A gaseous measurement system for carbon-14 dioxide and carbon-14 methane: An analytical methodology to be applied in the evaluation of the carbon-14 dioxide and carbon-14 methane produced via microbial activity in volcanic tuff

International Nuclear Information System (INIS)

Dolan, M.M.

1987-01-01

The objectives of this study were to develop a gaseous measurement system for the carbon-14 dioxide and carbon-14 methane produced via microbial activity or geochemical action on leachate in tuff; to determine the trapping efficiency of the system for carbon-14 dioxide; to determine the trapping efficiency of the system for carbon-14 methane; to apply the experimentally determined factors regarding the system's trapping efficiency for carbon-14 dioxide and carbon-14 methane to a trapping algorithm to determine the activity of the carbon-14 dioxide and carbon-14 methane in a mixed sample; to determine the minimum detectable activity of the measurement process in picocuries per liter; and to determine the lower limit or detection of the measurement process in counts per minute

Carbon and carbon-14 in lunar soil 14163

International Nuclear Information System (INIS)

Fireman, E.L.; Stoenner, R.W.

1981-01-01

Carbon is removed from the surface of lunar soil 14163 size fractions by combustions at 500 and 1000 0 C in an oxygen stream and the carbon contents and the carbon-14 activities are measured. The carbon contents are inversely correlated with grain size. A measured carbon content of 198 ppM for bulk 14163, obtained by combining the size fraction results, is modified to 109 +- 12 ppM by a carbon contamination correction. This value is in accord with a previous determination, 110 ppM, for bulk 14163. The small ( 53 μ) grains, 11.2 +- 2.0 dpm/kg. The combusted carbon and carbon-14 are attributed mainly to solar-wind implantation. Melt extractions of carbon-14 from the combusted soil samples gave essentially identical activities, 21.0 +- 1.5 and 19.2 +- 2.0 dpm/kg for the small and large grains, and are attributed to cosmic-ray spallation-produced carbon-14

The long-term trend of carbon-14 level in Japan

International Nuclear Information System (INIS)

Yoshikazu Inoue; Tetsuo Iwakura

1993-01-01

The long-term trend of the specific activity of 14 C in terms of dpm/gC from 1942 to 1991 in the natural environment in Japan was obtained as baseline data by analyzing plant components so as to evaluate the collective effective dose. It was deduced that the specific activity of 14 C in plants reflected well that of atmospheric 14 CO 2 . Uniform distribution of the specific activity in plant among species as well as the production places was confirmed. The Suess effect was observed clearly for a period of 10 years from the late 1960's. The 14 C level was at about 13.7 dpm/gC due to cosmic ray production in 1940's, and reached a peak of about 24.5 dpm/gC in 1963 due to nuclear weapons testing and decreased to 15.6 dpm/gC in 1991. Fermented alcohol proved to be a convenient indicator for measuring the annual mean specific activity of 14 C in the atmosphere. (3 figs.)

26 CFR 31.3401(a)(14)-1 - Group-term life insurance.

Science.gov (United States)

2010-04-01

...) EMPLOYMENT TAXES AND COLLECTION OF INCOME TAX AT SOURCE EMPLOYMENT TAXES AND COLLECTION OF INCOME TAX AT SOURCE Collection of Income Tax at Source § 31.3401(a)(14)-1 Group-term life insurance. (a) The cost of... 26 Internal Revenue 15 2010-04-01 2010-04-01 false Group-term life insurance. 31.3401(a)(14)-1...

Adsorption of carbon-14 on mortar

International Nuclear Information System (INIS)

Matsumoto, Junko; Banba, Tsunetaka; Muraoka, Susumu

1995-01-01

The sorption experiments of carbon-14 on the mortar grain (grain size: 0.50--1.0 mm) focused on the chemical form of the carbon-14 were carried out by the batch method. Three kinds of carbon-14 chemical form were used for the experiments: sodium carbonate (Na 2 14 CO 3 ) as the inorganic radiocarbon, and sodium acetate (CH 3 14 COONa) and acetaldehyde ( 14 CH 3 14 CHO) as the organic radiocarbons. 0.30 gram samples of mortar were soaked in the solution with carbon-14 at 15 C for periods of up to 160 days. At the end of each run, carbon-14 concentrations in the supernatants were determined before and after centrifugation (3,500 rpm., 1 hr). In the mortar-sodium carbonate system, the retention process of carbon-14 related to reaction on the surface of the mortar was speculated as follows. First, 3CaO-SiO 2 and 2CaO-SiO 2 of the mortar components contact with water and produce Ca(OH) 2 . Ca(OH) 2 produces Ca 2+ and OH - in the solution. Then, calcite forms from Ca 2+ and CO 3 2- in the solution. Thus, the sorption ratio of carbon-14 onto mortar will be high until mortar has been completely carbonated because Ca 2+ is rich in the mortar and the solubility of calcite is low. In the mortar-organic carbon system, the soluble organic carbon-14 is hardly sorbed on the surface of the mortar. Therefore, the cementitious materials may not inhibit the release of organic radiocarbons from the low-level radioactive wastes, contrary to the case of inorganic radiocarbon

Carbon-14 waste management

International Nuclear Information System (INIS)

Bush, R.P.

1984-01-01

As part of their research programme on Radioactive Waste Management, the Commission of the European Communities has provided financial support for a detailed study of wastes containing 14 C and the options for their management. The main results of this study are outlined. Carbon-14 is formed by neutron activation reactions in core materials and is therefore present in a variety of waste streams both at reactors and at reprocessing plants. Data on the production and release of 14 C from various reactor systems are presented. A possible management strategy for 14 C might be reduction of 14 N impurity levels in core materials, but only reductions of about a factor of five in arisings could be achieved in this way. The key problem in 14 C management is its retention in off-gas streams, particularly in the dissolver off-gas stream at reprocessing plants. In this stream the nuclide is present as carbon dioxide and is extensively isotopically diluted by the carbon dioxide content of the air. Processes for trapping 14 C from these off-gases must be integrated with the other processes in the overall off-gas treatment system, and should provide for conversion to a stable solid compound of carbon, suitable for subsequent immobilization and disposal. Three trapping processes that convert carbon dioxide into insoluble carbonates can be identified: the double alkali (NaOH/Ca(OH) 2 ) process, the direct calcium hydroxide slurry process, and the barium ocathydrate gas/solid process. Calcium or barium carbonates, produced in the above processes, could probably be incorporated into satisfactory immobilized waste forms. However, the stability of such waste forms to prolonged irradiation and to leaching remains to be investigated. (author)

Evaluation of carbon-14 life cycle in reactors VVER-1000

International Nuclear Information System (INIS)

Lysakova, Katerina; Neumann, Jan; Vonkova, Katerina

2012-09-01

This work is aimed at the evaluation of carbon-14 life cycle in light water reactors VVER-1000. Carbon-14 is generated as a side product in different systems of nuclear reactors and has been an issue not only in radioactive waste management but mainly in release into the environment in the form of gaseous effluents. The principal sources of this radionuclide are in primary cooling water and fuel. Considerable amount of C-14 is generated by neutron reactions with oxygen 17 O and nitrogen 14 N present in water coolant and fuel. The reaction likelihood and consequently volume of generated radioisotope depends on several factors, especially on the effective cross-section, concentrations of parent elements and conditions of power plant operating strategies. Due to its long half-life and high capability of integration into the environment and thus into the living species, it is very important to monitor the movement of carbon-14 in all systems of nuclear power plant and to manage its release out of NPP. The dominant forms of radioactive carbon-14 are the hydrocarbons owing to the combinations with hydrogen used for absorption of radiolytic oxygen. These organic compounds, such as formaldehyde, methyl alcohol, ethyl alcohol and formic acid can be mostly retained on ion exchange resins used in the system for purifying primary cooling water. The gaseous carbon compounds (CH 4 and CO 2 ) are released into the atmosphere via the ventilation systems of NPP. Based on the information and data obtained from different sources, it has been designed a balance model of possible carbon-14 pathways throughout the whole NPP. This model includes also mass balance model equations for each important node in system and available sampling points which will be the background for further calculations. This document is specifically not to intended to describe the best monitoring program attributes or technologies but rather to provide evaluation of obtained data and find the optimal way to

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

Science.gov (United States)

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

Carbon-14 as an hydrology tool

International Nuclear Information System (INIS)

Garcia y G, E.; Albarran B, R.

1977-01-01

Carbon-14 and tritium results from the action of cosmic radiation and of nuclear tests also. In general carbon-14 resulting from nuclear arms tests is of no interest from the hydrological point-of view, as tritium is a more efficient marker of juvenile waters through having a much shorter disintegration period. Radioactive carbon oxidizes and forms carbon dioxide which mixes with atmospheric carbon dioxide and enters the global carbon cycle. Use of carbon-14 in the dating of subterranean waters is based on the fact that the carbon dioxide found in the soil zone is of biologic origin arising from the respiration and decomposition of plant roots. Therefore it contains carbon-14 taken from the atmosphere by the plants. This carbon dioxide of biogenic origin is dissolved in infiltrating water and is borne along towards the water bearing strata. Its carbon-14 content decrease through radioactive loss and the fractional remainder of the original contents indicates the time which has passed since it left the supply zone in the soil, that is, the time passed since it filtrated the water. (author)

Sources and characteristics of terrestrial carbon in Holocene-scale sediments of the East Siberian Sea

Science.gov (United States)

Keskitalo, Kirsi; Tesi, Tommaso; Bröder, Lisa; Andersson, August; Pearce, Christof; Sköld, Martin; Semiletov, Igor P.; Dudarev, Oleg V.; Gustafsson, Örjan

2017-09-01

Thawing of permafrost carbon (PF-C) due to climate warming can remobilise considerable amounts of terrestrial carbon from its long-term storage to the marine environment. PF-C can be then be buried in sediments or remineralised to CO2 with implications for the carbon-climate feedback. Studying historical sediment records during past natural climate changes can help us to understand the response of permafrost to current climate warming. In this study, two sediment cores collected from the East Siberian Sea were used to study terrestrial organic carbon sources, composition and degradation during the past ˜ 9500 cal yrs BP. CuO-derived lignin and cutin products (i.e., compounds solely biosynthesised in terrestrial plants) combined with δ13C suggest that there was a higher input of terrestrial organic carbon to the East Siberian Sea between ˜ 9500 and 8200 cal yrs BP than in all later periods. This high input was likely caused by marine transgression and permafrost destabilisation in the early Holocene climatic optimum. Based on source apportionment modelling using dual-carbon isotope (Δ14C, δ13C) data, coastal erosion releasing old Pleistocene permafrost carbon was identified as a significant source of organic matter translocated to the East Siberian Sea during the Holocene.

Carbon-14 Graphitization Chemistry

Science.gov (United States)

Miller, James; Collon, Philippe; Laverne, Jay

2014-09-01

Accelerator Mass Spectrometry (AMS) is a process that allows for the analysis of mass of certain materials. It is a powerful process because it results in the ability to separate rare isotopes with very low abundances from a large background, which was previously impossible. Another advantage of AMS is that it only requires very small amounts of material for measurements. An important application of this process is radiocarbon dating because the rare 14C isotopes can be separated from the stable 14N background that is 10 to 13 orders of magnitude larger, and only small amounts of the old and fragile organic samples are necessary for measurement. Our group focuses on this radiocarbon dating through AMS. When performing AMS, the sample needs to be loaded into a cathode at the back of an ion source in order to produce a beam from the material to be analyzed. For carbon samples, the material must first be converted into graphite in order to be loaded into the cathode. My role in the group is to convert the organic substances into graphite. In order to graphitize the samples, a sample is first combusted to form carbon dioxide gas and then purified and reduced into the graphite form. After a couple weeks of research and with the help of various Physics professors, I developed a plan and began to construct the setup necessary to perform the graphitization. Once the apparatus is fully completed, the carbon samples will be graphitized and loaded into the AMS machine for analysis.

Monitoring and removal of gaseous carbon-14 species

International Nuclear Information System (INIS)

Kabat, M.J.

1979-01-01

A simple and efficient method was developed for the monitoring of low level carbon-14 in nuclear power station areas and gaseous effluent. Gaseous carbon compounds (hydrocarbons and CO) are catalytically oxidized to CO 2 , which is then absorbed on solid Ca(OH) 2 at elevated temperatures. The 14 C collected is quantitatively liberated by thermal decomposition of CaCO 3 as CO 2 , which is either measured directly by flow-through detectors or absorbed in alkali hydroxide followed by liquid scintillation counting. The method can also be used for the removal of gaseous 14 C. The Ca 14 CO 3 can be immobilized in concrete for long term disposal. Ca(OH) 2 is an inexpensive absorber. It is selective for CO 2 and has high capacity and efficiency for its absorption and retention. A theoretical evaluation of thee optium conditions for CO 2 absorption and liberation is discussed and experimental investigations are described. There is good agreement between theoretical predictions and experimental findings

Carbon-14 Bomb-Pulse Dating

Energy Technology Data Exchange (ETDEWEB)

Buchholz, B A

2007-12-16

Atmospheric testing of nuclear weapons during the 1950s and early 1960s doubled the concentration of carbon-14 atmosphere and created a pulse that labeled everything alive in the past 50 years as carbon moved up the food chain. The variation in carbon-14 concentration in time is well-documented and can be used to chronologically date all biological materials since the mid-1950s.

Carbon-14 discharges from the nuclear fuel cycle: Pt. 1

International Nuclear Information System (INIS)

McCartney, M.; Baxter, M.S.; Scott, E.M.

1988-01-01

The radiological impact of 14 C produced by the nuclear fuel cycle is assessed using an advanced 25-box model of the carbon cycle coupled with a range of feasible energy-use scenarios. In particular, this study estimates both the short- and long-term dose implications to the global population. In the former context, it is predicted that the atmospheric 14 C specific activity in the year 2050 will be 234 Bq kg -1 (carbon), corresponding to delivery of an individual effective dose equivalent rate of 15 μSv year -1 . The contribution of reactor-derived 14 C to the individual dose rate increases steadily throughout this period, reaching 1.8 μSv year -1 in 2050, well within ICRP limits. In the longer term, however, the collective effective dose equivalent commitment is conservatively estimated at 141 man Sv TBq -1 , corresponding to 480 man Sv (GW(e) year) -1 . These figures indicate that 14 C could generate one of the largest contributions to the total dose to man from nuclear power production. (author)

Carbon-14 releases from an unsaturated repository: A senseless but expensive dilemma

International Nuclear Information System (INIS)

Pflum, C.G.

1993-01-01

The purpose of the US Environmental Protection Agency (EPA) Environmental Standards for the Management and Disposal of Spent Nuclear Fuel, High-Level and Transuranic Radioactive Wastes (40 CFR Part 191 or standards) is to protect public health and safety. The 1985 rule was developed on the basis of the assumption that the repository would be located in a geologic formation that lies below the water table. It is appropriate to examine gaseous releases and transport of pollutants in order to determine site adequacy. When the provisions of the 1985 standard are applied to Yucca Mountain, specifically the limits for carbon-14, we can release in 10,000 years no more than 7,000 curies of carbon-14 in the form of carbon dioxide. Meanwhile, the US Department of Energy (DOE) and others indicate that the repository may release about 8,000 curies of carbon-14 dioxide, an amount that exceeds the standard by 10 to 20 percent. The original basis of the 1985 standards was that, in a site below the water table, the limit for carbon-14 was technically achievable. It was not a standard based on a release level that would prevent a danger to public health. If we examine the danger to public health of the release of 8,000 curies of carbon-14 dioxide during and 8,000-year period, this release would not a pose a significant threat to the average individual. Industry and natural sources release many times this amount of carbon-14 dioxide each year. The question therefore becomes: is it appropriate to spend an additional $3.2 billion on waste packages when the expenditure does not measurably improve the public health?

Syntheses of carbon-14 and sulfur-35 labeled 2-(Morpholinothio)-benzothiazoles and carbon-14 labeled 2-(Cyclohexylaminothio)-benzothiazoles

Energy Technology Data Exchange (ETDEWEB)

Tanaka, A.; Fukuoka, M.; Adachi, T.; Yamaha, T.

1986-04-01

Some vulcanizing accelerators, mercaptobenzothiazole derivatives labeled with carbon-14 or sulfur-35 were prepared. 2-(Morpholinothio)benzothiazole labeled with carbon-14 or sulfur-35 of the sulfhydryl group at position 2 was synthesized by oxidative condensation with sodium hypochlorite from a mixture of morpholine and 2-mercaptobenzothiazole-2-/sup 14/C or 2-mercaptobenzothiazole-2-/sup 35/S. The same method was applicable to the synthesis of 2-(morpholino-U-/sup 14/C-thio) -benzothiazole using morpholine-U-/sup 14/C as starting material. 2-(Cyclohexylaminothio)benzothiazole-2-/sup 14/C was prepared, by oxidation with a mixture of iodine and potassium iodide, from cyclohexylamine and 2-mercapto-benzothiazole-2-/sup 14/C, which was synthesized from carbon-/sup 14/C disulfide and 2-mercaptoaniline in the presence of trace sodium sulfide in dimethylformamide. 2-(Cyclohexyl-U-/sup 14/C-aminothio)benzothiazole was also obtained from cylcohexyl-amine-U-/sup 14/C and 2-mercaptobenzothiazole.

Global impact of carbon-14 from nuclear power reactors

International Nuclear Information System (INIS)

Moghissi, A.A.; Carter, M.W.

1977-01-01

Carbon-14 is produced by nuclear power reactors, predominently as a result of the interaction of a neutron and nitrogen-14 both in the fuel and in the coolant. Several other reactions also contribute to the production of carbon-14. Present operational procedures, in general, for reactors and fuel reprocessing plants result in the release of carbon-14 into the environment. Combustion of fossil fuels and certain industrial operations contribute to the supply of CO 2 in the atmosphere and this contribution is essentially free of carbon-14. Future carbon-14 burdens by assuming a thorough mixing of all CO 2 in the atmosphere is predicted. Available data on electric power generation, fossil fuel combustion and certain other information are used to calculate the projected specific activity of carbon-14 by the year 2000 and the twenty-first century. According to these calculations, the global population dose from carbon-14 can be substantial. Also, carbon-14 in the vicinity of nuclear power reactors is considered. Because of the chemistry of carbon-14, it is shown that local problems may be more significant around BWR's as compared to PWR's. Based on environmental considerations of carbon-14, its increasing production and discharge into the atmosphere, and available control technology, it is recommended that nitrogen use and its presence be minimized in pertinent reactor components and operations

Quantifying Carbon-14 for Biology Using Cavity Ring-Down Spectroscopy

OpenAIRE

McCartt, A. Daniel; Ognibene, Ted J.; Bench, Graham; Turteltaub, Kenneth W.

2016-01-01

A cavity ring-down spectroscopy (CRDS) instrument was developed using mature, robust hardware for the measurement of carbon-14 in biological studies. The system was characterized using carbon-14 elevated glucose samples and returned a linear response up to 387 times contemporary carbon-14 concentrations. Carbon-14 free and contemporary carbon-14 samples with varying carbon-13 concentrations were used to assess the method detection limit of approximately one-third contemporary carbon-14 levels...

Short-term rhizosphere effect on available carbon sources, phenanthrene degradation and active microbiome in an aged-contaminated industrial soil

Directory of Open Access Journals (Sweden)

François eThomas

2016-02-01

Full Text Available Over the last decades, understanding of the effects of plants on soil microbiomes has greatly advanced. However, knowledge on the assembly of rhizospheric communities in aged-contaminated industrial soils is still limited, especially with regard to transcriptionally active microbiomes and their link to the quality or quantity of carbon sources. We compared the short-term (2-10 days dynamics of bacterial communities and potential PAH-degrading bacteria in bare or ryegrass-planted aged-contaminated soil spiked with phenanthrene, put in relation with dissolved organic carbon sources and polycyclic aromatic hydrocarbon (PAH pollution. Both resident and active bacterial communities (analyzed from DNA and RNA, respectively showed higher species richness and smaller dispersion between replicates in planted soils. Root development strongly favored the activity of Pseudomonadales within the first two days, and of members of Actinobacteria, Caulobacterales, Rhizobiales and Xanthomonadales within 6-10 days. Plants slowed down the dissipation of phenanthrene, while root exudation provided a cocktail of labile substrates that might preferentially fuel microbial growth. Although the abundance of PAH-degrading genes increased in planted soil, their transcription level stayed similar to bare soil. In addition, network analysis revealed that plants induced an early shift in the identity of potential phenanthrene degraders, which might influence PAH dissipation on the long-term.

The metabolism and dosimetry of carbon-14 labelled compounds

International Nuclear Information System (INIS)

Crawley, F.E.H.

1977-01-01

The number of compounds labelled at high specific activity with carbon-14 has greatly increased over the last few years. There are limited biological data available to enable an assessment of the internal radiation dose and to identify the critical tissues after an intake of such compounds. The ICRP consider two Model Systems for deriving dose. Both Models assume a total elimination of the carbon-14 in the breath and only bone or whole body as critical tissues and are not representative of the majority of the compounds now available. A research programme has been established to study the rate of excretion and tissue distribution of selected carbon-14 labelled compounds in the rat after intravenous injection, pulmonary and gastric intubation and skin absorption. These metabolic data have been used to calculate the committed dose equivalent and maximum permissible annual intake (MPAI) for various tissues in man on the assumption that the experimental data obtained in the rat are true for man. To date potassium 14 C-cyanide and 14 C-methanol have been studied. The values for the MPAI's derived from the doses to individual tissues are more restrictive than values calculated from the whole body doses. The MPAI calculated from excretion data in terms of whole body dose is 31 mCi for 14 C-cyanide and 25 mCi for 14 C-methanol. However, the critical tissue for 14 C-cyanide is the stomach with an MPAI of 1.5 mCi based on a dose of 10.7 rem mCi -1 . This was an order of magnitude greater than the dose to any other region of the GI tract and 5 times that to the testis. The critical organs for 14 C-methanol are the testis (MPAI 2.5 mCi) for males and the ovaries (MPAI 6.2 mCi) for females

Carbon-14 dynamics in rice: an extension of the ORYZA2000 model

Energy Technology Data Exchange (ETDEWEB)

Galeriu, D.; Melintescu, A. [' ' Horia Hulubei' ' National Institute for Physics and Nuclear Engineering, Life and Environmental Physics Department, 30 Reactorului St., POB MG-6, Bucharest-Magurele (Romania)

2014-03-15

Carbon-14 ({sup 14}C) is a radionuclide of major interest in nuclear power production. The Fukushima accident changed the public attitude on the use of nuclear energy all over the world. In terms of nuclear safety, the need of quality-assured radiological models was emphasized by many international organizations, and for models used by decision-makers (i.e. regulatory environmental models and radiological models), a moderate conservatism, transparency, relative simplicity and user friendliness are required. Because the interaction between crops and the environment is complex and regulated by many feedback mechanisms, however, these requirements are difficult to accomplish. The present study makes a step forward regarding the development of a robust model dealing with food contamination after a short-term accidental emission and considers a single crop species, rice (Oryza sativa), one of the most widely used rice species. Old and more recent experimental data regarding the carbon dynamics in rice plants are reviewed, and a well-established crop growth model, ORYZA2000, is used and adapted in order to assess the dynamics of {sup 14}C in rice after a short-term exposure to {sup 14}CO{sub 2}. Here, the model is used to investigate the role of the genotype, management and weather on the concentration of radiocarbon at harvest. (orig.)

Two dimensional model study of atmospheric transport using carbon-14 and strontium-90 as inert tracers

International Nuclear Information System (INIS)

Kinnison, D.E.; Wuebbles, D.J.; Johnston, H.S.

1992-02-01

This study tests the transport processes in the LLNL two-dimensional chemical-radiative-transport model using recently reanalyzed carbon-14 and strontium-90 data. These radioactive tracers were produced bythe atmospheric nuclear bomb tests of 1952--58 and 1961--62, and they were measured at a few latitudes up to 35 kilometers over the period 1955--1970. Selected horizontal and vertical eddy diffusion coefficients were varied in the model to test their sensitivity to short and long term transpose of carbon-14. A sharp transition of K zz and K yy through the tropopause, as opposed to a slow transition between the same limiting values, shows a distinct improvement in the calculated carbon-14 distributions, a distinct improvement in the calculated seasonal and latitudinal distribution of ozone columns (relative to TOMS observations), and a very large difference in the calculated ozone reduction by a possible fleet of High Speed Civil Transports. Calculated northern hemisphere carbon-14 is more sensitive to variation of K yy than are global ozone columns. Strontium-90 was used to test the LLNL tropopause height at four different latitudes. Starting with the 1960 background distribution of carbon-14, we calculate the input of carbon-14 as the sum of each nuclear test of the 1961--62 series, using two bomb-cloud rise models. With the Seitz bomb-rise formulation in the LLNL model, we find good agreement between calculated and observedcarbon-14 (with noticeable exceptions at the north polar tropopause and the short-term mid-latitude mid-stratosphere) between 1963 and 1970

Carbon Sources for Polyhydroxyalkanoates and an Integrated Biorefinery

Directory of Open Access Journals (Sweden)

Guozhan Jiang

2016-07-01

Full Text Available Polyhydroxyalkanoates (PHAs are a group of bioplastics that have a wide range of applications. Extensive progress has been made in our understanding of PHAs’ biosynthesis, and currently, it is possible to engineer bacterial strains to produce PHAs with desired properties. The substrates for the fermentative production of PHAs are primarily derived from food-based carbon sources, raising concerns over the sustainability of their production in terms of their impact on food prices. This paper gives an overview of the current carbon sources used for PHA production and the methods used to transform these sources into fermentable forms. This allows us to identify the opportunities and restraints linked to future sustainable PHA production. Hemicellulose hydrolysates and crude glycerol are identified as two promising carbon sources for a sustainable production of PHAs. Hemicellulose hydrolysates and crude glycerol can be produced on a large scale during various second generation biofuels’ production. An integration of PHA production within a modern biorefinery is therefore proposed to produce biofuels and bioplastics simultaneously. This will create the potential to offset the production cost of biofuels and reduce the overall production cost of PHAs.

Carbon Sources for Polyhydroxyalkanoates and an Integrated Biorefinery.

Science.gov (United States)

Jiang, Guozhan; Hill, David J; Kowalczuk, Marek; Johnston, Brian; Adamus, Grazyna; Irorere, Victor; Radecka, Iza

2016-07-19

Polyhydroxyalkanoates (PHAs) are a group of bioplastics that have a wide range of applications. Extensive progress has been made in our understanding of PHAs' biosynthesis, and currently, it is possible to engineer bacterial strains to produce PHAs with desired properties. The substrates for the fermentative production of PHAs are primarily derived from food-based carbon sources, raising concerns over the sustainability of their production in terms of their impact on food prices. This paper gives an overview of the current carbon sources used for PHA production and the methods used to transform these sources into fermentable forms. This allows us to identify the opportunities and restraints linked to future sustainable PHA production. Hemicellulose hydrolysates and crude glycerol are identified as two promising carbon sources for a sustainable production of PHAs. Hemicellulose hydrolysates and crude glycerol can be produced on a large scale during various second generation biofuels' production. An integration of PHA production within a modern biorefinery is therefore proposed to produce biofuels and bioplastics simultaneously. This will create the potential to offset the production cost of biofuels and reduce the overall production cost of PHAs.

Degradation of multiwall carbon nanotubes by bacteria

International Nuclear Information System (INIS)

Zhang, Liwen; Petersen, Elijah J.; Habteselassie, Mussie Y.; Mao, Liang; Huang, Qingguo

2013-01-01

Understanding the environmental transformation of multiwall carbon nanotubes (MWCNTs) is important to their life cycle assessment and potential environmental impacts. We report that a bacterial community is capable of degrading 14 C-labeled MWCNTs into 14 CO 2 in the presence of an external carbon source via co-metabolism. Multiple intermediate products were detected, and genotypic characterization revealed three possible microbial degraders: Burkholderia kururiensis, Delftia acidovorans, and Stenotrophomonas maltophilia. This result suggests that microbe/MWCNTs interaction may impact the long-term fate of MWCNTs. Highlights: •Mineralization of MWCNTs by a bacterial community was observed. •The mineralization required an external carbon source. •Multiple intermediate products were identified in the MWCNT degrading culture. •Three bacterial species were found likely responsible for MWCNT degradation. -- The 14 C-labeled multiwall carbon nanotubes can be degraded to 14 CO 2 and other byproducts by a bacteria community under natural conditions

Selection of a carbon-14 fixation form

International Nuclear Information System (INIS)

Scheele, R.D.; Burger, L.L.

1982-09-01

This report summarizes work on the selection of a disposal form for carbon-14 produced during the production of nuclear power. Carbon compounds were screened on the basis of solubility, thermal stability, resistance to oxidation, cost and availability, compatibility with the selected disposal matrix, leach resistance when incorporated in concrete, and compatibility with capture technologies. Carbonates are the products of the various technologies presently considered for carbon-14 capture. The alkaline earth carbonates exhibit the greatest thermal stabilities, lowest solubilities, lowest raw material cost, and greatest raw material availabilities. When reactions with cement and its impurities are considered, calcium and strontium carbonates are the only alkaline earth carbonates resistant to hydrolysis and reaction with sulfate. Leaching tests of barium, calcium, lead, potassium, and strontium carbonates in concrete showed calcium carbonate concrete to be slightly superior to the other alkaline earth carbonates, and greatly superior to a soluble carbonate, potassium carbonate, and lead carbonate. None of the additives to the concrete reduced the carbonate leaching. Acidic CO 2 -containing waters were found to greatly increase carbonate leaching from concrete. Sea water was found to leach less carbon from carbonate concretes than either distilled water or Columbia River water, which showed nearly equivalent leaching. Based on our work, calcium, barium, and strontium carbonates in concrete are the most suitable waste forms for carbon-14, with calcium carbonate concrete slightly superior to the others. If the waste form is to be exposed to natural waters, sea water will have the lowest leach rate. 6 figures, 7 tables

Factors for Microbial Carbon Sources in Organic and Mineral Soils from Eastern United States Deciduous Forests

Energy Technology Data Exchange (ETDEWEB)

Stitt, Caroline R. [Mills College, Oakland, CA (United States)

2013-09-16

Forest soils represent a large portion of global terrestrial carbon; however, which soil carbon sources are used by soil microbes and respired as carbon dioxide (CO2) is not well known. This study will focus on characterizing microbial carbon sources from organic and mineral soils from four eastern United States deciduous forests using a unique radiocarbon (14C) tracer. Results from the dark incubation of organic and mineral soils are heavily influenced by site characteristics when incubated at optimal microbial activity temperature. Sites with considerable differences in temperature, texture, and location differ in carbon source attribution, indicating that site characteristics play a role in soil respiration.

Synthesis of carbon-13 and carbon-14 labeled paldimycin tri-sodium salt

International Nuclear Information System (INIS)

Hsi, R.S.P.; Witz, D.F.; Visser, J.; Stolle, W.T.; Ditto, C.L.

1989-01-01

Carbon-14 labeled paldimycin trisodium salt was prepared by addition of N-acetyl-L-cysteine to [ 14 C]paulomycin, the radioactive antibiotic produced by fermentation of Streptomyces paulus in the presence of L-methionine labeled with carbon-14 in the S-methyl group. Carbon-13 nuclear magnetic resonance (NMR) spectra of paulomycin produced when the fermentation was carried out in the presence of L-[S-methyl- 13 C]methionine showed that the isotope incorporation had occurred specifically at the methoxy group of ring C, i.e., the 2-deoxy sugar portion of paulomycin. With sustained slow feed of labeled precursors during the optimum antibiotic production period, carbon-14 isotope yields of up to 17.5% with specific activity of up to 11.4 μCi per milligram of paulomycin, and carbon-13 isotope yields of up to 24% with 17-fold isotope enrichment over natural abundance, were achieved. (author)

Carbon-14 in tree rings

International Nuclear Information System (INIS)

Cain, W.F.; Suess, H.E.

1976-01-01

In order to investigate how reliably the carbon 14 content of tree rings reflects that of atmospheric carbon dioxide, two types of determinations were carried out: (1) carbon 14 determinations in annual rings from the beginning of this century until 1974 and (2) carbon 14 determinations in synchronous wood from the North American bristlecone pine and from European oak trees, dendrochronologically dated to have grown in the third and fourth century B.C. The first series of measurements showed that bomb-produced radiocarbon was incorporated in wood at a time when it was converted from sapwood to heartwood, whenever radiocarbon from bomb testing was present in the atmosphere. The second series showed that wood more than 2000 years old and grown on two different continents at different altitudes had, within the limits of experimental error, the same radiocarbon content. This work and other experimental evidence, obtained in part by other laboratories, show that tree rings reflect the average radiocarbon content of global atmospheric carbon dioxide accurately within several parts per mil. In rare cases, deviations of up to 10 parts per thousand may be possible. This means that a typical single radiocarbon date for wood or charcoal possesses an intrinsic uncertainty (viz., an estimated ''one-sigma error'' in addition to all the other errors) of the order of +-50 years. This intrinsic uncertainty is independent of the absolute age of the sample. More accurate dates can, in principle, be obtained by the so-called method of ''wiggle matching.''

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

Science.gov (United States)

Feng, Xiaojuan; Gustafsson, Örjan; Holmes, R. Max; Vonk, Jorien E.; van 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.

Revised accident source terms for light-water reactors

Energy Technology Data Exchange (ETDEWEB)

Soffer, L. [Nuclear Regulatory Commission, Washington, DC (United States)

1995-02-01

This paper presents revised accident source terms for light-water reactors incorporating the severe accident research insights gained in this area over the last 15 years. Current LWR reactor accident source terms used for licensing date from 1962 and are contained in Regulatory Guides 1.3 and 1.4. These specify that 100% of the core inventory of noble gases and 25% of the iodine fission products are assumed to be instantaneously available for release from the containment. The chemical form of the iodine fission products is also assumed to be predominantly elemental iodine. These assumptions have strongly affected present nuclear air cleaning requirements by emphasizing rapid actuation of spray systems and filtration systems optimized to retain elemental iodine. A proposed revision of reactor accident source terms and some im implications for nuclear air cleaning requirements was presented at the 22nd DOE/NRC Nuclear Air Cleaning Conference. A draft report was issued by the NRC for comment in July 1992. Extensive comments were received, with the most significant comments involving (a) release fractions for both volatile and non-volatile species in the early in-vessel release phase, (b) gap release fractions of the noble gases, iodine and cesium, and (c) the timing and duration for the release phases. The final source term report is expected to be issued in late 1994. Although the revised source terms are intended primarily for future plants, current nuclear power plants may request use of revised accident source term insights as well in licensing. This paper emphasizes additional information obtained since the 22nd Conference, including studies on fission product removal mechanisms, results obtained from improved severe accident code calculations and resolution of major comments, and their impact upon the revised accident source terms. Revised accident source terms for both BWRS and PWRS are presented.

Continuous fermentation of food waste leachate for the production of volatile fatty acids and potential as a denitrification carbon source.

Science.gov (United States)

Kim, Hakchan; Kim, Jaai; Shin, Seung Gu; Hwang, Seokhwan; Lee, Changsoo

2016-05-01

This study investigated the simultaneous effects of hydraulic retention time (HRT) and pH on the continuous production of VFAs from food waste leachate using response surface analysis. The response surface approximations (R(2)=0.895, p<0.05) revealed that pH has a dominant effect on the specific VFA production (PTVFA) within the explored space (1-4-day HRT, pH 4.5-6.5). The estimated maximum PTVFA was 0.26g total VFAs/g CODf at 2.14-day HRT and pH 6.44, and the approximation was experimentally validated by running triplicate reactors under the estimated optimum conditions. The mixture of the filtrates recovered from these reactors was tested as a denitrification carbon source and demonstrated superior performance in terms of reaction rate and lag length relative to other chemicals, including acetate and methanol. The overall results provide helpful information for better design and control of continuous fermentation for producing waste-derived VFAs, an alternative carbon source for denitrification. Copyright © 2016 Elsevier Ltd. All rights reserved.

Distribution of carbon-14 assimilated by wheat awns

International Nuclear Information System (INIS)

Olugbemi, L.B.

1978-01-01

The pattern of distribution of carbon assimilated by awns was investigated in two lines of Triticum aestivum. Single awns on basal florets of spikelets in the central part of the ear were dosed with 14 C0 2 . Five days after dosing, 99% of the carbon-14 recovered was in the spikelet bearing the awn. Of the carbon-14 exported from the treated awn 57% went to the grain of the first floret, 1% to the second, 28% to the third and 7% to the fourth. (author)

The use of barytocalcite for carbon 14 immobilization: One-year leaching behavior

Energy Technology Data Exchange (ETDEWEB)

Massoni, Nicolas, E-mail: nicolas.massoni@cea.fr; Marcou, Céline; Rosen, Jérémy; Jollivet, Patrick

2014-11-15

The spent nuclear fuel reprocessing process is one of the anthropogenic sources of carbon-14, and since this element is highly mobile in the geosphere, its sequestration is necessary. Several phases and industrial solutions to immobilize this radionuclide have been studied, including the barytocalcite phase BaCa(CO{sub 3}){sub 2} at 8.08 wt.% of C, which has many advantages such as its low specific volume of carbon. Recently, different options to synthesize this phase have been reported. Here we report on the aqueous durability of barytocalcite, studied for one year with pure water at 30 °C, in order to complete the behavior studies. Unexpected leaching behavior was encountered: it had been supposed that barytocalcite would only leach slowly, but after 1 year, it was no longer present. It appears that its simple CaCO{sub 3} and BaCO{sub 3} constituents precipitated, though the overall carbon loss was low during the period studied. This research gives a new insight into the behavior of this phase regarding carbon-14 immobilization.

Carbon-14 production in nuclear reactors

International Nuclear Information System (INIS)

Davis, W. Jr.

1977-01-01

The radioactive nuclide 14 C is formed in all nuclear reactors due to absorption of neutrons by carbon, nitrogen, or oxygen. These may be present as components of the fuel, moderator, or structural hardware, or they may be present as impurities. Most of the 14 C formed in the fuels or in the graphite of HTGRs will be converted to a gaseous form at the fuel reprocessing plant, primarily as carbon dioxide; this will be released to the environment unless special equipment is installed to collect it and convert it to a solid for essentially permanent storage. If the 14 C is released as carbon dioxide or in any other chemical form, it will enter the biosphere, be inhaled or ingested as food by nearly all living organisms including man, and will thus contribute to the radiation burden of these organisms. Detailed estimates are presented of the amounts of 14 C formed in LWRs, HTGR, and LMFBR with emphasis on those pathways that are likely to lead to the release of this nuclide, either at the reactor site or at the fuel reprocessing plant. 83 references

Carbon allocation, source-sink relations and plant growth: do we need to revise our carbon centric concepts?

Science.gov (United States)

Körner, Christian

2014-05-01

Since the discovery that plants 'eat air' 215 years ago, carbon supply was considered the largely unquestioned top driver of plant growth. The ease at which CO2 uptake (C source activity) can be measured, and the elegant algorithms that describe the responses of photosynthesis to light, temperature and CO2 concentration, explain why carbon driven growth and productivity became the starting point of all process based vegetation models. Most of these models, nowadays adopt other environmental drivers, such as nutrient availability, as modulating co-controls, but the carbon priority is retained. Yet, if we believe in the basic rules of stoichometry of all life, there is an inevitable need of 25-30 elements other then carbon, oxygen and hydrogen to build a healthy plant body. Plants compete for most of these elements, and their availability (except for N) is finite per unit land area. Hence, by pure plausibility, it is a highly unlikely situation that carbon plays the rate limiting role of growth under natural conditions, except in deep shade or on exceptionally fertile soils. Furthermore, water shortage and low temperature, both act directly upon tissue formation (meristems) long before photosynthetic limitations come into play. Hence, plants will incorporate C only to the extent other environmental drivers permit. In the case of nutrients and mature ecosystems, this sink control of plant growth may be masked in the short term by a tight, almost closed nutrient cycle or by widening the C to other element ratio. Because source and sink activity must match in the long term, it is not possible to identify the hierarchy of growth controls without manipulating the environment. Dry matter allocation to C rich structures and reserves may provide some stoichimetric leeway or periodic escapes from the more fundamental, long-term environmental controls of growth and productivity. I will explain why carbon centric explanations of growth are limited or arrive at plausible answers

Dynamics of carbon 14 in soils: a review

International Nuclear Information System (INIS)

Tamponnet, C.

2004-01-01

In terrestrial ecosystems, soil is the main interface between atmosphere, hydrosphere, lithosphere and biosphere. Its interactions with carbon cycle are primordial. Information about carbon 14 dynamics in soils is quite dispersed and an up-to-date status is therefore presented in this paper. Carbon 14 dynamics in soils are governed by physical processes (soil structure, soil aggregation, soil erosion) chemical processes (sequestration by soil components either mineral or organic), and soil biological processes (soil microbes, soil fauna, soil biochemistry). The relative importance of such processes varied remarkably among the various biomes (tropical forest, temperate forest, boreal forest, tropical savannah, temperate pastures, deserts, tundra, marshlands, agro ecosystems) encountered in the terrestrial eco-sphere. Moreover, application for a simplified modelling of carbon 14 dynamics in soils is proposed. (author)

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

Science.gov (United States)

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

Fission-product source terms

International Nuclear Information System (INIS)

Lorenz, R.A.

1981-01-01

This presentation consists of a review of fission-product source terms for light water reactor (LWR) fuel. A source term is the quantity of fission products released under specified conditions that can be used to calculate the consequences of the release. The source term usually defines release from breached fuel-rod cladding but could also describe release from the primary coolant system, the reactor containment shell, or the site boundary. The source term would be different for each locality, and the chemical and physical forms of the fission products could also differ

An integrated approach to geological disposal of UK wastes containing carbon-14

International Nuclear Information System (INIS)

Vines, Sarah; Lever, David

2013-01-01

. Initially, the project team has undertaken a six month programme of work to examine the current understanding of these aspects and has captured this in the Phase 1 report [ii], in a modelling basis spreadsheet and in scoping assessments, which help us better understand the potential significance of carbon-14. Using the current modelling basis, but ignoring any potential benefits from the geosphere in retarding or preventing gas from reaching the surface, the calculated release of carbon- 14 is dominated by: corrosion of irradiated reactive metals (in the operational and early post-closure time frame); corrosion of irradiated stainless steel and leaching of irradiated graphite (in the longer term). The Phase 1 work has shown that there is considerable scope for reducing the calculated radiological consequence for these wastes and a roadmap has been developed for a second Phase of work. (authors)

An integrated approach to geological disposal of UK wastes containing carbon-14

Energy Technology Data Exchange (ETDEWEB)

Vines, Sarah [Nuclear Decommissioning Authority, Harwell, Oxfordshire (United Kingdom); Lever, David [AMEC, Harwell, Oxfordshire (United Kingdom)

2013-07-01

. Initially, the project team has undertaken a six month programme of work to examine the current understanding of these aspects and has captured this in the Phase 1 report [ii], in a modelling basis spreadsheet and in scoping assessments, which help us better understand the potential significance of carbon-14. Using the current modelling basis, but ignoring any potential benefits from the geosphere in retarding or preventing gas from reaching the surface, the calculated release of carbon- 14 is dominated by: corrosion of irradiated reactive metals (in the operational and early post-closure time frame); corrosion of irradiated stainless steel and leaching of irradiated graphite (in the longer term). The Phase 1 work has shown that there is considerable scope for reducing the calculated radiological consequence for these wastes and a roadmap has been developed for a second Phase of work. (authors)

Implication of using different carbon sources for denitrification in wastewater treatments.

Science.gov (United States)

Cherchi, Carla; Onnis-Hayden, Annalisa; El-Shawabkeh, Ibrahim; Gu, April Z

2009-08-01

Application of external carbon sources for denitrification becomes necessary for wastewater treatment plants that have to meet very stringent effluent nitrogen limits (e.g., 3 to 5 mgTN/L). In this study, we evaluated and compared three carbon sources--MicroC (Environmental Operating Solutions, Bourne, Massachusetts), methanol, and acetate-in terms of their denitrification rates and kinetics, effect on overall nitrogen removal performance, and microbial community structure of carbon-specific denitrifying enrichments. Denitrification rates and kinetics were determined with both acclimated and non-acclimated biomass, obtained from laboratory-scale sequencing batch reactor systems or full-scale plants. The results demonstrate the feasibility of the use of MicroC for denitrification processes, with maximum denitrification rates (k(dmax)) of 6.4 mgN/gVSSh and an observed yield of 0.36 mgVSS/mgCOD. Comparable maximum nitrate uptake rates were found with methanol, while acetate showed a maximum denitrification rate nearly twice as high as the others. The maximum growth rates measured at 20 degrees C for MicroC and methanol were 3.7 and 1.2 day(-1), respectively. The implications resulting from the differences in the denitrification rates and kinetics of different carbon sources on the full-scale nitrogen removal performance, under various configurations and operational conditions, were assessed using Biowin (EnviroSim Associates, Ltd., Flamborough, Ontario, Canada) simulations for both pre- and post-denitrification systems. Examination of microbial population structures using Automated Ribosomal Intergenic Spacer Analysis (ARISA) throughout the study period showed dynamic temporal changes and distinct microbial community structures of different carbon-specific denitrifying cultures. The ability of a specific carbon-acclimated denitrifying population to instantly use other carbon source also was investigated, and the chemical-structure-associated behavior patterns observed

Fate of gaseous tritium and carbon-14 released from buried low-level radioactive waste

International Nuclear Information System (INIS)

Striegl, R.G.

1988-01-01

Microbial decomposition, chemical degradation, and volatilization of buried low-level radioactive waste results in the release of gases containing tritium ( 3 H) and carbon-14 ( 14 C) to the surrounding environment. Water vapor, carbon dioxide, and methane that contain 3 H or 14 C are primary products of microbial decomposition of the waste. Depending on the composition of the waste source, chemical degradation and volatilization of waste also may result in the production of a variety of radioactive gases and organic vapors. Movement of the gases in materials that surround waste trenches is affected by physical, geochemical, and biological mechanisms including sorption, gas-water-mineral reactions, isotopic dilution, microbial consumption, and bioaccumulation. These mechanisms either may transfer 3 H and 14 C to solids and infiltrating water or may result in the accumulation of the radionuclides in plant or animal tissue. Gaseous 3 H or 14 C that is not transferred to other forms is ultimately released to the atmosphere

Biotechnological Production of Docosahexaenoic Acid Using Aurantiochytrium limacinum: Carbon Sources Comparison And Growth Characterization

Directory of Open Access Journals (Sweden)

Sergi Abad

2015-12-01

Full Text Available Aurantiochytrium limacinum, a marine heterotrophic protist/microalga has shown interesting yields of docosahexaenoic acid (DHA when cultured with different carbon sources: glucose, pure and crude glycerol. A complete study in a lab-scale fermenter allowed for the characterization and comparison of the growth kinetic parameters corresponding to each carbon source. Artificial Marine Medium (AMM with glucose, pure and crude glycerol offered similar biomass yields. The net growth rates (0.10–0.12 h−1, biomass (0.7–0.8 g cells/g Substrate and product (0.14–0.15 g DHA/g cells yields, as well as DHA productivity were similar using the three carbon sources. Viable potential applications to valorize crude glycerol are envisioned to avoid an environmental problem due to the excess of byproduct.

