radiocarbon compositions of straight chain n-hydrocarbon pyrolysis products from the corresponding demineralized sediments suggest their vascular plant-derived precursor structures also spent several millennia in continental reservoirs before being delivered to the Beaufort Sea. On a bulk level, the trend in sedimentary organic carbon contents, C/N ratios, and δ13C values point to an overall decrease in the terrigenous input (mainly from the Mackenzie river) with distance offshore, whereas bulk Δ14C measurements exhibit no trend suggesting a somewhat constant pre-aged component. A dual molecular isotopic mass balance approach

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  18. 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

  19. Effects of aging on left atrial reservoir, conduit, and booster pump function: a multi-institution acoustic quantification study

    PubMed Central

    Spencer, K; Mor-Avi, V; Gorcsan, J; DeMaria, A; Kimball, T; Monaghan, M; Perez, J; Weinert, L; Bednarz, J; Edelman, K; Kwan, O; Glascock, B; Hancock, J; Baumann, C; Lang, R

    2001-01-01

    OBJECTIVE—To assess the feasibility of measuring left atrial (LA) function with acoustic quantification (AQ) and then assess the effects of age and sex on LA reservoir, conduit, and booster pump function.
PATIENTS AND SETTING—165 subjects without cardiovascular disease, 3-79 years old, were enrolled by six tertiary hospital centres.
INTERVENTIONS—Continuous LA AQ area data were acquired and signal averaged to form composite waveforms which were analysed off-line.
MAIN OUTCOME MEASURES—Parameters of LA performance according to age and sex.
RESULTS—Signal averaged LA waveforms were sufficiently stable and detailed to allow automated analysis in all cases. An age related increase in LA area was noted. LA reservoir function did not vary with age or sex. All parameters of LA passive and active emptying revealed a significant age dependency. Overall, the passive emptying phase accounted for 66% of total LA emptying ranging from 76% in the youngest to 44% in the oldest decade. LA contraction accounted for 34% of atrial emptying in all subjects combined with the older subjects being more dependent on atrial booster pump function. When adjusted for atrial size, there were no sex related differences in LA function.
CONCLUSIONS—LA reservoir, conduit, and booster pump function can be assessed with automated analysis of signal averaged LA area waveforms. As LA performance varies with age, establishment of normal values should enhance the evaluation of pathologic states in which LA function is important.


Keywords: aging; atrium; echocardiography PMID:11179264

  20. Age and condition of juvenile catostomids in Clear Lake Reservoir, California

    USGS Publications Warehouse

    Burdick, Summer M.; Rasmussen, Josh

    2013-01-01

    Although infrequent recruitment of new individuals into the adult spawning populations of Lost River suckers (Deltistes luxatus) and shortnose suckers (Chasmistes brevirostris) limits recovery of these species in Upper Klamath Lake, it is not clear that populations are recruitment limited in Clear Lake Reservoir (hereafter Clear Lake). Specifically, some evidence indicates that shortnose suckers may regularly recruit to the adult spawning population in Clear Lake. Therefore, a study of early life history patterns and recruitment dynamics in Clear Lake may lead to a better understanding of what is limiting recovery of suckers in both lakes. Adult suckers in Clear Lake migrate up Willow Creek and its tributaries to spawn in some years, but low flow in Willow Creek may inhibit spawning migrations in other years. It is unclear whether spawning is successful, larvae survive, or how frequently juveniles persist to adulthood. Environmental variables associated with successful spawning or young-of-year survival have not been identified, and early life history for these populations is poorly understood. The U.S. Geological Survey, in cooperation with the U.S. Fish and Wildlife Service, initiated a study in 2011 to better understand juvenile sucker life history in Clear Lake, and to identify constraints in the early life history that may limit recruitment to the adult spawning populations. The relative weights of shortnose suckers from Clear Lake and Upper Klamath Lake were compared to examine differences in condition. However, it is unclear whether the disparity in relative weights between the populations reflects differences in condition, phenotype, or both. Approximately 80 percent of juvenile suckers in Clear Lake are shortnose suckers with some morphologic features similar to Klamath largescale suckers (Catostomus snyderi), whereas juvenile suckers in Upper Klamath Lake can be clearly classified as either shortnose or Lost River suckers. The presence of juvenile suckers

  1. Groundwater age, life expectancy and transit time distributions in advective dispersive systems; 2. Reservoir theory for sub-drainage basins

    NASA Astrophysics Data System (ADS)

    Cornaton, F.; Perrochet, P.

    2006-09-01

    Groundwater age and life expectancy probability density functions (pdf) have been defined, and solved in a general three-dimensional context by means of forward and backward advection-dispersion equations [Cornaton F, Perrochet P. Groundwater age, life expectancy and transit time distributions in advective-dispersive systems; 1. Generalized reservoir theory. Adv Water Res (xxxx)]. The discharge and recharge zones transit time pdfs were then derived by applying the reservoir theory (RT) to the global system, thus considering as ensemble the union of all inlet boundaries on one hand, and the union of all outlet boundaries on the other hand. The main advantages in using the RT to calculate the transit time pdf is that the outlet boundary geometry does not represent a computational limiting factor (e.g. outlets of small sizes), since the methodology is based on the integration over the entire domain of each age, or life expectancy, occurrence. In the present paper, we extend the applicability of the RT to sub-drainage basins of groundwater reservoirs by treating the reservoir flow systems as compartments which transfer the water fluxes to a particular discharge zone, and inside which mixing and dispersion processes can take place. Drainage basins are defined by the field of probability of exit at outlet. In this way, we make the RT applicable to each sub-drainage system of an aquifer of arbitrary complexity and configuration. The case of the well-head protection problem is taken as illustrative example, and sensitivity analysis of the effect of pore velocity variations on the simulated ages is carried out.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  3. Depositional features and source and reservoir rocks of Tertiary age in northern part of South China Sea

    SciTech Connect

    Wang, S.

    1986-07-01

    The northern part of the South China Sea covers an area of about 400,000 km/sup 2/. Tertiary deposits more than 10,000 m in thickness are widely distributed there. The area has sedimentary rocks more than 1000 m thick covers more than 300,000 km/sup 2/. Five sedimentary basins have been established in this area: Beibu Bay, Yinggehai, Southeastern Qiong, Pearl River Mouth, and Southwestern Taiwann basins. The primary source and reservoir rocks for oil and gas prospects are of Tertiary age. Tertiary rocks underwent three stages of development, each forming a specific sedimentation system: (1) a system of fluviolacustrine deposits in rift depressions from the Paleocene to early Oligocene; (2) a system of semiclosed-sea deposits from the late Oligocene to early Miocene; and (3) a system of deltaic open-sea deposits from the middle Miocene to Pliocene. These three sedimentation systems resulted in three suites of source rocks, three suites of reservoir rocks, and three groups of independent oil pools, complete with source, reservoir, and cap rocks. The three suites of source rocks are as follows: (1) the Eocene Liushagang Formation in the Beibu Bay basin, which is believed to be the best source rock discovered in the area; (2) the Oligocene Zhuhai Formation in the Pearl River Mouth basin; and (3) the lower Miocene series in the Pearl River Mouth basin. The Eocene formation is probably the principal source rock of regional scale in the northern part of the South China Sea. The three suites of reservoir rocks are as follows: (1) the fluviolacustrine sandstone bodies in the Liushagang Formation; (2) the fluviolacustrine sand bodies and shallow-sea sandstone bodies in the Zhuhai Formation and Lingshu Formation; (3) the deltaic, littoral, and shallow-sea sand bodies and bioherms of Neogene age, with the middle Miocene sandstone reservoirs having the best physical properties.

  4. Marine radiocarbon reservoir corrections (∆R) for Chesapeake Bay and the Middle Atlantic Coast of North America

    NASA Astrophysics Data System (ADS)

    Rick, Torben C.; Henkes, Gregory A.; Lowery, Darrin L.; Colman, Steven M.; Culleton, Brendan J.

    2012-01-01

    Radiocarbon dates from known age, pre-bomb eastern oyster (Crassostrea virginica) shells provide local marine reservoir corrections (∆R) for Chesapeake Bay and the Middle Atlantic coastal area of eastern North America. These data suggest subregional variability in ∆R, ranging from 148 ± 46 14C yr on the Potomac River to - 109 ± 38 14C yr at Swan Point, Maryland. The ∆R weighted mean for the Chesapeake's Western Shore (129 ± 22 14C yr) is substantially higher than the Eastern Shore (- 88 ± 23 14C yr), with outer Atlantic Coast samples falling between these values (106 ± 46 and 2 ± 46 14C yr). These differences may result from a combination of factors, including 14C-depleted freshwater that enters the bay from some if its drainages, 14C-depleted seawater that enters the bay at its mouth, and/or biological carbon recycling. We advocate using different subregional ∆R corrections when calibrating 14C dates on aquatic specimens from the Chesapeake Bay and coastal Middle Atlantic region of North America.

  5. 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

  6. 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

  7. 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%.

  8. Seasonal gonadal development and age-related maturity patterns of introduced pumpkinseed (Lepomis gibbosus Linnaeus, 1758) in a heated thermal reservoir and an adjacent river reach.

    PubMed

    Valente, E; Masson, G; Maul, A; Fox, M G; Meyer, A; Pihan, J C

    2016-05-01

    Testis and ovarian maturation status, maturity profile and gonado-somatic index (GSI) were assessed in pumpkinseed (Lepomis gibbosus) collected from Mirgenbach, a cooling-water reservoir associated with a nuclear power plant, and from the River Moselle 7km downstream of the reservoir's thermal outflow. Histological investigation indicated that in both sexes, gonadal development of pumpkinseed in the heated reservoir was more advanced than in the cooler Moselle River throughout the breeding season. The histological maturity profile of reservoir males ranked by the advancement of sperm cells was highly correlated with its GSI (rs=0.73, P<0.001). GSI of females in the reservoir increased with the stage at maturity, but GSI was not significantly correlated with total length, age or growth rate of the individual. All sampled individuals of both sexes were mature at age 1 in the heated reservoir, whereas 48% of age 1 males and 57% of age 1 females were not mature in the river. GSI patterns suggest that males in the reservoir adopted one of two reproductive strategies (nesters or cuckolders), whereas no small males with large enough testes to be considered cuckolders were apparent in the river. The warm thermal regime of Mirgenbach Reservoir led to precocial maturity, early season reproduction, and the greater prevalence of apparent cuckolder males than would normally occur in this climatic zone. PMID:27157335

  9. 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.

  10. 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

  11. 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

  12. 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...

  13. 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

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

    NASA Astrophysics Data System (ADS)

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

    2007-01-01

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

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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...

  2. 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.

