Differential controls on soil carbon density and mineralization among contrasting forest types in a temperate forest ecosystem

PubMed Central

You, Ye-Ming; Wang, Juan; Sun, Xiao-Lu; Tang, Zuo-Xin; Zhou, Zhi-Yong; Sun, Osbert Jianxin

2016-01-01

Understanding the controls on soil carbon dynamics is crucial for modeling responses of ecosystem carbon balance to global change, yet few studies provide explicit knowledge on the direct and indirect effects of forest stands on soil carbon via microbial processes. We investigated tree species, soil, and site factors in relation to soil carbon density and mineralization in a temperate forest of central China. We found that soil microbial biomass and community structure, extracellular enzyme activities, and most of the site factors studied varied significantly across contrasting forest types, and that the associations between activities of soil extracellular enzymes and microbial community structure appeared to be weak and inconsistent across forest types, implicating complex mechanisms in the microbial regulation of soil carbon metabolism in relation to tree species. Overall, variations in soil carbon density and mineralization are predominantly accounted for by shared effects of tree species, soil, microclimate, and microbial traits rather than the individual effects of the four categories of factors. Our findings point to differential controls on soil carbon density and mineralization among contrasting forest types and highlight the challenge to incorporate microbial processes for constraining soil carbon dynamics in global carbon cycle models. PMID:26925871

Changes in agricultural carbon emissions and factors that influence agricultural carbon emissions based on different stages in Xinjiang, China.

PubMed

Xiong, Chuanhe; Yang, Degang; Xia, Fuqiang; Huo, Jinwei

2016-11-10

Xinjiang's agricultural carbon emissions showed three stages of change, i.e., continued to rise, declined and continued to rise, during 1991-2014. The agriculture belonged to the "low emissions and high efficiency" agriculture category, with a lower agricultural carbon emission intensity. By using the logarithmic mean divisia index decomposition method, agricultural carbon emissions were decomposed into an efficiency factor, a structure factor, an economy factor, and a labour factor. We divided the study period into five stages based on the changes in efficiency factor and economy factor. Xinjiang showed different agricultural carbon emission characteristics at different stages. The degree of impact on agricultural carbon emissions at these stages depended on the combined effect of planting-animal husbandry carbon intensity and agricultural labour productivity. The economy factor was the critical factor to promote the increase in agricultural carbon emissions, while the main inhibiting factor for agricultural carbon emissions was the efficiency factor. The labour factor became more and more obvious in increasing agricultural carbon emissions. Finally, we discuss policy recommendations in terms of the main factors, including the development of agricultural science and technology (S&T), the establishment of three major mechanisms and transfer of rural labour in ethnic areas.

Changes in agricultural carbon emissions and factors that influence agricultural carbon emissions based on different stages in Xinjiang, China

NASA Astrophysics Data System (ADS)

Xiong, Chuanhe; Yang, Degang; Xia, Fuqiang; Huo, Jinwei

2016-11-01

Xinjiang’s agricultural carbon emissions showed three stages of change, i.e., continued to rise, declined and continued to rise, during 1991-2014. The agriculture belonged to the “low emissions and high efficiency” agriculture category, with a lower agricultural carbon emission intensity. By using the logarithmic mean divisia index decomposition method, agricultural carbon emissions were decomposed into an efficiency factor, a structure factor, an economy factor, and a labour factor. We divided the study period into five stages based on the changes in efficiency factor and economy factor. Xinjiang showed different agricultural carbon emission characteristics at different stages. The degree of impact on agricultural carbon emissions at these stages depended on the combined effect of planting-animal husbandry carbon intensity and agricultural labour productivity. The economy factor was the critical factor to promote the increase in agricultural carbon emissions, while the main inhibiting factor for agricultural carbon emissions was the efficiency factor. The labour factor became more and more obvious in increasing agricultural carbon emissions. Finally, we discuss policy recommendations in terms of the main factors, including the development of agricultural science and technology (S&T), the establishment of three major mechanisms and transfer of rural labour in ethnic areas.

Changes in agricultural carbon emissions and factors that influence agricultural carbon emissions based on different stages in Xinjiang, China

PubMed Central

Xiong, Chuanhe; Yang, Degang; Xia, Fuqiang; Huo, Jinwei

2016-01-01

Xinjiang’s agricultural carbon emissions showed three stages of change, i.e., continued to rise, declined and continued to rise, during 1991–2014. The agriculture belonged to the “low emissions and high efficiency” agriculture category, with a lower agricultural carbon emission intensity. By using the logarithmic mean divisia index decomposition method, agricultural carbon emissions were decomposed into an efficiency factor, a structure factor, an economy factor, and a labour factor. We divided the study period into five stages based on the changes in efficiency factor and economy factor. Xinjiang showed different agricultural carbon emission characteristics at different stages. The degree of impact on agricultural carbon emissions at these stages depended on the combined effect of planting-animal husbandry carbon intensity and agricultural labour productivity. The economy factor was the critical factor to promote the increase in agricultural carbon emissions, while the main inhibiting factor for agricultural carbon emissions was the efficiency factor. The labour factor became more and more obvious in increasing agricultural carbon emissions. Finally, we discuss policy recommendations in terms of the main factors, including the development of agricultural science and technology (S&T), the establishment of three major mechanisms and transfer of rural labour in ethnic areas. PMID:27830739

Spatial variation in microbial processes controlling carbon mineralization within soils and sediments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fendorf, Scott; Kleber, Markus; Nico, Peter

Soils have a defining role in global carbon cycling, having one of the largest dynamic stocks of C on earth—3300 Pg of C are stored in soils, which is three-times the amount stored in the atmosphere and more than the terrestrial land plants. An important control on soil organic matter (SOM) quantities is the mineralization rate. It is well recognized that the rate and extent of SOM mineralization is affected by climatic factors and mineral-organic matter associations. What remained elusive is to what extent constraints on microbial metabolism induced by the respiratory pathway, and specifically the electron acceptor in respiration,more » control overall rates of carbon mineralization in soils. Therefore, physical factors limiting oxygen diffusion such as soil texture and aggregate size (soil structure) may therefore be central controls on C mineralization rates. The goal of our research was therefore to determine if variations in microbial metabolic rates induced by anaerobic microsites in soils are a major control on SOM mineralization rates and thus storage. We performed a combination of laboratory experiments and field investigations will be performed to fulfill our research objectives. We used laboratory studies to examine fundamental factors of respiratory constraints (i.e., electron acceptor) on organic matter mineralization rates. We ground our laboratory studies with both manipulation of field samples and in-field measurements. Selection of the field sites is guided by variation in soil texture and structure while having (other environmental/soil factors constant. Our laboratory studies defined redox gradients and variations in microbial metabolism operating at the aggregate-scale (cm-scale) within soils using a novel constructed diffusion reactor. We further examined micro-scale variation in terminal electron accepting processes and resulting C mineralization rates within re-packed soils. A major outcome of our research is the ability to quantitatively

40 CFR 52.785 - Control strategy: Carbon monoxide.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 3 2010-07-01 2010-07-01 false Control strategy: Carbon monoxide. 52... (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS Indiana § 52.785 Control strategy: Carbon... for attainment and maintenance of the national standards for carbon monoxide in the Metropolitan...

40 CFR 52.349 - Control strategy: Carbon monoxide.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 3 2010-07-01 2010-07-01 false Control strategy: Carbon monoxide. 52... (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS Colorado § 52.349 Control strategy: Carbon monoxide. (a) Revisions to the Colorado State Implementation Plan, Carbon Monoxide Redesignation Request...

Space-Time Controls on Carbon Sequestration Over Large-Scale Amazon Basin

NASA Technical Reports Server (NTRS)

Smith, Eric A.; Cooper, Harry J.; Gu, Jiujing; Grose, Andrew; Norman, John; daRocha, Humberto R.; Starr, David O. (Technical Monitor)

2002-01-01

A major research focus of the LBA Ecology Program is an assessment of the carbon budget and the carbon sequestering capacity of the large scale forest-pasture system that dominates the Amazonia landscape, and its time-space heterogeneity manifest in carbon fluxes across the large scale Amazon basin ecosystem. Quantification of these processes requires a combination of in situ measurements, remotely sensed measurements from space, and a realistically forced hydrometeorological model coupled to a carbon assimilation model, capable of simulating details within the surface energy and water budgets along with the principle modes of photosynthesis and respiration. Here we describe the results of an investigation concerning the space-time controls of carbon sources and sinks distributed over the large scale Amazon basin. The results are derived from a carbon-water-energy budget retrieval system for the large scale Amazon basin, which uses a coupled carbon assimilation-hydrometeorological model as an integrating system, forced by both in situ meteorological measurements and remotely sensed radiation fluxes and precipitation retrieval retrieved from a combination of GOES, SSM/I, TOMS, and TRMM satellite measurements. Brief discussion concerning validation of (a) retrieved surface radiation fluxes and precipitation based on 30-min averaged surface measurements taken at Ji-Parana in Rondonia and Manaus in Amazonas, and (b) modeled carbon fluxes based on tower CO2 flux measurements taken at Reserva Jaru, Manaus and Fazenda Nossa Senhora. The space-time controls on carbon sequestration are partitioned into sets of factors classified by: (1) above canopy meteorology, (2) incoming surface radiation, (3) precipitation interception, and (4) indigenous stomatal processes varied over the different land covers of pristine rainforest, partially, and fully logged rainforests, and pasture lands. These are the principle meteorological, thermodynamical, hydrological, and biophysical

40 CFR 52.376 - Control strategy: Carbon monoxide.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 3 2010-07-01 2010-07-01 false Control strategy: Carbon monoxide. 52... (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS Connecticut § 52.376 Control strategy: Carbon... submitted a revision to the carbon monoxide State Implementation Plan for the 1990 base year emission...

40 CFR 52.376 - Control strategy: Carbon monoxide.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 3 2013-07-01 2013-07-01 false Control strategy: Carbon monoxide. 52... (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS Connecticut § 52.376 Control strategy: Carbon... submitted a revision to the carbon monoxide State Implementation Plan for the 1990 base year emission...

40 CFR 52.376 - Control strategy: Carbon monoxide.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 3 2014-07-01 2014-07-01 false Control strategy: Carbon monoxide. 52... (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS Connecticut § 52.376 Control strategy: Carbon... submitted a revision to the carbon monoxide State Implementation Plan for the 1990 base year emission...

40 CFR 52.376 - Control strategy: Carbon monoxide.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 3 2011-07-01 2011-07-01 false Control strategy: Carbon monoxide. 52... (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS Connecticut § 52.376 Control strategy: Carbon... submitted a revision to the carbon monoxide State Implementation Plan for the 1990 base year emission...

40 CFR 52.376 - Control strategy: Carbon monoxide.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 3 2012-07-01 2012-07-01 false Control strategy: Carbon monoxide. 52... (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS Connecticut § 52.376 Control strategy: Carbon... submitted a revision to the carbon monoxide State Implementation Plan for the 1990 base year emission...

40 CFR 52.1373 - Control strategy: Carbon monoxide.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 4 2010-07-01 2010-07-01 false Control strategy: Carbon monoxide. 52...: Carbon monoxide. (a) On July 8, 1997, the Governor of Montana submitted revisions to the SIP narrative for the Missoula carbon monoxide control plan. (b) Revisions to the Montana State Implementation Plan...

Factors affecting the behavior of unburned carbon upon steam activation

NASA Astrophysics Data System (ADS)

Lu, Zhe

The main objective of this study is to investigate the factors that could affect the behavior of unburned carbon samples upon steam activation. Through this work, the relationships among the factors that could influence the carbon-steam reaction with the surface area of the produced activated carbon were explored. Statistical analysis was used to relate the chemical and physical properties of the unburned carbon to the surface area of the activated carbon. Six unburned carbons were selected as feedstocks for activated carbon, and marked as UCA through UCF. The unburned carbons were activated using steam at 850°C for 90 minutes, and the surface areas of their activated counterparts were measured using N2 adsorption isotherms at 77K. The activated carbons produced from different unburned carbon precursors presented different surface areas at similar carbon burn-off levels. Moreover, in different carbon burn-off regions, the sequences for surface area of activated carbons from different unburned carbon samples were different. The factors that may affect the carbon-steam gasification reactions, including the concentration of carbon active sites, the crystallite size of the carbon, the intrinsic porous structure of carbon, and the inorganic impurities, were investigated. All unburned carbons investigated in this study were similar in that they showed the very broad (002) and (10 ) carbon peaks, which are characteristic of highly disordered carbonaceous materials. In this study, the unburned carbon samples contained about 17--48% of inorganic impurities. Compared to coals, the unburned carbon samples contain a larger amount of inorganic impurities as a result of the burn-off, or at lease part, of the carbon during the combustion process. These inorganic particles were divided into two groups in terms of the way they are associated with carbon particles: free single particles, and particles combined with carbon particles. As indicated from the present work, unburned

Carbon Dioxide Emission Factors for Coal

EIA Publications

1994-01-01

The Energy Information Administration (EIA) has developed factors for estimating the amount of carbon dioxide emitted, accounting for differences among coals, to reflect the changing "mix" of coal in U.S. coal consumption.

Factors Affecting Regional Per-Capita Carbon Emissions in China Based on an LMDI Factor Decomposition Model

PubMed Central

Dong, Feng; Long, Ruyin; Chen, Hong; Li, Xiaohui; Yang, Qingliang

2013-01-01

China is considered to be the main carbon producer in the world. The per-capita carbon emissions indicator is an important measure of the regional carbon emissions situation. This study used the LMDI factor decomposition model–panel co-integration test two-step method to analyze the factors that affect per-capita carbon emissions. The main results are as follows. (1) During 1997, Eastern China, Central China, and Western China ranked first, second, and third in the per-capita carbon emissions, while in 2009 the pecking order changed to Eastern China, Western China, and Central China. (2) According to the LMDI decomposition results, the key driver boosting the per-capita carbon emissions in the three economic regions of China between 1997 and 2009 was economic development, and the energy efficiency was much greater than the energy structure after considering their effect on restraining increased per-capita carbon emissions. (3) Based on the decomposition, the factors that affected per-capita carbon emissions in the panel co-integration test showed that Central China had the best energy structure elasticity in its regional per-capita carbon emissions. Thus, Central China was ranked first for energy efficiency elasticity, while Western China was ranked first for economic development elasticity. PMID:24353753

Factors affecting regional per-capita carbon emissions in China based on an LMDI factor decomposition model.

PubMed

Dong, Feng; Long, Ruyin; Chen, Hong; Li, Xiaohui; Yang, Qingliang

2013-01-01

China is considered to be the main carbon producer in the world. The per-capita carbon emissions indicator is an important measure of the regional carbon emissions situation. This study used the LMDI factor decomposition model-panel co-integration test two-step method to analyze the factors that affect per-capita carbon emissions. The main results are as follows. (1) During 1997, Eastern China, Central China, and Western China ranked first, second, and third in the per-capita carbon emissions, while in 2009 the pecking order changed to Eastern China, Western China, and Central China. (2) According to the LMDI decomposition results, the key driver boosting the per-capita carbon emissions in the three economic regions of China between 1997 and 2009 was economic development, and the energy efficiency was much greater than the energy structure after considering their effect on restraining increased per-capita carbon emissions. (3) Based on the decomposition, the factors that affected per-capita carbon emissions in the panel co-integration test showed that Central China had the best energy structure elasticity in its regional per-capita carbon emissions. Thus, Central China was ranked first for energy efficiency elasticity, while Western China was ranked first for economic development elasticity.

Biophysical Controls on Carbon Cycling in Restored and Unrestored Urban Streams

NASA Astrophysics Data System (ADS)

Larsen, L. G.; Harvey, J. W.; Singh, J. D.; Sinclair, G. A.; Langston, T.; Maglio, M. M.

2012-12-01

Stream restoration is a multibillion dollar industry, yet how restoration impacts the ecological functioning of streams remains poorly understood. Because stream restoration may alter numerous biophysical controls, including light availability (through tree removal during bank regrading), hydraulics, sediment characteristics, and/or nutrient concentrations, it can be challenging to achieve a general understanding of how different aspects of stream restoration design influence ecosystem function (e.g., carbon cycling). In this study we combined strategies of continuously monitoring hydrology, turbidity, and dissolved oxygen at a station with spatially distributed but temporally sparse synoptic sampling to understand how restoration and land-use impact carbon fixation and respiration in urban streams. The study was performed over three years in three adjacent 3rd-4th order stream reaches in the urban Chesapeake Bay watershed, one of which was restored in 2002 using the ubiquitous Natural Channel Design method. By parsing the dissolved oxygen time series into contributions from respiration and gross primary production, we found the unrestored urban reach to be the most heterotrophic. It removed two times more carbon from the stream to the atmosphere than an unrestored suburban stream that was nutrient impacted and five times more carbon than the restored urban stream. The synoptic sampling revealed that nutrients, light, and hydrodynamic disturbance were the primary controls on carbon fixation and respiration, with fine sediment also exhibiting importance, likely as a vehicle for nutrient transport. Low rates of net carbon removal in the restored stream arose from high light availability resulting in high primary production, combined with low fine sediment availability restricting respiration. Thus, while restoration may have been effective for stream stabilization, it has decreased the functionality of the stream for net carbon removal to the atmosphere. Surprisingly

Sequestration of flue gas CO₂ by direct gas-solid carbonation of air pollution control system residues.

PubMed

Tian, Sicong; Jiang, Jianguo

2012-12-18

Direct gas-solid carbonation reactions of residues from an air pollution control system (APCr) were conducted using different combinations of simulated flue gas to study the impact on CO₂ sequestration. X-ray diffraction analysis of APCr determined the existence of CaClOH, whose maximum theoretical CO₂ sequestration potential of 58.13 g CO₂/kg APCr was calculated by the reference intensity ratio method. The reaction mechanism obeyed a model of a fast kinetics-controlled process followed by a slow product layer diffusion-controlled process. Temperature is the key factor in direct gas-solid carbonation and had a notable influence on both the carbonation conversion and the CO₂ sequestration rate. The optimal CO₂ sequestrating temperature of 395 °C was easily obtained for APCr using a continuous heating experiment. CO₂ content in the flue gas had a definite influence on the CO₂ sequestration rate of the kinetics-controlled process, but almost no influence on the final carbonation conversion. Typical concentrations of SO₂ in the flue gas could not only accelerate the carbonation reaction rate of the product layer diffusion-controlled process, but also could improve the final carbonation conversion. Maximum carbonation conversions of between 68.6% and 77.1% were achieved in a typical flue gas. Features of rapid CO₂ sequestration rate, strong impurities resistance, and high capture conversion for direct gas-solid carbonation were proved in this study, which presents a theoretical foundation for the applied use of this encouraging technology on carbon capture and storage.

[Research on carbon reduction potential of electric vehicles for low-carbon transportation and its influencing factors].

PubMed

Shi, Xiao-Qing; Li, Xiao-Nuo; Yang, Jian-Xin

2013-01-01

Transportation is the key industry of urban energy consumption and carbon emissions. The transformation of conventional gasoline vehicles to new energy vehicles is an important initiative to realize the goal of developing low-carbon city through energy saving and emissions reduction, while electric vehicles (EV) will play an important role in this transition due to their advantage in energy saving and lower carbon emissions. After reviewing the existing researches on energy saving and emissions reduction of electric vehicles, this paper analyzed the factors affecting carbon emissions reduction. Combining with electric vehicles promotion program in Beijing, the paper analyzed carbon emissions and reduction potential of electric vehicles in six scenarios using the optimized energy consumption related carbon emissions model from the perspective of fuel life cycle. The scenarios included power energy structure, fuel type (energy consumption per 100 km), car type (CO2 emission factor of fuel), urban traffic conditions (speed), coal-power technologies and battery type (weight, energy efficiency). The results showed that the optimized model was able to estimate carbon emissions caused by fuel consumption more reasonably; electric vehicles had an obvious restrictive carbon reduction potential with the fluctuation of 57%-81.2% in the analysis of six influencing factors, while power energy structure and coal-power technologies play decisive roles in life-cycle carbon emissions of electric vehicles with the reduction potential of 78.1% and 81.2%, respectively. Finally, some optimized measures were proposed to reduce transport energy consumption and carbon emissions during electric vehicles promotion including improving energy structure and coal technology, popularizing energy saving technologies and electric vehicles, accelerating the battery R&D and so on. The research provides scientific basis and methods for the policy development for the transition of new energy vehicles

Transcription Factor Arabidopsis Activating Factor1 Integrates Carbon Starvation Responses with Trehalose Metabolism1[OPEN

PubMed Central

Garapati, Prashanth; Feil, Regina; Lunn, John Edward; Van Dijck, Patrick; Balazadeh, Salma; Mueller-Roeber, Bernd

2015-01-01

Plants respond to low carbon supply by massive reprogramming of the transcriptome and metabolome. We show here that the carbon starvation-induced NAC (for NO APICAL MERISTEM/ARABIDOPSIS TRANSCRIPTION ACTIVATION FACTOR/CUP-SHAPED COTYLEDON) transcription factor Arabidopsis (Arabidopsis thaliana) Transcription Activation Factor1 (ATAF1) plays an important role in this physiological process. We identified TREHALASE1, the only trehalase-encoding gene in Arabidopsis, as a direct downstream target of ATAF1. Overexpression of ATAF1 activates TREHALASE1 expression and leads to reduced trehalose-6-phosphate levels and a sugar starvation metabolome. In accordance with changes in expression of starch biosynthesis- and breakdown-related genes, starch levels are generally reduced in ATAF1 overexpressors but elevated in ataf1 knockout plants. At the global transcriptome level, genes affected by ATAF1 are broadly associated with energy and carbon starvation responses. Furthermore, transcriptional responses triggered by ATAF1 largely overlap with expression patterns observed in plants starved for carbon or energy supply. Collectively, our data highlight the existence of a positively acting feedforward loop between ATAF1 expression, which is induced by carbon starvation, and the depletion of cellular carbon/energy pools that is triggered by the transcriptional regulation of downstream gene regulatory networks by ATAF1. PMID:26149570

Controls of Parent Material and Topography on Soil Carbon Storage in the Critical Zone

NASA Astrophysics Data System (ADS)

Patton, N. R.; Seyfried, M. S.; Lohse, K. A.; Link, T. E.

2014-12-01

Semi-arid environments make up a large percentage of the world's terrestrial ecosystems, and climate is a major factor influencing soil carbon storage and release. However, the roles of local controls such as parent material, aspect and microtopography have received less attention and are important for consideration in soil carbon modeling. The purpose of this study is to understand the role that parent material, aspect and micro-topography play in storage and release of soil carbon along an elevation gradient in a semi-arid climate. Johnston Draw (JD) is a first order watershed within the Reynolds Creek Critical Zone Observatory in southwestern Idaho with underlining late cretaceous, granitic Idaho batholith bedrock. Upper Sheep Creek (USC) is a first order watershed consisting of basalt. Both watersheds were chosen for this project due to similar size, aspect, elevation, vegetation and for the contrast in parent material. Two transects, totaling approximately nine soil pits, were excavated on both the north and south facing slopes of each watershed running parallel to the water channel. Soil carbon was generally higher in basalt compared to the granite parent material in pits with similar aspect, elevation and vegetation. Preliminary data using soil organic matter (SOM) as a proxy for organic carbon (OC) and soil water dynamics showed that percent OC declines markedly with elevation in JD and soil depth at lower elevations and is more homogenous throughout the profile moving up elevation (1646 meters 4.3-9.7%; 1707 meters 6.87-3.83%). Similarly, aspect controls patterns of SOM at depth more strongly at lower elevations. Findings from our study suggest that parent material and topography may play as important roles in semi-arid ecosystems as climate factors in controlling soil carbon storage.

40 CFR 52.2353 - Control strategy: Carbon monoxide.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 4 2010-07-01 2010-07-01 false Control strategy: Carbon monoxide. 52...: Carbon monoxide. Determination. EPA has determined that the Provo carbon monoxide “moderate” nonattainment area attained the carbon monoxide national ambient air quality standard by December 31, 1995. This...

40 CFR 52.1237 - Control strategy: Carbon monoxide.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 4 2010-07-01 2010-07-01 false Control strategy: Carbon monoxide. 52... strategy: Carbon monoxide. (a) The base year carbon monoxide emission inventory requirement of section 187... Metropolitan Area and Minneapolis-St. Paul Metropolitan Area. (b) Approval—The 1993 carbon monoxide periodic...

Precise carbon control of fabricated stainless steel

DOEpatents

Nilsen, R.J.

1975-12-01

A process is described for controlling the carbon content of fabricated stainless steel components including the steps of heat treating the component in hydrogen atmospheres of varying dewpoints and carbon potentials.

40 CFR 52.1887 - Control strategy: Carbon monoxide.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 4 2010-07-01 2010-07-01 false Control strategy: Carbon monoxide. 52...: Carbon monoxide. (a) Part D—Approval—The following portions of the Ohio plan are approved: (1) The carbon...) The carbon monoxide attainment and reasonable further progress demonstrations for the following urban...

Transforming growth factor-beta1 accelerates resorption of a calcium carbonate biomaterial in periodontal defects.

PubMed

Koo, Ki-Tae; Susin, Cristiano; Wikesjö, Ulf M E; Choi, Seong-Ho; Kim, Chong-Kwan

2007-04-01

In a previous study, recombinant human transforming growth factor-beta1 (rhTGF-beta(1)) in a calcium carbonate carrier was implanted into critical-size, supraalveolar periodontal defects under conditions for guided tissue regeneration (GTR) to study whether rhTGF-beta(1) would enhance or accelerate periodontal regeneration. The results showed minimal benefits of rhTGF-beta(1), and a clear account for this could not be offered. One potential cause may be that the rhTGF-beta(1) formulation was biologically inactive. Several growth or differentiation factors have been suggested to accelerate degradation of biomaterials used as carriers. The objective of this study was to evaluate possible activity of rhTGF-beta(1) on biodegradation of the calcium carbonate carrier. rhTGF-beta(1) in a putty-formulated particulate calcium carbonate carrier was implanted into critical-size, supraalveolar periodontal defects under conditions for GTR in five beagle dogs. Contralateral defects received the calcium carbonate carrier combined with GTR without rhTGF-beta(1) (control). The animals were euthanized at week 4 post-surgery and block biopsies of the defect sites were collected for histologic and histometric analysis. Radiographs were obtained at defect creation and weeks 2 and 4 after defect creation. No statistically significant differences were observed in new bone formation (bone height and area) among the treatments. However, total residual carrier was significantly reduced in sites receiving rhTGF-beta(1) compared to control (P = 0.04). Similarly, carrier density was considerably reduced in sites receiving rhTGF-beta(1) compared to control; the difference was borderline statistically significant (P = 0.06). Within the limitations of the study, it may be concluded that rhTGF-beta(1) accelerates biodegradation of a particulate calcium carbonate biomaterial, indicating a biologic activity of the rhTGF-beta(1) formulation apparently not encompassing enhanced or accelerated

An Analysis of Terrestrial and Aquatic Environmental Controls of Riverine Dissolved Organic Carbon in the Conterminous United States

DOE PAGES

Yang, Qichun; Zhang, Xuesong; Xu, Xingya; ...

2017-05-29

Riverine carbon cycling is an important, but insufficiently investigated component of the global carbon cycle. Analyses of environmental controls on riverine carbon cycling are critical for improved understanding of mechanisms regulating carbon processing and storage along the terrestrial-aquatic continuum. Here, we compile and analyze riverine dissolved organic carbon (DOC) concentration data from 1402 United States Geological Survey (USGS) gauge stations to examine the spatial variability and environmental controls of DOC concentrations in the United States (U.S.) surface waters. DOC concentrations exhibit high spatial variability, with an average of 6.42 ± 6.47 mg C/ L (Mean ± Standard Deviation). In general,more » high DOC concentrations occur in the Upper Mississippi River basin and the Southeastern U.S., while low concentrations are mainly distributed in the Western U.S. Single-factor analysis indicates that slope of drainage areas, wetlands, forests, percentage of first-order streams, and instream nutrients (such as nitrogen and phosphorus) pronouncedly influence DOC concentrations, but the explanatory power of each bivariate model is lower than 35%. Analyses based on the general multi-linear regression models suggest DOC concentrations are jointly impacted by multiple factors. Soil properties mainly show positive correlations with DOC concentrations; forest and shrub lands have positive correlations with DOC concentrations, but urban area and croplands demonstrate negative impacts; total instream phosphorus and dam density correlate positively with DOC concentrations. Notably, the relative importance of these environmental controls varies substantially across major U.S. water resource regions. In addition, DOC concentrations and environmental controls also show significant variability from small streams to large rivers, which may be caused by changing carbon sources and removal rates by river orders. In sum, our results reveal that general multi

Factors controlling shell carbon isotopic composition of land snail Acusta despecta sieboldiana estimated from laboratory culturing experiment

NASA Astrophysics Data System (ADS)

Zhang, N.; Yamada, K.; Suzuki, N.; Yoshida, N.

2014-10-01

The carbon isotopic composition (δ13C) of land snail shell carbonate derives from three potential sources: diet, atmospheric CO2, and ingested carbonate (limestone). However, their relative contributions remain unclear. Under various environmental conditions, we cultured one land snail subspecies, Acusta despecta sieboldiana, collected from Yokohama, Japan, and confirmed that all of these sources affect shell carbonate δ13C values. Herein, we consider the influences of metabolic rates and temperature on the carbon isotopic composition of the shell carbonate. Based on results obtained from previous works and this study, a simple but credible framework is presented to illustrate how each source and environmental parameter affects shell carbonate δ13C values. According to this framework and some reasonable assumptions, we estimated the contributions of different carbon sources for each snail individual: for cabbage-fed (C3 plant) groups, the contributions of diet, atmospheric CO2, and ingested limestone vary in the ranges of 66-80, 16-24, and 0-13%, respectively. For corn-fed (C4 plant) groups, because of the possible food stress (less ability to consume C4 plants), the values vary in the ranges of 56-64, 18-20, and 16-26%, respectively. Moreover, according to the literature and our observations, the subspecies we cultured in this study show preferences towards different plant species for food. Therefore, we suggest that the potential food preference should be considered adequately for some species in paleoenvironment studies. Finally, we inferred that only the isotopic exchange of the calcite-HCO3--aragonite equilibrium during egg laying and hatching of our cultured snails controls carbon isotope fractionation.

Factors controlling shell carbon isotopic composition of land snail Acusta despecta sieboldiana estimated from lab culturing experiment

NASA Astrophysics Data System (ADS)

Zhang, N.; Yamada, K.; Suzuki, N.; Yoshida, N.

2014-05-01

The carbon isotopic composition (δ13C) of land snail shell carbonate derives from three potential sources: diet, atmospheric CO2, and ingested carbonate (limestone). However, their relative contributions remain unclear. Under various environmental conditions, we cultured one land snail species, Acusta despecta sieboldiana collected from Yokohama, Japan, and confirmed that all of these sources affect shell carbonate δ13C values. Herein, we consider the influences of metabolic rates and temperature on the carbon isotopic composition of the shell carbonate. Based on previous works and on results obtained in this study, a simple but credible framework is presented for discussion of how each source and environmental parameter can affect shell carbonate δ13C values. According to this framework and some reasonable assumptions, we have estimated the contributions of different carbon sources for each snail individual: for cabbage (C3 plant) fed groups, the contributions of diet, atmospheric CO2 and ingested limestone respectively vary as 66-80%, 16-24%, and 0-13%. For corn (C4 plant) fed groups, because of the possible food stress (lower consumption ability of C4 plant), the values vary respectively as 56-64%, 18-20%, and 16-26%. Moreover, we present new evidence that snails have discrimination to choose C3 and C4 plants as food. Therefore, we suggest that food preferences must be considered adequately when applying δ13C in paleo-environment studies. Finally, we inferred that, during egg laying and hatching of our cultured snails, carbon isotope fractionation is controlled only by the isotopic exchange of the calcite-HCO3--aragonite equilibrium.

40 CFR 52.1132 - Control strategy: Carbon Monoxide.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 4 2013-07-01 2013-07-01 false Control strategy: Carbon Monoxide. 52.1132 Section 52.1132 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) Massachusetts § 52.1132 Control strategy: Carbon Monoxide. (a)...

40 CFR 52.1132 - Control strategy: Carbon Monoxide.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 4 2011-07-01 2011-07-01 false Control strategy: Carbon Monoxide. 52.1132 Section 52.1132 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) Massachusetts § 52.1132 Control strategy: Carbon Monoxide. (a)...

40 CFR 52.1132 - Control strategy: Carbon Monoxide.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 4 2014-07-01 2014-07-01 false Control strategy: Carbon Monoxide. 52.1132 Section 52.1132 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) Massachusetts § 52.1132 Control strategy: Carbon Monoxide. (a)...

Density controlled carbon nanotube array electrodes

DOEpatents

Ren, Zhifeng F [Newton, MA; Tu, Yi [Belmont, MA

2008-12-16

CNT materials comprising aligned carbon nanotubes (CNTs) with pre-determined site densities, catalyst substrate materials for obtaining them and methods for forming aligned CNTs with controllable densities on such catalyst substrate materials are described. The fabrication of films comprising site-density controlled vertically aligned CNT arrays of the invention with variable field emission characteristics, whereby the field emission properties of the films are controlled by independently varying the length of CNTs in the aligned array within the film or by independently varying inter-tubule spacing of the CNTs within the array (site density) are disclosed. The fabrication of microelectrode arrays (MEAs) formed utilizing the carbon nanotube material of the invention is also described.

Landscape-Scale Controls on Aboveground Forest Carbon Stocks on the Osa Peninsula, Costa Rica

PubMed Central

Taylor, Philip; Asner, Gregory; Dahlin, Kyla; Anderson, Christopher; Knapp, David; Martin, Roberta; Mascaro, Joseph; Chazdon, Robin; Cole, Rebecca; Wanek, Wolfgang; Hofhansl, Florian; Malavassi, Edgar; Vilchez-Alvarado, Braulio; Townsend, Alan

2015-01-01

Tropical forests store large amounts of carbon in tree biomass, although the environmental controls on forest carbon stocks remain poorly resolved. Emerging airborne remote sensing techniques offer a powerful approach to understand how aboveground carbon density (ACD) varies across tropical landscapes. In this study, we evaluate the accuracy of the Carnegie Airborne Observatory (CAO) Light Detection and Ranging (LiDAR) system to detect top-of-canopy tree height (TCH) and ACD across the Osa Peninsula, Costa Rica. LiDAR and field-estimated TCH and ACD were highly correlated across a wide range of forest ages and types. Top-of-canopy height (TCH) reached 67 m, and ACD surpassed 225 Mg C ha-1, indicating both that airborne CAO LiDAR-based estimates of ACD are accurate in tall, high-biomass forests and that the Osa Peninsula harbors some of the most carbon-rich forests in the Neotropics. We also examined the relative influence of lithologic, topoedaphic and climatic factors on regional patterns in ACD, which are known to influence ACD by regulating forest productivity and turnover. Analyses revealed a spatially nested set of factors controlling ACD patterns, with geologic variation explaining up to 16% of the mapped ACD variation at the regional scale, while local variation in topographic slope explained an additional 18%. Lithologic and topoedaphic factors also explained more ACD variation at 30-m than at 100-m spatial resolution, suggesting that environmental filtering depends on the spatial scale of terrain variation. Our result indicate that patterns in ACD are partially controlled by spatial variation in geologic history and geomorphic processes underpinning topographic diversity across landscapes. ACD also exhibited spatial autocorrelation, which may reflect biological processes that influence ACD, such as the assembly of species or phenotypes across the landscape, but additional research is needed to resolve how abiotic and biotic factors contribute to ACD

40 CFR 52.1340 - Control strategy: Carbon monoxide.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 4 2013-07-01 2013-07-01 false Control strategy: Carbon monoxide. 52.1340 Section 52.1340 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) Missouri § 52.1340 Control strategy: Carbon monoxide. Approval—A...

40 CFR 52.1179 - Control strategy: Carbon monoxide.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 4 2014-07-01 2014-07-01 false Control strategy: Carbon monoxide. 52.1179 Section 52.1179 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) Michigan § 52.1179 Control strategy: Carbon monoxide. (a) Approval—On...

40 CFR 52.2353 - Control strategy: Carbon monoxide.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 5 2014-07-01 2014-07-01 false Control strategy: Carbon monoxide. 52.2353 Section 52.2353 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) Utah § 52.2353 Control strategy: Carbon monoxide. Determination. EPA has...

40 CFR 52.729 - Control strategy: Carbon monoxide.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 3 2013-07-01 2013-07-01 false Control strategy: Carbon monoxide. 52.729 Section 52.729 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS Illinois> § 52.729 Control strategy: Carbon monoxide. The following source specific...

40 CFR 52.1528 - Control strategy: Carbon monoxide.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 4 2014-07-01 2014-07-01 false Control strategy: Carbon monoxide. 52.1528 Section 52.1528 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) New Hampshire § 52.1528 Control strategy: Carbon monoxide. (a)...

40 CFR 52.2353 - Control strategy: Carbon monoxide.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 5 2013-07-01 2013-07-01 false Control strategy: Carbon monoxide. 52.2353 Section 52.2353 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) Utah § 52.2353 Control strategy: Carbon monoxide. Determination. EPA has...

40 CFR 52.729 - Control strategy: Carbon monoxide.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 3 2014-07-01 2014-07-01 false Control strategy: Carbon monoxide. 52.729 Section 52.729 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS Illinois> § 52.729 Control strategy: Carbon monoxide. The following source specific...

40 CFR 52.1179 - Control strategy: Carbon monoxide.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 4 2013-07-01 2013-07-01 false Control strategy: Carbon monoxide. 52.1179 Section 52.1179 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) Michigan § 52.1179 Control strategy: Carbon monoxide. (a) Approval—On...

40 CFR 52.1528 - Control strategy: Carbon monoxide.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 4 2013-07-01 2013-07-01 false Control strategy: Carbon monoxide. 52.1528 Section 52.1528 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) New Hampshire § 52.1528 Control strategy: Carbon monoxide. (a)...

40 CFR 52.729 - Control strategy: Carbon monoxide.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 3 2012-07-01 2012-07-01 false Control strategy: Carbon monoxide. 52.729 Section 52.729 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS Illinois> § 52.729 Control strategy: Carbon monoxide. The following source specific...

40 CFR 52.1185 - Control strategy: Carbon monoxide.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 4 2013-07-01 2013-07-01 false Control strategy: Carbon monoxide. 52.1185 Section 52.1185 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) Michigan § 52.1185 Control strategy: Carbon monoxide. (a) Approval—On...

40 CFR 52.1340 - Control strategy: Carbon monoxide.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 4 2014-07-01 2014-07-01 false Control strategy: Carbon monoxide. 52.1340 Section 52.1340 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) Missouri § 52.1340 Control strategy: Carbon monoxide. Approval—A...

40 CFR 52.1185 - Control strategy: Carbon monoxide.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 4 2014-07-01 2014-07-01 false Control strategy: Carbon monoxide. 52.1185 Section 52.1185 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) Michigan § 52.1185 Control strategy: Carbon monoxide. (a) Approval—On...