Sources of C-14 generation and associated doses

International Nuclear Information System (INIS)

Amado, Valeria A.; Biaggio, Alfredo L.; Canoba, Analia C.; Curti, Adriana R.

2009-01-01

C-14 is a radioactive isotope of C with a half-life of 5700 years that decays to N-14 by emission of beta radiation. It is naturally produced in the upper atmosphere by cosmic ray neutrons via the (n;p) reaction over N-14. Anthropogenic C-14 has been generated in the past by atmospheric nuclear weapon tests and it is currently produced during the operation of nuclear reactors. Once released this radionuclide behaves in the biosphere as the standard carbon cycle. Since the beginning of the industrial period the relationship Carbon-14/Stable Carbon has changed continuously, and so the dose incurred by the world population. In this paper the main anthropogenic activities that modified such relationship are presented and analyzed: the Suess effect and the generation of nuclear energy. It is concluded that the current trend of reduction of the total dose due to C-14 will continue during the next decades. Finally it is indicated that in order to prevent an excessive accumulation of this radionuclide in the biosphere, actions should be collectively implemented to be effective. (author) [es

The management of carbon-14 in Canadian nuclear facilities

International Nuclear Information System (INIS)

1995-07-01

In Canada, Derived Emission Limits (DELs) for the release of radionuclides from nuclear facilities are set to ensure that the dose to a member of a critical group from one year's release does not exceed the limit on annual dose to a member of the public set by the Atomic Energy Control Regulations. The Advisory Committee on Radiological Protection (ACRP) has expressed concerns as to whether this procedure provides adequate protection to members of the public, including future generations, for certain radionuclides such as a carbon-14 ( 14 C), which can accumulate in the environment and which can be dispersed, through environmental processes, beyond the local region where the critical group is assumed to live. The ACRP subsequently established a Working Group to review the production, release, environmental levels, and waste management of 14 C arising in CANDU power reactors. The ACRP recommendations resulting from this review can be summarized as · Given the current levels of emissions from CANDU nuclear power stations resulting from the use of a carbon dioxide annulus gas and the limitations in the calculation and use of collective dose, the ACRP sees no need for and additional collective dose limit to be applied to these sources. · The AECB should require licensees of power reactors and waste management sites to provide an annual inventory of 14 C held within reactor buildings and waste management sites; to provide information on the stability of the ion exchange resins and their continuing ability to retain the 14 C; to demonstrate on an ongoing basis that releases of 14 C are maintained at a small fraction of the emission limits; and to report annually the critical group and local collective doses arising from releases of 14 C. 61 refs., 25 tabs., 4 figs

7 CFR 1000.14 - Other source milk.

Science.gov (United States)

2010-01-01

... 7 Agriculture 9 2010-01-01 2009-01-01 true Other source milk. 1000.14 Section 1000.14 Agriculture... and Orders; Milk), DEPARTMENT OF AGRICULTURE GENERAL PROVISIONS OF FEDERAL MILK MARKETING ORDERS Definitions § 1000.14 Other source milk. Other source milk means all skim milk and butterfat contained in or...

Ligninolytic Activity of Ganoderma strains on Different Carbon Sources

Directory of Open Access Journals (Sweden)

TYPUK ARTININGSIH

2006-10-01

Full Text Available Lignin is a phenylpropanoid polymers with only few carbon bonds might be hydrolized. Due to its complexity, lignin is particularly difficult to decompose. Ganoderma is one of white rot fungi capable of lignin degradation. The ligninolytic of several species Ganoderma growing under different carbon sources was studied under controlled conditions which P. chrysosporium was used as standard comparison.Three types of ligninolytic, namely LiP, MnP, and laccase were assessed quantitatively and qualitatively. Ratio between clear zone and diameter of fungal colony was used for measuring specific activity qualitatively.Four sspecies of Ganoderma showed positive ligninolytic qualitatively that G. lucidum KT2-32 gave the highest ligninolytic. Activity of LiP and MnP in different carbon sources was consistently resulted by G. lucidum KT2-32, while the highest activity of laccase was shown by G. ochrolaccatum SA2-14. Medium of Indulin AT affected production of protein extracellular and induced ligninolytic. Glucose, BMC, and pine sawdust did not affect the activity of ligninolytic. The specific activity of Ganoderma species was found to be higher than the one of P. chrysosporium.

7 CFR 1001.14 - Other source milk.

Science.gov (United States)

2010-01-01

... 7 Agriculture 9 2010-01-01 2009-01-01 true Other source milk. 1001.14 Section 1001.14 Agriculture... and Orders; Milk), DEPARTMENT OF AGRICULTURE MILK IN THE NORTHEAST MARKETING AREA Order Regulating Handling Definitions § 1001.14 Other source milk. See § 1000.14. ...

7 CFR 1032.14 - Other source milk.

Science.gov (United States)

2010-01-01

... 7 Agriculture 9 2010-01-01 2009-01-01 true Other source milk. 1032.14 Section 1032.14 Agriculture... and Orders; Milk), DEPARTMENT OF AGRICULTURE MILK IN THE CENTRAL MARKETING AREA Order Regulating Handling Definitions § 1032.14 Other source milk. See § 1000.14. ...

7 CFR 1006.14 - Other source milk.

Science.gov (United States)

2010-01-01

... 7 Agriculture 9 2010-01-01 2009-01-01 true Other source milk. 1006.14 Section 1006.14 Agriculture... and Orders; Milk), DEPARTMENT OF AGRICULTURE MILK IN THE FLORIDA MARKETING AREA Order Regulating Handling Definitions § 1006.14 Other source milk. See § 1000.14. ...

7 CFR 1126.14 - Other source milk.

Science.gov (United States)

2010-01-01

... 7 Agriculture 9 2010-01-01 2009-01-01 true Other source milk. 1126.14 Section 1126.14 Agriculture... and Orders; Milk), DEPARTMENT OF AGRICULTURE MILK IN THE SOUTHWEST MARKETING AREA Order Regulating Handling Definitions § 1126.14 Other source milk. See § 1000.14. ...

7 CFR 1033.14 - Other source milk.

Science.gov (United States)

2010-01-01

... 7 Agriculture 9 2010-01-01 2009-01-01 true Other source milk. 1033.14 Section 1033.14 Agriculture... and Orders; Milk), DEPARTMENT OF AGRICULTURE MILK IN THE MIDEAST MARKETING AREA Order Regulating Handling Definitions § 1033.14 Other source milk. See § 1000.14. ...

7 CFR 1007.14 - Other source milk.

Science.gov (United States)

2010-01-01

... 7 Agriculture 9 2010-01-01 2009-01-01 true Other source milk. 1007.14 Section 1007.14 Agriculture... and Orders; Milk), DEPARTMENT OF AGRICULTURE MILK IN THE SOUTHEAST MARKETING AREA Order Regulating Handling Definitions § 1007.14 Other source milk. See § 1000.14. ...

7 CFR 1005.14 - Other source milk.

Science.gov (United States)

2010-01-01

... 7 Agriculture 9 2010-01-01 2009-01-01 true Other source milk. 1005.14 Section 1005.14 Agriculture... and Orders; Milk), DEPARTMENT OF AGRICULTURE MILK IN THE APPALACHIAN MARKETING AREA Order Regulating Handling Definitions § 1005.14 Other source milk. See § 1000.14. ...

7 CFR 1131.14 - Other source milk.

Science.gov (United States)

2010-01-01

... 7 Agriculture 9 2010-01-01 2009-01-01 true Other source milk. 1131.14 Section 1131.14 Agriculture... and Orders; Milk), DEPARTMENT OF AGRICULTURE MILK IN THE ARIZONA MARKETING AREA Order Regulating Handling Definitions § 1131.14 Other source milk. See § 1000.14. ...

Dual labelling of Lobuprofen with tritium and carbon-14

International Nuclear Information System (INIS)

Santamaria, J.; Rivera, P.; Esteban, M.; Martin, J.L.; Carretero, J.M.

1988-01-01

Dual labelling of Lobuprofen with tritium and carbon-14 was performed. The synthesis between 2-(4-isobutylphenyl)propionic acid (Ibuprofen), randomly labelled with tritium, and 2-[4-(3-chlorophenyl)-1-piperazinyl]ethanol (Cl-Alkanol) labelled with carbon-14 in the piperazine ring was achieved. Prior to this synthesis, the [ 14 C]Cl-Alkanol was obtained using 2-amino-[2- 14 C]ethanol as a precursor. (author)

7 CFR 1030.14 - Other source milk.

Science.gov (United States)

2010-01-01

... 7 Agriculture 9 2010-01-01 2009-01-01 true Other source milk. 1030.14 Section 1030.14 Agriculture... and Orders; Milk), DEPARTMENT OF AGRICULTURE MILK IN THE UPPER MIDWEST MARKETING AREA Order Regulating Handling Definitions § 1030.14 Other source milk. See § 1000.14. ...

7 CFR 1124.14 - Other source milk.

Science.gov (United States)

2010-01-01

... 7 Agriculture 9 2010-01-01 2009-01-01 true Other source milk. 1124.14 Section 1124.14 Agriculture... and Orders; Milk), DEPARTMENT OF AGRICULTURE MILK IN THE PACIFIC NORTHWEST MARKETING AREA Order Regulating Handling Definitions § 1124.14 Other source milk. See § 1000.14. ...

Online coupling of pure O_2 thermo-optical methods – "1"4C AMS for source apportionment of carbonaceous aerosols

International Nuclear Information System (INIS)

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

2015-01-01

This paper reports on novel separation methods developed for the direct determination of "1"4C 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 CO_2 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 CO_2 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 "1"4C aerosol source apportionment.

LDEO Carbon 14 Data from Selected Sea floor Cores

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Carbon-14 data in this file were compiled by W.F. Ruddiman and staff at the Lamont-Doherty Earth Observatory of Columbia University. Data include 974 carbon-14 dates...

Source attribution of black carbon in Arctic snow.

Science.gov (United States)

Hegg, Dean A; Warren, Stephen G; Grenfell, Thomas C; Doherty, Sarah J; Larson, Timothy V; Clarke, Antony D

2009-06-01

Snow samples obtained at 36 sites in Alaska, Canada, Greenland, Russia, and the Arctic Ocean in early 2007 were analyzed for light-absorbing aerosol concentration together with a suite of associated chemical species. The light absorption data, interpreted as black carbon concentrations, and other chemical data were input into the EPA PMF 1.1 receptor model to explore the sources for black carbon in the snow. The analysis found four factors or sources: two distinct biomass burning sources, a pollution source, and a marine source. The first three of these were responsible for essentially all of the black carbon, with the two biomass sources (encompassing both open and closed combustion) together accounting for >90% of the black carbon.

Carbonates in leaching reactions in context of {sup 14}C dating

Energy Technology Data Exchange (ETDEWEB)

Michalska, Danuta, E-mail: danamich@amu.edu.pl [Institute of Geology, Faculty of Geographical and Geological Sciences, Adam Mickiewicz University, ul. Makow Polnych 16, 61-606 Poznan (Poland); Czernik, Justyna, E-mail: justyna.czernik@gmail.com [Poznań Radiocarbon Laboratory, ul. Rubież 46, 61-612 Poznań (Poland)

2015-10-15

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 {sup 14}C 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

Carbonates in leaching reactions in context of "1"4C dating

International Nuclear Information System (INIS)

Michalska, Danuta; Czernik, Justyna

2015-01-01

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 "1"4C 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

A probabilistic analysis of cumulative carbon emissions and long-term planetary warming

International Nuclear Information System (INIS)

Fyke, Jeremy; Matthews, H Damon

2015-01-01

Efforts to mitigate and adapt to long-term climate change could benefit greatly from probabilistic estimates of cumulative carbon emissions due to fossil fuel burning and resulting CO 2 -induced planetary warming. Here we demonstrate the use of a reduced-form model to project these variables. We performed simulations using a large-ensemble framework with parametric uncertainty sampled to produce distributions of future cumulative emissions and consequent planetary warming. A hind-cast ensemble of simulations captured 1980–2012 historical CO 2 emissions trends and an ensemble of future projection simulations generated a distribution of emission scenarios that qualitatively resembled the suite of Representative and Extended Concentration Pathways. The resulting cumulative carbon emission and temperature change distributions are characterized by 5–95th percentile ranges of 0.96–4.9 teratonnes C (Tt C) and 1.4 °C–8.5 °C, respectively, with 50th percentiles at 3.1 Tt C and 4.7 °C. Within the wide range of policy-related parameter combinations that produced these distributions, we found that low-emission simulations were characterized by both high carbon prices and low costs of non-fossil fuel energy sources, suggesting the importance of these two policy levers in particular for avoiding dangerous levels of climate warming. With this analysis we demonstrate a probabilistic approach to the challenge of identifying strategies for limiting cumulative carbon emissions and assessing likelihoods of surpassing dangerous temperature thresholds. (letter)

Carbon-14 geochemistry at the Savannah River Site

International Nuclear Information System (INIS)

Roberts, Kimberly A.; Kaplan, Daniel I.

2013-01-01

Carbon-14 is among the key radionuclides driving risk at the E-Area Low-Level Waste Disposal Facility on the Savannah River Site (SRS). Much of this calculated risk is believed to be the result of having to make conservative assumptions in risk calculations because of the lack of site-specific data. The original geochemical data package (Kaplan 2006) recommended that performance assessments and composite analyses for the SRS assume that 14 C did not sorbed to sediments or cementitious materials, i.e., that C-14 K d value (solid:liquid concentration ratio) be set to 0 mL/g (Kaplan 2006). This recommendation was based primarily on the fact that no site-specific experimental work was available and the assumption that the interaction of anionic 14 C as CO 2 2- ) with similarly charged sediments or cementitious materials would be minimal. When used in reactive transport equations, the 0 mL/g Kd value results in 14 C not interacting with the solid phase and moving quickly through the porous media at the same rate as water. The objective of this study was to quantify and understand how aqueous 14 C, as dissolved carbonate, sorbs to and desorbs from SRS sediments and cementitious materials. Laboratory studies measuring the sorption of 14 C, added as a carbonate, showed unequivocally that 14 C-carbonate K d values were not equal to 0 mL/g for any of the solid phases tested, but they required several months to come to steady state. After six months of contact, the apparent K d values for a clayey sediment was 3,000 mL/g, for a sandy sediment was 10 mL/g, for a 36-year-old concrete was 30,000 mL/g, and for a reducing grout was 40 mL/g. Furthermore, it was demonstrated that (ad)sorption rates were appreciably faster than desorption rates, indicating that a kinetic sorption model, as opposed to the steady-state K d model, may be a more accurate description of the 14 C-carbonate sorption process. A second study demonstrated that the 14 C-carbonate sorbed very strongly onto the

Optimising carbon and nitrogen sources for Azotobacter ...

African Journals Online (AJOL)

The present work deals with selecting and optimization of carbon and nitrogen sources for producing biomass from Azotobacter chroococcum. Four carbon sources (glucose, sucrose, manitol and sodium benzoate) and four nitrogen sources (yeast extract, meat extract, NH4Cl and (NH4)2SO4) were evaluated during the first ...

The fate of river organic carbon in coastal areas: A study in the Rhône River delta using multiple isotopic (δ13C, Δ14C) and organic tracers

Science.gov (United States)

Cathalot, C.; Rabouille, C.; Tisnérat-Laborde, N.; Toussaint, F.; Kerhervé, P.; Buscail, R.; Loftis, K.; Sun, M.-Y.; Tronczynski, J.; Azoury, S.; Lansard, B.; Treignier, C.; Pastor, L.; Tesi, T.

2013-10-01

A significant fraction of the global carbon flux to the ocean occurs in River-dominated Ocean Margins (RiOMar) although large uncertainties remain in the cycle of organic matter (OM) in these systems. In particular, the OM sources and residence time have not been well clarified. Surface (0-1 cm) and sub-surface (3-4 cm) sediments and water column particles (bottom and intermediate depth) from the Rhône River delta system were collected in June 2005 and in April 2007 for a multi-proxy study. Lignin phenols, black carbon (BC), proto-kerogen/BC mixture, polycyclic aromatic hydrocarbons (PAHs), carbon stable isotope (δ13COC), and radiocarbon measurements (Δ14COC) were carried out to characterize the source of sedimentary organic material and to address degradation and transport processes. The bulk OM in the prodelta sediment appears to have a predominantly modern terrigenous origin with a significant contribution of modern vascular C3 plant detritus (Δ14COC = 27.9‰, δ13COC = -27.4‰). In contrast, the adjacent continental shelf, below the river plume, seems to be dominated by aged OM (Δ14COC = -400‰, δ13COC = -24.2‰), and shows no evidence of dilution and/or replacement by freshly produced marine carbon. Our data suggest an important contribution of black carbon (50% of OC) in the continental shelf sediments. Selective degradation processes occur along the main dispersal sediment system, promoting the loss of a modern terrestrial OM but also proto-kerogen-like OM. In addition, we hypothesize that during the transport across the shelf, a long term resuspension/deposition loop induces efficient long term degradation processes able to rework such refractory-like material until the OC is protected by the mineral matrix of particles.

Investigations into the post-natal development of demethylating enzyme systems by determination of carbon dioxide 14 in the air exhaled by mice after applications of carbon 14 dimethyl amino-antipyrine

International Nuclear Information System (INIS)

Schmidt, H.

1982-01-01

Albino mice were subcutaneously injected with carbon 14 dimethyl aminopyrines, the methyl group of which can be metabolised in the organism into carbon dioxide 14. The following results were obtained: In the carbon dioxide 14 exhalation of neonate, young and adult animals after administration of carbon 14 aminopyrine, distinct differences were noted. The maximum of elimination via the lungs occurs after 20-30 minutes in grown-up mice, in neonates or young animals distinctly later (60-90 min). The carbon dioxide 14 exhalation was also measured after additional subcutaneous application of methrotrexate. In mice aged 8 and 10 days a distinct decrease in carbon dioxide 14 exhalation was found. By contrast, a rise in carbon dioxide 14 exhaled was found in mice aged 2 days. The orientating experiments with folic acid and carbon 14 dimethyl aminopyrine show that leucovorin leads to a distinct increase in carbon dioxide 14 exhalation during the first 30 minutes. As a cause of the different degrees of stimulation respectively inhibition of demethylation, different biochemical ways of formaldehyde formation are pointed out. One of these probably includes the folate-dependent reaction. (orig./MG) [de

Long-term trends of black carbon and sulphate aerosol in the Arctic: changes in atmospheric transport and source region emissions

Directory of Open Access Journals (Sweden)

D. Hirdman

2010-10-01

Full Text Available As a part of the IPY project POLARCAT (Polar Study using Aircraft, Remote Sensing, Surface Measurements and Models, of Climate, Chemistry, Aerosols and Transport and building on previous work (Hirdman et al., 2010, this paper studies the long-term trends of both atmospheric transport as well as equivalent black carbon (EBC and sulphate for the three Arctic stations Alert, Barrow and Zeppelin. We find a general downward trend in the measured EBC concentrations at all three stations, with a decrease of −2.1±0.4 ng m⁻³ yr⁻¹ (for the years 1989–2008 and −1.4±0.8 ng m⁻³ yr⁻¹ (2002–2009 at Alert and Zeppelin respectively. The decrease at Barrow is, however, not statistically significant. The measured sulphate concentrations show a decreasing trend at Alert and Zeppelin of −15±3 ng m⁻³ yr⁻¹ (1985–2006 and −1.3±1.2 ng m⁻³ yr⁻¹ (1990–2008 respectively, while there is no trend detectable at Barrow.

To reveal the contribution of different source regions on these trends, we used a cluster analysis of the output of the Lagrangian particle dispersion model FLEXPART run backward in time from the measurement stations. We have investigated to what extent variations in the atmospheric circulation, expressed as variations in the frequencies of the transport from four source regions with different emission rates, can explain the long-term trends in EBC and sulphate measured at these stations. We find that the long-term trend in the atmospheric circulation can only explain a minor fraction of the overall downward trend seen in the measurements of EBC (0.3–7.2% and sulphate (0.3–5.3% at the Arctic stations. The changes in emissions are dominant in explaining the trends. We find that the highest EBC and sulphate concentrations are associated with transport from Northern Eurasia and decreasing emissions in this region drive the

Online coupling of pure O{sub 2} thermo-optical methods – {sup 14}C AMS for source apportionment of carbonaceous aerosols

Energy Technology Data Exchange (ETDEWEB)

Agrios, Konstantinos [Department of Chemistry and Biochemistry, University of Bern, Bern (Switzerland); Oeschger Centre for Climate Change Research, University of Bern, Bern (Switzerland); Paul Scherrer Institute, Villigen (Switzerland); Salazar, Gary [Department of Chemistry and Biochemistry, University of Bern, Bern (Switzerland); Oeschger Centre for Climate Change Research, University of Bern, Bern (Switzerland); Zhang, Yan-Lin; Uglietti, Chiara [Department of Chemistry and Biochemistry, University of Bern, Bern (Switzerland); Oeschger Centre for Climate Change Research, University of Bern, Bern (Switzerland); Paul Scherrer Institute, Villigen (Switzerland); Battaglia, Michael [Department of Chemistry and Biochemistry, University of Bern, Bern (Switzerland); Oeschger Centre for Climate Change Research, University of Bern, Bern (Switzerland); Luginbühl, Marc [Department of Chemistry and Biochemistry, University of Bern, Bern (Switzerland); Ciobanu, Viorela Gabriela [Paul Scherrer Institute, Villigen (Switzerland); Vonwiller, Matthias [Department of Chemistry and Biochemistry, University of Bern, Bern (Switzerland); Oeschger Centre for Climate Change Research, University of Bern, Bern (Switzerland); Paul Scherrer Institute, Villigen (Switzerland); Szidat, Sönke, E-mail: szidat@dcb.unibe.ch [Department of Chemistry and Biochemistry, University of Bern, Bern (Switzerland); Oeschger Centre for Climate Change Research, University of Bern, Bern (Switzerland)

2015-10-15

This paper reports on novel separation methods developed for the direct determination of {sup 14}C 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 CO{sub 2} 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 CO{sub 2} 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 {sup 14}C aerosol source apportionment.

Long-term groundwater contamination after source removal—The role of sorbed carbon and nitrogen on the rate of reoxygenation of a treated-wastewater plume on Cape Cod, MA, USA

Science.gov (United States)

Smith, Richard L.; Repert, Deborah A.; Barber, Larry B.; LeBlanc, Denis R.

2013-01-01

The consequences of groundwater contamination can remain long after a contaminant source has been removed. Documentation of natural aquifer recoveries and empirical tools to predict recovery time frames and associated geochemical changes are generally lacking. This study characterized the long-term natural attenuation of a groundwater contaminant plume in a sand and gravel aquifer on Cape Cod, Massachusetts, after the removal of the treated-wastewater source. Although concentrations of dissolved organic carbon (DOC) and other soluble constituents have decreased substantially in the 15 years since the source was removed, the core of the plume remains anoxic and has sharp redox gradients and elevated concentrations of nitrate and ammonium. Aquifer sediment was collected from near the former disposal site at several points in time and space along a 0.5-km-long transect extending downgradient from the disposal site and analyses of the sediment was correlated with changes in plume composition. Total sediment carbon content was generally low (rates in laboratory incubations, which ranged from 11.6 to 44.7 nmol (g dry wt)− 1 day− 1. Total water extractable organic carbon was groundwater velocity. This suggests that the total sorbed carbon pool is large relative to the rate of oxygen entrainment and will be impacting groundwater geochemistry for many decades. This has implications for long-term oxidation of reduced constituents, such as ammonium, that are being transported downgradient away from the infiltration beds toward surface and coastal discharge zones.

Design parameters and source terms: Volume 3, Source terms

International Nuclear Information System (INIS)

1987-10-01

The Design Parameters and Source Terms Document was prepared in accordance with DOE request and to provide data for the environmental impact study to be performed in the future for the Deaf Smith County, Texas site for a nuclear waste repository in salt. This document updates a previous unpublished report by Stearns Catalytic Corporation (SCC), entitled ''Design Parameters and Source Terms for a Two-Phase Repository in Salt,'' 1985, to the level of the Site Characterization Plan - Conceptual Design Report. The previous unpublished SCC Study identifies the data needs for the Environmental Assessment effort for seven possible Salt Repository sites. 11 refs., 9 tabs

Sources and transport of Δ14C in CO2 within the Mexico City Basin and vicinity

Directory of Open Access Journals (Sweden)

H. B. Singh

2009-07-01

Full Text Available Radiocarbon samples taken over Mexico City and the surrounding region during the MILAGRO field campaign in March 2006 exhibited an unexpected distribution: (1 relatively few samples (23% were below the North American free tropospheric background value (57±2‰ despite the fossil fuel emissions from one of the world's most highly polluted environments; and (2 frequent enrichment well above the background value was observed. Correlate source tracer species and air transport characteristics were examined to elucidate influences on the radiocarbon distribution. Our analysis suggests that a combination of radiocarbon sources biased the "regional radiocarbon background" above the North American value thereby decreasing the apparent fossil fuel signature. Likely sources include the release of 14C-enhanced carbon from bomb 14C sequestered in plant carbon pools via the ubiquitous biomass burning in the region as well as the direct release of radiocarbon as CO2 from other "hot" sources. Plausible perturbations from local point "hot" sources include the burning of hazardous waste in cement kilns; medical waste incineration; and emissions from the Laguna Verde Nuclear Power Plant. These observations provide insight into the use of Δ14CO2 to constrain fossil fuel emissions in the megacity environment, indicating that underestimation of the fossil fuel contribution to the CO2 flux is likely wherever biomass burning coexists with urban emissions and is unaccounted for as a source of the elevated CO2 observed above local background. Our findings increase the complexity required to quantify fossil fuel-derived CO2 in source-rich environments characteristic of megacities, and have implications for the use of Δ14CO2 observations in evaluating bottom-up emission inventories and their reliability as a tool for validating national emission claims of CO2 within the framework of the Kyoto Protocol.

Concentration of carbon-14 in plants

International Nuclear Information System (INIS)

1978-01-01

The carbon-14 survey program initiated 1960 to gather data on current levels of carbon-14 in environments. Plants essential oil and fermented alcohol were selected as sample materials. The carbon contained in these materials is fixed from atmospheric carbon dioxide by anabolism, so they well reflect the variation of carbon-14 in biosphere. Thymol; Thymol was obtained from the essential oil of Orthodon Japonicium Benth which was cultivated and harvested every year in the experimental field of NIRS and Chiba University. The methylation was carried out to eliminate the strong quenching action of the phenolic group of thymol. Eighteen grams of thymol methyl ether was used as liquid scintillator by adding 0.4% PPO and 0.01% POPOP. Menthol; Menthol was obtained from Mentha arvensis L which was cultivated in the east part of Hokkaido and prepared by Kitami Factory of Federation of Agricultural Cooperative Society of Hokkaido. The chemical conversion of menthol to p-cymene was carried out and used as liquid scintillator as same as above sample. Lemongrass oil; Lemongrass oil was obtained from Cymbopogon citratus Stapf which was cultivated in Izu Experimental Station of Medicinal Plants, National Institute of Hygienic Science located Minami-Izu, Shizuoka Pref. The p-cymene derived from Lemongrass oil was used as liquid scintillator. Alcohol; All sample of fermented alcohol were obtained from the Alcohol Factories of Ministry of Trade and Industry. Raw materials of alcohol were sweet potatos cultivated in several prefectures in Japan ''high test'' molasses and blackstrap molasses imported from several countries of Asia, South America and South Africa, crude alcohol imported from U.S.A., Argentina and Brazil. Mixed solvent of 10 ml sample alcohol and 10 ml toluene or p-xylene containing 0.8% PPO and 0.1% dimethyl POPOP was used as liquid scintillator. (author)

Study of a method of detection for natural carbon-14 using a liquid scintillator, recent variations in the natural radio-activity due to artificial carbon-14 (1963); Etude d'une methode de detection du carrons 14 naturel, utilisant un scintillateur liquide - variations recentes de l'activite naturelle dues au carbone 14 artificiel (1963)

Energy Technology Data Exchange (ETDEWEB)

Leger, C [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1963-06-15

Among the various natural isotopes of carbon, a radioactive isotope, carbon-14, is formed by the action of secondary neutrons from cosmic rays on nitrogen in the air. Until 1950, the concentration of this isotope in ordinary carbon underwent weak fluctuations of about 2-3 per cent. The exact measurement of this concentration 6 X 10{sup 12} Ci/gm of carbon, and of its fluctuations, are difficult and in the first part of this report a highly sensitive method is given using a liquid scintillator. Since 1950 this natural activity has shown large fluctuations because of the carbon-14 formed during nuclear explosions, and in the second part, the evolution in France of this specific activity of carbon in the atmosphere and biosphere is examined. In the last part is studied the local increase in carbon activity in the atmosphere around the Saclay site, an increase caused by the carbon-14 given off as C{sup 14}O{sub 2}, by the reactors cooled partially with exterior air. (author) [French] Parmi les differents isotopes naturels du carbone, un isotope radioactif, le carbone 14, est forme par l'action de neutrons secondaires due aux rayons cosmiques sir l'azote de l'air. Jusqu'en 1950, la concentration de cet isotope dans le carbone ordinaire est soumise a des fluctuations de faible amplitude, de l'ordre de 2 a 3 pour cent. Les mesures precises de cette concentration, 6. 10{sup -12} Ci/g de carbone, et de ses fluctuations sont delicates, et dans la premiere partie de ce rapport, on decrit une methode de detection a grande sensibilite utilisant un scintillateur liquide. Depuis 1950, cette activite naturelle subit des fluctuations importantes dues au carbone 14 forme lors des explosions nucleaires, et dans la seconde partie, on examine l'evolution en France de l'activite specifique du carbone de l'atmosphere et ce la biosphere. Dans la derniere partie, on etudie l'accroissement local de l'activite du carbone de l'air aux environs du site de Saclay, accroissement provoque par le

Black Carbon and Sulfate Aerosols in the Arctic: Long-term Trends, Radiative Impacts, and Source Attributions

Science.gov (United States)

Wang, H.; Zhang, R.; Yang, Y.; Smith, S.; Rasch, P. J.

2017-12-01

The Arctic has warmed dramatically in recent decades. As one of the important short-lived climate forcers, aerosols affect the Arctic radiative budget directly by interfering radiation and indirectly by modifying clouds. Light-absorbing particles (e.g., black carbon) in snow/ice can reduce the surface albedo. The direct radiative impact of aerosols on the Arctic climate can be either warming or cooling, depending on their composition and location, which can further alter the poleward heat transport. Anthropogenic emissions, especially, BC and SO2, have changed drastically in low/mid-latitude source regions in the past few decades. Arctic surface observations at some locations show that BC and sulfate aerosols had a decreasing trend in the recent decades. In order to understand the impact of long-term emission changes on aerosols and their radiative effects, we use the Community Earth System Model (CESM) equipped with an explicit BC and sulfur source-tagging technique to quantify the source-receptor relationships and decadal trends of Arctic sulfate and BC and to identify variations in their atmospheric transport pathways from lower latitudes. The simulation was conducted for 36 years (1979-2014) with prescribed sea surface temperatures and sea ice concentrations. To minimize potential biases in modeled large-scale circulations, wind fields in the simulation are nudged toward an atmospheric reanalysis dataset, while atmospheric constituents including water vapor, clouds, and aerosols are allowed to evolve according to the model physics. Both anthropogenic and open fire emissions came from the newly released CMIP6 datasets, which show strong regional trends in BC and SO2 emissions during the simulation time period. Results show that emissions from East Asia and South Asia together have the largest contributions to Arctic sulfate and BC concentrations in the upper troposphere, which have an increasing trend. The strong decrease in emissions from Europe, Russia and

Source contributions to atmospheric fine carbon particle concentrations

Science.gov (United States)

Andrew Gray, H.; Cass, Glen R.

A Lagrangian particle-in-cell air quality model has been developed that facilitates the study of source contributions to atmospheric fine elemental carbon and fine primary total carbon particle concentrations. Model performance was tested using spatially and temporally resolved emissions and air quality data gathered for this purpose in the Los Angeles area for the year 1982. It was shown that black elemental carbon (EC) particle concentrations in that city were dominated by emissions from diesel engines including both on-highway and off-highway applications. Fine primary total carbon particle concentrations (TC=EC+organic carbon) resulted from the accumulation of small increments from a great variety of emission source types including both gasoline and diesel powered highway vehicles, stationary source fuel oil and gas combustion, industrial processes, paved road dust, fireplaces, cigarettes and food cooking (e.g. charbroilers). Strategies for black elemental carbon particle concentration control will of necessity need to focus on diesel engines, while controls directed at total carbon particle concentrations will have to be diversified over a great many source types.

Regional cerebral blood flow after long-term exposure to carbon disulfide

International Nuclear Information System (INIS)

Aaserud, O.; Russell, D.; Nyberg-Hansen, R.; Joergensen, E.B.; Gjerstad, L.; Rootwelt, K.; Nakstad, P.; Hommeren, O.J.; Tvedt, B.

1992-01-01

Sixteen former rayon viscose workers were investigated four years after the exposure to carbon disulfide was discontinued. Median age was 58 years (range 43-65 years), median exposure time was 17 years (range 10-35 years). Encephalopathy was diagnosed in altogether 14 workers. To further explore pathophysiological mechanisms, cerebrovascular investigations were employed. Doppler ultrasound examination of the precerebral vessels in 15 workers showed a slight stenosis of the left internal carotid artery in one. Regional cerebral blood flow investigation (rCBF) with single photon emission computerized tomography (SPECT) with Xenon-133 gas was performed in 14. There was no significant difference from a control group. Regional side-to-side asymmetries beyond reference limits were demonstrated in eight workers. The abnormalities were modest, but may indicate a tendency toward focal blood flow disturbances in workers with long-term exposure to carbon disulfide. (au)

Biomarker and carbon isotope constraints (δ13C, Δ14C) on sources and cycling of particulate organic matter discharged by large Siberian rivers draining permafrost areas

International Nuclear Information System (INIS)

Winterfeld, Maria

2014-08-01

Circumpolar permafrost soils store about half of the global soil organic carbon pool. These huge amounts of organic matter (OM) could accumulate due to low temperatures and water saturated soil conditions over the course of millennia. Currently most of this OM remains frozen and therefore does not take part in the active carbon cycle, making permafrost soils a globally important carbon sink. Over the last decades mean annual air temperatures in the Arctic increased stronger than the global mean and this trend is projected to continue. As a result the permafrost carbon pool is under climate pressure possibly creating a positive climate feedback due to the thaw-induced release of greenhouse gases to the atmosphere. Arctic warming will lead to increased annual permafrost thaw depths and Arctic river runoff likely resulting in enhanced mobilization and export of old, previously frozen soil-derived OM. Consequently, the great arctic rivers play an important role in global biogeochemical cycles by connecting the large permafrost carbon pool of their hinterlands with the arctic shelf seas and the Arctic Ocean. The first part of this thesis deals with particulate organic matter (POM) from the Lena Delta and adjacent Buor Khaya Bay. The Lena River in central Siberia is one of the major pathways translocating terrestrial OM from its southernmost reaches near Lake Baikal to the coastal zone of the Laptev Sea. The permafrost soils from the Lena catchment area store huge amounts of pre-aged OM, which is expected to be remobilized due to climate warming. To characterize the composition and vegetation sources of OM discharged by the Lena River, the lignin phenol and carbon isotopic composition (δ 13 C and Δ 14 C) in total suspended matter (TSM) from surface waters, surface sediments from the Buor Khaya Bay along with soils from the Lena Delta's first (Holocene) and third terraces (Pleistocene ice complex) were analyzed. The lignin compositions of these samples are

The influence of different nitrogen and carbon sources on mycotoxin production in Alternaria alternata.

Science.gov (United States)

Brzonkalik, Katrin; Herrling, Tanja; Syldatk, Christoph; Neumann, Anke

2011-05-27

The aim of this study was to determine the influence of different carbon and nitrogen sources on the production of the mycotoxins alternariol (AOH), alternariol monomethyl ether (AME) and tenuazonic acid (TA) by Alternaria alternata at 28°C using a semi-synthetic medium (modified Czapek-Dox broth) supplemented with nitrogen and carbon sources. Additionally the effect of shaken and static cultivation on mycotoxin production was tested. Initial experiments showed a clear dependency between nitrogen depletion and mycotoxin production. To assess whether nitrogen limitation in general or the type of nitrogen source triggers the production, various nitrogen sources including several ammonium/nitrate salts and amino acids were tested. In static culture the production of AOH/AME can be enhanced greatly with phenylalanine whereas some nitrogen sources seem to inhibit the AOH/AME production completely. TA was not significantly affected by the choice of nitrogen source. In shaken culture the overall production of all mycotoxins was lower compared to static cultivation. Furthermore tests with a wide variety of carbon sources including monosaccharides, disaccharides, complex saccharides such as starch as well as glycerol and acetate were performed. In shaken culture AOH was produced when glucose, fructose, sucrose, acetate or mixtures of glucose/sucrose and glucose/acetate were used as carbon sources. AME production was not detected. The use of sodium acetate resulted in the highest AOH production. In static culture AOH production was also stimulated by acetate and the amount is comparable to shaken conditions. Under static conditions production of AOH was lower except when cultivated with acetate. In static cultivation 9 of 14 tested carbon sources induced mycotoxin production compared to 4 in shaken culture. This is the first study which analyses the influence of carbon and nitrogen sources in a semi-synthetic medium and assesses the effects of culture conditions on

Carbon budget of a marine phytoplankton-herbivore system with carbon-14 as a tracer

International Nuclear Information System (INIS)

Copping, A.E.; Lorenzen, C.J.

1980-01-01

Adult female and stage V Calanus pacificus were fed 14 C-labeled phytoplankton in the laboratory in the form of monospecific cultures and natural populations. A carbon budget was constructed by following the 14 C activity and the specific activity, over 48 h, in the phytoplankton, copepod, dissolved organic, dissolved inorganic, and fecal carbon compartments. The average incorporation of carbon into the copepod's body was 45% of the phytoplankton carbon available. Of the phytoplankton carbon, 27% appeared as dissolved organic carbon, 24% as dissolved inorganic carbon, and 3 to 4% in the form of fecal pellets. All of the tracer was recovered at the end of the experiments. The specific activity of the phytoplankton compartment was constant throughout each experiment. The other compartments had initial specific activities of zero, or close to zero, and increased throughout the experiment. In most experiments, the copepod specific activity equalled that of the phytoplankton at the end of 48 h, while the dissolved organic carbon, dissolved inorganic carbon, and fecal specific activities remained well below that of the phytoplankton

Carbonate as sputter target material for rapid {sup 14}C AMS

Energy Technology Data Exchange (ETDEWEB)

Longworth, Brett E., E-mail: blongworth@whoi.edu [Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA (United States); Robinson, Laura F. [Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA (United States); Roberts, Mark L.; Beaupre, Steven R.; Burke, Andrea [Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA (United States); Jenkins, William J. [Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA (United States)

2013-01-15

This paper describes a technique for measuring the {sup 14}C content of carbonate samples by producing C{sup -} 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.

Sources and delivery of carbon dioxide for enhanced oil recovery. Final report, October 1977--December 1978

Energy Technology Data Exchange (ETDEWEB)

Hare, M.; Perlich, H.; Robinson, R.; Shah, M.; Zimmerman, F.

1978-12-01

Results are presented from a comprehensive study by Pullman Kellogg, with assistance from Gulf Universities Research Consortium (GURC) and National Cryo-Chemics Incorporated (NCI), of the carbon dioxide supply situation for miscible flooding operations to enhance oil recovery. A survey of carbon dioxide sources within the geographic areas of potential EOR are shown on four regional maps with the tabular data for each region to describe the sources in terms of quantity and quality. Evaluation of all the costs, such as purchase, production, processing, and transportation, associated with delivering the carbon dioxide from its source to its destination are presented. Specific cases to illustrate the use of the maps and cost charts generated in this study have been examined.

Carbon 14 and tritium radioactivity of alcohols

International Nuclear Information System (INIS)

Guerain, J.; Tourliere, S.

1975-01-01

The method of measuring carbon 14 radioactivity of alcohols has been perfected in order to establish the correct determination of synthetic alcohol added to fermentation alcohol. The specific carbon and tritium activity of alcohol of different origins have been determined for 1973 and 1974. The Suess effect and nuclear fall-out are observed [fr

Applications of environmental tritium and carbon-14 in water resources investigation in Taiyuan region China

International Nuclear Information System (INIS)

Cai Zuhuang; Shi Huixin

1988-01-01

To evaluate the influence of exploiting karst groundwater by 0.5-1 cubic metre per second by Gujiao Coal Mine on the discharge rate of the major Lancun spring, Jinci spring and Xizhang waterworks in the Taiyuan region, Shanxi Province, and to seek new sources of water to make up for this influence, we carried out systematic hydrogeological studies in this region from 1983 to 1986, including measurement of 180 data of tritium, 49 data of carbon-13, 20 data of carbon-14, as well as more than 2,000 chemical data. Isotopic and chemical data were interpreted and used to distinguish the groundwater system, to determine the mixing ratios of various groundwaters, to trace the movement of groundwater both inside each subsystem and from one subsystem to another. Groundwater ages at 13 sites in the studied region were obtained after correction for mixing with young water, correction for dilution by dead carbon, and correction for variation of initial carbon-14 concentration. The velocity of groundwater flow was determined on the basis of groundwater ages. (author). 3 figs, 5 tabs

Study of a method of detection for natural carbon-14 using a liquid scintillator, recent variations in the natural radio-activity due to artificial carbon-14 (1963); Etude d'une methode de detection du carrons 14 naturel, utilisant un scintillateur liquide - variations recentes de l'activite naturelle dues au carbone 14 artificiel (1963)

Energy Technology Data Exchange (ETDEWEB)

Leger, C. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1963-06-15

Among the various natural isotopes of carbon, a radioactive isotope, carbon-14, is formed by the action of secondary neutrons from cosmic rays on nitrogen in the air. Until 1950, the concentration of this isotope in ordinary carbon underwent weak fluctuations of about 2-3 per cent. The exact measurement of this concentration 6 X 10{sup 12} Ci/gm of carbon, and of its fluctuations, are difficult and in the first part of this report a highly sensitive method is given using a liquid scintillator. Since 1950 this natural activity has shown large fluctuations because of the carbon-14 formed during nuclear explosions, and in the second part, the evolution in France of this specific activity of carbon in the atmosphere and biosphere is examined. In the last part is studied the local increase in carbon activity in the atmosphere around the Saclay site, an increase caused by the carbon-14 given off as C{sup 14}O{sub 2}, by the reactors cooled partially with exterior air. (author) [French] Parmi les differents isotopes naturels du carbone, un isotope radioactif, le carbone 14, est forme par l'action de neutrons secondaires due aux rayons cosmiques sir l'azote de l'air. Jusqu'en 1950, la concentration de cet isotope dans le carbone ordinaire est soumise a des fluctuations de faible amplitude, de l'ordre de 2 a 3 pour cent. Les mesures precises de cette concentration, 6. 10{sup -12} Ci/g de carbone, et de ses fluctuations sont delicates, et dans la premiere partie de ce rapport, on decrit une methode de detection a grande sensibilite utilisant un scintillateur liquide. Depuis 1950, cette activite naturelle subit des fluctuations importantes dues au carbone 14 forme lors des explosions nucleaires, et dans la seconde partie, on examine l'evolution en France de l'activite specifique du carbone de l'atmosphere et ce la biosphere. Dans la derniere partie, on etudie l'accroissement local de l'activite du carbone de l'air aux

Effect of various carbon and nitrogen sources on cellulose synthesis ...

African Journals Online (AJOL)

The effect of various carbon and nitrogen sources on cellulose production by Acetobacter lovaniensis HBB5 was examined. In this study, glucose, fructose, sucrose and ethanol as carbon source and yeast extract, casein hydrolysate and ammonium sulphate as nitrogen source were used. Among the carbon sources, ...

Synthesis of carbon-14 labelled ethyl chloride

International Nuclear Information System (INIS)

Kanski, R.

1976-01-01

A new efficient method of synthesis of ethyl chloride (1,2- 14 C), based on the Ba 14 CO 3 and dry hydrogen chloride as starting materials has been developed and described. Addition of the hydrogen chloride to ethylene (1,2- 14 C), obtained from Ba 14 CO 3 , has been carried out in the presence of the AlCl 3 as catalyst. The outlined method leads to ethyl chloride (1,2- 14 C) of high specific activity. The radiochemical yield of the reaction based on the activity of barium carbonate used was 72%. (author)

Laboratory Experiments to Evaluate Matrix Diffusion of Dissolved Organic Carbon Carbon-14 in Southern Nevada Fractured-rock Aquifers

Energy Technology Data Exchange (ETDEWEB)

Hershey, Ronald L. [Nevada University, Reno, NV (United States). Desert Research Institute; Fereday, Wyatt [Nevada University, Reno, NV (United States). Desert Research Institute

2016-05-01

Dissolved inorganic carbon (DIC) carbon-14 (¹⁴C) is used to estimate groundwater ages by comparing the DIC ¹⁴C content in groundwater in the recharge area to the DIC ¹⁴C content in the downgradient sampling point. However, because of chemical reactions and physical processes between groundwater and aquifer rocks, the amount of DIC ¹⁴C in groundwater can change and result in ¹⁴C loss that is not because of radioactive decay. This loss of DIC ¹⁴C results in groundwater ages that are older than the actual groundwater ages. Alternatively, dissolved organic carbon (DOC) ¹⁴C in groundwater does not react chemically with aquifer rocks, so DOC ¹⁴C ages are generally younger than DIC ¹⁴C ages. In addition to chemical reactions, ¹⁴C ages may also be altered by the physical process of matrix diffusion. The net effect of a continuous loss of ¹⁴C to the aquifer matrix by matrix diffusion and then radioactive decay is that groundwater appears to be older than it actually is. Laboratory experiments were conducted to measure matrix diffusion coefficients for DOC ¹⁴C in volcanic and carbonate aquifer rocks from southern Nevada. Experiments were conducted using bromide (Br-) as a conservative tracer and ¹⁴C-labeled trimesic acid (TMA) as a surrogate for groundwater DOC. Outcrop samples from six volcanic aquifers and five carbonate aquifers in southern Nevada were used. The average DOC ¹⁴C matrix diffusion coefficient for volcanic rocks was 2.9 x 10^-7 cm²/s, whereas the average for carbonate rocks was approximately the same at 1.7 x 10^-7 cm²/s. The average Br- matrix diffusion coefficient for volcanic rocks was 10.4 x 10^-7 cm²/s, whereas the average for carbonate rocks was less at 6.5 x 10^-7 cm²/s. Carbonate rocks exhibited greater variability in

Production of carbon-14 and preparation of some key precursors for labeling organic molecules

International Nuclear Information System (INIS)

Moriya, T.; Motoishi, S.