  3. 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

  4. 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

  5. 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

  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. 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.

  8. 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.

  9. 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

  10. 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.

  11. 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.

  12. 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.

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

    PubMed

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

    2016-01-01

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

  14. Magmas, Mushes and Mobility: Thermal Histories of Magma Reservoirs from Combined U-Series and Diffusion Ages

    NASA Astrophysics Data System (ADS)

    Cooper, K. M.; Rubin, A. E.; Schrecengost, K.; Kent, A. J.; Huber, C.

    2014-12-01

    The thermal conditions of magma storage control many aspects of the dynamics of a magma reservoir system. For example, the temperature of magma storage directly relates to the crystallinity, and magmas stored at relatively low temperatures in a crystal mush (more than 40-50% crystalline) must be remobilized (e.g., by heating) before they can be erupted. A better understanding of the duration of magma storage at largely-liquid vs. largely-solid conditions is thus critical to understanding crustal magmatic processes such as magma mixing and for quantifying the hazard potential of a given volcano. Although mineral thermometry reflects the conditions of crystal growth or equilibration, these may not correspond to the thermal conditions of crystal storage. The duration of crystal storage at high temperatures can be quantified by comparing U-series crystal ages with the time scales over which disequilibrium trace-element profiles in the same crystals would be erased by diffusion. In the case of Mount Hood, OR, such a comparison for the two most recent eruptions shows that <12% of the total lifetime of plagioclase crystals (minimum 21 kyr) was spent at temperatures high enough that the magma would be easily mobilized. Partial data sets for other systems suggest such behavior is common, although the diffusion and U-series ages in these cases are from different samples and may not be directly comparable. We will present preliminary data combining U-series dating and diffusion timescales on the same samples for other volcanic systems (e.g., Lassen Volcanic Center, Mount St. Helens, Okataina Volcanic Center, New Zealand). Combining these data with numerical models offers additional insights into the controls on the conditions of storage. In addition, extension of this approach to combining U-Th ages with time scales of Li diffusion in zircon offers a promising new method to quantify thermal histories of silicic reservoir systems.

  15. 14C dating of bone using (gamma) Carboxyglutamic Acid and Carboxyglycine (Aminomalonate)

    SciTech Connect

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

    1999-04-27

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

  16. 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.

  17. 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.

  18. Reservoir to river passage of age-0+ year fishes, indication of a dispersion pathway for a non-native species.

    PubMed

    Janáč, M; Jurajda, P; Kružíková, L; Roche, K; Prášek, V

    2013-03-01

    This study demonstrates passage of age-0+ year individuals of pikeperch Sander lucioperca, common bream Abramis brama and non-native tubenose goby Proterorhinus semilunaris from the Nové Mlýny Reservoir into the River Dyje (Danube River basin, Czech Republic) through the turbine of a hydropower facility. Most fishes had standard length (LS ) in the range 12-33 mm. Seasonal patterns corresponded with spawning activity, i.e. an early single spawning event for S. lucioperca, multiple spawning events for A. brama and continuous spawning with a later start and prolonged duration for P. semilunaris. Sander lucioperca, P. semilunaris and larger A. brama (>22 mm) drifted almost exclusively during the dark; smaller A. brama displayed no preference for light or dark. Proterorhinus semilunaris displayed significantly lower mortality than other species when passing through the turbine (3% compared to 18%). The passage of high numbers of P. semilunaris from the reservoir (estimated at 473 000 individuals per year), and their subsequent mass downstream drift, may have contributed to rapid population establishment along the River Dyje and the quick downstream expansion. PMID:23464556

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

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

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 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...

  5. 17 CFR 240.14c-7 - Providing copies of material for certain beneficial owners.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 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...

  6. 17 CFR 240.14c-4 - Presentation of information in information statement.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... information statement. 240.14c-4 Section 240.14c-4 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-4 Presentation of information in information statement. (a) The...

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

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 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...

  8. 17 CFR 240.14c-6 - False or misleading statements.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    .... 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...

  9. 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...

  10. 17 CFR 240.14c-6 - False or misleading statements.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    .... 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...

  11. 17 CFR 240.14c-7 - Providing copies of material for certain beneficial owners.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 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...

  12. 17 CFR 240.14c-4 - Presentation of information in information statement.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... information statement. 240.14c-4 Section 240.14c-4 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-4 Presentation of information in information statement. (a) The...

  13. 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...

  14. 17 CFR 240.14c-6 - False or misleading statements.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    .... 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...

  15. 17 CFR 240.14c-6 - False or misleading statements.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    .... 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...

  16. 17 CFR 240.14c-7 - Providing copies of material for certain beneficial owners.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 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...

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

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... information statement. 240.14c-4 Section 240.14c-4 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-4 Presentation of information in information statement. (a) The...

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

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 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...

  19. 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...

  20. The Mean Age of Mantle and Crustal Reservoirs for the Planet Mars

    NASA Technical Reports Server (NTRS)

    Jacobsen, S. B.; Yin Q-Z.

    2002-01-01

    Based on all available isotopic and trace element data for SNCs we obtain a mean age of formation of the crust on Mars of 3.4 +/- .6 Ga. Additional information is contained in the original extended abstract.

  1. Reservoir age based on pre-bomb shells from the intertidal zone along the coast of Israel

    NASA Astrophysics Data System (ADS)

    Boaretto, E.; Mienis, H. K.; Sivan, D.

    2010-04-01

    Local sea level curves are obtained by using various methods, from land as well as from sea records and are based on different indicators. The most updated Holocene sea level curve for the coast of Israel, Eastern Mediterranean, from about 9500 cal years ago up to about 700 hundred years ago (the end of the Crusaders period) is based mainly on coastal archaeological remains. For the last Millennia an attempt was made to use bio-constructions along the present-day abrasion platforms as a tool for reconstructing past sea levels. Here we present radiocarbon dating of pre-bomb mollusks from the intertidal zone in order to determine the reservoir age of the bio-construction.

  2. Dating a Small Impact Crater: An Age of Kaali Crater (Estonia) Based on Charcoal Emplaced Within Proximal Ejecta

    NASA Astrophysics Data System (ADS)

    Losiak, A.; Wild, E. M.; Geppert, W. D.; Huber, M. S.; Jõeleht, A.; Kriiska, A.; Kulkov, A.; Paavel, K.; Pirkovic, I.; Plado, J.; Steier, P.; Välja, R.; Wilk, J.; Wisniowski, T.; Zanetti, M.

    2015-09-01

    The Kaali crater was formed shortly after (tpq) 1530-1455 BC (3237 ± 10 14C yr BP). This age is based on dating charcoal within the ejecta blanket that makes it directly related to the impact, and not susceptible to potential reservoir effects.

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. 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...

  8. Integrated Outcrop and Subsurface Studies of the Interwell Environment of Carbonate Reservoirs: Clear Fork (Leonaradian Age) Reservoirs, West Texas and New Mexico

    SciTech Connect

    Lucia, F. Jerry; Jennings, Jr., James W.

    2001-05-08

    A preliminary reservoir model was constructed for the Lower Clear Fork of the South Wasson Clear Fork reservoir. The model was constructed by calibrating high-frequency cycles observed in cores to the porosity log. The rock fabrics mostly fall in petrophysical class 1, and cross plots of porosity and water saturation could not be used to identify rock fabrics. Data from two limestone fields and one dolostone field were presented to support the contention that grain-dominated fabrics have higher porosity than mud-dominated fabrics do and that this difference is retained when the limestone is dolomitized.

  9. 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

  10. Age Dating Fluvial Sediment Storage Reservoirs to Construct Sediment Waiting Time Distributions

    NASA Astrophysics Data System (ADS)

    Skalak, K.; Pizzuto, J. E.; Benthem, A.; Karwan, D. L.; Mahan, S.

    2015-12-01

    Suspended sediment transport is an important geomorphic process that can often control the transport of nutrients and contaminants. The time a particle spends in storage remains a critical knowledge gap in understanding particle trajectories through landscapes. We dated floodplain deposits in South River, VA, using fallout radionuclides (Pb-210, Cs-137), optically stimulated luminescence (OSL), and radiocarbon dating to determine sediment ages and construct sediment waiting time distributions. We have a total of 14 age dates in two eroding banks. We combine these age dates with a well-constrained history of mercury concentrations on suspended sediment in the river from an industrial release. Ages from fallout radionuclides document sedimentation from the early 1900s to the present, and agree with the history of mercury contamination. OSL dates span approximately 200 to 17,000 years old. We performed a standard Weibull analysis of nonexceedance to construct a waiting time distribution of floodplain sediment for the South River. The mean waiting time for floodplain sediment is 2930 years, while the median is approximately 710 years. When the floodplain waiting time distribution is combined with the waiting time distribution for in-channel sediment storage (available from previous studies), the mean waiting time shifts to approximately 680 years, suggesting that quantifying sediment waiting times for both channel and floodplain storage is critical in advancing knowledge of particle trajectories through watersheds.

  11. 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

  12. 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.

  13. Growth and mortality of age-0 northern squawfish, Ptychocheilus oregonensis, rearing in shoreline habitats of the Columbia River Reservoir

    USGS Publications Warehouse

    Barfoot, C.A.; Gadomski, D.M.; Wertheimer, R.H.

    1999-01-01

    We investigated growth and mortality of age-0 northern squawfish during early rearing in shallow shoreline habitats. Larvae and juveniles (n=22914) were collected by weekly seining at three sample sites in the upper John Day Reservoir, Columbia River, during June through early September 1994–1996. Using a length-based ageing method, it was estimated that the exponential growth rate (G) for a common growth stanza (10–28 mm standard length SL) was significantly higher in 1994 (G=0.047) than in 1996 (G=0.037). Growth rate in 1995 could not be estimated, but was probably intermediate between 1994 and 1996 based on mean standard lengths of fish collected at the end of each sampling season (46.3, 40.0, and 32.0 mm SL in 1994, 1995, and 1996, respectively). For many fish species, variations in early growth can influence survival through size-selective mortality processes. Consistent with this possibility, our estimates of instantaneous mortality rates (Z) demonstrated that larvae and juveniles had significantly higher mortality in 1996 than in 1994 (Z=0.103 in 1994, versus Z=0.138 in 1996). Enhanced growth and lower mortality in 1994 were associated with a number of interrelated environmental conditions – comparatively low flows and turbidities, abundant instream vegetative cover, and high near-shore water temperatures.

