Science.gov

Sample records for airborne carbon 14c

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

    PubMed Central

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

    1978-01-01

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

  2. Carbonate as sputter target material for rapid 14C AMS

    NASA Astrophysics Data System (ADS)

    Longworth, Brett E.; Robinson, Laura F.; Roberts, Mark L.; Beaupre, Steven R.; Burke, Andrea; Jenkins, William J.

    2013-01-01

    This paper describes a technique for measuring the 14C content of carbonate samples by producing C- ions directly in the negative ion sputter source of an accelerator mass spectrometer (AMS) system. This direct analysis of carbonate material eliminates the time and expense of graphite preparation. Powdered carbonate is mixed with titanium powder, loaded into a target cartridge, and compressed. Beam currents for optimally-sized carbonate targets (0.09-0.15 mg C) are typically 10-20% of those produced by optimally-sized graphite targets (0.5-1 mg C). Modern (>0.8 Fm) samples run by this method have standard deviations of 0.009 Fm or less, and near-modern samples run as unknowns agree with values from traditional hydrolysis/graphite to better than 2%. Targets with as little as 0.06 mg carbonate produce useable ion currents and results, albeit with increased error and larger blank. In its current state, direct sputtering is best applied to problems where a large number of analyses with lower precision are required. These applications could include age surveys of deep-sea corals for determination of historic population dynamics, to identify samples that would benefit from high precision analysis, and for growth rate studies of organisms forming carbonate skeletons.

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

    NASA Astrophysics Data System (ADS)

    Michalska, Danuta; Czernik, Justyna

    2015-10-01

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

  4. Constraining carbon sources and growth rates of freshwater microbialites in Pavilion Lake using (14)C analysis.

    PubMed

    Brady, A L; Slater, G; Laval, B; Lim, D S

    2009-12-01

    This study determined the natural abundance isotopic compositions ((13)C, (14)C) of the primary carbon pools and microbial communities associated with modern freshwater microbialites located in Pavilion Lake, British Columbia, Canada. The Delta(14)C of dissolved inorganic carbon (DIC) was constant throughout the water column and consistent with a primarily atmospheric source. Observed depletions in DIC (14)C values compared with atmospheric CO(2) indicated effects due either to DIC residence time and/or inputs of (14)C-depleted groundwater. Mass balance comparisons of local and regional groundwater indicate that groundwater DIC could contribute a maximum of 9-13% of the DIC. (14)C analysis of microbial phospholipid fatty acids from microbialite communities had Delta(14)C values comparable with lake water DIC, demonstrating that lake water DIC was their primary carbon source. Microbialite carbonate was also primarily derived from DIC. However, some depletion in microbialite carbonate (14)C relative to lake water DIC occurred, due either to residence time or mixing with a (14)C-depleted carbon source. A detrital branch covered with microbialite growth was used to estimate a microbialite growth rate of 0.05 mm year(-1) for the past 1000 years, faster than previous estimates for this system. These results demonstrate that the microbialites are actively growing and that the primary carbon source for both microbial communities and recent carbonate is DIC originating from the atmosphere. While these data cannot conclusively differentiate between abiotic and biotic formation mechanisms, the evidence for minor inputs of groundwater-derived DIC is consistent with the previously hypothesized biological origin of the Pavilion Lake microbialites.

  5. Short organic carbon turnover time and narrow 14C age spectra in early Holocene wetland paleosols

    NASA Astrophysics Data System (ADS)

    Vetter, Lael; Rosenheim, Brad E.; Fernandez, Alvaro; Törnqvist, Torbjörn E.

    2017-01-01

    Paleosols contain information about the rates of soil organic carbon turnover when the soil was actively forming. However, this temporal information is often difficult to interpret without tight stratigraphic control on the age of the paleosol. Here we apply ramped pyrolysis/oxidation (Ramped PyrOx) 14C analyses to evaluate age spectra of transgressive early Holocene paleosols from the Mississippi Delta in southeastern Louisiana, USA. We find 14C age spectra from soil organic matter (SOM) in both paleosols and overlying basal peats that represent variability in age that is close to, or only slightly greater than, analytical uncertainty of 14C measurements, despite different sources of carbon with likely disparate ages. Such age spectra have not previously been observed in the sedimentary record. Here they indicate vigorous soil carbon turnover prior to burial, which homogenized 14C ages within SOM across the entire thermochemical spectrum. The weighted bulk 14C ages from Ramped PyrOx of paleosols and overlying peats are identical within analytical and process-associated uncertainty, and corroborate 14C ages from charcoal fragments and plant macrofossils from the overlying peat. The youngest ages from Ramped PyrOx age spectra may also potentially be applied as chronometers for stratigraphic burial ages. Our results suggest rapid turnover (≪300 years) of carbon in these soils relative to input of allochthonous carbon, indicating that the 14C age of different soil components is decoupled from thermochemical stability and instead reflects vigorous turnover processes. The concurrence of paleosol and peat 14C ages also suggests that pedogenic processes were linked with the development of coastal marshes, and that the priming effect potentially masked the signal of allochthonous carbon inputs during sea level rise.

  6. 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

  7. Suitability of biogenic carbonate of Lithospermum fruits for 14C dating

    NASA Astrophysics Data System (ADS)

    Pustovoytov, Konstantin; Riehl, Simone

    2006-05-01

    Lithospermum (Boraginaceae) belongs to a small group of plant taxa that accumulate biogenic carbonate in their fruits. In this genus, carbonate incrustations form in the cells of the epidermis and sclerenchyma of the pericarp. Fossil Lithospermum fruits (nutlets) with well-preserved calcified tissues commonly occur in Quaternary sediments and cultural layers. We tested the suitability of biogenic carbonate of Lithospermum fruits for radiocarbon dating using a total of 15 AMS measurement results from four modern and 11 fossil samples. The 14C data from modern samples suggest that Lithospermum utilises only atmospheric carbon to synthesise calcite in the nutlets. In general, the ages determined through 14C dating of fossil fruitscorresponded well with the absolute-age intervals for archaeological sites over the last 5000 yr. Biogenic carbonate of Lithospermum fruits, like that of Celtis, represents a new source of chronological information for late Quaternary studies.

  8. [Quantifying soil autotrophic microbes-assimilated carbon input into soil organic carbon pools following continuous 14C labeling].

    PubMed

    Shi, Ran; Chen, Xiao-Juan; Wu, Xiao-Hong; Jian, Yan; Yuan, Hong-Zhao; Ge, Ti-Da; Sui, Fang-Gong; Tong, Cheng-Li; Wu, Jin-Shui

    2013-07-01

    Soil autotrophic microbe has been found numerous and widespread. However, roles of microbial autotrophic processes and the mechanisms of that in the soil carbon sequestration remain poorly understood. Here, we used soils incubated for 110 days in a closed, continuously labeled 14C-CO2 atmosphere to measure the amount of labeled C incorporated into the microbial biomass. The allocation of 14C-labeled assimilated carbon in variable soil C pools such as dissolved organic C (DOC) and microbial biomass C (MBC) were also examined over the 14C labeling span. The results showed that significant amounts of 14C-SOC were measured in paddy soils, which ranged from 69.06-133.81 mg x kg(-1), accounting for 0.58% to 0.92% of the total soil organic carbon (SOC). The amounts of 14C in the dissolved organic C (14C-DOC) and in the microbial biomass C (14C-MBC) were dependent on the soils, ranged from 2.54 to 8.10 mg x kg(-1), 19.50 to 49.16 mg x kg(-1), respectively. There was a significantly positive linear relationship between concentrations of 14C-SOC and 14C-MBC (R2 = 0.957**, P < 0.01). The 14C-DOC and 14C-MBC as proportions of total DOC, MBC, were 5.65%-24.91% and 4.23%-20.02%, respectively. Moreover, the distribution and transformation of microbes-assimilated-derived C had a greater influence on the dynamics of DOC and MBC than that on the dynamics of SOC. These data provide new insights into the importance of microorganisms in the fixation of atmospheric CO2 and of the potentially significant contributions made by microbial autotrophy to terrestrial C cycling.

  9. Black carbon decomposition during 7 years and its transformation in soil estimated by 14C labeling

    NASA Astrophysics Data System (ADS)

    Kuzyakov, Y.; Bogomolova, I.; Glaser, B.

    2012-04-01

    Incomplete combustion of organics (vegetation or fossil fuel) led to accumulation of charred products in soils. Such charred products, frequently called black carbon (BC), may act as an important long-term carbon (C) sink because its microbial decomposition and chemical transformation is very slow. There are no studies with direct estimations of BC decomposition rates and its transformation in soil. We produced BC by charring 14C labeled residues of perennial ryegrass and incubated this 14C labeled BC in a Haplic Luvisol or in loess. The decomposition rates of BC were estimated based on 14CO2 sampled 55 times during the 7-years incubation period. The decomposition rates of BC calculated based on 14C in CO2 were similar in soil and in loess and were about 10-5 d-1 (=10-3 % d-1). This corresponds to a decomposition of about 0.3% BC a-1 under optimal conditions. Considering about 10 times slower decomposition of BC under natural conditions, the mean residence time of BC is about 2000 years. Three years after the incubation start, we traced the BC transformation in soil by 14C incorporation into microbial biomass, DOC, PLFA, sugars, neutral lipids, glycolipids, sugars and benzene polycarboxylic acids. The most 14C (>80%) remained in benzene polycarboxylic acids confirming very high stability of BC. Incorporation of BC-14C into microbial biomass, DOC and PLFA was less than 0.5%. We conclude that despite very high stability of BC and very slow process rates, the application of 14C labeling opens new ways for very sensitive tracing of BC transformation products in released CO2, microbial biomass, DOC, and SOM pools with various properties.

  10. Decomposition and transformation of 14C labeled black carbon in soil

    NASA Astrophysics Data System (ADS)

    Kuzyakov, K.; Bogomolova, I.; Glaser, B.

    2012-04-01

    Incomplete combustion of organics (vegetation or fossil fuel) led to accumulation of charred products in soils. Such charred products, frequently called black carbon (BC), may act as an important long-term carbon (C) sink because its microbial decomposition and chemical transformation is very slow. There are no studies with direct estimations of BC decomposition rates and its transformation in soil. We produced BC by charring 14C labeled residues of perennial ryegrass and incubated this 14C labeled BC in a Haplic Luvisol or in loess. The decomposition rates of BC were estimated based on 14CO2 sampled 55 times during the 7-years incubation period. The decomposition rates of BC calculated based on 14C in CO2 were similar in soil and in loess and were about 10-5 d-1 (=10-3 % d-1). This corresponds to a decomposition of about 0.3% BC a-1 under optimal conditions. Considering about 10 times slower decomposition of BC under natural conditions, the mean residence time of BC is about 2000 years. Three years after the incubation start, we traced the BC transformation in soil by 14C incorporation into microbial biomass, DOC, PLFA, sugars, neutral lipids, glycolipids, sugars and benzene polycarboxylic acids. The most 14C (>80%) remained in benzene polycarboxylic acids confirming very high stability of BC. Incorporation of BC-14C into microbial biomass, DOC and PLFA was less than 0.5%. We conclude that despite very high stability of BC and very slow process rates, the application of 14C labeling opens new ways for very sensitive tracing of BC transformation products in released CO2, microbial biomass, DOC, and SOM pools with various properties.

  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. Source and age of carbon in peatland surface waters: new insights from 14C analysis

    NASA Astrophysics Data System (ADS)

    Billett, Michael; Garnett, Mark; Dinsmore, Kerry; Leith, Fraser

    2013-04-01

    Peatlands are a significant source of carbon to the aquatic environment which is increasingly being recognised as an important flux pathway (both lateral and vertical) in total landscape carbon budgets. Determining the source and age of the carbon (in its various forms) is a key step to understanding the stability of peatland systems as well as the connectivity between the soil carbon pool and the freshwater environment. Novel analytical and sampling methods using molecular sieves have been developed for (1) within-stream, in situ sampling of CO2 in the field and (2) for the removal/separation of CO2 in the laboratory prior to 14C analysis of CH4. Here we present dual isotope (δ13C and 14C) data from freshwater systems in UK and Finnish peatlands to show that significant differences exist in the source and age of CO2, DOC (dissolved organic carbon) and POC (particulate organic carbon). Individual peatlands clearly differ in terms of their isotopic freshwater signature, suggesting that carbon cycling may be "tighter" in some systems compared to others. We have also measured the isotopic signature of different C species in peatland pipes, which appear to be able to tap carbon from different peat depths. This suggests that carbon cycling and transport within "piped-peatlands" may be more complex than previously thought. Some of our most recent work has focussed on the development of a method to measure the 14C component of CH4 in freshwaters. Initial results suggest that CH4 in peatland streams is significantly older than CO2 and derived from a much deeper source. We have also shown that the age (but not the source) of dissolved CO2 changes over the hydrological year in response to seasonal changes in discharge and temperature. Radiocarbon measurements in the peat-riparian-stream system suggest that a significant degree of connectivity exists in terms of C transport and cycling, although the degree of connectivity differs for individual C species. In summary, 14C

  13. 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.

  14. 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

  15. Impact of activated carbon on the catabolism of (14)C-phenanthrene in soil.

    PubMed

    Oyelami, Ayodeji O; Ogbonnaya, Uchenna; Muotoh, Chitom; Semple, Kirk T

    2015-06-01

    Activated carbon amendment to contaminated soil has been proposed as an alternative remediation strategy to the management of persistent organic pollutant in soils and sediments. The impact of varying concentrations (0%, 0.01%, 0.1% and 1.0%) of different types of AC on the development of phenanthrene catabolism in soil was investigated. Mineralisation of (14)C-phenanthrene was measured using respirometric assays. The increase in concentration of CB4, AQ5000 or CP1 in soil led to an increase in the length of the lag phases. Statistical analyses showed that the addition of increasing concentrations of AC to the soil significantly reduced (P < 0.05) the extent of (14)C-phenanthrene mineralisation. For example, for CB4-, AQ5000- and CP1-amended soils, the overall extent of (14)C-phenanthrene mineralisation reduced from 43.1% to 3.28%, 36.9% to 0.81% and 39.6% to 0.96%, respectively, after 120 days incubation. This study shows that the properties of AC, such as surface area, pore volume and particle size, are important factors in controlling the kinetics of (14)C-phenanthrene mineralisation in soil.

  16. 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.

  17. Depth distribution of soil organic carbon fractions and AMS 14C concentrations at different landscape positions

    NASA Astrophysics Data System (ADS)

    Dlugoß, V.; Fiener, P.; Schneider, K.

    2012-04-01

    On sloped arable land soil redistribution has a great impact on spatial patterns of soil organic carbon (SOC) stocks and on the lateral and vertical carbon fluxes between soil and atmosphere. While most studies focus on total SOC, the investigation of the impact of soil redistribution on SOC fractions and thus on different SOC quality can improve the knowledge about the processes controlling an erosion induced C sink or source. Some studies indicate that the labile SOC pool might be preferentially transported by water erosion, however others indicate that black carbon being considered as an inert pool is preferentially redistributed. Preferential erosion and/or deposition of specific SOC fractions must lead to a spatial differentiation of the SOC pool composition in areas prone to erosion. In this study we analysed differences in the depth distribution of particle-size SOC fractions and AMS 14C concentrations in relation to these fractions at different slope positions within an arable field in western Germany. Based on modelled soil redistribution, two soil profiles representing depositional, erosional and reference (with ignorable erosion or deposition) sites were analysed. Soil cores were taken to a maximum depth of 1.6 m and were divided into 0.05 m increments except for the actual tillage depth (0-0.15 m). For every second depth increment starting with the topsoil layer total SOC, particle-size SOC fractions and AMS 14C concentrations were determined. The fractionation scheme of Amelung et al. (1998) was applied resulting in three particulate organic carbon fractions (POC 1: 250 - 2000 µm, POC 2: 53-250 µm, POC 3: 20 -53 µm) and the remaining fine sized fraction (< 20 µm). Combining POC 1 and 2, which are often assumed to represent the labile carbon pool shows a decline of SOC in these fractions from reference to erosional to depositional sites. This indicates (i) a preferential detachment of these fractions at erosional sites, while (ii) the more

  18. Optimizing isolation protocol of organic carbon and elemental carbon for 14C analysis using fine particulate samples

    NASA Astrophysics Data System (ADS)

    Liu, Junwen; Li, Jun; Ding, Ping; Zhang, Yanlin; Liu, Di; Shen, Chengde; Zhang, Gan

    2017-04-01

    Radiocarbon (14C) analysis is a unique tool that can be used to directly apportion organic carbon (OC) and elemental carbon (EC) into fossil and non-fossil fractions. In this study, a coupled carbon analyzer and high-vacuum setup was established to collect atmospheric OC and EC. We thoroughly investigated the correlations between 14C levels and mass recoveries of OC and EC using urban PM2.5 samples collected from a city in central China and found that: (1) the 14C signal of the OC fraction collected in the helium phase of the EUSSAR_2 protocol (200 °C for 120 s, 300 °C for 150 s, 450 °C for 180 s, and 650 °C for 180 s) was representative of the entire OC fraction, with a relative error of approximately 6%, and (2) after thermal treatments of 120 s at 200 °C, 150 s at 300 °C, and 180 s at 475 °C in an oxidative atmosphere (10% oxygen, 90% helium) and 180 s at 650 °C in helium, the remaining EC fraction sufficiently represented the 14C level of the entire EC, with a relative error of <10%. The average recovery of the OC and EC fractions for 14C analysis was 64± 7% (n = 5) and 87 ± 5% (n = 5), respectively. The fraction of modern carbon in the OC and EC of reference material (RM) 8785 was 0.564 ± 0.013 and 0.238 ± 0.006, respectively. Analysis of 14C levels in four selected PM2.5 samples in Xinxiang, China revealed that the relative contribution of fossil sources in OC and EC in the PM2.5 samples were 50.5± 5.8% and 81.4± 2.6%, respectively, which are comparable to findings in previous studies conducted in other Chinese cities. We confirmed that most urban EC derives from fossil fuel combustion processes, whereas both fossil and non-fossil sources have comparable and important impacts on OC. Our results suggested that water-soluble organic carbon (WSOC) and its pyrolytic carbon can be completely removed before EC collection via the method employed in this study.

  19. 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.

  20. 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.

  1. 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

  2. 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

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

    USGS Publications Warehouse

    Han, Liang-Feng; Plummer, L. Niel

    2013-01-01

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

  5. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  7. A novel 14C approach to follow fate of carbon in organic soils

    NASA Astrophysics Data System (ADS)

    Biasi, C.; Tavi, N. M.; Oinonen, M.; Kukkonen, J.; Platner, C.; Juutilainen, J.; Martikainen, P.

    2012-04-01

    Soils contain globally about 1500 Gt of organic carbon (C), and are thus the largest reservoir of C in terrestrial ecosystems. Separating variable sources (e.g. plant-derived and soil-derived sources) releasing carbon dioxide (CO2) from soil is challenging, but important for better understanding and predicting how different components with variable stability and turnover times will respond to climate and land-use change. To date, the non-destructive isotopic methods (e.g. C3 to C4 transitions) seem to be most reliable in partitioning CO2 derived from the various sources. However, relatively little data are available for the C-rich peat soils dominating in the northern latitudes which store a great amount (about 30%) of the global soil. A reason is that C4 plants are absent in the cold regions. We introduce here a novel approach to follow the fate of old, native vs. young plant-derived C in a highly organic soil (Biasi et al., 2011). Our innovation is to use plant cultivations on peat soil where the upper peat layers have been removed (cut-away peatland). There, the plants have a modern 14C signature and the left-over peat is old (about 7500 years old in our study), being thus naturally depleted in 14C. This large difference in age offers an ideal and unique possibility for separating CO2 released from decomposition of native organic soil and plant-derived recent sources. Large and uniform differences in isotopic signals between plants and soil are rare, but needed for reliably quantifying the contribution of CO2 derived from each source by isotope partitioning approaches. By dating CO2 derived from soil respiration over two growing seasons, we showed from a perennial bioenergy crop (reed canary grass) cultivation in Finland, as an example, that old peat decomposition contributed less to total soil respiration than respiration of recent plant material (30% vs. 70% on average, respectively). The relative proportions of old vs. young C respired from soils were

  8. Natural abundance 13C and 14C analysis of water-soluble organic carbon in atmospheric aerosols.

    PubMed

    Kirillova, Elena N; Sheesley, Rebecca J; Andersson, August; Gustafsson, Örjan

    2010-10-01

    Water-soluble organic carbon (WSOC) constitutes a large fraction of climate-forcing organic aerosols in the atmosphere, yet the sources of WSOC are poorly constrained. A method was developed to measure the stable carbon isotope (δ(13)C) and radiocarbon (Δ(14)C) composition of WSOC for apportionment between fossil fuel and different biogenic sources. Synthetic WSOC test substances and ambient aerosols were employed to investigate the effect of both modern and fossil carbon contamination and any method-induced isotope fractionation. The method includes extraction of aerosols collected on quartz filters followed by purification and preparation for off-line δ(13)C and Δ(14)C determination. The preparative freeze-drying step for isotope analysis yielded recoveries of only ∼70% for ambient aerosols and WSOC probes. However, the δ(13)C of the WSOC isolates were in agreement with the δ(13)C of the unprocessed starting material, even for the volatile oxalic acid probe (6.59 ± 0.37‰ vs 6.33 ± 0.31‰; 2 sd). A (14)C-fossil phthalic acid WSOC probe returned a fraction modern biomass of <0.008 whereas a (14)C-modern sucrose standard yielded a fraction modern of >0.999, indicating the Δ(14)C-WSOC method to be free of both fossil and contemporary carbon contamination. Application of the δ(13)C/Δ(14)C-WSOC method to source apportion climate-affecting aerosols was illustrated be constraining that WSOC in ambient Stockholm aerosols were 88% of contemporary biogenic C3 plant origin.

  9. 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

  10. Coprecipitation of (14)C and Sr with carbonate precipitates: The importance of reaction kinetics and recrystallization pathways.

    PubMed

    Hodkin, David J; Stewart, Douglas I; Graham, James T; Burke, Ian T

    2016-08-15

    This study investigated the simultaneous removal of Sr(2+) and (14)CO3(2-) from pH>12 Ca(OH)2 solution by the precipitation of calcium carbonate. Initial Ca(2+):CO3(2-) ratios ranged from 10:1 to 10:100 (mM:mM). Maximum removal of (14)C and Sr(2+) both occurred in the system containing 10mM Ca(2+) and 1mM CO3(2-) (99.7% and 98.6% removal respectively). A kinetic model is provided that describes (14)C and Sr removal in terms of mineral dissolution and precipitation reactions. The removal of (14)C was achieved during the depletion of the initial TIC in solution, and was subsequently significantly affected by recrystallization of the calcite precipitate from an elongate to isotropic morphology. This liberated >46% of the (14)C back to solution. Sr(2+) removal occurred as Ca(2+) became depleted in solution and was not significantly affected by the recrystallization process. The proposed reaction could form the basis for low cost remediation scheme for (90)Sr and (14)C in radioactively contaminated waters (<$0.25 reagent cost per m(3) treated).

  11. 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

  12. A study of the carbon dynamics of Japanese grassland and forest using 14C and 13C

    NASA Astrophysics Data System (ADS)

    Katsuno, Kazumi; Miyairi, Yosuke; Tamura, Kenji; Matsuzaki, Hiroyuki; Fukuda, Kenji

    2010-04-01

    We quantified the carbon contents of grassland and forest soil using conventional methods and studied the changes in their dynamics by measuring δ 13C and Δ 14C. Soil samples were taken from a neighboring Miscanthus sinensis grassland and Pinus densiflora forest in central Japan. Both had been maintained as grassland until the 1960s, when the latter was abandoned and became a pine forest by natural succession. The soil carbon content of the forest was much lower than that of the grassland, implying that the soil carbon decreased as the grassland became forest. The δ 13C values were very similar in the grassland and forest, at approximately -20‰, suggesting that M. sinensis (a C4 plant) contributed to carbon storage, whereas there was little carbon accumulation from P. densiflora (a C3 plant) in forest soil. The Δ 14C values and calculated soil carbon mean residence time (MRT) showed that the soil carbon in the upper A horizon was older, and that in the lower A horizon was younger in forest than in grassland. From these results, we conclude that young, fast-MRT soil carbon is decomposed in the upper A horizon, and old, stable soil carbon was decomposed in the lower A horizon after the pine invasion.

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

    USGS Publications Warehouse

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

    2011-01-01

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

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

    USGS Publications Warehouse

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

    2011-01-01

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

  15. Simulation of carbon cycling, including dissolved organic carbon transport, in forest soil locally enriched with 14C

    SciTech Connect

    Tipping, Ed; Chamberlain, Paul M.; Froberg, Mats J.; Hanson, Paul J; Jardine, Philip M

    2012-01-01

    The DyDOC model was used to simulate organic matter decomposition and dissolved organic matter (DOM) transport in deciduous forest soils at the Oak Ridge Reservation (ORR) in Tennessee, USA. The model application relied on extensive data from the Enriched Background Isotope study (EBIS), which made use of a local atmospheric enrichment of radiocarbon to establish a large-scale manipulation experiment with different inputs of 14C from both above-ground and below-ground litter. The aim of the modelling was to test if the processes that constitute DyDOC can explain the available observations for C dynamics in the ORR. More specifically we used the model to investigate the origins of DOM, its dynamics within the soil profile, and how it contributes to the formation of stable carbon in the mineral soil. The model was first configured to account for water transport through the soil, then observed pools and fluxes of carbon and 14C data were used to fit the model parameters that describe the rates of the metabolic transformations. The soils were described by a thin O-horizon, a 15 cm thick A-horizon and a 45-cm thick B-horizon. Within the thin O-horizon, litter is either converted to CO2 or to a second organic matter pool, which is converted to CO2 at a different rate, both pools being able to produce DOM. The best model performance was obtained by assuming that adsorption of downwardly transported DOM in horizons A and B, followed by further conversion to stable forms, produces mineral-associated carbon pools, while root litter is the source of non-mineral associated carbon, with relatively short residence times. In the simulated steady-state, most carbon entering the O-horizon leaves quickly as CO2, but 17% (46 gC m-2 a-1) is lost as DOC in percolating water. The DOM comprises mainly hydrophobic material, 40% being derived from litter and 60% from older organic matter pools (residence time ~ 10 years). Most of the DOM is converted to CO2 in the mineral soil, over

  16. Tracing source, mixing and uptaking processes of carbon in an epikarst spring-pond system in southeastern Guizhou of China by carbon isotopes (13C-14C)

    NASA Astrophysics Data System (ADS)

    Zhao, M.; Chen, B.; Liu, Z.; Li, H. C.; Yang, R.

    2015-12-01

    δ13C and Δ14C of dissolved inorganic carbon (DIC), particulate organic carbon (POC) and aquatic plants from a karst spring and two spring-fed ponds in Laqiao, Maolan County, Guizhou Province in January, July and October of 2013 were measured to understand the roles of aquatic photosynthesis through DIC uptake in karst surface waters. The mean Δ14C and δ13C values of DIC for the spring pool, midstream and downstream ponds are -60.6±26.3‰ and -13.53±1.97‰, -62.8±62.9‰ and -11.72±2.72‰, and -54.2±56.5‰ and -9.40±2.03‰, respectively. Both Δ14C and δ13C show seasonal variations, with lower Δ14C values but heavier δ13C values in dry season and vice versa in summer rainy season. This observation indicates that (1) the main carbon source of the spring DIC is from limestone bedrock dissolution and soil CO2 with higher contribution in summer due to higher productivity; and (2) 13C and 14C have different behaviors during DIC uptake by aquatic plants and during CO2 exchange between DIC and the atmospheric CO2. Biological uptake of CO2 will not affect the Δ14C of DIC, but lead to δ13CDIC enrichment. CO2 exchange between DIC and the atmospheric CO2 should elevate both the Δ14C and δ13C of DIC. In Laqiao spring-pond system, it seems that the effect of biological uptake on the Δ14C and δ13C of DIC is much stronger than that of CO2 exchange with the atmosphere. The mean Δ14C values of POC from the spring pool, midstream and downstream ponds are -308.1 ±64.3‰, -164.4±84.4‰ and -195.1±108.5‰, respectively, indicating mixture of aquatic algae and detrital particle (clay and dust). More aquatic algae were formed in the stream ponds especially in the summer. SEM results of the POC samples support this conclusion. Furthermore, the Δ14C values of the submerged aquatic plants range from -200.0‰ to -51.3 ‰ and were similar to those of the DIC, indicating that the aquatic plants used DIC for photosynthesis. The Δ14C value of an emergent plant

  17. Not all carbon dioxide degassed from Amazonian rivers is 14C-modern

    NASA Astrophysics Data System (ADS)

    Vihermaa, Leena; Waldron, Susan; Garnett, Mark; Newton, Jason

    2013-04-01

    Here we show that effluxed carbon dioxide in the Amazon basin may not always be from recent ecosystem derived release of carbon, but may be older, incorporating a maximum of 10% of 'fossil'-derived carbon or more of pre-1960 carbon. This is the first direct measurement of the age of effluxed carbon dioxide from the Amazon basin. Surprisingly 'old' efflux could be found in perennial first order rivers within forested landscapes. These drainage systems are not included routinely in upscaled carbon dioxide efflux budgets, and so are unlikely to also be included in global models of aquatic Amazonian response to changing climate. The source of this old carbon is either deep soils / trapped organic matter subsequently respired, or rock weathering. The former is important to consider as we know very little of the inheritance of a landscape and our understanding of the Amazon basin is one of rapid ecosystem-derived carbon cycling, rather than slow release from older reservoirs, other than where there has been anthropogenic-induced erosion. Deep organic soils are not prevalent in the Amazonian basin close to the study area, so the source of this old carbon is more likely to be from groundwater containing weathering-derived fossil carbon. Future projections of the importance of the Amazon as a global C sink focus largely on an ecosystem response to land use e.g. burning and clearing, or to acute meteorological events e.g. drought, so we must consider for accurate projection how important are older carbon sources in driving efflux.

  18. 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.

  19. The14C 'bomb' pulse in selected European stalagmites as a tracer of soil carbon cycling dynamics

    NASA Astrophysics Data System (ADS)

    Rudzka, D.; McDermott, F.

    2012-04-01

    The decomposition of soil organic matter (SOM) is temperature dependant, but its response to a future warmer climate remains equivocal. Enhanced rates of decomposition of SOM under increased global temperatures might cause higher CO2 emissions to the atmosphere, and could constitute a strong positive feedback. The magnitude of this feedback however remains poorly understood primarily because of the difficulty in quantifying the temperature sensitivity of stored, recalcitrant carbon that comprises the bulk (>90%) of SOM in most soils. In this study we investigated the effects of climate on soil carbon using the 'bomb' radiocarbon systematics of selected modern European speleothems. The 'bomb' 14C spike was used as a tracer of the accumulation and decomposition of SOM under different climatic settings. New time-series radiocarbon measurements were carried out, and the attenuation of the 'bomb' 14C spike was studied in three stalagmites and in one soda straw stalactite. The results were used to examine the quality of soil organic matter and carbon dynamics on decadal timescales under a range of soil conditions and different climatic regimes. These new data were combined with published results to further examine soil carbon transfer dynamics, and to explore the sensitivity of labile and recalcitrant organic matter decomposition to different climatic conditions. The initial radiocarbon activity from each speleothem was modelled using a three pool soil carbon inverse model (applying a Monte Carlo method) in order to investigate the soil carbon residence time and its turnover above the cave site. Sites that are characterised by high mean annual air temperatures (MAAT) and a high soil carbon storage capacity (e.g. overlain by thick soil cover with dense, well developed vegetation, such as La Garma, N. Spain and Sofular, Turkey) display the highest damping effect, and the oldest mean soil carbon ages (MSCA), with residence times of c. half a millennium. This suggests that

  20. Carbon nanotube translocation to distant organs after pulmonary exposure: insights from in situ (14)C-radiolabeling and tissue radioimaging.

    PubMed

    Czarny, Bertrand; Georgin, Dominique; Berthon, Fannely; Plastow, Gael; Pinault, Mathieu; Patriarche, Gilles; Thuleau, Aurélie; L'Hermite, Martine Mayne; Taran, Frédéric; Dive, Vincent

    2014-06-24

    Few approaches are available to investigate the potential of carbon nanotubes (CNTs) to translocate to distant organs following lung exposure, although this needs to be taken into account to evaluate potential CNT toxicity. Here, we report a method for quantitative analysis of the tissue biodistribution of multiwalled CNTs (MWCNTs) as a function of time. The method relies on the use of in situ (14)C-radiolabeled MWCNTs and combines radioimaging of organ tissue sections to ex vivo analysis of MWCNTs by electron microscopy. To illustrate the usefulness of this approach, mice were exposed to a single dose of 20 μg of (14)C-labeled MWCNTs by pharyngeal aspiration and were subjected to a follow-up study over one year. After administration, MWCNT were cleared from the lungs, but there was a concomitant relocation of these nanoparticles to distant organs starting throughout the follow-up period, with nanoparticle accumulation increasing with time. After one year, accumulation of MWCNTs was documented in several organs, including notably the white pulp of the spleen and the bone marrow. This study shows that the proposed method may be useful to complement other approaches to address unresolved toxicological issues associated with CNTs. These issues include their persistence over long periods in extrapulmonary organs, the relationship between the dose and the extent of translocation, and the effects of "safety by design" on those processes. The same approach could be used to study the translocation propensity of other nanoparticles containing carbon atoms.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  2. Dissolved Organic Carbon 14C in Southern Nevada Groundwater and Implications for Groundwater Travel Times

    SciTech Connect

    Hershey, Ronald L.; Fereday, Wyall; Thomas, James M

    2016-08-01

    Dissolved inorganic carbon (DIC) carbon-14 (14C) ages must be corrected for complex chemical and physical reactions and processes that change the amount of 14C in groundwater as it flows from recharge to downgradient areas. Because of these reactions, DIC 14C can produce unrealistically old ages and long groundwater travel times that may, or may not, agree with travel times estimated by other methods. Dissolved organic carbon (DOC) 14C ages are often younger than DIC 14C ages because there are few chemical reactions or physical processes that change the amount of DOC 14C in groundwater. However, there are several issues that create uncertainty in DOC 14C groundwater ages including limited knowledge of the initial (A0) DOC 14C in groundwater recharge and potential changes in DOC composition as water moves through an aquifer. This study examines these issues by quantifying A0 DOC 14C in recharge areas of southern Nevada groundwater flow systems and by evaluating changes in DOC composition as water flows from recharge areas to downgradient areas. The effect of these processes on DOC 14C groundwater ages is evaluated and DOC and DIC 14C ages are then compared along several southern Nevada groundwater flow paths. Twenty-seven groundwater samples were collected from springs and wells in southern Nevada in upgradient, midgradient, and downgradient locations. DOC 14C for upgradient samples ranged from 96 to 120 percent modern carbon (pmc) with an average of 106 pmc, verifying modern DOC 14C ages in recharge areas, which decreases uncertainty in DOC 14C A0 values, groundwater ages, and travel times. The HPLC spectra of groundwater along a flow path in the Spring Mountains show the same general pattern indicating that the DOC compound composition does not change along this flow path

  3. Hepatic albumin and urea synthesis: The mathematical modelling of the dynamics of [14C]carbonate-derived guanidine-labelled arginine in the isolated perfused rat liver.

    PubMed Central

    Tavill, A S; Nadkarni, D; Metcalfe, J; Black, E; Hoffenberg, R; Carson, E R

    1975-01-01

    A mathematical model was constructed to define the dynamics of incorporation of radioactivity into urea carbon and the guanidine carbon of arginine in plasma albumin after the rapid intraportal-venous administration of Na214CO3 in the isolated perfused rat liver. 2. The model was formulated in terms of compartmental analysis and additional experiments were designed to provide further information on subsystem dynamics and to discriminate between alternative model structures. 3. Evidence for the rapid-time-constant of labelling of intracellular arginine was provided by precursor-product analysis of precursor [14C]carboante and product [14C]urea in the perfusate. 4. Compartmental analysis of the dynamics of newly synthesized urea was based on the fate of exogenous [13C]urea, endogenous [14C]urea and the accumulation of [12C]urea in perfusate water, confirming the early completion of urea carbon labelling, the absence of continuing synthesis of labelled urea, and the presence of a small intrahepatic urea-delay pool. 5. Analysis of the perfusate dynamics of endogenously synthesized and exogenously administered [6-14C]arginine indicated that although the capacity for extrahepatic formation of [14C]-urea exists, little or no arginine formed within the intrahepatic urea cycle was transported out of the liver. However, the presence of a rapidly turning-over intrahepatic arginine pool was confirmed. 6. On the basis of these subsystem analyses it was possible to offer feasible estimations for the parameters of the mathematical model. However, it was not possible to stimulate the form and magnitude of the dynamics of newly synthesized labelled urea and albumin which were simultaneously observed after administration of [14C]carbonate on the basis of a preliminary model which postulated that both products were derived from a single hepatic pool of [16-14C]arginine. On the other hand these observed dynamics could be satisfied to a two-compartment arginine model, which also

  4. Biochar, activated carbon, and carbon nanotubes have different effects on fate of 14C-catechol and microbial community in soil

    PubMed Central

    Shan, Jun; Ji, Rong; Yu, Yongjie; Xie, Zubin; Yan, Xiaoyuan

    2015-01-01

    This study investigated the effects of biochar, activated carbon (AC)-, and single-walled and multi-walled carbon nanotubes (SWCNTs and MWCNTs) in various concentrations (0, 0.2, 20, and 2,000 mg/kg dry soil) on the fate of 14C-catechol and microbial community in soil. The results showed that biochar had no effect on the mineralization of 14C-catechol, whereas AC at all amendment rates and SWCNTs at 2,000 mg/kg significantly reduced mineralization. Particularly, MWCNTs at 0.2 mg/kg significantly stimulated mineralization compared with the control soil. The inhibitory effects of AC and SWCNTs on the mineralization were attributed to the inhibited soil microbial activities and the shifts in microbial communities, as suggested by the reduced microbial biomass C and the separated phylogenetic distance. In contrast, the stimulatory effects of MWCNTs on the mineralization were attributed to the selective stimulation of specific catechol-degraders by MWCNTs at 0.2 mg/kg. Only MWCNTs amendments and AC at 2,000 mg/kg significantly changed the distribution of 14C residues within the fractions of humic substances. Our findings suggest biochar, AC, SWCNTs and MWCNTs have different effects on the fate of 14C-catechol and microbial community in soil. PMID:26515132

  5. Biochar, activated carbon, and carbon nanotubes have different effects on fate of 14C-catechol and microbial community in soil

    NASA Astrophysics Data System (ADS)

    Shan, Jun; Ji, Rong; Yu, Yongjie; Xie, Zubin; Yan, Xiaoyuan

    2015-10-01

    This study investigated the effects of biochar, activated carbon (AC)-, and single-walled and multi-walled carbon nanotubes (SWCNTs and MWCNTs) in various concentrations (0, 0.2, 20, and 2,000 mg/kg dry soil) on the fate of 14C-catechol and microbial community in soil. The results showed that biochar had no effect on the mineralization of 14C-catechol, whereas AC at all amendment rates and SWCNTs at 2,000 mg/kg significantly reduced mineralization. Particularly, MWCNTs at 0.2 mg/kg significantly stimulated mineralization compared with the control soil. The inhibitory effects of AC and SWCNTs on the mineralization were attributed to the inhibited soil microbial activities and the shifts in microbial communities, as suggested by the reduced microbial biomass C and the separated phylogenetic distance. In contrast, the stimulatory effects of MWCNTs on the mineralization were attributed to the selective stimulation of specific catechol-degraders by MWCNTs at 0.2 mg/kg. Only MWCNTs amendments and AC at 2,000 mg/kg significantly changed the distribution of 14C residues within the fractions of humic substances. Our findings suggest biochar, AC, SWCNTs and MWCNTs have different effects on the fate of 14C-catechol and microbial community in soil.

  6. Biochar, activated carbon, and carbon nanotubes have different effects on fate of (14)C-catechol and microbial community in soil.

    PubMed

    Shan, Jun; Ji, Rong; Yu, Yongjie; Xie, Zubin; Yan, Xiaoyuan

    2015-10-30

    This study investigated the effects of biochar, activated carbon (AC)-, and single-walled and multi-walled carbon nanotubes (SWCNTs and MWCNTs) in various concentrations (0, 0.2, 20, and 2,000 mg/kg dry soil) on the fate of (14)C-catechol and microbial community in soil. The results showed that biochar had no effect on the mineralization of (14)C-catechol, whereas AC at all amendment rates and SWCNTs at 2,000 mg/kg significantly reduced mineralization. Particularly, MWCNTs at 0.2 mg/kg significantly stimulated mineralization compared with the control soil. The inhibitory effects of AC and SWCNTs on the mineralization were attributed to the inhibited soil microbial activities and the shifts in microbial communities, as suggested by the reduced microbial biomass C and the separated phylogenetic distance. In contrast, the stimulatory effects of MWCNTs on the mineralization were attributed to the selective stimulation of specific catechol-degraders by MWCNTs at 0.2 mg/kg. Only MWCNTs amendments and AC at 2,000 mg/kg significantly changed the distribution of (14)C residues within the fractions of humic substances. Our findings suggest biochar, AC, SWCNTs and MWCNTs have different effects on the fate of (14)C-catechol and microbial community in soil.

  7. Determination of microbial carbon sources and cycling during remediation of petroleum hydrocarbon impacted soil using natural abundance (14)C analysis of PLFA.

    PubMed

    Cowie, Benjamin R; Greenberg, Bruce M; Slater, Gregory F

    2010-04-01

    In a petroleum impacted land-farm soil in Sarnia, Ontario, compound-specific natural abundance radiocarbon analysis identified biodegradation by the soil microbial community as a major pathway for hydrocarbon removal in a novel remediation system. During remediation of contaminated soils by a plant growth promoting rhizobacteria enhanced phytoremediation system (PEPS), the measured Delta(14)C of phospholipid fatty acid (PLFA) biomarkers ranged from -793 per thousand to -897 per thousand, directly demonstrating microbial uptake and utilization of petroleum hydrocarbons (Delta(14)C(PHC) = -1000 per thousand). Isotopic mass balance indicated that more than 80% of microbial PLFA carbon was derived from petroleum hydrocarbons (PHC) and a maximum of 20% was obtained from metabolism of more modern carbon sources. These PLFA from the contaminated soils were the most (14)C-depleted biomarkers ever measured for an in situ environmental system, and this study demonstrated that the microbial community in this soil was subsisting primarily on petroleum hydrocarbons. In contrast, the microbial community in a nearby uncontaminated control soil maintained a more modern Delta(14)C signature than total organic carbon (Delta(14)C(PLFA) = +36 per thousand to -147 per thousand, Delta(14)C(TOC) = -148 per thousand), indicating preferential consumption of the most modern plant-derived fraction of soil organic carbon. Measurements of delta(13)C and Delta(14)C of soil CO(2) additionally demonstrated that mineralization of PHC contributed to soil CO(2) at the contaminated site. The CO(2) in the uncontaminated control soil exhibited substantially more modern Delta(14)C values, and lower soil CO(2) concentrations than the contaminated soils, suggesting increased rates of soil respiration in the contaminated soils. In combination, these results demonstrated that biodegradation in the soil microbial community was a primary pathway of petroleum hydrocarbon removal in the PEPS system. This study

  8. Multimolecular tracers of terrestrial carbon transfer across the pan-Arctic: 14C characteristics of sedimentary carbon components and their environmental controls

    NASA Astrophysics Data System (ADS)

    Feng, Xiaojuan; Gustafsson, Örjan; Holmes, R. Max; Vonk, Jorien E.; Dongen, Bart E.; Semiletov, Igor P.; Dudarev, Oleg V.; Yunker, Mark B.; Macdonald, Robie W.; Wacker, Lukas; Montluçon, Daniel B.; Eglinton, Timothy I.

    2015-11-01

    Distinguishing the sources, ages, and fate of various terrestrial organic carbon (OC) pools mobilized from heterogeneous Arctic landscapes is key to assessing climatic impacts on the fluvial release of carbon from permafrost. Through molecular 14C measurements, including novel analyses of suberin- and/or cutin-derived diacids (DAs) and hydroxy fatty acids (FAs), we compared the radiocarbon characteristics of a comprehensive suite of terrestrial markers (including plant wax lipids, cutin, suberin, lignin, and hydroxy phenols) in the sedimentary particles from nine major arctic and subarctic rivers in order to establish a benchmark assessment of the mobilization patterns of terrestrial OC pools across the pan-Arctic. Terrestrial lipids, including suberin-derived longer-chain DAs (C24,26,28), plant wax FAs (C24,26,28), and n-alkanes (C27,29,31), incorporated significant inputs of aged carbon, presumably from deeper soil horizons. Mobilization and translocation of these "old" terrestrial carbon components was dependent on nonlinear processes associated with permafrost distributions. By contrast, shorter-chain (C16,18) DAs and lignin phenols (as well as hydroxy phenols in rivers outside eastern Eurasian Arctic) were much more enriched in 14C, suggesting incorporation of relatively young carbon supplied by runoff processes from recent vegetation debris and surface layers. Furthermore, the radiocarbon content of terrestrial markers is heavily influenced by specific OC sources and degradation status. Overall, multitracer molecular 14C analysis sheds new light on the mobilization of terrestrial OC from arctic watersheds. Our findings of distinct ages for various terrestrial carbon components may aid in elucidating fate of different terrestrial OC pools in the face of increasing arctic permafrost thaw.

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

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

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

  10. Sources of Respired Carbon in a Northern Minnesota Ombrotrophic Spruce Bog: Preliminary 14C Results from the SPRUCE Site.

    NASA Astrophysics Data System (ADS)

    Guilderson, T. P.; McNicol, G.; Machin, A.; Hanson, P. J.; McFarlane, K. J.; Osuna, J. L.; Pett-Ridge, J.; Singleton, M. J.

    2014-12-01

    A significant uncertainty in future land-surface carbon budgets is the response of wetlands to climate change. A corollary and related question is the future net climate (radiative) forcing impact from wetlands. Active wetlands emit both CO2 and CH4 to the atmosphere. CH4 is, over a few decades, a much more potent greenhouse gas than CO2. CO2 has a longer atmospheric lifetime and a longer 'tail' to its radiative influence. Whether wetlands are a net source or sink of atmospheric carbon under future climate change will depend on ecosystem response to rising temperatures and elevated CO2. The largest uncertainty in future wetland C-budgets, and their climate forcing is the stability of the large below-ground carbon stocks, often in the form of peat, and the partitioning of CO2 and CH4 released via ecosystem respiration. In advance of a long-term experimental warming and elevated CO2 manipulation at the DOE Spruce and Peatland Responses Under Climatic and Environmental Change (SPRUCE) site in the Marcell Experimental Forest, we have characterized the source of respired carbon used for both the production of CO2 and CH4. Samples were collected in early June, late July, and will be collected in early September from three large (~1.1 m2, ~0.5m3) chambers from the control plot, and two of the experimental plots selected for heating (+9°C, +4.5°C). Early June fluxes from the three chambers were ~5500 mgC-m-2-d-1 and ~16 mgC-m-2-d-1 for CO2 and CH4 respectively. Radiocarbon analysis of CO2 and CH4 indicate that the source for the respired carbon is for the most part recent, with most 14C values between 30 and 40‰ - i.e., carbon that was photosynthetically fixed in the last few years. In concert with rising air and ground temperatures fluxes in late July increased to ~6500 mgC-m-2-d-1 and ~86 mgC-m-2-d-1. Although deep-heating was initiated in mid to late June we hypothesize that the July respiration signal is dominated by the regular seasonal cycle of natural warming

  11. Carbon cycling in primary production bottle incubations: inferences from grazing experiments and photosynthetic studies using 14C and 18O in the Arabian Sea

    NASA Astrophysics Data System (ADS)

    Laws, Edward A.; Landry, Michael R.; Barber, Richard T.; Campbell, Lisa; Dickson, Mary-Lynn; Marra, John

    Estimates of photosynthesis based on the incorporation of 14C-labeled inorganic carbon into particulate carbon were compared to estimates of gross photosynthesis based on net O 2 production and the production of 18O2 from H218O during the US Joint Global Ocean Flux Study (US JGOFS) Arabian Sea process cruises. For samples incubated below the surface and at optical depths<3, the 14C uptake : gross photosynthesis ratio averaged 0.45±0.1. This result is in accord with theoretical considerations of the combined effects of the Mehler reaction, photorespiration, dark respiration, excretion, and grazing effects on the two estimates of photosynthesis. The 14C uptake : gross photosynthesis ratio was distinctly higher (0.62) for samples incubated at the surface. This result is likely due to UV light effects, since the O 2 and 14C incubations were done in quartz and polysulfone bottles, respectively. The 14C uptake : gross photosynthesis ratio was lower (0.31) for bottles incubated at optical depths>3. This result probably reflects an increase in the ratio of dark respiration to net photosynthesis in the vicinity of the compensation light level.

  12. Concentration and 14C Content of Total Organic Carbon and Black Carbon in Small (<100 ug C) Samples from Low-Latitude Alpine Ice Cores

    NASA Astrophysics Data System (ADS)

    Kehrwald, N. M.; Czimczik, C. I.; Santos, G. M.; Thompson, L. G.; Ziolkowski, L.