1992-01-01

Production of carbon-14 on 50 GBq scale has been performed by neutron irradiation of aluminium nitride target in the JMTR. This nuclide is separated in carbon dioxide form by combustion of the irradiated target at 1100degC with oxygen. The [ 14 C] carbon dioxide liberated thus is trapped in caustic solution and finally recovered as [ 14 C] barium carbonate. Some precursors useful for incorporating carbon-14 into a given organic molecule have been prepared. Precursors such as [1- 14 C] sodium acetate, [ 14 C] methanol and [ 14 C] potassium cyanide are prepared by rather conventional methods involving carbonation of methyl magnesium iodine, reduction of carbon dioxide with lithium aluminium hydride and reduction of carbonate with metallic potassium in the presence of ammonium salt, respectively. A catalytic polymerization of acetylene is used to prepare benzene. (author)

Accident source terms for Light-Water Nuclear Power Plants. Final report

International Nuclear Information System (INIS)

Soffer, L.; Burson, S.B.; Ferrell, C.M.; Lee, R.Y.; Ridgely, J.N.

1995-02-01

In 1962 tile US Atomic Energy Commission published TID-14844, ''Calculation of Distance Factors for Power and Test Reactors'' which specified a release of fission products from the core to the reactor containment for a postulated accident involving ''substantial meltdown of the core''. This ''source term'', tile basis for tile NRC's Regulatory Guides 1.3 and 1.4, has been used to determine compliance with tile NRC's reactor site criteria, 10 CFR Part 100, and to evaluate other important plant performance requirements. During the past 30 years substantial additional information on fission product releases has been developed based on significant severe accident research. This document utilizes this research by providing more realistic estimates of the ''source term'' release into containment, in terms of timing, nuclide types, quantities and chemical form, given a severe core-melt accident. This revised ''source term'' is to be applied to the design of future light water reactors (LWRs). Current LWR licensees may voluntarily propose applications based upon it

Carbon-14 dating of groundwater under Christchurch, 1976 samples

International Nuclear Information System (INIS)

Stewart, M.K.; Brenninkmeijer, C.A.M.; Brown, L.J.

1986-06-01

Four samples of groundwater from deep aquifers under Christchurch have been analysed for carbon-14, tritium, oxygen-18 and chemical contents. Interpretation of the carbon-14 results requires two steps, (1) correction of the measured 14 C values for input of dead ( 14 C-free) carbon underground (indicating that the measured values of 80 PMC* should be increased to about 120 PMC), and (2) determination of water residence times for given flow models of the groundwater system. Interpretation of tritium results involves step 2 only. Three models are considered, of which the third is considered most appropriate to Christchurch. In this model, the 14 C and T results indicate that a small proportion of young water (post-1954) mixes with a larger proportion of older water (probably at least several hundred years). The oxygen-18 content indicates that recharge is mainly from the Waimakariri River and possibly from rainfall and streams near the foothills of the Canterbury Plains. Other aspect of the groundwater flow under Christchurch are discussed

Preparation of 14C-labelled poly(l-menthyl isopropenyl carbonates)

International Nuclear Information System (INIS)

Comes, R.A.; Grubbs, H.J.

1981-01-01

The synthesis of 14 C-labelled poly(l-menthyl isopropenyl carbonate) is described. Experimental conditions are included for incorporation of 14 C into each of the carbon atoms in the molecule. High pressure liquid chromatography conditions are given for separation and purification of the labelled intermediates. (author)

Uncertainty assessment of source attribution of PM(2.5) and its water-soluble organic carbon content using different biomass burning tracers in positive matrix factorization analysis--a case study in Beijing, China.

Science.gov (United States)

Tao, Jun; Zhang, Leiming; Zhang, Renjian; Wu, Yunfei; Zhang, Zhisheng; Zhang, Xiaoling; Tang, Yixi; Cao, Junji; Zhang, Yuanhang

2016-02-01

Daily PM2.5 samples were collected at an urban site in Beijing during four one-month periods in 2009-2010, with each period in a different season. Samples were subject to chemical analysis for various chemical components including major water-soluble ions, organic carbon (OC) and water-soluble organic carbon (WSOC), element carbon (EC), trace elements, anhydrosugar levoglucosan (LG), and mannosan (MN). Three sets of source profiles of PM2.5 were first identified through positive matrix factorization (PMF) analysis using single or combined biomass tracers - non-sea salt potassium (nss-K(+)), LG, and a combination of nss-K(+) and LG. The six major source factors of PM2.5 included secondary inorganic aerosol, industrial pollution, soil dust, biomass burning, traffic emission, and coal burning, which were estimated to contribute 31±37%, 39±28%, 14±14%, 7±7%, 5±6%, and 4±8%, respectively, to PM2.5 mass if using the nss-K(+) source profiles, 22±19%, 29±17%, 20±20%, 13±13%, 12±10%, and 4±6%, respectively, if using the LG source profiles, and 21±17%, 31±18%, 19±19%, 11±12%, 14±11%, and 4±6%, respectively, if using the combined nss-K(+) and LG source profiles. The uncertainties in the estimation of biomass burning contributions to WSOC due to the different choices of biomass burning tracers were around 3% annually and up to 24% seasonally in terms of absolute percentage contributions, or on a factor of 1.7 annually and up to a factor of 3.3 seasonally in terms of the actual concentrations. The uncertainty from the major source (e.g. industrial pollution) was on a factor of 1.9 annually and up to a factor of 2.5 seasonally in the estimated WSOC concentrations. Copyright © 2015 Elsevier B.V. All rights reserved.

Design parameters and source terms: Volume 2, Source terms: Revision 0

International Nuclear Information System (INIS)

1987-09-01

The Design Parameters and Source Terms Document was prepared in accordance with DOE request and to provide data for the environmental impact study to be performed in the future for the Deaf Smith County, Texas site for a nuclear waste repository in salt. This document updates a previous unpublished report to the level of the Site Characterization Plan---Conceptual Design Report SCP-CDR. The previous study identifies the data needs for the Environmental Assessment effort for seven possible salt repository sites. Volume 2 contains tables of source terms

Detecting the permafrost carbon feedback: talik formation and increased cold-season respiration as precursors to sink-to-source transitions

Science.gov (United States)

Parazoo, Nicholas C.; Koven, Charles D.; Lawrence, David M.; Romanovsky, Vladimir; Miller, Charles E.

2018-01-01

Thaw and release of permafrost carbon (C) due to climate change is likely to offset increased vegetation C uptake in northern high-latitude (NHL) terrestrial ecosystems. Models project that this permafrost C feedback may act as a slow leak, in which case detection and attribution of the feedback may be difficult. The formation of talik, a subsurface layer of perennially thawed soil, can accelerate permafrost degradation and soil respiration, ultimately shifting the C balance of permafrost-affected ecosystems from long-term C sinks to long-term C sources. It is imperative to understand and characterize mechanistic links between talik, permafrost thaw, and respiration of deep soil C to detect and quantify the permafrost C feedback. Here, we use the Community Land Model (CLM) version 4.5, a permafrost and biogeochemistry model, in comparison to long-term deep borehole data along North American and Siberian transects, to investigate thaw-driven C sources in NHL ( > 55° N) from 2000 to 2300. Widespread talik at depth is projected across most of the NHL permafrost region (14 million km2) by 2300, 6.2 million km2 of which is projected to become a long-term C source, emitting 10 Pg C by 2100, 50 Pg C by 2200, and 120 Pg C by 2300, with few signs of slowing. Roughly half of the projected C source region is in predominantly warm sub-Arctic permafrost following talik onset. This region emits only 20 Pg C by 2300, but the CLM4.5 estimate may be biased low by not accounting for deep C in yedoma. Accelerated decomposition of deep soil C following talik onset shifts the ecosystem C balance away from surface dominant processes (photosynthesis and litter respiration), but sink-to-source transition dates are delayed by 20-200 years by high ecosystem productivity, such that talik peaks early ( ˜ 2050s, although borehole data suggest sooner) and C source transition peaks late ( ˜ 2150-2200). The remaining C source region in cold northern Arctic permafrost, which shifts to a net

(CH4)-C-14 Measurements in Greenland Ice: Investigating Last Glacial Termination CH4 Sources

DEFF Research Database (Denmark)

Petrenko, V. V.; Smith, A. M.; Brook, E. J.

2009-01-01

by direct cosmogenic C-14 production in ice. C-14 of CO was measured to better understand this process and correct the sample (CH4)-C-14. Corrected results suggest that wetland sources were likely responsible for the majority of the Younger Dryas-Preboreal CH4 rise.......The cause of a large increase of atmospheric methane concentration during the Younger Dryas-Preboreal abrupt climatic transition (similar to 11,600 years ago) has been the subject of much debate. The carbon-14 (C-14) content of methane ((CH4)-C-14) should distinguish between wetland and clathrate...... contributions to this increase. We present measurements of (CH4)-C-14 in glacial ice, targeting this transition, performed by using ice samples obtained from an ablation site in west Greenland. Measured (CH4)-C-14 values were higher than predicted under any scenario. Sample (CH4)-C-14 appears to be elevated...

Prioritizing low-carbon energy sources to enhance China’s energy security

International Nuclear Information System (INIS)

Ren, Jingzheng; Sovacool, Benjamin K.

2015-01-01

Highlights: • Four dimensions and ten metrics are used for energy security assessment. • Both qualitative and quantitative metrics are considered for energy security. • AHP has been used to quantify qualitative metrics. • TOPSIS method has been used for prioritize the low-carbon energy sources. • Sensitivity analysis and integrated ranking have been carried out. - Abstract: This paper explores how low-carbon systems compare to each other in terms of their net effect on Chinese energy security, and how they ought to be ranked and strategized into an optimal and integrated resource plan. The paper utilizes Analytic Hierarchy Process (AHP) to first determine the relative performances of hydroelectricity, wind energy, solar energy, biomass energy, and nuclear power with respect to the energy security dimensions of availability, affordability, accessibility, and acceptability. Both qualitative and quantitative metrics are considered. It relies on AHP to calculate the relative weights of the qualitative metrics attached to these dimensions of energy security for each of our five low carbon energy sources. Then, energy security performance is determined by aggregating multiple, weighted metrics into a generic index based on the method of TOPSIS and then tweaked with a sensitivity analysis. Finally, an integrated method has been developed to rank the low-carbon energy systems from most to least important, with major implications for Chinese decision-makers and stakeholders. We conclude that hydroelectricity and wind power are the two low-carbon energy sources with the most potential to enhance China’s energy security. By contrast, nuclear and solar power have the least potential

Nanostructured current sources based on carbon nanotubes excited by β radiation

International Nuclear Information System (INIS)

Saurov, A. N.; Bulyarskiy, S. V.; Risovaniy, V. D.; Pavlov, A. A.; Abanin, I. E.; Kitsyuk, E. P.; Shamanaev, A. A.; Lebedev, E. A.

2016-01-01

An analysis of available and promising developments is carried out in the field of power elements based on β decay. The possible fabrication technologies are described, and the efficiency of the power sources manufactured with them is calculated. The possibility of designing a self-charging supercapacitor based on carbon nanotubes is considered with the use of "6"3Ni and "1"4C isotopes, and theoretical calculation confirms the promising nature of this line of research.

Nanostructured current sources based on carbon nanotubes excited by β radiation

Energy Technology Data Exchange (ETDEWEB)

Saurov, A. N. [SMC Technological Center (Russian Federation); Bulyarskiy, S. V. [Russian Academy of Sciences, Microelectronics Nanotechnology Institute, INME (Russian Federation); Risovaniy, V. D. [CJSC Science and Innovation (Russian Federation); Pavlov, A. A. [Russian Academy of Sciences, Microelectronics Nanotechnology Institute, INME (Russian Federation); Abanin, I. E.; Kitsyuk, E. P.; Shamanaev, A. A. [SMC Technological Center (Russian Federation); Lebedev, E. A., E-mail: dr.beefheart@gmail.com [National Research University Moscow Institute of Electronic Technology (MIET) (Russian Federation)

2016-12-15

An analysis of available and promising developments is carried out in the field of power elements based on β decay. The possible fabrication technologies are described, and the efficiency of the power sources manufactured with them is calculated. The possibility of designing a self-charging supercapacitor based on carbon nanotubes is considered with the use of {sup 63}Ni and {sup 14}C isotopes, and theoretical calculation confirms the promising nature of this line of research.

How organic carbon derived from multiple sources contributes to carbon sequestration processes in a shallow coastal system?

Science.gov (United States)

Watanabe, Kenta; Kuwae, Tomohiro

2015-04-16

Carbon captured by marine organisms helps sequester atmospheric CO 2 , especially in shallow coastal ecosystems, where rates of primary production and burial of organic carbon (OC) from multiple sources are high. However, linkages between the dynamics of OC derived from multiple sources and carbon sequestration are poorly understood. We investigated the origin (terrestrial, phytobenthos derived, and phytoplankton derived) of particulate OC (POC) and dissolved OC (DOC) in the water column and sedimentary OC using elemental, isotopic, and optical signatures in Furen Lagoon, Japan. Based on these data analysis, we explored how OC from multiple sources contributes to sequestration via storage in sediments, water column sequestration, and air-sea CO 2 exchanges, and analyzed how the contributions vary with salinity in a shallow seagrass meadow as well. The relative contribution of terrestrial POC in the water column decreased with increasing salinity, whereas autochthonous POC increased in the salinity range 10-30. Phytoplankton-derived POC dominated the water column POC (65-95%) within this salinity range; however, it was minor in the sediments (3-29%). In contrast, terrestrial and phytobenthos-derived POC were relatively minor contributors in the water column but were major contributors in the sediments (49-78% and 19-36%, respectively), indicating that terrestrial and phytobenthos-derived POC were selectively stored in the sediments. Autochthonous DOC, part of which can contribute to long-term carbon sequestration in the water column, accounted for >25% of the total water column DOC pool in the salinity range 15-30. Autochthonous OC production decreased the concentration of dissolved inorganic carbon in the water column and thereby contributed to atmospheric CO 2 uptake, except in the low-salinity zone. Our results indicate that shallow coastal ecosystems function not only as transition zones between land and ocean but also as carbon sequestration filters. They

Seasonal variability of organic matter composition in an Alaskan glacier outflow: insights into glacier carbon sources

International Nuclear Information System (INIS)

Spencer, Robert G M; Vermilyea, Andrew; Fellman, Jason; Hood, Eran; Raymond, Peter; Stubbins, Aron; Scott, Durelle

2014-01-01

Glacier ecosystems are a significant source of bioavailable, yet ancient dissolved organic carbon (DOC). Characterizing DOC in Mendenhall Glacier outflow (southeast Alaska) we document a seasonal persistence to the radiocarbon-depleted signature of DOC, highlighting ancient DOC as a ubiquitous feature of glacier outflow. We observed no systematic depletion in Δ 14 C-DOC with increasing discharge during the melt season that would suggest mobilization of an aged subglacial carbon store. However, DOC concentration, δ 13 C-DOC, Δ 14 C-DOC and fluorescence signatures appear to have been influenced by runoff from vegetated hillslopes above the glacier during onset and senescence of melt. In the peak glacier melt period, the Δ 14 C-DOC of stream samples at the outflow (−181.7 to −355.3‰) was comparable to the Δ 14 C-DOC for snow samples from the accumulation zone (−207.2 to −390.9‰), suggesting that ancient DOC from the glacier surface is exported in glacier runoff. The pre-aged DOC in glacier snow and runoff is consistent with contributions from fossil fuel combustion sources similar to those documented previously in ice cores and thus provides evidence for anthropogenic perturbation of the carbon cycle. Overall, our results emphasize the need to further characterize DOC inputs to glacier ecosystems, particularly in light of predicted changes in glacier mass and runoff in the coming century. (papers)

Design parameters and source terms: Volume 2, Source terms: Revision 0

International Nuclear Information System (INIS)

1987-10-01

The Design Parameters and Source Terms Document was prepared in accordance with DOE request and to provide data for the environmental impact study to be performed in the future for the Deaf Smith County, Texas site for a nuclear waste repository in salt. This document updates a previous unpublished report by Stearns Catalytic Corporation (SCC), entitled ''Design Parameters and Source Terms for a Two-Phase Repository Salt,'' 1985, to the level of the Site Characterization Plan - Conceptual Design Report. The previous unpublished SCC Study identifies the data needs for the Environmental Assessment effort for seven possible Salt Repository sites. 2 tabs

Determination of carbon-14 environmental samples by mixing 14CO2 with a liquid scintillator

International Nuclear Information System (INIS)

Garcia Sanz, M.R.; Gomez, V.; Heras, M.C.; Beltran, M.A.

1990-01-01

A method for the determination of Carbon-14 ( 14 CO 2 ) in environmental samples has been developed. The method use the direct absorption of the carbon dioxide into Carbosorb, followed with incorporation of the mixture (Carbosorb-CO 2 ) to the liquid scintillator. The results obtained to apply this method and the benzene synthesis, usual in our laboratory, are discused and compared. The method of collection of atmospheric samples is also described. (Author)

Preliminary study of lead isotopes in the carbonate-silica veins of Trench 14, Yucca Mountain, Nevada

International Nuclear Information System (INIS)

Zartman, R.E.; Kwak, L.M.

1993-01-01

The sub-vertical carbonate-silica veins filling the Bow Ridge Fault, where exposed in Trench 14 on the east side of Yucca Mountain, carry a lead isotopic signature that can be explained in terms of local sources. Two isotopically distinguishable--silicate and carbonate--fractions of lead are recognized within the vein system as well as in overlying surficial calcrete deposits. The acid-insoluble silicate fraction is contributed largely from the decomposing Miocene volcanic tuff, which forms the wall rock of the fault zone and is a ubiquitous component of the overlying soil. Lead contained in the silicate fraction approaches in isotopic composition that of the Miocene volcanic rocks of Yucca Mountain, but diverges from it in some samples by being more enriched in uranogenic isotopes. The carbonate fraction of lead in both vein and calcrete samples resides dominantly in the HCl- and CH 3 COOH-soluble calcite. HCl evidently also attacks and removes lead from silicate phases, but the milder CH 3 COOH dissolution procedure oftentimes identifies a significantly more radiogenic lead in the calcite. Wind-blown particulate matter brought to the area from Paleozoic and Late Proterozoic limestones in surrounding mountains may be the ultimate source of the calcite. Isotopically more uniform samples suggest that locally the basaltic ash and other volcanic rock have contributed most of the lead to both fractions of the vein system. An important finding of this study is that the data does not require the more exotic mechanisms or origins that have been proposed for the veins. Instead, the remarkably similar lead isotopic properties of the veins to those of the soil calcretes support their interpretation as a surficial, pedogenic phenomenon

Biomarker and carbon isotope constraints (δ{sup 13}C, Δ{sup 14}C) on sources and cycling of particulate organic matter discharged by large Siberian rivers draining permafrost areas

Energy Technology Data Exchange (ETDEWEB)

Winterfeld, Maria

2014-08-15

Circumpolar permafrost soils store about half of the global soil organic carbon pool. These huge amounts of organic matter (OM) could accumulate due to low temperatures and water saturated soil conditions over the course of millennia. Currently most of this OM remains frozen and therefore does not take part in the active carbon cycle, making permafrost soils a globally important carbon sink. Over the last decades mean annual air temperatures in the Arctic increased stronger than the global mean and this trend is projected to continue. As a result the permafrost carbon pool is under climate pressure possibly creating a positive climate feedback due to the thaw-induced release of greenhouse gases to the atmosphere. Arctic warming will lead to increased annual permafrost thaw depths and Arctic river runoff likely resulting in enhanced mobilization and export of old, previously frozen soil-derived OM. Consequently, the great arctic rivers play an important role in global biogeochemical cycles by connecting the large permafrost carbon pool of their hinterlands with the arctic shelf seas and the Arctic Ocean. The first part of this thesis deals with particulate organic matter (POM) from the Lena Delta and adjacent Buor Khaya Bay. The Lena River in central Siberia is one of the major pathways translocating terrestrial OM from its southernmost reaches near Lake Baikal to the coastal zone of the Laptev Sea. The permafrost soils from the Lena catchment area store huge amounts of pre-aged OM, which is expected to be remobilized due to climate warming. To characterize the composition and vegetation sources of OM discharged by the Lena River, the lignin phenol and carbon isotopic composition (δ{sup 13}C and Δ{sup 14}C) in total suspended matter (TSM) from surface waters, surface sediments from the Buor Khaya Bay along with soils from the Lena Delta's first (Holocene) and third terraces (Pleistocene ice complex) were analyzed. The lignin compositions of these samples are

Synthesis of carbon-14 labeled vigabatrin. [Antieplileptic

Energy Technology Data Exchange (ETDEWEB)

Schuster, A.J.; Wagner, E.R. (Marion Merrell Dow Inc, Indianapolis, IN (United States))

1993-01-01

Carbon-14 labeled vigabatrin was synthesized in 5 steps from 5-hydroxymethyl-2-pyrrolidone tosylate and NaCN-[[sup 14]C]. A key step involved reduction of the resulting nitrile in the presence of excess dimethylamine to give the dimethylamino-ethyl 2-pyrrolidone derivative in one step. This afforded an overall radiochemical yield of 22% and radiochemical purity greater than 98%. (Author).

Continental Arcs as Both Carbon Source and Sink in Regulating Long Term Climate

Science.gov (United States)

Jiang, H.; Lee, C. T.

2017-12-01

The long-term variability of atmospheric pCO2 is determined by the balance between the rate of geologic inputs of CO­­2 (e.g., magmatic/metamorphic degassing, carbonate weathering) and the rate of carbonate precipitation driven by silicate weathering. The Late Cretaceous-Early Cenozoic was characterized by elevated atmospheric pCO2 and greenhouse climate, likely due to increased magmatic flux from mid-ocean ridges and, in particular, continental arcs. However, it has been suggested that continental arc magmatism is accompanied by rapid uplift and erosion due to magmatic/tectonic thickening of the crust, thus continental arcs likely enhance the chemical weathering flux, in turn increasing the carbon sink. To assess the contribution of continental arcs to global carbon inputs and sinks, we conducted a case study in the Cretaceous Peninsular Ranges batholith (PRB) and associated forearc basin in southern California, USA, representing one segment of the Cretaceous Cordillera arc-forearc system. Arc magmatism occurred between 170-85 Ma, peaking at 100 Ma, but erosion of the arc continues into the early Eocene, with forearc sediments representing this protracted arc unroofing. During magmatism, we estimate the CO2 degassing flux from the PRB was at least 5-25*105 mol·km-2·yr-1. By calculating the depletion of Ca and Mg in the forearc sediments relative to their arc protoliths, we estimate the silicate weathering/carbonate precipitation flux to be 106 mol·km-2·yr-1 during Late Cretaceous magmatism, decreasing to 105 mol·km-2·yr-1 by the Early Eocene. We show that during active continental arc magmatism, the CO2 degassing flux is comparable to CO2 consumption driven by silicate weathering in the arc. However, after magmatism ends, a regional imbalance arises in which the arc no longer contributes to CO2 inputs but continued silicate weathering of the arc drives carbonate precipitation such that the arc indirectly becomes CO2 sink. We propose that the development of

Carbon 14 distribution in irradiated BWR fuel cladding and released carbon 14 after aqueous immersion of 6.5 years

Energy Technology Data Exchange (ETDEWEB)

Sakuragi, T. [Radioactive Waste Management Funding and Research Center, Tsukishima 1-15-7, Chuo City, Tokyo, 104-0052 (Japan); Yamashita, Y.; Akagi, M.; Takahashi, R. [TOSHIBA Corporation, Ukishima Cho 4-1, Kawasaki Ward, Kawasaki, 210-0862 (Japan)

2016-07-01

Spent fuel cladding which is highly activated and strongly contaminated is expected to be disposed of in an underground repository. A typical activation product in the activated metal waste is carbon 14 ({sup 14}C), which is mainly generated by the {sup 14}N(n,p){sup 14}C reaction and produces a significant exposure dose due to the large inventory, long half-life (5730 years), rapid release rate, and the speciation and consequent migration parameters. In the preliminary Japanese safety case, the release of radionuclides from the metal matrix is regarded as the corrosion-related congruent release, and the cladding oxide layer is regarded as a source of instant release fraction (IRF). In the present work, specific activity of {sup 14}C was measured using an irradiated BWR fuel cladding (Zircaloy-2, average rod burnup of 41.6 GWd/tU) which has an external oxide film having a thickness of 25.3 μm. The {sup 14}C specific activity of the base metal was 1.49*10{sup 4} Bq/g, which in the corresponding burnup is comparable to values in the existing literature, which were obtained from various irradiated claddings. Although the specific activity in oxide was 2.8 times the base metal activity due to the additive generation by the {sup 17}O(n,α){sup 14}C reaction, the {sup 14}C abundance in oxide was less than 10% of total inventory. A static leaching test using the cladding tube was carried out in an air-tight vessel filled with a deoxygenated dilute NaOH solution (pH of 12.5) at room temperature. After 6.5 years, {sup 14}C was found in each leachate fraction of gas phase and dissolved organics and inorganics, the total of which was less than 0.01% of the {sup 14}C inventory of the immersed cladding tube. A simple calculation based on the congruent release with Zircaloy corrosion has suggested that the 96.7% of released {sup 14}C was from the external oxide layer and 3.3% was from the base Zircaloy metal. However, both the {sup 14}C abundance and the low leaching rate

A Low Carbon EU Energy System and Unconventional Sources

International Nuclear Information System (INIS)

Gracceva, F.; Kanudia, A.; Tosato, GC.

2013-01-01

The paper investigates the potential role of unconventional fossil fuels in a global low carbon energy system. Making use of a systemic approach, the paper presents an original application of a global partial equilibrium energy system model (TIAM-JET). In order to give a worldwide perspective with higher detail on European energy systems, the model links a set of extra-European macro-regions to the 30 European countries. First, a review of the most recent estimates of the available stocks of unconventional hydrocarbon resources is used to build the set of assumption for the scenario analysis. Secondly, a set of scenarios assuming different availability and cost of unconventional fuels are added to both a Current Trend scenario and a Carbon Constrained (CC) scenario, to explore the perspectives of unconventional gas and oil in a scenario halving CO 2 emissions by 2050, which is consistent with a 2 degree temperature increase. The results show if/how unconventional sources can contribute to the robustness of the European energy system with respect to the stress of a strong carbon constraint. We define this robustness as the capacity of the energy system to adapt its evolution to long-term constraints and keep delivering energy services to end users. In our approach robustness represents the long-term dimension of energy security. Assessing this ''system property'' requires analysing the wide range of factors that can exercise a stabilizing influence on the energy services delivery system, together with their relations, actual interactions and synergies. The energy system approach used for the analysis seeks to take into account as much of this complexity as possible. We assess the robustness of the EU system to the carbon constraint by looking at how the CC scenario affects energy system costs and energy prices under scenarios with different deployment of unconventional sources. This provides insights on the synergies and/or trade-offs between energy security and

The preparation of glucose uniformly labelled with carbon-14

International Nuclear Information System (INIS)

Garcia Pineda, M.D.; Suarez Contreras, C.; Rodrigo Gonzalez, M.E.

1978-01-01

The plant, (Zea mais, L) and culture conditions for an optimum production of glucose has been chosen. To achieve the labelling of glucose, photosynthesis and carboxylation are carried on, under an artificial atmosphere of 14CO 2 produced from 14 C -barium carbonate. Following photosynthesis the sugars are extracted, and then the extract purified by several methods. The purified glucose is finally, degraded and the specific radioactivity is determined in each of its carbon atoms. (Author) 37 refs

Carbon-14 labeling of phytoplankton carbon and chlorophyll a carbon: determination of specific growth rates

International Nuclear Information System (INIS)

Welschmeyer, N.A.; Lorenzen, C.J.

1984-01-01

The pattern of photosynthetic 14 C labeling over time is described for phytoplankton. The carbon-specific growth rate (d -1 ) is defined explicitly by changes in the specific activity (dpm μg -1 C) of the algae. For Skeletonema costatum, growing in axenic batch culture, the specific activities of both total cellular carbon and chlorophyll carbon increase at equal rates and the change in specific activity with time follows the predicted pattern. The specific activity of 14 C-labeled chlorophyll a was used to estimate phytoplankton growth rates and C:Chl ratios of field samples in Dabob Bay (Puget Sound), Washington. Growth rates decreased with depth and C:Chl ratios were higher for samples incubated under high light intensity. In several instances the C:Chl ratio increased from the beginning to the end of the incubation; this trend was most conspicuous near surface light intensities and for days of high total incident radiation. On these occasions, Chl a was actively 14 C labeled, yet little (or even negative) change was noted in the concentration of Chl a. These results suggest that some process (or processes) of chlorophyll degradation must be active at the same time that chlorophyll is being synthesized

Constraints on primary and secondary particulate carbon sources using chemical tracer and 14C methods during CalNex-Bakersfield

Data.gov (United States)

U.S. Environmental Protection Agency — The present study investigates primary and secondary sources of organic carbon for Bakersfield, CA, USA as part of the 2010 CalNex study. The method used here...

Large-scale Patterns of 14C Age of Bulk Organic Carbon and Various Molecular Components in Grassland Soils

Science.gov (United States)

Jia, J.; Liu, Z.; Cao, Z.; Chen, L.; He, J. S.; Haghipour, N.; Wacker, L.; Eglinton, T. I.; Feng, X.

2017-12-01

Unraveling the fate of organic carbon (OC) in soils is essential to understanding the impact of global changes on the global carbon cycle. Previous studies have shown that while various soil OC components have different decomposability, chemically labile OC can have old 14C ages. However, few studies have compared the 14C age of various soil OC components on a large scale, which may provide important information on the link between the age or turnover of soil OC components to their sources, molecular structures as well as environmental variables. In this project, a suite of soil profiles were sampled along a large-scale transect of temperate and alpine grasslands across the Tibetan and Mongolian Plateaus in China with contrasting climatic, vegetation and soil properties. Bulk OC and source-specific compounds (including fatty acids (FAs), diacids (DAs) and lignin phenols) were radiocarbon-dated to investigate the age and turnover dynamics of different OC pools and the mechanisms controlling their stability. Our results show that lignin phenols displayed a large 14C variability. Short-chain (C16, 18) FAs sourced from vascular plants as well as microorganisms were younger than plant-derived long-chain FAs and DAs, indicating that short-chain FAs were easier to be decomposed or newly synthesized. In the temperate grasslands, long-chain DAs were younger than FAs, while the opposite trend was observed in the alpine grasslands. Preliminary correlation analysis suggests that the age of short-chain FAs were mainly influenced by clay contents and climate, while reactive minerals, clay or silt particles were important factors in the stabilization of long-chain FAs, DAs and lignin phenols. Overall, our study provided a unique 14 C dataset of soil OC components in grasslands, which will provide important constraints on soil carbon turnover in future investigations.

STACE: Source Term Analyses for Containment Evaluations of transport casks

International Nuclear Information System (INIS)

Seager, K.D.; Gianoulakis, S.E.; Barrett, P.R.; Rashid, Y.R.; Reardon, P.C.

1992-01-01

Following the guidance of ANSI N14.5, the STACE methodology provides a technically defensible means for estimating maximum permissible leakage rates. These containment criteria attempt to reflect the true radiological hazard by performing a detailed examination of the spent fuel, CRUD, and residual contamination contributions to the releasable source term. The evaluation of the spent fuel contribution to the source term has been modeled fairly accurately using the STACE methodology. The structural model predicts the cask drop load history, the mechanical response of the fuel assembly, and the probability of cladding breach. These data are then used to predict the amount of fission gas, volatile species, and fuel fines that are releasable from the cask. There are some areas where data are sparse or lacking (e.g., the quantity and size distribution of fuel rod breaches) in which experimental validation is planned. The CRUD spallation fraction is the major area where no quantitative data has been found; therefore, this also requires experimental validation. In the interim, STACE conservatively assumes a 100% spallation fraction for computing the releasable activity. The source term methodology also conservatively assumes that there is 1 Ci of residual contamination available for release in the transport cask. However, residual contamination is still by far the smallest contributor to the source term activity

Long-term operation experience with 2 ECR ion sources and planned extensions at HIT

International Nuclear Information System (INIS)

Winkelmann, T.; Cee, R.; Haberer, T.; Naas, B.; Peters, A.

2012-01-01

The HIT (Heidelberg Ion Beam Therapy Center) is the first treatment facility at a hospital in Europe where patients can be treated with protons and carbon ions. Since the commissioning starting in 2006 two 14.5 GHz electron cyclotron resonance ion sources are routinely used to produce a variety of ion beams from protons up to oxygen. The operating time is 330 days per year, our experience after three years of continuous operation will be presented. In the future a helium beam for patient treatment is requested, therefore a third ion source will be integrated. This third ECR source with a newly designed extraction system and a spectrometer line will be installed at a test-bench to commission and validate this section. Different test settings are foreseen to study helium operation as well as enhanced parameter sets for proton and carbon beams in combination with a modified beam transport line for higher transmission efficiency. An outlook to the possible integration scheme of the new ion source into the production facility will be discussed. The paper is followed by the associated poster. (authors)

Carbon-14 speciation during anoxic corrosion of activated steel in a repository environment

Energy Technology Data Exchange (ETDEWEB)

Wieland, E.; Cvetkovic, B.Z.; Kunz, D. [Paul Scherrer Institute, Villigen (Switzerland). Lab. for Waste Management; Salazar, G.; Szidat, S. [Bern Univ. (Switzerland). Dept. of Chemistry and Biochemistry and Oeschger Centre for Climate Change Research

2018-01-15

Radioactive waste contains significant amounts of {sup 14}C which has been identified a key radionuclide in safety assessments. In Switzerland, the {sup 14}C inventory of a cement-based repository for low- and intermediate-level radioactive waste (L/ILW) is mainly associated with activated steel (∝85 %). {sup 14}C is produced by {sup 14}N activation in steel parts exposed to thermal neutron flux in light water reactors. Release of {sup 14}C occurs in the near field of a deep geological repository due to anoxic corrosion of activated steel. Although the {sup 14}C inventory of the L/ILW repository and the sources of {sup 14}C are well known, the formation of {sup 14}C species during steel corrosion is only poorly understood. The aim of the present study was to identify and quantify the {sup 14}C-bearing carbon species formed during the anoxic corrosion of iron and steel and further to determine the {sup 14}C speciation in a corrosion experiment with activated steel. All experiments were conducted in conditions similar to those anticipated in the near field of a cement-based repository.

Synthesis of carbon-14 analogue of 1,5 diaryl-5-[14C]-1,2,3-triazoles

International Nuclear Information System (INIS)

Matloubi, Hojatollah; Shafiee, Abbas; Saemian, Nader; Shirvani, Gholamhossein; Daha, Fariba Johari

2004-01-01

Two 1,2,3-triazole anticonvulsants, 1-(4-methylsulfone-phenyl)-5-(4-methyl-phenyl)-1,2,3-triazole and 1-(4-methylsulfone-phenyl)-5-phenyl-1,2,3-triazole, both labeled with carbon-14 in the 5-position were prepared from para-tolunitrile-[cyano- 14 C] and benzonitrile-[cyano- 14 C], respectively

Short-term carbon isotopic fractionation in plants

International Nuclear Information System (INIS)

Rooney, M.A.

1988-01-01

A system was developed for measuring carbon isotopic fractionation in plants over a time interval of 1-3 hours, in contrast to leaf combustion studies which give long-term, integrated discrimination measurements. The system was used to study environmental effects on soybean (Glycine max) and corn (Zea mays) discrimination. Changes in leaf temperature, photon flux density (PFD), O 2 concentration, and CO 2 concentration produced little or no change in measured discrimination (Δ). For soybean, Δ increased with decreasing PFD. For corn, Δ decreased with decreasing O 2 concentration. For both soybean and corn, Δ increased with increasing CO 2 concentration. These changes in Δ were interpreted as environmental effects on stomatal conductance and photosynthetic capacity, which indirectly affect Δ by altering C i /C a . Respiratory discrimination in the dark and light was also investigated. Respired CO 2 was 5 per-thousand and 0-1 per-thousand more positive than leaf carbon for soybean and corn, respectively. Photorespiratory discrimination was 6-7 per-thousand for soybean, supporting the contention that glycine decarboxylase may be the source of discrimination in the photorespiratory pathway

Measuring priming using 14C of respired CO2: effects on respiration source pools and interactions with warming

Science.gov (United States)

Hopkins, F. M.; Trumbore, S.

2011-12-01

The role of substrate availability on soil carbon turnover is a critical unknown in predicting future soil carbon stocks. Substrate composition and availability can be altered by land cover change, warming, and nitrogen deposition, which can in turn affect soil carbon stocks through the priming effect. In particular, little is understood about the interaction between warming and changing substrate concentration. We examined the interactions between global change factors and the priming effect using sucrose addition to incubations of soils from two forest Free Air CO2 Enrichment (FACE) sites (Duke and Aspen). In addition to the in situ global change manipulations conducted at these sites, the CO2 fertilization procedure over the decade-long experiment labeled soil carbon pools with fossil-derived carbon (depleted in 14C relative to the background isotope content of soil carbon), allowing us to determine the effect of priming on respiration of soil carbon substrates of different ages. Thus, we used the carbon-13 signature of sucrose-derived CO2 to account for losses of substrate C, and the carbon-14 signature to partition fluxes of soil-derived CO2 between pre-FACE (> 10 y) and FACE derived (stocks, differences in the source of the priming effect between the two sites may be due to inherent differences in the relative role of stabilization factors within the soil carbon stock.

Detecting the permafrost carbon feedback: talik formation and increased cold-season respiration as precursors to sink-to-source transitions

Directory of Open Access Journals (Sweden)

N. C. Parazoo

2018-01-01

Full Text Available Thaw and release of permafrost carbon (C due to climate change is likely to offset increased vegetation C uptake in northern high-latitude (NHL terrestrial ecosystems. Models project that this permafrost C feedback may act as a slow leak, in which case detection and attribution of the feedback may be difficult. The formation of talik, a subsurface layer of perennially thawed soil, can accelerate permafrost degradation and soil respiration, ultimately shifting the C balance of permafrost-affected ecosystems from long-term C sinks to long-term C sources. It is imperative to understand and characterize mechanistic links between talik, permafrost thaw, and respiration of deep soil C to detect and quantify the permafrost C feedback. Here, we use the Community Land Model (CLM version 4.5, a permafrost and biogeochemistry model, in comparison to long-term deep borehole data along North American and Siberian transects, to investigate thaw-driven C sources in NHL ( >  55° N from 2000 to 2300. Widespread talik at depth is projected across most of the NHL permafrost region (14 million km2 by 2300, 6.2 million km2 of which is projected to become a long-term C source, emitting 10 Pg C by 2100, 50 Pg C by 2200, and 120 Pg C by 2300, with few signs of slowing. Roughly half of the projected C source region is in predominantly warm sub-Arctic permafrost following talik onset. This region emits only 20 Pg C by 2300, but the CLM4.5 estimate may be biased low by not accounting for deep C in yedoma. Accelerated decomposition of deep soil C following talik onset shifts the ecosystem C balance away from surface dominant processes (photosynthesis and litter respiration, but sink-to-source transition dates are delayed by 20–200 years by high ecosystem productivity, such that talik peaks early ( ∼  2050s, although borehole data suggest sooner and C source transition peaks late ( ∼  2150–2200. The

Carbon source/sink function of a subtropical, eutrophic lake determined from an overall mass balance and a gas exchange and carbon burial balance

International Nuclear Information System (INIS)

Yang Hong; Xing Yangping; Xie Ping; Ni Leyi; Rong Kewen

2008-01-01

Although studies on carbon burial in lake sediments have shown that lakes are disproportionately important carbon sinks, many studies on gaseous carbon exchange across the water-air interface have demonstrated that lakes are supersaturated with CO 2 and CH 4 causing a net release of CO 2 and CH 4 to the atmosphere. In order to more accurately estimate the net carbon source/sink function of lake ecosystems, a more comprehensive carbon budget is needed, especially for gaseous carbon exchange across the water-air interface. Using two methods, overall mass balance and gas exchange and carbon burial balance, we assessed the carbon source/sink function of Lake Donghu, a subtropical, eutrophic lake, from April 2003 to March 2004. With the overall mass balance calculations, total carbon input was 14 905 t, total carbon output was 4950 t, and net carbon budget was +9955 t, suggesting that Lake Donghu was a great carbon sink. For the gas exchange and carbon burial balance, gaseous carbon (CO 2 and CH 4 ) emission across the water-air interface totaled 752 t while carbon burial in the lake sediment was 9477 t. The ratio of carbon emission into the atmosphere to carbon burial into the sediment was only 0.08. This low ratio indicates that Lake Donghu is a great carbon sink. Results showed good agreement between the two methods with both showing Lake Donghu to be a great carbon sink. This results from the high primary production of Lake Donghu, substantive allochthonous carbon inputs and intensive anthropogenic activity. Gaseous carbon emission accounted for about 15% of the total carbon output, indicating that the total output would be underestimated without including gaseous carbon exchange. - Due to high primary production, substantive allochthonous carbon inputs and intensive anthropogenic acitivity, subtropical, eutrophic Lake Donghu is a great carbon sink

40 CFR 406.14 - Pretreatment standards for existing sources.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 28 2010-07-01 2010-07-01 true Pretreatment standards for existing sources. 406.14 Section 406.14 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS GRAIN MILLS POINT SOURCE CATEGORY Corn Wet Milling Subcategory § 406.14...

Achieving high performance in intermediate temperature direct carbon fuel cells with renewable carbon as a fuel source

International Nuclear Information System (INIS)

Hao, Wenbin; He, Xiaojin; Mi, Yongli

2014-01-01

Highlights: • Bamboo fiber and waste paper were pyrolyzed to generate bamboo carbon and waste paper carbon as anode fuels of IT-DCFC. • Superior cell performance was achieved with the waste paper carbon. • The results suggested the high performance was due to the highest thermal reactivity and the catalytic inherent impurities. • Calcite and kaolinite as inherent impurities favored the thermal decomposition and the electrooxidation of carbon. - Abstract: Three kinds of carbon sources obtained from carbon black, bamboo fiber and waste paper were investigated as anode fuels in an intermediate temperature direct carbon fuel cell. The carbon sources were characterized with X-ray photoelectron spectroscopy, thermal gravimetric analysis, etc. The results indicated that the waste paper carbon was more abundant in calcite and kaolinite, and showed higher thermal reactivity in the intermediate temperature range compared with the other two carbon sources. The cell performance was tested at 650 °C in a hybrid single cell, using Sm 0.20 Ce 0.80 O 2−x as the electrolyte. As a result, the cell fed with waste paper carbon showed the highest performance among the three carbon sources, with a peak power density of 225 mW cm −2 . The results indicated that its inherent impurities, such as calcite and kaolinite, might favor the thermal gasification of renewable carbon sources, which resulted in the enhanced performance of the intermediate temperature direct carbon fuel cell

Apportioning bacterial carbon source utilization in soil using 14 C isotope analysis of FISH-targeted bacterial populations sorted by fluorescence activated cell sorting (FACS): 14 C-FISH-FACS.

Science.gov (United States)

Gougoulias, Christos; Meade, Andrew; Shaw, Liz J

2018-02-19

An unresolved need in microbial ecology is methodology to enable quantitative analysis of in situ microbial substrate carbon use at the population level. Here, we evaluated if a novel combination of radiocarbon-labelled substrate tracing, fluorescence in situ hybridisation (FISH) and fluorescence-activated cell sorting (FACS) to sort the FISH-targeted population for quantification of incorporated radioactivity ( 14 C-FISH-FACS) can address this need. Our test scenario used FISH probe PSE1284 targeting Pseudomonas spp. (and some Burkholderia spp.) and salicylic acid added to rhizosphere soil. We examined salicylic acid- 14 C fate (mineralized, cell-incorporated, extractable and non-extractable) and mass balance (0-24 h) and show that the PSE1284 population captured ∼ 50% of the Nycodenz extracted biomass 14 C. Analysis of the taxonomic distribution of the salicylic acid biodegradation trait suggested that PSE1284 population success was not due to conservation of this trait but due to competitiveness for the added carbon. Adding 50KBq of 14 C sample -1 enabled detection of 14 C in the sorted population at ∼ 60-600 times background; a sensitivity which demonstrates potential extension to analysis of rarer/less active populations. Given its sensitivity and compatibility with obtaining a C mass balance, 14 C-FISH-FACS allows quantitative dissection of C flow within the microbial biomass that has hitherto not been achieved. © 2018 Society for Applied Microbiology and John Wiley & Sons Ltd.

Determination of Carbon-14 in environmental samples by mixing 14CO2 with a liquid scintillator

International Nuclear Information System (INIS)

Garcia, M. R.; Gomez, V.; Heras, M. C.; Beltran, M. A.

1990-01-01

A method for the determination of Carbon-14 (14CO2) in environmental samples has been developed. The method use the direct absorption of the carbon dioxide into Carbosorb, followed with incorporation of the mixture (Carbosorb-CO2) to the liquid scintillator. The results obtained to apply this method and the benzene synthesis, usual in our laboratory, are discussed and compared. The method of collection of atmospheric samples is also described. (Author) 10 refs

Growth of graphene films from non-gaseous carbon sources

Science.gov (United States)

Tour, James; Sun, Zhengzong; Yan, Zheng; Ruan, Gedeng; Peng, Zhiwei

2015-08-04

In various embodiments, the present disclosure provides methods of forming graphene films by: (1) depositing a non-gaseous carbon source onto a catalyst surface; (2) exposing the non-gaseous carbon source to at least one gas with a flow rate; and (3) initiating the conversion of the non-gaseous carbon source to the graphene film, where the thickness of the graphene film is controllable by the gas flow rate. Additional embodiments of the present disclosure pertain to graphene films made in accordance with the methods of the present disclosure.

An improved synthesis of carbon-14 labelled carboxylic acids from carbon-14 labelled amino acids

International Nuclear Information System (INIS)

Ramamurthy, T.V.; Ravi, S.; Viswanathan, K.V.

1988-01-01

Various carbon-14 labelled amino acids including the aromatic ones viz., tyrosine, phenylalanine and tryptophan are converted to the corresponding carboxylic acids in high yield (70-90%) on a micromolar scale synthesis by reaction with hydroxyl-amine-O-sulphonic acid and in a short reaction time. The improvement in yield has been achieved by using aqeuous alcohol as solvent in lieu of water alone as the medium of reaction. (author)

Carbon-14 kinetic isotope effects and mechanisms of addition of 2,4-dinitrobenzenesulfenyl chloride to substituted styrenes-1-14C and styrenes-2-14C

International Nuclear Information System (INIS)

Kanska, M.; Fry, A.