Carbon Structure Hazard Control

NASA Technical Reports Server (NTRS)

Yoder, Tommy; Greene, Ben; Porter, Alan

2015-01-01

Carbon composite structures are widely used in virtually all advanced technology industries for a multitude of applications. The high strength-to-weight ratio and resistance to aggressive service environments make them highly desirable. Automotive, aerospace, and petroleum industries extensively use, and will continue to use, this enabling technology. As a result of this broad range of use, field and test personnel are increasingly exposed to hazards associated with these structures. No single published document exists to address the hazards and make recommendations for the hazard controls required for the different exposure possibilities from damaged structures including airborne fibers, fly, and dust. The potential for personnel exposure varies depending on the application or manipulation of the structure. The effect of exposure to carbon hazards is not limited to personnel, protection of electronics and mechanical equipment must be considered as well. The various exposure opportunities defined in this document include pre-manufacturing fly and dust, the cured structure, manufacturing/machining, post-event cleanup, and post-event test and/or evaluation. Hazard control is defined as it is applicable or applied for the specific exposure opportunity. The carbon exposure hazard includes fly, dust, fiber (cured/uncured), and matrix vapor/thermal decomposition products. By using the recommendations in this document, a high level of confidence can be assured for the protection of personnel and equipment.

40 CFR 52.1682 - Control strategy: Carbon monoxide.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 4 2014-07-01 2014-07-01 false Control strategy: Carbon monoxide. 52.1682 Section 52.1682 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) New York § 52.1682 Control strategy: Carbon monoxide. (a) Approval—The...

40 CFR 52.1373 - Control strategy: Carbon monoxide.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 4 2014-07-01 2014-07-01 false Control strategy: Carbon monoxide. 52.1373 Section 52.1373 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) Montana § 52.1373 Control strategy: Carbon monoxide. (a) On July 8, 1997...

40 CFR 52.1682 - Control strategy: Carbon monoxide.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 4 2013-07-01 2013-07-01 false Control strategy: Carbon monoxide. 52.1682 Section 52.1682 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) New York § 52.1682 Control strategy: Carbon monoxide. (a) Approval—The...

40 CFR 52.1581 - Control strategy: Carbon monoxide.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 4 2014-07-01 2014-07-01 false Control strategy: Carbon monoxide. 52.1581 Section 52.1581 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) New Jersey § 52.1581 Control strategy: Carbon monoxide. (a) Approval—The...

40 CFR 52.1581 - Control strategy: Carbon monoxide.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 4 2013-07-01 2013-07-01 false Control strategy: Carbon monoxide. 52.1581 Section 52.1581 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) New Jersey § 52.1581 Control strategy: Carbon monoxide. (a) Approval—The...

40 CFR 52.785 - Control strategy: Carbon monoxide.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 3 2014-07-01 2014-07-01 false Control strategy: Carbon monoxide. 52.785 Section 52.785 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS Indiana § 52.785 Control strategy: Carbon monoxide. (a) The requirements of subpart G...

40 CFR 52.2089 - Control strategy: carbon monoxide.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 5 2013-07-01 2013-07-01 false Control strategy: carbon monoxide. 52.2089 Section 52.2089 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) Rhode Island § 52.2089 Control strategy: carbon monoxide. (a) Approval—O...

40 CFR 52.785 - Control strategy: Carbon monoxide.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 3 2013-07-01 2013-07-01 false Control strategy: Carbon monoxide. 52.785 Section 52.785 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS Indiana § 52.785 Control strategy: Carbon monoxide. (a) The requirements of subpart G...

40 CFR 52.2089 - Control strategy: carbon monoxide.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 5 2014-07-01 2014-07-01 false Control strategy: carbon monoxide. 52.2089 Section 52.2089 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) Rhode Island § 52.2089 Control strategy: carbon monoxide. (a) Approval—O...

40 CFR 52.1373 - Control strategy: Carbon monoxide.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 4 2013-07-01 2013-07-01 false Control strategy: Carbon monoxide. 52.1373 Section 52.1373 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) Montana § 52.1373 Control strategy: Carbon monoxide. (a) On July 8, 1997...

40 CFR 52.785 - Control strategy: Carbon monoxide.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 3 2012-07-01 2012-07-01 false Control strategy: Carbon monoxide. 52.785 Section 52.785 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS Indiana § 52.785 Control strategy: Carbon monoxide. (a) The requirements of subpart G...

40 CFR 52.1528 - Control strategy: Carbon monoxide.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 4 2010-07-01 2010-07-01 false Control strategy: Carbon monoxide. 52... strategy: Carbon monoxide. (a) Approval—On February 1, 1999, the New Hampshire Department of Environmental... program for carbon monoxide that ceased operating on January 1, 1995. The Nashua Inspection/Maintenance...

40 CFR 52.1132 - Control strategy: Carbon Monoxide.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 4 2010-07-01 2010-07-01 false Control strategy: Carbon Monoxide. 52... strategy: Carbon Monoxide. (a) Approval—On November 13, 1992, the Massachusetts Department of Environmental Protection submitted a revision to the carbon monoxide State Implementation Plan for the 1990 base year...

Factors controlling carbon isotopic composition of land snail shells estimated from lab culturing experiment

NASA Astrophysics Data System (ADS)

Zhang, Naizhong; Yamada, Keita; Yoshida, Naohiro

2014-05-01

Carbon isotopic composition (δ13C) of land snail shell carbonate is widely applied in reconstructing the C3/C4 vegetation distribution of paleo-environment, which is considered to reflect variations of some environmental parameters [1][2][3]. Land snail shell carbon has three potential sources: diet, atmospheric CO2 and ingested carbonate (limestone) [4]. However, their relative contributions to shell carbonate have not been understood well yet [4][5][6][7][8]. More researches are necessary before we could apply this tool in paleo-environment reconstruction, especially inter-lab culturing experiment. A kind of land snail species, Acusta despecta sieboldiana, was collected at Yokohama, Japan and cultured under suitable environment to lay eggs. The second generations were growing up from eggs to adults around 6-12 months at the temperature of 20°, 25° and 30°, respectively. All of the snails at 25° and 30° and most of those at 20° were fed by cabbage (C3 plant) during their life span while others were fed by corn (C4 plant). To investigate the effect of ingested carbonate, some of them were fed by Ca3(PO4)2 powder while others were fed by CaCO3 powder. δ13C of shells were analyzed by an Isotope Ratio Mass Spectrometry (Thermo Finnigan MAT 253); δ13C of food and snail tissue were measured by a Cavity Ring-Down Spectroscopy (Picarro G1121-i). At the same time, δ13C of eggshell and new born snails were analyzed by a Continuous Flow Isotope Ratio Mass Spectrometry (GasBench II). We confirmed that diet, atmospheric CO2 and ingested limestone could be important sources controlling shell δ13C values. And the temperature could affect shell carbonate δ13C values, too. A simple but credible frame was raised to discuss the mechanism of how each possible source and environmental parameter could affect shell carbonate δ13C values based on previous works [4][6][8] and this study. According to this frame and some reasonable assumptions, we have estimated the

40 CFR 52.2089 - Control strategy: carbon monoxide.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 4 2010-07-01 2010-07-01 false Control strategy: carbon monoxide. 52... strategy: carbon monoxide. (a) Approval—On September 22, 2008, the Rhode Island Department of Environmental Management submitted a request to establish a limited maintenance plan for the Providence Rhode Island carbon...

40 CFR 52.1185 - Control strategy: Carbon monoxide.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 4 2010-07-01 2010-07-01 false Control strategy: Carbon monoxide. 52...: Carbon monoxide. (a) Approval—On November 24, 1994, the Michigan Department of Natural Resources submitted a revision to the carbon monoxide State Implementation Plan. The submittal pertained to a plan for...

Factors controlling soil organic carbon stability along a temperate forest altitudinal gradient

PubMed Central

Tian, Qiuxiang; He, Hongbo; Cheng, Weixin; Bai, Zhen; Wang, Yang; Zhang, Xudong

2016-01-01

Changes in soil organic carbon (SOC) stability may alter carbon release from the soil and, consequently, atmospheric CO2 concentration. The mean annual temperature (MAT) can change the soil physico-chemical characteristics and alter the quality and quantity of litter input into the soil that regulate SOC stability. However, the relationship between climate and SOC stability remains unclear. A 500-day incubation experiment was carried out on soils from an 11 °C-gradient mountainous system on Changbai Mountain in northeast China. Soil respiration during the incubation fitted well to a three-pool (labile, intermediate and stable) SOC decomposition model. A correlation analysis revealed that the MAT only influenced the labile carbon pool size and not the SOC stability. The intermediate carbon pool contributed dominantly to cumulative carbon release. The size of the intermediate pool was strongly related to the percentage of sand particle. The decomposition rate of the intermediate pool was negatively related to soil nitrogen availability. Because both soil texture and nitrogen availability are temperature independent, the stability of SOC was not associated with the MAT, but was heavily influenced by the intrinsic processes of SOC formation and the nutrient status. PMID:26733344

Carbon bed mercury emissions control for mixed waste treatment.

PubMed

Soelberg, Nick; Enneking, Joe

2010-11-01

Mercury has various uses in nuclear fuel reprocessing and other nuclear processes, and so it is often present in radioactive and mixed (radioactive and hazardous) wastes. Compliance with air emission regulations such as the Hazardous Waste Combustor (HWC) Maximum Achievable Control Technology (MACT) standards can require off-gas mercury removal efficiencies up to 99.999% for thermally treating some mixed waste streams. Test programs have demonstrated this level of off-gas mercury control using fixed beds of granular sulfur-impregnated activated carbon. Other results of these tests include (1) the depth of the mercury control mass transfer zone was less than 15-30 cm for the operating conditions of these tests; (2) MERSORB carbon can sorb mercury up to 19 wt % of the carbon mass; and (3) the spent carbon retained almost all (98.3-99.99%) of the mercury during Toxicity Characteristic Leachability Procedure (TCLP) tests, but when even a small fraction of the total mercury dissolves, the spent carbon can fail the TCLP test when the spent carbon contains high mercury concentrations.

Research on carbon emission driving factors of China’s provincial construction industry

NASA Astrophysics Data System (ADS)

Shang, Mei; Dong, Rui; Fu, Yujie; Hao, Wentao

2018-03-01

As a pillar industry of the national economy, the damage to the environment by construction industry can not be ignored. In the context of low carbon development, identifying the main driving factors for the carbon emission of the provincial construction industry are the key for the local government to formulate the development strategy for construction. In the paper, based on the Kaya factor decomposition method, the carbon intensity of the energy structure, energy intensity and the impact of the construction output on the carbon emission of provincial construction industry are studied, and relevant suggestions for low carbon development of provincial construction industry are proposed. The conclusion of this paper provides a theoretical basis for the early realization of low-carbon development in China’s provincial construction industry.

Transforming Growth Factor-β1 Accelerates Resorption of a Calcium Carbonate Biomaterial in Periodontal Defects.

PubMed

Koo, Ki-Tae; Susin, Cristiano; Wikesjö, Ulf M E; Choi, Seong-Ho; Kim, Chong-Kwan

2007-04-01

In a previous study, recombinant human transforming growth factor-beta1 (rhTGF-β 1 ) in a calcium carbonate carrier was implanted into critical-size, supraalveolar periodontal defects under conditions for guided tissue regeneration (GTR) to study whether rhTGF-β 1 would enhance or accelerate periodontal regeneration. The results showed minimal benefits of rhTGF-β 1 , and a clear account for this could not be offered. One potential cause may be that the rhTGF-β 1 formulation was biologically inactive. Several growth or differentiation factors have been suggested to accelerate degradation of biomaterials used as carriers. The objective of this study was to evaluate possible activity of rhTGF-β 1 on biodegradation of the calcium carbonate carrier. rhTGF-β 1 in a putty-formulated particulate calcium carbonate carrier was implanted into critical-size, supraalveolar periodontal defects under conditions for GTR in five beagle dogs. Contralateral defects received the calcium carbonate carrier combined with GTR without rhTGF-β 1 (control). The animals were euthanized at week 4 post-surgery and block biopsies of the defect sites were collected for histologic and histometric analysis. Radiographs were obtained at defect creation and weeks 2 and 4 after defect creation. No statistically significant differences were observed in new bone formation (bone height and area) among the treatments. However, total residual carrier was significantly reduced in sites receiving rhTGF-β 1 compared to control (P = 0.04). Similarly, carrier density was considerably reduced in sites receiving rhTGF-β 1 compared to control; the difference was borderline statistically significant (P = 0.06). Within the limitations of the study, it may be concluded that rhTGF-β 1 accelerates biodegradation of a particulate calcium carbonate biomaterial, indicating a biologic activity of the rhTGF-β 1 formulation apparently not encompassing enhanced or accelerated periodontal regeneration. © 2007

Trends and Controls of inter-annual Variability in the Carbon Budget of Terrestrial Ecosystems

NASA Astrophysics Data System (ADS)

Cescatti, A.; Marcolla, B.

2014-12-01

The climate sensitivity of the terrestrial carbon budget will substantially affect the sign and strength of the land-climate feedbacks and the future climate trajectories. Current trends in the inter-annual variability of terrestrial carbon fluxes (IAV) may contribute to clarify the relative role of physical and biological controls of ecosystem responses to climate change. For this purpose we investigated how recent climate variability has impacted the carbon fluxes at long-term FLUXNET sites. Using a novel method, the IAV has been factored out in climate induced variability (physical control), variability due to changes in ecosystem functioning (biological control) and the interaction of the two terms. The relative control of the main climatic drivers (temperature, water availability) on the physical and biological sources of IAV has been investigated using both site level fluxes and global gridded products generated from the up-scaling of flux data. Results of this analysis highlight the fundamental role of precipitation trends on the pattern of IAV in the last 30 years. Our findings on the spatial/temporal trends of IAV have been finally confirmed using the signal derived from the global network of atmospheric CO2 concentrations measurements.

Controls on Variations of Surface Energy, Water, and Carbon Budgets within Large-Scale Amazon Basin

NASA Technical Reports Server (NTRS)

Smith, Eric A.; Cooper, Harry J.; Grose, Andrew; Gu, Jiu-Jing; Norman, John; daRocha, Humberto R.; Dias, Pedro Silva

2002-01-01

A key research focus of the LBA Research Program is understanding the space-time variations in interlinked surface energy, water, and carbon budgets, the controls on these variations, and the implications of these controls on the carbon sequestering capacity of the large scale forest-pasture system that dominates the Amaz6nia landscape. Quantification of these variations and controls are investigated by a combination of in situ measurements, remotely sensed measurements from space, and a realistically forced hydrometeorological model coupled to a carbon assimilation model, capable of simulating details within the surface energy and water budgets along with the principle processes of photosynthesis and respiration. Herein we describe the results of an investigation concerning the space-time controls of carbon sources and sinks distributed over the large scale Amazon basin. The results are derived from a carbon-water-energy budget retrieval system for the large scale Amazon basin, which uses a coupled carbon assimilation-hydrometeorological model as an integrating system, forced by both in situ meteorological measurements and remotely sensed radiation and precipitation fluxes obtained from a combination of GOES, SSM/I, TOMS, and TRh4M satellite measurements. Results include validation of (a) retrieved surface radiation and precipitation fluxes based on 30-min averaged surface measurements taken at Ji-Parani in Rondania and Manaus in Amazonas, and (b) modeled sensible, latent, and C02 fluxes based on tower measurements taken at Reserva Jaru, Manaus and Fazenda Nossa Senhora. The space-time controls on carbon sequestration are partitioned into sets of factors classified by: (1) above canopy meteorology, (2) incoming surface radiation, (3) precipitation interception, and (4) indigenous stomatal processes varied over the different land covers of pristine rainforest, partially, and fully logged rainforests, and pasture lands. These are the principle meteorological

Spatial patterns and environmental controls of particulate organic carbon in surface waters in the conterminous United States

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Qichun; Zhang, Xuesong; Xu, Xingya

2016-06-01

Carbon stocks and fluxes in inland waters have been identified as important, but poorly constrained components of the global carbon cycle. In this study, we compile and analyze particulate organic carbon (POC) concentration data from 1145 U.S. Geological Survey (USGS) hydrologic stations to investigate the spatial variability and environmental controls of POC concentration. We observe substantial spatial variability in POC concentration (1.43 ± 2.56 mg C/ L, Mean ± Standard Deviation), with the Upper Mississippi River basin and the Piedmont region in the eastern U.S. having the highest POC concentration. Further, we employ generalized linear regression models to analyze themore » impacts of sediment transport and algae growth as well as twenty-one other environmental factors on the POC variability. Suspended sediment and chlorophyll-a explain 26% and 17% of the variability in POC concentration, respectively. At the national level, the twenty-one selected environmental factors combined can explain ca. 40% of the spatial variance in POC concentration. Overall, urban area and soil clay content show significant negative correlation with POC concentration, while soil water content and soil bulk density correlate positively with POC. In addition, total phosphorus concentration and dam density covariate positively with POC concentration. Furthermore, regional scale analyses reveal substantial variation in environmental controls determining POC concentration across the 18 major water resource regions in the U.S. The POC concentration and associated environmental controls also vary non-monotonically with river order. These findings indicate complex interactions among multiple factors in regulating POC production over different spatial scales and across various sections of the river networks. This complexity together with the large unexplained uncertainty highlight the need for consideration of non-linear processes that control them and developing appropriate

Hyperbaric Oxygen Therapy Alleviates Carbon Monoxide Poisoning-Induced Delayed Memory Impairment by Preserving Brain-Derived Neurotrophic Factor-Dependent Hippocampal Neurogenesis.

PubMed

Liu, Wen-Chung; Yang, San-Nan; Wu, Chih-Wei J; Chen, Lee-Wei; Chan, Julie Y H

2016-01-01

To test the hypothesis that hyperbaric oxygen therapy ameliorates delayed cognitive impairment after acute carbon monoxide poisoning by promoting neurogenesis through upregulating the brain-derived neurotrophic factor in the hippocampus. Laboratory animal experiments. University/Medical center research laboratory. Adult, male Sprague-Dawley rats. Rats were divided into five groups: (1) non-carbon monoxide-treated control, (2) acute carbon monoxide poisoning, (3) acute carbon monoxide poisoning followed by 7-day hyperbaric oxygen treatment, (4) carbon monoxide + hyperbaric oxygen with additional intracerebroventricular infusion of Fc fragment of tyrosine kinase receptor B protein (TrkB-Fc) chimera, and (5) acute carbon monoxide poisoning followed by intracerebroventricular infusion of brain-derived neurotrophic factor. Acute carbon monoxide poisoning was achieved by exposing the rats to carbon monoxide at 2,500 ppm for 40 minutes, followed by 3,000 ppm for 20 minutes. Hyperbaric oxygen therapy (at 2.5 atmospheres absolute with 100% oxygen for 60 min) was conducted during the first 7 days after carbon monoxide poisoning. Recombinant human TrkB-Fc chimera or brain-derived neurotrophic factor was infused into the lateral ventricle via the implanted osmotic minipump. For labeling of mitotic cells in the hippocampus, bromodeoxyuridine was injected into the peritoneal cavity. Distribution of bromodeoxyuridine and two additional adult neurogenesis markers, Ki-67 and doublecortin, in the hippocampus was evaluated by immunohistochemistry or immunofluorescence staining. Tissue level of brain-derived neurotrophic factor was assessed by enzyme-linked immunosorbent assay. Cognitive behavior was evaluated by the use of eight-arm radial maze. Acute carbon monoxide poisoning significantly suppressed adult hippocampal neurogenesis evident by the reduction in number of bromodeoxyuridine-positive, Ki-67⁺, and doublecortin⁺ cells in the subgranular zone of the dentate gyrus. This

Economic growth and carbon emission control

NASA Astrophysics Data System (ADS)

Zhang, Zhenyu

The question about whether environmental improvement is compatible with continued economic growth remains unclear and requires further study in a specific context. This study intends to provide insight on the potential for carbon emissions control in the absence of international agreement, and connect the empirical analysis with theoretical framework. The Chinese electricity generation sector is used as a case study to demonstrate the problem. Both social planner and private problems are examined to derive the conditions that define the optimal level of production and pollution. The private problem will be demonstrated under the emission regulation using an emission tax, an input tax and an abatement subsidy respectively. The social optimal emission flow is imposed into the private problem. To provide tractable analytical results, a Cobb-Douglas type production function is used to describe the joint production process of the desired output and undesired output (i.e., electricity and emissions). A modified Hamiltonian approach is employed to solve the system and the steady state solutions are examined for policy implications. The theoretical analysis suggests that the ratio of emissions to desired output (refer to 'emission factor'), is a function of productive capital and other parameters. The finding of non-constant emission factor shows that reducing emissions without further cutting back the production of desired outputs is feasible under some circumstances. Rather than an ad hoc specification, the optimal conditions derived from our theoretical framework are used to examine the relationship between desired output and emission level. Data comes from the China Statistical Yearbook and China Electric Power Yearbook and provincial information of electricity generation for the year of 1993-2003 are used to estimate the Cobb-Douglas type joint production by the full information maximum likelihood (FIML) method. The empirical analysis shed light on the optimal

Hydrology and landscape structure control subalpine catchment carbon export

Treesearch

Vincent Jerald Pacific

2009-01-01

Carbon export from high elevation ecosystems is a critical component of the global carbon cycle. Ecosystems in northern latitudes have become the focus of much research due to their potential as large sinks of carbon in the atmosphere. However, there exists limited understanding of the controls of carbon export from complex mountain catchments due to strong spatial and...

Factors controlling black carbon distribution in the Arctic

NASA Astrophysics Data System (ADS)

Qi, Ling; Li, Qinbin; Li, Yinrui; He, Cenlin

2017-01-01

We investigate the sensitivity of black carbon (BC) in the Arctic, including BC concentration in snow (BCsnow, ng g-1) and surface air (BCair, ng m-3), as well as emissions, dry deposition, and wet scavenging using the global three-dimensional (3-D) chemical transport model (CTM) GEOS-Chem. We find that the model underestimates BCsnow in the Arctic by 40 % on average (median = 11.8 ng g-1). Natural gas flaring substantially increases total BC emissions in the Arctic (by ˜ 70 %). The flaring emissions lead to up to 49 % increases (0.1-8.5 ng g-1) in Arctic BCsnow, dramatically improving model comparison with observations (50 % reduction in discrepancy) near flaring source regions (the western side of the extreme north of Russia). Ample observations suggest that BC dry deposition velocities over snow and ice in current CTMs (0.03 cm s-1 in the GEOS-Chem) are too small. We apply the resistance-in-series method to compute a dry deposition velocity (vd) that varies with local meteorological and surface conditions. The resulting velocity is significantly larger and varies by a factor of 8 in the Arctic (0.03-0.24 cm s-1), which increases the fraction of dry to total BC deposition (16 to 25 %) yet leaves the total BC deposition and BCsnow in the Arctic unchanged. This is largely explained by the offsetting higher dry and lower wet deposition fluxes. Additionally, we account for the effect of the Wegener-Bergeron-Findeisen (WBF) process in mixed-phase clouds, which releases BC particles from condensed phases (water drops and ice crystals) back to the interstitial air and thereby substantially reduces the scavenging efficiency of clouds for BC (by 43-76 % in the Arctic). The resulting BCsnow is up to 80 % higher, BC loading is considerably larger (from 0.25 to 0.43 mg m-2), and BC lifetime is markedly prolonged (from 9 to 16 days) in the Arctic. Overall, flaring emissions increase BCair in the Arctic (by ˜ 20 ng m-3), the updated vd more than halves BCair (by ˜ 20 ng m-3

Self-organized global control of carbon emissions

NASA Astrophysics Data System (ADS)

Zhao, Zhenyuan; Fenn, Daniel J.; Hui, Pak Ming; Johnson, Neil F.

2010-09-01

There is much disagreement concerning how best to control global carbon emissions. We explore quantitatively how different control schemes affect the collective emission dynamics of a population of emitting entities. We uncover a complex trade-off which arises between average emissions (affecting the global climate), peak pollution levels (affecting citizens’ everyday health), industrial efficiency (affecting the nation’s economy), frequency of institutional intervention (affecting governmental costs), common information (affecting trading behavior) and market volatility (affecting financial stability). Our findings predict that a self-organized free-market approach at the level of a sector, state, country or continent can provide better control than a top-down regulated scheme in terms of market volatility and monthly pollution peaks. The control of volatility also has important implications for any future derivative carbon emissions market.

Porosity control in nanoporous carbide-derived carbon by oxidation in air and carbon dioxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Osswald, S.; Portet, C.; Gogotsi, Y., E-mail: gogotsi@drexel.ed

2009-07-15

Carbide-derived carbons (CDC) allow a precise control over the pore size through the selection of the carbide precursor and varying of the synthesis conditions. However, their pore volume is limited by the carbide stoichiometry. While activation of carbons derived from various organic precursors has been widely studied, this process may similarly be able to increase the pore volume and specific surface area of CDC. Oxidation of carbide-derived carbon in air and CO{sub 2} at different temperatures and times allows for significant increase in pore volume and specific surface area as well as control over average pore size with subnanometer accuracy.more » The effect of activation and associated changes in the pore volume and surface area on the hydrogen uptake are also discussed. - Graphical abstract: Carbide-derived carbons (CDC) provide great potential for sorption of toxicants and gas storage applications. Activation of CDC in air and CO{sub 2} at different temperatures and times is applied in order to maximize pore volume and specific surface area, and control the average pore size with subnanometer accuracy.« less

Biophysical Controls over Carbon and Nitrogen Stocks in Desert Playa Wetlands

NASA Astrophysics Data System (ADS)

McKenna, O. P.; Sala, O. E.

2014-12-01

Playas are ephemeral desert wetlands situated at the bottom of closed catchments. Desert playas in the Southwestern US have not been intensively studied despite their potential importance for the functioning of desert ecosystems. We want to know which geomorphic and ecological variables control of the stock size of soil organic carbon, and soil total nitrogen in playas. We hypothesize that the magnitude of carbon and nitrogen stocks depends on: (a) catchment size, (b) catchment slope, (d) catchment vegetation cover, (e) bare-ground patch size, and (f) catchment soil texture. We chose thirty playas from across the Jornada Basin (Las Cruces, NM) ranging from 0.5-60ha in area and with varying catchment characteristics. We used the available 5m digital elevation map (DEM) to calculate the catchment size and catchment slope for these thirty playas. We measured percent cover, and patch size using the point-intercept method with three 10m transects in each catchment. We used the Bouyoucos-hydrometer soil particle analysis to determine catchment soil texture. Stocks of organic carbon and nitrogen were measured from soil samples at four depths (0-10 cm, 10-30 cm, 30-60 cm, 60-100 cm) using C/N combustion analysis. In terms of nitrogen and organic carbon storage, we found soil nitrogen values in the top 10cm ranging from 41.963-214.365 gN/m2, and soil organic carbon values in the top 10cm ranging from 594.339-2375.326 gC/m2. The results of a multiple regression analysis show a positive relationship between catchment slope and both organic carbon and nitrogen stock size (nitrogen: y= 56.801 +47.053, R2=0.621; organic carbon: y= 683.200 + 499.290x, R2= 0.536). These data support our hypothesis that catchment slope is one of factors controlling carbon and nitrogen stock in desert playas. We also applied our model to the 69 other playas of the Jornada Basin and estimated stock sizes (0-10cm) between 415.07-447.97 Mg for total soil nitrogen and 4627.99-5043.51 Mg for soil organic

Factors regulating carbon sinks in mangrove ecosystems.

PubMed

Li, Shi-Bo; Chen, Po-Hung; Huang, Jih-Sheng; Hsueh, Mei-Li; Hsieh, Li-Yung; Lee, Chen-Lu; Lin, Hsing-Juh

2018-05-23

Mangroves are recognized as one of the richest carbon storage systems. However, the factors regulating carbon sinks in mangrove ecosystems are still unclear, particularly in the subtropical mangroves. The biomass, production, litterfall, detrital export and decomposition of the dominant mangrove vegetation in subtropical (Kandelia obovata) and tropical (Avicennia marina) Taiwan were quantified from October 2011 to July 2014 to construct the carbon budgets. Despite the different tree species, a principal component analysis revealed the site or environmental conditions had a greater influence than the tree species on the carbon processes. For both species, the net production (NP) rates ranged from 10.86 to 27.64 Mg C ha -1  year -1 and were higher than the global average rate due to the high tree density. While most of the litterfall remained on the ground, a high percentage (72%-91%) of the ground litter decomposed within 1 year and fluxed out of the mangroves. However, human activities might cause a carbon flux into the mangroves and a lower NP rate. The rates of the organic carbon export and soil heterotrophic respiration were greater than the global mean values and those at other locations. Only a small percentage (3%-12%) of the NP was stored in the sediment. The carbon burial rates were much lower than the global average rate due to their faster decomposition, indicating that decomposition played a critical role in determining the burial rate in the sediment. The summation of the organic and inorganic carbon fluxes and soil heterotrophic respiration well exceeded the amount of litter decomposition, indicating an additional source of organic carbon that was unaccounted for by decomposition in the sediment. Sediment-stable isotope analyses further suggest that the trapping of organic matter from upstream rivers or adjacent waters contributed more to the mangrove carbon sinks than the actual production of the mangrove trees. © 2018 John Wiley & Sons Ltd.

The impact of environmental factors on carbon dioxide fixation by microalgae.

PubMed

Morales, Marcia; Sánchez, León; Revah, Sergio

2018-02-01

Microalgae are among the most productive biological systems for converting sunlight into chemical energy, which is used to capture and transform inorganic carbon into biomass. The efficiency of carbon dioxide capture depends on the cultivation system configuration (photobioreactors or open systems) and can vary according to the state of the algal physiology, the chemical composition of the nutrient medium, and environmental factors such as irradiance, temperature and pH. This mini-review is focused on some of the most important environmental factors determining photosynthetic activity, carbon dioxide biofixation, cell growth rate and biomass productivity by microalgae. These include carbon dioxide and O2 concentrations, light intensity, cultivation temperature and nutrients. Finally, a review of the operation of microalgal cultivation systems outdoors is presented as an example of the impact of environmental conditions on biomass productivity and carbon dioxide fixation. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

40 CFR 52.1179 - Control strategy: Carbon monoxide.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 4 2010-07-01 2010-07-01 false Control strategy: Carbon monoxide. 52.1179 Section 52.1179 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS...: Carbon monoxide. (a) Approval—On March 18, 1999, the Michigan Department of Environmental Quality...

40 CFR 52.1340 - Control strategy: Carbon monoxide.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 4 2010-07-01 2010-07-01 false Control strategy: Carbon monoxide. 52.1340 Section 52.1340 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS...: Carbon monoxide. Approval—A maintenance plan and redesignation request for the St. Louis, Missouri, area...

The influencing factors of China carbon price: a study based on carbon trading market in hubei province

NASA Astrophysics Data System (ADS)

Li, Hao; Lei, Ming

2018-02-01

For the carbon market, good trading mechanism is the basis for the healthy development of the carbon trading market. In order to explore the core problem of carbon price formation, our research explores the influencing factors of the price of carbon trading market. After the preliminary statistical analysis, our study found that Hubei Province is in the leading position among seven pilots in the carbon trading volume and the transaction, so our study of carbon price takes Hubei Province as sample of the empirical research. Multi-time series model and ARCH model analysis method are used in the research, we use the data of Hubei carbon trading pilot from June 2014 to December 2016 to carry out empirical research, the results found that industrial income, energy price, government intervention and the number of participating corporation have significant effect on the carbon price, which provides a meaningful reference for the other pilots in-depth study, as well as the construction of a national carbon trading market.

Provincial variation of carbon emissions from bituminous coal: Influence of inertinite and other factors

USGS Publications Warehouse

Quick, J.C.; Brill, T.

2002-01-01

We observe a 1.3 kg C/net GJ variation of carbon emissions due to inertinite abundance in some commercially available bituminous coal. An additional 0.9 kg C/net GJ variation of carbon emissions is expected due to the extent of coalification through the bituminous rank stages. Each percentage of sulfur in bituminous coal reduces carbon emissions by about 0.08 kg C/net GJ. Other factors, such as mineral content, liptinite abundance and individual macerals, also influence carbon emissions, but their quantitative effect is less certain. The large range of carbon emissions within the bituminous rank class suggests that rank- specific carbon emission factors are provincial rather than global. Although carbon emission factors that better account for this provincial variation might be calculated, we show that the data used for this calculation may vary according to the methods used to sample and analyze coal. Provincial variation of carbon emissions and the use of different coal sampling and analytical methods complicate the verification of national greenhouse gas inventories. Published by Elsevier Science B.V.

Disrupted carbon cycling in restored and unrestored urban streams: Critical timescales and controls

USGS Publications Warehouse

Larsen, L. G.; Harvey, Judson

2017-01-01

Carbon fixation and respiration in flowing waterways play significant roles in global and regional carbon budgets, yet how land use and watershed management interact with temporal disturbances (storms) to influence metabolism remains poorly understood. Here, we combine long-term with synoptic sampling of metabolism and its variable controls in neighboring watersheds of the Chesapeake Bay to resolve limiting factors and critical timescales associated with recovery from disturbance. We found that, relative to predictions of the river continuum concept, focal streams have “disrupted” carbon cycles, with carbon balances closer to zero, and, in some cases, tighter coupling between gross primary production (GPP) and ecosystem respiration (ER), attributable to carbon limitation. Carbon became limiting to ER where flashy storm hydrographs and simplified channel geomorphology inhibited accumulation of fine sediment. Shannon entropy analysis of timescales revealed that fine sediment served as a time-release capsule for nutrients and carbon over 4–6 months, fueling biogeochemical transformations. Loss of fines through hydraulic disturbance had up to 30-d impacts on GPP and 50-d impacts on ER in the stream with carbon limitation. In contrast, where GPP and ER were not tightly coupled, recovery occurred within 1 d. Results suggest that a complex interplay between nutrient and carbon limitation and mechanical and chemical disturbance governs patterns and consequences of disrupted carbon cycling in urban streams. Carbon limitation and tight GPP/ER coupling enhance the vulnerability of stream ecosystem functions, but best management practices that target stormflow reduction and channel geomorphic diversity can break that coupling and minimize carbon cycle disruptions.

Controlling signal transport in a carbon nanotube opto-transistor

NASA Astrophysics Data System (ADS)

Li, Jinjin; Chu, Yanhui; Zhu, Ka-Di

2016-11-01

With the highly competitive development of communication technologies, modern information manufactures place high importance on the ability to control the transmitted signal using easy miniaturization materials. A controlled and miniaturized optical information device is, therefore, vital for researchers in information and communication fields. Here we propose a controlled signal transport in a doubly clamped carbon nanotube system, where the transmitted signal can be controlled by another pump beam. Pump off results in the transmitted signal off, while pump on results in the transmitted signal on. The more pump, the more amplified output signal transmission. Analogous with traditional cavity optomechanical system, the role of optical cavity is played by a localized exciton in carbon nanotube while the role of the mechanical element is played by the nanotube vibrations, which enables the realization of an opto-transistor based on carbon nanotube. Since the signal amplification and attenuation have been observed in traditional optomechanical system, and the nanotube optomechanical system has been realized in laboratory, the proposed carbon nanotube opto-transistor could be implemented in current experiments and open the door to potential applications in modern optical networks and future quantum networks.

Controlling porosity in lignin-derived nanoporous carbon for supercapacitor applications

DOE PAGES

Jeon, Ju-Won; Zhang, Libing; Lutkenhaus, Jodie L.; ...

2015-02-01

Low-cost renewable lignin has been used as a precursor to produce porous carbons. However, to date, it has not been easy to obtain high surface area porous carbon without activation processes or templating agents. Here, we demonstrate that low molecular weight lignin yields highly porous carbon (1092 m² g⁻¹) with more graphitization through direct carbonization without additional activation processes or templating agents. We found that molecular weight and oxygen consumption during carbonization are critical factors to obtain high surface area, graphitized porous carbons. This highly porous carbon from low-cost renewable lignin sources is a good candidate for supercapacitor electrode materials.

Controlling porosity in lignin-derived nanoporous carbon for supercapacitor applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jeon, Ju-Won; Zhang, Libing; Lutkenhaus, Jodie L.

Low-cost renewable lignin has been used as a precursor to produce porous carbons. However, to date, it has not been easy to obtain high surface area porous carbon without activation processes or templating agents. Here, we demonstrate that low molecular weight lignin yields highly porous carbon (1092 m² g⁻¹) with more graphitization through direct carbonization without additional activation processes or templating agents. We found that molecular weight and oxygen consumption during carbonization are critical factors to obtain high surface area, graphitized porous carbons. This highly porous carbon from low-cost renewable lignin sources is a good candidate for supercapacitor electrode materials.

Global carbon export from the terrestrial biosphere controlled by erosion.

PubMed

Galy, Valier; Peucker-Ehrenbrink, Bernhard; Eglinton, Timothy

2015-05-14

Riverine export of particulate organic carbon (POC) to the ocean affects the atmospheric carbon inventory over a broad range of timescales. On geological timescales, the balance between sequestration of POC from the terrestrial biosphere and oxidation of rock-derived (petrogenic) organic carbon sets the magnitude of the atmospheric carbon and oxygen reservoirs. Over shorter timescales, variations in the rate of exchange between carbon reservoirs, such as soils and marine sediments, also modulate atmospheric carbon dioxide levels. The respective fluxes of biospheric and petrogenic organic carbon are poorly constrained, however, and mechanisms controlling POC export have remained elusive, limiting our ability to predict POC fluxes quantitatively as a result of climatic or tectonic changes. Here we estimate biospheric and petrogenic POC fluxes for a suite of river systems representative of the natural variability in catchment properties. We show that export yields of both biospheric and petrogenic POC are positively related to the yield of suspended sediment, revealing that POC export is mostly controlled by physical erosion. Using a global compilation of gauged suspended sediment flux, we derive separate estimates of global biospheric and petrogenic POC fluxes of 157(+74)(-50) and 43(+61)(-25) megatonnes of carbon per year, respectively. We find that biospheric POC export is primarily controlled by the capacity of rivers to mobilize and transport POC, and is largely insensitive to the magnitude of terrestrial primary production. Globally, physical erosion rates affect the rate of biospheric POC burial in marine sediments more strongly than carbon sequestration through silicate weathering. We conclude that burial of biospheric POC in marine sediments becomes the dominant long-term atmospheric carbon dioxide sink under enhanced physical erosion.

[Carbon density distribution characteristics and influencing factors in aerially seeded Pinus massoniana plantations].

PubMed

Pan, Ping; Han, Tian Yi; OuYang, Xun Zhi; Liu, Yuan Qiu; Zang, Hao; Ning, Jin Kui; Yang, Yang

2017-12-01

The distribution characteristics of carbon density under aerially seeded Pinus massoniana plantations in Ganzhou City of Jiangxi Province were studied. Total 15 factors, including site, stand, understory vegetation, litter and so on were selected to establish a relationship model between stand carbon density and influencing factors, and the main influencing factors were also screened. The results showed that the average carbon density was 98.29 t·hm -2 at stand level with soil layer (49.58 t·hm -2 ) > tree layer (45.25 t·hm -2 ) > understory vegetation layer (2.23 t·hm -2 ) > litter layer (1.23 t·hm -2 ). Significantly positive correlations were found among the tree, litter and soil layers, but not among the other layers. The main factors were tree density, avera-ge diameter at breast height (DBH), soil thickness, slope position, stand age and canopy density to affect carbon density in aerially seeded P. massoniana plantations. The partial correlation coefficients of the six main factors ranged from 0.331 to 0.434 with significance by t test. The multiple correlation coefficient of quantitative model I reached 0.796 with significance by F test (F=9.28). For stand density, the best tree density and canopy density were 1500-2100 plants·hm -2 and 0.4-0.7, respectively. The moderate density was helpful to improve ecosystem carbon sequestration. The carbon density increased with increasing stand age, DBH and soil thickness, and was higher in lower than middle and upper slope positions.

