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Sample records for carbon regimes results

  1. Changes in soil carbon and enzyme activity as a result of different long-term fertilization regimes in a greenhouse field.

    PubMed

    Zhang, Lili; Chen, Wei; Burger, Martin; Yang, Lijie; Gong, Ping; Wu, Zhijie

    2015-01-01

    In order to discover the advantages and disadvantages of different fertilization regimes and identify the best management practice of fertilization in greenhouse fields, soil enzyme activities involved in carbon (C) transformations, soil chemical characteristics, and crop yields were monitored after long-term (20-year) fertilization regimes, including no fertilizer (CK), 300 kg N ha-1 and 600 kg N ha-1 as urea (N1 and N2), 75 Mg ha-1 horse manure compost (M), and M with either 300 or 600 kg N ha-1 urea (MN1 and MN2). Compared with CK, fertilization increased crop yields by 31% (N2) to 69% (MN1). However, compared with CK, inorganic fertilization (especially N2) also caused soil acidification and salinization. In the N2 treatment, soil total organic carbon (TOC) decreased from 14.1±0.27 g kg-1 at the beginning of the long-term experiment in 1988 to 12.6±0.11 g kg-1 (P<0.05). Compared to CK, N1 and N2 exhibited higher soil α-galactosidase and β-galactosidase activities, but lower soil α-glucosidase and β-glucosidase activities (P<0.05), indicating that inorganic fertilization had different impacts on these C transformation enzymes. Compared with CK, the M, MN1 and MN2 treatments exhibited higher enzyme activities, soil TOC, total nitrogen, dissolved organic C, and microbial biomass C and N. The fertilization regime of the MN1 treatment was identified as optimal because it produced the highest yields and increased soil quality, ensuring sustainability. The results suggest that inorganic fertilizer alone, especially in high amounts, in greenhouse fields is detrimental to soil quality. PMID:25706998

  2. Changes in Soil Carbon and Enzyme Activity As a Result of Different Long-Term Fertilization Regimes in a Greenhouse Field

    PubMed Central

    Zhang, Lili; Chen, Wei; Burger, Martin; Yang, Lijie; Gong, Ping; Wu, Zhijie

    2015-01-01

    In order to discover the advantages and disadvantages of different fertilization regimes and identify the best management practice of fertilization in greenhouse fields, soil enzyme activities involved in carbon (C) transformations, soil chemical characteristics, and crop yields were monitored after long-term (20-year) fertilization regimes, including no fertilizer (CK), 300 kg N ha-1 and 600 kg N ha-1 as urea (N1 and N2), 75 Mg ha-1 horse manure compost (M), and M with either 300 or 600 kg N ha-1 urea (MN1 and MN2). Compared with CK, fertilization increased crop yields by 31% (N2) to 69% (MN1). However, compared with CK, inorganic fertilization (especially N2) also caused soil acidification and salinization. In the N2 treatment, soil total organic carbon (TOC) decreased from 14.1±0.27 g kg-1 at the beginning of the long-term experiment in 1988 to 12.6±0.11 g kg-1 (P<0.05). Compared to CK, N1 and N2 exhibited higher soil α-galactosidase and β-galactosidase activities, but lower soil α-glucosidase and β-glucosidase activities (P<0.05), indicating that inorganic fertilization had different impacts on these C transformation enzymes. Compared with CK, the M, MN1 and MN2 treatments exhibited higher enzyme activities, soil TOC, total nitrogen, dissolved organic C, and microbial biomass C and N. The fertilization regime of the MN1 treatment was identified as optimal because it produced the highest yields and increased soil quality, ensuring sustainability. The results suggest that inorganic fertilizer alone, especially in high amounts, in greenhouse fields is detrimental to soil quality. PMID:25706998

  3. Conduction regime in innovative carbon nanotube via interconnect architectures

    NASA Astrophysics Data System (ADS)

    Coiffic, J. C.; Fayolle, M.; Maitrejean, S.; Foa Torres, L. E. F.; Le Poche, H.

    2007-12-01

    We report on the electrical properties of multiwall carbon nanotube based via interconnects over a broad range of temperature and bias voltage. By using innovating processing techniques, high density nanotube vias have been fabricated from single damascene and double damascene via architectures with diameters down to 140nm. For single damascene structures, resistances as low as 20Ω have been achieved for 300nm via size. Further measurements show that the conductance increases with temperature following an exponential law, which can be interpreted in terms of a disordered quasi-one dimensional conduction regime.

  4. A Universal Model for Nanoporous Carbon Supercapacitors Applicable to Diverse Pore Regimes, Carbons, and Electrolyte

    SciTech Connect

    Sumpter, Bobby G; Huang, Jingsong; Meunier, Vincent

    2008-01-01

    Supercapacitors, commonly called electric double-layer capacitors (EDLCs), are emerging as a novel type of energy storage device with the potential to substitute batteries in applications requiring high power densities. In response to the latest experimental breakthrough in nanoporous carbon supercapacitors, we propose a heuristic theoretical model that takes pore curvature into account as a replacement for the EDLC model which is based on a traditional parallel-plate capacitor. When the pore size is in the mesopore regime (2-50 nm), counterions enter mesoporous carbons and approach the pore wall to form an electric double-cylinder capacitor (EDCC); in the micropore regime (< 2 nm), solvated/desolvated counterions line up along the pore axis to form an electric wire-in-cylinder capacitor (EWCC). In the macropore regime (> 50 nm) where pores are large enough so that the pore curvature is no longer significant, the EDCC model can be reduced naturally to the EDLC model. We present density functional theory calculations and detailed analyses of available experimental data in various pore regimes, showing the significant effects of pore curvature on the supercapacitor properties of nanoporous carbons. It is shown that the EDCC/EWCC model is universal to carbon supercapacitors with diverse carbon materials including activated carbons, template carbons, and novel carbide-derived carbons, and with diverse electrolytes including organic electrolytes such as tetraethylammonium tetrafluoroborate (TEABF4), tetraethylammonium methyl-sulfonate (TEAMS) in acetonitrile, aqueous H2SO4 and KOH electrolytes, and even ionic liquid electrolyte such as 1-ethyl-3-methylimmidazolium bis(trifluromethane-sulfonyl)imide (EMI-TFSI). The EDCC/EWCC model allows the supercapacitor properties to be correlated with pore size, specific surface area, Debye length, electrolyte concentration and dielectric constant, and solute ion size, and may lend a support for the systematic optimization of the

  5. High nitrate to phosphorus regime attenuates negative effects of rising pCO2 on total population carbon accumulation

    NASA Astrophysics Data System (ADS)

    Matthiessen, B.; Eggers, S. L.; Krug, S. A.

    2012-03-01

    The ongoing rise in atmospheric pCO2 and consequent increase in ocean acidification have direct effects on marine calcifying phytoplankton, which potentially alters carbon export. To date it remains unclear, firstly, how nutrient regime, in particular by coccolithophores preferred phosphate limitation, interacts with pCO2 on particulate carbon accumulation; secondly, how direct physiological responses on the cellular level translate into total population response. In this study, cultures of Emiliania huxleyi were full-factorially exposed to two different N:P regimes and three different pCO2 levels. Cellular biovolume and PIC and POC content significantly declined in response to pCO2 in both nutrient regimes. Cellular PON content significantly increased in the Redfield treatment and decreased in the high N:P regime. Cell abundance significantly declined in the Redfield and remained constant in the high N:P regime. We hypothesise that in the high N:P regime severe phosphorous limitation could be compensated either by reduced inorganic phosphorous demand and/or by enzymatic uptake of organic phosphorous. In the Redfield regime we suggest that enzymatic phosphorous uptake to supplement enhanced phosphorous demand with pCO2 was not possible and thus cell abundance declined. These hypothesised different physiological responses of E. huxleyi among the nutrient regimes significantly altered population carrying capacities along the pCO2 gradient. This ultimately led to the attenuated total population response in POC and PIC content and biovolume to increased pCO2 in the high N:P regime. Our results point to the fact that the physiological (i.e. cellular) PIC and POC response to ocean acidification cannot be linearly extrapolated to total population response and thus carbon export. It is therefore necessary to consider both effects of nutrient limitation on cell physiology and their consequences for population size when predicting the influence of coccolithophores on

  6. Ecosystem carbon storage capacity as affected by disturbance regimes: A general theoretical model

    NASA Astrophysics Data System (ADS)

    Weng, Ensheng; Luo, Yiqi; Wang, Weile; Wang, Han; Hayes, Daniel J.; McGuire, A. David; Hastings, Alan; Schimel, David S.

    2012-09-01

    Disturbances have been recognized as a key factor shaping terrestrial ecosystem states and dynamics. A general model that quantitatively describes the relationship between carbon storage and disturbance regime is critical for better understanding large scale terrestrial ecosystem carbon dynamics. We developed a model (REGIME) to quantify ecosystem carbon storage capacities (E[x]) under varying disturbance regimes with an analytical solution E[x] = U · τE · ?, where U is ecosystem carbon influx, τE is ecosystem carbon residence time, and τ1 is the residence time of the carbon pool affected by disturbances (biomass pool in this study). The disturbance regime is characterized by the mean disturbance interval (λ) and the mean disturbance severity (s). It is a Michaelis-Menten-type equation illustrating the saturation of carbon content with mean disturbance interval. This model analytically integrates the deterministic ecosystem carbon processes with stochastic disturbance events to reveal a general pattern of terrestrial carbon dynamics at large scales. The model allows us to get a sense of the sensitivity of ecosystems to future environmental changes just by a few calculations. According to the REGIME model, for example, approximately 1.8 Pg C will be lost in the high-latitude regions of North America (>45°N) if fire disturbance intensity increases around 5.7 time the current intensity to the end of the twenty-first century, which will require around 12% increases in net primary productivity (NPP) to maintain stable carbon stocks. If the residence time decreased 10% at the same time additional 12.5% increases in NPP are required to keep current C stocks. The REGIME model also lays the foundation for analytically modeling the interactions between deterministic biogeochemical processes and stochastic disturbance events.

  7. Ecosystem carbon storage capacity as affected by disturbance regimes: a general theoretical model

    NASA Astrophysics Data System (ADS)

    Weng, E.; Luo, Y.; Wang, W.; Wang, H.; Hayes, D. J.; McGuire, A. D.; Hastings, A.; Schimel, D.

    2012-12-01

    Disturbances have been recognized as a key factor shaping terrestrial ecosystem states and dynamics. A general model that quantitatively describes the relationship between carbon storage and disturbance regime is critical for better understanding large scale terrestrial ecosystem carbon dynamics. We developed a model (REGIME) to quantify ecosystem carbon storage capacities (E[x]) under varying disturbance regimes with an analytical solution E[x]=UτE λ/(λ+sτ1) , where U is ecosystem carbon influx, τE is ecosystem carbon residence time, and τ1 is the residence time of the carbon pool affected by disturbances (biomass pool in this study). The disturbance regime is characterized by the mean disturbance interval (λ) and the mean disturbance severity (s). It is a Michaelis-Menten type equation illustrating the saturation of carbon content with mean disturbance interval. This model analytically integrates the deterministic ecosystem carbon processes with stochastic disturbance events to reveal a general pattern of terrestrial carbon dynamics at large scales. The model allows us to get a sense of the sensitivity of ecosystems to future environmental changes just by a few calculations. According to the REGIME model , for example, approximately 1.8 Pg C will be lost in the high latitude regions of North America (>45°N) if fire disturbance intensity increases around 5.7 time the current intensity to the end of 21st century, which will require around 12% increases in NPP to maintain stable carbon stocks. If the residence time decreased 10% at the same time additional 12.5% increases in NPP are required to keep current C stocks. The REGIME model also lays the foundation for analytically modeling the interactions between deterministic biogeochemical processes and stochastic disturbance events.

  8. Ecosystem carbon storage capacity as affected by disturbance regimes: A general theoretical model

    SciTech Connect

    Weng, Ensheng; Luo, Yiqi; Wang, Weile; Wang, Han; Hayes, Daniel J; McGuire, A. David; Hastings, Alan; Schimel, David

    2012-01-01

    Disturbances have been recognized as a key factor shaping terrestrial ecosystem states and dynamics. A general model that quantitatively describes the relationship between carbon storage and disturbance regime is critical for better understanding large scale terrestrial ecosystem carbon dynamics. We developed a model (REGIME) to quantify ecosystem carbon storage capacities (E[x]) under varying disturbance regimes with an analytical solution E[x] = U {center_dot} {tau}{sub E} {center_dot} {lambda}{lambda} + s {tau} 1, where U is ecosystem carbon influx, {tau}{sub E} is ecosystem carbon residence time, and {tau}{sub 1} is the residence time of the carbon pool affected by disturbances (biomass pool in this study). The disturbance regime is characterized by the mean disturbance interval ({lambda}) and the mean disturbance severity (s). It is a Michaelis-Menten-type equation illustrating the saturation of carbon content with mean disturbance interval. This model analytically integrates the deterministic ecosystem carbon processes with stochastic disturbance events to reveal a general pattern of terrestrial carbon dynamics at large scales. The model allows us to get a sense of the sensitivity of ecosystems to future environmental changes just by a few calculations. According to the REGIME model, for example, approximately 1.8 Pg C will be lost in the high-latitude regions of North America (>45{sup o} N) if fire disturbance intensity increases around 5.7 time the current intensity to the end of the twenty-first century, which will require around 12% increases in net primary productivity (NPP) to maintain stable carbon stocks. If the residence time decreased 10% at the same time additional 12.5% increases in NPP are required to keep current C stocks. The REGIME model also lays the foundation for analytically modeling the interactions between deterministic biogeochemical processes and stochastic disturbance events.

  9. Tundra carbon balance under varying temperature and moisture regimes

    NASA Astrophysics Data System (ADS)

    Huemmrich, K. F.; Kinoshita, G.; Gamon, J. A.; Houston, S.; Kwon, H.; Oechel, W. C.

    2010-12-01

    To understand the effects of environmental change on tundra carbon balance, a manipulation experiment was performed in wet sedge tundra near Barrow, Alaska. Three replicates of six environmental treatments were made: control, heating, raising or lowering water table, and heating along with raising or lowering water table. Carbon fluxes were measured using a portable chamber for six days during the 2001 growing season. Spectral reflectance and meteorological measurements were also collected. Empirical models derived from flux measurements were developed for daily gross ecosystem production (GEP) and ecosystem respiration (Re). The amount of photosynthetically active radiation absorbed by the plants was strongly correlated with GEP. This relationship was not affected by treatment or time during the growing season. Re was related to soil temperature with a different relationship for each water level treatment. Re in the lowered water table treatment had a strong response to temperature changes, while the raised water table treatment showed little temperature response. These models calculated daily net ecosystem exchange for all of the treatments over the growing season. Warming increased both the seasonal carbon gain and carbon loss. By the end of summer the lowered water table treatments, both heated and unheated, were net carbon sources while all other treatments were sinks. Warming and/or raising the water table increased the strength of the net sink. Over the timescale of this experiment, water table primarily determined whether the ecosystem was a source or sink, with temperature modifying the strength of the source or sink.

  10. Regime Shifts in Lakes: Organic Carbon Dynamics and Whole Ecosystem Responses

    NASA Astrophysics Data System (ADS)

    Anderson, N. J.

    2015-12-01

    The concept of using sediment records to identify regime shifts in lakes has largely focussed on biological proxies, such as diatoms and chironomids. In this approach, long-term records of rapid ecological change are compared with independent proxies of the variables driving ecosystem change, for example, climate or catchment disturbance processes (hydrological budgets, deforestation, fire etc.). One of the main problems with this approach is that the sediment cores upon which the data analyses are made are taken from the central part of lakes, often at the deepest point. As a result, the ecological changes observed reflect pelagic (open water) processes rather than whole-lake responses. As most lakes (apart from hypertrophic systems) are dominated by benthic production it is unclear whether palaeolimnological assessments of regime shifts are representative of the whole lake response. Theoretically, this question can be addressed simply by using cores from shallow water. There are a number of problems with this approach, most notably the loss of temporal resolution in shallow water cores (due to the slower sediment accumulation rate) and the different biological assemblages in the shallow water (littoral) cores. There is a strong effect of water depth on the zonation and distribution of biological remains across any lake. An alternative approach therefore is to use total organic carbon [OC] accumulation rate as a measure of the whole lake response to see if there is, in fact, a regime shift at the whole lake scale. Here I present examples of Holocene OC accumulation rate responses to external forcing from shallow eutrophic and boreal lakes and compare them to biological records of structural ecological change to determine whether there has been a whole-lake regime shift.

  11. Thermal effects on mass detection sensitivity of carbon nanotube resonators in nonlinear oscillation regime

    NASA Astrophysics Data System (ADS)

    Kang, Dong-Keun; Yang, Hyun-Ik; Kim, Chang-Wan

    2015-11-01

    A mass sensor using a nano-resonator has high detection sensitivity, and mass sensitivity is higher with smaller resonators. Therefore, carbon nanotubes (CNTs) are the ultimate materials for these applications and have been actively studied. In particular, CNT-based nanomechanical devices may experience high temperatures that lead to thermal expansion and residual stress in devices, which affects the device reliability. In this letter, to demonstrate the influence of the temperature change (i.e., thermal effect) on the mass detection sensitivity of CNT-based mass sensor, dynamic analysis is carried out for a CNT resonator with thermal effects in both linear and nonlinear oscillation regimes. Based on the continuum mechanics model, the analytical solution method with an assumed deflection eigenmode is applied to solve the nonlinear differential equation which involves the von Karman nonlinear strain-displacement relation and the additional axial force associated with thermal effects. A thermal effect on the fundamental resonance behavior and resonance frequency shift due to adsorbed mas, i.e., mass detection sensitivity, is examined in high-temperature environment. Results indicate a valid improvement of fundamental resonance frequency by using nonlinear oscillation in a thermal environment. In both linear and nonlinear oscillation regimes, the mass detection sensitivity becomes worse due to the increasing of temperature in a high-temperature environment. The thermal effect on the detection sensitivity is less effective in the nonlinear oscillation regime. It is concluded that a temperature change of a mass sensor with a CNT-based resonator can be utilized to enhance the detection sensitivity depending on the CNT length, linear/nonlinear oscillation behaviors, and the thermal environment.

  12. Carbon rhizodeposition by plants of contrasting strategies for resource acquisition: responses to various nitrogen fertility regimes

    NASA Astrophysics Data System (ADS)

    Baptist, Florence; Aranjuelo, I.; Lopez-Sangil, L.; Rovia, P.; Nogués, S.

    2010-05-01

    Rhizodeposition by plants is one of the most important physiological mechanisms related to carbon and nitrogen cycling which is also believed to vary along the acquisition-conservation continuum. However, owing to methodological difficulties (i.e. narrow zone of soil around roots and rapid assimilation by soil microbes), root exudation and variations between species are one of the most poorly understood belowground process. Although previous approaches such as hydroponic culture based system, permit the chemical analysis of exudates, the fact that this protocol is qualitative, conditions its utility (see review in Phillips et al. 2008). Others techniques based on pulse-labelling approach have been developed to quantify rhizodeposition but are rarely sufficient to uniformly label all plant inputs to soil. Consequently with this typical pulse chase methods, recent assimilates are labeled but the recalcitrant carbon will not be labeled and therefore the contribution of this carbon will not be considered. Hence, traditional pulse labelling is not a quantitative means of tracing carbon due to inhomogeneous labelling and so limits greatly comparative studies of rhizodeposition fluxes at the interspecific level. In this study we developped a new protocole based on a long-term (3 months) steady state 13C labelling in order (1) to quantify rhizodeposition fluxes for six graminoid species caracterized by contrasted nutrient acquisition strategies and (2) to investigate to what extent various level of nitrogen fertility regimes modulate rhizodeposition fluxes. This method will enable to quantify under natural soil conditions both the accumulation of 13C in the soil but also the quantity that has been respired by the microorganisms during a given time and so will give an integrated picture of rhizodeposition fluxes for each species under each nitrogen fertility level. Results are currently being processed and will be presented at the conference. References: Phillips RP, Erlitz

  13. Effects of Successive Rotation Regimes on Carbon Stocks in Eucalyptus Plantations in Subtropical China Measured over a Full Rotation

    PubMed Central

    Li, Xiaoqiong; Ye, Duo; Liang, Hongwen; Zhu, Hongguang; Qin, Lin; Zhu, Yuling; Wen, Yuanguang

    2015-01-01

    Plantations play an important role in carbon sequestration and the global carbon cycle. However, there is a dilemma in that most plantations are managed on short rotations, and the carbon sequestration capacities of these short-rotation plantations remain understudied. Eucalyptus has been widely planted in the tropics and subtropics due to its rapid growth, high adaptability, and large economic return. Eucalyptus plantations are primarily planted in successive rotations with a short rotation length of 6~8 years. In order to estimate the carbon-stock potential of eucalyptus plantations over successive rotations, we chose a first rotation (FR) and a second rotation (SR) stand and monitored the carbon stock dynamics over a full rotation from 1998 to 2005. Our results showed that carbon stock in eucalyptus trees (TC) did not significantly differ between rotations, while understory vegetation (UC) and soil organic matter (SOC) stored less carbon in the SR (1.01 vs. 2.76 Mg.ha-1 and 70.68 vs. 81.08 Mg. ha-1, respectively) and forest floor carbon (FFC) conversely stored more (2.80 vs. 2.34 Mg. ha-1). The lower UC and SOC stocks in the SR stand resulted in 1.13 times lower overall ecosystem carbon stock. Mineral soils and overstory trees were the two dominant carbon pools in eucalyptus plantations, accounting for 73.77%~75.06% and 20.50%~22.39%, respectively, of the ecosystem carbon pool. However, the relative contribution (to the ecosystem pool) of FFC stocks increased 1.38 times and that of UC decreased 2.30 times in the SR versus FR stand. These carbon pool changes over successive rotations were attributed to intensive successive rotation regimes of eucalyptus plantations. Our eight year study suggests that for the sustainable development of short-rotation plantations, a sound silvicultural strategy is required to achieve the best combination of high wood yield and carbon stock potential. PMID:26186367

  14. Effects of Successive Rotation Regimes on Carbon Stocks in Eucalyptus Plantations in Subtropical China Measured over a Full Rotation.

    PubMed

    Li, Xiaoqiong; Ye, Duo; Liang, Hongwen; Zhu, Hongguang; Qin, Lin; Zhu, Yuling; Wen, Yuanguang

    2015-01-01

    Plantations play an important role in carbon sequestration and the global carbon cycle. However, there is a dilemma in that most plantations are managed on short rotations, and the carbon sequestration capacities of these short-rotation plantations remain understudied. Eucalyptus has been widely planted in the tropics and subtropics due to its rapid growth, high adaptability, and large economic return. Eucalyptus plantations are primarily planted in successive rotations with a short rotation length of 6~8 years. In order to estimate the carbon-stock potential of eucalyptus plantations over successive rotations, we chose a first rotation (FR) and a second rotation (SR) stand and monitored the carbon stock dynamics over a full rotation from 1998 to 2005. Our results showed that carbon stock in eucalyptus trees (TC) did not significantly differ between rotations, while understory vegetation (UC) and soil organic matter (SOC) stored less carbon in the SR (1.01 vs. 2.76 Mg.ha(-1) and 70.68 vs. 81.08 Mg. ha(-1), respectively) and forest floor carbon (FFC) conversely stored more (2.80 vs. 2.34 Mg. ha(-1)). The lower UC and SOC stocks in the SR stand resulted in 1.13 times lower overall ecosystem carbon stock. Mineral soils and overstory trees were the two dominant carbon pools in eucalyptus plantations, accounting for 73.77%~75.06% and 20.50%~22.39%, respectively, of the ecosystem carbon pool. However, the relative contribution (to the ecosystem pool) of FFC stocks increased 1.38 times and that of UC decreased 2.30 times in the SR versus FR stand. These carbon pool changes over successive rotations were attributed to intensive successive rotation regimes of eucalyptus plantations. Our eight year study suggests that for the sustainable development of short-rotation plantations, a sound silvicultural strategy is required to achieve the best combination of high wood yield and carbon stock potential. PMID:26186367

  15. Salix response to different flow regimes in controlled experiments: first results

    NASA Astrophysics Data System (ADS)

    Gorla, Lorenzo; Signarbieux, Constant; Buttler, Alexandre; Perona, Paolo

    2013-04-01

    Dams and water management for hydropower production, agriculture and other human activities alter the natural flow regime of rivers. The new river hydrograph components depend on the type of impoundment and the policy of regulation but such a different flow regime will likely affect the riparian environment. The main challenge in order to define sustainable flow releases is to quantify hydrological effects in terms of geomorphology and ecosystem response. A considerable lack of knowledge still affects the link hydrology-ecology and inadequate flow rules (e.g., minimal or residual flows) are consequently still widespread: further research in this direction is urgently required. We present an experiment, which aims to investigate the effects of different water stage regimes on riparian vegetation (salix Viminalis cuttings) development in a temperate region (Switzerland). This work describes the installation setup, together with the first results concerning the first of the two scheduled seasons of campaign. Sixty Salix cuttings were planted in non-cohesive sandy-gravel sediment within 1 meter tall plastic pots installed outside in the EPFL campus. After grouping them in three batteries, the water level within them has been varying following three river regimes simulated by adjusting the water level within the pots by means of an automatic hydraulic system. The three water level regimes reproduce a natural flow regime, a minimum residual flow policy, which only conserves peaks during flooding conditions, and an artificial regime conserving only low frequencies (e.g., seasonality) of the natural dynamic. The natural flow regime of the first battery has been applied for two months to the entire system; the three regimes above said started in June 2012. This triggered a plant response transitory regime, which we monitored by measuring plant growth, soil and atmospheric variables. Particularly, measures concern with branches development leaves photosynthesis and

  16. Dynamic regime marginal structural mean models for estimation of optimal dynamic treatment regimes, Part II: proofs of results.

    PubMed

    Orellana, Liliana; Rotnitzky, Andrea; Robins, James M

    2010-01-01

    In this companion article to "Dynamic Regime Marginal Structural Mean Models for Estimation of Optimal Dynamic Treatment Regimes, Part I: Main Content" [Orellana, Rotnitzky and Robins (2010), IJB, Vol. 6, Iss. 2, Art. 7] we present (i) proofs of the claims in that paper, (ii) a proposal for the computation of a confidence set for the optimal index when this lies in a finite set, and (iii) an example to aid the interpretation of the positivity assumption. PMID:20405047

  17. Laser-driven 1 GeV carbon ions from preheated diamond targets in the break-out afterburner regime

    NASA Astrophysics Data System (ADS)

    Jung, D.; Yin, L.; Gautier, D. C.; Wu, H.-C.; Letzring, S.; Dromey, B.; Shah, R.; Palaniyappan, S.; Shimada, T.; Johnson, R. P.; Schreiber, J.; Habs, D.; Fernández, J. C.; Hegelich, B. M.; Albright, B. J.

    2013-08-01

    Experimental data are presented for laser-driven carbon C6+ ion-acceleration, verifying 2D-PIC studies for multi-species targets in the Break-Out Afterburner regime. With Trident's ultra-high contrast at relativistic intensities of 5 × 1020 W/cm2 and nm-scale diamond targets, acceleration of carbon ions has been optimized by using target laser-preheating for removal of surface proton contaminants. Using a high-resolution wide angle spectrometer, carbon C6+ ion energies exceeding 1 GeV or 83 MeV/amu have been measured, which is a 40% increase in maximum ion energy over uncleaned targets. These results are consistent with kinetic plasma modeling and analytic theory.

  18. The characteristics of water-carbon regime of Banzhai karst subterranean stream system covered by virgin forest with soil deficiency

    NASA Astrophysics Data System (ADS)

    Zeng, C.; Liu, Z.

    2012-04-01

    Three hydrological years' automatic monitoring (from January, 2007 to June, 2010) was made in the discharge area of karst subterranean stream system covered by virgin forest with soil deficiency by use of hydro-chemical auto-recordable instrument to investigate the characteristics of water-carbon regime of discharge from this subterranean stream system. The methods of water balance calculation, karst water discharge recession analysis and stable isotope and hydrochemistry were used. The results show that: first, the evapotranspiration of virgin forest is unexpectedly high, indicated by low infiltration coefficient and low subterranean river runoff generation; second, under the conditions of deficiency of soil cover, even the virgin forest has only moderate ability of regulation and control of hydrological (Q) and hydrochemical (e.g., bicarbonate concentration) processes, so that the karstification intensity and the relevant carbon sink capacity keep low. These characteristics reflect that soil cover plays important roles in the regulation and control of water resources and carbon cycle.

  19. Laser-driven 1 GeV carbon ions from preheated diamond targets in the break-out afterburner regime

    SciTech Connect

    Jung, D.; Department für Physik, Ludwig-Maximilians-Universität München, D-85748 Garching; Max-Planck-Institut für Quantenoptik, D-85748 Garching ; Yin, L.; Gautier, D. C.; Wu, H.-C.; Letzring, S.; Shah, R.; Palaniyappan, S.; Shimada, T.; Johnson, R. P.; Fernández, J. C.; Hegelich, B. M.; Albright, B. J.; Dromey, B.; Schreiber, J.; Habs, D.; Max-Planck-Institut für Quantenoptik, D-85748 Garching

    2013-08-15

    Experimental data are presented for laser-driven carbon C{sup 6+} ion-acceleration, verifying 2D-PIC studies for multi-species targets in the Break-Out Afterburner regime. With Trident's ultra-high contrast at relativistic intensities of 5 × 10{sup 20} W/cm{sup 2} and nm-scale diamond targets, acceleration of carbon ions has been optimized by using target laser-preheating for removal of surface proton contaminants. Using a high-resolution wide angle spectrometer, carbon C{sup 6+} ion energies exceeding 1 GeV or 83 MeV/amu have been measured, which is a 40% increase in maximum ion energy over uncleaned targets. These results are consistent with kinetic plasma modeling and analytic theory.

  20. Vadose Zone Flow and Transport of Dissolved Organic Carbon at Multiple Scales in Humid Regimes

    SciTech Connect

    Jardine, Philip M; Mayes, Melanie; Mulholland, Patrick J; Hanson, Paul J; Phillips, Jana Randolph; Luxmoore, Robert J; McCarthy, John F

    2006-06-01

    Scientists must embrace the necessity to offset global CO{sub 2} emissions regardless of politics. Efforts to enhance terrestrial organic carbon sequestration have traditionally focused on aboveground biomass and surface soils. An unexplored potential exists in thick lower horizons of widespread, mature soils such as Alfisols, Ultisols, and Oxisols. We present a case study of fate and transport of dissolved organic carbon (DOC) in a highly weathered Ultisol, involving spatial scales from the laboratory to the landscape. Our objectives were to interpret processes observed at various scales and provide an improved understanding of coupled hydrogeochemical mechanisms that control DOC mobility and sequestration in deep subsoils within humid climatic regimes. Our approach is multiscale, using laboratory-scale batch and soil columns (0.2 by 1.0 m), an in situ pedon (2 by 2 by 3 m), a well-instrumented subsurface facility on a subwatershed (0.47 ha), and ephemeral and perennial stream discharge at the landscape scale (38.4 ha). Laboratory-scale experiments confirmed that lower horizons have the propensity to accumulate DOC, but that preferential fracture flow tends to limit sequestration. Intermediate-scale experiments demonstrated the beneficial effects of C diffusion into soil micropores. Field- and landscape-scale studies demonstrated coupled hydrological, geochemical, and microbiological mechanisms that limit DOC sequestration, and their sensitivity to local environmental conditions. Our results suggest a multi-scale approach is necessary to assess the propensity of deep subsoils to sequester organic C in situ. By unraveling fundamental organic C sequestration mechanisms, we improve the conceptual and quantitative understanding needed to predict and alter organic C budgets in soil systems.

  1. Molecular systems under shock compression into the dense plasma regime: carbon dioxide and hydrocarbon polymers

    NASA Astrophysics Data System (ADS)

    Mattsson, Thomas R.; Cochrane, Kyle R.; Root, Seth; Carpenter, John H.

    2013-10-01

    Density Functional Theory (DFT) has proven remarkably accurate in predicting properties of matter under shock compression into the dense plasma regime. Materials where chemistry plays a role are of interest for many applications, including planetary science and inertial confinement fusion (ICF). As examples of systems where chemical reactions are important, and demonstration of the high fidelity possible for these both structurally and chemically complex systems, we will discuss shock- and re-shock of liquid carbon dioxide (CO2) in the range 100 to 800 GPa and shock compression of hydrocarbon polymers, including GDP (glow discharge polymer) which is used as an ablator in laser ICF experiments. Experimental results from Sandia's Z machine validate the DFT simulations at extreme conditions and the combination of experiment and DFT provide reliable data for evaluating existing and constructing future wide-range equations of state models for molecular compounds. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  2. Improved biological phosphorus removal performance driven by the aerobic/extended-idle regime with propionate as the sole carbon source.

    PubMed

    Wang, Dongbo; Li, Xiaoming; Yang, Qi; Zheng, Wei; Wu, Yan; Zeng, Tianjing; Zeng, Guangming

    2012-08-01

    Our previous studies proved that biological phosphorus removal (BPR) could be achieved in an aerobic/extended-idle (AEI) process employing two typical substrates of glucose and acetate as the carbon sources. This paper further evaluated the feasibility of another important substrate, propionate, serving as the carbon source for BPR in the AEI process, and compared the BPR performance between the AEI and anaerobic/oxic (A/O) processes. Two sequencing batch reactors (SBRs) were operated, respectively, as the AEI and A/O regimes for BPR using propionate as the sole substrate. The results showed that the AEI-reactor removed 2.98 ± 0.04-4.06 ± 0.06 mg of phosphorus per g of total suspended solids during the course of the steady operational trial, and the phosphorus content of the dried sludge was reached 8.0 ± 0.4% after 56-day operation, demonstrating the good performance of phosphorus removal. Then, the efficiencies of BPR and the transformations of the intracellular storages were compared between two SBRs. It was observed that the phosphorus removal efficiency was maintained around 95% in the AEI-reactor, and about 83% in the A/O-reactor, although the latter showed much greater transformations of both polyhydroxyalkanoates and glycogen. The facts clearly showed that BPR could be enhanced by the AEI regime using propionate as the carbon source. Finally, the mechanisms for the propionate fed AEI-reactor improving BPR were investigated. It was found that the sludge cultured by the AEI regime had more polyphosphate containing cells than that by the A/O regime. Further investigation revealed that the residual nitrate generated in the last aerobic period was readily deteriorated BPR in the A/O-SBR, but a slight deterioration was observed in the AEI-SBR. Moreover, the lower glycogen transformation measured in the AEI-SBR indicated that the biomass cultured by the AEI regime contained less glycogen accumulating organisms activities than that by the A/O regime. PMID

  3. Classifying organic materials by oxygen-to-carbon elemental ratio to predict the activation regime of Cloud Condensation Nuclei (CCN)

    NASA Astrophysics Data System (ADS)

    Kuwata, M.; Shao, W.; Lebouteiller, R.; Martin, S. T.

    2013-05-01

    The governing highly soluble, slightly soluble, or insoluble activation regime of organic compounds as cloud condensation nuclei (CCN) was examined as a function of oxygen-to-carbon elemental ratio (O : C). New data were collected for adipic, pimelic, suberic, azelaic, and pinonic acids. Secondary organic materials (SOMs) produced by α-pinene ozonolysis and isoprene photo-oxidation were also included in the analysis. The saturation concentrations C of the organic compounds in aqueous solutions served as the key parameter for delineating regimes of CCN activation, and the values of C were tightly correlated to the O : C ratios. The highly soluble, slightly soluble, and insoluble regimes of CCN activation were found to correspond to ranges of [O : C] > 0.6, 0.2 < [O : C] < 0.6, and [O : C] < 0.2, respectively. These classifications were evaluated against CCN activation data of isoprene-derived SOM (O : C = 0.69-0.72) and α-pinene-derived SOM (O : C = 0.38-0.48). Isoprene-derived SOM had highly soluble activation behavior, consistent with its high O : C ratio. For α-pinene-derived SOM, although CCN activation can be modeled as a highly soluble mechanism, this behavior was not predicted by the O : C ratio, for which a slightly soluble mechanism was anticipated. Complexity in chemical composition, resulting in continuous water uptake and the absence of a deliquescence transition that can thermodynamically limit CCN activation, might explain the difference in the behavior of α-pinene-derived SOM compared to that of pure organic compounds. The present results suggest that atmospheric particles dominated by hydrocarbon-like organic components do not activate (i.e., insoluble regime) whereas those dominated by oxygenated organic components activate (i.e., highly soluble regime) for typical atmospheric cloud life cycles.

  4. Classifying organic materials by oxygen-to-carbon elemental ratio to predict the activation regime of cloud condensation nuclei (CCN)

    NASA Astrophysics Data System (ADS)

    Kuwata, M.; Shao, W.; Lebouteiller, R.; Martin, S. T.

    2012-12-01

    The governing highly soluble, slightly soluble, or insoluble activation regime of organic compounds as cloud condensation nuclei (CCN) was examined as a function of oxygen-to-carbon elemental ratio (O : C). New data were collected for adipic, pimelic, suberic, azelaic and pinonic acids. Secondary organic materials (SOMs) produced by α-pinene ozonolysis and isoprene photo-oxidation were also included in the analysis. The saturation concentrations C of the organic compounds in aqueous solutions served as the key parameter for delineating regimes of CCN activation, and the values of C were tightly correlated to the O : C ratios. The highly soluble, slightly soluble, and insoluble regimes of CCN activation were found to correspond to ranges of [O : C] > 0.6, 0.2 < [O : C] < 0.6, and [O : C] < 0.2, respectively. These classifications were evaluated against CCN activation data of isoprene-derived SOM (O : C = 0.69-0.72) and α-pinene-derived SOM (O : C = 0.38-0.48). Isoprene-derived SOM had highly soluble activation behavior, consistent with its high O : C ratio. For α-pinene-derived SOM, although CCN activation can be modeled as a highly soluble mechanism, this behavior was not predicted by the O : C ratio, for which a slightly soluble mechanism was anticipated. Complexity in chemical composition, resulting in continuous water uptake and the absence of a deliquescence transition that can thermodynamically limit CCN activation, might explain the differences of α-pinene-derived SOM compared to the behavior of pure organic compounds. The present results suggest that atmospheric particles dominated by hydrocarbon-like organic components do not activate (i.e. insoluble regime) whereas those dominated by oxygenated organic components activate (i.e. highly soluble regime).

  5. Adapting fire management to future fire regimes: impacts on boreal forest composition and carbon balance in Canadian National Parks

    NASA Astrophysics Data System (ADS)

    de Groot, W. J.; Flannigan, M. D.; Cantin, A.

    2009-04-01

    The effects of future fire regimes altered by climate change, and fire management in adaptation to climate change were studied in the boreal forest region of western Canada. Present (1975-90) and future (2080-2100) fire regimes were simulated for several National Parks using data from the Canadian (CGCM1) and Hadley (HadCM3) Global Climate Models (GCM) in separate simulation scenarios. The long-term effects of the different fire regimes on forests were simulated using a stand-level, boreal fire effects model (BORFIRE). Changes in forest composition and biomass storage due to future altered fire regimes were determined by comparing current and future simulation results. This was used to assess the ecological impact of altered fire regimes on boreal forests, and the future role of these forests as carbon sinks or sources. Additional future simulations were run using adapted fire management strategies, including increased fire suppression and the use of prescribed fire to meet fire cycle objectives. Future forest composition, carbon storage and emissions under current and adapted fire management strategies were also compared to determine the impact of various future fire management options. Both of the GCM's showed more severe burning conditions under future fire regimes. This includes fires with higher intensity, greater depth of burn, greater total fuel consumption and shorter fire cycles (or higher rates of annual area burned). The Canadian GCM indicated burning conditions more severe than the Hadley GCM. Shorter fire cycles of future fire regimes generally favoured aspen, birch, and jack pine because it provided more frequent regeneration opportunity for these pioneer species. Black spruce was only minimally influenced by future fire regimes, although white spruce declined sharply. Maintaining representation of pure and mixed white spruce ecosystems in natural areas will be a concern under future fire regimes. Active fire suppression is required in these areas. In

  6. Importance of soil thermal regime in terrestrial ecosystem carbon dynamics in the circumpolar north

    NASA Astrophysics Data System (ADS)

    Jiang, Yueyang; Zhuang, Qianlai; Sitch, Stephen; O'Donnell, Jonathan A.; Kicklighter, David; Sokolov, Andrei; Melillo, Jerry

    2016-07-01

    In the circumpolar north (45-90°N), permafrost plays an important role in vegetation and carbon (C) dynamics. Permafrost thawing has been accelerated by the warming climate and exerts a positive feedback to climate through increasing soil C release to the atmosphere. To evaluate the influence of permafrost on C dynamics, changes in soil temperature profiles should be considered in global C models. This study incorporates a sophisticated soil thermal model (STM) into a dynamic global vegetation model (LPJ-DGVM) to improve simulations of changes in soil temperature profiles from the ground surface to 3 m depth, and its impacts on C pools and fluxes during the 20th and 21st centuries. With cooler simulated soil temperatures during the summer, LPJ-STM estimates ~ 0.4 Pg C yr- 1 lower present-day heterotrophic respiration but ~ 0.5 Pg C yr- 1 higher net primary production than the original LPJ model resulting in an additional 0.8 to 1.0 Pg C yr- 1 being sequestered in circumpolar ecosystems. Under a suite of projected warming scenarios, we show that the increasing active layer thickness results in the mobilization of permafrost C, which contributes to a more rapid increase in heterotrophic respiration in LPJ-STM compared to the stand-alone LPJ model. Except under the extreme warming conditions, increases in plant production due to warming and rising CO2, overwhelm the e nhanced ecosystem respiration so that both boreal forest and arctic tundra ecosystems remain a net C sink over the 21st century. This study highlights the importance of considering changes in the soil thermal regime when quantifying the C budget in the circumpolar north.