  14. 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

  15. Tree-ring 14C links seismic swarm to CO2 spike at Yellowstone, USA

    USGS Publications Warehouse

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

    2010-01-01

    Mechanisms to explain swarms of shallow seismicity and inflation-deflation cycles at Yellowstone caldera (western United States) commonly invoke episodic escape of magma-derived brines or gases from the ductile zone, but no correlative changes in the surface efflux of magmatic constituents have ever been documented. Our analysis of individual growth rings in a tree core from the Mud Volcano thermal area within the caldera links a sharp ~25% drop in 14C to a local seismic swarm in 1978. The implied fivefold increase in CO2 emissions clearly associates swarm seismicity with upflow of magma-derived fluid and shows that pulses of magmatic CO2 can rapidly traverse the 5-kmthick brittle zone, even through Yellowstone's enormous hydrothermal reservoir. The 1978 event predates annual deformation surveys, but recognized connections between subsequent seismic swarms and changes in deformation suggest that CO2 might drive both processes. ?? 2010 Geological Society of America.

  16. 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

  17. INTEGRATED OUTCROP AND SUBSURFACE STUDIES OF THE INTERWELL ENVIRONMENT OF CARBONATE RESERVOIRS: CLEAR FORK (LEONARADIAN AGE) RESERVOIRS, WEST TEXAS AND NEW MEXICO

    SciTech Connect

    James W. Jennings, Jr.; F. Jerry Lucia

    2001-10-01

    Petrophysical heterogeneity in the South Wasson Clear Fork (SWCF) reservoir and other shallow-water platform carbonates in the Permian Basin and elsewhere is composed of a large-scale stratigraphically controlled component and a small-scale poorly correlated component. The large-scale variability exists as a flow-unit scale petrophysical layering that is laterally persistent at interwell scales and produces highly stratified reservoir behavior. Capturing the rate-enhancing effect of the small-scale variability requires carefully controlled averaging procedures at four levels of scaleup. Porosity can be easily scaled using arithmetic averaging procedures. Permeability, however, requires carefully controlled power-averaging procedures. Effective permeability is increased at every scaleup level.

  18. 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

  19. 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

    Cosmogenic nuclides are routinely used to investigate deglaciation histories by exposure dating of rock surfaces after glacier retreat. For bedrock surfaces that have been efficiently eroded by glacier ice, the most commonly applied cosmogenic 10Be isotope has proven to give reliable estimates of the integrated time of surface exposure since major ice decay. Due to its long half-life (~1.4 Ma), however, 10Be does not record short episodes of intermittent surface cover, e.g. during phases of glacier readvance, which might have interrupted the general deglaciation trend. To detect such cases of "complex exposure", 10Be-based dating can be combined with the analysis of the short-lived (5730 a) in situ cosmogenic 14C nuclide. We present two examples, in which combined in situ 14C-10Be analysis has been successfully applied to reconstruct in detail post-LGM surface exposures histories - in the Swiss Alps [1] and in Antarctica [2]. In a study on the Gotthard Pass, Central Swiss Alps, in situ 14C-10Be exposure dating was combined with extensive mapping of glacial erosional features. Data from both cosmogenic nuclides are in overall good agreement with each other confirming continuous exposure of the Gotthard Pass area throughout the Holocene. Some slightly younger in situ 14C ages compared to the corresponding 10Be ages are interpreted to result from partial surface shielding due to snow cover. Constraining the average Holocene snow depth from the in situ 14C data allowed to apply an appropriate snow shielding correction for the 10Be exposure ages. Integration of the snow-corrected exposure ages with field observations provided a detailed chronology of a progressive downwasting of ice from the maximum LGM ice volume with a gradual reorganization of the ice flow pattern and a southward migration of the ice divide. In a study on the evolution and reorganization of ice streams entering the Weddell Sea, Antarctica, during the last deglaciation, ice sheet modelling was

  20. 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

  1. 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.

  2. 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

  3. 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.

  4. 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

  5. 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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  7. The western Mediterranean basin as an aged aerosols reservoir. Insights from an old-fashioned but efficient radiotracer

    NASA Astrophysics Data System (ADS)

    Brattich, E.; Hernández-Ceballos, M. A.; Orza, J. A. G.; Bolívar, J. P.; Tositti, L.

    2016-09-01

    The long-term contemporary 210Pb time series acquired during the period 2004-2011 at two distant sites of different altitude in the Mediterranean basin, El Arenosillo (40 m a.s.l. in southwestern Spain) and Mt. Cimone (2165 m a.s.l. in northern Italy), are analyzed and compared. Besides being considered a tracer of continental air masses, 210Pb radionuclide is also a proxy of fine stable aerosol. For this reason, the measurements of PM10 mass concentrations collected at the same time and the corresponding 210Pb/PM10 ratio at the two sites are considered to gain better insights into the origin and size of the particles. Three statistical trajectory methods are applied to identify and characterize the 210Pb source regions at the two sites. The three methods yield similar outcomes in the source identification, which strengthens the robustness of our results. In addition to the importance of the transport from areas of continental Europe, this study highlights the relevant role of the Mediterranean Sea as a major 210Pb reservoir layer associated to the aged air masses that accumulate in the western Mediterranean basin. The analysis of the sources points out the significant influence of northern Africa to 210Pb increases at both sites as well, even though the most intensive episodes are not of Saharan origin.

  8. Dynamics of the resting CD4+ T-cell latent HIV reservoir in infants initiating HAART less than 6 months of age

    PubMed Central

    Persaud, Deborah; Palumbo, Paul E.; Ziemniak, Carrie; Hughes, Michael D.; Alvero, Carmelita G.; Luzuriaga, Katherine; Yogev, Ram; Capparelli, Edmund V.; Chadwick, Ellen G.

    2012-01-01

    Objectives Identification of HIV infection in exposed infants facilitates early therapy, which may limit viral reservoirs that maintain HIV infection under HAART. Methods The dynamics of the resting CD4+ T-cell latent HIV reservoir was determined over the first 2 years of life in 17 HIV-infected infants initiating lopinavir/ritonavir-based HAART at a median age of 8.1 weeks and achieving adequate suppression of plasma viral load by 24 weeks. Results The resting CD4+ T-cell latent HIV reservoir was detected in 12 of 14 (86%) infants tested at 24 weeks of HAART [median frequency 1.88 infectious units per million (IUPM); range <0.22 to 81.7), and remained measurable (median IUPM =0.32; range < 0.22 to 3.25) in six of 10 (60%) children retested at 96 weeks. The reservoir declined, from 24 to 96 weeks of HAART, at an estimated mean rate of 0.028 log10 IUPM/month, corresponding to a half-life of 11 months (95% confidence interval 6–30 months]. A strong relationship was found between the frequency of latently infected CD4+T cells at 96 weeks of HAART and time to first undetectable plasma viral load (Spearman r =0.91, P <0.001). Conclusion Although the resting CD4+ T-cell latent reservoir remains detectable over the first 2 years of HAART in a substantial proportion of infants, its size is associated with time to first undetectable viral load. To minimize HIV reservoirs in infants, rapid curtailment of viremia may limit HIV reservoirs and should be a therapeutic goal of early HAART in infants. PMID:22555165

  9. 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.

  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. 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.

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

    NASA Astrophysics Data System (ADS)

    Vita-Finzi, Claudio; Leaney, Fred

    2006-05-01

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

  16. 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

  17. 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.

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

    USGS Publications Warehouse

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

    2013-01-01

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

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  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. 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

  5. The Dora-Maira Unit (Italian Cottian Alps): a reservoir of ornamental stones locally and worldwide employed since Roman age

    NASA Astrophysics Data System (ADS)

    Borghi, Alessandro; Cadoppi, Paola; Antonella Dino, Giovanna

    2015-04-01

    The Dora-Maira is a geological unit belonging to the Penninic Domain of the Western Alps (NW Italy), which covers over 1000 km2 from the Susa to the Maira valleys, in the inner part of the Cottian Alps. It consists of different superposed complexes made of micaschists, fine-grained gneisses, quartzites, impure and dolomitic marbles, metabasites and various types of orthogneisses deriving from metamorphic transformation, during alpine orogeny, of a Palaeozoic upper continental crust and its Mesozoic carbonate cover. Thanks to the presence of different varieties of rocks, the Dora-Maira Unit can be considered as a reservoir of ornamental stones, locally employed, since Roman age, for military and religious buildings. Furthermore, these materials were used in Piedmont region for the construction of important historical palaces (17th and 18th centuries). Several varieties of gneisses, quartzites and marbles, exploited in the past and up to now, come from the Paleozoic basement. The most famous variety of gneiss is the so called "Luserna stone", a leucocratic gneiss characterized by a mylonitic fabric deriving from highly differentiated granitoids of Permian age. The first traces of Luserna Stone exploitation arise to the medieval age in the Pellice Valley). This material was widely employed in Turin, from Savoia kingdom period up to know. The very peculiar and precious application of Luserna stone were: Royal Palace and Venaria Reale Palace, Mole Antonelliana. Recently, it has been employed for the construction of Turin Metro stations (launched in 2006). Other varieties of orthogneisses, not yet exploited, are: Borgone and Vaie Stones, Villarfocchiardo and Cumiana Stones. They were used for the realization of the columns characterising the façade of several churches in Turin and in the piers of different bridges over the Po River. Another gneiss variety, with dioritic composition, is the Malanaggio Stone employed in the Fenestrelle Fortress. As for the palaeozoic

  6. The disposition of /sup 14/C-trimethyltin in the pregnant rat and fetus

    SciTech Connect

    Lipscomb, J.C.; Paule, M.G.; Slikker, W. Jr.

    1989-03-01

    Trimethyltin (TMT) is a potent neurotoxicant. For unknown reasons, age at exposure to TMT may dramatically influence the severity of TMT-induced neuropathology. We have demonstrated previously that radiolabel derived from (/sup 14/C)-TMT given to pregnant dams on gestational day (GD) 17 is found in fetal brain and blood. The present study was designed to determine the distribution of radiolabel derived from (14C)-TMT to brain and other tissue in fetuses from dams dosed on either GD 12 or 17 with 7.0 mg/kg TMT chloride. Radioactivity in GD 12 and GD 17 maternal whole blood peaked 1 hour after IP treatment. Whole blood elimination half-lives were 12-15 days. Peak radiolabel concentrations in GD 12 maternal and fetal brain were only 11-30% of those from GD 17 animals, however, peak fetal brain concentrations of radiolabel were not different from their respective maternal brain concentrations. Radiolabel concentrations in liver, kidney, and adrenal of GD 17 dams were higher than those in corresponding GD 12 tissues. Combined urinary and fecal elimination of radiolabel for two weeks after dosing accounted for 31 and 22% of the GD 12 and 17 doses, respectively. It appears that gestational age influences the distribution and elimination of TMT in the rat.

  7. 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

  8. 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.

  9. 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.

  10. 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.