Research on the influencing factors of reverse logistics carbon footprint under sustainable development.

PubMed

Sun, Qiang

2017-10-01

With the concerns of ecological and circular economy along with sustainable development, reverse logistics has attracted the attention of enterprise. How to achieve sustainable development of reverse logistics has important practical significance of enhancing low carbon competitiveness. In this paper, the system boundary of reverse logistics carbon footprint is presented. Following the measurement of reverse logistics carbon footprint and reverse logistics carbon capacity is provided. The influencing factors of reverse logistics carbon footprint are classified into five parts such as intensity of reverse logistics, energy structure, energy efficiency, reverse logistics output, and product remanufacturing rate. The quantitative research methodology using ADF test, Johansen co-integration test, and impulse response is utilized to interpret the relationship between reverse logistics carbon footprint and the influencing factors more accurately. This research finds that energy efficiency, energy structure, and product remanufacturing rate are more capable of inhibiting reverse logistics carbon footprint. The statistical approaches will help practitioners in this field to structure their reverse logistics activities and also help academics in developing better decision models to reduce reverse logistics carbon footprint.

40 CFR 52.1627 - Control strategy and regulations: Carbon monoxide.

Code of Federal Regulations, 2010 CFR

2010-07-01

...: Carbon monoxide. 52.1627 Section 52.1627 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... § 52.1627 Control strategy and regulations: Carbon monoxide. (a) Part D Approval. The Albuquerque/Bernalillo County carbon monoxide maintenance plan as adopted on April 13, 1995, meets the requirements of...

Hydrological controls on chemical weathering in the typical carbonated river basin, SW China

NASA Astrophysics Data System (ADS)

LI, S. L.; Jin, L.; Zhong, J., Sr.

2016-12-01

The dynamics of dissolved load in the riverine system could provide an insight in understanding the surface processes, such as chemical weathering and carbon cycle. The Xijiang River is a typical carbonated river basin, located at southwestern China. The Xijiang River catchment is controlled by a humid subtropical climate. In spite of being impacted by monsoonal climate and with significant variations of discharge, the temporal variations of compositions of main ions and chemical weathering of Xijiang River are rarely documented. In this study, a systematic investigation on the seasonal and episodic water geochemistry (major ions and d13CDIC) of the major branch and outlet of Xijiang River were carried out with the purpose of 1) characterizing temporal variations of aqueous geochemistry and its controlling factors, 2) exploring the impact of hydrological controls on chemical weathering of the Xijiang River Basin. The results show that the concentrations of Cl, Na, Ca, Mg, and HCO3 are generally decreased during monsoon season, which should be mainly caused by dilution. However, the dilution effect does not strictly follow the theoretical dilution curve. Moreover, d13CDIC in the high-flow period has more negative values than in low-flow period. More negative δ13CDIC values in the river during the wet season reflected the influx of rain water with biological CO2 during the rain event. This study suggested that hydrochemistry and d13CDIC had a large variation responding to rainstorm events. The calculated results show that the weathering rates of silicate and carbonate as well as that of related CO2 consumption have a positive relation with water discharge, highlighting the hydrological controls on chemical weathering and CO2 consumption rates. The results indicated carbonated weathering rate responding to hydrological condition sensitivity in the typical carbonate river basin. This work was supported by The China National Science Fund for Outstanding Young Scholars

Controlled release of isoproturon, imidacloprid, and cyromazine from alginate-bentonite-activated carbon formulations.

PubMed

Garrido-Herrera, F J; Gonzalez-Pradas, E; Fernandez-Pérez, M

2006-12-27

Different alginate-based systems of isoproturon, imidacloprid, and cyromazine have been investigated in order to obtain controlled release (CR) properties. The basic formulation [sodium alginate (1.50%), pesticide (0.30%), and water] was modified using different amounts of bentonite and activated carbon. The higher values of encapsulation efficiency corresponded to those formulations prepared with higher percentages of activated carbon, showing higher encapsulation efficiency values for isoproturon and imidacloprid than for cyromazine, which has a higher water solubility. The kinetic experiments of imidacloprid/isoproturon release in water have shown us that the release rate is higher in imidacloprid systems than in those prepared with isoproturon. Moreover, it can be deduced that the use of bentonite and/or activated carbon sorbents reduces the release rate of the isoproturon and imidacloprid in comparison with the technical product and with alginate formulation without modifying agents. The highest decrease in release rate corresponds to the formulations prepared with the highest percentage of activated carbon. The water uptake, permeability, and time taken for 50% of the active ingredient to be released into water, T50, were calculated to compare the formulations. On the basis of a parameter of an empirical equation used to fit the pesticide release data, the release of isoproturon and imidacloprid from the various formulations into water is controlled by a diffusion mechanism. The sorption capacity of the sorbents and the permeability of the formulations were the most important factors modulating pesticide release. Finally, a linear correlation of the T50 values and the content of activated carbon in formulations were obtained.

Randomized Clinical Trial of Sevelamer Carbonate on Serum Klotho and Fibroblast Growth Factor 23 in CKD.

PubMed

Liabeuf, Sophie; Ryckelynck, Jean-Philippe; El Esper, Najeh; Ureña, Pablo; Combe, Christian; Dussol, Bertrand; Fouque, Denis; Vanhille, Philippe; Frimat, Luc; Thervet, Eric; Mentaverri, Romuald; Prié, Dominique; Choukroun, Gabriel

2017-12-07

Epidemiologic studies suggest that higher serum phosphaturic hormone fibroblast growth factor 23 levels are associated with increase morbidity and mortality. The aim of the FGF23 Reduction Efficacy of a New Phosphate Binder in CKD Trial was to evaluate the effect of sevelamer carbonate on serum C-terminal fibroblast growth factor 23 levels in normophosphatemic patients with CKD stage 3b/4. Patients with CKD, eGFR between 45 and 15 ml/min per 1.73 m 2 , fasting serum phosphate concentration >3.1 mg/dl, and serum C-terminal fibroblast growth factor 23 >80 relative units/ml were included in our double-blind, placebo-controlled, randomized multicenter study. All patients received 100,000 IU cholecalciferol at time of randomization. Participants received either placebo or sevelamer carbonate 4.8 g daily during a 12-week period. Biologic parameters, including serum C-terminal fibroblast growth factor 23, intact fibroblast growth factor 23, and α -klotho, were evaluated at baseline and 12 weeks after inclusion. Of 96 screened patients, 78 (mean±SD age: 63±13 years old; 70% men; mean eGFR: 27±9 ml/min per 1.73 m 2 ) met the inclusion criteria. At baseline, mean eGFR was 27±9 ml/min per 1.73 m 2 , mean serum phosphate level was 3.8±0.5 mg/dl, and median (interquartile range) serum C-terminal fibroblast growth factor 23 level was 157 (120-241) relative units/ml. After 12 weeks of treatment, urinary phosphate-to-creatinine ratio fell significantly in the sevelamer group. The sevelamer and placebo groups did not differ significantly in terms of median change in serum C-terminal fibroblast growth factor 23 levels: the median (interquartile range) change was 38 (-13-114) relative units/ml in the placebo group and 37 (-1-101) relative units/ml in the sevelamer group ( P =0.77). There was no significant difference in serum intact fibroblast growth factor 23, α -klotho, or phosphate levels changes between the two groups. Serum total and LDL cholesterol levels fell

Vertically aligned carbon nanofibers and related structures: Controlled synthesis and directed assembly

NASA Astrophysics Data System (ADS)

Melechko, A. V.; Merkulov, V. I.; McKnight, T. E.; Guillorn, M. A.; Klein, K. L.; Lowndes, D. H.; Simpson, M. L.

2005-02-01

The controlled synthesis of materials by methods that permit their assembly into functional nanoscale structures lies at the crux of the emerging field of nanotechnology. Although only one of several materials families is of interest, carbon-based nanostructured materials continue to attract a disproportionate share of research effort, in part because of their wide-ranging properties. Additionally, developments of the past decade in the controlled synthesis of carbon nanotubes and nanofibers have opened additional possibilities for their use as functional elements in numerous applications. Vertically aligned carbon nanofibers (VACNFs) are a subclass of carbon nanostructured materials that can be produced with a high degree of control using catalytic plasma-enhanced chemical-vapor deposition (C-PECVD). Using C-PECVD the location, diameter, length, shape, chemical composition, and orientation can be controlled during VACNF synthesis. Here we review the CVD and PECVD systems, growth control mechanisms, catalyst preparation, resultant carbon nanostructures, and VACNF properties. This is followed by a review of many of the application areas for carbon nanotubes and nanofibers including electron field-emission sources, electrochemical probes, functionalized sensor elements, scanning probe microscopy tips, nanoelectromechanical systems (NEMS), hydrogen and charge storage, and catalyst support. We end by noting gaps in the understanding of VACNF growth mechanisms and the challenges remaining in the development of methods for an even more comprehensive control of the carbon nanofiber synthesis process.

Fire Control Agent Effectiveness for Hazardous Chemical Fires: Carbon Disulfide.

DTIC Science & Technology

1981-01-01

Fires..................................... 46 12. AFFF Fire Control Data for Carbon Disulfide Fires............................. 47 13. Extinguishment...Disulfide and Hexane Fires ....... 67 22. Comparison of AFFF Fire Control Times for Carbon Disulfide and Hexane Fires ................... 68 23. Comparison of...Data .............. 27 2. Summary of Fluoroprotein Foam Fire Test Data ....... 28 3. Summary of AFFF Fire Test Data ..................... 29 4. Summary

Research on impacts of population-related factors on carbon emissions in Beijing from 1984 to 2012

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Yayun; Zhao, Tao; Wang, Yanan, E-mail: wyn3615@126.com

Carbon emissions related to population factors have aroused great attention around the world. A multitude of literature mainly focused on single demographic impacts on environmental issues at the national level, and comprehensive studies concerning population-related factors at a city level are rare. This paper employed STIRPAT (Stochastic Impacts by Regression on Population, Affluence and Technology) model incorporating PLS (Partial least squares) regression method to examine the influence of population-related factors on carbon emissions in Beijing from 1984 to 2012. Empirically results manifest that urbanization is the paramount driver. Changes in population age structure have significantly positive impacts on carbon emissions,more » and shrinking young population, continuous expansion of working age population and aging population will keep on increasing environmental pressures. Meanwhile, shrinking household size and expanding floating population boost the discharge of carbon emissions. Besides, per capita consumption is an important contributor of carbon emissions, while industry energy intensity is the main inhibitory factor. Based upon these findings and the specific circumstances of Beijing, policies such as promoting clean and renewable energy, improving population quality and advocating low carbon lifestyles should be enhanced to achieve targeted emissions reductions. - Highlights: • We employed the STIRPAT model to identify population-related factors of carbon emissions in Beijing. • Urbanization is the paramount driver of carbon emissions. • Changes in population age structure exert significantly positive impacts on carbon emissions. • Shrinking household size, expanding floating population and improving consumption level increase carbon emissions. • Industry energy intensity decreases carbon emissions.« less

Input-driven versus turnover-driven controls of simulated changes in soil carbon due to land-use change

NASA Astrophysics Data System (ADS)

Nyawira, S. S.; Nabel, J. E. M. S.; Brovkin, V.; Pongratz, J.

2017-08-01

Historical changes in soil carbon associated with land-use change (LUC) result mainly from the changes in the quantity of litter inputs to the soil and the turnover of carbon in soils. We use a factor separation technique to assess how the input-driven and turnover-driven controls, as well as their synergies, have contributed to historical changes in soil carbon associated with LUC. We apply this approach to equilibrium simulations of present-day and pre-industrial land use performed using the dynamic global vegetation model JSBACH. Our results show that both the input-driven and turnover-driven changes generally contribute to a gain in soil carbon in afforested regions and a loss in deforested regions. However, in regions where grasslands have been converted to croplands, we find an input-driven loss that is partly offset by a turnover-driven gain, which stems from a decrease in the fire-related carbon losses. Omitting land management through crop and wood harvest substantially reduces the global losses through the input-driven changes. Our study thus suggests that the dominating control of soil carbon losses is via the input-driven changes, which are more directly accessible to human management than the turnover-driven ones.

Shape-controlled synthesis of nanocarbons through direct conversion of carbon dioxide

NASA Astrophysics Data System (ADS)

Zhang, Haitao; Zhang, Xiong; Sun, Xianzhong; Ma, Yanwei

2013-12-01

Morphology control of carbon-based nanomaterials (nanocarbons) is critical to practical applications because their physical and chemical properties are highly shape-dependent. The discovery of novel shaped nanocarbons stimulates new development in carbon science and technology. Based on direct reaction of CO2 with Mg metal, we achieved controlled synthesis of several different types of nanocarbons including mesoporous graphene, carbon nanotubes, and hollow carbon nanoboxes. The last one, to our knowledge, has not been previously reported to this date. The method described here allows effective control of the shape and dimensions of nanocarbons through manipulation of reaction temperature. The formation mechanism of nanocarbons is proposed. As a proof of concept, the synthesized nanocarbons are used for electrodes in symmetrical supercapacitors, which exhibit high capacitance and good cycling stability. The reported protocols are instructive to production of nanocarbons with controlled shape and dimensions which are much desirable for many practical applications.

Growth factor controls on the distribution and carbon isotope composition of n-alkanes in leaf wax

NASA Astrophysics Data System (ADS)

Jia, C.; Xie, S.; Huang, X.

2012-12-01

Cuticular wax plays pivotal physiological and ecological roles in the interactions between plants and the environments in which they grow. Plant-derived long-chain alkanes are more resistant to decay than other biochemical polymers. n-Alkane distributions (Carbon Preference Index (CPI) values and Average Chain Length (ACL) values) and carbon isotopic values are used widely in palaeoenvironmental reconstruction. However, there is little information available on how growth stages of the plant might influence the abundance of n-alkanes in the natural environment. In this study, we analyzed n-alkane distributions and carbon isotope data from two tree species (Cinnamomum camphora (L.) Presl. and Liquidambar formosana Hance) collected monthly from 2009 to 2011 in Nanwang Shan, Wuhan, Hubei Province. CPI values for n-alkanes from C. camphora remained stable in autumn and winter but fluctuated dramatically during spring and autumn each year. Positive correlations between CPI values and the relative content of (C27+C29) were observed in both sun and shade leaves of C. camphora from April to July. In L. formosana, CPI values decreased gradually from April to December. A similar trend was observed in all three years suggesting that growth stages rather than temperature or relative humidity affected the CPI values on a seasonal timescale. In the samples of L. formosana ACL values were negatively correlated with CPI values in the growing season (from April to July) and positively correlated with CPI values in the other seasons. The δ13C values of C29 and C31 n-alkanes displayed more negative carbon isotopic values in autumn and winter compared with leaves sampled at the start of the growing season from both trees. The δ13C values of C29 and C31 n-alkanes of L. formosana decreased from April to December. These results demonstrate the importance of elucidating the growing factors that influence the distribution and δ13C values of alkanes in modern leaves prior to using CPI

Micro-/mesoporous carbons for controlled release of antipyrine and indomethacin

DOE PAGES

Saha, Dipendu; Moken, Tara; Chen, Jihua; ...

2015-02-24

Here, we have demonstrated the potential of meso- and microporous carbons in controlled release applications and targeted oral drug delivery. We have employed two mesoporous and two microporous carbons for the sustained release of one water-soluble drug (antipyrine) and one water-insoluble drug (indomethacin), using these as models to examine the controlled release characteristics. The micro-/mesoporous carbons were characterized as having a BET surface area of 372–2251 m 2 g –1 and pore volume 0.63–1.03 cm 3 g –1. The toxicity studies with E. coli bacterial cells did not reveal significant toxicity, which is in accordance with our previous studies onmore » human cells with similar materials. Mucin adsorption tests with type III pork mucin demonstrated 20–30% mucin adsorption by the carbon samples and higher mucin adsorption could be attributed to higher surface area and more oxygen functionalities. Antipyrine and indomethacin loading was 6–78% in these micro-/mesoporous carbons. The signatures in thermogravimetric studies revealed the presence of drug molecules within the porous moieties of the carbon. The partial shifting of the decomposition peak of the drug adsorbed within the carbon pores was caused by the confinement of drug molecules within the narrow pore space of the carbon. The release profiles of both drugs were examined in simulated gastric fluid (pH = 1.2) and in three other release media with respective pH values of 4.5, 6.8 and 7.4, along with varying residence times to simulate the physiological conditions of the stomach, duodenum, small intestine and colon, respectively. All the release profiles manifested diffusion controlled sustained release that corroborates the effective role of micro-/mesoporous carbons as potential drug carriers.« less

Micro-/mesoporous carbons for controlled release of antipyrine and indomethacin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saha, Dipendu; Moken, Tara; Chen, Jihua

Here, we have demonstrated the potential of meso- and microporous carbons in controlled release applications and targeted oral drug delivery. We have employed two mesoporous and two microporous carbons for the sustained release of one water-soluble drug (antipyrine) and one water-insoluble drug (indomethacin), using these as models to examine the controlled release characteristics. The micro-/mesoporous carbons were characterized as having a BET surface area of 372–2251 m 2 g –1 and pore volume 0.63–1.03 cm 3 g –1. The toxicity studies with E. coli bacterial cells did not reveal significant toxicity, which is in accordance with our previous studies onmore » human cells with similar materials. Mucin adsorption tests with type III pork mucin demonstrated 20–30% mucin adsorption by the carbon samples and higher mucin adsorption could be attributed to higher surface area and more oxygen functionalities. Antipyrine and indomethacin loading was 6–78% in these micro-/mesoporous carbons. The signatures in thermogravimetric studies revealed the presence of drug molecules within the porous moieties of the carbon. The partial shifting of the decomposition peak of the drug adsorbed within the carbon pores was caused by the confinement of drug molecules within the narrow pore space of the carbon. The release profiles of both drugs were examined in simulated gastric fluid (pH = 1.2) and in three other release media with respective pH values of 4.5, 6.8 and 7.4, along with varying residence times to simulate the physiological conditions of the stomach, duodenum, small intestine and colon, respectively. All the release profiles manifested diffusion controlled sustained release that corroborates the effective role of micro-/mesoporous carbons as potential drug carriers.« less

Shape-controlled synthesis of nanocarbons through direct conversion of carbon dioxide

PubMed Central

Zhang, Haitao; Zhang, Xiong; Sun, Xianzhong; Ma, Yanwei

2013-01-01

Morphology control of carbon-based nanomaterials (nanocarbons) is critical to practical applications because their physical and chemical properties are highly shape-dependent. The discovery of novel shaped nanocarbons stimulates new development in carbon science and technology. Based on direct reaction of CO2 with Mg metal, we achieved controlled synthesis of several different types of nanocarbons including mesoporous graphene, carbon nanotubes, and hollow carbon nanoboxes. The last one, to our knowledge, has not been previously reported to this date. The method described here allows effective control of the shape and dimensions of nanocarbons through manipulation of reaction temperature. The formation mechanism of nanocarbons is proposed. As a proof of concept, the synthesized nanocarbons are used for electrodes in symmetrical supercapacitors, which exhibit high capacitance and good cycling stability. The reported protocols are instructive to production of nanocarbons with controlled shape and dimensions which are much desirable for many practical applications. PMID:24346481

Bimetallic Metal-Organic Frameworks for Controlled Catalytic Graphitization of Nanoporous Carbons

PubMed Central

Tang, Jing; Salunkhe, Rahul R.; Zhang, Huabin; Malgras, Victor; Ahamad, Tansir; Alshehri, Saad M.; Kobayashi, Naoya; Tominaka, Satoshi; Ide, Yusuke; Kim, Jung Ho; Yamauchi, Yusuke

2016-01-01

Single metal-organic frameworks (MOFs), constructed from the coordination between one-fold metal ions and organic linkers, show limited functionalities when used as precursors for nanoporous carbon materials. Herein, we propose to merge the advantages of zinc and cobalt metals ions into one single MOF crystal (i.e., bimetallic MOFs). The organic linkers that coordinate with cobalt ions tend to yield graphitic carbons after carbonization, unlike those bridging with zinc ions, due to the controlled catalytic graphitization by the cobalt nanoparticles. In this work, we demonstrate a feasible method to achieve nanoporous carbon materials with tailored properties, including specific surface area, pore size distribution, degree of graphitization, and content of heteroatoms. The bimetallic-MOF-derived nanoporous carbon are systematically characterized, highlighting the importance of precisely controlling the properties of the carbon materials. This can be done by finely tuning the components in the bimetallic MOF precursors, and thus designing optimal carbon materials for specific applications. PMID:27471193

Controls on suspended sediment, particulate and dissolved organic carbon export from two adjacent catchments with contrasting land-uses, Exmoor UK.

NASA Astrophysics Data System (ADS)

Glendell, M.; Brazier, R. E.

2012-04-01

The fluvial export of total organic carbon (particulate and dissolved) plays an important role in the transportation of organic carbon from terrestrial to aquatic ecosystems, with implications for the understanding of the global carbon cycle and calculations of regional carbon budgets. The terrestrial biosphere contains large amounts of stored carbon in the soil and vegetation, thus a small change in the terrestrial carbon pool may have significant implications for atmospheric CO2 concentrations. Since the onset of agriculture, human activities have accelerated soil erosion rates 10- to 100- fold above all estimated natural background levels, especially in the uplands and at lower latitudes, whilst increasing DOC concentrations over the past decades have been reported in rivers across Western Europe and North America, raising concerns about potential destabilisation of the terrestrial soil carbon pool. The increased input of fine sediment and organic carbon into aquatic environments is also an important factor in stream water quality, being responsible for direct ecological effects as well as transport of a range of contaminants. Many factors, such as topography, hydrological regime and vegetation are known to influence the fluvial export of carbon from catchments. However, most work to date has focused on DOC losses from either forested or peaty catchments, with only limited studies examining the controls and rates of TOC (dissolved and particulate) fluxes from agricultural catchments, particularly during flood events. This research aims to: • Quantify the fluxes of total suspended sediment, total dissolved and total particulate carbon in two adjacent catchments with contrasting land-uses and • Examine the controlling factors of total fluvial carbon fluxes in a semi-natural and agricultural catchment in order to assess the impact of agricultural land-use on fluvial carbon export. The two contrasting study catchments (the Aller and Horner), in south

Monitoring by Control Technique - Activated Carbon Adsorber

EPA Pesticide Factsheets

Stationary source emissions monitoring is required to demonstrate that a source is meeting the requirements in Federal or state rules. This page is about Activated Carbon Adsorber control techniques used to reduce pollutant emissions.

Evaluating the air quality impacts of the 2008 Beijing Olympic Games: On-road emission factors and black carbon profiles

NASA Astrophysics Data System (ADS)

Wang, Xing; Westerdahl, Dane; Chen, Lung Chi; Wu, Ye; Hao, Jiming; Pan, Xiaochuan; Guo, Xinbiao; Zhang, K. Max

The aggressive traffic interventions and emission control measures implemented to improve air quality during the 2008 Beijing Olympic Games created a valuable case study to evaluate the effectiveness of these measures on mitigating air pollution and protecting public health. In this paper, we report the results from our field campaign in summer 2008 on the on-road emission factors of carbon monoxide, black carbon (BC) and ultrafine particles (UFP) as well as the ambient BC concentrations. The fleet average emission factors for light-duty gasoline vehicles (LDGV) showed considerable reduction in the Olympic year (2008) compared to the pre-Olympic year (2007). Our measurement of Black Carbon (BC), a primary pollutant, at different elevations at the ambient site suggests consistent decrease in BC concentrations as the height increased near the ground level, which indicates that the nearby ground level sources, probably dominated by traffic, contributed to a large portion of BC concentrations in the lower atmospheric layer in Beijing during summertime. These observations indicate that people living in near ground levels experience higher exposures than those living in higher floors in Beijing. The BC diurnal patterns on days when traffic control were in place during the Olympic Games were compared to those on non-traffic-control days in both 2007 and in 2008. These patterns strongly suggest that diesel trucks are a major source of summertime BC in Beijing. The median BC concentration on Olympic days was 3.7 μg m -3, which was dramatically lower than the value on non-traffic-control days, indicating the effectiveness of traffic control regulations in BC reduction in Beijing.

40 CFR 52.2353 - Control strategy: Carbon monoxide.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 5 2012-07-01 2012-07-01 false Control strategy: Carbon monoxide. 52.2353 Section 52.2353 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) Utah § 52.2353 Control strategy...

40 CFR 52.1340 - Control strategy: Carbon monoxide.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 4 2011-07-01 2011-07-01 false Control strategy: Carbon monoxide. 52.1340 Section 52.1340 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) Missouri § 52.1340 Control strategy...

40 CFR 52.1340 - Control strategy: Carbon monoxide.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 4 2012-07-01 2012-07-01 false Control strategy: Carbon monoxide. 52.1340 Section 52.1340 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) Missouri § 52.1340 Control strategy...

40 CFR 52.2353 - Control strategy: Carbon monoxide.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 4 2011-07-01 2011-07-01 false Control strategy: Carbon monoxide. 52.2353 Section 52.2353 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) Utah § 52.2353 Control strategy...

[Correlation Among Soil Organic Carbon, Soil Inorganic Carbon and the Environmental Factors in a Typical Oasis in the Southern Edge of the Tarim Basin].

PubMed

Gong, Lu; Zhu, Mei-ling; Liu, Zeng-yuan; Zhang, Xue-ni; Xie, Li-na

2016-04-15

We analyzed the differentiation among the environmental factors and soil organic/inorganic carbon contents of irrigated desert soil, brown desert soil, saline soil and aeolian sandy soil by classical statistics methods, and studied the correlation between soil carbon contents and the environmental factor by redundancy analysis (RDA) in a typical oasis of Yutian in the southern edge of the Tarim Basin. The results showed that the average contents of soil organic carbon and soil inorganic carbon were 2.51 g · kg⁻¹ and 25.63 g · kg⁻¹ respectively. The soil organic carbon content of the irrigated desert soil was significantly higher than those of brown desert soil, saline soil and aeolian sandy soil, while the inorganic carbon content of aeolian sandy soil was significantly higher than those of other soil types. The soil moisture and nutrient content were the highest in the irrigated desert soil and the lowest in the aeolian sandy sail. All soil types had high degree of salinization except the irrigated desert soil. The RDA results showed that the impacts of environmental factors on soil carbon contents ranked in order of importance were total nitrogen > available phosphorus > soil moisture > ground water depth > available potassium > pH > total salt. The soil carbon contents correlated extremely significantly with total nitrogen, available phosphorus, soil moisture and ground water depth (P < 0.01), and it correlated significantly with available potassium and pH (P < 0.05). There was no significant correlation between soil carbon contents and other environmental factors (P > 0.05).

Urban Household Carbon Emission and Contributing Factors in the Yangtze River Delta, China

PubMed Central

Xu, Xibao; Tan, Yan; Chen, Shuang; Yang, Guishan; Su, Weizhong

2015-01-01

Carbon reduction at the household level is an integral part of carbon mitigation. This study analyses the characteristics, effects, contributing factors and policies for urban household carbon emissions in the Yangtze River Delta of China. Primary data was collected through structured questionnaire surveys in three cities in the region – Nanjing, Ningbo, and Changzhou in 2011. The survey data was first used to estimate the magnitude of household carbon emissions in different urban contexts. It then examined how, and to what extent, each set of demographic, economic, behavioral/cognitive and spatial factors influence carbon emissions at the household level. The average of urban household carbon emissions in the region was estimated to be 5.96 tonnes CO2 in 2010. Energy consumption, daily commuting, garbage disposal and long-distance travel accounted for 51.2%, 21.3%, 16.0% and 11.5% of the total emission, respectively. Regulating rapidly growing car-holdings of urban households, stabilizing population growth, and transiting residents’ low-carbon awareness to household behavior in energy saving and other spheres of consumption in the context of rapid population aging and the growing middle income class are suggested as critical measures for carbon mitigation among urban households in the Yangtze River Delta. PMID:25884853

Improved carbon control in the sintering of structural PM parts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nowotarski, M.; Gaines, G.

1981-12-01

The use of a nitrogen-methanol atmosphere and a system of control of the atmosphere in furnace zones to provide improved control of carbon in sintering of sprockets are described.A new process has been developed by the Linde Div. of Union Carbide for the sintering of structural PM parts. The process is based on a nitrogen/methanol sintering atmosphere and features superior carbon control (/plus or minus/.03%), elimination of sooting due to lubricant decomposition, and significantly reduced furnace atmosphere gas flows as compared to typical endothermic atmosphere gas consumption.

Identification of an algal carbon fixation-enhancing factor extracted from Paramecium bursaria.

PubMed

Kato, Yutaka; Imamura, Nobutaka

2011-01-01

The green ciliate Paramecium bursaria contains several hundred symbiotic Chlorella species. We previously reported that symbiotic algal carbon fixation is enhanced by P. bursaria extracts and that the enhancing factor is a heat-stable, low-molecular-weight, water-soluble compound. To identify the factor, further experiments were carried out. The enhancing activity remained even when organic compounds in the extract were completely combusted at 700 degrees C, suggesting that the factor is an inorganic substance. Measurement of the major cations, K+, Ca2+, and Mg2+, by an electrode and titration of the extract resulted in concentrations of 0.90 mM, 0.55 mM, and 0.21 mM, respectively. To evaluate the effect of these cations, a mixture of the cations at the measured concentrations was prepared, and symbiotic algal carbon fixation was measured in the solution. The results demonstrated that the fixation was enhanced to the same extent as with the P. bursaria extract, and thus this mixture of K+, Ca2+, and Mg2+ was concluded to be the carbon fixation-enhancing factor. There was no effect of the cation mixture on free-living C. vulgaris. Comparison of the cation concentrations of nonsymbiotic and symbiotic Paramecium extracts revealed that the concentrations of K+ and Mg2+ in nonsymbiotic Paramecium extracts were too low to enhance symbiotic algal carbon fixation, suggesting that symbiotic P. bursaria provide suitable cation conditions for photosynthesis to its symbiotic Chlorella.

Trophic discrimination factors of stable carbon and nitrogen isotopes in hair of corn fed wild boar.

PubMed

Holá, Michaela; Ježek, Miloš; Kušta, Tomáš; Košatová, Michaela

2015-01-01

Stable isotope measurements are increasingly being used to gain insights into the nutritional ecology of many wildlife species and their role in ecosystem structure and function. Such studies require estimations of trophic discrimination factors (i.e. differences in the isotopic ratio between the consumer and its diet). Although trophic discrimination factors are tissue- and species-specific, researchers often rely on generalized, and fixed trophic discrimination factors that have not been experimentally derived. In this experimental study, captive wild boar (Sus scrofa) were fed a controlled diet of corn (Zea mays), a popular and increasingly dominant food source for wild boar in the Czech Republic and elsewhere in Europe, and trophic discrimination factors for stable carbon (Δ13C) and nitrogen (Δ15N) isotopes were determined from hair samples. The mean Δ13C and Δ15N in wild boar hair were -2.3‰ and +3.5‰, respectively. Also, in order to facilitate future derivations of isotopic measurements along wild boar hair, we calculated the average hair growth rate to be 1.1 mm d(-1). Our results serve as a baseline for interpreting isotopic patterns of free-ranging wild boar in current European agricultural landscapes. However, future research is needed in order to provide a broader understanding of the processes underlying the variation in trophic discrimination factors of carbon and nitrogen across of variety of diet types.

Controlling Processes on Carbonate Chemistry across the Pacific

NASA Astrophysics Data System (ADS)

Hartman, S. E.

2016-12-01

The SWIRE NOC Ocean Monitoring System (SNOMS) project is an innovative programme helping to answer important questions about global climate change by using a commercial ship of opportunity to measure carbon in the surface of the ocean. Daily sampling coupled to continuous underway observation from a ship of opportunity (MV Shengking) provides new insights into the processes controlling variability in the carbonate system across the Pacific. The ships track runs from Vancouver (Canada) to Brisbane (Australia). Daily samples were taken on-board and measurements of Total alkalinity (TA) and total dissolved inorganic carbon (DIC) were determined. This was alongside measurements of nutrients and continuous records of temperature, salinity, chlorophyll-fluorescence, carbon dioxide and dissolved oxygen (DO). These sensor based measurements were validated using the discrete samples. Carbon dioxide calculated from DIC and TA showed an offset from the sensor data of up to 8uatm. This and comparisons with climatology were used to calibrate the sensor data. The data have been compared with previous data from the MV Pacific Celebes that ran a similar route until 2012. The data show a clear increase in seawater carbon dioxide, tracking the atmospheric increases. Along track the partial pressure of seawater carbon dioxide varied by over 150 uatm. The highest values were seen just south of the equator in the Pacific, which is an important source region for carbon dioxide to the atmosphere.

Factors and processes governing the C-14 content of carbonate in desert soils

NASA Technical Reports Server (NTRS)

Amundson, Ronald; Wang, Yang; Chadwick, Oliver; Trumbore, Susan; Mcfadden, Leslie; Mcdonald, Eric; Wells, Steven; Deniro, Michael

1994-01-01

A model is presented describing the factors and processes which determine the measured C-14 ages of soil calcium carbonate. Pedogenic carbonate forms in isotopic equilium with soil CO2. Carbon dioxide in soils is a mixture of CO2 derived from two biological sources: respiration by living plant roots and respiration of microorganisms decomposing soil humus. The relative proportion of these two CO2 sources can greatly affect the initial C-14 content of pedogenic carbonate: the greater the contribution of humus-derived CO2, the greater the initial C-14 age of the carbonate mineral. For any given mixture of CO2 sources, the steady-state (14)CO2 distribution vs. soil depth can be described by a production/diffusion model. As a soil ages, the C-14 age of soil humus increases, as does the steady-state C-14 age of soil CO2 and the initial C-14 age of any pedogenic carbonate which forms. The mean C-14 age of a complete pedogenic carbonate coating or nodule will underestimate the true age of the soil carbonate. This discrepancy increases the older a soil becomes. Partial removal of outer (and younger) carbonate coatings greatly improves the relationship between measured C-14 age and true age. Although the production/diffusion model qualitatively explains the C-14 age of pedogenic carbonate vs. soil depth in many soils, other factors, such as climate change, may contribute to the observed trends, particularily in soils older than the Holocene.

Input-driven versus turnover-driven controls of simulated changes in soil carbon due to land-use change

NASA Astrophysics Data System (ADS)

Nyawira, Sylvia; Nabel, Julia; Brovkin, Victor; Pongratz, Julia

2017-04-01

Modelling studies estimate a global loss in soil carbon caused by land-use changes (LUCs) over the last century. Although it is known that this loss stems from the changes in quantity of litter inputs from the vegetation to the soil (input-driven) and the changes in turnover of carbon in the soil (turnover-driven) associated with LUC, the individual contribution of these two controls to the total changes have not been assessed. Using the dynamic global vegetation model JSBACH, we apply a factor separation approach to isolate the contribution of the input-driven and turnover-driven changes, as well as their synergies, to the total changes in soil carbon from LUC. To assess how land management through crop and wood harvest influences the controls, we compare our results for simulations with and without land management. Our results reveal that for the afforested regions both the input-driven and turnover-driven changes generally result in soil carbon gain, whereas deforested regions exhibit a loss. However, for regions where croplands have increased at the expense of grasslands and pastures, the input-driven changes result in a loss that is partly offset by a gain via the turnover-driven changes. This gain stems from a decrease in the fire-related carbon losses when grasslands or pastures are replaced with croplands. Omitting land management reduces the carbon losses in regions where natural vegetation has been converted to croplands and enhances the gain in afforested regions. The global simulated losses are substantially reduced from 54.0 Pg C to 22.0 Pg C, with the input-driven losses reducing from 54.7 Pg C to 24.9 Pg C. Our study shows that the dominating control of soil carbon losses is through the input-driven changes, which are more directly influenced by human management than the turnover-driven ones.

Versatile NiO/mesoporous carbon nanodisks: controlled synthesis from hexagon shaped heterobimetallic metal-organic frameworks.

PubMed

Zeng, Dehong; Yang, Ying; Yang, Feng; Guo, Fangmin; Yang, Senjie; Liu, Baijun; Hao, Shijie; Ren, Yang

2017-08-24

Hexagonal NiO/mesoporous carbon nanodisks (NiO/MCN) are facilely and controllably synthesized via constructing nickel-zinc trimesic acid heterobimetallic metal-organic framework (HMOF) disks before pyrolysis at 910 °C. Tailoring the Ni/(Zn + Ni) feed ratio and the reaction time during the HMOF synthesis creates a well-defined hexagonal carbon nanodisk with properly populated NiO nanocrystals while maintaining high porosity and conductivity. Such an elaborately fabricated NiO/MCN is highly stable, and exhibits the largest specific capacitance of 261 F g -1 and the highest specific activity factor of 1.93 s -1 g -1 of any composite nanodisk during the capacitive test and 4-nitrophenol reduction, respectively.

State factor relationships of dissolved organic carbon and nitrogen losses from unpolluted temperate forest watersheds

USGS Publications Warehouse

Perakis, S.S.; Hedin, L.O.

2007-01-01

We sampled 100 unpolluted, old-growth forested watersheds, divided among 13 separate study areas over 5 years in temperate southern Chile and Argentina, to evaluate relationships among dominant soil-forming state factors and dissolved carbon and nitrogen concentrations in watershed streams. These watersheds provide a unique opportunity to examine broad-scale controls over carbon (C) and nitrogen (N) biogeochemistry in the absence of significant human disturbance from chronic N deposition and land use change. Variations in the ratio dissolved organic carbon (DOC) to nitrogen (DON) in watershed streams differed by underlying soil parent material, with average C:N = 29 for watersheds underlain by volcanic ash and basalt versus C:N = 73 for sedimentary and metamorphic parent materials, consistent with stronger adsorption of low C:N hydrophobic materials by amorphous clays commonly associated with volcanic ash and basalt weathering. Mean annual precipitation was related positively to variations in both DOC (range: 0.2-9.7 mg C/L) and DON (range: 0.008-0.135 mg N/L) across study areas, suggesting that variations in water volume and concentration may act synergistically to influence C and N losses across dry to wet gradients in these forest ecosystems. Dominance of vegetation by broadleaf versus coniferous trees had negligible effects on organic C and N concentrations in comparison to abiotic factors. We conclude that precipitation volume and soil parent material are important controls over chemical losses of dissolved organic C and N from unpolluted temperate forest watersheds. Our results raise the possibility that biotic imprints on watershed C and N losses may be less pronounced in naturally N-poor forests than in areas impacted by land use change and chronic N deposition. Copyright 2007 by the American Geophysical Union.

Modelling the nonlinear behaviour of double walled carbon nanotube based resonator with curvature factors

NASA Astrophysics Data System (ADS)

Patel, Ajay M.; Joshi, Anand Y.