    2008-12-01

    Many low latitude glaciers are receding with consequences for the regional energy budget and hydrology. Ice loss has been linked to climate change and the deposition of organic aerosols such as black carbon (BC) which is formed during incomplete combustion. Little is known about how the contents of BC and total organic carbon (TOC) in aerosols change over time and how anthropogenic activities (e.g. land-use change) impact this variability. Low-latitude ice cores are located closer to population centers than polar ice caps and can provide a regional synthesis of TOC and BC variability. Radiocarbon (14C) may be used to partition BC aerosols into fossil (>50 kyrs) and modern sources (e.g. fossil-fuels vs. wildfires). We quantified TOC, BC, and their 14C content in three low-latitude ice cores: Naimona'nyi (30°27'N, 81°91'E) and Dasuopu (28°23'N, 85°43'E), Tibet, and Quelccaya (13°56'S; 70°50'W), Peru. Aerosols (52-256 g ice on filters) were separated into TOC and BC using thermal oxidation (CTO- 375). 14C was measured by AMS. TOC contents were 0.11-0.87, 0.05-0.43, and 0.06-0.19 μg C (g ice) -1 for Naimona'nyi, Dasuopu, and Quelccaya, respectively. BC contents were 18±8, 27±4, and 29±12 %TOC. Procedural blanks were 0.8 ± 0.4 μg C (TOC) and 1.2 ± 0.6 μg C (BC). In ice cores well dated through annual layer counting and/or independent ages (e.g. volcanic horizons) such as Quelccaya, the ability to separate BC from TOC, as well as partition BC into fossil and modern contributions has potential for reconstructing pre- and post-industrial changes in aerosol composition and their impact on the energy budget.

  13. Carbon isotopic composition (δ(13)C and (14)C activity) of plant samples in the vicinity of the Slovene nuclear power plant.

    PubMed

    Sturm, Martina; Vreča, Polona; Krajcar Bronić, Ines

    2012-08-01

    δ(13)C values of various plants (apples, wheat, and maize) collected in the vicinity of the Krško Nuclear Power Plant (Slovenia) during 2008 and 2009 were determined. By measuring dried samples and their carbonized counterparts we showed that no significant isotopic fractionation occurs during the carbonization phase of the sample preparation process in the laboratory. The measured δ(13)C values of the plants were used for δ(13)C correction of their measured (14)C activities.

  14. Distribution and Biomarker of Carbon-14 Labeled Fullerene C60 ([14C(U)]C60) in Pregnant and Lactating Rats and their Offspring after Maternal Intravenous Exposure

    PubMed Central

    Snyder, Rodney W.; Fennell, Timothy R.; Wingard, Christopher J.; Mortensen, Ninell P.; Holland, Nathan A.; Shannahan, Jonathan H.; Pathmasiri, Wimal; Lewin, Anita H.; Sumner, Susan C. J.

    2015-01-01

    A comprehensive distribution study was conducted in pregnant and lactating rats exposed to a suspension of uniformly carbon-14 labeled C60 ([14C(U)]C60). Rats were administered [14C(U)]C60 (~0.2 mg [14C(U)]C60/kg body weight) or 5% polyvinylpyrrolidone (PVP)-saline vehicle via a single tail vein injection. Pregnant rats were injected on gestation day (GD) 11 (terminated with fetuses after either 24h or 8d), GD15 (terminated after 24h or 4d), or GD18 (terminated after 24h). Lactating rats were injected on postnatal day 8 and terminated after 24h, 3d or 11d. The distribution of radioactivity in pregnant dams was influenced by both the state of pregnancy and time of termination after exposure. The percentage of recovered radioactivity in pregnant and lactating rats was highest in liver and lungs. Radioactivity was quantitated in over 20 tissues. Radioactivity was found in placenta and in fetuses of pregnant dams, and in the milk of lactating rats and in pups. Elimination of radioactivity was <2% in urine and feces at each time point. Radioactivity remained in blood circulation up to 11 days after [14C(U)]C60 exposure. Biomarkers of inflammation, cardiovascular injury and oxidative stress were measured to study the biological impacts of [14C(U)]C60 exposure. Oxidative stress were elevated in female pups of exposed dams. Metabolomics analysis of urine showed that [14C(U)]C60 exposure to pregnant rats impacted the pathways of vitamin B, regulation of lipid and sugar metabolism and aminoacyl-tRNA biosynthesis. This study demonstrated that [14C(U)]C60 crosses the placenta at all stages of pregnancy examined, and is transferred to pups via milk. PMID:26081520

  15. Distribution and biomarker of carbon-14 labeled fullerene C60 ([(14) C(U)]C60 ) in pregnant and lactating rats and their offspring after maternal intravenous exposure.

    PubMed

    Snyder, Rodney W; Fennell, Timothy R; Wingard, Christopher J; Mortensen, Ninell P; Holland, Nathan A; Shannahan, Jonathan H; Pathmasiri, Wimal; Lewin, Anita H; Sumner, Susan C J

    2015-12-01

    A comprehensive distribution study was conducted in pregnant and lactating rats exposed to a suspension of uniformly carbon-14 labeled C60 ([(14) C(U)]C60 ). Rats were administered [(14) C(U)]C60 (~0.2 mg [(14) C(U)]C60 kg(-1) body weight) or 5% polyvinylpyrrolidone (PVP)-saline vehicle via a single tail vein injection. Pregnant rats were injected on gestation day (GD) 11 (terminated with fetuses after either 24 h or 8 days), GD15 (terminated after 24 h or 4 days), or GD18 (terminated after 24 h). Lactating rats were injected on postnatal day 8 and terminated after 24 h, 3 or 11 days. The distribution of radioactivity in pregnant dams was influenced by both the state of pregnancy and time of termination after exposure. The percentage of recovered radioactivity in pregnant and lactating rats was highest in the liver and lungs. Radioactivity was quantitated in over 20 tissues. Radioactivity was found in the placenta and in fetuses of pregnant dams, and in the milk of lactating rats and in pups. Elimination of radioactivity was < 2% in urine and feces at each time point. Radioactivity remained in blood circulation up to 11 days after [(14) C(U)]C60 exposure. Biomarkers of inflammation, cardiovascular injury and oxidative stress were measured to study the biological impacts of [(14) C(U)]C60 exposure. Oxidative stress was elevated in female pups of exposed dams. Metabolomics analysis of urine showed that [(14) C(U)]C60 exposure to pregnant rats impacted the pathways of vitamin B, regulation of lipid and sugar metabolism and aminoacyl-tRNA biosynthesis. This study demonstrated that [(14) C(U)]C60 crosses the placenta at all stages of pregnancy examined, and is transferred to pups via milk.

  16. Airborne Oceanographic Lidar (AOL) (Global Carbon Cycle)

    NASA Technical Reports Server (NTRS)

    2003-01-01

    This bimonthly contractor progress report covers the operation, maintenance and data management of the Airborne Oceanographic Lidar and the Airborne Topographic Mapper. Monthly activities included: mission planning, sensor operation and calibration, data processing, data analysis, network development and maintenance and instrument maintenance engineering and fabrication.

  17. Inverse modelling of the 14C bomb pulse in stalagmites to constrain the dynamics of soil carbon cycling at selected European cave sites

    NASA Astrophysics Data System (ADS)

    Rudzka-Phillips, D.; McDermott, F.; Jackson, A.; Fleitmann, D.

    2013-07-01

    The decomposition of soil organic matter (SOM) is temperature dependent, but its response to a future warmer climate remains equivocal. Enhanced rates of decomposition of SOM under increased global temperatures might cause higher CO2 emissions to the atmosphere, and could therefore constitute a strong positive feedback. The magnitude of this feedback however remains poorly understood, primarily because of the difficulty in quantifying the temperature sensitivity of stored, recalcitrant carbon that comprises the bulk (>90%) of SOM in most soils. In this study we investigated the effects of climatic conditions on soil carbon dynamics using the attenuation of the 14C 'bomb' pulse as recorded in selected modern European speleothems. These new data were combined with published results to further examine soil carbon dynamics, and to explore the sensitivity of labile and recalcitrant organic matter decomposition to different climatic conditions. Temporal changes in 14C activity inferred from each speleothem was modelled using a three pool soil carbon inverse model (applying a Monte Carlo method) to constrain soil carbon turnover rates at each site. Speleothems from sites that are characterised by semi-arid conditions, sparse vegetation, thin soil cover and high mean annual air temperatures (MAATs), exhibit weak attenuation of atmospheric 14C 'bomb' peak (a low damping effect, D in the range: 55-77%) and low modelled mean respired carbon ages (MRCA), indicating that decomposition is dominated by young, recently fixed soil carbon. By contrast, humid and high MAAT sites that are characterised by a thick soil cover and dense, well developed vegetation, display the highest damping effect (D = c. 90%), and the highest MRCA values (in the range from 350 ± 126 years to 571 ± 128 years). This suggests that carbon incorporated into these stalagmites originates predominantly from decomposition of old, recalcitrant organic matter. SOM turnover rates cannot be ascribed to a single

  18. Sedimentary rocks as sources of ancient organic carbon to the ocean: An investigation through Δ14C and δ13C signatures of organic compound classes

    NASA Astrophysics Data System (ADS)

    Komada, Tomoko; Druffel, Ellen R. M.; Hwang, Jeomshik

    2005-06-01

    Chemical and isotopic variability of particulate organic carbon (POC) was examined in samples from the Santa Clara River watershed and adjacent shelf to investigate the processing of fossil POC derived from bedrock. The Santa Clara is a small coastal river that drains mountainous terrain in southern California, United States. Organic carbon in shale, river suspended sediment, and coastal marine sediment was separated into three operationally defined organic compound classes: total extractable lipids, acid hydrolyzable material, and the nonhydrolyzable residue. In all samples, the nonhydrolyzable fraction was dominant (˜50% of POC), while lipids and acid hydrolyzable moieties were relatively minor (≤22 and ≤13%, respectively). The Δ14C and δ13C signatures of the isolated fractions varied dramatically, not only across different sample types, but also for a given sample. At the shale exposure, low Δ14C values (<-760‰) indicated dominance of ancient C in all three organic compound classes. In downstream samples, the extractable lipids displayed the lowest Δ14C values (<-500‰), while the acid hydrolyzable fraction was predominantly modern (Δ14C > -30‰). The nonhydrolyzable fraction displayed intermediate Δ14C values (<-190‰) that increased steadily downstream with decreasing δ13C values (-22.2 to -25.0‰), possibly from mixing of shale and surface soil POC. Our results indicate that most of the fossil POC discharged by the Santa Clara is composed of non-acid hydrolyzable material, but its elusive molecular structure and marine-like δ13C signature may render its detection in the ocean difficult. In contrast, fossil lipids may be more amenable to detection if their resistant components (e.g., asphaltic material) are unique to crustal sources.

  19. Investigation of carbon distribution with {sup 14}C as tracer for carbon dioxide (CO{sub 2}) sequestration through NH{sub 4}HCO{sub 3} production

    SciTech Connect

    Zhongxian Cheng; Youhua Ma; Xin Li; Wei-Ping Pan

    2007-12-15

    This work studies carbon fate using the {sup 14}C tracer technique in ecosystems when synthesized fertilizer is applied. The concept of aqueous ammonia solution scrubbing CO{sub 2} from flue gas is used in the fertilizer synthesis. Products after the capture are ammonium bicarbonate (ABC, NH{sub 4}HCO{sub 3}) or long-term effect ammonium bicarbonate (LEABC, NH{sub 4}HCO{sub 3}), an economic source of nitrogen fertilizer. The ABC or LEABC is used as a 'carrier' to transport CO{sub 2} from the atmosphere to the crops and soil. An indoor greenhouse was built, and wheat was chosen as the plant to study in this ecosystem. The investigated ecosystem consists of plant (wheat), soils with three different pH values (alkaline, neutral, and acidic), and three types of underground water (different Ca{sup 2+} and Mg{sup 2+} concentrations). After biological assimilation and metabolism in wheat receiving ABC or LEABC, it was found that a considerable amount (up to 10%) of the carbon source was absorbed by the wheat with increased biomass production. The majority of the unused carbon source (up to 76%) percolated into the soil as carbonates, such as environmentally benign calcium carbonate (CaCO{sub 3}). Generally speaking, alkaline soil has a higher capability to capture and store carbon. For the same soil, there is no apparent difference in carbon capturing capability between ABC and LEABC. These findings answer the question of how carbon is distributed after synthesized ABC or LEABC is applied into the ecosystem. In addition, a separate postexperiment on carbon forms that existed in the soil was made. It was found that up to 88% of the trapped carbon existed in the form of insoluble salts (i.e., CaCO{sub 3}) in alkaline soils. This indicates that alkaline soil has a greater potential for storing carbon after the use of the synthesized ABC or LEABC from exhausted CO{sub 2}. 21 refs., 6 figs., 5 tabs.

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

    NASA Astrophysics Data System (ADS)

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

    2012-09-01

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

  1. The curved 14C vs. δ13C relationship in dissolved inorganic carbon: A useful tool for groundwater age- and geochemical interpretations

    USGS Publications Warehouse

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

    2014-01-01

    Determination of the 14C content of dissolved inorganic carbon (DIC) is useful for dating of groundwater. However, in addition to radioactive decay, the 14C content in DIC (14CDIC) can be affected by many geochemical and physical processes and numerous models have been proposed to refine radiocarbon ages of DIC in groundwater systems. Changes in the δ13C content of DIC (δ13CDIC) often can be used to deduce the processes that affect the carbon isotopic composition of DIC and the 14C value during the chemical evolution of groundwater. This paper shows that a curved relationship of 14CDIC vs. δ13CDIC will be observed for groundwater systems if (1) the change in δ13C value in DIC is caused by a first-order or pseudo-first-order process, e.g. isotopic exchange between DIC and solid carbonate, (2) the reaction/process progresses with the ageing of the groundwater, i.e. with decay of 14C in DIC, and (3) the magnitude of the rate of change in δ13C of DIC is comparable with that of 14C decay. In this paper, we use a lumped parameter method to derive a model based on the curved relationship between 14CDICand δ13CDIC. The derived model, if used for isotopic exchange between DIC and solid carbonate, is identical to that derived by Gonfiantini and Zuppi (2003). The curved relationship of 14CDIC vs. δ13CDIC can be applied to interpret the age of the DIC in groundwater. Results of age calculations using the method discussed in this paper are compared with those obtained by using other methods that calculate the age of DIC based on adjusted initial radiocarbon values for individual samples. This paper shows that in addition to groundwater age interpretation, the lumped parameter method presented here also provides a useful tool for geochemical interpretations, e.g. estimation of apparent rates of geochemical reactions and revealing the complexity of the geochemical environment.

  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. Synthesizing the Use of Carbon Isotope (14C and 13C) Approaches to Understand Rates and Pathways for Permafrost C Mobilization and Mineralization

    NASA Astrophysics Data System (ADS)

    Estop-Aragones, C.; Olefeldt, D.; Schuur, E.

    2015-12-01

    To better understand the permafrost carbon (C) feedback it is important to synthesize our current knowledge, and knowledge gaps, of how permafrost thaw can cause in situ mineralization or downstream mobilization of aged soil organic carbon (SOC) and the rate of this release. This potential loss of old SOC may occur via gaseous flux of CO2 and CH4 exchanged between soil and the atmosphere and via waterborne flux as DOC, POC (and their subsequent decomposition and release to the atmosphere). Carbon isotope (14C and 13C) approaches have been used to estimate both rates and pathways for permafrost C mobilization and mineralization. Radiocarbon (14C) has been used to estimate the contribution of aged C to overall respiration or waterborne C export. We aim to contrast results from radiocarbon studies, in order to assess differences between ecosystems (contrasting wet and dry ecosystems), thaw histories (active layer deepening or thermokarst landforms), greenhouse gas considered (CO2 and CH4) and seasons. We propose to also contrast methodologies used for assessing the contribution of aged C to overall C balance, and include studies using 13C data. Biological fractionation of 13C during both uptake and decomposition has been taken advantage of both in order to aid the interpretation of 14C data and on its own to assess sources and mineralization pathways. For example, 13C data has been used to differentiate between CH4 production pathways, and the relative contribution of anaerobic CO2 production to overall respiration. Overall, carbon isotope research is proving highly valuable for our understanding of permafrost C dynamics following thaw, and there is a current need to synthesize the available literature.

  4. Carbon isotopes profiles of human whole blood, plasma, red blood cells, urine and feces for biological/biomedical 14C-accelerator mass spectrometry applications.

    PubMed

    Kim, Seung-Hyun; Chuang, Jennifer C; Kelly, Peter B; Clifford, Andrew J

    2011-05-01

    Radiocarbon ((14)C) is an ideal tracer for in vivo human ADME (absorption, distribution, metabolism, elimination) and PBPK (physiological-based pharmacokinetic) studies. Living plants peferentially incorporate atmospheric (14)CO(2) versus (13)CO(2) versus (12)CO(2), which result in unique signature. Furthermore, plants and the food chains they support also have unique carbon isotope signatures. Humans, at the top of the food chain, consequently acquire isotopic concentrations in the tissues and body fluids depending on their dietary habits. In preparation of ADME and PBPK studies, 12 healthy subjects were recruited. The human baseline (specific to each individual and their diet) total carbon (TC) and carbon isotope (13)C (δ(13)C) and (14)C (F(m)) were quantified in whole blood (WB), plasma, washed red blood cell (RBC), urine, and feces. TC (mg of C/100 μL) in WB, plasma, RBC, urine, and feces were 11.0, 4.37, 7.57, 0.53, and 1.90, respectively. TC in WB, RBC, and feces was higher in men over women, P < 0.05. Mean δ(13)C were ranked low to high as follows: feces < WB = plasma = RBC = urine, P < 0.0001. δ(13)C was not affected by gender. Our analytic method shifted δ(13)C by only ±1.0 ‰ ensuring our F(m) measurements were accurate and precise. Mean F(m) were ranked low to high as follows: plasma = urine < WB = RBC = feces, P < 0.05. F(m) in feces was higher for men over women, P < 0.05. Only in WB, (14)C levels (F(m)) and TC were correlated with one another (r = 0.746, P < 0.01). Considering the lag time to incorporate atmospheric (14)C into plant foods (vegetarian) and or then into animal foods (nonvegetarian), the measured F(m) of WB in our population (recruited April 2009) was 1.0468 ± 0.0022 (mean ± SD), and the F(m) of WB matched the (extrapolated) atmospheric F(m) of 1.0477 in 2008. This study is important in presenting a procedure to determine a baseline for a study group for human ADME and PBPK studies using (14)C as a tracer.

  5. 14C in cropland soil of a long-term field trial - in-field variability and implications for estimating carbon turnover

    NASA Astrophysics Data System (ADS)

    Leifeld, J.; Mayer, J.

    2015-03-01

    Because of their controlled nature, the presence of independent replicates, and their known management history long-term field experiments are key to the understanding of factors controlling soil carbon. Together with isotope measurements, they provide profound insight into soil carbon dynamics. For soil radiocarbon, an important tracer for understanding these dynamics, in-field variability across replicates is usually not accounted for, hence, a relevant source of uncertainty for quantifying turnover rates is missing. Here, for the first time, radiocarbon measurements of independent field replicates, and for different layers, of soil from the 60 years old controlled field experiment ZOFE in Zurich, Switzerland, is used to address this issue. 14C variability was the same across three different treatments and for three different soil layers between surface and 90 cm depths. On average, in-field variability in 14C content was 12 times the analytical error but still, on a relative basis, smaller than that of in-field soil carbon concentration variability. Despite a relative homogeneous variability across the field and along the soil profile, the curved nature of the relationship between radiocarbon content and modelled carbon mean residence time suggests that the absolute error, without consideration of in-field variability, introduced to soil carbon turnover time calculations increases with soil depth. In our field experiment findings on topsoil carbon turnover variability would, if applied to subsoil, tend to underweight turnover variability even if in-field variability of the subsoil isotope concentration is not higher. Together, in-field variability in radiocarbon is an important component in an overall uncertainty assessment of soil carbon turnover.

  6. [Carbon metabolic characteristics of airborne microbes in Hangzhou].

    PubMed

    Gong, Chan-Juan; Xu, Jing; Fang, Zhi-Guo; Lou, Xiu-Qin; Ouyang, Zhi-Yun

    2014-02-01

    Carbon metabolic characteristics in four sampling sites including Yan'an Road Business Street (YRBS), Tianmushan Jiaogong Cross Road (TJCR), Zhejiang Gongshang University Jiaogong Campus (ZJGSUJC) and Breeze-ruffled Lotus at Quyuan Garden (BLQG) in Hangzhou were analyzed using Biolog technology in this study. Results showed that average well color development (AWCD) values were at stationary phase after 240 h cultivation in all four selected sampling sites. Significant differences in sole carbon utilization characterized as AWCD value were found among the four sampling sites, and the highest carbon utilization capacity was observed at YRBS, followed by TJCR and ZJGSUJC, and the lowest at BLQG. The species abundance and diversity of airborne microbes deceased in the order of YRBS, TJCR, ZJGSUJC, and BLQG. In addition, sugar and amino acid utilization capacity of airborne microbes was significantly higher that other carbons sources in all four sampling sites. Significant differences in different sole carbon utilization of airborne microbes in the same sampling site were found. The sugar utilization capacity was the highest, and polymer utilization capacity was the lowest at YRBS. At BLQG, highest sugar and lowest amine utilization capacity was detected. Principal component analysis showed that the contribution of PC1 and PC2 was 43.8% and 23.4%, respectively, in different sampling sites. Significant differences in carbon metabolic characteristics of microbial community in the air were found among YRBS, BLQG and TJCR, and no differences were observed between TJCR and ZJGSUJC.

  7. Detecting Airborne Mercury by Use of Polymer/Carbon Films

    NASA Technical Reports Server (NTRS)

    Shevade, Abhijit; Ryan, Margaret; Homer, Margie; Kisor, Adam; Jewell, April; Yen, Shiao-Pin; Manatt, Kenneth; Blanco, Mario; Goddard, William

    2009-01-01

    Films made of certain polymer/carbon composites have been found to be potentially useful as sensing films for detecting airborne elemental mercury at concentrations on the order of tens of parts per billion or more. That is to say, when the polymer/carbon composite films are exposed to air containing mercury vapor, their electrical resistances decrease by measurable amounts. Because airborne mercury is a health hazard, it is desirable to detect it with great sensitivity, especially in enclosed environments in which there is a risk of a mercury leak from lamps or other equipment. The present effort to develop polymerbased mercury-vapor sensors complements the work reported in NASA Tech Briefs Detecting Airborne Mercury by Use of Palladium Chloride (NPO- 44955), Vol. 33, No. 7 (July 2009), page 48 and De tecting Airborne Mer cury by Use of Gold Nanowires (NPO-44787), Vol. 33, No. 7 (July 2009), page 49. Like those previously reported efforts, the present effort is motivated partly by a need to enable operation and/or regeneration of sensors under relatively mild conditions more specifically, at temperatures closer to room temperature than to the elevated temperatures (greater than 100 C ) needed for regeneration of sensors based on noble-metal films. The present polymer/carbon films are made from two polymers, denoted EYN1 and EYN2 (see Figure 1), both of which are derivatives of poly-4-vinyl pyridine with amine functional groups. Composites of these polymers with 10 to 15 weight percent of carbon were prepared and solution-deposited onto the JPL ElectronicNose sensor substrates for testing. Preliminary test results showed that the resulting sensor films gave measurable indications of airborne mercury at concentrations on the order of tens of parts per billion (ppb) or more. The operating temperature range for the sensing films was 28 to 40 C and that the sensor films regenerated spontaneously, without heating above operating temperature (see Figure 2).

  8. Biophysical influence of airborne carbon nanomaterials on natural pulmonary surfactant.

    PubMed

    Valle, Russell P; Wu, Tony; Zuo, Yi Y

    2015-05-26

    Inhalation of nanoparticles (NP), including lightweight airborne carbonaceous nanomaterials (CNM), poses a direct and systemic health threat to those who handle them. Inhaled NP penetrate deep pulmonary structures in which they first interact with the pulmonary surfactant (PS) lining at the alveolar air-water interface. In spite of many research efforts, there is a gap of knowledge between in vitro biophysical study and in vivo inhalation toxicology since all existing biophysical models handle NP-PS interactions in the liquid phase. This technical limitation, inherent in current in vitro methodologies, makes it impossible to simulate how airborne NP deposit at the PS film and interact with it. Existing in vitro NP-PS studies using liquid-suspended particles have been shown to artificially inflate the no-observed adverse effect level of NP exposure when compared to in vivo inhalation studies and international occupational exposure limits (OELs). Here, we developed an in vitro methodology called the constrained drop surfactometer (CDS) to quantitatively study PS inhibition by airborne CNM. We show that airborne multiwalled carbon nanotubes and graphene nanoplatelets induce a concentration-dependent PS inhibition under physiologically relevant conditions. The CNM aerosol concentrations controlled in the CDS are comparable to those defined in international OELs. Development of the CDS has the potential to advance our understanding of how submicron airborne nanomaterials affect the PS lining of the lung.

  9. Large fluxes and rapid turnover of mineral-associated carbon across topographic gradients in a humid tropical forest: insights from paired 14C analysis

    NASA Astrophysics Data System (ADS)

    Hall, S. J.; McNicol, G.; Natake, T.; Silver, W. L.

    2015-04-01

    It has been proposed that the large soil carbon (C) stocks of humid tropical forests result predominantly from C stabilization by reactive minerals, whereas oxygen (O2) limitation of decomposition has received much less attention. We examined the importance of these factors in explaining patterns of C stocks and turnover in the Luquillo Experimental Forest, Puerto Rico, using radiocarbon (14C) measurements of contemporary and archived samples. Samples from ridge, slope, and valley positions spanned three soil orders (Ultisol, Oxisol, Inceptisol) representative of humid tropical forests, and differed in texture, reactive metal content, O2 availability, and root biomass. Mineral-associated C comprised the large majority (87 ± 2%, n = 30) of total soil C. Turnover of most mineral-associated C (66 ± 2%) was rapid (11 to 26 years; mean and SE: 18 ± 3 years) in 25 of 30 soil samples across surface horizons (0-10 and 10-20 cm depths) and all topographic positions, independent of variation in reactive metal concentrations and clay content. Passive C with centennial-millennial turnover was typically much less abundant (34 ± 3%), even at 10-20 cm depths. Carbon turnover times and concentrations significantly increased with concentrations of reduced iron (Fe(II)) across all samples, suggesting that O2 availability may have limited the decomposition of mineral-associated C over decadal scales. Steady-state inputs of mineral-associated C were statistically similar among the three topographic positions, and could represent 10-25% of annual litter production. Observed trends in mineral-associated Δ14C over time could not be fit using the single-pool model used in many other studies, which generated contradictory relationships between turnover and Δ14C as compared with a more realistic two-pool model. The large C fluxes in surface and near-surface soils documented here are supported by findings from paired 14C studies in other types of ecosystems, and suggest that most

  10. Large fluxes and rapid turnover of mineral-associated carbon across topographic gradients in a humid tropical forest: insights from paired 14C analysis

    NASA Astrophysics Data System (ADS)

    Hall, S. J.; McNicol, G.; Natake, T.; Silver, W. L.

    2015-01-01

    It has been proposed that the large soil carbon (C) stocks of humid tropical forests result predominantly from C stabilization by reactive minerals, whereas oxygen (O2) limitation of decomposition has received much less attention. We examined the importance of these factors in explaining patterns of C stocks and turnover in the Luquillo Experimental Forest, Puerto Rico, using radiocarbon (14C) measurements of contemporary and archived samples. Samples from ridge, slope, and valley positions spanned three soil orders (Ultisol, Oxisol, Inceptisol) representative of humid tropical forests, and differed in texture, reactive metal content, O2 availability, and root biomass. Mineral-associated C comprised the large majority (87 ± 2%, n = 30) of total soil C. Turnover of most mineral-associated C (74 ± 4%) was rapid (9 to 29 years, mean and SE 20 ± 2 years) in 25 of 30 soil samples across surface horizons (0-10 and 10-20 cm depths) and all topographic positions, independent of variation in reactive metal concentrations and clay content. Passive C with centennial - millennial turnover was much less abundant (26%), even at 10-20 cm depths. Carbon turnover times and concentrations significantly increased with concentrations of reduced iron (Fe(II)) across all samples, suggesting that O2 availability may have limited the decomposition of mineral associated C over decadal scales. Steady-state inputs of mineral-associated C were similar among the three topographic positions, and could represent 10-30% of annual litterfall production (estimated by doubling aboveground litterfall). Observed trends in mineral-associated Δ14C over time could not be fit using the single pool model used in many other studies, which generated contradictory relationships between turnover and Δ14C as compared with a more realistic constrained two-pool model. The large C fluxes in surface and near-surface soils implied by our data suggest that other studies using single-pool Δ14C models of mineral

  11. Large fluxes and rapid turnover of mineral-associated carbon across topographic gradients in a humid tropical forest: insights from paired 14C analysis

    DOE PAGES

    Hall, S. J.; McNicol, G.; Natake, T.; ...

    2015-04-29

    It has been proposed that the large soil carbon (C) stocks of humid tropical forests result predominantly from C stabilization by reactive minerals, whereas oxygen (O2) limitation of decomposition has received much less attention. We examined the importance of these factors in explaining patterns of C stocks and turnover in the Luquillo Experimental Forest, Puerto Rico, using radiocarbon (14C) measurements of contemporary and archived samples. Samples from ridge, slope, and valley positions spanned three soil orders (Ultisol, Oxisol, Inceptisol) representative of humid tropical forests, and differed in texture, reactive metal content, O2 availability, and root biomass. Mineral-associated C comprised themore » large majority (87 ± 2%, n = 30) of total soil C. Turnover of most mineral-associated C (66 ± 2%) was rapid (11 to 26 years; mean and SE: 18 ± 3 years) in 25 of 30 soil samples across surface horizons (0–10 and 10–20 cm depths) and all topographic positions, independent of variation in reactive metal concentrations and clay content. Passive C with centennial–millennial turnover was typically much less abundant (34 ± 3%), even at 10–20 cm depths. Carbon turnover times and concentrations significantly increased with concentrations of reduced iron (Fe(II)) across all samples, suggesting that O2 availability may have limited the decomposition of mineral-associated C over decadal scales. Steady-state inputs of mineral-associated C were statistically similar among the three topographic positions, and could represent 10–25% of annual litter production. Observed trends in mineral-associated Δ14C over time could not be fit using the single-pool model used in many other studies, which generated contradictory relationships between turnover and Δ14C as compared with a more realistic two-pool model. The large C fluxes in surface and near-surface soils documented here are supported by findings from paired 14C studies in other types of ecosystems, and

  12. Relationships between Δ14C and the molecular quality of dissolved organic carbon in rivers draining to the coast from the conterminous United States

    USGS Publications Warehouse

    Butman, David; Raymond, Peter A.; Butler, Kenna; Aiken, George R.

    2012-01-01

    Dissolved organic carbon (DOC) in natural waters possesses chemical and molecular qualities indicative of its source and age. The apportionment of DOC by age into millennial and decadal pools is necessary to understand the temporal connection between terrestrial and aquatic ecosystems in the global carbon cycle. We measured Δ14C-DOC and chemical composition indices (specific ultraviolet absorbance (SUVA254), fluorescence index (FI), hydrophobic organic acid fraction (HPOA) content) for 15 large river basins in the conterminous United States. Across all rivers the average proportion of HPOA in DOC correlated strongly with SUVA254 (r2 = 0.93 p < 0.001). Individual Δ14C-DOC ranged from a low of −92.9‰ (726 y.b.p.) in the Colorado River to 73.4‰ (>Modern) in the Altamaha River for the year 2009. When adjusted by total discharge, these U.S. Rivers export modern carbon at between 34 and 46‰, a signal dominated by the Mississippi River. The variation in Δ14C correlates to indices of the aromaticity of the DOC measured by the SUVA254 (r2 = 0.87, p < 0.001), and FI (r2 = 0.6; p < 0.001) as well as differences in annual river discharge (r2 = 0.46, p < 0.006). SUVA254 was further correlated to broad scale vegetation phenology estimated from the Enhanced Vegetation Index derived from the NASA Moderate Resolution Imaging Spectrometer (MODIS). We show that basins with high discharge, high proportions of vegetation cover, and low human population densities export DOC enriched in aromatic material that corresponds to recently fixed atmospheric CO2. Conversely old DOC is exported from low discharge watersheds draining arid regions, and watersheds more strongly impacted by humans. The potential influence from fossil carbon from human inputs to aquatic systems may be important and requires more research.

  13. ARM Airborne Continuous carbon dioxide measurements

    DOE Data Explorer

    Biraud, Sebastien

    2013-03-26

    The heart of the AOS CO2 Airborne Rack Mounted Analyzer System is the AOS Manifold. The AOS Manifold is a nickel coated aluminum analyzer and gas processor designed around two identical nickel-plated gas cells, one for reference gas and one for sample gas. The sample and reference cells are uniquely designed to provide optimal flushing efficiency. These cells are situated between a black-body radiation source and a photo-diode detection system. The AOS manifold also houses flow meters, pressure sensors and control valves. The exhaust from the analyzer flows into a buffer volume which allows for precise pressure control of the analyzer. The final piece of the analyzer is the demodulator board which is used to convert the DC signal generated by the analyzer into an AC response. The resulting output from the demodulator board is an averaged count of CO2 over a specified hertz cycle reported in volts and a corresponding temperature reading. The system computer is responsible for the input of commands and therefore works to control the unit functions such as flow rate, pressure, and valve control.The remainder of the system consists of compressors, reference gases, air drier, electrical cables, and the necessary connecting plumbing to provide a dry sample air stream and reference air streams to the AOS manifold.

  14. Retention of 14C-labeled multiwall carbon nanotubes by humic acid and polymers: Roles of macromolecule properties

    PubMed Central

    Zhao, Qing; Petersen, Elijah J.; Cornelis, Geert; Wang, Xilong; Guo, Xiaoying; Tao, Shu; Xing, Baoshan

    2016-01-01

    Developing methods to measure interactions of carbon nanotubes (CNTs) with soils and sediments and understanding the impact of soil and sediment properties on CNT deposition are essential for assessing CNT environmental risks. In this study, we utilized functionalized carbon-14 labeled nanotubes to systematically investigate retention of multiwall CNTs (MWCNTs) by 3 humic acids, 3 natural biopolymers, and 10 model solid-phase polymers, collectively termed macromolecules. Surface properties, rather than bulk properties of macromolecules, greatly influenced MWCNT retention. As shown via multiple linear regression analysis and path analysis, aromaticity and surface polarity were the two most positive factors for retention, suggesting retention was regulated by π-π stacking and hydrogen bonding interactions. Moreover, MWCNT deposition was irreversible. These observations may explain the high retention of MWCNT in natural soils. Moreover, our findings on the relative contribution of each macromolecule property on CNT retention provide information on macromolecule selection for removal of MWCNTs from wastewater and provide a method for measuring CNT interactions with organic macromolecules. PMID:27458320

  15. Review and developments of dissemination models for airborne carbon fibers

    NASA Technical Reports Server (NTRS)

    Elber, W.

    1980-01-01

    Dissemination prediction models were reviewed to determine their applicability to a risk assessment for airborne carbon fibers. The review showed that the Gaussian prediction models using partial reflection at the ground agreed very closely with a more elaborate diffusion analysis developed for the study. For distances beyond 10,000 m the Gaussian models predicted a slower fall-off in exposure levels than the diffusion models. This resulting level of conservatism was preferred for the carbon fiber risk assessment. The results also showed that the perfect vertical-mixing models developed herein agreed very closely with the diffusion analysis for all except the most stable atmospheric conditions.

  16. Carbon transitions from either Calvin cycle or transitory starch to heteroglycans as revealed by (14) C-labeling experiments using protoplasts from Arabidopsis.

    PubMed

    Malinova, Irina; Steup, Martin; Fettke, Joerg

    2013-09-01

    Plants metabolize transitory starch by precisely coordinated plastidial and cytosolic processes. The latter appear to include the action of water-soluble heteroglycans (SHGin ) whose monosaccharide pattern is similar to that of apoplastic glycans (SHGex ) but, unlike SHGex , SHGin strongly interacts with glucosyl transferases. In this study, we analyzed starch metabolism using mesophyll protoplasts from wild-type plants and two knock-out mutants [deficient in the cytosolic transglucosidase, disproportionating isoenzyme 2 (DPE2) or the plastidial phosphoglucomutase (PGM1)] from Arabidopsis thaliana. Protoplasts prelabeled by photosynthetic (14) CO2 fixation were transferred to an unlabeled medium and were darkened or illuminated. Carbon transitions from the Calvin cycle or from starch to both SHGin and SHGex were analyzed. In illuminated protoplasts, starch turn-over was undetectable but darkened protoplasts continuously degraded starch. During illumination, neither the total (14) C content nor the labeling patterns of the sugar residues of SHGin were significantly altered but both the total amount and the labeling of the constituents of SHGex increased with time. In darkened protoplasts, the (14) C-content of most of the sugar residues of SHGin transiently and strongly increased and then declined. This effect was not observed in any SHGex constituent. In darkened DPE2-deficient protoplasts, none of the SHGin constituents exhibited an essential transient increase in labeling. In contrast, some residues of SHGin from the PGM1 mutant exhibited a transient increase in label but this effect significantly differed from that of the wild type. Two conclusions are reached: first, SHGin and SHGex exert different metabolic functions and second, SHGin is directly involved in starch degradation.

  17. Distribution and biomarkers of Carbon-14 labeled fullerene C60 ([14C(U)]C60) in female rats and mice for up to 30 days after intravenous exposure

    PubMed Central

    Sumner, Susan C. J.; Snyder, Rodney W.; Wingard, Christopher; Mortensen, Ninell P.; Holland, Nathan A.; Shannahan, Jonathan H.; Dhungana, Suraj; Pathmasiri, Wimal; Han, Li; Lewin, Anita H.; Fennell, Timothy R.

    2016-01-01

    A comprehensive distribution study was conducted in female rats and mice exposed to a suspension of uniformly carbon-14 labeled C60 ([14C(U)]C60). Rodents were administered [14C(U)]C60 (~0.9 mg /kg body weight) or 5% PVP-saline vehicle alone via a single tail vein injection. Tissues were collected at 1 hour, 1, 7, 14 and 30 days after administration. A separate group of rodents received 5 daily injections of suspensions of either [14C(U)]C60 or vehicle with tissue collection 14 days post exposure. Radioactivity was detected in over 20 tissues at all time period. The highest concentration of radioactivity in rodents at each time point was in liver, lungs and spleen. Elimination of [14C(U)]C60 was <2% in urine and feces at any 24 hour time points. [14C(U)]C60 and [14C(U)]C60-retinol were detected in liver of rats and together accounted for ~99% and ~56% of the total recovered at 1 and 30 days post exposure, respectively. The blood radioactivity at 1 hour after [14C(U)]C60 exposure was four-fold higher in rats than in mice; blood radioactivity was still in circulation at 30 days post [14C(U)]C60 exposure in both species (<1%). Levels of oxidative stress markers increased by 5 days after exposure and remained elevated, while levels of inflammation markers initially increased and then returned to control values. The level of cardiovascular marker vWF, increased in rats, but remained at control levels in mice. This study demonstrates that [14C(U)]C60 is retained in female rodents with little elimination by 30 days after i.v. exposure, and leads to systemic oxidative stress. PMID:25727383

  18. Distribution and biomarkers of carbon-14-labeled fullerene C60 ([(14) C(U)]C60 ) in female rats and mice for up to 30 days after intravenous exposure.

    PubMed

    Sumner, Susan C J; Snyder, Rodney W; Wingard, Christopher; Mortensen, Ninell P; Holland, Nathan A; Shannahan, Jonathan H; Dhungana, Suraj; Pathmasiri, Wimal; Han, Li; Lewin, Anita H; Fennell, Timothy R

    2015-12-01

    A comprehensive distribution study was conducted in female rats and mice exposed to a suspension of uniformly carbon-14-labeled C60 ([(14) C(U)]C60 ). Rodents were administered [(14) C(U)]C60 (~0.9 mg kg(-1) body weight) or 5% polyvinylpyrrolidone-saline vehicle alone via a single tail vein injection. Tissues were collected at 1 h and 1, 7, 14 and 30 days after administration. A separate group of rodents received five daily injections of suspensions of either [(14) C(U)]C60 or vehicle with tissue collection 14 days post exposure. Radioactivity was detected in over 20 tissues at all time points. The highest concentration of radioactivity in rodents at each time point was in liver, lungs and spleen. Elimination of [(14) C(U)]C60 was < 2% in urine and feces at any 24 h time points. [(14) C(U)]C60 and [(14) C(U)]C60 -retinol were detected in liver of rats and together accounted for ~99% and ~56% of the total recovered at 1 and 30 days postexposure, respectively. The blood radioactivity at 1 h after [(14) C(U)]C60 exposure was fourfold higher in rats than in mice; blood radioactivity was still in circulation at 30 days post [(14) C(U)]C60 exposure in both species (<1%). Levels of oxidative stress markers increased by 5 days after exposure and remained elevated, while levels of inflammation markers initially increased and then returned to control values. The level of cardiovascular marker von Willebrand factor, increased in rats, but remained at control levels in mice. This study demonstrates that [(14) C(U)]C60 is retained in female rodents with little elimination by 30 days after i.v. exposure, and leads to systemic oxidative stress.

  19. Tritium and radioactive carbon (14C) analyses of gas collected from unsaturated sediments next to a low-level radioactive-waste burial site south of Beatty, Nevada, April 1994 and July 1995

    USGS Publications Warehouse

    Prudic, David E.; Striegl, Robert G.

    1995-01-01

    Tritium activities in water vapor and radioactive carbon (14C) activities in carbon dioxide were determined in gas samples pumped from small-diameter air ports installed in a test hole within the unsaturated sediments next to a commercial burial site for low-level radioactive waste south of Beatty, Nevada. In April 1994, gas samples were collected from test hole UZB-2, which was drilled about 350 feet south of the southwest corner of the fence enclosing the burial site. The test hole is part of a study to determine the depth to which atmospheric air circulates through the unsaturated sediments at the desert site. Laboratory results completed in May 1995 show activities of tritium and 14C were greater than expected, with measured tritium in the water vapor as high as 762 tritium units at a depth of 79 feet and measured 14C in carbon dioxide as high as 1,700 percent modern carbon at a depth of 18 feet. In July 1995, the uppermost five air ports in test hole UZB-2 were resampled. In addition, water vapor was collected for tritium analyses at a distant test hole, and water vapor for tritium analyses and carbon dioxide for 14C analyses were collected from three depths at the research shaft about 200 feet north of test hole UZB-2, and at two shallow probes (depth of 5.5 feet) next to the fence enclosing the burial site. Analyses of samples collected in the upper 112 feet from test hole UZB-2 in July 1995 show the same distribution of tritium and 14C as analyses of samples collected in April 1994, except that activities were somewhat greater in July. The greatest activities of tritium and 14C were measured from a shallow probe next to the fence with activities of 29,400 tritium units and 517,000 percent modern carbon, respectively.

  20. [Carbon sources metabolic characteristics of airborne microbial communities in constructed wetlands].

    PubMed

    Song, Zhi-Wen; Wang, Lin; Xu, Ai-Ling; Wu, Deng-Deng; Xia, Yan

    2015-02-01

    Using BIOLOG-GN plates, this article describes the carbon sources metabolic characteristics of airborne microbial communities in a free surface-flow constructed wetland in different seasons and clarify the correlation between airborne microbial metabolic functions and environmental factors. The average well color development (AWCD), carbon metabolic profiles and McIntosh values of airborne microbial communities in different seasons were quite different. Analysis of the variations showed that AWCD in spring and summer differed significantly from that in autumn and winter (P < 0.01). In the same season, the degree of utilization of different types of carbon by airborne microbes was different. Summer had a significant difference from other seasons (P < 0.05). Dominant communities of airborne microbes in four seasons were carboxylic acids metabolic community, carbohydrates metabolic community, polymers metabolic community and carboxylic acids metabolic community respectively. Principal component analysis showed that the carbon metabolic characteristics of airborne microbial community in autumn were similar to those in winter but different from those in spring and summer. The characteristics of carbon metabolism revealed differences between summer and spring, autumn, or winter. These differences were mainly caused by amines or amides while the differences between spring and autumn or winter were mainly caused by carboxylic acids. Environmental factors, including changes in wind speed, temperature, and humidity acted to influence the carbon sources metabolic properties of airborne microbial community. The dominant environmental factors that acted to influence the carbon sources metabolic properties of airborne microbial community varied between different seasons.

  1. Distribution of carbon-14 and associated radiation dose in rat fetal brain and liver after maternal injection of [{sup 14}C]thymidine

    SciTech Connect

    Takahashi, Sentaro; Kubota, Yoshihisa; Koshimoto, Chihiro; Sato, Hiroshi; Hatashita, Shizuo

    1994-10-01

    Pregnant Sprague-Dawley rats were injected intravenously with [{sup 14}C]thymidine on day 13.5 of gestation, and the concentrations and radiation doses of {sup 14}C in the fetal brain and liver were determined by liquid scintillation counting were 1.01% of the injected dose per gram wet weight at 6 h after injection and decreased to 0.39% g{sup {minus}1} at 48 h after injection. A significant accumulation of {sup 14}C was observed in the fetal liver: 3.8 and 0.51% of the injected dose per gram wet weight at 6 and 48 h after injection, respectively. Autoradiography showed that, especially at earlier periods after injection, there was remarkable concentration of {sup 14}C in the ventricular zone of the brain and the central region of the liver. With increasing time after injection, the distribution of {sup 14}C became relatively uniform. The concentrations of {sup 14}C in the ventricular zone of the fetal brain, determined by autoradiography, were much higher than those in the whole brain as determined by liquid scintillation counting. Cumulative radiation doses for 6-48 h after injection were 1.27 mGy for the whole fetus and 1.45 mGy for the whole brain. In contrast, the cumulative radiation dose for the ventricular zone of the brain which was determined by autoradiography was approximately 2.2 times that for the whole brain. 18 refs., 5 figs., 3 tabs.

  2. ARM Airborne Carbon Measurements VI (ACME VI) Science Plan

    SciTech Connect

    Biraud, S

    2015-12-01

    From October 1 through September 30, 2016, the Atmospheric Radiation Measurement (ARM) Aerial Facility will deploy the Cessna 206 aircraft over the Southern Great Plains (SGP) site, collecting observations of trace-gas mixing ratios over the ARM’s SGP facility. The aircraft payload includes two Atmospheric Observing Systems, Inc., analyzers for continuous measurements of CO2 and a 12-flask sampler for analysis of carbon cycle gases (CO2, CO, CH4, N2O, 13CO2, 14CO2, carbonyl sulfide, and trace hydrocarbon species, including ethane). The aircraft payload also includes instrumentation for solar/infrared radiation measurements. This research is supported by the U.S. Department of Energy’s ARM Climate Research Facility and Terrestrial Ecosystem Science Program and builds upon previous ARM Airborne Carbon Measurements (ARM-ACME) missions. The goal of these measurements is to improve understanding of 1) the carbon exchange at the SGP site, 2) how CO2 and associated water and energy fluxes influence radiative forcing, convective processes and CO2 concentrations over the SGP site, and 3) how greenhouse gases are transported on continental scales.

  3. Microbial carbon cycling in oligotrophic regional aquifers near the Tono Uranium Mine, Japan as inferred from δ 13C and Δ 14C values of in situ phospholipid fatty acids and carbon sources

    NASA Astrophysics Data System (ADS)

    Mills, Christopher T.; Amano, Yuki; Slater, Gregory F.; Dias, Robert F.; Iwatsuki, Teruki; Mandernack, Kevin W.

    2010-07-01

    Microorganisms are ubiquitous in deep subsurface environments, but their role in the global carbon cycle is not well-understood. The natural abundance δ 13C and Δ 14C values of microbial membrane phospholipid fatty acids (PLFAs) were measured and used to assess the carbon sources of bacteria in sedimentary and granitic groundwaters sampled from three boreholes in the vicinity of the Tono Uranium Mine, Gifu, Japan. Sample storage experiments were performed and drill waters analyzed to characterize potential sources of microbial contamination. The most abundant PLFA structures in all waters sampled were 16:0, 16:1ω7 c, cy17:0, and 18:1ω7 c. A PLFA biomarker for type II methanotrophs, 18:1ω8 c, comprised 3% and 18% of total PLFAs in anoxic sedimentary and granitic waters, respectively, sampled from the KNA-6 borehole. The presence of this biomarker was unexpected given that type II methanotrophs are considered obligate aerobes. However, a bacterium that grows aerobically with CH 4 as the sole energy source and which also produces 56% of its total PLFAs as 18:1ω8 c was isolated from both waters, providing additional evidence for the presence of type II methanotrophs. The Δ 14C values determined for type II methanotroph PLFAs in the sedimentary (-861‰) and granite (-867‰) waters were very similar to the Δ 14C values of dissolved inorganic carbon (DIC) in each water (˜-850‰). This suggests that type II methanotrophs ultimately derive all their carbon from inorganic sources, whether directly from DIC and/or from CH 4 produced by the reduction of DIC. In contrast, δ 13C values of type II PLFAs in the sedimentary (-93‰) and granite (-60‰) waters indicate that these organisms use different carbon assimilation schemes in each environment despite very similar δ13C values (˜-95‰) for each water. The δ 13C PLFA values (-28‰ to -45‰) of non-methanotrophic bacteria in the KNA-6 LTL water do not clearly distinguish between heterotrophic and autotrophic

  4. Apportioning carbon sources of authigenic carbonate of extremely 13C-depleted foraminifera from the western North Pacific sediments: Implication from the coupled 13C and 14C isotopic mass balance approach

    NASA Astrophysics Data System (ADS)

    Uchida, M.; Ohkushi, K.; Ahagon, N.; Kimoto, K.; Inagaki, F.; Shibata, Y.