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

    PubMed Central

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

    2011-01-01

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

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

    PubMed

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

    2011-06-15

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

  14. 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.

  15. Release of (14)C-labelled carbon nanotubes from polycarbonate composites.

    PubMed

    Rhiem, Stefan; Barthel, Anne-Kathrin; Meyer-Plath, Asmus; Hennig, Michael P; Wachtendorf, Volker; Sturm, Heinz; Schäffer, Andreas; Maes, Hanna M

    2016-08-01

    Waste disposal of carbon nanotube (CNT) containing products is expected to be the most important pathway for release of CNTs into the environment. In the present work, the use of radiolabelled CNTs ((14)C-CNT) for polycarbonate polymer nanocomposites with 1 wt% (14)C-CNT content allowed for the first time to quantify and differentiate the CNT release according to the type of impact along the materials' ageing history. After an initial exposure of the nanocomposite by solar-like irradiation, further environmental impacts were applied to composite material. They aimed at mimicking disposal site conditions that may induce further ageing effects and CNT release. This study included shaking in water, rapid temperature changes, soaking in humic acid solution as well as waste water effluent, and, finally, gentle mechanical abrasion. All ageing impacts were applied sequentially, both on pristine (control) and on solar-irradiated nanocomposites. All experiments were accompanied by absolute quantification of radioactive release as well as chemical and morphological analyses of the nanocomposite surfaces using infra-red (IR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The morphological analysis showed that spectral irradiation can uncover CNT networks on the outer nanocomposite surface layers by polymer degradation. After having subjected the solar-irradiated nanocomposite to all studied disposal site effect, the total radioactive release was quantified to amount to 64 mg CNT/m(2), whereas only 0.8 mg CNT/m(2) were found for the un-irradiated control sample. Solar degradation of polymers was thus found to significantly increase the propensity of the studied polymer nanocomposites to release CNTs during ageing effects at the product's end-of-life typical for disposal sites. PMID:27194367

  16. 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...

  17. 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

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

    NASA Astrophysics Data System (ADS)

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

    2006-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  20. Translocation of Radioactive Carbon after the Application of 14C-Alanine and 14CO2 to Sunflower Leaves 1

    PubMed Central

    Chopowick, R. E.; Forward, D. F.

    1974-01-01

    14C-(UL)-l-Alanine was applied to the surface of mature leaves at the second node of sunflower (Helianthus annuus L. cv Commander) plants, under illumination. The alanine was absorbed during a 4-hour period, and some of it was metabolized by the absorbing tissue. After a lag period of about 15 minutes from first application, distribution of 14C through the plant proceeded in much the same pattern as when 14CO2 is assimilated by similar leaves. Most, if not all, of the 14C exported from the absorbing regions was in sucrose. Only minute amounts appeared in alanine or other amino acids in surrounding parts of the leaf blade or in the petiole, although these were strongly labeled in the tissue absorbing 14C-alanine. When 14CO2 was supplied for 15 minutes to leaves of different ages, amino acids were lightly labeled in the leaf blade. Mature green leaves exported only sucrose. Yellowing leaves on 60-day-old plants exported a variety of substances including amino acids. PMID:16658645

  1. 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.

  2. 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.

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. 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

  8. 14C BOMB-PULSE DATING AND STABLE ISOTOPE ANALYSIS FOR GROWTH RATE AND DIETARY INFORMATION IN BREAST CANCER?

    PubMed

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

    2016-06-01

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

  9. 14C BOMB-PULSE DATING AND STABLE ISOTOPE ANALYSIS FOR GROWTH RATE AND DIETARY INFORMATION IN BREAST CANCER?

    PubMed Central

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

    2016-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  11. Chemical and isotopic heterogeneity in the Yellowstone magma reservoir revealed through sub-crystal-scale zircon age, trace-element, and Hf-isotopic analyses

    NASA Astrophysics Data System (ADS)

    Stelten, M. E.; Cooper, K. M.; Vazquez, J. A.; Barfod, G. H.; Yin, Q.; Wimpenny, J.

    2012-12-01

    The Yellowstone Plateau (USA) hosts one of the largest Quaternary magmatic systems in the world, with caldera forming eruptions at ~2.1 Ma, ~1.3 Ma, and ~0.64 Ma, as well as numerous intracaldera and extracaldera eruptions between caldera-forming events. The most recent eruptive episode at Yellowstone caldera produced the intracaldera Central Plateau Member (CPM) of the Plateau Rhyolite, which erupted intermittently between ~170-70 ka with a cumulative volume ≥600 km3, approaching the volume of rhyolite erupted during the caldera-forming eruptions. Thus, the CPM rhyolites provide snapshots of a large silicic magmatic system though time. In this study we examine the degree of compositional heterogeneity in the Yellowstone magma reservoir by comparing SHRIMP age, SHRIMP trace element, and LA-MC-ICPMS Hf-isotopic data for zircons hosted in five CPM rhyolites. The CPM rhyolites included in this study are: 1) the Solfatara Plateau flow (SPF) and Hayden Valley flow (HVF), which erupted ca. 103 ka from the east side of Yellowstone caldera, 2) the West Yellowstone flow (WYF), which erupted ca. 114 ka from the west side of the caldera, and 3) the Pitchstone Plateau flow (PPF) and Grants Pass flow (GPF), which erupted from the west side of the caldera ca. 75 ka. Linking the age, trace-element, and Hf-isotopic compositions of zones within individual zircons provides a robust method for recognizing distinct crystal populations within the CPM rhyolites and tracking the chemical evolution of the magma reservoir through time. Comparing crystal populations in coeval rhyolites erupted from different parts of the caldera allows for assessment of whether the entire reservoir hosts similar crystal populations at a given time and thus provides insight into the degree of compositional heterogeneity within the magma reservoir. Zircons hosted in the SPF, HVF, and WYF have cores with ages that vary from near eruption age to 200 ka and display a wide range in trace-element and Hf

  12. 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.

  13. (14C)Aminopyrine breath test in chronic liver disease: preliminary diagnostic implications

    SciTech Connect

    Burnstein, A.V.; Galambos, J.T.

    1981-12-01

    The (14C)aminopyrine breath test (APBT) score, an estimate of hepatic mixed-oxidase function, was evaluated in 21 consecutive patients wih active nonalcoholic chronic liver diseases. Ten had primary biliary cirrhosis (PBC) and 11 had chronic active hepatitis (CAH). The APBT score was normal or elevated in patients with PBC (P less than 0.001), and lower than normal in CAH patients (P less than 0.01); 10.5 +/- 1.6 and 3.5 +/- 1.86, respectively, vs control 7.65 +/- 1.15 (mean +/- SD). The 11 patients with CAH included two middle-aged women who displayed ambiguous severe intrahepatic cholestasis. There was no overlap between the APBT scores of the 10 PBC and 11 CAH patients. These initial data suggest that the APBT may be helpful in the differentiation of PBC and CAH, including misleading cholestatic forms of CAH.

  14. Collection, analysis, and age-dating of sediment cores from 56 U.S. lakes and reservoirs sampled by the U.S. Geological Survey, 1992-2001

    USGS Publications Warehouse

    Van Metre, Peter; Wilson, Jennifer T.; Fuller, Christopher C.; Callender, Edward; Mahler, Barbara J.

    2004-01-01

    The U.S. Geological Survey Reconstructed Trends National Synthesis study collected sediment cores from 56 lakes and reservoirs between 1992 and 2001 across the United States. Most of the sampling was conducted as part of the National Water-Quality Assessment (NAWQA) Program. The primary objective of the study was to determine trends in particle-associated contaminants in response to urbanization; 47 of the 56 lakes are in or near one of 20 U.S. cities. Sampling was done with gravity, piston, and box corers from boats and push cores from boats or by wading, depending on the depth of water and thickness of sediment being sampled. Chemical analyses included major and trace elements, organochlorine pesticides, polychlorinated biphenyls, polycyclic aromatic hydrocarbons, cesium-137, and lead-210. Age-dating of the cores was done on the basis of radionuclide analyses and the position of the pre-reservoir land surface in the reservoir and, in a few cases, other chemical or lithologic depth-date markers. Dates were assigned in many cores on the basis of assumed constant mass accumulation between known depth-date markers. Dates assigned were supported using a variety of other date markers including first occurrence and peak concentrations of DDT and polychlorinated biphenyls and peak concentration of lead. A qualitative rating was assigned to each core on the basis of professional judgment to indicate the reliability of age assignments. A total of 122 cores were collected from the 56 lakes and age dates were assigned to 113 of them, representing 54 of the 56 lakes. Seventy-four of the 122 cores (61 percent) received a good rating for the assigned age dates, 28 cores (23 percent) a fair rating, and 11 cores (9 percent) a poor rating; nine cores (7 percent) had no dates assigned. An analysis of the influence of environmental factors on the apparent quality of age-dating of the cores concluded that the most important factor was the mass accumulation rate (MAR) of sediment: the

  15. Investigations of (Delta)14C, (delta)13C, and (delta)15N in vertebrae of white shark (Carcharodon carcharias) from the eastern North Pacific Ocean

    SciTech Connect

    Kerr, L A; Andrews, A H; Cailliet, G M; Brown, T A; Coale, K H

    2006-06-08

    The white shark (Carcharodon carcharias) has a complex life history that is characterized by large scale movements and a highly variable diet. Estimates of age and growth for the white shark from the eastern North Pacific Ocean indicate they have a slow growth rate and a relatively high longevity. Age, growth, and longevity estimates useful for stock assessment and fishery models, however, require some form of validation. By counting vertebral growth band pairs, ages can be estimated, but because not all sharks deposit annual growth bands and many are not easily discernable, it is necessary to validate growth band periodicity with an independent method. Radiocarbon ({sup 14}C) age validation uses the discrete {sup 14}C signal produced from thermonuclear testing in the 1950s and 1960s that is retained in skeletal structures as a time-specific marker. Growth band pairs in vertebrae, estimated as annual and spanning the 1930s to 1990s, were analyzed for {Delta}{sup 14}C and stable carbon and nitrogen isotopes ({delta}{sup 13}C and {delta}{sup 15}N). The aim of this study was to evaluate the utility of {sup 14}C age validation for a wide-ranging species with a complex life history and to use stable isotope measurements in vertebrae as a means of resolving complexity introduced into the {sup 14}C chronology by ontogenetic shifts in diet and habitat. Stable isotopes provided useful trophic position information; however, validation of age estimates was confounded by what may have been some combination of the dietary source of carbon to the vertebrae, large-scale movement patterns, and steep {sup 14}C gradients with depth in the eastern North Pacific Ocean.