2016-10-01

This paper deals with the nonlinear vibration analysis of a double walled carbon nanotube based mass sensor with curvature factor or waviness, which is doubly clamped at a source and a drain. Nonlinear vibrational behaviour of a double-walled carbon nanotube excited harmonically near its primary resonance is considered. The double walled carbon nanotube is harmonically excited by the addition of an excitation force. The modelling involves stretching of the mid plane and damping as per phenomenon. The equation of motion involves four nonlinear terms for inner and outer tubes of DWCNT due to the curved geometry and the stretching of the central plane due to the boundary conditions. The vibrational behaviour of the double walled carbon nanotube with different surface deviations along its axis is analyzed in the context of the time response, Poincaré maps and Fast Fourier Transformation diagrams. The appearance of instability and chaos in the dynamic response is observed as the curvature factor on double walled carbon nanotube is changed. The phenomenon of Periodic doubling and intermittency are observed as the pathway to chaos. The regions of periodic, sub-harmonic and chaotic behaviour are clearly seen to be dependent on added mass and the curvature factors in the double walled carbon nanotube. Poincaré maps and frequency spectra are used to explicate and to demonstrate the miscellany of the system behaviour. With the increase in the curvature factor system excitations increases and results in an increase of the vibration amplitude with reduction in excitation frequency.

Factors influencing organic carbon preservation in marine sediments

NASA Technical Reports Server (NTRS)

Canfield, D. E.

1994-01-01

The organic matter that escapes decomposition is buried and preserved in marine sediments, with much debate as to whether the amount depends on bottom-water O2 concentration. One group argues that decomposition is more efficient with O2, and hence, organic carbon will be preferentially oxidized in its presence, and preserved in its absence. Another group argues that the kinetics of organic matter decomposition are similar in the presence and absence of O2, and there should be no influence of O2 on preservation. A compilation of carbon preservation shows that both groups are right, depending on the circumstances of deposition. At high rates of deposition, such as near continental margins, little difference in preservation is found with varying bottom-water O2. It is important that most carbon in these sediments decomposes by anaerobic pathways regardless of bottom-water O2. Hence, little influence of bottom-water O2 on preservation would, in fact, be expected. As sedimentation rate drops, sediments deposited under oxygenated bottom water become progressively more aerobic, while euxinic sediments remain anaerobic. Under these circumstances, the relative efficiencies of aerobic and anaerobic decomposition could affect preservation. Indeed, enhanced preservation is observed in low-O2 and euxinic environments. To explore in detail the factors contributing to this enhanced carbon preservation, aspects of the biochemistries of the aerobic and anaerobic process are reviewed. Other potential influences on preservation are also explored. Finally, a new model for organic carbon decomposition, the "pseudo-G" model, is developed. This model couples the degradation of refractory organic matter to the overall metabolic activity of the sediment, and has consequences for carbon preservation due to the mixing together of labile and refractory organic matter by bioturbation.

MODELING MERCURY CONTROL WITH POWDERED ACTIVATED CARBON

EPA Science Inventory

The paper presents a mathematical model of total mercury removed from the flue gas at coal-fired plants equipped with powdered activated carbon (PAC) injection for Mercury control. The developed algorithms account for mercury removal by both existing equipment and an added PAC in...

Local gate control in carbon nanotube quantum devices

NASA Astrophysics Data System (ADS)

Biercuk, Michael Jordan

This thesis presents transport measurements of carbon nanotube electronic devices operated in the quantum regime. Nanotubes are contacted by source and drain electrodes, and multiple lithographically-patterned electrostatic gates are aligned to each device. Transport measurements of device conductance or current as a function of local gate voltages reveal that local gates couple primarily to the proximal section of the nanotube, hence providing spatially localized control over carrier density along the nanotube length. Further, using several different techniques we are able to produce local depletion regions along the length of a tube. This phenomenon is explored in detail for different contact metals to the nanotube. We utilize local gating techniques to study multiple quantum dots in carbon nanotubes produced both by naturally occurring defects, and by the controlled application of voltages to depletion gates. We study double quantum dots in detail, where transport measurements reveal honeycomb charge stability diagrams. We extract values of energy-level spacings, capacitances, and interaction energies for this system, and demonstrate independent control over all relevant tunneling rates. We report rf-reflectometry measurements of gate-defined carbon nanotube quantum dots with integrated charge sensors. Aluminum rf-SETs are electrostatically coupled to carbon nanotube devices and detect single electron charging phenomena in the Coulomb blockade regime. Simultaneous correlated measurements of single electron charging are made using reflected rf power from the nanotube itself and from the rf-SET on microsecond time scales. We map charge stability diagrams for the nanotube quantum dot via charge sensing, observing Coulomb charging diamonds beyond the first order. Conductance measurements of carbon nanotubes containing gated local depletion regions exhibit plateaus as a function of gate voltage, spaced by approximately 1e2/h, the quantum of conductance for a single

Fuzzy comprehensive evaluation of multiple environmental factors for swine building assessment and control.

PubMed

Xie, Qiuju; Ni, Ji-Qin; Su, Zhongbin

2017-10-15

In confined swine buildings, temperature, humidity, and air quality are all important for animal health and productivity. However, the current swine building environmental control is only based on temperature; and evaluation and control methods based on multiple environmental factors are needed. In this paper, fuzzy comprehensive evaluation (FCE) theory was adopted for multi-factor assessment of environmental quality in two commercial swine buildings using real measurement data. An assessment index system and membership functions were established; and predetermined weights were given using analytic hierarchy process (AHP) combined with knowledge of experts. The results show that multi-factors such as temperature, humidity, and concentrations of ammonia (NH 3 ), carbon dioxide (CO 2 ), and hydrogen sulfide (H 2 S) can be successfully integrated in FCE for swine building environment assessment. The FCE method has a high correlation coefficient of 0.737 compared with the method of single-factor evaluation (SFE). The FCE method can significantly increase the sensitivity and perform an effective and integrative assessment. It can be used as part of environmental controlling and warning systems for swine building environment management to improve swine production and welfare. Copyright © 2017 Elsevier B.V. All rights reserved.

Active Control of pH in the Bioculture System Through Carbon Dioxide Control

NASA Technical Reports Server (NTRS)

Monhollon, Luke; Pletcher, David; Hauss, Jessica

2016-01-01

For successful cell research, the growth culture environment must be tightly controlled. Deviance from the optimal conditions will mask the desired variable being analyzed or lead to inconstancies in the results. In standard laboratories, technology and procedures are readily available for the reliable control of variables such as temperature, pH, nutrient loading, and dissolved gases. Due to the nature of spaceflight, and the inherent constraints to engineering designs, these same elements become a challenge to maintain at stable values by both automated and manual approaches. Launch mass, volume, and power usage create significant constraints to cell culture systems; nonetheless, innovative solutions for active environmental controls are available. The acidity of the growth media cannot be measured through standard probes due to the degradation of electrodes and reliance on indicators for chromatography. Alternatively, carbon dioxide sensors are capable of monitoring the pH by leveraging the relationship between the partial pressure of carbon dioxide and carbonic acid in solution across a membrane. In microgravity cell growth systems, the gas delivery system can be used to actively maintain the media at the proper acidity by maintaining a suitable gas mixture around permeable tubing. Through this method, launch mass and volume are significantly reduced through the efficient use of the limited gas supply in orbit.

Influence factors and forecast of carbon emission in China: structure adjustment for emission peak

NASA Astrophysics Data System (ADS)

Wang, B.; Cui, C. Q.; Li, Z. P.

2018-02-01

This paper introduced Principal Component Analysis and Multivariate Linear Regression Model to verify long-term balance relationships between Carbon Emissions and the impact factors. The integrated model of improved PCA and multivariate regression analysis model is attainable to figure out the pattern of carbon emission sources. Main empirical results indicate that among all selected variables, the role of energy consumption scale was largest. GDP and Population follow and also have significant impacts on carbon emission. Industrialization rate and fossil fuel proportion, which is the indicator of reflecting the economic structure and energy structure, have a higher importance than the factor of urbanization rate and the dweller consumption level of urban areas. In this way, some suggestions are put forward for government to achieve the peak of carbon emissions.

Automatic Control of Arc Process for Making Carbon Nanotubes

NASA Technical Reports Server (NTRS)

Scott, Carl D.; Pulumbarit, Robert B.; Victor, Joe

2004-01-01

An automatic-control system has been devised for a process in which carbon nanotubes are produced in an arc between a catalyst-filled carbon anode and a graphite cathode. The control system includes a motor-driven screw that adjusts the distance between the electrodes. The system also includes a bridge circuit that puts out a voltage proportional to the difference between (1) the actual value of potential drop across the arc and (2) a reference value between 38 and 40 V (corresponding to a current of about 100 A) at which the yield of carbon nanotubes is maximized. Utilizing the fact that the potential drop across the arc increases with the interelectrode gap, the output of the bridge circuit is fed to a motor-control circuit that causes the motor to move the anode toward or away from the cathode if the actual potential drop is more or less, respectively, than the reference potential. Thus, the system regulates the interelectrode gap to maintain the optimum potential drop. The system also includes circuitry that records the potential drop across the arc and the relative position of the anode holder as function of time.

Spatial distribution of soil organic carbon and its influencing factors in desert grasslands of the Hexi Corridor, northwest China.

PubMed

Wang, Min; Su, Yongzhong; Yang, Xiao

2014-01-01

Knowledge of the distribution patterns of soil organic carbon (SOC) and factors that influence these patterns is crucial for understanding the carbon cycle. The objectives of this study were to determine the spatial distribution pattern of soil organic carbon density (SOCD) and the controlling factors in arid desert grasslands of northwest China. The above- and belowground biomass and SOCD in 260 soil profiles from 52 sites over 2.7×10(4) km2 were investigated. Combined with a satellite-based dataset of an enhanced vegetation index during 2011-2012 and climatic factors at different sites, the relationships between SOCD and biotic and abiotic factors were identified. The results indicated that the mean SOCD was 1.20 (SD:+/- 0.85), 1.73 (SD:+/- 1.20), and 2.69 (SD:+/- 1.91) kg m(-2) at soil depths of 0-30 cm, 0-50 cm, and 0-100 cm, respectively, which was smaller than other estimates in temperate grassland, steppe, and desert-grassland ecosystems. The spatial distribution of SOCD gradually decreased from the southeast to the northwest, corresponding to the precipitation gradient. SOCD increased significantly with vegetation biomass, annual precipitation, soil moisture, clay and silt content, and decreased with mean annual temperature and sand content. The correlation between BGB and SOCD was closer than the correlation between AGB and SOCD. Variables could together explain about 69.8%, 74.4%, and 78.9% of total variation in SOCD at 0-30 cm, 0-50 cm, and 0-100 cm, respectively. In addition, we found that mean annual temperature is more important than other abiotic factors in determining SOCD in arid desert grasslands in our study area. The information obtained in this study provides a basis for accurately estimating SOC stocks and assessing carbon (C) sequestration potential in the desert grasslands of northwest China.

Soil carbon distribution in Alaska in relation to soil-forming factors

USGS Publications Warehouse

Johnson, K.D.; Harden, J.; McGuire, A.D.; Bliss, N.B.; Bockheim, James G.; Clark, M.R.; Nettleton-Hollingsworth, T.; Jorgenson, M.T.; Kane, E.S.; Mack, M.; O'Donnell, J.; Ping, C.-L.; Schuur, E.A.G.; Turetsky, M.R.; Valentine, D.W.

2011-01-01

The direction and magnitude of soil organic carbon (SOC) changes in response to climate change remain unclear and depend on the spatial distribution of SOC across landscapes. Uncertainties regarding the fate of SOC are greater in high-latitude systems where data are sparse and the soils are affected by sub-zero temperatures. To address these issues in Alaska, a first-order assessment of data gaps and spatial distributions of SOC was conducted from a recently compiled soil carbon database. Temperature and landform type were the dominant controls on SOC distribution for selected ecoregions. Mean SOC pools (to a depth of 1-m) varied by three, seven and ten-fold across ecoregion, landform, and ecosystem types, respectively. Climate interactions with landform type and SOC were greatest in the uplands. For upland SOC there was a six-fold non-linear increase in SOC with latitude (i.e., temperature) where SOC was lowest in the Intermontane Boreal compared to the Arctic Tundra and Coastal Rainforest. Additionally, in upland systems mineral SOC pools decreased as climate became more continental, suggesting that the lower productivity, higher decomposition rates and fire activity, common in continental climates, interacted to reduce mineral SOC. For lowland systems, in contrast, these interactions and their impacts on SOC were muted or absent making SOC in these environments more comparable across latitudes. Thus, the magnitudes of SOC change across temperature gradients were non-uniform and depended on landform type. Additional factors that appeared to be related to SOC distribution within ecoregions included stand age, aspect, and permafrost presence or absence in black spruce stands. Overall, these results indicate the influence of major interactions between temperature-controlled decomposition and topography on SOC in high-latitude systems. However, there remains a need for more SOC data from wetlands and boreal-region permafrost soils, especially at depths > 1 m in

Role of vegetation and edaphic factors in controlling diversity and use of different carbon sources in semi-arid ecosystems

NASA Astrophysics Data System (ADS)

Lohse, K. A.; McLain, J. E.; Harman, C. J.; Sivapalan, M.; Troch, P. A.

2010-12-01

Microbially-mediated soil carbon cycling is closely linked to soil moisture and temperature. Climate change is predicted to increase intra-annual precipitation variability (i.e. less frequent yet more intense precipitation events) and alter biogeochemical processes due to shifts in soil moisture dynamics and inputs of carbon. However, the responses of soil biology and chemistry to predicted climate change, and their concomitant feedbacks on ecosystem productivity and biogeochemical processes are poorly understood. We collected soils at three different elevations in the Santa Catalina Mountains, AZ and quantified carbon utilization during pre-monsoon precipitation conditions. Contrasting parent materials (schist and granite) were paired at each elevation. We expected climate to determine the overall activity of soil fungal and bacterial communities and diversity of soil C utilization, and differences in parent material to modify these responses through controls on soil physical properties. We used EcoPlateTM C utilization assays to determine the relative abundance of soil bacterial and fungal populations and rate and diversity of carbon utilization. Additional plates were incubated with inhibitors selective to fungal or bacterial activity to assess relative contribution of these microbial groups to overall C utilization. We analyzed soils for soil organic matter, total C and N, particle size analysis and soil moisture content via both gravimetric and volumetric methods to assess the influences of soil physical and chemical properties on the measured biological responses. Consistent with our expectations, overall microbial activity was highest at the uppermost conifer elevation sites compared to the middle and lower elevation sites. In contrast to our expectations, however, overall activity was lower at the mid elevation oak woodland sites compared to the low elevation desert sites. Also consistent with our expectations was the observation that overall activities

Trophic Discrimination Factors of Stable Carbon and Nitrogen Isotopes in Hair of Corn Fed Wild Boar

PubMed Central

Holá, Michaela; Ježek, Miloš; Kušta, Tomáš; Košatová, Michaela

2015-01-01

Stable isotope measurements are increasingly being used to gain insights into the nutritional ecology of many wildlife species and their role in ecosystem structure and function. Such studies require estimations of trophic discrimination factors (i.e. differences in the isotopic ratio between the consumer and its diet). Although trophic discrimination factors are tissue- and species- specific, researchers often rely on generalized, and fixed trophic discrimination factors that have not been experimentally derived. In this experimental study, captive wild boar (Sus scrofa) were fed a controlled diet of corn (Zea mays), a popular and increasingly dominant food source for wild boar in the Czech Republic and elsewhere in Europe, and trophic discrimination factors for stable carbon (Δ13C) and nitrogen (Δ15N) isotopes were determined from hair samples. The mean Δ13C and Δ15N in wild boar hair were –2.3 ‰ and +3.5 ‰, respectively. Also, in order to facilitate future derivations of isotopic measurements along wild boar hair, we calculated the average hair growth rate to be 1.1 mm d-1. Our results serve as a baseline for interpreting isotopic patterns of free-ranging wild boar in current European agricultural landscapes. However, future research is needed in order to provide a broader understanding of the processes underlying the variation in trophic discrimination factors of carbon and nitrogen across of variety of diet types. PMID:25915400

Double resonance calibration of g factor standards: Carbon fibers as a high precision standard

NASA Astrophysics Data System (ADS)

Herb, Konstantin; Tschaggelar, Rene; Denninger, Gert; Jeschke, Gunnar

2018-04-01

The g factor of paramagnetic defects in commercial high performance carbon fibers was determined by a double resonance experiment based on the Overhauser shift due to hyperfine coupled protons. Our carbon fibers exhibit a single, narrow and perfectly Lorentzian shaped ESR line and a g factor slightly higher than gfree with g = 2.002644 =gfree · (1 + 162ppm) with a relative uncertainty of 15ppm . This precisely known g factor and their inertness qualify them as a high precision g factor standard for general purposes. The double resonance experiment for calibration is applicable to other potential standards with a hyperfine interaction averaged by a process with very short correlation time.

Deep-Water Resedimented Carbonate Exploration Play Types: Controls and Models

NASA Astrophysics Data System (ADS)

Minzoni, M.; Janson, X.; Kerans, C.; Playton, T.; Winefield, P.; Burgess, P. M.

2016-12-01

Deepwater resedimented deposits have been described in both modern and ancient carbonate sequences, many with good reservoir potential, for example the giant Cretaceous Poza Rica field in Mexico ( 40 MMBoe), the Mississippian Tangiz field in Kazakhstan, and several fields in the U.S. Permian basin (several Tcf gas). Nevertheless, carbonate slope and basin systems remain poorly understood when compared to their siliciclastic counterparts. Legacy published and unpublished work, combined with a global database of surface and sub-surface examples of resedimented carbonates, has highlighted that downslope resedimentation of carbonate material is in large part controlled by the evolution of the parent platform margin, which in turn is best characterized in terms of various controlling processes such as the carbonate factory type, tectonic setting, eustatic variations, and prevailing wind direction and ocean current patterns. Two generic play types emerge: (i) attached carbonate slope play -developed immediately adjacent to the parent carbonate platform and dominated by rock fall and platform collapse deposits or in situ boundstone; and (ii) detached carbonate slope play - deposited further from the platform margin via channelized turbidity currents and other mass-flow processes. High-rising, steep, bypass platform margins with collapse scars and grain-dominated factories have the highest potential to generate channelized and detached deep-water reservoirs with high initial porosity and permeability. Best reservoirs are aragonitic grainstones transported from the platform into the adjacent basin, and undergoing dissolution in submarine undersaturated water with early formation of secondary porosity to further enhance reservoir properties. Any exploration model aiming at identifying potential resedimented carbonate plays should be based on carbonate platform configurations and factory types favorable for re-sedimentation of large sedimentary bodies and preservation or

Modeling physical and biogeochemical controls over carbon accumulation in a boreal forest soil

USGS Publications Warehouse

Carrasco, J.J.; Neff, J.C.; Harden, J.W.

2006-01-01

Boreal soils are important to the global C cycle owing to large C stocks, repeated disturbance from fire, and the potential for permafrost thaw to expose previously stable, buried C. To evaluate the primary mechanisms responsible for both short- and long-term C accumulation in boreal soils, we developed a multi-isotope (12,14C) Soil C model with dynamic soil layers that develop through time as soil organic matter burns and reaccumulates. We then evaluated the mechanisms that control organic matter turnover in boreal regions including carbon input rates, substrate recalcitrance, soil moisture and temperature, and the presence of historical permafrost to assess the importance of these factors in boreal C accumulation. Results indicate that total C accumulation is controlled by the rate of carbon input, decomposition rates, and the presence of historical permafrost. However, unlike more temperate ecosystems, one of the key mechanisms involved in C preservation in boreal soils examined here is the cooling of subsurface soil layers as soil depth increases rather than increasing recalcitrance in subsurface soils. The propagation of the 14C bomb spike into soils also illustrates the importance of historical permafrost and twentieth century warming in contemporary boreal soil respiration fluxes. Both 14C and total C simulation data also strongly suggest that boreal SOM need not be recalcitrant to accumulate; the strong role of soil temperature controls on boreal C accumulation at our modeling test site in Manitoba, Canada, indicates that carbon in the deep organic soil horizons is probably relatively labile and thus subject to perturbations that result from changing climatic conditions in the future. Copyright 2006 by the American Geophysical Union.

Sample Dilution and Bacterial Community Composition Influence Empirical Leucine-to-Carbon Conversion Factors in Surface Waters of the World's Oceans

PubMed Central

Hernando-Morales, Víctor; Cornejo-Castillo, Francisco M.; Alonso-Sáez, Laura; Sarmento, Hugo; Valencia-Vila, Joaquín; Serrano Catalá, Teresa; Hernández-Ruiz, Marta; Varela, Marta M.; Ferrera, Isabel; Gutiérrez Morán, Xosé Anxelu; Gasol, Josep M.

2015-01-01

The transformation of leucine incorporation rates to prokaryotic carbon production rates requires the use of either theoretical or empirically determined conversion factors. Empirical leucine-to-carbon conversion factors (eCFs) vary widely across environments, and little is known about their potential controlling factors. We conducted 10 surface seawater manipulation experiments across the world's oceans, where the growth of the natural prokaryotic assemblages was promoted by filtration (i.e., removal of grazers [F treatment]) or filtration combined with dilution (i.e., also relieving resource competition [FD treatment]). The impact of sunlight exposure was also evaluated in the FD treatments, and we did not find a significant effect on the eCFs. The eCFs varied from 0.09 to 1.47 kg C mol Leu−1 and were significantly lower in the FD than in the F samples. Also, changes in bacterial community composition during the incubations, as assessed by automated ribosomal intergenic spacer analysis (ARISA), were more pronounced in the FD than in the F treatments, compared to unmanipulated controls. Thus, we discourage the common procedure of diluting samples (in addition to filtration) for eCF determination. The eCFs in the filtered treatment were negatively correlated with the initial chlorophyll a concentration, picocyanobacterial abundance (mostly Prochlorococcus), and the percentage of heterotrophic prokaryotes with high nucleic acid content (%HNA). The latter two variables explained 80% of the eCF variability in the F treatment, supporting the view that both Prochlorococcus and HNA prokaryotes incorporate leucine in substantial amounts, although this results in relatively low carbon production rates in the oligotrophic ocean. PMID:26407885

A cross-site comparison of factors controlling streamwater carbon flux in western North American catchments (Invited)

NASA Astrophysics Data System (ADS)

Brooks, P. D.; Biederman, J. A.; Condon, K.; Chorover, J.; McIntosh, J. C.; Meixner, T.; Perdrial, J. N.

2013-12-01

Increasing variability in climate is expected to alter the amount and form of terrestrial carbon in stream water both directly, through changes in the magnitude and timing of discharge, and indirectly through changes in land cover following disturbance (e.g. drought, fire, or insect driven mortality). Predicting how these changes will impact individual stream-catchment ecosystems however, is hampered by a lack of concurrent observations on both dissolved and particulate carbon flux across a range of spatial, temporal, and discharge scales. Because carbon is strongly coupled to most biogeochemical reactions within both aquatic and terrestrial ecosystems, this represents a critical unknown in predicting the response of catchment-ecosystems to concurrent changes in climate and land cover. This presentation will address this issue using a meta-analysis of dissolved organic, dissolved inorganic, and particulate organic carbon fluxes from multiple locations, including undisturbed sites along a climate gradient from desert rivers to seasonally snow-covered, forested mountain catchments, and sites disturbed by both fire and extensive, insect driven mortality. Initial analyses suggest that dissolved (organic and inorganic) and particulate fluxes respond differently to various types of disturbance and depend on interactions between changes in size of mobile carbon pools and changes in hydrologic routing of carbon to streamwater. Anomalously large fluxes of both dissolved and particulate organic matter are associated with episodic changes in hydrologic routing (e.g. storm floods; snowmelt) that connect normally hydrologically isolated carbon pools (e.g. surficial hillslope soils) with surface water. These events are often of short duration as the supply of mobile carbon is exhausted in short term flushing response. In contrast, disturbances that increase the size of the mobile carbon pool (e.g. widespread vegetation mortality) result smaller proportional increases in

40 CFR 65.152 - Carbon adsorbers used as control devices.

Code of Federal Regulations, 2011 CFR

2011-07-01

... control device. If an owner or operator elects to replace a control device on a Group 1 process vent or... 40 Protection of Environment 15 2011-07-01 2011-07-01 false Carbon adsorbers used as control... PROGRAMS (CONTINUED) CONSOLIDATED FEDERAL AIR RULE Closed Vent Systems, Control Devices, and Routing to a...

Carbonate Mineral Formation on Mars: Clues from Stable Isotope Variation Seen in Cryogenic Laboratory Studies of Carbonate Salts

NASA Technical Reports Server (NTRS)

Socki, Richard; Niles, Paul B.; Sun, Tao; Fu, Qi; Romanek, Christopher S.; Gibson, Everett K.

2013-01-01

The geologic history of water on the planet Mars is intimately connected to the formation of carbonate minerals through atmospheric CO2 and its control of the climate history of Mars. Carbonate mineral formation under modern martian atmospheric conditions could be a critical factor in controlling the martian climate in a means similar to the rock weathering cycle on Earth. The combination of evidence for liquid water on the martian surface and cold surface conditions suggest fluid freezing could be very common on the surface of Mars. Cryogenic calcite forms readily when a rise in pH occurs as a result of carbon dioxide degassing quickly from freezing Ca-bicarbonate-rich water solutions. This is a process that has been observed in some terrestrial settings such as arctic permafrost cave deposits, lakebeds of the Dry Valleys of Antarctica, and in aufeis (river icings) from rivers of N.E. Alaska. We report here the results of a series of laboratory experiments that were conducted to simulate potential cryogenic carbonate formation on the planet Mars. These results indicate that carbonates grown under martian conditions (controlled atmospheric pressure and temperature) show enrichments from starting bicarbonate fluids in both carbon and oxygen isotopes beyond equilibrium values with average delta13C(DIC-CARB) values of 20.5%0 which exceed the expected equilibrium fractionation factor of [10(sup 3) ln alpha = 13%0] at 0 degC. Oxygen isotopes showed a smaller enrichment with delta18O(H2O-CARB) values of 35.5%0, slightly exceeding the equilibrium fractionation factor of [10(sup 3) ln alpha = 34%0 ] at 0degC. Large kinetic carbon isotope effects during carbonate precipitation could substantially affect the carbon isotope evolution of CO2 on Mars allowing for more efficient removal of 13C from the Noachian atmosphere enriched by atmospheric loss. This mechanism would be consistent with the observations of large carbon isotope variations in martian materials despite the

Identification of atmospheric organic sources using the carbon hollow tube-gas chromatography method and factor analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cobb, G.P.; Braman, R.S.; Gilbert, R.A.

Atmospheric organics were sampled and analyzed by using the carbon hollow tube-gas chromatography method. Chromatograms from spice mixtures, cigarettes, and ambient air were analyzed. Principal factor analysis of row order chromatographic data produces factors which are eigenchromatograms of the components in the samples. Component sources are identified from the eigenchromatograms in all experiments and the individual eigenchromatogram corresponding to a particular source is determined in most cases. Organic sources in ambient air and in cigaretts are identified with 87% certainty. Analysis of clove cigarettes allows the determination of the relative amount of clove in different cigarettes. A new nondestructive qualitymore » control method using the hollow tube-gas chromatography analysis is discussed.« less

A conceptual model of the controlling factors of soil organic carbon and nitrogen densities in a permafrost-affected region on the eastern Qinghai-Tibetan Plateau

NASA Astrophysics Data System (ADS)

Wu, Xiaodong; Fang, Hongbing; Zhao, Yonghua; Smoak, Joseph M.; Li, Wangping; Shi, Wei; Sheng, Yu; Zhao, Lin; Ding, Yongjian

2017-07-01

Many investigations of the preservation of soil organic carbon (SOC) in permafrost regions have examined roles of geomorphology, pedogenesis, vegetation cover, and permafrost within particular regions. However, it is difficult to disentangle the effects of multiple factors on the SOC in permafrost regions due to the heterogeneity in environmental conditions. Based on data from 73 soil study sites in permafrost regions of the eastern Qinghai-Tibetan Plateau, we developed a simple conceptual model, which relates SOC to topography, vegetation, and pedogenesis. We summarized the dominant factors and their controls on SOC using 31 measured soil physiochemical variables. Soil texture explains approximately 60% of the variations in the SOC stocks for the upper 0-2 m soil. Soil particle size closely correlates to soil moisture, which is an important determinant of SOC. Soil salinity and cations are important factors as well and can explain about 10% of the variations in SOC. The SOC and total nitrogen (TN) stocks for the 1-2 m depths have larger uncertainties than those of upper 1 m soil layer. The vegetation, pH, and bulk density mainly affects SOC and TN stocks for the upper 1 m soil layers, while the active layer thickness and soil particle size have greater influence on SOC and TN stocks for the 1-2 m soils. Our results suggest that the soil particle size is the most important controller of SOC pools, and the stocks of SOC and TN are strongly effected by soil development processes in the permafrost regions of the eastern Qinghai-Tibetan Plateau.

Boreal soil carbon dynamics under a changing climate: a model inversion approach

Treesearch

Zhaosheng Fan; Jason C. Neff; Jennifer W. Harden; Kimberly P. Wickland

2008-01-01

Several fundamental but important factors controlling the feedback of boreal organic carbon (OC) to climate change were examined using a mechanistic model of soil OC dynamics, including the combined effects of temperature and moisture on the decomposition of OC and the factors controlling carbon quality and decomposition with depth. To estimate decomposition rates and...

Quantification of carbon accumulation in eleven New England eelgrass meadows

EPA Science Inventory

As atmospheric and oceanic concentrations of carbon dioxide continue to increase, quantifying the carbon storage potential of seagrass meadows and improving the understanding of the factors controlling carbon sequestration in seagrass meadows is essential information for decision...

Effects of lanthanum carbonate and calcium carbonate on fibroblast growth factor 23 and hepcidin levels in chronic hemodialysis patients.

PubMed

Chang, Yu-Ming; Tsai, Shih-Ching; Shiao, Chih-Chung; Liou, Hung-Hsiang; Yang, Chuan-Lan; Tung, Nai-Yu; Hsu, Kua-Sui; Chen, I-Ling; Liu, Mei-Chyn; Kao, Jsun-Liang; Jhen, Rong-Na; Huang, Ya-Ting

2017-10-01

Phosphate binders have an impact on fibroblast growth factor 23 (FGF23); however, the effect of phosphate binders on serum hepcidin has not been explored. We conducted a 24-week multicenter randomized controlled trial to investigate the effects of lanthanum carbonate or calcium carbonate monotherapy on serum phosphate, FGF23, and hepcidin levels in chronic hemodialysis patients. Forty-six patients were recruited, and daily dietary phosphorus was controlled between 600-800 mg. Serum calcium, phosphate, albumin, alkaline phosphatase (ALP), FGF23, intact parathyroid hormone (iPTH), hepcidin, high-sensitivity CRP (hsCRP), 25(OH)D, 1,25(OH) 2 D, fetuin-A, and osteopontin were checked as scheduled. Twenty-five patients completed the study. Mean serum FGF23 level was significantly decreased after a 24-week treatment with lanthanum (8677.5 ± 7490.0 vs. 4692.8 ± 5348.3 pg/mL, p = 0.013, n = 13), but not with calcium (n = 12). The reduction of serum hepcidin in lanthanum group was positively correlated with the decrement of serum phosphate (r = 0.631, p = 0.021) and serum hsCRP (r = 0.670, p = 0.012) levels, respectively. Serum ALP, iPTH, vitamin D, fetuin-A, and osteopontin revealed no significant inter- or intragroup differences. In summary, a decrease in serum FGF23 levels and a trend of decline in hepcidin levels were observed only in lanthanum group.

Innate immune humoral factors, C1q and factor H, with differential pattern recognition properties, alter macrophage response to carbon nanotubes.

PubMed

Pondman, Kirsten M; Pednekar, Lina; Paudyal, Basudev; Tsolaki, Anthony G; Kouser, Lubna; Khan, Haseeb A; Shamji, Mohamed H; Ten Haken, Bennie; Stenbeck, Gudrun; Sim, Robert B; Kishore, Uday

2015-11-01

Interaction between the complement system and carbon nanotubes (CNTs) can modify their intended biomedical applications. Pristine and derivatised CNTs can activate complement primarily via the classical pathway which enhances uptake of CNTs and suppresses pro-inflammatory response by immune cells. Here, we report that the interaction of C1q, the classical pathway recognition molecule, with CNTs involves charge pattern and classical pathway activation that is partly inhibited by factor H, a complement regulator. C1q and its globular modules, but not factor H, enhanced uptake of CNTs by macrophages and modulated the pro-inflammatory immune response. Thus, soluble complement factors can interact differentially with CNTs and alter the immune response even without complement activation. Coating CNTs with recombinant C1q globular heads offers a novel way of controlling classical pathway activation in nanotherapeutics. Surprisingly, the globular heads also enhance clearance by phagocytes and down-regulate inflammation, suggesting unexpected complexity in receptor interaction. Carbon nanotubes (CNTs) maybe useful in the clinical setting as targeting drug carriers. However, it is also well known that they can interact and activate the complement system, which may have a negative impact on the applicability of CNTs. In this study, the authors functionalized multi-walled CNT (MWNT), and investigated the interaction with the complement pathway. These studies are important so as to gain further understanding of the underlying mechanism in preparation for future use of CNTs in the clinical setting. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Control of Effluent Gases from Solid Waste Processing Using Carbon Nanotubes

NASA Technical Reports Server (NTRS)

Fisher, John; Cinke, Martin; Wignarajab, Kanapathipillai

2005-01-01

One of the major problems associated with solid waste processing technologies is the release of effluent gases and contaminants that are in gaseous formed from the processes. A number of other gases, in particular NO(x), SO2, NH3, Hydrocarbons (e.g. CH4) do present hazards to the crew in space habitats. Reduction of mass, power, volume and resupply can be achieved by using catalyst impregnated carbon nanotubes as compared to other catalytic systems. The development and characterization of an innovative approach for the control and elimination of gaseous toxins using single walled carbon nanotubes (SWNTs) promise superior performance over conventional approaches. This is due to the ability to direct the selective uptake of gaseous species based on their controllable pore size, high adsorptive capacity and the effectiveness of carbon nanotubes as catalyst supports for gaseous conversion. For example, SWNTs have high adsorptive capacity for NO and the adsorbed NO can be decomposed to N2 and O2 . Experimental results showing the decomposition of NO on metal impregnated carbon nanotubes is presented. Equivalent System Mass (ESM) comparisons are made of the existing TCCS systems with the carbon nanotube technology for removing NO(x). The potential for methane decomposition using carbon nanotubes catalysts is also discussed.

Carbon Nanotubes in Biomedical Applications: Factors, Mechanisms, and Remedies of Toxicity.

PubMed

Alshehri, Reem; Ilyas, Asad Muhammad; Hasan, Anwarul; Arnaout, Adnan; Ahmed, Farid; Memic, Adnan

2016-09-22

Carbon nanotubes (CNTs) represent one of the most studied allotropes of carbon. The unique physicochemical properties of CNTs make them among prime candidates for numerous applications in biomedical fields including drug delivery, gene therapy, biosensors, and tissue engineering applications. However, toxicity of CNTs has been a major concern for their use in biomedical applications. In this review, we present an overview of carbon nanotubes in biomedical applications; we particularly focus on various factors and mechanisms affecting their toxicity. We have discussed various parameters including the size, length, agglomeration, and impurities of CNTs that may cause oxidative stress, which is often the main mechanism of CNTs' toxicity. Other toxic pathways are also examined, and possible ways to overcome these challenges have been discussed.

Polymer-free carbon nanotube thermoelectrics with improved charge carrier transport and power factor

DOE PAGES

Norton-Baker, Brenna; Ihly, Rachelle; Gould, Isaac E.; ...

2016-11-17

Here, semiconducting single-walled carbon nanotubes (s-SWCNTs) have recently attracted attention for their promise as active components in a variety of optical and electronic applications, including thermoelectricity generation. Here we demonstrate that removing the wrapping polymer from the highly enriched s-SWCNT network leads to substantial improvements in charge carrier transport and thermoelectric power factor. These improvements arise primarily from an increase in charge carrier mobility within the s-SWCNT networks because of removal of the insulating polymer and control of the level of nanotube bundling in the network, which enables higher thin-film conductivity for a given carrier density. Ultimately, these studies demonstratemore » that highly enriched s-SWCNT thin films, in the complete absence of any accompanying semiconducting polymer, can attain thermoelectric power factors in the range of approximately 400 μW m -1K -2, which is on par with that of some of the best single-component organic thermoelectrics demonstrated to date.« less

Redox-controlled carbon and phosphorus burial: A mechanism for enhanced organic carbon sequestration during the PETM

NASA Astrophysics Data System (ADS)

Komar, Nemanja; Zeebe, Richard E.

2017-12-01

Geological records reveal a major perturbation in carbon cycling during the Paleocene-Eocene Thermal Maximum (PETM, ∼56 Ma), marked by global warming of more than 5 °C and a prominent negative carbon isotope excursion of at least 2.5‰ within the marine realm. The entire event lasted about 200,000 yr and was associated with a massive release of light carbon into the ocean-atmosphere system over several thousands of years. Here we focus on the terminal stage of the PETM, during which the ocean-atmosphere system rapidly recovered from the carbon cycle perturbation. We employ a carbon-cycle box model to examine the feedbacks between surface ocean biological production, carbon, oxygen, phosphorus, and carbonate chemistry during massive CO2 release events, such as the PETM. The model results indicate that the redox-controlled carbon-phosphorus feedback is capable of producing enhanced organic carbon sequestration during large carbon emission events. The locale of carbon oxidation (ocean vs. atmosphere) does not affect the amount of carbon sequestered. However, even though the model produces trends consistent with oxygen, excess accumulation rates of organic carbon (∼1700 Pg C during the recovery stage), export production and δ13 C data, it fails to reproduce the magnitude of change of sediment carbonate content and the CCD over-deepening during the recovery stage. The CCD and sediment carbonate content overshoot during the recovery stage is muted by a predicted increase in CaCO3 rain. Nonetheless, there are indications that the CaCO3 export remained relatively constant during the PETM. If this was indeed true, then an initial pulse of 3,000 Pg C followed by an additional, slow leak of 2,500 Pg C could have triggered an accelerated nutrient supply to the surface ocean instigating enhanced organic carbon export, consequently increasing organic carbon sequestration, resulting in an accelerated restoration of ocean-atmosphere biogeochemistry during the termination

Key factors of low carbon development strategy for sustainable transport

NASA Astrophysics Data System (ADS)

Thaveewatanaseth, K.; Limjirakan, S.

2018-02-01

Cities become more vulnerable to climate change impacts causing by urbanization, economic growth, increasing of energy consumption and carbon dioxide (CO2) emissions. People who live in the cities have already been affected from the impacts in terms of socioeconomic and environmental aspects. Sustainable transport plays the key role in CO2 mitigation and contributes positive impacts on sustainable development for the cities. Several studies in megacities both in developed and developing countries support that mass transit system is an important transportation mode in CO2 mitigation and sustainable transport development. This paper aims to study key factors of low carbon development strategy for sustainable transport. The Bangkok Mass Rapid Transit System (MRT) located in Bangkok was the study area. Data collection was using semi-structured in-depth interview protocol with thirty respondents consisting of six groups i.e. governmental agencies, the MRT operators, consulting companies, international organizations, non-profit organizations, and experts. The research findings highlighted the major factors and supplemental elements composing of institution and technical capacity, institutional framework, policy setting and process, and plan of implementation that would support more effective strategic process for low carbon development strategy (LCDS) for sustainable transport. The study would highly recommend on readiness of institution and technical capacities, stakeholder mapping, high-level decision- makers participation, and a clear direction of the governmental policies that are strongly needed in achieving the sustainable transport.