    2005-12-01

    Recently, Uchida et al. (G-cubed, 2004) and Ohkushi et al. (G-cubed, 2005) interprete /delta 13C variations of planktonic and benthic foraminifera found in Last Glacial sediments in off Shimokita Peninsula and Tokachi as evidence for periodic releases of methane, arising from the dissociation of methane hydrate, and its subsequent oxidation in bottom- and/or surface-water environments. According to recent observations of anomalous bottom-simulating reflections, northwest Pacific marginal sediments around Japan main islands bear large abundances of methane hydrate. In this study, analyzed piston cores (42° 21.42' N, 144° 13.36' E) at a water depth 1066-m was retrieved from the off Tokachi continental slope in the Oyashio current region, where recently is found to bear immense amounts of methane hydrate. The piston core covered past 22 ka with high-resolution. Here we showed that carbon isotope signals indicated that planktonic and benthic foraminifera in several glacial sediment layers in the core were highly depleted in13 C; both the planktonic and benthic foraminiferal /delta 13C values ranged from about -10/permil to -2/permil. Most foraminiferal tests in these horizons were brown as a result of postdepositional alteration. Foraminiferal oxygen isotopes fluctuated abnormally in the glacial sediment layers, showing small (about 0.5/permil) positive shifts relative to normal glacial values. We attributed the positive shifts to authigenic carbonate formation in the foraminiferal tests. In order to decipher the relation between foraminifera carbon isotopic signal and methane release from the seafloor, we have apportioned carbon sources (methane from methane hydrate or not) of foraminiferal carbon isotopic anomalies using dual mass balance isotopic model (14C/ 12C and 13C/ 12C). It has been suggested that sulfate-dependent anaerobic methane oxidation (AOM) dominates carbon oxidation and attendant authigenic carbonate precipitation to foraminifera. To this assumption

  5. Distribution of labeled products from (1-/sup 14/C), (U-/sup 14/C) and (16-/sup 14/C)-palmitate in isolated rat hepatocytes and liver mitochondria

    SciTech Connect

    Chatzidakis, C.; Otto, D.A.

    1986-05-01

    Fatty acids (FA) labeled in different carbon positions are used to study the distribution of labeled oxidation products. With rat hepatocytes (Hep) the authors observed significant differences in the distribution of label into products from (1-/sup 14/C) and (U-/sup 14/C)-palmitate (P). The total recovery of label in products (/sup 14/CO/sub 2/ + acid soluble fraction (ASF)) was identical between the two labeled FA. However, /sup 14/CO/sub 2/ production from (U-/sup 14/C)-P was only 40% of that from (1-/sup 14/C)-P. A recent report showed that approximately = 95% of succinate (Suc) utilized by Hep does not complete one full turn through the citric acid cycle. The authors observed that /sup 14/CO/sub 2/ evolution from (2,3-/sup 14/C)-Suc was approximately = 9% of that from (1,4-/sup 14/C)-Suc, indicating that the differences in label distribution between (1-/sup 14/C) and (U-/sup 14/C)-P are partially due to less /sup 14/CO/sub 2/ production from label in the even carbon positions of the FA with consequently more label remaining in the ASF. The /sup 14/CO/sub 2/ production from (16-/sup 14/C)-P was only 4% of that from (1-/sup 14/C)-P a value less than expected from the Suc experiments. Ketone bodies (KB) comprised 78% of total labeled products from (16-/sup 14/C)-P as compared to 28% from (1-/sup 14/C)-P and 41% from (U-/sup 14/C)-P, giving support to the previously reported preferential use of the omega-C/sub 2/ unit for KB synthesis without entry into the acetyl-CoA pool. Studies with isolated rat liver mitochondria gave results similar to those with Hep, indicating minimal involvement of perioxisomal ..beta..-oxidation.

  6. 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

  7. Effects of airborne black carbon pollution on maize

    NASA Astrophysics Data System (ADS)

    Illes, Bernadett; Anda, Angela; Soos, Gabor

    2013-04-01

    The black carbon (BC) changes the radiation balance of the Earth and contributes to global warming. The airborne BC deposited on the surface of plant, changing the radiation balance, water balance and the total dry matter (TDM) content of plant. The objective of our study was to investigate the impact of soot originated from motor vehicle exhaust on maize. The field experiment was carried out in Keszthely Agrometeorological Research Station (Hungary) in three consecutive years (2010, 2011, 2012) of growing season. The test plant was the maize hybrid Sperlona (FAO 340) with short growing season. The BC was chemically "pure", which means that it is free any contaminants (e.g. heavy metals). The BC was coming from the Hankook Tyre Company (Dunaújváros, Hungary), where used that for improve the wear resistance of tires. We used a motorised sprayer of SP 415 type to spray the BC onto the leaf surface. The leaf area index (LAI) was measured each week on the same 12 sample maize in each treatment using an LI 3000A automatic planimeter (LI-COR, Lincoln, NE). Albedo was measured by pyranometers of the CMA-11 type (Kipp & Zonen, Vaisala), what we placed the middle of the plot of 0.3 ha. The effects of BC were studied under two different water supplies: evapotranspirometers of Thornthwaite type were used for "ad libitum" treatment and rainfed treatment in field plots. In 2010 and 2012, a big difference was not observed in the case of LAI in the effects of BC. However, in 2011 there was a significant difference. The LAI of the BC polluted maize was higher (10-15%, P<0.05), than the LAI of the control maize in the rainfed plot and in the ET chambers, respectively. The albedo of the BC contaminated maize decreased (15-30%, P<0.05) in all three years. We also detected that the green plant surface of maize increased on BC contaminated treatment. These results may suggest that the plant is able to absorb the additional carbon source through the leaves. The albedo decreased

  8. Airborne Measurements in Support of the NASA Atmospheric Carbon and Transport - America (ACT-America) Mission

    NASA Technical Reports Server (NTRS)

    Meadows, Byron; Davis, Ken; Barrick, John; Browell, Edward; Chen, Gao; Dobler, Jeremy; Fried, Alan; Lauvaux, Thomas; Lin, Bing; McGill, Matt; Miles, Natasha; Nehrir, Amin; Obland, Michael; O'Dell, Chris; Sweeney, Colm; Yang, Melissa

    2015-01-01

    NASA announced the research opportunity Earth Venture Suborbital -2 (EVS-2) mission in support of the NASA's science strategic goals and objectives in 2013. Penn State University, NASA Langley Research Center (LaRC), and other academic institutions, government agencies, and industrial companies together formulated and proposed the Atmospheric Carbon and Transport -America (ACT -America) suborbital mission, which was subsequently selected for implementation. The airborne measurements that are part of ACT-America will provide a unique set of remote and in-situ measurements of CO2 over North America at spatial and temporal scales not previously available to the science community and this will greatly enhance our understanding of the carbon cycle. ACT -America will consist of five airborne campaigns, covering all four seasons, to measure regional atmospheric carbon distributions and to evaluate the accuracy of atmospheric transport models used to assess carbon sinks and sources under fair and stormy weather conditions. This coordinated mission will measure atmospheric carbon in the three most important regions of the continental US carbon balance: Northeast, Midwest, and South. Data will be collected using 2 airborne platforms (NASA Wallops' C-130 and NASA Langley's B-200) with both in-situ and lidar instruments, along with instrumented ground towers and under flights of the Orbiting Carbon Observatory (OCO-2) satellite. This presentation provides an overview of the ACT-America instruments, with particular emphasis on the airborne CO2and backscatter lidars, and the, rationale, approach, and anticipated results from this mission.

  9. Rates and quantities of carbon flux to ectomycorrhizal mycelium following 14C pulse labeling of Pinus sylvestris seedlings: effects of litter patches and interaction with a wood-decomposer fungus.

    PubMed

    Leake, J R; Donnelly, D P; Saunders, E M; Boddy, L; Read, D J

    2001-02-01

    We used a novel digital autoradiographic technique that enabled, for the first time, simultaneous visualization and quantification of spatial and temporal changes in carbon allocation patterns in ectomycorrhizal mycelia. Mycorrhizal plants of Pinus sylvestris L. were grown in microcosms containing non-sterile peat. The time course and spatial distribution of carbon allocation by P. sylvestris to mycelia of its mycorrhizal partners, Paxillus involutus (Batsch) Fr. and Suillus bovinus (L.): Kuntze, were quantified following 14C pulse labeling of the plants. Litter patches were used to investigate the effects of nutrient resource quality on carbon allocation. The wood-decomposer fungus Phanerochaete velutina (D.C.: Pers.) Parmasto was introduced to evaluate competitive and territorial interactions between its mycelial cords and the mycelial system of S. bovinus. Growth of ectomycorrhizal mycelium was stimulated in the litter patches. Nearly 60% of the C transferred from host plant to external mycorrhizal mycelium (> 2 mm from root surfaces) was allocated to mycelium in the patches, which comprised only 12% of the soil area available for mycelial colonization. Mycelia in the litter patch most recently colonized by mycorrhizal mycelium received the largest investment of carbon, amounting to 27 to 50% of the total 14C in external mycorrhizal mycelium. The amount of C transfer to external mycelium of S. bovinus following pulse labeling was reduced from a maximum of 167 nmol in systems with no saprotroph to a maximum of 61 nmol in systems interacting with P. velutina. The 14C content of S. bovinus mycelium reached a maximum 24-36 h after labeling in control microcosms, but allocation did not reach a peak until 56 h after labeling, when S. bovinus interacted with mycelium of P. velutina. The mycelium of S. bovinus contained 9% of the total 14C in the plants (including mycorrhizae) at the end of the experiment, but this was reduced to 4% in the presence of P. velutina. The

  10. 14C Fixation by Leaves and Leaf Cell Protoplasts of the Submerged Aquatic Angiosperm Potamogeton lucens: Carbon Dioxide or Bicarbonate? 1

    PubMed Central

    Staal, Marten; Elzenga, J. Theo M.; Prins, Hidde B. A.

    1989-01-01

    Protoplasts were isolated from leaves of the aquatic angiosperm Potamogeton lucens L. The leaves utilize bicarbonate as a carbon source for photosynthesis, and show polarity; that is, acidification of the periplasmic space of the lower, and alkalinization of the space near the upper leaf side. At present there are two models under consideration for this photosynthetic bicarbonate utilization process: conversion of bicarbonate into free carbon dioxide as a result of acidification and, second, a bicarbonate-proton symport across the plasma membrane. Carbon fixation of protoplasts was studied at different pH values and compared with that in leaf strips. Using the isotopic disequilibrium technique, it was established that carbon dioxide and not bicarbonate was the form in which DIC actually crossed the plasma membrane. It is concluded that there is probably no true bicarbonate transport system at the plasma membrane of these cells and that bicarbonate utilization in this species apparently rests on the conversion of bicarbonate into carbon dioxide. Experiments with acetazolamide, an inhibitor of periplasmic carbonic anhydrase, and direct measurements of carbonic anhydrase activity in intact leaves indicate that in this species the role of this enzyme for periplasmic conversion of bicarbonate into carbon dioxide is insignificant. PMID:16666848

  11. sup 14 C fixation by leaves and leaf cell protoplasts of the submerged aquatic angiosperm Potamogeton lucens: Carbon dioxide or bicarbonate

    SciTech Connect

    Staal, M.; Elzenga, J.T.M.; Prins, H.B.A. )

    1989-07-01

    Protoplasts were isolated from leaves of the aquatic angiosperm Potamogeton lucens L. The leaves utilize bicarbonate as a carbon source for photosynthesis, and show polarity; that is acidification of the periplasmic space of the lower, and alkalinization of the space near the upper leaf side. At present there are two models under consideration for this photosynthetic bicarbonate utilization process: conversion of bicarbonate into free carbon dioxide as a result of acidification and, second, a bicarbonate-proton symport across the plasma membrane. Carbon fixation of protoplasts was studied at different pH values and compared with that in leaf strips. Using the isotopic disequilibrium technique, it was established that carbon dioxide and not bicarbonate was the form in which DIC actually crossed the plasma membrane. It is concluded that there is probably no true bicarbonate transport system at the plasma membrane of these cells and that bicarbonate utilization in this species apparently rests on the conversion of bicarbonate into carbon dioxide. Experiments with acetazolamide, an inhibitor of periplasmic carbonic anhydrase, and direct measurements of carbonic anhydrase activity in intact leaves indicate that in this species the role of this enzyme for periplasmic conversion of bicarbonate into carbon dioxide is insignificant.

  12. 14C analysis via intracavity optogalvanic spectroscopy

    NASA Astrophysics Data System (ADS)

    Murnick, Daniel; Dogru, Ozgur; Ilkmen, Erhan

    2010-04-01

    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 CO 2 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 -1514C/ 12C ratios have been obtained with theoretical limits much lower. Using a 15 W 14CO 2 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 CO 2 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.

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

    PubMed

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

    2014-07-01

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

  14. ENVIRONMENTAL BIODEGRADABILITY OF [14C] SINGLE-WALLED CARBON NANOTUBESBY TRAMETES VERSICOLOR AND NATURAL MICROBIAL CULTURES FOUND IN NEWBEDFORD HARBOR SEDIMENT AND AERATED WASTEWATER TREATMENT PLANT SLUDGE

    EPA Science Inventory

    Little is known about environmental biodegradability or biotransformations of single-walled carbon nanotubes (SWNT). Because of their strong association with aquatic organic matter, detailed knowledge of the ultimate fate and persistence of SWNT requires investigation of possible...

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

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

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

  16. Tree-centric mapping of forest carbon density from airborne laser scanning and hyperspectral data.

    PubMed

    Dalponte, Michele; Coomes, David A

    2016-10-01

    Forests are a major component of the global carbon cycle, and accurate estimation of forest carbon stocks and fluxes is important in the context of anthropogenic global change. Airborne laser scanning (ALS) data sets are increasingly recognized as outstanding data sources for high-fidelity mapping of carbon stocks at regional scales.We develop a tree-centric approach to carbon mapping, based on identifying individual tree crowns (ITCs) and species from airborne remote sensing data, from which individual tree carbon stocks are calculated. We identify ITCs from the laser scanning point cloud using a region-growing algorithm and identifying species from airborne hyperspectral data by machine learning. For each detected tree, we predict stem diameter from its height and crown-width estimate. From that point on, we use well-established approaches developed for field-based inventories: above-ground biomasses of trees are estimated using published allometries and summed within plots to estimate carbon density.We show this approach is highly reliable: tests in the Italian Alps demonstrated a close relationship between field- and ALS-based estimates of carbon stocks (r(2) = 0·98). Small trees are invisible from the air, and a correction factor is required to accommodate this effect.An advantage of the tree-centric approach over existing area-based methods is that it can produce maps at any scale and is fundamentally based on field-based inventory methods, making it intuitive and transparent. Airborne laser scanning, hyperspectral sensing and computational power are all advancing rapidly, making it increasingly feasible to use ITC approaches for effective mapping of forest carbon density also inside wider carbon mapping programs like REDD++.

  17. Seasonal and snowmelt-driven changes in the water-extractable organic carbon dynamics in a cool-temperate Japanese forest soil, estimated using the bomb-(14)C tracer.

    PubMed

    Nakanishi, Takahiro; Atarashi-Andoh, Mariko; Koarashi, Jun; Saito-Kokubu, Yoko; Hirai, Keizo

    2014-02-01

    Water-extractable organic carbon (WEOC) in soil consists of a mobile and bioavailable portion of the dissolved organic carbon (DOC) pool. WEOC plays an important role in dynamics of soil organic carbon (SOC) and transport of radionuclides in forest soils. Although considerable research has been conducted on the importance of recent litter versus older soil organic matter as WEOC sources in forest soil, a more thorough evaluation of the temporal pattern of WEOC is necessary. We investigated the seasonal variation in WEOC in a Japanese cool-temperate beech forest soil by using the carbon isotopic composition ((14)C and (13)C) of WEOC as a tracer for the carbon sources. Our observations demonstrated that fresh leaf litter DOC significantly contributed to WEOC in May (35-52%) when the spring snowmelt occurred because of the high water flux and low temperature. In the rainy season, increases in the concentration of WEOC and the proportion of hydrophobic compounds were caused by high microbial activity under wetter conditions. From summer to autumn, the WEOC in the mineral soil horizons was also dominated by microbial release from SOC (>90%). These results indicate that the origin and dynamics of WEOC are strongly controlled by seasonal events such as the spring snowmelt and the rainy season's intense rainfall.

  18. Near Surface Leakage Monitoring for the Verification and Accounting of Geologic Carbon Sequestration Using a Field Ready {sup 14}C Isotopic Analyzer

    SciTech Connect

    Marino, Bruno

    2014-04-14

    Results for the development of a field ready multi-isotopic analyzer for {sup 12}CO{sub 2}, {sup 13}CO{sub 2} and {sup 14}CO{sub 2} and applications for carbon capture and storage (CCS) containment performance are described. A design goal of the field platform was to provide isotopic data with a high data rate, a standardized reference baseline and acceptable precision (e.g., ~ ±50 per mil D{sup 14}CO{sub 2}) for detection and quantification of fossil-fuel CO{sub 2} CCS leakage scenarios. The instrument platform was not designed to replace high precision accelerator mass spectrometry. An additional goal was to combine project scale isotopic data and associated fluxes with unique financial instruments linking CCS containment performance to a publicly traded security providing project revenue to stakeholders. While the primary goals of the project were attained additional work is needed for the instrument platform and deployment within a full scale CCS site that was not available during the project timeframe.

  19. 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

  20. A Novel Airborne Carbon Isotope Analyzer for Methane and Carbon Dioxide Source Fingerprinting

    NASA Astrophysics Data System (ADS)

    Berman, E. S.; Huang, Y. W.; Owano, T. G.; Leifer, I.

    2014-12-01

    Recent field studies on major sources of the important greenhouse gas methane (CH4) indicate significant underestimation of methane release from fossil fuel industrial (FFI) and animal husbandry sources, among others. In addition, uncertainties still exist with respect to carbon dioxide (CO2) measurements, especially source fingerprinting. CO2 isotopic analysis provides a valuable in situ measurement approach to fingerprint CH4 and CO2as associated with combustion sources, leakage from geologic reservoirs, or biogenic sources. As a result, these measurements can characterize strong combustion source plumes, such as power plant emissions, and discriminate these emissions from other sources. As part of the COMEX (CO2 and MEthane eXperiment) campaign, a novel CO2 isotopic analyzer was installed and collected data aboard the CIRPAS Twin Otter aircraft. Developing methods to derive CH4 and CO2 budgets from remote sensing data is the goal of the summer 2014 COMEX campaign, which combines hyperspectral imaging (HSI) and non-imaging spectroscopy (NIS) with in situ airborne and surface data. COMEX leverages the synergy between high spatial resolution HSI and moderate spatial resolution NIS. The carbon dioxide isotope analyzer developed by Los Gatos Research (LGR) uses LGR's patented Off-Axis ICOS (Integrated Cavity Output Spectroscopy) technology and incorporates proprietary internal thermal control for high sensitivity and optimal instrument stability. This analyzer measures CO2 concentration as well as δ13C, δ18O, and δ17O from CO2 at natural abundance (100-3000 ppm). The laboratory accuracy is ±1.2 ppm (1σ) in CO2 from 370-1000 ppm, with a long-term (1000 s) precision of ±0.012 ppm. The long-term precision for both δ13C and δ18O is 0.04 ‰, and for δ17O is 0.06 ‰. The analyzer was field-tested as part of the COWGAS campaign, a pre-cursor campaign to COMEX in March 2014, where it successfully discriminated plumes related to combustion processes associated with

  1. Double-Pulse Two-Micron IPDA Lidar Simulation for Airborne Carbon Dioxide Measurements

    NASA Technical Reports Server (NTRS)

    Refaat, Tamer F.; Singh, Upendra N.; Yu, Jirong; Petros, Mulugeta

    2015-01-01

    An advanced double-pulsed 2-micron integrated path differential absorption lidar has been developed at NASA Langley Research Center for measuring atmospheric carbon dioxide. The instrument utilizes a state-of-the-art 2-micron laser transmitter with tunable on-line wavelength and advanced receiver. Instrument modeling and airborne simulations are presented in this paper. Focusing on random errors, results demonstrate instrument capabilities of performing precise carbon dioxide differential optical depth measurement with less than 3% random error for single-shot operation from up to 11 km altitude. This study is useful for defining CO2 measurement weighting, instrument setting, validation and sensitivity trade-offs.

  2. 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

  3. A universal airborne LiDAR approach for tropical forest carbon mapping.

    PubMed

    Asner, Gregory P; Mascaro, Joseph; Muller-Landau, Helene C; Vieilledent, Ghislain; Vaudry, Romuald; Rasamoelina, Maminiaina; Hall, Jefferson S; van Breugel, Michiel

    2012-04-01

    Airborne light detection and ranging (LiDAR) is fast turning the corner from demonstration technology to a key tool for assessing carbon stocks in tropical forests. With its ability to penetrate tropical forest canopies and detect three-dimensional forest structure, LiDAR may prove to be a major component of international strategies to measure and account for carbon emissions from and uptake by tropical forests. To date, however, basic ecological information such as height-diameter allometry and stand-level wood density have not been mechanistically incorporated into methods for mapping forest carbon at regional and global scales. A better incorporation of these structural patterns in forests may reduce the considerable time needed to calibrate airborne data with ground-based forest inventory plots, which presently necessitate exhaustive measurements of tree diameters and heights, as well as tree identifications for wood density estimation. Here, we develop a new approach that can facilitate rapid LiDAR calibration with minimal field data. Throughout four tropical regions (Panama, Peru, Madagascar, and Hawaii), we were able to predict aboveground carbon density estimated in field inventory plots using a single universal LiDAR model (r ( 2 ) = 0.80, RMSE = 27.6 Mg C ha(-1)). This model is comparable in predictive power to locally calibrated models, but relies on limited inputs of basal area and wood density information for a given region, rather than on traditional plot inventories. With this approach, we propose to radically decrease the time required to calibrate airborne LiDAR data and thus increase the output of high-resolution carbon maps, supporting tropical forest conservation and climate mitigation policy.

  4. Flux Of Carbon from an Airborne Laboratory (FOCAL): Synergy of airborne and surface measures of carbon emission and isotopologue content from tundra landscape in Alaska

    NASA Astrophysics Data System (ADS)

    Dobosy, R.; Dumas, E.; Sayres, D. S.; Kochendorfer, J.

    2013-12-01

    Arctic tundra, recognized as a potential major source of new atmospheric carbon, is characterized by low topographic relief and small-scale heterogeneity consisting of small lakes and intervening tundra vegetation. This fits well the flux-fragment method (FFM) of analysis of data from low-flying aircraft. The FFM draws on 1)airborne eddy-covariance flux measurements, 2)a classified surface-characteristics map (e.g. open water vs tundra), 3)a footprint model, and 4)companion surface-based eddy-covariance flux measurements. The FOCAL, a collaboration among Harvard University's Anderson Group, NOAA's Atmospheric Turbulence and Diffusion Division (ATDD), and Aurora Flight Sciences, Inc., made coordinated flights in 2013 August with a collaborating surface site. The FOCAL gathers not only flux data for CH4 and CO2 but also the corresponding carbon-isotopologue content of these gases. The surface site provides a continuous sample of carbon flux from interstitial tundra over time throughout the period of the campaign. The FFM draws samples from the aircraft data over many instances of tundra and also open water. From this we will determine how representative the surface site is of the larger area (100 km linear scale), and how much the open water differs from the tundra as a source of carbon.

  5. Comparison between carbon monoxide measurements from spaceborne and airborne platforms

    NASA Technical Reports Server (NTRS)

    Connors, V. S.; Cahoon, D. R.; Reichle, H. G., Jr.; Scheel, H. E.

    1991-01-01

    The measurements of air pollution from satellites (MAPS) experiment measured the distribution of middle tropospheric carbon monoxide (CO) from the Space Shuttle during October 1984. A critical area of the experiment is the assessment of experimental error of the MAPS data. This error is determined by the comparison between the space-based CO data and concurrent, direct CO measurements taken aboard aircraft. Because of the variability in the CO measurements near land sources, a strategy for comparing the tropospheric CO measurements over the remote oceans is presented.

  6. Brown Carbon: Results From Ground and Airborne Studies

    NASA Astrophysics Data System (ADS)

    Weber, R. J.; Forrister, H.; Liu, J.; Nenes, A.

    2015-12-01

    Brown carbon (BrC) is directly measured with high sensitivity by isolating it from black carbon in aerosol extracts and using long path wave-guide spectrophotometry. Ambient measurements by this approach show that BrC is pervasive and can be found in almost all locations, ranging from urban environments to remote continental sites and upper reaches of the free troposphere. Biomass burning appears to be the major source in many urban and rural locations, but other sources of incomplete combustion, such as vehicle emissions in urban environments also play a role. Secondary aerosols not associated with combustion sources may also contribute, but are likely of lesser importance. Studies of ambient wildfire smoke plumes show that BrC levels decrease as it ages, with a half-life of approximately 10 hours. However, a small fraction of the emitted BrC is stable and may account for much of the BrC observed throughout the atmosphere due to widely dispersed and ubiquitous smoke. A radiative transfer model indicates that this background BrC reduced US continental TOA forcing by 20 percent. Human health studies point to similar chemical components linked to BrC (i.e., HULIS), of this same ubiquitous smoke, as a significant source of adverse cardiorespiratory effects. This talk will summarize findings on BrC sources, transformations and estimates of environmental effects based on bulk measurements.

  7. Metabolism of [1-14C]glyoxylate, [1-14C]-glycollate, [1-14C]glycine and [2-14C]-glycine by homogenates of kidney and liver tissue from hyperoxaluric and control subjects

    PubMed Central

    Dean, Betty M.; Watts, R. W. E.; Westwick, Wendy J.

    1967-01-01

    1. The metabolism of [1-14C]glyoxylate to carbon dioxide, glycine, oxalate, serine, formate and glycollate was investigated in hyperoxaluric and control subjects' kidney and liver tissue in vitro. 2. Only glycine and carbon dioxide became significantly labelled with 14C, and this was less in the hyperoxaluric patients' kidney tissue than in the control tissue. 3. Liver did not show this difference. 4. The metabolism of [1-14C]glycollate was also studied in the liver tissue; glyoxylate formation was demonstrated and the formation of 14CO2 from this substrate was likewise unimpaired in the hyperoxaluric patients' liver tissue in these experiments. 5. Glycine was not metabolized by human kidney, liver or blood cells under the conditions used. 6. These observations show that glyoxylate metabolism by the kidney is impaired in primary hyperoxaluria. PMID:5584012

  8. 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.

  9. Campaign datasets for ARM Airborne Carbon Measurements (ARM-ACME-V)

    SciTech Connect

    Biraud,Sebastien; Mei,Fan; Flynn,Connor; Hubbe,John; Long,Chuck; Matthews,Alyssa; Pekour,Mikhail; Sedlacek,Arthur; Springston,Stephen; Tomlinson,Jason; Chand,Duli

    2016-03-15

    Atmospheric temperatures are warming faster in the Arctic than predicted by climate models. The impact of this warming on permafrost degradation is not well understood, but it is projected to increase carbon decomposition and greenhouse gas production (CO2 and/or CH4) by arctic ecosystems. Airborne observations of atmospheric trace gases, aerosols, and cloud properties at the North Slope of Alaska are improving our understanding of global climate, with the goal of reducing the uncertainty in global and regional climate simulations and projections.

  10. Taking Stock of Circumboreal Forest Carbon With Ground Measurements, Airborne and Spaceborne LiDAR

    NASA Technical Reports Server (NTRS)

    Neigh, Christopher S. R.; Nelson, Ross F.; Ranson, K. Jon; Margolis, Hank A.; Montesano, Paul M.; Sun, Guoqing; Kharuk, Viacheslav; Naesset, Erik; Wulder, Michael A.; Andersen, Hans-Erik

    2013-01-01

    The boreal forest accounts for one-third of global forests, but remains largely inaccessible to ground-based measurements and monitoring. It contains large quantities of carbon in its vegetation and soils, and research suggests that it will be subject to increasingly severe climate-driven disturbance. We employ a suite of ground-, airborne- and space-based measurement techniques to derive the first satellite LiDAR-based estimates of aboveground carbon for the entire circumboreal forest biome. Incorporating these inventory techniques with uncertainty analysis, we estimate total aboveground carbon of 38 +/- 3.1 Pg. This boreal forest carbon is mostly concentrated from 50 to 55degN in eastern Canada and from 55 to 60degN in eastern Eurasia. Both of these regions are expected to warm >3 C by 2100, and monitoring the effects of warming on these stocks is important to understanding its future carbon balance. Our maps establish a baseline for future quantification of circumboreal carbon and the described technique should provide a robust method for future monitoring of the spatial and temporal changes of the aboveground carbon content.

  11. Two distinct patterns of seasonal variation of airborne black carbon over Tibetan Plateau.

    PubMed

    Wang, Mo; Xu, Baiqing; Wang, Ninglian; Cao, Junji; Tie, Xuexi; Wang, Hailong; Zhu, Chongshu; Yang, Wei

    2016-12-15

    Airborne black carbon (BC) mass concentrations were measured from November 2012 to June 2013 at Ranwu and Beiluhe, located in the southeastern and central Tibetan Plateau, respectively. Monthly mean BC concentrations show a winter (November-February) high (413.2ngm(-3)) and spring (March-June) low (139.1ngm(-3)) at Ranwu, but in contrast a winter low and spring high at Beiluhe (204.8 and 621.6ngm(-3), respectively). By examining the meteorological conditions at various scales, we found that the monthly variation of airborne BC over the southeastern Tibetan Plateau (TP) was highly influenced by regional precipitation and over the hinterland by winds. Local precipitation at both sites showed little impact on the seasonal variation of airborne BC concentrations. Potential BC source regions are identified using air mass backward trajectory analysis. At Ranwu, BC was dominated by the air masses from the northeastern India and Bangladesh in both winter and spring, whereas at Beiluhe it was largely contributed by air masses from the south slope of Himalayas in winter, and from the arid region in the north of the TP in spring. The winter and spring seasonal peak of BC in the southern TP is largely contributed by emissions from South Asia, and this seasonal variation is heavily influenced by the regional monsoon. In the northern TP, BC had high concentrations during spring and summer seasons, which is very likely associated with more efficient transport of BC over the arid regions on the north of Tibetan Plateau and in Central Asia. Airborne BC concentrations at the Ranwu sampling site showed a significant diurnal cycle with a peak shortly after sunrise followed by a decrease before noon in both winter and spring, likely shaped by local human activities and the diurnal variation of wind speed. At the Beiluhe sampling site, the diurnal variation of BC is different and less distinct.

  12. Two distinct patterns of seasonal variation of airborne black carbon over Tibetan Plateau

    SciTech Connect

    Wang, Mo; Xu, Baiqing; Wang, Ninglian; Cao, Junji; Tie, Xuexi; Wang, Hailong; Zhu, Chongshu; Yang, Wei

    2016-12-01

    Airborne black carbon (BC) mass concentrations were measured from November 2012 to June 2013 at Ranwu and Beiluhe, located in the southeastern and central Tibetan Plateau, respectively. Monthly mean BC concentrations showawinter (November–February) high (413.2 ng m$-$3) and spring (March–June) low(139.1 ng m$-$3) at Ranwu, but in contrast awinter lowand spring high at Beiluhe (204.8 and 621.6 ng m$-$3, respectively). By examining the meteorological conditions at various scales, we found that themonthly variation of airborne BC over the southeastern Tibetan Plateau (TP) was highly influenced by regional precipitation and over the hinterland by winds. Local precipitation at both sites showed little impact on the seasonal variation of airborne BC concentrations. Potential BC source regions are identified using air mass backward trajectory analysis. At Ranwu, BC was dominated by the air masses from the northeastern India and Bangladesh in both winter and spring, whereas at Beiluhe it was largely contributed by air masses from the south slope of Himalayas in winter, and from the arid region in the north of the TP in spring. Thewinter and spring seasonal peak of BC in the southern TP is largely contributed by emissions from South Asia, and this seasonal variation is heavily influenced by the regional monsoon. In the northern TP, BC had high concentrations during spring and summer seasons, which is very likely associated with more efficient transport of BC over the arid regions on the north of Tibetan Plateau and in Central Asia. Airborne BC concentrations at the Ranwusampling site showed a significant diurnal cyclewith a peak shortly after sunrise followed by a decrease before noon in both winter and spring, likely shaped by local human activities and the diurnal variation of wind speed. At the Beiluhe sampling site, the diurnal variation of BC is different and less distinct.

  13. Estimating 14C groundwater ages in a methanogenic aquifer

    USGS Publications Warehouse

    Aravena, Ramon; Wassenaar, Leonard I; Plummer, L. Niel

    1995-01-01

    This paper addresses the problem of 14C age dating of groundwaters in a confined regional aquifer affected by methanogenesis. Increasing CH4 concentrations along the groundwater flow system and 13C and 14C isotopic data for dissolved inorganic carbon, dissolved organic carbon, and CH4 clearly show the effect of methanogenesis on groundwater chemistry. Inverse reaction path modeling using NETPATH indicates the predominant geochemical reactions controlling the chemical evolution of groundwater in the aquifer are incongruent dissolution of dolomite, ion exchange, methanogenesis, and oxidation of sedimentary organic matter. Modeling of groundwater 14C ages using NETPATH indicates that a significant part of groundwater in the Alliston aquifer is less than 13,000 years old; however, older groundwater in the range of 15,000–23,000 years is also present in the aquifer. This paper demonstrates that 14C ages calculated using NETPATH, incorporating the effects of methanogenesis on the carbon pools, provide reasonable groundwater ages that were not possible by other isotopic methods.

  14. Detection of airborne carbon nanotubes based on the reactivity of the embedded catalyst.

    PubMed

    Neubauer, N; Kasper, G

    2015-01-01

    A previously described method for detecting catalyst particles in workplace air((1,2)) was applied to airborne carbon nanotubes (CNT). It infers the CNT concentration indirectly from the catalytic activity of metallic nanoparticles embedded as part of the CNT production process. Essentially, one samples airborne CNT onto a filter enclosed in a tiny chemical reactor and then initiates a gas-phase catalytic reaction on the sample. The change in concentration of one of the reactants is then determined by an IR sensor as measure of activity. The method requires a one-point calibration with a CNT sample of known mass. The suitability of the method was tested with nickel containing (25 or 38% by weight), well-characterized multi-walled CNT aerosols generated freshly in the lab for each experiment. Two chemical reactions were investigated, of which the oxidation of CO to CO2 at 470°C was found to be more effective, because nearly 100% of the nickel was exposed at that temperature by burning off the carbon, giving a linear relationship between CO conversion and nickel mass. Based on the investigated aerosols, a lower detection limit of 1 μg of sampled nickel was estimated. This translates into sampling times ranging from minutes to about one working day, depending on airborne CNT concentration and catalyst content, as well as sampling flow rate. The time for the subsequent chemical analysis is on the order of minutes, regardless of the time required to accumulate the sample and can be done on site.

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

    SciTech Connect

    Brand, B.; Boos, W. )

    1989-09-01

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

  16. 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.

  17. Airborne Carbon Dioxide Laser Absorption Spectrometer for IPDA Measurements of Tropospheric CO2: Recent Results

    NASA Technical Reports Server (NTRS)

    Spiers, Gary D.; Menzies, Robert T.

    2008-01-01

    The National Research Council's decadal survey on Earth Science and Applications from Space[1] recommended the Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) mission for launch in 2013-2016 as a logical follow-on to the Orbiting Carbon Observatory (OCO) which is scheduled for launch in late 2008 [2]. The use of a laser absorption measurement technique provides the required ability to make day and night measurements of CO2 over all latitudes and seasons. As a demonstrator for an approach to meeting the instrument needs for the ASCENDS mission we have developed the airborne Carbon Dioxide Laser Absorption Spectrometer (CO2LAS) which uses the Integrated Path Differential Absorption (IPDA) Spectrometer [3] technique operating in the 2 micron wavelength region.. During 2006 a short engineering checkout flight of the CO2LAS was conducted and the results presented previously [4]. Several short flight campaigns were conducted during 2007 and we report results from these campaigns.

  18. Double-Pulse Two-micron LPDA Lidar Simulation for Airborne Carbon Dioxide Measurements

    NASA Astrophysics Data System (ADS)

    Refaat, Tamer F.; Singh, Upendra N.; Yu, Jirong; Petros, Mulugeta

    2016-06-01

    An advanced double-pulse 2-μm integrated path differential absorption lidar has been developed at NASA Langley Research Center for measuring atmospheric carbon dioxide. The instrument utilizes a state-of-the-art 2-μm laser transmitter with tunable on-line wavelength and advanced receiver. Instrument modeling and airborne simulations are presented in this paper. Focusing on random errors, results demonstrate instrument capabilities of performing precise carbon dioxide differential optical depth measurement with less than 3% random error for single-shot operation up to 11 km altitude. This study is useful for defining CO2 measurement weighting function for adaptive targeting, instrument setting, validation and sensitivity trade-offs.

  19. Exposure assessment to airborne endotoxin, dust, ammonia, hydrogen sulfide and carbon dioxide in open style swine houses.

    PubMed

    Chang, C W; Chung, H; Huang, C F; Su, H J

    2001-08-01

    Information is limited for the exposure levels of airborne hazardous substances in swine feed buildings that are not completely enclosed. Open-style breeding, growing and finishing swine houses in six farms in subtropical Taiwan were studied for the airborne concentrations of endotoxin, dust, ammonia, hydrogen sulfide and carbon dioxide. The air in the farrowing and nursery stalls as partially enclosed was also simultaneously evaluated. Three selected gases and airborne dusts were quantified respectively by using Drager diffusion tubes and a filter-weighing method. Endotoxin was analyzed by the Limulus amoebocyte lysate assay. Average concentration of airborne total endotoxin among piggeries was between 36.8 and 298 EU/m(3), while that for respirable endotoxin was 14.1-129 EU/m(3). Mean concentration of total dust was between 0.15 and 0.34 mg/m(3), with average level of respirable dust of 0.14 mg/m(3). The respective concentrations of NH3, CO2 and H2S were less than 5 ppm, 600-895 ppm and less than 0.2 ppm. Airborne concentrations of total dust and endotoxin in the nursery house were higher than in the other types of swine houses. The finishing house presented the highest exposure risk to NH3, CO2 and H2S. Employees working in the finishing stalls were also exposed to the highest airborne levels of respirable endotoxin and dust. On the other hand, the air of the breeding units was the least contaminated in terms of airborne endotoxin, dust, NH3, CO2 and H2S. The airborne concentrations of substances measured in the present study were all lower than most of published studies conducted in mainly enclosed swine buildings. Distinct characteristics, including maintaining swine houses in an open status and frequent spraying water inside the stalls, significantly reduce accumulation of gases and airborne particulates.

  20. Peat Depth Assessment Using Airborne Geophysical Data for Carbon Stock Modelling

    NASA Astrophysics Data System (ADS)

    Keaney, Antoinette; McKinley, Jennifer; Ruffell, Alastair; Robinson, Martin; Graham, Conor; Hodgson, Jim; Desissa, Mohammednur

    2013-04-01

    The Kyoto Agreement demands that all signatory countries have an inventory of their carbon stock, plus possible future changes to this store. This is particularly important for Ireland, where some 16% of the surface is covered by peat bog. Estimates of soil carbon stores are a key component of the required annual returns made by the Irish and UK governments to the Intergovernmental Panel on Climate Change. Saturated peat attenuates gamma-radiation from underlying rocks. This effect can be used to estimate the thickness of peat, within certain limits. This project examines this relationship between peat depth and gamma-radiation using airborne geophysical data generated by the Tellus Survey and newly acquired data collected as part of the EU-funded Tellus Border project, together encompassing Northern Ireland and the border area of the Republic of Ireland. Selected peat bog sites are used to ground truth and evaluate the use of airborne geophysical (radiometric and electromagnetic) data and validate modelled estimates of soil carbon, peat volume and depth to bedrock. Data from two test line sites are presented: one in Bundoran, County Donegal and a second line in Sliabh Beagh, County Monaghan. The plane flew over these areas at different times of the year and at a series of different elevations allowing the data to be assessed temporally with different soil/peat saturation levels. On the ground these flight test lines cover varying surface land use zones allowing future extrapolation of data from the sites. This research applies spatial statistical techniques, including uncertainty estimation in geostatistical prediction and simulation, to investigate and model the use of airborne geophysical data to examine the relationship between reduced radioactivity and peat depth. Ground truthing at test line locations and selected peat bog sites involves use of ground penetrating radar, terrestrial LiDAR, peat depth probing, magnetometry, resistivity, handheld gamma

  1. 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.

  2. Mapping Above- and Below-Ground Carbon Pools in Boreal Forests: The Case for Airborne Lidar

    PubMed Central

    Kristensen, Terje; Næsset, Erik; Ohlson, Mikael; Bolstad, Paul V.; Kolka, Randall

    2015-01-01

    A large and growing body of evidence has demonstrated that airborne scanning light detection and ranging (lidar) systems can be an effective tool in measuring and monitoring above-ground forest tree biomass. However, the potential of lidar as an all-round tool for assisting in assessment of carbon (C) stocks in soil and non-tree vegetation components of the forest ecosystem has been given much less attention. Here we combine the use airborne small footprint scanning lidar with fine-scale spatial C data relating to vegetation and the soil surface to describe and contrast the size and spatial distribution of C pools within and among multilayered Norway spruce (Picea abies) stands. Predictor variables from lidar derived metrics delivered precise models of above- and below-ground tree C, which comprised the largest C pool in our study stands. We also found evidence that lidar canopy data correlated well with the variation in field layer C stock, consisting mainly of ericaceous dwarf shrubs and herbaceous plants. However, lidar metrics derived directly from understory echoes did not yield significant models. Furthermore, our results indicate that the variation in both the mosses and soil organic layer C stock plots appears less influenced by differences in stand structure properties than topographical gradients. By using topographical models from lidar ground returns we were able to establish a strong correlation between lidar data and the organic layer C stock at a stand level. Increasing the topographical resolution from plot averages (~2000 m2) towards individual grid cells (1 m2) did not yield consistent models. Our study demonstrates a connection between the size and distribution of different forest C pools and models derived from airborne lidar data, providing a foundation for future research concerning the use of lidar for assessing and monitoring boreal forest C. PMID:26426532

  3. Mapping Above- and Below-Ground Carbon Pools in Boreal Forests: The Case for Airborne Lidar.

    PubMed

    Kristensen, Terje; Næsset, Erik; Ohlson, Mikael; Bolstad, Paul V; Kolka, Randall

    2015-01-01

    A large and growing body of evidence has demonstrated that airborne scanning light detection and ranging (lidar) systems can be an effective tool in measuring and monitoring above-ground forest tree biomass. However, the potential of lidar as an all-round tool for assisting in assessment of carbon (C) stocks in soil and non-tree vegetation components of the forest ecosystem has been given much less attention. Here we combine the use airborne small footprint scanning lidar with fine-scale spatial C data relating to vegetation and the soil surface to describe and contrast the size and spatial distribution of C pools within and among multilayered Norway spruce (Picea abies) stands. Predictor variables from lidar derived metrics delivered precise models of above- and below-ground tree C, which comprised the largest C pool in our study stands. We also found evidence that lidar canopy data correlated well with the variation in field layer C stock, consisting mainly of ericaceous dwarf shrubs and herbaceous plants. However, lidar metrics derived directly from understory echoes did not yield significant models. Furthermore, our results indicate that the variation in both the mosses and soil organic layer C stock plots appears less influenced by differences in stand structure properties than topographical gradients. By using topographical models from lidar ground returns we were able to establish a strong correlation between lidar data and the organic layer C stock at a stand level. Increasing the topographical resolution from plot averages (~2000 m2) towards individual grid cells (1 m2) did not yield consistent models. Our study demonstrates a connection between the size and distribution of different forest C pools and models derived from airborne lidar data, providing a foundation for future research concerning the use of lidar for assessing and monitoring boreal forest C.

  4. 14C content in aerosols in Mexico City

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  5. Relating urban airborne particle concentrations to shipping using carbon based elemental emission ratios

    NASA Astrophysics Data System (ADS)

    Johnson, Graham R.; Juwono, Alamsyah M.; Friend, Adrian J.; Cheung, Hing-Cho; Stelcer, Eduard; Cohen, David; Ayoko, Godwin A.; Morawska, Lidia

    2014-10-01

    This study demonstrates a novel method for testing the hypothesis that variations in primary and secondary particle number concentration (PNC) in urban air are related to residual fuel oil combustion at a coastal port lying 30 km upwind, by examining the correlation between PNC and airborne particle composition signatures chosen for their sensitivity to the elemental contaminants present in residual fuel oil. Residual fuel oil combustion indicators were chosen by comparing the sensitivity of a range of concentration ratios to airborne emissions originating from the port. The most responsive were combinations of vanadium and sulphur concentration ([S], [V]) expressed as ratios with respect to black carbon concentration ([BC]). These correlated significantly with ship activity at the port and with the fraction of time during which the wind blew from the port. The average [V] when the wind was predominantly from the port was 0.52 ng m-3 (87%) higher than the average for all wind directions and 0.83 ng m-3 (280%) higher than that for the lowest vanadium yielding wind direction considered to approximate the natural background. Shipping was found to be the main source of V impacting urban air quality in Brisbane. However, contrary to the stated hypothesis, increases in PNC related measures did not correlate with ship emission indicators or ship traffic. Hence at this site ship emissions were not found to be a major contributor to PNC compared to other fossil fuel combustion sources such as road traffic, airport and refinery emissions.

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

    PubMed

    Yin, Jinhui; Yang, Xue; Zheng, Yonggang

    2014-10-07

    Several attempts have been made to directly date phytoliths, but most (14)C 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 (14)C 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 (14)C age. Our results show that the (14)C 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 (14)C.

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

    NASA Astrophysics Data System (ADS)

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

    2011-05-01

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

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

    SciTech Connect

    Norris, D.M.

    1980-08-01

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

  9. Quantitative measurement of the L-type pentose phosphate cycle with [2-14C]glucose and [5-14C]glucose in isolated hepatocytes.

    PubMed Central

    Longenecker, J P; Williams, J F

    1980-01-01

    1. Investigations of the mechanism of the non-oxidative segment of the pentose phosphate cycle in isolatd hepatocytes by prediction-labelling studies following the metabolism of [2-14C]-, [5-14C]- and [4,5,6-14C]glucose are reported. The 14C distribution patterns in glucose 6-phosphate show that the reactions of the L-type pentose pathway in hepatocytes. 2. Estimates of the quantitative contribution of the L-type pentose cycle are the exclusive form of the pentose cycle to glucose metabolism have been made. The contribution of the L-type pentose cycle to the metabolism of glucose lies between 22 and 30% in isolated hepatocytes. 3. The distribution of 14C in the carbon atoms of glucose 6-phosphate following the metabolism of [4,5,6-14C]- and [2-14C]glucose indicate that gluconeogenesis from triose phosphate and non-oxidative formation of pentose 5-phosphate do not contribute significantly to randomization of 14C in isolated hepatocytes. The transaldolase exchange reaction between fructose 6-phosphate and glyceraldehyde 3-phosphate is very active in these cells. PMID:7470039

  10. Airborne radioactivity survey of the Miller Hill area, Carbon county, Wyoming

    USGS Publications Warehouse

    Meuschke, J.L.; Moxham, R.M.

    1953-01-01

    The accompanying map shows the results of an airborne radioactivity survey covering 65 square miles northwest of Miller Hill, Carbon county, Wyoming. The survey was made by the U.S. Geological Survey as part of a cooperative program with the U.S. Atomic Energy Commission. At 500 feet above the ground, the width of the zone from which anomalous radioactivity is measured varies with the intensity of radiation of the source and, for strong sources, the width would be as much as 1,400 feet. Quarter-mile spacing of the flight paths of the aircraft should be adequate to detect anomalies from strong sources of radioactivity. However, small areas of considerable radioactivity midway between flight paths may not be noted. The approximate location of each radioactivity anomaly is shown on the accompanying map. The plotted position of an anomaly may be in error by as much as a quarter of a mile owing to errors in the available base maps up to several square miles in which it is impossible to find and plot recognizable landmarks. The radioactivity anomalies shown on the accompanying map cannot be interpreted in terms of either the radioactive content or the extent of the source materials. The present technique of airborne radioactivity measurement does not permit distinguishing between activity due to thorium and that due to uranium. An anomaly, therefore, may represent radioactivity due entirely to uranium, or to thorium, or to a combination of uranium and thorium. The radioactivity that is recorded by airborne measurements at 500 feet above the ground can be caused by: 1. A moderately large area in which the rocks and soils are slightly more radioactive than the rocks and soils of the surrounding area. 2. A smaller area in which the rocks and soils are considerably more radioactive than rocks and soils in the surrounding area. 3. A very small area in which to rocks and soils are much more radioactive than the rocks and soils of the surrounding area. Any particular anomaly

  11. Extraction of in situ cosmogenic 14C from olivine

    USGS Publications Warehouse

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

    2010-01-01

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

  12. Characterization and Control of Airborne Particles Emitted During Production of Epoxy / Carbon Nanotube Nanocomposites

    PubMed Central

    Cena, Lorenzo G.; Peters, Thomas M.