  7. Response of vegetation to carbon dioxide - effect of elevated levels of CO{sub 2} on winter wheat under two moisture regimes

    SciTech Connect

    Chaudhuri, U.N.; Burnett, R.B.; Kanemasu, E.T.; Kirkham, M.B.

    1987-12-31

    This report deals with the second-year (1985-86) findings of an on going experiment with winter wheat (Triticum aestivum L.) at different carbon dioxide (CO{sub 2}) levels and under two moisture regimes. The results for the first year are given in the U.S. Department of Energy, Carbon Dioxide Research Division Response of Vegetation to Carbon Dioxide. The purpose of the second year`s experiment was to verify the results of 1984-85. However, based on the performance and the results of 1984-85 experiments, a few modifications were made.

  8. First-Order 0-π Quantum Phase Transition in the Kondo Regime of a Superconducting Carbon-Nanotube Quantum Dot

    NASA Astrophysics Data System (ADS)

    Maurand, Romain; Meng, Tobias; Bonet, Edgar; Florens, Serge; Marty, Laëtitia; Wernsdorfer, Wolfgang

    2012-01-01

    We study a carbon-nanotube quantum dot embedded in a superconducting-quantum-interference-device loop in order to investigate the competition of strong electron correlations with a proximity effect. Depending on whether local pairing or local magnetism prevails, a superconducting quantum dot will exhibit a positive or a negative supercurrent, referred to as a 0 or π Josephson junction, respectively. In the regime of a strong Coulomb blockade, the 0-to-π transition is typically controlled by a change in the discrete charge state of the dot, from even to odd. In contrast, at a larger tunneling amplitude, the Kondo effect develops for an odd-charge (magnetic) dot in the normal state, and quenches magnetism. In this situation, we find that a first-order 0-to-π quantum phase transition can be triggered at a fixed valence when superconductivity is brought in, due to the competition of the superconducting gap and the Kondo temperature. The superconducting-quantum-interference-device geometry together with the tunability of our device allows the exploration of the associated phase diagram predicted by recent theories. We also report on the observation of anharmonic behavior of the current-phase relation in the transition regime, which we associate with the two accessible superconducting states. Our results finally demonstrate that the spin-singlet nature of the Kondo state helps to enhance the stability of the 0 phase far from the mixed-valence regime in odd-charge superconducting quantum dots.

  9. Carbon production on accreting neutron stars in a new regime of stable nuclear burning

    NASA Astrophysics Data System (ADS)

    Keek, L.; Heger, A.

    2016-02-01

    Accreting neutron stars exhibit Type I X-ray bursts from both frequent hydrogen/helium flashes as well as rare carbon flashes. The latter (superbursts) ignite in the ashes of the former. Hydrogen/helium bursts, however, are thought to produce insufficient carbon to power superbursts. Stable burning could create the required carbon, but this was predicted to only occur at much larger accretion rates than where superbursts are observed. We present models of a new steady-state regime of stable hydrogen and helium burning that produces pure carbon ashes. Hot CNO burning of hydrogen heats the neutron star envelope and causes helium to burn before the conditions of a helium flash are reached. This takes place when the mass accretion rate is around 10 per cent of the Eddington limit: close to the rate where most superbursts occur. We find that increased heating at the base of the envelope sustains steady-state burning by steepening the temperature profile, which increases the amount of helium that burns before a runaway can ensue.

  10. The influence of climate cycles on the water regime and carbonate profile in chernozems of Central European Russia and adjacent territories

    NASA Astrophysics Data System (ADS)

    Bazykina, G. S.; Ovechkin, S. V.

    2016-04-01

    The influence of long-term "dry" and "wet" climatic cycles on the water regime, hydrological parameters, and carbonate profiles of chernozems in Central European Russia and adjacent territories was studied. The hydrological and carbonate profiles were found to change during the wet cycle. However, the upper part of the hydrological profile is basically unchanging, whereas in its lower part, the number of hydrological horizons and contrast in their moistening decrease in the forest-steppe chernozems and increase in the steppe chernozems. The frequency of through wetting of chernozems increases during the wet cycles. The vertical lithological heterogeneity of the parent material affects the soil moisture status. In the wet climatic cycle, the moisture content above the lithological contact increases resulting in the development of the features of soil hydromorphism. In the carbonate profile, the character of pedofeatures is changing: some carbonate neoformations disappear, while the other ones develop. Possible variations of the periodically percolative water regime were revealed in chernozems. The classification of water regime proposed by A.A. Rode may be updated based on the data obtained during the dry climatic cycle. Rode's hypothesis about cyclic variations in the soil water regime is confirmed.

  11. Future hydrological regimes of the upper Indus basin: results from the PAPRIKA project.

    NASA Astrophysics Data System (ADS)

    Bocchiola, Daniele; Soncini, Andrea; Confortola, Gabriele; Nana, Ester; Bianchi, Alberto; Rosso, Renzo; Diolaiuti, Guglielmina; Smiraglia, Claudio; von Hardenberg, Jost; Palazzi, Elisa; Provenzale, Antonello; Giorgi, Filippo; Solmon, Fabien; Vuillermoz, Elisa

    2013-04-01

    ) hydrological cycle in the area by feeding the hydrological model with future precipitation and temperature (plus downscaling, whenever necessary) from two climate models, one global (EC-Earth), and one regional (RegCM), the latter specifically set up for SHARE-Paprika project. The projected flow duration curves, some selected flow descriptors, and the significance of modified flow regimes in the Shigar river are then evaluated. We comment upon modified snow cover, ice ablation regime and implications for future water resources and flood regime in the area. The uncertainty of the results is addressed, and future research questions are discussed. Keywords: Upper Indus basin; hydrological models; climate models; future water resources.

  12. A Recent Shift in the Carbon Balance of High-latitude Terrestrial Ecosystems in Response to Changes in Climate and Disturbance Regime

    NASA Astrophysics Data System (ADS)

    Hayes, D. J.; McGuire, A.; Kicklighter, D. W.; Gurney, K. R.; Burnside, T. J.; Melillo, J. M.

    2008-12-01

    Analyses of the global carbon budget suggest that terrestrial ecosystems have been responsible for slowing the rate of anthropogenic CO2 build-up in the atmosphere through carbon uptake and storage, with northern extratropical regions responsible for most of this land-based CO2 sink. However, recent changes in atmospheric chemistry, climate trends, disturbance regimes, land use and management systems in northern high latitude regions have the potential to alter the terrestrial sink of atmospheric CO2. To determine the recent trends in the carbon balance of the arctic and boreal ecosystems of this region, we performed a retrospective analysis of terrestrial ecosystem dynamics across the pan-arctic (north of 45°N latitude) using a process-based biogeochemistry model. The results of the simulations suggest a shift in direction of the net flux from the terrestrial sink of earlier decades to a net source on the order of 8.5 Tg C per year between 1997 and 2006. The positive carbon balance (sink) estimated for tundra regions is consistent with observations suggesting a "greening" of, or an increase in productivity in, these ecosystems. However, the simulation framework and subsequent analyses presented in this study attribute the overall shift in regional carbon balance primarily to a large loss of carbon as a result of "browning" in boreal forest ecosystems. Model results suggest that primary productivity of the boreal forest declined over this recent time period in response to a decreasing trend in water balance. However, the substantial release of CO2 as a direct result of the large area of boreal forest burned during the past decade was the largest signal in the overall negative carbon balance for the pan-arctic region. Our results, along with those of other recent studies, emphasize the importance of changes in the disturbance regime (e.g., fire events and insect outbreaks) in the weakening and possible disappearance of the terrestrial carbon sink in high latitude

  13. Sedimentary structures formed by upper-regime flows on a Pleistocene carbonate ramp (Favignana Calcarenite, Sicily, Italy)

    NASA Astrophysics Data System (ADS)

    Slootman, Arnoud; Moscariello, Andrea; Cartigny, Matthieu; de Boer, Poppe

    2015-04-01

    flow. Using published experimental Froude numbers for breaking antidune waves, average flow thickness and sediment flux is computed. The ratio of bed volume and sediment flux provides an estimate for the duration of the sediment gravity flows. We show that applying hydraulic equations to upper-regime sedimentary structures in coarse-grained carbonate sandstones reveal that about half of the ramp deposits, that formed over ca. 350 thousand years, were deposited in not more than tens of hours. Our results provide renewed insight into the evolution of the Favignana Calcarenite and other carbonate ramp deposits.

  14. Latest Results on Pulsar Wind Nebulae on the TeV Energy Regime

    NASA Astrophysics Data System (ADS)

    de Oña Wilhelmi, E.

    2011-08-01

    The last few years have seen a revolution in very high γ-ray astronomy (VHE E>100 GeV) driven largely by a new generation of Cherenkov telescopes. These new facilities, namely H.E.S.S. (High Energy Stereoscopic System), MAGIC (Major Atmospheric Gamma Imaging Cherenkov Telescope) and its upgrade MAGIC 2, Veritas (Very Energetic Radiation Imaging Telescope Array System) and CANGAROO (Collaboration of Australia and Nippon for a Gamma Ray Observatory in the Outback) were designed to increase the flux sensitivity in the energy regime of hundreds of GeV, expanding the observed energy range from 100 (50) GeV to multi-TeV, and fostered as a result a period of rapid growth in our understanding of the Non-Thermal Universe. As a result of this fast development the number of pulsar wind nebulae (PWNe) detected has increased from a few in the early 90's to more than two dozen of firm candidates nowadays. A review of the most relevant VHE results concerning pulsars and their relativistic winds is discussed here in the context of Cherenkov telescopes.

  15. Methane Pyrolysis and Disposing Off Resulting Carbon

    NASA Technical Reports Server (NTRS)

    Sharma, P. K.; Rapp, D.; Rahotgi, N. K.

    1999-01-01

    Sabatier/Electrolysis (S/E) is a leading process for producing methane and oxygen for application to Mars ISPP. One significant problem with this process is that it produces an excess of methane for combustion with the amount of oxygen that is produced. Therefore, one must discard roughly half of the methane to obtain the proper stoichiometric methane/oxygen mixture for ascent from Mars. This is a waste of hydrogen, which must be brought from Earth and is difficult to transport to Mars and store on Mars. To reduce the problem of transporting hydrogen to Mars, the S/E process can be augmented by another process which reduces overall hydrogen requirement. Three conceptual approaches for doing this are (i) recover hydrogen from the excess methane produced by the S/E process, (ii) convert the methane to a higher hydrocarbon or other organic with a lower H/C ratio than methane, and (iii) use a separate process (such as zirconia or reverse water gas shift reaction) to produce additional oxygen, thus utilizing all the methane produced by the Sabatier process. We report our results here on recovering hydrogen from the excess methane using pyrolysis of methane. Pyrolysis has the advantage that it produces almost pure hydrogen, and any unreacted methane can pass through the S/E process reactor. It has the disadvantage that disposing of the carbon produced by pyrolysis presents difficulties. The goals of a research program on recovery of hydrogen from methane are (in descending priority order): 1) Study the kinetics of pyrolysis to arrive at a pyrolysis reactor design that produces high yields in a confined volume at the lowest possible operating temperature; 2) Study the kinetics of carbon burnoff to determine whether high yields can be obtained in a confined volume at acceptable operating temperatures; and 3) Investigate catalytic techniques for depositing carbon as a fine soot which can be physically separated from the reactor. In the JPL program, we have made significant

  16. Methane Pyrolysis and Disposing Off Resulting Carbon

    NASA Technical Reports Server (NTRS)

    Sharma, P. K.; Rapp, D.; Rahotgi, N. K.

    1999-01-01

    Sabatier/Electrolysis (S/E) is a leading process for producing methane and oxygen for application to Mars ISPP. One significant problem with this process is that it produces an excess of methane for combustion with the amount of oxygen that is produced. Therefore, one must discard roughly half of the methane to obtain the proper stoichiometric methane/oxygen mixture for ascent from Mars. This is wasteful of hydrogen, which must be brought from Earth and is difficult to transport to Mars and store on Mars. To reduced the problem of transporting hydrogen to Mars, the S/E process can be augmented by another process which reduces overall hydrogen requirement. Three conceptual approaches for doing this are (1) recover hydrogen from the excess methane produced by the S/E process, (2) convert the methane to a higher hydrocarbon or other organic with a lower H/C ratio than methane, and (3) use a separate process (such as zirconia or reverse water gas shift reaction) to produce additional oxygen, thus utilizing all the methane produced by the Sabatier process. We report our results here on recovering hydrogen from the excess methane using pyrolysis of methane. Pyrolysis has the advantage that it produces almost pure hydrogen, and any unreacted methane can pass through the S/E process reactor. It has the disadvantage that disposing of the carbon produced by pyrolysis presents difficulties. Hydrogen may be obtained from methane by pyrolysis in the temperature range 10000-12000C. The main reaction products are hydrogen and carbon, though very small amounts of higher hydrocarbons, including aromatic hydrocarbons are formed. The conversion efficiency is about 95% at 12000C. One needs to distinguish between thermodynamic equilibrium conversion and conversion limited by kinetics in a finite reactor.

  17. Compartment Syndrome Resulting from Carbon Monoxide Poisoning.

    PubMed

    Serbest, Sancar; Belhan, Oktay; Gürger, Murat; Tosun, Haci Bayram

    2015-12-01

    Every year, especially in the cooler Fall and Winter months, hundreds of people die because of carbon monoxide poisoning. This occurs usually as an accident. It is a significant cause of poisoning worldwide. We present a case of compartment syndrome in both lower extremities with accompanying acute renal failure and systemic capillary leakage syndrome because of carbon monoxide poisoning. PMID:26588033

  18. Shelf morphology as an indicator of sedimentary regimes: A synthesis from a mixed siliciclastic-carbonate shelf on the eastern Brazilian margin

    NASA Astrophysics Data System (ADS)

    Bastos, Alex C.; Quaresma, Valéria S.; Marangoni, Mariana B.; D'Agostini, Danielle P.; Bourguignon, Silvia N.; Cetto, Paulo H.; Silva, Alex E.; Amado Filho, Gilberto M.; Moura, Rodrigo L.; Collins, Michael

    2015-11-01

    Modern shelf morphology is the result of the interplay between short and long term sedimentary processes. The relation between rates of sediment supply/carbonate growth and accommodation space creation will not only control coastal transgression and regression, but will also define the shelf sedimentary regimes acting to shape the seabed. Herein, shelf morphology and sedimentology are investigated in order to discuss how these characteristics can be representative of distinct sedimentary regimes. The study area is the eastern Brazilian shelf where coastal transgression and regression coexist with the most important coral reef system of the South Atlantic. A compilation of existing published and unpublished data was carried out in order to produce morphological and faciological maps and compare the mapped features with high-resolution seismic and sonographic data. The results show three major regions or morphological compartments: Abrolhos Shelf, Doce River Shelf and the Paleovalleys Shelf. In terms of shelf sedimentary domain, rhodolith beds predominate over the outer shelf along the entire area, coralline reefs are present along the northern Abrolhos inner shelf and a significant terrigenous mud deposit is observed associated to the Doce River adjacent inner shelf beds. The rest of the shelf is composed by bioclastic or terrigenous mud sand and gravel. Terrigenous sedimentation is always restricted to the shoreface or inner shelf shallower areas and carbonate sands and gravels are predominant elsewhere. The Abrolhos shelf shows two distinct sectors; the northern area is a typical mixed sediment environment that has a supply regime along the coast/shoreface, mainly due to longshore transport and a carbonate regime along the inner and outer shelf. The southern shelf morphology and sedimentation are controlled by the antecedent topography and is typically a accommodation regime shelf with associated rhodolith beds. The Doce river shelf is a supply regime environment

  19. Chaoticity threshold in magnetized plasmas: Numerical results in the weak coupling regime

    SciTech Connect

    Carati, A. Benfenati, F.; Maiocchi, A.; Galgani, L.; Zuin, M.

    2014-03-15

    The present paper is a numerical counterpart to the theoretical work [Carati et al., Chaos 22, 033124 (2012)]. We are concerned with the transition from order to chaos in a one-component plasma (a system of point electrons with mutual Coulomb interactions, in a uniform neutralizing background), the plasma being immersed in a uniform stationary magnetic field. In the paper [Carati et al., Chaos 22, 033124 (2012)], it was predicted that a transition should take place when the electron density is increased or the field decreased in such a way that the ratio ω{sub p}/ω{sub c} between plasma and cyclotron frequencies becomes of order 1, irrespective of the value of the so-called Coulomb coupling parameter Γ. Here, we perform numerical computations for a first principles model of N point electrons in a periodic box, with mutual Coulomb interactions, using as a probe for chaoticity the time-autocorrelation function of magnetization. We consider two values of Γ (0.04 and 0.016) in the weak coupling regime Γ ≪ 1, with N up to 512. A transition is found to occur for ω{sub p}/ω{sub c} in the range between 0.25 and 2, in fairly good agreement with the theoretical prediction. These results might be of interest for the problem of the breakdown of plasma confinement in fusion machines.

  20. A Comparison of the Role of Episode Nutrient Supply on Pathways of Carbon in Upwelling Regimes

    NASA Technical Reports Server (NTRS)

    Carr, M. E.

    1997-01-01

    Nutrient supply is episode in the ocean even in regions of fairly high and continuous nutrient supply, such as coastal upwelling regimes. The structure of the ecosystem depends on nutrient availability and the different requirements of phytoplankton cells.

  1. Temperature regime and carbon dioxide enrichment alter cotton boll development and fiber properties

    SciTech Connect

    Reddy, K.R.; Davidonis, G.H.; Johnson, A.S.; Vinyard, B.T.

    1999-10-01

    Temperature and atmospheric carbon dioxide concentration [CO{sub 2}] affect cotton (Gossypium hirsutum L.) growth and development, but the interaction of these two factors on bill and fiber properties has not been studied. An experiment was conducted in naturally lit plant growth chambers to determine the influence of temperature and atmospheric [CO{sub 2}] on cotton (cv. DPL-51) boll and fiber growth parameters. Five temperature regimes were evaluated: the 1995 temperature at Mississippi State, MS; the 1995 temperature minus 2 C; and the 1995 temperature plus 2, 5, and 7 C. Daily and seasonal variation and amplitudes were maintained. Atmospheric [CO{sub 2}] treatments were 360 (ambient) and 720 {micro}L L{sup {minus}1}. Boll number, boll growth, and fiber properties were measured. Boll size and maturation periods decreased as temperature increased. Boll growth increased with temperature to 25 C and then declined at the highest temperature. Boll maturation period, size, and growth rates were not affected by atmospheric [CO{sub 2}]. The most temperature-sensitive aspect of cotton development is boll retention. Almost no bolls were retained to maturity at 1995 plus 5 or 7 C, but squares and bolls were continuously produced even at those high temperatures. Therefore, the upper limit for cotton boll survival is 32 C, or 5 C warmer than the 1995 US Mid-South ambient temperatures. The 720 {micro}L L{sup {minus}1} atmospheric [CO{sub 2}] had about 40% more squares and bolls across temperatures than the 360 {micro}L L{sup {minus}1} [CO{sub 2}]. Fibers were longer when bolls grew at less than optimal temperatures (25 C) for boll growth. As temperature increased, fiber length distributions were more uniform. Fiber fineness and maturity increased linearly with the increase in temperature up to 26 C, but decreased at 32 C. Short-fiber content declined linearly from 17 to 26 C, but was higher at higher temperature. As for boll growth and developmental parameters, elevated

  2. Semiclassical (qft) and Quantum (string) Anti-De Sitter Regimes:. New Results

    NASA Astrophysics Data System (ADS)

    Bouchareb, A.; Ramón Medrano, M.; Sánchez, N. G.

    We compute the quantum string entropy Ss(m, H) from the microscopic string density of states ρs(m, H) of mass m in Anti-de Sitter space-time. For high m, (high Hm → c/α‧), no phase transition occurs at the Anti-de Sitter string temperature Ts = (1/2πkB)Lclc2/α‧, which is higher than the flat space (Hagedorn) temperature ts. (Lcl = c/H, the Hubble constant H acts as producing a smaller string constant α‧ and thus, a higher tension). Ts is the precise quantum dual of the semiclassical (QFT) Anti-de Sitter temperature scale Tsem = ℏc/(2πkBLcl). We compute the quantum string emission σstring by a black hole in Anti-de Sitter (or asymptotically Anti-de Sitter) space-time (bhAdS). For Tsem bhAdS ≪ Ts (early evaporation stage), it shows the QFT Hawking emission with temperature Tsem bhAdS (semiclassical regime). For Tsem bhAdS → Ts, it exhibits a phase transition into a Anti-de Sitter string state of size Ls = ls2/L_ cl, (ls = √ hbar α '/c}), and Anti-de Sitter string temperature Ts. New string bounds on the black hole emerge in the bhAdS string regime. The bhAdS string regime determines a maximal value for H : Hmax = 0.841c/ls. The minimal black hole radius in Anti-de Sitter space-time turns out to be rg min = 0.841ls, and is larger than the minimal black hole radius in de Sitter space-time by a numerical factor equal to 2.304. We find a new formula for the full AdS entropy Ssem(H), as a function of the usual Bekenstein-Hawking entropy S sem(0)(H). For Lcl ≫ ℓPlanck, i.e. for low H ≪ c/ℓPlanck, or classical regime, S sem(0)(H) is the leading term with its logarithmic correction, but for high H ≥ c/ℓPlanck or quantum regime, no phase transition operates, in contrast to de Sitter space, and the entropy Ssem(H) is very different from the Bekenstein-Hawking term S sem(0)(H).

  3. Modeling the transition between upper plane bed regime and sheet flow without an active layer formulation. Preliminary results.

    NASA Astrophysics Data System (ADS)

    Viparelli, E.; Hernandez Moreira, R. R.; Blom, A.

    2015-12-01

    A perusal of the literature on bedload transport revealed that, notwithstanding the large number of studies on bedform morphology performed in the past decades, the upper plane bed regime has not been thoroughly investigated and the distinction between the upper plane bed and sheet flow transport regimes is still poorly defined. Previous experimental work demonstrated that the upper plane bed regime is characterized by long wavelength and small amplitude bedforms that migrate downstream. These bedforms, however, were not observed in experiments on sheet flow transport suggesting that the upper plane bed and the sheet flow are two different regimes. We thus designed and performed experiments in a sediment feed flume in the hydraulic laboratory of the Department of Civil and Environmental Engineering at the University of South Carolina at Columbia to study the transition from upper plane bed to sheet flow regime. Periodic measurements of water surface and bed elevation, bedform geometry and thicknesses of the bedload layer were performed by eyes, and with cameras, movies and a system of six ultrasonic probes that record the variations of bed elevation at a point over time. We used the time series of bed elevations to determine the probability functions of bed elevation. These probability functions are implemented in a continuous model of river morphodynamics, i.e. a model that does not use the active layer approximation to describe the sediment fluxes between the bedload and the deposit and that should thus be able to capture the details of the vertical and streamwise variation of the deposit grain size distribution. This model is validated against the experimental results for the case of uniform material. We then use the validated model in the attempt to study if and how the spatial distribution of grain sizes in the deposit changes from upper plane bed regime to sheet flow and if these results are influenced by the imposed rates of base level rise.

  4. An ecological regime shift resulting from disrupted predator-prey interactions in Holocene Australia.

    PubMed

    Prowse, Thomas A A; Johnson, Christopher N; Bradshaw, Corey J A; Brook, Barry W

    2014-03-01

    The mass extinction events during human prehistory are striking examples of ecological regime shifts, the causes of which are still hotly debated. In Australia, human arrival approximately 50 thousand years ago was associated with the continental-scale extinction of numerous marsupial megafauna species and a permanent change in vegetation structure. An alternative stable state persisted until a second regime shift occurred during the late Holocene, when the largest two remaining marsupial carnivores, the thylacine and devil, disappeared from mainland Australia. These extinctions have been widely attributed to the human-assisted invasion of a competing predator, the dingo. In this unusual case, the simultaneous effects of human "intensification" (population growth and technological advances) and climate change (particularly increased ENSO variability) have been largely overlooked. We developed a dynamic model system capable of simulating the complex interactions between the main predators (humans, thylacines, devils, dingoes) and their marsupial prey (macropods), which we coupled with reconstructions of human population growth and climate change for late-Holocene Australia. Because the strength of important interspecific interactions cannot be estimated directly, we used detailed scenario testing and sensitivity analysis to identify robust model outcomes and investigate competing explanations for the Holocene regime shift. This approach identified human intensification as the most probable cause, while also demonstrating the potential importance of synergies with the effects of climate change. Our models indicate that the prehistoric impact of humans on Australian mammals was not limited to the late Pleistocene (i.e., the megafaunal extinctions) but extended into the late Holocene. PMID:24804453

  5. Impact of carbon to nitrogen ratio and aeration regime on mainstream deammonification.

    PubMed

    Han, M; De Clippeleir, H; Al-Omari, A; Wett, B; Vlaeminck, S E; Bott, C; Murthy, S

    2016-01-01

    While deammonification of high-strength wastewater in the sludge line of sewage treatment plants has become well established, the potential cost savings spur the development of this technology for mainstream applications. This study aimed at identifying the effect of aeration and organic carbon on the deammonification process. Two 10 L sequencing bath reactors with different aeration frequencies were operated at 25°C. Real wastewater effluents from chemically enhanced primary treatment and high-rate activated sludge process were fed into the reactors with biodegradable chemical oxygen demand/nitrogen (bCOD/N) of 2.0 and 0.6, respectively. It was found that shorter aerobic solids retention time (SRT) and higher aeration frequency gave more advantages for aerobic ammonium-oxidizing bacteria (AerAOB) than nitrite oxidizing bacteria (NOB) in the system. From the kinetics study, it is shown that the affinity for oxygen is higher for NOB than for AerAOB, and higher dissolved oxygen set-point could decrease the affinity of both AerAOB and NOB communities. After 514 days of operation, it was concluded that lower organic carbon levels enhanced the activity of anoxic ammonium-oxidizing bacteria (AnAOB) over denitrifiers. As a result, the contribution of AnAOB to nitrogen removal increased from 40 to 70%. Overall, a reasonably good total removal efficiency of 66% was reached under a low bCOD/N ratio of 2.0 after adaptation. PMID:27438242

  6. Calcium carbonate budgets for two coral reefs affected by different terrestrial runoff regimes, Rio Bueno, Jamaica

    NASA Astrophysics Data System (ADS)

    Mallela, J.; Perry, C. T.

    2007-03-01

    A process-based carbonate budget was used to compare carbonate framework production at two reef sites subject to varying degrees of fluvial influence in Rio Bueno, Jamaica. The turbid, central embayment was subjected to high rates of fluvial sediment input, framework accretion was restricted to ≤30 m, and net carbonate production was 1,887 g CaCO3 m-2 year-1. Gross carbonate production (GCP) was dominated by scleractinians (97%), particularly by sediment-resistant species, e.g. Diploria strigosa on the reef flat (<2 m). Calcareous encrusters contributed very little carbonate. Total bioerosion removed 265 g CaCO3 m-2 year-1 and was dominated by microborers. At the clear-water site, net carbonate production was 1,236 g CaCO3 m-2 year-1; the most productive zone was on the fore-reef (10 m). Corals accounted for 82% of GCP, and encrusting organisms 16%. Bioerosion removed 126 g CaCO3 m-2 year-1 and was dominated by macroborers. Total fish and urchin grazing was limited throughout (≤20 g CaCO3 m-2 year-1). The study demonstrates that: (1) carbonate production and net reef accretion can occur where environmental conditions approach or exceed perceived threshold levels for coral survival; and (2) although live coral cover (and carbonate production rates) were reduced on reef-front sites along the North Jamaican coast, low population densities of grazing fish and echinoids to some extent offset this, thus maintaining positive carbonate budgets.

  7. Response to multi-generational selection under elevated [CO2] in two temperature regimes suggests enhanced carbon assimilation and increased reproductive output in Brassica napus L.

    PubMed Central

    Frenck, Georg; van der Linden, Leon; Mikkelsen, Teis Nørgaard; Brix, Hans; Jørgensen, Rikke Bagger

    2013-01-01

    Functional plant traits are likely to adapt under the sustained pressure imposed by environmental changes through natural selection. Employing Brassica napus as a model, a multi-generational study was performed to investigate the potential trajectories of selection at elevated [CO2] in two different temperature regimes. To reveal phenotypic divergence at the manipulated [CO2] and temperature conditions, a full-factorial natural selection regime was established in a phytotron environment over the range of four generations. It is demonstrated that a directional response to selection at elevated [CO2] led to higher quantities of reproductive output over the range of investigated generations independent of the applied temperature regime. The increase in seed yield caused an increase in aboveground biomass. This suggests quantitative changes in the functions of carbon sequestration of plants subjected to increased levels of CO2 over the generational range investigated. The results of this study suggest that phenotypic divergence of plants selected under elevated atmospheric CO2 concentration may drive the future functions of plant productivity to be different from projections that do not incorporate selection responses of plants. This study accentuates the importance of phenotypic responses across multiple generations in relation to our understanding of biogeochemical dynamics of future ecosystems. Furthermore, the positive selection response of reproductive output under increased [CO2] may ameliorate depressions in plant reproductive fitness caused by higher temperatures in situations where both factors co-occur. PMID:23762504

  8. Anthropogenic perturbation of the global carbon cycle as a result of agricultural carbon erosion and burial

    NASA Astrophysics Data System (ADS)

    Wang, Zhengang; Govers, Gerard; Kaplan, Jed; Hoffmann, Thomas; Doetterl, Sebastian; Six, Johan; Van Oost, Kristof

    2016-04-01

    Changes in terrestrial carbon storage exert a strong control over atmospheric CO2 concentrations but the underlying mechanisms are not fully constrained. Anthropogenic land cover change is considered to represent an important carbon loss mechanism, but current assessments do not consider the associated acceleration of carbon erosion and burial in sediments. We evaluated the role of anthropogenic soil erosion and the resulting carbon fluxes between land and atmosphere from the onset of agriculture to the present day. We show, here, that agricultural erosion induced a significant cumulative net uptake of 198±57 Pg carbon on terrestrial ecosystems. This erosion-induced soil carbon sink is estimated to have offset 74±21% of carbon emissions. Since 1850, erosion fluxes have increased 3-fold. As a result, the erosion and lateral transfer of organic carbon in relation to human activities is an important driver of the global carbon cycle at millennial timescales.

  9. A Numerical Study of the Effect of Periodic Nutrient Supply on Pathways of Carbon in a Coastal Upwelling Regime

    NASA Technical Reports Server (NTRS)

    Carr, Mary-Elena

    1998-01-01

    A size-based ecosystem model was modified to include periodic upwelling events and used to evaluate the effect of episodic nutrient supply on the standing stock, carbon uptake, and carbon flow into mesozooplankton grazing and sinking flux in a coastal upwelling regime. Two ecosystem configurations were compared: a single food chain made up of net phytoplankton and mesozooplankton (one autotroph and one heterotroph, A1H1), and three interconnected food chains plus bacteria (three autotrophs and four heterotrophs, A3H4). The carbon pathways in the A1H1 simulations were under stronger physical control than those of the A3H4 runs, where the small size classes are not affected by frequent upwelling events. In the more complex food web simulations, the microbial pathway determines the total carbon uptake and grazing rates, and regenerated nitrogen accounts for more than half of the total primary production for periods of 20 days or longer between events. By contrast, new production, export of carbon through sinking and mesozooplankton grazing are more important in the A1H1 simulations. In the A3H4 simulations, the turnover time scale of the autotroph biomass increases as the period between upwelling events increases, because of the larger contribution of slow-growing net phytoplankton. The upwelling period was characterized for three upwelling sites from the alongshore wind speed measured by the NASA Scatterometer (NSCAT) and the corresponding model output compared with literature data. This validation exercise for three upwelling sites and a downstream embayment suggests that standing stock, carbon uptake and size fractionation were best supported by the A3H4 simulations, while the simulated sinking fluxes are not distinguishable in the two configurations.

  10. Projected carbon stocks in the conterminous USA with land use and variable fire regimes.

    PubMed

    Bachelet, Dominique; Ferschweiler, Ken; Sheehan, Timothy J; Sleeter, Benjamin M; Zhu, Zhiliang

    2015-12-01

    The dynamic global vegetation model (DGVM) MC2 was run over the conterminous USA at 30 arc sec (~800 m) to simulate the impacts of nine climate futures generated by 3GCMs (CSIRO, MIROC and CGCM3) using 3 emission scenarios (A2, A1B and B1) in the context of the LandCarbon national carbon sequestration assessment. It first simulated potential vegetation dynamics from coast to coast assuming no human impacts and naturally occurring wildfires. A moderate effect of increased atmospheric CO2 on water use efficiency and growth enhanced carbon sequestration but did not greatly influence woody encroachment. The wildfires maintained prairie-forest ecotones in the Great Plains. With simulated fire suppression, the number and impacts of wildfires was reduced as only catastrophic fires were allowed to escape. This greatly increased the expansion of forests and woodlands across the western USA and some of the ecotones disappeared. However, when fires did occur, their impacts (both extent and biomass consumed) were very large. We also evaluated the relative influence of human land use including forest and crop harvest by running the DGVM with land use (and fire suppression) and simple land management rules. From 2041 through 2060, carbon stocks (live biomass, soil and dead biomass) of US terrestrial ecosystems varied between 155 and 162 Pg C across the three emission scenarios when potential natural vegetation was simulated. With land use, periodic harvest of croplands and timberlands as well as the prevention of woody expansion across the West reduced carbon stocks to a range of 122-126 Pg C, while effective fire suppression reduced fire emissions by about 50%. Despite the simplicity of our approach, the differences between the size of the carbon stocks confirm other reports of the importance of land use on the carbon cycle over climate change. PMID:26207729

  11. The carbonate profile and water regime of migrational-mycelial chernozems in different ecosystems of Kursk oblast

    NASA Astrophysics Data System (ADS)

    Ovechkin, S. V.; Bazykina, G. S.

    2011-12-01

    The carbonate profiles of migrational-mycelial (typical) chernozems under regularly mown and absolutely reserved steppes in the V.V. Alekhin Central Chernozemic State Biospheric Reserve and under cropland with cereals (Kursk oblast) were studied in 2007-2009. A comparison of the results of these studies with previous results obtained in the mid-1970s attests to certain changes in the carbonate profiles of the soils. They are conditioned by the activation of the migration of carbonates and the more pronounced manifestation of differently directed processes of the leaching and accumulation of carbonates. The reasons for the observed transformation of the carbonate profiles are related to the increased moistening of the upper 3-m-deep chernozemic layer in different ecosystems because of a general rise in the humidity of the local climate in the recent decades (1973-2006).

  12. Intensification of Climate-Carbon Feedbacks after 2100 and Implications for Disturbance Regimes

    NASA Astrophysics Data System (ADS)

    Randerson, J. T.; Lindsay, K. T.; Munoz, E.; Fu, W.; Hoffman, F. M.; Moore, J. K.; Doney, S. C.; Mahowald, N. M.; Bonan, G. B.

    2014-12-01

    Long-term ecosystem and carbon cycle responses to climate change are needed to inform mitigation policy, yet our understanding of how these responses may evolve after 2100 remains highly uncertain. Using the Community Earth System Model (version 1.0), we quantified climate-carbon feedbacks from 1850 to 2300 for the Representative Concentration Pathway 8.5 (and its extension). In three simulations, land and ocean biogeochemical models were exposed to the same trajectory of increasing atmospheric CO2. In one simulation, atmospheric CO2 and other forcing agents were radiatively active (fully coupled), modifying temperature and other aspects of climate. In another, CO2 was radiatively uncoupled, and in the third, both CO2 and other atmospheric forcing agents (including CH4, N2O, and aerosols) were radiatively uncoupled. In the fully coupled simulation, global mean air temperatures increased by 9.3°C from 1850 to 2300, with 4.4°C of this warming occurring after 2100. Without radiative forcing from CO2, cumulative warming was much lower at 2.4°C, but exceeding 2°C targets needed to avoid dangerous interference with the climate system. In response to climate change, ocean and land rates of carbon uptake were reduced, with the size of the impact increasing over time. In the oceans, reductions in cumulative carbon uptake from climate change increased from 3% during the 20th century to 40% during the 23rd century. By 2300, climate change had reduced cumulative ocean uptake by 330 Pg C, from 1410 Pg C to 1080 Pg C. Most of this reduction occurred after 2100 as a consequence of increases in surface stratification and decreases in Atlantic meridional overturning circulation. Land fluxes similarly diverged over time, with climate change inducing a cumulative loss of 230 Pg C by 2300. On land the intensification of the hydrological cycle globally increased terrestrial water storage, although asymmetric responses were observed across different continents in the tropics. Net

  13. Widely Tunable Single-Photon Source from a Carbon Nanotube in the Purcell Regime

    NASA Astrophysics Data System (ADS)

    Jeantet, A.; Chassagneux, Y.; Raynaud, C.; Roussignol, Ph.; Lauret, J. S.; Besga, B.; Estève, J.; Reichel, J.; Voisin, C.

    2016-06-01

    The narrow emission of a single carbon nanotube at low temperature is coupled to the optical mode of a fiber microcavity using the built-in spatial and spectral matching brought by this flexible geometry. A thorough cw and time-resolved investigation of the very same emitter both in free space and in cavity shows an efficient funneling of the emission into the cavity mode together with a strong emission enhancement corresponding to a Purcell factor of up to 5. At the same time, the emitted photons retain a strong sub-Poissonian statistics. By exploiting the cavity feeding effect on the phonon wings, we locked the emission of the nanotube at the cavity resonance frequency, which allowed us to tune the frequency over a 4 THz band while keeping an almost perfect antibunching. By choosing the nanotube diameter appropriately, this study paves the way to the development of carbon-based tunable single-photon sources in the telecom bands.

  14. The role of hydrologic regimes on dissolved organic carbon composition in an agricultural watershed

    USGS Publications Warehouse

    Hernes, P.J.; Spencer, R.G.M.; Dyda, R.Y.; Pellerin, B.A.; Bachand, P.A.M.; Bergamaschi, B.A.

    2008-01-01

    Willow Slough, a seasonally irrigated agricultural watershed in the Sacramento River valley, California, was sampled weekly in 2006 in order to investigate seasonal concentrations and compositions of dissolved organic carbon (DOC). Average DOC concentrations nearly doubled from winter baseflow (2.75 mg L-1) to summer irrigation (5.14 mg L-1), while a concomitant increase in carbon-normalized vanillyl phenols (0.11 mg 100 mg OC-1 increasing to 0.31 mg 100 mg OC-1, on average) indicates that this additional carbon is likely vascular plant-derived. A strong linear relationship between lignin concentration and total suspended sediments (r2 = 0.79) demonstrates that agricultural management practices that mobilize sediments will likely have a direct and significant impact on DOC composition. The original source of vascular plant-derived DOC to Willow Slough appears to be the same throughout the year as evidenced by similar syringyl to vanillyl and cinnamyl to vanillyl ratios. However, differing diagenetic pathways during winter baseflow as compared to the rest of the year are evident in acid to aldehyde ratios of both vanillyl and syringyl phenols. The chromophoric dissolved organic matter (CDOM) absorption coefficient at 350 nm showed a strong correlation with lignin concentration (r2 = 0.83). Other CDOM measurements related to aromaticity and molecular weight also showed correlations with carbon-normalized yields (e.g. specific UV absorbance at 254 nm (r2 = 0.57) and spectral slope (r2 = 0.54)). Our overall findings suggest that irrigated agricultural watersheds like Willow Slough can potentially have a significant impact on mainstem DOC concentration and composition when scaled to the entire watershed of the main tributary. ?? 2008 Elsevier Ltd.

  15. Variations in the fire regime in the North American boreal forest between 1990 and 2004 and their potential impacts on terrestrial carbon storage

    NASA Astrophysics Data System (ADS)

    Kasischke, E. S.; Turetsky, M. R.; McGuire, A. D.; French, N. H.

    2004-12-01

    that organic layers common in boreal forests and peatlands burn deeper and release more carbon during large fire events and during late season fires. In this paper, we will present the results of a study on how recent changes in the North American boreal fire regime have influenced carbon storage in the ground-organic layer in this region based on different assumption regarding levels of consumption of organic layer burning.

  16. Analytical results for quasiparticle excitations in the Fractional Quantum Hall Effect regime

    NASA Astrophysics Data System (ADS)

    Bentalha, Z.

    2016-07-01

    In this work, quasiparticle energies for systems with N = 3 , 4 , 5 , 6 and 7 electrons are calculated analytically in both Laughlin and composite fermions (CF) theories by considering the electron-electron interaction potential. The exact results we have obtained for the first and the second excited states agree with previous numerical results. This study shows that at this level the CF-wave function has lower energy in comparison with Laughlin wave function energy.