1983-01-01

As the first reported examples of carbon isotope effects in simple electrophilic addition reactions we have measured the carbon-14 kinetic isotope effects in the addition of 2,4-dinitrobenzenesulfenyl chloride to a series of para-substituted α and β-labeled styrenes in acetic acid at 30.1 0 C: for para substituents Cl, H, and CH 3 the k/ 14 K values for α labeling are 1.027, 1.022, and 1.004, and the k/ 14 k values for β labeling are 1.035, 1.032, and 1.037, all +/-approx.0.004. The kinetics of the reaction were measured for the p-CH 3 O,p-CH 3 , unsubstituted, p-Cl, and m-NO 2 styrenes; electron-donating groups strongly accelerate the reaction, and electron-withdrawing groups retard it. The Hammett plot is curved with p + values ranging from about -4.6 at the electron-donating group (EDG) end to about -1.8 at the electron-withdrawing group (EWG) end. Both the isotope effect and kinetic data, and related data from the literature, are interpreted in terms of a changing mechanism, with the activated complexes of the rate-determining steps having much open carbenium ion (ion pair) character for EDG-substituted styrenes and much cyclic thiiranium io (ion par) character for EWG-substituted styrenes. 1 figure, 2 tables

Carbon-14 immobilization via the CO2-Ba(OH)2 hydrate gas-solid reaction

International Nuclear Information System (INIS)

Haag, G.L.

1980-01-01

Although no restrictions have been placed on the release of carbon-14, it has been identified as a potential health hazard due to the ease in which it may be assimilated into the biosphere. The intent of the Carbon-14 Immobilization Program, funded through the Airborne Waste Program Management Office, is to develop and demonstrate a novel process for restricting off-gas releases of carbon-14 from various nuclear facilities. The process utilizes the CO 2 -Ba(OH) 2 hydrate gas-solid reaction to directly remove and immobilize carbon-14. The reaction product, BaCO 3 , possesses both the thermal and chemical stability desired for long-term waste disposal. The process is capable of providing decontamination factors in excess of 1000 and reactant utilization of greater than 99% in the treatment of high volumetric, airlike (330 ppM CO 2 ) gas streams. For the treatment of an air-based off-gas stream, the use of packed beds of Ba(OH) 2 .8H 2 O flakes to remove CO 2 has been demonstrated. However, the operating conditions must be maintained between certain upper and lower limits with respect to the partial pressure of water. If the water vapor pressure in the gas is less than the dissociation vapor pressure of Ba(OH) 2 .8H 2 O, the bed will deactivate. If the vapor pressure is considerably greater, pressure drop problems will increase with increasing humidity as the particles curl and degrade. Results have indicated that when operated in the proper regime, the bulk of the increase in pressure drop results from the conversion of Ba(OH) 2 .8H 2 O to BaCO 3 and not from the hydration of the commercial Ba(OH) 2 .8H 2 O (i.e. Ba(OH) 2 .7.50H 2 O) to Ba(OH) 2 .8H 2 O

New views on "old" carbon in the Amazon River: Insight from the source of organic carbon eroded from the Peruvian Andes

Science.gov (United States)

Clark, K. E.; Hilton, R. G.; West, A. J.; Malhi, Y.; Gröcke, D. R.; Bryant, C. L.; Ascough, P. L.; Robles Caceres, A.; New, M.

2013-05-01

rivers play a key role in the delivery of particulate organic carbon (POC) to large river systems and the ocean. Due to the extent of its drainage area and runoff, the Amazon River is one of Earth's most important biogeochemical systems. However, the source of POC eroded from the humid region of the Eastern Andes and the input of fossil POC from sedimentary rocks (POCfossil) remains poorly constrained. Here we collected suspended sediments from the Kosñipata River during flood events to better characterize Andean POC, measuring the nitrogen to organic carbon ratio (N/C), stable carbon isotopes (δ13Corg) and radiocarbon (Δ14Corg). Δ14Corg values ranged from -711‰ to -15‰, and significant linear trends between Δ14Corg, N/C and δ13Corg suggested that this reflects the mixing of POCfossil with very young organic matter (Δ14Corg 50‰) from the terrestrial biosphere (POCnon-fossil). Using N/C and Δ14Corg in an end-member mixing analysis, we quantify the fraction of POCfossil (to within 0.1) and find that it contributes a constant proportion of the suspended sediment mass (0.37 ± 0.03%) and up to 80% of total POC. In contrast, the relative contribution of POCnon-fossil was variable, being most important during the rising limb and peak discharges of flood events. The new data shed light on published measurements of "old" POC (low Δ14Corg) in Andean-fed tributaries of the Amazon River, with their Δ14Corg and δ13Corg values consistent with variable addition of POCfossil. The findings suggest a greater persistence of Andean POC in the lowland Amazon than previously recognized.

Carbon source feeding strategies for recombinant protein ...

African Journals Online (AJOL)

USER

2010-04-12

Apr 12, 2010 ... protein expression with the influence of the carbon source feeding ... in the culture media, increasing the peroxisomes numbers ...... source, temperature, pH, O2, methanol feeding strategy) ..... Catabolite Inactivation in Yeast.

Woody debris along an upland chromosequence in boreal Manitoba and its impact on long-term carbon storage

Energy Technology Data Exchange (ETDEWEB)

Manies, K. L.; Harden, J. W. [US Geological Survey, Menlo Park, CA (United States); Bond-Lamberty, B. P. [University of Wisconsin, Dept. of Forest Ecology and Management, Madison, WI (United States); O' Neill, K. P. [USDA Agricultural Research Service, Appalachian Farming Systems Research Center, Beaver, WV (United States)

2005-02-01

The amount of standing dead and downed woody debris along an upland chromosequence was measured in an effort to investigate the role of fire-killed woody debris as a source of soil carbon in black spruce stands in Manitoba. Based on the measurement data and existing primary production values, a mass balance model was used to assess the potential impact of fire-killed wood on long-term carbon storage at this site. Long-term carbon was represented by the amount of carbon stored in deeper soil organic layers, persisting over millenia. Between 10 and 60 per cent of the deep-soil carbon was estimated to have been derived from wood biomass. The actual amount appears to be most affected by fire return interval, decay rate of wood, the amount of net primary production, and the decay rate of the post-fire carbon pool. Although the model was less sensitive to fire consumption rates and to rates at which standing dead wood becomes woody debris, all model runs clearly established that woody debris plays an important role in long-term carbon storage in this area. 53 refs., 4 tabs., 4 figs.

Model study of atmospheric transport using carbon 14 and strontium 90 as inert tracers

Science.gov (United States)

Kinnison, D. E.; Johnston, H. S.; Wuebbles, D. J.

1994-10-01

The observed excess carbon 14 in the atmosphere from 1963 to 1970 provides unique, but limited, data up to an altitude of about 35 km for testing the air motions calculated by 11 multidimensional atmospheric models. Strontium 90 measurements in the atmosphere from 1964 to mid-1967 provide data that have more latitude coverage than those of carbon 14 and are useful for testing combined models of air motions and aerosol settling. Model calculations for carbon 14 begin at October 1963, 9 months after the conclusion of the nuclear bomb tests; the initial conditions for the calculations are derived by three methods, each of which agrees fairly well with measured carbon 14 in October 1963 and each of which has widely different values in regions of the stratosphere where there were no carbon 14 measurements. The model results are compared to the stratospheric measurements, not as if the observed data were absolute standards, but in an effort to obtain new insight about the models and about the atmosphere. The measured carbon 14 vertical profiles at 31°N are qualitatively different from all of the models; the measured vertical profiles show a maximum mixing ratio in the altitude range of 20 to 25 km from October 1963 through July 1966, but all modeled profiles show mixing ratio maxima that increase in altitude from 20 km in October 1963 to greater than 40 km by April 1966. Both carbon 14 and strontium 90 data indicate that the models differ substantially among themselves with respect to stratosphere-troposphere exchange rate, but the modeled carbon 14 stratospheric residence times indicate that differences among the models are small with respect to transport rate between the middle stratosphere and the lower stratosphere. Strontium 90 data indicate that aerosol settling is important up to at least 35 km altitude. Relative to the measurements, about three quarters of the models transport carbon 14 from the lower stratosphere to the troposphere too rapidly, and all models

Authigenic carbonates from newly discovered active cold seeps on the northwestern slope of the South China Sea: Constraints on fluid sources, formation environments, and seepage dynamics

Science.gov (United States)

Liang, Qianyong; Hu, Yu; Feng, Dong; Peckmann, Jörn; Chen, Linying; Yang, Shengxiong; Liang, Jinqiang; Tao, Jun; Chen, Duofu

2017-06-01

Authigenic carbonates recovered from two newly discovered active cold seeps on the northwestern slope of the South China Sea have been studied using petrography, mineralogy, stable carbon and oxygen isotopic, as well as trace element compositions, together with AMS 14C ages of shells of seep-dwelling bivalves to unravel fluid sources, formation conditions, and seepage dynamics. The two seeps (ROV1 and ROV2), referred to as 'Haima seeps' herein, are approximately 7 kilometers apart, and are typified by abundant carbonate rocks represented bycrusts and nodules. Aragonite and high-Mg calcite are the main carbonate minerals. Based on low δ13Ccarbonate values ranging from -43.0‰ to -27.5‰ (V-PDB) methane is apparently the predominant carbon source of seep carbonates. The corresponding δ18O values, varying from 2.5‰ to 5.8‰ (V-PDB), mostly are higher than calculated values representing precipitation in equilibrium with seawater (2.5‰ to 3.8‰), which probably reflects past destabilization of locally abundant gas hydrates. In addition, we found that carbonates with bivalve shells are generally aragonite-dominated, and bear no barium enrichment but uranium enrichments, reflecting shallow formation depths close to the seafloor. In contrast, carbonate crusts without bivalve shells and nodules contain more calcite, and are characterized by major molybdenum enrichment and different degrees of barium enrichment, agreeing with precipitation at greater depth under strictly anoxic conditions. AMS 14C ages suggest that a major episode of carbonate precipitation occurred between 6.1 ka and 5.1 ka BP at the Haima seeps, followed by a possibly subordinate episode from approximately 3.9 ka to 2.9 ka BP. The common occurrence of dead bivalves at both sites indicates that chemosynthesis-based communities flourished to a greater extent in the past, probably reflecting a decline of seepage activity in recent times. Overall, these results confirm that authigenic carbonates from

The metabolism and dosimetry of carbon-14 labelled diethylenetriaminepentaacetic acid (DTPA)

International Nuclear Information System (INIS)

Crawley, F.E.H.; Haines, J.W.

1978-01-01

Male rats were given carbon-14 labelled Ca-DTPA either by intravenous injection or by pulmonary intubation. The elimination of the carbon-14 by excretion in urine, faeces and breath was followed, Chromatographic examination of the urine showed that no metabolic degradation of the 14 C-DTPA had occurred. The distribution of activity between lung, kidneys, bone, muscle and GI tract was also followed. The data obtained have been used to assess the radiation dose to man from an intake of 14 C-DTPA on the assumption that the behaviour of 14 C-DTPA in man is the same as in the rat. The results are discussed. (U K.)

Near-term deployment of carbon capture and sequestration from biorefineries in the United States.

Science.gov (United States)

Sanchez, Daniel L; Johnson, Nils; McCoy, Sean T; Turner, Peter A; Mach, Katharine J

2018-05-08

Capture and permanent geologic sequestration of biogenic CO 2 emissions may provide critical flexibility in ambitious climate change mitigation. However, most bioenergy with carbon capture and sequestration (BECCS) technologies are technically immature or commercially unavailable. Here, we evaluate low-cost, commercially ready CO 2 capture opportunities for existing ethanol biorefineries in the United States. The analysis combines process engineering, spatial optimization, and lifecycle assessment to consider the technical, economic, and institutional feasibility of near-term carbon capture and sequestration (CCS). Our modeling framework evaluates least cost source-sink relationships and aggregation opportunities for pipeline transport, which can cost-effectively transport small CO 2 volumes to suitable sequestration sites; 216 existing US biorefineries emit 45 Mt CO 2 annually from fermentation, of which 60% could be captured and compressed for pipeline transport for under $25/tCO 2 A sequestration credit, analogous to existing CCS tax credits, of $60/tCO 2 could incent 30 Mt of sequestration and 6,900 km of pipeline infrastructure across the United States. Similarly, a carbon abatement credit, analogous to existing tradeable CO 2 credits, of $90/tCO 2 can incent 38 Mt of abatement. Aggregation of CO 2 sources enables cost-effective long-distance pipeline transport to distant sequestration sites. Financial incentives under the low-carbon fuel standard in California and recent revisions to existing federal tax credits suggest a substantial near-term opportunity to permanently sequester biogenic CO 2 This financial opportunity could catalyze the growth of carbon capture, transport, and sequestration; improve the lifecycle impacts of conventional biofuels; support development of carbon-negative fuels; and help fulfill the mandates of low-carbon fuel policies across the United States. Copyright © 2018 the Author(s). Published by PNAS.

Carbon trading and carbon taxation: how to consider biotic sources and sinks

International Nuclear Information System (INIS)

Madlener, Reinhard; Schlamadinger, Bernhard

1999-01-01

The Kyoto Protocol (KP) to the UNFCCC includes land-use change and forestry in the carbon accounting process, limited to afforestation, reforestation and deforestation since 1990, and explicitly provides for the option of using a variety of flexibility mechanisms to meet the greenhouse gas (GHG) reduction targets stipulated in a more cost-efficient manner. Domestically, different countries might adopt different approaches to achieve their emission reduction objectives, such as carbon trading or carbon taxation, and it is not clear to date what the implications for bioenergy use, forestry, and land-use change can be expected to be. With respect to national GHG emissions trading, the main issues studied in this paper are: Should trading of fossil fuel emissions allowances be coupled with trading of biotic credits and debits? Should credits for carbon sequestration in forests be auctioned or grandfathered? Should there be a distinction between a carbon permit issued for an additional biotic sink and those issued for fossil fuel carbon emissions? Is there a difference for biotic carbon sinks and sources between one-time permits and permits that allow a continued release of GHG over some pre-specified time? Should permits be issued only for the carbon-stock changes that count under the KP? With respect to national carbon taxation schemes, two questions are investigated: Should a tax credit be given for afforestation/reforestation (and a tax debit for deforestation)? Should tax credits also be given for projects that sequester carbon but do not count under the KP (such as forest protection rather than forest management)? For both schemes a crucial point is that by the formulation chosen in the KP two different classes of forest are created (i.e. those counted and those not counted under the KP), so that the implications for land prices might be significant. From a conceptual point of view this paper addresses the above-mentioned questions and contrasts some of the major

Carbon source in the future chemical industries

Science.gov (United States)

Hofmann, Peter; Heinrich Krauch, Carl

1982-11-01

Rising crude oil prices favour the exploitation of hitherto unutilised energy carriers and the realisation of new technologies in all sectors where carbon is used. These changed economic constraints necessitate both savings in conventional petrochemistry and a change to oil-independent carbon sources in the chemical industry. While, in coal chemistry, the synthesis and process principles of petrochemistry — fragmentation of the raw material and subsequent buildup of molecular structures — can be maintained, the raw material structure largely remains unchanged in the chemistry of renewable raw materials. This lecture is to demonstrate the structural as well as the technological and energy criteria of the chemistry of alternative carbon sources, to forecast the chances of commercial realization and to discuss some promising fields of research and development.

Synthesis of carbon-14 analogue of 1,5 diaryl-5-[{sup 14}C]-1,2,3-triazoles

Energy Technology Data Exchange (ETDEWEB)

Matloubi, Hojatollah E-mail: hmatloubi@aeoi.org.ir; Shafiee, Abbas; Saemian, Nader; Shirvani, Gholamhossein; Daha, Fariba Johari

2004-05-01

Two 1,2,3-triazole anticonvulsants, 1-(4-methylsulfone-phenyl)-5-(4-methyl-phenyl)-1,2,3-triazole and 1-(4-methylsulfone-phenyl)-5-phenyl-1,2,3-triazole, both labeled with carbon-14 in the 5-position were prepared from para-tolunitrile-[cyano-{sup 14}C] and benzonitrile-[cyano-{sup 14}C], respectively.

Revised reactor accident source terms in the U.S. and implementation for light water reactors

International Nuclear Information System (INIS)

Soffer, L.; Lee, J.Y.

1992-01-01

Current NRC reactor accident source terms used for licensing are contained in Regulatory Guides 1.3 and 1.4 and specify that 100 % of the core inventory of noble gases and 25 % of the iodine fission products are assumed to be instantaneously available for release from the containment. The chemical form of the iodine fission products is also assumed to be predominantly elemental (I 2 ) iodine. These assumptions have strongly affected present nuclear plant designs. Severe accident research results have confirmed that although the current source term is very substantial and has resulted in a very high level of plant capability, the present source term is no longer compatible with a realistic understanding of severe accidents. The NRC has issued a proposed revision of the reactor accident source terms as part of several regulatory activities to incorporate severe accident insights for future plants. A revision to 10 CFR 100 is also being proposed to specify site criteria directly and to eliminate source terms and doses for site evaluation. Reactor source terms will continue to be important in evaluating plant designs. Although intended primarily for future plants, existing and evolutionary power plants may voluntarily apply revised accident source term insights as well in licensing. The proposed revised accident source terms are presented in terms of fission product composition, magnitude, timing and iodine chemical form. Some implications for light water reactors are discussed. (author)

SOURCE TERMS FOR HLW GLASS CANISTERS

International Nuclear Information System (INIS)

J.S. Tang

2000-01-01

This calculation is prepared by the Monitored Geologic Repository (MGR) Waste Package Design Section. The objective of this calculation is to determine the source terms that include radionuclide inventory, decay heat, and radiation sources due to gamma rays and neutrons for the high-level radioactive waste (HLW) from the, West Valley Demonstration Project (WVDP), Savannah River Site (SRS), Hanford Site (HS), and Idaho National Engineering and Environmental Laboratory (INEEL). This calculation also determines the source terms of the canister containing the SRS HLW glass and immobilized plutonium. The scope of this calculation is limited to source terms for a time period out to one million years. The results of this calculation may be used to carry out performance assessment of the potential repository and to evaluate radiation environments surrounding the waste packages (WPs). This calculation was performed in accordance with the Development Plan ''Source Terms for HLW Glass Canisters'' (Ref. 7.24)

Hydrogen Transfer from Hantzsch 1,4-Dihydropyridines to Carbon-Carbon Double Bonds under Microwave Irradiation

OpenAIRE

Jean Jacques Vanden Eynde; Didier Barbry; Guy Cordonnier; Séverine Torchy

2002-01-01

1,4-Dihydropyridines (DHPs) have been used in the reduction of carbon-carbon double bonds under microwave irradiation without solvent. The efficiency of the reactions is dramatically dependent on the steric effects in the DHPs and on the electronic effects in the olefins.

Stable carbon isotope ratios: implications for the source of sediment carbon and for phytoplankton carbon assimilation in Lake Memphremagog, Quebec

International Nuclear Information System (INIS)

LaZerte, B.D.

1983-01-01

The stable carbon isotope (SCI) ratio of the sediment of Lake Memphremagog, Quebec is compared with that ot terrestrial sources and the phytoplankton to determine the relative proportion of allochthonous carbon incorporated into the sediments. Approximately 40-50% of the organic carbon in the main basins' pelagic sediment was terrestrial in origin, whereas up to 100% was terrestrial in littoral areas. The SCI method of determining the organic carbon source of sediments appears more reliable than the C/N method. A comparison of the SCI fractionation of the phytoplankton with laboratory cultures under different degrees of carbon limitation indicates that the phytoplankton of Lake Memphremagog are not carbon limited and fix carbon primarily by the C 3 pathway

Biodegradation and utilization of 4-n-nonylphenol by Aspergillus versicolor as a sole carbon and energy source

International Nuclear Information System (INIS)

Krupiński, Mariusz; Janicki, Tomasz; Pałecz, Bartłomiej; Długoński, Jerzy

2014-01-01

Highlights: • A. versicolor is able to degrade 4-n-NP as the sole source of carbon and energy. • 4-n-NP removal by A. versicolor was accompanied by the formation of metabolites. • Radioactive experiments show complete 4-n-NP mineralization by A. versicolor. • 4-n-NP initiates heat production in the A. versicolor spores. - Abstract: 4-n-Nonylphenol (4-n-NP) is an environmental pollutant with endocrine-disrupting activities that is formed during the degradation of nonylphenol polyethoxylates, which are widely used as surfactants. Utilization of 4-n-NP by the filamentous fungus Aspergillus versicolor as the sole carbon and energy source was investigated. By means of gas chromatography–mass spectrometry, we showed that in the absence of any carbon source other than 4-n-NP in the medium, A. versicolor completely removed the xenobiotic (100 mg L −1 ) after 3 d of cultivation. Moreover, mass spectrometric analysis of intracellular extracts led to the identification of eight intermediates. The mineralization of the xenobiotic in cultures supplemented with 4-n-NP [ring- 14 C(U)] as a growth substrate was also assessed. After 3 d of incubation, approximately 50% of the initially applied radioactivity was recovered in the form of 14 CO 2 , proving that this xenobiotic was completely metabolized and utilized by A. versicolor as a carbon source. Based on microscopic analysis, A. versicolor is capable of germinating spores under such conditions. To confirm these observations, a microcalorimetric method was used. The results show that even the highest amount of 4-n-NP initiates heat production in the fungal samples, proving that metabolic processes were affected by the use of 4-n-NP as an energetic substrate

Biodegradation and utilization of 4-n-nonylphenol by Aspergillus versicolor as a sole carbon and energy source

Energy Technology Data Exchange (ETDEWEB)

Krupiński, Mariusz; Janicki, Tomasz [Department of Industrial Microbiology and Biotechnology, University of Lodz, Banacha 12/16, 90-237 Łódź (Poland); Pałecz, Bartłomiej [Department of Physical Chemistry, University of Lodz, Pomorska 165, 90-236 Łódź (Poland); Długoński, Jerzy, E-mail: jdlugo@biol.uni.lodz.pl [Department of Industrial Microbiology and Biotechnology, University of Lodz, Banacha 12/16, 90-237 Łódź (Poland)

2014-09-15

Highlights: • A. versicolor is able to degrade 4-n-NP as the sole source of carbon and energy. • 4-n-NP removal by A. versicolor was accompanied by the formation of metabolites. • Radioactive experiments show complete 4-n-NP mineralization by A. versicolor. • 4-n-NP initiates heat production in the A. versicolor spores. - Abstract: 4-n-Nonylphenol (4-n-NP) is an environmental pollutant with endocrine-disrupting activities that is formed during the degradation of nonylphenol polyethoxylates, which are widely used as surfactants. Utilization of 4-n-NP by the filamentous fungus Aspergillus versicolor as the sole carbon and energy source was investigated. By means of gas chromatography–mass spectrometry, we showed that in the absence of any carbon source other than 4-n-NP in the medium, A. versicolor completely removed the xenobiotic (100 mg L{sup −1}) after 3 d of cultivation. Moreover, mass spectrometric analysis of intracellular extracts led to the identification of eight intermediates. The mineralization of the xenobiotic in cultures supplemented with 4-n-NP [ring-{sup 14}C(U)] as a growth substrate was also assessed. After 3 d of incubation, approximately 50% of the initially applied radioactivity was recovered in the form of {sup 14}CO{sub 2}, proving that this xenobiotic was completely metabolized and utilized by A. versicolor as a carbon source. Based on microscopic analysis, A. versicolor is capable of germinating spores under such conditions. To confirm these observations, a microcalorimetric method was used. The results show that even the highest amount of 4-n-NP initiates heat production in the fungal samples, proving that metabolic processes were affected by the use of 4-n-NP as an energetic substrate.

10 CFR 50.67 - Accident source term.

Science.gov (United States)

2010-01-01

... Conditions of Licenses and Construction Permits § 50.67 Accident source term. (a) Applicability. The... 10 Energy 1 2010-01-01 2010-01-01 false Accident source term. 50.67 Section 50.67 Energy NUCLEAR... to January 10, 1997, who seek to revise the current accident source term used in their design basis...

L-Lactic acid production from glucose and xylose with engineered strains of Saccharomyces cerevisiae: aeration and carbon source influence yields and productivities.

Science.gov (United States)

Novy, Vera; Brunner, Bernd; Nidetzky, Bernd

2018-04-11

Saccharomyces cerevisiae, engineered for L-lactic acid production from glucose and xylose, is a promising production host for lignocellulose-to-lactic acid processes. However, the two principal engineering strategies-pyruvate-to-lactic acid conversion with and without disruption of the competing pyruvate-to-ethanol pathway-have not yet resulted in strains that combine high lactic acid yields (Y LA ) and productivities (Q LA ) on both sugar substrates. Limitations seemingly arise from a dependency on the carbon source and the aeration conditions, but the underlying effects are poorly understood. We have recently presented two xylose-to-lactic acid converting strains, IBB14LA1 and IBB14LA1_5, which have the L-lactic acid dehydrogenase from Plasmodium falciparum (pfLDH) integrated at the pdc1 (pyruvate decarboxylase) locus. IBB14LA1_5 additionally has its pdc5 gene knocked out. In this study, the influence of carbon source and oxygen on Y LA and Q LA in IBB14LA1 and IBB14LA1_5 was investigated. In anaerobic fermentation IBB14LA1 showed a higher Y LA on xylose (0.27 g g Xyl -1 ) than on glucose (0.18 g g Glc -1 ). The ethanol yields (Y EtOH , 0.15 g g Xyl -1 and 0.32 g g Glc -1 ) followed an opposite trend. In IBB14LA1_5, the effect of the carbon source on Y LA was less pronounced (~ 0.80 g g Xyl -1 , and 0.67 g g Glc -1 ). Supply of oxygen accelerated glucose conversions significantly in IBB14LA1 (Q LA from 0.38 to 0.81 g L -1  h -1 ) and IBB14LA1_5 (Q LA from 0.05 to 1.77 g L -1  h -1 ) at constant Y LA (IBB14LA1 ~ 0.18 g g Glc -1 ; IBB14LA1_5 ~ 0.68 g g Glc -1 ). In aerobic xylose conversions, however, lactic acid production ceased completely in IBB14LA1 and decreased drastically in IBB14LA1_5 (Y LA aerobic ≤ 0.25 g g Xyl -1 and anaerobic ~ 0.80 g g Xyl -1 ) at similar Q LA (~ 0.04 g L -1  h -1 ). Switching from aerobic to microaerophilic conditions (pO 2  ~ 2%) prevented lactic acid metabolization, observed for

Analysis of 14C level around Qinshan NPP base

International Nuclear Information System (INIS)

Huang Renjie; Liang Haiyan; Chen Qianyuan; Ni Shiying; He Jun; Zeng Guangjian; Ma Yongfu

2012-01-01

By using the method of alkaline solution absorption, the activity concentrations of Carbon-14 as well as its variation tendency in air and biological samples were analyzed. The air samples and biological samples were collected around the Qinshan nuclear power plant base (Qinshan NPP Base) in 2002 to 2009 and 2007 to 2009 respectively. The results showed that, since 2002, the annual average activity concentrations of Carbon-14 in air samples were in the range of 38.3 mBq/m 3 to 55.4 mBq/m 3 . Although the monitoring results of Xiajiawan village and Yanliucun village were comparatively higher than the reference site in Hangzhou City, the results were still at the same level. Meanwhile, monitoring results of Xiajiawan village and Yangliucun village in the summer of 2004 and 2005 are relatively high, with the peak value of 55.4 mBq/m 3 appeared in Xiajiawan village during the summer of 2005. Correspondingly the annual airborne Carbon-14 of 2004 and 2005 discharged from the Qinshan NPP 3 rd Phase were higher than normal as well, it can therefore be concluded that the activity concentration of Carbon-14 around the Qinshan NPP Base are related to the discharged source term. The activity concentration of Carbon-14 in rice and leaf vegetable samples from Xiajiawan village and Yangliucun village were slightly higher, but within the same level, than that of Hangzhou. The activity concentration of Carbon-14 in the mullet samples collected from the sea area around Qinshan NPP Base are approximately the same with the sea area of Zhoushan. (authors)

Carbon-14 dating of tree rings for tritium measurement

International Nuclear Information System (INIS)

Yamada, Y.; Yasuike, K.; Kiriyama, N.; Komura, K.; Ueno, K.

1998-01-01

The carbon-14 concentration in tree-ring cellulose of an 80-year-old pine tree which has been used for tritium measurement was measured during the 1941-1987 period. This was done to determine the formation year of each tree ring in order to study the pathway of tritium uptake into the tree rings. In the 1941 to 1953 period, the δ 14 C value remained slightly lower than 0 per mille. It began to increase from 1954 to a small broad peak of 250 per mille between 1959 and 1961, followed by rapid increase to the highest value of approximately 800 per mille in 1964. Since 1964, it had been diminishing year by year to reach a level of 190 per mille in 1987. The two peak years coincided with those in the known carbon-14 patterns in tree rings. However, there existed a difference in the amplitude of the δ 14 C values during the period of 1963-1967. (author)

The lichens, tritium and carbon 14 integrators; Les lichens, integrateurs de tritium et de carbone 14

Energy Technology Data Exchange (ETDEWEB)

Daillant, O

2007-07-01

The present report concerns a research for the tritium and for the carbon 14 in lichens in a spirit of bio-indication: the first results appear in Daillant and al (2004 ) and additional results were presented to the congress B.I.O.M.A.P. in Slovenia, organized collectively by the institute Josef Stefan from Ljubljana and the international atomic energy agency from Vienna (Daillant and al 2003). (N.C.)

40 CFR 407.14 - Pretreatment standards for existing sources.

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 28 2010-07-01 2010-07-01 true Pretreatment standards for existing sources. 407.14 Section 407.14 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS CANNED AND PRESERVED FRUITS AND VEGETABLES PROCESSING POINT SOURCE...

Preparation of pyridostigmine bromide labeled with carbon-14 and tritium

Energy Technology Data Exchange (ETDEWEB)

Kepler, J.A.; Twine, C.E.; Austin, R.D. (Research Triangle Inst., Research Triangle Park, NC (United States))

1992-08-01

[2-[sup 14]C]Pyridostigmine bromide was prepared in 17.6% radiochemical yield with specific activity of 18 mCi/mmol. The reaction sequence involved preparation of 2-furan[[sup 14]C]carboxylic acid by carbonation of 2-lithiofuran, followed by conversion to 2-amino[[sup 14]C]methylfuran by lithium aluminium hydride reduction of its carboxamide. Oxidative rearrangement of 2-amino[[sup 14]C]methylfuran gave 3-hydroxy[2-[sup 14]C]pyridine which was converted to [2-[sup 14]C]pyridostigmine bromide by reaction with dimethylcarbamyl chloride and quarternization with bromomethane. Pyridostigmine bromide labeled in the methyl group of the carbamate function was prepared in 73% yield with specific activity of 37.6 mCi/mmol by reaction of bis-3-pyridyl carbonate with [[sup 14]C]dimethylamine followed by quarternization with bromomethane. [6-[sup 3]H]-Pyridostigmine bromide with specific activity of 22.5 mCi/mmol was prepared by catalytic halogen-tritium replacement of 2,6-dibromo-3-dimethylcarbamyloxypyridine followed by quarternization with bromomethane and back-exchanging the labile 2-tritium. (author).

Preparation of pyridostigmine bromide labeled with carbon-14 and tritium

International Nuclear Information System (INIS)

Kepler, J.A.; Twine, C.E.; Austin, R.D.

1992-01-01

[2- 14 C]Pyridostigmine bromide was prepared in 17.6% radiochemical yield with specific activity of 18 mCi/mmol. The reaction sequence involved preparation of 2-furan[ 14 C]carboxylic acid by carbonation of 2-lithiofuran, followed by conversion to 2-amino[ 14 C]methylfuran by lithium aluminium hydride reduction of its carboxamide. Oxidative rearrangement of 2-amino[ 14 C]methylfuran gave 3-hydroxy[2- 14 C]pyridine which was converted to [2- 14 C]pyridostigmine bromide by reaction with dimethylcarbamyl chloride and quarternization with bromomethane. Pyridostigmine bromide labeled in the methyl group of the carbamate function was prepared in 73% yield with specific activity of 37.6 mCi/mmol by reaction of bis-3-pyridyl carbonate with [ 14 C]dimethylamine followed by quarternization with bromomethane. [6- 3 H]-Pyridostigmine bromide with specific activity of 22.5 mCi/mmol was prepared by catalytic halogen-tritium replacement of 2,6-dibromo-3-dimethylcarbamyloxypyridine followed by quarternization with bromomethane and back-exchanging the labile 2-tritium. (author)

14 CFR 1274.909 - Term of agreement.

Science.gov (United States)

2010-01-01

... Agreement, which, by their express terms or by necessary implication, apply for periods of time other than... 14 Aeronautics and Space 5 2010-01-01 2010-01-01 false Term of agreement. 1274.909 Section 1274... COMMERCIAL FIRMS Other Provisions and Special Conditions § 1274.909 Term of agreement. Term of Agreement July...

Short-term variability of mineral dust, metals and carbon emission from road dust resuspension

Science.gov (United States)

Amato, Fulvio; Schaap, Martijn; Denier van der Gon, Hugo A. C.; Pandolfi, Marco; Alastuey, Andrés; Keuken, Menno; Querol, Xavier

2013-08-01

Particulate matter (PM) pollution in cities has severe impact on morbidity and mortality of their population. In these cities, road dust resuspension contributes largely to PM and airborne heavy metals concentrations. However, the short-term variation of emission through resuspension is not well described in the air quality models, hampering a reliable description of air pollution and related health effects. In this study we experimentally show that the emission strength of resuspension varies widely among road dust components/sources. Our results offer the first experimental evidence of different emission rates for mineral dust, heavy metals and carbon fractions due to traffic-induced resuspension. Also, the same component (or source) recovers differently in a road in Barcelona (Spain) and a road in Utrecht (The Netherlands). This finding has important implications on atmospheric pollution modelling, mostly for mineral dust, heavy metals and carbon species. After rain events, recoveries were generally faster in Barcelona rather than in Utrecht. The largest difference was found for the mineral dust (Al, Si, Ca). Tyre wear particles (organic carbon and zinc) recovered faster than other road dust particles in both cities. The source apportionment of road dust mass provides useful information for air quality management.

Calculation of source terms for NUREG-1150

International Nuclear Information System (INIS)

Breeding, R.J.; Williams, D.C.; Murfin, W.B.; Amos, C.N.; Helton, J.C.

1987-10-01

The source terms estimated for NUREG-1150 are generally based on the Source Term Code Package (STCP), but the actual source term calculations used in computing risk are performed by much smaller codes which are specific to each plant. This was done because the method of estimating the uncertainty in risk for NUREG-1150 requires hundreds of source term calculations for each accident sequence. This is clearly impossible with a large, detailed code like the STCP. The small plant-specific codes are based on simple algorithms and utilize adjustable parameters. The values of the parameters appearing in these codes are derived from the available STCP results. To determine the uncertainty in the estimation of the source terms, these parameters were varied as specified by an expert review group. This method was used to account for the uncertainties in the STCP results and the uncertainties in phenomena not considered by the STCP

40 CFR 425.14 - New source performance standards (NSPS).

Science.gov (United States)

2010-07-01

... 40 Protection of Environment 29 2010-07-01 2010-07-01 false New source performance standards (NSPS). 425.14 Section 425.14 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS LEATHER TANNING AND FINISHING POINT SOURCE CATEGORY Hair Pulp, Chrome Tan, Retan-Wet...

Fossil and non-fossil sources of organic carbon (OC and elemental carbon (EC in Göteborg, Sweden

Directory of Open Access Journals (Sweden)

S. Szidat

2009-03-01

Full Text Available Particulate matter was collected at an urban site in Göteborg (Sweden in February/March 2005 and in June/July 2006. Additional samples were collected at a rural site for the winter period. Total carbon (TC concentrations were 2.1–3.6 μg m⁻³, 1.8–1.9 μg m⁻³, and 2.2–3.0 μg m⁻³ for urban/winter, rural/winter, and urban/summer conditions, respectively. Elemental carbon (EC, organic carbon (OC, water-insoluble OC (WINSOC, and water-soluble OC (WSOC were analyzed for ¹⁴C in order to distinguish fossil from non-fossil emissions. As wood burning is the single major source of non-fossil EC, its contribution can be quantified directly. For non-fossil OC, the wood-burning fraction was determined independently by levoglucosan and ¹⁴C analysis and combined using Latin-hypercube sampling (LHS. For the winter period, the relative contribution of EC from wood burning to the total EC was >3 times higher at the rural site compared to the urban site, whereas the absolute concentrations of EC from wood burning were elevated only moderately at the rural compared to the urban site. Thus, the urban site is substantially more influenced by fossil EC emissions. For summer, biogenic emissions dominated OC concentrations most likely due to secondary organic aerosol (SOA formation. During both seasons, a more pronounced fossil signal was observed for Göteborg than has previously been reported for Zurich, Switzerland. Analysis of air mass origin using back trajectories suggests that the fossil impact was larger when local sources dominated, whereas long-range transport caused an enhanced non-fossil signal. In comparison to other European locations, concentrations of levoglucosan and other monosaccharide anhydrides were low for the urban and the rural site in the area of Göteborg during winter.

14 CFR 1300.15 - Loan terms.

Science.gov (United States)

2010-01-01

... 14 Aeronautics and Space 5 2010-01-01 2010-01-01 false Loan terms. 1300.15 Section 1300.15... DISASTER RELIEF-AIR CARRIER GUARANTEE LOAN PROGRAM Minimum Requirements and Application Procedures § 1300.15 Loan terms. (a) A loan guaranteed under the program shall be due and payable in full no later than...

The preparation of glucose uniformly labelled with carbon-14; Preparacion de glucosa uniformemente marcada con carbono-14

Energy Technology Data Exchange (ETDEWEB)

Garcia, M D; Suarez, C; Rodrigo, M E

1978-07-01

The plant, (Zea mais, L) and culture conditions for an optimum production of glucose has been chosen. To achieve the labelling of glucose, photosynthesis and carboxylation are carried on, under an artificial atmosphere of 14CO{sub 2} produced from 14{sup C}-barium carbonate. Following photosynthesis the sugars are extracted, and then the extract purified by several methods. The purified glucose is finally, degraded and the specific radioactivity is determined in each of its carbon atoms. (Author) 37 refs.

LOSCAR: Long-term Ocean-atmosphere-Sediment CArbon cycle Reservoir Model v2.0.4

Directory of Open Access Journals (Sweden)

R. E. Zeebe

2012-01-01

Full Text Available The LOSCAR model is designed to efficiently compute the partitioning of carbon between ocean, atmosphere, and sediments on time scales ranging from centuries to millions of years. While a variety of computationally inexpensive carbon cycle models are already available, many are missing a critical sediment component, which is indispensable for long-term integrations. One of LOSCAR's strengths is the coupling of ocean-atmosphere routines to a computationally efficient sediment module. This allows, for instance, adequate computation of CaCO₃ dissolution, calcite compensation, and long-term carbon cycle fluxes, including weathering of carbonate and silicate rocks. The ocean component includes various biogeochemical tracers such as total carbon, alkalinity, phosphate, oxygen, and stable carbon isotopes. LOSCAR's configuration of ocean geometry is flexible and allows for easy switching between modern and paleo-versions. We have previously published applications of the model tackling future projections of ocean chemistry and weathering, pCO₂ sensitivity to carbon cycle perturbations throughout the Cenozoic, and carbon/calcium cycling during the Paleocene-Eocene Thermal Maximum. The focus of the present contribution is the detailed description of the model including numerical architecture, processes and parameterizations, tuning, and examples of input and output. Typical CPU integration times of LOSCAR are of order seconds for several thousand model years on current standard desktop machines. The LOSCAR source code in C can be obtained from the author by sending a request to loscar.model@gmail.com.

Assessing the Resilience of a Blue Carbon Store: Characterizing the Lateral Flux of DIC from an East Coast U.S. Saltmarsh using Δ14C and δ13C

Science.gov (United States)

Felgate, S. L.; Gonneea, M. E.; Kroeger, K. D.; Chu, S. N.; Wang, A. Z.

2016-12-01

Intertidal saltmarshes are highly productive coastal habitats and important blue carbon stores. They commonly exhibit high salinity, low oxygen environmental regimes which lend themselves towards reduced rates of microbial respiration, and the assimilation of atmospheric CO2 into plant biomass tends to outpace the rate at which that biomass is broken down. As a result, a relatively high proportion of CO2 entering the system can be expected to become incorporated into marsh sediment before it can be metabolised, potentially entering storage for thousands of years and providing a sizeable natural carbon sink. However, the rate at which these habitats are now being degraded is substantial and growing: the combined impacts of stressors such as increasing temperature and sea level rise are predicted to reduce global saltmarsh coverage by 30-40% by the end of the century, and many saltmarsh carbon stores can be expected to shift from net sinks to sources within the same time frame. Based on high resolution measurements and modelling in a northeastern U.S. saltmarsh, a recent study reported a marsh DIC export of 414g C m2 yr-1. This is more than twice that put forward in previous estimates, and is larger than the total uptake by plant biomass. This translates into one of the largest carbon fluxes to the coastal ocean found along the U.S. East Coast. Additionally it is possible that the marsh carbon budget is not in balance, with export exceeding carbon fixation rates. Here we characterise this carbon flux using Δ14C and δ13C data to age and source the exported dissolved carbon pools. Carbon isotope mixing models between surface (modern) and porewater (old) carbon sources are constrained by creek samples and porewaters from multiple depths and locations within the marsh. We determine the age of exported carbon to see if carbon stored over the lifetime of the marsh (c. 2000 years) continues to be respired, thereby evaluating the long term resilience of the carbon sink.

Metabolic engineering of Corynebacterium glutamicum aimed at alternative carbon sources and new products

Directory of Open Access Journals (Sweden)

Volker Fritz Wendisch

2012-10-01

Full Text Available Corynebacterium glutamicum is well known as the amino acid-producing workhorse of fermentation industry, being used for multi-million-ton scale production of glutamate and lysine for more than 60 years. However, it is only recently that extensive research has focused on engineering it beyond the scope of amino acids. Meanwhile, a variety of corynebacterial strains allows access to alternative carbon sources and/or allows production of a wide range of industrially relevant compounds. Some of these efforts set new standards in terms of titers and productivities achieved whereas others represent a proof-of-principle. These achievements manifest the position of C. glutamicum as an important industrial microorganism with capabilities far beyond the traditional amino acid production. In this review we focus on the state of the art of metabolic engineering of C. glutamicum for utilization of alternative carbon sources, (e.g. coming from wastes and unprocessed sources, and construction of C. glutamicum strains for production of new products such as diamines, organic acids and alcohols.

Subsurface Shielding Source Term Specification Calculation

International Nuclear Information System (INIS)

S.Su

2001-01-01

The purpose of this calculation is to establish appropriate and defensible waste-package radiation source terms for use in repository subsurface shielding design. This calculation supports the shielding design for the waste emplacement and retrieval system, and subsurface facility system. The objective is to identify the limiting waste package and specify its associated source terms including source strengths and energy spectra. Consistent with the Technical Work Plan for Subsurface Design Section FY 01 Work Activities (CRWMS M and O 2001, p. 15), the scope of work includes the following: (1) Review source terms generated by the Waste Package Department (WPD) for various waste forms and waste package types, and compile them for shielding-specific applications. (2) Determine acceptable waste package specific source terms for use in subsurface shielding design, using a reasonable and defensible methodology that is not unduly conservative. This calculation is associated with the engineering and design activity for the waste emplacement and retrieval system, and subsurface facility system. The technical work plan for this calculation is provided in CRWMS M and O 2001. Development and performance of this calculation conforms to the procedure, AP-3.12Q, Calculations

Alluvial Mountain Meadow Source-Sink Dynamics: Land-Cover Effects on Water and Fluvial Carbon Export

Science.gov (United States)

Weiss, T.; Covino, T. P.; Wohl, E.; Rhoades, C.; Fegel, T.; Clow, D. W.

2017-12-01

Fluvial networks of historically glaciated mountain landscapes alternate between confined and unconfined valley segments. In low-gradient unconfined reaches, river-connected wet meadows commonly establish, and have been recognized as important locations of long-term water, carbon, and nutrient storage. Among connected meadow floodplains, sink-source behavior shifts as a function of flow state; storing water at high flows (snowmelt) and contributing toward higher late-season baseflows. Despite these benefits, historical and contemporary land-use practices often result in the simplification of wet meadow systems, leading to reduced river-floodplain connectivity, lower water-tables and reductions in hydrologic buffering capacity. In this study, we are exploring hydrologic-carbon relationships across a gradient of valley confinement and river-floodplain connectivity (connected, n=3; disconnected, n=4) within the Colorado Rockies. Our approach includes hydrologic analysis, fluorometric assays, water chemistry, instream metabolic measures, and land-cover assessment to examine patterns between land-form, carbon quantity and quality, and stream ecosystem productivity. Between different meadow types, preliminary results suggest differences between instream productivity, carbon qualities, and hydrologic-carbon sink-source dynamics across the season. These data and analyses will provide insight into water, carbon and nutrient flux dynamics as a function of land-cover in mountain headwaters.

Short Term vs Long Term Environmental Reconstruction from Carbonated Deposits of the Limagne Area (Massif Central, France)

Energy Technology Data Exchange (ETDEWEB)

Barbecot, F.; Gibert, E.; Amokrane, Y.; Massault, M.; Noret, A. [Centre National de la Recherche Scientifique Interaction et Dynamique des Environnements de Surface, Universite Paris (France); Ghaleb, B. [Geotop, Universite du Quebec a Montreal, Montreal (Canada)

2013-07-15

A 80 cm sequence has been cored from carbonated travertine in the limagne area (French Massif Central, France) in order to document recent environmental fluctuations (0-100 a) of gaseous springs, in relation to the environmental and geochemical parameters that control the isotopic signatures of modern carbonate deposits. The chronology of these finely laminated deposits that are ideal for reconstructing hydrological conditions at very narrow time steps is determined through AMS-{sup 14}C and {sup 210}Pb/{sup 226}Ra radiometric methods. Preliminary results highlight a high enrichment in stable isotopes (eg up to +8 per mille vs VPDB for {delta}{sup 13}C), likely linked to both recharge temperature and degassing processes. Moreover, two general trends are superimposed: the first one, cyclic, may be correlated to the hydrologic annual/biannual budget while the second one, linear, implies a long term environmental trend. (author)

ORIGIN OF PALMITIC ACID CARBON IN PALMITATES FORMED FROM HEXADECANE-1-C14 AND TETRADECANE-1-C14 BY MICROCOCCUS CERIFICANS

Science.gov (United States)

Finnerty, W. R.; Kallio, R. E.

1964-01-01

Finnerty, W. R. (University of Iowa, Iowa City), and R. E. Kallio. Origin of palmitic acid carbon in palmitates formed from hexadecane-1-C14 and tetradecane-1-C14 by Micrococcus cerificans. J. Bacteriol. 87:1261–1265. 1964.—Degradation of the palmitic acid moiety of cetyl palmitate and myristyl palmitate formed from hexadecane-1-C14 and tetradecane-1-C14 by Micrococcus cerificans was carried out. The patterns of C14 labeling in palmitic acid from cetyl palmitate showed that hexadecane is oxidized at the C1 position, and cetyl alcohol and palmitic acid thus formed are directly esterified. Palmitic acid arising from tetradecane and esterified to tetradecanol appeared to have been synthesized by the addition of two carbon atoms to an existing 14-carbon atom skeleton. Considerable mixing of C14 occurred in the C1 and C2 positions of palmitic acid thus synthesized. PMID:14188700

A detective from the past called carbon 14; Un detective del pasado llamado carbono 14

Energy Technology Data Exchange (ETDEWEB)

Trintan, R. M.