    2016-01-01

    This work characterized airborne particles that were generated from the weighing of bulk, multi-wall carbon nanotubes (CNTs) and the manual sanding of epoxy test samples reinforced with CNTs. It also evaluated the effectiveness of three local exhaust ventilation (LEV) conditions (no LEV, custom fume hood, and biosafety cabinet) for control of particles generated during sanding of CNT-epoxy nanocomposites. Particle number and respirable mass concentrations were measured using an optical particle counter (OPC) and a condensation particle counter (CPC), and particle morphology was assessed by transmission electron microscopy. The ratios of the geometric mean (GM) concentrations measured during the process to that measured in the background (P/B ratios) were used as indices of the impact of the process and the LEVs on observed concentrations. Processing CNT-epoxy nanocomposites materials released respirable size airborne particles (P/B ratio: weighing = 1.79; sanding = 5.90) but generally no nanoparticles (P/B ratiô1). The particles generated during sanding were predominately micron-sized with protruding CNTs and very different from bulk CNTs that tended to remain in large (>1 μm) tangled clusters. Respirable mass concentrations in the operator’s breathing zone were lower when sanding was performed in the biological safety cabinet (GM = 0.20 μg/m3) compared to those with no LEV (GM = 2.68 μg/m3) or those when sanding was performed inside the fume hood (GM = 21.4 μg/m3; p-value < 0.0001). The poor performance of the custom fume hood used in this study may have been exacerbated by its lack of a front sash and rear baffles and its low face velocity (0.39 m/sec). PMID:21253981

  13. Airborne sulfur trace species intercomparison campaign: Sulfur dioxide, dimethylsulfide, hydrogen sulfide, carbon disulfide, and carbonyl sulfide

    NASA Technical Reports Server (NTRS)

    Gregory, Gerald L.; Hoell, James M., Jr.; Davis, Douglas D.

    1991-01-01

    Results from an airborne intercomparison of techniques to measure tropospheric levels of sulfur trace gases are presented. The intercomparison was part of the NASA Global Tropospheric Experiment (GTE) and was conducted during the summer of 1989. The intercomparisons were conducted on the Wallops Electra aircraft during flights from Wallops Island, Virginia, and Natal, Brazil. Sulfur measurements intercompared included sulfur dioxide (SO2), dimethylsulfide (DMS), hydrogen sulfide (H2S), carbon disulfide (CS2), and carbonyl sulfide (OCS). Measurement techniques ranged from filter collection systems with post-flight analyses to mass spectrometer and gas chromatograph systems employing various methods for measuring and identifying the sulfur gases during flight. Sampling schedules for the techniques ranged from integrated collections over periods as long as 50 minutes to one- to three-minute samples every ten or fifteen minutes. Several of the techniques provided measurements of more than one sulfur gas. Instruments employing different detection principles were involved in each of the sulfur intercomparisons. Also included in the intercomparison measurement scenario were a host of supporting measurements (i.e., ozone, nitrogen oxides, carbon monoxide, total sulfur, aerosols, etc.) for purposes of: (1) interpreting results (i.e., correlation of any noted instrument disagreement with the chemical composition of the measurement environment); and (2) providing supporting chemical data to meet CITE-3 science objectives of studying ozone/sulfur photochemistry, diurnal cycles, etc. The results of the intercomparison study are briefly discussed.

  14. Making Carbon Emissions Remotely Sensible: Flux Observations of Carbon from an Airborne Laboratory (FOCAL), its Near-Surface Survey of Carbon Gases and Isotopologues on Alaska's North Slope

    NASA Astrophysics Data System (ADS)

    Dobosy, R.; Dumas, E. J.; Sayres, D. S.; Healy, C. E.; Munster, J. B.; Baker, B.; Anderson, J. G.

    2014-12-01

    Detailed process-oriented study of the mechanisms of conversion in the Arctic of fossil carbon to atmospheric gas is progressing, but necessarily limited to a few point locations and requiring detailed subsurface measurements inaccessible to remote sensing. Airborne measurements of concentration, transport and flux of these carbon gases at sufficiently low altitude to reflect surface variations can tie such local measurements to remotely observable features of the landscape. Carbon dioxide and water vapor have been observable for over 20 years from low-altitude small aircraft in the Arctic and elsewhere. Methane has been more difficult, requiring large powerful aircraft or limited flask samples. Recent developments in spectroscopy, however, have reduced the power and weight required to measure methane at rates suitable for eddy-covariance flux estimates. The Flux Observations of Carbon from an Airborne Laboratory (FOCAL) takes advantage of Integrated Cavity-Output Spectroscopy (ICOS) to measure CH4, CO2, and water vapor in a new airborne system. The system, moreover, measures these gases' stable isotopologues every two seconds or faster helping to separate thermogenic from biogenic emissions. Paired with the Best Airborne Turbulence (BAT) probe developed for small aircraft by NOAA's Air Resources Laboratory and a light twin-engine aircraft adapted by Aurora Flight Sciences Inc., the FOCAL measures at 6 m spacing, covering 100 km in less than 30 minutes. It flies between 10 m and 50 m above ground interspersed with profiles to the top of the boundary layer and beyond. This presentation gives an overview of the magnitude and variation in fluxes and concentrations of CH4, CO2, and H2O with space, time, and time of day in a spatially extensive survey, more than 7500 km total in 15 flights over roughly a 100 km square during the month of August 2013. An extensive data set such as this at low altitude with high-rate sampling addresses features that repeat on 1 km scale

  15. Improving estimation of tree carbon stocks by harvesting aboveground woody biomass within airborne LiDAR flight areas

    NASA Astrophysics Data System (ADS)

    Colgan, M.; Asner, G. P.; Swemmer, A. M.

    2011-12-01

    The accurate estimation of carbon stored in a tree is essential to accounting for the carbon emissions due to deforestation and degradation. Airborne LiDAR (Light Detection and Ranging) has been successful in estimating aboveground carbon density (ACD) by correlating airborne metrics, such as canopy height, to field-estimated biomass. This latter step is reliant on field allometry which is applied to forest inventory quantities, such as stem diameter and height, to predict the biomass of a given tree stem. Constructing such allometry is expensive, time consuming, and requires destructive sampling. Consequently, the sample sizes used to construct such allometry are often small, and the largest tree sampled is often much smaller than the largest in the forest population. The uncertainty resulting from these sampling errors can lead to severe biases when the allometry is applied to stems larger than those harvested to construct the allometry, which is then subsequently propagated to airborne ACD estimates. The Kruger National Park (KNP) mission of maintaining biodiversity coincides with preserving ecosystem carbon stocks. However, one hurdle to accurately quantifying carbon density in savannas is that small stems are typically harvested to construct woody biomass allometry, yet they are not representative of Kruger's distribution of biomass. Consequently, these equations inadequately capture large tree variation in sapwood/hardwood composition, root/shoot/leaf allocation, branch fall, and stem rot. This study eliminates the "middleman" of field allometry by directly measuring, or harvesting, tree biomass within the extent of airborne LiDAR. This enables comparisons of field and airborne ACD estimates, and also enables creation of new airborne algorithms to estimate biomass at the scale of individual trees. A field campaign was conducted at Pompey Silica Mine 5km outside Kruger National Park, South Africa, in Mar-Aug 2010 to harvest and weigh tree mass. Since

  16. Mapping Forest Carbon by Fusing Terrestrial and Airborne LiDAR Datasets

    NASA Astrophysics Data System (ADS)

    Stovall, A. E.

    2015-12-01

    The storage and flux of terrestrial carbon (C) is one of the largest and most uncertain components of the global C budget, the vast majority of which is held within the biomass of the world's forests. However, the spatial distribution and quantification of forest C remains difficult to measure on a large scale. Remote sensing of forests with airborne LiDAR has proven to be an extremely effective method of bridging the gap between data from plot-level forestry mensuration and landscape-scale C storage estimates, but the standard method of assessing forest C is typically based on national or regional-scale allometric equations that are often not representative on the local-scale. Improvement of these measurements is necessary in order for collaborative multi-national carbon monitoring programs such as REDD implemented by the UNFCCC to be successful in areas, such as tropical forests, with tree species that have insufficiently documented allometric relationships. The primary goal of this study is to set forth a pipeline for precise non-destructive monitoring of C storage by: 1) determining C storage on 15 1/10th ha plots in a 25.6 ha Virginia temperate forest using the recently updated national allometric equations from Chojnacky et. al 2014, 2) comparing these estimates to non-destructively determined individual tree biomass using several semi-automated approaches of three-dimensionally analyzing the point cloud from a high-precision Terrestrial Laser Scanner (TLS), and 3) creating a predictive model of forest C storage by fusing airborne LiDAR data to the plot-level TLS measurements. Our findings align with several other studies, indicating a strong relationship between allometrically-derived C estimates and TLS-derived C measurements (R2=0.93, n=30) using relatively few individuals, suggesting the potential application of these methods to species that are understudied or are without allometric relationships. Voxel based C storage was estimated on the plot level and

  17. ARM-ACME V: ARM Airborne Carbon Measurements V on the North Slope of Alaska Science and Implementation Plan

    SciTech Connect

    Biraud, S

    2015-05-01

    Atmospheric temperatures are warming faster in the Arctic than predicted by climate models. The impact of this warming on permafrost degradation is not well understood, but it is projected to increase carbon decomposition and greenhouse gas production (CO₂ and/or CH₄) by arctic ecosystems. Airborne observations of atmospheric trace gases, aerosols, and cloud properties at the North Slope of Alaska are improving our understanding of global climate, with the goal of reducing the uncertainty in global and regional climate simulations and projections.

  18. Bulk sediment 14C dating in an estuarine environment: How accurate can it be?

    NASA Astrophysics Data System (ADS)

    Lougheed, Bryan C.; Obrochta, Stephen P.; Lenz, Conny; Mellström, Anette; Metcalfe, Brett; Muscheler, Raimund; Reinholdsson, Maja; Snowball, Ian; Zillén, Lovisa

    2017-02-01

    Due to a lack of marine macrofossils in many sediment cores from the estuarine Baltic Sea, researchers are often forced to carry out 14C determinations on bulk sediment samples. However, ambiguity surrounding the carbon source pathways that contribute to bulk sediment formation introduces a large uncertainty into 14C geochronologies based on such samples, and such uncertainty may not have been fully considered in previous Baltic Sea studies. We quantify this uncertainty by analyzing bulk sediment 14C determinations carried out on densely spaced intervals in independently dated late-Holocene sediment sequences from two central Baltic Sea cores. Our results show a difference of 600 14C yr in median bulk sediment reservoir age, or R(t)bulk, between the two core locations ( 1200 14C yr for one core, 620 14C yr for the other), indicating large spatial variation. Furthermore, we also find large downcore (i.e., temporal) R(t)bulk variation of at least 200 14C yr for both cores. We also find a difference of 585 14C yr between two samples taken from the same core depth. We propose that studies using bulk sediment 14C dating in large brackish water bodies should take such spatiotemporal variation in R(t)bulk into account when assessing uncertainties, thus leading to a larger, but more accurate, calibrated age range.

  19. A Nadir-adjusted Airborne Multi Spectral Imaging System (NAMSIS) for high-resolution remote sensing of carbon fluxes

    NASA Astrophysics Data System (ADS)

    Jiang, Z.; Scott, S.; Rahman, A. F.

    2012-12-01

    Satellite remote sensing is widely used in vegetation monitoring, water stress detection and carbon cycle modeling. However, image pixels from high temporal resolution satellite sensors (such as MODIS) have coarse spatial resolution, much larger than the canopies they are supposed to characterize. An alternative solution for on-demand high spatial resolution remote sensing is sensors onboard low-flying aircrafts. Airborne remote sensing has been traditionally used in crop management studies. In this presentation we demonstrate the application of a relatively low-cost airborne sensor system with customized spectral band combinations for studying forest carbon fluxes. Our team has developed an Inertia Measurement Unit (IMU) controlled automated system to detach aircraft movements (pitch and roll) and engine vibration from the six-band programmable imager, in order to maintain the sensor at nadir view at all times during the flight. Flight lines are configured by a GPS-controleld system to simulate MODIS pixels. A feature-based algorithm is used to automatically generate a mosaic of individual images along the flight lines. This algorithm eliminates the need to mosiac and georeference images manually. An empirical line method is used to calculate reflectance from the raw data. Images from this airborne system produce reflectance values that are comparable with MODIS reflectance product. These high spatial resolution (~0.5 m) images deliver detailed information about tree species and phenological conditions within each MODIS pixel, and thus permit a high resolution spatio-temporal assessment of forest carbon fluxes.

  20. 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.

  1. An approximate calculation of advective gas-phase transport of 14C at Yucca Mountain, Nevada

    NASA Astrophysics Data System (ADS)

    Knapp, R. B.

    1990-01-01

    A quasilinear partial differential equation, which describes gas-phase transport of a 14C kinematic wave through a porous medium, is derived, its sensitivity to system variables is analyzed and it is applied to one possible release scenarion at the porposed Yucca Mountain, Nevada high-level radioactive waste repository. Advection, isotope exchange between CO 2 in a flowing gas phase and HCO 3- in a static aqueous phase, and radioactive decay are incorporated. The governing equation is solved analytically by the method of characteristics. The mass fraction of 14C in the gas phase,X 14g, is controlled by radioactive decay. The relatively long half-line of 14C, about 5720 years, and the relatively shallow proposed burial depth of the radioactive waste, about 350m, requires significant retardation of the 14C wave velocity for significant reduction in X 14g. 14C wave velocity is most sensitive to temperature and pH which control the distribution of total carbon between gas and liquid phase; the greater the partitioning of carbon into the liquid phase, the greater the retardation of the 14C wave velocity and the greater the ultimate reduction in X 14g from initial conditions. Partitioning of total carbon into the liquid phase is greatest at low temperatures, < 100° C, and high pH values, > 8. Increasing water saturation also tends to retard 14C wave velocity but to a lesser extent. The governing equation has been applied using conditions that may possibly occur at the proposed Yucca Mountain repository. Calculations indicate that the 14C wave takes about 5900 years to reach the surface with a X 14g equal to 25 ppm. Diffusion and dispersion are not of major importance for these conditions. These calculations are approximate due to the number of assumptions involved. Discharge of 14C into the gas before the selected time would accelerate wave arrival and increase the amount of 14C reaching the surface.

  2. First Airborne Lidar Measurements of Methane and Carbon Dioxide Applying the MERLIN Demonstrator CHARM-F

    NASA Astrophysics Data System (ADS)

    Amediek, Axel; Büdenbender, Christian; Ehret, Gerhard; Fix, Andreas; Gerbig, Christoph; Kiemle, Chritstoph; Quatrevalet, Mathieu; Wirth, Martin

    2016-04-01

    CHARM-F is the new airborne four-wavelengths lidar for simultaneous soundings of atmospheric CO2 and CH4. Due to its high technological conformity it is also a demonstrator for MERLIN, the French-German satellite mission providing a methane lidar. MERLIN's Preliminary Design Review was successfully passed recently. The launch is planned for 2020. First CHARM-F measurements were performed in Spring 2015 onboard the German research aircraft HALO. The aircraft's maximum flight altitude of 15 km and special features of the lidar, such as a relatively large laser ground spot, result in data similar to those obtained by a spaceborne system. The CHARM-F and MERLIN lidars are designed in the IPDA (integrated path differential absorption) configuration using short double pulses, which gives column averaged gas mixing ratios between the system and ground. The successfully completed CHARM-F flight measurements provide a valuable dataset, which supports the retrieval algorithm development for MERLIN notably. Furthermore, the dataset allows detailed analyses of measurement sensitivities, general studies on the IPDA principle and on system design questions. These activities are supported by another instrument onboard the aircraft during the flight campaign: a cavity ring down spectrometer, providing in-situ data of carbon dioxide, methane and water vapor with high accuracy and precision, which is ideal for validation purposes of the aircraft lidar. For the near future, detailed characterizations of CHARM-F are planned, further support of the MERLIN design, as well as the scientific aircraft campaign CoMet.

  3. Monitoring of Carbon Dioxide and Methane Plumes from Combined Ground-Airborne Sensors

    NASA Astrophysics Data System (ADS)

    Jacob, Jamey; Mitchell, Taylor; Honeycutt, Wes; Materer, Nicholas; Ley, Tyler; Clark, Peter

    2016-11-01

    A hybrid ground-airborne sensing network for real-time plume monitoring of CO2 and CH4 for carbon sequestration is investigated. Conventional soil gas monitoring has difficulty in distinguishing gas flux signals from leakage with those associated with meteorologically driven changes. A low-cost, lightweight sensor system has been developed and implemented onboard a small unmanned aircraft and is combined with a large-scale ground network that measures gas concentration. These are combined with other atmospheric diagnostics, including thermodynamic data and velocity from ultrasonic anemometers and multi-hole probes. To characterize the system behavior and verify its effectiveness, field tests have been conducted with simulated discharges of CO2 and CH4 from compressed gas tanks to mimic leaks and generate gaseous plumes, as well as field tests over the Farnsworth CO2-EOR site in the Anadarko Basin. Since the sensor response time is a function of vehicle airspeed, dynamic calibration models are required to determine accurate location of gas concentration in space and time. Comparisons are made between the two tests and results compared with historical models combining both flight and atmospheric dynamics. Supported by Department of Energy Award DE-FE0012173.

  4. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  6. Analyzing carbon dioxide and methane emissions in California using airborne measurements and model simulations

    NASA Astrophysics Data System (ADS)

    Johnson, M. S.; Yates, E. L.; Iraci, L. T.; Jeong, S.; Fischer, M. L.

    2013-12-01

    Greenhouse gas (GHG) concentrations have increased over the past decades and are linked to global temperature increases and climate change. These changes in climate have been suggested to have varying effects, and uncertain consequences, on agriculture, water supply, weather, sea-level rise, the economy, and energy. To counteract the trend of increasing atmospheric concentrations of GHGs, the state of California has passed the California Global Warming Act of 2006 (AB-32). This requires that by the year 2020, GHG (e.g., carbon dioxide (CO2) and methane (CH4)) emissions will be reduced to 1990 levels. To quantify GHG fluxes, emission inventories are routinely compiled for the State of California (e.g., CH4 emissions from the California Greenhouse Gas Emissions Measurement (CALGEM) Project). The major sources of CO2 and CH4 in the state of California are: transportation, electricity production, oil and gas extraction, cement plants, agriculture, landfills/waste, livestock, and wetlands. However, uncertainties remain in these emission inventories because many factors contributing to these processes are poorly quantified. To alleviate these uncertainties, a synergistic approach of applying air-borne measurements and chemical transport modeling (CTM) efforts to provide a method of quantifying local and regional GHG emissions will be performed during this study. Additionally, in order to further understand the temporal and spatial distributions of GHG fluxes in California and the impact these species have on regional climate, CTM simulations of daily variations and seasonality of total column CO2 and CH4 will be analyzed. To assess the magnitude and spatial variation of GHG emissions and to identify local 'hot spots', airborne measurements of CH4 and CO2 were made by the Alpha Jet Atmospheric eXperiment (AJAX) over the San Francisco Bay Area (SFBA) and San Joaquin Valley (SJV) in January and February 2013 during the Discover-AQ-CA study. High mixing ratios of GHGs were

  7. ARM Airborne Carbon Measurements (ARM-ACME) and ARM-ACME 2.5 Final Campaign Reports

    SciTech Connect

    Biraud, S. C.; Tom, M. S.; Sweeney, C.

    2016-01-01

    We report on a 5-year multi-institution and multi-agency airborne study of atmospheric composition and carbon cycling at the Atmospheric Radiation Measurement (ARM) Climate Research Facility’s Southern Great Plains (SGP) site, with scientific objectives that are central to the carbon-cycle and radiative-forcing goals of the U.S. Global Change Research Program and the North American Carbon Program (NACP). The goal of these measurements is to improve understanding of 1) the carbon exchange of the Atmospheric Radiation Measurement (ARM) SGP region; 2) how CO2 and associated water and energy fluxes influence radiative-forcing, convective processes, and CO2 concentrations over the ARM SGP region, and 3) how greenhouse gases are transported on continental scales.

  8. Carbon stocks and cycling in the Amazon basin: Measurement and modeling of natural disturbance and recovery using airborne LIDAR

    NASA Astrophysics Data System (ADS)

    Hunter, Maria O'Healy

    Forest structure, the three dimensional distribution of living and dead plant material including live crowns, understory vegetation and coarse woody debris, is the concrete physical form of carbon storage, the framework for biodiversity, and the instantaneous manifestation of disturbance and recovery processes. The frequency of disturbance and rate of decomposition drives the fractions of living and dead biomass, and the size of and intensity of disturbance drives the rate and species composition of forest recovery; both are primary sinks and sources in the carbon cycle. To improve understanding of disturbance and recovery processes, high-resolution airborne LIDAR (light detection and ranging) data from the Amazon region is combined with field measurements to analyze forest structure. These measurements are incorporated into a simple model to estimate light availability and the associated changes in carbon stocks. This work improves the understanding of Amazon forest dynamics and its role in the carbon cycle.

  9. Testing of a Two-Micron Double-Pulse IPDA Lidar Instrument for Airborne Atmospheric Carbon Dioxide Measurement

    NASA Astrophysics Data System (ADS)

    Yu, J.; Petros, M.; Refaat, T. F.; Remus, R.; Singh, U. N.

    2015-12-01

    Utilizing a tunable two-micron double-pulse laser transmitter, an airborne IPDA lidar system has been developed at NASA Langley Research Center for atmospheric carbon dioxide column measurements. The instrument comprises a receiver with 0.4 m telescope and InGaAs pin detectors coupled to 12-bit, 200 MS/s waveform digitizers. For on-site ground testing, the 2-μm CO2 IPDA lidar was installed inside a trailer located where meteorological data and CO2 mixing ratio profiles were obtained from CAPABLE and LiCoR in-suite sampling, respectively. IPDA horizontal ground testing with 860 m target distance indicated CO2 sensitivity of 2.24 ppm with -0.43 ppm offset, while operating at 3 GHz on-line position from the R30 line center. Then, the IPDA lidar was integrated inside the NASA B-200 aircraft, with supporting instrumentation, for airborne testing and validation. Supporting instruments included in-situ LiCoR sensor, GPS and video recorder for target identification. Besides, aircraft built-in sensors provided altitude, pressure, temperature and relative humidity sampling during flights. The 2-mm CO2 IPDA lidar airborne testing was conducted through ten daytime flights (27 hours flight time). Airborne testing included different operating and environmental conditions for flight altitude up to 7 km, different ground target conditions such as vegetation, soil, ocean, snow and sand and different cloud conditions. Some flights targeted power plant incinerators for investigating IPDA sensitivity to CO2 plums. Relying on independent CO2 in-situ sampling, conducted through NOAA, airborne IPDA CO2 sensitivity of 4.15 ppm with 1.14 ppm offset were observed at 6 km altitude and 4 GHz on-line offset frequency. This validates the 2-μm double-pulse IPDA lidar for atmospheric CO2 measurement.

  10. 14C Incorporation into the Fatty Acids and Aliphatic Hydrocarbons of Sarcina lutea

    PubMed Central

    Tornabene, T. G.; Oró, J.

    1967-01-01

    An initial investigation into the mechanism of hydrocarbon biosynthesis in Sarcina lutea was performed by measuring the amounts of 14C incorporated into the hydrocarbons and fatty acids by use of a combination gas chromatograph and high-temperature gas-flow ionization apparatus. Uniformly labeled l-isoleucine-14C was predominantly incorporated into the anteiso-branched chains. Palmitate-16-14C gave evidence that a direct correlation may exist between the nonpolar end of the palmitate and the biosynthesis of hydrocarbons and carotenoids. The label from palmitate-1-14C was incorporated into the various hydrocarbon groups as a compound, derived from the polar end of the palmitate, consisting of more than two carbon atoms. Palmitate-16-14C and -1-14C gave no detectable evidence that transformed products were incorporated into other fatty acids. Sodium acetate-2-14C and uniformly labeled l-leucine-14C gave evidence of a nonspecific incorporation into both the aliphatic hydrocarbons and fatty acids of Sarcina lutea. PMID:6039358

  11. Modelling above-ground carbon dynamics using multi-temporal airborne lidar: insights from a Mediterranean woodland

    NASA Astrophysics Data System (ADS)

    Simonson, W.; Ruiz-Benito, P.; Valladares, F.; Coomes, D.

    2016-02-01

    Woodlands represent highly significant carbon sinks globally, though could lose this function under future climatic change. Effective large-scale monitoring of these woodlands has a critical role to play in mitigating for, and adapting to, climate change. Mediterranean woodlands have low carbon densities, but represent important global carbon stocks due to their extensiveness and are particularly vulnerable because the region is predicted to become much hotter and drier over the coming century. Airborne lidar is already recognized as an excellent approach for high-fidelity carbon mapping, but few studies have used multi-temporal lidar surveys to measure carbon fluxes in forests and none have worked with Mediterranean woodlands. We use a multi-temporal (5-year interval) airborne lidar data set for a region of central Spain to estimate above-ground biomass (AGB) and carbon dynamics in typical mixed broadleaved and/or coniferous Mediterranean woodlands. Field calibration of the lidar data enabled the generation of grid-based maps of AGB for 2006 and 2011, and the resulting AGB change was estimated. There was a close agreement between the lidar-based AGB growth estimate (1.22 Mg ha-1 yr-1) and those derived from two independent sources: the Spanish National Forest Inventory, and a tree-ring based analysis (1.19 and 1.13 Mg ha-1 yr-1, respectively). We parameterised a simple simulator of forest dynamics using the lidar carbon flux measurements, and used it to explore four scenarios of fire occurrence. Under undisturbed conditions (no fire) an accelerating accumulation of biomass and carbon is evident over the next 100 years with an average carbon sequestration rate of 1.95 Mg C ha-1 yr-1. This rate reduces by almost a third when fire probability is increased to 0.01 (fire return rate of 100 years), as has been predicted under climate change. Our work shows the power of multi-temporal lidar surveying to map woodland carbon fluxes and provide parameters for carbon

  12. Modelling above-ground carbon dynamics using multi-temporal airborne lidar: insights from a Mediterranean woodland

    NASA Astrophysics Data System (ADS)

    Simonson, W.; Ruiz-Benito, P.; Valladares, F.; Coomes, D.

    2015-09-01

    Woodlands represent highly significant carbon sinks globally, though could lose this function under future climatic change. Effective large-scale monitoring of these woodlands has a critical role to play in mitigating for, and adapting to, climate change. Mediterranean woodlands have low carbon densities, but represent important global carbon stocks due to their extensiveness and are particularly vulnerable because the region is predicted to become much hotter and drier over the coming century. Airborne lidar is already recognized as an excellent approach for high-fidelity carbon mapping, but few studies have used multi-temporal lidar surveys to measure carbon fluxes in forests and none have worked with Mediterranean woodlands. We use a multi-temporal (five year interval) airborne lidar dataset for a region of central Spain to estimate above-ground biomass (AGB) and carbon dynamics in typical mixed broadleaved/coniferous Mediterranean woodlands. Field calibration of the lidar data enabled the generation of grid-based maps of AGB for 2006 and 2011, and the resulting AGB change were estimated. There was a close agreement between the lidar-based AGB growth estimate (1.22 Mg ha-1 year-1) and those derived from two independent sources: the Spanish National Forest Inventory, and a~tree-ring based analysis (1.19 and 1.13 Mg ha-1 year-1, respectively). We parameterised a simple simulator of forest dynamics using the lidar carbon flux measurements, and used it to explore four scenarios of fire occurrence. Under undisturbed conditions (no fire occurrence) an accelerating accumulation of biomass and carbon is evident over the next 100 years with an average carbon sequestration rate of 1.95 Mg C ha-1 year-1. This rate reduces by almost a third when fire probability is increased to 0.01, as has been predicted under climate change. Our work shows the power of multi-temporal lidar surveying to map woodland carbon fluxes and provide parameters for carbon dynamics models. Space

  13. Identifying a Sea Breeze Circulation Pattern Over the Los Angeles Basin Using Airborne In Situ Carbon Dioxide Measurements

    NASA Astrophysics Data System (ADS)

    Brannan, A. L.; Schill, S.; Trousdell, J.; Heath, N.; Lefer, B. L.; Yang, M. M.; Bertram, T. H.

    2014-12-01

    The Los Angeles Basin in Southern California is an optimal location for a circulation study, due to its location between the Pacific Ocean to the west and the Santa Monica and San Gabriel mountain ranges to the east, as well as its booming metropolitan population. Sea breeze circulation carries air at low altitudes from coastal to inland regions, where the air rises and expands before returning back towards the coast at higher altitudes. As a result, relatively clean air is expected at low altitudes over coastal regions, but following the path of sea breeze circulation should increase the amount of anthropogenic influence. During the 2014 NASA Student Airborne Research Program, a highly modified DC-8 aircraft completed flights from June 23 to 25 in and around the LA Basin, including missed approaches at four local airports—Los Alamitos and Long Beach (coastal), Ontario and Riverside (inland). Because carbon dioxide (CO2) is chemically inert and well-suited as a conserved atmospheric tracer, the NASA Langley Atmospheric Vertical Observations of CO2 in the Earth's Troposphere (AVOCET) instrument was used to make airborne in situ carbon dioxide measurements. Combining measured wind speed and direction data from the aircraft with CO2 data shows that carbon dioxide can be used to trace the sea breeze circulation pattern of the Los Angeles basin.

  14. 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.

  15. 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.

  16. Intermediate water 14C evidence for the mechanism of deglacial CO2 increase

    NASA Astrophysics Data System (ADS)

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

    2006-12-01

    Carbon sequestration in the ocean is widely considered to be the proximate cause of glacial CO2 lowering. The 14C activity of the atmosphere during the last glacial period appears to have been too high to be explained by increased cosmogenic production alone, implying that exchange of CO2 with the deep ocean must have been reduced. In other words, there must have been a relatively isolated deep ocean carbon reservoir. Likewise there was a sharp drop in atmospheric 14C activity coincident with the Termination I atmospheric CO2 increase, suggesting that the deep isolated reservoir, and therefore the carbon released from the ocean, was extremely depleted in 14C. Both the CO2 and 14C changes occurred in step with Antarctic warming, implicating the Southern Ocean as the main locus of carbon release. We therefore hypothesize that 14C-depleted waters should have spread to the intermediate/upper ocean via Antarctic Intermediate Water and Subantarctic Mode Water during the last deglaciation. We show that at ~700 m water depth off of southern Baja California, very 14C-depleted waters appeared in two stages during the last deglaciation, closely coincident with the atmospheric CO2 rise. The spectral reflectance record from our sediment core bears a remarkable resemblance to Greenland ice δ 18O, allowing us to assign calendar ages to our samples. Radiocarbon activity of paleo-waters is then calculated by age-correcting our benthic foraminiferal 14C measurements. During most of the 40,000 year record, intermediate water activity was ~100-200‰ lower than the atmosphere (like today), but during deglaciation this depletion increased to as much as 450‰. We suggest that this transient drop reflects the mixing of `old' carbon to the Southern Ocean surface, with spreading to the North Pacific via Antarctic Intermediate Water.

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

    NASA Technical Reports Server (NTRS)

    Koehler, Peter; Muscheler, Raimund; Fischer, Hubertus

    2006-01-01

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

  18. Mineralisation of (14)C-labelled polystyrene plastics by Penicillium variabile after ozonation pre-treatment.

    PubMed

    Tian, Lili; Kolvenbach, Boris; Corvini, Nora; Wang, Songfeng; Tavanaie, Nasrin; Wang, Lianhong; Ma, Yini; Scheu, Stefan; Corvini, Philippe François-Xavier; Ji, Rong

    2016-07-19

    Large amounts of polystyrene (PS), one of the most widely used plastics in the world, end up in the environment through industrial discharge and littering, becoming one of the major components of plastic debris. Such plastics, especially the small-sized microplastics and nanoplastics, have received increasing concerns in terms of their potential environmental risks. Feasible approaches for the degradation of PS in waste materials and in the environment are highly desirable. Physicochemical pretreatments of PS may be applied to enhance biological degradation. In the present study, we synthesized (14)C-labelled PS polymers, either uniformly labelled on the ring ([U-ring-(14)C]-PS) or labelled at the β-carbon position of the alkyl chain ([β-(14)C]-PS), and investigated the mineralisation of the (14)C-PS polymers by the fungus Penicillium variabile CCF3219 as well as the effect of ozonation as a physico-chemical pre-treatment on the mineralisation by the fungi. Biodegradation of the (14)C-PS polymers was studied in liquid medium (pH 7.5, without additional carbon substrate) with P. variabile for 16 weeks. During the incubation time, (14)CO2 was captured to calculate the mineralisation of (14)C-PS and the remaining polymers were analysed by means of scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectrometry and gel-permeation chromatography (GPC). The results showed that the fungi mineralised both labelled polymers, and that the [U-ring-(14)C]-PS with a lower molecular weight led to a higher mineralisation rate. Ozonation pre-treatment strongly enhanced mineralisation of [β-(14)C]-PS. SEM analysis showed that the surface of the ozonated [β-(14)C]-PS became uneven and rough after the incubation, indicating an attack on the polymer by P. variabile. FT-IR analysis showed that ozonation generated carbonyl groups on the [β-(14)C]-PS and the amount of the carbonyl groups decreased after incubation of the [β-(14)C]-PS with P. variabile. GPC

  19. 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.

  20. Proton production cross sections of {sup 14}C from silicon and oxygen: Implications for cosmic-ray studies

    SciTech Connect

    Sisterson, J.M.; Jull, A.J.T.; Beverding, A.

    1993-12-31

    The production rates of {sup 14}C from proton spallation of silicon, and oxygen have been measured over a wide range of energies from 31 to 450 MeV. {sup 14}C was measured by accelerator mass spectrometry (AMS) after extraction of carbon from the samples by melting in a flow of oxygen.

  1. [Measuring 14C-glucose and 14C-acetate oxidation in tumour cells and tumorous host organism].

    PubMed

    Hujber, Zoltán; Jeney, András; Oláh, Júlia; Szoboszlai, Norbert; Baranyai, Lajos; Környei, József; Petõvári, Gábor; Sebestyén, Anna

    2015-12-01

    Tumour cell metabolism can be influenced by alterations of the extracellular microenvironment and the tumour-promoting genetically changed mechanisms. There is increasing interest to introduce appropriate bioenergetic assays to describe the therapeutic effect and metabolic subtypes of tumours in clinical oncology. The analysis of 14C-glucose and 14C-acetate oxidation could be a suitable method to examine the metabolic/bioenergetic profiles of tumour cells and tumorous host organisms. The metabolic activity of tumour cells (in vitro cell lines, primary human lymphocytes and leukaemia cells) and the tumourous host organism were examined in vitro and in vivo by detecting the released CO2 levels derived from the radioactive carbon atom labelled energy substrates. We have found that the most cancer cells of solid tumours oxidised glucose more intensively than acetate. It was interesting that AML, CML and CLL cells isolated from blood preferred acetate as an energy substrate in vitro. Furthermore, based on our observations, tumours affected the glucose or acetate oxidation of the organism when applying bioenergetic substrates per os or iv. We provided the first data about the alterations in metabolic profiles of the tumour bearing organism in xenograft models. In summary, according to our results, comparison of the energy substrate oxidation can be an indicative method related to the metabolic profile analysis of tumour cells in vitro and tumorous host organism in vivo.

  2. Evaluation of Airborne Particle Emissions from Commercial Products Containing Carbon Nanotubes

    PubMed Central

    Huang, Guannan; Park, Jae Hong; Cena, Lorenzo G.; Shelton, Betsy L.; Peters, Thomas M.

    2012-01-01

    The emission of the airborne particles from epoxy resin test sticks with different CNT loadings and two commercial products were characterized while sanding with three grit sizes and three disc sander speeds. The total number concentrations, respirable mass concentrations, and particle size number/mass distributions of the emitted particles were measured using a condensation particle counter, an optical particle counter, and a scanning mobility particle sizer. The emitted particles were sampled on a polycarbonate filter and analyzed using electron microscopy. The highest number concentrations (arithmetic mean = 4670 particles/cm3) were produced with coarse sandpaper, 2% (by weight) CNT test sticks and medium disc sander speed, whereas the lowest number concentrations (arithmetic mean = 92 particles/cm3) were produced with medium sandpaper, 2% CNT test sticks and slow disc sander speed. Respirable mass concentrations were highest (arithmetic mean = 1.01 mg/m3) for fine sandpaper, 2% CNT test sticks and medium disc sander speed and lowest (arithmetic mean = 0.20 mg/m3) for medium sandpaper, 0% CNT test sticks and medium disc sander speed. For CNT-epoxy samples, airborne particles were primarily micrometer-sized epoxy cores with CNT protrusions. No free CNTs were observed in airborne samples, except for tests conducted with 4% CNT epoxy. The number concentration, mass concentration, and size distribution of airborne particles generated when products containing CNTs are sanded depends on the conditions of sanding and the characteristics of the material being sanded. PMID:23204914

  3. Evaluation of Airborne Particle Emissions from Commercial Products Containing Carbon Nanotubes.

    PubMed

    Huang, Guannan; Park, Jae Hong; Cena, Lorenzo G; Shelton, Betsy L; Peters, Thomas M

    2012-10-01

    The emission of the airborne particles from epoxy resin test sticks with different CNT loadings and two commercial products were characterized while sanding with three grit sizes and three disc sander speeds. The total number concentrations, respirable mass concentrations, and particle size number/mass distributions of the emitted particles were measured using a condensation particle counter, an optical particle counter, and a scanning mobility particle sizer. The emitted particles were sampled on a polycarbonate filter and analyzed using electron microscopy. The highest number concentrations (arithmetic mean = 4670 particles/cm(3)) were produced with coarse sandpaper, 2% (by weight) CNT test sticks and medium disc sander speed, whereas the lowest number concentrations (arithmetic mean = 92 particles/cm(3)) were produced with medium sandpaper, 2% CNT test sticks and slow disc sander speed. Respirable mass concentrations were highest (arithmetic mean = 1.01 mg/m(3)) for fine sandpaper, 2% CNT test sticks and medium disc sander speed and lowest (arithmetic mean = 0.20 mg/m(3)) for medium sandpaper, 0% CNT test sticks and medium disc sander speed. For CNT-epoxy samples, airborne particles were primarily micrometer-sized epoxy cores with CNT protrusions. No free CNTs were observed in airborne samples, except for tests conducted with 4% CNT epoxy. The number concentration, mass concentration, and size distribution of airborne particles generated when products containing CNTs are sanded depends on the conditions of sanding and the characteristics of the material being sanded.

  4. Pharmacokinetics of 14C CDP-choline.

    PubMed

    Dinsdale, J R; Griffiths, G K; Rowlands, C; Castelló, J; Ortiz, J A; Maddock, J; Aylward, M

    1983-01-01

    The absorption, metabolism and excretion of cytidine diphosphate choline (CDP-choline, citicoline, Somazina) were investigated in six adult healthy subjects after a single oral dose of 300 mg of the 14C-labelled compound. The compound was well tolerated by the subjects. Absorption was virtually complete with less than 1% of the dose being found in the faeces during the 5-day collection period. Two peaks were found in the plasma radioactivity time profile: the first at 1 h, and a second larger peak at 24 h post-dose. Elimination of the ingested dose occurred via respiratory CO2 and through urinary excretion; the former predominating, and both routes exhibited biphasic patterns characterized by an early phase followed by slower decline. It is postulated that in the healthy human subject CDP-choline is metabolized in the gut wall and in the liver; the products arising from the compound's extensive hepatic metabolism being subsequently available for diverse biosynthetic pathways, tissue metabolism, and excretion.

  5. Evaluation of the (14)C-urea breath test using indigenously produced (14)C-urea capsules and a modified technique for trapping exhaled breath: a pilot study.

    PubMed

    Tiwari, Bijaynath P; Nistala, Srinivas; Patil, Sanjay P; Kalgutkar, Deepak P; Jaychandran, Narath; Chander, Harish; Basu, Sandip

    2014-03-01

    The carbon urea breath test ((14)C-UBT) is a noninvasive technique used to detect Helicobacter pylori infection in patients presenting with dyspeptic symptoms. The present study was undertaken to determine the efficacy of indigenously produced (14)C-UBT capsules by the Board of Radiation and Isotope Technology, India. Thirty consecutive patients with dyspeptic symptoms were included in the study. After ingestion of capsules, breath samples were collected in a CO2-trapping solution to which a scintillation cocktail was added. After 24 h, the whole sample was counted in a liquid scintillation counter along with a standard of (14)C. The number of disintegrations of (14)C per minute in the breath sample was calculated. The results were compared with histopathological reports. Of 30 patients, 19 were positive and 11 were negative on (14)C-UBT. Histopathological reports confirmed 27 cases as positive and three as negative for H. pylori. Thus, the results of (14)C-UBT were concordant with histopathological results in 22/30 (73.3%) cases. Considering histopathology as the gold standard, the sensitivity, specificity, and positive predictive value of (14)C-UBT using indigenously produced capsules were found to be 70.33, 100, and 100%, respectively. On critical analysis of the discordant results, we observed that six patients had undergone H. pylori eradication therapy exactly 4 weeks before the test. When these six patients were excluded from the analysis, the sensitivity, specificity, and positive predictive value were found to be 90.05, 100, and 100%, respectively, which compared well with the values obtained using the standard procedure. The study demonstrates adequate efficacy of the indigenous methodology in newly diagnosed symptomatic patients with acid peptic disorders. The analyses of the results indicate that the test should be preferably employed after the recommended period of 1 month following completion of eradication therapy.

  6. 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.

  7. 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.

  8. 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

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  10. Airborne detection of diffuse carbon dioxide emissions at Mammoth Mountain, California

    USGS Publications Warehouse

    Gerlach, T.M.; Doukas, M.P.; McGee, K.A.; Kessler, R.

    1999-01-01

    We report the first airborne detection of CO2 degassing from diffuse volcanic sources. Airborne measurement of diffuse CO2 degassing offers a rapid alternative for monitoring CO2 emission rates at Mammoth Mountain. CO2 concentrations, temperatures, and barometric pressures were measured at ~2,500 GPS-referenced locations during a one-hour, eleven-orbit survey of air around Mammoth Mountain at ~3 km from the summit and altitudes of 2,895-3,657 m. A volcanic CO2 anomaly 4-5 km across with CO2 levels ~1 ppm above background was revealed downwind of tree-kill areas. It contained a 1-km core with concentrations exceeding background by >3 ppm. Emission rates of ~250 t d-1 are indicated. Orographic winds may play a key role in transporting the diffusely degassed CO2 upslope to elevations where it is lofted into the regional wind system.We report the first airborne detection of CO2 degassing from diffuse volcanic sources. Airborne measurement of diffuse CO2 degassing offers a rapid alternative for monitoring CO2 emission rates at Mammoth Mountain. CO2 concentrations, temperatures, and barometric pressures were measured at approximately 2,500 GPS-referenced locations during a one-hour, eleven-orbit survey of air around Mammoth Mountain at approximately 3 km from the summit and altitudes of 2,895-3,657 m. A volcanic CO2 anomaly 4-5 km across with CO2 levels approximately 1 ppm above background was revealed downwind of tree-kill areas. It contained a 1-km core with concentrations exceeding background by >3 ppm. Emission rates of approximately 250 t d-1 are indicated. Orographic winds may play a key role in transporting the diffusely degassed CO2 upslope to elevations where it is lofted into the regional wind system.

  11. The use of airborne laser scanning to develop a pixel-based stratification for a verified carbon offset project

    PubMed Central

    2011-01-01

    Background The voluntary carbon market is a new and growing market that is increasingly important to consider in managing forestland. Monitoring, reporting, and verifying carbon stocks and fluxes at a project level is the single largest direct cost of a forest carbon offset project. There are now many methods for estimating forest stocks with high accuracy that use both Airborne Laser Scanning (ALS) and high-resolution optical remote sensing data. However, many of these methods are not appropriate for use under existing carbon offset standards and most have not been field tested. Results This paper presents a pixel-based forest stratification method that uses both ALS and optical remote sensing data to optimally partition the variability across an ~10,000 ha forest ownership in Mendocino County, CA, USA. This new stratification approach improved the accuracy of the forest inventory, reduced the cost of field-based inventory, and provides a powerful tool for future management planning. This approach also details a method of determining the optimum pixel size to best partition a forest. Conclusions The use of ALS and optical remote sensing data can help reduce the cost of field inventory and can help to locate areas that need the most intensive inventory effort. This pixel-based stratification method may provide a cost-effective approach to reducing inventory costs over larger areas when the remote sensing data acquisition costs can be kept low on a per acre basis. PMID:22004847

  12. Carbon monoxide total column retrievals by use of the measurements of pollution in the troposphere airborne test radiometer.

    PubMed

    Niu, Jianguo; Deeter, Merritt N; Gille, John C; Edwards, David P; Ziskin, Daniel C; Francis, Gene L; Hills, Alan J; Smith, Mark W

    2004-08-20

    The Measurements of Pollution in the Troposphere (MOPITT) Airborne Test Radiometer (MATR) uses gas correlation filter radiometry from high-altitude aircraft to measure tropospheric carbon monoxide. This radiometer is used in support of the ongoing validation campaign for the MOPITT instrument aboard the Earth Observation System Terra satellite. A recent study of MATR CO retrievals that used data from the autumn of 2001 in the western United States is presented. Retrievals of the CO total column were performed and compared to in situ sampling with less than 10% retrieval error. Effects that influence retrieval, such as instrument sensitivity, retrieval sensitivity, and the bias between observations and the radiative transfer model, are discussed. Comparisons of MATR and MOPITT retrievals show promising consistency. A preliminary interpretation of MATR results is also presented.

  13. Reconstructions of the 14C cosmogenic isotope content from natural archives after the last glacial termination

    NASA Astrophysics Data System (ADS)

    Kudryavtsev, I. V.; Volobuev, D. M.; Dergachev, V. A.; Nagovitsyn, Yu. A.; Ogurtsov, M. G.

    2016-12-01

    Data on the content of the 14C cosmogenic isotope in tree rings, which were obtained as a result of laboratory measurements, are often used when solar activity (SA) is reconstructed for previous epochs, in which direct observations are absent. However, these data contain information not only about SA variations but also about changes in the Earth climatic parameters, such as the global temperature and the CO2 content in the Earth's atmosphere. The effect of these variations on the 14C isotope content in different natural reservoirs after the last glacial termination to the middle of the Holocene is considered. The global temperature and the CO2 content increased on this time interval. In this case the 14C absolute content in the atmosphere increased on this time interval, even though the 14C to 12C isotope concentration ratio (as described by the Δ14C parameter) decreased. These variations in the radiocarbon absolute content can be caused by its redistribution between natural reservoirs. It has been indicated that such a redistribution is possible only when the rate of carbon exchange between the ocean and atmosphere depends on temperature. The values of the corresponding temperature coefficient for the 17-10 ka BC time interval, which make it possible to describe the carbon redistribution between the ocean and atmosphere, have been obtained.

  14. Airborne Observations of the Spatial and Temporal Variability of Tropospheric Carbon Dioxide during the INTEX-B Campaign

    NASA Technical Reports Server (NTRS)

    Vay, Stephanie A.; Choi, Younghoon; Woo, Jung-Hun; Barrick, John D.; Sachse, Glen W.; Blake, Donald; Avery, Melody A.; Fuelberg, Henry; Nolf, Scott

    2006-01-01

    The Intercontinental Chemical Transport Experiment-North America (INTEX-NA) is an international field campaign envisioned to investigate the transport and transformation of gases and aerosols on transcontinental/intercontinental scales and assess their impact on air quality and climate. Phase B (INTEX-B) of the mission was conducted during a 10- week period from March 1 to May 15, 2006 and focused initially on pollution outflow from the Mexico City Metropolitan Area, later addressing the transport of pollution from Asia to North America during springtime meteorological conditions. During the deployment, fast-response (1-s resolution) CO2 measurements were recorded aboard the NASA DC-8 providing valuable regional-scale information on carbon sources and sinks over sparsely sampled areas of North America and adjacent ocean basins. When coupled with the enormously sophisticated chemistry payload on the DC-8, these measurements collectively afford extremely powerful multi-tracer constraints for carbon source/sink attribution. Preliminary examination of the two data sets from the INTEX-B campaign, acquired one month apart, reveals not only the influence of the CO2 seasonal cycle, but also the preponderance of human population and industrial activity in the northern hemisphere. In this presentation, a synergy of the ensemble of airborne and surface observations, bottomup emission inventories, as well as transport history are invoked in a GIS framework to elucidate the source/sink processes reflected in the observations. The airborne CO2 data, along with simultaneous surface measurements (e.g. NOAA ESRL), are examined to establish the vertical distribution and variability of CO2 as a function of location. The role of localized sources, long-range transport, the biosphere, stratospheric exchange, and dynamical processes on the CO2 spatial variability observed throughout the tropospheric column will be discussed.