  17. Gunshot wounds (resulting from execution) of exhumed victims of the communist regime in Poland.

    PubMed

    Szleszkowski, Łukasz; Thannhäuser, Agata; Szwagrzyk, Krzysztof; Kawecki, Jerzy; Jurek, Tomasz

    2014-07-01

    This study presents the results of the analysis of the remains of 23 executed male individuals aged between 21 and 63 years, recovered from Osobowicki Cemetery in Wroclaw (Poland), field 83B, in 2012. In 1948 and 1949, prisoners sentenced to death by firing squad--most of them associated with the post-war anti-communist underground independence movement in Poland--were buried there. The aim of the study was to analyse fatal wounds and the method of execution, and to compare the results to data from archival documents. The results were also compared with studies concerning executions during a later period, i.e. 1949-1954. The research on the method of execution during this period of history carried out during the exhumations in Osobowicki Cemetery was the first conducted on such a scale in Poland. Forensic analysis revealed a wide variety of gunshot wounds inflicted during executions, revealing both gunshots to the head, especially single shots to the back of the head, and cases corresponding to the use of a firing squad, probably equipped with machine guns. The results of the research indicate that capital punishment by shooting was carried out in ways both similar to those the specified in the regulations and completely different. PMID:24767546

  18. A Review of Update Clinical Results of Carbon Ion Radiotherapy

    PubMed Central

    Tsujii, Hirohiko; Kamada, Tadashi

    2012-01-01

    Among various types of ion species, carbon ions are considered to have the most balanced, optimal properties in terms of possessing physically and biologically effective dose localization in the body. This is due to the fact that when compared with photon beams, carbon ion beams offer improved dose distribution, leading to the concentration of the sufficient dose within a target volume while minimizing the dose in the surrounding normal tissues. In addition, carbon ions, being heavier than protons, provide a higher biological effectiveness, which increases with depth, reaching the maximum at the end of the beam's range. This is practically an ideal property from the standpoint of cancer radiotherapy. Clinical studies have been carried out in the world to confirm the efficacy of carbon ions against a variety of tumors as well as to develop effective techniques for delivering an efficient dose to the tumor. Through clinical experiences of carbon ion radiotherapy at the National Institute of Radiological Sciences and Gesellschaft für Schwerionenforschung, a significant reduction in the overall treatment time with acceptable toxicities has been obtained in almost all types of tumors. This means that carbon ion radiotherapy has meanwhile achieved for itself a solid place in general practice. This review describes clinical results of carbon ion radiotherapy together with physical, biological and technological aspects of carbon ions. PMID:22798685

  19. Shifts in the hydrodynamic regime determine patterns of regional changes of the Arctic Ocean carbon cycle in future climate change projections

    NASA Astrophysics Data System (ADS)

    Ilyina, T.; Heinze, M.; Li, H.; Jungclaus, J. H.; Six, K. D.

    2015-12-01

    In future projections the Arctic Ocean carbon cycle is a hotspot for changes driven by rising CO2 emissions. Concomitantly, the Arctic Ocean hydrodynamic regime undergoes substantial shifts so the net effect on the carbon cycle is not intuitively clear. In the high CO2 scenario RCP8.5 extended until 2300 in projections of the Max Planck Institute's Earth System Model, the averaged Arctic Ocean surface temperature rises by 4°C in 2100 and by 10°C in 2300, respectively. The Arctic becomes free of summer sea ice in the second half of the 21st century, whereas winter sea ice disappears at the beginning of the 23rd century. Owing to increased sea ice melting and runoff, fresh water content increases gradually until the end of the 22nd century and then drops abruptly as a result of an intensification of the saline Atlantic water inflow. Accumulation of Atlantic water collapses the halocline in the central basin of the Arctic Ocean by the first half of the 23rd century. Ongoing warming enhances thermal stratification and the mixed layer shoales. In contrast, halocline erosion and the cooling of the ice free water act in concert to favor formation of convection cells in the central basin. Freshening in the Canada basin and transport of salty water into the Eurasian basin generate a dipole structure in the anomalies of surface salinity. Driven by the rising CO2, the averaged dissolved inorganic carbon (DIC) is growing. Changes in the averaged total alkalinity (TA) go along with the fresh water content evolution and decreasing carbonate ion concentration so that TA drops below preindustrial values. Yet, along with salinity, the Eurasian basin receives waters with higher DIC and TA from the Atlantic. As a result, the distributions of TA and DIC anomalies resemble the dipole pattern projected for salinity. We show that while future changes in the Arctic Ocean carbon cycle proceed at rates determined by atmospheric CO2 levels, the regional patterns are driven by shifts in the

  20. Critical adsorption in the undersaturated regime: Scaling and exact results in Ising strips

    NASA Astrophysics Data System (ADS)

    Ciach, A.; Maciolek, A.; Stecki, J.

    1998-04-01

    Critical adsorption for weak surface field h1 is reconsidered. On the basis of physical heuristic arguments, approximate behavior of the scaling function is derived. New form of a scaling for weak h1 in finite systems is proposed and verified by testing against exact results obtained for this purpose in the 2D Ising strips. For weak h1 we find the approximate behavior of adsorption Γ˜τβ-Δ1 for the reduced temperatures h11/Δ1˜τ≪1. This behavior is consistent with experimental data [N. S. Desai, S. Peach, and C. Franck, Phys. Rev. E 52, 4129 (1995)] obtained for τ=10-5, and is in a very good agreement with exact results in the 2D Ising strip.

  1. Widely Tunable Single-Photon Source from a Carbon Nanotube in the Purcell Regime.

    PubMed

    Jeantet, A; Chassagneux, Y; Raynaud, C; Roussignol, Ph; Lauret, J S; Besga, B; Estève, J; Reichel, J; Voisin, C

    2016-06-17

    The narrow emission of a single carbon nanotube at low temperature is coupled to the optical mode of a fiber microcavity using the built-in spatial and spectral matching brought by this flexible geometry. A thorough cw and time-resolved investigation of the very same emitter both in free space and in cavity shows an efficient funneling of the emission into the cavity mode together with a strong emission enhancement corresponding to a Purcell factor of up to 5. At the same time, the emitted photons retain a strong sub-Poissonian statistics. By exploiting the cavity feeding effect on the phonon wings, we locked the emission of the nanotube at the cavity resonance frequency, which allowed us to tune the frequency over a 4 THz band while keeping an almost perfect antibunching. By choosing the nanotube diameter appropriately, this study paves the way to the development of carbon-based tunable single-photon sources in the telecom bands. PMID:27367407

  2. Properties of single wall carbon nanotubes array antennas in the optical regime

    NASA Astrophysics Data System (ADS)

    Wu, Xiaofang; Jiang, Yuesong; Hua, Houqiang

    2014-11-01

    Single wall carbon nanotubes (SWCNTs) can be metallic, depending on their chirality. For their nanoscale geometric dimension, SWCNTs can be used as antennas to convert high-frequency electromagnetic radiation such as optical radiation into localized energy and vice versa. However, at optical frequencies, traditional antenna design theory fails for metals behave as strongly coupled plasmas. As a matter of fact, an optical antenna responds to a shorter effective wavelength which depends on the material properties and geometric parameters. In this letter, we derived the relationship of effective wavelength with the wavelength of incident radiation for SWCNTs optical antenna, assuming that the SWCNTs can be described by a free electron gas according to the Drude model. SWCNTs optical antenna holds great promise for increasing solar energy conversion efficiency.

  3. Tc-99 Adsorption on Selected Activated Carbons - Batch Testing Results

    SciTech Connect

    Mattigod, Shas V.; Wellman, Dawn M.; Golovich, Elizabeth C.; Cordova, Elsa A.; Smith, Ronald M.

    2010-12-01

    CH2M HILL Plateau Remediation Company (CHPRC) is currently developing a 200-West Area groundwater pump-and-treat system as the remedial action selected under the Comprehensive Environmental Response, Compensation, and Liability Act Record of Decision for Operable Unit (OU) 200-ZP-1. This report documents the results of treatability tests Pacific Northwest National Laboratory researchers conducted to quantify the ability of selected activated carbon products (or carbons) to adsorb technetium-99 (Tc-99) from 200-West Area groundwater. The Tc-99 adsorption performance of seven activated carbons (J177601 Calgon Fitrasorb 400, J177606 Siemens AC1230AWC, J177609 Carbon Resources CR-1240-AW, J177611 General Carbon GC20X50, J177612 Norit GAC830, J177613 Norit GAC830, and J177617 Nucon LW1230) were evaluated using water from well 299-W19-36. Four of the best performing carbons (J177606 Siemens AC1230AWC, J177609 Carbon Resources CR-1240-AW, J177611 General Carbon GC20X50, and J177613 Norit GAC830) were selected for batch isotherm testing. The batch isotherm tests on four of the selected carbons indicated that under lower nitrate concentration conditions (382 mg/L), Kd values ranged from 6,000 to 20,000 mL/g. In comparison. Under higher nitrate (750 mg/L) conditions, there was a measureable decrease in Tc-99 adsorption with Kd values ranging from 3,000 to 7,000 mL/g. The adsorption data fit both the Langmuir and the Freundlich equations. Supplemental tests were conducted using the two carbons that demonstrated the highest adsorption capacity to resolve the issue of the best fit isotherm. These tests indicated that Langmuir isotherms provided the best fit for Tc-99 adsorption under low nitrate concentration conditions. At the design basis concentration of Tc 0.865 µg/L(14,700 pCi/L), the predicted Kd values from using Langmuir isotherm constants were 5,980 mL/g and 6,870 mL/g for for the two carbons. These Kd values did not meet the target Kd value of 9,000 mL/g. Tests

  4. Carbon pools and flows during lab-scale degradation of old landfilled waste under different oxygen and water regimes

    SciTech Connect

    Brandstätter, Christian Laner, David Fellner, Johann

    2015-06-15

    Graphical abstract: Display Omitted - Highlights: • 40 year old waste from an old MSW landfill was incubated in LSR experiments. • Carbon balances for anaerobic and aerobic waste degradation were established. • The transformation of carbon pools during waste degradation was investigated. • Waste aeration resulted in the formation of a new, stable organic carbon pool. • Water addition did not have a significant effect on aerobic waste degradation. - Abstract: Landfill aeration has been proven to accelerate the degradation of organic matter in landfills in comparison to anaerobic decomposition. The present study aims to evaluate pools of organic matter decomposing under aerobic and anaerobic conditions using landfill simulation reactors (LSR) filled with 40 year old waste from a former MSW landfill. The LSR were operated for 27 months, whereby the waste in one pair was kept under anaerobic conditions and the four other LSRs were aerated. Two of the aerated LSR were run with leachate recirculation and water addition and two without. The organic carbon in the solid waste was characterized at the beginning and at the end of the experiments and major carbon flows (e.g. TOC in leachate, gaseous CO{sub 2} and CH{sub 4}) were monitored during operation. After the termination of the experiments, the waste from the anaerobic LSRs exhibited a long-term gas production potential of more than 20 NL kg{sup −1} dry waste, which corresponded to the mineralization of around 12% of the initial TOC (67 g kg{sup −1} dry waste). Compared to that, aeration led to threefold decrease in TOC (32–36% of the initial TOC were mineralized), without apparent differences in carbon discharge between the aerobic set ups with and without water addition. Based on the investigation of the carbon pools it could be demonstrated that a bit more than 10% of the initially present organic carbon was transformed into more recalcitrant forms, presumably due to the formation of humic substances

  5. In situ application of activated carbon and biochar to PCB-contaminated soil and the effects of mixing regime.

    PubMed

    Denyes, Mackenzie J; Rutter, Allison; Zeeb, Barbara A

    2013-11-01

    The in situ use of carbon amendments such as activated carbon (AC) and biochar to minimize the bioavailability of organic contaminants is gaining in popularity. In the first in situ experiment conducted at a Canadian PCB-contaminated Brownfield site, GAC and two types of biochar were statistically equal at reducing PCB uptake into plants. PCB concentrations in Cucurbita pepo root tissue were reduced by 74%, 72% and 64%, with the addition of 2.8% GAC, Burt's biochar and BlueLeaf biochar, respectively. A complementary greenhouse study which included a bioaccumulation study of Eisenia fetida (earthworm), found mechanically mixing carbon amendments with PCB-contaminated soil (i.e. 24 h at 30 rpm) resulted in shoot, root and worm PCB concentrations 66%, 59% and 39% lower than in the manually mixed treatments (i.e. with a spade and bucket). Therefore, studies which mechanically mix carbon amendments with contaminated soil may over-estimate the short-term potential to reduce PCB bioavailability. PMID:23933124

  6. THERMAL ESCAPE IN THE HYDRODYNAMIC REGIME: RECONSIDERATION OF PARKER's ISENTROPIC THEORY BASED ON RESULTS OF KINETIC SIMULATIONS

    SciTech Connect

    Volkov, Alexey N.; Johnson, Robert E.

    2013-03-10

    The one-dimensional steady-state problem of thermal escape from a single-component atmosphere of mon- and diatomic gases is studied in the hydrodynamic (blow-off) regime using the direct simulation Monte Carlo method for an evaporative-type condition at the lower boundary. The simulations are performed for various depths into an atmosphere, indicated by a Knudsen number, Kn{sub 0}, equal to the ratio of the mean free path of molecules to the radial position of the source surface, ranging from 10 to 10{sup -5}, and for the range of the source Jeans parameter, {lambda}{sub 0}, equal to the ratio of gravitational and thermal energies, specific to blow-off. The results of kinetic simulations are compared with the isentropic model (IM) and the Navier-Stokes model. It is shown that the IM can be simplified if formulated in terms of the local Mach number and Jeans parameter. The simulations predict that at Kn{sub 0} < {approx} 10{sup -3} the flow includes a near-surface non-equilibrium Knudsen layer, a zone where the flow can be well approximated by the IM, and a rarefied far field. The corresponding IM solutions, however, only approach Parker's critical solution as {lambda}{sub 0} approaches the upper limit for blow-off. The IM alone is not capable for predicting the flow and requires boundary conditions at the top of the Knudsen layer. For small Kn{sub 0}, the scaled escape rate and energy loss rate are found to be independent of {lambda}{sub 0}. The simulation results can be scaled to any single-component atmosphere exhibiting blow-off if the external heating above the lower boundary is negligible, in particular, to sublimation-driven atmospheres of Kuiper belt objects.

  7. Carbon Dioxide Sequestration by Direct Mineral Carbonation: Results from Recent Studies and Current Status

    SciTech Connect

    O'Connor, William K.; Dahlin, David C.; Nilsen, David N.; Rush, G.E.; Walters, Richard P.; Turner, Paul C.

    2001-01-01

    Direct mineral carbonation has been investigated as a process to convert gaseous CO2 into a geologically stable, solid final form. The process utilizes a solution of sodium bicarbonate (NaHCO3), sodium chloride (NaCl), and water, mixed with a mineral reactant, such as olivine (Mg2SiO4) or serpentine [Mg3Si2O5(OH)4]. Carbon dioxide is dissolved into this slurry, by diffusion through the surface and gas dispersion within the aqueous phase. The process includes dissolution of the mineral and precipitation of magnesium carbonate (MgCO3) in a single unit operation. Optimum results have been achieved using heat pretreated serpentine feed material, with a surface area of roughly 19 m2 per gram, and high partial pressure of CO2 (PCO2). Specific conditions include: 155?C; PCO2=185 atm; 15% solids. Under these conditions, 78% stoichiometric conversion of the silicate to the carbonate was achieved in 30 minutes. Studies suggest that the mineral dissolution rate is primarily surface controlled, while the carbonate precipitation rate is primarily dependent on the bicarbonate concentration of the slurry. Current studies include further examination of the reaction pathways, and an evaluation of the resource potential for the magnesium silicate reactant, particularly olivine. Additional studies include the examination of various pretreatment options, the development of a continuous flow reactor, and an evaluation of the economic feasibility of the process.

  8. Thermal regime and potential bedrock weathering in alpine rockwalls of Austria: Results from eight years of monitoring (2006-2014)

    NASA Astrophysics Data System (ADS)

    Kellerer-Pirklbauer, Andreas; Wecht, Matthias

    2015-04-01

    Bedrock temperature at sites with a minor winter snow cover gives a good indication for the effects of air temperature anomalies on ground thermal conditions as well as for the intensity of near-surface physical weathering in bedrock. In this study we present results from an ongoing bedrock temperature monitoring program initiated in 2006. Within the framework of this program nine surface boreholes in rockwalls with different slope orientations and two additional boreholes at flat bedrock sites were drilled between August and September 2006 and subsequently instrumented. The altogether eleven rock temperature sites (RTS) are located in the alpine periglacial zone of the Austrian Alps at latitude 46°55' to 47°22' and longitude 12°44' to 14°41'. All RTS have been installed in metamorphic rock (5 x mica schist; 6 x gneiss) at elevations between 1960 and 2725 m asl (mean 2491 m asl.). Three temperature sensors (PT1000) have been inserted at each borehole site at vertical depths of 3, 10 and 30-40 cm. At each RTS the three sensors are connected to a 3-channel miniature temperature datalogger (MTD) manufactured by GeoPrecision, Germany. Our analysis focussed on (a) the variation of mean and extreme daily temperatures at the rock surface and at depth, (b) the variation of the daily temperature range, (c) the number of freeze-thaw-cycles (FTC) and (d) effective freeze-thaw cycles for frost shattering (eFTC), (e) the duration and intensity of freeze-thaw-cycles (DI-FTC), (f) the number of hours and days within the so-called frost-cracking-window (FCW), and effects of (g) aspect and (h) snow cover on the thermal regimes in the bedrock. Results show for instance that the number of FTC and eFTC varied substantially during the observation period at all eleven RTS and at all sensor depths. However, this variation differs from site to site related to snow cover condition, elevation and aspect. For instance, at one lower-elevated (2255 m asl) north exposed RTS the number of

  9. Amazon Forest Response to Changes in Rainfall Regime: Results from an Individual-Based Dynamic Vegetation Model

    NASA Astrophysics Data System (ADS)

    Longo, Marcos

    The Amazon is the largest tropical rainforest in the world, and thus plays a major role on global water, energy, and carbon cycles. However, it is still unknown how the Amazon forest will respond to the ongoing changes in climate, especially droughts, which are expected to become more frequent. To help answering this question, in this thesis I developed and improved the representation of biophysical processes and photosynthesis in the Ecosystem Demography model (ED-2.2), an individual-based land ecosystem model. I also evaluated the model biophysics against multiple data sets for multiple forest and savannah sites in tropical South America. Results of this comparison showed that ED-2.2 is able to represent the radiation and water cycles, but exaggerates heterotrophic respiration seasonality. Also, the model generally predicted correct distribution of biomass across different areas, although it overestimated biomass in subtropical savannahs. To evaluate the forest resilience to droughts, I used ED-2.2 to simulate the plant community dynamics at two sites in Eastern Amazonia, and developed scenarios by resampling observed annual rainfall but increasing the probability of selecting dry years. While the model predicted little response at French Guiana, results at the mid-Eastern Amazonia site indicated substantial biomass loss at modest rainfall reductions. Also, the response to drier climate varied within the plant community, with evergreen, early-successional, and larger trees being the most susceptible. The model also suggests that competition for water during prolonged periods of drought caused the largest impact on larger trees, when insufficient wet season rainfall did not recharge deeper soil layers. Finally, results suggested that a decrease in return period of long-lasting droughts could prevent ecosystem recovery. Using different rainfall datasets, I defined vulnerability based on the change in climate needed to reduce the return period of long droughts. The

  10. Carbon dioxide fluxes from Tifway bermudagrass: early results

    NASA Astrophysics Data System (ADS)

    Cotten, David L.; Zhang, G.; Leclerc, M. Y.; Raymer, P.; Steketee, C. J.

    2016-06-01

    This paper reports for the first time preliminary data on carbon uptake of warm-season turfgrass at a well-managed sod farm in south central Georgia. It examines the changes in carbon uptake from one of the most widely used warm-season turfgrass cultivars in the world, Tifway Bermudagrass. It elucidates the role of canopy density and light avalaibility on the net carbon uptake using the eddy-covariance technique. Preliminary evidence suggests that turfgrass is effective at sequestering carbon dioxide during the summer months even when the canopy is being reestablished following a grass harvest.

  11. Variation of organic carbon and nitrate with river flow within an oceanic regime in a rural area and potential impacts for drinking water production

    NASA Astrophysics Data System (ADS)

    Baurès, E.; Delpla, I.; Merel, S.; Thomas, M.-F.; Jung, A.-V.; Thomas, O.

    2013-01-01

    SummaryOver the last two decades, climate change has become a major environmental and public health concern due to the increase of the mean temperature on the Earth and its consequences on extreme meteorological events such as floods and droughts. These events induce very low or very high river flows that may impair surface water quality, and therefore result in potential health impacts when used for drinking water production. The present study aims at assessing the impact of hydrologic regime on surface water quality with a particular emphasis on total organic carbon (TOC) and nitrate. Water quality data from three French rivers acquired over a 27 years period, from January 1983 to December 2009, show the influence of extreme flows. Variation in TOC and nitrate concentrations showed opposite patterns for the whole range of flow rate (from less than 10% up to more than 100% of the mean flow). Regarding fluxes, TOC increased continuously with flow rate while nitrate was stable for very high discharges. The C/N ratio expressed from TOC and nitrate concentrations showed high values for extreme flows and particularly for very low flow rates, generally in summer, where nitrate is assimilated by biomass. Considering TOC and nitrate fluxes, it is confirmed that the worst situations were encountered for very high flow rates, namely for TOC exportation during surface runoff which was related to heavy rains or floods. These findings are of great importance with regard to the adaptation for drinking water treatment in facing extreme hydrological conditions, of which the frequency is increasing with climate change.

  12. Collective electronic excitations in the ultra violet regime in 2-D and 1-D carbon nanostructures achieved by the addition of foreign atoms

    PubMed Central

    Bangert, U.; Pierce, W.; Boothroyd, C.; Pan, C.-T.; Gwilliam, R.

    2016-01-01

    Plasmons in the visible/UV energy regime have attracted great attention, especially in nano-materials, with regards to applications in opto-electronics and light harvesting; tailored enhancement of such plasmons is of particular interest for prospects in nano-plasmonics. This work demonstrates that it is possible, by adequate doping, to create excitations in the visible/UV regime in nano-carbon materials, i.e., carbon nanotubes and graphene, with choice of suitable ad-atoms and dopants, which are introduced directly into the lattice by low energy ion implantation or added via deposition by evaporation. Investigations as to whether these excitations are of collective nature, i.e., have plasmonic character, are carried out via DFT calculations and experiment-based extraction of the dielectric function. They give evidence of collective excitation behaviour for a number of the introduced impurity species, including K, Ag, B, N, and Pd. It is furthermore demonstrated that such excitations can be concentrated at nano-features, e.g., along nano-holes in graphene through metal atoms adhering to the edges of these holes. PMID:27271352

  13. Collective electronic excitations in the ultra violet regime in 2-D and 1-D carbon nanostructures achieved by the addition of foreign atoms.

    PubMed

    Bangert, U; Pierce, W; Boothroyd, C; Pan, C-T; Gwilliam, R

    2016-01-01

    Plasmons in the visible/UV energy regime have attracted great attention, especially in nano-materials, with regards to applications in opto-electronics and light harvesting; tailored enhancement of such plasmons is of particular interest for prospects in nano-plasmonics. This work demonstrates that it is possible, by adequate doping, to create excitations in the visible/UV regime in nano-carbon materials, i.e., carbon nanotubes and graphene, with choice of suitable ad-atoms and dopants, which are introduced directly into the lattice by low energy ion implantation or added via deposition by evaporation. Investigations as to whether these excitations are of collective nature, i.e., have plasmonic character, are carried out via DFT calculations and experiment-based extraction of the dielectric function. They give evidence of collective excitation behaviour for a number of the introduced impurity species, including K, Ag, B, N, and Pd. It is furthermore demonstrated that such excitations can be concentrated at nano-features, e.g., along nano-holes in graphene through metal atoms adhering to the edges of these holes. PMID:27271352

  14. Collective electronic excitations in the ultra violet regime in 2-D and 1-D carbon nanostructures achieved by the addition of foreign atoms

    NASA Astrophysics Data System (ADS)

    Bangert, U.; Pierce, W.; Boothroyd, C.; Pan, C.-T.; Gwilliam, R.

    2016-06-01

    Plasmons in the visible/UV energy regime have attracted great attention, especially in nano-materials, with regards to applications in opto-electronics and light harvesting; tailored enhancement of such plasmons is of particular interest for prospects in nano-plasmonics. This work demonstrates that it is possible, by adequate doping, to create excitations in the visible/UV regime in nano-carbon materials, i.e., carbon nanotubes and graphene, with choice of suitable ad-atoms and dopants, which are introduced directly into the lattice by low energy ion implantation or added via deposition by evaporation. Investigations as to whether these excitations are of collective nature, i.e., have plasmonic character, are carried out via DFT calculations and experiment-based extraction of the dielectric function. They give evidence of collective excitation behaviour for a number of the introduced impurity species, including K, Ag, B, N, and Pd. It is furthermore demonstrated that such excitations can be concentrated at nano-features, e.g., along nano-holes in graphene through metal atoms adhering to the edges of these holes.

  15. Were fossil spring-associated carbonates near Zaca Lake, Santa Barbara, California deposited under an ambient or thermal regime?

    NASA Astrophysics Data System (ADS)

    Ibarra, Yadira; Corsetti, Frank A.; Cheetham, Michael I.; Feakins, Sarah J.

    2014-03-01

    A previously undescribed succession of currently-inactive spring-associated carbonates located near Zaca Lake, Southern California, was investigated in order to determine the nature of deposition (ambient temperature or hydrothermal water, as both are found within the region). The carbonate deposits are up to ~ 1 m thick and formed discontinuously for over 200 m in a narrow valley between two ridges that drain Miocene Monterey Formation bedrock. Depositional facies along the presently dry fluvial path include barrage deposits, narrow fluvial channels, and cascade deposits. The carbonates are mesoscopically banded and contain ubiquitous micro- to macrophyte calcite encrusted fabrics. All of the depositional facies contain alternating bands (~ .05 mm to 5 mm thick) of dark brown and light brown isopachous calcite; the dark brown bands are composed of dense isopachous bladed calcite, whereas the light brown bands are composed of bundles of calcite tubules interpreted as the biosignature of the desmid microalgae Oocardium stratum. Oxygen isotope thermometry utilizing modern water δ18O values from the piped spring reveal depositional water temperature estimates that collectively range from ~ 11 to 16 °C. Stable isotope carbon values exhibit a mean δ13C value of - 9.01 ± 0.62‰ (1σ, n = 27). Our petrographic and geochemical data demonstrate that (1) inactive carbonates were likely sourced from ambient temperature water with a strong soil-zone δ13C signal, (2) the Oocardium calcite biosignature can be used to infer depositional temperature and flow conditions, and (3) the occurrence of extensive carbonates (especially the presence of a perched cascade deposit) indicate the carbonates formed when conditions were much wetter.

  16. Total carbon measurement in soils using laser-induced breakdown spectroscopy : Results from the field and implications for carbon sequestration

    SciTech Connect

    Ebinger, M. H.; Breshears, D. D.; Unkefer, P. J.; Cremers, D. A.; Kammerdiener, S. A.; Ferris, M. J.

    2001-01-01

    Rapid measurement of total carbon in soils is an important factor in modeling the effects of global change and carbon sequestration in soils. Conventional methods of carbon analysis such as dry combustion are relatively slow, and reliable estimation of carbon concentrations at the landscape scale is practically impossible because of the need for many replicate measurements. A new spectroscopic method, laser-induced breakdown spectroscopy (LIBS), provides rapid carbon analysis with little or no sample preparation time. LIBS is portable and can be used for carbon analysis in the field or even in situ, such as inside a soil borehole. Data from LIBS analyses can be used to monitor small changes in soil carbon at different times, a critical component in many global climate models and terrestrial carbon sequestration strategies. We present a comparison of dry combustion measurements with LIBS analyses using several agricultural and woodland soils. The LIBS data are highly reproducible, are not affected by differences in soil types, and there is a strong correlation with dry combustion measurements. We further show the results of carbon measurements in different parts of a pinon-juniper woodland in semiarid New Mexico. Our results highlight soil carbon concentrations under tree canopies, in intercanopy spaces, and in small-scale catchments within the woodland. The latter measurements show an important, but until use of LIBS, overlooked store of carbon in semiarid areas. The use of LIBS data shows many benefits including reducing the uncertainty inherent in measurements of soil carbon in different environments, the speed with which LIBS analyses can be obtained (minutes) compared to dry combustion (days), and in modeling the global cycling of carbon in terrestrial settings. LIBS analyses make possible the estimation of landscape-scale carbon inventories that require large sample numbers as well as detailed quantification of carbon concentrations in soils under canopies or

  17. Dynamic Pore-Scale Imaging of Reactive Transport in Heterogeneous Carbonates at Reservoir Conditions Across Multiple Dissolution Regimes

    NASA Astrophysics Data System (ADS)

    Menke, H. P.; Bijeljic, B.; Andrew, M. G.; Blunt, M. J.

    2014-12-01

    Sequestering carbon in deep geologic formations is one way of reducing anthropogenic CO2 emissions. When supercritical CO2 mixes with brine in a reservoir, the acid generated has the potential to dissolve the surrounding pore structure. However, the magnitude and type of dissolution are condition dependent. Understanding how small changes in the pore structure, chemistry, and flow properties affect dissolution is paramount for successful predictive modelling. Both 'Pink Beam' synchrotron radiation and a Micro-CT lab source are used in dynamic X-ray microtomography to investigate the pore structure changes during supercritical CO2 injection in carbonate rocks of varying heterogeneity at high temperatures and pressures and various flow-rates. Three carbonate rock types were studied, one with a homogeneous pore structure and two heterogeneous carbonates. All samples are practically pure calcium carbonate, but have widely varying rock structures. Flow-rate was varied in three successive experiments by over an order of magnitude whlie keeping all other experimental conditions constant. A 4-mm carbonate core was injected with CO2-saturated brine at 10 MPa and 50oC. Tomographic images were taken at 30-second to 20-minute time-resolutions during a 2 to 4-hour injection period. A pore network was extracted using a topological analysis of the pore space and pore-scale flow modelling was performed directly on the binarized images with connected pathways and used to track the altering velocity distributions. Significant differences in dissolution type and magnitude were found for each rock type and flowrate. At the highest flow-rates, the homogeneous carbonate was seen to have predominately uniform dissolution with minor dissolution rate differences between the pores and pore throats. Alternatively, the heterogeneous carbonates which formed wormholes at high flow rates. At low flow rates the homogeneous rock developed wormholes, while the heterogeneous samples showed evidence

  18. Snowpack regimes of the Western United States

    NASA Astrophysics Data System (ADS)

    Trujillo, Ernesto; Molotch, Noah P.

    2014-07-01

    Snow accumulation and melt patterns play a significant role in the water, energy, carbon, and nutrient cycles in the montane environments of the Western United States. Recent studies have illustrated that changes in the snow/rainfall apportionments and snow accumulation and melt patterns may occur as a consequence of changes in climate in the region. In order to understand how these changes may affect the snow regimes of the region, the current characteristics of the snow accumulation and melt patterns must be identified. Here we characterize the snow water equivalent (SWE) curve formed by the daily SWE values at 766 snow pillow stations in the Western United States, focusing on several metrics of the yearly SWE curves and the relationships between the different metrics. The metrics are the initial snow accumulation and snow disappearance dates, the peak snow accumulation and date of peak, the length of the snow accumulation season, the length of the snowmelt season, and the snow accumulation and snowmelt slopes. Three snow regimes emerge from these results: a maritime, an intermountain, and a continental regime. The maritime regime is characterized by higher maximum snow accumulations reaching 300 cm and shorter accumulation periods of less than 220 days. Conversely, the continental regime is characterized by lower maximum accumulations below 200 cm and longer accumulation periods reaching over 260 days. The intermountain regime lies in between. The regions that show the characteristics of the maritime regime include the Cascade Mountains, the Klamath Mountains, and the Sierra Nevada Mountains. The intermountain regime includes the Eastern Cascades slopes and foothills, the Blue Mountains, Northern and Central basins and ranges, the Columbia Mountains/Northern Rockies, the Idaho Batholith, and the Canadian Rockies. Lastly, the continental regime includes the Middle and Southern Rockies, and the Wasatch and Uinta Mountains. The implications of snow regime

  19. Compilation of reinforced carbon-carbon transatlantic abort landing arc jet test results

    NASA Technical Reports Server (NTRS)

    Milhoan, James D.; Pham, Vuong T.; Yuen, Eric H.

    1993-01-01

    This document consists of the entire test database generated to support the Reinforced Carbon-Carbon Transatlantic Abort Landing Study. RCC components used for orbiter nose cap and wing leading edge thermal protection were originally designed to have a multi-mission entry capability of 2800 F. Increased orbiter range capability required a predicted increase in excess of 3300 F. Three test series were conducted. Test series #1 used ENKA-based RCC specimens coated with silicon carbide, treated with tetraethyl orthosilicate, sealed with Type A surface enhancement, and tested at 3000-3400 F with surface pressure of 60-101 psf. Series #2 used ENKA- or AVTEX-based RCC, with and without silicon carbide, Type A or double Type AA surface enhancement, all impregnated with TEOS, and at temperatures from 1440-3350 F with pressures from 100-350 psf. Series #3 tested ENKA-based RCC, with and without silicon carbide coating. No specimens were treated with TEOS or sealed with Type A. Surface temperatures ranged from 2690-3440 F and pressures ranged from 313-400 psf. These combined test results provided the database for establishing RCC material single-mission-limit temperature and developing surface recession correlations used to predict mass loss for abort conditions.

  20. Carbon pools and flows during lab-scale degradation of old landfilled waste under different oxygen and water regimes.

    PubMed

    Brandstätter, Christian; Laner, David; Fellner, Johann

    2015-06-01

    Landfill aeration has been proven to accelerate the degradation of organic matter in landfills in comparison to anaerobic decomposition. The present study aims to evaluate pools of organic matter decomposing under aerobic and anaerobic conditions using landfill simulation reactors (LSR) filled with 40 year old waste from a former MSW landfill. The LSR were operated for 27 months, whereby the waste in one pair was kept under anaerobic conditions and the four other LSRs were aerated. Two of the aerated LSR were run with leachate recirculation and water addition and two without. The organic carbon in the solid waste was characterized at the beginning and at the end of the experiments and major carbon flows (e.g. TOC in leachate, gaseous CO2 and CH4) were monitored during operation. After the termination of the experiments, the waste from the anaerobic LSRs exhibited a long-term gas production potential of more than 20 NL kg(-1) dry waste, which corresponded to the mineralization of around 12% of the initial TOC (67 g kg(-1) dry waste). Compared to that, aeration led to threefold decrease in TOC (32-36% of the initial TOC were mineralized), without apparent differences in carbon discharge between the aerobic set ups with and without water addition. Based on the investigation of the carbon pools it could be demonstrated that a bit more than 10% of the initially present organic carbon was transformed into more recalcitrant forms, presumably due to the formation of humic substances. The source of anaerobic degradation could be identified mainly as cellulose which played a minor role during aerobic degradation in the experiment. PMID:25816770

  1. Spatial distribution of seafloor bio-geological and geochemical processes as proxies of fluid flux regime and evolution of a carbonate/hydrates mound, northern Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Macelloni, Leonardo; Brunner, Charlotte A.; Caruso, Simona; Lutken, Carol B.; D'Emidio, Marco; Lapham, Laura L.

    2013-04-01

    Woolsey Mound, a carbonate/hydrate complex of cold seeps, vents, and seafloor pockmarks in Mississippi Canyon Block 118, is the site of the Gulf of Mexico Hydrates Research Consortium's (GOMHRC) multi-sensor, multi-disciplinary, permanent seafloor observatory. In preparation for installing the observatory, the site has been studied through geophysical, biological, geological, and geochemical surveys. By integrating high-resolution, swath bathymetry, acoustic imagery, seafloor video, and shallow geological samples in a morpho-bio-geological model, we have identified a complex mound structure consisting of three main crater complexes: southeast, northwest, and southwest. Each crater complex is associated with a distinct fault. The crater complexes exhibit differences in morphology, bathymetric relief, exposed hydrates, fluid venting, sediment accumulation rates, sediment diagenesis, and biological community patterns. Spatial distribution of these attributes suggests that the complexes represent three different fluid flux regimes: the southeast complex seems to be an extinct or quiescent vent; the northwest complex exhibits young, vigorous activity; and the southwest complex is a mature, fully open vent. Geochemical evidence from pore-water gradients corroborates this model suggesting that upward fluid flux waxes and wanes over time and that microbial activity is sensitive to such change. Sulfate and methane concentrations show that microbial activity is patchy in distribution and is typically higher within the northwest and southwest complexes, but is diminished significantly over the southeast complex. Biological community composition corroborates the presence of distinct conditions at the three crater complexes. The fact that three different fluid flux regimes coexist within a single mound complex confirms the dynamic nature of the plumbing system that discharges gases into bottom water. Furthermore, the spatial distribution of bio-geological processes appears to

  2. Hydrogen storage in carbon materials—preliminary results

    NASA Astrophysics Data System (ADS)

    Jörissen, Ludwig; Klos, Holger; Lamp, Peter; Reichenauer, Gudrun; Trapp, Victor

    1998-08-01

    Recent developments aiming at the accelerated commercialization of fuel cells for automotive applications have triggered an intensive research on fuel storage concepts for fuel cell cars. The fuel cell technology currently lacks technically and economically viable hydrogen storage technologies. On-board reforming of gasoline or methanol into hydrogen can only be regarded as an intermediate solution due to the inherently poor energy efficiency of such processes. Hydrogen storage in carbon nanofibers may lead to an efficient solution to the above described problems.

  3. Primary carbonates and Ca-chloride brines as monitors of a paleo-hydrological regime in the Dead Sea basin

    NASA Astrophysics Data System (ADS)

    Waldmann, Nicolas; Starinsky, Abraham; Stein, Mordechai

    2007-09-01

    Lakes Samra, Lisan and the Dead Sea occupied the Dead Sea basin during the Last Interglacial (˜140-75 ka BP), last glacial (˜70-14 ka BP) and Holocene periods, respectively. The age of Lake Lisan and Samra was determined by U-Th dating of primary aragonites comprising parts of the lacustrine sedimentary sequences. The lakes have periodically deposited sequences of layered calcitic marls (Lake Samra) or laminated primary aragonite (Lake Lisan). The deposition of aragonite as the primary carbonate phase reflects the contribution of the incoming freshwater (loaded with bi-carbonate) and high Mg-, Ca-chloride brine that originated from the subsurface vicinity of the Dead Sea basin. Deposition of calcitic marls suggests a minor effect of the brines. The Ca-chloride subsurface brine has been migrating in and out of the wall rocks of the Dead Sea basin, reflecting the regional hydrological conditions. During most of the last glacial period and during the late Holocene, sufficient precipitation above the Judea Mountains pushed the subsurface Ca-chloride brines into the lakes causing the deposition of aragonite. During the Last Interglacial period the rain that precipitated above the Judea Mountains was insufficient to induce brine flow toward Lake Samra. It appears that sporadic floods provided calcium, bicarbonate and detritus to produce the Samra calcitic marls. Travertines deposited at the Samra-Lisan boundary indicate the early stage in the resumption of groundwater (springs) activity that led to the resurgence of Ca-chloride brine and rise of Lake Lisan. Similar variations in the regional rain precipitation and hydrological activity probably characterized the long-term geochemical evolution of Pleistocene lacustrine water-bodies in the Dead Sea basin, enabling the use of the carbonates as paleo-hydrological monitors.

  4. Results of the "carbon conference" international aerosol carbon round robin test stage I

    NASA Astrophysics Data System (ADS)

    Schmid, Heidrun; Laskus, Lothar; Jürgen Abraham, Hans; Baltensperger, Urs; Lavanchy, Vincent; Bizjak, Mirko; Burba, Peter; Cachier, Helene; Crow, Dale; Chow, Judith; Gnauk, Thomas; Even, Arja; ten Brink, H. M.; Giesen, Klaus-Peter; Hitzenberger, Regina; Hueglin, Christoph; Maenhaut, Willy; Pio, Casimiro; Carvalho, Abel; Putaud, Jean-Philippe; Toom-Sauntry, Desiree; Puxbaum, Hans

    An international round robin test on the analysis of carbonaceous aerosols on quartz fiber filters sampled at an urban site was organized by the Vienna University of Technology. Seventeen laboratories participated using nine different thermal and optical methods. For the analysis of total carbon (TC), a good agreement of the values obtained by all laboratories was found (7 and 9% r.s.d.) with only two outliers in the complete data set. In contrast the results of the determination of elemental carbon (EC) in two not pre-extracted samples were highly variable ranging over more than one order of magnitude and the relative standard deviations (r.s.d.) of the means were 36.6 and 45.5%. The laboratories that obtained similar results by using methods which reduce the charring artifact were put together to a new data set in order to approach a "real EC" value. The new data set consisting of the results of 10 laboratories using seven different methods showed 16 and 24% lower averages and r.s.d. of 14 and 24% for the two not pre-extracted samples. Taking the current filters as "equivalents" for urban aerosol samples we conclude that the following methods can be used for the analysis of EC in carbonaceous aerosols: thermal methods with an optical feature to correct for charring during pyrolysis, two-step thermal procedures reducing charring during pyrolysis, the VDI 2465/1 method (removal of OC by solvent extraction and thermodesorption in nitrogen) and the VDI 2465/2 method (combustion of OC and EC at different temperatures) with an additional pre-extraction with a dimethyl formamide (DMF)/toluene mixture. Only thermal methods without any correction for charring during pyrolysis and the VDI 2465/2 method were outside the range of twice the standard deviation of the new data set. For a filter sample pre-extracted with the DMF/toluene mixture the average and r.s.d. from all laboratories (20.7 μgC; 24.4% r.s.d.) was very similar as for the laboratory set reduced to 10

  5. Regime change?

    SciTech Connect

    Pilat, Joseph F.; Budlong-Sylvester, K. W.