2015-07-01

The analysis is carried out using Radiometry or Accelerator mass spectrometry. After the system allowing to date the age of any organic rest - whether a fossil, a wood fragment, a parchment or a seed - is an isotope called carbon-14. An atom that comes from reactions nuclear produced in the atmosphere and cosmic-ray-induced they interact with oxygen to form carbon dioxide. This element they absorb it plants in photosynthesis and then passes to the animals remained almost unchanged during the life of the organism. to the meet the initial ratio of c-14 that had been in the atmosphere before his death, the remains that are left in it determine the elapsed time. (Author)

ITER Safety Task NID-5A, Subtask 1-1: Source terms and energies - initial tritium source terms. Final report

International Nuclear Information System (INIS)

Fong, C.; Kalyanam, K.M.; Tanaka, M.R.; Sood, S.; Natalizio, A.; Delisle, M.

1995-02-01

The overall objective of the Early Safety and Environmental Characterization Study (ESECS) is to assess the environmental impact of tritium using appropriate assumptions on a hypothetical site for ITER, having the r eference s ite characteristics as proposed by the JCT. The objective of this work under the above subtask 1-1, NID-5a, is to determine environmental source terms (i.e., process source term x containment release fraction) for the fuel cycle and cooling systems. The work is based on inventories and process source terms (i.e., inventory x mobilization fraction), provided by others (under Task NID 3b). The results of this work form the basis for the determination, by others, of the off-site dose (i.e., environmental source term x dose/release ratio). For the determination of the environmental source terms, the TMAP4 code has been utilized (ref 1). This code is approved by ITER for safety assessment. Volume 3 is a compilation of appendices giving detailed results of the study

ITER Safety Task NID-5A, Subtask 1-1: Source terms and energies - initial tritium source terms. Final report

International Nuclear Information System (INIS)

Fong, C.; Kalyanam, K.M.; Tanaka, M.R.; Sood, S.; Natalizio, A.; Delisle, M.

1995-02-01

The overall objective of the Early Safety and Environmental Characterization Study (ESECS) is to assess the environmental impact of tritium using appropriate assumptions on a hypothetical site for ITER, having the r eference s ite characteristics as proposed by the JCT. The objective of this work under the above subtask 1-1, NID-5a, is to determine environmental source terms (i.e., process source term x containment release fraction) for the fuel cycle and cooling systems. The work is based on inventories and process source terms (i.e., inventory x mobilization fraction), provided by others (under Task NID 3b). The results of this work form the basis for the determination, by others, of the off-site dose (i.e., environmental source term x dose/release ratio). For the determination of the environmental source terms, the TMAP4 code has been utilized (ref 1). This code is approved by ITER for safety assessment. 6 refs

Modelling accidental releases of carbon 14 in the environment: application as an excel spreadsheet

International Nuclear Information System (INIS)

Le Dizes, S.; Tamponnet, C.

2004-01-01

An application as an Excel spreadsheet of the simplified modelling approach of carbon 14 transfer in the environment developed by Tamponnet (2002) is presented. Based on the use of growth models of biological systems (plants, animals, etc.), the one-pool model (organic carbon) that was developed estimates the concentration of carbon 14 within the different compartments of the food chain and in fine the dose to man by ingestion in the case of a chronic or accidental release of carbon 14 in a river or the atmosphere. Data and knowledge have been implemented on Excel using the object-oriented programming language VisualBasic (Microsoft Visual Basic 6.0). The structure of the conceptual model and the Excel sheet are first briefly exposed. A numerical application of the model under a scenario of an accidental release of carbon 14 in the atmosphere is then presented. Simulation results and perspectives are discussed. (author)

[Variation characteristics of soil carbon sequestration under long-term different fertilization in red paddy soil].

Science.gov (United States)

Huang, Jing; Zhang, Yang-zhu; Gao, Ju-sheng; Zhang, Wen-ju; Liu, Shu-jun

2015-11-01

The objective of this study was to clarify the changes of soil organic carbon (SOC) content, the saturation capacity of soil carbon sequestration and its cooperation with carbon input (crop source and organic fertilizer source carbon) under long-term (1982-2012) different fertilization in red paddy soil. The results showed that fertilization could increase SOC content. The SOC content of all the fertilization treatments demonstrated a trend of stabilization after applying fertilizer for 30 years. The SOC content in the treatments applying organic manure with mineral fertilizers was between 21.02 and 21.24 g · kg(-1), and the increase rate ranged from 0.41 to 0.59 g · kg(-1) · a(-1). The SOC content in the treatments applying mineral fertilizers only was 15.48 g · kg(-1). The average soil carbon sequestration in the treatments that applied organic manure with mineral fertilizers ranged from 43.61 to 48.43 t C · hm(-2), and the average SOC storage over the years in these treatments was significantly greater than those applying mineral fertilizers only. There was an exponentially positive correlation between C sequestration efficiency and annual average organic C input. It must input exogenous organic carbon at least at 0. 12 t C · hm(-2) · a(-1) to maintain the balance of soil organic carbon under the experimental conditions.

Carbon-14 as an indicator of CO2 pollution in cities

International Nuclear Information System (INIS)

Vogel, J.C.; Uhlitzsch, I.

1975-01-01

The combustion of fossil fuels in cities, and especially in industrial areas, releases large quantities of carbon dioxide into the local atmosphere. This carbon dioxide does not contain carbon-14, with the result that the carbon-14 content of the atmospheric carbon dioxide is locally depleted. The degree of depletion provides a measure for the carbon dioxide pollution at the sampling site. Since growing plants represent a convenient average sample of the carbon dioxide in the air, the leaves of deciduous trees can be used for comparing the magnitude of local pollution in different localities during the summer growing period. A series of leaf samples collected in 1973 from Europe, North America and South Africa reveals the expected differences in the degree of pollution. Extreme instances occur in Scholven (Ruhrgebiet, Germany), where the average day-time carbon dioxide content during the summer months is found to be 8.7% above normal, and in Manhatten, New York City, where the corresponding figure is 6.4%. The technique can easily be extended to include the winter months by directly absorbing carbon dioxide in a hydroxide solution during different seasons. The proposed method is sensitive but much less time-consuming than the continuous measurement of the carbon dioxide concentration in the air. It thus lends itself to the monitoring of impact areas of pollution. (author)

Effect of carbon dioxide and bicarbonate as inorganic carbon sources on growth and adaptation of autohydrogenotrophic denitrifying bacteria

International Nuclear Information System (INIS)

Ghafari, Shahin; Hasan, Masitah; Aroua, Mohamed Kheireddine

2009-01-01

Acclimation of autohydrogenotrophic denitrifying bacteria using inorganic carbon source (CO 2 and bicarbonate) and hydrogen gas as electron donor was performed in this study. In this regard, activated sludge was used as the seed source and sequencing batch reactor (SBR) technique was applied for accomplishing the acclimatization. Three distinct strategies in feeding of carbon sources were applied: (I) continuous sparging of CO 2 , (II) bicarbonate plus continuous sparging of CO 2 , and (III) only bicarbonate. The pH-reducing nature of CO 2 showed an unfavorable impact on denitrification rate; however bicarbonate resulted in a buffered environment in the mixed liquor and provided a suitable mean to maintain the pH in the desirable range of 7-8.2. As a result, bicarbonate as the only carbon source showed a faster adaptation, while carbon dioxide as the only carbon source as well as a complementary carbon source added to bicarbonate resulted in longer acclimation period. Adapted hydrogenotrophic denitrifying bacteria, using bicarbonate and hydrogen gas in the aforementioned pH range, caused denitrification at a rate of 13.33 mg NO 3 - -N/g MLVSS/h for degrading 20 and 30 mg NO 3 - -N/L and 9.09 mg NO 3 - -N/g MLVSS/h for degrading 50 mg NO 3 - -N/L

Carbon-14 labelling of biomolecules induced by 14CO ionized gas

International Nuclear Information System (INIS)

Lier, J.E. van; Sanche, L.

1979-01-01

Ionized 14 CO gas provides a rapid method for producing 14 C-labelled biomolecules. The apparatus consists of a high vacuum system in which a small amount of 14 CO is ionized by electron impact. The resulting species drift towards a target where they interact with the molecule of interest to produce 14 C-labelled compounds. Since the reaction time is only 2 minutes, the method is particularly promising for producing tracer biomolecules with short-lived 11 C at high specific activities. The applicability of the method to various classes of compounds of biological importance, including steroids, alkaloids, prostaglandins, nucleosides, amino acids and proteins has been studied. All compounds treated gave rise to 14 C addition and degradation products. Furthermore, for some compounds, chromatographic analysis in multiple systems followed by derivatization and crystallization to constant specific activity, indicated that carbon exchange may occur to produce the labelled, but otherwise unaltered substrate in yields of the order of 10-100 mCi/mol. More conclusive proof of radiochemical identity must await production of larger quantities of material and rigorous purification including at least two different chromatographic techniques. (author)

Constraining the sources and cycling of dissolved organic carbon in a large oligotrophic lake using radiocarbon analyses

Science.gov (United States)

Zigah, Prosper K.; Minor, Elizabeth C.; McNichol, Ann P.; Xu, Li; Werne, Josef P.

2017-07-01

We measured the concentrations and isotopic compositions of solid phase extracted (SPE) dissolved organic carbon (DOC) and high molecular weight (HMW) DOC and their constituent organic components in order to better constrain the sources and cycling of DOC in a large oligotrophic lacustrine system (Lake Superior, North America). SPE DOC constituted a significant proportion (41-71%) of the lake DOC relative to HMW DOC (10-13%). Substantial contribution of 14C-depleted components to both SPE DOC (Δ14C = 25-43‰) and HMW DOC (Δ14C = 22-32‰) was evident during spring mixing, and depressed their radiocarbon values relative to the lake dissolved inorganic carbon (DIC; Δ14C ∼ 59‰). There was preferential removal of 14C-depleted (older) and thermally recalcitrant components from HMW DOC and SPE DOC in the summer. Contemporary photoautotrophic addition to HMW DOC was observed during summer stratification in contrast to SPE DOC, which decreased in concentration during stratification. Serial thermal oxidation radiocarbon analysis revealed a diversity of sources (both contemporary and older) within the SPE DOC, and also showed distinct components within the HMW DOC. The thermally labile components of HMW DOC were 14C-enriched and are attributed to heteropolysaccharides (HPS), peptides/amide and amino sugars (AMS) relative to the thermally recalcitrant components reflecting the presence of older material, perhaps carboxylic-rich alicyclic molecules (CRAM). The solvent extractable lipid-like fraction of HMW DOC was very 14C-depleted (as old as 1270-2320 14C years) relative to the carbohydrate-like and protein-like substances isolated by acid hydrolysis of HMW DOC. Our data constrain relative influences of contemporary DOC and old DOC, and DOC cycling in a modern freshwater ecosystem.

Determination of 14C age of inorganic and organic carbon in ancient Siberian permafrost

Science.gov (United States)

Onstott, T. C.; Liang, R.; Lau, M.; Vishnivetskaya, T. A.; Lloyd, K. G.; Pfiffner, S. M.; Hodgins, G.; Rivkina, E.

2017-12-01

Permafrost represents a large reservoir of ancient carbon that could have an important impact on the global carbon budget during climate warming. Due to the low turnover rate of carbon by microorganisms at subzero temperatures, the persistence of ancient carbon in younger permafrost deposits could also pose challenges for radiocarbon dating of permafrost sediment. We utilized Accelerator Mass Spectrometry to determine the 14C age of inorganic carbon, labile and recalcitrant organic carbon in Siberian permafrost sediment sampled at various depths from 2.9 to 5.6m. The fraction of inorganic carbon (CO2) was collected after acidification using phosphoric acid. The labile (younger) and recalcitrant (old) organic carbon in the subsequent residues were collected after combustion at 400 ºC and 800 ºC, respectively. The percentages of inorganic carbon increased from the youngest (2.9m) to the oldest (5.6m), whereas the fractions for organic carbon varied significantly at different depths. The 14C age determined in the inorganic fraction in the top sample (2.9 m) was 21,760 yr BP and gradually increased to 33,900 yr BP in the relative deeper sediment (3.5 and 5.6 m). Surprisingly, the fraction of "younger" carbon liberated at 400 oC was older than the more recalcitrant and presumably older organic carbon liberated at 800 oC in all cases. Moreover, the 14C age of the younger and older organic carbon fractions did not increase with depth as observed in the carbonate fraction. In particular, the 14C age of the organic carbon in the top sample (38,590-41,700 yr BP) was much older than the deeper samples at depth of 3.5m (18,228-20,158 yr BP) and 5.6m (29,040-38,020 yr BP). It should be noticed that the metabolism of ancient carbon in frozen permafrost may vary at different depths due to the different proportion of necromass and metabolically active microbes. Therefore, additional knowledge about the carbon dynamics of permafrost and more investigation would be required to

Validation test for carbon-14 migration and accumulation in a Canadian shield lake

International Nuclear Information System (INIS)

Bird, G.A.

1996-09-01

This particular BIOMOVS II Technical Report is concerned with modelling the transfer of C-14 through the aquatic food chain following release to a Canadian shield lake. Model performance has been tested against field data supplied by Atomic Energy of Canada Limited. Carbon-14 was added in 1978 to the epilimnion of a small Canadian Shield lake to investigate primary production and carbon dynamics. Data from this experiment were used within BIOMOVS II to provide a validation test, which involved modelling the fate of the C-14 added to the lake. The nature of the spike and the subsequent monitoring allowed the investigation of both short-term processes relevant to evaluation of the impacts of accidental releases as well as longer-term processes relevant to routine release and to solid waste disposal. Four models participated in the scenario: 1) a simple mass balance model of a lake (AECL, Whiteshell Laboratories, Canada); 2) a relatively complex deterministic dynamic compartment model (QuantiSci Ltd.,UK); 3) a complex deterministic model (Studsvik Model A) and a more complex probabilistic model (Studsvik Model B; Studsvik Eco and Safety AB, Sweden). Endpoints were C-14 concentrations in water, sediment and whitefish over a thirteen year period. Each model produced reasonable predictions when compared to the observed data and when uncertainty is taken into consideration. About 0.2 to 0.4% of the initial C-14 inventory to the lakes remained in the water at the end of the study, because of internal recycling of C-14 from sediments. The simple AECL model did not account for this internal recycling of C-14 and, in this respect, its predictions were not as realistic as those of the QuantiSci and Studsvik models for concentrations in water. However, the AECL model predictions for the C-14 inventory remaining in lake sediment were closest to the observed values. Overall, Studsvik Model B was the most accurate in simulating C-14 concentrations in water and in whitefish, but

Validation test for carbon-14 migration and accumulation in a Canadian shield lake

Energy Technology Data Exchange (ETDEWEB)

Bird, G.A. [AECL, Pinawa, MB (Canada). Whiteshell Labs.] [and others

1996-09-01

This particular BIOMOVS II Technical Report is concerned with modelling the transfer of C-14 through the aquatic food chain following release to a Canadian shield lake. Model performance has been tested against field data supplied by Atomic Energy of Canada Limited. Carbon-14 was added in 1978 to the epilimnion of a small Canadian Shield lake to investigate primary production and carbon dynamics. Data from this experiment were used within BIOMOVS II to provide a validation test, which involved modelling the fate of the C-14 added to the lake. The nature of the spike and the subsequent monitoring allowed the investigation of both short-term processes relevant to evaluation of the impacts of accidental releases as well as longer-term processes relevant to routine release and to solid waste disposal. Four models participated in the scenario: (1) a simple mass balance model of a lake (AECL, Whiteshell Laboratories, Canada); (2) a relatively complex deterministic dynamic compartment model (QuantiSci Ltd.,UK); (3) a complex deterministic model (Studsvik Model A) and a more complex probabilistic model (Studsvik Model B; Studsvik Eco and Safety AB, Sweden). Endpoints were C-14 concentrations in water, sediment and whitefish over a thirteen year period. Each model produced reasonable predictions when compared to the observed data and when uncertainty is taken into consideration. About 0.2 to 0.4% of the initial C-14 inventory to the lakes remained in the water at the end of the study, because of internal recycling of C-14 from sediments. The simple AECL model did not account for this internal recycling of C-14 and, in this respect, its predictions were not as realistic as those of the QuantiSci and Studsvik models for concentrations in water. However, the AECL model predictions for the C-14 inventory remaining in lake sediment were closest to the observed values. Overall, Studsvik Model B was the most accurate in simulating C-14 concentrations in water and in whitefish, but

ITER Safety Task NID-5A, Subtask 1-1: Source terms and energies - initial tritium source terms. Final report

International Nuclear Information System (INIS)

Fong, C.; Kalyanam, K.M.; Tanaka, M.R.; Sood, S.; Natalizio, A.; Delisle, M.

1995-02-01

The overall objective of the Early Safety and Environmental Characterization Study (ESECS) is to assess the environmental impact of tritium using appropriate assumptions on a hypothetical site for ITER, having the r eference s ite characteristics as proposed by the JCT. The objective of this work under the above subtask 1-1, NID-5a, is to determine environmental source terms (i.e., process source term x containment release fraction) for the fuel cycle and cooling systems. The work is based on inventories and process source terms (i.e., inventory x mobilization fraction), provided by others (under Task NID 3b). The results of this work form the basis for the determination, by others, of the off-site dose (i.e., environmental source term x dose/release ratio). For the determination of the environmental source terms, the TMAP4 code has been utilized (ref 1). This code is approved by ITER for safety assessment. Volume 2 is a compilation of appendices giving detailed results of the study. 5 figs

Modelling the Environmental Transfer of Tritium and Carbon-14 to Biota and Man. Report of the Tritium and Carbon-14 Working Group of EMRAS Theme 1

International Nuclear Information System (INIS)

2012-01-01

Hydrogen and carbon are biologically-regulated, essential elements that are highly mobile in the environment and the human body. As isotopes of these elements, tritium and 14 C enter freely into water (in the case of tritium), plants, animals and humans. This complex behaviour means that there are substantial uncertainties in the predictions of models that calculate the transfer of tritium and 14 C through the environment. The EMRAS Tritium/C14 Working Group (WG) was set up to establish the confidence that can be placed in the predictions of such models, to recommend improved modelling approaches, and to encourage experimental work leading to the development of data sets for model testing. The activities of the WG focused on the assessment of models for organically bound tritium (OBT) formation and translocation in plants and animals, the area where model uncertainties are largest. Environmental 14 C models were also addressed because the dynamics of carbon and OBT are similar. The goals of the WG were achieved primarily through nine test scenarios in which model predictions were compared with observations obtained in laboratory or field studies. Seven of the scenarios involved tritium, covering terrestrial and aquatic ecosystems and steady-state and dynamic conditions. The remaining two scenarios concerned 14 C, one addressing steady-state concentrations in plants and the other time-dependent concentrations in animals. The WG also considered one model intercomparison exercise involving the calculation of doses following a hypothetical, short-term release of tritium to the atmosphere in a farming area. Finally, the WG discussed the nature of OBT and proposed a definition to promote common understanding and usage within the international tritium community. The models used by the various participants varied in complexity from simple specific activity approaches to dynamic compartment models and process-oriented models, in which the various transfer processes were

Modelling the Environmental Transfer of Tritium and Carbon-14 to Biota and Man. Report of the Tritium and Carbon-14 Working Group of EMRAS Theme 1

Energy Technology Data Exchange (ETDEWEB)

NONE

2012-06-15

Hydrogen and carbon are biologically-regulated, essential elements that are highly mobile in the environment and the human body. As isotopes of these elements, tritium and {sup 14}C enter freely into water (in the case of tritium), plants, animals and humans. This complex behaviour means that there are substantial uncertainties in the predictions of models that calculate the transfer of tritium and {sup 14}C through the environment. The EMRAS Tritium/C14 Working Group (WG) was set up to establish the confidence that can be placed in the predictions of such models, to recommend improved modelling approaches, and to encourage experimental work leading to the development of data sets for model testing. The activities of the WG focused on the assessment of models for organically bound tritium (OBT) formation and translocation in plants and animals, the area where model uncertainties are largest. Environmental {sup 14}C models were also addressed because the dynamics of carbon and OBT are similar. The goals of the WG were achieved primarily through nine test scenarios in which model predictions were compared with observations obtained in laboratory or field studies. Seven of the scenarios involved tritium, covering terrestrial and aquatic ecosystems and steady-state and dynamic conditions. The remaining two scenarios concerned {sup 14}C, one addressing steady-state concentrations in plants and the other time-dependent concentrations in animals. The WG also considered one model intercomparison exercise involving the calculation of doses following a hypothetical, short-term release of tritium to the atmosphere in a farming area. Finally, the WG discussed the nature of OBT and proposed a definition to promote common understanding and usage within the international tritium community. The models used by the various participants varied in complexity from simple specific activity approaches to dynamic compartment models and process-oriented models, in which the various

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

Energy Technology Data Exchange (ETDEWEB)

Hershey, Ronald L. [Nevada University, Reno, NV (United States). Desert Research Institute; Fereday, Wyall [Nevada University, Reno, NV (United States). Desert Research Institute; Thomas, James M [Nevada University, Reno, NV (United States). Desert Research Institute

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

Aerosol behavior and light water reactor source terms

International Nuclear Information System (INIS)

Abbey, F.; Schikarski, W.O.

1988-01-01

The major developments in nuclear aerosol modeling following the accident to pressurized water reactor Unit 2 at Three Mile Island are briefly reviewed and the state of the art summarized. The importance and implications of these developments for severe accident source terms for light water reactors are then discussed in general terms. The treatment is not aimed at identifying specific source term values but is intended rather to illustrate trends, to assess the adequacy of the understanding of major aspects of aerosol behavior for source term prediction, and demonstrate in qualitative terms the effect of various aspects of reactor design. Areas where improved understanding of aerosol behavior might lead to further reductions in current source terms predictions are also considered

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

International Nuclear Information System (INIS)

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

2010-01-01

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

Sources of C-14 generation and associated doses; Fuentes de generacion de C-14 y dosis asociadas

Energy Technology Data Exchange (ETDEWEB)

Amado, Valeria A; Biaggio, Alfredo L; Canoba, Analia C; Curti, Adriana R. [Autoridad Regulatoria Nuclear, Buenos Aires (Argentina)], E-mail: vamado@cae.arn.gov.ar

2009-07-01

C-14 is a radioactive isotope of C with a half-life of 5700 years that decays to N-14 by emission of beta radiation. It is naturally produced in the upper atmosphere by cosmic ray neutrons via the (n;p) reaction over N-14. Anthropogenic C-14 has been generated in the past by atmospheric nuclear weapon tests and it is currently produced during the operation of nuclear reactors. Once released this radionuclide behaves in the biosphere as the standard carbon cycle. Since the beginning of the industrial period the relationship Carbon-14/Stable Carbon has changed continuously, and so the dose incurred by the world population. In this paper the main anthropogenic activities that modified such relationship are presented and analyzed: the Suess effect and the generation of nuclear energy. It is concluded that the current trend of reduction of the total dose due to C-14 will continue during the next decades. Finally it is indicated that in order to prevent an excessive accumulation of this radionuclide in the biosphere, actions should be collectively implemented to be effective. (author) [Spanish] El C-14 es un isotopo radiactivo del C con un periodo de semidesintegracion igual a 5700 anios y que decae a N-14 por emision de radiacion beta. Se produce naturalmente en las altas capas de la atmosfera debido a la reaccion N-14(n,p)C-14 inducida por neutrones lentos de rayos cosmicos. El C-14 antropogenico se genero debido a los ensayos nucleares y actualmente es producido durante la operacion de los reactores nucleares. Una vez liberado se incorpora a la biosfera a traves del ciclo del carbono. A partir de los inicios del periodo industrial la relacion C-14/C-estable, y por ende la dosis debida a C-14 que recibiria la poblacion mundial, ha variado continuamente. El objetivo del presente trabajo es presentar y analizar los distintos factores antropogenicos que modifican la concentracion de C-14, en particular el efecto Suess y la generacion de energia nuclear. Se observa que las

Effect of carbon dioxide and bicarbonate as inorganic carbon sources on growth and adaptation of autohydrogenotrophic denitrifying bacteria

Energy Technology Data Exchange (ETDEWEB)

Ghafari, Shahin; Hasan, Masitah [Department of Chemical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia); Aroua, Mohamed Kheireddine [Department of Chemical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur (Malaysia)], E-mail: mk_aroua@um.edu.my

2009-03-15

Acclimation of autohydrogenotrophic denitrifying bacteria using inorganic carbon source (CO{sub 2} and bicarbonate) and hydrogen gas as electron donor was performed in this study. In this regard, activated sludge was used as the seed source and sequencing batch reactor (SBR) technique was applied for accomplishing the acclimatization. Three distinct strategies in feeding of carbon sources were applied: (I) continuous sparging of CO{sub 2}, (II) bicarbonate plus continuous sparging of CO{sub 2}, and (III) only bicarbonate. The pH-reducing nature of CO{sub 2} showed an unfavorable impact on denitrification rate; however bicarbonate resulted in a buffered environment in the mixed liquor and provided a suitable mean to maintain the pH in the desirable range of 7-8.2. As a result, bicarbonate as the only carbon source showed a faster adaptation, while carbon dioxide as the only carbon source as well as a complementary carbon source added to bicarbonate resulted in longer acclimation period. Adapted hydrogenotrophic denitrifying bacteria, using bicarbonate and hydrogen gas in the aforementioned pH range, caused denitrification at a rate of 13.33 mg NO{sub 3}{sup -}-N/g MLVSS/h for degrading 20 and 30 mg NO{sub 3}{sup -}-N/L and 9.09 mg NO{sub 3}{sup -}-N/g MLVSS/h for degrading 50 mg NO{sub 3}{sup -}-N/L.

Immobilization of carbon 14 contained in spent fuel hulls through melting-solidification treatment

International Nuclear Information System (INIS)

Mizuno, T.; Maeda, T.; Nakayama, S.; Banba, T.

2004-01-01

The melting-solidification treatment of spent nuclear fuel hulls is a potential technique to improve immobilization/stabilization of carbon-14 which is mobile in the environment due to its weakly absorbing properties. Carbon-14 can be immobilized in a solid during the treatment under an inert gas atmosphere, where carbon is not oxidized to gaseous form and remains in the solid. A series of laboratory scale experiments on retention of carbon into an alloy waste form was conducted. Metallic zirconium was melted with metallic copper (Zr/Cu=8/2 in weight) at 1200 deg C under an argon atmosphere. Almost all of the carbon remained in the resulting zirconium-copper alloy. (authors)

Production of bacterial cellulose using different carbon sources and culture media.

Science.gov (United States)

Mohammadkazemi, Faranak; Azin, Mehrdad; Ashori, Alireza

2015-03-06

In this work, the effects of carbon sources and culture media on the production and structural properties of bacterial cellulose (BC) have been studied. BC nanofibers were synthesized using Gluconacetobacter xylinus strain PTCC 1734. Media used were Hestrin-Schramm (H), Yamanaka (Y), and Zhou (Z). Five different carbon sources, namely date syrup, glucose, mannitol, sucrose, and food-grade sucrose were used in these media. All the produced BC pellicles were characterized in terms of dry weight production, biomass yield, thermal stability, crystallinity and morphology by thermogravimetric analysis (TGA), x-ray diffraction (XRD), and field emission scanning electron microscopy (FE-SEM). The obtained results showed that mannitol lead to the highest yield, followed by sucrose. The highest production efficiency of mannitol might be due to the nitrogen source, which plays an important role. The maximum improvement on the thermal stability of the composites was achieved when mannitol was used in H medium. In addition, the crystallinity was higher in BC formed in H medium compared to other media. FE-SEM micrographs illustrated that the BC pellicles, synthesized in the culture media H and Z, were stable, unlike those in medium Y that were unstable. The micrographs of BC produced in media containing mannitol and sucrose provided evidence of the strong interfacial adhesion between the BC fibers without noticeable aggregates. Copyright © 2014 Elsevier Ltd. All rights reserved.

Synthesis and solubility measurement in supercritical carbon dioxide of two solid derivatives of 2-methylnaphthalene-1,4-dione (menadione): 2-(Benzylamino)-3-methylnaphthalene-1,4-dione and 3-(phenethylamino)-2-methylnaphthalene-1,4-dione

International Nuclear Information System (INIS)

Zacconi, Flavia C.; Nuñez, Olga N.; Cabrera, Adolfo L.; Valenzuela, Loreto M.

2016-01-01

Highlights: • Two menadione derivatives were synthesized, purified and characterized. • Solubility of menadione derivatives in SC-CO 2 was measured at T < 333 K, p < 28 MPa. • Thermodynamic consistency of solubility data measured was evaluated. • Solubility data was correlated in terms of temperature and CO 2 density. - Abstract: Synthesis of two solid derivatives of vitamin K 3 (2-methylnaphthalene-1,4-dione or menadione), 2-(benzylamino)-3-methylnaphthalene-1,4-dione and 3-(phenethylamino)-2-methylnaphthalene-1,4-dione was completed using a 1,4 Michael addition reaction at 323 K in an inert atmosphere, with reaction yields of 62% mol·mol −1 and 71% mol·mol −1 , respectively, and a purity grade of 98% mol·mol −1 for each component. Isothermal solubility (mole fraction) of each solid derivative in supercritical carbon dioxide was performed using an analytic-recirculation methodology, with direct determination of the molar composition of the carbon dioxide-rich phase by using high performance liquid chromatography, at temperatures of (313, 323 and 333) K and pressures from (8–28) MPa. Results indicated that the range of measured solubilities were from (59 × 10 −6 to 368 × 10 −6 ) mol·mol −1 for solid 2-(benzylamino)-3-methylnaphthalene-1,4-dione and from (40 × 10 −6 to 205 × 10 −6 ) mol·mol −1 for solid 3-(phenethylamino)-2-methylnaphthalene-1,4-dione. The experimental solubility was validated using three approaches, estimating the combined expanded uncertainty of measurement for each solubility data point, evaluating the thermodynamic consistency of the data utilizing a test based on the Gibbs–Duhem equation, and verifying the self-consistency by correlating the experimental solubility values with a semi-empirical model as a function of temperature, pressure and pure carbon dioxide density.

The Nordic Seas carbon budget: Sources, sinks, and uncertainties

OpenAIRE

Jeansson, Emil; Olsen, Are; Eldevik, Tor; Skjelvan, Ingunn; Omar, Abdirahman M.; Lauvset, Siv K.; Nilsen, Jan Even Ø.; Bellerby, Richard G. J; Johannessen, Truls; Falck, Eva

2011-01-01

A carbon budget for the Nordic Seas is derived by combining recent inorganic carbon data from the CARINA database with relevant volume transports. Values of organic carbon in the Nordic Seas' water masses, the amount of carbon input from river runoff, and the removal through sediment burial are taken from the literature. The largest source of carbon to the Nordic Seas is the Atlantic Water that enters the area across the Greenland-Scotland Ridge; this is in particular true for the anthropogen...

Burial fluxes and source apportionment of carbon in culture areas of Sanggou Bay over the past 200 years

Institute of Scientific and Technical Information of China (English)

LIU Sai; HUANG Jiansheng; YANG Qian; YANG Shu; YANG Guipeng; SUN Yao

2015-01-01

In this study, we assessed the burial fluxes and source appointment of different forms of carbon in core sediments collected from culture areas in the Sanggou Bay, and preliminarily analyzed the reasons for the greater proportion of inorganic carbon burial fluxes (BFTIC). The average content of total carbon (TC) in the Sanggou Bay was 2.14%. Total organic carbon (TOC) accounted for a small proportion in TC, more than 65% of which derived from terrigenous organic carbon (Ct), and while the proportion of marine-derived organic carbon (Ca) increased significantly since the beginning of large-scale aquaculture. Total inorganic carbon (TIC) accounted for 60%–75%of TC, an average of which was 60%, with a maximum up to 90% during flourishing periods (1880–1948) of small natural shellfish derived from seashells inorganic carbon (Shell-IC). The TC burial fluxes ranged from 31 g/(m2·a) to 895 g/(m2·a) with an average of 227 g/(m2·a), which was dominated by TIC (about 70%). Shell-IC was the main source of TIC and even TC. As the main food of natural shellfish, biogenic silica (BSi) negatively correlated with BFTIC through affecting shellfish breeding. BFTIC of Sta. S1, influenced greatly by the Yellow Sea Coastal Current, had a certain response to Pacific Decadal Oscillation (PDO) in some specific periods.

Investigating the effect of carbon source on rabies virus glycoprotein production in Pichia pastoris by a transcriptomic approach.

Science.gov (United States)

Ben Azoun, Safa; Kallel, Héla

2017-08-01

Several factors affect protein expression in Pichia pastoris, one among them is the carbon source. In this work, we studied the effect of this factor on the expression level of rabies virus glycoprotein (RABV-G) in two recombinant clones harboring seven copies of the gene of interest. The expression was driven either by the constitutive glyceraldehyde-3-phosphate dehydrogenase (GAP) promoter or the inducible alcohol oxidase1 (AOX1) promoter. Clones were compared in terms of cell physiology and carbon source metabolism. The transcription levels of 16 key genes involved in the central metabolic pathway, the methanol catabolism, and the oxidative stress were investigated in both clones. Cell size, as a parameter reflecting cell physiological changes, was also monitored. Our results showed that when glucose was used as the sole carbon source, large cells were obtained. Transcript levels of the genes of the central metabolic pathway were also upregulated, whereas antioxidative gene transcript levels were low. By contrast, the use of methanol as a carbon source generated small cells and a shift in carbon metabolism toward the dissimilatory pathway by the upregulation of formaldehyde dehydrogenase gene and the downregulation of those of the central metabolic. These observations are in favor of the use of glucose to enhance the expression of RABV-G in P. pastoris. © 2017 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

Synthesis of highly aligned carbon nanotubes by one-step liquid-phase process: Effects of carbon sources on morphology of carbon nanotubes

Science.gov (United States)

Yamagiwa, Kiyofumi; Kuwano, Jun

2017-06-01

This paper describes a unique and innovative synthesis technique for carbon nanotubes (CNTs) by a one-step liquid-phase process under ambient pressure. Vertically aligned multi-walled CNT arrays with a maximum height of 100 µm are prepared on stainless steel substrates, which are submerged and electrically heated in straight-chain primary alcohols with n C = 1-4 (n C: number of C atoms in the molecule) containing an appropriate amount of cobalt-based organometallic complex as a catalyst precursor. Structural isomers of butanol were also used for the synthesis to examine the effects of structural factors on the morphology of the deposited products. Notably, 2-methyl-2-propanol, which is a tertiary alcohol, produced only a small amount of low-crystallinity carbonaceous deposits, whereas vertically aligned CNTs were grown from the other isomers of butanol. These results suggest that the presence or absence of β-hydrogen in the molecular structure is a key factor for understanding the dissociation behavior of the carbon source molecules on the catalyst.

Potential for long-term transfer of dissolved organic carbon from riparian zones to streams in boreal catchments.

Science.gov (United States)

Ledesma, José L J; Grabs, Thomas; Bishop, Kevin H; Schiff, Sherry L; Köhler, Stephan J

2015-08-01

Boreal regions store most of the global terrestrial carbon, which can be transferred as dissolved organic carbon (DOC) to inland waters with implications for both aquatic ecology and carbon budgets. Headwater riparian zones (RZ) are important sources of DOC, and often just a narrow 'dominant source layer' (DSL) within the riparian profile is responsible for most of the DOC export. Two important questions arise: how long boreal RZ could sustain lateral DOC fluxes as the sole source of exported carbon and how its hydromorphological variability influences this role. We estimate theoretical turnover times by comparing carbon pools and lateral exports in the DSL of 13 riparian profiles distributed over a 69 km(2) catchment in northern Sweden. The thickness of the DSL was 36 ± 18 (average ± SD) cm. Thus, only about one-third of the 1-m-deep riparian profile contributed 90% of the lateral DOC flux. The 13 RZ exported 8.7 ± 6.5 g C m(-2) year(-1) , covering the whole range of boreal stream DOC exports. The variation could be explained by local hydromorphological characteristics including RZ width (R(2) = 0.90). The estimated theoretical turnover times were hundreds to a few thousands of years, that is there is a potential long-lasting supply of DOC. Estimates of net ecosystem production in the RZ suggest that lateral fluxes, including both organic and inorganic C, could be maintained without drawing down the riparian pools. This was supported by measurements of stream DO(14) C that indicated modern carbon as the predominant fraction exported, including streams disturbed by ditching. The transfer of DOC into boreal inland waters from new and old carbon sources has a major influence on surface water quality and global carbon balances. This study highlights the importance of local variations in RZ hydromorphology and DSL extent for future DOC fluxes under a changing climate. © 2015 The Authors. Global Change Biology Published by John Wiley & Sons Ltd.

Short Term Electric Production Technology Switching Under Carbon Cap and Trade

Directory of Open Access Journals (Sweden)

Donald F. Larson

2012-10-01

Full Text Available This study examines fuel switching in electricity production following the introduction of the European Union’s Emissions Trading System (EU ETS for greenhouse gas emissions. A short-run restricted cost equation is estimated with carbon permits, high-carbon fuels, and low carbon fuels as variable inputs. Shadow values and substitution elasticities for carbon-free energy resources from nuclear, hydroelectric and renewable sources are imputed from the cost equation. The empirical analysis examines 12 European countries using monthly data on fuel use, prices, and electricity generation during the first phase of the European Emissions Trading System. Despite low emission permit prices, this study finds statistically significant substitution between fossil fuels and carbon free sources of energy for electric power production. Significant substitution between fossil fuels and nuclear energy also was found. Still, while 18 of the 20 substitution elasticities are statistically significant, they are all less than unity, consistent with limited substitution. Overall, these results suggest that prices for carbon emission permits relative to prices for carbon and carbon free sources of energy do matter but that electric power producers have limited operational flexibility in the short-run to satisfy greenhouse gas emission limits.

Partitioning of carbon sources among functional pools to investigate short-term priming effects of biochar in soil: A 13C study

International Nuclear Information System (INIS)

Kerré, Bart; Hernandez-Soriano, Maria C.; Smolders, Erik

2016-01-01

Biochar sequesters carbon (C) in soils because of its prolonged residence time, ranging from several years to millennia. In addition, biochar can promote indirect C-sequestration by increasing crop yield while, potentially, reducing C-mineralization. This laboratory study was set up to evaluate effects of biochar on C-mineralization with due attention to source appointment by using 13 C isotope signatures. An arable soil (S) (7.9 g organic C, OC kg −1 ) was amended (single dose of 10 g kg −1 soil) with dried, grinded maize stover (leaves and stalks), either natural (R) or 13 C enriched (R*), and/or biochar (B/B*) prepared from the maize stover residues (450 °C). Accordingly, seven different combinations were set up (S, SR, SB, SR*, SB*, SRB*, SR*B) to trace the source of C in CO 2 (180 days), dissolved organic-C (115 days) and OC in soil aggregate fractions (90 days). The application of biochar to soil reduced the mineralization of native soil organic C but the effect on maize stover-C mineralization was not consistent. Biochar application decreased the mineralization of the non-enriched maize stover after 90 days, this being consistent with a significant reduction of dissolved organic C concentration from 45 to 18 mg L −1 . However, no significant effect was observed for the enriched maize stover, presumably due to differences between the natural and enriched materials. The combined addition of biochar and enriched maize stover significantly increased (twofold) the presence of native soil organic C or maize derived C in the free microaggregate fraction relative to soil added only with stover. Although consistent effects among C sources and biochar materials remains elusive, our outcomes indicate that some biochar products can reduce mineralization and solubilization of other sources of C while promoting their physical protection in soil particles. - Highlights: • Biochar can reduce native soil organic carbon mineralization. • Biochar can promote storage

Study of the biogenesis of flavones and cinnamic acids by using molecules labelled with carbon 14

International Nuclear Information System (INIS)

Chabannes, Bernard

1970-01-01

This research thesis reports the study of flavones, flavonoid compounds and cinnamic acids which are very common as natural pigments in plant species. The author first reports the study of the synthesis of shikimic acid labelled with carbon 14 (biological methods of preparation, synthesis), and then the synthesis of prunin labelled with carbon 14. The next part reports the study of the transformation of prunin labelled with carbon 14 into cosmosiine in flowers with white cosmos. The author finally compares the introduction of cinnamic acid and of shikimic acid (both labelled with carbon 14) into the sinapic acid of red cabbage leaves

Identifying sources of dissolved organic carbon in agriculturally dominated rivers using radiocarbon age dating: Sacramento-San Joaquin River Basin, California

Science.gov (United States)

Sickman, James O.; DiGiorgio, Carol L.; Davisson, M. Lee; Lucero, Delores M.; Bergamaschi, Brian A.

2010-01-01

We used radiocarbon measurements of dissolved organic carbon (DOC) to resolve sources of riverine carbon within agriculturally dominated landscapes in California. During 2003 and 2004, average Δ14C for DOC was −254‰ in agricultural drains in the Sacramento–San Joaquin Delta, −218‰ in the San Joaquin River, −175‰ in the California State Water Project and −152‰ in the Sacramento River. The age of bulk DOC transiting the rivers of California’s Central Valley is the oldest reported for large rivers and suggests wide-spread loss of soil organic matter caused by agriculture and urbanization. Using DAX 8 adsorbent, we isolated and measured 14C concentrations in hydrophobic acid fractions (HPOA); river samples showed evidence of bomb-pulse carbon with average Δ14C of 91 and 76‰ for the San Joaquin and Sacramento Rivers, respectively, with older HPOA, −204‰, observed in agricultural drains. An operationally defined non-HPOA fraction of DOC was observed in the San Joaquin River with seasonally computed Δ14C values of between −275 and −687‰; the source of this aged material was hypothesized to be physically protected organic-matter in high clay-content soils and agrochemicals (i.e., radiocarbon-dead material) applied to farmlands. Mixing models suggest that the Sacramento River contributes about 50% of the DOC load in the California State Water Project, and agricultural drains contribute approximately one-third of the load. In contrast to studies showing stabilization of soil carbon pools within one or two decades following land conversion, sustained loss of soil organic matter, occurring many decades after the initial agricultural-land conversion, was observed in California’s Central Valley.

Utilization of carbon and nitrogen sources by Streptomyces ...

African Journals Online (AJOL)

We tested a number of carbon and nitrogen compounds for their effect on the production of an antibacterial antibiotic by Streptomyces kananmyceticus M27. Dextrose was found to be the most suitable carbon source, though maltose, sucrose, and soluble starch gave moderate yields. (NH4)H2PO4 and yeast extract were ...

The preparation of nucleotides uniformly labelled with carbon-14 by biosinthetic methods. Isolation of adenilic, uridilic, cytidilic and guanlic acids, from the alkaline hydrolisate of escherichia coli RNA

International Nuclear Information System (INIS)

Garcia Pineda, D.; Pacheco Lopez, J.

1978-01-01

A method is described for the preparation and analysis of adenilic, uridilic, cytidylic and guanilic acids, labelled with carbon 14. Escherichia coli cells have been labelled by growing them in media containing glucose-carbon 14 as their only source of carbon. RNA is isolated from the cells, and after hydrolisis of the molecule the resulting nucleotides are separated by gel filtration and exchange chromatography. Chemical and radiochemical purity of the isolated nucleotides is determined and also its specific radioactivity. The distribution of radioactivity incorporated in the cell among different groups of molecular species is analyse. (author)

Mechanistic facility safety and source term analysis

International Nuclear Information System (INIS)

PLYS, M.G.

1999-01-01

A PC-based computer program was created for facility safety and source term analysis at Hanford The program has been successfully applied to mechanistic prediction of source terms from chemical reactions in underground storage tanks, hydrogen combustion in double contained receiver tanks, and proccss evaluation including the potential for runaway reactions in spent nuclear fuel processing. Model features include user-defined facility room, flow path geometry, and heat conductors, user-defined non-ideal vapor and aerosol species, pressure- and density-driven gas flows, aerosol transport and deposition, and structure to accommodate facility-specific source terms. Example applications are presented here

Some practical implications of source term reassessment

International Nuclear Information System (INIS)

1988-03-01

This report provides a brief summary of the current knowledge of severe accident source terms and suggests how this knowledge might be applied to a number of specific aspects of reactor safety. In preparing the report, consideration has been restricted to source term issues relating to light water reactors (LWRs). Consideration has also generally been restricted to the consequences of hypothetical severe accidents rather than their probability of occurrence, although it is recognized that, in the practical application of source term research, it is necessary to take account of probability as well as consequences. The specific areas identified were as follows: Exploration of the new insights that are available into the management of severe accidents; Investigating the impact of source term research on emergency planning and response; Assessing the possibilities which exist in present reactor designs for preventing or mitigating the consequences of severe accidents and how these might be used effectively; Exploring the need for backfitting and assessing the implications of source term research for future designs; and Improving the quantification of the radiological consequences of hypothetical severe accidents for probabilistic safety assessments (PSAs) and informing the public about the realistic risks associated with nuclear power plants. 7 refs

Source apportionment of PM10 mass and particulate carbon in the Kathmandu Valley, Nepal

Science.gov (United States)

Kim, Bong Mann; Park, Jin-Soo; Kim, Sang-Woo; Kim, Hyunjae; Jeon, Haeun; Cho, Chaeyoon; Kim, Ji-Hyoung; Hong, Seungkyu; Rupakheti, Maheswar; Panday, Arnico K.; Park, Rokjin J.; Hong, Jihyung; Yoon, Soon-Chang

2015-12-01

The Kathmandu Valley in Nepal is a bowl-shaped urban basin in the Himalayan foothills with a serious problem of fine particulate air pollution that impacts local health and impairs visibility. Particulate carbon concentrations have reached severe levels that threaten the health of 3.5 million local residents. Moreover, snow and ice on the Himalayan mountains are melting as a result of additional warming due to particulate carbon, especially high black carbon concentrations. To date, the sources of the Valley's particulate carbon and the impacts of different sources on particulate carbon concentrations are not well understood. Thus, before an effective control strategy can be developed, these particulate carbon sources must be identified and quantified. Our study has found that the four primary sources of particulate carbon in the Kathmandu Valley during winter are brick kilns, motor vehicles, fugitive soil dust, and biomass/garbage burning. Their source contributions are quantified using a recently developed new multivariate receptor model SMP. In contrast to other highly polluted areas such as China, secondary contribution is almost negligible in Kathmandu Valley. Brick kilns (40%), motor vehicles (37%) and biomass/garbage burning (22%) have been identified as the major sources of elemental carbon (black carbon) in the Kathmandu Valley during winter, while motor vehicles (47%), biomass/garbage burning (32%), and soil dust (13%) have been identified as the most important sources of organic carbon. Our research indicates that controlling emissions from motor vehicles, brick kilns, biomass/garbage burning, and soil dust is essential for the mitigation of the particulate carbon that threatens public health, impairs visibility, and influences climate warming within and downwind from the Kathmandu Valley. In addition, this paper suggests several useful particulate carbon mitigation methods that can be applied to Kathmandu Valley and other areas in South Asia with

The present status of carbon 14 analysis and projects for beryllium 10 analysis at the Tandetron 1 accelerator, Nagoya University

Energy Technology Data Exchange (ETDEWEB)

Nakamura, Toshio; Oda, Hirotaka; Ikeda, Akiko; Niu, Etsuko [Nagoya Univ. (Japan)

2001-02-01

The operation experience in 1999 of the Tandetron accelerator age estimation system, Nagoya University, is reported, after the overview and the history of the accelerator is briefly described. Total number of carbon 14 environmental samples analyzed was 8567. The project of introducing new HVEE Tandetron for C-14 analysis, and modifying the present GIC Tandetron for Be-10 analysis is presented. Ion source shall be replaced, and the heavy ion detector shall be installed. Projected geological and archaeological studies using Be-10 are enumerated. (A. Yamamoto)

Shunting arc plasma source for pure carbon ion beam

Energy Technology Data Exchange (ETDEWEB)

Koguchi, H.; Sakakita, H.; Kiyama, S.; Shimada, T.; Sato, Y.; Hirano, Y. [Energy Technology Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan)

2012-02-15

A plasma source is developed using a coaxial shunting arc plasma gun to extract a pure carbon ion beam. The pure carbon ion beam is a new type of deposition system for diamond and other carbon materials. Our plasma device generates pure carbon plasma from solid-state carbon material without using a hydrocarbon gas such as methane gas, and the plasma does not contain any hydrogen. The ion saturation current of the discharge measured by a double probe is about 0.2 mA/mm{sup 2} at the peak of the pulse.