  16. Post-bomb coral Δ14C record from Iki Island, Japan: possible evidence of oceanographic conditions on the northern East China Sea shelf

    NASA Astrophysics Data System (ADS)

    Mitsuguchi, Takehiro; Hirota, Masashi; Paleo Labo AMS Dating Group; Yamazaki, Atsuko; Watanabe, Tsuyoshi; Yamano, Hiroya

    2016-07-01

    In this study, a sea-surface water Δ14C record of AD 1966-2000 (i.e., after the atmospheric nuclear-bomb testing period of the mid-1950s to early 1960s) was reconstructed from a coral sample collected from Iki Island, western Japan. The island is located in the Tsushima Strait where the Tsushima Current flows from the East China Sea (ECS) continental shelf into the Sea of Japan, indicating a strong influence of the ECS shelf water on the island. It is widely accepted that the Tsushima Current originates in the area between the ECS shelf break and the Nansei Islands further offshore as a branch of the Kuroshio Current, although another possible origin is the Taiwan-Tsushima Current System. The Δ14C record from Iki Island shows the following evidence of a response to the atmospheric nuclear testing: (1) an increase from ~55‰ in 1966 to ~133‰ in 1970, (2) a plateau ranging between ~123 and ~142‰ during the 1970s to the late 1980s, and (3) a gradual decrease from ~115‰ in 1990 to ~83‰ in 2000. Comparison of this record with coral Δ14C records from the Nansei Islands (Okinawa Island, Ishigaki Island and Kikai Island), located ~160-280 km off the ECS shelf break and little influenced by the shelf water, suggests that the surface-water Δ14C around Iki Island was ~30-45‰ lower than that of the Nansei Islands from the mid-1960s to late 1970s, and that the Δ14C difference between Iki Island and the Nansei Islands decreased from the end of the 1970s to ~0-15‰ in the mid-1980s to 2000. The lower Δ14C around Iki Island can be explained as follows: (1) in contrast to the Nansei Islands area, the ECS shelf area is a vertically mixed, highly concentrated carbon reservoir significantly connected to subsurface and deeper waters outside the shelf area, strongly suggesting that the surface-water Δ14C of the shelf area (perhaps excepting very shallow innermost shelf areas) was significantly less sensitive to the atmospheric nuclear-bomb 14C spike than that of the

  17. 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.

  18. 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

  19. 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

  20. Age-specific metal and accumulation patterns in different tissues of nase (Chodrostoma nasus) from the Medjuvršje Reservoir.

    PubMed

    Djikanović, Vesna; Skorić, Stefan; Jarić, Ivan; Lenhardt, Mirjana

    2016-10-01

    Nase (Chodrostoma nasus L. 1758) specimens of four age classes (1(+) to 4(+)) were caught in July 2013 in the Medjuvršje Reservoir. Concentrations of 14 metals and elements (Al, B, Ba, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Si, Sr, Zn) in the muscle, gills and liver were analyzed by inductively-coupled plasma optical spectrometry (ICP-OES). The highest concentrations of Al, Ba, Co, Cr, Mn, Si, Sr and Zn were detected in gills, while Cd, Cu, Fe and Mo reached the highest values in the liver. The majority of the analyzed elements were found in minimal concentrations in the muscle. Younger age classes (1(+), 2(+)) were differentiated by higher concentrations of Mn, Sr and Zn in muscle tissue, while the older ones were mainly differentiated by higher concentrations for Ni and Cu. The youngest age class (1(+)) was distinguished by higher concentrations of Zn, while the oldest age class (4(+)) was distinguished by higher concentrations of Ba, Cu, Mo and Sr in gills. Results obtained were likely caused by differences in the physiology and feeding habits between younger (1-2(+)) and older (3-4(+)) age groups of nase. PMID:27232958

  1. 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.

  2. 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

  3. 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.

  4. 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

  5. (/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.

  6. (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

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

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

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

  8. Comparison of nonabsorbable markers Poly R-478 and (14C)PEG-4,000 for use in developmental absorption studies

    SciTech Connect

    Stahl, G.E.; Fayer, J.C.; Ling, S.C.; Watkins, J.B. )

    1991-05-01

    To determine the utility of Poly R-478, a stable, polymeric dye (MW, 40,000), as a nonabsorbable marker for studies in the developing small intestine, it was validated by comparison to carbon 14-labeled polyethylene glycol, MW 4,000 (( 14C)PEG-4,000) in rats from 14 to 40 days of age. The recovery and quantification of Poly R-478 from biological samples is simple and rapid compared to other nonradioactive nonabsorbable markers. In 40-day-old rats simultaneously given Poly R-478 and (14C)PEG, total recoveries were similar, the percentages of the Poly R-478 dose and the (14C)PEG dose recovered per segment were identical, and taurocholate absorption rates calculated using each marker were comparable. Recovery of Poly R-478 from flushed intestinal segments, determined by a one-step extraction, was equivalent to that of (14C)PEG in 40-day-old rats (96.5 {plus minus} 3.7% versus 102.7 {plus minus} 10.1%; NS) but was superior to that of (14C)PEG in 21-day-old rats (98.0 {plus minus} 6.2% versus 63.4 {plus minus} 5.5%; p less than 0.001) and 14-day-old rats (97.8 {plus minus} 6.7% versus 56.7 {plus minus} 12.6%; p less than 0.001). Within each age group, the distribution of Poly R-478 within the intestine was similar to that of (14C)PEG. In addition, total taurocholate absorption in the presence of Poly R-478 was comparable to that in the presence of (14C)PEG. Complete recovery of Poly R-478 from a suspension of liver particles and from mixtures with two commercial infant formulas was demonstrated in vitro, suggesting that Poly R-478 may be used when foods are present in the intestine.

  9. Dermal penetration and systemic distribution of sup 14 C-labeled vitamin E human skin grafted athymic nude mice

    SciTech Connect

    Klain, G.J.

    1989-03-13

    In vivo percutaneous penetration and tissue distribution of 14C-labeled vitamin E applied to human skin grafted onto athymic nude mice were determined. At 1 hr, mouse skin contained the highest level of radioactivity, followed by the muscle, blood, liver, lung, adipose tissue, spleen, kidney, brain, heart, and eyes. A linear increase with time in tissue radioactivity was observed throughout the 24 hr experimental period. At 4 and 24 hrs skin grafts were highly radioactive. At 4 hrs the epidermis and the upper portion of the dermis contained more radioactivity than the remaining portion of the dermis. In contrast, at 24 hrs the highest level of radioactivity was detected in the lower dermis. No radioactivity was detected in expired air while 0.2% of the dose was found in the urine. The data show that vitamin E does penetrate skin and that the dermis acts as a barrier or reservoir for this highly lipophilic compound.

  10. 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.

  11. Associated terrestrial and marine fossils in the late-glacial Presumpscot Formation, southern Maine, USA, and the marine reservoir effect on radiocarbon ages

    USGS Publications Warehouse

    Thompson, W.B.; Griggs, C.B.; Miller, N.G.; Nelson, R.E.; Weddle, T.K.; Kilian, T.M.

    2011-01-01

    Excavations in the late-glacial Presumpscot Formation at Portland, Maine, uncovered tree remains and other terrestrial organics associated with marine invertebrate shells in a landslide deposit. Buds of Populus balsamifera (balsam poplar) occurred with twigs of Picea glauca (white spruce) in the Presumpscot clay. Tree rings in Picea logs indicate that the trees all died during winter dormancy in the same year. Ring widths show patterns of variation indicating responses to environmental changes. Fossil mosses and insects represent a variety of species and wet to dry microsites. The late-glacial environment at the site was similar to that of today's Maine coast. Radiocarbon ages of 14 tree samples are 11,907??31 to 11,650??5014C yr BP. Wiggle matching of dated tree-ring segments to radiocarbon calibration data sets dates the landslide occurrence at ca. 13,520+95/??20calyr BP. Ages of shells juxtaposed with the logs are 12,850??6514C yr BP (Mytilus edulis) and 12,800??5514C yr BP (Balanus sp.), indicating a marine reservoir age of about 1000yr. Using this value to correct previously published radiocarbon ages reduces the discrepancy between the Maine deglaciation chronology and the varve-based chronology elsewhere in New England. ?? 2011 University of Washington.

  12. 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...

  13. 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...

  14. 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.

  15. 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...

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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

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

    PubMed Central

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

    2015-01-01

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

  3. What are we Dating? An Evaluation of Chemical Pretreatment Methods for AMS 14C Dating of Peat

    NASA Astrophysics Data System (ADS)

    Scharer, K.; Kashgarian, M.; Zermeno, P.; Kurdyla, D.

    2006-12-01

    Progressive deformation of landforms commonly creates depositional environments where organic-rich sediment layers such as peats are preserved (e.g., Wrightwood, Coachella, Vedanta paleoseismic sites). Field studies using 3-D excavation methods can improve estimates of landform displacement, while AMS 14C dating of well characterized organic material sampled during field work is essential for determining slip rates associated with landform deformations. Here we present results of a test of chemical pretreatment used for AMS 14C dating of peat in an attempt to better characterize what we are dating and how the age of organic fractions is affected by different extraction procedures. Standard chemical pretreatment of organic materials for AMS 14C analysis typically isolates three broad organic fractions: humic acids, humin, and fulvic acids. Humic acids, the focus of this study, are thought to result from complex degradation of lignin and related compounds, and in principle should provide the most accurate age of in-situ organic layers (i.e., the decomposed leaf of a plant). The extraction of humic acid from organic-rich sediments or soils is operationally defined by chemical solubility and is not directly associated with a particular starting material. This means that chemical extracts are likely to contain humic acids derived from different starting materials which may have different ages and origins. In earlier studies of the duration of chemical pretreatment, Cook et al. (1998) found that increasing the amount of time that peat was exposed to NaOH increased the quantity of humics extracted, and Williams (1989) reported that increasing the duration of the NaOH wash will sometimes, but not always, result in an older sample age. Thus, a long base extraction time may solubilize more resistant and potentially older humics. To test whether the duration of the base extraction step affects dates, we extracted humic acid from three peat layers from the Wrightwood

  4. 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.

  5. 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

  6. 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.

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

    SciTech Connect

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

    2006-01-01

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

  8. Re-examination of crystal ages in recent Mount St. Helens lavas: implications for magma reservoir processes

    NASA Astrophysics Data System (ADS)

    Cooper, Kari M.; Reid, Mary R.