Double resonance calibration of g factor standards: Carbon fibers as a high precision standard.

PubMed

Herb, Konstantin; Tschaggelar, Rene; Denninger, Gert; Jeschke, Gunnar

2018-04-01

The g factor of paramagnetic defects in commercial high performance carbon fibers was determined by a double resonance experiment based on the Overhauser shift due to hyperfine coupled protons. Our carbon fibers exhibit a single, narrow and perfectly Lorentzian shaped ESR line and a g factor slightly higher than g free with g=2.002644=g free ·(1+162ppm) with a relative uncertainty of 15ppm. This precisely known g factor and their inertness qualify them as a high precision g factor standard for general purposes. The double resonance experiment for calibration is applicable to other potential standards with a hyperfine interaction averaged by a process with very short correlation time. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

Altitude controls carbon dioxide in boreal lakes

NASA Astrophysics Data System (ADS)

Bhattacharya, Atreyee

2012-09-01

Organic matter present in lakes, derived either from land-based sources—such as plants, soil, and sediments—or from in situ processes—such as degrading detritus in the water—could be important in the global carbon cycle, and possibly a significant source of the atmospheric carbon dioxide (CO2) budget. The partial pressure of CO2 in surface waters (pCO2) drives the escape of CO2 to the atmosphere. Hence, scientists have long suspected that the relationship between pCO2 and the dissolved organic matter (DOC) in lake waters refects the relative contribution of the environment and in situ processes to the high-latitude carbon budget. Combining measurements of DOC and pCO2 from nearly 200 lakes across Quebec, Canada, with an additional 13 lake-based studies from temperate regions across the northern hemisphere, Lapierre and del Giorgio suggest that on a regional scale the A variety of lakes dominate the boreal landscape of Quebec, Canada. elevation of lakes is one of the strongest controls on the relationship between DOC and pCO2 in boreal lakes.

Sample dilution and bacterial community composition influence empirical leucine-to-carbon conversion factors in surface waters of the world's oceans.

PubMed

Teira, Eva; Hernando-Morales, Víctor; Cornejo-Castillo, Francisco M; Alonso-Sáez, Laura; Sarmento, Hugo; Valencia-Vila, Joaquín; Serrano Catalá, Teresa; Hernández-Ruiz, Marta; Varela, Marta M; Ferrera, Isabel; Gutiérrez Morán, Xosé Anxelu; Gasol, Josep M

2015-12-01

The transformation of leucine incorporation rates to prokaryotic carbon production rates requires the use of either theoretical or empirically determined conversion factors. Empirical leucine-to-carbon conversion factors (eCFs) vary widely across environments, and little is known about their potential controlling factors. We conducted 10 surface seawater manipulation experiments across the world's oceans, where the growth of the natural prokaryotic assemblages was promoted by filtration (i.e., removal of grazers [F treatment]) or filtration combined with dilution (i.e., also relieving resource competition [FD treatment]). The impact of sunlight exposure was also evaluated in the FD treatments, and we did not find a significant effect on the eCFs. The eCFs varied from 0.09 to 1.47 kg C mol Leu(-1) and were significantly lower in the FD than in the F samples. Also, changes in bacterial community composition during the incubations, as assessed by automated ribosomal intergenic spacer analysis (ARISA), were more pronounced in the FD than in the F treatments, compared to unmanipulated controls. Thus, we discourage the common procedure of diluting samples (in addition to filtration) for eCF determination. The eCFs in the filtered treatment were negatively correlated with the initial chlorophyll a concentration, picocyanobacterial abundance (mostly Prochlorococcus), and the percentage of heterotrophic prokaryotes with high nucleic acid content (%HNA). The latter two variables explained 80% of the eCF variability in the F treatment, supporting the view that both Prochlorococcus and HNA prokaryotes incorporate leucine in substantial amounts, although this results in relatively low carbon production rates in the oligotrophic ocean. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Total Belowground Carbon Allocation in a Fast-growing Eucalyptus Plantation Estimated Using a Carbon Balance Approach

Treesearch

Christian P. Giardina; Michael G. Ryan

2002-01-01

Trees allocate a large portion of gross primary production belowground for the production and maintenance of roots and mycorrhizae. The difficulty of directly measuring total belowground carbon allocation (TBCA) has limited our understanding of belowground carbon (C) cycling and the factors that control this important flux. We measured TBCA over 4 years using a...

A Study of the Critical Factors Controlling the Synthesis of Ceramic Matrix Composites from Preceramic Polymers.

DTIC Science & Technology

1988-04-15

physical properties of a polycarbosilane preceramic polymer as a function of temperature to derive synthesis methodology for SiC matrix composites , (2...investigate the role of interface modification in creating tough carbon fiber reinforced SiC matrix composites . RESEARCH PROGRESS Preceramic Polymer ...Classfication) A STUDY OF THE CRITICAL FACTORS CONTROLLING THE SYNTHESIS OF CERAMIC MATRIX COMPOSITES FROM PRECERAMIC POLYMERS 12. PERSONAL AUTHOR(S

The ultrasonic-enhanced factor of mass-transfer coefficient in the supercritical carbon dioxide extraction

NASA Astrophysics Data System (ADS)

Luo, Benyi; Lu, Yigang

2008-10-01

Based on several hypotheses about the process of supercritical carbon dioxide extraction, the onflow around the solute granule is figured out by the Navier-Stocks equation. In combination with the Higbie’s solute infiltration model, the link between the mass-transfer coefficient and the velocity of flow is found. The mass-transfer coefficient with the ultrasonical effect is compared with that without the ultrasonical effect, and then a new parameter named the ultrasonic-enhanced factor of mass-transfer coefficient is brought forward, which describes the mathematical model of the supercritical carbon dioxide extraction process enhanced by ultrasonic. The model gives out the relationships among the ultrasonical power, the ultrasonical frequency, the radius of solute granule and the ultrasonic-enhanced factor of mass-transfer coefficient. The results calculated by this model fit well with the experimental data, including the extraction of Coix Lacryma-jobi Seed Oil (CLSO) and Coix Lacryma-jobi Seed Ester (CLSE) from coix seeds and the extraction of Eicosapentaenoic Acid (EPA) and Docosahexaenoic Acid (DHA) from the alga by means of the ultrasonic-enhanced supercritical carbon dioxide extraction (USFE) and the supercritical carbon dioxide extraction (SFE) respectively. This proves the rationality of the ultrasonic-enhanced factor model. The model provides a theoretical basis for the application of ultrasonic-enhanced supercritical fluid extraction technique.

Spontaneous and controlled-diameter synthesis of single-walled and few-walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Inoue, Shuhei; Lojindarat, Supanat; Kawamoto, Takahiro; Matsumura, Yukihiko; Charinpanitkul, Tawatchai

2018-05-01

In this study, we explored the spontaneous and controlled-diameter growth of carbon nanotubes. We evaluated the effects of catalyst density, reduction time, and a number of catalyst coating on the substrate (for multi-walled carbon nanotubes) on the diameter of single-walled carbon nanotubes and the number of layers in few-walled carbon nanotubes. Increasing the catalyst density and reduction time increased the diameters of the carbon nanotubes, with the average diameter increasing from 1.05 nm to 1.86 nm for single-walled carbon nanotubes. Finally, we succeeded in synthesizing a significant double-walled carbon nanotube population of 24%.

Environmental factors controlling phytoplankton productivity and phenology in the Southern Ocean

NASA Astrophysics Data System (ADS)

Ardyna, M.; Claustre, H.; Sallee, J. B.; Gentili, B.; D'Ortenzio, F.

2016-02-01

The Southern Ocean (SO), highly sensitive to climate change, is currently experiencing a rapid warming and freshening. Such drastic hydrographical changes may significantly alter the SO's biological carbon pump (i.e., the efficiency of primary production and its transfers to higher trophic levels and/or sequestration to depth). However, before making any predictions, a better understanding of the biogeography and environmental factors controlling phytoplankton processes (i.e., productivity and phenology) in the Southern Ocean is clearly needed. We present here a bio-regionalization of the SO from satellite-derived observations, where a range of three orders of magnitude of productivity is observed. A clear latitudinal gradient in the bloom initiation was underpinned following the light regime, with some exception in well-mixed and sea-ice edge areas. Environmental factors controlling the phytoplankton phenology and productivity appear to be completely decoupled. Phytoplankton productivity in the SO is clearly associated to both shallow areas and front locations, where iron limitation seems to be less pronounced. These findings will give us a more comprehensive understanding in both space and time of the limiting factors of PP (i.e., nutrients, light-mixing regime…), which are of fundamental interest for identifying and explaining potential ongoing changes in SO's marine ecosystems.

Estimates of increased black carbon emissions from electrostatic precipitators during powdered activated carbon injection for mercury emissions control.

PubMed

Clack, Herek L

2012-07-03

The behavior of mercury sorbents within electrostatic precipitators (ESPs) is not well-understood, despite a decade or more of full-scale testing. Recent laboratory results suggest that powdered activated carbon exhibits somewhat different collection behavior than fly ash in an ESP and particulate filters located at the outlet of ESPs have shown evidence of powdered activated carbon penetration during full-scale tests of sorbent injection for mercury emissions control. The present analysis considers a range of assumed differential ESP collection efficiencies for powdered activated carbon as compared to fly ash. Estimated emission rates of submicrometer powdered activated carbon are compared to estimated emission rates of particulate carbon on submicrometer fly ash, each corresponding to its respective collection efficiency. To the extent that any emitted powdered activated carbon exhibits size and optical characteristics similar to black carbon, such emissions could effectively constitute an increase in black carbon emissions from coal-based stationary power generation. The results reveal that even for the low injection rates associated with chemically impregnated carbons, submicrometer particulate carbon emissions can easily double if the submicrometer fraction of the native fly ash has a low carbon content. Increasing sorbent injection rates, larger collection efficiency differentials as compared to fly ash, and decreasing sorbent particle size all lead to increases in the estimated submicrometer particulate carbon emissions.

Structure Controlled Long-Range Sequential Tunneling in Carbon-Based Molecular Junctions.

PubMed

Morteza Najarian, Amin; McCreery, Richard L

2017-04-25

Carbon-based molecular junctions consisting of aromatic oligomers between conducting sp 2 hybridized carbon electrodes exhibit structure-dependent current densities (J) when the molecular layer thickness (d) exceeds ∼5 nm. All four of the molecular structures examined exhibit an unusual, nonlinear ln J vs bias voltage (V) dependence which is not expected for conventional coherent tunneling or activated hopping mechanisms. All molecules exhibit a weak temperature dependence, with J increasing typically by a factor of 2 over the range of 200-440 K. Fluorene and anthraquinone show linear plots of ln J vs d with nearly identical J values for the range d = 3-10 nm, despite significant differences in their free-molecule orbital energy levels. The observed current densities for anthraquinone, fluorene, nitroazobenzene, and bis-thienyl benzene for d = 7-10 nm show no correlation with occupied (HOMO) or unoccupied (LUMO) molecular orbital energies, contrary to expectations for transport mechanisms based on the offset between orbital energies and the electrode Fermi level. UV-vis absorption spectroscopy of molecular layers bonded to carbon electrodes revealed internal energy levels of the chemisorbed films and also indicated limited delocalization in the film interior. The observed current densities correlate well with the observed UV-vis absorption maxima for the molecular layers, implying a transport mechanism determined by the HOMO-LUMO energy gap. We conclude that transport in carbon-based aromatic molecular junctions is consistent with multistep tunneling through a barrier defined by the HOMO-LUMO gap, and not by charge transport at the electrode interfaces. In effect, interfacial "injection" at the molecule/electrode interfaces is not rate limiting due to relatively strong electronic coupling, and transport is controlled by the "bulk" properties of the molecular layer interior.

40 CFR 52.1627 - Control strategy and regulations: Carbon monoxide.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 4 2014-07-01 2014-07-01 false Control strategy and regulations: Carbon monoxide. 52.1627 Section 52.1627 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) New Mexico § 52.1627 Control strategy and regulations:...

40 CFR 52.1627 - Control strategy and regulations: Carbon monoxide.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 4 2013-07-01 2013-07-01 false Control strategy and regulations: Carbon monoxide. 52.1627 Section 52.1627 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) New Mexico § 52.1627 Control strategy and regulations:...

40 CFR 52.1682 - Control strategy: Carbon monoxide.

Code of Federal Regulations, 2010 CFR

2010-07-01

... (CONTINUED) APPROVAL AND PROMULGATION OF IMPLEMENTATION PLANS (CONTINUED) New York § 52.1682 Control strategy... plan for the New York portion of the New York—Northern New Jersey—Long Island Carbon Monoxide... plan. The November 23, 1999, request to redesignate the New York portion of the New York—Northern New...

Automatic control of arterial carbon dioxide tension in mechanically ventilated patients.

PubMed

Fernando, Tyrone; Cade, John; Packer, John

2002-12-01

This paper presents a method of controlling the arterial carbon dioxide tension of patients receiving mechanical ventilation. Controlling of the CO2 tension is achieved by regulating the ventilator initiated breath frequency and also volume per breath.

Soil Organic Carbon Loss: An Overlooked Factor in the Carbon Sequestration Potential of Enhanced Mineral Weathering

NASA Astrophysics Data System (ADS)

Dietzen, Christiana; Harrison, Robert

2016-04-01

Weathering of silicate minerals regulates the global carbon cycle on geologic timescales. Several authors have proposed that applying finely ground silicate minerals to soils, where organic acids would enhance the rate of weathering, could increase carbon uptake and mitigate anthropogenic CO2 emissions. Silicate minerals such as olivine could replace lime, which is commonly used to remediate soil acidification, thereby sequestering CO2 while achieving the same increase in soil pH. However, the effect of adding this material on soil organic matter, the largest terrestrial pool of carbon, has yet to be considered. Microbial biomass and respiration have been observed to increase with decreasing acidity, but it is unclear how long the effect lasts. If the addition of silicate minerals promotes the loss of soil organic carbon through decomposition, it could significantly reduce the efficiency of this process or even create a net carbon source. However, it is possible that this initial flush of microbial activity may be compensated for by additional organic matter inputs to soil pools due to increases in plant productivity under less acidic conditions. This study aimed to examine the effects of olivine amendments on soil CO2 flux. A liming treatment representative of typical agricultural practices was also included for comparison. Samples from two highly acidic soils were split into groups amended with olivine or lime and a control group. These samples were incubated at 22°C and constant soil moisture in jars with airtight septa lids. Gas samples were extracted periodically over the course of 2 months and change in headspace CO2 concentration was determined. The effects of enhanced mineral weathering on soil organic matter have yet to be addressed by those promoting this method of carbon sequestration. This project provides the first data on the potential effects of enhanced mineral weathering in the soil environment on soil organic carbon pools.

Engineered carbon foam for temperature control applications

NASA Astrophysics Data System (ADS)

Almajali, Mohammad Rajab

pressure within the foam matrix were investigated. These factors lowered the heat transfer rate considerably and the melting area was reduced by more than 23%. Two samples, coated and uncoated carbon foam, were infiltrated with PCM and subjected to a uniform heat load test in a vacuum. The coated foam showed excellent performance compared to the uncoated foam. (iii) Finally, the new engineered carbon foam was used as a heat sink and heat exchanger in a thermoelectric cooler for a cooling vest application. Using carbon foam as the core material for this application, the effective transfer of heat was significantly increased while reducing the size and weight of the heat exchanger.

An evaluation of the carbon balance technique for estimating emission factors and fuel consumption in forest fires

Treesearch

Nelson, Jr. Ralph M.

1982-01-01

Eighteen experimental fires were used to compare measured and calculated values for emission factors and fuel consumption to evaluate the carbon balance technique. The technique is based on a model for the emission factor of carbon dioxide, corrected for the production of other emissions, and which requires measurements of effluent concentrations and air volume in the...

Weathering controls on mechanisms of carbon storage in grassland soils

USGS Publications Warehouse

Masiello, C.A.; Chadwick, O.A.; Southon, J.; Torn, M.S.; Harden, J.W.

2004-01-01

On a sequence of soils developed under similar vegetation, temperature, and precipitation conditions, but with variations in mineralogical properties, we use organic carbon and 14C inventories to examine mineral protection of soil organic carbon. In these soils, 14C data indicate that the creation of slow-cycling carbon can be modeled as occurring through reaction of organic ligands with Al3+ and Fe3+ cations in the upper horizons, followed by sorption to amorphous inorganic Al compounds at depth. Only one of these processes, the chelation Al3+ and Fe3+ by organic ligands, is linked to large carbon stocks. Organic ligands stabilized by this process traverse the soil column as dissolved organic carbon (both from surface horizons and root exudates). At our moist grassland site, this chelation and transport process is very strongly correlated with the storage and long-term stabilization of soil organic carbon. Our 14C results show that the mechanisms of organic carbon transport and storage at this site follow a classic model previously believed to only be significant in a single soil order (Spodosols), and closely related to the presence of forests. The presence of this process in the grassland Alfisol, Inceptisol, and Mollisol soils of this chronosequence suggests that this process is a more significant control on organic carbon storage than previously thought. Copyright 2004 by the American Geophysical Union.

pH and Organic Carbon Dose Rates Control Microbially Driven Bioremediation Efficacy in Alkaline Bauxite Residue.

PubMed

Santini, Talitha C; Malcolm, Laura I; Tyson, Gene W; Warren, Lesley A

2016-10-18

Bioremediation of alkaline tailings, based on fermentative microbial metabolisms, is a novel strategy for achieving rapid pH neutralization and thus improving environmental outcomes associated with mining and refining activities. Laboratory-scale bioreactors containing bauxite residue (an alkaline, saline tailings material generated as a byproduct of alumina refining), to which a diverse microbial inoculum was added, were used in this study to identify key factors (pH, salinity, organic carbon supply) controlling the rates and extent of microbially driven pH neutralization (bioremediation) in alkaline tailings. Initial tailings pH and organic carbon dose rates both significantly affected bioremediation extent and efficiency with lower minimum pHs and higher extents of pH neutralization occurring under low initial pH or high organic carbon conditions. Rates of pH neutralization (up to 0.13 mM H + produced per day with pH decreasing from 9.5 to ≤6.5 in three days) were significantly higher in low initial pH treatments. Representatives of the Bacillaceae and Enterobacteriaceae, which contain many known facultative anaerobes and fermenters, were identified as key contributors to 2,3-butanediol and/or mixed acid fermentation as the major mechanism(s) of pH neutralization. Initial pH and salinity significantly influenced microbial community successional trajectories, and microbial community structure was significantly related to markers of fermentation activity. This study provides the first experimental demonstration of bioremediation in bauxite residue, identifying pH and organic carbon dose rates as key controls on bioremediation efficacy, and will enable future development of bioreactor technologies at full field scale.

Decoupled carbonate chemistry controls on the incorporation of boron into Orbulina universa

NASA Astrophysics Data System (ADS)

Howes, Ella L.; Kaczmarek, Karina; Raitzsch, Markus; Mewes, Antje; Bijma, Nienke; Horn, Ingo; Misra, Sambuddha; Gattuso, Jean-Pierre; Bijma, Jelle

2017-01-01

In order to fully constrain paleo-carbonate systems, proxies for two out of seven parameters, plus temperature and salinity, are required. The boron isotopic composition (δ11B) of planktonic foraminifera shells is a powerful tool for reconstructing changes in past surface ocean pH. As B(OH)4- is substituted into the biogenic calcite lattice in place of CO32-, and both borate and carbonate ions are more abundant at higher pH, it was suggested early on that B / Ca ratios in biogenic calcite may serve as a proxy for [CO32-]. Although several recent studies have shown that a direct connection of B / Ca to carbonate system parameters may be masked by other environmental factors in the field, there is ample evidence for a mechanistic relationship between B / Ca and carbonate system parameters. Here, we focus on investigating the primary relationship to develop a mechanistic understanding of boron uptake. Differentiating between the effects of pH and [CO32-] is problematic, as they co-vary closely in natural systems, so the major control on boron incorporation remains unclear. To deconvolve the effects of pH and [CO32-] and to investigate their impact on the B / Ca ratio and δ11B, we conducted culture experiments with the planktonic foraminifer Orbulina universa in manipulated culture media: constant pH (8.05), but changing [CO32-] (238, 286 and 534 µmol kg-1 CO32-) and at constant [CO32-] (276 ± 19.5 µmol kg-1) and varying pH (7.7, 7.9 and 8.05). Measurements of the isotopic composition of boron and the B / Ca ratio were performed simultaneously using a femtosecond laser ablation system coupled to a MC-ICP-MS (multiple-collector inductively coupled plasma mass spectrometer). Our results show that, as expected, δ11B is controlled by pH but it is also modulated by [CO32-]. On the other hand, the B / Ca ratio is driven by [HCO3-], independently of pH. This suggests that B / Ca ratios in foraminiferal calcite can possibly be used as a second, independent, proxy for

Controls of Carbon Exchange in a Boreal Minerogenic Mire

NASA Astrophysics Data System (ADS)

Nilsson, M.; Sagerfors, J.; Buffam, I.; Eriksson, T.; Grelle, A.; Klemedtsson, L.; Weslien, P.; Laudon, H.; Lindroth, A.

2008-12-01

Based on theories on both mire development and their response to environmental change, the current role of mires as a net carbon sink has been questioned. A rigorous evaluation of the contemporary net C-exchange in mires requires direct measurements of all relevant fluxes. We use data on carbon exchange from a boreal minerogenic oligotrophic mire (Degerö Stormyr, 64°11' N, 19°33E) to derive a contemporary carbon budget and to analyze the main controls on the C exchange. Data on the following fluxes were collected: land-atmosphere CO2 (continuous Eddy Covariance measurements, 7 years) and CH4 (static chambers during the snow free period, 4 years) exchange; DOC in precipitation; loss of TOC, CO2 and CH4 through water runoff, 4 years (continuous discharge measurement and regular C-content measurements). The annual land atmosphere exchange of CO2 (NEE) was fairly constant between years and varied between -48 - -61 gCm-2yr-1 during six out of the seven years, despite a large variation in weather combinations, the average being -53 ± 5 gCm-2yr-1. Of the net fixation of atmospheric CO2-C during the net uptake period, i.e. the growing season, approximately a third was lost during the net source period, i.e. the winter period. During the four years with measurements of methane and runoff C-export another third of the growing season uptake was lost from the mire ecosystem as methane and runoff C. While the balance between the length of the NEE uptake and the NEE loss period are most important for the annual net ecosystem carbon balance (NECB) it is central to understand the controls of the spring-summer, and the summer-autumn transitions. The onset of the net C uptake period was controlled by the interaction between the water content and the temperature of the peat moss surface. We interpret this as mainly being a control of the CO2 photosynthesis uptake by the Sphagnum mosses. The transition from being a net C sink to being a net C source is in contrast only controlled

Controlling factors of evaporation and CO2 flux over an open water lake in southeastern margin of Tibetan Plateau

NASA Astrophysics Data System (ADS)

Du, Q.; Liu, H.; Liu, Y.; Wang, L.; Xu, L.

2017-12-01

Erhai lake is located in the southeastern margin of Tibetan Plateau. Based on the 4 years measurement over Erhai lake with eddy covariance technique (EC) from 2012 to 2015, the diurnal and seasonal variations of latent and sensible heat and CO2 fluxes, and their controlling factors over different time scales were analyzed. The diurnal average LE ranged from 31 to 171 Wm-2, while Hs ranged from -31 to 21 Wm-2. Bowen ratio was larger during January and May and smaller during June and October. The lake continued storing heat during January and June, and releasing heat since July. The diurnal average CO2 fluxes during nighttime were higher than the daytime, and carbon uptake was almost observed during the midday time of the day for the whole study period. The annual carbon budget fluctuated from 117.5 to 161.7 g C m-2 a-1, while annual total evaporation (ET) from 1120.8 to 1228.5 mm for the four-years period. The Erhai Lake behaved as a net carbon source over the whole period but carbon uptake was observed during the middle time of each year. The difference between water surface and air temperature (DeltaT) and the product of DeltaT and wind speed were the main controlling factors for Hs from halfhourly to monthly scale. There was significant relationship between wind speed, the product of wind speed and vapor pressure deficit (VPD) and LE on halfhourly and daily scales. The total cloud amount and net radiation (Rn) had a large effect on monthly variation of LE. Photosynthetic active radiation (PAR) and wind speed was mainly responsible for the variation of halfhourly and daily CO2 fluxes, respectively. The total cloud amount was the most important factors controlling for annual total ET. The annual rainfall, water surface temperature was observed to be negatively related with annual CO2 fluxes.

Chemical and stable carbon isotopic composition of PM2.5 from on-road vehicle emissions in the PRD region and implication for vehicle emission control policy

NASA Astrophysics Data System (ADS)

Dai, S.; Bi, X.; Chan, L. Y.; He, J.; Wang, B.; Wang, X.; Sheng, G.; Fu, J.

2014-11-01

Vehicle emission is a major source of urban air pollution. In recent decade, the Chinese government has introduced a range of policies to reduce the vehicle emission. In order to understand the chemical characteristics of PM2.5 from on-road vehicle emission in the Pearl River Delta (PRD) region and to evaluate the effectiveness of control policies on vehicles emission, the emission factors of PM2.5 mass, elemental carbon (EC), organic carbon (OC), water-soluble organic carbon (WSOC), water-soluble inorganic ions (WSII), metal elements, organic compounds and stable carbon isotopic composition were measured in the Zhujiang Tunnel of Guangzhou, the PRD region of China in 2013. Emission factors of PM2.5 mass, OC, EC, and WSOC were 92.4, 16.7, 16.4, and 1.31 mg vehicle-1 km-1 respectively. Emission factors of WSII were 0.016 (F-) ~4.17 (Cl-) mg vehicle-1 km-1, totally contributing about 9.8% to the PM2.5 emissions. The sum of 27 measured metal elements accounted for 15.2% of the PM2.5 emissions. Fe was the most abundant metal element, with an emission factor of 3.91 mg vehicle-1 km-1. Emission factors of organic compounds including n-alkanes, PAHs, hopanes, and steranes were 91.9, 5.02, 32.0 and 7.59 μg vehicle-1 km-1, respectively. Stable carbon isotopic composition δ13C value was measured and it was -25.0‰ on average. An isotopic fractionation of 3.2‰ was found during fuel combustion. Compared with a previous study in Zhujiang Tunnel in year 2004, emission factors of PM2.5 mass, EC, OC, WSII except Cl-, and organic compounds decreased by 16.0-93.4%, which could be attributed to emission control policy from 2004 to 2013. However, emission factors of most of the metal elements increased significantly, which could be partially attributed to the changes in motor oil additives and vehicle condition. There are no mandatory national standards to limit metal content from vehicle emission, which should be a concern of the government. A snapshot of the 2013 characteristic

Chemical and stable carbon isotopic composition of PM2.5 from on-road vehicle emissions in the PRD region and implications for vehicle emission control policy

NASA Astrophysics Data System (ADS)

Dai, S.; Bi, X.; Chan, L. Y.; He, J.; Wang, B.; Wang, X.; Peng, P.; Sheng, G.; Fu, J.

2015-03-01

Vehicle emissions are a major source of urban air pollution. In recent decade, the Chinese government has introduced a range of policies to reduce vehicle emissions. In order to understand the chemical characteristics of PM2.5 from on-road vehicle emissions in the Pearl River Delta (PRD) region and to evaluate the effectiveness of control policies on vehicle emissions, the emission factors of PM2.5 mass, elemental carbon (EC), organic carbon (OC), water-soluble organic carbon (WSOC), water-soluble inorganic ions (WSII), metal elements, organic compounds and stable carbon isotopic composition were measured in the Zhujiang tunnel of Guangzhou, in the PRD region of China in 2013. Emission factors of PM2.5 mass, OC, EC and WSOC were 92.4, 16.7, 16.4 and 1.31 mg vehicle-1 km-1 respectively. Emission factors of WSII were 0.016 (F-) ~ 4.17 (Cl-) mg vehicle-1 km-1, contributing about 9.8% to the PM2.5 emissions. The sum of 27 measured metal elements accounted for 15.2% of PM2.5 emissions. Fe was the most abundant metal element, with an emission factor of 3.91 mg vehicle-1 km-1. Emission factors of organic compounds including n-alkanes, polycyclic aromatic hydrocarbons, hopanes and steranes were 91.9, 5.02, 32.0 and 7.59 μg vehicle-1 km-1, respectively. Stable carbon isotopic composition δ13C value was -25.0‰ on average. An isotopic fractionation of 3.2‰ was found during fuel combustion. Compared to a previous study in Zhujiang tunnel in 2004, emission factors of PM2.5mass, EC, OC, WSII except Cl- and organic compounds decreased by 16.0 ~ 93.4%, which could be attributed to emission control policy from 2004 to 2013. However, emission factors of most of the metal elements increased significantly, which could be partially attributed to the changes in motor oil additives and vehicle conditions. There are no mandatory national standards to limit metal content from vehicle emissions, which should be a concern of the government. A snapshot of the 2013 characteristic

Nitrogen attenuation of terrestrial carbon cycle response to global environmental factors

USGS Publications Warehouse

Jain, A.A.; Yang, Xiaojuan; Kheshgi, H.; McGuire, A. David; Post, W.; Kicklighter, David W.

2009-01-01

Nitrogen cycle dynamics have the capacity to attenuate the magnitude of global terrestrial carbon sinks and sources driven by CO2 fertilization and changes in climate. In this study, two versions of the terrestrial carbon and nitrogen cycle components of the Integrated Science Assessment Model (ISAM) are used to evaluate how variation in nitrogen availability influences terrestrial carbon sinks and sources in response to changes over the 20th century in global environmental factors including atmospheric CO2 concentration, nitrogen inputs, temperature, precipitation and land use. The two versions of ISAM vary in their treatment of nitrogen availability: ISAM-NC has a terrestrial carbon cycle model coupled to a fully dynamic nitrogen cycle while ISAM-C has an identical carbon cycle model but nitrogen availability is always in sufficient supply. Overall, the two versions of the model estimate approximately the same amount of global mean carbon uptake over the 20th century. However, comparisons of results of ISAM-NC relative to ISAM-C reveal that nitrogen dynamics: (1) reduced the 1990s carbon sink associated with increasing atmospheric CO2 by 0.53 PgC yr−1 (1 Pg = 1015g), (2) reduced the 1990s carbon source associated with changes in temperature and precipitation of 0.34 PgC yr−1 in the 1990s, (3) an enhanced sink associated with nitrogen inputs by 0.26 PgC yr−1, and (4) enhanced the 1990s carbon source associated with changes in land use by 0.08 PgC yr−1 in the 1990s. These effects of nitrogen limitation influenced the spatial distribution of the estimated exchange of CO2 with greater sink activity in high latitudes associated with climate effects and a smaller sink of CO2 in the southeastern United States caused by N limitation associated with both CO2 fertilization and forest regrowth. These results indicate that the dynamics of nitrogen availability are important to consider in assessing the spatial distribution and temporal dynamics of terrestrial carbon

[Adsorbent effect of activated carbon on small molecular uremic toxin and its influence factors].

PubMed

Yang, Bo; Jiang, Yun-sheng; Li, Jun

2003-06-01

To analyze the adsorbent effect of activated carbon on uremic toxin and its influence factors. Uremic toxins (urea, creatinine and uric acid) were dissolved in the distilled water to obtain uremic toxic solution. Activated carbon was added to the solution, and the concentrations of uremic toxins were measured at different time spots. To determine the influence factors, some possible related materials, such as bile, amino acid, Ringer's, solution of glucose, HCl or NaOH respectively were added simultaneously. The concentrations of toxins in uremic toxic solution decreased 5 min after adding the activated carbon. The concentration of urea was the lowest at 30 min, but it increased after 50 min; while the concentrations of creatinine and uric acid reached the lowest level from 10 to 30 min after adding the activated carbon, and maintained at the same level after that. The bile, amino acid, electrolyte, glucose and pH value did not influence the adsorption of uric acid significantly, but they influenced the adsorption of urea and creatinine. Bile and amino acid influenced the concentration of urea remarkably, following glucose, NaOH and HCl. The effect of pH 2.0 solution on the creatinine concentration was the most significant, following glucose. Activated carbon has adsorptive effect on uremic toxins, but its adsorptive effect decreases as time goes on. Bile, glucose, amino acid, NaOH and HCl can affect the adsorptive effect of activated carbon on uremic toxins to some extent.

Hydrologic control of carbon cycling and aged carbon discharge in the Congo River basin

NASA Astrophysics Data System (ADS)

Schefuß, Enno; Eglinton, Timothy I.; Spencer-Jones, Charlotte L.; Rullkötter, Jürgen; de Pol-Holz, Ricardo; Talbot, Helen M.; Grootes, Pieter M.; Schneider, Ralph R.

2016-09-01

The age of organic material discharged by rivers provides information about its sources and carbon cycling processes within watersheds. Although elevated ages in fluvially transported organic matter are usually explained by erosion of soils and sedimentary deposits, it is commonly assumed that mainly young organic material is discharged from flat tropical watersheds due to their extensive plant cover and rapid carbon turnover. Here we present compound-specific radiocarbon data of terrigenous organic fractions from a sedimentary archive offshore the Congo River, in conjunction with molecular markers for methane-producing land cover reflecting wetland extent. We find that the Congo River has been discharging aged organic matter for several thousand years, with apparently increasing ages from the mid- to the Late Holocene. This suggests that aged organic matter in modern samples is concealed by radiocarbon from atmospheric nuclear weapons testing. By comparison to indicators for past rainfall changes we detect a systematic control of organic matter sequestration and release by continental hydrology, mediating temporary carbon storage in wetlands. As aridification also leads to exposure and rapid remineralization of large amounts of previously stored labile organic matter, we infer that this process may cause a profound direct climate feedback that is at present underestimated in carbon cycle assessments.

40 CFR 52.1627 - Control strategy and regulations: Carbon monoxide.

Code of Federal Regulations, 2012 CFR

2012-07-01

... § 52.1627 Control strategy and regulations: Carbon monoxide. (a) Part D Approval. The Albuquerque... Section 172 of the Clean Air Act, and is therefore approved. (b) Approval—The Albuquerque/Bernalillo...

40 CFR 52.1627 - Control strategy and regulations: Carbon monoxide.

Code of Federal Regulations, 2011 CFR

2011-07-01

... § 52.1627 Control strategy and regulations: Carbon monoxide. (a) Part D Approval. The Albuquerque... Section 172 of the Clean Air Act, and is therefore approved. (b) Approval—The Albuquerque/Bernalillo...

The new urban politics as a politics of carbon control.

PubMed

Jonas, Andrew E G; Gibbs, David; While, Aidan

2011-01-01

The new urban politics (NUP) literature has helped to draw attention to a new generation of entrepreneurial urban regimes involved in the competition to attract investment to cities. Interurban competition often had negative environmental consequences for the urban living place. Yet knowledge of the environment was not very central to understanding the NUP. Entrepreneurial urban regimes today are struggling to deal with climate change and reductions in greenhouse gas emissions. Carbon reduction strategies could have profound implications for interurban competition and the politics of urban development. This paper explores the rise of a distinctive low-carbon urban polity—carbon control—and examines its potential ramifications for a new environmental politics of urban development (NEPUD). The NEPUD signals the growing centrality of carbon control in discourses, strategies and struggles around urban development. Using examples from cities in the US and Europe, the paper examines how these new environmental policy considerations are being mainstreamed in urban development politics. Alongside competitiveness, the management of carbon emissions represents a new yet at the same time contestable mode of calculation in urban governance.

Carbonic anhydrases, EPF2 and a novel protease mediate CO2 control of stomatal development.

PubMed

Engineer, Cawas B; Ghassemian, Majid; Anderson, Jeffrey C; Peck, Scott C; Hu, Honghong; Schroeder, Julian I

2014-09-11

Environmental stimuli, including elevated carbon dioxide levels, regulate stomatal development; however, the key mechanisms mediating the perception and relay of the CO2 signal to the stomatal development machinery remain elusive. To adapt CO2 intake to water loss, plants regulate the development of stomatal gas exchange pores in the aerial epidermis. A diverse range of plant species show a decrease in stomatal density in response to the continuing rise in atmospheric CO2 (ref. 4). To date, one mutant that exhibits deregulation of this CO2-controlled stomatal development response, hic (which is defective in cell-wall wax biosynthesis, ref. 5), has been identified. Here we show that recently isolated Arabidopsis thaliana β-carbonic anhydrase double mutants (ca1 ca4) exhibit an inversion in their response to elevated CO2, showing increased stomatal development at elevated CO2 levels. We characterized the mechanisms mediating this response and identified an extracellular signalling pathway involved in the regulation of CO2-controlled stomatal development by carbonic anhydrases. RNA-seq analyses of transcripts show that the extracellular pro-peptide-encoding gene EPIDERMAL PATTERNING FACTOR 2 (EPF2), but not EPF1 (ref. 9), is induced in wild-type leaves but not in ca1 ca4 mutant leaves at elevated CO2 levels. Moreover, EPF2 is essential for CO2 control of stomatal development. Using cell-wall proteomic analyses and CO2-dependent transcriptomic analyses, we identified a novel CO2-induced extracellular protease, CRSP (CO2 RESPONSE SECRETED PROTEASE), as a mediator of CO2-controlled stomatal development. Our results identify mechanisms and genes that function in the repression of stomatal development in leaves during atmospheric CO2 elevation, including the carbonic-anhydrase-encoding genes CA1 and CA4 and the secreted protease CRSP, which cleaves the pro-peptide EPF2, in turn repressing stomatal development. Elucidation of these mechanisms advances the understanding

Carbonic anhydrases, EPF2 and a novel protease mediate CO2 control of stomatal development

PubMed Central

Engineer, Cawas B.; Ghassemian, Majid; Anderson, Jeffrey C.; Peck, Scott C.; Hu, Honghong; Schroeder, Julian I.