  15. Survival of Airborne Bacteria in a High Urban Concentration of Carbon Monoxide1

    PubMed Central

    Lighthart, Bruce

    1973-01-01

    Vegetative cells of Serratia marcescens 8UK, Sarcina lutea, and spores of Bacillus subtilus var. niger were held in aerosols, with and without an urban concentration of CO (85 μliters per liter or ppm), for up to 6 hr at 15 C and a relative humidity (RH) of approximately 0, 25, 50, 75, and 95%. It was found that CO enhanced the death rate of S. marcescens 8UK at least four- to sevenfold at low RH (ca. 1 to 25%), but protected the cells at high RH (ca. 90%). Death rates of S. lutea, with or without added CO, were comparatively low over the entire RH range. However, in the first hour, airborne S. lutea held in CO-containing air were more stable than those in air without added CO (i.e., CO protection). A marked increase in the death rate (up to 70-fold) occurred in the subsequent 5 hr within the RH range of approximately 0 to 75%. Statistical analysis indicated that aerosol decay rates of B. subtilus var. niger spores decreased significantly, when held in a CO-containing as compared to a non-CO-containing atmosphere, in the 0 to 85% RH range. Thus, the data presented indicate that CO in the urban environment may have a protective or lethal effect on airborne bacteria, dependent upon at least the microbial species, aerosol age, and relative humidity. A mechanism for CO death enhancement and protection of airborne S. marcescens 8UK is suggested to involve CO uncoupling of an energy-requiring death mechanism and an energy-requiring maintenance mechanism at high and low RH, respectively. PMID:4631439

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  17. Development of an Airborne Triple-Pulse 2-Micron Integrated Path Differential Absorption Lidar (IPDA) for Simultaneous Airborne Column Measurements of Carbon Dioxide and Water Vapor in the Atmosphere

    NASA Technical Reports Server (NTRS)

    Singh, Upendra N.; Petros, Mulugeta; Refaat, Tamer F.; Yu, Jirong; Antill, Charles W.; Remus, Ruben

    2016-01-01

    This presentation will provide status and details of an airborne 2-micron triple-pulse integrated path differential absorption (IPDA) lidar being developed at NASA Langley Research Center with support from NASA ESTO Instrument Incubator Program. The development of this active optical remote sensing IPDA instrument is targeted for measuring both atmospheric carbon dioxide and water vapor in the atmosphere from an airborne platform. This presentation will focus on the advancement of the 2-micron triple-pulse IPDA lidar development. Updates on the state-of-the-art triple-pulse laser transmitter will be presented including the status of seed laser locking, wavelength control, receiver and detector upgrades, laser packaging and lidar integration. Future plan for IPDA lidar system for ground integration, testing and flight validation will also be presented.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  19. AMS measurements of 14C and 129I in seawater around radioactive waste dump sites

    NASA Astrophysics Data System (ADS)

    Povinec, P. P.; Oregioni, B.; Jull, A. J. T.; Kieser, W. E.; Zhao, X.-L.

    2000-10-01

    According to a recent IAEA compilation of inventories of radioactive wastes dumped in the world ocean, a total of 85 PBq of radioactive wastes were dumped, in the Atlantic (45 PBq), the Pacific (1.4 PBq) and the Arctic (38 PBq) Oceans and their marginal seas between 1946 and 1993, mostly in the form of low-level wastes. 3H, and 14C formed an important part of the beta-activity of these dumped wastes. Because of its long half-life, 14C will be the main constituent in possible leakages from the wastes in the future. On the other hand, 14C and 129I are important radioactive tracers which have been artificially introduced into the oceans. Small amounts of 14C and 129I can be easily measured by accelerator mass spectrometry (AMS) on mg-size samples of carbon and iodine extracted from 500 ml seawater samples. The high analytical sensitivity enables one therefore to find even trace amounts of 14C and 129I which could be released from radioactive wastes, and to compare the measured levels with the global distribution of these radionuclides. The IAEAs Marine Environment Laboratory (IAEA-MEL) has been engaged in an assessment program related to radioactive waste dumping in the oceans since 1992 and has participated in several expeditions to the Atlantic, Arctic, Indian and Pacific Oceans to sample seawater, biota and sediment for radiological assessment studies. In the present paper, we report on methods of 14C and 129I measurements in seawater by AMS and present data on the NE Atlantic, the Arctic and the NW Pacific Ocean dumping sites. A small increase of 14C was observed at the NE Atlantic dumping site.

  20. 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.

  1. 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.

  2. First Airborne IPDA Lidar Measurements of Methane and Carbon Dioxide Applying the DLR Greenhouse Gas Sounder CHARM-F

    NASA Astrophysics Data System (ADS)

    Amediek, A.; Ehret, G.; Fix, A.; Wirth, M.; Quatrevalet, M.; Büdenbender, C.; Kiemle, C.; Loehring, J.; Gerbig, C.

    2015-12-01

    First airborne measurement using CHARM-F, the four-wavelengths lidar for simultaneous soundings of atmospheric CO2 and CH4, were performed in Spring 2015 onboard the German research aircraft HALO. The lidar is designed in the IPDA (integrated path differential absorption) configuration using short double pulses, which gives column averaged gas mixing ratios between aircraft and ground. HALO's maximum flight altitude of 15 km and special features of the lidar, such as a relatively large laser ground spot, enable the CHARM-F system to be an airborne demonstrator for future spaceborne greenhouse gas lidars. Due to a high technological conformity this applies in particular to the French-German satellite mission MERLIN, the spaceborne methane IPDA lidar. The successfully completed flight measurements provide a valuable dataset, which supports the retrieval algorithm development for MERLIN notably. The flights covered different ground cover types, different orography types as well as the sea. Additionally, we captured different cloud conditions, at which the broken cloud case is a matter of particular interest. This dataset allows detailed analyses of measurement sensitivities, general studies on the IPDA principle and on technical details of the system. These activities are supported by another instrument onboard: a cavity ring down spectrometer, providing in-situ data of carbon dioxide, methane and water vapor with high accuracy and precision, which is ideal for validation purposes of the lidar. Additionally the onboard instrumentation of HALO gives information about pressure and temperature for cross-checking the ECMWF data, which are intended to be used for calculating the weighting function, the key quantity for the retrieval of gas column mixing ratios from the measured gas optical depths. In combination with dedicated descents into the boundary layer and subsequent ascents, a self-contained dataset for characterizations of CHARM-F is available.

  3. Assessment of 14C AMS dating of phytoliths as a new paleoenvironmental and archaeological tool

    NASA Astrophysics Data System (ADS)

    Corbineau, R.; Alexandre, A. E.; Santos, G. M.; Reyerson, P. E.

    2011-12-01

    14C AMS analysis of occluded carbon in phytoliths (phytC) is a promising dating tool for palaeoenvironmental and archaeological studies. In order to assess the accuracy of this method, different tests were recently carried out on large phytolith concentrates of phytC samples extracted from soils and harvested plants, in association with blank samples of SiO2 powder to check the absence of carbon contamination during the treatments. Despite this precaution, 14C values from recent harvested plants were inexplicably old (2 - 8 ka years BP). Nevertheless, we noticed that many chemical extraction protocols that were used did not lead to samples totally free of organic matter. In order to tackle this problem, and as a first step, the efficiency of common extraction protocols from the literature were tested. Samples were analyzed by SEM/EDX in order to assess the purity of the siliceous material following extraction. As a result of these tests, a new extraction protocol combining acid digestion, oxidation and dry ashing to acquire pure samples of phytoliths from harvested plants is proposed. In a second step, modern and well dated archaeological materials (harvested plants grown within a FACE experiment and plant residues from a 17th century French mummy) were analyzed in 14C-AMS. Results should allow either to demonstrate the reliability of 14C-AMS analysis of phytolith occluded carbon as a dating tool or trigger further investigations of possible sources of old occluded carbon in phytoliths if the 14C ages are still older than expected.

  4. ARM-ACME V: ARM Airborne Carbon Measurements V on the North Slope of Alaska Field Campaign Report

    SciTech Connect

    Biraud, Sebastien C

    2016-05-01

    Atmospheric temperatures are warming faster in the Arctic than predicted by climate models. The impact of this warming on permafrost degradation is not well understood, but it is projected to increase carbon decomposition and greenhouse gas production (CO2 and/or CH4) by arctic ecosystems. Airborne observations of atmospheric trace gases, aerosols and cloud properties in North Slopes of Alaska (NSA) are improving our understanding of global climate, with the goal of reducing the uncertainty in global and regional climate simulations and projections. From June 1 through September 15, 2015, AAF deployed the G1 research aircraft and flew over the North Slope of Alaska (38 flights, 140 science flight hours), with occasional vertical profiling over Prudhoe Bay, Oliktok point, Barrow, Atqasuk, Ivotuk, and Toolik Lake. The aircraft payload included Picarro and Los Gatos Research (LGR) analyzers for continuous measurements of CO2, CH4, H2O, and CO and N2O mixing ratios, and a 12-flask sampler for analysis of carbon cycle gases (CO2, CO, CH4, N2O, 13CO2, and trace hydrocarbon species). The aircraft payload also include measurements of aerosol properties (number size distribution, total number concentration, absorption, and scattering), cloud properties (droplet and ice size information), atmospheric thermodynamic state, and solar/infrared radiation.

  5. Development and Preliminary Tests of an Open-Path Airborne Diode Laser Absorption Instrument for Carbon Dioxide

    NASA Astrophysics Data System (ADS)

    Diskin, G. S.; DiGangi, J. P.; Yang, M. M.; Rana, M.; Slate, T. A.

    2015-12-01

    Carbon dioxide (CO2) is well known for its importance as an atmospheric greenhouse gas, with many sources and sinks around the globe. Understanding the fluxes of carbon into and out of the atmosphere is a complex and daunting challenge. One tool applied by scientists to measure the vertical flux of CO2 near the surface uses the eddy covariance technique, most often from towers but also from aircraft flying specific patterns over the study area. In this technique, variations of constituents of interest are correlated with fluctuations in the local vertical wind velocity. Measurement requirements are stringent, particularly with regard to precision, sensitivity to small changes, and temporal sampling rate. In addition, many aircraft have limited payload capability, so instrument size, weight, and power consumption are also important considerations. We report on the development and preliminary application of an airborne sensor for the measurement of atmospheric CO2. The instrument, modeled on the successful DLH (Diode Laser Hygrometer) series of instruments, has been tested in the laboratory and on the NASA DC-8 aircraft. Performance parameters such as accuracy, precision, sensitivity, specificity, and temporal response are discussed in the context of typical atmospheric variability and suitability for flux measurement applications. On-aircraft, in-flight intercomparison data have been obtained and will be discussed as well. Performance of the instrument has been promising, and continued flight testing is planned during 2016.

  6. Development and Preliminary Tests of an Open-Path Airborne Diode Laser Absorption Instrument for Carbon Dioxide

    NASA Technical Reports Server (NTRS)

    Diskin, Glenn S.; DiGangi, Joshua P.; Yang, Melissa; Slate, Thomas A.; Rana, Mario

    2015-01-01

    Carbon dioxide (CO2) is well known for its importance as an atmospheric greenhouse gas, with many sources and sinks around the globe. Understanding the fluxes of carbon into and out of the atmosphere is a complex and daunting challenge. One tool applied by scientists to measure the vertical flux of CO2 near the surface uses the eddy covariance technique, most often from towers but also from aircraft flying specific patterns over the study area. In this technique, variations of constituents of interest are correlated with fluctuations in the local vertical wind velocity. Measurement requirements are stringent, particularly with regard to precision, sensitivity to small changes, and temporal sampling rate. In addition, many aircraft have limited payload capability, so instrument size, weight, and power consumption are also important considerations. We report on the development and preliminary application of an airborne sensor for the measurement of atmospheric CO2. The instrument, modeled on the successful DLH (Diode Laser Hygrometer) series of instruments, has been tested in the laboratory and on the NASA DC-8 aircraft. Performance parameters such as accuracy, precision, sensitivity, specificity, and temporal response are discussed in the context of typical atmospheric variability and suitability for flux measurement applications. On-aircraft, in-flight data have been obtained and are discussed as well. Performance of the instrument has been promising, and continued flight testing is planned during 2016.

  7. 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.

  8. 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.

  9. Estimating Carbon STOCK Changes of Mangrove Forests Using Satellite Imagery and Airborne LiDAR Data in the South Sumatra State, Indonesia

    NASA Astrophysics Data System (ADS)

    Maeda, Y.; Fukushima, A.; Imai, Y.; Tanahashi, Y.; Nakama, E.; Ohta, S.; Kawazoe, K.; Akune, N.

    2016-06-01

    The purposes of this study were 1) to estimate the biomass in the mangrove forests using satellite imagery and airborne LiDAR data, and 2) to estimate the amount of carbon stock changes using biomass estimated. The study area is located in the coastal area of the South Sumatra state, Indonesia. This area is approximately 66,500 ha with mostly flat land features. In this study, the following procedures were carried out: (1) Classification of types of tree species using Satellite imagery in the study area, (2) Development of correlation equations between spatial volume based on LiDAR data and biomass stock based on field survey for each types of tree species, and estimation of total biomass stock and carbon stock using the equation, and (3) Estimation of carbon stock change using Chronological Satellite Imageries. The result showed the biomass and the amount of carbon stock changes can be estimated with high accuracy, by combining the spatial volume based on airborne LiDAR data with the tree species classification based on satellite imagery. Quantitative biomass monitoring is in demand for projects related to REDD+ in developing countries, and this study showed that combining airborne LiDAR data with satellite imagery is one of the effective methods of monitoring for REDD+ projects.

  10. 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.

  11. TMEM14C is required for erythroid mitochondrial heme metabolism

    PubMed Central

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

    2014-01-01

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

  12. Airborne measurements of Black Carbon using miniature high-performance Aethalometers during global circumnavigation campaign GLWF 2012

    NASA Astrophysics Data System (ADS)

    Močnik, Griša; Drinovec, Luka; Vidmar, Primož; Lenarčič, Matevž

    2013-04-01

    While ground-level measurements of atmospheric aerosols are routinely performed around the world, there exists very little data on their vertical and geographical distribution in the global atmosphere. This data is a crucial requirement for our understanding of the dispersion of pollutant species of anthropogenic origin, and their possible effects on radiative forcing, cloud condensation, and other phenomena which can contribute to adverse outcomes. Black Carbon (BC) is a unique tracer for combustion emissions, and can be detected rapidly and with great sensitivity by filter-based optical methods. It has no non-combustion sources and is not transformed by atmospheric processes. Its presence at altitude is unequivocal. Recent technical advances have led to the development of miniaturized instruments which can be operated on ultra-light aircraft, balloons or UAV's. From January to April 2012, a 'Pipistrel Virus' single-seat ultra-light aircraft flew around the world on a photographic and environmental-awareness mission. The flight track covered all seven continents; crossed all major oceans; and operated at altitudes around 3000 m ASL and up to 8900 m ASL. The aircraft carried a specially-developed high-sensitivity miniaturized dual-wavelength Aethalometer, which recorded BC concentrations with very high temporal resolution and sensitivity (see Reference below). We present examples of data from flight tracks over remote oceans, uninhabited land masses, and densely populated areas. Back-trajectories are used to show transport of polluted air masses. Measuring the dependence of the aerosol absorption on the wavelength, we show that aerosols produced during biomass combustion can be transported to high altitude in high concentrations. 1. __, Carbon Sampling Takes Flight, Science 2012, 335, 1286. 2. G. Močnik, L. Drinovec, M. Lenarčič, Airborne measurements of Black Carbon during the GLW Flight using miniature high-performance Aethalometers, accessed 8 January 2013

  13. Exposure vs toxicity levels of airborne quartz, metal and carbon particles in cast iron foundries.

    PubMed

    Moroni, Beatrice; Viti, Cecilia; Cappelletti, David

    2014-01-01

    Aerosol dust samples and quartz raw materials from different working stations in foundry plants were characterized in order to assess the health risk in this working environment. Samples were analysed by scanning and transmission electron microscopy coupled with image analysis and microanalysis, and by cathodoluminescence spectroscopy. In addition, the concentration and the solubility degree of Fe and other metals of potential health effect (Mn, Zn and Pb) in the bulk samples were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). Overall, the results indicate substantial changes in quartz crystal structure and texture when passing from the raw material to the airborne dust, which include lattice defects, non-bridging oxygen hole centres and contamination of quartz grains by metal and/or graphite particles. All these aspects point towards the relevance of surface properties on reactivity. Exposure doses have been estimated based on surface area, and compared with threshold levels resulting from toxicology. The possible synergistic effects of concomitant exposure to inhalable magnetite, quartz and/or graphite particles in the same working environment have been properly remarked.

  14. 14C as a tracer of labile organic matter in Antarctic benthic food webs

    NASA Astrophysics Data System (ADS)

    Purinton, Brett L.; DeMaster, David J.; Thomas, Carrie J.; Smith, Craig R.

    2008-11-01

    14C measurements were made on surface plankton, particle-trap material, surface sediment, benthic invertebrate gut contents, and body tissue samples to assess the effectiveness of this radioisotope as a tracer of labile organic carbon in Antarctic benthic food webs. Samples were collected on five cruises to the West Antarctic Peninsula (WAP) shelf between November 1999 and March 2001 as part of the Food for Benthos on the ANtarctic Continental-Shelf (FOODBANCS) Project. The 14C contents of the body tissues from a variety of deposit feeders (-126±13 per mil) were substantially enriched relative to the surface sediment (-234±13 per mil) and statistically similar to the organic matter collected in plankton tows (-135±10 per mil), indicating that recently produced marine plankton are the primary source of nutrition for these deposit feeders on the West Antarctic shelf. Selective ingestion was the primary feeding strategy used by echiuran worms and certain holothurians (i.e. Peniagone vignoni) for incorporating labile organic carbon into their tissues as demonstrated by the large differences (105±13 per mil) between surface sediment and gut content 14C activities. In contrast, digestive and/or assimilatory selection was the predominant strategy used by an irregular urchin ( Amphipneustes lorioli) and several other holothurians ( Protelpidia murrayi, Bathyplotes fuscivinculum and the head-down conveyor belt feeder, Molpadia musculus), as demonstrated by large differences (42±7 per mil) between the 14C activities of their foregut or whole-gut organic contents and their body tissues. Despite large fluctuations in carbon export from the euphotic zone, benthic feeding strategies remained essentially constant over the 15-month sampling period. No seasonal variation was evident in either the 14C abundance of the deposit-feeder body tissues, or in the 14C abundance of their gut contents. The mean 14C abundance in the body tissues of the two sub-surface deposit feeders ( A

  15. Using airborne HIAPER Pole-to-Pole Observations (HIPPO) to evaluate model and remote sensing estimates of atmospheric carbon dioxide

    NASA Astrophysics Data System (ADS)

    Frankenberg, Christian; Kulawik, Susan S.; Wofsy, Steven C.; Chevallier, Frédéric; Daube, Bruce; Kort, Eric A.; O'Dell, Christopher; Olsen, Edward T.; Osterman, Gregory

    2016-06-01

    In recent years, space-borne observations of atmospheric carbon dioxide (CO2) have been increasingly used in global carbon-cycle studies. In order to obtain added value from space-borne measurements, they have to suffice stringent accuracy and precision requirements, with the latter being less crucial as it can be reduced by just enhanced sample size. Validation of CO2 column-averaged dry air mole fractions (XCO2) heavily relies on measurements of the Total Carbon Column Observing Network (TCCON). Owing to the sparseness of the network and the requirements imposed on space-based measurements, independent additional validation is highly valuable. Here, we use observations from the High-Performance Instrumented Airborne Platform for Environmental Research (HIAPER) Pole-to-Pole Observations (HIPPO) flights from 01/2009 through 09/2011 to validate CO2 measurements from satellites (Greenhouse Gases Observing Satellite - GOSAT, Thermal Emission Sounder - TES, Atmospheric Infrared Sounder - AIRS) and atmospheric inversion models (CarbonTracker CT2013B, Monitoring Atmospheric Composition and Climate (MACC) v13r1). We find that the atmospheric models capture the XCO2 variability observed in HIPPO flights very well, with correlation coefficients (r2) of 0.93 and 0.95 for CT2013B and MACC, respectively. Some larger discrepancies can be observed in profile comparisons at higher latitudes, in particular at 300 hPa during the peaks of either carbon uptake or release. These deviations can be up to 4 ppm and hint at misrepresentation of vertical transport. Comparisons with the GOSAT satellite are of comparable quality, with an r2 of 0.85, a mean bias μ of -0.06 ppm, and a standard deviation σ of 0.45 ppm. TES exhibits an r2 of 0.75, μ of 0.34 ppm, and σ of 1.13 ppm. For AIRS, we find an r2 of 0.37, μ of 1.11 ppm, and σ of 1.46 ppm, with latitude-dependent biases. For these comparisons at least 6, 20, and 50 atmospheric soundings have been averaged for GOSAT, TES, and AIRS

  16. Long-term Airborne Black Carbon Measurements on a Lufthansa Passenger Aircraft

    NASA Astrophysics Data System (ADS)

    Cheng, Y.; Su, H.; Ditas, J.; Scharffe, D.; Wang, S.; Zhang, Y.; McMeeking, G. R.; Brenninkmeijer, C. A. M.; Poeschl, U.

    2015-12-01

    Aerosol particles containing black carbon are the most absorbing component of incoming solar radiation and exert a significant positive radiative forcing thus forming next to CO2 the strongest component of current global warming. Nevertheless, the role of black carbon particles and especially their complex interaction with clouds needs further research which is hampered by the limited experimental data, especially observations in the free troposphere, and in the UTLS (upper troposphere and lower stratosphere). In August 2014, a single particle soot photometer (SP2) was included in the extensive scientific payload of the CARIBIC (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container) project. CARIBIC is in operation since 1997 and carries out systematic observations of trace gas and aerosol sampling and on-line analyses, as well as DOAS remote sensing system at 10-12 km altitude. For this a special air freight container combining different instruments is transported on a monthly basis using a Lufthansa Airbus A340-600 passenger aircraft with destinations from 120°W to 120°E and 10°N to 75°N. The integration of a SP2 offers the possibility for the first long-term measurement of global distribution of black carbon. Up to date the SP2 measurements have been analyzed for 392 flights hours over four continents (Fig. 1). The first measurements show promising results of black carbon including periods when background concentrations in the UTLS were encountered. Beside a general distribution of number and mass of black carbon particles, peak events were detected with up to 20 times higher concentrations compared to the background. Moreover, high concentration plumes have been observed continuously over a range of 10,000 km. Interestingly, our results show also a generally lower amount of black carbon mass in the tropics compared to the mid latitude northern hemisphere.

  17. Long-term airborne black carbon measurements on a Lufthansa passenger aircraft

    NASA Astrophysics Data System (ADS)

    Ditas, Jeannine; Su, Hang; Scharffe, Dieter; Wang, Siwen; Zhang, Yuxuan; Brenninkmeijer, Carl; Pöschl, Ulrich; Cheng, Yafang

    2016-04-01

    Aerosol particles containing black carbon are the most absorbing component of incoming solar radiation and exert a significant positive radiative forcing thus forming next to CO² the strongest component of current global warming (Bond, 2013). Nevertheless, the role of black carbon particles and especially their complex interaction with clouds needs further research which is hampered by the limited experimental data, especially observations in the free and upper troposphere, and in the UTLS (upper troposphere and lower stratosphere). Many models underestimate the global atmospheric absorption attributable to black carbon by a factor of almost 3 (Bond, 2013). In August 2014, a single particle soot photometer was included in the extensive scientific payload of the CARIBIC (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container) project. CARIBIC is in operation since 1997 (with an interruption for 2002-2005) and carries out systematic observations at 10-12 km altitude. For this a special air freight container combining different instruments is transported on a monthly basis using a Lufthansa Airbus A340-600 passenger aircraft with destinations from 120°W to 120°E and 10°N to 75°N. The container has equipment for trace gas analyses and sampling and aerosol analyses and sampling and is connected to an inlet system that is part of the aircraft which contains a camera and DOAS remote sensing system. The integration of a single particle soot photometer (SP2) offers the possibility for the first long-term measurement of global distribution of black carbon and so far flights up to November 2015 have been conducted with more than 400 flight hours. So far the SP2 measurements have been analysed for flights over four continents from Munich to San Francisco, Sao Paulo, Tokyo, Beijing, Cape Town, Los Angeles and Hong Kong). The first measurements show promising results of black carbon measurements. Background concentrations in the UTLS

  18. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

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

  20. {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.

  1. Tracking airborne CO2 mitigation and low cost transformation into valuable carbon nanotubes

    PubMed Central

    Licht, Stuart

    2016-01-01

    Primary evidence of the direct uptake of atmospheric CO2 and direct transformation into carbon nanotubes, CNTs, is demonstrated through isotopic labeling, and provides a new high yield route to mitigate this greenhouse gas. CO2 is converted directly to CNTs and does not require pre-concentration of the airbone CO2. This C2CNT (CO2 to carbon nanotube) synthesis transforms CO2-gas dissolved in a 750 °C molten Li2CO3, by electrolysis, into O2-gas at a nickel electrode, and at a steel cathode into CNTs or carbon or nanofibers, CNFs. CNTs are synthesized at a 100-fold price reduction compared to conventional chemical vapour deposition, CVD, synthesis. The low cost conversion to a stable, value-added commodity incentivizes CO2 removal to mitigate climate change. The synthesis allows morphology control at the liquid/solid interface that is not available through conventional CVD synthesis at the gas/solid interface. Natural abundance 12CO2 forms hollow CNTs, while equivalent synthetic conditions with heavier 13CO2 favours closed core CNFs, as characterized by Raman, SEM and TEM. Production ease is demonstrated by the first synthesis of a pure 13C multiwalled carbon nanofiber. PMID:27279594

  2. Tracking airborne CO2 mitigation and low cost transformation into valuable carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Ren, Jiawen; Licht, Stuart

    2016-06-01

    Primary evidence of the direct uptake of atmospheric CO2 and direct transformation into carbon nanotubes, CNTs, is demonstrated through isotopic labeling, and provides a new high yield route to mitigate this greenhouse gas. CO2 is converted directly to CNTs and does not require pre-concentration of the airbone CO2. This C2CNT (CO2 to carbon nanotube) synthesis transforms CO2-gas dissolved in a 750 °C molten Li2CO3, by electrolysis, into O2-gas at a nickel electrode, and at a steel cathode into CNTs or carbon or nanofibers, CNFs. CNTs are synthesized at a 100-fold price reduction compared to conventional chemical vapour deposition, CVD, synthesis. The low cost conversion to a stable, value-added commodity incentivizes CO2 removal to mitigate climate change. The synthesis allows morphology control at the liquid/solid interface that is not available through conventional CVD synthesis at the gas/solid interface. Natural abundance 12CO2 forms hollow CNTs, while equivalent synthetic conditions with heavier 13CO2 favours closed core CNFs, as characterized by Raman, SEM and TEM. Production ease is demonstrated by the first synthesis of a pure 13C multiwalled carbon nanofiber.

  3. Identification of Biodegradation Pathways in a Multi-Process Phytoremediation System (MPPS) Using Natural Abundance 14C Analysis of PLFA

    NASA Astrophysics Data System (ADS)

    Cowie, B. R.; Greenberg, B. M.; Slater, G. F.

    2008-12-01

    Optimizing remediation of petroleum-contaminated soils requires thorough understanding of the mechanisms and pathways involved in a proposed remediation system. In many engineered and natural attenuation systems, multiple degradation pathways may contribute to observed contaminant mass losses. In this study, biodegradation in the soil microbial community was identified as a major pathway for petroleum hydrocarbon removal in a Multi-Process Phytoremediation System (MPPS) using natural abundance 14C analysis of Phospholipid Fatty Acids (PLFA). In contaminated soils, PLFA were depleted in Δ14C to less than -800‰, directly demonstrating microbial uptake and utilization of petroleum derived carbon14C = -992‰) during bioremediation. Mass balance indicated that more than 80% of microbial carbon was derived from petroleum hydrocarbons and a maximum of 20% was produced from metabolism of modern carbon sources. In contrast, in a nearby uncontaminated control soil, the microbial community maintained a nearly modern 14C signature, suggesting preferential degradation of more labile, recent carbon. Mass balance using δ13C and Δ14C of soil CO2 demonstrated that mineralization of petroleum carbon contributed 60-65% of soil CO2 at the contaminated site. The remainder was derived from atmospheric (27-30%) and decomposition of non- petroleum natural organic carbon (5-10%). The clean control exhibited substantially lower CO2 concentrations that were derived from atmospheric (55%) and natural organic carbon (45%) sources. This study highlights the value of using multiple carbon isotopes to identify degradation pathways in petroleum- contaminated soils undergoing phytoremediation and the power of natural abundance 14C to detect petroleum metabolism in natural microbial communities.

  4. Quality of graphite target for biological/biomedical/environmental applications of 14C-accelerator mass spectrometry.

    PubMed

    Kim, Seung-Hyun; Kelly, Peter B; Ortalan, Volkan; Browning, Nigel D; Clifford, Andrew J

    2010-03-15

    Catalytic graphitization for (14)C-accelerator mass spectrometry ((14)C-AMS) produced various forms of elemental carbon. Our high-throughput Zn reduction method (C/Fe = 1:5, 500 degrees C, 3 h) produced the AMS target of graphite-coated iron powder (GCIP), a mix of nongraphitic carbon and Fe(3)C. Crystallinity of the AMS targets of GCIP (nongraphitic carbon) was increased to turbostratic carbon by raising the C/Fe ratio from 1:5 to 1:1 and the graphitization temperature from 500 to 585 degrees C. The AMS target of GCIP containing turbostratic carbon had a large isotopic fractionation and a low AMS ion current. The AMS target of GCIP containing turbostratic carbon also yielded less accurate/precise (14)C-AMS measurements because of the lower graphitization yield and lower thermal conductivity that were caused by the higher C/Fe ratio of 1:1. On the other hand, the AMS target of GCIP containing nongraphitic carbon had higher graphitization yield and better thermal conductivity over the AMS target of GCIP containing turbostratic carbon due to optimal surface area provided by the iron powder. Finally, graphitization yield and thermal conductivity were stronger determinants (over graphite crystallinity) for accurate/precise/high-throughput biological, biomedical, and environmental (14)C-AMS applications such as absorption, distribution, metabolism, elimination (ADME), and physiologically based pharmacokinetics (PBPK) of nutrients, drugs, phytochemicals, and environmental chemicals.

  5. /sup 14/C distribution in the Atlantic Ocean

    SciTech Connect

    Stuiver, M.

    1980-05-20

    The amount of /sup 14/C produced by nuclear bomb testing that entered the Atlantic Ocean by late 1972 was 1.71 x 10/sup -8/ ..mu..mol/cm/sup 2/ of ocean surface area for the west Atlantic (36/sup 0/S-45/sup 0/N) and 1.18 x 10/sup -8/ ..mu..mol/cm/sup 2/ for the east Atlantic (50/sup 0/S-28/sup 0/N) Geochemical Ocean Sections Study stations. There are strong latitudinal differences in the integrated amount of bomb /sup 14/C content in Atlantic waters. Bomb-produced /sup 14/C is mostly encountered near the center of the large mid-latitude gyres, whereas the equatorial region has a lower /sup 14/C inventory. The average ocean wide vertical distribution of bomb /sup 14/C in the Atlantic can be explained by a vertical eddy diffusion coefficient of 4.0 cm/sup 2//s in the surface mixed layer plus thermocline gyre reservoirs. The average /sup 14/C activity per unit area measured in the Atlantic yields an atmosphere-ocean CO/sub 2/ exchange rate of 23 mol/m/sup 2/ yr, which is equivalent with an atmospheric CO/sub 2/ residence time of 6.8 years.

  6. 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.

  7. Airborne radioactivity survey of parts of Baggs SW and Baggs SE quadrangles, Carbon and Sweetwater counties, Wyoming

    USGS Publications Warehouse

    Henderson, J.R.

    1954-01-01

    The accompanying map shows the results of an airborne radioactivity survey in 151 square miles of Baggs SW and Baggs SE quadrangles, Wyoming. This area is part of a larger survey made in southern Carbon and Sweetwater counties by the U.S. Geological Survey, November 9-24, 1953. The work was undertaken as part of a cooperative program with the U.S. Atomic Energy Commission. The survey was made with scintillation detection equipment mounted in a C-47 aircraft and consisted of parallel east-west flight lines spaced at quarter mile intervals, flown approximately 500 feet above the ground. Aerial photographs were used for pilot guidance, and the flight path of the aircraft was recorded by a gyrostabilized, continuous-strip-film camera. The distance of the aircraft from the ground was measured with a continuously recording radio altimeter. The width of the zone on the ground form which the anomalous radiation is measured at the nominal 500 foot flight altitude varied with the areal extent and the intensity of radioactivity of the source. For strong sources of radioactivity the width of the zone may be as much as 1,400 feet. Thus, quarter mile spacing of the flight lines would be adequate to detect anomalies from strong sources of radioactivity; however, small areas of considerable radioactivity midway between flight lines may not be noted. The approximate locations of twelve radioactivity anomalies are shown on the accompanying map. The plotted position of the anomalies may be in error by as much as a quarter mile owing to the errors in available base maps or to the existence of areas on the base maps up to several square miles in which it is impossible to find and plot recognizable landmarks. The present technique of airborne radioactivity measurement does not permit distinguishing between activity due to thorium and that due to uranium. An anomaly, therefore, may represent radioactivity due entirely to one or to a combination of these elements. The radioactivity

  8. Investigating Seasonal Emissions of Carbon Dioxide and Methane in Northern California Using Airborne Measurements and Inverse Modeling

    NASA Astrophysics Data System (ADS)

    Johnson, M. S.; Xi, X.; Yates, E. L.; Iraci, L. T.; Potter, C. S.; Tanaka, T.; Tadic, J.; Loewenstein, M.; Jeong, S.; Fischer, M. L.; Gurney, K. R.

    2014-12-01

    Greenhouse gas (GHG) concentrations have increased over the past decades and are linked to increasing global surface temperatures and climate change. To counteract the trend of increasing atmospheric concentrations of GHGs, the state of California has passed the California Global Warming Solutions Act of 2006 (AB-32). This requires that by 2020, GHG (e.g., carbon dioxide (CO2) and methane (CH4)) emissions will be reduced to 1990 levels. Currently, California emits ~500 Tg yr-1 of CO2eq GHGs, with CO2 and CH4 contributing ~90% of the total. To quantify the success of AB-32, GHG emission rates must be more thoroughly quantified in California. Presently, uncertainties remain in the existing "bottom-up" emission inventories in California due to many contributing factors not being fully understood. To help alleviate these uncertainties, we have analyzed airborne GHG measurements and applied inverse modeling techniques to quantify GHG spatiotemporal concentration patterns and "top-down" emission rates. To assess the magnitude/spatial variation of GHGs, and to identify local emission "hot spots", airborne measurements of CO2 and CH4 were made by the Alpha Jet Atmospheric eXperiment (AJAX) in the boundary layer of the San Francisco Bay Area (SFBA) and northern San Joaquin Valley (SJV) in Jan.-Feb. 2013 and July-Aug. 2014. To quantify/constrain GHG emissions we applied the WRF-STILT model and inverse modeling techniques, in conjunction with AJAX data, to estimate "top-down" SFBA/SJV GHG emission rates. Model simulations utilized source apportioned a priori CO2 and CH4 emission inventories from the Vulcan Project (including NASA Carnegie Ames Stanford Approach (NASA-CASA) model CO2 biosphere fluxes) and the California Greenhouse Gas Emissions Measurement (CALGEM) Project, respectively. Results from the evaluation of a priori and posterior GHG concentrations/emissions in northern California using AJAX data, along with the analysis of CO2 and CH4 concentration spatiotemporal

  9. Double-pulse 2-μm integrated path differential absorption lidar airborne validation for atmospheric carbon dioxide measurement.

    PubMed

    Refaat, Tamer F; Singh, Upendra N; Yu, Jirong; Petros, Mulugeta; Remus, Ruben; Ismail, Syed

    2016-05-20

    Field experiments were conducted to test and evaluate the initial atmospheric carbon dioxide (CO2) measurement capability of airborne, high-energy, double-pulsed, 2-μm integrated path differential absorption (IPDA) lidar. This IPDA was designed, integrated, and operated at the NASA Langley Research Center on-board the NASA B-200 aircraft. The IPDA was tuned to the CO2 strong absorption line at 2050.9670 nm, which is the optimum for lower tropospheric weighted column measurements. Flights were conducted over land and ocean under different conditions. The first validation experiments of the IPDA for atmospheric CO2 remote sensing, focusing on low surface reflectivity oceanic surface returns during full day background conditions, are presented. In these experiments, the IPDA measurements were validated by comparison to airborne flask air-sampling measurements conducted by the NOAA Earth System Research Laboratory. IPDA performance modeling was conducted to evaluate measurement sensitivity and bias errors. The IPDA signals and their variation with altitude compare well with predicted model results. In addition, off-off-line testing was conducted, with fixed instrument settings, to evaluate the IPDA systematic and random errors. Analysis shows an altitude-independent differential optical depth offset of 0.0769. Optical depth measurement uncertainty of 0.0918 compares well with the predicted value of 0.0761. IPDA CO2 column measurement compares well with model-driven, near-simultaneous air-sampling measurements from the NOAA aircraft at different altitudes. With a 10-s shot average, CO2 differential optical depth measurement of 1.0054±0.0103 was retrieved from a 6-km altitude and a 4-GHz on-line operation. As compared to CO2 weighted-average column dry-air volume mixing ratio of 404.08 ppm, derived from air sampling, IPDA measurement resulted in a value of 405.22±4.15  ppm with 1.02% uncertainty and

  10. Biocomponent determination in vinegars with the help of 14C measured by liquid scintillation counting.

    PubMed

    Tudyka, Konrad; Pawlyta, Jacek

    2014-02-15

    This article presents a method of carbon extraction from vinegar used in preparation of liquid scintillation counting cocktails for measurements of low (14)C radioactivity. The presented method is relatively fast and can be used to produce liquid scintillation cocktails e.g., via benzene synthesis. In this work we present specific radiocarbon radioactivity determinations and based on them estimation of bio product content for five commercially available vinegars. All investigated vinegars are likely produced from plants in fermentation process.

  11. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

    paired with those from the South Pacific, it appears AAIW was not the vehicle that carried the 14C anomaly to lower latitudes, and therefore other hypotheses to explain the eastern tropical Pacific data are required. References Marchitto, T., Lehman, S., Ortiz, J., Fluckiger, J. & van Geen, A. Marine radiocarbon evidence for the mechanism of deglacial atmospheric CO2 rise. Science 316, 1456-1459 (2007). Stott, L., Southon, J., Timmermann, A. & Koutavas, A. Radiocarbon age anomaly at intermediate depth in the Pacific Ocean during the last deglaciation. Paleoceanography 24, PA2223 (2009). Pol-Holz, R.D., Keigwin, L., Southon, J., Hebbeln, D. & Mohtadi, M. No signature of abyssal carbon in intermediate waters off Chile during deglaciation. Nature Geosci. 3, 192-195 (2010). Oppo, D.W. & Horowitz, M. Glacial deep water geometry: South Atlantic benthic foraminiferal Cd/Ca and delta C-13 evidence. Paleoceanography 15, 147-160 (2000). Mangini, A., Godoy, J.M., Godoy, M.L., Kowsmann, R., Santos, G.M., Ruckelshausen, M., Schroeder-Ritzrau, A. & Wacker, L. Deep Sea corals off Brazil verify a poorly ventilated Southern Pacific Ocean during H2, H1 and the Younger Dryas. Earth Planet. Sci. Lett. 293, 269-276 (2010).

  13. 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.

  14. 14C and 13C characteristics of higher plant biomarkers in Washington margin surface sediments

    NASA Astrophysics Data System (ADS)

    Feng, Xiaojuan; Benitez-Nelson, Bryan C.; Montluçon, Daniel B.; Prahl, Fredrick G.; McNichol, Ann P.; Xu, Li; Repeta, Daniel J.; Eglinton, Timothy I.

    2013-03-01

    Plant wax lipids and lignin phenols are the two most common classes of molecular markers that are used to trace vascular plant-derived OM in the marine environment. However, their 13C and 14C compositions have not been directly compared, which can be used to constrain the flux and attenuation of terrestrial carbon in marine environment. In this study, we describe a revised method of isolating individual lignin phenols from complex sedimentary matrices for 14C analysis using high pressure liquid chromatography (HPLC) and compare this approach to a method utilizing preparative capillary gas chromatography (PCGC). We then examine in detail the 13C and 14C compositions of plant wax lipids and lignin phenols in sediments from the inner and mid shelf of the Washington margin that are influenced by discharge of the Columbia River. Plant wax lipids (including n-alkanes, n-alkanoic (fatty) acids, n-alkanols, and n-aldehydes) displayed significant variability in both δ13C (-28.3‰ to -37.5‰) and Δ14C values (-204‰ to +2‰), suggesting varied inputs and/or continental storage and transport histories. In contrast, lignin phenols exhibited similar δ13C values (between -30‰ and -34‰) and a relatively narrow range of Δ14C values (-45‰ to -150‰; HPLC-based measurement) that were similar to, or younger than, bulk OM (-195‰ to -137‰). Moreover, lignin phenol 14C age correlated with the degradation characteristics of this terrestrial biopolymer in that vanillyl phenols were on average ˜500 years older than syringyl and cinnamyl phenols that degrade faster in soils and sediments. The isotopic characteristics, abundance, and distribution of lignin phenols in sediments suggest that they serve as promising tracers of recently biosynthesized terrestrial OM during supply to, and dispersal within the marine environment. Lignin phenol 14C measurements may also provide useful constraints on the vascular plant end member in isotopic mixing models for carbon source

  15. Implications of ammonia emissions from post-combustion carbon capture for airborne particulate matter.

    PubMed

    Heo, Jinhyok; McCoy, Sean T; Adams, Peter J

    2015-04-21

    Amine scrubbing, a mature post-combustion carbon capture and storage (CCS) technology, could increase ambient concentrations of fine particulate matter (PM2.5) due to its ammonia emissions. To capture 2.0 Gt CO2/year, for example, it could emit 32 Gg NH3/year in the United States given current design targets or 15 times higher (480 Gg NH3/year) at rates typical of current pilot plants. Employing a chemical transport model, we found that the latter emission rate would cause an increase of 2.0 μg PM2.5/m(3) in nonattainment areas during wintertime, which would be troublesome for PM2.5-burdened areas, and much lower increases during other seasons. Wintertime PM2.5 increases in nonattainment areas were fairly linear at a rate of 3.4 μg PM2.5/m(3) per 1 Tg NH3, allowing these results to be applied to other CCS emissions scenarios. The PM2.5 impacts are modestly uncertain (±20%) depending on future emissions of SO2, NOx, and NH3. The public health costs of CCS NH3 emissions were valued at $31-68 per tonne CO2 captured, comparable to the social cost of carbon itself. Because the costs of solvent loss to CCS operators are lower than the social costs of CCS ammonia, there is a regulatory interest to limit ammonia emissions from CCS.

  16. What do we learn from EC (black carbon), OC and their Isotope Measurements in Fine Airborne PM over Canada?

    NASA Astrophysics Data System (ADS)

    Huang, L.; Zhang, W.; Sharma, S.; Brook, J.; Chan, T.; Leaitch, R.

    2009-04-01

    Elemental carbon and organic carbon (EC & OC) components in fine airborne carbonaceous particulate matter (PM) are major air pollutants existing in urban, rural and remote environments as well as key players in climate change (via radiative forcing). It is known that both EC (also called as black carbon or soot) and OC are released from various emission sources (e.g., fossil fuel combustion, biomass burning) and OC is also produced in the atmosphere through photochemical oxidations from gas phase organics. Tracking their spatial (e.g., from urban to rural to background air or latitudinal) and temporal (e.g. seasonal and inter-annual) distributions will provide valuable information to constraining emission sources and atmospheric transport/transformation mechanisms as well as to assessing effectiveness of mitigation for these pollutants. Sources/processes detecting and attributing are key aspects in both air quality and climate change research. Isotope measurements, as independent tools, can provide valuable insight to constrain those aspects. Duo to its inert nature, it is expected that the ^13C of EC won't be changed after emitting to the atmosphere, reflecting the signature of source, whereas the ^13Cof OC will have a various degree of changes through photochemical processes, depending on the history of the air mass. Therefore, an isotopic profile of ^13C in carbon components released at different temperature ranges can provide useful insight to the emission sources and formation processes in ambient PM. Quartz filter samples were collected at the five sites over Canada, from Toronto (a typical urban site), Egbert (a rural site, ~ 80 km northwest of Toronto), to Fraserdale, and Berm-TT (both are continental boreal forest sites), to Alert (an Arctic baseline site). EC and OC concentrations for those samples collected during the period (2006 - 2007) were determined using a thermal method (Totoal_900_EnCan) developed in Toronto lab at Environment Canada, which is

  17. Spatial patterns of vegetation biomass and soil organic carbon acquired from airborne lidar and hyperspectral imagery at Reynolds Creek Critical Zone Observatory

    NASA Astrophysics Data System (ADS)

    Will, R. M.; Li, A.; Glenn, N. F.; Benner, S. G.; Spaete, L.; Ilangakoon, N. T.

    2015-12-01

    Soil organic carbon distribution and the factors influencing this distribution are important for understanding carbon stores, vegetation dynamics, and the overall carbon cycle. Linking soil organic carbon (SOC) with aboveground vegetation biomass may provide a method to better understand SOC distribution in semiarid ecosystems. The Reynolds Creek Critical Zone Observatory (RC CZO) in Idaho, USA, is approximately 240 square kilometers and is situated in the semiarid Great Basin of the sagebrush-steppe ecosystem. Full waveform airborne lidar data and Next-Generation Airborne Visible/Infrared Imaging Spectrometer (AVIRIS-ng) collected in 2014 across the RC CZO are used to map vegetation biomass and SOC and then explore the relationships between them. Vegetation biomass is estimated by identifying vegetation species, and quantifying distribution and structure with lidar and integrating the field-measured biomass. Spectral data from AVIRIS-ng are used to differentiate non-photosynthetic vegetation (NPV) and soil, which are commonly confused in semiarid ecosystems. The information from lidar and AVIRIS-ng are then used to predict SOC by partial least squares regression (PLSR). An uncertainty analysis is provided, demonstrating the applicability of these approaches to improving our understanding of the distribution and patterns of SOC across the landscape.

  18. 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.

  19. 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.

  20. Airborne black carbon concentrations over an urban region in western India-temporal variability, effects of meteorology, and source regions.

    PubMed

    Bapna, Mukund; Sunder Raman, Ramya; Ramachandran, S; Rajesh, T A

    2013-03-01

    This study characterizes over 5 years of high time resolution (5 min), airborne black carbon (BC) concentrations (July 2003 to December 2008) measured over Ahmedabad, an urban region in western India. The data were used to obtain different time averages of BC concentrations, and these averages were then used to assess the diurnal, seasonal, and annual variability of BC over the study region. Assessment of diurnal variations revealed a strong association between BC concentrations and vehicular traffic. Peaks in BC concentration were co-incident with the morning (0730 to 0830, LST) and late evening (1930 to 2030, LST) rush hour traffic. Additionally, diurnal variability in BC concentrations during major festivals (Diwali and Dushera during the months of October/November) revealed an increase in BC concentrations due to fireworks displays. Maximum half hourly BC concentrations during the festival days were as high as 79.8 μg m(-3). However, the high concentrations rapidly decayed suggesting that local meteorology during the festive season was favorable for aerosol dispersion. A multiple linear regression (MLR) model with BC as the dependent variable and meteorological parameters as independent variables was fitted. The variability in temperature, humidity, wind speed, and wind direction accounted for about 49% of the variability in measured BC concentrations. Conditional probability function (CPF) analysis was used to identify the geographical location of local source regions contributing to the effective BC measured (at 880 nm) at the receptor site. The east north-east (ENE) direction to the receptor was identified as a major source region. National highway (NH8) and two coal-fired thermal power stations (at Gandhinagar and Sabarmati) were located in the identified direction, suggesting that local traffic and power plant emissions were likely contributors to the measured BC.

  1. Characterization of 14C in Neutron-Irradiated Graphite

    NASA Astrophysics Data System (ADS)

    LaBrier, Daniel Patrick

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

  2. 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.

  3. 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.

  4. 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.

  5. High-resolution 14C dating of a 25,000-year lake-sediment record from equatorial East Africa

    NASA Astrophysics Data System (ADS)

    Blaauw, Maarten; van Geel, Bas; Kristen, Iris; Plessen, Birgit; Lyaruu, Anna; Engstrom, Daniel R.; van der Plicht, Johannes; Verschuren, Dirk

    2011-10-01

    We dated a continuous, ˜22-m long sediment sequence from Lake Challa (Mt. Kilimanjaro area, Kenya/Tanzania) to produce a solid chronological framework for multi-proxy reconstructions of climate and environmental change in equatorial East Africa over the past 25,000 years. The age model is based on a total of 168 AMS 14C dates on bulk-organic matter, combined with a 210Pb chronology for recent sediments and corrected for a variable old-carbon age offset. This offset was estimated by i) pairing bulk-organic 14C dates with either 210Pb-derived time markers or 14C dates on grass charcoal, and ii) wiggle-matching high-density series of bulk-organic 14C dates. Variation in the old-carbon age offset through time is relatively modest, ranging from ˜450 yr during glacial and late glacial time to ˜200 yr during the early and mid-Holocene, and increasing again to ˜250 yr today. The screened and corrected 14C dates were calibrated sequentially, statistically constrained by their stratigraphical order. As a result their constrained calendar-age distributions are much narrower, and the calibrated dates more precise, than if each 14C date had been calibrated on its own. The smooth-spline age-depth model has 95% age uncertainty ranges of ˜50-230 yr during the Holocene and ˜250-550 yr in the glacial section of the record. The δ 13C values of paired bulk-organic and grass-charcoal samples, and additional 14C dating on selected turbidite horizons, indicates that the old-carbon age offset in Lake Challa is caused by a variable contribution of old terrestrial organic matter eroded from soils, and controlled mainly by changes in vegetation cover within the crater basin.