    2003-08-01

    U-series data for recent Mount St. Helens lavas suggest that crystallization preceded eruption by more than 0.5 ka but are complicated by possible evidence of crystal recycling and/or addition of radium to the liquid after crystallization. We report new ion and electron microprobe trace- and major-element data for plagioclase and pyroxene in these recent Mount St. Helens lavas and use these data to reassess 226Ra-230Th crystal ages by taking into account differences in the partitioning behavior of radium and barium and the effects of impurities in mineral separates. Revised 226Ra-230Th model crystallization ages are ∼2-4 ka for plagioclase (with the exception of the 1982 dacite) and ∼0.15-5.7 ka for pyroxene. In contrast to previous interpretations, no late-stage addition of Ra to the liquid after precipitation of the minerals is required. The variability of Ba concentrations measured in plagioclase is too large to be consistent with progressive crystallization from the same liquid or with diffusive re-equilibration of xenocrysts with a new host liquid. Ba heterogeneity limits the residence time of the crystals in a magma at high temperatures and also suggests that in most cases Ra-Th ages have not been significantly modified by Ra diffusion into or out of the crystals. High (226Ra)/Ba in plagioclase in the 1982 dacite relative to the host liquid likely reflects crystallization processes that precluded bulk crystal-liquid chemical equilibrium. One possibility is that of growth entrapment of surface enrichments during rapid crystallization, which could lead to less discrimination between Ra and Ba than predicted by calculated bulk partition coefficients. 226Ra-230Th crystal ages for the Castle Creek andesite and basalt that are younger than 230Th-238U ages of the same crystals could be explained by mixing of crystals into melts with different 230Th/232Th ratios, by combinations of older and younger crystal growth within the same magma, or, for the basalt, by

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

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

    PubMed Central

    MIYATA, Yoshiki; MINAMI, Masayo; ONBE, Shin; SAKAMOTO, Minoru; MATSUZAKI, Hiroyuki; NAKAMURA, Toshio; IMAMURA, Mineo

    2011-01-01

    AMS (Accelerator Mass Spectrometry) radiocarbon dates for eight potsherds from a single piece of pottery from a wetland archaeological site indicated that charred material from the inner pottery surfaces (5052 ± 12 BP; N = 5) is about 90 14C years older than that from the outer surfaces (4961 ± 22 BP; N = 7). We considered three possible causes of this difference: the old wood effect, reservoir effects, and diagenesis. We concluded that differences in the radiocarbon ages between materials from the inner and outer surfaces of the same pot were caused either by the freshwater reservoir effect or by diagenesis. Moreover, we found that the radiocarbon ages of carbonized material on outer surfaces (soot) of pottery from other wetland archaeological sites were the same as the ages of material on inner surfaces (charred food) of the same pot within error, suggesting absence of freshwater reservoir effect or diagenesis. PMID:21986315

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

    PubMed

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

    2011-01-01

    AMS (Accelerator Mass Spectrometry) radiocarbon dates for eight potsherds from a single piece of pottery from a wetland archaeological site indicated that charred material from the inner pottery surfaces (5052 ± 12 BP; N = 5) is about 90 (14)C years older than that from the outer surfaces (4961 ± 22 BP; N = 7). We considered three possible causes of this difference: the old wood effect, reservoir effects, and diagenesis. We concluded that differences in the radiocarbon ages between materials from the inner and outer surfaces of the same pot were caused either by the freshwater reservoir effect or by diagenesis. Moreover, we found that the radiocarbon ages of carbonized material on outer surfaces (soot) of pottery from other wetland archaeological sites were the same as the ages of material on inner surfaces (charred food) of the same pot within error, suggesting absence of freshwater reservoir effect or diagenesis. PMID:21986315

  16. 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

  17. 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.

  18. 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

  19. Rates of Litter Decomposition and Soil Respiration in Relation to Soil Temperature and Water in Different-Aged Pinus massoniana Forests in the Three Gorges Reservoir Area, China

    PubMed Central

    Zeng, Lixiong; Huang, Zhilin; Lei, Jingpin; Zhou, Benzhi; Li, Maihe

    2014-01-01

    To better understand the soil carbon dynamics and cycling in terrestrial ecosystems in response to environmental changes, we studied soil respiration, litter decomposition, and their relations to soil temperature and soil water content for 18-months (Aug. 2010–Jan. 2012) in three different-aged Pinus massoniana forests in the Three Gorges Reservoir Area, China. Across the experimental period, the mean total soil respiration and litter respiration were 1.94 and 0.81, 2.00 and 0.60, 2.19 and 0.71 µmol CO2 m−2 s−1, and the litter dry mass remaining was 57.6%, 56.2% and 61.3% in the 20-, 30-, and 46-year-old forests, respectively. We found that the temporal variations of soil respiration and litter decomposition rates can be well explained by soil temperature at 5 cm depth. Both the total soil respiration and litter respiration were significantly positively correlated with the litter decomposition rates. The mean contribution of the litter respiration to the total soil respiration was 31.0%–45.9% for the three different-aged forests. The present study found that the total soil respiration was not significantly affected by forest age when P. masonniana stands exceed a certain age (e.g. >20 years old), but it increased significantly with increased soil temperature. Hence, forest management strategies need to protect the understory vegetation to limit soil warming, in order to reduce the CO2 emission under the currently rapid global warming. The contribution of litter decomposition to the total soil respiration varies across spatial and temporal scales. This indicates the need for separate consideration of soil and litter respiration when assessing the climate impacts on forest carbon cycling. PMID:25004164

  20. 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.

  1. 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.

  2. Fate of /sup 14/C-allylalcohol herbicide in soils and crop residues

    SciTech Connect

    Scheunert, I.; Vockel, D.; Klein, W.; Korte, F.

    1981-01-01

    Residue disappearance and leaching of /sup 14/C-allylalcohol from different soils were studied in laboratory experiments. Additionally, the uptake of residues by lettuce and carrots was investigated in the greenhouse. In laboratory experiments, residue disappearance and leaching from soils was correlated negatively to the organic matter content. In greenhouse experiments with a sandy loam soil at an application rate normally used in practice, an average of 12.5% of the applied radioactivity was recovered after an eight day interval between application and sowing. Furthermore, an average of 8% (sum in soil and plants) of the applied radioactivity was recovered after lettuce or carrot growing. Uptake of residues was higher by carrots than by lettuce, and higher by lettuce roots than by lettuce tops. No bioaccumulation was observed. The residues in soils and plants were, to a high percent-age, unextractable and, to a smaller extent, fully water-soluble products. Unchanged allylalcohol could not be detected by the analytical methods used.

  3. Introducing the global carbon cycle to middle school students with a 14C research project

    NASA Astrophysics Data System (ADS)

    Brodman Larson, L.; Phillips, C. L.; LaFranchi, B. W.

    2012-12-01

    Global Climate Change (GCC) is currently not part of the California Science Standards for 7th grade. Required course elements, however, such as the carbon cycle, photosynthesis, and cellular respiration could be linked to global climate change. Here we present a lesson plan developed in collaboration with scientists from Lawrence Livermore National Laboratory, to involve 7th grade students in monitoring of fossil fuel emissions in the Richmond/San Pablo area of California. -The lesson plan is a Greenhouse Gas/Global Climate Change Unit, with an embedded research project in which students will collect plant samples from various locals for analysis of 14C, to determine if there is a correlation between location and how much CO2 is coming from fossil fuel combustion. Main learning objectives are for students to: 1) understand how fossil fuel emissions impact the global carbon cycle, 2) understand how scientists estimate fossil CO2 emissions, and 3) engage in hypothesis development and testing. This project also engages students in active science learning and helps to develop responsibility, two key factors for adolescentsWe expect to see a correlation between proximity to freeways and levels of fossil fuel emissions. This unit will introduce important GCC concepts to students at a younger age, and increase their knowledge about fossil fuel emissions in their local environment, as well as the regional and global impacts of fossil emissions.

  4. 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

  5. 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

  6. 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

  7. 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

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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

  13. 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.

  14. 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.

  15. 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

  16. 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...

  17. 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.

  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 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. 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...

  20. 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...

  1. 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...

  2. 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

  3. 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.

  4. 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

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

    SciTech Connect

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

    1991-04-15

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

  6. 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

  7. Towards sediment residence time in a Himalayan catchment? Insights from paired in-situ 14C and 10Be measurements in river sands

    NASA Astrophysics Data System (ADS)

    Lupker, M.; Hippe, K.; Wacker, L.; Wieler, R.

    2014-12-01

    Cosmogenic nuclides in detrital river sediments have been widely applied to derive denudation rates and sediment fluxes across entire catchments. Nuclides, such as 10Be, allow the derivation of denudation rates integrated over several hundreds to thousands of years, but single isotopic systems often provide little information on the intricate dynamics that control the export of sediments from catchments. The quantification of sediment storage and recycling within catchments is nevertheless crucial for a better understanding of the variability of sediments fluxes and their implication for landscape evolution. The paired measurement of 10Be along with cosmogenic, in-situ 14C in river sediments may provide new insides into sediment dynamics over kyr time scales for which other nuclides are not suitable [1,2]. In an effort to better understand the sediment dynamics in active orogens we combine in-situ 14C and 10Be measurements from the Kosi basin in eastern Nepal (~53 000 km2). Our preliminary 14C/10Be data shows apparent burial/storage ages of 14 to 21 kyr in the sediments currently exported by the river. These elevated burial ages suggest a larger storage component than previously thought in these catchments, even though possible biases associated to the use of 14C/10Be in sediments as burial chronometer have to be considered: First, the short half-life of 14C cannot be neglected and hence basin wide denudation cannot be considered as a simple mixing of sediments from individually eroding surfaces, introducing bias towards higher apparent burial ages in most settings. Second, in steep environments, sediments supplied by deep-seated landslides carry a buried signature that should not be confounded with sediment storage in the catchment. The importance of both biases needs to be quantified carefully, before basin-wide storage can be quantified. [1] Lauer & Willenbring, 2010 - JGR-Earth, vol. 115, F04018. [2] Hippe et al., 2012 - Geomorphology, vol. 179, pp. 58-70.

  8. 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.

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

    SciTech Connect

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

    1982-01-01

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

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

    SciTech Connect

    Smith, A.E.

    1986-11-01

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

  11. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  13. 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.

  14. 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...

  15. Carbonate petroleum reservoirs

    SciTech Connect

    Roehl, P.O.; Choquette, P.W.

    1985-01-01

    This book presents papers on the geology of petroleum deposits. Topics considered include diagenesis, porosity, dolomite reservoirs, deposition, reservoir rock, reefs, morphology, fracture-controlled production, Cenozoic reservoirs, Mesozoic reservoirs, and Paleozoic reservoirs.

  16. 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

  17. 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.

  18. 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.

  19. 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.