    2004-01-01

    Following the 1998 nuclear tests in South Asia and later reinforced by revelations about North Korean and Iraqi nuclear activities, there has been growing concern about increasing proliferation dangers. At the same time, the prospects of radiological/nuclear terrorism are seen to be rising - since 9/11, concern over a proliferation/terrorism nexus has never been higher. In the face of this growing danger, there are urgent calls for stronger measures to strengthen the current international nuclear nonproliferation regime, including recommendations to place civilian processing of weapon-useable material under multinational control. As well, there are calls for entirely new tools, including military options. As proliferation and terrorism concerns grow, the regime is under pressure and there is a temptation to consider fundamental changes to the regime. In this context, this paper will address the following: Do we need to change the regime centered on the Treaty on the Nonproliferation of Nuclear Weapons (NPT) and the International Atomic Energy Agency (IAEA)? What improvements could ensure it will be the foundation for the proliferation resistance and physical protection needed if nuclear power grows? What will make it a viable centerpiece of future nonproliferation and counterterrorism approaches?

  6. Compressible magnetic Rayleigh-Taylor instability in stratified plasmas: Comparison of analytical and numerical results in the linear regime

    SciTech Connect

    Liberatore, S.; Jaouen, S.; Tabakhoff, E.; Canaud, B.

    2009-04-15

    Magnetic Rayleigh-Taylor instability is addressed in compressible hydrostatic media. A full model is presented and compared to numerical results from a linear perturbation code. A perfect agreement between both approaches is obtained in a wide range of parameters. Compressibility effects are examined and substantial deviations from classical Chandrasekhar growth rates are obtained and confirmed by the model and the numerical calculations.

  7. Brown Carbon: Results From Ground and Airborne Studies

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  8. Catastrophic regime shifts in coral communities exposed to physical disturbances: simulation results from object-oriented 3-dimensional coral reef model.

    PubMed

    Tam, Tze-wai; Ang, Put O

    2009-07-21

    A 3-dimensional individual-based model, the ReefModel, was developed to simulate the dynamical structure of coral reef community using object-oriented techniques. Interactions among functional groups of reef organisms were simulated in the model. The behaviours of these organisms were described with simple mechanistic rules that were derived from their general behaviours (e.g. growing habits, competitive mechanisms, response to physical disturbance) observed in natural coral reef communities. The model was implemented to explore the effects of physical disturbance on the dynamical structure of a 3-coral community that was characterized with three functional coral groups: tabular coral, foliaceous coral and massive coral. Simulation results suggest that (i) the integration of physical disturbance and differential responses (disturbance sensitivity and growing habit) of corals plays an important role in structuring coral communities; (ii) diversity of coral communities can be maximal under intermediate level of acute physical disturbance; (iii) multimodality exists in the final states and dynamic regimes of individual coral group as well as coral community structure, which results from the influence of small random spatial events occurring during the interactions among the corals in the community, under acute and repeated physical disturbances. These results suggest that alternative stable states and catastrophic regime shifts may exist in a coral community under unstable physical environment. PMID:19306887

  9. A Comparison of Symmetric and Asymmetric Warming Regimes on the Soil Carbon and Nitrogen Dynamics of Grassland Ecosystems

    NASA Astrophysics Data System (ADS)

    Wig, J.; Lajtha, K.; Gregg, J. W.

    2010-12-01

    Global mean temperatures have increased 0.10 to 0.16°C per decade over the last 50 years, and continued increases in atmospheric greenhouse gas concentrations are expected to cause temperatures to increase by more than 3°C by the middle of the 21st century. While many warming experiments have been performed, most have determined impacts of equal increases in day and night temperatures on production, diversity, or ecosystem carbon dynamics. However, there have been faster increases in daily minimum temperature (Tmin) than daily maximum temperature (Tmax), a phenomenon commonly referred to as asymmetric warming. Photosynthesis and respiration are differentially affected by altered day and night temperatures, and thus the ecological effects of alterations in Tmin could differ from alterations in Tmax. Therefore, it is imperative that we expand our understanding of potential impacts of global warming to include the effects of asymmetrically elevated temperature profiles. To examine the affects of asymmetric vs. symmetric warming, we used Terracosm chambers with planted grassland communities native to Oregon’s Willamette Valley. The warmed chambers are subjected to an average increase of +3.5°C/day, with asymmetrically warmed chambers having an increase of dawn Tmin of +5°C, and an increase of midday Tmax of +2°C; and with symmetrically warmed chambers having a constant increase of +3.5°C. The goals of this project are to assess (1) whether patterns of increased NPP, changes in species composition and altered C, H2O and nutrient cycles shown for symmetric warming are similar in the asymmetric profiles, or whether entirely different patterns emerge unique to the asymmetrically elevated temperature treatments, and (2) whether the impacts of asymmetric and symmetric warming differ for soil C stabilization and destabilization processes. Our data indicate that whole ecosystem carbon balance was negative, with higher respiration than photosynthesis, for both symmetric

  10. Increase of Carbon Cycle Feedback with Climate Sensitivity: Results from a coupled Climate and Carbon Cycle Model

    SciTech Connect

    Govindasamy, B; Thompson, S; Mirin, A; Wickett, M; Caldeira, K; Delire, C

    2004-04-01

    Coupled climate and carbon cycle modeling studies have shown that the feedback between global warming and the carbon cycle, in particular the terrestrial carbon cycle, could accelerate climate change and result in larger warming. In this paper, we investigate the sensitivity of this feedback for year-2100 global warming in the range of 0 K to 8 K. Differing climate sensitivities to increased CO{sub 2} content are imposed on the carbon cycle models for the same emissions. Emissions from the SRES A2 scenario are used. We use a fully-coupled climate and carbon cycle model, the INtegrated Climate and CArbon model (INCCA) the NCAR/DOE Parallel Coupled Model coupled to the IBIS terrestrial biosphere model and a modified-OCMIP ocean biogeochemistry model. In our model, for scenarios with year-2100 global warming increasing from 0 to 8 K, land uptake decreases from 47% to 29% of total CO{sub 2} emissions. Due to competing effects, ocean uptake (16%) shows almost no change at all. Atmospheric CO{sub 2} concentration increases were 48% higher in the run with 8 K global climate warming than in the case with no warming. Our results indicate that carbon cycle amplification of climate warming will be greater if there is higher climate sensitivity to increased atmospheric CO{sub 2} content; the carbon cycle feedback factor increases from 1.13 to 1.48 when global warming increases from 3.2 to 8 K.

  11. Mass transport through carbon nanotube membranes in three different regimes: ionic diffusion and gas and liquid flow.

    PubMed

    Majumder, Mainak; Chopra, Nitin; Hinds, Bruce J

    2011-05-24

    Transport phenomena through the hollow conduits of carbon nanotubes (CNTs) are subjects of intense theoretical and experimental research. We have studied molecular transport over the large spectrum of ionic diffusion to pressure-driven gaseous and liquid flow. Plasma oxidation during the fabrication of the membrane introduces carboxylic acid groups at the CNT entrance, which provides electrostatic "gatekeeper" effects on ionic transport. Diffusive transport of ions of different charge and size through the core of the CNT is close to bulk diffusion expectations and allows estimation of the number of open pores or porosity of the membrane. Flux of gases such as N(2), CO(2), Ar, H(2), and CH(4) scaled inversely with their molecular weight by an exponent of 0.4, close to expected kinetic theory velocity expectations. However, the magnitude of the fluxes was ∼15- to 30-fold higher than predicted from Knudsen diffusion kinetics and consistent with specular momentum reflection inside smooth pores. Polar liquids such as water, ethanol, and isopropyl alcohol and nonpolar liquids such as hexane and decane were dramatically enhanced, with water flow over 4 orders of magnitude larger than "no-slip" hydrodynamic flow predictions. As direct experimental proof for the mechanism of near perfect slip conditions within CNT cores, a stepwise hydrophilic functionalization of CNT membranes from as-produced, tip-functionalized, and core-functionalized was performed. Pressure-driven water flow through the membrane was reduced from 5 × 10(4) to 2 × 10(2) to less than a factor of 5 enhancement over conventional Newtonian flow, while retaining nearly the same pore area. PMID:21500837

  12. National assessment of geologic carbon dioxide storage resources: results

    USGS Publications Warehouse

    U.S. Geological Survey Geologic Carbon Dioxide Storage Resources Assessment Team

    2013-01-01

    In 2012, the U.S. Geological Survey (USGS) completed an assessment of the technically accessible storage resources (TASR) for carbon dioxide (CO2) in geologic formations underlying the onshore and State waters area of the United States. The formations assessed are at least 3,000 feet (914 meters) below the ground surface. The TASR is an estimate of the CO2 storage resource that may be available for CO2 injection and storage that is based on present-day geologic and hydrologic knowledge of the subsurface and current engineering practices. Individual storage assessment units (SAUs) for 36 basins were defined on the basis of geologic and hydrologic characteristics outlined in the assessment methodology of Brennan and others (2010, USGS Open-File Report 2010–1127) and the subsequent methodology modification and implementation documentation of Blondes, Brennan, and others (2013, USGS Open-File Report 2013–1055). The mean national TASR is approximately 3,000 metric gigatons (Gt). The estimate of the TASR includes buoyant trapping storage resources (BSR), where CO2 can be trapped in structural or stratigraphic closures, and residual trapping storage resources, where CO2 can be held in place by capillary pore pressures in areas outside of buoyant traps. The mean total national BSR is 44 Gt. The residual storage resource consists of three injectivity classes based on reservoir permeability: residual trapping class 1 storage resource (R1SR) represents storage in rocks with permeability greater than 1 darcy (D); residual trapping class 2 storage resource (R2SR) represents storage in rocks with moderate permeability, defined as permeability between 1 millidarcy (mD) and 1 D; and residual trapping class 3 storage resource (R3SR) represents storage in rocks with low permeability, defined as permeability less than 1 mD. The mean national storage resources for rocks in residual trapping classes 1, 2, and 3 are 140 Gt, 2,700 Gt, and 130 Gt, respectively. The known recovery

  13. Carbon-nitrogen interactions regulate climate-carbon cycle feedbacks: results from an atmosphere-ocean general circulation model

    SciTech Connect

    Thornton, Peter E; Doney, Scott C.; Lindsay, Keith; Moore, Jefferson Keith; Mahowald, Natalie; Randerson, James T; Fung, Inez; Lamarque, Jean-Francois H; Feddema, Johan J.

    2009-01-01

    Inclusion of fundamental ecological interactions between carbon and nitrogen cycles in the land component of an atmosphere-ocean general circulation model (AOGCM) leads to decreased carbon uptake associated with CO{sub 2} fertilization, and increased carbon uptake associated with warming of the climate system. The balance of these two opposing effects is to reduce the fraction of anthropogenic CO{sub 2} predicted to be sequestered in land ecosystems. The primary mechanism responsible for increased land carbon storage under radiatively forced climate change is shown to be fertilization of plant growth by increased mineralization of nitrogen directly associated with increased decomposition of soil organic matter under a warming climate, which in this particular model results in a negative gain for the climate-carbon feedback. Estimates for the land and ocean sink fractions of recent anthropogenic emissions are individually within the range of observational estimates, but the combined land plus ocean sink fractions produce an airborne fraction which is too high compared to observations. This bias is likely due in part to an underestimation of the ocean sink fraction. Our results show a significant growth in the airborne fraction of anthropogenic CO{sub 2} emissions over the coming century, attributable in part to a steady decline in the ocean sink fraction. Comparison to experimental studies on the fate of radio-labeled nitrogen tracers in temperate forests indicates that the model representation of competition between plants and microbes for new mineral nitrogen resources is reasonable. Our results suggest a weaker dependence of net land carbon flux on soil moisture changes in tropical regions, and a stronger positive growth response to warming in those regions, than predicted by a similar AOGCM implemented without land carbon-nitrogen interactions. We expect that the between-model uncertainty in predictions of future atmospheric CO{sub 2} concentration and

  14. An Integrated Spatially Dynamic Disturbance and Forest Soil Carbon Model: Preliminary Results from Willow Creek Experimental Forest

    NASA Astrophysics Data System (ADS)

    Scheller, R. M.; Hua, D.; Bolstad, P. V.

    2008-12-01

    Total forest carbon (C) storage is determined by forest succession, multiple interacting disturbances, climate and the edaphic properties of a site or region, including soil texture and depth. How these complex processes interact will determine forest carbon dynamics at landscape and regional scales. We have developed a new succession extension for the LANDIS-II forest landscape simulation model that incorporates the belowground soil C dynamics of the Century soil model. This extension simulates three primary soil organic matter (SOM) pools (fast, slow, passive), litter dynamics, and nitrogen (N) feedbacks to overstory production. The extension was validated against data from the Willow Creek experimental forest in Wisconsin, USA. We subsequently initialized the full model to simulate forest dynamics of 10,000 ha of the surrounding forest landscape. We simulated a representative harvest regime and a historic wind throw regime (50 year wind rotation period, including light, moderate, and extreme events), two common disturbances in mesic forests of the Lake States. We also simulated forest change and total C storage assuming no atmospheric N deposition and N deposition equivalent to 2008 rates. Our results indicate a strong feedback from harvesting to litter C and the fast and slow SOM pools. The passive SOM pool was not significantly altered. Wind disturbance had a negligible effect on all pools. Simulations without N deposition significantly underestimated contemporary forest productivity and the system was more sensitive to disturbances when N deposition was excluded. In conclusion, we have developed a robust model of above and belowground C and N cycling that can readily plug into an existing forest modeling framework to simulate landscape and regional scale forest dynamics and the interactions among forest disturbances, climate change, and soil processes.

  15. Carbon savings resulting from the cooling effect of green areas: a case study in Beijing.

    PubMed

    Lin, Wenqi; Wu, Tinghai; Zhang, Chengguo; Yu, Ting

    2011-01-01

    Green areas cool the climate of a city, reduce the energy consumption caused by the urban heat island (UHI) effect, and bring along carbon savings. However, the calculation of carbon savings due to the cooling effect of green areas is still not well understood. We have used a Landsat Enhanced Thematic Mapper Plus (ETM+) image of Beijing, to identify the cooled areas, compute the possible energy used to maintain the temperature differences between cooled areas and their surrounding heated areas, and calculate the carbon savings owing to the avoidance of energy use. Results show that a total amount of 14315.37 tons carbon savings was achieved in the study area and the amount was related to the biomass, the size and the shape of green areas. These results demonstrate the importance of carbon savings resulting from green areas' cooling effect. PMID:21444136

  16. 78 FR 21107 - Circular Welded Carbon Steel Pipes and Tubes from Turkey: Preliminary Results of Countervailing...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-09

    ... International Trade Administration Circular Welded Carbon Steel Pipes and Tubes from Turkey: Preliminary Results... carbon steel pipes and tubes from Turkey (pipes and tubes from Turkey) for the period of review (POR) of..., of any wall thickness (pipe and tube) from Turkey. These products are currently provided for...

  17. On the heat capacity of elements in WMD regime

    NASA Astrophysics Data System (ADS)

    Hamel, Sebatien

    2014-03-01

    Once thought to get simpler with increasing pressure, elemental systems have been discovered to exhibit complex structures and multiple phases at high pressure. For carbon, QMD/PIMC simulations have been performed and the results are guiding alternative modelling methodologies for constructing a carbon equation-of-state covering the warm dense matter regime. One of the main results of our new QMD/PIMC carbon equation of state is that the decay of the ion-thermal specific heat with temperature is much faster than previously expected. An important question is whether this is only found in carbon and not other element. In this presentation, based on QMD calculations for several elements, we explore trends in the transition from condensed matter to warm dense matter regime.

  18. Stepwise drowning of the urgonian carbonate platform and the sedimentary regime during the Mid-Cretaceous environmental crisis: new evidence from the Helvetic Alps

    NASA Astrophysics Data System (ADS)

    Linder, P.; Weissert, H.; Funk, H.; Föllmi, K. B.

    2003-04-01

    In the region of Anzeindaz (Ct. Vaud, Switzerland) the sedimentary succession of the so-called "Urgonian" of the Schrattenkalk Formation (late Barremian to early Aptian in age) and of the Garschella Formation (early Aptian to late Cenomanian in age) is well developed. These outcrops in the helvetic Morcles nappe are particularly appropriate to study the drowning events that lead to the disappearance of the urgonian carbonate platform and the subsequent development towards a sedimentary regime of condensation and authigenesis. Cavities with infillings of Garschella Formation sediments penetrating the Schrattenkalk limestone up to 20 meters deep are interpreted as karstic erosional cavities and/or neptunian dikes. The most interesting finding was the special way in which the drowning of the urgonian carbonate platform is documented. At one outcrop (La Corde) thin relics of a bed interpreted as the Upper Orbitolina Bed seem to be integrated in the Garschella Formation since it separates relics of at least two phosphoritic beds, probably the Luitere Bed but also an older bed that was not described by Föllmi and Ouwehand (1987). In fact a diploma student at the University of Neuchâtel, François Gainon (2001) just recently rediscovered and correctly interpreted a similar but less condensed succession in the nearby Rawil region that was first described (but misinterpreted) by Schaub (1936). Gainon named this older phosphoritic horizon of the Rawil region "Plaine Morte Bed" and he was able to date it with an ammonite of the earliest Aptian Weissi/Tuarkyricus Zones. In both the Rawil and Anzeindaz regions the whole ensemble is deposited over an erosive unconformity cutting off the Schrattenkalk limestone. The sedimentary succession of the Garschella Formation in the Anzeindaz region contains equivalents of nearly all beds described and defined in the type outcrops of eastern Switzerland and Austria (Föllmi &Ouwehand 1987). The study of these sediments revealed new

  19. Carbon fluxes resulting from land-use changes in the Tamaulipan thornscrub of northeastern Mexico

    PubMed Central

    Návar-Chaidez, Jose de Jesus

    2008-01-01

    Information on carbon stock and flux resulting from land-use changes in subtropical, semi-arid ecosystems are important to understand global carbon flux, yet little data is available. In the Tamaulipan thornscrub forests of northeastern Mexico, biomass components of standing vegetation were estimated from 56 quadrats (200 m2 each). Regional land-use changes and present forest cover, as well as estimates of soil organic carbon from chronosequences, were used to predict carbon stocks and fluxes in this ecosystem. For the period of 1980–1996, the Tamaulipan thornscrub is presenting an annual deforestation rate of 2.27% indicating that approximately 600 km2 of this plant community are lost every year and that 60% of the original Mexican Tamaulipan thornscrub vegetation has been lost since the 1950's. On the other hand, intensive agriculture, including introduced grasslands increased (4,000 km2) from 32 to 42% of the total studied area, largely at the expense of the Tamaulipan thornscrub forests. Land-use changes from Tamaulipan thornscrub forest to agriculture contribute 2.2 Tg to current annual carbon emissions and standing biomass averages 0.24 ± 0.06 Tg, root biomass averages 0.17 ± 0.03 Tg, and soil organic carbon averages 1.80 ± 0.27 Tg. Land-use changes from 1950 to 2000 accounted for Carbon emissions of the order of 180.1 Tg. Projected land-use changes will likely contribute to an additional carbon flux of 98.0 Tg by the year 2100. Practices to conserve sequester, and transfer carbon stocks in semi-arid ecosystems are discussed as a means to reduce carbon flux from deforestation practices. PMID:18826617

  20. Targeting carbonic anhydrase to treat diabetic retinopathy: Emerging evidences and encouraging results

    SciTech Connect

    Weiwei, Zhang; Hu, Renming

    2009-12-18

    Diabetic retinopathy (DR) is the leading cause of vision loss among working-age populations in developed countries. Current treatment options are limited to tight glycemic, blood pressure control and destructive laser surgery. Carbonic anhydrases (CAs) are a group of enzymes involving in the rapid conversion of carbon dioxide to bicarbonate and protons. Emerging evidences reveal CA inhibitors hold the promise for the treatment of DR. This article summarizes encouraging results from clinical and animal studies, and reviews the possible mechanisms.

  1. Modelling fires in the terrestrial carbon balance by incorporating SPITFIRE into the global vegetation model ORCHIDEE - Part 1: Simulating historical global burned area and fire regime

    NASA Astrophysics Data System (ADS)

    Yue, C.; Ciais, P.; Cadule, P.; Thonicke, K.; Archibald, S.; Poulter, B.; Hao, W. M.; Hantson, S.; Mouillot, F.; Friedlingstein, P.; Maignan, F.; Viovy, N.

    2014-04-01

    Fire is an important global ecological process that determines the distribution of biomes, with consequences for carbon, water, and energy budgets. The modelling of fire is critical for understanding its role in both historical and future changes in terrestrial ecosystems and the climate system. This study incorporates the process-based prognostic fire module SPITFIRE into the global vegetation model ORCHIDEE, which was then used to simulate the historical burned area and the fire regime for the 20th century. For 2001-2006, the simulated global spatial extent of fire occurrence agrees well with that given by the satellite-derived burned area datasets (L3JRC, GLOBCARBON, GFED3.1) and captures 78-92% of global total burned area depending on which dataset is used for comparison. The simulated global annual burned area is 329 Mha yr-1, which falls within the range of 287-384 Mha yr-1 given by the three global observation datasets and is close to the 344 Mha yr-1 given by GFED3.1 data when crop fires are excluded. The simulated long-term trends of burned area agree best with the observation data in regions where fire is mainly driven by the climate variation, such as boreal Russia (1920-2009), and the US state of Alaska and Canada (1950-2009). At the global scale, the simulated decadal fire trend over the 20th century is in moderate agreement with the historical reconstruction, possibly because of the uncertainties of past estimates, and because land-use change fires and fire suppression are not explicitly included in the model. Over the globe, the size of large fires (the 95th quantile fire size) is systematically underestimated by the model compared with the fire patch data as reconstructed from MODIS 500 m burned area data. Two case studies of fire size distribution in boreal North America and southern Africa indicate that both the number and the size of big fires are underestimated, which could be related with too low fire spread rate (in the case of static

  2. REgional Carbon Cycle Assessment and Processes: Results and Data Legacy (Invited)

    NASA Astrophysics Data System (ADS)

    Canadell, J.; Ciais, P.

    2013-12-01

    The Global Carbon Project with the involvement of over 150 contributing scientists has finalized the largest and most comprehensive assessment of regional carbon budgets, land and oceans, ever undertaken: the REgional Carbon Cycle Assessment and Processes (RECCAP; http:// www.globalcarbonproject.org/reccap). The objective of RECCAP was to establish the mean carbon balance of 10 land regions (Africa, the Arctic tundra, Australia, Europe, Russia, East Asia, South Asia, Southeast Asia, Central and South America, and North America) and 4 major ocean basins (Atlantic and Arctic, Indian, Pacific, and Southern oceans) for the period 1990-2009. The fundamental tenet of RECCAP was to establish carbon budgets in each region by comparing and reconciling multiple bottom-up flux estimates with top-down estimates. Bottom-up flux approaches include estimates from ensembles of process-based land and ocean models, surface partial pressure of CO2 (pCO2), forest inventories, eddy covariance measurements, fire modeling, riverine export, and wood harvest among others, while top-down estimates relied on model ensembles of atmospheric CO2 and CH4 inversions. In this talk we'll present an overview of results of the various regions, compare with the independently developed global carbon budget, and emphasize major regional differences and data gaps. An important legacy of RECCAP are a number of updated and new databases including an ensemble of 9 Global Dynamic Vegetation Models (TRENDY), 4 Ocean biogeochemical models, and 10 atmospheric CO2 inversions for the period 1990-2009.

  3. Carbon dioxide injection and resultant alteration of Weber Sandstone (Pennsylvanian-Permian), Rangely field, Colorado

    SciTech Connect

    Bowker, K.A.; Shuler, P.J.

    1989-03-01

    Geologic interpretations made during the current EOR (enhanced oil recovery) project at Rangely field (Rio Blanco County, Colorado), have made interesting connections between alteration of reservoir mineralogy and texture, changes in produced water composition, and increased production problems. Carbon dioxide is being injected into the Weber Sandstone in portions of Rangely field. The carbon dioxide injection is part of a very successful tertiary recovery project initiated in late 1986. The bottomhole pH of Weber brine has decreased from approximately 7.5 to 4.5 with the addition of CO/sub 2/. Changes in the chemistry of produced water are associated with alteration of reservoir mineralogy. The CO/sub 2/ flood has caused a substantial increase in the concentrations of iron, calcium, magnesium, and strontium in the produced brine. The amount of increase is directly related to the volume of CO/sub 2/ produced in each well. This increase resulted from the dissolution of carbonate cements, authigenic clays, and detrital feldspars. An increase in the calculated scaling potential of the produced water is a result of this change in chemistry. Hypotheses based on the water-chemistry changes were confirmed in pressure-cell and core-flood experiments. Core-flood experiments also indicate no net change in permeability following carbon dioxide injection: the increase in permeability due to the dissolution of carbonate cements is being offset by a decrease caused by migratory clays plugging pore throats. The clays, which coat the authigenic carbonates, are liberated when the carbonates are dissolved.

  4. Monitoring changes in soil carbon resulting from intensive production, a non-traditional agricultural methodology.

    SciTech Connect

    Dwyer, Brian P.

    2013-03-01

    New Mexico State University and a group of New Mexico farmers are evaluating an innovative agricultural technique they call Intensive Production (IP). In contrast to conventional agricultural practice, IP uses intercropping, green fallowing, application of soil amendments and soil microbial inocula to sequester carbon as plant biomass, resulting in improved soil quality. Sandia National Laboratories role was to identify a non-invasive, cost effective technology to monitor soil carbon changes. A technological review indicated that Laser Induced Breakdown Spectroscopy (LIBS) best met the farmers' objectives. Sandia partnered with Los Alamos National Laboratory (LANL) to analyze farmers' test plots using a portable LIBS developed at LANL. Real-time LIBS field sample analysis was conducted and grab samples were collected for laboratory comparison. The field and laboratory results correlated well implying the strong potential for LIBS as an economical field scale analytical tool for analysis of elements such as carbon, nitrogen, and phosphate.

  5. Results of JET operation with continuous carbon and beryllium X-point target plates

    NASA Astrophysics Data System (ADS)

    Lowry, C. G.; Ady, W. N.; Campbell, D. J.; Carman, P.; Clement, S.; Deksnis, E. B.; Gondhalekar, A.; Harbour, P. J.; Horton, L.; Janeschitz, G.; Lesourd, M.; Lingertat, J.; Pick, M. A.; Saibene, G.; Summers, D. D. R.; Thomas, P. R.

    1992-12-01

    The 1991/92 JET experimental campaign assessed the performance of three different toroidally continuous X-point target plates. The main differences were in the tile material, beryllium and carbon, and the presence of exposed edges. These three configurations have been tested up to power levels in excess of 22 MW and with gas fuelling at the X-point and in the midplane. With the beryllium a radiating divertor was achieved by puffing deuterium into the X-point region, while rapid ELMs resulted from deuterium puffing on the carbon target. The investigation into the importance of small edges, up to 1.5 mm, yielded some interesting results. Although the surface temperature rise was substantially reduced by eliminating exposed tile edges, the onset of the carbon bloom was not delayed by a similar amount. In this paper a model is presented which can explain this and other features of the bloom.

  6. Organic and Elemental Carbon Filter Sets: Preparation Method and Interlaboratory Results

    PubMed Central

    Chai, Ming; Birch, M. Eileen; Deye, Greg

    2012-01-01

    Carbonaceous aerosols play an important role in climate, visibility, air quality, and human health effects, and they have been routinely monitored in workplace and environmental settings. Different thermal analysis methods have been applied to determine the carbon content of carbonaceous aerosols. Good agreement between results for total carbon (TC) generally has been found, but the organic and elemental carbon (OC and EC) fractions determined by different methods often disagree. Measurement uncertainty is mainly due to pyrolysis and charring of OC sample components. Lack of reference materials has impeded progress on method standardization and understanding method biases. A relatively simple method for generating matched filter sets having known OC–EC contents is reported. After generation and analysis of each set to confirm agreement between filters, the filter sets were distributed to six laboratories for an interlaboratory comparison. Analytical results indicate a uniform carbon distribution for the filter sets and good agreement between the participating laboratories. Relative standard deviations (RSDs) for mean TC (OC + EC), OC, and EC results for seven laboratories were <10, 11, and 12% (respectively). Except for one EC result (RSD = 16%), RSDs reported by individual laboratories for TC, OC, and EC were <12%. The method of filter generation is generally applicable and reproducible. Depending on the application, different filter loadings and types of OC materials can be employed. Matched filter sets prepared by the described approach can be used for determining the accuracy of OC–EC methods and thereby contribute to method standardization. PMID:22459320

  7. 75 FR 44766 - Certain Welded Carbon Steel Standard Pipe from Turkey: Final Results of Countervailing Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-29

    ...: Certain Welded Carbon Steel Pipe and Tube Products From Turkey, 51 FR 7984 (March 7, 1986). On April 1...: Preliminary Results of Countervailing Duty Administrative Review, 75 FR 16439 (April 1, 2010) (Preliminary... Countervailing Duty Administrative Review, In Part, 74 FR 47921(September 18, 2009). This administrative...

  8. Patterns and controls of winter carbon dioxide emissions and microbial biomass C and N, in two arctic ecosystem types under varying snow regimes

    NASA Astrophysics Data System (ADS)

    Larsen, K. S.

    2003-04-01

    In a manipulative study, snow fences were put up in sub arctic birch forest and dry heath areas near Abisko, Northern Sweden, increasing the natural snow-cover by 5-35 cm. In early March, CO2 fluxes were 77% and 157% higher in the snow-fenced areas (birch and heath, respectively) and in the snowmelt period from April to May there was a tendency to higher effluxes of CO2 in patches with increased snow-cover. This indicates that small increases in winter snowfall have the potential to increase the CO2 loss substantially from these ecosystems during the off-season. CO2 fluxes integrated over 22 days in April-May at the heath site constituted 8% of growing season net primary production at a nearby heath site, showing that a substantial part of annual CO2 loss may take place during the early spring. In a second study, measurements of CO2 emissions from birch and heath ecosystems situated across a natural snow-cover gradient were performed. The results of this study corroborates with the findings in the snow fence study, showing consistently higher fluxes from sites with higher snow depths. The microbial biomass N and P were determined in both studies and were consistently high in the sub nivean soils compared to summer estimates, indicating that microbes provide a significant buffer limiting the export of mineral nutrients in the snowmelt period. A significant decrease in microbial biomass was observed as plots became snow free at the heath site. Although such decreases have been suggested to be caused by freeze-thaw cycles, this cannot fully explain the observation in this study. The first spring thaw and the transition from constant, sub-zero temperatures and a constant water regime to more variable conditions, and possibly increased grazing by nematodes and protozoans, may also play and important role controlling the microbial population during and after snowmelt.

  9. Carbon sequestration via reaction with basaltic rocks: geochemical modeling and experimental results

    USGS Publications Warehouse

    Rosenbauer, Robert J.; Thomas, Burt; Bischoff, James L.; Palandri, James

    2012-01-01

    Basaltic rocks are potential repositories for sequestering carbon dioxide (CO2) because of their capacity for trapping CO2 in carbonate minerals. We carried out a series of thermodynamic equilibrium models and high pressure experiments, reacting basalt with CO2-charged fluids over a range of conditions from 50 to 200 °C at 300 bar. Results indicate basalt has a high reactivity to CO2 acidified brine. Carbon dioxide is taken up from solution at all temperatures from 50 to 200 °C, 300 bar, but the maximum extent and rate of reaction occurs at 100 °C, 300 bar. Reaction path simulations utilizing the geochemical modeling program CHILLER predicted an equilibrium carbonate alteration assemblage of calcite, magnesite, and siderite, but the only secondary carbonate identified in the experiments was a ferroan magnesite. The amount of uptake at 100 °C, 300 bar ranged from 8% by weight for a typical tholeite to 26% for a picrite. The actual amount of CO2 uptake and extent of rock alteration coincides directly with the magnesium content of the rock suggesting that overall reaction extent is controlled by bulk basalt Mg content. In terms of sequestering CO2, an average basaltic MgO content of 8% is equivalent to 2.6 × 108 metric ton CO2/km3 basalt.

  10. Interactive effects of nitrogen deposition and insect herbivory on carbon and nitrogen dynamics: Results from CENTURY

    NASA Astrophysics Data System (ADS)

    Throop, H. L.; Holland, E. A.; Parton, W. J.; Ojima, D. S.; Keough, C.

    2002-12-01

    The direct effects of nitrogen deposition on nutrient availability in ecosystems have been well studied, however, little is known about the indirect effects of nitrogen deposition on insect herbivory and subsequent changes to ecosystem processes. Numerous empirical studies have demonstrated that host plant nitrogen concentration can strongly affect individual insect consumption rates and population dynamics. We used the CENTURY ecosystem model to explore how interactions between nitrogen deposition and insect herbivory might affect plant production and the pools and fluxes of carbon and nitrogen in an old field community. We modified the preexisting CENTURY mammalian grazing functions to reflect patterns of insect herbivory. Vegetative tissue loss to herbivores was modeled as a dynamic function based on the carbon to nitrogen ratio of aboveground vegetation. Parameterization of the plant response to nitrogen and herbivory was based on field data collected on Ambrosia artemisiifolia (common ragweed, Asteraceae). The modeled response to nitrogen deposition included a strong increase in plant production, decreased plant C:N ratios, and increased soil organic carbon pools. Insect herbivory alone generally caused depressed aboveground production, decreased soil organic carbon pools, and decreased nitrogen mineralization rates. These relationships broke down, however, under moderate nitrogen deposition loads (over 30 kg N ha-1 yr-1) in simulations where insect herbivory increased in response to declining plant C:N. In these cases, herbivory acted to depress the positive influence of nitrogen deposition on carbon storage in soil and vegetative pools and caused strong increases in nitrogen mineralization rates. The results of these simulations suggest that herbivory may play an increasingly important role in affecting ecosystem processes under conditions of high nitrogen deposition. Including effects of herbivory in ecosystem analyses, particularly in systems where rates

  11. Carbon and Water Flux Observations from AmeriFlux and Fluxnet: Some Early Results

    NASA Astrophysics Data System (ADS)

    Law, B. E.

    2001-12-01

    Flux networks provide a means for scientists to make common measurements of carbon, water, and energy exchange, to share advancements in methods, and synthesize results across the network. AmeriFlux objectives are to: Determine how environmental factors and climate regulate ecosystem CO2 and H2O exchange over the short- and long-term, evaluate impacts of anthropogenic factors, and provide data and new understanding for incorporation into models. AmeriFlux is part of the larger international network, Fluxnet. Among Fluxnet sites, we investigated seasonal and annual CO2 and water vapor exchange, and relations with environmental variables to elucidate generalities within and among biomes. The data showed a strong linkage between carbon gain and water loss, with the highest water-use efficiency values for grasslands, and lowest values for tundra. Ecosystem respiration was only weakly correlated with mean annual temperature across biomes, in spite of sensitivity within site over shorter temporal scales. Mean annual temperature and site water balanced explained much of the variation in gross photosynthesis, whereby water availability limits LAI over the long-term, and inter-annual climate variability limits carbon uptake below the potential of the leaf area available for photosynthesis. We compared BIOME-BGC model results among AmeriFlux coniferous forests, and the model showed that variation in net ecosystem carbon exchange (NEE) is mostly a function of disturbance history, with important secondary effects from site climate, ecophysiology, and changing atmospheric CO2 and nitrogen deposition.

  12. 78 FR 71563 - Certain Circular Welded Carbon Steel Pipes and Tubes From Taiwan: Final Results of Antidumping...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-29

    ... International Trade Administration Certain Circular Welded Carbon Steel Pipes and Tubes From Taiwan: Final... administrative review of the antidumping duty order on certain circular welded carbon steel pipes and tubes from... Carbon Steel Pipes and Tubes From Taiwan: Preliminary Results of Antidumping Duty Administrative...

  13. Stable carbon isotope analysis of dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC) in natural waters - Results from a worldwide proficiency test

    NASA Astrophysics Data System (ADS)

    van Geldern, Robert; Verma, Mahendra P.; Carvalho, Matheus C.; Grassa, Fausto; Delgado Huertas, Antonio; Monvoisin, Gael; Barth, Johannes A. C.

    2014-05-01

    Stable carbon isotope ratios of dissolved inorganic (DIC) and organic carbon (DOC) are of particular interest in aquatic geochemistry. The precision for this kind of analysis is typically reported in the range of 0.1 to 0.5‰. To date, no published data attempted a comparison of δ13C measurements of DIC and DOC from for natural water samples among different laboratories. Five natural water sample types (lake water, seawater, two geothermal waters, and petroleum well water) were analyzed for their δ13C-DIC and δ13C-DOC values by 5 laboratories with isotope ratio mass spectrometry (IRMS) in an international proficiency test. Reported δ13C-DIC values for lake water and seawater showed fairly good agreement within a range of about 1‰ whereas geothermal and petroleum waters were characterized by much larger differences of up to 6.6‰ between laboratories. In contrast, δ13C-DOC values were only comparable for seawater and showed differences of 10 to 21‰ for all other samples. This study [1] indicates that scatter in δ13C-DIC isotope data can be in the range of several per mil for samples from extreme environments (geothermal waters) and may not yield reliable information with respect to dissolved carbon (petroleum wells). The analyses of lake water and seawater also revealed a larger than expected difference. Evaluation of analytical procedures of the participating laboratories indicated that the differences cannot be explained by analytical errors or different data normalization procedures and must be related to specific sample characteristics or secondary effects during sample storage and handling. Our results reveal the need for further research on sources of error and on method standardization. References [1] van Geldern, R., Verma, M.P., Carvalho, M.C., Grassa, F., Huertas, A.D., Monvoisin, G. and Barth, J.A.C. (2013): Stable carbon isotope analysis of dissolved inorganic carbon (DIC) and dissolved organic carbon (DOC) in natural waters - Results from a

  14. Preliminary results on estimating permeability characteristics of carbonate rocks using pore microstructures

    NASA Astrophysics Data System (ADS)

    Lee, M.; Keehm, Y.

    2013-12-01

    Direct numerical simulation on pore microstructures from X-ray microtomography is regarded as a good tool to determine and characterize the physical properties of rocks, especially for sandstone. When the same approach is considered for carbonate rocks, we face many difficulties mostly from the heterogeneous nature of carbonates. In this study, we report preliminary results on permeability estimation of carbonate rocks from X-ray tomographic pore microstructures. Since carbonate rocks have quite different types of pore geometry depending on depositional and diagenetic environments, we choose three rock samples with different porosity types: interparticle; vuggy/moldic; and fracture, and obtain high-resolution 3D pore microstructures using X-ray microtomography technique. From the original 3D pore geometry (typically 2,000^3 voxels), we choose various digital sub-blocks to determine local variation and length dependency, and calculate permeability using the Lattice-Boltzmann method. For the interparticle case, the calculated permeability values show very similar trends to clastic sediments, and we can determine a porosity-permeability relation for a given formation as we do with the Koneny-Carman relation. On the other hand, for vuggy or fracture cases, we cannot observe any significant dependence of permeability on porosity. Thus we focus more on the local variation and scale variation of permeability. We perform analyses on percolation probability; local porosity distribution; and direction/length/width of fractures. And we present preliminary conceptual models to determine permeability characteristics. Although the results are from a few limited samples and more detailed researches will be required, our approach will be helpful to estimate and characterize permeability of carbonate rocks, and to investigate scaling and representativeness issues. Acknowledgements: This research was supported by the Basic Research Project of the Korea Institute of Geoscience and

  15. Physiological changes of the lichen Parmotrema tinctorum as result of carbon nanotubes exposition.

    PubMed

    Viana, Camila de O; Vaz, Raissa P; Cano, Abraham; Santos, Adelina P; Cançado, Luiz G; Ladeira, Luiz O; Junior, Ary Corrêa

    2015-10-01

    Carbon nanotubes (CNT) is one of the more abundant nanomaterial produced in the world. Therefore, it is desirable to access its effects in all environment compartments, in order to mitigate environmental distress. This study aims to verify the potential use of lichens - classical atmospheric pollution indicators - as biomonitors of carbon nanotubes aerosols. To examine cause-effect relationships, preserving environmental microclimatic parameters, the lichen Parmotrema tinctorum (Nyl.) Hale was transplanted to open top chambers where aerosols of CNT were daily added. Physiological parameters such as cell viability, photosynthetic efficiency, cell permeability as well as nanoparticle internalization were assessed. Carbon nanotubes exposure led to reduction on the cell viability of P. tinctorum. The treatment with 100µg/mL of MWCNT-COOH resulted in intracellular ion leakage, probably due to changes in membrane permeability. No alterations on photosynthetic efficiency were detected. Carbon nanotubes entrapment and internalization into the lichen thallus were observed. Short term exposition of CNT produced measurable physiological changes in P. tinctorum lichen. This suggests the possibility of use of lichens as models to assess the environmental impact (air related) of engineered nanomaterials. PMID:26057077

  16. Redox freezing and melting in the Earth's deep mantle resulting from carbon-iron redox coupling.

    PubMed

    Rohrbach, Arno; Schmidt, Max W

    2011-04-14

    Very low seismic velocity anomalies in the Earth's mantle may reflect small amounts of melt present in the peridotite matrix, and the onset of melting in the Earth's upper mantle is likely to be triggered by the presence of small amounts of carbonate. Such carbonates stem from subducted oceanic lithosphere in part buried to depths below the 660-kilometre discontinuity and remixed into the mantle. Here we demonstrate that carbonate-induced melting may occur in deeply subducted lithosphere at near-adiabatic temperatures in the Earth's transition zone and lower mantle. We show experimentally that these carbonatite melts are unstable when infiltrating ambient mantle and are reduced to immobile diamond when recycled at depths greater than ∼250 kilometres, where mantle redox conditions are determined by the presence of an (Fe,Ni) metal phase. This 'redox freezing' process leads to diamond-enriched mantle domains in which the Fe(0), resulting from Fe(2+) disproportionation in perovskites and garnet, is consumed but the Fe(3+) preserved. When such carbon-enriched mantle heterogeneities become part of the upwelling mantle, diamond will inevitably react with the Fe(3+) leading to true carbonatite redox melting at ∼660 and ∼250 kilometres depth to form deep-seated melts in the Earth's mantle. PMID:21441908

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

    NASA Technical Reports Server (NTRS)

    Spiers, Gary D.; Menzies, Robert T.