  6. Transfer of 14C-photosynthate to the sporocarp of an ectomycorrhizal fungus Laccaria amethystina.

    PubMed

    Teramoto, Munemasa; Wu, Bingyun; Hogetsu, Taizo

    2012-04-01

    Sporocarps of ectomycorrhizal fungi are strong carbon sinks for the source in host trees, but the details of carbon transfer from the host to the sporocarp are unknown. In this study, single seedlings of Japanese red pine (Pinus densiflora) colonised by Laccaria amethystina were grown on floral foam plates fitted in rhizoboxes, resulting in fruiting on the substrate. The seedlings were photosynthetically labelled with (14)CO(2); (14)C-labelled photosynthate transfer from leaves to sporocarps was then chased using a time-course autoradiography technique. (14)C was transferred to healthy, fresh sporocarps in a purple colour ranging from primordial to elongate sporocarps, but hardly to senesced ones that had faded to white or grey, or browned. This suggested that C is transferred only to physiologically active sporocarps. Two seedlings associated with a growing sporocarp were labelled again 7 and 16 days after the first labelling, respectively. (14)C accumulation in the sporocarps rose in a stepwise manner after the second labelling, indicating that sporocarps mainly used recently rather than previously photosynthesised C.

  7. ( 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.

  8. Production of 14C-labeled gas in BACTEC Neisseria Differentiation kits by Neisseria cinerea.

    PubMed

    Boyce, J M; Mitchell, E B; Knapp, J S; Buttke, T M

    1985-09-01

    Six strains of Neisseria cinerea were tested in BACTEC Neisseria Differentiation kits (Johnston Laboratories, Inc., Towson, Md.), and all yielded positive glucose growth indices and negative maltose and fructose growth indices. These results were similar to those achieved with Neisseria gonorrhoeae. However, most of the N. cinerea isolates tested yielded 3-h glucose growth indices that were lower than those obtained with gonococci. 14C-labeled gas was produced significantly faster (P less than 0.02) by N. gonorrhoeae than by N. cinerea. Additional studies suggested that the 14C-labeled gas produced by N. cinerea was carbon dioxide. N. cinerea strains were similar to Branhamella catarrhalis strains because both species failed to produce detectable acid from glucose, maltose, sucrose, fructose, and lactose in cysteine-tryptic agar media. However, in contrast to N. cinerea strains, B. catarrhalis strains did not metabolize glucose in BACTEC Neisseria Differentiation kits.

  9. Impacts of C-uptake by plants on the spatial distribution of (14)C accumulated in vegetation around a nuclear facility-Application of a sophisticated land surface (14)C model to the Rokkasho reprocessing plant, Japan.

    PubMed

    Ota, Masakazu; Katata, Genki; Nagai, Haruyasu; Terada, Hiroaki

    2016-10-01

    The impacts of carbon uptake by plants on the spatial distribution of radiocarbon ((14)C) accumulated in vegetation around a nuclear facility were investigated by numerical simulations using a sophisticated land surface (14)C model (SOLVEG-II). In the simulation, SOLVEG-II was combined with a mesoscale meteorological model and an atmospheric dispersion model. The model combination was applied to simulate the transfer of (14)CO2 and to assess the radiological impact of (14)C accumulation in rice grains during test operations of the Rokkasho reprocessing plant (RRP), Japan, in 2007. The calculated (14)C-specific activities in rice grains agreed with the observed activities in paddy fields around the RRP within a factor of four. The annual effective dose delivered from (14)C in the rice grain was estimated to be less than 0.7 μSv, only 0.07% of the annual effective dose limit of 1 mSv for the public. Numerical experiments of hypothetical continuous atmospheric (14)CO2 release from the RRP showed that the (14)C-specific activities of rice plants at harvest differed from the annual mean activities in the air. The difference was attributed to seasonal variations in the atmospheric (14)CO2 concentration and the growth of the rice plant. Accumulation of (14)C in the rice plant significantly increased when (14)CO2 releases were limited during daytime hours, compared with the results observed during the nighttime. These results indicated that plant growth stages and diurnal photosynthesis should be considered in predictions of the ingestion dose of (14)C for long-term chronic releases and short-term diurnal releases of (14)CO2, respectively.

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

    PubMed

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

    2015-01-01

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

  11. 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.

  12. 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.

  13. 17 CFR 240.14c-1 - Definitions.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... director or officer of the registrant or any of its parents or subsidiaries. (b) Employee benefit plan. For purposes of § 240.14c-7, the term “employee benefit plan” means any purchase, savings, option, bonus..., trustees or officers. (c) Entity that exercises fiduciary powers. The term “entity that exercises...

  14. Evaluation of an airborne triple-pulsed 2 μm IPDA lidar for simultaneous and independent atmospheric water vapor and carbon dioxide measurements.

    PubMed

    Refaat, Tamer F; Singh, Upendra N; Yu, Jirong; Petros, Mulugeta; Ismail, Syed; Kavaya, Michael J; Davis, Kenneth J

    2015-02-20

    Water vapor and carbon dioxide are the most dominant greenhouse gases directly contributing to the Earth's radiation budget and global warming. A performance evaluation of an airborne triple-pulsed integrated path differential absorption (IPDA) lidar system for simultaneous and independent monitoring of atmospheric water vapor and carbon dioxide column amounts is presented. This system leverages a state-of-the-art Ho:Tm:YLF triple-pulse laser transmitter operating at 2.05 μm wavelength. The transmitter provides wavelength tuning and locking capabilities for each pulse. The IPDA lidar system leverages a low risk and technologically mature receiver system based on InGaAs pin detectors. Measurement methodology and wavelength setting are discussed. The IPDA lidar return signals and error budget are analyzed for airborne operation on-board the NASA B-200. Results indicate that the IPDA lidar system is capable of measuring water vapor and carbon dioxide differential optical depth with 0.5% and 0.2% accuracy, respectively, from an altitude of 8 km to the surface and with 10 s averaging. Provided availability of meteorological data, in terms of temperature, pressure, and relative humidity vertical profiles, the differential optical depth conversion into weighted-average column dry-air volume-mixing ratio is also presented.

  15. Spatial variability in 14C-herbicide degradation in surface and subsurface soils.

    PubMed

    Charnay, Marie-Paule; Tuis, Sébastien; Coquet, Yves; Barriuso, Enrique

    2005-09-01

    The spatial variability in mineralization of atrazine, isoproturon and metamitron in soil and subsoil samples taken from a 135-ha catchment in north France was studied. Fifty-one samples from the top layer were taken to represent exhaustively the 31 agricultural fields and 21 soil types of the catchment. Sixteen additional samples were collected between depths of 0.7 and 10 m to represent the major geological materials encountered in the vadose zone of the catchment. All these samples were incubated with 14C-labelled atrazine under laboratory conditions at 28 degrees C. Fourteen selected surface samples which exhibited distinctly different behaviour for atrazine dissipation (including sorption and mineralization) were incubated with 14C-isoproturon and 14C-metamitron. Overall soil microbial activity and specific herbicide degradation activities were monitored during the incubations through measurements of total carbon dioxide and 14C-carbon dioxide respectively. At the end of the incubations, extractable and non-extractable (bound) residues remaining in soils were measured. Variability of herbicide dissipation half-life in soil surface samples was lower for atrazine and metamitron (CV < 12%) than for isoproturon (CV = 46%). The main contributor to the isoproturon dissipation variability was the variability of the extractable residues. For the other herbicides, spatial variability was mainly related to the variability of their mineralization. In all cases, herbicide mineralization half-lives showed higher variability than those of dissipation. Sorption or physicochemical soil properties could not explain atrazine and isoproturon degradation, whose main factors were probably directly related to the dynamics of the specific microbial degradation activity. In contrast, variability of metamitron degradation was significantly correlated to sorption coefficient (K(d)) through correlation with the sorptive soil components, organic matter and clay. Herbicide degradation

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

    SciTech Connect

    Kashgarian, M; Guilderson, T P

    2001-02-23

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

  17. Reassessment of sup 14 CO sub 2 compartmentation and of ( sup 14 C)formate oxidation in rat liver

    SciTech Connect

    Marsolais, C.; Lafreniere, F.; David, F.; Dodgson, S.J.; Brunengraber, H. )

    1989-11-25

    Our previous report had concluded that a fraction of ({sup 14}C)formate oxidation in liver occurs in the mitochondrion. This conclusion was based on the labeling patterns of urea and acetoacetate labeled via {sup 14}CO{sub 2} generated from ({sup 14}C)formate and other ({sup 14}C)substrates. We reassessed our interpretation in experiments conducted in (i) perifused mitochondria and (ii) isolated livers perfused with buffer containing ({sup 14}C)formate, ({sup 14}C)gluconolactone, {sup 14}CO{sub 2}, or NaH{sup 13}CO{sub 3}, in the absence and presence of acetazolamide, an inhibitor of carbonic anhydrase. Our data show that the cytosolic pools of bicarbonate and CO{sub 2} are not in isotopic equilibrium when {sup 14}CO{sub 2} is generated in the cytosol or is supplied as NaH{sup 14}CO3. We retract our earlier suggestion of a mitochondrial site of ({sup 14}C)formate oxidation.

  18. Does the 14C method estimate net photosynthesis? Implications from batch and continuous culture studies of marine phytoplankton

    NASA Astrophysics Data System (ADS)

    Pei, Shaofeng; Laws, Edward A.

    2013-12-01

    We carried out batch culture studies with seven species of marine phytoplankton and chemostat studies with two of the seven species to determine whether and to what extent 14C uptake approximated net photosynthesis. In two of seven cases, Isochrysis galbana and Dunaliella tertiolecta, cells uniformly labeled with 14C lost no activity when they were transferred to a 14C-free medium and allowed to grow in the light. In similar experiments with four other species, uniformly labeled cells lost activity when incubated in the light, but the loss rates were only a few percent per day. Thus these six species appear to respire primarily recently fixed carbon. In the case of the remaining species, Chlorella kessleri, loss rates of 14C in the light from uniformly labeled cells were about 29% per day, the apparent ratio of respiration to net photosynthesis being 0.4. Follow-up chemostat studies with I. galbana and C. kessleri grown under both light- and nitrate-limited conditions produced results consistent with the implications of the batch culture work: uptake of 14C by I. galbana after incubations of 24 h yielded estimates of photosynthetic carbon fixation equal to the product of the chemostat dilution rate and the concentration of organic carbon in the growth chamber. Similar experiments with C. kessleri produced 14C-based estimates of photosynthetic carbon fixation that exceeded the net rates of organic carbon production in the growth chamber by roughly 55%. Time-course studies with both species indicated that at high growth rates recently fixed carbon began to enter the respiratory substrate pool after a time lag of several hours, a result consistent with previous work with D. tertiolecta. The lag time appeared to be much shorter at low growth rates. The results with C. kessleri are similar to results previously reported for Chlorella pyrenoidosa and Amphidium carteri. Collectively these results suggest that 14C uptake by species with relatively high ratios of

  19. 14C in a stalagmite from NE India: preliminary results of dating near the limit of radiocarbon time scale

    NASA Astrophysics Data System (ADS)

    Hajdas, I.; Breitenbach, S. F. M.; Gierga, M.; Haug, G. H.; Adkins, J. F.; Biechele, C.; Bonani, G.; Maurer, M.; Wacker, L.

    2012-04-01

    The radiocarbon time scale covers the last 50,000 years and is being used in many applications. Old records close to the dating limit that can provide additional information about 14C variability are rare. Stalagmite MAW-3 has been collected in 2006 from Mawmluh Cave, Meghalaya, NE India and subsequently U-series dated at Caltech. Stable isotopes (delC13 and delO18) were measured at the Geological Institute of the ETH Zurich. MAW-3 grew through a large part of Marine Isotope Stage 3 and stable isotope results clearly show millennial scale climatic fluctuations known as Dansgaard-Oeschger events. U-series dating shows that our sample which grew during the time interval corresponding to the geomagnetic low intensity interval, called Laschamp Event at ca. 40 ka BP. Therefore, we test its usefulness for studies of potential 14C variability at the time. Samples for 14C dating were taken following the method of Hoffman et al. (2010). After preparation of a slab from the centre of the stalagmite small sub-samples for 14C and U-series analysis were cut with a wire saw. Samples containing ca. 10 mg of carbonate were dissolved in concentrated (85%) phosphoric acid and graphitized prior to AMS analysis at the ETH AMS facility. Preliminary results indicate that despite of the very high correction for the dead carbon fraction DCF (ca. 6000 14C yrs) and close proximity to the limit of the 14C dating method, we are still able to measure reliable 14C ages of this portion of MAW-3. We argue that, based on available results, fluctuations of DCF could be reconstructed. DCF changes show a correlation with stable isotope changes (delO18), i.e. precipitation patterns in the region.

  20. Retrieval of Vegetation Structure and Carbon Balance Parameters Using Ground-Based Lidar and Scaling to Airborne and Spaceborne Lidar Sensors

    NASA Astrophysics Data System (ADS)

    Strahler, A. H.; Ni-Meister, W.; Woodcock, C. E.; Li, X.; Jupp, D. L.; Culvenor, D.

    2006-12-01

    This research uses a ground-based, upward hemispherical scanning lidar to retrieve forest canopy structural information, including tree height, mean tree diameter, basal area, stem count density, crown diameter, woody biomass, and green biomass. These parameters are then linked to airborne and spaceborne lidars to provide large-area mapping of structural and biomass parameters. The terrestrial lidar instrument, Echidna(TM), developed by CSIRO Australia, allows rapid acquisition of vegetation structure data that can be readily integrated with downward-looking airborne lidar, such as LVIS (Laser Vegetation Imaging Sensor), and spaceborne lidar, such as GLAS (Geoscience Laser Altimeter System) on ICESat. Lidar waveforms and vegetation structure are linked for these three sensors through the hybrid geometric-optical radiative-transfer (GORT) model, which uses basic vegetation structure parameters and principles of geometric optics, coupled with radiative transfer theory, to model scattering and absorption of light by collections of individual plant crowns. Use of a common model for lidar waveforms at ground, airborne, and spaceborne levels facilitates integration and scaling of the data to provide large-area maps and inventories of vegetation structure and carbon stocks. Our research plan includes acquisition of Echidna(TM) under-canopy hemispherical lidar scans at North American test sites where LVIS and GLAS data have been or are being acquired; analysis and modeling of spatially coincident lidar waveforms acquired by the three sensor systems; linking of the three data sources using the GORT model; and mapping of vegetation structure and carbon-balance parameters at LVIS and GLAS resolutions based on Echidna(TM) measurements.

  1. Cluster Structure and 3-body decay in 14C

    NASA Astrophysics Data System (ADS)

    Carpenter, Lisa; Bazin, D.; Mittig, W.; Ayyad, Y.; Beceiro Novo, S.; Bradt, J.; Ahn, T.; Kolata, J. J.; Becchetti, F. D.; Fritsch, A.

    2016-09-01

    Recent model calculations with most advanced methods for cluster states have shown the need of experimental data to probe the structure of light exotic nuclei, including those with α-clustering, such as 14C. The Prototype Active Target Time Projection Chamber (PAT-TPC) allows us to investigate these types of structures, giving access to the full excitation function with a single beam energy. This type of experiment measures resonances in 14C that can be compared to the models. With an improved Micromegas pad plane with a circular backgammon design we are able to investigate 3-body decays in addition to 2-body scattering. The measurements were carried out by resonant alpha-scattering on 10Be beam delivered by the TwinSol facility at the University of Notre Dame. This work is supported by the National Science Foundation.

  2. The behaviour of (14)C profiles in Helianthus seedlings.

    PubMed

    Whittle, C M

    1971-06-01

    The log. (14)C activity/distance profile in the stems of Helianthus seedlings consists of two main parts: region 1, the linear advancing front and region 2, which is also linear but with a less steep slope. As the front passes down the stem, the slope of region 1 remains constant but the amplitude of the front becomes attenuated. The attenuation increases with temperature. The apparent velocity of the profile, which can be derived from the position of the front, is also temperature dependent. Small amounts of (14)C occur in the stem ahead of the profile; these amounts increase with a rise of temperature. Region 2 behaves differently: its slope decreases steadily with time but it is insensitive to temperature. The behaviour of this region is dependent on the movement of tracer into an immobile fraction as well as on the longitudinal movement of tracer in the translocation stream.

  3. The impact of biochar on the bioaccessibility of (14)C-phenanthrene in aged soil.

    PubMed

    Ogbonnaya, O U; Adebisi, O O; Semple, K T

    2014-11-01

    Biochar is a carbon rich product from the incomplete combustion of biomass and it has been shown to reduce bioavailability of organic contaminants through adsorption. This study investigated the influence of 0%, 1%, 5% and 10% of two different particle sized wood biochars (≤2 mm and 3-7 mm) on the bioaccessibility of (14)C-phenanthrene (10 mg kg(-1)) in aged soil. The extent of (14)C-phenanthrene mineralisation by phenanthrene-degrading Pseudomonas sp. inoculum was monitored over a 14 day period in respirometric assays and compared to hydroxypropyl-β-cyclodextrin (HPCD) aqueous extraction. Notably, biochar amendments showed significant reduction in extents of mineralisation and HPCD extraction. Linear correlations between HPCD extractability and the total amount mineralised revealed good correlations, with 2 mm biochar showing a best fit (r(2) = 0.97, slope = 1.11, intercept = 1.72). Biochar reduced HPCD extractability and bioaccessibility of (14)C-phenanthrene to microorganisms in a similar manner. Biochar can aid risk reduction to phenanthrene exposure to biota in soil and HPCD can serve as a useful tool to assess the extent of exposure in biochar-amended soils.

  4. Accelerator mass spectrometry best practices for accuracy and precision in bioanalytical (14)C measurements.

    PubMed

    Vogel, John S; Giacomo, Jason A; Schulze-König, Tim; Keck, Bradly D; Lohstroh, Peter; Dueker, Stephen

    2010-03-01

    Accelerator mass spectrometers have an energy acceleration and charge exchange between mass definition stages to destroy molecular isobars and allow single ion counting of long-lived isotopes such as (14)C (t½=5370 years.). 'Low' voltage accelerations to 200 kV allow laboratory-sized accelerator mass spectrometers instruments for bioanalytical quantitation of (14)C to 2-3% precision and accuracy in isolated biochemical fractions. After demonstrating this accuracy and precision for our new accelerator mass spectrometer, we discuss the critical aspects of maintaining quantitative accuracy from the defined biological fraction to the accelerator mass spectrometry quantitation. These aspects include sufficient sample mass for routine rapid sample preparation, isotope dilution to assure this mass, isolation of the carbon from other sample combustion gasses and use of high-efficiency biochemical separations. This review seeks to address a bioanalytical audience, who should know that high accuracy data of physiochemical processes within living human subjects are available, as long as a (14)C quantitation can be made indicative of the physiochemistry of interest.

  5. 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.

  6. Estimating Aboveground Forest Carbon Stock of Major Tropical Forest Land Uses Using Airborne Lidar and Field Measurement Data in Central Sumatra

    NASA Astrophysics Data System (ADS)

    Thapa, R. B.; Watanabe, M.; Motohka, T.; Shiraishi, T.; shimada, M.

    2013-12-01

    Tropical forests are providing environmental goods and services including carbon sequestration, energy regulation, water fluxes, wildlife habitats, fuel, and building materials. Despite the policy attention, the tropical forest reserve in Southeast Asian region is releasing vast amount of carbon to the atmosphere due to deforestation. Establishing quality forest statistics and documenting aboveground forest carbon stocks (AFCS) are emerging in the region. Airborne and satellite based large area monitoring methods are developed to compliment conventional plot based field measurement methods as they are costly, time consuming, and difficult to implement for large regions. But these methods still require adequate ground measurements for calibrating accurate AFCS model. Furthermore, tropical region comprised of varieties of natural and plantation forests capping higher variability of forest structures and biomass volumes. To address this issue and the needs for ground data, we propose the systematic collection of ground data integrated with airborne light detection and ranging (LiDAR) data. Airborne LiDAR enables accurate measures of vertical forest structure, including canopy height and volume demanding less ground measurement plots. Using an appropriate forest type based LiDAR sampling framework, structural properties of forest can be quantified and treated similar to ground measurement plots, producing locally relevant information to use independently with satellite data sources including synthetic aperture radar (SAR). In this study, we examined LiDAR derived forest parameters with field measured data and developed general and specific AFCS models for tropical forests in central Sumatra. The general model is fitted for all types of natural and plantation forests while the specific model is fitted to the specific forest type. The study region consists of natural forests including peat swamp and dry moist forests, regrowth, and mangrove and plantation forests

  7. 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.

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

    SciTech Connect

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

    1986-04-01

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

  9. Metabolism of U/sup 14/C palmitic and 1-/sup 14/C caproic acids by lettuce seeds during early germination

    SciTech Connect

    Salon, C.; Raymond, P.; Pradet, A.

    1986-04-01

    Germinating lettuce embryos (before radicule emergence) were fed with either U/sup 14/C palmitic acid or 1/sup 14/C caproic acid until a metabolic steady state was reached. The bulk of labelled caproate was evolved as respiratory CO/sub 2/ (52%) and incorporated into organic and amino acids (38%) and only a small part incorporated into lipids whereas most of labelled palmitic acid was found into lipids (92%) and only 8% evolved as CO/sub 2/ and incorporated into organic and amino acids. The label distribution at steady state in intermediates linked to the T.C.A. cycle was interpreted using a metabolic model. They found that the two fatty acids were degraded by ..beta..-oxidation and incorporated into the T.C.A. cycle as acetylCoA suggesting that ..beta..-oxidation is located in the mitochondria. The results also indicate that lipids contribute for at least 90% to the carbon supply to respiration.

  10. A batch preparation method for graphite targets with low background for AMS [sup 14]C measurements

    SciTech Connect

    Kitagawa, Hiroyuki International Research Center for Japanese Studies, Nishikyp-ku, Kyoto ); Masuzawa, Toshiyuki; Matsumoto, Eiji ); Makamura, Toshio )

    1993-01-01

    The authors have developed a method of graphitization from CO[sub 2] samples for accurate [sup 14]C measurements by accelerator mass spectrometry. Their batch method, using a sealed Vycor tube, reduces the risk of contamination during graphitization and makes it possible to prepare many samples in a short time (typically 20 samples per day). They also describe details of the target-preparation method involving carbon isotopic fractionation during graphitization, yield of graphite from CO[sub 2], ion-beam intensity of the target, and background (or blank) level estimated using bituminous coal.

  11. Searching For A Suitable Gas Ion Source For 14C Accelerator Mass Spectrometry

    SciTech Connect

    Reden, Karl von; Roberts, Mark; Han, Baoxi; Schneider, Robert; Wills, John

    2007-08-10

    This paper describes the challenges facing 14C Accelerator Mass Spectrometry (AMS) in the effort to directly analyze the combusted effluent of a chromatograph (or any other continuous source of sample material). An efficient, low-memory negative gas ion source would greatly simplify the task to make this a reality. We discuss our tests of a microwave ion source charge exchange canal combination, present an improved design, and hope to generate more interest in the negative ion source community to develop a direct-extraction negative carbon gas ion source for AMS.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  13. 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.

  14. Amount and identity of (/sup 14/C) residues in bluegills (Lepomis macrochirus) exposed to (/sup 14/C)triclopyr

    SciTech Connect

    Lickly, T.D.; Murphy, P.G.

    1987-01-01

    The level and identity of (/sup 14/C) residues in bluegills (Lepomis macrochirus) exposed to 2.5 mg/L (/sup 14/C) triclopyr (3,5,6-trichloro-2-pyridinyloxyacetic acid) have been determined. The highest level of radioactivity observed in the flesh of a fish at any time point (0.13 mg/kg, calculated as equivalent mg triclopyr/kg fish) was less than 5% of the fish exposure level of 2.5 mg/L, while the maximum level in the remainder (head, skin, and viscera) was about 95% (2.33 mg/kg) of the fish exposure level, indicating no concentrating effect. The principal components observed in the fish tissues were triclopyr, 3,5,6-trichloro-2-pyridinol, 2-methoxy-3,5,6-trichloropyridine and a conjugate. These components accounted for greater than 75% of all the residues observed.

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

    SciTech Connect

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

    1995-12-31

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

  16. 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

  17. In vitro O 2 fluxes compared with 14C production and other rate terms during the JGOFS Equatorial Pacific experiment

    NASA Astrophysics Data System (ADS)

    Bender, Michael; Orchardo, Joe; Dickson, Mary-Lynn; Barber, Richard; Lindley, Steven

    1999-04-01

    We report rates of gross and net O 2 production measured in vitro during JGOFS cruises in the equatorial Pacific in spring and fall, 1992. We scale O 2 productivities to net and gross C production. We then compare the calculated rates with 14C production and with new/export production measured by various techniques. 14C productivities in samples incubated for 24 h are about 45% of gross carbon production rates calculated from gross O 2 production. The difference is compatible with expected rates of the Mehler reaction, photorespiration, excretion, and community mitochondrial respiration. 14C production rates are similar to net carbon production rates in the upper half of the euphotic zone. At lower irradiances, where net C production can be zero or less, 14C productivities lie between net community production and gross primary production. Net carbon production rates in vitro are a factor of =4-20 times greater than estimates from drifting sediment trap and tracer transport studies. This difference probably reflects anomalous accumulation of POC in bottles because of the exclusion of grazers.

  18. Influence of selected pesticides on the microbial degradation of 14C-triallate and 14C-diallate in soil.

    PubMed

    Anderson, J P; Domsch, K H

    1980-01-01

    Degradation in soil of [allyl-2-14C]triallate and [carbonyl-14C]diallate herbicides, as affected by other selected pesticides, was studied in an incubation system that allowed recovery of 95 to 100% of added 14C. The amount and sequence of pesticide additions simulated field use in the protection of wheat (triallate) and sugar beets (diallate). Neither the rate nor the pattern of triallate degradation in soil was influenced by the following sequence of formulated pesticides: dinoseb acetate, (bentazon + dichlorprop + 2,4,5-T), 2,4-D, (chlorcholinchloride + cholinchloride), tridemorph, and thiophanate. Similarly, diallate degradation was unaffected by pyrazon, dimethoate, and thiophanate. The effect of azinphosmethyl was unclear. In contrast, chlorpyrifos reduced diallate degradation by approximately 14% relative to the occurring in the insecticide's absence. This effect was caused by chlorpyrifos and not its formulation components. Chlorpyrifos was also found to partially inhibit degradation of triallate in soil. Inhibition of neither herbicide was considered to be of ecological significance. Triallate, diallate, and thiophanate were applied at 1 microgram/g; all others were at 2 microgram/g.

  19. 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.

  20. 14C-based Source Apportionment of Carbonaceous Aerosols in Switzerland for 2008 - 2012

    NASA Astrophysics Data System (ADS)

    Zotter, Peter; Ciobanu, Gabriela; Zhang, Yanlin; El-Haddad, Imad; Szidat, Sönke; Wacker, Lukas; Baltensperger, Urs; Prévôt, André

    2013-04-01

    Carbonaceous particles (total carbon, TC) are a major fraction of the fine aerosol and affect climate and human health. TC is classified into the sub-fractions elemental carbon (EC) and organic carbon (OC). EC originates only from fossil fuel combustion and biomass burning. OC can be emitted directly as primary organic aerosol from biogenic emissions, wood burning and fossil fuel combustion or can be formed in-situ in the atmosphere (secondary organic aerosol) (Szidat et al. 2006). Radiocarbon (14C) analysis is a direct and quantitative tool for distinguishing fossil and non-fossil sources, since 14C in fossil fuels is completely depleted whereas other sources have a contemporary 14C level. This study presents source apportionment results from the winter season over a time period of 5 years (2007/2008-2011/2012) using 14C measurements on aerosol filters collected simultaneously at 16 air quality monitoring stations across Switzerland. For every year 5 winter smog episode days were selected from which filters from all stations were analyzed. To resolve a good spatial variability 11 stations north and 5 stations south of the Alps were selected. This 14C data set is unique around the world concerning the number of analyzed filters and the duration. The filter sampling was conducted using high volume samplers with PM10 inlets and a time resolution of 24h. Separation of OC and EC was carried out using the THEODORE system (Szidat et al. 2004) and a Sunset EC/OC analyzer (Zhang et al. 2012), respectively. The resulting CO2 was cryo-trapped and sealed in glass ampoules for 14C measurements, performed with the Mini Carbon Dating System MICADAS (Ruff et al. 2007) at the Swiss Federal Institute of Technology (ETH) Zürich. The results for non-fossil (NF) OC (5 year average) are 81% ± 10% for north and 85% ± 8% for south of the Alps. ECNF values range from 31% to 53% north and from 36% to 66% south of the Alps. Both, the OCNF and ECNF show higher values south of the Alps

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

    Code of Federal Regulations, 2011 CFR

    2011-04-01

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

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

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

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

    Periphytic algae attached to a streambed substrate (periphyton) are an important primary producer in stream ecosystems. We determined the isotopic composition of chlorophyll a in periphyton collected from a stream flowing on limestone bedrock in the Seri River, central Japan. Stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) and natural radiocarbon abundances (Δ14C) were measured in chlorophyll a (δ13Cchl, δ15Nchl and Δ14Cchl) and bulk (δ13Cbulk, δ15Nbulk and Δ14Cbulk) for periphyton, a pure aquatic primary producer (Cladophora sp.) and a terrestrial primary producer (Quercus glauca). Periphyton δ13Cbulk and δ13Cchl values did not necessarily correspond to δ13Cbulk for an algal-grazing specialist (Epeorus latifolium). Periphyton Δ14Cchl values (-258 ‰ in April and -190 ‰ in October) were slightly lower than Δ14Cbulk values (-228 ‰ in April and -179 ‰ in October) but were close to the Δ14C value for dissolved inorganic carbon (DIC; -217 ± 31 ‰), which is a mixture of weathered carbonates14C = -1000 ‰), CO2 derived from aquatic and terrestrial organic matters (variable Δ14C) and dissolved atmospheric CO2 (Δ14C approximately +30 ‰ in 2013). Δ14Cchl values were also close to Δ14Cbulk for E. latifolium (-215 ‰ in April and -199 ‰ in October) and Cladophora sp. (-210 ‰), whereas the Δ14Cbulk value for Q. glauca (+27 ‰) was closer to Δ14C for atmospheric CO2. Although the bulk isotopic composition of periphyton is recognised as a surrogate for the photosynthetic algal community, natural periphyton is a mixture of aquatic and terrestrial organic materials. Our results indicate that the bulk periphyton matrix at the study site consists of 89 to 95 % algal carbon (derived from 14C-depleted DIC) and 5 to 11 % terrestrial organic carbon (derived from 14C-enriched atmospheric CO2).

  6. Using Airborne Microwave Remotely Sensed Root-Zone Soil Moisture and Flux Measurements to Improve Regional Predictions of Carbon Fluxes in a Terrestrial Biosphere Model

    NASA Astrophysics Data System (ADS)

    Zhang, K.; Antonarakis, A. S.; Medvigy, D.; Burgin, M. S.; Crow, W. T.; Milak, S.; Jaruwatanadilok, S.; Truong-Loi, M.; Moghaddam, M.; Saatchi, S. S.; Cuenca, R. H.; Moorcroft, P. R.

    2013-12-01

    North American ecosystems are critical components of the global carbon cycle, exchanging large amounts of carbon dioxide and other gases with the atmosphere. Net ecosystem exchange (NEE) of CO2 between atmosphere and ecosystems quantifies these carbon fluxes, but current continental-scale estimates contain high levels of uncertainty. Root-zone soil moisture (RZSM) and its spatial and temporal heterogeneity influences NEE and improved estimates can help reduce uncertainty in NEE estimates. We used the RZSM measurements from the Airborne Microwave Observatory of Subcanopy and Subsurface (AirMOSS) mission, and the carbon, water and energy fluxes observed by the eddy-covariance flux towers to constrain the Ecosystem Demography Model 2.2 (ED2.2) to improve its predictions of carbon fluxes. The parameters of the ED2.2 model were first optimized at seven flux tower sites in North America, which represent six different biomes, by constraining the model against a suite of flux measurements and forest inventory measurements through a Bayesian Markov-Chain Monte Carlo framework. We further applied the AirMOSS RZSM products to constrain the ED2.2 model to achieve better estimates of regional NEE. Evaluation against flux tower measurements and forest dynamics measurements shows that the constrained ED2.2 model produces improved predictions of monthly to annual carbon fluxes. The remote sensing based RZSM can further help improve the spatial patterns and temporal variations of model NEE. The results demonstrate that model-data fusion can substantially improve model performance and highlight the important role of RZSM in regulating the spatial and temporal heterogeneities of carbon fluxes.

  7. A First Look at Airborne Imaging Spectrometer (AIS) Data in an Area of Altered Volcanic Rocks and Carbonate Formations, Hot Creek Range, South Central Nevada

    NASA Technical Reports Server (NTRS)

    Feldman, S. C.; Taranik, J. V.; Mouat, D. A.

    1985-01-01

    Three flight lines of Airborne Imaging Spectrometer (AIS) data were collected in 128 bands between 1.2 and 2.4 microns in the Hot Creek Range, Nevada on July 25, 1984. The flight lines are underlain by hydrothermally altered and unaltered Paleozoic carbonates and Tertiary rhyolitic to latitic volcanics in the Tybo mining district. The original project objectives were to discriminate carbonate rocks from other rock types, to distinguish limestone from dolomite, and to discriminate carbonate units from each other using AIS imagery. Because of high cloud cover over the prime carbonate flight line and because of the acquisition of another flight line in altered and unaltered volcanics, the study has been extended to the discrimination of alteration products. In an area of altered and unaltered rhyolites and latites in Red Rock Canyon, altered and unaltered rock could be discriminated from each other using spectral features in the 1.16 to 2.34 micron range. The altered spectral signatures resembled montmorillonite and kaolinite. Field samples were gathered and the presence of montmorillonite was confirmed by X-ray analysis.

  8. 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.

  9. 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

  10. 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.

  11. Impacts of stable element intake on 14C and 129I dose estimates.

    PubMed

    Moeller, Dade W; Ryan, Michael T; Sun, Lin-Shen C; Cherry, Robert N

    2005-10-01

    The purpose of this study was to evaluate and provide insights related to the influence of the intake of stable isotopes of carbon and iodine on the committed doses due to the ingestion of (14)C and (129)I. This was accomplished through the application of two different computational approaches. The first was based on the assumption that ground (drinking) water was the only source of intake of (14)C and (129)I, as well as stable carbon and stable iodine. In the second, the intake of (14)C and (129)I was still assumed to be restricted to that in the ground (drinking) water, but the intake of stable carbon and stable iodine was expanded to include that in other components of the diet. The doses were estimated using either a conversion formula or the applicable dose coefficients in Federal Guidance Reports No. 11 and No. 13. Serving as input for the analyses was the estimated maximum concentrations of (14)C or (129)I that would be present in the ground water due to potential releases from the proposed Yucca Mountain high-level radioactive waste repository during the first 10,000 y after closure. The estimated contributions of stable carbon and iodine through the consumption of ground water were based on analyses of samples collected in the Amargosa Valley, NV. The contributions through dietary intake were based on surveys conducted in the United States. Based on the accompanying analyses, it was noted that stable isotope intake has a significant effect on the estimated doses due to the intake of radioactive isotopes of the same element. While this is a well-known fact, this observation has international implications in terms of dose estimates for key radionuclides, such as (14)C and (129)I, a primary reason being the wide variations in the intakes of stable carbon and iodine in various countries. For this reason, analysts planning to apply the dose coefficients developed by the International Commission on Radiological Protection (ICRP) should either confirm that the

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

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

    We determined the isotopic composition of chlorophyll a in periphytic algae attached to a streambed substrate (periphyton). The samples were collected from a stream flowing on limestone bedrock in the Seri River, central Japan. Stable isotope ratios of carbon (δ13C) and nitrogen (δ15N) and natural radiocarbon abundances (Δ14C) were measured in chlorophyll a (δ13Cchl, δ15Nchl and Δ14Cchl) and bulk (δ13Cbulk, δ15Nbulk and Δ14Cbulk) for periphyton, pure aquatic primary producer (Cladophora sp.) and terrestrial primary producer (Quercus glauca). Periphyton δ13Cbulk and δ13Cchl values did not necessarily correspond to δ13Cbulk for an algal-grazing specialist (Mayfly larva, Epeorus latifolium), suggesting that periphyton δ13C values do not faithfully trace carbon transfer between primary producers and primary consumers. Periphyton Δ14Cchl values (-258 ‰ in April and -190 ‰ in October) were slightly lower than Δ14Cbulk values (-228 ‰ in April and -179 ‰ in October), but were close to the Δ14C value for dissolved inorganic carbon (DIC) (-217 ± 31 ‰), which is a mixture of weathered carbonates14C = -1000 ‰) and dissolved atmospheric CO2 (Δ14C approximately +30 ‰ in 2013). Δ14Cchl values were also close to Δ14Cbulk for E. latifolium (-215 ‰ in April and -199 ‰ in October) and Cladophora sp. (-210 ‰), whereas the Δ14Cbulk value for Q. glauca (+27 ‰) was closer to Δ14C for atmospheric CO2. Although the bulk isotopic composition of periphyton is recognised as a surrogate for the photosynthetic algal community, natural periphyton is a mixture of aquatic and terrestrial organic materials. Our results indicate that the bulk periphyton matrix at the study site consists of 89 to 95 % algal carbon (derived from 14C-depleted DIC) and 5 to 11 % terrestrial organic carbon (derived from 14C-enriched atmospheric CO2).

  15. Solid-State 2-Micron Laser Transmitter Advancement for Wind and Carbon Dioxide Measurements From Ground, Airborne, and Space-Based Lidar Systems

    NASA Technical Reports Server (NTRS)

    Singh, Upendra N.; Kavaya, Michael J.; Koch, Grady; Yu, Jirong; Ismail, Syed

    2008-01-01

    NASA Langley Research Center has been developing 2-micron lidar technologies over a decade for wind measurements, utilizing coherent Doppler wind lidar technique and carbon dioxide measurements, utilizing Differential Absorption Lidar (DIAL) technique. Significant advancements have been made towards developing state-of-the-art technologies towards laser transmitters, detectors, and receiver systems. These efforts have led to the development of solid-state lasers with high pulse energy, tunablility, wavelength-stability, and double-pulsed operation. This paper will present a review of these technological developments along with examples of high resolution wind and high precision CO2 DIAL measurements in the atmosphere. Plans for the development of compact high power lasers for applications in airborne and future space platforms for wind and regional to global scale measurement of atmospheric CO2 will also be discussed.

  16. 2-micron triple-pulse integrated path differential absorption lidar development for simultaneous airborne column measurements of carbon dioxide and water vapor in the atmosphere

    NASA Astrophysics Data System (ADS)

    Singh, Upendra N.; Petros, Mulugeta; Refaat, Tamer F.; Yu, Jirong

    2016-05-01

    For more than 15 years, NASA Langley Research Center (LaRC) has contributed in developing several 2-micron carbon dioxide active remote sensors using the DIAL technique. Currently, an airborne 2-micron triple-pulse integrated path differential absorption (IPDA) lidar is under development at NASA LaRC. This paper focuses on the advancement of the 2-micron triple-pulse IPDA lidar development. Updates on the state-of-the-art triple-pulse laser transmitter will be presented including the status of wavelength control, packaging and lidar integration. In addition, receiver development updates will also be presented, including telescope integration, detection systems and data acquisition electronics. Future plan for IPDA lidar system for ground integration, testing and flight validation will be presented.

  17. 2-Micron Triple-Pulse Integrated Path Differential Absorption Lidar Development for Simultaneous Airborne Column Measurements of Carbon Dioxide and Water Vapor in the Atmosphere

    NASA Technical Reports Server (NTRS)

    Singh, Upendra N.; Petros, Mulugeta; Refaat, Tamer F.; Yu, Jirong

    2016-01-01

    For more than 15 years, NASA Langley Research Center (LaRC) has contributed in developing several 2-micron carbon dioxide active remote sensors using the DIAL technique. Currently, an airborne 2-micron triple-pulse integrated path differential absorption (IPDA) lidar is under development at NASA LaRC. This paper focuses on the advancement of the 2-micron triple-pulse IPDA lidar development. Updates on the state-of-the-art triple-pulse laser transmitter will be presented including the status of wavelength control, packaging and lidar integration. In addition, receiver development updates will also be presented, including telescope integration, detection systems and data acquisition electronics. Future plan for IPDA lidar system for ground integration, testing and flight validation will be presented.

  18. 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.

  19. Fourth Airborne Geoscience Workshop

    NASA Technical Reports Server (NTRS)

    1991-01-01

    The focus of the workshop was on how the airborne community can assist in achieving the goals of the Global Change Research Program. The many activities that employ airborne platforms and sensors were discussed: platforms and instrument development; airborne oceanography; lidar research; SAR measurements; Doppler radar; laser measurements; cloud physics; airborne experiments; airborne microwave measurements; and airborne data collection.

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

    PubMed Central

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

    2016-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  2. Surrogate gas prediction model as a proxy for Δ(14)C-based measurements of fossil fuel-CO2.

    PubMed

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

    2016-06-27

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

  3. Synthesis of (2-mercaptoacetyl)-L-[2-(14) C]tryptophan as a selective metallo-β-lactamase inhibitor via [2-(14) C]indole based on chiral pool strategy.

    PubMed

    Shirvani, Gholamhossein; Shockravi, Abbas; Amini, Mohsen; Saemian, Nader

    2017-02-01

    Metallo-beta-lactamase enzymes make bacteria resistant to a broad range of commonly used beta-lactam antibiotics. Several thiol derivatives of L-amino acids have been shown their inhibitory effects against the metallo-β-lactamase IMP-1. In this study, (2-mercaptoacetyl)-L-tryptophan as a new inhibitor of metallo-β-lactamases labeled with carbon-14 in the 2-position of the indole ring was prepared from [2-(14) C]indole as a key synthetic intermediate based on chiral pool strategy. The overall synthesis was performed in 10 steps with the overall radiochemical yield 3.6% on the basis of the barium [(14) C]carbonate as a starting material.

  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. Process-oriented dose assessment model for 14C due to releases during normal operation of a nuclear power plant.

    PubMed

    Aquilonius, Karin; Hallberg, Bengt

    2005-01-01

    Swedish nuclear utility companies are required to assess doses due to releases of radionuclides during normal operation. In 2001, calculation methods used earlier were updated due to new authority regulations. The isotope (14)C is of special interest in dose assessments due to the role of carbon in the metabolism of all life forms. Earlier, factors expressing the ratio between concentration of (14)C in air and in various plants were used. In order to extend the possibility to take local conditions into account, a process-oriented assessment model for uptake of carbon and doses from releases of (14)C to air was developed (POM(14)C). The model uses part of DAISY which has been developed to model the turnover of carbon in crops. [Hansen, S., Jensen, H.E., Nielsen, N.E., Svendsen, H., 1993. Description of the Soil Plant System Model DAISY, Basic Principles and Modelling Approach. Simulation Model for Transformation and Transport of Energy and Matter in the Soil Plant Atmosphere System. Jordbruksförlaget, The Royal Veterinary and Agricultural University, Copenhagen, Denmark]. The main objectives were to test model performance of the former method, and to investigate if taking site specific parameters into account to a greater degree would lead to major differences in the results. Several exposure pathways were considered: direct consumption of locally grown cereals, vegetables, and root vegetables, as well as consumption of milk and meat from cows having eaten fodder cereals and green fodder from the area around the nuclear plant. The total dose of the earlier model was compared with that of POM(14)C. The result of the former was shown to be slightly higher than the latter, but POM(14)C confirmed that the earlier results were of a reasonable magnitude. When full account of local conditions was taken, e.g. as regards solar radiation, temperature, and concentration of (14)C in air at various places in the surroundings of each nuclear plant, a difference in dose between

  6. Conceptual approaches for the development of dynamic specific activity models of 14C transfer from surface water to humans.

    PubMed

    Sheppard, S C; Ciffroy, P; Siclet, F; Damois, C; Sheppard, M I; Stephenson, M

    2006-01-01

    Carbon-14 is a particularly interesting radionuclide from the perspective of dose estimation. Many nuclear facilities, including power reactors, release 14C into the environment, and much of this is as 14CO2. This mixes readily with stable CO2, and hence enters the food chain as fundamental biomolecules. This isotopic mixing is often used as the basis for dose assessment models. The present model was developed for the situation of 14C releases to surface waters, where there are distinct changes in the water 14C activity concentrations throughout the year. Complete isotopic mixing (equilibrium) cannot be assumed. The model computes the specific activity (activity of 14C per mass of total C) in water, phytoplankton, fish, crops, meat, milk and air, following a typical irrigation-based food-chain scenario. For most of the biotic compartments, the specific activity is a function of the specific activity in the previous time step, the specific activity of the substrate media, and the C turnover rate in the tissue. The turnover rate is taken to include biochemical turnover, growth dilution and mortality, recognizing that it is turnover of C in the population, not a tissue or an individual, that is relevant. Attention is paid to the incorporation of 14C into the surface water biota and the loss of any remaining 14CO2 from the surface water-air interface under its own activity concentration gradient. For certain pathways, variants in the conceptual model are presented, in order to fully discuss the possibilities. As an example, a new model of the soil-to-plant specific activity relationship is proposed, where the degassing of both 14C and stable C from the soil is considered. Selection of parameter values to represent the turnover rates as modeled is important, and is dealt with in a companion paper.

  7. Human Vitamin B12 Absorption and Metabolism are Measured by Accelerator Mass Spectrometry Using Specifically Labeled 14C-Cobalamin

    SciTech Connect

    Carkeet, C; Dueker, S R; Lango, J; Buchholz, B A; Miller, J W; Green, R; Hammock, B D; Roth, J R; Anderson, P J

    2006-01-26

    There is need for an improved test of human ability to assimilate dietary vitamin B{sub 12}. Assaying and understanding absorption and uptake of B{sub 12} is important because defects can lead to hematological and neurological complications. Accelerator mass spectrometry (AMS) is uniquely suited for assessing absorption and kinetics of {sup 14}C-labeled substances after oral ingestion because it is more sensitive than decay counting and can measure levels of carbon-14 ({sup 14}C) in microliter volumes of biological samples, with negligible exposure of subjects to radioactivity. The test we describe employs amounts of B{sub 12} in the range of normal dietary intake. The B{sub 12} used was quantitatively labeled with {sup 14}C at one particular atom of the DMB moiety by exploiting idiosyncrasies of Salmonellametabolism. In order to grow aerobically on ethanolamine, S. entericamust be provided with either pre-formed B{sub 12} or two of its precursors: cobinamide and dimethylbenzimidazole (DMB). When provided with {sup 14}C-DMB specifically labeled in the C2 position, cells produced {sup 14}C-B{sub 12} of high specific activity (2.1 GBq/mmol, 58 mCi/mmol) and no detectable dilution of label from endogenous DMB synthesis. In a human kinetic study, a physiological dose (1.5 mg, 2.2 KBq/59 nCi) of purified {sup 14}C-B{sub 12} was administered and showed plasma appearance and clearance curves consistent with the predicted behavior of the pure vitamin. This method opens new avenues for study of B{sub 12} assimilation.

  8. A new metabolically trapped agent by brain monoamine oxidase: N-methyl labeled (14C) N-methylphenylethylamine (14C-MPEA).

    PubMed

    Osamu, I

    1983-01-01

    A new type of metabolically trapped agent for measuring regional brain function was designed and evaluated. N-methylphenylethylamine (14C-MPEA) was synthesized with trifluoroacetylphenylethylamine and 14C-methyl iodide. A high concentration of 14C-MPEA accumulated in mouse brain 1 min after injection, and radioactivities in the brain remained for a long period. By radiochemical analysis, it was found 14C-MPEA was metabolized in the brain to 14C-methylamine. 14C-methylamine was trapped by the blood-brain barrier because of its cationic charge at physiological pH. When the mouse was pretreated with a MAO inhibitor (pargyline hydrochloride 100 mg/kg IP) the radioactivity was rapidly excreted from the brain with a half-life of about 45 min. These results indicate that 11C-MPEA has potential for the measurement of brain MAO activity.

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

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

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

  10. 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.

  11. 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.

  12. Highly Sensitive 14C and 3H Quantification of Biochemical Samples Using Accelerator Mass Spectrometry

    SciTech Connect

    Ognibene, T J; Vogel, J S

    2003-10-23

    Accelerator Mass Spectrometry (AMS) is an isotope ratio mass spectrometer that quantifies low levels of rare isotopes with half-lives between 10 and 10{sup 8} years. Typical sensitivities are 10{sup 6} atoms in a milligram-sized sample. AMS was originally developed for use in the geosciences as a tool to carbon date archaeological artifacts, but has applications in many fields. In the biosciences, the extreme sensitivity of AMS is used to trace nutrients, toxins and therapeutics in humans and animals using less than {micro}g/kg doses containing between 1-100 nCi of {sup 14}C. This sensitivity is used to reduce sample size, reduce chemical exposures to environmental or physiological levels, reduce radiation exposures to subjects, and/or reduce radioactive (and ''mixed'') waste. Compared to decay counting, AMS provides for a much higher measurement throughput for low activity samples. For example, a milligram-sized sample containing 1 dpm of {sup 14}C can be measured to 3% precision in several seconds. That same sample would require approximately 1 week of decay counting to obtain similar precision.

  13. Factors affecting the uptake of 14C-labeled organic chemicals by plants from soil

    SciTech Connect

    Topp, E.; Scheunert, I.; Attar, A.; Korte, F.