2014-01-01

Environmental stimuli, including elevated carbon dioxide levels, regulate stomatal development1–3; however, the key mechanisms mediating the perception and relay of the CO2 signal to the stomatal development machinery remain elusive. To adapt CO2 intake to water loss, plants regulate the development of stomatal gas exchange pores in the aerial epidermis. A diverse range of plant species show a decrease in stomatal density in response to the continuing rise in atmospheric CO2 (ref. 4). To date, one mutant that exhibits deregulation of this CO2-controlled stomatal development response, hic (which is defective in cell-wall wax biosynthesis, ref. 5), has been identified. Here we show that recently isolated Arabidopsis thaliana β-carbonic anhydrase double mutants (ca1 ca4)6 exhibit aninversion in their response to elevated CO2, showing increased stomatal development at elevated CO2 levels. We characterized the mechanisms mediating this response and identified an extracellular signalling pathway involved in the regulation of CO2-controlled stomatal development by carbonic anhydrases. RNA-seq analyses of transcripts show that the extracellular pro-peptide-encoding gene EPIDERMAL PATTERNING FACTOR 2 (EPF2)7,8, but not EPF1 (ref. 9), is induced in wild-type leaves but not inca1 ca4 mutant leaves at elevated CO2 levels. Moreover, EPF2 is essential for CO2 control of stomatal development. Using cell-wall proteomic analyses and CO2-dependent transcriptomic analyses, we identified a novel CO2-induced extracellular protease, CRSP (CO2 RESPONSE SECRETED PROTEASE), as a mediator of CO2-controlled stomatal development. Our results identify mechanisms and genes that function in the repression of stomatal development in leaves during atmospheric CO2 elevation, including the carbonic-anhydrase-encoding genes CA1 and CA4 and the secreted protease CRSP, which cleaves the pro-peptide EPF2, in turn repressing stomatal development. Elucidation of these mechanisms advances the

Emission factors of black carbon and co-pollutants from diesel vehicles in Mexico City

NASA Astrophysics Data System (ADS)

Zavala, Miguel; Molina, Luisa T.; Yacovitch, Tara I.; Fortner, Edward C.; Roscioli, Joseph R.; Floerchinger, Cody; Herndon, Scott C.; Kolb, Charles E.; Knighton, Walter B.; Paramo, Victor Hugo; Zirath, Sergio; Mejía, José Antonio; Jazcilevich, Aron

2017-12-01

Diesel-powered vehicles are intensively used in urban areas for transporting goods and people but can substantially contribute to high emissions of black carbon (BC), organic carbon (OC), and other gaseous pollutants. Strategies aimed at controlling mobile emissions sources thus have the potential to improve air quality and help mitigate the impacts of air pollutants on climate, ecosystems, and human health. However, in developing countries there are limited data on the BC and OC emission characteristics of diesel-powered vehicles, and thus there are large uncertainties in the estimation of the emission contributions from these sources. We measured BC, OC, and other inorganic components of fine particulate matter (PM), as well as carbon monoxide (CO), nitrogen oxides (NOx), sulfur dioxide (SO2), ethane, acetylene, benzene, toluene, and C2-benzenes under real-world driving conditions for 20 diesel-powered vehicles encompassing multiple emission level technologies in Mexico City with the chasing technique using the Aerodyne mobile laboratory. Average BC emission factors ranged from 0.41-2.48 g kg-1 of fuel depending on vehicle type. The vehicles were also simultaneously measured using the cross-road remote sensing technique to obtain the emission factors of nitrogen oxide (NO), CO, total hydrocarbons, and fine PM, thus allowing for the intercomparison of the results from the two techniques. There is overall good agreement between the two techniques and both can identify high and low emitters, but substantial differences were found in some of the vehicles, probably due to the ability of the chasing technique to capture a larger diversity of driving conditions in comparison to the remote sensing technique. A comparison of the results with the US EPA MOVES2014b model showed that the model underestimates CO, OC, and selected VOC species, whereas there is better agreement for NOx and BC. Larger OC / BC ratios were found in comparison to ratios measured in California using

Crystal shape controlled H2 storage rate in nanoporous carbon composite with ultra-fine Pt nanoparticle

NASA Astrophysics Data System (ADS)

Chen, Tsan-Yao; Zhang, Yanhui; Hsu, Liang-Ching; Hu, Alice; Zhuang, Yu; Fan, Chia-Ming; Wang, Cheng-Yu; Chung, Tsui-Yun; Tsao, Cheng-Si; Chuang, Haw-Yeu

2017-02-01

This study demonstrates that the hydrogen storage rate (HSR) of nanoporous carbon supported platinum nanocatalysts (NC) is determined by their heterojunction and geometric configurations. The present NC is synthesized in an average particle size of ~1.5 nm by incipient wetness impregnation of Pt4+ at carbon support followed by annealing in H2 ambient at 102-105 °C. Among the steps in hydrogen storage, decomposition of H2 molecule into 2 H atoms on Pt NC surface is the deciding factor in HSR that is controlled by the thickness of Pt NC. For the best condition, HSR of Pt NC in 1~2 atomic layers thick (4.7 μg/g min) is 2.6 times faster than that (1.3 μg/g min) of Pt NC with higher than 3 atomic layers thick.

One-Carbon Metabolic Factors and Risk of Renal Cell Cancer: A Meta-Analysis.

PubMed

Mao, Bijing; Li, Yafei; Zhang, Zhimin; Chen, Chuan; Chen, Yuanyuan; Ding, Chenchen; Lei, Lin; Li, Jian; Jiang, Mei; Wang, Dong; Wang, Ge

2015-01-01

Nutrients related to one-carbon metabolism were previously shown to be significantly associated with the risk of cancer. The aim of this meta-analysis was to evaluate potential relationships between one-carbon metabolic factors and renal cell cancer (RCC) risk. PubMed, EMBASE, and Cochrane Library databases were searched through March 2015 for observational studies of quantitative RCC risk estimates in relation to one-carbon metabolic factors. The relative risks (RRs) with 95% confidence intervals (CIs) measured the relationship between one-carbon metabolic factors and RCC risk using a random-effects model. Of the 463 citations and abstracts identified by database search, seven cohorts from five observational studies reported data on 133,995 individuals, and included 2,441 RCC cases. Comparing the highest with the lowest category, the pooled RRs of RCC were 0.72 (95%CI: 0.52-1.00; P = 0.048) for vitamin B12. In addition, an increase in folic acid supplementation of 100 μg/day was associated with a 3% lower risk of RCC (RR, 0.97; 95%CI: 0.93-1.00; P = 0.048). Similarly, an increase of 5 nmol/L of vitamin B2 was associated with a reduced risk of RCC 0.94 (95%CI: 0.89-1.00; P = 0.045). Sensitivity analyses suggested that a higher serum vitamin B6 might contribute to a reduced risk of RCC (RR, 0.83; 95%CI: 0.77-0.89; P < 0.001). Higher levels of serum vitamin B2, B6, B12, and folic acid supplementation lowered the risk of RCC among the study participants.

Three phase power factor controller

NASA Technical Reports Server (NTRS)

Nola, F. J. (Inventor)

1984-01-01

A power control circuit for a three phase induction motor is described. Power factors for the three phases are summed to provide a control signal, and this control signal is particularly filtered and then employed to control the duty cycle of each phase of input power to the motor.

Factors influencing buyers' willingness to offer price premiums for carbon credits sourced from urban forests

Treesearch

N.C. Poudyal; J.M. Bowker; J.P. Siry

2015-01-01

Marketing carbon offset credits generated by urban forest projects could help cities and local governments achieve their financial self-sufficiency and environmental sustainability goals. Understanding the value of carbon credits sourced from urban forests, and the factors that determine buyers’ willingness to pay a premium for such credits could benefit cities in...

Evaluation of carbon isotope flux partitioning theory under simplified and controlled environmental conditions

USDA-ARS?s Scientific Manuscript database

Separation of the photosynthetic (Fp) and respiratory (Fr) fluxes of net CO2 exchange (Fn)remains a necessary step toward understanding the biological and physical controls on carbon cycling between the soil, biomass, and atmosphere. Despite recent advancements in stable carbon isotope partitioning ...

Photo-Responsive Graphene and Carbon Nanotubes to Control and Tackle Biological Systems.

PubMed

Cardano, Francesca; Frasconi, Marco; Giordani, Silvia

2018-01-01

Photo-responsive multifunctional nanomaterials are receiving considerable attention for biological applications because of their unique properties. The functionalization of the surface of carbon nanotubes (CNTs) and graphene, among other carbon based nanomaterials, with molecular switches that exhibit reversible transformations between two or more isomers in response to different kind of external stimuli, such as electromagnetic radiation, temperature and pH, has allowed the control of the optical and electrical properties of the nanomaterial. Light-controlled molecular switches, such as azobenzene and spiropyran, have attracted a lot of attention for nanomaterial's functionalization because of the remote modulation of their physicochemical properties using light stimulus. The enhanced properties of the hybrid materials obtained from the coupling of carbon based nanomaterials with light-responsive switches has enabled the fabrication of smart devices for various biological applications, including drug delivery, bioimaging and nanobiosensors. In this review, we highlight the properties of photo-responsive carbon nanomaterials obtained by the conjugation of CNTs and graphene with azobenzenes and spiropyrans molecules to investigate biological systems, devising possible future directions in the field.

Photo-Responsive Graphene and Carbon Nanotubes to Control and Tackle Biological Systems

NASA Astrophysics Data System (ADS)

Cardano, Francesca; Frasconi, Marco; Giordani, Silvia

2018-04-01

Photo-responsive multifunctional nanomaterials are receiving considerable attention for biological applications because of their unique properties. The functionalization of the surface of carbon nanotubes (CNTs) and graphene, among other carbon based nanomaterials, with molecular switches that exhibit reversible transformations between two or more isomers in response to different kind of external stimuli, such as electromagnetic radiation, temperature and pH, has allowed the control of the optical and electrical properties of the nanomaterial. Light-controlled molecular switches, such as azobenzene and spiropyran, have attracted a lot of attention for nanomaterial’s functionalization because of the remote modulation of their physicochemical properties using light stimulus. The enhanced properties of the hybrid materials obtained from the coupling of carbon based nanomaterials with light-responsive switches has enabled the fabrication of smart devices for various biological applications, including drug delivery, bioimaging and nanobiosensors. In this review, we highlight the properties of photo-responsive carbon nanomaterials obtained by the conjugation of CNTs and graphene with azobenzenes and spiropyrans molecules to investigate biological systems, devising possible future directions in the field.

Photo-Responsive Graphene and Carbon Nanotubes to Control and Tackle Biological Systems

PubMed Central

Cardano, Francesca; Frasconi, Marco; Giordani, Silvia

2018-01-01

Photo-responsive multifunctional nanomaterials are receiving considerable attention for biological applications because of their unique properties. The functionalization of the surface of carbon nanotubes (CNTs) and graphene, among other carbon based nanomaterials, with molecular switches that exhibit reversible transformations between two or more isomers in response to different kind of external stimuli, such as electromagnetic radiation, temperature and pH, has allowed the control of the optical and electrical properties of the nanomaterial. Light-controlled molecular switches, such as azobenzene and spiropyran, have attracted a lot of attention for nanomaterial's functionalization because of the remote modulation of their physicochemical properties using light stimulus. The enhanced properties of the hybrid materials obtained from the coupling of carbon based nanomaterials with light-responsive switches has enabled the fabrication of smart devices for various biological applications, including drug delivery, bioimaging and nanobiosensors. In this review, we highlight the properties of photo-responsive carbon nanomaterials obtained by the conjugation of CNTs and graphene with azobenzenes and spiropyrans molecules to investigate biological systems, devising possible future directions in the field. PMID:29707534

[Measurement model of carbon emission from forest fire: a review].

PubMed

Hu, Hai-Qing; Wei, Shu-Jing; Jin, Sen; Sun, Long

2012-05-01

Forest fire is the main disturbance factor for forest ecosystem, and an important pathway of the decrease of vegetation- and soil carbon storage. Large amount of carbonaceous gases in forest fire can release into atmosphere, giving remarkable impacts on the atmospheric carbon balance and global climate change. To scientifically and effectively measure the carbonaceous gases emission from forest fire is of importance in understanding the significance of forest fire in the carbon balance and climate change. This paper reviewed the research progress in the measurement model of carbon emission from forest fire, which covered three critical issues, i. e., measurement methods of forest fire-induced total carbon emission and carbonaceous gases emission, affecting factors and measurement parameters of measurement model, and cause analysis of the uncertainty in the measurement of the carbon emissions. Three path selections to improve the quantitative measurement of the carbon emissions were proposed, i. e., using high resolution remote sensing data and improving algorithm and estimation accuracy of burned area in combining with effective fuel measurement model to improve the accuracy of the estimated fuel load, using high resolution remote sensing images combined with indoor controlled environment experiments, field measurements, and field ground surveys to determine the combustion efficiency, and combining indoor controlled environment experiments with field air sampling to determine the emission factors and emission ratio.

Revised methane emissions factors and spatially distributed annual carbon fluxes for global livestock.

PubMed

Wolf, Julie; Asrar, Ghassem R; West, Tristram O

2017-09-29

Livestock play an important role in carbon cycling through consumption of biomass and emissions of methane. Recent research suggests that existing bottom-up inventories of livestock methane emissions in the US, such as those made using 2006 IPCC Tier 1 livestock emissions factors, are too low. This may be due to outdated information used to develop these emissions factors. In this study, we update information for cattle and swine by region, based on reported recent changes in animal body mass, feed quality and quantity, milk productivity, and management of animals and manure. We then use this updated information to calculate new livestock methane emissions factors for enteric fermentation in cattle, and for manure management in cattle and swine. Using the new emissions factors, we estimate global livestock emissions of 119.1 ± 18.2 Tg methane in 2011; this quantity is 11% greater than that obtained using the IPCC 2006 emissions factors, encompassing an 8.4% increase in enteric fermentation methane, a 36.7% increase in manure management methane, and notable variability among regions and sources. For example, revised manure management methane emissions for 2011 in the US increased by 71.8%. For years through 2013, we present (a) annual livestock methane emissions, (b) complete annual livestock carbon budgets, including carbon dioxide emissions, and (c) spatial distributions of livestock methane and other carbon fluxes, downscaled to 0.05 × 0.05 degree resolution. Our revised bottom-up estimates of global livestock methane emissions are comparable to recently reported top-down global estimates for recent years, and account for a significant part of the increase in annual methane emissions since 2007. Our results suggest that livestock methane emissions, while not the dominant overall source of global methane emissions, may be a major contributor to the observed annual emissions increases over the 2000s to 2010s. Differences at regional and local scales may help

Adaptation of SUBSTOR for controlled-environment potato production with elevated carbon dioxide

NASA Technical Reports Server (NTRS)

Fleisher, D. H.; Cavazzoni, J.; Giacomelli, G. A.; Ting, K. C.; Janes, H. W. (Principal Investigator)

2003-01-01

The SUBSTOR crop growth model was adapted for controlled-environment hydroponic production of potato (Solanum tuberosum L. cv. Norland) under elevated atmospheric carbon dioxide concentration. Adaptations included adjustment of input files to account for cultural differences between the field and controlled environments, calibration of genetic coefficients, and adjustment of crop parameters including radiation use efficiency. Source code modifications were also performed to account for the absorption of light reflected from the surface below the crop canopy, an increased leaf senescence rate, a carbon (mass) balance to the model, and to modify the response of crop growth rate to elevated atmospheric carbon dioxide concentration. Adaptations were primarily based on growth and phenological data obtained from growth chamber experiments at Rutgers University (New Brunswick, N.J.) and from the modeling literature. Modified-SUBSTOR predictions were compared with data from Kennedy Space Center's Biomass Production Chamber for verification. Results show that, with further development, modified-SUBSTOR will be a useful tool for analysis and optimization of potato growth in controlled environments.

Calcium carbonates: induced biomineralization with controlled macromorphology

NASA Astrophysics Data System (ADS)

Meier, Aileen; Kastner, Anne; Harries, Dennis; Wierzbicka-Wieczorek, Maria; Majzlan, Juraj; Büchel, Georg; Kothe, Erika

2017-11-01

Biomineralization of (magnesium) calcite and vaterite by bacterial isolates has been known for quite some time. However, the extracellular precipitation has hardly ever been linked to different morphologies of the minerals that are observed. Here, isolates from limestone-associated groundwater, rock and soil were shown to form calcite, magnesium calcite or vaterite. More than 92 % of isolates were indeed able to form carbonates, while abiotic controls failed to form minerals. The crystal morphologies varied, including rhombohedra, prisms and pyramid-like macromorphologies. Different conditions like varying temperature, pH or media components, but also cocultivation to test for collaborative effects of sympatric bacteria, were used to differentiate between mechanisms of calcium carbonate formation. Single crystallites were cemented with bacterial cells; these may have served as nucleation sites by providing a basic pH at short distance from the cells. A calculation of potential calcite formation of up to 2 g L-1 of solution made it possible to link the microbial activity to geological processes.

Possible environmental, occupational, and other etiologic factors for Parkinson's disease: a case-control study in Germany.

PubMed

Seidler, A; Hellenbrand, W; Robra, B P; Vieregge, P; Nischan, P; Joerg, J; Oertel, W H; Ulm, G; Schneider, E

1996-05-01

In a case-control study, we investigated the possible etiologic relevance to Parkinson's disease (PD) of rural factors such as farming activity, pesticide exposures, well-water drinking, and animal contacts; toxicologic exposures such as wood preservatives, heavy metals, and solvents; general anesthesia; head trauma; and differences in the intrauterine environment. We recruited 380 patients in nine German clinics, 379 neighborhood control subjects, and 376 regional control subjects in the largest case-control study investigating such factors and collected data in structured personal interviews using conditional logistic regression to control for educational status and cigarette smoking. The latter was strongly inversely associated with PD. There were significantly elevated odds ratios (OR) for pesticide use, in particular, for organochlorines and alkylated phosphates, but no association was present between PD and other rural factors. A significantly elevated OR was present for exposure to wood preservatives. Subjective assessment by the probands indicated that exposure to some heavy metals, solvents, exhaust fumes, and carbon monoxide was significantly more frequent among patients than control subjects, but this was not confirmed by a parallel assessment of job histories according to a job exposure matrix. Patients had undergone general anesthesia and suffered severe head trauma more often than control subjects, but a dose-response gradient was not present. Patients reported a significantly larger number of amalgam-filled teeth before their illness than control subjects. The frequency of premature births and birth order did not differ between patients and control subjects. Patients reported significantly more relatives affected with PD than control subjects. These results support a role for environmental and genetic factors in the etiology of PD.

Carbon exchange between ecosystems and atmosphere in the Czech Republic is affected by climate factors.

PubMed

Marek, Michal V; Janouš, Dalibor; Taufarová, Klára; Havránková, Kateřina; Pavelka, Marian; Kaplan, Věroslav; Marková, Irena

2011-05-01

By comparing five ecosystem types in the Czech Republic over several years, we recorded the highest carbon sequestration potential in an evergreen Norway spruce forest (100%) and an agroecosystem (65%), followed by European beech forest (25%) and a wetland ecosystem (20%). Because of a massive ecosystem respiration, the final carbon gain of the grassland was negative. Climate was shown to be an important factor of carbon uptake by ecosystems: by varying the growing season length (a 22-d longer season in 2005 than in 2007 increased carbon sink by 13%) or by the effect of short- term synoptic situations (e.g. summer hot and dry days reduced net carbon storage by 58% relative to hot and wet days). Carbon uptake is strongly affected by the ontogeny and a production strategy which is demonstrated by the comparison of seasonal course of carbon uptake between coniferous (Norway spruce) and deciduous (European beech) stands. Copyright © 2011 Elsevier Ltd. All rights reserved.

Spatial and temporal control of the diazonium modification of sp2 carbon surfaces.

PubMed

Kirkman, Paul M; Güell, Aleix G; Cuharuc, Anatolii S; Unwin, Patrick R

2014-01-08

Interest in the controlled chemical functionalization of sp(2) carbon materials using diazonium compounds has been recently reignited, particularly as a means to generate a band gap in graphene. We demonstrate local diazonium modification of pristine sp(2) carbon surfaces, with high control, at the micrometer scale through the use of scanning electrochemical cell microscopy (SECCM). Electrochemically driven diazonium patterning is investigated at a range of driving forces, coupled with surface analysis using atomic force microscopy (AFM) and Raman spectroscopy. We highlight how the film density, level of sp(2)/sp(3) rehybridization and the extent of multilayer formation can be controlled, paving the way for the use of localized electrochemistry as a route to controlled diazonium modification.

Enhanced-Adhesion Multi-Walled Carbon Nanotubes on Titanium Substrates for Stray Light Control

NASA Technical Reports Server (NTRS)

Hagopian, John; Getty, Stephanie; Quijada, Manuel

2012-01-01

Carbon nanotubes previously grown on silicon have extremely low reflectance, making them a good candidate for stray light suppression. Silicon, however, is not a good structural material for stray light components such as tubes, stops, and baffles. Titanium is a good structural material and can tolerate the 700 C nanotube growth process. The ability to grow carbon nanotubes on a titanium substrate that are ten times blacker than the current NASA state-of-the-art paints in the visible to near infrared spectra has been achieved. This innovation will allow significant improvement of stray light performance in scientific instruments or any other optical system. This innovation is a refinement of the utilization of multiwalled carbon nano tubes for stray light suppression in spaceflight instruments. The innovation is a process to make the surface darker and improve the adhesion to the substrate, improving robustness for spaceflight use. Bright objects such as clouds or ice scatter light off of instrument structures and components and make it difficult to see dim objects in Earth observations. A darker material to suppress this stray light has multiple benefits to these observations, including enabling scientific observations not currently possible, increasing observational efficiencies in high-contrast scenes, and simplifying instruments and lowering their cost by utilizing fewer stray light components and achieving equivalent performance. The prior art was to use commercially available black paint, which resulted in approximately 4% of the light being reflected (hemispherical reflectance or total integrated scatter, or TIS). Use of multiwalled carbon nanotubes on titanium components such as baffles, entrance aperture, tubes, and stops, can decrease this scattered light by a factor of ten per bounce over the 200-nm to 2,500-nm wavelength range. This can improve system stray light performance by orders of magnitude. The purpose of the innovation is to provide an enhanced

Controllable synthesis of mesoporous carbon nanospheres and Fe-N/carbon nanospheres as efficient oxygen reduction electrocatalysts

NASA Astrophysics Data System (ADS)

Wei, Jing; Liang, Yan; Zhang, Xinyi; Simon, George P.; Zhao, Dongyuan; Zhang, Jin; Jiang, Sanping; Wang, Huanting

2015-03-01

The synthesis of mesoporous carbon nanospheres (MCNs), especially with diameters below 200 nm remains a great challenge due to weak interactions between the carbon precursors and soft templates, as well as the uncontrollable cross-linking rate of carbon precursors. Herein, we demonstrate a simple acid-assisted, hydrothermal synthesis approach to synthesizing such uniform MCNs with well controlled diameters ranging from 20 to 150 nm under highly acidic conditions (2 M HCl). Both the carbon precursor and the template are partly protonated under such conditions and show additional Coulombic interactions with chloride ions (acts as mediators). This kind of enhanced interaction is similar to that of the ``I+X-S+'' mechanism in the synthesis of mesoporous metal oxide, which can effectively retard the cross-linking rate of resol molecules and avoid macroscopic phase separation during the hydrothermal synthesis. Due to their uniform spherical morphology, small diameter, and high surface areas, MCNs can be modified with Fe and N species via impregnation of cheap precursors (ferric nitrate and dicyandiamide), which are further converted into nonprecious electrocatalysts for oxygen reduction reactions. The resulting Fe-N/MCNs exhibit high catalytic activities, long-term stability and improved methanol tolerance under alkaline conditions, which can be potentially used in direct methanol fuel cells and metal-air batteries.The synthesis of mesoporous carbon nanospheres (MCNs), especially with diameters below 200 nm remains a great challenge due to weak interactions between the carbon precursors and soft templates, as well as the uncontrollable cross-linking rate of carbon precursors. Herein, we demonstrate a simple acid-assisted, hydrothermal synthesis approach to synthesizing such uniform MCNs with well controlled diameters ranging from 20 to 150 nm under highly acidic conditions (2 M HCl). Both the carbon precursor and the template are partly protonated under such conditions

Shared control of gene expression in bacteria by transcription factors and global physiology of the cell

PubMed Central

Berthoumieux, Sara; de Jong, Hidde; Baptist, Guillaume; Pinel, Corinne; Ranquet, Caroline; Ropers, Delphine; Geiselmann, Johannes

2013-01-01

Gene expression is controlled by the joint effect of (i) the global physiological state of the cell, in particular the activity of the gene expression machinery, and (ii) DNA-binding transcription factors and other specific regulators. We present a model-based approach to distinguish between these two effects using time-resolved measurements of promoter activities. We demonstrate the strength of the approach by analyzing a circuit involved in the regulation of carbon metabolism in E. coli. Our results show that the transcriptional response of the network is controlled by the physiological state of the cell and the signaling metabolite cyclic AMP (cAMP). The absence of a strong regulatory effect of transcription factors suggests that they are not the main coordinators of gene expression changes during growth transitions, but rather that they complement the effect of global physiological control mechanisms. This change of perspective has important consequences for the interpretation of transcriptome data and the design of biological networks in biotechnology and synthetic biology. PMID:23340840

Carbon Dioxide Sealing Capacity: Textural or Compositional Controls?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cranganu, Constantin; Soleymani, Hamidreza; Sadiqua, Soleymani

2013-11-30

This research project is aiming to assess the carbon dioxide sealing capacity of most common seal-rocks, such as shales and non-fractured limestones, by analyzing the role of textural and compositional parameters of those rocks. We hypothesize that sealing capacity is controlled by textural and/or compositional pa-rameters of caprocks. In this research, we seek to evaluate the importance of textural and compositional parameters affecting the sealing capacity of caprocks. The conceptu-al framework involves two testable end-member hypotheses concerning the sealing ca-pacity of carbon dioxide reservoir caprocks. Better understanding of the elements controlling sealing quality will advance our knowledge regarding the sealingmore » capacity of shales and carbonates. Due to relatively low permeability, shale and non-fractured carbonate units are considered relatively imper-meable formations which can retard reservoir fluid flow by forming high capillary pres-sure. Similarly, these unites can constitute reliable seals for carbon dioxide capture and sequestration purposes. This project is a part of the comprehensive project with the final aim of studying the caprock sealing properties and the relationship between microscopic and macroscopic characteristics of seal rocks in depleted gas fields of Oklahoma Pan-handle. Through this study we examined various seal rock characteristics to infer about their respective effects on sealing capacity in special case of replacing reservoir fluid with super critical carbon dioxide (scCO{sub 2}). To assess the effect of textural and compositional properties on scCO{sub 2} maximum reten-tion column height we collected 30 representative core samples in caprock formations in three counties (Cimarron, Texas, Beaver) in Oklahoma Panhandle. Core samples were collected from various seal formations (e.g., Cherokee, Keys, Morrowan) at different depths. We studied the compositional and textural properties of the core samples using several

Digital image analysis of fingernail colour in cadavers comparing carbon monoxide poisoning to controls.

PubMed

Langlois, Neil E I

2010-03-01

Carbon monoxide is a component of motor vehicle exhaust fumes, provided a functional catalytic converter is not present. This gas binds avidly to the hemoglobin molecule in red blood cells preventing its oxygen transport function, effectively poisoning the body by starving it of oxygen. In binding to hemoglobin, carbon monoxide forms carboxyhemoglobin, which has a characteristic bright pink color. It has been remarked that the fingernails of victims of carbon monoxide tend to exhibit pink color, otherwise fingernails of deceased bodies tend towards a dark red to blue color. This study sought to objectively determine by using digital image analysis if a color difference occurred between the fingernails of a group of cadavers with carbon monoxide poisoning compared to a group of controls. The fingernails of the carbon monoxide group did tend to be more red than the controls, but due to overlap between the two groups assessment of the fingernails cannot be recommended as a rapid screening test.

Controlling the crystalline three-dimensional order in bulk materials by single-wall carbon nanotubes.

PubMed

López-Andarias, Javier; López, Juan Luis; Atienza, Carmen; Brunetti, Fulvio G; Romero-Nieto, Carlos; Guldi, Dirk M; Martín, Nazario

2014-04-29

The construction of ordered single-wall carbon nanotube soft-materials at the nanoscale is currently an important challenge in science. Here we use single-wall carbon nanotubes as a tool to gain control over the crystalline ordering of three-dimensional bulk materials composed of suitably functionalized molecular building blocks. We prepare p-type nanofibres from tripeptide and pentapeptide-containing small molecules, which are covalently connected to both carboxylic and electron-donating 9,10-di(1,3-dithiol-2-ylidene)-9,10-dihydroanthracene termini. Adding small amounts of single-wall carbon nanotubes to the so-prepared p-nanofibres together with the externally controlled self assembly by charge screening by means of Ca(2+) results in new and stable single-wall carbon nanotube-based supramolecular gels featuring remarkably long-range internal order.

Reconciling carbon-cycle concepts, terminology, and methodology

Treesearch

F.S. III Chapin; G.M Woodwell; J.T. Randerson; G.M. Lovett; E.B. Rastetter; D.D. Baldocchi; D.A. Clark; M.E. Harmon; D.S. Schimel; Valentini R.; Wirth C.; Aber J.D.; Cole J.J.; Goulden M.L.; Harden J.W.; Heimann M.; Howarth R.W.; Matson P.A.; McGuire A.D.; Melillo J.M.; H.A. Mooney; J.C. Neff; R.A. Houghton; M.L. Pace; M.G. Ryan; S.W. Running; O.E. Sala; W.H. Schlesinger; E. D. Schulze

2005-01-01

Recent projections of climatic change have focused a great deal of scientific and public attention on patterns of carbon (C) cycling as well as its controls, particularly the factors that determine whether an ecosystem is a net source or sink of atmospheric carbon dioxide (CO2). Net ecosystem production (NEP), a central concept in C-cycling research, has been used by...

Crystal shape controlled H2 storage rate in nanoporous carbon composite with ultra-fine Pt nanoparticle

PubMed Central

Chen, Tsan-Yao; Zhang, Yanhui; Hsu, Liang-Ching; Hu, Alice; Zhuang, Yu; Fan, Chia-Ming; Wang, Cheng-Yu; Chung, Tsui-Yun; Tsao, Cheng-Si; Chuang, Haw-Yeu

2017-01-01

This study demonstrates that the hydrogen storage rate (HSR) of nanoporous carbon supported platinum nanocatalysts (NC) is determined by their heterojunction and geometric configurations. The present NC is synthesized in an average particle size of ~1.5 nm by incipient wetness impregnation of Pt4+ at carbon support followed by annealing in H2 ambient at 102–105 °C. Among the steps in hydrogen storage, decomposition of H2 molecule into 2 H atoms on Pt NC surface is the deciding factor in HSR that is controlled by the thickness of Pt NC. For the best condition, HSR of Pt NC in 1~2 atomic layers thick (4.7 μg/g min) is 2.6 times faster than that (1.3 μg/g min) of Pt NC with higher than 3 atomic layers thick. PMID:28195224

Commercialization of the power factor controller

NASA Technical Reports Server (NTRS)

1981-01-01

The purpose of the Motor Power Controller, also known as the Power Factor Controller, is to improve power factor and reduce power dissipation in induction motors operating below full load. These purposes were studied and tested in detail. The Motor Power Controller is capable of raising power factors from 0.2 to 0.8 and results in energy savings. It was found that many motors, in their present operating applications, are classified as unstable. The electronic nature of the controller vs. the electrical nature of the motor, compound this problem due to the differences in response time of the two devices. Many tests were successfully completed, the most indicating greater savings than anticipated. Also, there was an effect on efficiency which was not included in the calculations.

40 CFR Table U-1 to Subpart U of... - CO2 Emission Factors for Common Carbonates

Code of Federal Regulations, 2011 CFR

2011-07-01

... Mineral name—carbonate CO2 emission factor(tons CO2/ton carbonate) Limestone—CaCO3 0.43971 Magnesite—MgCO3 0.52197 Dolomite—CaMg(CO3)2 0.47732 Siderite—FeCO3 0.37987 Ankerite—Ca(Fe, Mg, Mn)(CO3)2 0.47572...

40 CFR Table U-1 to Subpart U of... - CO2 Emission Factors for Common Carbonates

Code of Federal Regulations, 2014 CFR

2014-07-01

... Mineral name—carbonate CO2 emission factor(tons CO2/ton carbonate) Limestone—CaCO3 0.43971 Magnesite—MgCO3 0.52197 Dolomite—CaMg(CO3)2 0.47732 Siderite—FeCO3 0.37987 Ankerite—Ca(Fe, Mg, Mn)(CO3)2 0.47572...

40 CFR Table U-1 to Subpart U of... - CO2 Emission Factors for Common Carbonates

Code of Federal Regulations, 2013 CFR

2013-07-01

... Mineral name—carbonate CO2 emission factor(tons CO2/ton carbonate) Limestone—CaCO3 0.43971 Magnesite—MgCO3 0.52197 Dolomite—CaMg(CO3)2 0.47732 Siderite—FeCO3 0.37987 Ankerite—Ca(Fe, Mg, Mn)(CO3)2 0.47572...

40 CFR Table U-1 to Subpart U of... - CO2 Emission Factors for Common Carbonates

Code of Federal Regulations, 2012 CFR

2012-07-01

... Mineral name—carbonate CO2 emission factor(tons CO2/ton carbonate) Limestone—CaCO3 0.43971 Magnesite—MgCO3 0.52197 Dolomite—CaMg(CO3)2 0.47732 Siderite—FeCO3 0.37987 Ankerite—Ca(Fe, Mg, Mn)(CO3)2 0.47572...

Internal Active Thermal Control System (IATCS) Sodium Bicarbonate/Carbonate Buffer in an Open Aqueous Carbon Dioxide System and Corollary Electrochemical/Chemical Reactions Relative to System pH Changes

NASA Technical Reports Server (NTRS)

Stegman, Thomas W.; Wilson, Mark E.; Glasscock, Brad; Holt, Mike

2014-01-01

The International Space Station (ISS) Internal Active Thermal Control System (IATCS) experienced a number of chemical changes driven by system absorption of CO2 which altered the coolant’s pH. The natural effects of the decrease in pH from approximately 9.2 to less than 8.4 had immediate consequences on system corrosion rates and corrosion product interactions with specified coolant constituents. The alkalinity of the system was increased through the development and implementation of a carbonate/bicarbonate buffer that would increase coolant pH to 9.0 – 10.0 and maintain pH above 9.0 in the presence of ISS cabin concentrations of CO2 up to twenty times higher than ground concentrations. This paper defines how a carbonate/bicarbonate buffer works in an open carbon dioxide system and summarizes the analyses performed on the buffer for safe and effective application in the on-orbit system. The importance of the relationship between the cabin environment and the IATCS is demonstrated as the dominant factor in understanding the system chemistry and pH trends before and after addition of the carbonate/bicarbonate buffer. The paper also documents the corollary electrochemical and chemical reactions the system has experienced and the rationale for remediation of these effects with the addition of the carbonate/bicarbonate buffer.

Reliable and Affordable Control Systems Active Combustor Pattern Factor Control

NASA Technical Reports Server (NTRS)

McCarty, Bob; Tomondi, Chris; McGinley, Ray

2004-01-01

Active, closed-loop control of combustor pattern factor is a cooperative effort between Honeywell (formerly AlliedSignal) Engines and Systems and the NASA Glenn Research Center to reduce emissions and turbine-stator vane temperature variations, thereby enhancing engine performance and life, and reducing direct operating costs. Total fuel flow supplied to the engine is established by the speed/power control, but the distribution to individual atomizers will be controlled by the Active Combustor Pattern Factor Control (ACPFC). This system consist of three major components: multiple, thin-film sensors located on the turbine-stator vanes; fuel-flow modulators for individual atomizers; and control logic and algorithms within the electronic control.

Spatially Explicit Simulation of Mesotopographic Controls on Peatland Hydrology and Carbon Fluxes

NASA Astrophysics Data System (ADS)

Sonnentag, O.; Chen, J. M.; Roulet, N. T.

2006-12-01

A number of field carbon flux measurements, paleoecological records, and model simulations have acknowledged the importance of northern peatlands in terrestrial carbon cycling and methane emissions. An important parameter in peatlands that influences both net primary productivity, the net gain of carbon through photosynthesis, and decomposition under aerobic and anaerobic conditions, is the position of the water table. Biological and physical processes involved in peatland carbon dynamics and their hydrological controls operate at different spatial scales. The highly variable hydraulic characteristics of the peat profile and the overall shape of the peat body as defined by its surface topography at the mesoscale (104 m2) are of major importance for peatland water table dynamics. Common types of peatlands include bogs with a slightly domed centre. As a result of the convex profile, their water supply is restricted to atmospheric inputs, and water is mainly shed by shallow subsurface flow. From a modelling perspective the influence of mesotopographic controls on peatland hydrology and thus carbon balance requires that process-oriented models that examine the links between peatland hydrology, ecosystem functioning, and climate must incorporate some form of lateral subsurface flow consideration. Most hydrological and ecological modelling studies in complex terrain explicitly account for the topographic controls on lateral subsurface flow through digital elevation models. However, modelling studies in peatlands often employ simple empirical parameterizations of lateral subsurface flow, neglecting the influence of peatlands low relief mesoscale topography. Our objective is to explicitly simulate the mesotopographic controls on peatland hydrology and carbon fluxes using the Boreal Ecosystem Productivity Simulator (BEPS) adapted to northern peatlands. BEPS is a process-oriented ecosystem model in a remote sensing framework that takes into account peatlands multi

Controlled gas-liquid interfacial plasmas for synthesis of nano-bio-carbon conjugate materials

NASA Astrophysics Data System (ADS)

Kaneko, Toshiro; Hatakeyama, Rikizo

2018-01-01

Plasmas generated in contact with a liquid have been recognized to be a novel reactive field in nano-bio-carbon conjugate creation because several new chemical reactions have been yielded at the gas-liquid interface, which were induced by the physical dynamics of non-equilibrium plasmas. One is the ion irradiation to a liquid, which caused the spatially selective dissociation of the liquid and the generation of additive reducing and oxidizing agents, resulting in the spatially controlled synthesis of nanostructures. The other is the electron irradiation to a liquid, which directly enhanced the reduction action at the plasma-liquid interface, resulting in temporally controlled nanomaterial synthesis. Using this novel reaction field, gold nanoparticles with controlled interparticle distance were synthesized using carbon nanotubes as a template. Furthermore, nanoparticle-biomolecule conjugates and nanocarbon-biomolecule conjugates were successfully synthesized by an aqueous-solution contact plasma and an electrolyte plasma, respectively, which were rapid and low-damage processes suitable for nano-bio-carbon conjugate materials.

Geomorphic control of landscape carbon accumulation

USGS Publications Warehouse

Rosenbloom, N.A.; Harden, J.W.; Neff, J.C.; Schimel, D.S.

2006-01-01

We use the CREEP process-response model to simulate soil organic carbon accumulation in an undisturbed prairie site in Iowa. Our primary objectives are to identify spatial patterns of carbon accumulation, and explore the effect of erosion on basin-scale C accumulation. Our results point to two general findings. First, redistribution of soil carbon by erosion results in a net increase in basin-wide carbon storage relative to a noneroding environment. Landscape-average mean residence times are increased in an eroding landscape owing to the burial/preservation of otherwise labile C. Second, field observations taken along a slope transect may overlook significant intraslope variations in carbon accumulation. Spatial patterns of modeled deep C accumulation are complex. While surface carbon with its relatively short equilibration time is predictable from surface properties, deep carbon is strongly influenced by the landscape's geomorphic and climatic history, resulting in wide spatial variability. Convergence and divergence associated with upland swales and interfluves result in bimodal carbon distributions in upper and mid slopes; variability in carbon storage within modeled mid slopes was as high as simulated differences between erosional shoulders and depositional valley bottoms. The bimodality of mid-slope C variability in the model suggests that a three-dimensional sampling strategy is preferable over the traditional two-dimensional analog or "catena" approach. Copyright 2006 by the American Geophysical Union.

Mineralogical Controls on Carbon Cycling in a Floodplain Environment

NASA Astrophysics Data System (ADS)

Arora, B.; Dwivedi, D.; Steefel, C. I.; Spycher, N.; Fox, P. M.; Nico, P. S.

2016-12-01

-associated organic carbon as compared to non-NRZ locations. Results therefore suggest that soil mineralogy constitutes a dominant control over organic carbon stocks and residence times. A mechanistic representation of soil mineral-organic-microbe interactions is necessary to reproduce SOM profiles at the site.