    2008-01-01

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

  18. The anaerobic corrosion of carbon steel in alkaline media - Phase 2 results

    NASA Astrophysics Data System (ADS)

    Smart, N. R.; Rance, A. P.; Fennell, P. A. H.; Kursten, B.

    2013-07-01

    In the Belgian Supercontainer concept a carbon steel overpack will surround high-level waste and spent fuel containers and be encased in a cementitious buffer material. A programme of research was carried out to investigate and measure the rate of anaerobic corrosion of carbon steel in an artificial alkaline porewater that simulates the aqueous phase in the cementitious buffer material. The corrosion rates were measured by monitoring hydrogen evolution using a manometric gas cell technique and by applying electrochemical methods. Phase 2 of the programme has repeated and extended previous Phase 1 measurements of the effects of radiation, temperature and chloride concentration of the anaerobic corrosion rate. This paper provides an update on the results from Phase 2 of the programme. The results confirm previous conclusions that the long-term corrosion rate of carbon steel in alkaline simulated porewater is determined by the formation of a thin barrier layer and a thicker outer layer composed of magnetite. Anaerobic corrosion of steel in cement requires an external supply of water.

  19. OFF-GAS MERCURY CONTROL USING SULFUR-IMPREGNATED ACTIVATED CARBON – TEST RESULTS

    SciTech Connect

    Nick Soelberg

    2007-05-01

    Several laboratory and pilot-scale tests since the year 2000 have included demonstrations of off-gas mercury control using fixed bed, sulfur-impregnated activated carbon. These demonstrations have included operation of carbon beds with gas streams containing a wide range of mercury and other gas species concentrations representing off-gas from several U.S. Department of Energy (DOE) mixed waste treatment processes including electrical resistance heated (joule-heated) glass melters, fluidized bed calciners, and fluidized bed steam reformers. Surrogates of various DOE mixed waste streams (or surrogates of offgas from DOE mixed waste streams) including INL “sodium bearing waste” (SBW), liquid “low activity waste” (LAW) from the Pacific Northwest National Laboratory, and liquid waste from Savannah River National Laboratory (“Tank 48H waste”) have been tested. Test results demonstrate mercury control efficiencies up to 99.999%, high enough to comply with the Hazardous Waste (HWC) Combustor Maximum Achievable Control Technology (MACT) standards even when the uncontrolled off-gas mercury concentrations exceed 400,000 ug/dscm (at 7% O2), and confirm carbon bed design parameters for such high efficiencies. Results of several different pilot-scale and engineering-scale test programs performed over several years are presented and compared.

  20. Purification and sidewall functionalization of multiwalled carbon nanotubes and resulting bioactivity in two macrophage models

    PubMed Central

    Hamilton, Raymond F.; Xiang, Chengcheng; Li, Ming; Ka, Ibrahima; Yang, Feng; Ma, Dongling; Porter, Dale W.; Wu, Nianqiang; Holian, Andrij

    2014-01-01

    This study examined the consequences of surface carboxylation of multiwalled carbon nanotubes (MWCNT) on bioactivity. Since commercial raw MWCNT contain impurities that may affect their bioactivity, HCl refluxing was exploited to purify raw “as-received” MWCNT by removing the amorphous carbon layer on the MWCNT surface and reducing the metal impurities (e.g. Ni). The removal of amorphous carbon layer was confirmed by Raman spectroscopy and thermogravimetric analysis. Furthermore, the HCl-purified MWCNT provided more available reaction sites, leading to enhanced sidewall functionalization. The sidewall of HCl-purified MWCNT was further functionalized with the −COOH moiety by HNO3 oxidation. This process resulted in four distinct MWCNT: raw, purified, −COOH-terminated raw MWCNT, and −COOH-terminated purified MWCNT. Freshly isolated alveolar macrophages from C57Bl/6 mice were exposed to these nanomaterials to determine the effects of the surface chemistry on the bioactivity in terms of cell viability and inflammasome activation. Inflammasome activation was confirmed using inhibitors of cathepsin B and Caspase-1. Purification reduced the cell toxicity and inflammasome activation slightly compared to raw MWCNT. In contrast, functionalization of MWCNT with the −COOH group dramatically reduced the cytotoxicity and inflammasome activation. Similar results were seen using THP-1 cells supporting their potential use for high-throughput screening. This study demonstrated that the toxicity and bioactivity of MWCNT were diminished by removal of the Ni contamination and/or addition of −COOH groups to the sidewalls. PMID:23480196

  1. Early Results from the NASA Orbiting Carbon Observatory-2 (OCO-2)

    NASA Astrophysics Data System (ADS)

    Crisp, David; Eldering, Annmarie

    2015-04-01

    The Orbiting Carbon Observatory-2 (OCO-2) is NASA's first satellite designed to collect the measurements needed to estimate the column-averaged carbon dioxide (CO2) dry air mole fraction, XCO2, with the sensitivity, accuracy, and resolution needed to characterize the CO2 sources and sinks on regional scales over the globe. OCO-2 was successfully launched from Vandenberg Air Force Base in California on July 2, 2014 and joined the 705-km Afternoon Constellation (A-Train) on August 3, 2014. The three-channel imaging grating spectrometer was then cooled to its operating temperatures and a comprehensive series of characterization and calibration activities were initiated. Since early October 2014, the observatory has been routinely collecting almost 1 million soundings over the sunlit hemisphere each day. Early cloud screening results indicate that 15-30% of these measurements may be sufficiently cloud free to yield precise estimates of XCO2. Initial deliveries of calibrated, geo-located OCO-2 spectra to the NASA Goddard Earth Science Data and Information Services Center (GES DISC) began on December 30, 2014. Preliminary estimates of XCO2 retrieved from these data are currently being validated against observations from the Total Carbon Column Observing Network (TCCON) and other standards. Routine deliveries XCO2 and other products, including surface pressure and chlorophyll fluorescence, to the GES DISC are expected to begin before the end of March, 2015. This presentation will summarize the status of the OCO-2 mission and the coverage, resolution, and accuracy of its early results.

  2. Basal insulin regime change from Lantus to Toujeo resulted in fewer hypoglycaemic episodes in a 28-year-old man with diabetes mellitus.

    PubMed

    Shields, Alexandra; Sankaranarayanan, Sailesh

    2016-01-01

    An active 28-year-old man with type 1 diabetes mellitus reported a reduced number of hypoglycaemic episodes following change in basal regime insulin glargine from U100 Lantus to U300 Toujeo. Consequently, an improved quality of life was also reported. Flash-based glucose monitoring was utilised to record 24-hour continuous glucose levels throughout two comparable 60-day periods before and after the change in regimen. Low blood glucose was most likely between 03:00 and 08:00. Nocturnal hypoglycaemic episodes (≤3.9 mmol/L) reduced by an average of 2.5 episodes per week. Severe hypoglycaemic episodes (≤2.9 mmol/L) reduced to an average of 0.4 per week, down from 1.5 per week. Nocturnal hypoglycaemic episodes reduced in frequency and severity. Furthermore, nocturnal hypoglycaemia episodes occurred in a more predictable time window. This was especially important in the reported reduction of impact on the patient's quality of life, as the episodes tended to be associated with anxiety and low mood. Patient education needed to facilitate this change was minimal, and benefits to the patient were great, including decreased sleep disturbances and reduced risk of associated anxiety symptoms. PMID:27307429

  3. Scattering of sulfur ions by carbon: Classical-trajectory Monte Carlo results

    SciTech Connect

    Slabkowska, Katarzyna; Polasik, Marek; Janowicz, Maciej

    2003-01-01

    We analyze classically the scattering of sulfur ions by carbon using the classical-trajectory Monte Carlo method. It is assumed that the scatterer and scattered nuclei are coupled to each other as well as to all electrons, but there is no coupling between electrons themselves. To initialize the state of both atoms, quasiexact energies are used that are obtained from the Dirac-Fock method. Effective charges are used to partially take into account the intra-atomic interactions between electrons. We concentrate on the cross sections for production of vacancies in the K and L shells and capture of electrons to K, L, and M shells of the sulfur ions. The dependence of these cross sections on the energy of the projectile sulfur ions and on the initial charge states of these ions is analyzed. Our results will be helpful in the interpretation of x-ray spectra from highly ionized fast sulfur projectiles passing through a carbon foil.

  4. An investigation into factors affecting the stability of carbons and carbon supported platinum and platinum/cobalt alloy catalysts during 1.2 V potentiostatic hold regimes at a range of temperatures

    NASA Astrophysics Data System (ADS)

    Ball, S. C.; Hudson, S. L.; Thompsett, D.; Theobald, B.

    To meet automotive targets for fuel cell operation and allow higher temperature operation an understanding of the factors affecting carbon and platinum stability is critical. The stability of both carbons and carbon supported platinum and platinum/cobalt alloy catalysts was studied during 1.2 V versus RHE potentiostatic hold tests using carbon and catalyst coated electrodes in a three-chamber wet electrolyte cell at a range of temperatures. At 80 °C the wt% of carbon corroded increases with increasing BET area. Surface oxidation was followed electrochemically using the quinone/hydroquinone redox couple. Increasing temperature, time at 1.2 V and wt% platinum on the carbon increases surface oxidation. Although increasing temperature was shown to increase the extent of carbon corrosion, catalysing the carbon did not significantly change how much carbon was corroded. Platinum stability was investigated by electrochemical metal area loss (ECA). Platinum catalysts on commercial carbons lost more ECA with increasing temperature. A platinum/cobalt alloy on a low surface area carbon was demonstrated to be more stable to both carbon corrosion and metal area loss at temperatures up to 80 °C than platinum catalysts on commercial carbons, making this material an excellent candidate for higher temperature automotive operation.

  5. Reduction of FeO in smelting slags by solid carbon: Experimental results

    NASA Astrophysics Data System (ADS)

    Sarma, B.; Cramb, A. W.; Fruehan, R. J.

    1996-10-01

    The reduction of CaO-SiO2-Al2O3-FeO slags containing less than 10 wt pct FeO by solid carbonaceous materials such as graphite, coke, and coal char was investigated at reaction temperatures of 1400 °C to 1450 °C. The carbon monoxide evolution rate from the system was measured using stationary and rotating carbon rods, stationary horizontal carbon surfaces, and pinned stationary spheres as the reductants. The measured reaction rate ranged from 3.25 × 10-7 mol cm-2 s-1 at 2.1 pct FeO under static conditions to 3.6 × 10-6 mol cm-2 s-1 at 9.5 pct FeO for a rotating rod experiment. Visualization of the experiment using X-ray fluoroscopy showed that gas evolution from the reduction reaction caused the slag to foam during the experiment and that a gas film formed between the carbon surface and the slag at all times during experimentation. The reaction rate increased with increased slag FeO contents under all experimental conditions; however, this variation was not linear with FeO content. The reaction rate also increased with the rotation speed of the carbon rod at a given FeO content. A small increase in the reaction rate, at a given FeO content, was found when horizontal coke surfaces and coke spheres were used as the reductant as compared to graphite and coal char. The results of these experiments do not fit the traditional mass transfer correlations due to the evolution of gas during the experiment. The experimental results are consistent, however, with the hypothesis that liquid phase mass transfer of iron oxide is a major factor in the rate of reduction of iron oxide from slags by carbonaceous materials. In a second article, the individual rates of the possible limiting steps will be compared and a mixed control model will be used to explain the measured reaction rates.

  6. 76 FR 63902 - Circular Welded Carbon Steel Pipes and Tubes From Taiwan: Final Results of Antidumping Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-14

    ... Welded Carbon Steel Pipes and Tubes From Taiwan, 76 FR 33210 (June 8, 2011) (Preliminary Results). This... Circular Welded Carbon Steel Pipes and Tubes From Taiwan: Antidumping Duty Order, 49 FR 19369 (May 7, 1984... section 773(b) of the Tariff Act of 1930, as amended (the Act). See Preliminary Results, 76 FR at...

  7. Advancements for Active Remote Sensing of Carbon Dioxide from Space using the ASCENDS CarbonHawk Experiment Simulator: First Results

    NASA Astrophysics Data System (ADS)

    Obland, M. D.; Nehrir, A. R.; Lin, B.; Harrison, F. W.; Kooi, S. A.; Choi, Y.; Plant, J.; Yang, M. M.; Antill, C.; Campbell, J. F.; Ismail, S.; Browell, E. V.; Meadows, B.; Dobler, J. T.; Zaccheo, T. S.; Moore, B., III; Crowell, S.

    2014-12-01

    The ASCENDS CarbonHawk Experiment Simulator (ACES) is an Intensity-Modulated Continuous-Wave lidar system recently developed at NASA Langley Research Center that seeks to advance technologies and techniques critical to measuring atmospheric column carbon dioxide (CO2) mixing ratios in support of the NASA Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) mission. These advancements include: (1) increasing the power-aperture product to approach ASCENDS mission requirements by implementing multi-aperture telescopes and multiple co-aligned laser transmitters; (2) incorporating high-efficiency, high-power Erbium-Doped Fiber Amplifiers (EDFAs); (3) developing and incorporating a high-bandwidth, low-noise HgCdTe detector and transimpedence amplifier (TIA) subsystem capable of long-duration operation on Global Hawk aircraft, and (4) advancing algorithms for cloud and aerosol discrimination. The ACES instrument architecture is being developed for operation on high-altitude aircraft and will be directly scalable to meet the ASCENDS mission requirements. ACES simultaneously transmits five laser beams: three from commercial EDFAs operating near 1571 nm, and two from the Exelis oxygen (O2) Raman fiber laser amplifier system operating near 1260 nm. The Integrated-Path Differential Absorption (IPDA) lidar approach is used at both wavelengths to independently measure the CO2 and O2 column number densities and retrieve the average column CO2 mixing ratio. The outgoing laser beams are aligned to the field of view of ACES' three fiber-coupled 17.8-cm diameter athermal telescopes. The backscattered light collected by the three telescopes is sent to the detector/TIA subsystem, which has a bandwidth of 4.7 MHz and operates service-free using a tactical dewar and cryocooler. Two key laser modulation approaches are being tested to significantly mitigate the effects of thin clouds on the retrieved CO2 column amounts. Full instrument development concluded in the

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

    USGS Publications Warehouse

    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

  9. Preliminary results of carbon cycling in southwestern ecosystems: Implications for climate change

    SciTech Connect

    Klopatek, C.C. |; Murphy, K.L.; Klopatek, J.M.

    1995-12-31

    By determining the C pool sizes, cycling and relative sequestering rates, the authors intend to estimate the effects of a vegetation change caused by a temperature increase and available moisture decrease. A predominant source of C for the soil compartment is the plant litter and its subsequent decomposition. The resulting effect of temperature and moisture on decomposition will vary according to the biome and litter quality of that biome. Litter quality, referring to the carbon and other nutrient fractions, strongly influences the potential rate of decomposition. The preliminary findings indicate that litter quality and moisture, not temperature, are the major controlling variables in decomposition.

  10. Carbonated Eclogite Solidus Between 14 and 20 GPa: Results from the Model CMAS-CO2 System and Contrasting Solidus Behavior to Carbonated Peridotite

    NASA Astrophysics Data System (ADS)

    Keshav, S.; Gudfinnsson, G. H.

    2007-12-01

    , and magnesite. From average calculated melting reactions along these isobarically univariant curves, stishovite is produced upon melting at all pressures investigated. Significantly, cpx at 14 and 16 GPa and capv at 20 GPa are the dominant contributors toward melt production/composition, in contrast to lower pressures (3-8 GPa) where carbonate dominantly contributes toward melt generation/composition at the solidus. The solidus of model carbonated eclogite at 14, 16, and 20 GPa, lies at 1350, 1450, and 1600 degrees C, respectively, and is nearly linear in P-T space. Melts in equilibrium with all the crystalline phases are highly calcic (Ca no.-0.70), resembling calcio-carbonatites. When magnesite is exhausted from the crystalline assemblage, the melts become slightly less calcic (Ca no.-65). The model carbonated eclogite solidus is always lower than the model carbonated peridotite solidus in the same pressure range. The most remarkable feature of this work is the absence of a drop in the solidus of model carbonated eclogite between 14 and 16 GPa, a result that is in stark contrast to that observed for the model carbonated peridotite at identical pressures. Therefore, even though the solidus temperatures in both carbonated peridotite and eclogite are strongly influenced by the presence of crystalline carbonate, melt compositions and the shape of the solidus in the pressure range investigated seem to be dominantly controlled by the silicate component of the rock in question. Given these results, it is fair to say that a wide range of petrological and geochemical processes operate at these depths in the mantle, and that we have barely scratched the surface in our investigation.

  11. Carbon dioxide removal system for closed loop atmosphere revitalization, candidate sorbents screening and test results

    NASA Astrophysics Data System (ADS)

    Mattox, E. M.; Knox, J. C.; Bardot, D. M.

    2013-05-01

    Due to the difficulty and expense it costs to resupply manned-spacecraft habitats, a goal is to create a closed loop atmosphere revitalization system, in which precious commodities such as oxygen, carbon dioxide, and water are continuously recycled. Our aim is to test other sorbents for their capacity for future spacecraft missions, such as on the Orion spacecraft, or possibly lunar or Mars mission habitats to see if they would be better than the zeolite sorbents on the 4-bed molecular sieve. Some of the materials being tested are currently used for other industry applications. Studying these sorbents for their specific spacecraft application is different from that for applications on earth because in space, there are certain power, mass, and volume limitations that are not as critical on Earth. In manned-spaceflight missions, the sorbents are exposed to a much lower volume fraction of CO2 (0.6% volume CO2) than on Earth. LiLSX was tested for its CO2 capacity in an atmosphere like that of the ISS. Breakthrough tests were run to establish the capacities of these materials at a partial pressure of CO2 that is seen on the ISS. This paper discusses experimental results from benchmark materials, such as results previously obtained from tests on Grade 522, and the forementioned candidate materials for the Carbon Dioxide Removal Assembly (CDRA) system.

  12. Multi-century Changes to Global Climate and Carbon Cycle: Results from a Coupled Climate and Carbon Cycle Model

    SciTech Connect

    Bala, G; Caldeira, K; Mirin, A; Wickett, M; Delire, C

    2005-02-17

    In this paper, we use a coupled climate and carbon cycle model to investigate the global climate and carbon cycle changes out to year 2300 that would occur if CO{sub 2} emissions from all the currently estimated fossil fuel resources were released to the atmosphere. By year 2300, the global climate warms by about 8 K and atmospheric CO{sub 2} reaches 1423 ppmv. The warming is higher than anticipated because the sensitivity to radiative forcing increases as the simulation progresses. In our simulation, the rate of emissions peak at over 30 PgC yr{sup -1} early in the 22nd century. Even at year 2300, nearly 50% of cumulative emissions remain in the atmosphere. In our simulations both soils and living biomass are net carbon sinks throughout the simulation. Despite having relatively low climate sensitivity and strong carbon uptake by the land biosphere, our model projections suggest severe long-term consequences for global climate if all the fossil-fuel carbon is ultimately released to the atmosphere.

  13. Results from the CCSM Carbon-Land Model Intercomparison Project (C-LAMP)

    NASA Astrophysics Data System (ADS)

    Hoffman, F. M.; Randerson, J. T.; Fung, I.; Thornton, P.; Lee, Y. J.; Covey, C. C.

    2007-12-01

    The National Center for Atmospheric Research (NCAR) Community Climate System Model (CCSM) Biogeochemistry Working Group has initiated an intercomparison of terrestrial biosphere models running within the CCSM framework. Called the CCSM Carbon-Land Model Intercomparison Project (C-LAMP), its purpose is to allow the U.S. scientific community to evaluate the performance of biogeochemical cycling models within CCSM and to identify the most important processes for inclusion in future versions of CCSM. Two terrestrial biogeochemistry modules coupled to CCSM---CLM3-CASA' and CLM3-CN---have been evaluated following a set of carefully crafted experiments that build upon the C4MIP Phase 1 protocol. In Experiment 1, the models were forced with an improved NCEP/NCAR reanalysis data set, while in Experiment 2, the models were coupled to the Community Atmosphere Model Version 3 (CAM3) with carbon, water, and energy exchanges over the 20th century. Unlike with most model intercomparisons, for C-LAMP a model performance methodology based on comparison against best-available observational data sets has been developed. Scalar metrics for each model are derived from comparisons against measurements of net primary production, leaf area index, the seasonal cycle of CO2, carbon stocks, and energy. Results from both experiments for CLM3- CASA' and CLM3-CN will be presented, along with recommendations for future evaluations of terrestrial models. C-LAMP model output will be made available by the Program for Climate Model Diagnosis and Intercomparison (PCMDI) via the Earth System Grid (ESG). C-LAMP is a sub-project of the Computational Climate Science End Station headed by Dr. Warren Washington, using computing resources at the U.S. Department of Energy's National Center for Computational Sciences (NCCS).

  14. 78 FR 26748 - Certain Activated Carbon From the People's Republic of China: Preliminary Results of Antidumping...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-08

    ... Notice of Antidumping Duty Order: Certain Activated Carbon from the People's Republic of China, 72 FR... FR 67142 (October 31, 2011); Certain Activated Carbon From the People's Republic of China; 2010-2011... Antidumping Duty Administrative Review, 74 FR 57995 (November 10, 2009); AR4 Carbon, 77 FR at 67339...

  15. 78 FR 21105 - Circular Welded Carbon Steel Pipes and Tubes From Thailand: Preliminary Results of Antidumping...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-09

    ..., available in Antidumping Duty Order: Circular Welded Carbon Steel Pipes and Tubes from Thailand, 51 FR 8341... International Trade Administration Circular Welded Carbon Steel Pipes and Tubes From Thailand: Preliminary... conducting an administrative review of the antidumping duty order on circular welded carbon steel pipes...

  16. 76 FR 77775 - Certain Hot-Rolled Carbon Steel Flat Products From India: Amended Final Results of Countervailing...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-14

    ..., 75 FR 43448 (July 26, 2010) (Final Results), and accompanying Issues and Decision Memorandum. Tata... International Trade Administration Certain Hot-Rolled Carbon Steel Flat Products From India: Amended Final... administrative review of the countervailing duty order on certain ] hot-rolled carbon steel flat products...

  17. 75 FR 80455 - Certain Hot-Rolled Carbon Steel Flat Products From India: Amended Final Results of Countervailing...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-22

    ..., 73 FR 40295 (July 14, 2008) (Final Results), and accompanying Issues and Decision Memorandum (``I&D... International Trade Administration Certain Hot-Rolled Carbon Steel Flat Products From India: Amended Final... administrative review of the countervailing duty order on certain hot-rolled carbon steel flat products...

  18. 76 FR 65179 - Certain Welded Carbon Steel Standard Pipe From Turkey: Extension of Time for Preliminary Results...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-20

    ... Administrative Reviews, 76 FR 23545 (April 27, 2011). The preliminary results are currently due no later than... International Trade Administration Certain Welded Carbon Steel Standard Pipe From Turkey: Extension of Time for... countervailing duty order on certain welded carbon steel standard pipe from Turkey covering the period of...

  19. Cellphone Monitoring of Multi-Qubit Emission Enhancements from Pd-Carbon Plasmonic Nanocavities in Tunable Coupling Regimes with Attomolar Sensitivity.

    PubMed

    Srinivasan, Venkatesh; Manne, Anupam Kumar; Patnaik, Sai Gourang; Ramamurthy, Sai Sathish

    2016-09-01

    We demonstrate for the first time the tuning of qubit emission based on cavity engineering on plasmonic silver thin films. This tunable transition from weak to strong coupling regime in plasmon-coupled fluorescence platform was achieved with the use of palladium nanocomposites. In addition to our recently established correlation between Purcell factor and surface plasmon-coupled emission enhancements, we now show that the qubit-cavity environment experiences the Purcell effect, Casimir force, internal fano resonance, and Rabi splitting. Finite-difference time-domain simulations and time correlated single photon counting studies helped probe the molecular structure of the radiating dipole, rhodamine-6G, in palladium-based nanocavities. The sensitivity of the qubit-cavity mode helped attain a DNA detection limit of 1 aM (attomolar) and multianalyte sensing at picomolar concentration with the use of a smartphone camera and CIE color space. We believe that this low-cost technology will lay the groundwork for mobile phone-based next-gen plasmonic sensing devices. PMID:27529116

  20. Influence of laser hardening and resulting microstructure on fatigue properties of carbon steels

    SciTech Connect

    Cerny, I.; Fuerbacher, I.; Linhart, V.

    1998-06-01

    Cylindrical specimens of a CSN 12050 carbon steel, equivalent to the UNS G 10420 steel, with two different initial microstructures, normalized and heat treated, were surface processed without melting by a 2.5 kW, CO{sub 2} laser to study the effects of laser-beam hardening and resulting microstructure on fatigue properties and mechanisms. Two configurations of circumferential laser passes were made, resulting in one and three separate surface hardened lines, respectively. Fatigue resistance was studied using alternating bend tests. A detailed metallographic study and x-ray measurements of surface stresses were carried out. It was shown that the laser beam hardening under different conditions either reduced or slightly improved the fatigue life.

  1. A global ocean carbon climatology: Results from Global Data Analysis Project (GLODAP)

    SciTech Connect

    Key, Robert; Kozyr, Alexander; Sabine, Chris; Lee, K.; Wanninkhof, R.; Bullister, J.L.; Feely, R. A.; Millero, F. J.; Mordy, C.; Peng, T.-H.

    2004-01-01

    During the 1990s, ocean sampling expeditions were carried out as part of the World Ocean Circulation Experiment (WOCE), the Joint Global Ocean Flux Study (JGOFS), and the Ocean Atmosphere Carbon Exchange Study (OACES). Subsequently, a group of U.S. scientists synthesized the data into easily usable and readily available products. This collaboration is known as the Global Ocean Data Analysis Project (GLODAP). Results were merged into a common format data set, segregated by ocean. For comparison purposes, each ocean data set includes a small number of high-quality historical cruises. The data were subjected to rigorous quality control procedures to eliminate systematic data measurement biases. The calibrated 1990s data were used to estimate anthropogenic CO{sub 2}, potential alkalinity, CFC watermass ages, CFC partial pressure, bomb-produced radiocarbon, and natural radiocarbon. These quantities were merged into the measured data files. The data were used to produce objectively gridded property maps at a 1{sup o} resolution on 33 depth surfaces chosen to match existing climatologies for temperature, salinity, oxygen, and nutrients. The mapped fields are interpreted as an annual mean distribution in spite of the inaccuracy in that assumption. Both the calibrated data and the gridded products are available from the Carbon Dioxide Information Analysis Center. Here we describe the important details of the data treatment and the mapping procedure, and present summary quantities and integrals for the various parameters.

  2. Granular Activated Carbon Treatment May Result in Higher Predicted Genotoxicity in the Presence of Bromide.

    PubMed

    Krasner, Stuart W; Lee, Tiffany Chih Fen; Westerhoff, Paul; Fischer, Natalia; Hanigan, David; Karanfil, Tanju; Beita-Sandí, Wilson; Taylor-Edmonds, Liz; Andrews, Robert C

    2016-09-01

    Certain unregulated disinfection byproducts (DBPs) are more of a health concern than regulated DBPs. Brominated species are typically more cytotoxic and genotoxic than their chlorinated analogs. The impact of granular activated carbon (GAC) on controlling the formation of regulated and selected unregulated DBPs following chlorine disinfection was evaluated. The predicted cyto- and genotoxicity of DBPs was calculated using published potencies based on the comet assay for Chinese hamster ovary cells (assesses the level of DNA strand breaks). Additionally, genotoxicity was measured using the SOS-Chromotest (detects DNA-damaging agents). The class sum concentrations of trihalomethanes, haloacetic acids, and unregulated DBPs, and the SOS genotoxicity followed the breakthrough of dissolved organic carbon (DOC), however the formation of brominated species did not. The bromide/DOC ratio was higher than the influent through much of the breakthrough curve (GAC does not remove bromide), which resulted in elevated brominated DBP concentrations in the effluent. Based on the potency of the haloacetonitriles and halonitromethanes, these nitrogen-containing DBPs were the driving agents of the predicted genotoxicity. GAC treatment of drinking or reclaimed waters with appreciable levels of bromide and dissolved organic nitrogen may not control the formation of unregulated DBPs with higher genotoxicity potencies. PMID:27467860

  3. [Tribological properties of carbon fiber-reinforced plastic. Experimental and clinical results].

    PubMed

    Früh, H J; Ascherl, R; Hipp, E

    1997-02-01

    Wear of the articulating components (especially PE-UHMW) of total hip endoprostheses is the most important technical factor limiting the functional lifetime. To minimize wear debris, ceramic heads, according to ISO 6474 (Al2O3), have been used, from 1969 paired with Al2O3 and since 1975 paired with PE-UHMW. Al2O3 balls articulating with cups made from CFRP have been in clinical use since 1988. Laboratory experiments and in-vivo testing showed minimized wear debris and mild biological response to wear products using CFRP (carbon fiber reinforced plastic) instead of PE-UHMW as the cup material. The articulating surfaces of retrieved ceramic heads (Al2O3-Biolox) and cementless CFRP cups (carbon fiber reinforced plastic, Caproman) were compared using sphericity measurement techniques, scanning electron microscopy (SEM) and roughness measurements (including advanced roughness parameters Rvk or Rpk according to ISO 4287). Altogether, the first results of the clinical study showed that the combination Al2O3-ball/CFRP-cup came up to the expected lower wear rates compared with the conventional combinations. The wear rates are comparable with the combination Al2O3/Al2O3 without the material-related problems of ceramic components in all ceramic combinations. PMID:9157355

  4. Results and Discussion on Physical Property Calculation from Pore Microstructures of Carbonate Rocks

    NASA Astrophysics Data System (ADS)

    Lee, M.; Keehm, Y.

    2014-12-01

    In this paper, we report results and discussion on the physical properties estimation of carbonate rocks using pore microstructures. We obtained high-resolution 3D microstructures with different porosity-types (inter-particle, vuggy/moldic, and fracture) from the X-ray microtomography technique. We calculated permeability, electrical conductivity, and P-wave velocity using the Lattice-Boltzmann method and finite element methods. We also applied the pore-scale simulation techniques to different sub-blocks from the original 3D pore geometry (2,0003 voxels) to determine the heterogeneity of pore geometry. For the inter-particle porosity-type, the calculated transport properties (permeability and electrical conductivity) show very similar trends to clastic sediments. These relations can be modeled by common empirical relations such as Kozeny-Carman relation for porosity-permeability or Archie's equation for porosity-formation factor. For the vuggy or fracture porosity-type, it is difficult to determine any consistent relations; therefore we tried to build conceptual models with cracks or vugs to establish quantitative relations. On the other hand, P-wave velocity showed very little dependence on the porosity-types, due to high frame stiffness of carbonate rocks. Acknowledgements: This research was supported by the Basic Research Project of the Korea Institute of Geoscience and Mineral Resources (KIGAM) funded by the Ministry of Trade, Industry and Energy of Korea (GP2012-029).

  5. Sequential growth of deformation bands in carbonate grainstones in the hangingwall of an active growth fault: Implications for deformation mechanisms in different tectonic regimes

    NASA Astrophysics Data System (ADS)

    Rotevatn, Atle; Thorsheim, Elin; Bastesen, Eivind; Fossmark, Heidi S. S.; Torabi, Anita; Sælen, Gunnar

    2016-09-01

    Deformation bands in porous sandstones have been extensively studied for four decades, whereas comparatively less is known about deformation bands in porous carbonate rocks, particularly in extensional settings. Here, we investigate porous grainstones of the Globigerina Limestone Formation in Malta, which contain several types of deformation bands in the hangingwall of the Maghlaq Fault: (i) bed-parallel pure compaction bands (PCB); (ii) pressure solution-dominated compactive shear bands (SCSB) and iii) cataclasis-dominated compactive shear bands (CCSB). Geometric and kinematic analyses show that the bands formed sequentially in the hangingwall of the evolving Maghlaq growth fault. PCBs formed first due to fault-controlled subsidence and vertical loading; a (semi-)tectonic control on PCB formation is thus documented for the first time in an extensional setting. Pressure solution (dominating SCSBs) and cataclasis (dominating CCSBs) appear to have operated separately, and not in concert. Our findings therefore suggest that, in some carbonate rocks, cataclasis within deformation bands may develop irrespective of whether pressure solution processes are involved. We suggest this may be related to stress state, and that whereas pressure solution is a significant facilitator of grain size reduction in contractional settings, grain size reduction within deformation bands in extensional settings is less dependent on pressure solution processes.

  6. Preliminary Results from the CCSM Carbon-Land Model Intercomparison Project (C- LAMP)

    NASA Astrophysics Data System (ADS)

    Hoffman, F. M.; Fung, I.; Randerson, J.; Thornton, P.; Stöckli, R.; Heinsch, F.; Running, S.; Hibbard, K.; John, J.; Covey, C.; Foley, J.; Post, W. M.; Hargrove, W. W.; Erickson, D. J.; Mahowald, N.

    2006-12-01

    The Biogeochemistry Working Group for the National Center for Atmospheric Research (NCAR) Community Climate System Model (CCSM) has initiated an intercomparison of terrestrial biosphere models running within the CCSM framework. Called the CCSM Carbon-Land Model Intercomparison Project (C-LAMP), its purpose is to allow the U.S. scientific community to evaluate the performance of biogeochemical cycling models within CCSM and to identify the most important processes for inclusion in a biosphere model participating in simulations supporting the IPCC Fifth Assessment Report (AR5). Three terrestrial biogeochemistry modules coupled to CCSM---CLM3-CASA', CLM3-CN, and LSX-IBIS---will be evaluated following a set of carefully crafted experiments that build upon the C4MIP Phase 1 protocol. In Experiment 1, the models will be forced with an improved NCAR/NCAR reanalysis data set, while in Experiment 2, the models will be coupled to the Community Atmosphere Model Version 3 (CAM3) with carbon, water, and energy exchanges over the 20th century. In order to quickly verify and validate the performance of these biogeochemistry models against high quality observations, a set of offline runs for Fluxnet tower sites have been performed using observed meteorology. Certain biogeochemical, hydrological, physiological, and radiation fields have been saved hourly for intercomparison across models and with high frequency tower measurements. An analysis of the offline flux tower runs will be presented along with preliminary results from the global experiments run within the CCSM framework. Model results will be made available by the Program for Climate Model Diagnosis and Intercomparison (PCMDI) via the Earth System Grid (ESG), and this presentation will include an invitation for community participation in the analysis and evaluation of the model results. C-LAMP is a subproject of the Computational Climate Science End Station headed by Dr. Warren Washington, using computing resources at the

  7. Copper Content in Synthetic Copper Carbonate: A Statistical Comparison of Experimental and Expected Results

    NASA Astrophysics Data System (ADS)

    Sheeran, Daniel

    1998-04-01

    This paper describes a general chemistry experiment which was implemented in the 1995-96 academic year and which is based on the preparation of a basic copper(II) carbonate, Cu(OH)2(CO3), and its analysis for copper. Individual results of the copper determination were compiled and a class mean and standard deviation were computed and a frequency plot was constructed for the purpose of comparing class results to the expected result. From a student perspective, the expected result was not Cu(OH)2(CO3), rather it was CuCO3. Students were unaware that they prepared a basic salt, and assumed they prepared CuCO3. This assumption originates in the synthesis which has the appearance of a double displacement reaction. Students expected the copper determination to verify this assumption and were quite surprised when it did not. Statistics was used to reveal the discrepancy between experimental and expected results, and a t-test established that this discrepancy was significant--the prepared material cannot be formulated as CuCO3. The statistical conclusion was further substantiated by observational evidence in the synthesis and analysis steps.

  8. Nano-hillock formation in diamond-like carbon induced by swift heavy projectiles in the electronic stopping regime: Experiments and atomistic simulations

    NASA Astrophysics Data System (ADS)

    Schwen, D.; Bringa, E.; Krauser, J.; Weidinger, A.; Trautmann, C.; Hofsäss, H.

    2012-09-01

    The formation of surface hillocks in diamond-like carbon is studied experimentally and by means of large-scale molecular dynamics simulations with 5 × 106 atoms combined with a thermal spike model. The irradiation experiments with swift heavy ions cover a large electronic stopping range between ˜12 and 72 keV/nm. Both experiments and simulations show that beyond a stopping power threshold, the hillock height increases linearly with the electronic stopping, and agree extremely well assuming an efficiency of approximately 20% in the transfer of electronic energy to the lattice. The simulations also show a transition of sp3 to sp2 bonding along the tracks with the hillocks containing almost no sp3 contribution.

  9. Nano-hillock formation in diamond-like carbon induced by swift heavy projectiles in the electronic stopping regime: Experiments and atomistic simulations

    SciTech Connect

    Schwen, D.; Bringa, E.; Krauser, J.; Weidinger, A.; Trautmann, C.; Hofsaess, H.

    2012-09-10

    The formation of surface hillocks in diamond-like carbon is studied experimentally and by means of large-scale molecular dynamics simulations with 5 Multiplication-Sign 10{sup 6} atoms combined with a thermal spike model. The irradiation experiments with swift heavy ions cover a large electronic stopping range between {approx}12 and 72 keV/nm. Both experiments and simulations show that beyond a stopping power threshold, the hillock height increases linearly with the electronic stopping, and agree extremely well assuming an efficiency of approximately 20% in the transfer of electronic energy to the lattice. The simulations also show a transition of sp{sup 3} to sp{sup 2} bonding along the tracks with the hillocks containing almost no sp{sup 3} contribution.

  10. Radiative Forcing associated with Particulate Carbon Emissions resulting from the Use of Mercury Control Technology

    NASA Astrophysics Data System (ADS)

    Clack, H.; Penner, J. E.; Lin, G.

    2013-12-01

    Mercury is a persistent, toxic metal that bio-accumulates within the food web and causes neurological damage and fetal defects in humans. The U.S. was the first country to regulate the leading anthropogenic source of mercury into the atmosphere: coal combustion for electric power generation. The U.S. EPA's 2005 Clean Air Mercury Rule (CAMR) was replaced and further tightened in 2012 by the Mercury and Air Toxics Standard (MATS), which required existing coal-fired utilities to reduce their mercury emissions by approximately 90% by 2015. Outside the U.S., the Governing Council of the United Nations Environment Programme (UNEP) has passed the legally binding Minamata global mercury treaty that compels its signatory countries to prevent and reduce the emission and release of mercury. The most mature technology for controlling mercury emissions from coal combustion is the injection into the flue gas of powdered activated carbon (PAC) adsorbents having chemically treated surfaces designed to rapidly oxidize and adsorb mercury. However, such PAC is known to have electrical properties that make it difficult to remove from flue gas via electrostatic precipitation, by far the most common particulate control technology used in countries such as the U.S., India, and China which rely heavily on coal for power generation. As a result, PAC used to control mercury emissions can be emitted into the atmosphere, the sub-micron fraction of which may result in unintended radiative forcing similar to black carbon (BC). Here, we estimate the potential increases in secondary BC emissions, those not produced from combustion but arising instead from the use of injected PAC for mercury emission reduction. We also calculate the radiative forcing associated with these secondary BC emissions by using a global atmospheric chemical transport model coupled with a radiative transfer model.