    1986-04-01

    The uptake of /sup 14/C from various /sup 14/C-labeled organic chemicals from different chemical classes by barley and cress seedlings from soil was studied for 7 days in a closed aerated laboratory apparatus. Uptake by roots and by leaves via the air was determined separately. Although comparative long-term outdoor studies showed that an equilibrium is not reached within a short time period, plant concentration factors after 7 days could be correlated to some physicochemical and structural substance properties. Barley root concentration factors due to root uptake, expressed as concentration in roots divided by concentration in soil, gave a fairly good negative correlation to adsorption coefficients based on soil organic carbon. Barley root concentration factors, expressed as concentration in roots divided by concentration in soil liquid, gave a positive correlation to the n-octanol/water partition coefficients. Uptake of chemicals by barley leaves via air was strongly positively correlated to volatilization of chemicals from soil. Both root and foliar uptake by barley could be correlated well to the molecular weight of 14 chemicals. Uptake of chemicals by cress differed from that by barley, and correlations to physicochemical substance properties mostly were poor.

  14. Photoperiodic control of soybean /sup 14/C-assimilate partitioning during the seed filling period

    SciTech Connect

    Morandi, E.N.

    1986-04-01

    Photoperiod not only controls the timing of flowering, but also affects later stages of seed development. To study its effect on assimilate partitioning, soybean plants were kept in short days (SD) or night interrupted (NI) during seed filling. The source-sink ratio was fixed to one leaflet-one pod per node. The node was girdle-isolated and its leaflet was pulse labelled with /sup 14/CO/sub 2/. SD plants partitioned more /sup 14/C into seeds, while NI plants showed higher proportions in the petiole, stem and carpel. Seed growth rate and final seed dry weight were increased by 40% in SD. The sugar/starch ratio was increased in cotyledons and decreased in leaves of SD plants. In contrast, NI plants showed more /sup 14/C incorporation into proteins. No changes were detected in carbon exchange ratio, dark respiration and total node dry weight. Thus, photoperiodic induced changes in carbohydrate and protein partitioning occurred without changes in the overall assimilatory process.

  15. Tracing bomb /sup 14/C in the atmosphere 1962--1980

    SciTech Connect

    Nydal, R.; Loevseth, K.

    1983-04-20

    When the ever greater series of nuclear tests were exposed to the atmosphere at higher northern latitudes during 1961 and 1962, an attempt was made at this laboratory to trace the distribution of bomb-produced /sup 14/C down to lower latitudes and into the ocean surface. Several ground level stations were established for this purpose in the early 1960's, from Spitsbergen (78 /sup 0/N) to Madagascar (21 /sup 0/S). Measurements were also gradually extended to the ocean surface. The tropospheric measurements which partly have been performed during the last 18 years have proved to be important for testing exchange models for industrial CO/sub 2/ in the atmosphere and more generally for studying the carbon cycle in nature. The present paper includes tables of all the atmospheric /sup 14/C data measured at this laboratory during 18 years. Several graphs are also included and a description of sampling locations and contamination problems. The paper is an answer to those who want to use the data in their own modeling research.

  16. Airborne Particles.

    ERIC Educational Resources Information Center

    Ojala, Carl F.; Ojala, Eric J.

    1987-01-01

    Describes an activity in which students collect airborne particles using a common vacuum cleaner. Suggests ways for the students to convert their data into information related to air pollution and human health. Urges consideration of weather patterns when analyzing the results of the investigation. (TW)

  17. Airborne Imagery

    NASA Technical Reports Server (NTRS)

    1983-01-01

    ATM (Airborne Thematic Mapper) was developed for NSTL (National Space Technology Companies) by Daedalus Company. It offers expanded capabilities for timely, accurate and cost effective identification of areas with prospecting potential. A related system is TIMS, Thermal Infrared Multispectral Scanner. Originating from Landsat 4, it is also used for agricultural studies, etc.

  18. 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.

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

    SciTech Connect

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

    1985-01-01

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

  20. 14C-NaVP and 14C-PEV repeated dose study in rat. Pharmacokinetic study in rats after repeated oral administrations of 14C-valproic acid sodium salt and 14C-valproic acid pivaloyl oxymethyl ester.

    PubMed

    Bertolino, M; Acerbi, D; Canali, S; Giachetti, C; Poli, G; Ventura, P; Zanolo, G

    1998-01-01

    The absorption, excretion and tissue distribution of radioactivity after repeated oral equimolar doses of 14C-valproic acid sodium salt (NaVP) or 14C-valproic acid pivaloyl oxymethyl ester (PEV) was investigated in male rats treated once a day for 14 consecutive days. The 14th day plasma time-course of radioactivity after PEV administrations was characterised by a slow absorption rate with a delayed peak (tmax 2 h, Cmax 7.52 +/- 1.35 microg eq./ml), followed by a plateau lasting up to 8 h. After NaVP treatment, the main peak of radioactivity was observed 0.5 h after administration (Cmax 8.30 +/- 1.26 microg eq./ml) followed by a secondary peak due to biliary enterohepatic recycling. Starting from 4 h onwards, radioactivity levels after PEV treatment were higher than those after NaVP (AUCtau = 113.3 h.microg eq./ml after PEV vs 71.9 h.microg eq./ml after NaVP), but concentrations declined with similar terminal half-lives (52.8 h for PEV and 49.7 h for NaVP). Radioactivity recovered (0-432 h interval) in urine accounted for 79.3% (PEV) and 56.1% (NaVP) while, in faeces accounted for 9.1% (PEV) and 26.1% (NaVP) of total administered dose (14 days). The difference is attributable to a higher excretion of radioactivity in the bile for NaVP. The missing fraction in the total radioactivity balance is probably excreted in expired air, as observed in single dose studies. Radioactivity excreted in bile (0-8 h interval of the last 14th day) accounted for 5.1% (NaVP) and 0.23% (PEV) of the total administered dose (14 days). A possible explanation of this difference may be a different metabolism pattern for the two compounds. The negligible biliary excretion observed after PEV administration is probably due to an inhibition of the glucuronation of valproic acid (or other metabolites) caused by the pivalic acid. Due to the presence of the enterohepatic recycle, the radioactivity levels in intestine, 0.5 and 2 h after administration, were higher after NaVP administration

  1. MEASUREMENTS OF PAST 14C LEVELS AND 13C/12C RATIOS IN THE SURFACE WATERS OF THE WORLD'S SUBPOLAR OCEANS.

    SciTech Connect

    Brown, T A

    2010-04-22

    Under this project we have developed methods that allow the reconstruction of past {sup 14}C levels of the surface waters of the subpolar North Pacific Ocean by measuring the {sup 14}C contents of archived salmon scales. The overall goal of this research was to reduce of the uncertainty in the uptake of fossil CO{sub 2} by the oceans and thereby improve the quantification of the global carbon cycle and to elucidate the fate of anthropogenic CO{sub 2}. Ocean General Circulation Models (OGCMs), with their three dimensional global spatial coverage and temporal modeling capabilities, provide the best route to accurately calculating the total uptake of CO{sub 2} by the oceans and, hence, to achieving the desired reduction in uncertainty. {sup 14}C has played, and continues to play, a central role in the validation of the OGCMs calculations, particularly with respect to those model components which govern the uptake of CO{sub 2} from the atmosphere and the transport of this carbon within the oceans. Under this project, we have developed time-series records of the {sup 14}C levels of the surface waters of three areas of the subpolar North Pacific Ocean. As the previously available data on the time-history of oceanic surface water {sup 14}C levels are very limited, these time-series records provide significant new {sup 14}C data to constrain and validate the OGCMs.

  2. Simultaneous and Independent Measurement of Atmospheric Water Vapor and Carbon Dioxide using a Triple-Pulsed, 2-micron Airborne IPDA Lidar - A Feasibility Study

    NASA Astrophysics Data System (ADS)

    Singh, U. N.; Refaat, T. F.; Yu, J.; Petros, M.

    2013-12-01

    Water vapor (H2O) and carbon dioxide (CO2) are dominant greenhouse gases that are critical for Earth's radiation budget and global warming through the eco-system and the carbon cycle. NASA Langley Research Center (LaRC) has a strong heritage in atmospheric remote sensing of both gases using several instruments adopting various DIAL techniques. This communication presents a feasibility study for measuring both H2O and CO2 simultaneously and independently using a single instrument. This instrument utilizes the Integrated Path Differential Absorption (IPDA) lidar technique to measure the weighted-average column dry-air mixing ratios of CO2 (XCO2) and H2O (XH2O) independently and simultaneously from an airborne platform. The key component of this instrument is a tunable triple-pulse 2-micron laser. The three laser pulses are transmitted sequentially within a short time interval of 200 microsec. The wavelength of each of the laser pulses can be tuned separately. The IPDA receiver design is based on low-risk, commercially available components, including 300-micron diameter InGaAs 2-micron pin detector, a low-noise, high speed trans-impedance amplifier (TIA) and 12-bit 400 MHz digitizer.

  3. 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...

  4. Metabolism of [(1)(4)C]prometryn in rats.

    PubMed

    Maynard, M S; Brumback, D; Itterly, W; Capps, T; Rose, R

    1999-09-01

    [(1)(4)C]Prometryn, 2, 4-bis(isopropylamino)-6-(methylthio)-s-triazine, was orally administered to male and female rats at approximately 0.5 and 500 mg/kg; daily urine and feces were collected. After 3 or 7 days rats were sacrificed, and blood and selected tissues were isolated. The urine and feces extracts were characterized for metabolite similarity as well as for metabolite identification. Over 30 metabolites were observed, and of these, 28 were identified mostly by mass spectrometry and/or cochromatography with available reference standards. The metabolism of prometryn was shown to occur by N-demethylation, S-oxidation, S-S dimerization, OH substitution for NH(2) and SCH(3), and conjugation with glutathione or glucuronic acid. Rat liver microsomal incubations of prometryn were conducted and compared to the in vivo metabolism. Both in vivo and in vitro phase I metabolisms of prometryn were similar, with S-oxidation and N-dealkylation predominating. The involvement of cytochrome P-450 and flavin-containing monooxidase in the in vitro metabolism of prometryn was investigated.

  5. Bioaccumulation of 51Cr, 63Ni and 14C in Baltic Sea benthos.

    PubMed

    Kumblad, L; Bradshaw, C; Gilek, M

    2005-03-01

    The Baltic Sea is a species-poor, semi-enclosed, brackish sea, whose sediments contain a wide range of contaminants, including sediment-associated metals and radionuclides. In this study, we have examined and compared bioaccumulation kinetics and assimilation efficiencies of sediment-associated (51)Cr, (63)Ni and (14)C in three key benthic invertebrates (the deposit-feeding Monoporeia affinis, the facultative deposit-feeding Macoma baltica, and the omnivorous Halicryptus spinulosus). Our results demonstrate that (i) all radionuclides were accumulated, (ii) the different radionuclides were accumulated to various extents, (iii) small changes in organic carbon concentration can influence the accumulation, and (iv) the degree of accumulation differed only slightly between species. These processes, together with sediment resuspension and bioturbation, may remobilise trace metals from the sediment to the water and to higher trophic levels, and therefore should be taken into account in exposure models and ERAs.

  6. 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

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    As is shown in the IPCC (Intergovernmental Panel on Climate Change) report, the observed climate changes are caused, among others, by human activity. Mainly emission of CO2 to the atmosphere coming from the burning of fossil fuels, can have dire consequences for life on Earth and development of humankind. The report uses, among others, data obtained from isotopic measurements in the biosphere. Measurements of 14C and 13C concentration in modern atmospheric carbon dioxide and biosphere allow the determination of the decrease of the concentration of this isotope. Furthermore, the magnitude of emission to the atmosphere of carbon dioxide not containing the isotope 14C can be estimated on this basis. Such emission stems from fossil fuel combustion - petroleum, natural gas and black coal. A sensitive bioindicator of the emission are annual tree rings. The measurements of 14C concentration in tree ring material using AMS allow to see its seasonal changes. Trees, treated as an archive of changes in conjunction with information about the isotopic composition of carbon can be used for monitoring of environment as sensitive bioindicators on local, as well as on the global scale. Regular investigations of isotopic composition of carbon in trees have been carried out in the GADAM Centre for the urban areas of both Poland and worldwide. This method can be applied in the study of the emission of CO2 to the atmosphere and its spatial and temporal distribution connected with the production of energy by power plants based on fossil fuel combustion for the area of southern Poland. Modelling of CO2 emission using both 14C and 13C carbon isotopes measured in pine tree rings on the background of climatic changes will be presented. The national ecological policy in the era of global warming requires the manufacturers of energy to get involved in the development of methods suitable for monitoring the state of the environment. Hence, the interest in the area of monitoring the fossil fuel

  8. 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.

  9. COCA: deriving urban emissions and the carbon exchange of a forested region using airborne CO2 and CO observations

    NASA Astrophysics Data System (ADS)

    Geiss, H.; Schmitgen, S.; Ciais, P.; Neininger, B.; Baeumle, M.; Brunet, Y.; Kley, D.

    2002-05-01

    A crucial challenge in measuring the partitioning of sources and sinks of atmospheric CO2 is the separation of regional anthropogenic CO2 sources from biogenic activity. The aim of the COCA project is to quantify the fossil fuel and biogenic CO2 fractions using continuous airborne CO2 and CO measurements, where CO acts as a tracer for anthropogenic CO2. At first part of the project COCA an attempt was made to measure daytime biogenic CO2 fluxes over a forest area (about 15 by 30 km size). The campaign took place around the CARBOEUROFLUX site ``Le Bray'' (Pinus pinaster) close to Bordeaux in France end of June 2001 Based on continuous airborne CO2, H2O and CO flux and concentration measurements a Lagrangian budgeting approach was chosen to measure regional CO2 deposition fluxes. The objective is to determine the CO2 uptake of the extended forest area from the CO2/CO gradients up- and downwind of the ecosystem, using CO as air mass tracer and such estimating the influence of anthropogenic CO2 advected into the area First results of the summer flight on June 23rd will be shown, where fair wind speeds (~5 m/s) and a low CBL height led to the observation of a clear decrease in CO2 at the downwind flight stacks with basically constant CO concentrations. For other summer flights with very low wind speeds, local effects dominate the observations leading to a larger variability in the observations. Both, correlations and anti-correlations of CO2 with the anthropogenic tracer CO have been observed. Positive correlations indicate fresh plumes of anthropogenic CO2. Negative correlations are indicative of entrainment of free tropospheric air, that was marked by relatively higher CO2 and lower CO concentrations than the average CBL concentrations. During a second campaign the variance of anthropogenic CO and CO2 emissions of a large city unaffected by biogenic processes has been studied. This campaign was carried out on February 16 and 17, 2002 over the Paris metropolitan area

  10. Quantifying biomass consumption and carbon release from the California Rim fire by integrating airborne LiDAR and Landsat OLI data

    PubMed Central

    Saatchi, Sassan; Casas, Angeles; Koltunov, Alexander; Ustin, Susan; Ramirez, Carlos; Garcia‐Gutierrez, Jorge; Balzter, Heiko

    2017-01-01

    Abstract Quantifying biomass consumption and carbon release is critical to understanding the role of fires in the carbon cycle and air quality. We present a methodology to estimate the biomass consumed and the carbon released by the California Rim fire by integrating postfire airborne LiDAR and multitemporal Landsat Operational Land Imager (OLI) imagery. First, a support vector regression (SVR) model was trained to estimate the aboveground biomass (AGB) from LiDAR‐derived metrics over the unburned area. The selected model estimated AGB with an R 2 of 0.82 and RMSE of 59.98 Mg/ha. Second, LiDAR‐based biomass estimates were extrapolated to the entire area before and after the fire, using Landsat OLI reflectance bands, Normalized Difference Infrared Index, and the elevation derived from LiDAR data. The extrapolation was performed using SVR models that resulted in R 2 of 0.73 and 0.79 and RMSE of 87.18 (Mg/ha) and 75.43 (Mg/ha) for the postfire and prefire images, respectively. After removing bias from the AGB extrapolations using a linear relationship between estimated and observed values, we estimated the biomass consumption from postfire LiDAR and prefire Landsat maps to be 6.58 ± 0.03 Tg (1012 g), which translate into 12.06 ± 0.06 Tg CO2e released to the atmosphere, equivalent to the annual emissions of 2.57 million cars.

  11. (14C)deoxyglucose uptake and imaging in malignant melanoma

    SciTech Connect

    Kern, K.A. )

    1991-06-01

    Since malignant tumors utilize more glucose than normal tissues, tumor uptake and autoradiographic imaging studies using the 14C-labeled glucose analog 2-deoxyglucose (DG) provide a useful preclinical system to determine if similar human tumors will image in vivo with positron emission tomography (PET) using 18F-labeled DG (FDG-PET). We studied B16 murine melanomas of increasing metastatic potential (F1, low; BL-6, intermediate; F10, high) as a feasibility study to determine the potential for human melanoma imaging using FDG-PET. Male C57BL-6 mice (50 g) were implanted sc with 1-mm3 fragments of B16 melanomas. Fourteen days later mice were injected ip with 1.25 muCi of {sup 14}CDG. Sixty minutes later tumor (T) and gastrocnemius muscle (M) were harvested, solubilized, and counted for {sup 14}CDG dpm/mg to estimate glucose utilization. Autoradiographic imaging was carried out similarly, using 2.0 muCi or {sup 14}CDG with 30-day exposure of T and M tissue sections (20 microns thick) to x-ray film. The uptake of {sup 14}CDG (expressed as dpm/mg; % injected dose/g; and tumor-to-muscle uptake ratios) was 6 to 10 times higher in tumors than in muscle tissue (P less than 0.001). All three melanoma cell lines imaged successfully with {sup 14}CDG autoradiography. Tumor uptake of {sup 14}CDG did not correlate with increasing metastatic potential. The experimental B16 murine melanomas F1, BL-6, and F10 extract glucose at higher rates than muscle tissue, a property necessary for successful PET imaging of cutaneous melanoma. The lack of correlation between glucose extraction and metastatic potential suggests that the demands for glucose during tumor growth and metastasis are not related. This is the first laboratory study to predict that human malignant melanoma will image with FDG-PET.

  12. Partitioning of Soil Respiration Sources Using 14C-Enriched Leaf Litter and Roots in a Temperate Forest, Oak Ridge, TN

    NASA Astrophysics Data System (ADS)

    Cisneros Dozal, L.; Trumbore, S.; Hanson, P.; Xu, X.

    2002-12-01

    Leaf litter enriched in 14C with values ranging from +952‰ to +1055 ‰ and control leaf litter with Δ14C of +215 ‰ to +230 ‰ were used to establish replicated plots on the Oak Ridge Reservation (ORR), Oak Ridge National Laboratory, Tennessee for tracking of soil carbon cycling. Our goal is to partition the heterotrophic and autotrophic components of total CO2 emission from the soil. Measurements have been carried out in the summer of 2001 and 2002 at two sites (Walker Branch and TVA) that are on the same soil type, but that have different initial levels of 14C resulting from a localized ecosystem-scale 14C release event in 1999. Measurements include total soil respiration rates using a chamber technique, trapping of CO2 evolved from chambers and from root respiration to determine 14C and 13C signatures, and incubations of soil and leaf litter in the laboratory to obtain rates of decomposition and 14C and 13C signatures from heterotrophic CO2 sources. Total C fluxes (mg C/m2-hr) varied among the sites by up to ~40%, with differences between enriched and control plots similar to site-to-site variation between TVA and Walker Branch. In May of 2002, the 14C signature of the total CO2 emitted from the enriched plots was always higher than that of the control plots in both sites, with averaged values of Δ14C of +493 ‰ and +357 ‰ in TVA and of +300 ‰ and +156 ‰ in Walker Branch, for the enriched and control plots respectively. We use the mass balance equation, Δ14Ctotal=FxΔ14C{leaf litter}+(1-F)x(Δ14C{root and soil decomposition} +Δ14C{roots respiration}) to estimate the contribution of leaf litter decomposition to the total CO2 flux (F). Within any one site, the difference in the 14C signature emitted from the soil between the two treatments should be directly proportional to the contribution of leaf litter decomposition only, since the other components (roots and soil decomposition and roots respiration) are assumed to remain the same for enriched

  13. CO2 increases 14C-primary production in an Arctic plankton community

    NASA Astrophysics Data System (ADS)

    Engel, A.; Borchard, C.; Piontek, J.; Schulz, K.; Riebesell, U.; Bellerby, R.

    2012-08-01

    Responses to ocean acidification in plankton communities were studied during a CO2-enrichment experiment in the Arctic Ocean, accomplished from June to July 2010 in Kongsfjorden, Svalbard (78°56, 2' N, 11°53, 6' E). Enclosed in 9 mesocosms (volume: 43.9-47.6 m3), plankton was exposed to CO2 concentrations, ranging from glacial to projected mid-next-century levels. Fertilization with inorganic nutrients at day 13 of the experiment supported the accumulation of phytoplankton biomass, as indicated by two periods of high Chl a concentration. This study tested for CO2 sensitivities in primary production (PP) of particulate organic carbon (PPPOC) and of dissolved organic carbon (PPDOC). Therefore, 14C-bottle incubations (24 h) of mesocosm samples were performed at 1 m depth receiving about 60% of incoming radiation. PP for all mesocosms averaged 8.06 ± 3.64 μmol C l-1 d-1 and was slightly higher than in the outside fjord system. Comparison between mesocosms revealed significantly higher PPPOC at elevated compared to low pCO2 after nutrient addition. PPDOC was significantly higher in CO2 enriched mesocosms before as well as after nutrient addition, suggesting that CO2 had a direct influence on DOC production. DOC concentrations inside the mesocosms increased before nutrient addition and more in high CO2 mesocosms. After addition of nutrients, however, further DOC accumulation was negligible and not significantly different between treatments, indicating rapid utilization of freshly produced DOC. Bacterial biomass production (BP) was coupled to PP in all treatments, indicating that 3.5 ± 1.9% of PP, or 21.6 ± 12.5% of PPDOC provided sufficient carbon for synthesis of bacterial biomass. The response of 14C-based PP rates to CO2 enrichment was at odds with O2-based net community production (NCP) rates that were also determined during this study, albeit at lower light level. We conclude that the enhanced release of labile DOC during autotrophic production at high CO2

  14. CO2 increases 14C primary production in an Arctic plankton community

    NASA Astrophysics Data System (ADS)

    Engel, A.; Borchard, C.; Piontek, J.; Schulz, K. G.; Riebesell, U.; Bellerby, R.

    2013-03-01

    Responses to ocean acidification in plankton communities were studied during a CO2-enrichment experiment in the Arctic Ocean, accomplished from June to July 2010 in Kongsfjorden, Svalbard (78°56' 2'' N, 11°53' 6'' E). Enclosed in 9 mesocosms (volume: 43.9-47.6 m3), plankton was exposed to CO2 concentrations, ranging from glacial to projected mid-next-century levels. Fertilization with inorganic nutrients at day 13 of the experiment supported the accumulation of phytoplankton biomass, as indicated by two periods of high chl a concentration. This study tested for CO2 sensitivities in primary production (PP) of particulate organic carbon (PPPOC) and of dissolved organic carbon (PPDOC). Therefore, 14C-bottle incubations (24 h) of mesocosm samples were performed at 1 m depth receiving about 60% of incoming radiation. PP for all mesocosms averaged 8.06 ± 3.64 μmol C L-1 d-1 and was slightly higher than in the outside fjord system. Comparison between mesocosms revealed significantly higher PPPOC at elevated compared to low pCO2 after nutrient addition. PPDOC was significantly higher in CO2-enriched mesocosms before as well as after nutrient addition, suggesting that CO2 had a direct influence on DOC production. DOC concentrations inside the mesocosms increased before nutrient addition and more in high CO2 mesocosms. After addition of nutrients, however, further DOC accumulation was negligible and not significantly different between treatments, indicating rapid utilization of freshly produced DOC. Bacterial biomass production (BP) was coupled to PP in all treatments, indicating that 3.5 ± 1.9% of PP or 21.6 ± 12.5% of PPDOC provided on average sufficient carbon for synthesis of bacterial biomass. During the later course of the bloom, the response of 14C-based PP rates to CO2 enrichment differed from net community production (NCP) rates that were also determined during this mesocosm campaign. We conclude that the enhanced release of labile DOC during autotrophic

  15. In vivo distribution of organophosphate antidotes: autoradiography of (/sup 14/C)HI-6 in the rat

    SciTech Connect

    Ligtenstein, D.A.; Moes, G.W.; Kossen, S.P.

    1988-02-01

    In order to visualize the distribution of HI-6 in the rat after iv administration, autoradiographic experiments were carried out with (/sup 14/C)HI-6, labeled at the carbon of the carboxamide moiety. Autoradiography clearly confirms penetration of HI-6 into the central nervous system. Considerable radioactivity was found in the cerebrum, the cerebellum, and the choroid plexus. No significant activity was detected in the pontomedullary region or the spinal cord. Peripherally, (/sup 14/C)HI-6 is observed in large amounts in kidneys, heart, liver, nose, bladder, testes, and marrow-containing bone. The gastrointestinal tract was largely devoid of any radioactivity. The relative absence of HI-6 in the pontomedullary region renders centrally mediated influences of HI-6 on hemodynamic and respiratory parameters less likely.

  16. Translocation of Indole-3-acetic Acid-1′-14C and Tryptophan-1-14C in Seedlings of Phaseolus coccineus L. and Zea mays L. 1

    PubMed Central

    Whitehouse, R. L.; Zalik, Saul

    1967-01-01

    Indole-3-acetic acid-1′-14C (IAA-14C) and tryptophan-1-14C injected in small amounts into cotyledons of Phaseolus coccineus L. seedlings were found to be translocated acropetally into the epicotyls and young shoots. Similarly IAA-14C was translocated acropetally into coleoptiles of Zea mays following injection into the endosperms. Labeled metabolites of the injected compounds were also extractable from shoot tissue. However, evidence that IAA-14C itself was translocated acropetally was obtained by collection in agar blocks applied to cut surfaces of coleoptiles of injected seedlings. The acropetal translocation in Phaseolus was shown not to occur in the transpiration stream but in living tissue. Cotyledons of Phaseolus coccineus and Phaseolus vulgaris contain extensive vascular tissue. Tryptophan-14C was not actively translocated through excised segments of Phaseolus coccineus epicotyl and Zea mays coleoptile when supplied from donor agar blocks in concentrations as high as 100 μm. The small amount of tryptophan-14C which did reach receiver blocks when high concentrations were used may be accounted for by passive diffusion through the fluid-filled xylem vessels. Translocation of a non-toxic dye, Light Green SF Yellowish, through xylem vessels was found to occur when supplied from donor blocks placed acropetally or basipetally. Metabolism of the supplied tryptophan-14C by the tissue segments was shown to occur during the 3 to 6 hour translocation experiments. IAA-14C was transported in a strictly basipetal manner in both tissues. Only 1 labeled compound with an RF value of IAA was found in receiver blocks. Composition of a simple green safelight suitable for work in plant physiology is described. Images PMID:16656664

  17. Synthesis of enantiomerically pure [(14) C]-labelled morpholine derivatives for a class of trace amine-associate receptor 1 agonists.

    PubMed

    Edelmann, Martin R; Hartung, Thomas; Trussardi, René; Iding, Hans; Galley, Guido; Pflieger, Philippe; Norcross, Roger D

    2016-12-01

    Various agonists of the trace amine-associate receptor 1, under consideration as potential clinical development candidates, were labelled with carbon-14 for use in preclinical in vitro and in vivo drug metabolism studies. Herein, the [(14) C]-radiosynthesis of 2-phenyl-substituted morpholines 1 is described. After evaluating and optimizing different synthetic routes, 4-iodonitrobenzene 3 was selected as starting material for the 14-step synthesis. Incorporation of carbon-14 into the acetyl moiety allowed a safe and efficient synthesis of [(14) C]-labelled 4-nitroacetophenone 2 in five steps and 38% yield. Further transformation of 2 to the target compounds 1 was achieved in a 9-step synthesis. In a representative example, [(14) C]-labelled 1 was obtained in an overall yield of 11% and was isolated in >99% radiochemical purity and a specific activity of 47 mCi/mmol.

  18. 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 (

  19. The effect of composition on stability ((14)C activity) of soil organic matter fractions from the albic and black soils.

    PubMed

    Jin, Jie; Sun, Ke; Wang, Ziying; Han, Lanfang; Wu, Fengchang; Xing, Baoshan

    2016-01-15

    The importance of the composition of soil organic matter (SOM) for carbon (C) cycling is still under debate. Here a single soil source was used to examine the specific influence of its composition on stability ((14)C activity) of SOM fractions while constraining other influential C turnover factors such as mineral, climate and plant input. The following SOM fractions were isolated from two soil samples: four humic acids, two humins, non-hydrolyzable carbon, and the demineralized fraction. We examined the isotope ratios of SOM fractions in relation to composition (such as aliphatic and aromatic C content) using solid state (13)C nuclear magnetic resonance (NMR) and thermal analysis. The Δ(14)C values of the fractions isolated from both an albic soil (SOMs-A) and a black soil (SOMs-B) correlated negatively with their peak temperature of decomposition and the temperature where half of the total heat of reaction was evolved, implying a potential link between thermal and biogeochemical stability of SOM fractions. Aryl C contents of SOMs-A determined using (13)C NMR varied inversely with δ(15)N values and directly with δ(13)C values, suggesting that part of aryl C of SOMs-A might be fire-derived. The Δ(14)C values of SOMs-A correlated positively with aliphatic C content and negatively with aromatic C content. We therefore concluded that fire-derived aromatic C in SOMs-A appeared to be more stable than microbially-derived aliphatic C. The greater decomposition of SOMs-B fractions weakened the relationship of their Δ(14)C values with alkyl and aryl C contents. Hence, the role of the composition of SOM fractions in regulating stability might be dependent on the source of specific C forms and their stage of decomposition.

  20. Airborne Fiber Size Characterization in Exposure Estimation: Evaluation of a Modified Transmission Electron Microcopy Protocol for Asbestos and Potential Use for Carbon Nanotubes and Nanofibers

    PubMed Central

    Dement, John M.; Kuempel, Eileen D.; Zumwalde, Ralph D.; Ristich, Anna M.; Fernback, Joseph E.; Smith, Randall J.

    2015-01-01

    Background Airborne fiber size has been shown to be an important factor relative to adverse lung effects of asbestos and suggested in animal studies of carbon nanotubes and nanofibers (CNT/CNF). Materials and Methods The International Standards Organization (ISO) transmission electron microscopy (TEM) method for asbestos was modified to increase the statistical precision of fiber size determinations, improve efficiency, and reduce analysis costs. Comparisons of the fiber size distributions and exposure indices by laboratory and counting method were performed. Results No significant differences in size distributions by the ISO and modified ISO methods were observed. Small but statistically-significant inter-lab differences in the proportion of fibers in some size bins were found, but these differences had little impact on the summary exposure indices. The modified ISO method produced slightly more precise estimates of the long fiber fraction (>15 μm). Conclusions The modified ISO method may be useful for estimating size-specific structure exposures, including CNT/CNF, for risk assessment research. PMID:25675894

  1. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2010-04-01

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

  3. 14C autoradiography with an energy-sensitive silicon pixel detector.

    PubMed

    Esposito, M; Mettivier, G; Russo, P

    2011-04-07

    The first performance tests are presented of a carbon-14 ((14)C) beta-particle digital autoradiography system with an energy-sensitive hybrid silicon pixel detector based on the Timepix readout circuit. Timepix was developed by the Medipix2 Collaboration and it is similar to the photon-counting Medipix2 circuit, except for an added time-based synchronization logic which allows derivation of energy information from the time-over-threshold signal. This feature permits direct energy measurements in each pixel of the detector array. Timepix is bump-bonded to a 300 µm thick silicon detector with 256 × 256 pixels of 55 µm pitch. Since an energetic beta-particle could release its kinetic energy in more than one detector pixel as it slows down in the semiconductor detector, an off-line image analysis procedure was adopted in which the single-particle cluster of hit pixels is recognized; its total energy is calculated and the position of interaction on the detector surface is attributed to the centre of the charge cluster. Measurements reported are detector sensitivity, (4.11 ± 0.03) × 10(-3) cps mm(-2) kBq(-1) g, background level, (3.59 ± 0.01) × 10(-5) cps mm(-2), and minimum detectable activity, 0.0077 Bq. The spatial resolution is 76.9 µm full-width at half-maximum. These figures are compared with several digital imaging detectors for (14)C beta-particle digital autoradiography.

  4. Online coupling of pure O2 thermo-optical methods - 14C AMS for source apportionment of carbonaceous aerosols

    NASA Astrophysics Data System (ADS)

    Agrios, Konstantinos; Salazar, Gary; Zhang, Yan-Lin; Uglietti, Chiara; Battaglia, Michael; Luginbühl, Marc; Ciobanu, Viorela Gabriela; Vonwiller, Matthias; Szidat, Sönke

    2015-10-01

    This paper reports on novel separation methods developed for the direct determination of 14C in organic carbon (OC) and elemental carbon (EC), two sub-fractions of total carbon (TC) of atmospheric air particulate matter. Until recently, separation of OC and EC has been performed off-line by manual and time-consuming techniques that relied on the collection of massive CO2 fractions. We present here two on-line hyphenated techniques between a Sunset OC/EC analyzer and a MICADAS (MIni radioCArbon DAting System) accelerator mass spectrometer (AMS) equipped with a gas ion source. The first implementation facilitates the direct measurement in the low sample size range (<10 μg C) with high throughput on a routine basis, while the second explores the potential for a continuous-flow real-time CO2 gas feed into the ion source. The performance achieved with reference materials and real atmospheric samples will be discussed to draw conclusions on the improvement offered in the field of 14C aerosol source apportionment.

  5. Airborne measurements of sulfur dioxide, dimethyl sulfide, carbon disulfide, and carbonyl sulfide by isotope dilution gas chromatography/mass spectrometry

    NASA Technical Reports Server (NTRS)

    Bandy, Alan R.; Thornton, Donald C.; Driedger, Arthur R., III

    1993-01-01

    A gas chromatograph/mass spectrometer is described for determining atmospheric sulfur dioxide, carbon disulfide, dimethyl sulfide, and carbonyl sulfide from aircraft and ship platforms. Isotopically labelled variants of each analyte were used as internal standards to achieve high precision. The lower limit of detection for each species for an integration time of 3 min was 1 pptv for sulfur dioxide and dimethyl sulfide and 0.2 pptv for carbon disulfide and carbonyl sulfide. All four species were simultaneously determined with a sample frequency of one sample per 6 min or greater. When only one or two species were determined, a frequency of one sample per 4 min was achieved. Because a calibration is included in each sample, no separate calibration sequence was needed. Instrument warmup was only a few minutes. The instrument was very robust in field deployments, requiring little maintenance.

  6. Regional prediction of soil organic carbon content over temperate croplands using visible near-infrared airborne hyperspectral imagery and synchronous field spectra

    NASA Astrophysics Data System (ADS)

    Vaudour, E.; Gilliot, J. M.; Bel, L.; Lefevre, J.; Chehdi, K.

    2016-07-01

    This study aimed at identifying the potential of Vis-NIR airborne hyperspectral AISA-Eagle data for predicting the topsoil organic carbon (SOC) content of bare cultivated soils over a large peri-urban area (221 km2) with both contrasted soils and SOC contents, located in the western region of Paris, France. Soil types comprised haplic luvisols, calcaric cambisols and colluvic cambisols. Airborne AISA-Eagle data (400-1000 nm, 126 bands) with 1 m-resolution were acquired on 17 April 2013 over 13 tracks. Tracks were atmospherically corrected then mosaicked at a 2 m-resolution using a set of 24 synchronous field spectra of bare soils, black and white targets and impervious surfaces. The land use identification system layer (RPG) of 2012 was used to mask non-agricultural areas, then calculation and thresholding of NDVI from an atmospherically corrected SPOT image acquired the same day enabled to map agricultural fields with bare soil. A total of 101 sites sampled either in 2013 or in the 3 previous years and in 2015 were identified as bare by means of this map. Predictions were made from the mosaic AISA spectra which were related to topsoil SOC contents by means of partial least squares regression (PLSR). Regression robustness was evaluated through a series of 1000 bootstrap data sets of calibration-validation samples, considering 74 sites outside cloud shadows only, and different sampling strategies for selecting calibration samples. Validation root-mean-square errors (RMSE) were comprised between 3.73 and 4.49 g Kg-1 and were ∼4 g Kg-1 in median. The most performing models in terms of coefficient of determination (R2) and Residual Prediction Deviation (RPD) values were the calibration models derived either from Kennard-Stone or conditioned Latin Hypercube sampling on smoothed spectra. The most generalizable model leading to lowest RMSE value of 3.73 g Kg-1 at the regional scale and 1.44 g Kg-1 at the within-field scale and low bias was the cross-validated leave

  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 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.

  8. Experimental investigation of a linear-chain structure in the nucleus 14C

    NASA Astrophysics Data System (ADS)

    Yamaguchi, H.; Kahl, D.; Hayakawa, S.; Sakaguchi, Y.; Abe, K.; Nakao, T.; Suhara, T.; Iwasa, N.; Kim, A.; Kim, D. H.; Cha, S. M.; Kwag, M. S.; Lee, J. H.; Lee, E. J.; Chae, K. Y.; Wakabayashi, Y.; Imai, N.; Kitamura, N.; Lee, P.; Moon, J. Y.; Lee, K. B.; Akers, C.; Jung, H. S.; Duy, N. N.; Khiem, L. H.; Lee, C. S.

    2017-03-01

    It is a well-known fact that a cluster of nucleons can be formed in the interior of an atomic nucleus, and such clusters may occupy molecular-like orbitals, showing characteristics similar to normal molecules consisting of atoms. Chemical molecules having a linear alignment are commonly seen in nature, such as carbon dioxide. A similar linear alignment of the nuclear clusters, referred to as linear-chain cluster state (LCCS), has been studied since the 1950s, however, up to now there is no clear experimental evidence demonstrating the existence of such a state. Recently, it was proposed that an excess of neutrons may offer just such a stabilizing mechanism, revitalizing interest in the nuclear LCCS, specifically with predictions for their emergence in neutron-rich carbon isotopes. Here we present the experimental observation of α-cluster states in the radioactive 14C nucleus. Using the 10Be + α resonant scattering method with a radioactive beam, we observed a series of levels which completely agree with theoretically predicted levels having an explicit linear-chain cluster configuration. We regard this as the first strong indication of the linear-chain clustered nucleus.

  9. 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.

  10. Low-level occupational 14C contamination--results from a pilot study.

    PubMed

    Stenström, Kristina; Leide-Svegborn, Sigrid; Mattsson, Sören

    2008-01-01

    This paper presents a pilot study in which specific activities of 14C in hair and urine from 11 radiation workers handling 14C-containing substances have been measured using accelerator mass spectrometry. Varying degrees of contamination were revealed: up to 63% excess in hair and 400% excess in urine. Although the 14C excess reported in this study would result in low effective doses, it would be of interest to monitor the situation at other workplaces with potentially higher risks of contamination. Simultaneous measurements of 14C in hair and urine with additional random measurements of 14C in faeces and exhaled air could provide a means of improving dose estimates for workers handling different types of 14C-containing substances.

  11. The New Airborne Disease

    PubMed Central

    Goldsmith, John R.

    1970-01-01

    Community air pollution is the new airborne disease of our generation's communities. It is caused by the increasing use of fuel, associated with both affluence and careless waste. Photochemical air pollution of the California type involves newly defined atmospheric reactions, is due mostly to motor vehicle exhaust, is oxidizing, and produces ozone, plant damage, impairment of visibility and eye and respiratory symptoms. Aggravation of asthma, impairment of lung function among persons with chronic respiratory disease and a possible causal role, along with cigarette smoking in emphysema and chronic bronchitis, are some of the effects of photochemical pollution. More subtle effects of pollution include impairment of oxygen transport by the blood due to carbon monoxide and interference with porphyrin metabolism due to lead. Carbon monoxide exposures may affect survival of patients who are in hospitals because of myocardial infarction. While many uncertainties in pollution-health reactions need to be resolved, a large number of people in California have health impairment due to airborne disease of this new type. PMID:5485227

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

    PubMed

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

    2012-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    1990-08-01

    A recent experiment on the 14C fine structure has shown that the branching ratio to 209Pb ground state is quite different from the one predicted by the various models of cluster emission. Assuming that the 14C is preformed in the 223Ra nucleus, we have calculated the hindrance factor F14C of the three 14C branches to 209Pb states with a barrier penetrability approximated by a square-well Coulomb potential. The F14C=3.9 and 4.6 values found for the 14C transitions to the two excited states at 779 keV (Iπ=11/2+) and 1423 keV (Iπ=15/2-), respectively, reveal that the cluster formation amplitudes in both transitions are close to those of the 222Ra and 224Ra 14C decays. Such values could be the result of ||nlj> shell-model components common to both the wave functions of the octupole deformed 223Ra nucleus and of the two first excited states of 209Pb spherical nucleus. The high hindrance factor F14C=583 of the 14C branch to the 209Pb ground state (Iπ=9/2+) could reveal the absence of ||1g9/2> shell-model component in the 223Ra wave function.

  14. Microbially-mediated fate of {sup 14}C-pyrene in soil organic matter

    SciTech Connect

    Guthroe, E.A.; Pfaender, F.K.

    1995-12-31

    Polycyclic aromatic hydrocarbons (PAH) are ubiquitous environmental contaminants that result from both natural and anthropogenic combustion processes. Several microbial processes are known to influence the fate of PAH in soil. Their effect on PAH structure and mobility can affect the potential health risk exposure to humans and indigenous organisms in soil. Microbial metabolism of PAHs can result in the accumulation of more polar by-products or the formation of by-products that may be further metabolized or mineralized by other microorganisms. A third possible fate is the incorporation of PAHs into soil organic matter via various sorption/binding processes. Experiments were conducted to determine the extent of {sup 14}C-pyrene associations with soil organic matter (SOM) in adapted and non-adapted soils. Changes in microbial respiration (CO{sub 2} efflux), {sup 14}C volatile organics, {sup 14}C water soluble metabolites and {sup 14}C SOM were measured in aerated soil systems treated individually with 100 mg/kg [4,5,9,10-{sup 14}C] pyrene over time. Mass balances were generated based on V products in water extracts, CO{sub 2} efflux. SOM, {sup 14}C-volatiles, and residual soil. The {sup 14}C products in SOM were further fractionated into humic acids (HA), fulvic acids (FA), and humin. The presence of an adapted, microbial community enhances {sup 14}C-pyrene mineralization and increases the {sup 14}C product accumulation in water extracts and fulvic acids (FA).

  15. Airborne Mapping of Total Carbon Productivity and Export within Giant Kelp Forests in the Santa Barbara Channel

    NASA Astrophysics Data System (ADS)

    Dietz, D.; Kudela, R. M.; Broughton, J.

    2013-12-01

    Giant Kelp (Macrocystis pyrifera) is one of the world's fastest growing autotrophs, able to take up, and potentially release, massive amounts of Carbon daily. This project aims to quantify both Carbon uptake and export from two Giant Kelp forests in the Santa Barbara Channel by quantifying kelp gross primary productivity (GPP), respiration, and dissolved organic Carbon (DOC) export. A mass balance method was employed using three steps: first, the extent of kelp (surface and subsurface) was estimated. Second, gross production was estimated using a photosynthetic model. Third, loss terms including respiration and direct release of DOC were estimated. Remote sensing data of the Channel was obtained using MASTER multispectral imagery while in situ data was used to measure DOC. MASTER imagery was used in ENVI to spectrally map areas of the two kelp beds, including subsurface kelp not perceivable in true color MASTER imagery without manipulation. In order to detect subsurface kelp, spectral analysis was used within ENVI to identify vegetation at varying depths. Productivity was then estimated for surface and subsurface kelp based on the Zimmerman (2003) seagrass model, adapted to account for absorption differences of kelp at depth and life cycle stages (immature, mature, senescent). Respiration values for both beds were calculated by synthesizing data from Cavanaugh et. al, 2010, Arnold and Manley, 1985, and Rassweiller et. al, 2008. Respiration rates were assumed constant with depth, and resulted in nearly 50% of GPP for both beds. DOC values were extrapolated to the top 3m of each bed, as a pycnocline at 3 m was observed in both beds; offshore DOC values were applied to water at depth. Time series CDOM data from the MODIS satellite was utilized to estimate flow rates of DOC out of kelp beds in order to calculate flux. However, the eddy circulation pattern in the Santa Barbara Channel, combined with offshore tidal currents, caused CDOM to consistently be transported in

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

    NASA Astrophysics Data System (ADS)

    Currie, L. A.

    2003-01-01

    Radiocarbon dating would not have been possible if 14C had not had the “wrong” half-life—a fact that delayed its discovery [1]. Following the discovery of this 5730 year radionuclide in laboratory experiments by Ruben and Kamen, it became clear to W. F. Libby that 14C should exist in nature, and that it could serve as a quantitative means for dating artifacts and events marking the history of civilization. The search for natural radiocarbon was a metrological challenge; the level in the living biosphere [ca. 230 Bq/kg] lay far beyond the then current state of the measurement art. This article traces the metrological history of radiocarbon, from the initial breakthrough devised by Libby, to minor (evolutionary) and major (revolutionary) advances that have brought 14C measurement from a crude, bulk [8 g carbon] dating tool, to a refined probe for dating tiny amounts of precious artifacts, and for “molecular dating” at the 10 μg to 100 μg level. The metrological advances led to opportunities and surprises, such as the non-monotonic dendrochronological calibration curve and the “bomb effect,” that spawned new multidisciplinary areas of application, ranging from cosmic ray physics to oceanography to the reconstruction of environmental history.

  17. Assimilation of /sup 14/CO/sub 2/ and /sup 14/C sucrose by citrus fruit tissues

    SciTech Connect

    Tomlinson, P.T.; Koch, K.E.

    1987-04-01

    Assimilation and metabolism of /sup 14/CO/sub 2/ was compared to that of (U-/sup 14/C) sucrose in young grapefruit (ca 25 mm diameter) to determine their respective roles in fruit growth. Fixation of /sup 14/CO/sub 2/ by isolated fruit tissues during 10 min in light exceeded that in dark by 2- to 30-fold depending on tissue content of chlorophyll. Greatest apparent photosynthesis occurred in outer green peel, but green juice tissues assimilated more than did adjoining inner peel tissue. In the dark, juice tissues incorporated 2.5-fold more /sup 14/CO/sub 2/ than any other tissue. Neutral sugars accounted for a smaller proportion and organic acids, a greater proportion, of the /sup 14/C-assimilates in interior peel and juice tissues. These data suggest more extensive production of organic acids from /sup 14/CO/sub 2/ in tissues isolated from the fruit interior. In contrast, little difference among tissues was evident in extent of organic- and amino-acid production from exogenous (U-/sup 14/C) sucrose. A small area of cuticle on whole fruit was replaced by a filter disc impregnated with radiolabeled sucrose and incubated for 16 h. Thus, carbon derived from CO/sub 2/ assimilation by fruit appears to be partitioned differently than that derived from sucrose.

  18. Evolution of CO{sub 2} during birnessite-induced oxidation of {sup 14}C-labeled catechol

    SciTech Connect

    Majcher, E.H.; Chorover, J.; Bollag, J.M.; Huang, P.M.

    2000-02-01

    Phenolic compounds undergo several transformation processes in soil and water (i.e., partial degradation, mineralization, and polymerization), many of which have been attributed primarily to biological activity. Results from previous work indicate that naturally occurring Mn oxides are also capable of oxidizing phenolic compounds. In the present study, {sup 14}C-labeled catechol was reacted with birnessite (manganese oxide) in aqueous suspension of pH 4. The mass of catechol-derived c in solid, solution, and gas phases was quantified as a function of time. Between 5 and 16% of the total catechol C was liberated as CO{sub 2} from oxidation and abiotic ring cleavage under various conditions. Most of the {sup 14}C (55--83%) was incorporated into the solid phase in the form of stable organic reaction products whereas solution phase {sup 14}C concentrations increased from 16 to 39% with a doubling of total catechol added. Polymerization and CO{sub 2} evolution appear to be competitive pathways in the transformation of catechol since their relative importance was strongly dependent on initial birnessite-catechol reaction conditions. Solid phase Fourier transform infrared (FTIR) spectra are consistent with the presence of phenolic, quinone, and aromatic ring cleavage products. Carbon dioxide release appears to be limited by availability of reactive birnessite surface sites and it is diminished in the presence of polymerized reaction products.

  19. Infrared airborne spectroradiometer survey results in the western Nevada area

    NASA Technical Reports Server (NTRS)

    Collins, W.; Chang, S. H.; Kuo, J. T.

    1982-01-01

    The Mark II airborne spectroradiometer system was flown over several geologic test sites in western Nevada. The infrared mineral absorption bands were observed and recorded for the first time using an airborne system with high spectral resolution in the 2.0 to 2.5 micron region. The data show that the hydrothermal alteration zone minerals, carbonates, and other minerals are clearly visible in the airborne survey mode. The finer spectral features that distinguish the various minerals with infrared bands are also clearly visible in the airborne survey data. Using specialized computer pattern recognition methods, it is possible to identify mineralogy and map alteration zones and lithologies by airborne spectroradiometer survey techniques.

  20. Measurement of biocarbon in flue gases using 14C

    SciTech Connect

    Haemaelaeinen, K.M.; Jungner, H.; Antson, O.; Rasanen, J.; Tormonen, K.; Roine, J.