Shunting arc plasma source for pure carbon ion beam.

Science.gov (United States)

Koguchi, H; Sakakita, H; Kiyama, S; Shimada, T; Sato, Y; Hirano, Y

2012-02-01

A plasma source is developed using a coaxial shunting arc plasma gun to extract a pure carbon ion beam. The pure carbon ion beam is a new type of deposition system for diamond and other carbon materials. Our plasma device generates pure carbon plasma from solid-state carbon material without using a hydrocarbon gas such as methane gas, and the plasma does not contain any hydrogen. The ion saturation current of the discharge measured by a double probe is about 0.2 mA∕mm(2) at the peak of the pulse.

Synthesis of pyrimidinic nucleotides and nucleosides labelled with carbon 14, through tri-methylsilylated and lithiated derivatives

International Nuclear Information System (INIS)

Godbillon, Jacques

1972-01-01

After a presentation of the trimethysilylation, lithiation, and methylation processes, this research thesis reports the synthesis of methyl carbon 14 - 5 - uridine, of ethyl carbon 14 - 5 - desoxy - 2' - uridine, and of thymidine monophosphate - 5' (methyl carbon 14) by using silylated and lithiated derivatives. The author also reports preliminary studies of biological studies of the trimethylsilyl-5-uridine and of the iodine-6-thymine

Effect of carbon coating on cycle performance of LiFePO4/C composite cathodes using Tween80 as carbon source

International Nuclear Information System (INIS)

Huang, You-Guo; Zheng, Feng-Hua; Zhang, Xiao-Hui; Li, Qing-Yu; Wang, Hong-Qiang

2014-01-01

Highlights: • The Tween80 addition could enhance cycle stability of LiFePO 4 material. • The FTIR spectrum confirms Tween80 surfactant can bond with LiFePO 4 particles. • Some chemical bonds between material and carbon layer still exist after sintering. - Abstract: The influence of carbon coating on the cycle performance of LiFePO 4 /C composite cathodes using polyoxyethylenesorbitan monooleate (Tween80) as carbon source against lithium metal foil anode for Li-ion batteries was investigated in this paper. According to Infrared spectrum analysis (FTIR), the Tween80 surfactant molecules bond to the surface of LiFePO 4 and form an adsorption layer, which contribute to the formation of a homogeneous carbon layer tightly coating on the surface of LiFePO 4 particles in the process of sintering, due to a strong binding force provided by surface chemical bonds. The transmission electron microscopy (TEM) shows that the carbon layer around LiFePO 4 using Tween80 as carbon source still coating on the surface of LiFePO 4 after 200 cycles at 5 C rate while the carbon layer shed from the surface of LiFePO 4 using glucose as carbon source. As a result, the carbon-coated LiFePO 4 using Tween80 as carbon source exhibits much higher capacity retention than the sample using glucose as carbon source. Electrochemical impedance measurement (EIS) reveals that the carbon-coated LiFePO 4 electrode using Tween80 surfactant has a lower charge transfer resistance than the electrode using glucose as carbon source electrode after 100 and 200 cycles at 5 C rate

Dynamics of carbon sources supporting burial in seagrass sediments under increasing anthropogenic pressure

KAUST Repository

Mazarrasa, Inés

2017-03-15

Seagrass meadows are strong coastal carbon sinks of autochthonous and allochthonous carbon. The aim of this study was to assess the effect of coastal anthropogenic pressure on the variability of carbon sources in seagrass carbon sinks during the last 150 yr. We did so by examining the composition of the sediment organic carbon (Corg) stocks by measuring the δ13Corg signature and C : N ratio in 210Pb dated sediments of 11 Posidonia oceanica seagrass meadows around the Balearic Islands (Spain, Western Mediterranean) under different levels of human pressure. On average, the top meter sediment carbon deposits were mainly (59% ± 12%) composed by P. oceanica derived carbon whereas seston contribution was generally lower (41% ± 8%). The contribution of P. oceanica to the total sediment carbon stock was the highest (∼ 80%) in the most pristine sites whereas the sestonic contribution was the highest (∼ 40–80%) in the meadows located in areas under moderate to very high human pressure. Furthermore, an increase in the contribution of sestonic carbon and a decrease in that of seagrass derived carbon toward present was observed in most of the meadows examined, coincident with the onset of the tourism industry development and coastal urbanization in the region. Our results demonstrate a general increase of total carbon accumulation rate in P. oceanica sediments during the last century, mainly driven by the increase in sestonic Corg carbon burial, which may have important implications in the long-term carbon sink capacity of the seagrass meadows in the region examined.

Long-term decline of the Amazon carbon sink.

Science.gov (United States)

Brienen, R J W; Phillips, O L; Feldpausch, T R; Gloor, E; Baker, T R; Lloyd, J; Lopez-Gonzalez, G; Monteagudo-Mendoza, A; Malhi, Y; Lewis, S L; Vásquez Martinez, R; Alexiades, M; Álvarez Dávila, E; Alvarez-Loayza, P; Andrade, A; Aragão, L E O C; Araujo-Murakami, A; Arets, E J M M; Arroyo, L; Aymard C, G A; Bánki, O S; Baraloto, C; Barroso, J; Bonal, D; Boot, R G A; Camargo, J L C; Castilho, C V; Chama, V; Chao, K J; Chave, J; Comiskey, J A; Cornejo Valverde, F; da Costa, L; de Oliveira, E A; Di Fiore, A; Erwin, T L; Fauset, S; Forsthofer, M; Galbraith, D R; Grahame, E S; Groot, N; Hérault, B; Higuchi, N; Honorio Coronado, E N; Keeling, H; Killeen, T J; Laurance, W F; Laurance, S; Licona, J; Magnussen, W E; Marimon, B S; Marimon-Junior, B H; Mendoza, C; Neill, D A; Nogueira, E M; Núñez, P; Pallqui Camacho, N C; Parada, A; Pardo-Molina, G; Peacock, J; Peña-Claros, M; Pickavance, G C; Pitman, N C A; Poorter, L; Prieto, A; Quesada, C A; Ramírez, F; Ramírez-Angulo, H; Restrepo, Z; Roopsind, A; Rudas, A; Salomão, R P; Schwarz, M; Silva, N; Silva-Espejo, J E; Silveira, M; Stropp, J; Talbot, J; ter Steege, H; Teran-Aguilar, J; Terborgh, J; Thomas-Caesar, R; Toledo, M; Torello-Raventos, M; Umetsu, R K; van der Heijden, G M F; van der Hout, P; Guimarães Vieira, I C; Vieira, S A; Vilanova, E; Vos, V A; Zagt, R J

2015-03-19

Atmospheric carbon dioxide records indicate that the land surface has acted as a strong global carbon sink over recent decades, with a substantial fraction of this sink probably located in the tropics, particularly in the Amazon. Nevertheless, it is unclear how the terrestrial carbon sink will evolve as climate and atmospheric composition continue to change. Here we analyse the historical evolution of the biomass dynamics of the Amazon rainforest over three decades using a distributed network of 321 plots. While this analysis confirms that Amazon forests have acted as a long-term net biomass sink, we find a long-term decreasing trend of carbon accumulation. Rates of net increase in above-ground biomass declined by one-third during the past decade compared to the 1990s. This is a consequence of growth rate increases levelling off recently, while biomass mortality persistently increased throughout, leading to a shortening of carbon residence times. Potential drivers for the mortality increase include greater climate variability, and feedbacks of faster growth on mortality, resulting in shortened tree longevity. The observed decline of the Amazon sink diverges markedly from the recent increase in terrestrial carbon uptake at the global scale, and is contrary to expectations based on models.

Revised accident source terms and control room habitability

International Nuclear Information System (INIS)

Lahti, G.P.; Hubner, R.S.; Johnson, W.J.; Schwartz, B.C.

1993-01-01

In April 1992, the NRC staff presented to the Commissioners the draft NUREG open-quotes Revised Accident Source Terms for Light-Water Nuclear Power Plants.close quotes This document is the culmination of more than ten years of NRC-sponsored research and represents the first change in the NRC's position on source terms since TID-14844 was issued in 1962. The purpose of this paper is to investigate the impact of the revised source terms on the current approach to analyzing control room habitability as required by 10 CFR 50. Sample calculations are presented that identify aspects of the model requiring clarification before the implementation of the revised source terms. 6 refs., 4 tabs

From carbon sink to carbon source: extensive peat oxidation in insular Southeast Asia since 1990

Science.gov (United States)

Miettinen, Jukka; Hooijer, Aljosja; Vernimmen, Ronald; Liew, Soo Chin; Page, Susan E.

2017-02-01

Tropical peatlands of the western part of insular Southeast Asia have experienced extensive land cover changes since 1990. Typically involving drainage, these land cover changes have resulted in increased peat oxidation in the upper peat profile. In this paper we provide current (2015) and cumulative carbon emissions estimates since 1990 from peat oxidation in Peninsular Malaysia, Sumatra and Borneo, utilizing newly published peatland land cover information and the recently agreed Intergovernmental Panel on Climate Change (IPCC) peat oxidation emission values for tropical peatland areas. Our results highlight the change of one of the Earth’s most efficient long-term carbon sinks to a short-term emission source, with cumulative carbon emissions since 1990 estimated to have been in the order of 2.5 Gt C. Current (2015) levels of emissions are estimated at around 146 Mt C yr-1, with a range of 132-159 Mt C yr-1 depending on the selection of emissions factors for different land cover types. 44% (or 64 Mt C yr-1) of the emissions come from industrial plantations (mainly oil palm and Acacia pulpwood), followed by 34% (49 Mt C yr-1) of emissions from small-holder areas. Thus, altogether 78% of current peat oxidation emissions come from managed land cover types. Although based on the latest information, these estimates may still include considerable, yet currently unquantifiable, uncertainties (e.g. due to uncertainties in the extent of peatlands and drainage networks) which need to be focused on in future research. In comparison, fire induced carbon dioxide emissions over the past ten years for the entire equatorial Southeast Asia region have been estimated to average 122 Mt C yr-1 (www.globalfiredata.org/_index.html). The results emphasise that whilst reducing emissions from peat fires is important, urgent efforts are also needed to mitigate the constantly high level of emissions arising from peat drainage, regardless of fire occurrence.

14 CFR 137.3 - Definition of terms.

Science.gov (United States)

2010-01-01

... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Definition of terms. 137.3 Section 137.3... General § 137.3 Definition of terms. For the purposes of this part— Agricultural aircraft operation means... man or other animals, which the Secretary of Agriculture shall declare to be a pest, and (2) any...

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

Science.gov (United States)

Hesshaimer, Vago; Heimann, Martin; Levin, Ingeborg

1994-07-01

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

A Precisely Assembled Carbon Source to Synthesize Fluorescent Carbon Quantum Dots for Sensing Probes and Bioimaging Agents.

Science.gov (United States)

Qiao, Yiqiang; Luo, Dan; Yu, Min; Zhang, Ting; Cao, Xuanping; Zhou, Yanheng; Liu, Yan

2018-02-09

A broad range of carbon sources have been used to fabricate varieties of carbon quantum dots (CQDs). However, the majority of these studies concern the influence of primary structures and chemical compositions of precursors on the CQDs; it is still unclear whether or not the superstructures of carbon sources have effects on the physiochemical properties of the synthetic CQDs. In this work, the concept of molecular assembly is first introduced into the design of a new carbon source. Compared with the tropocollagen molecules, the hierarchically assembled collagen scaffolds, as a new carbon source, immobilize functional groups of the precursors through hydrogen bonds, electrostatic attraction, and hydrophobic forces. Moreover, the accumulation of functional groups in collagen self-assembly further promotes the covalent bond formation in the obtained CQDs through a hydrothermal process. Both of these two chemical superiorities give rise to high quality CQDs with enhanced emission. The assembled collagen scaffold-based CQDs with heteroatom doping exhibit superior stability, and could be further applied as effective fluorescent probes for Fe 3+ detection and cellular cytosol imaging. These findings open a wealth of possibilities to explore more nanocarbons from precursors with assembled superstructures. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Some problems in the categorization of source terms

International Nuclear Information System (INIS)

Abbey, F.; Dunbar, I.H.; Hayns, M.R.; Nixon, W.

1985-01-01

In recent years techniques for calculating source terms have been considerably improved. It would be unfortunate if the new information were to be blurred by the use of old schemes for the categorization of source terms. In the past categorization schemes have been devised without the question of the general principles of categorization and the available options being addressed explicitly. In this paper these principles are set out, providing a framework within which categorization schemes used in past probabilistic risk assessments and possible future improvements are discussed. In particular the use of input from scoping consequence calculations in deciding how to group source terms, and the question of how modelling uncertainties may be expressed as uncertainties in a final category source terms are considered

Carbon footprint of urban source separation for nutrient recovery.

Science.gov (United States)

Kjerstadius, H; Bernstad Saraiva, A; Spångberg, J; Davidsson, Å

2017-07-15

Source separation systems for the management of domestic wastewater and food waste has been suggested as more sustainable sanitation systems for urban areas. The present study used an attributional life cycle assessment to investigate the carbon footprint and potential for nutrient recovery of two sanitation systems for a hypothetical urban area in Southern Sweden. The systems represented a typical Swedish conventional system and a possible source separation system with increased nutrient recovery. The assessment included the management chain from household collection, transport, treatment and final return of nutrients to agriculture or disposal of the residuals. The results for carbon footprint and nutrient recovery (phosphorus and nitrogen) concluded that the source separation system could increase nutrient recovery (0.30-0.38 kg P capita -1 year -1 and 3.10-3.28 kg N capita -1 year -1 ), while decreasing the carbon footprint (-24 to -58 kg CO 2 -eq. capita -1 year -1 ), compared to the conventional system. The nutrient recovery was increased by the use of struvite precipitation and ammonium stripping at the wastewater treatment plant. The carbon footprint decreased, mainly due to the increased biogas production, increased replacement of mineral fertilizer in agriculture and less emissions of nitrous oxide from wastewater treatment. In conclusion, the study showed that source separation systems could potentially be used to increase nutrient recovery from urban areas, while decreasing the climate impact. Copyright © 2017 Elsevier Ltd. All rights reserved.

Radiocarbon (14C) Constraints On The Fraction Of Refractory Dissolved Organic Carbon In Primary Marine Aerosol From The Northwest Atlantic

Science.gov (United States)

Beaupre, S. R.; Kieber, D. J.; Keene, W. C.; Long, M. S.; Frossard, A. A.; Kinsey, J. D.; Duplessis, P.; Chang, R.; Maben, J. R.; Lu, X.; Zhu, Y.; Bisgrove, J.

2017-12-01

Nearly all organic carbon in seawater is dissolved (DOC), with more than 95% considered refractory based on modeled average lifetimes ( 16,000 years) and characteristically old bulk radiocarbon (14C) ages (4000 - 6000 years) that exceed the timescales of overturning circulation. Although this refractory dissolved organic carbon (RDOC) is present throughout the oceans as a major reservoir of the global carbon cycle, its sources and sinks are poorly constrained. Recently, RDOC was proposed to be removed from the oceans through adsorption onto the surfaces of rising bubble plumes produced by breaking waves, ejection into the atmosphere via bubble bursting as a component of primary marine aerosol (PMA), and subsequent oxidation in the atmosphere. To test this mechanism, we used natural abundance 14C (5730 ± 40 yr half-life) to trace the fraction of RDOC in PMA produced in a high capacity generator at two biologically-productive and two oligotrophic hydrographic stations in the Northwest Atlantic Ocean during a research cruise aboard the R/V Endeavor (Sep - Oct 2016). The 14C signatures of PMA separately generated day and night from near-surface (5 m) and deep (2500 m) seawater were compared with corresponding 14C signatures in seawater of near-surface dissolved inorganic carbon (DIC, a proxy for recently produced organic matter), bulk deep DOC (a proxy for RDOC), and near-surface bulk DOC. Results constrain the selectivity of PMA formation from RDOC in natural mixtures of recently produced and refractory DOC. The implications of these results for PMA formation and RDOC biogeochemistry will be discussed.

The 14 mu m band of carbon stars

NARCIS (Netherlands)

Yamamura, [No Value; de Jong, T; Waters, LBFM; Cami, J; Justtanont, K; LeBertre, T; Lebre, A; Waelkens, C

1999-01-01

We have studied the absorption bands around 14 mum in the spectra of 11 carbon stars with mass-loss rates ranging from 10(-8) to 10(-4) M-circle dot yr(-1), based on data obtained with the Short Wavelength Spectrometer (SWS) on board the Infrared Space Observatory (ISO). All stars clearly show a

Synthesis of 1-(4-methylsulfone-phenyl)-5-(4-fluoro-phenyl)-5-[14C]-1,2,3- triazole and 1-(4-sulfonamide-phenyl)-5-(4-fluoro-phenyl)-5-[14C]-1,2,3- triazole as novel carbon-14 anticonvulsant

International Nuclear Information System (INIS)

Saemian, N.; Shirvani, G.; Matloubi, H.

2006-01-01

Two 1,2,3-triazole anticonvulsants, 1-(4-methylsulfone-phenyl)-5-(4-fluoro-phenyl)-5-[ 14 C]-1,2,3-triazole and 1-(4-sulfonamide-phenyl)-5-(4- fluoro-phenyl)-5-[ 14 C]-1,2,3-triazole, both labeled with carbon-14 in the 5-position were prepared from para-fluoro-benzonitrile-[cyano- 14 C]. (author)

Application of Alkenone 14C-Based chronostratigraphy in carbonate barren sediments on the Peru Margin.

Science.gov (United States)

Higginson, M. J.; Altabet, M. A.; Herbert, T. D.

2003-04-01

Despite the availability of high-quality sediment cores in key locations, little paleoclimatic information exists for the Peru margin largely because poor carbonate preservation severely restricts the use of traditional carbonate-based proxies for stratigraphy, dating, and paleo-environmental reconstruction. Many sites also include hiatuses produced by the variable influence of undercurrents on sediment accumulation. To overcome these difficulties, we have developed (in collaboration with T. Eglinton, WHOI) a laboratory facility to successfully extract and purify haptophyte-derived alkenones for compound specific 14C AMS dating (modified from OHKOUCHI et al., 2002). This avoids potential problems with dating bulk organic carbon which we assume, even in an upwelling environment as highly productive as the Peru margin, is not a priori solely of marine origin. In a recently collected, mid-Peru Margin core (ODP Leg 201 Site 1228D), comparison of our alkenone 14C dates with bulk sediment organic carbon dates and known stratigraphic markers produces a very well constrained, curvilinear age-depth relationship for at least the last 14 Kyr. A discrete ash layer at Site 1228D with an adjacent alkenone 14C age of 3890 ± 350 yr, is within error identical to the 14C age of a prominent ash layer (3800 ± 50 yr) found west of the large Peruvian El Misti volcano (16^o18'S, 71^o24'W). In summary, these results show that the Peru margin alkenones are autochthonous (i.e. not from an older, distant source) and provide sufficient dating precision to permit, for the first time, high-resolution paleoceanographic studies in this highly important marine province. Based upon this new chronology, synchronous changes in alkenone-derived SST estimates in two of our independently-dated records are the first to record at high-resolution (a) a large LGM-Holocene SST range in the Tropics (up to 7.8 ^oC during brief events in this upwelling location); and (b) sharp coolings (4 ^oC) consistent with

Partitioning of carbon sources among functional pools to investigate short-term priming effects of biochar in soil: A {sup 13}C study

Energy Technology Data Exchange (ETDEWEB)

Kerré, Bart [Department of Earth and Environmental Science, KU Leuven, Kasteelpark Arenberg 20, B-3001 Heverlee (Belgium); Hernandez-Soriano, Maria C., E-mail: m.hernandezsoriano@uq.edu.au [Department of Earth and Environmental Science, KU Leuven, Kasteelpark Arenberg 20, B-3001 Heverlee (Belgium); The University of Queensland, School of Agriculture and Food Sciences, St. Lucia, Queensland 4072 (Australia); Smolders, Erik [Department of Earth and Environmental Science, KU Leuven, Kasteelpark Arenberg 20, B-3001 Heverlee (Belgium)

2016-03-15

Biochar sequesters carbon (C) in soils because of its prolonged residence time, ranging from several years to millennia. In addition, biochar can promote indirect C-sequestration by increasing crop yield while, potentially, reducing C-mineralization. This laboratory study was set up to evaluate effects of biochar on C-mineralization with due attention to source appointment by using {sup 13}C isotope signatures. An arable soil (S) (7.9 g organic C, OC kg{sup −1}) was amended (single dose of 10 g kg{sup −1} soil) with dried, grinded maize stover (leaves and stalks), either natural (R) or {sup 13}C enriched (R*), and/or biochar (B/B*) prepared from the maize stover residues (450 °C). Accordingly, seven different combinations were set up (S, SR, SB, SR*, SB*, SRB*, SR*B) to trace the source of C in CO{sub 2} (180 days), dissolved organic-C (115 days) and OC in soil aggregate fractions (90 days). The application of biochar to soil reduced the mineralization of native soil organic C but the effect on maize stover-C mineralization was not consistent. Biochar application decreased the mineralization of the non-enriched maize stover after 90 days, this being consistent with a significant reduction of dissolved organic C concentration from 45 to 18 mg L{sup −1}. However, no significant effect was observed for the enriched maize stover, presumably due to differences between the natural and enriched materials. The combined addition of biochar and enriched maize stover significantly increased (twofold) the presence of native soil organic C or maize derived C in the free microaggregate fraction relative to soil added only with stover. Although consistent effects among C sources and biochar materials remains elusive, our outcomes indicate that some biochar products can reduce mineralization and solubilization of other sources of C while promoting their physical protection in soil particles. - Highlights: • Biochar can reduce native soil organic carbon mineralization. �

Synthesis of a polycyclic aromatic hydrocarbon marked with carbon-14: (b, d e f) dibenzo-chrysene {sup 14}C-7,14; Synthese d'un hydrocarbure aromatique polycyclique marque au carbone 14: le dibenzo (b, d e f) chrysene {sup 14}C-7,14

Energy Technology Data Exchange (ETDEWEB)

Chatelain, G [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1965-07-01

(b, d e f) dibenzo-chrysene C-7,14 has been synthesized from radioactive carbon dioxide and the organic magnesium compound derived from 1,5 dibromo naphthalene. The product has been purified by a very precise series of fractionated chromatographs on alumina having a chromatographic activity. This has necessitated the development of a special technique. (author) [French] Le dibenzo (b, d e f) chrysene 14C-7,14 a ete synthetise au depart de gaz carbonique radioactif et de bis-organomagnesien derive du dibromo-1,5 naphtalene. Le produit a ete purifie par une serie de chromatographies fractionnees sur alumine d'activite chromatographique tres precise. Ceci a fait l'objet d'une mise au point de technique. (auteur)

A potential explanation for the effect of carbon source on the ...

African Journals Online (AJOL)

This paper proposes a new theory to account for the effect of carbon source on the characteristics of acetate-fed and glucose-fed aerobic granules. It is well known that reactor pH can vary in response to the oxidation of glucose or sodium acetate. As such, the effects associated with the carbon sources may be explained by ...

Quantitative carbon-14 autoradiography at the cellular level: principles and application for cell kinetic studies

International Nuclear Information System (INIS)

Doermer, P.

1981-01-01

Amounts of radio-labelled substances as low as 10 -18 moles incorporated into individual cells can be measured by utilizing techniques of quantitative autoradiography. The principles and application of quantitative carbon-14 autoradiography are reviewed. Silver grain densities can be counted by automated microphotometry allowing on-line data processing by an interfaced computer. Rate measurements of 14 C-thymidine incorporation into individual cells yield values of the DNA synthesis rate and the DNA synthesis time of a cell compartment can be derived. This is an essential time parameter for the evaluation of kinetic events in proliferating cell populations. This method is applicable to human cells without radiation hazard to man and provides an optimal source of detailed information on the kinetics of normal and diseased human haematopoiesis. Examples of application consist of thalassaemia, malaria infection, iron deficiency anaemia and acute myelogenous leukaemia. (author)

Long-term analysis of carbon dioxide and methane column-averaged mole fractions retrieved from SCIAMACHY

Directory of Open Access Journals (Sweden)

O. Schneising

2011-03-01

Full Text Available Carbon dioxide (CO₂ and methane (CH₄ are the two most important anthropogenic greenhouse gases contributing to global climate change. SCIAMACHY onboard ENVISAT (launch 2002 was the first and is now with TANSO onboard GOSAT (launch 2009 one of only two satellite instruments currently in space whose measurements are sensitive to CO₂ and CH₄ concentration changes in the lowest atmospheric layers where the variability due to sources and sinks is largest.

We present long-term SCIAMACHY retrievals (2003–2009 of column-averaged dry air mole fractions of both gases (denoted XCO₂ and XCH₄ derived from absorption bands in the near-infrared/shortwave-infrared (NIR/SWIR spectral region focusing on large-scale features. The results are obtained using an upgraded version (v2 of the retrieval algorithm WFM-DOAS including several improvements, while simultaneously maintaining its high processing speed. The retrieved mole fractions are compared to global model simulations (CarbonTracker XCO₂ and TM5 XCH₄ being optimised by assimilating highly accurate surface measurements from the NOAA/ESRL network and taking the SCIAMACHY averaging kernels into account. The comparisons address seasonal variations and long-term characteristics.

The steady increase of atmospheric carbon dioxide primarily caused by the burning of fossil fuels can be clearly observed with SCIAMACHY globally. The retrieved global annual mean XCO₂ increase agrees with CarbonTracker within the error bars (1.80±0.13 ppm yr⁻¹ compared to 1.81±0.09 ppm yr⁻¹. The amplitude of the XCO₂ seasonal cycle as retrieved by SCIAMACHY, which is 4.3±0.2 ppm for the Northern Hemisphere and 1.4±0.2 ppm for the Southern Hemisphere, is on average about 1 ppm larger than for CarbonTracker.

An investigation of the boreal forest carbon uptake during the

Chernobyl source term estimation

International Nuclear Information System (INIS)

Gudiksen, P.H.; Harvey, T.F.; Lange, R.

1990-09-01

The Chernobyl source term available for long-range transport was estimated by integration of radiological measurements with atmospheric dispersion modeling and by reactor core radionuclide inventory estimation in conjunction with WASH-1400 release fractions associated with specific chemical groups. The model simulations revealed that the radioactive cloud became segmented during the first day, with the lower section heading toward Scandinavia and the upper part heading in a southeasterly direction with subsequent transport across Asia to Japan, the North Pacific, and the west coast of North America. By optimizing the agreement between the observed cloud arrival times and duration of peak concentrations measured over Europe, Japan, Kuwait, and the US with the model predicted concentrations, it was possible to derive source term estimates for those radionuclides measured in airborne radioactivity. This was extended to radionuclides that were largely unmeasured in the environment by performing a reactor core radionuclide inventory analysis to obtain release fractions for the various chemical transport groups. These analyses indicated that essentially all of the noble gases, 60% of the radioiodines, 40% of the radiocesium, 10% of the tellurium and about 1% or less of the more refractory elements were released. These estimates are in excellent agreement with those obtained on the basis of worldwide deposition measurements. The Chernobyl source term was several orders of magnitude greater than those associated with the Windscale and TMI reactor accidents. However, the 137 Cs from the Chernobyl event is about 6% of that released by the US and USSR atmospheric nuclear weapon tests, while the 131 I and 90 Sr released by the Chernobyl accident was only about 0.1% of that released by the weapon tests. 13 refs., 2 figs., 7 tabs

Source term and radiological consequences of the Chernobyl accident

International Nuclear Information System (INIS)

Mourad, R.

1987-09-01

This report presents the results of a study of the source term and radiological consequences of the Chernobyl accident. The results two parts. The first part was performed during the first 2 months following the accident and dealt with the evaluation of the source term and an estimate of individual doses in the European countries outside the Soviet Union. The second part was performed after August 25-29, 1986 when the Soviets presented in a IAEA Conference in Vienna detailed information about the accident, including source term and radiological consequences in the Soviet Union. The second part of the study reconfirms the source term evaluated in the first part and in addition deals with the radiological consequences in the Soviet Union. Source term and individual doses are calculated from measured post-accident data, reported by the Soviet Union and European countries, microcomputer program PEAR (Public Exposure from Accident Releases). 22 refs

Phase 1 immobilized low-activity waste operational source term

International Nuclear Information System (INIS)

Burbank, D.A.

1998-01-01

This report presents an engineering analysis of the Phase 1 privatization feeds to establish an operational source term for storage and disposal of immobilized low-activity waste packages at the Hanford Site. The source term information is needed to establish a preliminary estimate of the numbers of remote-handled and contact-handled waste packages. A discussion of the uncertainties and their impact on the source term and waste package distribution is also presented. It should be noted that this study is concerned with operational impacts only. Source terms used for accident scenarios would differ due to alpha and beta radiation which were not significant in this study

Accelerator mass analyses of meteorites - carbon-14 terrestrial ages

International Nuclear Information System (INIS)

Miura, Y.; Rucklidge, J.; Beukens, R.; Fireman, E.

1988-01-01

Carbon-14 terrestrial ages of ten Antarctic meteorites have been measured by the IsoTrace accelerator mass spectrometry (AMS). The 14 C terrestrial age of 1 gram sample was determined from 14 C concentrations collected at melt and re-melt temperatures, compared with the 14 C concentration of the known Bruderheim chondrite. Yamato-790448 (LL3) chondrite was found to be the oldest terrestrial age of 3x10 4 years in the nine Yamato chondrites, whereas Yamato-791630 (L4) chondrite is considered to be the youngest chondrites less than thousand years. Allan Hills chondrite of ALH-77231 (L6) shows older terrestrial age than the nine Yamato chondrites. New accelerator data of the terrestrial age show higher accuracy with smaller sample than the previous counting method. (author)

Understanding the carbon cycle in a Late Quaternary-age limestone aquifer system using radiocarbon of dissolved inorganic and organic carbon

Science.gov (United States)

Bryan, Eliza; Meredith, Karina T.; Baker, Andy; Andersen, Martin S.; Post, Vincent E. A.

2017-04-01

Estimating groundwater residence time is critical for our understanding of hydrogeological systems, for groundwater resource assessments and for the sustainable management of groundwater resources. Due to its capacity to date groundwater up to 30 thousand years old, as well as the ubiquitous nature of dissolved carbon (as organic and inorganic forms) in groundwater, 14C is the most widely used radiogenic dating technique in regional aquifers. However, the geochemistry of carbon in groundwater systems includes interaction with the atmosphere, biosphere and geosphere, which results in multiple sources and sinks of carbon that vary in time and space. Identifying these sources of carbon and processes relating to its release or removal is important for understanding the evolution of the groundwater and essential for residence time calculations. This study investigates both the inorganic and organic facets of the carbon cycle in groundwaters throughout a freshwater lens and mixing zone of a carbonate island aquifer and identifies the sources of carbon that contribute to the groundwater system. Groundwater samples were collected from shallow (5-20 m) groundwater wells on a small carbonate Island in Western Australia in September 2014 and analysed for major and minor ions, stable water isotopes (SWIs: δ18O, δ2H), 3H, 14C and 13C carbon isotope values of both DIC and DOC, and 3H. The composition of groundwater DOC was investigated by Liquid Chromatography-Organic Carbon Detection (LC-OCD) analysis. The presence of 3H (0.12 to 1.35 TU) in most samples indicates that groundwaters on the Island are modern, however the measured 14CDIC values (8.4 to 97.2 pmc) suggest that most samples are significantly older due to carbonate dissolution and recrystallisation reactions that are identified and quantified in this work. 14CDOC values (46.6 to 105.6 pMC) were higher than 14CDIC values and were well correlated with 3H values, however deeper groundwaters had lower 14CDOC values than

[Kinetic simulation of enhanced biological phosphorus removal with fermentation broth as carbon source].

Science.gov (United States)

Zhang, Chao; Chen, Yin-Guang

2013-07-01

As a high-quality carbon source, fermentation broth could promote the phosphorus removal efficiency in enhanced biological phosphorus removal (EBPR). The transformation of substrates in EBPR fed with fermentation broth was well simulated using the modified activated sludge model No. 2 (ASM2) based on the carbon source metabolism. When fermentation broth was used as the sole carbon source, it was found that heterotrophic bacteria acted as a promoter rather than a competitor to the phosphorus accumulating organisms (PAO). When fermentation broth was used as a supplementary carbon source of real municipal wastewater, the wastewater composition was optimized for PAO growth; and the PAO concentration, which was increased by 3.3 times compared to that in EBPR fed with solely real municipal wastewater, accounting for about 40% of the total biomass in the reactor.

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

Energy Technology Data Exchange (ETDEWEB)

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

Effects of different external carbon sources and electron acceptors on interactions between denitrification and phosphorus removal in biological nutrient removal processes.

Science.gov (United States)

Hu, Xiang; Sobotka, Dominika; Czerwionka, Krzysztof; Zhou, Qi; Xie, Li; Makinia, Jacek

The effects of two different external carbon sources (acetate and ethanol) and electron acceptors (dissolved oxygen, nitrate, and nitrite) were investigated under aerobic and anoxic conditions with non-acclimated process biomass from a full-scale biological nutrient removal-activated sludge system. When acetate was added as an external carbon source, phosphate release was observed even in the presence of electron acceptors. The release rates were 1.7, 7.8, and 3.5 mg P/(g MLVSS·h) (MLVSS: mixed liquor volatile suspended solids), respectively, for dissolved oxygen, nitrate, and nitrite. In the case of ethanol, no phosphate release was observed in the presence of electron acceptors. Results of the experiments with nitrite showed that approximately 25 mg NO 2 -N/L of nitrite inhibited anoxic phosphorus uptake regardless of the concentration of the tested external carbon sources. Furthermore, higher denitrification rates were obtained with acetate (1.4 and 0.8 mg N/(g MLVSS·h)) compared to ethanol (1.1 and 0.7 mg N/ (g MLVSS·h)) for both anoxic electron acceptors (nitrate and nitrite).

Source term analyses under severe accidents for KNGR

Energy Technology Data Exchange (ETDEWEB)

Song, Yong Mann; Park, Soo Yong

2001-03-01

In this study, in-containment source term for LOFW (Loss of Feed Water), which has appeared the most frequent core melt accident, is calculated and compared with NUREG-1465 source term. This study provides not only new source term data using MELCOR1.8.4 and its state-of-the-art models but also evaluating basis of KNGR design and its mitigation capability under severe accidents. As the selected accident is identical with LOFW-S17, which has been analyzed using MAAP by KEPCO with only difference of 2 SITs, mutual comparison of the results is especially expected.

Characterization of Black and Brown Carbon Concentrations and Sources during winter in Beijing

Science.gov (United States)

Yan, Caiqing; Liu, Yue; Hansen, Anthony D. A.; Močnik, Griša; Zheng, Mei

2017-04-01

Carbonaceous aerosols, including black carbon (BC) and organic carbon (OC), play important roles in air quality, human health, and climate change. A better understanding of sources of light-absorbing carbonaceous aerosol (including black carbon and brown carbon) is particular critical for formulating emission-based control strategies and reducing uncertainties in current aerosol radiative forcing estimates. Beijing, the capital of China, has experienced serious air pollution problems and high concentrations of carbonaceous aerosols in recent years, especially during heating seasons. During November and December of 2016, several severe haze episodes occurred in Beijing, with hourly average PM2.5 mass concentration up to 400 μg/m3. In this study, concentration levels and sources of black carbon and brown carbon were investigated based on 7-wavelength Aethalometer (AE-33) with combination of other PM2.5 chemical composition information. Contributions of traffic and non-traffic emissions (e.g., coal combustion, biomass burning) were apportioned, and brown carbon was separated from black carbon. Our preliminary results showed that (1) Concentrations of BC were around 5.3±4.2 μg/m3 during the study period, with distinct diurnal variations during haze and non-haze days. (2) Traffic emissions contributed to about 37±17% of total BC, and exhibited higher contributions during non-haze days compared to haze days. (3) Coal combustion was a major source of black carbon and brown carbon in Beijing, which was more significant compared to biomass burning. Sources and the relative contributions to black carbon and brown carbon during haze and non-haze days will be further discussed.

14C Analysis of protein extracts from Bacillus spores.

Science.gov (United States)

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. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

UTILIZATION OF PINEAPPLE WASTE AS CARBON SOURCE

Directory of Open Access Journals (Sweden)

Abdullah Moch Busairi

2012-02-01

Full Text Available The liquid pineapple waste contains mainly sucrose, glucose, fructose and other nutrients. It therefore can potentially be used as carbon source for organic acid fermentation.  The objective of this work is to evaluate the use of pineapple waste as substrate for lactic acid fermentation under variables of aerobic, anaerobic condition and pH controlling. Initial results showed that the liquid pineapple waste can be used as carbon source for lactic acid fermentation using Lactobacillus delbrueckii. In the anaerobic condition growth of bacteria and lactic acid production better than aerobic condition. In the anaerobic condition and the controlled pH  the production of lactic acid are found to be 54.79 g/l  (78.27% yield at  40oC, pH 6, 50 rpm and 70 g/l sugar concentration.  In contrast, only 13.87g/l lactic acid produced if the fermentation pH was not controlled even though the fermentation parameters were kept at the same conditions

On the identification of carbonaceous aerosols via 14C accelerator mass spectrometry, and laser microprobe mass spectrometry

International Nuclear Information System (INIS)

Currie, L.A.; Fletcher, R.A.; Klouda, G.A.

1987-01-01

Carbon isotopic measurements ( 12 C, 14 C), derived from chemical measurements of total carbon plus AMS measurements of 14 C/ 12 C have become an accepted means for estimating fossil and contemporary carbon source contributions to atmospheric carbon. Because of the limited sensitivity of these techniques, however, such measurements are restricted to 'bulk' samples comprising at least 10-100 μg of carbon. Laser microprobe mass spectrometry (LMMS) offers an important complementary opportunity to investigate the chemical nature of individual particles as small as 0.1 μm in diameter. Although there is little hope to measure 14 C/ 12 C in such small samples, the compositional and structural information available with the laser microprobe is of interest for possible source discrimination. Also, the analysis of individual particles, which may reflect individual sources, yields significant potential increases in spatial, temporal and source resolution, in comparison to bulk sample analysis. Results of our exploratory investigation of known sources of carbonaceous particles, using LMMS, are presented. By applying multivariate techniques to laser mass spectra of soot from the combustion of heptane and wood, we found striking differences in the alkali metals (notably potassium) in the positive ion mass spectra. For ambient particles, 14 C has proved to be a crucial adjunct for the development and validation of the LMMS approach to single particle source assignment via carbon cluster pattern recognition. The combined techniques offer great promise for objective modeling (number and types of carbon sources) and for extension of the dichotomous carbon apportionment (fossil, contemporary) to subclasses such as soot from wood and agricultural burning, and that from coal and petroleum combustion. (orig.)

Metabolism and risks from tritium and carbon-14 in the developing organism

International Nuclear Information System (INIS)

Gerber, G.B.; Kirchmann, R.; Hoek, J. van den

1987-01-01

In this review the risks are considered from tritium and carbon-14 to the developing organs of mammals. It mainly deals with H-3 but the conclusions are largely valid also for C-14. The metabolism and average tissue of THO as well as of organically bound tritium are discussed. Dosimetry of radiosensitive structures is also considered. 14 refs.; 2 figs.; 1 table

Rhodococcus erythropolis DCL14 Contains a Novel Degradation Pathway for Limonene

OpenAIRE

van der Werf, Mariët J.; Swarts, Henk J.; de Bont, Jan A. M.

1999-01-01

Strain DCL14, which is able to grow on limonene as a sole source of carbon and energy, was isolated from a freshwater sediment sample. This organism was identified as a strain of Rhodococcus erythropolis by chemotaxonomic and genetic studies. R. erythropolis DCL14 also assimilated the terpenes limonene-1,2-epoxide, limonene-1,2-diol, carveol, carvone, and (−)-menthol, while perillyl alcohol was not utilized as a carbon and energy source. Induction tests with cells grown on limonene revealed t...

Development of dose calculation program (DBADOSE) incorporating alternative source term due to design basis accident

International Nuclear Information System (INIS)

Bae, Young Jig; Nam, Ki Mun; Lee, Yu Jong; Chung, Chan Young

2003-01-01

Source terms presented in TID-14844 and Regulatory Guide 1.4 have been used for radiological analysis of design basis accidents for licensing existing pressurized water reactor (PWR). However, more realistic and physically-based source term based on results of study and experiments for about 30 years after the publication of TID-14844 was developed and presented in NUREG-1465 published by U.S NRC in 1995. In addition, ICRP has revised dose concepts and criteria through the publication of ICRP-9, 26, 60 and recommended effective dose concepts rather than critical organ concept since the publication of ICRP-26. Accordingly, multipurpose computer program called DBADOSE incorporating alternative source terms in NUREG-1465 and effective dose concepts in ICRP-60 was developed. Comparison of results of DBADOSE with those of POSTDBA and STARDOSE was performed and verified and no significant difference and inaccuracy were found. DBADOSE will be used to evaluate accidental doses for licensing application according to the domestic laws that are expected to be revised in the near future

Evaluation of applicability of alternative source terms to operating nuclear power plants in Korea

International Nuclear Information System (INIS)

Lim, S. N.; Park, Y. S.; Nam, K. M.; Song, D. B.; Bae, Y. J.; Lee, Y. J.; Jung, C. Y.

2002-01-01

In 1995 and 2000, NRC issued NUREG-1465 and Regulatory Guide 1.183 with respect to Alternative Source Terms(AST) replacing the existing source terms of TID-14844 and Regulatory Guide 1.4, 1.25, and 1.77 for radiological Design Basis Accidents(DBA) analysis. In 1990, ICRP published ICRP Pub. 60 which represents new recommendations on dose criteria and concepts. In Korea, alternative source terms were used for evaluation of effective doses for design basis accidents of Advanced Power Reactor(APR1400) using the computer program developed by an overseas company. Recently, DBADOSE, new computer program for DBA analysis incorporating AST and effective dose concept was developed by KHNP and KOPEC, and reanalysis applying AST to operating nuclear power plants, Kori units 3 and 4 in Korea using DBADOSE has been performed. As the results of this analysis, it was concluded that some conservative variables or operation procedures of operating plants could be mitigated or simplified by virtue of increased safety margin and consequently, economical and operational benefits ensue. In this paper, methodologies and results of Kori 3 and 4 DBA reanalysis and sensitivity analysis for mitigation of main design variables are introduced

A simplified approach to evaluating severe accident source term for PWR

International Nuclear Information System (INIS)

Huang, Gaofeng; Tong, Lili; Cao, Xuewu

2014-01-01

Highlights: • Traditional source term evaluation approaches have been studied. • A simplified approach of source term evaluation for 600 MW PWR is studied. • Five release categories are established. - Abstract: For early design of NPPs, no specific severe accident source term evaluation was considered. Some general source terms have been used for some NPPs. In order to implement a best estimate, a special source term evaluation should be implemented for an NPP. Traditional source term evaluation approaches (mechanism approach and parametric approach) have some difficulties associated with their implementation. The traditional approaches are not consistent with cost-benefit assessment. A simplified approach for evaluating severe accident source term for PWR is studied. For the simplified approach, a simplified containment event tree is established. According to representative cases selection, weighted coefficient evaluation, computation of representative source term cases and weighted computation, five containment release categories are established, including containment bypass, containment isolation failure, containment early failure, containment late failure and intact containment

Radiological and chemical source terms for Solid Waste Operations Complex

International Nuclear Information System (INIS)

Boothe, G.F.

1994-01-01

The purpose of this document is to describe the radiological and chemical source terms for the major projects of the Solid Waste Operations Complex (SWOC), including Project W-112, Project W-133 and Project W-100 (WRAP 2A). For purposes of this document, the term ''source term'' means the design basis inventory. All of the SWOC source terms involve the estimation of the radiological and chemical contents of various waste packages from different waste streams, and the inventories of these packages within facilities or within a scope of operations. The composition of some of the waste is not known precisely; consequently, conservative assumptions were made to ensure that the source term represents a bounding case (i.e., it is expected that the source term would not be exceeded). As better information is obtained on the radiological and chemical contents of waste packages and more accurate facility specific models are developed, this document should be revised as appropriate. Radiological source terms are needed to perform shielding and external dose calculations, to estimate routine airborne releases, to perform release calculations and dose estimates for safety documentation, to calculate the maximum possible fire loss and specific source terms for individual fire areas, etc. Chemical source terms (i.e., inventories of combustible, flammable, explosive or hazardous chemicals) are used to determine combustible loading, fire protection requirements, personnel exposures to hazardous chemicals from routine and accident conditions, and a wide variety of other safety and environmental requirements

Radiocarbon and stable carbon isotope compositions of chemically fractionated soil organic matter in a temperate-zone forest

International Nuclear Information System (INIS)

Koarashi, Jun; Iida, Takao; Asano, Tomohiro

2005-01-01

To better understand the role of soil organic matter in terrestrial carbon cycle, carbon isotope compositions in soil samples from a temperate-zone forest were measured for bulk, acid-insoluble and base-insoluble organic matter fractions separated by a chemical fractionation method. The measurements also made it possible to estimate indirectly radiocarbon ( 14 C) abundances of acid- and base-soluble organic matter fractions, through a mass balance of carbon among the fractions. The depth profiles of 14 C abundances showed that (1) bomb-derived 14 C has penetrated the first 16 cm mineral soil at least; (2) Δ 14 C values of acid-soluble organic matter fraction are considerably higher than those of other fractions; and (3) a significant amount of the bomb-derived 14 C has been preserved as the base-soluble organic matter around litter-mineral soil boundary. In contrast, no or little bomb-derived 14 C was observed for the base-insoluble fraction in all sampling depths, indicating that this recalcitrant fraction, accounting for approximately 15% of total carbon in this temperate-zone forest soil, plays a role as a long-term sink in the carbon cycle. These results suggest that bulk soil organic matter cannot provide a representative indicator as a source or a sink of carbon in soil, particularly on annual to decadal timescales

Mineral Carbonation Potential of CO2 from Natural and Industrial-based Alkalinity Sources

Science.gov (United States)

Wilcox, J.; Kirchofer, A.