  11. Toward biologically meaningful net carbon exchange estimates for tall, dense canopies: multi-level eddy covariance observations and canopy coupling regimes in a mature Douglas-fir forest in Oregon

    NASA Astrophysics Data System (ADS)

    Thomas, C. K.; Martin, J.; Law, B. E.

    2012-12-01

    We sought to improve net ecosystem exchange (NEE) estimates for a tall, dense, mature Douglas-Fir forest in the Oregon Coast range located in moderately complex terrain and characterized by weak flows, directional shear, and limited turbulent mixing throughout the diurnal period. We used eddy covariance (EC) observations at two levels and concurrent biological measurements of carbon and water fluxes collected over a period of 6 years (2006-2011) to develop and test a conceptual framework with the goal of i) reducing uncertainty by retaining more measurements for the computation of annual NEE estimates, and ii) producing defendable and biologically meaningful NEE estimates by accounting for the missing sub-canopy respiration due to the weak turbulence. The framework assumes that the scalar exchange between vertical layers can be categorized into discrete canopy coupling regimes, and that advection leads to a systematic loss of scalar from the observational volume that can indirectly be estimated and accounted for as sub-canopy respiration flux when canopy layers are decoupled. The standard deviation of the vertical velocity variance was the most adequate proxy for turbulent mixing strength. It allowed for straight-forward estimation of thresholds used to delineate the exchange regimes and was more sensitive to directional shear and other mechanisms enhancing the mixing. Periods with a decoupled sub-canopy layer dominated and occupied 65 and 88 % of the day- and nighttime periods, respectively. Annual NEE derived from the new framework was estimated as 480 gC m-2 yr-1, which was reduced by 620 gC m-2 yr-1 compared to traditional estimates from single-level EC data filtered using a critical friction velocity. The reduction in NEE was caused by an enhanced ecosystem respiration (ER), while gross ecosystem productivity remained unchanged. Improved ER estimates agreed well with those from independent biological estimates including soil, stem, and foliage respiration

  12. Field-aligned magnetohydrodynamic bow shock flows in the switch-on regime. Parameter study of the flow around a cylinder and results for the axi-symmetrical flow over a sphere

    NASA Astrophysics Data System (ADS)

    de Sterck, H.; Poedts, S.

    1999-03-01

    A parameter study is undertaken for steady symmetrical planar field-aligned MHD bow shock flows around a perfectly conducting cylinder. For sets of values of the inflow plasma beta and Alfvénic Mach number (MA) which allow for switch-on shocks, a numerical solution is obtained which exhibits a complex bow shock shape and topology with multiple shock fronts and a dimpled leading front. For parameter values outside the switch-on domain, a classical single-front bow shock flow is obtained. These results show that the beta and MA parameter regime for which the complex bow shock topology occurs, corresponds closely to the parameter regime for which switch-on shocks are possible. The axi-symmetrical field-aligned bow shock flow over a perfectly conducting sphere is then calculated for one set of values for beta and MA in the switch-on domain, resulting in a complex bow shock topology similar to the topology of the flow around a cylinder. These complex shock shapes and topologies may be encountered in low-beta space plasmas. Fast coronal mass ejections moving away from the sun in the low-beta inner corona may induce preceding shock fronts with upstream parameters in the switch-on domain. Planetary and cometary bow shocks may have upstream parameters in the switch-on domain when the impinging solar wind occasionally becomes low-beta . The simulation results may be important for phenomena in the Earth's magnetosheath.

  13. 75 FR 62366 - Circular Welded Carbon Steel Pipes and Tubes From Taiwan: Final Results of Antidumping Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-08

    ... Welded Carbon Steel ] Pipes and Tubes From Taiwan, 75 FR 32911 (June 10, 2010) (Preliminary Results...) of the Act. See Preliminary Results, 75 FR at 32913. Those results apply to these final results... accordance with section 773(a)(4) of the Act. See Preliminary Results, 75 FR 32913. Analysis of...

  14. Nanosized carbon coating formed on different surfaces at the result of carbon emission from graphite under millisecond pulses of glass: Yb, Er laser

    NASA Astrophysics Data System (ADS)

    Zulina, N. A.; Belikov, A. V.; Skrypnik, A. V.

    2013-11-01

    Possibility of nanosized carbon coatings synthesis on metal and dielectric surfaces at the result of carbon emission from different impurity amount graphite materials under millisecond pulses of Glass: Yb, Er laser. Size of particles and morphology of obtained coatings were investigated with scanning electron microscopy. It was found experimentally, that separated particles of obtained carbon coating has a size about 50-100 nm. Also Raman spectras of nanosized carbon coatings were obtained to investigate a structure. At the result of Raman spectras analysis was found, that coatings are contained of different structural units depends on graphite material impurity amount. For graphite material 99.9% products of laser evaporation are amorphous carbon nanoparticles, and for graphite material with impurity amount about 30% - graphitized nanoparticles. In this article mechanical properties, such as microhardness, of obtained coatings were estimated. It is shown that microhardness of metal surfaces and surface of substrates prepared from human tooth enamel and dentin could be increased significantly due to nanosized carbon coating. Also for tooth enamel and dentin substrates was observed an ability to increase its acid resistance and protective property of obtained coatings to the action of phosphic acid (37.5%).

  15. A Terrestrial Ecosystem Full Verified Carbon Accounting for Russian Land: Results and Uncertainty

    NASA Astrophysics Data System (ADS)

    Shvidenko, A.; Schepaschenko, D.; Maksyutov, S.

    2010-12-01

    We present a terrestrial full carbon account (FCA) for Russian land in a spatially explicit form for 2009 and aggregated country-wide annual estimates for 2004-2008. The integrated methodology of the FCA takes into account the fuzzy character of the studied systems. IIASA’s landscape-ecosystem approach (LEA) is used for designing the account boundaries and assessment of major pools and fluxes. An Integrated Land Information System (ILIS) serves as the information background of the FCA. The ILIS is based on a system integration of all available ground data and multi-sensor remote sensing applications. The ILIS includes a georeferenced hybrid land cover (~500 land classes, resolution 1 x 1 km), corresponding attributive datasets and sets of empirical and semi-empirical ecosystem and landscape models. The latter are based on long-period measurements of ecological parameters with corrections - if necessary - due to weather specifics of individual growth seasons. On average, terrestrial ecosystems of Russia served as a sink of roughly 0.6 Pg C yr-1 during the last five years which exceeds the technosphere’s emissions of the country by about one third. Two major fluxes (net primary production and heterotrophic respiration) for all productive lands of the country are estimated at 323 and 204 g C yr-1 m-2, respectively. Disturbance and consumption of plant products comprise from 15 to 20% of the net primary production. Forests serve as a major component of the sink (~85% of the country’s total). Disturbed forests and peatlands, as well as cultivated agricultural lands, are a relatively small carbon source. The interannual variability of the net ecosystem carbon balance are mostly driven by climatic conditions and natural disturbance (fire, insects) of the growth periods and is in limits of 10-15% for the country as a whole, but could exceed 25-30% for large regions with weather anomalies of the vegetation periods. Uncertainty within the LEA was assessed for all

  16. Woody plant encroachment effect on soil organic carbon dynamics: results from a latitudinal gradient in Italy

    NASA Astrophysics Data System (ADS)

    Pellis, Guido; Chiti, Tommaso; Moscatelli, Maria Cristina; Marinari, Sara; Papale, Dario

    2016-04-01

    Woody plant encroachment into pastures and grasslands represents a significant land cover change phenomenon, with a considerable impact on carbon dynamics at an ecosystem level. It was estimated that 7.64% of the Southern Europe land was subject to that process between 1950 to 2010. As a result of woody encroachment, changes in vegetation composition can produce substantial changes to the soil organic carbon (SOC) cycle. Despite the numerous papers published on land-use change, an evaluation of the IPCC terrestrial carbon pools changes occurring during woody encroachment on abandoned pastures and grasslands is still lacking, particularly for the Italian territory. Therefore, the aim of this study was to investigate the role of woody encroachment on carbon sequestration over abandoned pastures and grasslands in Alpine and Apennine ecosystems, with a particular focus on the SOC. We applied a chronosequence approach to seven selected sites located along a latitudinal gradient in Italy. Each chronosequence consisted of a pasture currently managed, three sites abandoned at different times in the past and, finally, a mature forest stand representing the last phase of the succession. The European Commission sampling protocols to certify SOC changes was adopted to estimate the variations following woody encroachment. Soil samples were collected at different depths in the topsoil (0-30 cm) and subsoil (30-70 cm), despite the original protocol formulation being limited to the topsoil only. In addition, aboveground living biomass (AGB), dead wood and litter were also measured following international protocols. Considering all C pools together, woody plant encroachment leads to a progressive C stock accumulation in all the chronosequences. The total C stock of mature forest stands ranges from 1.78±0.11 times (Eastern Alps) to 2.48±0.31 times (central Apennine) the initial value on pastures. Unsurprisingly, the C stocks of AGB, dead wood and litter all increase during the

  17. 76 FR 45509 - Final Results of Antidumping Duty Changed Circumstances Review: Carbon and Certain Alloy Steel...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-29

    ... Circumstances Review: Carbon and Certain Alloy Steel Wire Rod from Mexico, 75 FR 67685 (November 3, 2010... of the Antidumping Duty and Countervailing Duty Orders, and Intent To Revoke Orders in Part, 68 FR...: Carbon and Certain Alloy Steel Wire Rod From Mexico, 71 FR 27989 (May 15, 2006). Notification This...

  18. 77 FR 19623 - Certain Welded Carbon Steel Standard Pipe from Turkey: Preliminary Results of Countervailing Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-04-02

    ... Pipe and Tube Products from Turkey, 51 FR 7984 (March 7, 1986). \\2\\ See Antidumping or Countervailing... certain welded carbon steel pipe and tube with an outside diameter of 0.375 inch or more, but not over 16...: Certain Welded Carbon Steel Standard Pipe from Turkey, 72 FR 62837, 62838 (November 7, 2007) (Turkey...

  19. 75 FR 16439 - Certain Welded Carbon Steel Standard Pipe From Turkey: Preliminary Results of Countervailing Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

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    ... Steel Pipe and Tube Products from Turkey, 51 FR 7984 (March 7, 1986). On March 2, 2009, the Department... products covered by this order are certain welded carbon steel pipe and tube with an outside diameter of 0... Administrative Review: Certain Welded Carbon Steel Standard Pipe from Turkey, 72 FR 62837, 62838 (November...

  20. 78 FR 34335 - Certain Circular Welded Carbon Steel Pipes and Tubes From Taiwan: Preliminary Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-07

    ... Steel Pipes and Tubes From Taiwan: Antidumping Duty Order, 49 FR 19369 (May 7, 1984). These cash deposit... International Trade Administration Certain Circular Welded Carbon Steel Pipes and Tubes From Taiwan: Preliminary... conducting an administrative review of the antidumping duty order on certain circular welded carbon...

  1. Incorporation of inorganic carbon by Antarctic cryptoendolithic fungi

    NASA Technical Reports Server (NTRS)

    Palmer, R. J. Jr; Friedmann, E. I.

    1988-01-01

    Fungi isolated from the cryptoendolithic community of the Ross Desert are capable of fixing inorganic carbon. Results suggest that lichen mycobionts and parasymbionts are adapted to different water regimes in the cryptoendolithic environment.

  2. Divergent trajectories in tropical rainforest carbon-climate relationships: results from a new tropical forest carbon inventory database

    NASA Astrophysics Data System (ADS)

    Taylor, P.; Wieder, W.; Townsend, A.; Asner, G. P.; Cleveland, C.; Loarie, S.

    2010-12-01

    Intact tropical rainforests play a disproportionate role in the terrestrial carbon (C) cycle because they exchange more CO2 with the atmosphere than any other biome. As with any ecosystem, climate controls rates of C uptake and storage; however, the specific nature of climate-carbon relationships in the tropics remains poorly understood and oft-debated. Consequently, there are major uncertainties in how human-driven climate change may alter tropical C storage. One way to investigate climate - forest C interactions is via meta-analyses that examine shifts in forest C dynamics along climatic gradients. Past such analyses for the role of precipitation suggest tropical aboveground net primary production (ANPP) peaks near 2500 mm/yr, and then sharply declines in wetter regions. However, the downturn in ANPP is driven by a bias in early databases toward montane forests, which may exhibit temperature-driven biogeochemical feedbacks not present in wet lowland forests. To address this possibility, we assembled a tropical forest carbon dynamics database that includes nearly 900 different sites. We found substantial divergence in montane versus lowland forest ANPP responses to shifts in rainfall. As previous analyses imply, montane forest ANPP shows a distinct “hump-shaped” pattern, with a downturn in wetter sites. However, in contrast to prevailing assumptions, we find that lowland forest ANPP and biomass remain steady or increase with increasing rainfall. The data suggest that temperature plays a key role in determining the shape of rainfall - forest C interactions by regulating plant-soil nutrient feedbacks that underlie trends in ANPP. In montane systems, lower temperatures under wet conditions allow the development of organic horizons and the persistence of low redox conditions that reduce fertility, but in lowland systems, higher temperatures prevent organic matter accumulation, and high precipitation appears to drive rapid exchanges of nutrients between litter and

  3. An intercomparison of carbon monoxide, nitric oxide, and hydroxyl measurement techniques - Overview of results

    NASA Technical Reports Server (NTRS)

    Hoell, J. M.; Gregory, G. L.; Carroll, M. A.; Mcfarland, M.; Ridley, B. A.; Davis, D. D.; Bradshaw, J.; Rodgers, M. O.; Torres, A. L.; Condon, E. P.

    1984-01-01

    Results from an intercomparison of methods to measure carbon monoxide (CO), nitric oxide (NO), and the hydroxyl radical (OH) are discussed. The intercomparison was conducted at Wallops Island, Virginia, in July 1983 and included a laser differential absorption and three grab sample/gas chromatograph methods for CO, a laser-induced fluorescence (LIF) and two chemiluminescence methods for NO, and two LIF methods and a radiocarbon tracer method for OH. The intercomparison was conducted as a field measurement program involving ambient measurements of CO (150-300 ppbv) and NO (10-180 pptv) from a common manifold with controlled injection of CO in incremental steps from 20 to 500 ppbv and NO in steps from 10 to 220 pptv. Only ambient measurements of OH were made. The agreement between the techniques was on the order of 14 percent for CO and 17 percent for NO. Hardware difficulties during the OH tests resulted in a data base with insufficient data and uncertanties too large to permit a meaningful intercomposition.

  4. CO2-brine-mineral Reactions in Geological Carbon Storage: Results from an EOR Experiment

    NASA Astrophysics Data System (ADS)

    Chapman, H.; Wigley, M.; Bickle, M.; Kampman, N.; Dubacq, B.; Galy, A.; Ballentine, C.; Zhou, Z.

    2012-04-01

    Dissolution of CO2 in brines and reactions of the acid brines ultimately dissolving silicate minerals and precipitating carbonate minerals are the prime long-term mechanisms for stabilising the light supercritical CO2 in geological carbon storage. However the rates of dissolution are very uncertain as they are likely to depend on the heterogeneity of the flow of CO2, the possibility of convective instability of the denser CO2-saturated brines and on fluid-mineral reactions which buffer brine acidity. We report the results of sampling brines and gases during a phase of CO2 injection for enhanced oil recovery in a small oil field. Brines and gases were sampled at production wells daily for 3 months after initiation of CO2 injection and again for two weeks after 5 months. Noble gas isotopic spikes were detected at producing wells within days of initial CO2 injection but signals continued for weeks, and at some producers for the duration of the sampling period, attesting to the complexity of gas-species pathways. Interpretations are complicated by the previous history of the oil field and re-injection of produced water prior to injection of CO2. However water sampled from some producing wells during the phase of CO2 injection showed monotonic increases in alkalinity and in concentrations of major cations to levels in excess of those in the injected water. The marked increase in Na, and smaller increases in Ca, Mg, Si, K and Sr are interpreted primarily to result from silicate dissolution as the lack of increase in S and Cl concentrations preclude additions of more saline waters. Early calcite dissolution was followed by re-precipitation. 87Sr/86Sr ratios in the waters apparently exceed the 87Sr/86Sr ratios of acetic and hydrochloric acid leaches of carbonate fractions of the reservoir rocks and the silicate residues from the leaching. This may indicate incongruent dissolution of Sr or larger scale isotopic heterogeneity of the reservoir. This is being investigated

  5. CO2-brine-mineral Reactions in Geological Carbon Storage: Results from an EOR Experiment

    NASA Astrophysics Data System (ADS)

    Bickle, M. J.; Chapman, H.; Galy, A.; Kampman, N.; Dubacq, B.; Ballentine, C. J.; Zhou, Z.; Members Of The Crius Project

    2011-12-01

    Dissolution of CO2 in brines is a prime mechanism for stabilising the light supercritical CO2 in geological carbon storage. However the rates of dissolution are very uncertain as they likely depend on the heterogeneity of the flow of CO2, the possibility of convective instability of the denser CO2-saturated brines and on fluid-mineral reactions which buffer brine acidity. We report the results of sampling brines and gases during a phase of CO2 injection for enhanced oil recovery in a small oil field. The injected CO2 was spiked with isotopically enriched noble gases at the start of injection. Brines and gases were sampled at production wells daily for 3 months after initiation of CO2 injection and again for two weeks after 5 months. The noble gas spikes were detected at producing wells within days of injection but signals continued for weeks, and at some producers for the duration of the sampling period, attesting to the complexity of gas-species pathways. Interpretation of the water chemistry is complicated by the previous history of the oil field and re-injection of produced water prior to injection of CO2. However water sampled from some producing wells during the phase of CO2 injection showed monotonic increases in alkalinity and in concentrations of major cations to levels in excess of those in the injected water. The marked increase in Na, and smaller increases in Ca, Mg, Si, K and Sr are interpreted primarily to result from silicate dissolution with either dissolution or precipitation of calcite. The precipitation of calcite driven by the rise in pH consequent on dissolution of silicates is as predicted by previous modelling (Knaus et al., 2005, Chemical Geology) and as observed in natural analogue systems (Kampman et al., 2009, Earth Planetary Science Letters). A key question is the extent to which the rates of dissolution are controlled by the surface reaction rates of the minerals versus the rate at which CO2 can dissolve in formation brines. Simple flow

  6. Does Iron Fertilization Lead to Enhanced Carbon Sequestration? A Synthesis of Polar Star Results.

    SciTech Connect

    Buesseler, K.O.

    2002-12-01

    This research synthesized activities related to work conducted as part of the Southern Ocean Iron Experiment (SOFeX) which investigated the effects of iron fertilization on enhanced carbon sequestration. The primary interest was in the fate of sinking particles which carry carbon to the deep ocean, where it can be sequestered from the atmosphere for >100-1000 year time scales. This was accomplished through direct measurements of thorium-234, a naturally occurring particle reactive radionuclide that traces shallow particle export; SF6 measurements to track the position of the Fe fertilized region; and the collection of ancillary data and samples to augment the study of major C, nutrient and elemental budgets as well as appropriate samples for biological study. Results of this work show a small, but progressively increasing flux of particulate organic C to depth as a consequence of Fe fertilization. This is the first data set to show any effect of Fe fertilization on C sequestration in the Southern Ocean. The changes in particle export during SOFeX are significant, but only possible to detect given what is arguably the largest 234Th data set ever collected as part of an oceanographic experiment. Most prior 234Th studies, simply use a steady-state approximation and ignore advective and diffusive fluxes in the calculation of 234Th fluxes. High resolution time-series of average 0-50m 234Th activities in and out of the Southern patch find a clear steady decrease in 234Th flux that is slightly larger in vs. out of the Fe fertilized patch. This decrease must be included in the full 234Th flux calculation and the deliberate tagging of this water mass with SF6 combined with time-series sampling allowed for a careful evaluation of this non-steady state (NSS) term. Likewise, the addition of SF6 allows for the evaluation of vertical exchange (via the gradient of SF6 below the patch) and dilution effects (after correction for atmospheric losses). In most set tings these physical

  7. A dense Black Carbon network in the region of Paris, France: Implementation, objectives, and first results

    NASA Astrophysics Data System (ADS)

    Sciare, Jean; Petit, Jean-Eudes; Sarda-Esteve, Roland; Bonnaire, Nicolas; Gros, Valérie; Pernot, Pierre; Ghersi, Véronique; Ampe, Christophe; Songeur, Charlotte; Brugge, Benjamin; Debert, Christophe; Favez, Olivier; Le Priol, Tiphaine; Mocnik, Grisa

    2013-04-01

    Motivations. Road traffic and domestic wood burning emissions are two major contributors of particulate pollution in our cities. These two sources emit ultra-fine, soot containing, particles in the atmosphere, affecting health adversely, increasing morbidity and mortality from cardiovascular and respiratory conditions and casing lung cancer. A better characterization of soot containing aerosol sources in our major cities provides useful information for policy makers for assessment, implementation and monitoring of strategies to tackle air pollution issues affecting human health with additional benefits for climate change. Objectives. This study on local sources of primary Particulate Matter (PM) in the megacity of Paris is a follow-up of several programs (incl. EU-FP7-MEGAPOLI) that have shown that fine PM - in the Paris background atmosphere - is mostly secondary and imported. A network of 14 stations of Black Carbon has been implemented in the larger region of Paris to provide highly spatially resolved long term survey of local combustion aerosols. To our best knowledge, this is the first time that such densely BC network is operating over a large urban area, providing novel information on the spatial/temporal distribution of combustion aerosols within a post-industrialized megacity. Experimental. As part of the PRIMEQUAL "PREQUALIF" project, a dense Black Carbon network (of 14 stations) has been installed over the city of Paris beginning of 2012 in order to produce spatially resolved Equivalent Black Carbon (EBC) concentration maps with high time resolution through modeling and data assimilation. This network is composed of various real-time instruments (Multi-Angle Absorption Photometer, MAAP by THERMO; Multi-wavelength Aethalometers by MAGEE Scientific) implemented in contrasted sites (rural background, urban background, traffic) complementing the regulated measurements (PM, NOx) in the local air quality network AIRPARIF (http

  8. On unstable periodic regime of small HAWT

    NASA Astrophysics Data System (ADS)

    Dosaev, Marat Z.; Klimina, Liubov A.; Selyutskiy, Yury D.; Tsai, Mi-Ching; Yang, Hong-Tzer

    2012-11-01

    Dynamics of a small HAWT is studied. The closed mathematical model involving phenomenological description of both aerodynamic load upon turbine blades and permanent magnet electric generator is developed, in order to take into account the inductive reactance of the electric circuit. A series of experiments is performed in the subsonic wind tunnel of the LMSU Institute of Mechanics that allowed verifying the model and identifying its parameters. Parameters of dynamic model are identified, such as the coefficient of electromechanical interaction, the active internal resistance of generator, the circuit reactance. Parametric analysis of steady regimes is performed. The model prediction that HAWT operating dynamic system has two stable steady regimes (high speed regime and low speed one) is confirmed by experiments. Transient regimes are registered depending on parameters of the system, which allows estimating the unstable steady regime. The characteristics of the unstable regime are experimentally determined. Obtained results are used for estimation of aerodynamic moment acting on HAWT blades.

  9. Carbon cycling in a rapidly changing High Arctic: Results from long-term climate experiments and observations of interannual variability in NW Greenland

    NASA Astrophysics Data System (ADS)

    Czimczik, C. I.; Lupascu, M.; Csank, A. Z.; Seibt, U. H.; Maseyk, K. S.; Xu, X.; Welker, J. M.

    2013-12-01

    The High Arctic, a region dominated by polar semi-deserts underlain with continuous permafrost, is experiencing dramatic changes in climate associated with the loss of sea ice, including warming and shifts in precipitation regimes (i.e. wetting and changing snow cover). Here, we present findings from a set of studies that are addressing the sign and strength of the High Arctic's summertime carbon (C) cycle feedback. We explored magnitudes, patterns and sources of C losses through CO2 and CH4 fluxes and via leaching as dissolved organic C (DOC) and particulate organic C (POC) along with measurements of net ecosystem exchange and plant C uptake. From studying long-term summertime experimental warming and/or watering and interannual weather patterns we find that in polar semi-deserts: a) Summer precipitation regime is the key driver of current summertime C budgets. Warming plus wetting results in increased ecosystem C sequestration and reduced losses of older C as CO2, while warming alone decreases C uptake and increases losses of older soil C as CO2. The system is a sink for CH4, but the sink strength will decline with increasing soil moisture. Thus, the High Arctic has the potential to remain a strong summertime C sink even as the rest of the permafrost region transitions to a net C source to the atmosphere as climate continues to warm. b) Old C is diffusing out of the High Arctic landscape into the atmosphere. This C loss is especially evident in the spring before vegetation pumps fresh C into the soil system. Further, loss of older C from the deeper active layer is highly episodic and dominates C emissions during small precipitation events. c) Precipitation regime is also the key driver of that ancient C export from the land surface as DOC, higher precipitation in the later part of the growing season (July-August), when the active layer is deeper, results in a greater fraction of old C transported to the nearshore Arctic Ocean. Collectively these findings

  10. 75 FR 64696 - Circular Welded Carbon Steel Pipes and Tubes From Thailand: Final Results of Antidumping Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-20

    ... Carbon Steel Pipes and Tubes from Thailand: Final Determination of Sales at Less Than Fair Value, 51 FR... Administrative Review, 75 FR 18788 (April 13, 2010) (Preliminary Results). In the Preliminary Results, the...: Extension of Time Limit for Final Results of Antidumping Duty Administrative Review, 75 FR 28557 (May...

  11. 78 FR 64916 - Circular Welded Carbon Steel Pipes and Tubes From Turkey: Final Results of Countervailing Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-30

    ... Review; Calendar Year 2011, 78 FR 21107 (April 9, 2013) (Preliminary Results). \\2\\ See Decision..., 51 FR 7984 (March 7, 1986). \\4\\ See Preliminary Results. \\5\\ Petitioners in this review are Wheatland... International Trade Administration Circular Welded Carbon Steel Pipes and Tubes From Turkey: Final Results...

  12. Crystal alignment of carbonated apatite in bone and calcified tendon: results from quantitative texture analysis.

    PubMed

    Wenk, H R; Heidelbach, F

    1999-04-01

    Calcified tissue contains collagen associated with minute crystallites of carbonated apatite. In this study, methods of quantitative X-ray texture analysis were used to determine the orientation distribution and texture strength of apatite in a calcified turkey tendon and in trabecular and cortical regions of osteonal bovine ankle bone (metacarpus). To resolve local heterogeneity, a 2 or 10 microm synchrotron microfocus X-ray beam (lambda = 0.78 A) was employed. Both samples revealed a strong texture. In the case of turkey tendon, 12 times more c axes of hexagonal apatite were parallel to the fibril axis than perpendicular, and a axes had rotational freedom about the c axis. In bovine bone, the orientation density of the c axes was three times higher parallel to the surface of collagen fibrils than perpendicular to it, and there was no preferential alignment with respect to the long axis of the bone (fiber texture). Whereas half of the apatite crystallites were strongly oriented, the remaining half had a random orientation distribution. The synchrotron X-ray texture results were consistent with previous analyses of mineral orientation in calcified tissues by conventional X-ray and neutron diffraction and electron microscopy, but gave, for the first time, a quantitative description. PMID:10221548

  13. Photochemical alkene formation in seawater from dissolved organic carbon: Results from laboratory experiments

    NASA Astrophysics Data System (ADS)

    Ratte, M.; Bujok, O.; Spitzy, A.; Rudolph, J.

    1998-03-01

    The production mechanism of light alkenes, alkanes, and isoprene was investigated in laboratory experiments by measuring their concentrations in natural seawater as a function of spectral range, exposure time and origin, and concentration of dissolved organic carbon (DOC). The production mechanism of alkanes and of isoprene could not be clarified. Ethene and propene are produced photochemically from DOC. The relevant spectral range is UV and short-wavelength visible light. Initial production rates (up to day 10 of exposure) were in the range of several pmol L-1 h-1 (mg DOC)-1; the corresponding mean quantum yields for the spectral range of 300-420 nm were about 10-8. Generally, the production rates and the quantum yields for ethene were about 2 times that of propene. The key factors in the total column integrated oceanic alkene production are the solar photon flux at sea surface, the penetration depth of the light into the ocean (especially the relation between different light absorbers, i.e., the extinction due to absorption of DOC), and the wavelength- and DOC-dependent quantum yields. As a result of the high variability of these parameters, actual local alkene production rates for a specific oceanic region may differ considerably from the globally averaged oceanic alkene production rates. The latter were estimated to be at most 5 Mt yr-1.

  14. An Experimental Evaluation of HVAC-Grade Carbon-Dioxide Sensors: Part 2, Performance Test Results

    SciTech Connect

    Shrestha, Som S; Maxwell, Dr. Gregory

    2010-01-01

    This is the second paper in a four-part series reporting on the test and evaluation of typical carbon-dioxide sensors used in building HVAC applications. Fifteen models of NDIR HVAC-grade CO2 sensors were tested and evaluated to determine the accuracy, linearity, repeatability, and hysteresis of each sensor. This paper describes the performance of the sensors and provides a comparison with the manufacturers specifications. The sensors were tested at 40% relative humidity, 73oF (22.8oC) temperature, 14.70 psia (101.35 kPa) pressure, and at five different CO2 concentrations (400 ppm, 750 ppm, 1100 ppm, 1450 ppm, and 1800 ppm). The test results showed a wide variation in sensor performance among the various manufacturers and in some cases a wide variation among sensors of the same model. In all, 45 sensors were evaluated: three from each of the 15 models. Among the 15 models tested, eight models have a single-lamp, single-wavelength configuration, four models have a dual-lamp, single-wavelength configuration, and three models have a single-lamp, dual-wavelength configuration.

  15. Analysis of results of biomass forest inventory in northeastern Amazon for development of REDD+ carbon project.

    PubMed

    Mello, Leonel N C; Sales, Marcio H R; Rosa, Luiz P

    2016-03-01

    In Brazil, a significant reduction in deforestation rates occurred during the last decade. In spite of that fact, the average annual rates are still too high, approximately 400.000 ha/year (INPE/Prodes). The projects of emissions reduction through avoided deforestation (REED+) are an important tool to reduce deforestation rates in Brazil. Understanding the amazon forest structure, in terms of biomass stock is key to design avoided deforestation strategies. In this work, we analyze data results from aboveground biomass of 1,019.346,27 hectares in the state of Pará. It was collected data from 16,722 trees in 83 random independent plots. It was tested 4 allometric equations, for DBH > 10cm: Brown et al. (1989), Brown and Lugo (1999), Chambers et al. (2000), Higuchi et al. (1998). It revealed that the biggest carbon stock of above ground biomass is stocked on the interval at DBH between 30cm and 80cm. This biomass compartment stocks 75.70% of total biomass in Higuchi et al. (1998) equation, 75.56% of total biomass in Brown et al. (1989) equation, 78.83% of total biomass in Chambers et al. (2000) equation, and 73.22% in Brown and Lugo (1999) equation. PMID:26959317

  16. Effect of petroleum coke expanding by perchloric acid on the performance of the resulted activated carbon

    NASA Astrophysics Data System (ADS)

    Deng, Mei-Gen; Wang, Ren-Qing

    2014-10-01

    Petroleum coke (PC) was expanded by using KMnO4 as oxidant and HClO4 as intercalator so as to decrease the amount of KOH needed for the successive activation. Activated carbon (AC) was prepared by activation of the expanded PC (EPC) at KOH/coke mass ratio of 3:1 (denoted as EAC-3). As a comparison, AC was also made by activation of PC at KOH/coke mass ratio of 3:1, 4:1 and 5:1 (denoted as AC-3, AC-4 and AC-5). Influence of expanding modification on the structure and performance of PC and AC was investigated. The results revealed that the expanding treatment increased the interplanar distance of PC microcrystalline from 0.344 to 0.362 nm and decreased the microcrystalline thickness from 2.34 to 1.57 nm. The specific surface area of EAC-3 and AC-5 was 3461 and 3291 m2ṡg-1, respectively. The average pore size of EAC-3 was 2.19 nm, which is 0.11 nm larger than that of AC-5. At a scan rate of 0.5 mVṡs-1, EAC-3 and AC-5 achieved a specific gravimetric capacitance of 486 and 429 Fṡg-1, respectively. Supercapacitor based on EAC-3 possessed lower resistance and better power performance.

  17. DISSOLVED ORGANIC CARBON TRENDS RESULTING FROM CHANGES IN ATMOSPHERIC DEPOSITION CHEMISTRY

    EPA Science Inventory

    Several hypotheses have been proposed to explain recent, widespread increases in concentrations of dissolved organic carbon (DOC) in the surface waters of glaciated landscapes across eastern North America and northern and central Europe. Some invoke anthropogenic forcing through ...

  18. Structure and single-phase regime of boron carbides

    NASA Astrophysics Data System (ADS)

    Emin, David

    1988-09-01

    The boron carbides are composed of twelve-atom icosahedral clusters which are linked by direct covalent bonds and through three-atom intericosahedral chains. The boron carbides are known to exist as a single phase with carbon concentrations from about 8 to about 20 at. %. This range of carbon concentrations is made possible by the substitution of boron and carbon atoms for one another within both the icosahedra and intericosahedral chains. The most widely accepted structural model for B4C (the boron carbide with nominally 20% carbon) has B11C icosahedra with C-B-C intericosahedral chains. Here, the free energy of the boron carbides is studied as a function of carbon concentration by considering the effects of replacing carbon atoms within B4C with boron atoms. It is concluded that entropic and energetic considerations both favor the replacement of carbon atoms with boron atoms within the intericosahedral chains, C-B-C-->C-B-B. Once the carbon concentration is so low that the vast majority of the chains are C-B-B chains, near B13C2, subsequent substitutions of carbon atoms with boron atoms occur within the icosahedra, B11C-->B12. Maxima of the free energy occur at the most ordered compositions: B4C,B13C2,B14C. This structural model, determined by studying the free energy, agrees with that previously suggested by analysis of electronic and thermal transport data. These considerations also provide an explanation for the wide single-phase regime found for boron carbides. The significant entropies associated with compositional disorder within the boron carbides, the high temperatures at which boron carbides are formed (>2000 K), and the relatively modest energies associated with replacing carbon atoms with boron atoms enable the material's entropy to be usually important in determining its composition. As a result, boron carbides are able to exist in a wide range of compositions.

  19. Testing and Results of Vacuum Swing Adsorption Units for Spacesuit Carbon Dioxide and Humidity Control

    NASA Technical Reports Server (NTRS)

    McMillin, Summer; Broerman, Craig; Swickrath, Mike; Anderson, Molly

    2010-01-01

    A principal concern for extravehicular activity (EVA) space suits is the capability to control carbon dioxide (CO2) and humidity (H2O) for the crewmember. The release of CO2 in a confined or unventilated area is dangerous for human health and leads to asphyxiation; therefore, CO2 and H2O become leading factors in the design and development of the spacesuit. An amine-based CO2 and H2O vapor sorbent for use in pressure-swing re-generable beds has been developed by Hamilton Sundstrand. The application of solid-amine materials with vacuum swing adsorption technology has shown the capacity to concurrently manage CO2 and H2O levels through a fully regenerative cycle eliminating mission constraints imposed with non-regenerative technologies. Two prototype solid amine-based systems, known as rapid cycle amine (RCA), were designed to continuously remove CO2 and H2O vapor from a flowing ventilation stream through the use of a two-bed amine based, vacuum-swing adsorption system. The Engineering and Science Contract Group (ESCG) RCA is the first RCA unit implementing radial flow paths, whereas the Hamilton Sundstrand RCA was designed with linear flow paths. Testing was performed in a sea-level pressure environment and a reduced-pressure environment with simulated human metabolic loads in a closed-loop configuration. This paper presents the experimental results of laboratory testing for a full-size and a sub-scale test article. The testing described here characterized and evaluated the performance of each RCA unit at the required Portable Life Support Subsystem (PLSS) operating conditions. The test points simulated a range of crewmember metabolic rates. The experimental results demonstrate the ability of each RCA unit to sufficiently remove CO2 and H2O from a closed loop ambient or subambient atmosphere.

  20. Differences in Chemical Composition of Soil Organic Carbon Resulting From Long-Term Fertilization Strategies

    PubMed Central

    Li, Zengqiang; Zhao, Bingzi; Wang, Qingyun; Cao, Xiaoyan; Zhang, Jiabao

    2015-01-01

    Chemical composition of soil organic carbon (SOC) is central to soil fertility. We hypothesize that change in SOC content resulting from various long-term fertilization strategies accompanies the shift in SOC chemical structure. This study examined the effect of fertilization strategies along with the time of fertilizer application on the SOC composition by 13C nuclear magnetic resonance (NMR) spectroscopy. The soils (Aquic Inceptisol) subjected to seven fertilizer treatments were collected in 1989, 1999 and 2009, representing 0, 10 and 20 years of fertilization, respectively. The seven fertilizer treatments were (1–3) balanced fertilization with application of nitrogen (N), phosphorus (P) and potassium (K) including organic compost (OM), half organic compost plus half chemical fertilizer (1/2OM), and pure chemical NPK fertilizer (NPK); (4–6) unbalanced chemical fertilization without application of one of the major elements including NP fertilizer (NP), PK fertilizer (PK), and NK fertilizer (NK); and (7) an unamended control (CK). The SOC content in the balanced fertilization treatments were 2.3–52.6% and 9.4–64.6% higher than in the unbalanced fertilization/CK treatments in 1999 and 2009, respectively, indicating significant differences in SOC content with time of fertilizer application between the two treatment groups. There was a significantly greater proportion of O-alkyl C and a lower proportion of aromatic C in the balanced fertilization than in unbalanced fertilization/CK treatments in 1999, but not in 2009, because their proportions in the former treatments approached the latter in 2009. Principal component analysis further showed that the C functional groups from various fertilization strategies tended to become compositionally similar with time. The results suggest that a shift in SOC chemical composition may be firstly dominated by fertilization strategies, followed by fertilization duration. PMID:25884713

  1. Testing and Results of Vacuum Swing Adsorption Units for Spacesuit Carbon Dioxide and Humidity Control

    NASA Technical Reports Server (NTRS)

    McMillin, Summer D.; Broerman, Craig D.; Swickrath, Michael; Anderson, Molly

    2011-01-01

    A principal concern for extravehicular activity (EVA) spacesuits is the capability to control carbon dioxide (CO2) and humidity (H2O) for the crewmember. The release of CO2 in a confined or unventilated area is dangerous for human health and leads to asphyxiation; therefore, CO2 and H2O control become leading factors in the design and development of the spacesuit. An amine-based CO2 and H2O vapor sorbent for use in pressure-swing regenerable beds has been developed by Hamilton Sundstrand. The application of solidamine materials with vacuum swing adsorption technology has shown the capacity to concurrently manage CO2 and H2O levels through a fully regenerative cycle eliminating mission constraints imposed with nonregenerative technologies. Two prototype solid amine-based systems, known as rapid cycle amine (RCA), were designed to continuously remove CO2 and H2O vapor from a flowing ventilation stream through the use of a two-bed amine based, vacuum-swing adsorption system. The Engineering and Science Contract Group (ESCG) RCA implements radial flow paths, whereas the Hamilton Sundstrand RCA was designed with linear flow paths. Testing was performed in a sea-level pressure environment and a reduced-pressure environment with simulated human metabolic loads in a closed-loop configuration. This paper presents the experimental results of laboratory testing for a full-size and a sub-scale test article. The testing described here characterized and evaluated the performance of each RCA unit at the required Portable Life Support Subsystem (PLSS) operating conditions. The test points simulated a range of crewmember metabolic rates. The experimental results demonstrated the ability of each RCA unit to sufficiently remove CO2 and H2O from a closed loop ambient or sub-ambient atmosphere.

  2. Interactions Between Mineral Surfaces, Substrates, Enzymes, and Microbes Result in Hysteretic Temperature Sensitivities and Microbial Carbon Use Efficiencies and Weaker Predicted Carbon-Climate Feedbacks

    NASA Astrophysics Data System (ADS)

    Riley, W. J.; Tang, J.

    2014-12-01

    We hypothesize that the large observed variability in decomposition temperature sensitivity and carbon use efficiency arises from interactions between temperature, microbial biogeochemistry, and mineral surface sorptive reactions. To test this hypothesis, we developed a numerical model that integrates the Dynamic Energy Budget concept for microbial physiology, microbial trait-based community structure and competition, process-specific thermodynamically ­­based temperature sensitivity, a non-linear mineral sorption isotherm, and enzyme dynamics. We show, because mineral surfaces interact with substrates, enzymes, and microbes, both temperature sensitivity and microbial carbon use efficiency are hysteretic and highly variable. Further, by mimicking the traditional approach to interpreting soil incubation observations, we demonstrate that the conventional labile and recalcitrant substrate characterization for temperature sensitivity is flawed. In a 4 K temperature perturbation experiment, our fully dynamic model predicted more variable but weaker carbon-climate feedbacks than did the static temperature sensitivity and carbon use efficiency model when forced with yearly, daily, and hourly variable temperatures. These results imply that current earth system models likely over-estimate the response of soil carbon stocks to global warming.