    2007-07-01

    A preliminary investigation of the biocarbon fraction in carbon dioxide emissions of power plants using both fossil- and biobased fuels is presented. Calculation of the biocarbon fraction is based on radiocarbon content measured in power plant flue gases. Samples were collected directly from the chimneys into plastic sampling bags. The C-14 content in CO{sub 2} was measured by accelerator mass spectrometry (AMS). Flue gases from power plants that use natural gas, coal, wood chips, bark, plywood residue, sludge from the pulp factory, peat, and recovered fuel were measured. Among the selected plants, there was one that used only fossil fuel and one that used only biofuel; the other investigated plants burned mixtures of fuels. The results show that C-14 measurement provides the possibility to determine the ratio of bio and fossil fuel burned in power plants.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  2. Assay and digestion of 14C-labelled condensed tannins in the gastrointestinal tract of sheep.

    PubMed

    Terrill, T H; Waghorn, G C; Woolley, D J; McNabb, W C; Barry, T N

    1994-09-01

    Three experiments were conducted to determine the fate of condensed tannins (CT) during digestion in sheep. CT were measured as extractable, protein-bound and fibre-bound fractions using the butanol-HCl procedure. In Expt 1, purified CT were added to digesta from different parts of the digestive tract obtained from a pasture-fed sheep. Recoveries of CT after 0 and 4 h of anaerobic incubation at 39 degrees averaged: rumen 78.9 and 57.5%; abomasum 50.9 and 49.0%; duodenum 64.4 and 46.0% and ileum 43.4 and 38.8%. In Expt 2, [14C]CT was given per abomasum over a 6.5 h period at 15 min intervals to a sheep previously fed on Lotus pedunculatus (which contains CT). The sheep was killed at the end of the period and 92.4% of the label was recovered. Virtually all of the label was in the digesta, and none was detected in the blood, so that the CT-carbon appeared not to be absorbed from the small intestine. In Expt 3, rumen, abomasal and ileal digesta and faeces samples from sheep fed on Lotus pedunculatus were analysed for CT and CT flow along the digestive tract calculated from reference to indigestible markers. Values were low in all digesta samples, indicating disappearance of CT across the rumen and small intestine, and CT recovery in faeces was only about 15% of intake. However, the 14C results from Expt 2 suggested that little if any CT-carbon was absorbed and the low recoveries in Expt 1 are considered to be a consequence of either conformational changes to the CT molecule such that it is no longer detectable by colorimetric methods, an inability of the analytical method to release bound CT for the butanol-HCl assay, or interference from other digesta constituents. It is concluded that the butanol-HCl method of CT analysis is appropriate for quantifying CT in herbages but not in digesta or faeces, and that a substantial part of CT released during protein digestion in the small intestine may not be detectable by normal CT analytical methods.

  3. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

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

  5. 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.

  6. Airborne measurements of black carbon aerosol over the Southeastern U.S. during the Southeast Atmosphere Study (SAS) experiment

    NASA Astrophysics Data System (ADS)

    Markovic, M. Z.; Perring, A. E.; Schwarz, J. P.; Fahey, D. W.; Gao, R.; Watts, L.; Holloway, J.; Graus, M.; Warneke, C.; De Gouw, J. A.; Veres, P. R.; Roberts, J. M.; Middlebrook, A. M.; Welti, A.; Liao, J.

    2013-12-01

    The Southeast Atmosphere Study (SAS) field campaign was a large-scale, collaborative project, which took place in the Southeastern U.S. in June and July of 2013. The goal of the campaign was to investigate the impacts of biogenic and anthropogenic gases and aerosols on the formation of haze and anomalous climate cooling in the region. During SAS, a NOAA Single Particle Soot Photometer (SP2) instrument was utilized onboard NOAA WP-3D research aircraft for measurements of black carbon (BC) aerosol mass and microphysical properties. BC aerosol is emitted into the atmosphere from biomass burning (BB) and incomplete combustion of fossil and biofuel. Hence, BC sources are strongly linked to anthropogenic activity. BC aerosol is currently the second largest anthropogenic climate forcing agent after CO2(g), and its climate impacts, which depend on vertical burden and internal mixing, are not fully understood. In the Southeast, BC aerosol is expected to provide surface area for the condensation of semi-volatile products of VOC oxidation and subsequent formation of secondary organic aerosol (SOA). Hence, BC is expected to impact the haze formation and regional climate. In this work we present an overview of BC measurements during Southeast Nexus (SENEX) study, the NOAA contribution to SAS. Geographical variations in mass mixing ratios, mass size distributions, and mixing state of BC over the Southeast U.S. are discussed. Relationships of BC with carbon monoxide (CO), acetonitrile (ACN) and other trace gases are used to investigate the impacts of urban, BB, natural gas development, and power plant emissions on the distribution and properties of BC aerosol in the region. Among studied urban centers, St. Louis and Atlanta were determined to be the largest source regions of BC. A clear weekend effect in BC mass mixing ratios and microphysical properties was observed in the metropolitan Atlanta region. Compared to BB and urban centers, power plants and natural gas developments

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

    USGS Publications Warehouse

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

    1998-01-01

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

  8. 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

  9. 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.

  10. 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.

  11. 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... 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...

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

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... Section 14(c) § 240.14c-3 Annual report to be furnished security holders. (a) If the information statement... Availability of Proxy Materials, annual report to security holders or information statement, as applicable. (d... 17 Commodity and Securities Exchanges 3 2010-04-01 2010-04-01 false Annual report to be...

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

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 17 Commodity and Securities Exchanges 3 2010-04-01 2010-04-01 false Providing copies of material for certain beneficial owners. 240.14c-7 Section 240.14c-7 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION (CONTINUED) GENERAL RULES AND REGULATIONS, SECURITIES EXCHANGE ACT OF...

  14. 17 CFR 240.14c-2 - Distribution of information statement.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 17 Commodity and Securities Exchanges 3 2010-04-01 2010-04-01 false Distribution of information statement. 240.14c-2 Section 240.14c-2 Commodity and Securities Exchanges SECURITIES AND EXCHANGE COMMISSION (CONTINUED) GENERAL RULES AND REGULATIONS, SECURITIES EXCHANGE ACT OF 1934 Rules and Regulations Under...

  15. 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.

  16. Multi-Year Dynamics of Upland-Oak Forest Organic Horizons: Observations Based on a Unique 14C-Tracer and a Mechanistic Model

    NASA Astrophysics Data System (ADS)

    Hanson, P. J.; Trumbore, S. E.; Swanston, C. W.; Garten, C. T.; Callaham, M. A.; Jardine, P.; Post, W. M.

    2005-12-01

    The Enriched Background Isotope Study (EBIS) was initiated on the Oak Ridge Reservation (ORR) near Oak Ridge, Tennessee in the fall of 2000 to collect and utilize unique 14C-labeled leaf litter for a multi-year, litter-replacement experiment. The goal of EBIS is to understand key mechanisms driving soil carbon cycling and to develop robust models for describing the fate and accumulation of carbon within organic and mineral soils of oak-dominated forests. EBIS uses a combination of high-to-low gradients of 14C-signatures within the soils, roots, and leaf litter across the ORR together with manipulated 14C-litter enrichments or dilutions to track litter-layer C movement through the organic and mineral soil horizons. Through 3-years of defined 14C-litter-additions, we have no evidence that canopy leaf litter is a near-term source of mineral soil carbon. Rather, the downward migration of leaf-litter carbon is driven by annual layering and gravity-induced packing of organic matter to the surface of the mineral horizons. The well-drained, acid soils of these upland sites studies support only low earthworm populations and, therefore, bioturbation is an ineffective mechanism for C transport in this ecosystem. Standard multi-component isotopic mixing models were shown to be inadequate for the prediction of the observed 14C-distributions within the organic horizons following multiple year litter additions. Models containing expanded spatial and temporal details were needed to successfully capture organic-layer C turnover and transport through the organic layers of these soils. Critical details required to model 14C-dynamics in these soils include: the tracking of individual litter-layer cohorts over time, daily time-step simulations of intra-annual litter and humus decomposition as a function of temperature and water content, and the simulation of DOC leaching as a mass-loss and differential 14C-transport process. Within only a short time span (3 to 4 years), the EBIS is

  17. Combustion/absorption process for the separation of (14)C and (3)H in radwastes released from nuclear power plants and their analysis.

    PubMed

    Ko, Young Gun; Kim, Chang-Jong; Cho, Young Hyun; Chung, Kun Ho; Kang, Mun Ja

    2017-02-16

    Radioactivities of (3)H and (14)C in spent radioactive ion exchange resins and spent radioactive lubricant oils released from nuclear power plants, has been determined using a combustion and sorption method (combustion method). The liquid scintillation counting (LSC) spectra showed that the interference of other radionuclides has not significantly affected the determination of radioactivities of (3)H and (14)C in the radwaste samples. The chemical structure of (14)CO2, which originated from the combustion of radwastes, trapped (14)C sorbent has been investigated using Fourier transform infrared spectroscopy (FT-IR). FT-IR study showed interesting results that peaks for uncoupled CO2 and carbonic amide appeared at FT-IR spectra of CO2 high-absorbed (14)C sorbents, while the peak for carbamate was only observed at the spectra of CO2 low-absorbed sorbents. During the CO2 sorption in (14)C sorbent, temperature and viscosity of the sorbent increased owing to decrease of enthalpy and increase of apparent molecular weight of the sorbent caused by the bonding formation between sorbent molecules.

  18. 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.

  19. 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.

  20. [The metabolism of [2-(14)C] glycine in rat tissues in vivo].

    PubMed

    Brodin, S V; Ianovych, V H

    1996-01-01

    It is found that two hours after intraperitoneal injection of [2-(14)C] glycine to rats its higher amount (83.6%) is used in the protein synthesis and 16.4% is catabolized. The carbonic chain of the amino acid is used to the greater extent in the synthesis of lipids than in the oxidation and glucogenesis. Radioactivity of the proteins in the investigated organs and tissues of rats varies within L7-50.6 thou. DPM per 100 mg of wet tissue and decreases in a series: small intestine mucosa, kidneys, liver, stomach mucosa, heart, lungs, cardiac muscle, skin, skeletal muscle, adipose tissue, brain. Radioactivity of lipids is within the limits of 0.2-5.1 thou. DPM per 100 mg of wet tissue 11.7-81.6% of protein radioactivity) and decreases in a series: liver, adipose tissue, kidneys, lungs, cardiac muscle, stomach mucosa, skin, skeletal muscle, brain. The total radioactivity of glucose+glycogen varies within 0.05-0.34 thou. DPM per 100 mg of wet tissue (0.8-10.7% of protein radioactivity) and decreases is a series: kidneys, liver, brain, skeletal muscle.

  1. Metabolic fate of [14C]-labeled meal protein amino acids in Aedes aegypti mosquitoes.

    PubMed

    Zhou, Guoli; Flowers, Matthew; Friedrich, Kenneth; Horton, James; Pennington, James; Wells, Michael A

    2004-04-01

    We developed a method to follow the metabolic fate of [(14)C]-labeled Euglena gracilis protein amino acids in Aedes aegypti mosquitoes under three different adult nutritional regimes. Quantitative analysis of blood meal protein amino acid metabolism showed that most of the carbon of the amino acids was either oxidized to CO(2) or excreted as waste. Under the three different adult nutritional regimes, no significant differences in the metabolism of amino acids were found, which indicated that the female A. aegypti mosquitoes possess a substantial capacity of maintaining metabolic homeostasis during a gonotrophic cycle. The amount of maternal glycogen and lipid after egg laying were significantly lower in the mosquitoes that underwent a partial starvation before a blood meal and/or starvation after the blood meal. The content of egg lipid or protein or the number of eggs laid did not show a significant difference among the three different regimes, which indicates that stable fecundity of A. aegypti under the partial starvation before a blood meal and/or starvation after the blood meal seemed to result from a trade-off between current fecundity and future survival after the eggs laid. The methods described in this paper can be applied to a wide range of questions about the effects of environmental conditions on the utilization of blood meal amino acids.

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

    PubMed

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

    2011-10-01

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

  3. Uptake of anthropogenic CO/sub 2/ by lateral transport models of the ocean based on the distribution of bomb-produced /sup 14/C

    SciTech Connect

    Peng, T.H.

    1986-01-01

    The pattern of global water column inventories of bomb-produced /sup 14/C suggests that a sizeable portion of bomb /sup 14/C that entered the Antarctic, northern Pacific, and tropical oceans has been transported to adjacent temperate regions. Models of lateral transport of surface water in the Atlantic, Indian, and Pacific Oceans are based on this distribution pattern. Upwelling of bomb-/sup 14/C-free water from below takes place in the Antarctic, northern Pacific, and tropical regions; downwelling of surface water occurs in the temperate oceans and northern Atlantic. Uptake of excess CO/sub 2/ by these models is calculated using the observed Mauna Loa pCO/sub 2/ record as an input function. Results indicate that 35% of fossil fuel CO/sub 2/ is taken up by these model oceans during the period 1958-1980. Considering the observed airborne fraction of 0.55, it appears that ca 10% of the global fossil fuel CO/sub 2/ is still missing.

  4. 14C-Based source assessment of soot aerosols in Stockholm and the Swedish EMEP-Aspvreten regional background site

    NASA Astrophysics Data System (ADS)

    Andersson, August; Sheesley, Rebecca J.; Kruså, Martin; Johansson, Christer; Gustafsson, Örjan

    2011-01-01

    Combustion-derived soot or black carbon (BC) in the atmosphere has a strong influence on both climate and human health. In order to propose effective mitigation strategies for BC emissions it is of importance to investigate geographical distributions and seasonal variations of BC emission sources. Here, a radiocarbon methodology is used to distinguish between fossil fuel and biomass burning sources of soot carbon (SC). SC is isolated for subsequent off-line 14C quantification with the chemothermal oxidation method at 375 °C (CTO-375 method), which reflects a recalcitrant portion of the BC continuum known to minimize inadvertent inclusion of any non-pyrogenic organic matter. Monitored wind directions largely excluded impact from the Stockholm metropolitan region at the EMEP-Aspvreten rural station 70 km to the south-west. Nevertheless, the Stockholm city and the rural stations yielded similar relative source contributions with fraction biomass ( fbiomass) for fall and winter periods in the range of one-third to half. Large temporal variations in 14C-based source apportionment was noted for both the 6 week fall and the 4 month winter observations. The fbiomass appeared to be related to the SC concentration suggesting that periods of elevated BC levels may be caused by increased wood fuel combustion. These results for the largest metropolitan area in Scandinavia combine with other recent 14C-based studies of combustion-derived aerosol fractions to suggest that biofuel combustion is contributing a large portion of the BC load to the northern European atmosphere.

  5. Reconstruction of last-deglacial palaeoclimate in Northeast Japan using 14C and δ13C records of marsh deposits

    NASA Astrophysics Data System (ADS)

    Shinozaki, T.; Minoura, K.; Kondo, M.; Yasuyuki, S.; Masatoshi, S.; Uchida, M.

    2009-12-01

    Today, global warming has been regarded as a serious problem. High-resolution palaeoclimatic records are needed to be reconstructed to accurately predict climate for the future. From our observations of continuous peat sediment sequences, augmented by a detailed 14C chronology and δ13C, we reconstructed hydrological circulation that related to Asia Monsoon since last 15ka. We used a sediment core (8.8m total thickness) from the Tashiro mire (40°41‧N, 144°55‧, 570m a.s.l.), Northeast Japan. It mostly consisted of peat sediment and four well known dated tephras interbedded. The base of the core is To-H tephra (about 15,000 cal BP), and the other tephras corresponded to the To-Cu (about 6,000 cal BP), To-a (1,000 cal BP) and B-Tm (about AD915) demonstrated by EPMA analysis of volcanic glasses. And we conduct 14C measurement about 50 samples, for sphagnum within peat sediments and bulk organic carbon. Hence, those sediments may have recorded abrupt climatic changes in the last-deglaciation, early-Holocene and late-Holocene. In this study, in order to reconstruct hydrological circulation around the East Asia, we carried out δ13C measurement, from a bulk organic carbon within peat sediments, that indicate for humidity or precipitation variability. So δ13C value, in the Northeast Japan, records humidity fluctuation which is nearly connected with the East Asia Monsoon. We report decadal to centennial scale environmental changes, based on a δ13C records and a detailed 14C chronology, in terrestrial at the Northwest Pacific region for the last-deglaciation.

  6. 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.

  7. Large 14C excursion in 5480 BC indicates an abnormal sun in the mid-Holocene.

    PubMed

    Miyake, Fusa; Jull, A J Timothy; Panyushkina, Irina P; Wacker, Lukas; Salzer, Matthew; Baisan, Christopher H; Lange, Todd; Cruz, Richard; Masuda, Kimiaki; Nakamura, Toshio

    2017-01-31

    Radiocarbon content in tree rings can be an excellent proxy of the past incoming cosmic ray intensities to Earth. Although such past cosmic ray variations have been studied by measurements of (14)C contents in tree rings with ≥10-y time resolution for the Holocene, there are few annual (14)C data. There is a little understanding about annual (14)C variations in the past, with the exception of a few periods including the AD 774-775 (14)C excursion where annual measurements have been performed. Here, we report the result of (14)C measurements using the bristlecone pine tree rings for the period from 5490 BC to 5411 BC with 1- to 2-y resolution, and a finding of an extraordinarily large (14)C increase (20‰) from 5481 BC to 5471 BC (the 5480 BC event). The (14)C increase rate of this event is much larger than that of the normal grand solar minima. We propose the possible causes of this event are an unknown phase of grand solar minimum, or a combination of successive solar proton events and a normal grand solar minimum.

  8. Large 14C excursion in 5480 BC indicates an abnormal sun in the mid-Holocene

    NASA Astrophysics Data System (ADS)

    Miyake, Fusa; Jull, A. J. Timothy; Panyushkina, Irina P.; Wacker, Lukas; Salzer, Matthew; Baisan, Christopher H.; Lange, Todd; Cruz, Richard; Masuda, Kimiaki; Nakamura, Toshio

    2017-01-01

    Radiocarbon content in tree rings can be an excellent proxy of the past incoming cosmic ray intensities to Earth. Although such past cosmic ray variations have been studied by measurements of 14C contents in tree rings with ≥10-y time resolution for the Holocene, there are few annual 14C data. There is a little understanding about annual 14C variations in the past, with the exception of a few periods including the AD 774‑775 14C excursion where annual measurements have been performed. Here, we report the result of 14C measurements using the bristlecone pine tree rings for the period from 5490 BC to 5411 BC with 1- to 2-y resolution, and a finding of an extraordinarily large 14C increase (20‰) from 5481 BC to 5471 BC (the 5480 BC event). The 14C increase rate of this event is much larger than that of the normal grand solar minima. We propose the possible causes of this event are an unknown phase of grand solar minimum, or a combination of successive solar proton events and a normal grand solar minimum.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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; Group, Paleo Labo AMS Dating; Yamazaki, Atsuko; Watanabe, Tsuyoshi; Yamano, Hiroya

    2016-10-01

    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

  14. Metabolism of 14C-Maltose in Avena fatua Seeds During Germination 1

    PubMed Central

    Chen, Shepley S. C.; Varner, J. E.

    1969-01-01

    Non-dormant and dormant seeds of Avena fatua metabolize 14C-maltose in different ways: in non-dormant seeds, 14C-maltose administered to the endosperm is readily converted to sucrose in the scutellum and translocated to the embryo; in dormant seeds, little sucrose is synthesized from 14C-maltose, and maltose and glucose tend to accumulate in the endosperm. It is suggested that biosynthesis of sucrose is essential for effective transport of the endosperm reserve to the embryonic axis in germinating seeds. PMID:16657130

  15. 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.

  16. 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.

  17. 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.

  18. Performance of a scanning mobility particle sizer in measuring diverse types of airborne nanoparticles: Multi-walled carbon nanotubes, welding fumes, and titanium dioxide spray.

    PubMed

    Chen, Bean T; Schwegler-Berry, Diane; Cumpston, Amy; Cumpston, Jared; Friend, Sherri; Stone, Samuel; Keane, Michael

    2016-07-01

    Direct-reading instruments have been widely used for characterizing airborne nanoparticles in inhalation toxicology and industrial hygiene studies for exposure/risk assessments. Instruments using electrical mobility sizing followed by optical counting, e.g., scanning or sequential mobility particle spectrometers (SMPS), have been considered as the "gold standard" for characterizing nanoparticles. An SMPS has the advantage of rapid response and has been widely used, but there is little information on its performance in assessing the full spectrum of nanoparticles encountered in the workplace. In this study, an SMPS was evaluated for its effectiveness in producing "monodisperse" aerosol and its adequacy in characterizing overall particle size distribution using three test aerosols, each mimicking a unique class of real-life nanoparticles: singlets of nearly spherical titanium dioxide (TiO2), agglomerates of fiber-like multi-walled carbon nanotube (MWCNT), and aggregates that constitutes welding fume (WF). These aerosols were analyzed by SMPS, cascade impactor, and by counting and sizing of discrete particles by scanning and transmission electron microscopy. The effectiveness of the SMPS to produce classified particles (fixed voltage mode) was assessed by examination of the resulting geometric standard deviation (GSD) from the impactor measurement. Results indicated that SMPS performed reasonably well for TiO2 (GSD = 1.3), but not for MWCNT and WF as evidenced by the large GSD values of 1.8 and 1.5, respectively. For overall characterization, results from SMPS (scanning voltage mode) exhibited particle-dependent discrepancies in the size distribution and total number concentration compared to those from microscopic analysis. Further investigation showed that use of a single-stage impactor at the SMPS inlet could distort the size distribution and underestimate the concentration as shown by the SMPS, whereas the presence of vapor molecules or atom clusters in some test

  19. Performance of a Scanning Mobility Particle Sizer in Measuring Diverse Types of Airborne Nanoparticles: Multi-Walled Carbon Nanotubes, Welding Fumes, and Titanium Dioxide Spray

    PubMed Central

    Chen, Bean T.; Schwegler-Berry, Diane; Cumpston, Amy; Cumpston, Jared; Friend, Sherri; Stone, Samuel; Keane, Michael

    2016-01-01

    Direct-reading instruments have been widely used for characterizing airborne nanoparticles in inhalation toxicology and industrial hygiene studies for exposure/risk assessments. Instruments using electrical mobility sizing followed by optical counting, e.g., scanning or sequential mobility particle spectrometers (SMPS), have been considered as the “gold standard” for characterizing nanoparticles. An SMPS has the advantage of rapid response and has been widely used, but there is little information on its performance in assessing the full spectrum of nanoparticles encountered in the workplace. In this study, an SMPS was evaluated for its effectiveness in producing “monodisperse” aerosol and its adequacy in characterizing overall particle size distribution using three test aerosols, each mimicking a unique class of real-life nanoparticles: singlets of nearly spherical titanium dioxide (TiO2), agglomerates of fiber-like multi-walled carbon nanotube (MWCNT), and aggregates that constitutes welding fume (WF). These aerosols were analyzed by SMPS, cascade impactor, and by counting and sizing of discrete particles by scanning and transmission electron microscopy. The effectiveness of the SMPS to produce classified particles (fixed voltage mode) was assessed by examination of the resulting geometric standard deviation (GSD) from the impactor measurement. Results indicated that SMPS performed reasonably well for TiO2 (GSD = 1.3), but not for MWCNT and WF as evidenced by the large GSD values of 1.8 and 1.5, respectively. For overall characterization, results from SMPS (scanning voltage mode) exhibited particle-dependent discrepancies in the size distribution and total number concentration compared to those from microscopic analysis. Further investigation showed that use of a single-stage impactor at the SMPS inlet could distort the size distribution and underestimate the concentration as shown by the SMPS, whereas the presence of vapor molecules or atom clusters in

  20. Seasonal variations and sources of ambient fossil and biogenic-derived carbonaceous aerosols based on 14C measurements in Lhasa, Tibet

    NASA Astrophysics Data System (ADS)

    Huang, Jie; Kang, Shichang; Shen, Chengde; Cong, Zhiyuan; Liu, Kexin; Wang, Wei; Liu, Lichao

    2010-06-01

    A total of 30 samples of total suspended particles were collected at an urban site in Lhasa, Tibet from August 2006 to July 2007 for investigating carbonaceous aerosol features. The fractions of contemporary carbon ( fc) in total carbon (TC) of ambient aerosols are presented using radiocarbon ( 14C) measurements. The value of fc represents the biogenic contribution to TC, as the biosphere releases organic compounds with the present 14C/ 12C level ( fc = 1), whereas 14C has become extinct in anthropogenic emissions of fossil carbon ( fc = 0). The fc values in Lhasa ranging from 0.357 to 0.702, are higher than Beijing and Tokyo, but clearly lower than the rural region of Launceston, which indicates a major biogenic influence in Lhasa. Seasonal variations of fc values corresponded well with variations of pollutants concentrations (e.g. NO 2). Higher fc values appeared in winter indicating carbonaceous aerosol is more dominated by wood burning and incineration of agricultural wastes within this season. The lower fc values in summer and autumn may be caused by increased diesel and petroleum emissions related to tourism in Lhasa. δ13C values ranged from - 26.40‰ to - 25.10‰, with relative higher values in spring and summer, reflecting the increment of fossil carbon emissions.

  1. Penetrative and dislodgeable residue characteristics of 14C-insecticides in apple fruit.

    PubMed

    Mota-Sanchez, David; Cregg, Bert; Hoffmann, Eric; Flore, James; Wise, John C

    2012-03-28

    Infinite- and finite-dose laboratory experiments were used to study the penetrative and dislodgeable residue characteristics of (14)C-insecticides in apple fruit. The differences in dislodgeable and penetrated residues of three radiolabeled insecticides ((14)C-thiamethoxam, (14)C-thiacloprid, and (14)C-indoxacarb), applied in aqueous solution with commercial formulations, were determined after water and methanol wash extractions. The rate of sorption and extent of penetration into the fruit cuticles and hypanthium of two apple cultivars were measured after 1, 6, and 24 h of treatment exposure, using radioactivity quantification methods. For all three compounds, 97% or more of the treatment solutions were found on the fruit surface as some form of non-sorbed residues. For indoxacarb, sorption into the epicuticle was rapid but desorption into the fruit hypanthium was delayed, indicative of a lipophilic penetration pathway. For the neonicotinoids, initial cuticular penetration was slower but with no such delay in desorption into the hypanthium.

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

    SciTech Connect

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

    1989-11-01

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

  3. 14C cluster emission: a tool for the study of nuclear structures

    NASA Astrophysics Data System (ADS)

    Hussonnois, M.; Ardisson, G.

    1994-09-01

    A brief survey of the14C cluster emission of different radium isotopes will remind the first evidence for an odd-even effect in14C radioactivity. The discovery at the I.P.N. Orsay, of a fine structure in the14C emission of223Ra enhanced the development of this new investigation field. The qualitative interpretation of the favoured transitions to the first two excited states of the209Pb daughter nucleus offers a new possibility to better understand nuclear structures of heavy deformed nuclei. For instance, an accurate determination of the energy of the14C clusters emitted by225Ac and221Fr must allow to improve our knowledge of ground state configurations of these nuclei.

  4. Search for a fine structure in the 14C decay of 222Ra

    NASA Astrophysics Data System (ADS)

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

    1991-06-01

    The 14C decay of 222Ra has been reinvestigated, using an 85 MBq activity 230U source radiochemically separated, a Si barrier detector, and a superconducting magnetic spectrometer. In a 16 days counting run, 210 14C events were recorded. The 14C particles energy value 30.930+/-0.090 MeV was found and an upper limit b<=2×10-12 was estimated for the 14C branching ratio to the 208Pb first excited state; the branching-ratio value to the 208Pb ground state, thus equal to the total branching ratio, was found to be b=λc/λα=(2.31+/-0.31)×10-10.

  5. ( 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.

  6. 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.

  7. [14C]deoxyglucose labelling of functional activity in the cephalopod central nervous system.

    PubMed

    Novicki, A; Messenger, J B; Budelmann, B U; Terrell, M L; Kadekaro, M

    1992-07-22

    For the first time, the [14C]deoxyglucose radioautographic technique has been successfully used to map physiological activity in cephalopod brains. In unilaterally blinded octopus and cuttlefish, the optic lobe of the deprived side showed a decreased uptake of the labelled tracer. This suggests that the uptake is related to functional activity. The potential of the [14C]deoxyglucose technique as a powerful tool in studying the functional organization of cephalopod brains is discussed.

  8. New measurement of exotic decay of 225Ac by 14C emission

    NASA Astrophysics Data System (ADS)

    Guglielmetti, A.; Bonetti, R.; Ardisson, G.; Barci, V.; Giles, T.; Hussonnois, M.; Le Du, J. F.; Le Naour, C.; Mikheev, V. L.; Pasinetti, A. L.; Ravn, H. L.; Tretyakova, S. P.; Trubert, D.

    The branching ratio of 225Ac decay by emission of 14C was remeasured under improved experimental conditions by using a radioactive source produced at the ISOLDE mass-separator at CERN and a nuclear track detector technique. The result, B = λ14C/λα = (4.5+/-1.4)10-12, is consistent with the anomalously high value obtained in the 1993 experiment, thus confirming the importance of nuclear-structure effects in this exotic decay.

  9. Accelerator mass spectrometry 14C dating of lime mortars: Methodological aspects and field study applications at CIRCE (Italy)

    NASA Astrophysics Data System (ADS)

    Marzaioli, Fabio; Nonni, Sara; Passariello, Isabella; Capano, Manuela; Ricci, Paola; Lubritto, Carmine; De Cesare, Nicola; Eramo, Giacomo; Quirós Castillo, Juan Antonio; Terrasi, Filippo

    2013-01-01

    Centre for Isotopic Research on Cultural and Environmental heritage (CIRCE) has, recently, obtained some promising results in testing the feasibility of mortar radiocarbon dating by means of an ad hoc developed purification procedure (CryoSoniC: Cryobraking, Sonication, Centrifugation) applied to a series of laboratory mortars. Observed results encouraged CryoSoniC accuracy evaluation on genuine mortars sampled from archeological sites of known or independently constrained age (i.e., other 14C dates on different materials). In this study, some 14C measurements performed on genuine mortars will be discussed and compared with independently estimated (i.e., radiocarbon/archaeometrical dating) absolute chronologies of two Spanish sites. Observed results confirm the agreement of the CryoSoniC mortar dates with the archaeological expectations for both examined cases. Several authors reported the possibility of obtaining accurate radiocarbon dates of mortar matrices by analyzing lime lumps: binder-related particles of different sizes exclusively composed of calcium carbonate. In this paper, preliminary data for the absolute chronology reconstruction of the Basilica of the cemetery complex of Ponte della Lama (Canosa di Puglia, Italy) based on lime lumps will also be discussed. Dating accuracy will be quantified by comparing 14C data on mortar lime lumps from a funerary inscription of known age found near the Basilica, in the same study site. For this site, a comparison between absolute chronologies performed by bulk and CryoSoniC purified lime lumps, and charcoal incased in mortars (when found) will also be discussed. Observed results for this site provide evidence of how bulk lime lump dating may introduce systematic overestimations of the analyzed sample while CryoSoniC purification allows accurate dating.

  10. Tracking deposition of a 14C-radiolabeled kudzu hairy root-derived isoflavone-rich fraction into bone.

    PubMed

    Mun, Jonathan G; Grannan, Michael D; Lachcik, Pamela J; Rogers, Randy B; Yousef, Gad G; Grace, Mary H; Janle, Elsa M; Wu, Qing Li; Simon, James E; Weaver, Connie M; Lila, Mary Ann

    2010-10-01

    Hairy roots were induced in four genotypes from three kudzu species (Pueraria montana var. lobata, P. lobata and P. phaseoloides) in vitro using Agrobacterium rhizogenes to stimulate rapid secondary metabolite synthesis. Hairy roots from P. montana var. lobata (United States Department of Agriculture no. PI 434246) yielded the highest puerarin and total isoflavone content and the greatest new biomass per growth cycle among the genotypes evaluated. Hairy roots from this genotype were selected for radiolabeling using (14)C-sucrose as a carbon source. Isoflavones from radiolabeled kudzu hairy root cultures were extracted with 80% methanol, partitioned by solvent extraction, and then subfractionated by Sephadex LH-20 gel filtration. Radiolabeled isoflavones were isolated in a highly enriched fraction, which contained predominantly puerarin, daidzin and malonyl-daidzin and had an average radioactivity of 8.614 MBq/g (232.8 μCi/g) dry fraction. The (14)C-radiolabeled, isoflavone-rich fraction was orally administered at a dose of 60 mg/kg body weight to male Sprague-Dawley rats implanted with a jugular catheter, a subcutaneous ultrafiltrate probe and a brain microdialysate probe. Serum, interstitial fluid, brain microdialysate, urine and feces were collected using a Culex(®) Automated Blood Collection System for 24 h. At the end of this period, rats were sacrificed and major tissues were collected. Analysis by a scintillation counter confirmed that a bolus dose of (14)C-radiolabeled, isoflavone-rich kudzu fraction reached bone tissues, which accumulated 0.011%, 0.09% and 0.003% of the administered dose in femur, tibia and vertebrae, respectively. Femurs extracted with 80% methanol were analyzed by high-performance liquid chromatography with electrospray ionization-mass spectrometry and were found to contain trace quantities of puerarin, daidzein and puerarin glucuronide. This study demonstrates that kudzu isoflavones and metabolites are capable of reaching bone tissues

  11. 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.

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

    PubMed

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

    2003-10-01

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

  13. Biological and biomedical (14)C-accelerator mass spectrometry and graphitization of carbonaceous samples.

    PubMed

    Chung, Ill-Min; Kim, Seung-Hyun

    2013-06-21

    Accelerator mass spectrometry (AMS) is the ultimate technique for measuring rare isotopes in small samples. Biological and biomedical applications of (14)C-AMS (bio-(14)C-AMS) commenced in the early 1990s and are now widely used in many research fields including pharmacology, toxicology, food, and nutrition. For accurate, precise, and reproducible bio-(14)C-AMS analysis, the graphitization step in sample preparation is the most critical step. So, various sample preparation methods for a process called graphitization have been reported for specific applications. Catalytic graphitization using either a flame-sealed borosilicate tube or a septa-sealed vial is a popular sample preparation method for bio-(14)C-AMS. In this review, we introduce the AMS system, especially for bio-(14)C-AMS. In addition, we also review the graphitization method for bio-(14)C-AMS to promote further understanding and improvement of sample preparation for this technique. Examples of catalytic graphitization methods over the past two decades are described.

  14. 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.

  15. Magma-derived CO 2 emissions recorded in 14C and 13C content of plants growing in Furnas caldera, Azores

    NASA Astrophysics Data System (ADS)

    Pasquier-Cardin, Aline; Allard, Patrick; Ferreira, Teresa; Hatte, Christine; Coutinho, Rui; Fontugne, Michel; Jaudon, Michel

    1999-09-01

    The environmental impact of fumarolic and soil emanations of magma-derived carbon dioxide across Furnas caldera has been investigated by measuring the 14C and 13C content of 40 specimens of different C3 plants (leaves) growing within and outside the degassing areas. The results demonstrate a significant to large 14C depletion in many of the plants due to assimilation of 14C-free endogenous CO 2 during photosynthesis and leading to artificial radiocarbon ageing of up to 4400 years. The extent of 14C ageing broadly correlates with the intensity of gas manifestations at the sampling sites, as inferred from field observations and measurements of excess CO 2 concentrations in the volcanic ground. It also provides a time-integrated measure of the amount of volcanic CO 2 locally admixed to the ambient air; at several sites this accounts for 15 to 40% of total CO 2 (420 to 600 ppm) in enriched air. In some of the plant species ( Azalea, Camellia and fern) 14C depletion is correlated with an enrichment of 13C due to assimilation of magma-derived CO 2 with a 4‰ higher δ 13C than normal atmosphere. The rate of 13C enrichment averages ca. 0.18‰ by percent of volcanic carbon fixed in the plant and includes enhanced 13C discrimination during photosynthesis as a consequence of increased ambient pCO 2 (inferred at -0.0306‰ per added ppm of volcanic CO 2). Furnas is one of the few volcanoes where clear 13C enrichment in plants due to endogenous degassing has been evidenced. Our results can be used to estimate the local intensity of volcanic soil gas fluxes in the emanating areas of Furnas caldera. They also have implications for radiocarbon dating of past eruptive events in the caldera, since plants artificially aged by previous degassing could be trapped in volcanic deposits.

  16. Use of uranium-thorium dating to determine past 14C reservoir effects in lakes: examples from Antarctica

    NASA Astrophysics Data System (ADS)

    Hall, Brenda L.; Henderson, Gideon M.

    2001-12-01

    The chronologies of many lacustrine records suffer from radiocarbon reservoir effects due to the presence of dissolved 'dead' carbon or to slow air-water exchange. Here we use the TIMS uranium-thorium disequilibrium method, in conjunction with AMS radiocarbon dating, to determine the age of lacustrine carbonates and to quantify the past radiocarbon reservoir effect in two Antarctic lakes with differing characteristics. By correcting a single-sample U/Th age for detrital contamination, a 14C offset of ˜18 000 yr was obtained for carbonates from the former grounding line of the Ross Sea ice sheet in Glacial Lake Trowbridge. This large reservoir effect is believed to result from the direct input of old CO 2 from glacial meltwater. In the second example, an isochron approach on coeval samples formed at the bottom of Lake Vida (now exposed due to lower lake level) yielded an age of 9550±340 yr B.P. and a radiocarbon reservoir age of 3600 yr. This offset was probably the result of lack of aeration due to perennial ice cover and/or strong density stratification. This evidence for long-term isolation of the lake bottom indicates another level of hardship for life in the Dry Valley lacustrine environment - an environment studied as an analogue for extreme periods of Earth history, as well as for exobiological implications. The success of the U/Th technique on these two examples indicates that TIMS U/Th dating will be of widespread use in dating the important climate information recorded in the Dry Valleys both within and beyond the 14C age range.

  17. 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.

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

    PubMed

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

    2002-01-01

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

  19. Quantitative and regional measurement of retinal blood flow in rats using N-isopropyl-p-[14C]-iodoamphetamine ([14C]-IMP).

    PubMed

    Pouliot, Mylène; Deschênes, Micheline C; Hétu, Simon; Chemtob, Sylvain; Lesk, Mark R; Couture, Réjean; Vaucher, Elvire

    2009-12-01

    Quantitative and regional measurement of retinal blood flow in rodents is of prime interest for the investigation of regulatory mechanisms of ocular circulation in physiological and pathological conditions. In this study, a quantitative autoradiographic method using N-isopropyl-p-(14)C-iodoamphetamine ([(14)C]-IMP), a diffusible radioactive tracer, was evaluated for its ability to detect changes in retinal blood perfusion during hypercapnia. Findings were compared to cerebral blood flow values measured simultaneously. Hypercapnia was induced in awaken Wistar rats by inhalation of 5% or 8% CO(2) in medical air for 5 min. [(14)C]-IMP (100 microCi/kg) was injected in the femoral vein over a 30 s period and the rats were sacrificed 2 min later. Blood flow was calculated from whole-mount retinae and 20 microm thick brain sections in discrete regions of interest by quantitative autoradiography or from digested samples of retina and brain by liquid scintillation counting. Retinal blood flow values measured with quantitative and regional autoradiography were higher in the central (108 +/- 20 ml/100 g/min) than in peripheral (84 +/- 15 ml/100 g/min) retina. These values were within the same range as cortical blood flow values (97 +/- 4 ml/100 g/min). The retinal blood flow values obtained on whole-mount retinae were validated by the sampling method. Hypercapnia significantly increased overall blood flow in the retina (24-53%) with a maximal augmentation in the peripheral region and in the brain (22-142%). The changes were stronger in the brain compared to retina (p = 0.016). These results demonstrate that retinal blood flow can be quantified using [(14)C]-IMP and compared with cerebral blood flow. This technique is a powerful tool to study how retinal blood flow is regulated in different regions of the rat retina.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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...

  5. In vivo measurement of lipogenesis in ruminants using [1-(14)C]acetate.

    PubMed

    Greathead, H M; Dawson, J M; Scollan, N D; Buttery, P J

    2001-07-01

    A method for the measurement of the rate of lipogenesis in ruminants using a continuous intravenous infusion of [1-(14)C]acetate and measuring the rate of [1-(14)C]acetate incorporation into adipose tissue lipid was evaluated. Subcutaneous adipose tissue samples obtained by biopsy over the course of a 6 h continuous intravenous infusion of [1-(14)C]acetate into a wether and a steer maintained in a 'metabolic steady state' demonstrated that the incorporation of [1-(14)C]acetate into subcutaneous adipose tissue lipid was linear for the duration of the infusion period. Subsequent measures of rates of [1-(14)C]acetate incorporation into adipose tissue lipid were made on adipose tissue samples taken at a single time point during the infusion period. The technique was used to measure rates of lipogenesis in the subcutaneous adipose tissue of fourteen Hereford x Friesian steers that had been fed a pelleted diet of dried grass at a range of metabolizable energy (ME) intakes from 1.1 x ME requirement for maintenance to ad libitum for 11 weeks. Rates of lipogenesis increased linearly with increasing ME intake. It was concluded that the method is an effective technique for measuring rates of lipogenesis in specific adipose tissue depots in vivo in ruminants.

  6. 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

  7. 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.

  8. Measurement of {alpha} and neutron decay widths of excited states of {sup 14}C

    SciTech Connect

    Haigh, P. J.; Ashwood, N. I.; Bloxham, T.; Curtis, N.; Freer, M.; McEwan, P.; Price, D.; Ziman, V.; Bohlen, H. G.; Kokalova, Tz.; Schulz, Ch.; Torabi, R.; Oertzen, W. von; Wheldon, C.; Catford, W.; Harlin, C.; Kalpakchieva, R.; Massey, T. N.

    2008-07-15

    The {sup 12}C({sup 16}O,{sup 14}O){sup 14}C reaction was studied at a beam energy of 234 MeV. The {sup 14}O ejectile was detected by a Q3D spectrometer at forward angles. The energies and angles of the excited {sup 14}C recoil break-up fragments were measured in coincidence with the {sup 14}O ejectile using a double sided silicon strip detector array at backward angles. A complete kinematic reconstruction of the reaction was performed to reconstruct the {sup 14}C*{yields}{sup 10}Be+{alpha} and {sup 14}C*{yields}{sup 13}C+n decay channels and the branching ratios and widths of these decays were calculated. Theoretical decay branches were calculated using barrier penetrability factors and were compared to the measured ratios to provide information on the spins, parities, and configurations of the states. Neutron emission was found to be favored for the 11.73, 12.96, 14.87, 16.72, and 18.6 MeV states. The 14.87, 18.6, and 21.4 MeV states were found to have a considerable width for {alpha}-decay and are candidates for the three bodied molecular cluster structure of {sup 14}C.

  9. 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.

  10. A 10,300 14C yr Record of Climate and Vegetation Change from Haiti

    NASA Astrophysics Data System (ADS)

    Higuera-Gundy, Antonia; Brenner, Mark; Hodell, David A.; Curtis, Jason H.; Leyden, Barbara W.; Binford, Michael W.

    1999-09-01

    Pleistocene and Holocene vegetation dynamics in the American tropics are inferred largely from pollen in continental lake sediments. Maritime influences may have moderated climate and vegetation changes on Caribbean islands. Stable isotope (δ18O) study of a 7.6-m core from Lake Miragoane, Haiti, provided a high-resolution record of changing evaporation/precipitation (E/P) since ∼10,300 14C yr B.P. The Miragoane pollen record documents climate influences and human impacts on vegetation in Hispaniola. The δ18O and pollen data near the base of the core indicate cool, dry conditions before ∼10,000 14C yr B.P. Lake Miragoane filled with water in the early Holocene as E/P declined and the freshwater aquifer rose. Despite increasing early Holocene moisture, shrubby, xeric vegetation persisted. Forest expanded ∼7000 14C yr B.P. in response to greater effective moisture and warming. The middle Holocene (∼7000-3200 14C yr B.P.) was characterized by high lake levels and greatest relative abundance of pollen from moist forest taxa. Climatic drying that began ∼3200 14C yr B.P. may have driven some mesophilic animal species to extinction. The pollen record of the last millennium reflects pre-Columbian (Taino) and European deforestation. Long-term, Holocene vegetation trends in southern Haiti are comparable to trends from continental, lowland circum-Caribbean sites, suggesting a common response to regional climate change.

  11. Discovery of radioactive decay of /sup 222/Ra and /sup 224/Ra by /sup 14/C emission

    SciTech Connect

    Price, P.B.; Stevenson, J.D.; Barwick, S.W.; Ravn, H.L.

    1985-01-28

    Using the ISOLDE on-line isotope separator at CERN to produce sources of /sup 221/Fr, /sup 221/Ra, /sup 222/Ra, /sup 223/Ra, and /sup 224/Ra, and using polycarbonate track-recording films sensitive to energetic carbon nuclei but not to alpha particles, we have discovered two new cases of the rare /sup 14/C decay mode: in /sup 222/Ra and /sup 224/Ra. Our results for branching ratios, B, relative to alpha decay are for /sup 221/Fr and /sup 221/Ra, B<4.4 x 10/sup -12/; for /sup 222/Ra, B = (3.7 +- 0.6) x 10/sup -10/; for /sup 223/Ra, B = (6.1 +- 1.0) x 10/sup -10/; for /sup 224/Ra, B = (4.3 +- 1.2) x 10/sup -11/. .AE

  12. Exotic Archaeology:. Searching for Superheavy Elements in Nature and Dating Human DNA with the 14C Bomb Peak

    NASA Astrophysics Data System (ADS)

    Kutschera, Walter; Dellinger, Franz; Liebl, Jakob; Steier, Peter

    2011-03-01

    This contribution conveys the power of accelerator mass spectrometry (AMS) to measure ultra-low traces of long-lived radionuclides in two highly divers fields: Astrophysics and molecular biology. Our search for nuclides of superheavy elements (SHE) in several natural materials did not confirm the claims of positive evidence for SHEs reported by the group of Amnon Marinov from Jerusalem, even though the sensitivity of our AMS measurements were several orders of magnitude higher. We also report on the investigation by the group of Kirsty Spalding from Stockholm to date human DNA with the 14C bomb peak. This allows one to determine retrospectively the birth date of cells in sections of the human body. Ongoing efforts to miniaturize carbon samples down to the level of 10 μg C for AMS measurements will allow one to venture into ever smaller subsections of the human brain.

  13. Operational overview of the NASA GTE/CITE 3 airborne instrument intercomparisons for sulfur dioxide, hydrogen sulfide, carbonyl sulfide, dimethyl sulfide, and carbon disulfide

    NASA Technical Reports Server (NTRS)

    Hoell, James M., Jr.; Davis, Douglas D.; Gregory, Gerald L.; Mcneal, Robert J.; Bendura, Richard J.; Drewry, Joseph W.; Barrick, John D.; Kirchhoff, Volker W. J. H.; Motta, Adauto G.; Navarro, Roger L.

    1993-01-01

    This paper reports the overall experimental design and gives a brief overview of results from the third airborne Chemical Instrumentation Test and Evaluation (CITE 3) mission conducted as part of the National Aeronautics and Space Administration's Global Tropospheric Experiment. The primary objective of CITE 3 was to evaluate the capability of instrumentation for airborne measurements of ambient concentrations of SO2, H2S, CS, dimethyl sulfide, and carbonyl sulfide. Ancillary measurements augmented the intercomparison data in order to address the secondary objective of CITE 3 which was to address specific issues related to the budget and photochemistry of tropospheric sulfur species. The CITE 3 mission was conducted on NASA's Wallops Flight Center Electra aircraft and included a ground-based intercomparison of sulfur standards and intercomparison/sulfur science flights conducted from the NASA Wallops Flight Facility, Wallops Island, Virginia, followed by flights from Natal, Brazil. Including the transit flights, CITE 3 included 16 flights encompassing approximately 96 flight hours.

  14. Differences in ( sup 14 C)glycerol utilization in normal and familial hypercholesterolemic fibroblasts

    SciTech Connect

    Shireman, R.B.; Durieux, J. )

    1991-01-01

    It is known that cultured fibroblasts from familial hypercholesterolemia (FH) patients lack the normal cell receptor for low density lipoprotein (LDL) and that the absence of receptor-mediated transport of LDL cholesterol into these cells results in increased cellular synthesis of cholesterol. After 20 h perincubation in lipid-free medium, cultured FH fibroblasts incorporated significantly greater amounts of ({sup 14}C)glycerol into cellular lipids than did normal fibroblasts. Relative to the control medium which contained only bovine serum albumin (BSA), preincubation with 5% fetal bovine serum or 50 micrograms LDL/ml decreased ({sup 14}C)glycerol incorporation by both cell types. FH cells utilized more ({sup 14}C)glycerol for phospholipid synthesis and less for triglyceride synthesis than normal cells. This study indicates that LDL may be important in the transport of glycerides, as well as cholesterol, to cells.

  15. [Fermentative degradation of 2-14C-mannose with Leuconostoc mesenteroides (author's transl)].

    PubMed

    Ziegler, E; Dahmen, J

    1975-12-31

    Mannose-2-14C has been fermented by Leuconostoc mesenteroides, CO2 ethanol and D-lactic acid were formed in a molar ratio of 1:1:1. A small amount of acetic acid was found as by-product. It could easily be isolated from the main products of the fermentation and it did not disturb further degradation procedures. The methyl-C-atom of ethanol, which was derived from C-2 of the mannose, had nearly the same specific radioactivity as mannose-2-14C. All other C-atoms of the degradation products were only very slightly labeled. Their content of radioactivity was in any case lower than 3% of the specific radioactivity of the degraded mannose. This procedure is applicable for the degradation of 14C-labeled mannose.

  16. 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.

  17. 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)<