2014-12-01

Mineral carbonation is a Carbon Capture and Storage (CSS) technology where gaseous CO2 is reacted with alkaline materials (such as silicate minerals and alkaline industrial wastes) and converted into stable and environmentally benign carbonate minerals (Metz et al., 2005). Here, we present a holistic, transparent life cycle assessment model of aqueous mineral carbonation built using a hybrid process model and economic input-output life cycle assessment approach. We compared the energy efficiency and the net CO2 storage potential of various mineral carbonation processes based on different feedstock material and process schemes on a consistent basis by determining the energy and material balance of each implementation (Kirchofer et al., 2011). In particular, we evaluated the net CO2 storage potential of aqueous mineral carbonation for serpentine, olivine, cement kiln dust, fly ash, and steel slag across a range of reaction conditions and process parameters. A preliminary systematic investigation of the tradeoffs inherent in mineral carbonation processes was conducted and guidelines for the optimization of the life-cycle energy efficiency are provided. The life-cycle assessment of aqueous mineral carbonation suggests that a variety of alkalinity sources and process configurations are capable of net CO2 reductions. The maximum carbonation efficiency, defined as mass percent of CO2 mitigated per CO2 input, was 83% for CKD at ambient temperature and pressure conditions. In order of decreasing efficiency, the maximum carbonation efficiencies for the other alkalinity sources investigated were: olivine, 66%; SS, 64%; FA, 36%; and serpentine, 13%. For natural alkalinity sources, availability is estimated based on U.S. production rates of a) lime (18 Mt/yr) or b) sand and gravel (760 Mt/yr) (USGS, 2011). The low estimate assumes the maximum sequestration efficiency of the alkalinity source obtained in the current work and the high estimate assumes a sequestration efficiency

Effect of source term composition on offsite doses

International Nuclear Information System (INIS)

Karahalios, P.; Gardner, R.

1985-01-01

The development of new realistic accident source terms has identified the need to establish a basis for comparing the impact of such source terms. This paper attempts to develop a generalized basis of comparison by investigating contributions to offsite acute whole body doses from each group of radionuclides being released to the atmosphere, using CRAC2. The paper also investigates the effect of important parameters such as regional meteorology, sheltering, and duration of release. Finally, the paper focuses on significant changes in the relative importance of individual radionuclide groups in PWR2, SST1, and a revision of the Stone and Webster proposed interim source term

Physiological conditions and uptake of inorganic carbon-14 by plant roots

International Nuclear Information System (INIS)

Amiro, B.D.; Ewing, L.L.

1992-01-01

The uptake of inorganic 14 C by bean plant roots was measured. The plants were grown in a nutrient solution culture at pH 6 and a NaH 14 CO 3 tracer was added to the growth medium. Photosynthesis and transpiration were varied by exposing the aerial portions of the plants to different atmospheric CO 2 concentrations, humidities and light levels in a cuvette system. Leaf concentrations of 14 C were measured at the end of the experiments using liquid scintillation counting. Plant uptake of 14 C via the roots was independent of the photosynthetic rate and, in most cases, could be predicted by knowing the transpiration rate and the nutrient solution concentration. However, when a less efficient root-medium aeration system was used, 14 C uptake was greater than that predicted using transpiration, a phenomenon observed by other researchers. This contrasted to results of another experiment where the measured uptake of iodine was much slower than that predicted using transpiration. Knowledge of transpiration rates is useful in predicting inorganic carbon uptake via the roots and in estimating 14 C transport from contaminated soils to biota. Also, the independence of the uptake from photosynthesis and ambient CO 2 concentrations suggests that future increases in atmospheric CO 2 concentrations may not have a direct effect on root uptake of soil carbon. (author)

Design parameters and source terms: Volume 3, Source terms: Revision 0

International Nuclear Information System (INIS)

1987-09-01

The Design Parameters and Source Terms Document was prepared in accordance with DOE request and to provide data for the environmental impact study to be performed in the future for the Deaf Smith County, Texas site for a nuclear waste repository in salt. This document updates a previous unpublished report to the level of the Site Characterization Plan /endash/ Conceptual Design Report, SCP-CDR. The previous unpublished SCC Study identifies the data needs for the Environmental Assessment effort for seven possible salt repository sites

Coprecipitation of {sup 14}C and Sr with carbonate precipitates: The importance of reaction kinetics and recrystallization pathways

Energy Technology Data Exchange (ETDEWEB)

Hodkin, David J. [School of Earth and Environment, University of Leeds, Leeds LS2 9JT (United Kingdom); Stewart, Douglas I. [School of Civil Engineering, University of Leeds (United Kingdom); Graham, James T. [National Nuclear Laboratory, Sellafield, Cumbria (United Kingdom); Burke, Ian T., E-mail: I.T.Burke@leeds.ac.uk [School of Earth and Environment, University of Leeds, Leeds LS2 9JT (United Kingdom)

2016-08-15

This study investigated the simultaneous removal of Sr{sup 2+} and {sup 14}CO{sub 3}{sup 2−} from pH > 12 Ca(OH){sub 2} solution by the precipitation of calcium carbonate. Initial Ca{sup 2+}:CO{sub 3}{sup 2−} ratios ranged from 10:1 to 10:100 (mM:mM). Maximum removal of {sup 14}C and Sr{sup 2+} both occurred in the system containing 10 mM Ca{sup 2+} and 1 mM CO{sub 3}{sup 2−} (99.7% and 98.6% removal respectively). A kinetic model is provided that describes {sup 14}C and Sr removal in terms of mineral dissolution and precipitation reactions. The removal of {sup 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 {sup 14}C back to solution. Sr{sup 2+} removal occurred as Ca{sup 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 {sup 90}Sr and {sup 14}C in radioactively contaminated waters (<$0.25 reagent cost per m{sup 3} treated). - Highlights: • 99.7% of {sup 14}C and 98.6% of Sr removed from aqueous solution by CaCO{sub 3} precipitation. • Remobilization of {sup 14}C observed during calcium carbonate recrystallization. • Sr displayed variable distribution coefficient (possibly affected by Ca:Sr ratio). • Reagent cost of $0.22/m{sup 3} of treated groundwater.

Orbital forcing of climate 1.4 billion years ago

DEFF Research Database (Denmark)

Zhang, Shuichang; Wang, Xiaomei; Hammarlund, Emma U

2015-01-01

Fluctuating climate is a hallmark of Earth. As one transcends deep into Earth time, however, both the evidence for and the causes of climate change become difficult to establish. We report geochemical and sedimentological evidence for repeated, short-term climate fluctuations from the exceptionally...... well-preserved ∼1.4-billion-year-old Xiamaling Formation of the North China Craton. We observe two patterns of climate fluctuations: On long time scales, over what amounts to tens of millions of years, sediments of the Xiamaling Formation record changes in geochemistry consistent with long-term changes...... reflect what appear to be orbitally forced changes in wind patterns and ocean circulation as they influenced rates of organic carbon flux, trace metal accumulation, and the source of detrital particles to the sediment....

Determination of Carbon-14 in environmental samples by mixing 14CO{sub 2} with a liquid scintillator; Determinacion de carbono-14 en muestras ambientales por incorporacion de 14CO{sub 2} a un centelleador liquido

Energy Technology Data Exchange (ETDEWEB)

Garcia, M. R.; Gomez, V.; Heras, M. C.; Beltran, M. A.

1990-07-01

A method for the determination of Carbon-14 (14CO2) in environmental samples has been developed. The method use the direct absorption of the carbon dioxide into Carbosorb, followed with incorporation of the mixture (Carbosorb-CO2) to the liquid scintillator. The results obtained to apply this method and the benzene synthesis, usual in our laboratory, are discussed and compared. The method of collection of atmospheric samples is also described. (Author) 10 refs.

Bayesian source term determination with unknown covariance of measurements

Science.gov (United States)

Belal, Alkomiet; Tichý, Ondřej; Šmídl, Václav

2017-04-01

Determination of a source term of release of a hazardous material into the atmosphere is a very important task for emergency response. We are concerned with the problem of estimation of the source term in the conventional linear inverse problem, y = Mx, where the relationship between the vector of observations y is described using the source-receptor-sensitivity (SRS) matrix M and the unknown source term x. Since the system is typically ill-conditioned, the problem is recast as an optimization problem minR,B(y - Mx)TR-1(y - Mx) + xTB-1x. The first term minimizes the error of the measurements with covariance matrix R, and the second term is a regularization of the source term. There are different types of regularization arising for different choices of matrices R and B, for example, Tikhonov regularization assumes covariance matrix B as the identity matrix multiplied by scalar parameter. In this contribution, we adopt a Bayesian approach to make inference on the unknown source term x as well as unknown R and B. We assume prior on x to be a Gaussian with zero mean and unknown diagonal covariance matrix B. The covariance matrix of the likelihood R is also unknown. We consider two potential choices of the structure of the matrix R. First is the diagonal matrix and the second is a locally correlated structure using information on topology of the measuring network. Since the inference of the model is intractable, iterative variational Bayes algorithm is used for simultaneous estimation of all model parameters. The practical usefulness of our contribution is demonstrated on an application of the resulting algorithm to real data from the European Tracer Experiment (ETEX). This research is supported by EEA/Norwegian Financial Mechanism under project MSMT-28477/2014 Source-Term Determination of Radionuclide Releases by Inverse Atmospheric Dispersion Modelling (STRADI).

A comparison of world-wide uses of severe reactor accident source terms

International Nuclear Information System (INIS)

Ang, M.L.; Frid, W.; Kersting, E.J.; Friederichs, H.G.; Lee, R.Y.; Meyer-Heine, A.; Powers, D.A.; Soda, K.; Sweet, D.

1994-09-01

The definitions of source terms to reactor containments and source terms to the environment are discussed. A comparison is made between the TID-14844 example source term and the alternative source term described in NUREG-1465. Comparisons of these source terms to the containments and those used in France, Germany, Japan, Sweden, and the United Kingdom are made. Source terms to the environment calculated in NUREG-1500 and WASH-1400 are discussed. Again, these source terms are compared to those now being used in France, Germany, Japan, Sweden, and the United Kingdom. It is concluded that source terms to the containment suggested in NUREG-1465 are not greatly more conservative than those used in other countries. Technical bases for the source terms are similar. The regulatory use of the current understanding of radionuclide behavior varies among countries

Nuclear graphite waste's behaviour under disposal conditions: Study of the release and repartition of organic and inorganic forms of carbon 14 and tritium in alkaline media

International Nuclear Information System (INIS)

Vende, L.

2012-01-01

23000 tons of graphite wastes will be generated during dismantling of the first generation of French reactors (9 gas cooled reactors). These wastes are classified as Long Lived Low Level wastes (LLW-LL). As requested by the law, the French National Radioactive Waste Management Agency (Andra) is studying concepts of low-depth disposals.In this work we focus on carbon 14, the main long-lived radionuclide in graphite waste (5730 y), but also on tritium, which is the main contributor to the radioactivity in the short term. Carbon 14 and tritium may be released from graphite waste in many forms in gaseous phase ( 14 CO 2 , HT...) or in solution ( 14 CO 3 2- , HTO...). Their speciation will strongly affect their migration from the disposal site to the environment. Leaching experiments, in alkaline solution (0.1 M NaOH simulating repository conditions) have been performed on irradiated graphite, from Saint-Laurent A2 and G2 reactors, in order to quantify their release and characterize their speciation. The studies show that carbon 14 exists in both gaseous and aqueous phases. In the gaseous phase, release is weak (≤0.1%) and corresponds to oxidizable species. Carbon 14 is mainly released into liquid phase, as both inorganic and organic species. 65% of released fraction is inorganic and 35% organic carbon. Two tritiated species have been identified in gaseous phase: HTO and HT/Organically Bond Tritium. More than 90% of tritium in that phase corresponds to HT/OBT. But release is weak (≤0.1%). HTO is mainly in the liquid phase. (author)

Sources and Reactivity of Terrestrial Organic Carbon to the Colville River Delta, Beaufort Sea, Alaska

Science.gov (United States)

Schreiner, K. M.; Bianchi, T. S.; Rosenheim, B. E.

2014-12-01

Terrestrial particulate organic carbon (tPOC) delivery to nearshore deltaic regions is an important mechanism of OC storage and burial, and continental margins worldwide account for approximately 90% of the carbon burial in the ocean. Increasing warming in the Arctic is leading to an acceleration of the hydrologic cycle, warming of permafrost, and broad shifts in vegetation. All of these changes are likely to affect the delivery, reactivity, and burial of tPOC in nearshore Arctic regions, making the Arctic an ideal place to study the effects of climate change on tPOC delivery. However, to date, most studies of tPOC delivery from North America to the Arctic Ocean have focused on large Arctic rivers like the Mackenzie and Yukon, and a significant portion of those watersheds lie in sub-Arctic latitudes, meaning that their tPOC delivery is likely not uniquely representative of the high Arctic tundra. Here, we focus on tPOC delivery by the Colville River, the largest North American river with a watershed that does not include sub-Arctic latitudes. Sediment samples from the river delta and nearby Simpson's Lagoon were taken in August of 2010 and subsequently fractionated by density, in order to study the delivery of both discrete and sediment-sorbed tPOC. Samples were analyzed for stable carbon isotopes, bulk radiocarbon, terrestrial biomarkers (including lignin-phenols, and other CuO reaction products), and aquatic biomarkers (algal pigments), and additionally a subset of the samples were analyzed by ramped pyrolysis-14C. Results show that tPOC delivery near the river mouth is sourced from coastal plain tundra, with additional delivery of tPOC from peat released into the lagoon from the seaward limit of the tundra by coastal erosion. Ramped pyrolysis-14C analysis also shows a clear differentiation between tPOC delivered by the river and tPOC delivered by coastal retreat in the lagoon. Additionally, a significant portion of the OC released by the Colville River is

Rapid localization of carbon 14-labeled molecules in biological samples by ion mass microscopy

International Nuclear Information System (INIS)

Hindie, E.; Escaig, F.; Coulomb, B.; Lebreton, C.; Galle, P.

1989-01-01

We report here on the ability of secondary ion mass spectrometry (SIMS) to provide rapid imaging of the intracellular distribution of 14 C-labeled molecules. The validity of this method, using mass discrimination of carbon 14 atoms, was assessed by imaging the distribution of two molecules of well-known metabolism, [ 14 C]-thymidine and [ 14 C]-uridine, incorporated by human fibroblasts in culture. As expected, 14 C ion images showed the presence of [ 14 C]-thymidine in the nucleus of dividing cells, whereas [ 14 C]-uridine was present in the cytoplasm as well as the nucleus of all cells, with a large concentration in the nucleoli. The time required to obtain the distribution images with the SMI 300 microscope was less than 6 min, whereas microautoradiography, the classical method for mapping the tissue distribution of 14 C-labeled molecules, usually requires exposure times of several months. Secondary ion mass spectrometry using in situ mass discrimination is proposed here as a very sensitive method which permits rapid imaging of the subcellular distribution of molecules labeled with carbon 14

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

Science.gov (United States)

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.

Quantification of severe accident source terms of a Westinghouse 3-loop plant

International Nuclear Information System (INIS)

Lee Min; Ko, Y.-C.

2008-01-01

Integrated severe accident analysis codes are used to quantify the source terms of the representative sequences identified in PSA study. The characteristics of these source terms depend on the detail design of the plant and the accident scenario. A historical perspective of radioactive source term is provided. The grouping of radionuclides in different source terms or source term quantification tools based on TID-14844, NUREG-1465, and WASH-1400 is compared. The radionuclides release phenomena and models adopted in the integrated severe accident analysis codes of STCP and MAAP4 are described. In the present study, the severe accident source terms for risk quantification of Maanshan Nuclear Power Plant of Taiwan Power Company are quantified using MAAP 4.0.4 code. A methodology is developed to quantify the source terms of each source term category (STC) identified in the Level II PSA analysis of the plant. The characteristics of source terms obtained are compared with other source terms. The plant analyzed employs a Westinghouse designed 3-loop pressurized water reactor (PWR) with large dry containment

Experiments on a 14.5 GHz ECR source

International Nuclear Information System (INIS)

Hill, C.E.; Langbein, K.

1996-01-01

The 14.5 GHz ECR4 source supplied to CERN in the framework of the Heavy Ion Facility collaboration provided Pb 27+ operational beams to a new custom built linac in 1994. This source, which operates in the pulsed 'afterglow' mode, quickly met its design specification of 80 eμA and now provides currents >100 eμA regularly. Early source tests showed the existence of extremely stable modes of operation. In the search for higher intensities a number of experiments have been performed on plasma gas composition, RF power matching, extraction, beam pulse compression and a biased dynode. The results of these tests will be presented along with further ideas to improve source performance. (author)

Characterizing and sourcing ambient PM2.5 over key emission regions in China III: Carbon isotope based source apportionment of black carbon

Science.gov (United States)

Yu, Kuangyou; Xing, Zhenyu; Huang, Xiaofeng; Deng, Junjun; Andersson, August; Fang, Wenzheng; Gustafsson, Örjan; Zhou, Jiabin; Du, Ke

2018-03-01

Regional haze over China has severe implications for air quality and regional climate. To effectively combat these effects the high uncertainties regarding the emissions from different sources needs to be reduced. In this paper, which is the third in a series on the sources of PM2.5 in pollution hotspot regions of China, we focus on the sources of black carbon aerosols (BC), using carbon isotope signatures. Four-season samples were collected at two key locations: Beijing-Tianjin-Hebei (BTH, part of Northern China plain), and the Pearl River Delta (PRD). We find that that fossil fuel combustion was the predominant source of BC in both BTH and PRD regions, accounting for 75 ± 5%. However, the contributions of what fossil fuel components were dominating differed significantly between BTH and PRD, and varied dramatically with seasons. Coal combustion is overall the all-important BC source in BTH, accounting for 46 ± 12% of the BC in BTH, with the maximum value (62%) found in winter. In contrast for the PRD region, liquid fossil fuel combustion (e.g., oil, diesel, and gasoline) is the dominant source of BC, with an annual mean value of 41 ± 15% and the maximum value of 55% found in winter. Region- and season-specific source apportionments are recommended to both accurately assess the climate impact of carbonaceous aerosol emissions and to effectively mitigate deteriorating air quality caused by carbonaceous aerosols.

Lipids Reprogram Metabolism to Become a Major Carbon Source for Histone Acetylation

DEFF Research Database (Denmark)

McDonnell, Eoin; Crown, Scott B; Fox, Douglas B

2016-01-01

Cells integrate nutrient sensing and metabolism to coordinate proper cellular responses to a particular nutrient source. For example, glucose drives a gene expression program characterized by activating genes involved in its metabolism, in part by increasing glucose-derived histone acetylation....... Here, we find that lipid-derived acetyl-CoA is a major source of carbon for histone acetylation. Using (13)C-carbon tracing combined with acetyl-proteomics, we show that up to 90% of acetylation on certain histone lysines can be derived from fatty acid carbon, even in the presence of excess glucose...

Carbon source-sink relationship in Arabidopsis thaliana: the role of sucrose transporters.

Science.gov (United States)

Durand, Mickaël; Mainson, Dany; Porcheron, Benoît; Maurousset, Laurence; Lemoine, Rémi; Pourtau, Nathalie

2018-03-01

The regulation of source-to-sink sucrose transport is associated with AtSUC and AtSWEET sucrose transporters' gene expression changes in plants grown hydroponically under different physiological conditions. Source-to-sink transport of sucrose is one of the major determinants of plant growth. Whole-plant carbohydrates' partitioning requires the specific activity of membrane sugar transporters. In Arabidopsis thaliana plants, two families of transporters are involved in sucrose transport: AtSUCs and AtSWEETs. This study is focused on the comparison of sucrose transporter gene expression, soluble sugar and starch levels and long distance sucrose transport, in leaves and sink organs (mainly roots) in different physiological conditions (along the plant life cycle, during a diel cycle, and during an osmotic stress) in plants grown hydroponically. In leaves, the AtSUC2, AtSWEET11, and 12 genes known to be involved in phloem loading were highly expressed when sucrose export was high and reduced during osmotic stress. In roots, AtSUC1 was highly expressed and its expression profile in the different conditions tested suggests that it may play a role in sucrose unloading in roots and in root growth. The SWEET transporter genes AtSWEET12, 13, and 15 were found expressed in all organs at all stages studied, while differential expression was noticed for AtSWEET14 in roots, stems, and siliques and AtSWEET9, 10 expressions were only detected in stems and siliques. A role for these transporters in carbohydrate partitioning in different source-sink status is proposed, with a specific attention on carbon demand in roots. During development, despite trophic competition with others sinks, roots remained a significant sink, but during osmotic stress, the amount of translocated [U- 14 C]-sucrose decreased for rosettes and roots. Altogether, these results suggest that source-sink relationship may be linked with the regulation of sucrose transporter gene expression.

Seasonal dynamics of permafrost carbon emissions: A passive, quasi-continuous 14CO2 sampler

Science.gov (United States)

Pedron, S.; Xu, X.; Walker, J. C.; Welker, J. M.; Klein, E. S.; Euskirchen, E. S.; Czimczik, C. I.

2017-12-01

Millennia of carbon (C) fixation by tundra vegetation, coupled with low rates of C mineralization by soil microorganisms and preservation in permafrost, have allowed Arctic soils to accumulate vast quantities of organic C (1672 Pg C total). Today, the Arctic is rapidly warming (0.48oC decade-1) and widespread degradation of permafrost may subject permafrost C to microbial mineralization and fluxes to the atmosphere, accelerating climate change. Loss of permafrost C can be quantified in situ by measuring the radiocarbon (14C) content of soil and ecosystem respiration, because permafrost C is older (depleted in 14C) than current plant products and soil C cycling operates on timescales of years to centuries. Here, we use 14C analysis of CO2 respired from graminoid tundra in Arctic Alaska to 1) apportion how plant and microbial respiration contribute to ecosystem respiration in spring, summer, and fall, and 2) elucidate the C sources of microbial respiration throughout the year. We used a novel, passive sampling system, capable of trapping diffusive CO2 throughout the active layer of tussock sedge tundra (n=4, from mineral soil to air) over periods of 2 days to 3 weeks in June 2017. CO2 was collected into various sizes of canisters, ranging from 0.5-32 L, and analyzed for its 14C content at UC Irvine's KCCAMS laboratory. To evaluate the system's efficiency, and quantify the temporal and spatial variability of ecosystem respiration sources, we co-deployed 3 Vaisala Carbocap [CO2] and temperature probes, and traditional chambers (n=6) and gas wells (n=10) for sampling of ecosystem- and soil-respired 14CO2 over 15 min-24 hours. A comparison of traditional methods with our new sampler indicates that the system accurately sampled the expected [CO2] depth gradient. The CO2 sampling rate was positively correlated to soil [CO2] (R2=0.963), equivalent to 1.4*10-3±1.6*10-3 mg C/L/month/ppm (n=8). Gas well and probe concentrations were of the same order of magnitude on the same

Quantifying Sources and Fluxes of Aquatic Carbon in U.S. Streams and Reservoirs Using Spatially Referenced Regression Models

Science.gov (United States)

Boyer, E. W.; Smith, R. A.; Alexander, R. B.; Schwarz, G. E.

2004-12-01

Organic carbon (OC) is a critical water quality characteristic in riverine systems that is an important component of the aquatic carbon cycle and energy balance. Examples of processes controlled by OC interactions are complexation of trace metals; enhancement of the solubility of hydrophobic organic contaminants; formation of trihalomethanes in drinking water; and absorption of visible and UV radiation. Organic carbon also can have indirect effects on water quality by influencing internal processes of aquatic ecosystems (e.g. photosynthesis and autotrophic and heterotrophic activity). The importance of organic matter dynamics on water quality has been recognized, but challenges remain in quantitatively addressing OC processes over broad spatial scales in a hydrological context. In this study, we apply spatially referenced watershed models (SPARROW) to statistically estimate long-term mean-annual rates of dissolved- and total- organic carbon export in streams and reservoirs across the conterminous United States. We make use of a GIS framework for the analysis, describing sources, transport, and transformations of organic matter from spatial databases providing characterizations of climate, land use, primary productivity, topography, soils, and geology. This approach is useful because it illustrates spatial patterns of organic carbon fluxes in streamflow, highlighting hot spots (e.g., organic-rich environments in the southeastern coastal plain). Further, our simulations provide estimates of the relative contributions to streams from allochthonous and autochthonous sources. We quantify surface water fluxes of OC with estimates of uncertainty in relation to the overall US carbon budget; our simulations highlight that aquatic sources and sinks of OC may be a more significant component of regional carbon cycling than was previously thought. Further, we are using our simulations to explore the potential role of climate and other changes in the terrestrial environment on

Carbonation-Related Microstructural Changesin Long-Term Durability Concrete

Directory of Open Access Journals (Sweden)

Cláudio A. Rigo da Silva

2002-09-01

Full Text Available This paper discusses the effects of carbonation on the microstructure of Portland cement concrete for long-term durability applications. A class C40 concrete (characteristic compression strength between 40 MPa and 44 MPa on the 28th day, according to Brazilian standard NBR 8953 was chosen for the experimental study of the carbonation effects, from which test samples were molded for accelerated test under a 100%-CO2 atmosphere after physical and mechanical characterization. It was observed that carbonation provoked a reduction of 5% to 12% of the concrete open porosity accessible to water. Flexural strength values obtained after the carbonation tests revealed a decrease of 12% and 25% in relation to the values obtained before tests on the 28th and 91st days, respectively.

Carbon-14 in neutron-irradiated graphite for graphite-moderated reactors. Joint research

Energy Technology Data Exchange (ETDEWEB)

Fujii, Kimio [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Matsuo, Hideto [Radioactive Waste Management and Nuclear Facility Decommissioning Technology Center, Tokyo (Japan)

2002-12-01

The graphite moderated gas cooled reactor operated by the Japan Atomic Power Company was stopped its commercial operation on March 1998, and the decommissioning process has been started. Graphite material is often used as the moderator and the reflector materials in the core of the gas cooled reactor. During the operation, a long life nuclide of {sup 14}C is generated in the graphite by several transmutation reactions. Separation of {sup 14}C isotope and the development of the separation method have been recognized to be critical issues for the decommissioning of the reactor core. To understand the current methodologies for the carbon isotope separation, literature on the subject was surveyed. Also, those on the physical and chemical behavior of {sup 14}C were surveyed. This is because the larger part of the nuclides in the graphite is produced from {sup 14}N by (n,p) reaction, and the location of them in the material tends to be different from those of the other carbon atoms. This report summarizes the result of survey on the open literature about the behavior of {sup 14}C and the separation methods, including the list of the literature on these subjects. (author)

Long term rise of a free aquifer in Sahel: hydrodynamic and radioisotopic estimations (3H, 14C) of the recharge in SW Niger

International Nuclear Information System (INIS)

Favreau, G.

2001-01-01

This article summarizes an hydrodynamic and geochemical survey carried out in SW Niger in order to estimate the impact of rainfall changes and deforestation on the recharge of the uppermost Cretaceous aquifer. 14 C and 3 H activities of the total dissolved inorganic carbon have been used to quantify the long-term recharge of the aquifer. (J.S.)

Influence of carbon source on alpha-amylase production by Aspergillus oryzae

DEFF Research Database (Denmark)

Carlsen, Morten; Nielsen, Jens

2001-01-01

on sucrose, fructose, glycerol, mannitol and acetate. During growth on acetate there was no production of alpha -amylase, whereas addition of small amounts of glucose resulted in alpha -amylase production. A possible induction by alpha -methyl-D-glucoside during growth on glucose was also investigated......, but this compound was not found to be a better inducer of alpha -amylase production than glucose. The results strongly indicate that besides acting as a repressor via the CreA protein, glucose acts as an inducer.......The influence of the carbon source on a-amylase production by Aspergillus oryzae was quantified in carbon-limited chemostat cultures. The following carbon sources were investigated: maltose, maltodextrin (different chain lengths), glucose, fructose, galactose, sucrose, glycerol, mannitol...

Synthesis of a polycyclic aromatic hydrocarbon marked with carbon-14: (b, d e f) dibenzo-chrysene 14C-7,14

International Nuclear Information System (INIS)

Chatelain, G.

1965-01-01

(b, d e f) dibenzo-chrysene C-7,14 has been synthesized from radioactive carbon dioxide and the organic magnesium compound derived from 1,5 dibromo naphthalene. The product has been purified by a very precise series of fractionated chromatographs on alumina having a chromatographic activity. This has necessitated the development of a special technique. (author) [fr

The influence of various carbon and nitrogen sources on oil production by Fusarium oxysporum.

Science.gov (United States)

Joshi, S; Mathur, J M

1987-01-01

The oil-synthesizing capacity of Fusarium oxysporum, cultivated on basal nutrient medium, was evaluated using different carbon and nitrogen sources. In one of the media, molasses was also used as a principal carbon source. Media containing glucose and ammonium nitrate were found to be most efficient for oil production. Fatty acid profile of the fungal oil indicated the presence of a wide range of fatty acids ranging from C8 to C24. Fatty acid composition largely depends on the type of carbon and nitrogen sources.

Photosynthate supply and utilization in alfalfa: a developmental shift from a source to a sink limitation of photosynthesis

International Nuclear Information System (INIS)

Baysdorfer, C.; Bassham, J.A.

1985-01-01

Long-term carbon dioxide enrichment, 14 CO 2 feeding, and partial defoliation were employed as probes to investigate source/sink limitations of photosynthesis during the development of symbiotically grown alfalfa. In the mature crop, long-term CO 2 enrichment does not affect the rates of net photosynthesis, relative growth, 14 C export to nonphotosynthetic organs, or the rates of 14 C label incorporation into leaf sucrose, starch, or malate. The rate of glycolate labeling is, however, substantially reduced under these conditions. When the mature crop was partially defoliated, a considerable increase in net photosynthesis occurred in the remaining leaves. In the seedling crop, long-term CO 2 enrichment increased dry matter accumulation, primarily as a result of increases in leaf starch content. Although the higher rates of starch synthesis are not maintained, the growth enhancement of the enriched plants persisted throughout the experimental period. These results imply a source limitation of seedling photosynthesis and a sink limitation of photosynthesis in more mature plants. Consequently, both the supply and the utilization of photosynthate may limit seasonal photosynthesis in alfalfa

Optical Performance of Carbon-Nanotube Electron Sources

International Nuclear Information System (INIS)

Jonge, Niels de; Allioux, Myriam; Oostveen, Jim T.; Teo, Kenneth B. K.; Milne, William I.

2005-01-01

The figure of merit for the electron optical performance of carbon-nanotube (CNT) electron sources is presented. This figure is given by the relation between the reduced brightness and the energy spread in the region of stable emission. It is shown experimentally that a CNT electron source exhibits a highly stable emission process that follows the Fowler-Nordheim theory for field emission, fixing the relationship among the energy spread, the current, and the radius. The performance of the CNT emitter under realistic operating conditions is compared with state-of-the-art electron point sources. It is demonstrated that the reduced brightness is a function of the tunneling parameter, a measure of the energy spread at low temperatures, only, independent of the geometry of the emitter

36 CFR 14.76 - Terms and conditions.

Science.gov (United States)

2010-07-01

...-OF-WAY Principles and Procedures, Power Transmission Lines § 14.76 Terms and conditions. (a) By... Interior to determine the relationship of the proposed facility to the power marketing program of the... in order to eliminate conflicts with the power-marketing program of the United States, the authorized...

Carbonate-silicate cycle models of the long-term carbon cycle, carbonate accumulation in the oceans, and climate

International Nuclear Information System (INIS)

Caldeira, K.G.

1991-01-01

Several models of the long-term carbon cycle, incorporating models of the carbonate-silicate cycle, were developed and utilized to investigate issues relating to global climate and the causes and consequences of changes in calcium carbonate accumulation in the oceans. Model results indicate that the marked mid-Cretaceous (120 Ma) global warming could be explained by increased rates of release of carbon dioxide from subduction-zone metamorphism and mid-ocean-ridges, in conjunction with paleogeographic factors. Since the mid-Cretaceous, the primary setting for calcium carbonate accumulation in the oceans has shifted from shallow-water to deep-water environments. Model results suggest that this shift could have major consequences for the carbonate-silicate cycle and climate, and lead to significant increases in the flux of metamorphic carbon dioxide to the atmosphere. Increases in pelagic carbonate productivity, and decreases in tropical shallow-water area available for neritic carbonate accumulation, have both been proposed as the primary cause of this shift. Two lines of evidence developed here (one involving a statistical analysis of Tertiary carbonate-accumulation and oxygen-isotope data, and another based on modeling the carbonate-silicate cycle and ocean chemistry) suggest that a decrease in tropical shallow-water area was more important than increased pelagic productivity in explaining this shift. Model investigations of changes in ocean chemistry at the Cretaceous/Tertiary (K/T) boundary (66 Ma) indicate that variations in deep-water carbonate productivity may affect shallow-water carbonate accumulation rates through a mechanism involving surface-water carbonate-ion concentration. In the aftermath of the K/T boundary event, deep-water carbonate production and accumulation were significantly reduced as a result of the extinction of calcareous plankton

Immobilization of carbon-14 from reactor graphite waste by use of self-sustaining reaction in the C-Al-TiO2 system

International Nuclear Information System (INIS)

Karlina, O.K.; Klimov, V.L.; Ojovan, M.I.; Pavlova, G.Yu.; Dmitriev, S.A.; Yurchenko, A.Yu.

2005-01-01

As a result of long-term neutron irradiation, the long-lived 14 C is produced in the reactor graphite. The exothermic self-sustaining reaction 3C(graphite) + 4Al + 3TiO 2 = 3TiC + 2Al 2 O 3 was proposed for processing of such waste. In doing so, the carbon, including the 14 C, is chemically bound in the stable TiC. The reaction products in the C-Al-TiO 2 system were investigated both by thermodynamic simulation and experimentally in the course of this work

Effects of carbon and nitrogen sources on the induction and ...

African Journals Online (AJOL)

user

about the induction and repression mechanism of this hydrolytic enzyme. This report ... chitin as a sole source of carbon followed by the medium containing an extra nitrogen source, yeast extract. .... against fluorescent background by UV illumination. Statistical ..... Virulence Associated with Native and Mutant Isolates of an.

Quantitative carbon-14 autoradiography at the cellular level: principles and application for cell kinetic studies. [Review

Energy Technology Data Exchange (ETDEWEB)

Doermer, P [Gesellschaft fuer Strahlen- und Umweltforschung m.b.H., Muenchen (Germany, F.R.). Inst. fuer Haematologie

1981-03-01

Amounts of radio-labelled substances as low as 10/sup -18/ moles incorporated into individual cells can be measured by utilizing techniques of quantitative autoradiography. The principles and application of quantitative carbon-14 autoradiography are reviewed. Silver grain densities can be counted by automated microphotometry allowing on-line data processing by an interfaced computer. Rate measurements of /sup 14/C-thymidine incorporation into individual cells yield values of the DNA synthesis rate and the DNA synthesis time of a cell compartment can be derived. This is an essential time parameter for the evaluation of kinetic events in proliferating cell populations. This method is applicable to human cells without radiation hazard to man and provides an optimal source of detailed information on the kinetics of normal and diseased human haematopoiesis. Examples of application consist of thalassaemia, malaria infection, iron deficiency anaemia and acute myelogenous leukaemia.

Metabolism of carbon-14 labelled l-tryptophan, l-kynerenine and hydroxy-l-kynerenine in miners with scleroderma

International Nuclear Information System (INIS)

Hankes, L.V.; De Bruin, E.; Jansen, C.R.; Voster, L.; Schmaeler, M.

1977-01-01

Six South African white miners were studied with the 2-g l-tryptophan load test and tracer doses of L-tryptophan-7a-carbon-14, L-kynurenine-keto-carbon-14 and hydroxy-L-kynerenine-keto-carbon-14. The breath 14 CO 2 and 14 urinary metabolites were measured. When they were compared with a previous study of American women with scleroderma, similar 14 CO 2 and tryptophan metabolite excretion patterns were observed in the data from the miners. The labelled quinolinic acid excretion was more significantly elevated in the South African miners' urine than in the urine of the American women. The data from both studies suggest that some patients with scleroderma have an altered step in the tryptophan metabolic pathway after hydroxy-anthranilic acid. What relationship exists between the induction of pulmonary silicosis and the subsequent development of scleroderma, requires additional human studies

Estimation of Source Term Behaviors in SBO Sequence in a Typical 1000MWth PWR and Comparison with Other Source Term Results

Energy Technology Data Exchange (ETDEWEB)

Kim, Tae Woon; Han, Seok Jung; Ahn, Kwang Il; Fynan, Douglas; Jung, Yong Hoon [KAERI, Daejeon (Korea, Republic of)

2016-05-15

Since the Three Mile Island (TMI) (1979), Chernobyl (1986), Fukushima Daiichi (2011) accidents, the assessment of radiological source term effects on the environment has been a key concern of nuclear safety. In the Fukushima Daiichi accident, the long-term SBO (station blackout) accident occurs. Using the worst case assumptions like in Fukushima accident on the accident sequences and on the availability of safety systems, the thermal hydraulic behaviors, core relocation and environmental source terms behaviors are estimated for long-term SBO accident for OPR-1000 reactor. MELCOR code version 1.8.6 is used in this analysis. Source term results estimated in this study is compared with other previous studies and estimated results in Fukushima accidents in UNSCEAR-2013 report. This study estimated that 11 % of iodine can be released to environment and 2% of cesium can be released to environment. UNSCEAR-2013 report estimated that 2 - 8 % of iodine have been released to environment and 1 - 3 % of cesium have been released to the environment. They have similar results in the aspect of release fractions of iodine and cesium to environment.

Mangroves, a major source of dissolved organic carbon to the oceans

Science.gov (United States)

Dittmar, Thorsten; Hertkorn, Norbert; Kattner, Gerhard; Lara, RubéN. J.

2006-03-01

Organic matter, which is dissolved in low concentrations in the vast waters of the oceans, contains a total amount of carbon similar to atmospheric carbon dioxide. To understand global biogeochemical cycles, it is crucial to quantify the sources of marine dissolved organic carbon (DOC). We investigated the impact of mangroves, the dominant intertidal vegetation of the tropics, on marine DOC inventories. Stable carbon isotopes and proton nuclear magnetic resonance spectroscopy showed that mangroves are the main source of terrigenous DOC in the open ocean off northern Brazil. Sunlight efficiently destroyed aromatic molecules during transport offshore, removing about one third of mangrove-derived DOC. The remainder was refractory and may thus be distributed over the oceans. On a global scale, we estimate that mangroves account for >10% of the terrestrially derived, refractory DOC transported to the ocean, while they cover only <0.1% of the continents' surface.

Food sources for the mangrove tree crab aratus pisonii: a carbon isotopic study

International Nuclear Information System (INIS)

Lacerda, L.D.; Silva, C.A.R.; Rezende, C.E.; Martinelli, L.A.

1991-01-01

Muscle tissues from the mangrove tree crab Aratus pisonii was analysed for carbon isotopic composition, in order to trace its major food sources. Potential food sources: mangrove leaves epi phytic green algae, mangrove sediments and open water and mangrove suspended matter; were also analysed. The results show that A. pisonii is basically omnivorous, with major food sources from marine origin. However, mangrove carbon can contribute with 16% to 42% in the crab's diet. (author)

Synthesis of {delta}-aminolevulic acid. Application to the introduction of carbon-14 and of tritium; Syntheses de l'acide {delta} aminolevulique. Application a l'introduction de carbone 14 et de tritium

Energy Technology Data Exchange (ETDEWEB)

Loheac, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1966-06-01

Several new syntheses of {delta} aminolevulic acid ({delta} A.L.A.) have been studied. {sup 14}C-4 {delta} - aminolevulic acid has been obtained from {sup 14}C allylacetic carboxylic acid with a yield of 30 per cent with respect to barium carbonate and with a specific activity of 32 mCi/mM. The {sup 14}C-1 or {sup 14}C-2 {delta}-A.L.A. has been prepared from the {sup 14}C-1 or {sup 14}C-2 acetate with a yield of 55 per cent with respect to the acetate. Finally the tritiated {delta}-A.L.A. has been obtained for the first time by tritiation of ethyl phthalimidodehydrolevulate. (author) [French] Plusieurs syntheses nouvelles de l'acide {delta}-aminolevulique ont ete etudiees. L'acide {delta}-aminolevulique {sup 14}C-4 a ete obtenu a partir d'acide allylacetique carboxylique {sup 14}C, avec un rendement global de 30 pour cent par rapport au carbonate de baryum a une activite specifique de 32 mCi/M. Le {delta}-A.A.L. {sup 14}C-1 ou {sup 14}C-2 a ete obtenu a partir d'acetate {sup 14}C-1 ou {sup 14}C-2 avec un rendement de 55 pour cent par rapport a l'acetate. Enfin le {delta}-A.A.L. tritie a ete obtenu pour la premiere fois par tritiation du phtalimidodehydrolevulate d'ethyle. (auteur)

Evaluating vertical concentration profile of carbon source released from slow-releasing carbon source tablets and in situ biological nitrate denitrification activity

Science.gov (United States)

Yeum, Y.; HAN, K.; Yoon, J.; Lee, J. H.; Song, K.; Kang, J. H.; Park, C. W.; Kwon, S.; Kim, Y.

2017-12-01

Slow-releasing carbon source tablets were manufactured during the design of a small-scale in situ biological denitrification system to reduce high-strength nitrate (> 30 mg N/L) from a point source such as livestock complexes. Two types of slow-releasing tablets, precipitating tablet (PT, apparent density of 2.0 g/mL) and floating tablet (FT), were prepared to achieve a vertically even distribution of carbon source (CS) in a well and an aquifer. Hydroxypropyl methylcellulose (HPMC) was used to control the release rate, and microcrystalline cellulose pH 101 (MCC 101) was added as a binder. The #8 sand was used as a precipitation agent for the PTs, and the floating agents for the FTs were calcium carbonate and citric acid. FTs floated within 30 min. and remained in water because of the buoyance from carbon dioxide, which formed during the acid-base reaction between citric acid and calcium carbonate. The longevities of PTs with 300 mg of HPMC and FTs with 400 mg of HPMC were 25.4 days and 37.3 days, respectively. We assessed vertical CS profile in a continuous flowing physical aquifer model (release test, RT) and its efficiency on biological nitrate denitrification (denitrification test, DT). During the RT, PTs, FTs and a tracer (as 1 mg rhodamine B/L) were initially injected into a well of physical aquifer model (PAM). Concentrations of CS and the tracer were monitored along the streamline in the PAM to evaluate vertical profile of CS. During the DT, the same experiment was performed as RT, except continuous injection of solution containing 30 mg N/L into the PAM to evaluate biological denitrification activity. As a result of RT, temporal profiles of CS were similar at 3 different depths of monitoring wells. These results suggest that simultaneous addition of PT and FT be suitable for achieving a vertically even distribution of the CS in the injection well and an aquifer. In DT, similar profile of CS was detected in the injection well, and nitrate was biologically

Carbon-14 behavior in a cement-dominated environment: Implications for spent CANDU resin waste disposal

International Nuclear Information System (INIS)

Dayal, R.; Reardon, E.J.

1994-01-01

Cement based waste forms and concrete engineered barriers are expected to play a key role in providing 14 C waste containment and control 14 C migration for time periods commensurate with its hazardous life of about 50,000 years. The main thrust of this study was, therefore, to evaluate the performance of cement based waste forms with regard to 14 C containment. Of particular importance are the geochemical processes controlling 14 C solubility and release under anticipated cement dominated low and intermediate level waste repository conditions. Immobilization of carbonate-form exchange resin in grout involves transfer of sorbed 14 CO 3 2- ions, through exchange for hydroxyl ions from the grout slurry, followed by localized precipitation of solid calcium carbonate at the cement/resin interface in the grout matrix. Carbon-14 release behavior can be attributed to the dissolution characteristics and solubility of calcite present in the cement based waste form. The groundwater flow regime can exert a pronounced effect both on the near-field chemistry and the leaching behavior of 14 C. For a cement dominated repository, at relatively low-flow or stagnant groundwater conditions, the alkaline near-field chemical environments inhibits the release of 14 C from the cemented waste form. Under high flow conditions, the near-field environment is characterized by relatively neutral pH conditions which promote calcite dissolution, thus resulting in 14 C release from the waste form

Occult carbon monoxide poisoning.

Science.gov (United States)

Kirkpatrick, J N

1987-01-01

A syndrome of headache, fatigue, dizziness, paresthesias, chest pain, palpitations and visual disturbances was associated with chronic occult carbon monoxide exposure in 26 patients in a primary care setting. A causal association was supported by finding a source of carbon monoxide in a patient's home, workplace or vehicle; results of screening tests that ruled out other illnesses; an abnormally high carboxyhemoglobin level in 11 of 14 patients tested, and abatement or resolution of symptoms when the source of carbon monoxide was removed. Exposed household pets provided an important clue to the diagnosis in some cases. Recurrent occult carbon monoxide poisoning may be a frequently overlooked cause of persistent or recurrent headache, fatigue, dizziness, paresthesias, abdominal pain, diarrhea and unusual spells.

Selection of models to calculate the LLW source term

International Nuclear Information System (INIS)

Sullivan, T.M.