  3. Integrated Assessment Modeling of Carbon Sequestration and Land Use Emissions Using Detailed Model Results and Observations

    SciTech Connect

    Dr. Atul Jain

    2005-04-17

    This report outlines the progress on the development and application of Integrated Assessment Modeling of Carbon Sequestrations and Land Use Emissions supported by the DOE Office of Biological and Environmental Research (OBER), U.S. Department of Energy, Grant No. DOE-DE-FG02-01ER63069. The overall objective of this collaborative project between the University of Illinois at Urbana-Champaign (UIUC), Oak Ridge National Laboratory (ORNL), Lawrence Livermore National Laboratory (LLNL), and Pacific Northwest National Laboratory (PNNL) was to unite the latest advances in carbon cycle research with scientifically based models and policy-related integrated assessment tools that incorporate computationally efficient representations of the latest knowledge concerning science and emission trajectories, and their policy implications. As part of this research we accomplished the following tasks that we originally proposed: (1) In coordination with LLNL and ORNL, we enhanced the Integrated Science Assessment Model's (ISAM) parametric representation of the ocean and terrestrial carbon cycles that better represent spatial and seasonal variations, which are important to study the mechanisms that influence carbon sequestration in the ocean and terrestrial ecosystems; (2) Using the MiniCAM modeling capability, we revised the SRES (IPCC Special Report on Emission Scenarios; IPCC, 2000) land use emission scenarios; and (3) On the application front, the enhanced version of ISAM modeling capability is applied to understand how short- and long-term natural carbon fluxes, carbon sequestration, and human emissions contribute to the net global emissions (concentrations) trajectories required to reach various concentration (emission) targets. Under this grant, 21 research publications were produced. In addition, this grant supported a number of graduate and undergraduate students whose fundamental research was to learn a disciplinary field in climate change (e.g., ecological dynamics and

  4. Can carbon surface oxidation shift the pore size distribution curve calculated from Ar, N2 and CO2 adsorption isotherms? Simulation results for a realistic carbon model

    NASA Astrophysics Data System (ADS)

    Furmaniak, Sylwester; Terzyk, Artur P.; Gauden, Piotr A.; Harris, Peter J. F.; Kowalczyk, Piotr

    2009-08-01

    Using the virtual porous carbon model proposed by Harris et al, we study the effect of carbon surface oxidation on the pore size distribution (PSD) curve determined from simulated Ar, N2 and CO2 isotherms. It is assumed that surface oxidation is not destructive for the carbon skeleton, and that all pores are accessible for studied molecules (i.e., only the effect of the change of surface chemical composition is studied). The results obtained show two important things, i.e., oxidation of the carbon surface very slightly changes the absolute porosity (calculated from the geometric method of Bhattacharya and Gubbins (BG)); however, PSD curves calculated from simulated isotherms are to a greater or lesser extent affected by the presence of surface oxides. The most reliable results are obtained from Ar adsorption data. Not only is adsorption of this adsorbate practically independent from the presence of surface oxides, but, more importantly, for this molecule one can apply the slit-like model of pores as the first approach to recover the average pore diameter of a real carbon structure. For nitrogen, the effect of carbon surface chemical composition is observed due to the quadrupole moment of this molecule, and this effect shifts the PSD curves compared to Ar. The largest differences are seen for CO2, and it is clearly demonstrated that the PSD curves obtained from adsorption isotherms of this molecule contain artificial peaks and the average pore diameter is strongly influenced by the presence of electrostatic adsorbate-adsorbate as well as adsorbate-adsorbent interactions.

  5. Can carbon surface oxidation shift the pore size distribution curve calculated from Ar, N(2) and CO(2) adsorption isotherms? Simulation results for a realistic carbon model.

    PubMed

    Furmaniak, Sylwester; Terzyk, Artur P; Gauden, Piotr A; Harris, Peter J F; Kowalczyk, Piotr

    2009-08-01

    Using the virtual porous carbon model proposed by Harris et al, we study the effect of carbon surface oxidation on the pore size distribution (PSD) curve determined from simulated Ar, N(2) and CO(2) isotherms. It is assumed that surface oxidation is not destructive for the carbon skeleton, and that all pores are accessible for studied molecules (i.e., only the effect of the change of surface chemical composition is studied). The results obtained show two important things, i.e., oxidation of the carbon surface very slightly changes the absolute porosity (calculated from the geometric method of Bhattacharya and Gubbins (BG)); however, PSD curves calculated from simulated isotherms are to a greater or lesser extent affected by the presence of surface oxides. The most reliable results are obtained from Ar adsorption data. Not only is adsorption of this adsorbate practically independent from the presence of surface oxides, but, more importantly, for this molecule one can apply the slit-like model of pores as the first approach to recover the average pore diameter of a real carbon structure. For nitrogen, the effect of carbon surface chemical composition is observed due to the quadrupole moment of this molecule, and this effect shifts the PSD curves compared to Ar. The largest differences are seen for CO(2), and it is clearly demonstrated that the PSD curves obtained from adsorption isotherms of this molecule contain artificial peaks and the average pore diameter is strongly influenced by the presence of electrostatic adsorbate-adsorbate as well as adsorbate-adsorbent interactions. PMID:21828590

  6. Jellyfish blooms result in a major microbial respiratory sink of carbon in marine systems.

    PubMed

    Condon, Robert H; Steinberg, Deborah K; del Giorgio, Paul A; Bouvier, Thierry C; Bronk, Deborah A; Graham, William M; Ducklow, Hugh W

    2011-06-21

    Jellyfish blooms occur in many estuarine and coastal regions and may be increasing in their magnitude and extent worldwide. Voracious jellyfish predation impacts food webs by converting large quantities of carbon (C), fixed by primary producers and consumed by secondary producers, into gelatinous biomass, which restricts C transfer to higher trophic levels because jellyfish are not readily consumed by other predators. In addition, jellyfish release colloidal and dissolved organic matter (jelly-DOM), and could further influence the functioning of coastal systems by altering microbial nutrient and DOM pathways, yet the links between jellyfish and bacterioplankton metabolism and community structure are unknown. Here we report that jellyfish released substantial quantities of extremely labile C-rich DOM, relative to nitrogen (25.6 ± 31.6 C:1N), which was quickly metabolized by bacterioplankton at uptake rates two to six times that of bulk DOM pools. When jelly-DOM was consumed it was shunted toward bacterial respiration rather than production, significantly reducing bacterial growth efficiencies by 10% to 15%. Jelly-DOM also favored the rapid growth and dominance of specific bacterial phylogenetic groups (primarily γ-proteobacteria) that were rare in ambient waters, implying that jelly-DOM was channeled through a small component of the in situ microbial assemblage and thus induced large changes in community composition. Our findings suggest major shifts in microbial structure and function associated with jellyfish blooms, and a large detour of C toward bacterial CO(2) production and away from higher trophic levels. These results further suggest fundamental transformations in the biogeochemical functioning and biological structure of food webs associated with jellyfish blooms. PMID:21646531

  7. Thermostructural Analysis of Carbon Cloth Phenolics "Ply Lifting" and Correlation to LHMEL Test Results

    NASA Technical Reports Server (NTRS)

    Clayton, Louie

    2004-01-01

    This paper provides a discussion of the history of Carbon Cloth Phenolic (CCP) ply lifting in the Redesigned Solid Rocket Motor (RSRM) Program, a brief presentation of theoretical methods used for analytical evaluation, and results of parametric analyses of CCP material subject to test conditions of the Laser Hardened Material Evaluation Laboratory. CCP ply lift can occur in regions of the RSRM nozzle where ply angle to flame surface is generally less than about 20 degrees. There is a heat rate dependence on likelihood and severity of the condition with the higher heating rates generally producing more ply lift. The event occurs in-depth, near the heated surface, where the load necessary to mechanically separate the CCP plies is produced by the initial stages of pyrolysis gas generation due to the thermal decomposition of the phenolic resin matrix. Due to the shallow lay-up angle of the composite, normal components of the indepth mechanical load, due to "pore pressure", are imparted primarily as a cross-ply tensile force on the interlaminar ply boundaries. Tensile capability in the cross-ply (out of plane) direction is solely determined by the matrix material capability. The elevated temperature matrix material capabilities are overcome by pressure induced mechanical normal stress and ply-lift occurs. A theoretical model used for CCP in-depth temperature, pressure, and normal stress prediction, based on first principles, is briefly discussed followed by a parametric evaluation of response variables subject to boundary conditions typical of on-going test programs at the LHMEL facility. Model response demonstrates general trends observed in test and provides insight into the interactivity of material properties and constitutive relationships.

  8. 77 FR 67337 - Certain Activated Carbon From the People's Republic of China; 2010-2011; Final Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-09

    ...The Department of Commerce (``the Department'') published its Preliminary Results of the antidumping duty order on certain activated carbon from the People's Republic of China (``PRC'') on May 4, 2012,\\1\\ and we gave interested parties an opportunity to comment on the Preliminary Results. Based upon our analysis of the comments and information received, we made changes to the margin......

  9. 78 FR 70533 - Certain Activated Carbon From the People's Republic of China: Final Results of Antidumping Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-11-26

    ...; 2011-2012, 78 FR 26748 (May 8, 2013) (``Preliminary Results''). DATES: Effective Date: November 26....\\12\\ \\2\\ See id. \\3\\ See id., 78 FR at 26749. \\4\\ See Memorandum to Christian Marsh, Deputy Assistant... Results, 78 FR at 26749; see also Notice of Antidumping Duty Order: Certain Activated Carbon from...

  10. The Carbon in Arctic Reservoirs Vulnerability Experiment (CARVE): Results from 2011 Engineering Test Flights

    NASA Astrophysics Data System (ADS)

    Miller, C. E.; Dinardo, S. J.

    2011-12-01

    The carbon balance of Arctic ecosystems is not known with confidence since fundamental elements of the complex Arctic biological-climatologic-hydrologic system are poorly quantified. CARVE - The Carbon in Arctic Reservoirs Vulnerability Experiment - will address this key gap in science knowledge by: 1) Directly testing hypotheses attributing the mobilization of vulnerable Arctic carbon reservoirs to climate warming; 2) Delivering the first direct measurements and detailed maps of CO2 and CH4 sources on regional scales in the critical Arctic ecozone; and 3) Demonstrating new remote sensing and modeling capabilities to quantify feedbacks between carbon fluxes and carbon cycle-climate processes in the Arctic. CARVE measurements and integrated science data will provide unprecedented experimental insights into Arctic carbon cycling and its response to climate change. CARVE employs a robust, flexible strategy to reconcile Arctic carbon fluxes estimated from atmospheric concentrations of CO2 and CH4 (top-down approach) with carbon fluxes estimated from coincident measurements of surface state controls (bottom-up approach). The CARVE Science Operations involve deployments in Alaska during the spring, summer, and fall each year from 2012-2014. CARVE flight plans sample multiple permafrost domains and ecosystems, and deliver detailed observations over ground-based measurement sites, fires, and burn-recovery chronosequences. CARVE flies aboard the De Havilland DHC-6 Twin Otter. The science payload consists of: JPL's Passive Active L-band System (PALS) to deliver the measurements of soil moisture, freeze/thaw state, inundation state, and surface temperature; an airborne Fourier Transform Spectrometer (FTS) to deliver total atmospheric column measurements of CO2 and CH4, and CO; and (3) an In Situ Gas Analyzer (ISGA) to deliver continuous measurements of CO2 and CH4, and CO, calibration standards, and whole air flask samples for point measurements of over 50 trace gases

  11. Arctic circulation regimes.

    PubMed

    Proshutinsky, Andrey; Dukhovskoy, Dmitry; Timmermans, Mary-Louise; Krishfield, Richard; Bamber, Jonathan L

    2015-10-13

    Between 1948 and 1996, mean annual environmental parameters in the Arctic experienced a well-pronounced decadal variability with two basic circulation patterns: cyclonic and anticyclonic alternating at 5 to 7 year intervals. During cyclonic regimes, low sea-level atmospheric pressure (SLP) dominated over the Arctic Ocean driving sea ice and the upper ocean counterclockwise; the Arctic atmosphere was relatively warm and humid, and freshwater flux from the Arctic Ocean towards the subarctic seas was intensified. By contrast, during anticylonic circulation regimes, high SLP dominated driving sea ice and the upper ocean clockwise. Meanwhile, the atmosphere was cold and dry and the freshwater flux from the Arctic to the subarctic seas was reduced. Since 1997, however, the Arctic system has been under the influence of an anticyclonic circulation regime (17 years) with a set of environmental parameters that are atypical for this regime. We discuss a hypothesis explaining the causes and mechanisms regulating the intensity and duration of Arctic circulation regimes, and speculate how changes in freshwater fluxes from the Arctic Ocean and Greenland impact environmental conditions and interrupt their decadal variability. PMID:26347536

  12. Arctic circulation regimes

    PubMed Central

    Proshutinsky, Andrey; Dukhovskoy, Dmitry; Timmermans, Mary-Louise; Krishfield, Richard; Bamber, Jonathan L.

    2015-01-01

    Between 1948 and 1996, mean annual environmental parameters in the Arctic experienced a well-pronounced decadal variability with two basic circulation patterns: cyclonic and anticyclonic alternating at 5 to 7 year intervals. During cyclonic regimes, low sea-level atmospheric pressure (SLP) dominated over the Arctic Ocean driving sea ice and the upper ocean counterclockwise; the Arctic atmosphere was relatively warm and humid, and freshwater flux from the Arctic Ocean towards the subarctic seas was intensified. By contrast, during anticylonic circulation regimes, high SLP dominated driving sea ice and the upper ocean clockwise. Meanwhile, the atmosphere was cold and dry and the freshwater flux from the Arctic to the subarctic seas was reduced. Since 1997, however, the Arctic system has been under the influence of an anticyclonic circulation regime (17 years) with a set of environmental parameters that are atypical for this regime. We discuss a hypothesis explaining the causes and mechanisms regulating the intensity and duration of Arctic circulation regimes, and speculate how changes in freshwater fluxes from the Arctic Ocean and Greenland impact environmental conditions and interrupt their decadal variability. PMID:26347536

  13. 75 FR 18788 - Circular Welded Carbon Steel Pipes and Tubes from Thailand: Preliminary Results and Rescission...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-04-13

    ...: Circular Welded Carbon Steel Pipes and Tubes from Thailand, 51 FR 8341 (March 11, 1986). On March 2, 2009..., Finding or Suspended Investigation; Opportunity to Request Administrative Review, 74 FR 9077 (March 2... Reviews and Request for Revocation in Part, 74 FR 19042 (April 27, 2009). On May 5, 2009, Pacific...

  14. 78 FR 34340 - Welded Carbon Steel Standard Pipe and Tube Products From Turkey: Preliminary Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-07

    ... for Revocation in Part, 77 FR 40565 (July 10, 2012). \\3\\ The Department initiated a review on the... Order; Welded Carbon Steel Standard Pipe and Tube Products from Turkey, 51 FR 17784 (May 15, 1986). The... clarification, see Antidumping and Countervailing Duty Proceedings: Assessment of Antidumping Duties, 68...

  15. 75 FR 70208 - Certain Activated Carbon From the People's Republic of China: Final Results and Partial...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-17

    ... Second Antidumping Duty Administrative Review, and Preliminary Rescission in Part, 75 FR 26927 (May 13... review was requested. See Initiation of Antidumping and Countervailing Duty Administrative Reviews, 74 FR... Administrative Review, 74 FR 31690 (July 2, 2009). \\3\\ See Certain Activated Carbon From the People's Republic...

  16. Net Carbon Emissions from Deforestation in Bolivia during 1990-2000 and 2000-2010: Results from a Carbon Bookkeeping Model.

    PubMed

    Andersen, Lykke E; Doyle, Anna Sophia; del Granado, Susana; Ledezma, Juan Carlos; Medinaceli, Agnes; Valdivia, Montserrat; Weinhold, Diana

    2016-01-01

    Accurate estimates of global carbon emissions are critical for understanding global warming. This paper estimates net carbon emissions from land use change in Bolivia during the periods 1990-2000 and 2000-2010 using a model that takes into account deforestation, forest degradation, forest regrowth, gradual carbon decomposition and accumulation, as well as heterogeneity in both above ground and below ground carbon contents at the 10 by 10 km grid level. The approach permits detailed maps of net emissions by region and type of land cover. We estimate that net CO2 emissions from land use change in Bolivia increased from about 65 million tons per year during 1990-2000 to about 93 million tons per year during 2000-2010, while CO2 emissions per capita and per unit of GDP have remained fairly stable over the sample period. If we allow for estimated biomass increases in mature forests, net CO2 emissions drop to close to zero. Finally, we find these results are robust to alternative methods of calculating emissions. PMID:26990865

  17. Net Carbon Emissions from Deforestation in Bolivia during 1990-2000 and 2000-2010: Results from a Carbon Bookkeeping Model

    PubMed Central

    Andersen, Lykke E.; Doyle, Anna Sophia; del Granado, Susana; Ledezma, Juan Carlos; Medinaceli, Agnes; Valdivia, Montserrat; Weinhold, Diana

    2016-01-01

    Accurate estimates of global carbon emissions are critical for understanding global warming. This paper estimates net carbon emissions from land use change in Bolivia during the periods 1990–2000 and 2000–2010 using a model that takes into account deforestation, forest degradation, forest regrowth, gradual carbon decomposition and accumulation, as well as heterogeneity in both above ground and below ground carbon contents at the 10 by 10 km grid level. The approach permits detailed maps of net emissions by region and type of land cover. We estimate that net CO2 emissions from land use change in Bolivia increased from about 65 million tons per year during 1990–2000 to about 93 million tons per year during 2000–2010, while CO2 emissions per capita and per unit of GDP have remained fairly stable over the sample period. If we allow for estimated biomass increases in mature forests, net CO2 emissions drop to close to zero. Finally, we find these results are robust to alternative methods of calculating emissions. PMID:26990865

  18. How does carbon dioxide permeate cell membranes? A discussion of concepts, results and methods

    PubMed Central

    Endeward, Volker; Al-Samir, Samer; Itel, Fabian; Gros, Gerolf

    2013-01-01

    We review briefly how the thinking about the permeation of gases, especially CO2, across cell and artificial lipid membranes has evolved during the last 100 years. We then describe how the recent finding of a drastic effect of cholesterol on CO2 permeability of both biological and artificial membranes fundamentally alters the long-standing idea that CO2—as well as other gases—permeates all membranes with great ease. This requires revision of the widely accepted paradigm that membranes never offer a serious diffusion resistance to CO2 or other gases. Earlier observations of “CO2-impermeable membranes” can now be explained by the high cholesterol content of some membranes. Thus, cholesterol is a membrane component that nature can use to adapt membrane CO2 permeability to the functional needs of the cell. Since cholesterol serves many other cellular functions, it cannot be reduced indefinitely. We show, however, that cells that possess a high metabolic rate and/or a high rate of O2 and CO2 exchange, do require very high CO2 permeabilities that may not be achievable merely by reduction of membrane cholesterol. The article then discusses the alternative possibility of raising the CO2 permeability of a membrane by incorporating protein CO2 channels. The highly controversial issue of gas and CO2 channels is systematically and critically reviewed. It is concluded that a majority of the results considered to be reliable, is in favor of the concept of existence and functional relevance of protein gas channels. The effect of intracellular carbonic anhydrase, which has recently been proposed as an alternative mechanism to a membrane CO2 channel, is analysed quantitatively and the idea considered untenable. After a brief review of the knowledge on permeation of O2 and NO through membranes, we present a summary of the 18O method used to measure the CO2 permeability of membranes and discuss quantitatively critical questions that may be addressed to this method. PMID

  19. Hall effect in hopping regime

    NASA Astrophysics Data System (ADS)

    Avdonin, A.; Skupiński, P.; Grasza, K.

    2016-02-01

    A simple description of the Hall effect in the hopping regime of conductivity in semiconductors is presented. Expressions for the Hall coefficient and Hall mobility are derived by considering averaged equilibrium electron transport in a single triangle of localization sites in a magnetic field. Dependence of the Hall coefficient is analyzed in a wide range of temperature and magnetic field values. Our theoretical result is applied to our experimental data on temperature dependence of Hall effect and Hall mobility in ZnO.

  20. Regime shifts in the anthropocene: drivers, risks, and resilience.

    PubMed

    Rocha, Juan Carlos; Peterson, Garry D; Biggs, Reinette

    2015-01-01

    Many ecosystems can experience regime shifts: surprising, large and persistent changes in the function and structure of ecosystems. Assessing whether continued global change will lead to further regime shifts, or has the potential to trigger cascading regime shifts has been a central question in global change policy. Addressing this issue has, however, been hampered by the focus of regime shift research on specific cases and types of regime shifts. To systematically assess the global risk of regime shifts we conducted a comparative analysis of 25 generic types of regime shifts across marine, terrestrial and polar systems; identifying their drivers, and impacts on ecosystem services. Our results show that the drivers of regime shifts are diverse and co-occur strongly, which suggests that continued global change can be expected to synchronously increase the risk of multiple regime shifts. Furthermore, many regime shift drivers are related to climate change and food production, whose links to the continued expansion of human activities makes them difficult to limit. Because many regime shifts can amplify the drivers of other regime shifts, continued global change can also be expected to increase the risk of cascading regime shifts. Nevertheless, the variety of scales at which regime shift drivers operate provides opportunities for reducing the risk of many types of regime shifts by addressing local or regional drivers, even in the absence of rapid reduction of global drivers. PMID:26267896

  1. Regime Shifts in the Anthropocene: Drivers, Risks, and Resilience

    PubMed Central

    Rocha, Juan Carlos; Peterson, Garry D.; Biggs, Reinette

    2015-01-01

    Many ecosystems can experience regime shifts: surprising, large and persistent changes in the function and structure of ecosystems. Assessing whether continued global change will lead to further regime shifts, or has the potential to trigger cascading regime shifts has been a central question in global change policy. Addressing this issue has, however, been hampered by the focus of regime shift research on specific cases and types of regime shifts. To systematically assess the global risk of regime shifts we conducted a comparative analysis of 25 generic types of regime shifts across marine, terrestrial and polar systems; identifying their drivers, and impacts on ecosystem services. Our results show that the drivers of regime shifts are diverse and co-occur strongly, which suggests that continued global change can be expected to synchronously increase the risk of multiple regime shifts. Furthermore, many regime shift drivers are related to climate change and food production, whose links to the continued expansion of human activities makes them difficult to limit. Because many regime shifts can amplify the drivers of other regime shifts, continued global change can also be expected to increase the risk of cascading regime shifts. Nevertheless, the variety of scales at which regime shift drivers operate provides opportunities for reducing the risk of many types of regime shifts by addressing local or regional drivers, even in the absence of rapid reduction of global drivers. PMID:26267896

  2. Modeling of the Ablation of Fibrous Materials in the Knudsen Regime

    NASA Technical Reports Server (NTRS)

    Lachaud, J.; Mansour, N. N.

    2008-01-01

    During atmospheric entry of planetary probes, the thermal protection system (TPS) of the probe is exposed to high temperatures under low pressures. In these conditions, carbonous TPS materials undergo gasification in the Knudsen regime leading to mass loss and wall recession called ablation. This work aims to improve the understanding of materiaVenvironment interactions through a study of the coupling between carbon dioxide transport in the Knudsen regime, heterogeneous oxidation of carbon, and sutface recession. A 3D Monte-Carlo simulation tool is used for this study. The fibrous architecture of the materiils, consisting of high porosity random array of carbon fibers, is numerically reproduced on a 3D Cartesian grid. Mass transport in the Knudsen regime from the boundary layer to the surface, and inside this porous material is simulated by random walk. A reaction probability is used to simulate the heterogeneous oxidation reaction. The surface recession is followed by front tracking using a simplified marching cube approach. The output data of the simulations are ablation velocity and dynamic evolution of the material porosity. A parametric study is carried out to analyze the material behavior as a function of Knudsen number for the porous media (length of the mean free path compared to the mean pore diameter) and the intrinsic reactivity of the carbon fibers. The results enable extrapolation of laboratory experimental data to actual entry conditions.

  3. 75 FR 64254 - Certain Hot-Rolled Flat-Rolled Carbon Quality Steel Products From Brazil; Final Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-19

    ... Antidumping Duty Administrative Review and Extension of Time Limit for the Final Results, 75 FR 19369 (April... Carbon-Quality Steel Products from the Russian Federation, 65 FR 5510, 5518 (February 4, 2000) (Russian...: Assessment of Antidumping Duties, 68 FR 23954 (May 6, 2003). This clarification will apply to entries...

  4. 75 FR 43488 - Certain Hot-Rolled Carbon Steel Flat Products From India: Final Results of Countervailing Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-26

    ... Hot-Rolled Carbon Steel Flat Products from India, 66 FR 60198 (December 3, 2001). On February 2, 2009...; 75 FR 1495 (January 11, 2010) (Preliminary Results). We preliminarily found that Tata Steel Limited... Countervailing Duty Administrative Reviews and Requests for Revocation in Part, 74 FR 5821 (February 2,...

  5. 76 FR 33204 - Certain Welded Carbon Steel Pipe and Tube From Turkey; Notice of Preliminary Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-06-08

    ... Results of Antidumping Duty Administrative Review, 75 FR 6627 (February 10, 2010) (``SSSS from Mexico..., 75 FR 37759 (June 30, 2010) (``Review Initiation'').\\1\\ This review covers the Borusan Group \\2... Order; Welded Carbon Steel Standard Pipe and Tube Products From Turkey, 51 FR 17784 (May 15,...

  6. 77 FR 13545 - Carbon and Certain Alloy Steel Wire Rod From Mexico: Notice of Final Results of Antidumping Duty...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-07

    ... Antidumping Duty Administrative Review 76 FR 67407 (November 1, 2011) (Preliminary Results). \\2\\ We determined... Changed Circumstances Review: Carbon and Certain Alloy Steel Wire Rod from Mexico, 76 FR 45509 (July 29... Countervailing Duty Proceedings: Assessment of Antidumping Duties, 68 FR 23954 (May 6, 2003) (Assessment...

  7. 75 FR 33262 - Certain Welded Carbon Steel Pipe and Tube from Turkey: Notice of Preliminary Results of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-11

    ... Turkey, 51 FR 17784 (May 15, 1986) (``Antidumping Duty Order''). On May 1, 2009, the Department published... and Tube From Turkey, 74 FR 6368 (February 9, 2009), unchanged in Certain Welded Carbon Steel Pipe and Tube from Turkey: Notice of Final Results of Antidumping Duty Administrative Review, 74 FR 22883...

  8. 78 FR 60850 - Carbon and Certain Alloy Steel Wire Rod From Brazil: Final Results of the Expedited Second Sunset...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-02

    ... Alloy Steel Wire Rod from Brazil, 67 FR 55805 (August 30, 2002). \\2\\ See Initiation of Five-Year (``Sunset'') Review, 78 FR 33063 (June 3, 2013). On June 18, 2013, the Department received a notice of... International Trade Administration Carbon and Certain Alloy Steel Wire Rod From Brazil: Final Results of...

  9. Fracture trace map and single-well aquifer test results in a carbonate aquifer in Berkeley County, West Virginia

    USGS Publications Warehouse

    McCoy, Kurt J.; Podwysocki, Melvin H.; Crider, E. Allen; Weary, David J.

    2005-01-01

    These data contain information on the results of single-well aquifer tests, lineament analysis, and a bedrock geologic map compilation for the low-lying carbonate and shale areas of eastern Berkeley County, West Virginia. Efforts have been initiated by management agencies of Berkeley County in cooperation with the U.S. Geological Survey to further the understanding of the spatial distribution of fractures in the carbonate regions and their correlation with aquifer properties. This report presents transmissivity values from about 200 single-well aquifer tests and a map of fracture-traces determined from aerial photos and field investigations. Transmissivity values were compared to geologic factors possibly affecting its magnitude.

  10. Solid and Gas-Phase Spectroscopy of Cosmic Carbon Analogs: Results and Perspectives

    NASA Technical Reports Server (NTRS)

    Salama, Farid; DeVincenzi, Donald L. (Technical Monitor)

    2001-01-01

    The laboratory studies of interstellar carbon materials analogs (PAHs, Fullerenes, chains) will be discussed with their advantages and limitations from the point of view of the application to astrophysical processes. The discussion will focus on the newest generation of laboratory experiments that has been developed in order to provide a closer simulation of space environments and a better support to space missions. The astrophysical implications and future perspectives will be stressed.

  11. Carbon isotope analysis of conodont organic material--Procedure and preliminary results

    SciTech Connect

    Over, D.J. . Dept. of Geological Sciences); Grossman, E.L. )

    1992-01-01

    Conodonts, the phosphatic microfossil remains of an extinct pelagic animal, are well suited for isotopic studies of Paleozoic marine organic carbon. The author report here what they believe are the first delta C-13 data for the organic matrix of conodont elements. Conodont delta C-13 values (PDB) for Upper Devonian Palmatolepis platform elements from a single interval of the Chappel Limestones in Texas range from [minus]24.5 to [minus]25.6 [per thousand] (n = 5). Lower Carboniferous Siphonodella platform elements from the same interval in the Chappel Limestone range from [minus]26.3 to [minus]27.3 [per thousand] (n = 2). Upper Carboniferous Streptognathodus elegantulus platform elements from four intervals in a 3.9 m section of the Necessity Shale in Texas range from [minus]23.0 to [minus]24.0 [per thousand] (n = 4). delta C-13 values also differ significantly between the three sample groups. Average values were [minus]4.7, [minus]7.1, and [minus]8.3 [per thousand] respectively, however, the relevance of these values is unclear. The conodont organic carbon isotopic values are within the range of delta C-13 values in sedimentary organic matter of late Paleozoic age. Although the data are limited, they show that significant isotopic differences occur between genera and between stratigraphically separate units. These isotopic differences in delta C-13 may be related to local changes in source of organic carbon, global changes in the carbon budget, or to dietary differences among conodont animals. Future study is directed toward evaluating the importance of each of these factors.

  12. JPL Carbon Dioxide Laser Absorption Spectrometer Data Processing Results for the 2010 Flight Campaign

    NASA Technical Reports Server (NTRS)

    Jacob, Joseph C.; Spiers, Gary D.; Menzie, Robert T.; Christensen, Lance E.

    2011-01-01

    As a precursor to and validation of the core technology necessary for NASA's Active Sensing of CO2 Emissions over Nights, Days,and Seasons (ASCENDS) mission, we flew JPL's Carbon Dioxide Laser Absorption Spectrometer (CO2LAS) in a campaign of five flights onboard NASA's DC-8 Airborne Laboratory in July 2010. This is the latest in a series of annual flight campaigns that began in 2006, and our first on the DC-8 aircraft.

  13. Regimes of DNA confined in a nanochannel

    NASA Astrophysics Data System (ADS)

    Dai, Liang; Doyle, Patrick

    2014-03-01

    Scaling regimes for polymers confined to tubular channels are well established when the channel cross-sectional dimension is either very small (Odjik regime) or large (classic de Gennes regime) relative to the polymer Kuhn length. In the literature, there is no clear consensus regarding the intermediate region and if subregimes even exist to connect these two classic bounding regimes. The confluence of emerging single DNA mapping technologies and a resurged interest in the fundamental properties of confined polymers has led to extensive research in this area using DNA as a model system. Due to the DNA molecule's properties and limitations of nanofabrication, most experiments are performed in this intermediate regime with channel dimensions of a few Kuhn lengths. Here we use simulations and theory to reconcile conflicting theories and show that there are indeed extended de Gennes, partial alignment and hairpin regimes located between the two classic regimes. Simulations results for both chain extension and free energy support the existence of these regimes. This research was supported by the National Research Foundation Singapore through the Singapore MIT Alliance for Research and Technology's research program in BioSystems and Micromechanics, the National Science Foundation (CBET-1335938).

  14. Radiative forcing associated with particulate carbon emissions resulting from the use of mercury control technology.

    PubMed

    Lin, Guangxing; Penner, Joyce E; Clack, Herek L

    2014-09-01

    Injection of powdered activated carbon (PAC) adsorbents into the flue gas of coal fired power plants with electrostatic precipitators (ESPs) is the most mature technology to control mercury emissions for coal combustion. However, the PAC itself can penetrate ESPs to emit into the atmosphere. These emitted PACs have similar size and optical properties to submicron black carbon (BC) and thus could increase BC radiative forcing unintentionally. The present paper estimates, for the first time, the potential emission of PAC together with their climate forcing. The global average maximum potential emissions of PAC is 98.4 Gg/yr for the year 2030, arising from the assumed adoption of the maximum potential PAC injection technology, the minimum collection efficiency, and the maximum PAC injection rate. These emissions cause a global warming of 2.10 mW m(-2) at the top of atmosphere and a cooling of -2.96 mW m(-2) at the surface. This warming represents about 2% of the warming that is caused by BC from direct fossil fuel burning and 0.86% of the warming associated with CO2 emissions from coal burning in power plants. Its warming is 8 times more efficient than the emitted CO2 as measured by the 20-year-integrated radiative forcing per unit of carbon input (the 20-year Global Warming Potential). PMID:25093939

  15. CO2 release due to impact devolatilization of carbonate: Results of shock experiments

    NASA Astrophysics Data System (ADS)

    Bell, Mary Sue

    2016-04-01

    A study of pure, single crystal calcite shocked to pressures from 9.0 to 60.8 GPa was conducted to address contradictory data for carbonate shock behavior. The recovered materials were analyzed optically and by transmission electron microscopy (TEM), as well as by thermogravimetry (TGA), X-ray diffraction (XRD), and Raman-spectroscopy. In thin section, progressive comminution of calcite is observed although grains remain birefringent to at least 60.8 GPa. TGA analysis reveals a positive correlation between percent of mass loss due to shock and increasing shock pressure (R = 0.77) and suggests that shock loading leads to the modest removal of structural volatiles in this pressure range. XRD patterns of shocked Iceland spar samples produce peaks that are qualitatively and quantitatively less intense, more diffuse, and shift to lower o2θ. However, the regularity observed in these shocked powder patterns suggests that structures with very uniform unit cell separations persist to shock pressures as high as 60.8 GPa. Raman spectral analyses indicate no band asymmetry and no systematic peak shifting or broadening. TEM micrographs display progressively diminishing crystallite domain sizes. Selected area electron diffraction (SAED) patterns reveal no signatures of amorphous material. These data show that essentially intact calcite is recovered at shock pressures up to 60.8 GPa with only slight mass loss (~7%). This work suggests that the amount of CO2 gas derived from shock devolatilization of carbonate by large meteorite impacts into carbonate targets has been (substantially) overestimated.

  16. Regimes of Helium Burning

    SciTech Connect

    Timmes, F. X.; Niemeyer, J. C.

    2000-07-10

    The burning regimes encountered by laminar deflagrations and Zeldovich von Neumann Doering [ZND] detonations propagating through helium-rich compositions in the presence of buoyancy-driven turbulence are analyzed. Particular attention is given to models of X-ray bursts that start with a thermonuclear runaway on the surface of a neutron star and to the thin-shell helium instability of intermediate-mass stars. In the X-ray burst case, turbulent deflagrations propagating in the lateral or radial direction encounter a transition from the distributed regime to the flamelet regime at a density of {approx}108 g cm-3. In the radial direction, the purely laminar deflagration width is larger than the pressure scale height for densities smaller than {approx}106 g cm-3. Self-sustained laminar deflagrations traveling in the radial direction cannot exist below this density. Similarly, the planar ZND detonation width becomes larger than the pressure scale height at {approx}107 g cm-3, suggesting that steady state, self-sustained detonations cannot come into existence in the radial direction. In the thin helium shell case, turbulent deflagrations traveling in the lateral or radial direction encounter the distributed regime at densities below {approx}107 g cm-3 and the flamelet regime at larger densities. In the radial direction, the purely laminar deflagration width is larger than the pressure scale height for densities smaller than {approx}104 g cm-3, indicating that steady state laminar deflagrations cannot form below this density. The planar ZND detonation width becomes larger than the pressure scale height at {approx}5x10{sup 4} g cm-3, suggesting that steady state, self-sustained detonations cannot come into existence in the radial direction. (c) 2000 The American Astronomical Society.

  17. Changes in mineralogical and leaching properties of converter steel slag resulting from accelerated carbonation at low CO2 pressure.

    PubMed

    van Zomeren, André; van der Laan, Sieger R; Kobesen, Hans B A; Huijgen, Wouter J J; Comans, Rob N J

    2011-11-01

    Steel slag can be applied as substitute for natural aggregates in construction applications. The material imposes a high pH (typically 12.5) and low redox potential (Eh), which may lead to environmental problems in specific application scenarios. The aim of this study is to investigate the potential of accelerated steel slag carbonation, at relatively low pCO2 pressure (0.2 bar), to improve the environmental pH and the leaching properties of steel slag, with specific focus on the leaching of vanadium. Carbonation experiments are performed in laboratory columns with steel slag under water-saturated and -unsaturated conditions and temperatures between 5 and 90 °C. Two types of steel slag are tested; free lime containing (K3) slag and K1 slag with a very low free lime content. The fresh and carbonated slag samples are investigated using a combination of leaching experiments, geochemical modelling of leaching mechanisms and microscopic/mineralogical analysis, in order to identify the major processes that control the slag pH and resulting V leaching. The major changes in the amount of sequestered CO2 and the resulting pH reduction occurred within 24h, the free lime containing slag (K3-slag) being more prone to carbonation than the slag with lower free lime content (K1-slag). While carbonation at these conditions was found to occur predominantly at the surface of the slag grains, the formation of cracks was observed in carbonated K3 slag, suggesting that free lime in the interior of slag grains had also reacted. The pH of the K3 slag (originally pH±12.5) was reduced by about 1.5 units, while the K1 slag showed a smaller decrease in pH from about 11.7 to 11.1. However, the pH reduction after carbonation of the K3 slag was observed to lead to an increased V-leaching. Vanadium leaching from the K1 slag resulted in levels above the limit values of the Dutch Soil Quality Decree, for both the untreated and carbonated slag. V-leaching from the carbonated K3 slag remained

  18. Results.

    ERIC Educational Resources Information Center

    Zemsky, Robert; Shaman, Susan; Shapiro, Daniel B.

    2001-01-01

    Describes the Collegiate Results Instrument (CRI), which measures a range of collegiate outcomes for alumni 6 years after graduation. The CRI was designed to target alumni from institutions across market segments and assess their values, abilities, work skills, occupations, and pursuit of lifelong learning. (EV)

  19. He-accreting white dwarfs: accretion regimes and final outcomes

    NASA Astrophysics Data System (ADS)

    Piersanti, L.; Tornambé, A.; Yungelson, L. R.

    2014-12-01

    The behaviour of carbon-oxygen (CO) white dwarfs (WDs) subject to direct helium accretion is extensively studied. We aim to analyse the thermal response of an accreting WD to mass deposition at different timescales. The analysis has been performed for initial WD masses and accretion rates in the range 0.60-1.02 M⊙ and 10-9-10-5 M⊙ yr-1, respectively. Thermal regimes in the parameter space MWD-dot{M}_He leading to formation of red-giant-like structures, steady burning of He, and mild, strong and dynamical flashes have been identified and the transition between these regimes has been studied in detail. In particular, the physical properties of WDs experiencing the He-flash accretion regime have been investigated to determine the mass retention efficiency as a function of the accretor total mass and accretion rate. We also discuss to what extent the building up of a He-rich layer via H burning could be described according to the behaviour of models accreting He-rich matter directly. Polynomial fits to the obtained results are provided for use in binary population synthesis computations. Several applications for close binary systems with He-rich donors and CO WD accretors are considered and the relevance of the results for interpreting He novae is discussed.

  20. The measurement results of carbon ion beam structure extracted by bent crystal from U-70 accelerator

    NASA Astrophysics Data System (ADS)

    Afonin, A. G.; Barnov, E. V.; Britvich, G. I.; Chesnokov, Yu A.; Chirkov, P. N.; Durum, A. A.; Kostin, M. Yu; Maisheev, V. A.; Pitalev, V. I.; Reshetnikov, S. F.; Yanovich, A. A.; Nazhmudinov, R. M.; Kubankin, A. S.; Shchagin, A. V.

    2016-07-01

    The carbon ion +6C beam with energy 25 GeV/nucleon was extracted by bent crystal from the U-70 ring. The bent angle of silicon crystal was 85 mrad. About 2×105 particles for 109 circulated ions in the ring were observed in beam line 4a after bent crystal. Geometrical parameters, time structure and ion beam structure were measured. The ability of the bent monocrystal to extract and generate ion beam with necessary parameters for regular usage in physical experiments is shown in the first time.

  1. Translaminar fracture toughness test methods and results from interlaboratory tests of carbon/epoxy laminates

    SciTech Connect

    Underwood, J.H.; Kortschot, M.T.; Lloyd, W.R.; Eidinoff, H.L.; Wilson, D.A.; Ashbaugh, N.

    1995-12-31

    Fracture tests were performed with carbon/polymer laminates and analyzed for the purpose of developing translaminar fracture toughness test and analysis procedures. Notched specimens were tested of two types of symmetrical layups--quasi-isotropic [0/45/90] and [0/90]; two carbon fiber/epoxy materials--a relatively brittle T300 fiber/976 epoxy and a tougher AS4 fiber/977-2 epoxy; two laminate thicknesses--2 mm and 4 mm; and three specimen configurations--the standard three-point bend and compact configurations, and an extended compact specimen with arm-height to specimen-width ratio of 1.9. Stress and displacement expressions were obtained for the extended compact specimen, including those for stress intensity factor, K, and crack mouth opening displacement, V, in terms of relative notch length, a/W, and for a/W in terms of V. Relationships for the bending stresses that control self-similar and off-axis cracking for the extended compact specimen were derived.