  20. 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

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 14C/C measurements support Andreev's internode method to determine lichen growth rates in Cladina stygia (Fr.) Ahti

    SciTech Connect

    Holt, E; Bench, G

    2007-12-05

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

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

    NASA Astrophysics Data System (ADS)

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

    1990-04-01

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

  9. TRITIUM RESERVOIR STRUCTURAL PERFORMANCE PREDICTION

    SciTech Connect

    Lam, P.S.; Morgan, M.J

    2005-11-10

    The burst test is used to assess the material performance of tritium reservoirs in the surveillance program in which reservoirs have been in service for extended periods of time. A materials system model and finite element procedure were developed under a Savannah River Site Plant-Directed Research and Development (PDRD) program to predict the structural response under a full range of loading and aged material conditions of the reservoir. The results show that the predicted burst pressure and volume ductility are in good agreement with the actual burst test results for the unexposed units. The material tensile properties used in the calculations were obtained from a curved tensile specimen harvested from a companion reservoir by Electric Discharge Machining (EDM). In the absence of exposed and aged material tensile data, literature data were used for demonstrating the methodology in terms of the helium-3 concentration in the metal and the depth of penetration in the reservoir sidewall. It can be shown that the volume ductility decreases significantly with the presence of tritium and its decay product, helium-3, in the metal, as was observed in the laboratory-controlled burst tests. The model and analytical procedure provides a predictive tool for reservoir structural integrity under aging conditions. It is recommended that benchmark tests and analysis for aged materials be performed. The methodology can be augmented to predict performance for reservoir with flaws.

  10. 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.

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

    NASA Astrophysics Data System (ADS)

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

    1989-03-01

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

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

    PubMed

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

    2016-01-01

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

  13. 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

  14. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2002-06-01

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

  16. Estimation of groundwater residence time using environmental radioisotopes (14C,T) in carbonate aquifers, southern Poland.

    PubMed

    Samborska, Katarzyna; Różkowski, Andrzej; Małoszewski, Piotr

    2013-01-01

    Triassic carbonate aquifers in the Upper Silesia region, affected by intense withdrawal, have been investigated by means of isotopic analyses of (14)C, δ(13)C, δ(2)H, δ(18)O and (3)H. The isotopic examinations were carried out in the 1970s and in the early 1980s, and it was the first application of tracers to estimate age and vulnerability for the contamination of groundwater in this region. Similar isotopic analyses were conducted in 2007 and 2008 with the same Triassic carbonate formation. The isotopic examinations were performed within the confined part of the carbonate formation, wherein aquifers are covered by semi-permeable deposits. The direct recharge of the aquifer occurs in the outcrop areas, but it mainly takes place due to percolation of the water through aquitards and erosional windows. The Triassic aquifer has been intensively drained by wells and by lead-zinc mines. Nowadays, the declining water demand and closure of some mines have induced a significant increase in the water table level. The detailed analysis of the results, including the radiocarbon age corrections and the comparison of radioisotope activities, has made it possible to estimate the range of residence time within the carbonate Triassic aquifer. This range from several tens to several tens of thousands indicates that the recharge of aquifers might have occurred between modern times and the Pleistocene. The apparent age of the water estimated on the basis of (14)C activity was corrected considering the carbon isotope exchange and the diffusion between mobile water in fractures and stagnant water in micropores. The obtained corrected period of recharge corresponds to the result of investigations of noble gases, which were carried out in the 1990s. In almost half of the cases, groundwater is a mixture of young and old water. The mixing processes occur mainly in areas of heavy exploitation of the aquifer. PMID:22607326

  17. Enhanced Mineralization of [U-14C]2,4-Dichlorophenoxyacetic Acid in Soil from the Rhizosphere of Trifolium pratense

    PubMed Central

    Shaw, Liz J.; Burns, Richard G.

    2004-01-01

    Enhanced biodegradation in the rhizosphere has been reported for many organic xenobiotic compounds, although the mechanisms are not fully understood. The purpose of this study was to discover whether rhizosphere-enhanced biodegradation is due to selective enrichment of degraders through growth on compounds produced by rhizodeposition. We monitored the mineralization of [U-14C]2,4-dichlorophenoxyacetic acid (2,4-D) in rhizosphere soil with no history of herbicide application collected over a period of 0 to 116 days after sowing of Lolium perenne and Trifolium pratense. The relationships between the mineralization kinetics, the number of 2,4-D degraders, and the diversity of genes encoding 2,4-D/α-ketoglutarate dioxygenase (tfdA) were investigated. The rhizosphere effect on [14C]2,4-D mineralization (50 μg g−1) was shown to be plant species and plant age specific. In comparison with nonplanted soil, there were significant (P < 0.05) reductions in the lag phase and enhancements of the maximum mineralization rate for 25- and 60-day T. pratense soil but not for 116-day T. pratense rhizosphere soil or for L. perenne rhizosphere soil of any age. Numbers of 2,4-D degraders in planted and nonplanted soil were low (most probable number, <100 g−1) and were not related to plant species or age. Single-strand conformational polymorphism analysis showed that plant species had no impact on the diversity of α-Proteobacteria tfdA-like genes, although an impact of 2,4-D application was recorded. Our results indicate that enhanced mineralization in T. pratense rhizosphere soil is not due to enrichment of 2,4-D-degrading microorganisms by rhizodeposits. We suggest an alternative mechanism in which one or more components of the rhizodeposits induce the 2,4-D pathway. PMID:15294813

  18. {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.

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

    PubMed

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

    2015-04-01

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

  20. 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.

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

    PubMed

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

    2013-05-01

    The (14)C content of 60 human blood serum samples from residents of Malmö (Sweden) in 1978, obtained from a biobank, has been measured to estimate the accuracy of (14)C bomb-pulse dating. The difference between the date estimated using the Calibomb software and sampling date varied between -3 ± 0.4 and +0.2 ± 0.5 years. The average age deviation of all samples was -1.5 ± 0.7 years, with the delay between production and consumption of foodstuffs being probably the dominating cause. The potential influence of food habits on the (14)C date has been evaluated using stable isotope δ(13)C and δ(15)N analysis and information about the dietary habits of the investigated individuals. Although the group consisting of lacto-ovo vegetarians and vegans (pooled group) was not completely separated from the omnivores in a stable isotopic trophic level diagram, this analysis proved to add valuable information on probable dietary habits. The age deviation of the sampling date from the respective Calibomb date was found strongly correlated with the δ(13)C values, probably due to influence from marine diet components. For the omnivore individuals, there were indications of seasonal effects on δ(13)C and the age deviation. No significant correlation was found between the age deviation and the δ(15)N values of any dietary group. No influence of sex or year of birth was found on neither the (14)C nor the δ(13)C and δ(15)N values of the serum samples. The data were also divided into two groups (omnivores and pooled group), based on the level of δ(15)N in the samples. The consumption of high δ(15)N-valued fish and birds can be responsible for this clustering. PMID:23358598

  2. 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.

  3. 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.

  4. 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

  5. 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.

  6. 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.

  7. 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

  8. 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

  9. Dating a small impact crater: An age of Kaali crater (Estonia) based on charcoal emplaced within proximal ejecta

    NASA Astrophysics Data System (ADS)

    Losiak, A.; Wild, E. M.; Geppert, W. D.; Huber, M. S.; Jõeleht, A.; Kriiska, A.; Kulkov, A.; Paavel, K.; Pirkovic, I.; Plado, J.; Steier, P.; VäLja, R.; Wilk, J.; Wisniowski, T.; Zanetti, M.

    2016-04-01

    The estimates of the age of the Kaali impact structure (Saaremaa Island, Estonia) provided by different authors vary by as much as 6000 years, ranging from ~6400 to ~400 before current era (BCE). In this study, a new age is obtained based on 14C dating charred plant material within the proximal ejecta blanket, which makes it directly related to the impact structure, and not susceptible to potential reservoir effects. Our results show that the Kaali crater was most probably formed shortly after 1530-1450 BCE (3237 ± 10 14C yr BP). Saaremaa was already inhabited when the bolide hit the Earth, thus, the crater-forming event was probably witnessed by humans. There is, however, no evidence that this event caused significant change in the material culture (e.g., known archeological artifacts) or patterns of human habitation on Saaremaa.

  10. Estimation of prevalence of Helicobacter pylori infection in an asymptomatic elderly population comparing [14C] urea breath test and serology.

    PubMed Central

    Newell, D G; Hawtin, P R; Stacey, A R; MacDougall, M H; Ruddle, A C

    1991-01-01

    A non-invasive serological assay devised in this laboratory had a sensitivity and specificity of 100% as determined by culture and confirmed by histology in a group of 47 patients who had undergone endoscopy. The correlation between serology and the non-invasive [14C] breath test was very good. Only one of 24 culture positive patients was, while all 23 culture negative patients were, breath test negative. In a group of 46 healthy elderly persons, however, significant anomalies between serology and breath test were observed. Only 83% of the breath test negative persons were seronegative, while only 68% of the breath test positive persons were seropositive. These results can be explained in terms of age related atrophic gastritis and immune incompetence, causing reduced colonisation and decreased antibody production, respectively. These investigations suggest that non-invasive tests for H pylori infection may not be reliable in the elderly. PMID:2045496

  11. 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.

  12. 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...

  13. 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.

  14. 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.

  15. 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

  16. 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.

  17. 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

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. 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

  5. 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...

  6. Kinetics of the uptake of sup 14 C-labeled chlorinated benzenes from soil by plants

    SciTech Connect

    Topp, E.; Scheunert, I.; Korte, F. )

    1989-04-01

    ({sup 14}C)Benzene, ({sup 14}C)1,2,4-trichlorobenzene, ({sup 14}C)pentachlorobenzene, and ({sup 14}C)hexachlorobenzene were applied to soils in outdoor lysimeters to a 10-cm depth (2 mg/kg dry soil); barley and cress plants were grown for one vegetation period and analyzed after varying time intervals. The bioaccumulation factors (concentration of radioactive substances in plants divided by that in soils) of barley were higher than those of cress, except for hexachlorobenzene. In barley, bioaccumulation factors increased with decreasing chlorine content of the molecules, except for benzene, whereas in cress hexachlorobenzene exhibited the highest bioaccumulation factor. The conversion ratios of chlorinated benzenes (percentage of conversion products based on total radioactivity in plants) were negatively correlated to the chlorine content of the molecules and, in barley, positively correlated with time; in general, they were higher in barley than in cress. The concentration of radioactive substances in the plants, as well as bioaccumulation factors, decreased with time, except for a slight increase in benzene-derived residues in barley after 125 days. This effect is due to growth dilution. The percentage of radioactivity in barley seeds, based on that in the whole plant, was negatively correlated to the chlorine content of the molecule.

  7. 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...

  8. 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...