1991-10-01

Performance assessment of a LLW disposal facility begins with an estimation of the rate at which radionuclides migrate out of the facility (i.e., the source term). The focus of this work is to develop a methodology for calculating the source term. In general, the source term is influenced by the radionuclide inventory, the wasteforms and containers used to dispose of the inventory, and the physical processes that lead to release from the facility (fluid flow, container degradation, wasteform leaching, and radionuclide transport). In turn, many of these physical processes are influenced by the design of the disposal facility (e.g., infiltration of water). The complexity of the problem and the absence of appropriate data prevent development of an entirely mechanistic representation of radionuclide release from a disposal facility. Typically, a number of assumptions, based on knowledge of the disposal system, are used to simplify the problem. This document provides a brief overview of disposal practices and reviews existing source term models as background for selecting appropriate models for estimating the source term. The selection rationale and the mathematical details of the models are presented. Finally, guidance is presented for combining the inventory data with appropriate mechanisms describing release from the disposal facility. 44 refs., 6 figs., 1 tab

Review of SFR In-Vessel Radiological Source Term Studies

International Nuclear Information System (INIS)

Suk, Soo Dong; Lee, Yong Bum

2008-10-01

An effort has been made in this study to search for and review the literatures in public domain on the studies of the phenomena related to the release of radionuclides and aerosols to the reactor containment of the sodium fast reactor (SFR) plants (i.e., in-vessel source term), made in Japan and Europe including France, Germany and UK over the last few decades. Review work is focused on the experimental programs to investigate the phenomena related to determining the source terms, with a brief review on supporting analytical models and computer programs. In this report, the research programs conducted to investigate the CDA (core disruptive accident) bubble behavior in the sodium pool for determining 'primary' or 'instantaneous' source term are first introduced. The studies performed to determine 'delayed source term' are then described, including the various stages of phenomena and processes: fission product (FP) release from fuel , evaporation release from the surface of the pool, iodine mass transfer from fission gas bubble, FP deposition , and aerosol release from core-concrete interaction. The research programs to investigate the release and transport of FPs and aerosols in the reactor containment (i.e., in-containment source term) are not described in this report

Flux density measurements of radio sources at 2.14 millimeter wavelength

International Nuclear Information System (INIS)

Cogdell, J.R.; Davis, J.H.; Ulrich, B.T.; Wills, B.J.

1975-01-01

Flux densities of galactic and extragalactic sources, and planetary temperatures, have been measured at 2.14 mm wavelength (140 GHz). Results are presented for OJ 287; the galactic sources DR 21, W3, and Orion A; the extragalactic sources PKS 0106plus-or-minus01, 3C 84, 3C 120, BL Lac, 3C 216, 3C 273, 3C 279, and NGC 4151; and the Sun, Venus, Mars, and Jupiter. Also presented is the first measurement of the 2.14-mm temperature of Uranus. The spectra of some of these sources are discussed. The flux density scale was calibrated absolutely. The measurements were made with a new continuum receiver on the 4.88-m radio telescope of The University of Texas

Utility view of the source term and air cleaning

International Nuclear Information System (INIS)

Littlefield, P.S.

1985-01-01

The utility view of the source term and air cleaning is discussed. The source term is made up of: (1) noble gases, which there has been a tendency to ignore in the past because it was thought there was nothing that could be done with them anyway, (2) the halogens, which have been dealt with in Air Cleaning Conferences in the past in terms of charcoal and other systems for removing them, and (3) the solid components of the source term which particulate filters are designed to handle. Air cleaning systems consist of filters, adsorbers, containment sprays, suppression pools in boiling water reactors and ice beds in ice condenser-equipped plants. The feasibility and cost of air cleaning systems are discussed

Secondary organic carbon quantification and source apportionment of PM10 in Kaifeng, China

Institute of Scientific and Technical Information of China (English)

WU Lin; FENG Yinchang; WU Jianhui; ZHU Tan; BI Xiaohui; HAN Bo; YANG Weihong; YANG Zhiqiang

2009-01-01

During 2005, the filter samples of ambient PM10 from five sites and the source samples of particulate matter were collected in Kaifeng, Henan province of China. Nineteen elements, water-soluble ions, total carbon (TC) and organic carbon (OC) contained in samples were analyzed. Seven contributive source types were identified and their contributions to ambient PM10 were estimated by chemical mass balance (CMB) receptor model. Weak associations between the concentrations of organic carbon and element carbon (EC) were observed during the sampling periods, indicating that there was secondary organic aerosol pollution in the urban atmosphere. An indirect method of "OC/EC minimum ratio" was applied to estimate the concentration of secondary organic carbon (SOC). The results showed that SOC contributed 26.2%, 32.4% and 18.0% of TC in spring, summer-fall and winter respectively, and the annual average SOC concentration was 7.07 μg/m3, accounting for 5.73% of the total mass in ambient PM10. The carbon species concentrations in ambient PM10 were recalculated by subtracting the SOC concentrations from measured concentrations of TC and OC to increase the compatibility of source and receptor measurements for CMB model.

Electron source with a carbon-fibrous cathode for radiation-technology accelerator

International Nuclear Information System (INIS)

Korenev, S.A.

1994-01-01

The paper analyses the circuit of a full operating voltage electron source which is a direct-action electron accelerator. The electron source consists of a power supply, high-voltage multiplier-rectifier, vacuum planar diode, vacuum system and control system. The vacuum electron diode contains an autoemission carbon-fibrous cathode and beryllium foil strip anode. The results of measurements of emission characteristics of alumosilicate and carbon-fibrous cathodes are presented. The investigations into test electron source show that it can be used as a basis for creating an electron accelerator which will be capable of generating 1 MW electron beams of 1-2 MeV energy and 1 A current. 3 refs., 1 fig., 1 tab

The near-term impacts of carbon mitigation policies on manufacturing industries

International Nuclear Information System (INIS)

Morgenstern, Richard D.; Ho Mun; Shih, J.-S.; Zhang Xuehua

2004-01-01

Who pays for new policies to reduce carbon dioxide and other greenhouse gas emissions in the United States? This paper considers a slice of the question by examining the near-term impact on domestic manufacturing industries of both upstream (economy-wide) and downstream (electric power industry only) carbon mitigation policies. Detailed Census data on the electricity use of four-digit manufacturing industries are combined with input-output information on inter-industry purchases to paint a detailed picture of carbon use, including effects on final demand. Regional information on electricity supply and use by region is also incorporated. A relatively simple model is developed which yields estimates of the relative burdens within the manufacturing sector of alternative carbon policies. Overall, the principal conclusion is that within the manufacturing sector (which by definition excludes coal production and electricity generation), only a small number of industries would bear a disproportionate short-term burden of a carbon tax or similar policy. Not surprisingly, an electricity-only policy affects very different manufacturing industries than an economy-wide carbon tax

Long-term sampling of CO2 from waste-to-energy plants: 14C determination methodology, data variation and uncertainty

DEFF Research Database (Denmark)

Fuglsang, Karsten; Pedersen, Niels Hald; Larsen, Anna Warberg

2014-01-01

A dedicated sampling and measurement method was developed for long-term measurements of biogenic and fossil-derived CO2 from thermal waste-to-energy processes. Based on long-term sampling of CO2 and 14C determination, plant-specific emission factors can be determined more accurately, and the annual...... emission of fossil CO2 from waste-to-energy plants can be monitored according to carbon trading schemes and renewable energy certificates. Weekly and monthly measurements were performed at five Danish waste incinerators. Significant variations between fractions of biogenic CO2 emitted were observed...... was ± 4.0 pmC (95 % confidence interval) at 62 pmC. The long-term sampling method was found to be useful for waste incinerators for determination of annual fossil and biogenic CO2 emissions with relatively low uncertainty....

Conceptual Design of a 14-MeV D-T Neutron Source for Material Inspection

International Nuclear Information System (INIS)

Kim, Jin-Choon; Oh, Byung-Hoon

2007-01-01

There is a worldwide need for the efficient inspection of cargo containers at airports, seaports and border crossings. And there is also a growing need for nondestructive inspection of metal objects such as airplane parts. The limitations of X-ray systems for the detection of explosives, drugs, and thick metal structures have stimulated interest in neutron radiograph or tomography. The weak link in such applications is the neutron source. The ideal neutron source should provide a high intensity, high-energy for sufficient penetration and activation, a reliable long-term operation, and a monoenergetic neutron beam. In this paper, we describe a conceptual design of a DT fusion neutron source (monoenergetic 14 MeV neutron generator) which satisfies the fore-mentioned requirements. The current design is based upon the actually proven system using the drive-in target principle. The design is versatile enough to accommodate various applications, ranging from material inspection and explosive interrogation to medical probing and cancer treatment

Low-level radioactive waste performance assessments: Source term modeling

International Nuclear Information System (INIS)

Icenhour, A.S.; Godbee, H.W.; Miller, L.F.

1995-01-01

Low-level radioactive wastes (LLW) generated by government and commercial operations need to be isolated from the environment for at least 300 to 500 yr. Most existing sites for the storage or disposal of LLW employ the shallow-land burial approach. However, the U.S. Department of Energy currently emphasizes the use of engineered systems (e.g., packaging, concrete and metal barriers, and water collection systems). Future commercial LLW disposal sites may include such systems to mitigate radionuclide transport through the biosphere. Performance assessments must be conducted for LUW disposal facilities. These studies include comprehensive evaluations of radionuclide migration from the waste package, through the vadose zone, and within the water table. Atmospheric transport mechanisms are also studied. Figure I illustrates the performance assessment process. Estimates of the release of radionuclides from the waste packages (i.e., source terms) are used for subsequent hydrogeologic calculations required by a performance assessment. Computer models are typically used to describe the complex interactions of water with LLW and to determine the transport of radionuclides. Several commonly used computer programs for evaluating source terms include GWSCREEN, BLT (Breach-Leach-Transport), DUST (Disposal Unit Source Term), BARRIER (Ref. 5), as well as SOURCE1 and SOURCE2 (which are used in this study). The SOURCE1 and SOURCE2 codes were prepared by Rogers and Associates Engineering Corporation for the Oak Ridge National Laboratory (ORNL). SOURCE1 is designed for tumulus-type facilities, and SOURCE2 is tailored for silo, well-in-silo, and trench-type disposal facilities. This paper focuses on the source term for ORNL disposal facilities, and it describes improved computational methods for determining radionuclide transport from waste packages

Russia's black carbon emissions: focus on diesel sources

Directory of Open Access Journals (Sweden)

N. Kholod

2016-09-01

Full Text Available Black carbon (BC is a significant climate forcer with a particularly pronounced forcing effect in polar regions such as the Russian Arctic. Diesel combustion is a major global source of BC emissions, accounting for 25–30 % of all BC emissions. While the demand for diesel is growing in Russia, the country's diesel emissions are poorly understood. This paper presents a detailed inventory of Russian BC emissions from diesel sources. Drawing on a complete Russian vehicle registry with detailed information about vehicle types and emission standards, this paper analyzes BC emissions from diesel on-road vehicles. We use the COPERT emission model (COmputer Programme to calculate Emissions from Road Transport with Russia-specific emission factors for all types of on-road vehicles. On-road diesel vehicles emitted 21 Gg of BC in 2014: heavy-duty trucks account for 60 % of the on-road BC emissions, while cars represent only 5 % (light commercial vehicles and buses account for the remainder. Using Russian activity data and fuel-based emission factors, the paper also presents BC emissions from diesel locomotives and ships, off-road engines in industry, construction and agriculture, and generators. The study also factors in the role of superemitters in BC emissions from diesel on-road vehicles and off-road sources. The total emissions from diesel sources in Russia are estimated to be 49 Gg of BC and 17 Gg of organic carbon (OC in 2014. Off-road diesel sources emitted 58 % of all diesel BC in Russia.

Literature study of source term research for PWRs

Energy Technology Data Exchange (ETDEWEB)

Sponton, L.L.; NiIsson, Lars

2001-04-01

A literature survey has been carried out in support of ongoing source term calculations with the MELCOR code of some severe accident scenarios for the Swedish Ringhals 2 pressurised water reactor (PWR). The research in the field of severe accidents in power reactors and the source term for subsequent release of radioisotopes was intensified after the Harrisburg accident and has produced a large amount of reports and papers. This survey was therefore limited to research concerning PWR type of reactors and with emphasis on papers related to MELCOR code development. A background is given, relating to some historic documents, and then more recent research after 1990 is reviewed. Of special interest is the ongoing PMbus-programme which is creating new and important results of benefit to the code development and validation of, among others, the MELCOR code. It is concluded that source term calculations involve simulation of many interacting complex physical phenomena, which result in large uncertainties The research has, however, over the years led to considerable improvements Thus has the uncertainty in source term predictions been reduced one to two orders of magnitude from the simpler codes in the early 1980-s to the more realistic codes of today, like MELCOR.

Literature study of source term research for PWRs

International Nuclear Information System (INIS)

Sponton, L.L.; NiIsson, Lars

2001-04-01

A literature survey has been carried out in support of ongoing source term calculations with the MELCOR code of some severe accident scenarios for the Swedish Ringhals 2 pressurised water reactor (PWR). The research in the field of severe accidents in power reactors and the source term for subsequent release of radioisotopes was intensified after the Harrisburg accident and has produced a large amount of reports and papers. This survey was therefore limited to research concerning PWR type of reactors and with emphasis on papers related to MELCOR code development. A background is given, relating to some historic documents, and then more recent research after 1990 is reviewed. Of special interest is the ongoing PMbus-programme which is creating new and important results of benefit to the code development and validation of, among others, the MELCOR code. It is concluded that source term calculations involve simulation of many interacting complex physical phenomena, which result in large uncertainties The research has, however, over the years led to considerable improvements Thus has the uncertainty in source term predictions been reduced one to two orders of magnitude from the simpler codes in the early 1980-s to the more realistic codes of today, like MELCOR

Reassessment of the technical bases for estimating source terms. Final report

International Nuclear Information System (INIS)

Silberberg, M.; Mitchell, J.A.; Meyer, R.O.; Ryder, C.P.

1986-07-01

This document describes a major advance in the technology for calculating source terms from postulated accidents at US light-water reactors. The improved technology consists of (1) an extensive data base from severe accident research programs initiated following the TMI accident, (2) a set of coupled and integrated computer codes (the Source Term Code Package), which models key aspects of fission product behavior under severe accident conditions, and (3) a number of detailed mechanistic codes that bridge the gap between the data base and the Source Term Code Package. The improved understanding of severe accident phenonmena has also allowed an identification of significant sources of uncertainty, which should be considered in estimating source terms. These sources of uncertainty are also described in this document. The current technology provides a significant improvement in evaluating source terms over that available at the time of the Reactor Safety Study (WASH-1400) and, because of this significance, the Nuclear Regulatory Commission staff is recommending its use

Regulatory impact of nuclear reactor accident source term assumptions. Technical report

International Nuclear Information System (INIS)

Pasedag, W.F.; Blond, R.M.; Jankowski, M.W.

1981-06-01

This report addresses the reactor accident source term implications on accident evaluations, regulations and regulatory requirements, engineered safety features, emergency planning, probabilistic risk assessment, and licensing practice. Assessment of the impact of source term modifications and evaluation of the effects in Design Basis Accident analyses, assuming a change of the chemical form of iodine from elemental to cesium iodide, has been provided. Engineered safety features used in current LWR designs are found to be effective for all postulated combinations of iodine source terms under DBA conditions. In terms of potential accident consequences, it is not expected that the difference in chemical form between elemental iodine and cesium iodide would be significant. In order to account for the current information on source terms, a spectrum of accident scenerios is discussed to realistically estimate the source terms resulting from a range of potential accident conditions

The source apportionment of carbonaceous combustion products by micro-radiocarbon measurements for the integrated air cancer project (IACP)

International Nuclear Information System (INIS)

Klouda, G.A.; Currie, L.A.; Sheffield, A.E.; Wise, S.A.; Benner, B.A.; Stevens, R.K.; Merrill, R.G.

1987-01-01

Atmospheric particle samples were collected during the winter of 1984-1985 in Albuquerque, NM and Raleigh, NC by the EPA for the Integrated Air Cancer Project (IACP). Selected chemical fractions were analyzed for /sup 14/C to apportion mobile (motor vehicles) and stationary (residential wood combustion) sources. In addition, these results were used to validate the EPA Single Tracer Regression Model (STRM), also a technique for the source apportionment of aerosols. Preliminary /sup 14/C results for the Albuquerque residential site at night showed 79% Contemporary Carbon (CC) compared to 95% CC for Raleight at night for the total carbon; 88% and 94% of the total-C was organic, respectively. The Albuquerque traffic site during the day showed 1.4 to 3.9 times less CC compared to the daytime residential site for total-C. The elemental carbon fraction in all cases showed a lower percentage of contemporary carbon than the total carbon, which indicates that this chemical fraction may be an excellent tracer of mobile sources. These results are consistent with a daytime mobile source at the traffic site and a nighttime Residential Wood Combustion (RWC) source at the residential site. Also, the results from the EPA STRM technique for this study were in good agreement with those obtained by the /sup 14/C Direct Tracer (/sup 14/C-DT) technique for source apportionment of these aerosols

Determination of the growth of nematophagous fungi on diverse carbon sources

Directory of Open Access Journals (Sweden)

Martha Orozco

2015-11-01

Full Text Available Organic amendments have been widely used to stimulate the populations of predatory nematophagous fungi (PNF in soil; however, the use of organic amendments has produced inconsistent results in the control of parasitic nematodes. The inconsistencies have been partially attributed to the chemical composition of the organic amendments, specifically to carbon and nitrogen contents. Therefore, to know the carbon preferences of these fungi could be helpful to promote the predatory phase of the PNF in soil. The aim of this study was to determine the growth of native PNF strains from Costa Rica in diverse carbon sources. The PNF Arthrobotrys oligospora and Candelabrella musiformis were grown in artificial culture media containing the following carbon sources: cellulose, chitin, pectin, starch, and skim milk. The growth rate developed by the PNF in each one of the culture media was determined and compared. The growth rates developed by both fungal species followed the next order: cellulos e>chitin>pectin>starch>skim milk. Significant differences in the growth rates developed by the fungal strains were detected only in culture medium containing cellulose, in comparison with culture media containing other carbon sources. In culture medium containing cellulose both A. oligospora and C. musiformis grew faster with respect to the other culture media, but A. oligospora strains grew faster in comparison with C. musiformis strains. Both fungal species developed the lowest growth rates in culture media containing starch and skim milk.

Paleotempestological chronology developed from gas ion source AMS analysis of carbonates determined through real-time Bayesian statistical approach

Science.gov (United States)

Wallace, D. J.; Rosenheim, B. E.; Roberts, M. L.; Burton, J. R.; Donnelly, J. P.; Woodruff, J. D.

2014-12-01

Is a small quantity of high-precision ages more robust than a higher quantity of lower-precision ages for sediment core chronologies? AMS Radiocarbon ages have been available to researchers for several decades now, and precision of the technique has continued to improve. Analysis and time cost is high, though, and projects are often limited in terms of the number of dates that can be used to develop a chronology. The Gas Ion Source at the National Ocean Sciences Accelerator Mass Spectrometry Facility (NOSAMS), while providing lower-precision (uncertainty of order 100 14C y for a sample), is significantly less expensive and far less time consuming than conventional age dating and offers the unique opportunity for large amounts of ages. Here we couple two approaches, one analytical and one statistical, to investigate the utility of an age model comprised of these lower-precision ages for paleotempestology. We use a gas ion source interfaced to a gas-bench type device to generate radiocarbon dates approximately every 5 minutes while determining the order of sample analysis using the published Bayesian accumulation histories for deposits (Bacon). During two day-long sessions, several dates were obtained from carbonate shells in living position in a sediment core comprised of sapropel gel from Mangrove Lake, Bermuda. Samples were prepared where large shells were available, and the order of analysis was determined by the depth with the highest uncertainty according to Bacon. We present the results of these analyses as well as a prognosis for a future where such age models can be constructed from many dates that are quickly obtained relative to conventional radiocarbon dates. This technique currently is limited to carbonates, but development of a system for organic material dating is underway. We will demonstrate the extent to which sacrificing some analytical precision in favor of more dates improves age models.

Carbon source from the toroidal pumped limiter during long discharge operation in Tore Supra

International Nuclear Information System (INIS)

Dufour, E.; Brosset, C.; Lowry, C.; Bucalossi, J.; Chappuis, P.; Corre, Y.; Desgranges, C.; Guirlet, R.; Gunn, J.; Loarer, T.; Mitteau, R.; Monier-Garbet, P.; Pegourie, B.; Reichle, R.; Thomas, P.; Tsitrone, E.; Hogan, J.; Roubin, P.; Martin, C.; Arnas, C.

2005-01-01

A better understanding of deuterium retention mechanisms requires the knowledge of carbon sources in Tore-Supra. The main source of carbon in the vacuum vessel during long discharges is the toroidal pumped limiter (TPL). This work is devoted to the experimental characterisation of the carbon source from the TPL surface during long discharges using a visible spectroscopy diagnostic. Moreover, we present an attempt to perform a carbon balance over a typical campaign and we discuss it with regards to the deuterium in-vessel inventory deduced from particle balance and the deuterium content of the deposited layers. The study shows that only a third of the estimated deuterium trapped in the vessel is trapped in the carbon deposits. Thus, in the present state of our knowledge and characterisation of the permanent retention, one has to search for mechanisms other than co-deposition to explain the deuterium retention in Tore Supra. (A.C.)

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

Science.gov (United States)

Han, Liang-Feng; Plummer, 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

Carbon source-sink limitations differ between two species with contrasting growth strategies.

Science.gov (United States)

Burnett, Angela C; Rogers, Alistair; Rees, Mark; Osborne, Colin P

2016-11-01

Understanding how carbon source and sink strengths limit plant growth is a critical knowledge gap that hinders efforts to maximize crop yield. We investigated how differences in growth rate arise from source-sink limitations, using a model system comparing a fast-growing domesticated annual barley (Hordeum vulgare cv. NFC Tipple) with a slow-growing wild perennial relative (Hordeum bulbosum). Source strength was manipulated by growing plants at sub-ambient and elevated CO 2 concentrations ([CO 2 ]). Limitations on vegetative growth imposed by source and sink were diagnosed by measuring relative growth rate, developmental plasticity, photosynthesis and major carbon and nitrogen metabolite pools. Growth was sink limited in the annual but source limited in the perennial. RGR and carbon acquisition were higher in the annual, but photosynthesis responded weakly to elevated [CO 2 ] indicating that source strength was near maximal at current [CO 2 ]. In contrast, photosynthetic rate and sink development responded strongly to elevated [CO 2 ] in the perennial, indicating significant source limitation. Sink limitation was avoided in the perennial by high sink plasticity: a marked increase in tillering and root:shoot ratio at elevated [CO 2 ], and lower non-structural carbohydrate accumulation. Alleviating sink limitation during vegetative development could be important for maximizing growth of elite cereals under future elevated [CO 2 ]. © 2016 John Wiley & Sons Ltd.

Sources of uncertainties in modelling black carbon at the global scale

NARCIS (Netherlands)

Vignati, E.; Karl, M.; Krol, M.C.; Wilson, J.; Stier, P.; Cavalli, F.

2010-01-01

Our understanding of the global black carbon (BC) cycle is essentially qualitative due to uncertainties in our knowledge of its properties. This work investigates two source of uncertainties in modelling black carbon: those due to the use of different schemes for BC ageing and its removal rate in

Nasu 1.4 GHz Interferometer Transient Radio Source Survey and Improvement in Detection of Radio Sources

International Nuclear Information System (INIS)

Matsumura, Nobuo; Kuniyoshi, Masaya; Takefuji, Kazuhiro; Niinuma, Kotaro; Kida, Sumiko; Takeuchi, Akihiko; Asuma, Kuniyuki; Daishido, Tsuneaki

2006-01-01

We have surveyed 1.4GHz transient radio sources in Nasu Pulsar Observatory. To investigate such sources, both immediacy and accuracy are severely maintained. We have developed Data Transfer System and improved antenna control system. Now we have received the fringe data from transient radio source candidates. To get reliable information, we carefully analyze with Fringe Band Pass Filter software and Fringe Fitting method

Quantity of dates trumps quality of dates for dense Bayesian radiocarbon sediment chronologies - Gas ion source 14C dating instructed by simultaneous Bayesian accumulation rate modeling

Science.gov (United States)

Rosenheim, B. E.; Firesinger, D.; Roberts, M. L.; Burton, J. R.; Khan, N.; Moyer, R. P.

2016-12-01

Radiocarbon (14C) sediment core chronologies benefit from a high density of dates, even when precision of individual dates is sacrificed. This is demonstrated by a combined approach of rapid 14C analysis of CO2 gas generated from carbonates and organic material coupled with Bayesian statistical modeling. Analysis of 14C is facilitated by the gas ion source on the Continuous Flow Accelerator Mass Spectrometry (CFAMS) system at the Woods Hole Oceanographic Institution's National Ocean Sciences Accelerator Mass Spectrometry facility. This instrument is capable of producing a 14C determination of +/- 100 14C y precision every 4-5 minutes, with limited sample handling (dissolution of carbonates and/or combustion of organic carbon in evacuated containers). Rapid analysis allows over-preparation of samples to include replicates at each depth and/or comparison of different sample types at particular depths in a sediment or peat core. Analysis priority is given to depths that have the least chronologic precision as determined by Bayesian modeling of the chronology of calibrated ages. Use of such a statistical approach to determine the order in which samples are run ensures that the chronology constantly improves so long as material is available for the analysis of chronologic weak points. Ultimately, accuracy of the chronology is determined by the material that is actually being dated, and our combined approach allows testing of different constituents of the organic carbon pool and the carbonate minerals within a core. We will present preliminary results from a deep-sea sediment core abundant in deep-sea foraminifera as well as coastal wetland peat cores to demonstrate statistical improvements in sediment- and peat-core chronologies obtained by increasing the quantity and decreasing the quality of individual dates.

Measurement of the carbon 14 activity at natural level in air samples

International Nuclear Information System (INIS)

Olivier, A.; Tenailleau, L.; Baron, Y.; Maro, D.

2004-01-01

The aim of the study was to measure the carbon 14 activity at natural level in air samples using classical methods of radiochemistry and beta counting. Three different methods have been tested in order to minimise the detection limit. In the three methods, the first step consists in trapping the atmospheric carbon 14 into NaOH (1N) using a bubbling chamber. The atmospheric carbon dioxide reacts with NaOH to form Na 2 CO 3 . In the first method the Na 2 CO 3 solution is mixed with a liquid scintillate and is directly analysed by liquid scintillation counting (LSC). The detection limit is approximately 1 Bq/m 3 of air samples. The second method consists in evaporating the carbonate solution and then counting the solid residue with a proportional gas circulation counter. The detection limit obtained is lower than the first method (0.4 Bq/m 3 of air samples). In the third method, Na 2 CO 3 is precipitated into CaCO 3 in presence of CaCl 2 . CaCO 3 is then analysed by LSC. This method appear to be the most appropriate, the detection limit is 0.05 Bq/m 3 of air samples. (author)

Distribution of organic carbon and petroleum source rock potential of Cretaceous and lower Tertiary carbonates, South Florida Basin: preliminary results

Science.gov (United States)

Palacas, James George

1978-01-01

Analyses of 134 core samples from the South Florida Basin show that the carbonates of Comanchean age are relatively richer in average organic carbon (0.41 percent) than those of Coahuilan age (0.28 percent), Gulfian age (0.18 percent) and Paleocene age (0.20 percent). They are also nearly twice as rich as the average world, wide carbonate (average 0.24 percent). The majority of carbonates have organic carbons less than 0.30 percent but the presence of many relatively organic rich beds composed of highly bituminous, argillaceous, highly stylolitic, and algal-bearing limestones and dolomites accounts for the higher percentage of organic carbon in some of the stratigraphic units. Carbonate rocks that contain greater than 0.4 percent organic carbon and that might be considered as possible petroleum sources were noted in almost each subdivision of the Coahuilan and Comanchean Series but particularly the units of Fredericksburg 'B', Trinity 'A', Trinity 'F', and Upper Sunniland. Possible source rocks have been ascribed by others to the Lower Sunniland, but lack of sufficient samples precluded any firm assessment in this initial report. In the shallower section of the basin, organic-rich carbonates containing as much as 3.2 percent organic carbon were observed in the lowermost part of the Gulfian Series and carbonate rocks with oil staining or 'dead' and 'live oil' were noted by others in the uppermost Gulfian and upper Cedar Keys Formation. It is questionable whether these shallower rocks are of sufficient thermal maturity to have generated commercial oil. The South Florida basin is still sparsely drilled and produces only from the Sunniland Limestone at an average depth of 11,500 feet (3500 m). Because the Sunniland contains good reservoir rocks and apparently adequate source rocks, and because the success rate of new oil field discoveries has increased in recent years, the chances of finding additional oil reserves in the Sunniland are promising. Furthermore, the

Acceleration of 14C beams in electrostatic accelerators

International Nuclear Information System (INIS)

Rowton, L.J.; Tesmer, J.R.

1981-01-01

Operational problems in the production and acceleration of 14 C beams for nuclear structure research in Los Alamos National Laboratory's Van de Graaff accelerators are discussed. Methods for the control of contamination in ion sources, accelerators and personnel are described. Sputter source target fabrication techniques and the relative beam production efficiencies of various types of bound particulate carbon sputter source targets are presented

Tracing the sources of organic carbon in freshwater systems

Science.gov (United States)

Glendell, Miriam; Meersmans, Jeroen; Barclay, Rachel; Yvon-Durocher, Gabriel; Barker, Sam; Jones, Richard; Hartley, Iain; Dungait, Jennifer; Quine, Timothy

2016-04-01

Quantifying the lateral fluxes of carbon from land to inland waters is critical for the understanding of the global carbon cycle and climate change mitigation. However, the crucial role of rivers in receiving, transporting and processing the equivalent of terrestrial net primary production in their watersheds has only recently been recognised. In addition, the fluxes of carbon from land to ocean, and the impact of anthropogenic perturbation, are poorly quantified. Therefore, a mechanistic understanding of the processes involved in the loss and preservation of C along the terrestrial-aquatic continuum is required to predict the present and future contribution of aquatic C fluxes to the global C budget. This pilot study examines the effect of land use on the fate of organic matter within two headwater catchments in Cornwall (UK) in order to develop a methodological framework for investigating C-cycling across the entire terrestrial-aquatic continuum. To this end, we aim to characterise the spatial heterogeneity of soil erosion driven lateral fluxes of SOC to identify areas of erosion and deposition using 137Cs radio-isotope and trace the terrestrial versus aquatic origin of C along the river reaches and in lake sediments at the catchment outlet. The 3D spatial distribution of SOC has been investigated by sampling three depth increments (i.e. 0-15cm, 15-30cm and 30-50cm) along 14 hillslope transects within two sub-catchments of ˜km2 each. In total, 80 terrestrial sites were monitored and analysed for total C and N, and bulk stable 13C/15N isotope values, while 137Cs was used to obtain a detailed understanding of the spatial - temporal variability in erosion driven lateral fluxes of SOC within the catchments. The relative contribution of terrestrial and aquatic C was examined along the river reaches as well as in lake sediments at the catchment outlet by considering n-alkane signatures. By linking the C accumulation rates in lake sediments over decadal timescales from

A mobile light source for carbon/nitrogen cameras

International Nuclear Information System (INIS)

Trower, W.P.; Melekhin, V.N.; Shvedunov, V.I.; Sobenin, N.P.

1995-01-01

The pulsed light source for carbon/nitrogen cameras developed to image concealed narcotics/explosives is described. This race-track microtron will produce 40 mA pulses of 70 MeV electrons, have minimal size and weight, and maximal ruggedness and reliability, so that it can be transported on a truck. (orig.)

A mobile light source for carbon/nitrogen cameras

Science.gov (United States)

Trower, W. P.; Karev, A. I.; Melekhin, V. N.; Shvedunov, V. I.; Sobenin, N. P.

1995-05-01

The pulsed light source for carbon/nitrogen cameras developed to image concealed narcotics/explosives is described. This race-track microtron will produce 40 mA pulses of 70 MeV electrons, have minimal size and weight, and maximal ruggedness and reliability, so that it can be transported on a truck.

Photosynthesis and assimilate partitioning characteristics of the coconut palm as observed by carbon-14 labelling

International Nuclear Information System (INIS)

Jayasekara, K.S.; Jayaswkara, K.S.; Bowen, G.D.

2000-01-01

A technique was developed on the use of carbon dioxide(carbon-14 labelled) rapid labelling of foliage and to ascertain photosynthesis and partitioning characteristics of labelled assimilate into other parts of the coconut palm. An eight-year-old Tall x Tall young coconut palm growing under field conditions at Bandirippuwa Estate and with six developing bunches , was selected for this study. The labelling was carried out on a bright sunny day and soil was at field capacity. Seventh leaf from the youngest open leaf was used for labelling with 5 mCi of sodium bi carbonate (Carbon-14 labelled). The results revealed that within 24 hours, 60% of the labelled assimilate was partitioned into other parts of the palm and at the end of the seventh day about 18% of the labelled assimilate still remained in the labelled leaf. Among the developing bunches fifth and sixth bunches from the youngest developing bunch received more labelled assimilate than young developing bunches above them. It was revealed that partitioning of assimilate into various ''sinks'' is determined by the developmental stage or activeness of the ''sink''. The proportion of C-14 labelled carbon assimilate, partitioned into developing bunches was substantially low compared to the total amount of labelled carbon fixed by the labelled leaf. Further, it was observed that partitioning of assimilated labelled carbon into the young leaves above, as well as the mature leaves below the labelled leaf. The complex vascular anatomy of the palms could be attributed to this pattern of partitioning of assimilates into upper and lower leaves from the labelled leaf

Hazardous constituent source term. Revision 2

International Nuclear Information System (INIS)

1994-01-01

The Department of Energy (DOE) has several facilities that either generate and/or store transuranic (TRU)-waste from weapons program research and production. Much of this waste also contains hazardous waste constituents as regulated under Subtitle C of the Resource Conservation and Recovery Act (RCRA). Toxicity characteristic metals in the waste principally include lead, occurring in leaded rubber gloves and shielding. Other RCRA metals may occur as contaminants in pyrochemical salt, soil, debris, and sludge and solidified liquids, as well as in equipment resulting from decontamination and decommissioning activities. Volatile organic compounds (VOCS) contaminate many waste forms as a residue adsorbed on surfaces or occur in sludge and solidified liquids. Due to the presence of these hazardous constituents, applicable disposal regulations include land disposal restrictions established by Hazardous and Solid Waste Amendments (HSWA). The DOE plans to dispose of TRU-mixed waste from the weapons program in the Waste Isolation Pilot Plant (WIPP) by demonstrating no-migration of hazardous constituents. This paper documents the current technical basis for methodologies proposed to develop a post-closure RCRA hazardous constituent source term. For the purposes of demonstrating no-migration, the hazardous constituent source term is defined as the quantities of hazardous constituents that are available for transport after repository closure. Development of the source term is only one of several activities that will be involved in the no-migration demonstration. The demonstration will also include uncertainty and sensitivity analyses of contaminant transport

Real time source term and dose assessment

International Nuclear Information System (INIS)

Breznik, B.; Kovac, A.; Mlakar, P.

2001-01-01

The Dose Projection Programme is a tool for decision making in case of nuclear emergency. The essential input data for quick emergency evaluation in the case of hypothetical pressurised water reactor accident are following: source term, core damage assessment, fission product radioactivity, release source term and critical exposure pathways for an early phase of the release. A reduced number of radio-nuclides and simplified calculations can be used in dose calculation algorithm. Simple expert system personal computer programme has been developed for the Krsko Nuclear Power Plant for dose projection within the radius of few kilometers from the pressurised water reactor in early phase of an accident. The input data are instantaneous data of core activity, core damage indicators, release fractions, reduction factor of the release pathways, spray operation, release timing, and dispersion coefficient. Main dose projection steps are: accurate in-core radioactivity determination using reactor power input; core damage and in-containment source term assessment based on quick indications of instrumentation or on activity analysis data; user defines release pathway for typical PWR accident scenarius; dose calculation is performed only for exposure pathway critical for decision about evacuation or sheltering in early phase of an accident.(author)

Stable carbon (12/13C) and nitrogen (14/15N) isotopes as a tool for identifying the sources of cyanide in wastes and contaminated soils-A method development

International Nuclear Information System (INIS)

Weihmann, Jenny; Mansfeldt, Tim; Schulte, Ulrike

2007-01-01

The occurrence of iron-cyanide complexes in the environment is of concern, since they are potentially hazardous. In order to determine the source of iron-cyanide complexes in contaminated soils and wastes, we developed a method based on the stable isotope ratios 13 C/ 12 C and 15 N/ 14 N of the complexed cyanide-ion (CN - ). The method was tested on three pure chemicals and two industrials wastes: blast-furnace sludge (BFS) and gas-purifier waste (GPW). The iron-cyanide complexes were converted into the solid cupric ferrocyanide, Cu 2 [Fe(China) 6 ].7H 2 O, followed by combustion and determination of the isotope-ratios by continuous flow isotope ratio mass spectrometry. Cupric ferrocyanide was obtained from the materials by (i) an alkaline extraction with 1 M NaOH and (ii) a distillate digestion. The [Fe(China) 6 ] 4- of the alkaline extraction was precipitated after adding Cu 2+ . The CN - of the distillate digestion was at first complexed with Fe 2+ under inert conditions and then precipitated after adding Cu 2+ . The δ 13 C-values obtained by the two methods differed slightly up to 1-3 per mille for standards and BFS. The difference was larger for alkaline-extracted GPW (4-7 per mille ), since non-cyanide C was co-extracted and co-precipitated. Therefore the distillate digestion technique is recommended when determining the C isotope ratios in samples rich in organic carbon. Since the δ 13 C-values of BFS are in the range of -30 to -24 per mille and of -17 to -5 per mille for GPW, carbon seems to be a suitable tracer for identifying the source of cyanide in both wastes. However, the δ 15 N-values overlapped for BFS and GPW, making nitrogen unsuitable as a tracer

A perspective on tritium versus carbon-14: ensuring optimal label selection in pharmaceutical research and development.

Science.gov (United States)

Krauser, Joel A

2013-01-01

Tritium ((3) H) and carbon-14 ((14) C) labels applied in pharmaceutical research and development each offer their own distinctive advantages and disadvantages coupled with benefits and risks. The advantages of (3) H have a higher specific activity, shorter half-life that allows more manageable waste remediation, lower material costs, and often more direct synthetic routes. The advantages of (14) C offer certain analytical benefits and less potential for label loss. Although (3) H labels offer several advantages, they might be overlooked as a viable option because of the concerns about its drawbacks. A main drawback often challenged is metabolic liability. These drawbacks, in some cases, might be overstated leading to underutilization of a perfectly viable option. As a consequence, label selection may automatically default to (14) C, which is a more conservative approach. To challenge this '(14) C-by-default' approach, pharmaceutical agents with strategically selected (3) H-labeling positions based on non-labeled metabolism data have been successfully implemented and evaluated for (3) H loss. From in-house results, the long term success of projects clearly would benefit from a thorough, objective, and balanced assessment regarding label selection ((3) H or (14) C). This assessment should be based on available project information and scientific knowledge. Important considerations are project applicability (preclinical and clinical phases), synthetic feasibility, costs, and timelines. Copyright © 2013 John Wiley & Sons, Ltd.

Coal chemistry. 8. Reactions of tetralin with coal and with some carbon-14-containing model compounds

International Nuclear Information System (INIS)

Collins, C.J.; Raaen, V.F.; Benjamin, B.M.; Maupin, P.H.; Roark, W.H.

1979-01-01

When coal was treated with tetralin-l- 14 C at 400 0 C, small yields of α- and β-methylnaphthalenes- 14 C were observed. In order to determine the mechanism of the reaction, tetralin was heated with 14 C-labeled 1,3-diphenylpropanes (1), with 1,3-diphenylpropene (2), and with 14 C-labeled phenetoles (3). In each case methylnaphthalenes were observed, and the origins of the methyl groups were determined with carbon-14. In addition to the methylnaphthalenes, 1 and 2 also yielded toluene and ethylbenzene (after 19 h), whereas phenetole-β- 14 C (3-β- 14 C) yielded toluene (unlabeled) plus ethyl- 14 C-benzene, benzene, phenol, and a mixture of α- and β-ethyl- 14 C-naphthalenes. Crossover experiments with labeled phenetole and unlabeled ethyl p-tolyl ether proved the intramolecularity of the reaction phenetole → toluene + ethylbenzene, thus illustrating a 1,2-phenyl shift from oxygen to carbon

Spatial distribution of carbon sources and sinks in Canada's forests

International Nuclear Information System (INIS)

Chen, Jing M.; Weimin, Ju; Liu, Jane; Cihlar, Josef; Chen, Wenjun

2003-01-01

Annual spatial distributions of carbon sources and sinks in Canada's forests at 1 km resolution are computed for the period from 1901 to 1998 using ecosystem models that integrate remote sensing images, gridded climate, soils and forest inventory data. GIS-based fire scar maps for most regions of Canada are used to develop a remote sensing algorithm for mapping and dating forest burned areas in the 25 yr prior to 1998. These mapped and dated burned areas are used in combination with inventory data to produce a complete image of forest stand age in 1998. Empirical NPP age relationships were used to simulate the annual variations of forest growth and carbon balance in 1 km pixels, each treated as a homogeneous forest stand. Annual CO 2 flux data from four sites were used for model validation. Averaged over the period 1990-1998, the carbon source and sink map for Canada's forests show the following features: (i) large spatial variations corresponding to the patchiness of recent fire scars and productive forests and (ii) a general south-to-north gradient of decreasing carbon sink strength and increasing source strength. This gradient results mostly from differential effects of temperature increase on growing season length, nutrient mineralization and heterotrophic respiration at different latitudes as well as from uneven nitrogen deposition. The results from the present study are compared with those of two previous studies. The comparison suggests that the overall positive effects of non-disturbance factors (climate, CO 2 and nitrogen) outweighed the effects of increased disturbances in the last two decades, making Canada's forests a carbon sink in the 1980s and 1990s. Comparisons of the modeled results with tower-based eddy covariance measurements of net ecosystem exchange at four forest stands indicate that the sink values from the present study may be underestimated

Application of the source term code package to obtain a specific source term for the Laguna Verde Nuclear Power Plant

International Nuclear Information System (INIS)

Souto, F.J.

1991-06-01

The main objective of the project was to use the Source Term Code Package (STCP) to obtain a specific source term for those accident sequences deemed dominant as a result of probabilistic safety analyses (PSA) for the Laguna Verde Nuclear Power Plant (CNLV). The following programme has been carried out to meet this objective: (a) implementation of the STCP, (b) acquisition of specific data for CNLV to execute the STCP, and (c) calculations of specific source terms for accident sequences at CNLV. The STCP has been implemented and validated on CDC 170/815 and CDC 180/860 main frames as well as on a Micro VAX 3800 system. In order to get a plant-specific source term, data on the CNLV including initial core inventory, burn-up, primary containment structures, and materials used for the calculations have been obtained. Because STCP does not explicitly model containment failure, dry well failure in the form of a catastrophic rupture has been assumed. One of the most significant sequences from the point of view of possible off-site risk is the loss of off-site power with failure of the diesel generators and simultaneous loss of high pressure core spray and reactor core isolation cooling systems. The probability for that event is approximately 4.5 x 10 -6 . This sequence has been analysed in detail and the release fractions of radioisotope groups are given in the full report. 18 refs, 4 figs, 3 tabs

Evidence for the assimilation of ancient glacier organic carbon in a proglacial stream food web

Science.gov (United States)

Fellman, Jason; Hood, Eran; Raymond, Peter A.; Hudson, J.H.; Bozeman, Maura; Arimitsu, Mayumi L.

2015-01-01

We used natural abundance δ13C, δ15N, and Δ14C to compare trophic linkages between potential carbon sources (leaf litter, epilithic biofilm, and particulate organic matter) and consumers (aquatic macroinvertebrates and fish) in a nonglacial stream and two reaches of the heavily glaciated Herbert River. We tested the hypothesis that proglacial stream food webs are sustained by organic carbon released from glacial ecosystems. Carbon sources and consumers in the nonglacial stream had carbon isotope values that ranged from -30‰ to -25‰ for δ13C and from -14‰ to 53‰ for Δ14C reflecting a food web sustained mainly on contemporary primary production. In contrast, biofilm in the two glacial stream sites was highly Δ14C-depleted (-215‰ to 175‰) relative to the nonglacial stream consistent with the assimilation of ancient glacier organic carbon. IsoSource modeling showed that in upper Herbert River, macroinvertebrates (Δ14C = -171‰ to 22‰) and juvenile salmonids (Δ14C = −102‰ to 17‰) reflected a feeding history of both biofilm (~ 56%) and leaf litter (~ 40%). We estimate that in upper Herbert River on average 36% of the carbon incorporated into consumer biomass is derived from the glacier ecosystem. Thus, 14C-depleted glacial organic carbon was likely transferred to higher trophic levels through a feeding history of bacterial uptake of dissolved organic carbon and subsequent consumption of 14C-depleted biofilm by invertebrates and ultimately fish. Our findings show that the metazoan food web is sustained in part by glacial organic carbon such that future changes in glacial runoff could influence the stability and trophic structure of proglacial aquatic ecosystems.

Source Term Model for Fine Particle Resuspension from Indoor Surfaces

National Research Council Canada - National Science Library

Kim, Yoojeong; Gidwani, Ashok; Sippola, Mark; Sohn, Chang W

2008-01-01

This Phase I effort developed a source term model for particle resuspension from indoor surfaces to be used as a source term boundary condition for CFD simulation of particle transport and dispersion in a building...

Biogenic Carbon Fraction of Biogas and Natural Gas Fuel Mixtures Determined with 14C

NARCIS (Netherlands)

Palstra, Sanne W. L.; Meijer, Harro A. J.

2014-01-01

This study investigates the accuracy of the radiocarbon-based calculation of the biogenic carbon fraction for different biogas and biofossil gas mixtures. The focus is on the uncertainty in the C-14 reference values for 100% biogenic carbon and on the C-13-based isotope fractionation correction of

The Effect of Carbon Source and Fluoride Concentrations in the "Streptococcus Mutans" Biofilm Formation

Science.gov (United States)

Paulino, Tony P.; Andrade, Ricardo O.; Bruschi-Thedei, Giuliana C. M.; Thedei, Geraldo, Jr.; Ciancaglini, Pietro

2004-01-01

The main objective of this class experiment is to show the influence of carbon source and of different fluoride concentrations on the biofilm formation by the bacterium "Streptococcus mutans." The observation of different biofilm morphology as a function of carbon source and fluoride concentration allows an interesting discussion regarding the…

Scoping Analysis of Source Term and Functional Containment Attenuation Factors

Energy Technology Data Exchange (ETDEWEB)

Pete Lowry

2012-10-01

In order to meet future regulatory requirements, the Next Generation Nuclear Plant (NGNP) Project must fully establish and validate the mechanistic modular high temperature gas-cooled reactor (HTGR) source term. This is not possible at this stage in the project, as significant uncertainties in the final design remain unresolved. In the interim, however, there is a need to establish an approximate characterization of the source term. The NGNP team developed a simplified parametric model to establish mechanistic source term estimates for a set of proposed HTGR configurations.

Scoping Analysis of Source Term and Functional Containment Attenuation Factors

Energy Technology Data Exchange (ETDEWEB)

Pete Lowry

2012-02-01

In order to meet future regulatory requirements, the Next Generation Nuclear Plant (NGNP) Project must fully establish and validate the mechanistic modular high temperature gas-cooled reactor (HTGR) source term. This is not possible at this stage in the project, as significant uncertainties in the final design remain unresolved. In the interim, however, there is a need to establish an approximate characterization of the source term. The NGNP team developed a simplified parametric model to establish mechanistic source term estimates for a set of proposed HTGR configurations.