Heart Disease Risk Factors You Can't Control

MedlinePlus

... Submit Heart disease risk factors you can't control Some factors you can't control, like pregnancy ... 2018. Heart disease risk factors you can't control Age and menopause As you get older, your ...

Enhanced water vapor separation by temperature-controlled aligned-multiwalled carbon nanotube membranes.

PubMed

Jeon, Wonjae; Yun, Jongju; Khan, Fakhre Alam; Baik, Seunghyun

2015-09-14

Here we present a new strategy of selectively rejecting water vapor while allowing fast transport of dry gases using temperature-controlled aligned-multiwalled carbon nanotubes (aligned-MWNTs). The mechanism is based on the water vapor condensation at the entry region of nanotubes followed by removing aggregated water droplets at the tip of the superhydrophobic aligned-MWNTs. The first condensation step could be dramatically enhanced by decreasing the nanotube temperature. The permeate-side relative humidity was as low as ∼17% and the helium-water vapor separation factor was as high as 4.62 when a helium-water vapor mixture with a relative humidity of 100% was supplied to the aligned-MWNTs. The flow through the interstitial space of the aligned-MWNTs allowed the permeability of single dry gases an order of magnitude higher than the Knudsen prediction regardless of membrane temperature. The water vapor separation performance of hydrophobic polytetrafluoroethylene membranes could also be significantly enhanced at low temperatures. This work combines the membrane-based separation technology with temperature control to enhance water vapor separation performance.

Inter-annual variability of carbon fluxes in temperate forest ecosystems: effects of biotic and abiotic factors

NASA Astrophysics Data System (ADS)

Chen, M.; Keenan, T. F.; Hufkens, K.; Munger, J. W.; Bohrer, G.; Brzostek, E. R.; Richardson, A. D.

2014-12-01

Carbon dynamics in terrestrial ecosystems are influenced by both abiotic and biotic factors. Abiotic factors, such as variation in meteorological conditions, directly drive biophysical and biogeochemical processes; biotic factors, referring to the inherent properties of the ecosystem components, reflect the internal regulating effects including temporal dynamics and memory. The magnitude of the effect of abiotic and biotic factors on forest ecosystem carbon exchange has been suggested to vary at different time scales. In this study, we design and conduct a model-data fusion experiment to investigate the role and relative importance of the biotic and abiotic factors for inter-annual variability of the net ecosystem CO2 exchange (NEE) of temperate deciduous forest ecosystems in the Northeastern US. A process-based model (FöBAAR) is parameterized at four eddy-covariance sites using all available flux and biometric measurements. We conducted a "transplant" modeling experiment, that is, cross- site and parameter simulations with different combinations of site meteorology and parameters. Using wavelet analysis and variance partitioning techniques, analysis of model predictions identifies both spatial variant and spatially invariant parameters. Variability of NEE was primarily modulated by gross primary productivity (GPP), with relative contributions varying from hourly to yearly time scales. The inter-annual variability of GPP and NEE is more regulated by meteorological forcing, but spatial variability in certain model parameters (biotic response) has more substantial effects on the inter-annual variability of ecosystem respiration (Reco) through the effects on carbon pools. Both the biotic and abiotic factors play significant roles in modulating the spatial and temporal variability in terrestrial carbon cycling in the region. Together, our study quantifies the relative importance of both, and calls for better understanding of them to better predict regional CO2

Mesoporous wormholelike carbon with controllable nanostructure for lithium ion batteries application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Xiaoqing, E-mail: yxq-886@163.com; Li, Xinxi; Li, Zhenghui

2015-06-15

Highlights: • Wormholelike carbon (WMC) with controllable nanostructure is prepared by sol–gel method. • The reversible capacity of WMC is much higher than that of many other reported nanocarbons. • The effect of pore diameter on Li storage capacity is investigated. - Abstract: A class of mesoporous wormholelike carbon (WMC) with controllable nanostructure was prepared by sol–gel method and then used as the anode material of lithium-ion batteries. Based on the experimental results, it is found that the nanostructure of the as-prepared WMC plays an important role in the electrochemical performances. A suitable mesopore size is necessary for a highmore » performance carbon-based anode material since it can not only guarantee effective mass transport channels but also provide large surface area. As a result, F30 with a mesopore size of 4.4 nm coupled with high surface area of 1077 m{sup 2} g{sup −1} shows a reversible capacity of 630 mAh g{sup −1}, much higher than commercial graphite and many other reported nanocarbons.« less

Advances in the Control System for a High Precision Dissolved Organic Carbon Analyzer

NASA Astrophysics Data System (ADS)

Liao, M.; Stubbins, A.; Haidekker, M.

2017-12-01

Dissolved organic carbon (DOC) is a master variable in aquatic ecosystems. DOC in the ocean is one of the largest carbon stores on earth. Studies of the dynamics of DOC in the ocean and other low DOC systems (e.g. groundwater) are hindered by the lack of high precision (sub-micromolar) analytical techniques. Results are presented from efforts to construct and optimize a flow-through, wet chemical DOC analyzer. This study focused on the design, integration and optimization of high precision components and control systems required for such a system (mass flow controller, syringe pumps, gas extraction, reactor chamber with controlled UV and temperature). Results of the approaches developed are presented.

Mineralogical Controls over Carbon Storage and Residence Times in Grassland Soils

NASA Astrophysics Data System (ADS)

Dwivedi, D.; Riley, W. J.; Torn, M. S.; Spycher, N.

2014-12-01

Globally, soil organic matter (SOM) contains approximately three times more carbon than the atmosphere and terrestrial vegetation contain combined. However, it is not well understood why some SOM persists for a long time while other SOM decomposes quickly. For future climate predictions, representing soil organic matter (SOM) dynamics accurately in Earth system models is essential. Soil minerals stabilize organic carbon in soil; however, there are gaps in our understanding of how soil mineralogy controls the quantity and turnover of long-residence-time organic carbon. To investigate the impact of soil mineralogy on SOM dynamics, we used a new model (Biotic and Abiotic Model of SOM—BAMS1 [Riley et al., 2014]) integrated with a three-dimensional, multiphase reactive transport solver (TOUGHREACT). The model represents bacterial and fungal activity, archetypal polymer and monomer carbon substrate groups, aqueous chemistry, gaseous diffusion, aqueous advection and diffusion, and adsorption and desorption processes. BAMS1 can predict bulk SOM and radiocarbon signatures without resorting to an arbitrary depth-dependent decline in SOM turnover rates. Results show a reasonable match between observed and simulated depth-resolved SOM and Δ14C in grassland ecosystems (soils formed on terraces south of Eureka, California, and the Central Chernozem Region of Russia) and were consistent with expectations of depth-resolved profiles of lignin content and fungi:aerobic bacteria ratios. Results also suggest that clay-mineral surface area and soil sorption coefficients constitute dominant controls over organic carbon stocks and residence times, respectively. Bibliography: Riley, W.J., F.M. Maggi, M. Kleber, M.S. Torn, J.Y. Tang, D. Dwivedi, and N. Guerry (2014), Long residence times of rapidly decomposable soil organic matter: application of a multi-phase, multi-component, and vertically resolved model (BAMS1) to soil carbon dynamics, Geoscientific Model Development, vol. 7, 1335

Controlled release of alendronate from nitrogen-doped mesoporous carbon

DOE PAGES

Saha, Dipendu; Spurri, Amanda; Chen, Jihua; ...

2016-04-13

With this study, we have synthesized a nitrogen doped mesoporous carbon with the BET surface area of 1066 m 2/g, total pore volume 0.6 cm 3/g and nitrogen content of 0.5%. Total alendronate adsorption in this carbon was ~5%. The release experiments were designed in four different media with sequential pH values of 1.2, 4.5, 6.8 and 7.4 for 3, 1, 3 and 5 h, respectively and at 37 °C to imitate the physiological conditions of stomach, duodenum, small intestine and colon, respectively. Release of the drug demonstrated a controlled fashion; only 20% of the drug was released in themore » media with pH = 1.2, whereas 64% of the drug was released in pH = 7.4. This is in contrary to pure alendronate that was completely dissolved within 30 min in the first release media (pH = 1.2) only. The relatively larger uptake of alendronate in this carbon and its sustained fashion of release can be attributed to the hydrogen bonding between the drug and the nitrogen functionalities on carbon surface. Based on this result, it can be inferred that this formulation may lower the side effects of oral delivery of alendronate.« less

Risk and Protective Factors for Fires, Burns, and Carbon Monoxide Poisoning in U.S. Households

PubMed Central

Runyan, Carol W.; Johnson, Renee M.; Yang, Jingzhen; Waller, Anna E.; Perkis, David; Marshall, Stephen W.; Coyne-Beasley, Tamera; McGee, Kara S.

2011-01-01

Background More needs to be known about the prevalence of risk and protective factors for fires, burns, and carbon monoxide poisoning in U.S. households. Methods A random-digit-dial survey was conducted about home safety with 1003 respondents representing households in the continental United States. Descriptive statistics assess the prevalence of risk and protective factors for fires, burns, and carbon monoxide overall, and by demographic characteristics, household structure, region, and residential tenure. The data were weighted to adjust for nonresponse and to reflect the U.S. population. Results Although most respondents reported having a smoke alarm (97%), and 80% reported having one on each level of their home, <20% reported checking the alarm at least every 3 months. Seventy-one percent reported having a fire extinguisher, 29% had a carbon monoxide detector, and 51% of those living with at least one other person had a fire escape plan. Few could report the temperature of their hot water at the tap (9%), or the setting on the hot water heater (25%). Only 6% had an antiscald device. Conclusions Results suggest that there is much room for improvement regarding adoption of measures to prevent fires, burns, and carbon monoxide poisoning. Further investigations of the efficacy of carbon monoxide detectors, fire extinguishers, and escape plans, as well as effectiveness studies of fire and burn-prevention efforts are needed. PMID:15626564

Risk and protective factors for fires, burns, and carbon monoxide poisoning in U.S. households.

PubMed

Runyan, Carol W; Johnson, Renee M; Yang, Jingzhen; Waller, Anna E; Perkis, David; Marshall, Stephen W; Coyne-Beasley, Tamera; McGee, Kara S

2005-01-01

More needs to be known about the prevalence of risk and protective factors for fires, burns, and carbon monoxide poisoning in U.S. households. A random-digit-dial survey was conducted about home safety with 1003 respondents representing households in the continental United States. Descriptive statistics assess the prevalence of risk and protective factors for fires, burns, and carbon monoxide overall, and by demographic characteristics, household structure, region, and residential tenure. The data were weighted to adjust for nonresponse and to reflect the U.S. population. Although most respondents reported having a smoke alarm (97%), and 80% reported having one on each level of their home, <20% reported checking the alarm at least every 3 months. Seventy-one percent reported having a fire extinguisher, 29% had a carbon monoxide detector, and 51% of those living with at least one other person had a fire escape plan. Few could report the temperature of their hot water at the tap (9%), or the setting on the hot water heater (25%). Only 6% had an antiscald device. Results suggest that there is much room for improvement regarding adoption of measures to prevent fires, burns, and carbon monoxide poisoning. Further investigations of the efficacy of carbon monoxide detectors, fire extinguishers, and escape plans, as well as effectiveness studies of fire and burn-prevention efforts are needed.

Dynamic and inertial controls on forest carbon-water relations

NASA Astrophysics Data System (ADS)

Maxwell, T.; Silva, L.; Horwath, W. R.

2017-12-01

This study fuses theory, empirical measurements, and statistical models to evaluate multiple processes controlling coupled carbon-water cycles in forest ecosystems. A series of latitudinal and altitudinal transects across the California Sierra Nevada was used to study the effects of climatic and edaphic gradients on intrinsic water-use efficiency (iWUE) - CO2 fixed per unit of water lost via transpiration - of nine dominant trees species. Transfer functions were determined between leaf, litter, and soil organic matter stable isotope ratios of carbon, oxygen, and nitrogen, revealing causal links between the physiological performance of tree species and stand-level estimations of productivity and water balance. Our results show that species iWUE is governed both by leaf traits (24% of the variation) and edaphic properties, such as parent material and soil development (3% and 12% of the variation, respectively). We show that soil properties combined with isotopic indicators can be used to explain constraints over iWUE by regulating water and nutrient availability across elevation gradients. Based on observed compositional shifts likely driven by changing climates in the region, encroachment of broad leaf trees could lead to an 80% increase in water loss via transpiration for each unit of CO2 fixed in Sierra mixed conifer zones. A combination of field-based, laboratory, and remote sensed data provide a useful framework for differentiating the effect of multiple controls of carbon and water cycles in temperate forest ecosystems.

Tectonic control of the crustal organic carbon reservoir during the Precambrian

NASA Technical Reports Server (NTRS)

Des Marais, D. J.

1994-01-01

Carbon isotopic trends indicate that the crustal reservoir of reduced, organic carbon increased during the Proterozoic, particularly during periods of widespread continental rifting and orogeny. No long-term trends are apparent in the concentration of organic carbon in shales, cherts and carbonates. The age distribution of 261 sample site localities sampled for well-preserved sedimentary rocks revealed a 500-700-Ma periodicity which coincided with tectonic cycles. It is assumed that the numbers of sites are a proxy for mass of sediments. A substantial increase in the number of sites in the late Archean correlates with the first appearance between 2.9 and 2.5 Ga of extensive continental platforms and their associated sedimentation. It is proposed that the size of the Proterozoic crustal organic carbon reservoir has been modulated by tectonic control of the volume of sediments deposited in environments favorable for the burial and preservation of organic matter. Stepwise increases in this reservoir would have caused the oxidation state of the Proterozoic environment to increase in a stepwise fashion.

Shape‐Controlled, Self‐Wrapped Carbon Nanotube 3D Electronics

PubMed Central

Wang, Huiliang; Wang, Yanming; Tee, Benjamin C.‐K.; Kim, Kwanpyo; Lopez, Jeffrey; Cai, Wei

2015-01-01

The mechanical flexibility and structural softness of ultrathin devices based on organic thin films and low‐dimensional nanomaterials have enabled a wide range of applications including flexible display, artificial skin, and health monitoring devices. However, both living systems and inanimate systems that are encountered in daily lives are all 3D. It is therefore desirable to either create freestanding electronics in a 3D form or to incorporate electronics onto 3D objects. Here, a technique is reported to utilize shape‐memory polymers together with carbon nanotube flexible electronics to achieve this goal. Temperature‐assisted shape control of these freestanding electronics in a programmable manner is demonstrated, with theoretical analysis for understanding the shape evolution. The shape control process can be executed with prepatterned heaters, desirable for 3D shape formation in an enclosed environment. The incorporation of carbon nanotube transistors, gas sensors, temperature sensors, and memory devices that are capable of self‐wrapping onto any irregular shaped‐objects without degradations in device performance is demonstrated. PMID:27980972

Carbon nanowall scaffold to control culturing of cervical cancer cells

NASA Astrophysics Data System (ADS)

Watanabe, Hitoshi; Kondo, Hiroki; Okamoto, Yukihiro; Hiramatsu, Mineo; Sekine, Makoto; Baba, Yoshinobu; Hori, Masaru

2014-12-01

The effect of carbon nanowalls (CNWs) on the culturing rate and morphological control of cervical cancer cells (HeLa cells) was investigated. CNWs with different densities were grown using plasma-enhanced chemical vapor deposition and subjected to post-growth plasma treatment for modification of the surface terminations. Although the surface wettability of the CNWs was not significantly dependent on the CNW densities, the cell culturing rates were significantly dependent. Morphological changes of the cells were not significantly dependent on the density of CNWs. These results indicate that plasma-induced surface morphology and chemical terminations enable nanobio applications using carbon nanomaterials.

Baltic Sea Blue Carbon: Role of environmental factors influencing the carbon sink capacity of eelgrass (Zostera marina) meadows.

NASA Astrophysics Data System (ADS)

Röhr, E.; Holmer, M.; Boström, C.

2016-02-01

Although the global seagrass coverage area is less than 0.2 % of the worlds ocean floor, the carbon sink capacity of seagrasses may account up to 18 % of oceanic carbon burial and thus play a critical structural and functional role in many coastal ecosystems. Recent studies have shown considerable variation in the global estimates for seagrass meadow Corg accumulation rates and stocks, and indicate lack of understanding the factors influencing this variability. We sampled 20 eelgrass (Zostera marina) meadows in Finland and Denmark to study the variation in Corg accumulation rates and stocks within the Baltic Sea area. The study sites in both regions spanned a gradient from sheltered to exposed locations. The estimates for Corg accumulation rates at the Finnish eelgrass meadows were two orders of magnitude lower than the estimates for the Danish sites. The Corg stock integrated over the top 25 cm of sediment showed similar pattern, suggesting that the Finnish eelgrass meadows are carbon sources rather than carbon sinks, and the produced Corg is exported from the meadows. In contrast, at the Danish sites both Corg accumulation rates and areal Corg stock was more varying suggesting, that in this region the meadows function both as carbon sinks and sources. Our analysis further showed that a large percentage (> 55 %) of the variation in the Corg stocks was explained by sediment characteristics (density, fraction of silt and grain size distribution). In addition, the contribution of Zostera marina detritus to the sediment Corg pool explained >14 % of the variation in the Corg stocks. In order to get more reliable regional and global estimates of the role of seagrass meadows in the ocean carbon cycle, more studies accounting for the full range of environmental and species characteristics are urgently needed.

Origin and effect factors of sedimentary organic carbon in a karst groundwater-fed reservoir, South China.

PubMed

Huang, Siyu; Pu, Junbing; Cao, Jianhua; Li, Jianhong; Zhang, Tao; Jiang, Feng; Li, Li; Wu, Feihong; Pan, Moucheng; Bai, Bing

2018-03-01

Reservoirs are commonly recharged by groundwater that is rich in bicarbonate ions in karst regions of South China, and the recharge of this groundwater to the reservoir can affect the biogeochemical processes of carbon sedimentation at the reservoir bottom. In this study, Dalongdong Reservoir, which is mainly recharged by two subterranean streams, was investigated based on a 42-cm-thick sedimentary core and the 210 Pb/ 137 Cs dating technique and isotope analyses to understand the sedimentary history and identify the carbon sources. The 210 Pb/ 137 Cs age model showed that the sediments were accumulated over the last 60 years. The annual increase precipitation and temperature showed no obvious change compared with trends of δ 13 C in total organic carbon (δ 13 C org ), δ 15 N values in total nitrogen, and the carbon and nitrogen ratio (C/N). This shows that climate was not the main control of the variation in sediment factors. Based on δ 13 C org , δ 15 N, C/N, and isotopic mixing modeling, sources of organic carbon in the sediments were derived from plankton (60.84%), soil (22.93%), waste water (14.56%), and terrestrial plants (1.67%). From 1958 to 1978, reservoir establishment and leakage affected the contribution of the four sources. The contribution of the plankton source increased from 1978 to 2015, resulting from change of water level and continued input of external nitrogen. However, because of the revegetation supplied by an economic aid project the contribution of soil showed a considerable decreasing trend from 1978 to 2002. After 2002, For "Grain for Green" project, the contribution from soil further decreased. After reservoir construction, the contribution of waste water stabilized. The contribution of terrestrial plants started increased rapidly after 2002. Karst groundwater, which contains more dissolved inorganic carbon containing lower δ 13 C DIC than the water sources of other lakes or reservoirs, makes the δ 13 C org value of sediment more

Controllable synthesis of single-walled carbon nanotube framework membranes and capsules.

PubMed

Song, Changsik; Kwon, Taeyun; Han, Jae-Hee; Shandell, Mia; Strano, Michael S

2009-12-01

Controlling the morphology of membrane components at the nanometer scale is central to many next-generation technologies in water purification, gas separation, fuel cell, and nanofiltration applications. Toward this end, we report the covalent assembly of single-walled carbon nanotubes (SWNTs) into three-dimensional framework materials with intertube pores controllable by adjusting the size of organic linker molecules. The frameworks are fashioned into multilayer membranes possessing linker spacings from 1.7 to 3.0 nm, and the resulting framework films were characterized, including transport properties. Nanoindentation measurements by atomic force microscopy show that the spring constant of the SWNT framework film (22.6 +/- 1.2 N/m) increased by a factor of 2 from the control value (10.4 +/- 0.1 N/m). The flux ratio comparison in a membrane-permeation experiment showed that larger spacer sizes resulted in larger pore structures. This synthetic method was equally efficient on silica microspheres, which could then be etched to create all-SWNT framework, hollow capsules approximately 5 mum in diameter. These hollow capsules are permeable to organic and inorganic reagents, allowing one to form inorganic nanoparticles, for example, that become entrapped within the capsule. The ability to encapsulate functional nanomaterials inside perm-selective SWNT cages and membranes may find applications in new adsorbents, novel catalysts, and drug delivery vehicles.

Carbonate-sensitive phytotransferrin controls high-affinity iron uptake in diatoms

NASA Astrophysics Data System (ADS)

McQuaid, Jeffrey B.; Kustka, Adam B.; Oborník, Miroslav; Horák, Aleš; McCrow, John P.; Karas, Bogumil J.; Zheng, Hong; Kindeberg, Theodor; Andersson, Andreas J.; Barbeau, Katherine A.; Allen, Andrew E.

2018-03-01

In vast areas of the ocean, the scarcity of iron controls the growth and productivity of phytoplankton. Although most dissolved iron in the marine environment is complexed with organic molecules, picomolar amounts of labile inorganic iron species (labile iron) are maintained within the euphotic zone and serve as an important source of iron for eukaryotic phytoplankton and particularly for diatoms. Genome-enabled studies of labile iron utilization by diatoms have previously revealed novel iron-responsive transcripts, including the ferric iron-concentrating protein ISIP2A, but the mechanism behind the acquisition of picomolar labile iron remains unknown. Here we show that ISIP2A is a phytotransferrin that independently and convergently evolved carbonate ion-coordinated ferric iron binding. Deletion of ISIP2A disrupts high-affinity iron uptake in the diatom Phaeodactylum tricornutum, and uptake is restored by complementation with human transferrin. ISIP2A is internalized by endocytosis, and manipulation of the seawater carbonic acid system reveals a second-order dependence on the concentrations of labile iron and carbonate ions. In P. tricornutum, the synergistic interaction of labile iron and carbonate ions occurs at environmentally relevant concentrations, revealing that carbonate availability co-limits iron uptake. Phytotransferrin sequences have a broad taxonomic distribution and are abundant in marine environmental genomic datasets, suggesting that acidification-driven declines in the concentration of seawater carbonate ions will have a negative effect on this globally important eukaryotic iron acquisition mechanism.

Substrate and environmental controls on microbial assimilation of soil organic carbon: a framework for Earth System Models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xu, Xiaofeng; Schimel, Joshua; Thornton, Peter E

2014-01-01

Microbial assimilation of soil organic carbon is one of the fundamental processes of global carbon cycling and it determines the magnitude of microbial biomass in soils. Mechanistic understanding of microbial assimilation of soil organic carbon and its controls is important for to improve Earth system models ability to simulate carbon-climate feedbacks. Although microbial assimilation of soil organic carbon is broadly considered to be an important parameter, it really comprises two separate physiological processes: one-time assimilation efficiency and time-dependent microbial maintenance energy. Representing of these two mechanisms is crucial to more accurately simulate carbon cycling in soils. In this study, amore » simple modeling framework was developed to evaluate the substrate and environmental controls on microbial assimilation of soil organic carbon using a new term: microbial annual active period (the length of microbes remaining active in one year). Substrate quality has a positive effect on microbial assimilation of soil organic carbon: higher substrate quality (lower C:N ratio) leads to higher ratio of microbial carbon to soil organic carbon and vice versa. Increases in microbial annual active period from zero stimulate microbial assimilation of soil organic carbon; however, when microbial annual active period is longer than an optimal threshold, increasing this period decreases microbial biomass. The simulated ratios of soil microbial biomass to soil organic carbon are reasonably consistent with a recently compiled global dataset at the biome-level. The modeling framework of microbial assimilation of soil organic carbon and its controls developed in this study offers an applicable ways to incorporate microbial contributions to the carbon cycling into Earth system models for simulating carbon-climate feedbacks and to explain global patterns of microbial biomass.« less

40 CFR 52.2428 - Control Strategy: Carbon monoxide and ozone.

Code of Federal Regulations, 2010 CFR

2010-07-01

... ozone. 52.2428 Section 52.2428 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Control Strategy: Carbon monoxide and ozone. (a) Determination—EPA has determined that, as of November 5, 1997, the Richmond ozone nonattainment area, which consists of the counties of Chesterfield, Hanover...

40 CFR 52.2428 - Control Strategy: Carbon monoxide and ozone.

Code of Federal Regulations, 2013 CFR

2013-07-01

... ozone. 52.2428 Section 52.2428 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Control Strategy: Carbon monoxide and ozone. (a) Determination—EPA has determined that, as of November 5, 1997, the Richmond ozone nonattainment area, which consists of the counties of Chesterfield, Hanover...

40 CFR 52.2428 - Control Strategy: Carbon monoxide and ozone.

Code of Federal Regulations, 2012 CFR

2012-07-01

... ozone. 52.2428 Section 52.2428 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Control Strategy: Carbon monoxide and ozone. (a) Determination—EPA has determined that, as of November 5, 1997, the Richmond ozone nonattainment area, which consists of the counties of Chesterfield, Hanover...

40 CFR 52.2428 - Control Strategy: Carbon monoxide and ozone.

Code of Federal Regulations, 2014 CFR

2014-07-01

... ozone. 52.2428 Section 52.2428 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Control Strategy: Carbon monoxide and ozone. (a) Determination—EPA has determined that, as of November 5, 1997, the Richmond ozone nonattainment area, which consists of the counties of Chesterfield, Hanover...

40 CFR 52.2428 - Control Strategy: Carbon monoxide and ozone.

Code of Federal Regulations, 2011 CFR

2011-07-01

... ozone. 52.2428 Section 52.2428 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Control Strategy: Carbon monoxide and ozone. (a) Determination—EPA has determined that, as of November 5, 1997, the Richmond ozone nonattainment area, which consists of the counties of Chesterfield, Hanover...

Intrinsically disordered and pliable Starmaker-like protein from medaka (Oryzias latipes) controls the formation of calcium carbonate crystals.

PubMed

Różycka, Mirosława; Wojtas, Magdalena; Jakób, Michał; Stigloher, Christian; Grzeszkowiak, Mikołaj; Mazur, Maciej; Ożyhar, Andrzej

2014-01-01

Fish otoliths, biominerals composed of calcium carbonate with a small amount of organic matrix, are involved in the functioning of the inner ear. Starmaker (Stm) from zebrafish (Danio rerio) was the first protein found to be capable of controlling the formation of otoliths. Recently, a gene was identified encoding the Starmaker-like (Stm-l) protein from medaka (Oryzias latipes), a putative homologue of Stm and human dentine sialophosphoprotein. Although there is no sequence similarity between Stm-l and Stm, Stm-l was suggested to be involved in the biomineralization of otoliths, as had been observed for Stm even before. The molecular properties and functioning of Stm-l as a putative regulatory protein in otolith formation have not been characterized yet. A comprehensive biochemical and biophysical analysis of recombinant Stm-l, along with in silico examinations, indicated that Stm-l exhibits properties of a coil-like intrinsically disordered protein. Stm-l possesses an elongated and pliable structure that is able to adopt a more ordered and rigid conformation under the influence of different factors. An in vitro assay of the biomineralization activity of Stm-l indicated that Stm-l affected the size, shape and number of calcium carbonate crystals. The functional significance of intrinsically disordered properties of Stm-l and the possible role of this protein in controlling the formation of calcium carbonate crystals is discussed.

Intrinsically Disordered and Pliable Starmaker-Like Protein from Medaka (Oryzias latipes) Controls the Formation of Calcium Carbonate Crystals

PubMed Central

Różycka, Mirosława; Wojtas, Magdalena; Jakób, Michał; Stigloher, Christian; Grzeszkowiak, Mikołaj; Mazur, Maciej; Ożyhar, Andrzej

2014-01-01

Fish otoliths, biominerals composed of calcium carbonate with a small amount of organic matrix, are involved in the functioning of the inner ear. Starmaker (Stm) from zebrafish (Danio rerio) was the first protein found to be capable of controlling the formation of otoliths. Recently, a gene was identified encoding the Starmaker-like (Stm-l) protein from medaka (Oryzias latipes), a putative homologue of Stm and human dentine sialophosphoprotein. Although there is no sequence similarity between Stm-l and Stm, Stm-l was suggested to be involved in the biomineralization of otoliths, as had been observed for Stm even before. The molecular properties and functioning of Stm-l as a putative regulatory protein in otolith formation have not been characterized yet. A comprehensive biochemical and biophysical analysis of recombinant Stm-l, along with in silico examinations, indicated that Stm-l exhibits properties of a coil-like intrinsically disordered protein. Stm-l possesses an elongated and pliable structure that is able to adopt a more ordered and rigid conformation under the influence of different factors. An in vitro assay of the biomineralization activity of Stm-l indicated that Stm-l affected the size, shape and number of calcium carbonate crystals. The functional significance of intrinsically disordered properties of Stm-l and the possible role of this protein in controlling the formation of calcium carbonate crystals is discussed. PMID:25490041

Linking the climatic and geochemical controls on global soil carbon cycling

NASA Astrophysics Data System (ADS)

Doetterl, Sebastian; Stevens, Antoine; Six, Johan; Merckx, Roel; Van Oost, Kristof; Casanova Pinto, Manuel; Casanova-Katny, Angélica; Muñoz, Cristina; Boudin, Mathieu; Zagal Venegas, Erick; Boeckx, Pascal

2015-04-01

Climatic and geochemical parameters are regarded as the primary controls for soil organic carbon (SOC) storage and turnover. However, due to the difference in scale between climate and geochemical-related soil research, the interaction of these key factors for SOC dynamics have rarely been assessed. Across a large geochemical and climatic transect in similar biomes in Chile and the Antarctic Peninsula we show how abiotic geochemical soil features describing soil mineralogy and weathering pose a direct control on SOC stocks, concentration and turnover and are central to explaining soil C dynamics at larger scales. Precipitation and temperature had an only indirect control by regulating geochemistry. Soils with high SOC content have low specific potential CO2 respiration rates, but a large fraction of SOC that is stabilized via organo-mineral interactions. The opposite was observed for soils with low SOC content. The observed differences for topsoil SOC stocks along this transect of similar biomes but differing geo-climatic site conditions are of the same magnitude as differences observed for topsoil SOC stocks across all major global biomes. Using precipitation and a set of abiotic geochemical parameters describing soil mineralogy and weathering status led to predictions of high accuracy (R2 0.53-0.94) for different C response variables. Partial correlation analyses revealed that the strength of the correlation between climatic predictors and SOC response variables decreased by 51 - 83% when controlling for geochemical predictors. In contrast, controlling for climatic variables did not result in a strong decrease in the strength of the correlations of between most geochemical variables and SOC response variables. In summary, geochemical parameters describing soil mineralogy and weathering were found to be essential for accurate predictions of SOC stocks and potential CO2 respiration, while climatic factors were of minor importance as a direct control, but are

[Spatial-temporal distributions of dissolved inorganic carbon and its affecting factors in the Yellow River estuary].

PubMed

Guo, Xing-Sen; Lü, Ying-Chun; Sun, Zhi-Gao; Wang, Chuan-Yuan; Zhao, Quan-Sheng

2015-02-01

Estuary is an important area contributing to the global carbon cycle. In order to analyze the spatial-temporal distribution characteristics of the dissolved inorganic carbon (DIC) in the surface water of Yellow River estuary. Samples were collected in spring, summer, fall, winter of 2013, and discussed the correlation between the content of DIC and environmental factors. The results show that, the DIC concentration of the surface water in Yellow River estuary is in a range of 26.34-39.43 mg x L(-1), and the DIC concentration in freshwater side is higher than that in the sea side. In some areas where the salinity is less than 15 per thousand, the DIC concentration appears significant losses-the maximum loss is 20.46%. Seasonal distribution of performance in descending order is spring, fall, winter, summer. Through principal component analysis, it shows that water temperature, suspended solids, salinity and chlorophyll a are the main factors affecting the variation of the DIC concentration in surface water, their contribution rate is as high as 83% , and alkalinity, pH, dissolved organic carbon, dissolved oxygen and other factors can not be ignored. The loss of DIC in the low area is due to the calcium carbonate sedimentation. DIC presents a gradually increasing trend, which is mainly due to the effects of water retention time, temperature, outside input and environmental conditions.

Preventing childhood obesity by reducing consumption of carbonated drinks: cluster randomised controlled trial

PubMed Central

James, Janet; Thomas, Peter; Cavan, David; Kerr, David

2004-01-01

Objective To determine if a school based educational programme aimed at reducing consumption of carbonated drinks can prevent excessive weight gain in children. Design Cluster randomised controlled trial. Setting Six primary schools in southwest England. Participants 644 children aged 7-11 years. Intervention Focused educational programme on nutrition over one school year. Main outcome measures Drink consumption and number of overweight and obese children. Results Consumption of carbonated drinks over three days decreased by 0.6 glasses (average glass size 250 ml) in the intervention group but increased by 0.2 glasses in the control group (mean difference 0.7, 95% confidence interval 0.1 to 1.3). At 12 months the percentage of overweight and obese children increased in the control group by 7.5%, compared with a decrease in the intervention group of 0.2% (mean difference 7.7%, 2.2% to 13.1%). Conclusion A targeted, school based education programme produced a modest reduction in the number of carbonated drinks consumed, which was associated with a reduction in the number of overweight and obese children. PMID:15107313

Synergistic Impacts of Electrolyte Adsorption on the Thermoelectric Properties of Single-Walled Carbon Nanotubes.

PubMed

Nakano, Motohiro; Nakashima, Takuya; Kawai, Tsuyoshi; Nonoguchi, Yoshiyuki

2017-08-01

Single-walled carbon nanotubes are promising candidates for light-weight and flexible energy materials. Recently, the thermoelectric properties of single-walled carbon nanotubes have been dramatically improved by ionic liquid addition; however, controlling factors remain unsolved. Here the thermoelectric properties of single-walled carbon nanotubes enhanced by electrolytes are investigated. Complementary characterization with absorption, Raman, and X-ray photoelectron spectroscopy reveals that shallow hole doping plays a partial role in the enhanced electrical conductivity. The molecular factors controlling the thermoelectric properties of carbon nanotubes are systematically investigated in terms of the ionic functionalities of ionic liquids. It is revealed that appropriate ionic liquids show a synergistic enhancement in conductivity and the Seebeck coefficient. The discovery of significantly precise doping enables the generation of thermoelectric power factor exceeding 460 µW m - 1 K -2 . © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Controllable synthesis of mesoporous carbon nanospheres and Fe-N/carbon nanospheres as efficient oxygen reduction electrocatalysts.

PubMed

Wei, Jing; Liang, Yan; Zhang, Xinyi; Simon, George P; Zhao, Dongyuan; Zhang, Jin; Jiang, Sanping; Wang, Huanting

2015-04-14

The synthesis of mesoporous carbon nanospheres (MCNs), especially with diameters below 200 nm remains a great challenge due to weak interactions between the carbon precursors and soft templates, as well as the uncontrollable cross-linking rate of carbon precursors. Herein, we demonstrate a simple acid-assisted, hydrothermal synthesis approach to synthesizing such uniform MCNs with well controlled diameters ranging from 20 to 150 nm under highly acidic conditions (2 M HCl). Both the carbon precursor and the template are partly protonated under such conditions and show additional Coulombic interactions with chloride ions (acts as mediators). This kind of enhanced interaction is similar to that of the "I(+)X(-)S(+)" mechanism in the synthesis of mesoporous metal oxide, which can effectively retard the cross-linking rate of resol molecules and avoid macroscopic phase separation during the hydrothermal synthesis. Due to their uniform spherical morphology, small diameter, and high surface areas, MCNs can be modified with Fe and N species via impregnation of cheap precursors (ferric nitrate and dicyandiamide), which are further converted into nonprecious electrocatalysts for oxygen reduction reactions. The resulting Fe-N/MCNs exhibit high catalytic activities, long-term stability and improved methanol tolerance under alkaline conditions, which can be potentially used in direct methanol fuel cells and metal-air batteries.

Amounts, isotopic character, and ages of organic and inorganic carbon exported from rivers to ocean margins: 2. Assessment of natural and anthropogenic controls

NASA Astrophysics Data System (ADS)

Hossler, Katie; Bauer, James E.

2013-04-01

Riverine exports of carbon (C) and organic matter (OM) are regulated by a variety of natural and anthropogenic factors. Understanding the relationships between these various factors and C and OM exports can help to constrain global C budgets and allow assessment of current and future anthropogenic impacts on both riverine and global C cycles. We quantified the effects of multiple natural and anthropogenic controls on riverine export fluxes and compositions of particulate organic C, dissolved organic C, and dissolved inorganic C for a regional group of eight rivers in the northeastern U.S. Potential controls related to hydrogeomorphology and regional climate, soil order, soil texture, bedrock lithology, land use, and anthropogenic factors were analyzed individually, collectively, and at scales of both local and regional influence. Factors related to hydrogeomorphology and climate, followed in importance by land use and anthropogenic factors, exhibited the strongest impacts on riverine C exports and compositions, particularly at smaller localized scales. The effects of hydrogeomorphology and climate were primarily related to volumetric flow, which resulted in greater exports of terrestrial and total C. Principal anthropogenic factors included impacts of wastewater treatment plants (WWTPs) and river impoundments. The presence of WWTPs as well as anthropogenic use of carbonate-based materials (e.g., limestone) may have substantially increased riverine C exports, particularly fossil C exports, in the study region. The presence of nuclear power plants in the associated watersheds is also discussed because of the potential for anthropogenic 14C inputs and subsequent biasing of aquatic C studies utilizing natural abundance 14C.

Climatic and topographical factors affecting the vegetative carbon stock of rangelands in arid and semiarid regions of China

USGS Publications Warehouse

Zhengchao, Ren; Huazhong, Zhu; Shi, Hua; Xiaoni, Liu

2016-01-01

Rangeland systems play an important role in ecological stabilization and the terrestrial carbon cycle in arid and semiarid regions. However, little is known about the vegetative carbon dynamics and climatic and topographical factors that affect vegetative carbon stock in these rangelands. Our goal was to assess vegetative carbon stock by examining meteorological data in conjunction with NDVI (normalized difference vegetation index) time series datasets from 2001–2012. An improved CASA (Carnegie Ames Stanford Approach) model was then applied to simulate the spatiotemporal dynamic variation of vegetative carbon stock, and analyze its response to climatic and topographical factors. We estimated the vegetative carbon stock of rangeland in Gansu province, China to be 4.4× 1014 gC, increasing linearly at an annual rate of 9.8×1011 gC. The mean vegetative carbon density of the whole rangeland was 136.5 gC m-2. Vegetative carbon density and total carbon varied temporally and spatially and were highly associated with temperature, precipitation and solar radiation. Vegetative carbon density reached the maximal value on elevation at 2500–3500 m, a slope of >30°and easterly aspect. The effect of precipitation, temperature and solar radiation on the vegetative carbon density of five rangeland types (desert and salinized meadow, steppe, alpine meadow, shrub and tussock, and marginal grassland in the forest) depends on the acquired quantity of water and heat for rangeland plants at all spatial scales. The results of this study provide new evidence for explaining spatiotemporal heterogeneity in vegetative carbon dynamics and responses to global change for rangeland vegetative carbon stock, and offer a theoretical and practical basis for grassland agriculture management in arid and semiarid regions.