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  10. 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.

  11. [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

  12. 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.

  13. 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

  14. 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.

  15. 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

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Growth rate and age distribution of deep-sea black corals in the Gulf of Mexico

    USGS Publications Warehouse

    Prouty, N.G.; Roark, E.B.; Buster, N.A.; Ross, S.W.

    2011-01-01

    Black corals (order Antipatharia) are important long-lived, habitat-forming, sessile, benthic suspension feeders that are found in all oceans and are usually found in water depths greater than 30 m. Deep-water black corals are some of the slowest-growing, longest-lived deep-sea corals known. Previous age dating of a limited number of black coral samples in the Gulf of Mexico focused on extrapolated ages and growth rates based on skeletal 210Pb dating. Our results greatly expand the age and growth rate data of black corals from the Gulf of Mexico. Radiocarbon analysis of the oldest Leiopathes sp. specimen from the upper De Soto Slope at 300 m water depth indicates that these animals have been growing continuously for at least the last 2 millennia, with growth rates ranging from 8 to 22 µm yr–1. Visual growth ring counts based on scanning electron microscopy images were in good agreement with the 14C-derived ages, suggestive of annual ring formation. The presence of bomb-derived 14C in the outermost samples confirms sinking particulate organic matter as the dominant carbon source and suggests a link between the deep-sea and surface ocean. There was a high degree of reproducibility found between multiple discs cut from the base of each specimen, as well as within duplicate subsamples. Robust 14C-derived chronologies and known surface ocean 14C reservoir age constraints in the Gulf of Mexico provided reliable calendar ages with future application to the development of proxy records.

  1. 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.

  2. 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.

  3. Towards a global understanding of vertical soil carbon dynamics: meta-analysis of soil 14C data

    NASA Astrophysics Data System (ADS)

    hatte, C.; Balesdent, J.; Guiot, J.

    2012-12-01

    Soil represents the largest terrestrial storage mechanism for atmospheric carbon from photosynthesis, with estimates ranging from 1600 Pg C within the top 1 meter to 2350 Pg C for the top 3 meters. These values are at least 2.5 times greater than atmospheric C pools. Small changes in soil organic carbon storage could result in feedback to atmospheric CO2 and the sensitivity of soil organic matter to changes in temperature, and precipitation remains a critical area of research with respect to the global carbon cycle. As an intermediate storage mechanism for organic material through time, the vertical profile of carbon generally shows an age continuum with depth. Radiocarbon provides critical information for understanding carbon exchanges between soils and atmosphere, and within soil layers. Natural and "bomb" radiocarbon has been used to demonstrate the importance and nature of the soil carbon response to climatic and human impacts on decadal to millennial timescales. Radiocarbon signatures of bulk, or chemically or physically fractionated soil, or even of specific organic compounds, offer one of the only ways to infer terrestrial carbon turnover times or test ecosystem carbon models. We compiled data from the literature on radiocarbon distribution on soil profiles and characterized each study according to the following categories: soil type, analyzed organic fraction, location (latitude, longitude, elevation), climate (temperature, precipitation), land use and sampling year. Based on the compiled data, soil carbon 14C profiles were reconstructed for each of the 226 sites. We report here partial results obtained by statistical analyses of portion of this database, i.e. bulk and bulk-like organic matter and sampling year posterior to 1980. We highlight here 14C vertical pattern in relationship with external parameters (climate, location and land use).

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

    SciTech Connect

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

    1993-03-01

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

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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).

  10. 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.

  11. 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.

  12. 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

  13. {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.

  14. 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.

  15. 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

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. ( 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.

  1. Reservoir Technology

    SciTech Connect

    Renner, J.L.

    1992-03-24

    The reservoir technology program supports the utilization of geothermal resources through development and verification of new earth science technologies for: exploration, fluid production and injection; and prediction of reservoir lifetimes. A two-fold strategy of conducting DOE-sponsored research to meet higher-risk, longer-term needs and cost-shared research with industry in areas of greatest current need is utilized to maximize the benefit of the program to the geothermal industry. The program uses a coordinated, multi-disciplinary approach to investigating and solving reservoir problems facing the industry. Research at The Geysers geothermal field has received major emphasis in the past three years. Recent progress in that work will be reviewed in detail by The Geysers operators, federal, state and local regulators and other interested parties during a meeting in Santa Rosa on May 5 and 6, 1992. Hence the papers by Lipman, Bodvarsson et al., Wannamaker, et al., Horne, and Shook in this proceedings volume emphasize non-Geysers research in the program.

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

    NASA Astrophysics Data System (ADS)

    Johnson, L.; Komada, T.

    2010-12-01

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

  3. 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.

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

    SciTech Connect

    Gordon, R.; Maclachlan, G. )

    1989-09-01

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

  5. Kernel abortion in maize. II. Distribution of /sup 14/C among kernel carboydrates

    SciTech Connect

    Hanft, J.M.; Jones, R.J.

    1986-06-01

    This study was designed to compare the uptake and distribution of /sup 14/C among fructose, glucose, sucrose, and starch in the cob, pedicel, and endosperm tissues of maize (Zea mays L.) kernels induced to abort by high temperature with those that develop normally. Kernels cultured in vitro at 309 and 35/sup 0/C were transferred to (/sup 14/C)sucrose media 10 days after pollination. Kernels cultured at 35/sup 0/C aborted prior to the onset of linear dry matter accumulation. Significant uptake into the cob, pedicel, and endosperm of radioactivity associated with the soluble and starch fractions of the tissues was detected after 24 hours in culture on atlageled media. After 8 days in culture on (/sup 14/C)sucrose media, 48 and 40% of the radioactivity associated with the cob carbohydrates was found in the reducing sugars at 30 and 35/sup 0/C, respectively. Of the total carbohydrates, a higher percentage of label was associated with sucrose and lower percentage with fructose and glucose in pedicel tissue of kernels cultured at 35/sup 0/C compared to kernels cultured at 30/sup 0/C. These results indicate that sucrose was not cleaved to fructose and glucose as rapidly during the unloading process in the pedicel of kernels induced to abort by high temperature. Kernels cultured at 35/sup 0/C had a much lower proportion of label associated with endosperm starch (29%) than did kernels cultured at 30/sup 0/C (89%). Kernels cultured at 35/sup 0/C had a correspondingly higher proportion of /sup 14/C in endosperm fructose, glucose, and sucrose.

  6. 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

  7. 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

  8. 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.

  9. Accuracy and precision of 14C-based source apportionment of organic and elemental carbon in aerosols using the Swiss_4S protocol

    NASA Astrophysics Data System (ADS)

    Mouteva, G. O.; Fahrni, S. M.; Santos, G. M.; Randerson, J. T.; Zhang, Y.-L.; Szidat, S.; Czimczik, C. I.

    2015-09-01

    Aerosol source apportionment remains a critical challenge for understanding the transport and aging of aerosols, as well as for developing successful air pollution mitigation strategies. The contributions of fossil and non-fossil sources to organic carbon (OC) and elemental carbon (EC) in carbonaceous aerosols can be quantified by measuring the radiocarbon (14C) content of each carbon fraction. However, the use of 14C in studying OC and EC has been limited by technical challenges related to the physical separation of the two fractions and small sample sizes. There is no common procedure for OC/EC 14C analysis, and uncertainty studies have largely focused on the precision of yields. Here, we quantified the uncertainty in 14C measurement of aerosols associated with the isolation and analysis of each carbon fraction with the Swiss_4S thermal-optical analysis (TOA) protocol. We used an OC/EC analyzer (Sunset Laboratory Inc., OR, USA) coupled to a vacuum line to separate the two components. Each fraction was thermally desorbed and converted to carbon dioxide (CO2) in pure oxygen (O2). On average, 91 % of the evolving CO2 was then cryogenically trapped on the vacuum line, reduced to filamentous graphite, and measured for its 14C content via accelerator mass spectrometry (AMS). To test the accuracy of our setup, we quantified the total amount of extraneous carbon introduced during the TOA sample processing and graphitization as the sum of modern and fossil (14C-depleted) carbon introduced during the analysis of fossil reference materials (adipic acid for OC and coal for EC) and contemporary standards (oxalic acid for OC and rice char for EC) as a function of sample size. We further tested our methodology by analyzing five ambient airborne particulate matter (PM2.5) samples with a range of OC and EC concentrations and 14C contents in an interlaboratory comparison. The total modern and fossil carbon blanks of our setup were 0.8 ± 0.4 and 0.67 ± 0.34 μg C, respectively

  10. Accuracy and precision of 14C-based source apportionment of organic and elemental carbon in aerosols using the Swiss_4S protocol

    NASA Astrophysics Data System (ADS)

    Mouteva, G. O.; Fahrni, S. M.; Santos, G. M.; Randerson, J. T.; Zhang, Y. L.; Szidat, S.; Czimczik, C. I.

    2015-04-01

    Aerosol source apportionment remains a critical challenge for understanding the transport and aging of aerosols, as well as for developing successful air pollution mitigation strategies. The contributions of fossil and non-fossil sources to organic carbon (OC) and elemental carbon (EC) in carbonaceous aerosols can be quantified by measuring the radiocarbon (14C) content of each carbon fraction. However, the use of 14C in studying OC and EC has been limited by technical challenges related to the physical separation of the two fractions and small sample sizes. There is no common procedure for OC/EC 14C analysis, and uncertainty studies have largely focused on the precision of yields. Here, we quantified the uncertainty in 14C measurement of aerosols associated with the isolation and analysis of each carbon fraction with the Swiss_4S thermal-optical analysis (TOA) protocol. We used an OC/EC analyzer (Sunset Laboratory Inc., OR, USA) coupled to vacuum line to separate the two components. Each fraction was thermally desorbed and converted to carbon dioxide (CO2) in pure oxygen (O2). On average 91% of the evolving CO2 was then cryogenically trapped on the vacuum line, reduced to filamentous graphite, and measured for its 14C content via accelerator mass spectrometry (AMS). To test the accuracy of our set-up, we quantified the total amount of extraneous carbon introduced during the TOA sample processing and graphitization as the sum of modern and fossil (14C-depleted) carbon introduced during the analysis of fossil reference materials (adipic acid for OC and coal for EC) and contemporary standards (oxalic acid for OC and rice char for EC) as a function of sample size. We further tested our methodology by analyzing five ambient airborne particulate matter (PM2.5) samples with a range of OC and EC concentrations and 14C contents in an interlaboratory comparison. The total modern and fossil carbon blanks of our set-up were 0.8 ± 0.4 and 0.67 ± 0.34 μg C, respectively

  11. 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

  12. 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

  13. 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

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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

  3. 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.

  4. 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.

  5. 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),