  2. Diagenesis of bank margin carbonates monitors glacio-eustacy: modeling and core study results

    SciTech Connect

    Matthews, R.K.; Al-Saqri, K.; Frohlich, C.

    1985-01-01

    Subsiding bank margin carbonates provide a monitoring system for high frequency sea level fluctuations. When sea level rises, new reefs and skeletal sands accumulate to near high-stand sea level. When sea level falls, subaerial exposure and related meteoric and mixed water diagenesis rapidly impart their mineralogic, isotopic, chemical, and petrographic signature on the strata. The authors model the interaction of fluctuating sea level (Milankovitch frequencies) and subsiding bank margin carbonates. Characteristic diagenetic lithologies occur seemingly randomly interbedded and unrelatable to specific subaerial exposure surfaces. This is similar to the pattern observed in Eocene bank margin skeletal sands of Kirkuk Field, Iraq. Meteoric diagenesis dominates the upper 35 meters of the authors core. The next 85 meters contain randomly alternating beds of meteoric limestone, mixed water dolomite, and limestone with well-preserved skeletal grains. This sequence is consistent with rapid glacio-eustatic fluctuations of Late Eocene sea level followed by a 35 to 50 meter glacio-eustatic lowering of average sea level at or near Eocene/Oligocene boundary.

  3. A methodology for elemental and organic carbon emission inventory and results for Lombardy region, Italy.

    PubMed

    Caserini, Stefano; Galante, Silvia; Ozgen, Senem; Cucco, Sara; de Gregorio, Katia; Moretti, Marco

    2013-04-15

    This paper presents a methodology and its application for the compilation of elemental carbon (EC) and organic carbon (OC) emission inventories. The methodology consists of the estimation of EC and OC emissions from available total suspended particulate matter (TSP) emission inventory data using EC and OC abundances in TSP derived from an extensive literature review, by taking into account the local technological context. In particular, the method is applied to the 2008 emissions of Lombardy region, Italy, considering 148 different activities and 30 types of fuels, typical of Western Europe. The abundances estimated in this study may provide a useful basis to assess the emissions also in other emission contexts with similar prevailing sources and technologies. The dominant sources of EC and OC in Lombardy are diesel vehicles for EC and the residential wood combustion (RWC) for OC which together account for about 83% of the total emissions of both pollutants. The EC and OC emissions from industrial processes and other fuel (e.g., gasoline, kerosene and LPG) combustion are significantly lower, while non-combustion sources give an almost negligible contribution. Total EC+OC contribution to regional greenhouse gas emissions is positive for every sector assuming whichever GWP100 value within the range proposed in literature. An uncertainty assessment is performed through a Monte Carlo simulation for RWC, showing a large uncertainty range (280% of the mean value for EC and 70% for OC), whereas for road transport a qualitative analysis identified a narrower range of uncertainty. PMID:23454906

  4. Health effects of carbon-containing particulate matter: focus on sources and recent research program results.

    PubMed

    Rohr, Annette; McDonald, Jacob

    2016-02-01

    Air pollution is a complex mixture of gas-, vapor-, and particulate-phase materials comprised of inorganic and organic species. Many of these components have been associated with adverse health effects in epidemiological and toxicological studies, including a broad spectrum of carbonaceous atmospheric components. This paper reviews recent literature on the health impacts of organic aerosols, with a focus on specific sources of organic material; it is not intended to be a comprehensive review of all the available literature. Specific emission sources reviewed include engine emissions, wood/biomass combustion emissions, biogenic emissions and secondary organic aerosol (SOA), resuspended road dust, tire and brake wear, and cooking emissions. In addition, recent findings from large toxicological and epidemiological research programs are reviewed in the context of organic PM, including SPHERES, NPACT, NERC, ACES, and TERESA. A review of the extant literature suggests that there are clear health impacts from emissions containing carbon-containing PM, but difficulty remains in apportioning responses to certain groupings of carbonaceous materials, such as organic and elemental carbon, condensed and gas phases, and primary and secondary material. More focused epidemiological and toxicological studies, including increased characterization of organic materials, would increase understanding of this issue. PMID:26635181

  5. Results of a European interlaboratory comparison on CO2 sorption on activated carbon and coals

    NASA Astrophysics Data System (ADS)

    Gensterblum, Yves; Busch, Andreas; Krooss, Bernhard; de Weireld, Guy; Billemont, Pierre; van Hemert, Patrick; Wolf, Karl-Heinz

    2013-04-01

    For the assessment of CO2 storage in coal seams or enhanced coalbed methane production (ECBM), the sorption properties of natural coals are important parameters. Since more and more laboratories worldwide are concerned with measurements of gas sorption on coal it is indispensable to establish quality standards for such experiments. The first two interlaboratory studies on CO2 sorption on coal (Goodman et al. 2004, 2007) revealed a poor agreement of sorption isotherms among the participating laboratories, particularly in the high-pressure range. During the MOVECBM (http://www.movecbm.eu/) project funded by the European Commission (6th framework), an interlaboratory comparison of CO2 sorption on selected coals and activated carbon was initiated. Measurements were performed on dry samples at 45° C using the manometric and the gravimetric method. up to a final pressure of 15 MPa. The first set of high-pressure sorption measurements was performed on a Filtrasorb 400 activated carbon sample in order to minimise heterogeneity effects and to optimize the experimental procedures for the individual (manometric or gravimetric) methods (Gensterblum et al. 2009). Since comparability for the activated carbon was excellent, the measurements were continued using natural coals of various rank (anthracite, bituminous coal and lignite) to study the influence of heterogeneities and varying starting conditions on the CO2 sorption properties (Gensterblum et al. 2010). Compared to the poor reproducibility observed in previous interlaboratory studies (Goodman et al., 2004, 2007) this European study showed excellent agreement (<5 % deviation) among the participating laboratories with good repeatability. The sorption data and technical information on the different experimental setups have been used to investigate errors and potential pitfalls in the assessment of high-pressure CO2 sorption isotherms. References Gensterblum Y., P. van Hemert, P. Billemont, A. Busch, B.M. Krooss, G. de

  6. Dynamic Treatment Regimes

    PubMed Central

    Chakraborty, Bibhas; Murphy, Susan A.

    2014-01-01

    A dynamic treatment regime consists of a sequence of decision rules, one per stage of intervention, that dictate how to individualize treatments to patients based on evolving treatment and covariate history. These regimes are particularly useful for managing chronic disorders, and fit well into the larger paradigm of personalized medicine. They provide one way to operationalize a clinical decision support system. Statistics plays a key role in the construction of evidence-based dynamic treatment regimes – informing best study design as well as efficient estimation and valid inference. Due to the many novel methodological challenges it offers, this area has been growing in popularity among statisticians in recent years. In this article, we review the key developments in this exciting field of research. In particular, we discuss the sequential multiple assignment randomized trial designs, estimation techniques like Q-learning and marginal structural models, and several inference techniques designed to address the associated non-standard asymptotics. We reference software, whenever available. We also outline some important future directions. PMID:25401119

  7. Climate change impacts on the vegetation carbon cycle of the Iberian Peninsula—Intercomparison of CMIP5 results

    NASA Astrophysics Data System (ADS)

    Aparício, Sara; Carvalhais, Nuno; Seixas, Júlia

    2015-04-01

    The vulnerability of a water-limited region like the Iberian Peninsula (IP) to climate changes drives a great concern and interest in understanding its impacts on the carbon cycle, namely, in terms of biomass production. This study assesses the effects of climate change and rising CO2 on forest growth, carbon sequestration, and water-use efficiency on the IP by late 21st century using 12 models from the CMIP5 project (Coupled Model Intercomparison Project Phase 5). We find a strong agreement among the models under representative concentration pathway 4.5 (RCP4.5) scenario, mostly regarding projected forest growth and increased primary production (13, 9% of gross primary production (GPP) increase projected by the models ensemble). Under RCP8.5 scenario, the results are less conclusive, as seven models project both GPP and net primary production to increase (up to 83% and 69%, respectively), while the remaining four models project the IP as a potential carbon source by late century. Divergences in carbon mass in wood predictions could be attributed to model structures, such as the N cycle, land model component, land cover data and parameterization, and distinct clusters of Earth System Models (ESMs). ESMs divergences in carbon feedbacks are likely being highly impacted by parameterization divergences and susceptibility to climate change and CO2 fertilization effect. Despite projected rainfall reductions, we observe a strong agreement between models regarding the increase of water-use efficiency (by 21% and 34%) under RCP4.5 and RCP8.5, respectively. Results suggest that rising CO2 has the potential to partially alleviate the adverse effects of drought.

  8. Microbial Growth and Air Pollutants in the Corrosion of Carbonate Rocks: Results from Laboratory and Outdoor Experimental Tests

    NASA Astrophysics Data System (ADS)

    Moroni, B.; Poli, G.; Pitzurra, L.

    2003-04-01

    Microorganisms and atmospheric pollution are primary causes of deterioration of materials exposed to open air. Due to the variety of chemical-mineralogical compositions and textures, stone represents a variegated substrate that interacts with environmental fluids and particulate, and is a selective environment for biological proliferation. Carbonate rocks, in particular, are highly exposed to environmental decay and extremely susceptible to acid attack caused by atmospheric pollutants and metabolic acid production. The aim of this work is to study the combined effect of microbial contamination and atmospheric pollutants in the weathering of carbonate rocks by means of laboratory and outdoor exposure tests. Laboratory experiments performed on carbonate rocks allowed evaluation of the influence of the gas mixture in the chemical modifications of the lithic substrate, and formulation of a kinetic model of sulphation. The obtained results suggest that nucleation alternates with growth as leading processes in the development of sulphation. In particular, nucleation of the reaction products is the leading process in the initial period of sulphation, which is characterized by a marked slowdown of the reaction progress, whereas growth of the products is the leading process in the subsequent period of resumption of sulphation. In situ experiments performed by exposing limestone specimens at two air monitoring stations in Perugia with different degrees of urban air pollution showed high levels of fungal colonization at early times and the presence of weathering products (i.e. gypsum) in the longer term. Results point to a combined effect of microbial colonization and atmospheric pollutants in promoting the weathering of stone through acid attack within the film of water present on the surface of the exposed material, and through the oxidation of metal sulphide particulate pollutant to sulphate. Laboratory tests assaying the extent of fungal colonization and/or chemical

  9. Preliminary Results from the NASA Orbiting Carbon Observatory-2 (OCO-2)

    NASA Astrophysics Data System (ADS)

    Crisp, D.; Eldering, A.; Gunson, M. R.

    2014-12-01

    The NASA Orbiting Carbon Observatory - 2 (OCO-2) was successfully launched from Vandenberg Air Force Base at 9:56:44 UTC on July 2, 2014. After a series of spacecraft checkout activities and orbit raising maneuvers, OCO-2 was inserted at the front of the 705-km Afternoon constellation (A-Train) on August 3rd. This presentation will summarize the science objectives, review the measurement approach, and introduce some preliminary data from the first few months of operation. OCO-2 was designed to return estimates of the column-averaged atmospheric carbon dioxide (CO2) dry air mole fraction (XCO2) with the precision, resolution, and coverage needed to quantify CO2 surface fluxes on regional scales. To meet these goals, it carries and points a 3-channel grating spectrometer that collects high resolution, co-bore-sighted spectra of reflected sunlight in the 765 nm O2 A-band and in the CO2 bands centered near 1610 and 2060 nm. Each channel records 24 spectra per second along a narrow (< 0.8-degree) track, returning about one million soundings each day. At least 10% of these soundings are expected to be sufficiently cloud free to yield full-column estimates of XCO2with single-sounding accuracies of 0.25 % on regional scales at monthly intervals. The instrument is calibrated using on-board sources and targets, the Moon, well-characterized surface sites (Pollock et al. this session), and comparisons with nearly-coincident observations from the Japanese Greenhouse gases Observing SATellite (GOSAT; Kuze et al. this session). Cloudy soundings are identified and screened out (Taylor et al. this session) and the remaining soundings are analyzed to yield spatially-resolved estimates of XCO2 and other geophysical products (c.f. Frankenberg et al. this session). OCO-2 XCO2 estimates are then validated against those from the Total Carbon Column Observing Network (TCCON) to assess their accuracy and precision (Wennberg et al. this session). Preliminary products from each step of this

  10. Gas flaring and resultant air pollution: A review focusing on black carbon.

    PubMed

    Fawole, Olusegun G; Cai, X-M; MacKenzie, A R

    2016-09-01

    Gas flaring is a prominent source of VOCs, CO, CO2, SO2, PAH, NOX and soot (black carbon), all of which are important pollutants which interact, directly and indirectly, in the Earth's climatic processes. Globally, over 130 billion cubic metres of gas are flared annually. We review the contribution of gas flaring to air pollution on local, regional and global scales, with special emphasis on black carbon (BC, "soot"). The temporal and spatial characteristics of gas flaring distinguishes it from mobile combustion sources (transport), while the open-flame nature of gas flaring distinguishes it from industrial point-sources; the high temperature, flame control, and spatial compactness distinguishes gas flaring from both biomass burning and domestic fuel-use. All of these distinguishing factors influence the quantity and characteristics of BC production from gas flaring, so that it is important to consider this source separately in emissions inventories and environmental field studies. Estimate of the yield of pollutants from gas flaring have, to date, paid little or no attention to the emission of BC with the assumption often being made that flaring produces a smokeless flame. In gas flares, soot yield is known to depend on a number of factors, and there is a need to develop emission estimates and modelling frameworks that take these factors into consideration. Hence, emission inventories, especially of the soot yield from gas flaring should give adequate consideration to the variation of fuel gas composition, and to combustion characteristics, which are strong determinants of the nature and quantity of pollutants emitted. The buoyant nature of gas flaring plume, often at temperatures in the range of 2000 K, coupled with the height of the stack enables some of the pollutants to escape further into the free troposphere aiding their long-range transport, which is often not well-captured by model studies. PMID:27262132

  11. Cryogenic cave carbonates as an archive of Late Pleistocene permafrost in the Ural Mountains: preliminary results

    NASA Astrophysics Data System (ADS)

    Dublyansky, Yuri; Kadebskaya, Olga; Cheng, Hai; Luetscher, Mark; Spötl, Christoph

    2015-04-01

    A specific type of cave deposits, cryogenic cave carbonates (CCCs), was discovered in the late 1980s in several caves of Central Europe. Unlike 'common' speleothems that form primarily due to degassing of CO2 from Ca2+ and HCO3- -rich waters, CCCs form by freezing-induced segregation (Žák et al., 2004). The formation of CCCs, hence, requires the presence of both liquid water and freezing temperatures. The latter combination may occur in caves in two situations: (1) freezing-thawing cycles in cave entrance zones; and (2) degrading permafrost conditions, when the active layer reaches the cave ceiling, whilst the deeper parts of the cave remain frozen. The latter situation is associated with a particular type of CCCs, which can be used as a marker for permafrost conditions. Because cave carbonates can be accurately dated using the U/Th method, CCCs may be used to identify events of (degrading) palaeo-permafrost conditions. In this study, CCCs were identified and sampled in four caves, located along a 1000 km-long transect from the northern to the southern Ural Associating the CCCs to permafrost conditions was possible on the basis of field observations (locations deep inside the cave, far from entrance zones) and stable isotope properties (strongly depleted δ18O values, inverse correlation between δ18O and δ13C). Chaikovskiy et al. (2014) reported five U/Th analyses of CCC from three caves: 16.7 ka and 104.8 ka (Divja Cave, northern Ural); and 13.4 ka, 86.5 ka and 125.3 ka (Rossijskaya and Usvinskaya Caves, central Ural). In this study we report 25 additional U/Th ages from northern and central Ural, as well as the first CCC age from southern Ural (Shulgan-Tash Cave). Most of the younger ages (

  12. First results on stable isotopes in fluid inclusions in cryogenic carbonates from Ural Mountains (Russia)

    NASA Astrophysics Data System (ADS)

    Dublyansky, Yuri; Luetscher, Mark; Spötl, Christoph; Töchterle, Paul; Kadebskaya, Olga

    2015-04-01

    Cryogenic cave carbonates (CCC) were found in a number of caves in the Ural. In contrast to the CCC previously reported from Central Europe, the Uralian CCC have larger sizes (up to 4-5 cm), which allows for more detailed petrographic and geochemical studies. CCCs from Uralian caves commonly show spherulitic shapes due to crystal splitting, supporting the model of calcite precipitating in a freezing water pond. δ18O values of studied CCCs are lower by 1 to 14 o compared to noncryogenic speleothems of Pleistocene and Holocene age from the same caves. δ18O and δ13C values are inversely correlated and typically show a fractionation between the core and the rim of individual samples. These trends are similar to those reported for CCCs from European caves (Žák et al., 2004). Petrographic observations performed on doubly polished, 100-150 micron-thick sections revealed abundant fluid inclusions, trapped between fibres of the spherulites. Petrographic relationships suggest that these inclusions are primary. The isotopic composition of water trapped in fluid inclusions in CCCs from two caves was analyzed following mechanical crushing at 120 °C, cryo-trapping of released water, pyrolysis on glassy carbon at 1400 °C (TC/EA device; Thermo), and analysis of the evolved gases on an isotope ratio mass spectrometer (Delta V Advantage; Thermo Fisher). The lack of peaks on the m/z 2 trace during the heating of the loaded crushing cell attests for a good sealing of the fluid inclusions. The measured δD values range between -136 o and -145 o VSMOW. The values measured in CCCs are more negative than the typical values of fluid inclusion water measured in the Holocene stalagmites from central Ural (-99 to -108 ). This shift toward more negative values is attributed to the isotopic fractionation between ice and water during the freezing. Reference: Žák et al., 2004, Chemical Geology, 2006, 119-136.

  13. Black Carbon Emissions from In-use Ships: Results from CalNex 2010

    NASA Astrophysics Data System (ADS)

    Buffaloe, Gina Marise

    Black carbon (BC) mass emission factors (EFBC; g-BC (kg-fuel)--1) from a variety of ocean going vessels have been determined from measurements of BC and CO2 concentrations in ship plumes intercepted by the R/V Atlantis during the 2010 California Nexus (CalNex) campaign. The ships encountered were all operating within 24 nautical miles of the California coast and were utilizing relatively low sulphur fuels. Black carbon concentrations within the plumes, from which EFBC values are determined, were measured using four independent instruments: a photoacoustic spectrometer and a particle soot absorption photometer, which measure light absorption, and a single particle soot photometer and soot particle aerosol mass spectrometer, which measure the mass concentration of refractory BC directly. The measured EFBC have been divided into vessel type categories and engine type categories, from which averages have been determined. The geometric average EFBC, determined from over 71 vessels and 135 plumes encountered, was 0.31 g-BC (kg-fuel)--1. The most frequent engine type encountered was the slow speed diesel (SSD), and the most frequent SSD vessel type was the cargo ship sub-category. Average and median EF BC values from these two categories are compared to previous observations from the Texas Air Quality Study (TexAQS) in 2006, in which the ships encountered were predominately operating high sulphur fuels. There is some indication that the EFBC values for SSD vessels during CalNex were lower than during TexAQS, although ship-to-ship variability in these data sets makes it difficult to draw firm conclusions about the influence of fuel quality on EFBC.

  14. Carbon dioxide laser vaporization of the inferior turbinate for allergic rhinitis: short-term results.

    PubMed

    Imamura, Shun-ichi; Honda, Hideyuki

    2003-12-01

    Carbon dioxide laser vaporization of the turbinate has recently become accepted as a common treatment for allergic rhinitis. Usually, only a single procedure is applied to minimize trauma. However, repeated procedures on separate days are often required to achieve an adequate effect. Therefore, we attempted a new method of vaporization and evaluated the outcome, and also tried to determine which patients have good indications for laser treatment. To widely and deeply vaporize the inferior turbinate, we repeated the procedure 3 times in 1 session after removing the carbon coating from the previous vaporization under nasal endoscopic observation. After the procedure, most patients experienced complete nasal obstruction for 2 or 3 days, but there was no intraoperative or postoperative bleeding or severe pain. All patients obtained improvement of their chief complaints and were satisfied 2 months after the operation. In particular, 60% of the patients were completely relieved of refractory nasal obstruction. Most patients were more satisfied with the effects than are those treated by the usual methods. Completely successful cases (improvement in all symptoms and complete satisfaction obtained) were selected and were compared with other cases. Favorable prognostic factors are more severe complaints, longer symptomatic periods, stronger allergic reactions, and worse nasal resistance and its greater improvement with administration of decongestant nasal drops. This method may be especially accepted by patients with severe complaints, in particular nasal obstruction, who do not experience enough relief with conservative therapies or have enough time to make frequent visits to an outpatient clinic over a period of several weeks. PMID:14703108

  15. A quantitative comparison of Soil Development in four climatic regimes

    USGS Publications Warehouse

    Harden, J.W.; Taylor, E.M.

    1983-01-01

    A new quantitative Soil Development Index based on field data has been applied to chronosequences formed under different climatic regimes. The four soil chronosequences, developed primarily on sandy deposits, have some numeric age control and are located in xeric-inland (Merced, Calif.), xeric-coastal (Ventura, Calif.), aridic (Las Cruces, N. Mex.), and udic (Susquehanna Valley, Pa.) soil-moisture regimes. To quantify field properties, points are assigned for developmental increases in soil properties in comparison to the parent material. Currently ten soil-field properties are quantified and normalized for each horizon in a given chronosequence, including two new properties for carbonate-rich soils in addition to the eight properties previously defined. When individual properties or the combined indexes are plotted as a function of numeric age, rates of soil development can be compared in different climates. The results demonstrate that (1) the Soil Development Index can be applied to very different soil types, (2) many field properties develop systematically in different climatic regimes, (3) certain properties appear to have similar rates of development in different climates, and (4) the Profile Index that combines different field properties increases significantly with age and appears to develop at similar rates in different climates. The Soil Development Index can serve as a preliminary guide to soil age where other age control is lacking and can be used to correlate deposits of different geographical and climatic regions. ?? 1983.

  16. Carbon, oxygen and biological productivity in the Southern Ocean in and out the Kerguelen plume: CARIOCA drifter results

    NASA Astrophysics Data System (ADS)

    Merlivat, L.; Boutin, J.; d'Ovidio, F.

    2014-12-01

    The Kerguelen Plateau region in the Indian sector of the Southern Ocean supports annually a large-scale phytoplankton bloom which is naturally fertilized with iron. As part of the second Kerguelen Ocean and Plateau compared Study expedition (KEOPS2) in austral spring (October-November 2011), one Carioca buoy was deployed east of the Kerguelen plateau. It drifted eastward downstream in the Kerguelen plume. Hourly surface measurements of pCO2, O2 and ancillary observations were collected between 1 November 2011 to 12 February 2012 with the aim of characterizing the spatial and temporal variability of the biological Net Community Production (NCP) downstream the Kerguelen plateau, assess the impact of iron-induced productivity on the biological carbon consumption and consequently on the CO2 flux exchanged at the air-sea interface. The trajectory of the buoy until mid-December was within the longitude range, 72-83° E, close to the polar front and then in the polar frontal zone, PFZ, until 97° E. From 17 November to 16 December, the buoy drifted within the Kerguelen plume following a filament carrying dissolved iron, DFe, for a total distance of 700 km. In the first part of the trajectory, the ocean surface waters are a sink for CO2 and a source for CO2, with fluxes of respective mean values equal to -8 and +38 mmol CO2 m-2 d-1. Eastward, as the buoy escapes the iron enriched filament, the fluxes are in opposite direction, with respective mean values of +5 and -48 mmol O2 m-2 d-1. These numbers clearly indicate the strong impact of biological processes on the biogeochemistry in the surface waters within the Kerguelen plume in November-mid-December, while it is undetectable eastward in the PFZ from mid-December to mid-February. While the buoy follows the Fe enriched filament, simultaneous observations of dissolved inorganic carbon, DIC, and dissolved oxygen, O2, highlight biological events lasting from 2 to 4 days. Stoichiometric ratios, O2/C, between 1.1 and 1.4 are

  17. [Factors influencing the spatial variability in soil respiration under different land use regimes].

    PubMed

    Chen, Shu-Tao; Liu, Qiao-Hui; Hu, Zheng-Hua; Liu, Yan; Ren, Jing-Quan; Xie, Wei

    2013-03-01

    In order to investigate the factors influencing the spatial variability in soil respiration under different land use regimes, field experiments were performed. Soil respiration and relevant environment, vegetation and soil factors were measured. The spatial variability in soil respiration and the relationship between soil respiration and these measured factors were investigated. Results indicated that land use regimes had significant effects on soil respiration. Soil respiration varied significantly (P < 0.001) among different land use regimes. Soil respiration rates ranged from 1.82 to 7.46 micromol x (m2 x s)(-1), with a difference of 5.62 micromol x (m2 x s)(-1) between the highest and lowest respiration rates. Soil organic carbon was a key factor controlling the spatial variability in soil respiration. In all, ecosystems studied, the relationship between soil respiration and soil organic carbon content can be described by a power function. Soil respiration increased with the increase of soil organic carbon. In forest ecosystem, the relationship between soil respiration and diameter at breast height (DBH) of trees can be explained by a natural logarithmic function. A model composed of soil organic carbon (C, %), available phosphorous (AP, g x kg(-1)) and diameter at breast height (DBH, cm) explained 92.8% spatial variability in soil respiration for forest ecosystems. PMID:23745410

  18. The relationship between void waves and flow regime transition

    SciTech Connect

    Lahey, R.T. Jr.; Drew, D.A.; Kalkach-Navarro, S.; Park, J.W.

    1992-12-31

    The results of an extensive experimental and analytical study on the relationship between void waves and flow regime transition are presented, in particular, the bubbly/slug flow regime transition. It is shown that void wave instability signals a flow regime transition.

  19. Carbon and hydrogen isotopic compositions of stratospheric methane: 2. Two-dimensional model results and implications for kinetic isotope effects

    NASA Astrophysics Data System (ADS)

    McCarthy, M. C.; Boering, K. A.; Rice, A. L.; Tyler, S. C.; Connell, P.; Atlas, E.

    2003-08-01

    New high-precision measurements of the carbon and hydrogen isotopic compositions of stratospheric CH4 made on whole air samples collected aboard the NASA ER-2 aircraft are compared with results from the Lawrence Livermore National Laboratory 2-D model. Model runs incorporating sets of experimentally determined kinetic isotope effects (KIEs) for the reactions of CH4 with each of the oxidants OH, O(1D), and Cl are examined with the goals of determining (1) how well the 2-D model can reproduce the observations for both the carbon and hydrogen isotopic compositions, (2) what factors are responsible for the observed increase in the apparent isotopic fractionation factors with decreasing methane mixing ratios, and (3) how sensitive the modeled isotopic compositions are to various experimentally determined KIEs. Bound by estimates of the effects of uncertainties in model chemistry and transport on isotopic compositions, we then examine the constraints the ER-2 observations place on values for the KIEs. For the carbon KIE for reaction of CH4 with O(1D), for example, the analysis of model results and observations favors the larger of the experimental values, 1.013, over a value of 1.001. These analyses also suggest that intercomparisons of results from different models using a given set of KIEs may be useful as a new diagnostic of model-model differences in integrated chemistry and transport.

  20. Changes in Snow Albedo Resulting from Snow Darkening Caused by Black Carbon

    NASA Astrophysics Data System (ADS)

    Engels, J.; Kloster, S.; Bourgeois, Q.

    2014-12-01

    We investigate the potential impact of snow darkening caused by pre-industrial and present-day black carbon (BC) emissions on snow albedo and subsequently climate. To assess this impact, we implemented the effect of snow darkening caused by BC emitted from natural as well as anthropogenic sources into the Max Planck Institute for Meteorology Earth System Model (MPI-M ESM). Considerable amounts of BC are emitted e.g. from fires and are transported through the atmosphere for several days before being removed by rain or snow precipitation in snow covered regions. Already very small quantities of BC reduce the snow reflectance significantly, with consequences for snow melting and snow spatial coverage. We implemented the snow albedo reduction caused by BC contamination and snow aging in the one layer land surface component (JSBACH) of the atmospheric general circulation model ECHAM6, developed at MPI-M. For this we used the single-layer simulator of the SNow, Ice, and Aerosol Radiation (SNICAR-Online (Flanner et al., 2007); http://snow.engin.umich.edu) model to derive snow albedo values for BC in snow concentrations ranging between 0 and 1500 ng(BC)/g(snow) for different snow grain sizes for the visible (0.3 - 0.7 μm) and near infrared range (0.7 - 1.5 μm). As snow grains grow over time, we assign different snow ages to different snow grain sizes (50, 150, 500, and 1000 μm). Here, a radius of 50 μm corresponds to new snow, whereas a radius of 1000 μm corresponds to old snow. The deposition rates of BC on snow are prescribed from previous ECHAM6-HAM simulations for two time periods, pre-industrial (1880-1889) and present-day (2000-2009), respectively. We perform a sensitivity study regarding the scavenging of BC by snow melt. To evaluate the newly implemented albedo scheme we will compare the modeled black carbon in snow concentrations to observed ones. Moreover, we will show the impact of the BC contamination and snow aging on the simulated snow albedo. The

  1. Spatial Variation in Carbon Release From Arctic Tundra Resulting From Microtopography Created by Permafrost Thawing

    NASA Astrophysics Data System (ADS)

    Lee, H.; Schuur, E. A.; Vogel, J. G.

    2007-12-01

    One of the biggest potential feedbacks to global climate change from high latitude ecosystems may come from thawing of permafrost, which stores 30% of the total global terrestrial soil organic carbon (SOC). Thawing of permafrost may accelerate decomposition of soil organic matter (SOM) and increase carbon dioxide (CO2) emissions and such emissions from soil can lead to further warming in global scale. When permafrost thaws in ice-rich areas, it creates localized topographical surface subsidence called thermokarst, which can induce variations in soil abiotic properties. By altering multiple resources in soil, thermokarst can change C cycling in high latitude ecosystems beyond simple increases in temperature alone. The objective was to determine how thermokarst affects ecosystem C exchange. We hypothesized that there would be a positive relationship between the degree of ground subsidence and CO2 emissions from decomposition of SOM. This study was conducted in a tundra site near Denali National Park, Alaska. Three study sites were established according to the degree of surface depressions: Severe Thaw, Moderate Thaw, and Minimal Thaw. We established 50 equally spaced grid points each site and they were surveyed using GPS to measure the micro-elevation. Clear static chamber measurements were used to measure ecosystem C exchange, while soil properties such as temperature and volumetric water content (VWC) were measured simultaneously. Normalized Difference Vegetation Index (NDVI) was measured as an indicator of primary productivity. We used forward stepwise regression analysis to quantify how much microtopography explained ecosystem C exchange. There was a negative correlation between ecosystem respiration and relative elevation at the Severe and Minimal site. The best predictor variable for ecosystem C exchange was VWC alone, which was better than temperature alone, or mixed effects of temperature and VWC. There was no relationship between NDVI and microtopography

  2. Preliminary results on the effects of afforestation of maize soils with Populus alba L., on carbon metabolism

    NASA Astrophysics Data System (ADS)

    García-Campos, Elena; Zorita, Félix; Gil-Sotres, Fernando; Leirós, Mā Carmen; Trasar-Cepeda, Carmen

    2010-05-01

    Transformation of a natural soil to agricultural land is generally assumed to be accompanied by increased mineralization of the organic matter and increased CO2emissions; in contrast, afforestation of agricultural soil is thought to lead to sequestration of carbon and incorporation of atmospheric CO2 into the organic matter. In other words the type of management and land use determine whether soils act as carbon sinks or sources, so that transformation of agricultural land to forest land is generally considered to be accompanied by an increase in edaphic carbon, although it is not clear whether this effect is always produced or if it depends on the agricultural history of the land being afforested. In light of the recognised importance of forest land in sequestering C, and therefore in regulating climate change, in 1992 the EU established Regulation 2080 to promote the afforestation of marginal agricultural land. This had strong repercussions in regions such as Galicia (NW Spain) as the afforestation was mainly applied to good quality agricultural land rather than to marginal land. Although, as a result, large areas of agricultural land have been afforested in Galicia, the associated effects on edaphic carbon have not been widely investigated. The present study involves analysis of large number of afforested soils, planted with different trees and located in different areas throughout Galicia (NW Spain), with the aim of investigating the effects on carbon metabolism in agricultural soils transformed for forestry use. Here we report the preliminary results concerning the observed effects on carbon metabolism in six soils afforested with poplar, Populus alba L., of age between 4 and 8 years. In addition to the six soils planted with poplars, adjacent agricultural soils (x6) were analyzed. In each case the adjacent soil was the same as the original soil prior to afforestation, and all were maize soils. Samples of the soils were collected in autumn, after harvesting

  3. A new carbon monoxide occupational dosimeter: results from a worker exposure assessment survey.

    PubMed

    Apte, M G; Cox, D D; Hammond, S K; Gundel, L A

    1999-01-01

    The LBNL/QGI occupational carbon monoxide (CO) dosimeter (LOCD), a new, inexpensive CO passive sampler, was field-validated in an occupational exposure assessment study in the Moscone Convention Center (MCC) in San Francisco, CA in January, 1997. The LOCD measures time-weighed-average (TWA) CO exposures from 10 to 800 parts per million hours (ppm h; accuracy +/- 20%; precision 10 ppm h). This device represents a major improvement over currently available low-cost personal CO monitors. At the MCC, over 1000 workers set up and remove exhibitions. Forty propane-powered forklifts moved materials throughout the 42,000 m2 of exhibit halls. Diesel truck emissions enter the building via three internal underground loading docks. The LOCD was used to measure 154 worker exposures on 3 days. Sampler performance was compared to a standard method at 15 fixed sites. The geometric mean (GM) of all 154 exposures was 7 ppm (geometric standard deviation (GSD) = 1.6); 10% of the exposures was 10 ppm or more. Dock Walkers and Forklift Operators had the highest exposures (maximum = 34 ppm) with GM (GSD) of 9 (1.7) and 9 (1.6) ppm, respectively. Attendants and Installer/Decorators had the lowest exposures with GMs of 6 (1.6) and 7 (1.4), respectively. The Cal/OSHA personal exposure limit for CO is 25 ppm time-weighted average (TWA). PMID:10638840

  4. Experimental Results in Support of Simulating Progressive Crush in Carbon-Fiber Textile Composites

    SciTech Connect

    DeTeresa, S J; Allison, L M; Cunningham, B J; Freeman, DC; Saculla, M D; Sanchez, R J; Winchester, S W

    2001-04-02

    This report summarizes the findings of an experimental program conducted to support the modeling of the crush behavior of triaxial braid carbon fiber composites. The matrix material as well as braided panels and tubes were characterized in order to determine material properties, to assess failure modes, and to provide a test bed for new analytical and numerical tools developed specifically for braided composites. The matrix material selected by the ACC was an epoxy vinyl ester (Ashland Hetron 922). Tensile tests were used to compare two formulations-one used by the ACC and one recommended by the resin supplier. The latter was a faster reacting system and gelled in one-third the time of the ACC formulation. Both formulations had an average elongation at failure that was only half of the resin supplier's reported value. Only one specimen of each type came close to the reported elongation value and it was shown that failure invariably initiated at both surface and internal defects. Overall, the tensile properties of the two formulations were nearly identical, but those of the ACC system were more consistent. The properties of the ACC matrix formulation were measured in tension, shear, and compression and the average properties obtained in these tests are summarized.

  5. Measurements of Electrode Skin Impedances using Carbon Rubber Electrodes - First Results

    NASA Astrophysics Data System (ADS)

    Kaufmann, Steffen; Ardelt, Gunther; Ryschka, Martin

    2013-04-01

    Non-invasive bioimpedance measurement as a tool in biomedical engineering and life sciences allows conclusions about condition and composition of living tissue. For interfacing the electronic conduction of the instrumentation and the ionic conduction of the tissue, electrodes are needed. A crucial point is the uncertainty arising from the unknown, time-varying and current density depend Electrode Skin Impedance (ESI). This work presents ESI measurements using carbon rubber electrodes on different human test subjects. The measurements for this work are carried out by employing a high accuracy Bioimpedance Measurement System (BMS) developed by the authors group, which is based on a Field Programmable Gate Array (FPGA) System on Chip (SoC). The system is able to measure magnitude and phase of complex impedances using a two- or four-electrode setup, with excitation currents from 60 μA to 5 mA in a frequency range from about 10 kHz to 300 kHz. Achieved overall measurement uncertainties are below 1%.

  6. Effect of Carbon Ion Radiotherapy for Sacral Chordoma: Results of Phase I-II and Phase II Clinical Trials

    SciTech Connect

    Imai, Reiko; Kamada, Tadashi; Tsuji, Hiroshi; Sugawara, Shinji; Serizawa, Itsuko; Tsujii, Hirohiko; Tatezaki, Shin-ichiro

    2010-08-01

    Purpose: To summarize the results of treatment for sacral chordoma in Phase I-II and Phase II carbon ion radiotherapy trials for bone and soft-tissue sarcomas. Patients and Methods: We performed a retrospective analysis of 38 patients with medically unresectable sacral chordomas treated with the Heavy Ion Medical Accelerator in Chiba, Japan between 1996 and 2003. Of the 38 patients, 30 had not received previous treatment and 8 had locally recurrent tumor after previous resection. The applied carbon ion dose was 52.8-73.6 Gray equivalents (median, 70.4) in a total of 16 fixed fractions within 4 weeks. Results: The median patient age was 66 years. The cranial tumor extension was S2 or greater in 31 patients. The median clinical target volume was 523 cm{sup 3}. The median follow-up period was 80 months. The 5-year overall survival rate was 86%, and the 5-year local control rate was 89%. After treatment, 27 of 30 patients with primary tumor remained ambulatory with or without supportive devices. Two patients experienced severe skin or soft-tissue complications requiring skin grafts. Conclusion: Carbon ion radiotherapy appears effective and safe in the treatment of patients with sacral chordoma and offers a promising alternative to surgery.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  8. Ruthenium-bipyridine complexes bearing fullerene or carbon nanotubes: synthesis and impact of different carbon-based ligands on the resulting products.

    PubMed

    Wu, Zhen-yi; Huang, Rong-bin; Xie, Su-yuan; Zheng, Lan-sun

    2011-09-01

    This paper discusses the synthesis of two carbon-based pyridine ligands of fullerene pyrrolidine pyridine (C(60)-py) and multi-walled carbon nanotube pyrrolidine pyridine (MWCNT-py) via 1,3-dipolar cycloaddition. The two complexes, C(60)-Ru and MWCNT-Ru, were synthesized by ligand substitution in the presence of NH(4)PF(6), and Ru(II)(bpy)(2)Cl(2) was used as a reaction precursor. Both complexes were characterized by mass spectroscopy (MS), elemental analysis, nuclear magnetic resonance (NMR) spectroscopy, infrared spectroscopy (IR), ultraviolet/visible spectroscopy (UV-VIS) spectrometry, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and cyclic voltammetry (CV). The results showed that the substitution way of C(60)-py is different from that of MWCNT-py. The C(60)-py and a NH(3) replaced a Cl(-) and a bipyridine in Ru(II)(bpy)(2)Cl(2) to produce a five-coordinate complex of [Ru(bpy)(NH(3))(C(60)-py)Cl]PF(6), whereas MWCNT-py replaced a Cl(-) to generate a six-coordinate complex of [Ru(bpy)(2)(MWCNT-py)Cl]PF(6). The cyclic voltammetry study showed that the electron-withdrawing ability was different for C(60) and MWCNT. The C(60) showed a relatively stronger electron-withdrawing effect with respect to MWCNT. PMID:21769337

  9. Acid rain and weathering damage to carbonate building stone: Results of material loss measurements

    SciTech Connect

    Reddy, M.; Youngdahl, C.A.

    1987-01-01

    Marble and limestone specimens were exposed to atmospheric conditions at four eastern U.S. sites. A number of methods were employed for damage assessment; this paper describes the results of chemical and physical measurements of material loss. Good agreement was observed among results obtained with different methods. A rate of surface recession near 15 ..mu..m/y was observed for skyward surfaces of marble tested in North Carolina, and comparable results were obtained at the other test sites. Response of the porous limestone was assessed with greater difficulty; a rate of loss similar to that of marble was inferred. Initial correlations of material loss with environmental factors are briefly discussed.

  10. Acid rain and weathering damage to carbonate building stone: Results of material loss measurements

    SciTech Connect

    Reddy, M.M.; Youngdahl, C.A.

    1986-11-01

    Marble and limestone specimens were exposed to atmospheric conditions at four eastern US sites. A number of methods were employed for damage assessment; this paper describes the results of chemical and physical measurements of material loss. Good agreement was observed among results obtained with different methods. A rate of surface recession near 15 ..mu..m/y was observed for skyward surfaces of marble tested in North Carolina, and comparable results were obtained at the other test sites. Response of the porous limestone was assessed with greater difficulty; a rate of loss similar to that of marble was inferred. Initial correlations of material loss with environmental factors are briefly discussed.