Optimal boiler control through real-time monitoring of unburned carbon in fly ash by laser-induced breakdown spectroscopy.

PubMed

Kurihara, Miki; Ikeda, Koji; Izawa, Yoshinori; Deguchi, Yoshihiro; Tarui, Hitoshi

2003-10-20

A laser-induced breakdown spectroscopy (LIBS) technique has been applied for detection of unburned carbon in fly ash, and an automated LIBS unit has been developed and applied in a 1000-MW pulverized-coal-fired power plant for real-time measurement, specifically of unburned carbon in fly ash. Good agreement was found between measurement results from the LIBS method and those from the conventional method (Japanese Industrial Standard 8815), with a standard deviation of 0.27%. This result confirms that the measurement of unburned carbon in fly ash by use of LIBS is sufficiently accurate for boiler control. Measurements taken by this apparatus were also integrated into a boiler-control system with the objective of achieving optimal and stable combustion. By control of the rotating speed of a mill rotary separator relative to measured unburned-carbon content, it has been demonstrated that boiler control is possible in an optimized manner by use of the value of the unburned-carbon content of fly ash.

Federal Control of Geological Carbon Sequestration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reitze, Arnold W.

The United States has economically recoverable coal reserves of about 261 billion tons, which is in excess of a 250-­year supply based on 2009 consumption rates. However, in the near future the use of coal may be legally restricted because of concerns over the effects of its combustion on atmospheric carbon dioxide concentrations. In response, the U.S. Department of Energy is making significant efforts to help develop and implement a commercial scale program of geologic carbon sequestration that involves capturing and storing carbon dioxide emitted from coal-burning electric power plants in deep underground formations. This article explores the technical andmore » legal problems that must be resolved in order to have a viable carbon sequestration program. It covers the responsibilities of the United States Environmental Protection Agency and the Departments of Energy, Transportation and Interior. It discusses the use of the Safe Drinking Water Act, the Clean Air Act, the National Environmental Policy Act, the Endangered Species Act, and other applicable federal laws. Finally, it discusses the provisions related to carbon sequestration that have been included in the major bills dealing with climate change that Congress has been considering in 2009 and 2010. The article concludes that the many legal issues that exist can be resolved, but whether carbon sequestration becomes a commercial reality will depend on reducing its costs or by imposing legal requirements on fossil-fired power plants that result in the costs of carbon emissions increasing to the point that carbon sequestration becomes a feasible option.« less

Stored Carbon Dynamics are Controlled by a Combination of Evolutionary, Physiological, and Ecological Pressures

NASA Astrophysics Data System (ADS)

Aubrey, D. P.; Mims, J. T.; Oswald, S. W.; Teskey, R. O.; Mitchell, R. J.

2016-12-01

Allocation of assimilated carbon to storage provides a critical carbohydrate buffer when metabolic demands exceed current photosynthetic supply; however, our process-level understanding of controls on carbon storage pools and fluxes remains relatively poor. Recent studies have shifted the paradigm from the concept that stored carbon pools are a sink of low priority that accumulate passively when photosynthetic inputs exceed demand toward the concept that these pools are active sinks of high priority. It follows that allocation toward storage—at the expense of growth—is a trait that would be under selective pressure since species that allocate toward storage should be more resilient to disturbance. Using fire-dependent longleaf pine in a series of manipulative and observational studies, we explore how stored carbon dynamics are controlled by a combination of evolutionary, physiological, and ecological pressures. Our manipulative studies revealed large stored carbon pools in roots that maintained belowground metabolism for a year after current photosynthetic supply was restricted. Likewise, the concentration of stored carbon in the smallest, most metabolically active roots was not influenced until nearly one year later. Our observational studies indicated that stored carbon pools differ among closely related species with overlapping natural distributions, but evolutionary histories of different disturbance frequencies and thus, different selective pressures on carbon storage. Our comparisons of stored carbon pools between longleaf trees growing under xeric or mesic soil moisture regimes indicated that allocation toward storage exhibits plasticity through space and time in response to both short- and long-term variations in resource availability. We expect a continuum of responses to disturbances related to ecological niche and evolutionary adaptation that influence the availability of carbohydrates for metabolic demands. We also expect a continuum in stored

Amounts, isotopic character and ages of organic and inorganic carbon exported from rivers to ocean margins: Assessment of natural and anthropogenic controls

NASA Astrophysics Data System (ADS)

Bauer, J. E.; Hossler, K.

2012-12-01

Riverine exports of carbon (C) and organic matter (OM) are regulated by a variety of natural and anthropogenic factors. Understanding the relationships between these various factors and C and OM exports can help to constrain global C budgets, as well allow assessment of current and future anthropogenic impacts on both riverine and global C cycles. We quantified the effects of multiple natural and anthropogenic controls on riverine export fluxes and compositions of particulate organic C (POC), dissolved organic C (DOC), and dissolved inorganic C (DIC) for a regional group of eight rivers in the northeastern U.S. For allochthonous and aged C contributions to POC, DOC and DIC exports, we first estimated fractional contributions from six potential sources for POC and DOC (i.e., modern C3 plant material (C3-OC), modern C4 plant material (C4-OC), modern algal material (algal OC), slow-turnover soil OC (slow SOC; turnover time 25 yr), passive-turnover soil OC (passive SOC; turnover time 5,000 yr) and fossil OC and four potential sources for DIC (i.e., modern atmospheric CO2 exchange, carbonate dissolution, POC remineralization and DOC remineralization) using a novel time-varying isotope mixing model. Using these estimated source contributions, we then estimated the allochthonous proportions of (a) the POC and DOC pools to be the C3-OC, C4-OC, slow SOC, passive SOC, and fossil OC contributions; and (b) the DIC pools to be the dissolved carbonates, remineralized allochthonous POC, and remineralized allochthonous DOC contributions. We considered aged C to be anything older than ˜ 60 yr, which included passive SOC and fossil OC for POC and DOC and dissolved carbonates and aged fractions of remineralized POC and DOC for DIC. Potential controls related to hydrogeomorphology and regional climate, soil order, soil texture, bedrock lithology, land use, and additional anthropogenic factors were analyzed collectively, individually, and at scales of both local and regional influence

Multilayer regulatory mechanisms control cleavage factor I proteins in filamentous fungi

PubMed Central

Rodríguez-Romero, J.; Franceschetti, M.; Bueno, E.; Sesma, A.

2015-01-01

Cleavage factor I (CFI) proteins are core components of the polyadenylation machinery that can regulate several steps of mRNA life cycle, including alternative polyadenylation, splicing, export and decay. Here, we describe the regulatory mechanisms that control two fungal CFI protein classes in Magnaporthe oryzae: Rbp35/CfI25 complex and Hrp1. Using mutational, genetic and biochemical studies we demonstrate that cellular concentration of CFI mRNAs is a limited indicator of their protein abundance. Our results suggest that several post-transcriptional mechanisms regulate Rbp35/CfI25 complex and Hrp1 in the rice blast fungus, some of which are also conserved in other ascomycetes. With respect to Rbp35, these include C-terminal processing, RGG-dependent localization and cleavage, C-terminal autoregulatory domain and regulation by an upstream open reading frame of Rbp35-dependent TOR signalling pathway. Our proteomic analyses suggest that Rbp35 regulates the levels of proteins involved in melanin and phenylpropanoids synthesis, among others. The drastic reduction of fungal CFI proteins in carbon-starved cells suggests that the pre-mRNA processing pathway is altered. Our findings uncover broad and multilayer regulatory mechanisms controlling fungal polyadenylation factors, which have profound implications in pre-mRNA maturation. This area of research offers new avenues for fungicide design by targeting fungal-specific proteins that globally affect thousands of mRNAs. PMID:25514925

Disentangling the control of tectonics, eustasy, trophic conditions and climate on shallow-marine carbonate production during the Aalenian-Oxfordian interval: From the western France platform to the western Tethyan domain

NASA Astrophysics Data System (ADS)

Andrieu, Simon; Brigaud, Benjamin; Barbarand, Jocelyn; Lasseur, Eric; Saucède, Thomas

2016-11-01

The objective of this work is to improve our understanding of the processes controlling changes in the architecture and facies of intracontinental carbonate platforms. We examined the facies and sequence stratigraphy of Aalenian to Oxfordian limestones of western France. Seventy-seven outcrop sections were studied and thirty-one sedimentary facies identified in five depositional environments ranging from lower offshore to backshore. Platform evolution was reconstructed along a 500 km cross-section. Twenty-two depositional sequences were identified on the entire western France platform and correlated with European third-order sequences at the biozone level, demonstrating that eustasy was the major factor controlling the cyclic trend of accommodation. The tectonic subsidence rate was computed from accommodation measurements from the Aalenian to the Oxfordian in key localities. Tectonism controlled the sedimentation rate and platform architecture at a longer time scale. Tectonic subsidence triggered the demise of carbonate production at the Bathonian/Callovian boundary while the uplift made possible the recovery of carbonate platform from Caen to Le Mans during the mid Oxfordian. Topography of the Paleozoic basement mainly controlled lateral variations of paleodepth within the western France platform until the mid Bathonian. A synthesis of carbonate production in the western Tethyan domain at that time was conducted. Stages of high carbonate production during the Bajocian/Bathonian and the middle to late Oxfordian are synchronous with low δ13C, high eccentricity intervals, and rather dry climate promoting (1) evaporation and carbonate supersaturation, and (2) oligotrophic conditions. Periods of low carbonate production during the Aalenian and from the middle Callovian to early Oxfordian correlate with high δ13C and low eccentricity intervals, characterized by wet climate and less oligotrophic conditions. Such conditions tend to diminish growth potential of carbonate

Spatially controlled carbon sponge for targeting internalized radioactive materials in human body.

PubMed

Hong, Jin-Yong; Oh, Wan-Kyu; Shin, Keun-Young; Kwon, Oh Seok; Son, Suim; Jang, Jyongsik

2012-07-01

Carbon sponge, an adsorbent with spatially controlled structure is demonstrated for targeting internalized radiocesium and other radionuclides in human body. Three dimensionally ordered macroporous (3DOM) carbons derived from inverse opal replicas of colloidal-crystal template exhibit large surface area and high porosity, resulting in highly efficient adsorbents for radionuclides. It is also possible to enhance binding affinity and selectivity to radionuclide targets by decoration of 3DOM carbon surfaces with Prussian blue (PB) nanoparticles, and synthesized PB nanoparticles reveal low toxicity toward macrophage cells with potential advantages over oral administration. It is noteworthy that the maximum (133)Cs adsorption capacity of PB-decorated 3DOM carbons is 40.07 mmol g(-1) which is ca. 30 and 200 times higher than that of commercialized medicine Radiogardase(®) and bulk PB, respectively. Further, adsorption kinetics study indicates that the PB-decorated 3DOM carbons have the homogenous surface for (133)Cs ion adsorption and all sites have equal adsorption energies in terms of ion exchange between the cyano groups of the PB-decorated 3DOM carbons and radionuclides. As a concept of the oral-administrable "carbon sponge", the PB-decorated 3DOM carbons offer useful implications in the separation science of radioactive materials and important insight for designing novel materials for treatment of patients or suspected internal contamination with radioactive materials. Copyright © 2012 Elsevier Ltd. All rights reserved.

40 CFR Table N-1 to Subpart N of... - CO2 Emission Factors for Carbonate-Based Raw Materials

Code of Federal Regulations, 2014 CFR

2014-07-01

... Raw Materials Carbonate-basedraw material—mineral CO2 emission factor a Limestone—CaCO3 0.440 Dolomite—CaMg(CO3)2 0.477 Sodium carbonate/soda ash—Na2CO3 0.415 Barium carbonate—BaCO3 0.223 Potassium...

40 CFR Table N-1 to Subpart N of... - CO2 Emission Factors for Carbonate-Based Raw Materials

Code of Federal Regulations, 2012 CFR

2012-07-01

... Raw Materials Carbonate-basedraw material—mineral CO2 emission factor a Limestone—CaCO3 0.440 Dolomite—CaMg(CO3)2 0.477 Sodium carbonate/soda ash—Na2CO3 0.415 Barium carbonate—BaCO3 0.223 Potassium...

40 CFR Table N-1 to Subpart N of... - CO2 Emission Factors for Carbonate-Based Raw Materials

Code of Federal Regulations, 2013 CFR

2013-07-01

... Raw Materials Carbonate-basedraw material—mineral CO2 emission factor a Limestone—CaCO3 0.440 Dolomite—CaMg(CO3)2 0.477 Sodium carbonate/soda ash—Na2CO3 0.415 Barium carbonate—BaCO3 0.223 Potassium...

Oxidation of Carbon/Carbon through Coating Cracks

NASA Technical Reports Server (NTRS)

Jacobson, N. S.; Roth, d. J.; Rauser, R. W.; Cawley, J. D.; Curry, D. M.

2008-01-01

Reinforced carbon/carbon (RCC) is used to protect the wing leading edge and nose cap of the Space Shuttle Orbiter on re-entry. It is composed of a lay-up of carbon/carbon fabric protected by a SiC conversion coating. Due to the thermal expansion mismatch of the carbon/carbon and the SiC, the SiC cracks on cool-down from the processing temperature. The cracks act as pathways for oxidation of the carbon/carbon. A model for the diffusion controlled oxidation of carbon/carbon through machined slots and cracks is developed and compared to laboratory experiments. A symmetric cylindrical oxidation cavity develops under the slots, confirming diffusion control. Comparison of cross sectional dimensions as a function of oxidation time shows good agreement with the model. A second set of oxidation experiments was done with samples with only the natural craze cracks, using weight loss as an index of oxidation. The agreement of these rates with the model is quite reasonab

Rapid and controllable perforation of carbon nanotubes by microwave radiation

NASA Astrophysics Data System (ADS)

Ojaghi, Neda; Mokhtarifar, Maryam; Sabaghian, Zahra; Arab, Hamed; Maghrebi, Morteza; Baniadam, Majid

2018-05-01

This study presents a new controlled approach to deep perforation of millimeter-long carbon nanotube arrays (CNTAs) by fast oxidative cutting. The approach is based on decorating CNTAs with silver (Ag) nanoparticles, followed by heating Ag-decorated CNTAs with microwave radiation (2.48 GHz, 300 W). The perforation was evaluated using different techniques such as transmission electron microscopy, X-ray photoelectron spectroscopy, and Brunauer-Emmett-Teller method. The results of the oxidation of carbonaceous materials indicated that the relative amount of oxygen functional groups increased without total oxidation of carbon up to 60 s. After 60 s, the amount of functional groups decreased as the total oxidation started suddenly. Afterwards, at around 120 and 420 s, the oxidation of Ag-decorated CNTAs reached the point of total perforation and total cutting, respectively. Though carbon decomposition terminated at around 420 s, the total pore volume and surface area increased continuously. This was attributed to the steady growth of Ag nanoparticles located between CNTAs.

Chemical control of electrical contact to sp² carbon atoms.

PubMed

Frederiksen, Thomas; Foti, Giuseppe; Scheurer, Fabrice; Speisser, Virginie; Schull, Guillaume

2014-04-16

Carbon-based nanostructures are attracting tremendous interest as components in ultrafast electronics and optoelectronics. The electrical interfaces to these structures play a crucial role for the electron transport, but the lack of control at the atomic scale can hamper device functionality and integration into operating circuitry. Here we study a prototype carbon-based molecular junction consisting of a single C60 molecule and probe how the electric current through the junction depends on the chemical nature of the foremost electrode atom in contact with the molecule. We find that the efficiency of charge injection to a C60 molecule varies substantially for the considered metallic species, and demonstrate that the relative strength of the metal-C bond can be extracted from our transport measurements. Our study further suggests that a single-C60 junction is a basic model to explore the properties of electrical contacts to meso- and macroscopic sp(2) carbon structures.

Chemical control of electrical contact to sp2 carbon atoms

NASA Astrophysics Data System (ADS)

Frederiksen, Thomas; Foti, Giuseppe; Scheurer, Fabrice; Speisser, Virginie; Schull, Guillaume

2014-04-01

Carbon-based nanostructures are attracting tremendous interest as components in ultrafast electronics and optoelectronics. The electrical interfaces to these structures play a crucial role for the electron transport, but the lack of control at the atomic scale can hamper device functionality and integration into operating circuitry. Here we study a prototype carbon-based molecular junction consisting of a single C60 molecule and probe how the electric current through the junction depends on the chemical nature of the foremost electrode atom in contact with the molecule. We find that the efficiency of charge injection to a C60 molecule varies substantially for the considered metallic species, and demonstrate that the relative strength of the metal-C bond can be extracted from our transport measurements. Our study further suggests that a single-C60 junction is a basic model to explore the properties of electrical contacts to meso- and macroscopic sp2 carbon structures.

Patterns and controls of inter-annual variability in the terrestrial carbon budget

NASA Astrophysics Data System (ADS)

Marcolla, Barbara; Rödenbeck, Christian; Cescatti, Alessandro

2017-08-01

The terrestrial carbon fluxes show the largest variability among the components of the global carbon cycle and drive most of the temporal variations in the growth rate of atmospheric CO2. Understanding the environmental controls and trends of the terrestrial carbon budget is therefore essential to predict the future trajectories of the CO2 airborne fraction and atmospheric concentrations. In the present work, patterns and controls of the inter-annual variability (IAV) of carbon net ecosystem exchange (NEE) have been analysed using three different data streams: ecosystem-level observations from the FLUXNET database (La Thuile and 2015 releases), the MPI-MTE (model tree ensemble) bottom-up product resulting from the global upscaling of site-level fluxes, and the Jena CarboScope Inversion, a top-down estimate of surface fluxes obtained from observed CO2 concentrations and an atmospheric transport model. Consistencies and discrepancies in the temporal and spatial patterns and in the climatic and physiological controls of IAV were investigated between the three data sources. Results show that the global average of IAV at FLUXNET sites, quantified as the standard deviation of annual NEE, peaks in arid ecosystems and amounts to ˜ 120 gC m-2 y-1, almost 6 times more than the values calculated from the two global products (15 and 20 gC m-2 y-1 for MPI-MTE and the Jena Inversion, respectively). Most of the temporal variability observed in the last three decades of the MPI-MTE and Jena Inversion products is due to yearly anomalies, whereas the temporal trends explain only about 15 and 20 % of the variability, respectively. Both at the site level and on a global scale, the IAV of NEE is driven by the gross primary productivity and in particular by the cumulative carbon flux during the months when land acts as a sink. Altogether these results offer a broad view on the magnitude, spatial patterns and environmental drivers of IAV from a variety of data sources that can be

Revised methane emissions factors and spatially distributed annual carbon fluxes for global livestock

USDA-ARS?s Scientific Manuscript database

Livestock play an important role in carbon cycling through consumption of biomass and emissions of methane. Recent research suggests that existing bottom-up inventories of livestock methane emissions in the U.S., such as those made using 2006 IPCC Tier 1 livestock emissions factors, are too low. Thi...

The Response of Heterotrophic Prokaryote and Viral Communities to Labile Organic Carbon Inputs Is Controlled by the Predator Food Chain Structure.

PubMed

Sandaa, Ruth-Anne; Pree, Bernadette; Larsen, Aud; Våge, Selina; Töpper, Birte; Töpper, Joachim P; Thyrhaug, Runar; Thingstad, Tron Frede

2017-08-23

Factors controlling the community composition of marine heterotrophic prokaryotes include organic-C, mineral nutrients, predation, and viral lysis. Two mesocosm experiments, performed at an Arctic location and bottom-up manipulated with organic-C, had very different results in community composition for both prokaryotes and viruses. Previously, we showed how a simple mathematical model could reproduce food web level dynamics observed in these mesocosms, demonstrating strong top-down control through the predator chain from copepods via ciliates and heterotrophic nanoflagellates. Here, we use a steady-state analysis to connect ciliate biomass to bacterial carbon demand. This gives a coupling of top-down and bottom-up factors whereby low initial densities of ciliates are associated with mineral nutrient-limited heterotrophic prokaryotes that do not respond to external supply of labile organic-C. In contrast, high initial densities of ciliates give carbon-limited growth and high responsiveness to organic-C. The differences observed in ciliate abundance, and in prokaryote abundance and community composition in the two experiments were in accordance with these predictions. Responsiveness in the viral community followed a pattern similar to that of prokaryotes. Our study provides a unique link between the structure of the predator chain in the microbial food web and viral abundance and diversity.

Development Requirements for the Exploration PLSS (xPLSS) Carbon Dioxide and Humidity Control Unit (CDHCU)

NASA Technical Reports Server (NTRS)

Chullen, Cinda

2017-01-01

Functional Requirements for the Carbon Dioxide and Humidity Control Unit (CDHCU): The CDHCU is a component of the Exploration Portable Life Support System (xPLSS) to provide carbon dioxide (CO2) and humidity control within the spacesuit for a crewmember to perform extravehicular activities (EVA) in vacuum (micro-g), lunar, and Mars environments for up to 8 hours continuous, and during EVA preparation in airlocks or support vehicles for an additional 2 hours (TBR) continuous.

Carbonic acid salts at 25 or 45 degrees C to control loquat decay under shelf life conditions.

PubMed

Molinu, M G; D'Hallewin, G; Dore, A; Serusi, A; Venditti, T; Agabbio, M

2005-01-01

Generally recognised as save compounds (G.R.A.S) are attractive substitutes to synthetic chemicals in postharvest control diseases. They meet safety requirements, are cheap and able to be integrated with other disease control technologies. Among G.R.A.S compounds, carbonic acid salts have been investigated on carrots, bell pepper, melons, sweet cherries and their efficacy was also evaluated when combined with biological control agents. Moreover, the possibility to use sodium carbonate and sodium bicarbonate to prevent P. digitatum an P. italicum spread on Citrus fruit was studied since the begin of the 20th century. We explored the possibility to extend the use of carbonate-bicarbonate salts on loquat fruit in order to control the pathogens and to extend postharvest life. Loquat is a very perishable fruit, susceptible to decay, mechanical damage, moisture and nutritional losses during its postharvest life. We tested the combined effect of temperature and sodium or potassium carbonate-bicarbonate and ammonium carbonate. The fruit was dipped in the salt solutions at variable concentrations (0.5, 1 and 2% w/v) at 25 or 45 degrees C for two minutes and than stored under shelf life conditions (25 degrees C and 70% RH). Decay, weight loss, pH, titrable acidity and sugar content were detected after twelve days. Preliminary data show that the combined treatments were effective in decay control depending on salts. Best results were obtained with 2% potassium and sodium carbonate solution at 25 degrees C. Weight losses were related to treatment temperature and salts concentrations whereas, no differences were detected in the chemical parameters compared to the control.

Climatic and biotic controls on annual carbon storage in Amazonian ecosystems

USGS Publications Warehouse

Tian, H.; Melillo, J.M.; Kicklighter, D.W.; McGuire, A.D.; Helfrich, J.; Moore, B.; Vorosmarty, C.J.

2000-01-01

1 The role of undisturbed tropical land ecosystems in the global carbon budget is not well understood. It has been suggested that inter-annual climate variability can affect the capacity of these ecosystems to store carbon in the short term. In this paper, we use a transient version of the Terrestrial Ecosystem Model (TEM) to estimate annual carbon storage in undisturbed Amazonian ecosystems during the period 1980-94, and to understand the underlying causes of the year-to-year variations in net carbon storage for this region. 2 We estimate that the total carbon storage in the undisturbed ecosystems of the Amazon Basin in 1980 was 127.6 Pg C, with about 94.3 Pg C in vegetation and 33.3 Pg C in the reactive pool of soil organic carbon. About 83% of the total carbon storage occurred in tropical evergreen forests. Based on our model's results, we estimate that, over the past 15 years, the total carbon storage has increased by 3.1 Pg C (+ 2%), with a 1.9-Pg C (+2%) increase in vegetation carbon and a 1.2-Pg C (+4%) increase in reactive soil organic carbon. The modelled results indicate that the largest relative changes in net carbon storage have occurred in tropical deciduous forests, but that the largest absolute changes in net carbon storage have occurred in the moist and wet forests of the Basin. 3 Our results show that the strength of interannual variations in net carbon storage of undisturbed ecosystems in the Amazon Basin varies from a carbon source of 0.2 Pg C/year to a carbon sink of 0.7 Pg C/year. Precipitation, especially the amount received during the drier months, appears to be a major controller of annual net carbon storage in the Amazon Basin. Our analysis indicates further that changes in precipitation combine with changes in temperature to affect net carbon storage through influencing soil moisture and nutrient availability. 4 On average, our results suggest that the undisturbed Amazonian ecosystems accumulated 0.2 Pg C/year as a result of climate

Soil Carbon Storage in Christmas Tree Farms: Maximizing Ecosystem Management and Sustainability for Carbon Sequestration

NASA Astrophysics Data System (ADS)

Chapman, S. K.; Shaw, R.; Langley, A.

2008-12-01

Management of agroecosystems for the purpose of manipulating soil carbon stocks could be a viable approach for countering rising atmospheric carbon dioxide concentrations, while maximizing sustainability of the agroforestry industry. We investigated the carbon storage potential of Christmas tree farms in the southern Appalachian mountains as a potential model for the impacts of land management on soil carbon. We quantified soil carbon stocks across a gradient of cultivation duration and herbicide management. We compared soil carbon in farms to that in adjacent pastures and native forests that represent a control group to account for variability in other soil-forming factors. We partitioned tree farm soil carbon into fractions delineated by stability, an important determinant of long-term sequestration potential. Soil carbon stocks in the intermediate pool are significantly greater in the tree farms under cultivation for longer periods of time than in the younger tree farms. This pool can be quite large, yet has the ability to repond to biological environmental changes on the centennial time scale. Pasture soil carbon was significantly greater than both forest and tree farm soil carbon, which were not different from each other. These data can help inform land management and soil carbon sequestration strategies.

Factors Influencing NO2 Adsorption/Reduction on Microporous Activated Carbon: Porosity vs. Surface Chemistry

PubMed Central

Ghouma, Imen; Limousy, Lionel; Bennici, Simona

2018-01-01

The textural properties and surface chemistry of different activated carbons, prepared by the chemical activation of olive stones, have been investigated in order to gain insight on the NO2 adsorption mechanism. The parent chemical activated carbon was prepared by the impregnation of olive stones in phosphoric acid followed by thermal carbonization. Then, the textural properties and surface chemistry were modified by chemical treatments including nitric acid, sodium hydroxide and/or a thermal treatment at 900 °C. The main properties of the parent and modified activated carbons were analyzed by N2-adsorption, scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR) techniques, in order to enlighten the modifications issued from the chemical and thermal treatments. The NO2 adsorption capacities of the different activated carbons were measured in fixed bed experiments under 500 ppmv NO2 concentrations at room temperature. Temperature programmed desorption (TPD) was applied after adsorption tests in order to quantify the amount of the physisorbed and chemisorbed NO2. The obtained results showed that the development of microporosity, the presence of oxygen-free sites, and the presence of basic surface groups are key factors for the efficient adsorption of NO2. PMID:29670008

Shaping carbon nanostructures by controlling the synthesis process

NASA Astrophysics Data System (ADS)

Merkulov, Vladimir I.; Guillorn, Michael A.; Lowndes, Douglas H.; Simpson, Michael L.; Voelkl, Edgar

2001-08-01

The ability to control the nanoscale shape of nanostructures in a large-scale synthesis process is an essential and elusive goal of nanotechnology research. Here, we report significant progress toward that goal. We have developed a technique that enables controlled synthesis of nanoscale carbon structures with conical and cylinder-on-cone shapes and provides the capability to dynamically change the nanostructure shape during the synthesis process. In addition, we present a phenomenological model that explains the formation of these nanostructures and provides insight into methods for precisely engineering their shape. Since the growth process we report is highly deterministic in allowing large-scale synthesis of precisely engineered nanoscale components at defined locations, our approach provides an important tool for a practical nanotechnology.

Different controls on sedimentary organic carbon in the Bohai Sea: River mouth relocation, turbidity and eutrophication

NASA Astrophysics Data System (ADS)

Xu, Yunping; Zhou, Shangzhe; Hu, Limin; Wang, Yinghui; Xiao, Wenjie

2018-04-01

The extractable lipids and bulk organic geochemical parameters in three sediment cores (M-1, M-3 and M-7) from southern, central and northern Bohai Sea were analyzed in order to reconstruct environmental changes since 1900. The C/N ratio and multiple biomarkers (e.g., C27 + C29 + C31n-alkanes, C24 + C26 + C28n-alkanols, branched versus isoprenoid tetraether index) suggest more terrigenous organic carbon (OC) inputs in southern Bohai Sea. The abrupt changes of biomarker indicators in core M-1 are generally synchronous with the Yellow River mouth relocation events (e.g., 1964, 1976 and 1996), suggesting the distance to the river mouth being an important factor for sedimentary OC dispersal in the southern Bohai Sea. However, in cores M-3 and M-7, terrigenous biomarkers (i.e., BIT) show a long-term declining trend, consistent with a continuous reduction of the Yellow River sediment load, whereas marine biomarkers such as cholesterol, brassicasterol and dinosterol dramatically increased post-1980, apparently related to human-induced eutrophication in the Bohai Sea. Our study suggests different controlling factors on sedimentary OC distribution in the southern (high turbidity) and other parts (less turbidity) of the Bohai Sea, which should be considered for interpretation of paleoenvironments and biogeochemical processes in the river dominated margins that are hotspots of the global carbon cycling.

Hydrological controls on dissolved organic carbon production and release from UK peatlands

NASA Astrophysics Data System (ADS)

Fenner, Nathalie; Freeman, Chris; Worrall, Fred

Long-term increases in dissolved organic carbon (DOC) release from peatlands to British aquatic ecosystems are widely acknowledged, and are now confirmed to occur in a wide variety of boreal and subboreal settings. Depth to water table is probably the single most important hydrological factor governing that DOC generation and will modulate the response of the system to other environmental factors (such as warming and rising atmospheric carbon dioxide) in a changing climate. Many workers have attempted to attribute the rising DOC trend to a single "universal" driving variable. However, two fundamental problems prevent this: (1) universal theories, i.e., climate change theories that can account for rising trends in diverse catchment types, seem insufficient to account for the large observed increases, and (2) regional theories cannot account for the trend in all catchment types. Here it is suggested that multiple and possibly different drivers can modify DOC exports at four stages, namely, production, diffusion, solubility, and transport, with hydrology undoubtedly having a direct or indirect role in all the potential drivers considered here. These mechanisms, and the interactions between them, need to be more fully understood if we are to predict the response of the United Kingdom and global peatland carbon stores to environmental changes. Moreover, if we are to attempt to ameliorate rising DOC, we will need to fully appreciate the implications of restoration of drained peatlands and land management practices, to ensure that carbon losses are reduced on various temporal scales. These are research topics that remain in their infancy.

Decoding depositional sequences in carbonate systems: Concepts vs experience

NASA Astrophysics Data System (ADS)

Pomar, Luis; Haq, Bilal U.

2016-11-01

Efficacy of sequence stratigraphic concepts in siliciclastic systems has been proven by successful applications in both academia and the industry over the past four decades. However, experience has demonstrated repeatedly that the relatively simple advective transportational approach of these models is less than successful when applied to the more complex carbonate systems and can lead to erroneous interpretations. Instead, an approach that includes the use of the changes in the biotic components of carbonate deposits to infer the sea-level trajectory and thereby placing it in the proper sequence framework is deemed to be more meaningful. This is exemplified with several well-studied examples that illustrate the variety of ways in which the biotic components can build carbonate platforms, and how these have changed through the ages prompted by biological evolution. This extended review discusses carbonate production, source to sink transportation influenced by sea-level changes, surface waves, as well as the less understood and under-appreciated internal waves, and the resulting variety of platforms that can be built by the interaction of these factors, as well as the changing patterns of biotic components with time. Their effect on the carbonate reservoir is considerable, understanding of which is the ultimate objective of carbonate research for applications in the industry. Key elements in the carbonate environments that differ from the siliciclastic systems are: 1) intrabasinal conditions (nutrients, salinity, temperature, water energy, transparency) are important controls on carbonate production and therefore also control in-situ accommodation and how it may be filled; 2) depositional accommodation can be both physical (controlled by hydrodynamics) and ecological (in the building-up above the base level mode); 3) because carbonates are products of biological activity, their production modes have been changing with time as their biotic components have evolved; 4

Improving source identification of Atlanta aerosol using temperature resolved carbon fractions in positive matrix factorization

NASA Astrophysics Data System (ADS)

Kim, Eugene; Hopke, Philip K.; Edgerton, Eric S.

Daily integrated PM 2.5 (particulate matter ⩽2.5 μm in aerodynamic diameter) composition data including eight individual carbon fractions collected at the Jefferson Street monitoring site in Atlanta were analyzed with positive matrix factorization (PMF). Particulate carbon was analyzed using the thermal optical reflectance method that divides carbon into four organic carbon (OC), pyrolized organic carbon (OP), and three elemental carbon (EC) fractions. A total of 529 samples and 28 variables were measured between August 1998 and August 2000. PMF identified 11 sources in this study: sulfate-rich secondary aerosol I (50%), on-road diesel emissions (11%), nitrate-rich secondary aerosol (9%), wood smoke (7%), gasoline vehicle (6%), sulfate-rich secondary aerosol II (6%), metal processing (3%), airborne soil (3%), railroad traffic (3%), cement kiln/carbon-rich (2%), and bus maintenance facility/highway traffic (2%). Differences from previous studies using only the traditional OC and EC data (J. Air Waste Manag. Assoc. 53(2003a)731; Atmos Environ. (2003b)) include four traffic-related combustion sources (gasoline vehicle, on-road diesel, railroad, and bus maintenance facility) containing carbon fractions whose abundances were different between the various sources. This study indicates that the temperature resolved fractional carbon data can be utilized to enhance source apportionment study, especially with respect to the separation of diesel emissions from gasoline vehicle sources. Conditional probability functions using surface wind data and identified source contributions aid the identifications of local point sources.

Southern Ocean coccolithophore biogeography - controlling factors and implications for global biogeochemical cycles

NASA Astrophysics Data System (ADS)

Nissen, Cara; Vogt, Meike; Münnich, Matthias; Gruber, Nicolas

2017-04-01

Southern Ocean phytoplankton biogeography is important for the biogeochemical cycling of carbon, silicate, and the transport of macronutrients to lower latitudes. With the discovery of the "Great Calcite Belt" (GBC), revealing an unexpectedly high prevalence of calcifying phytoplankton in the subtropical frontal region between 40-55°S, the relative importance of Southern Ocean coccolithophores for phytoplankton biomass, net primary productivity and the carbon cycle need to be revisited. Using a regional high-resolution model with an embedded ecosystem module (ROMS-BEC) for the Southern Ocean (24-78°S) that has been extended to include an explicit representation of coccolithophores, we assess the environmental drivers of Southern Ocean coccolithophore biogeography over the course of the growing season. We thereby focus on biotic interactions and the relative importance of top-down (grazing) versus bottom-up factors (light, nutrient, temperature) controlling growth and abundance. In our simulation, coccolithophores are an important member of the Southern Ocean phytoplankton community, contributing 13% to annually integrated net primary productivity south of 30°S. We estimate the integrated annual calcification rate to account for 40% of the satellite derived global estimate. Modeled coccolithophore biomass is highest in February and March in a latitudinal band between 40-55°S, when diatoms become heavily silicate limited. This region is characterized by a number of divergent fronts with a low Si:Fe ratio of waters supplied to the mixed layer, supporting an increased growth of coccolithophores at the expense of diatoms. We find top down controls to be the major control on the relative abundance of diatoms and coccolithophores in the Southern Ocean. We perform iron and silicate fertilization experiments to assess the effects of changed nutrient availability on coccolithophore abundance in the GCB. We find that changes in nutrient stoichiometry significantly alter

Soft-Starting Power-Factor Motor Controller

NASA Technical Reports Server (NTRS)

Nola, F. J.

1983-01-01

Three-phase power-factor controller with soft start is based on earlier version that does not control starting transients. Additional components serve to turn off "run" command signal and substitute gradual startup command signal during preset startup interval. Improved controller reduces large current surge that usually accompanies starting. Controller applies power smoothly, without causing motor vibrations.

The effects of emission control strategies on light-absorbing carbon emissions from a modern heavy-duty diesel engine.

PubMed

Robinson, Michael A; Olson, Michael R; Liu, Z Gerald; Schauer, James J

2015-06-01

Control of atmospheric black carbon (BC) and brown carbon (BrC) has been proposed as an important pathway to climate change mitigation, but sources of BC and BrC are still not well understood. In order to better identify the role of modern heavy-duty diesel engines on the production of BC and BrC, emissions from a heavy-duty diesel engine operating with different emission control strategies were examined using a source dilution sampling system. The effect of a diesel oxidation catalyst (DOC) and diesel particulate filter (DPF) on light-absorbing carbon (LAC) was evaluated at three steady-state engine operation modes: idle, 50% speed and load, and 100% speed and load. LAC was measured with four different engine configurations: engine out, DOC out, DPF out, and engine out with an altered combustion calibration. BC and BrC emission rates were measured with the Aethalometer (AE-31). EC and BC emission rates normalized to the mass of CO₂emitted increased with increasing engine speed and load. Emission rates normalized to brake-specific work did not exhibit similar trends with speed and load, but rather the highest emission rate was measured at idle. EC and OC emissions were reduced by 99% when the DOC and DPF architecture was applied. The application of a DPF was equally effective at removing 99% of the BC fraction of PM, proving to be an important control strategy for both LAC and PM. BC emissions were unexpectedly increased across the DOC, seemingly due to a change aerosol optical properties. Removal of exhaust gas recirculation (EGR) flow due to simulated EGR cooler failure caused a large increase in OC and BrC emission rates at idle, but had limited influence during high load operation. LAC emissions proved to be sensitive to the same control strategies effective at controlling the total mass of diesel PM. In the context of black carbon emissions, very small emission rates of brown carbon were measured over a range of control technologies and engine operating

A simple, mass balance model of carbon flow in a controlled ecological life support system

NASA Technical Reports Server (NTRS)

Garland, Jay L.

1989-01-01

Internal cycling of chemical elements is a fundamental aspect of a Controlled Ecological Life Support System (CELSS). Mathematical models are useful tools for evaluating fluxes and reservoirs of elements associated with potential CELSS configurations. A simple mass balance model of carbon flow in CELSS was developed based on data from the CELSS Breadboard project at Kennedy Space Center. All carbon reservoirs and fluxes were calculated based on steady state conditions and modelled using linear, donor-controlled transfer coefficients. The linear expression of photosynthetic flux was replaced with Michaelis-Menten kinetics based on dynamical analysis of the model which found that the latter produced more adequate model output. Sensitivity analysis of the model indicated that accurate determination of the maximum rate of gross primary production is critical to the development of an accurate model of carbon flow. Atmospheric carbon dioxide was particularly sensitive to changes in photosynthetic rate. The small reservoir of CO2 relative to large CO2 fluxes increases the potential for volatility in CO2 concentration. Feedback control mechanisms regulating CO2 concentration will probably be necessary in a CELSS to reduce this system instability.

Hydrologic Transport of Dissolved Inorganic Carbon and Its Control on Chemical Weathering

NASA Astrophysics Data System (ADS)

Calabrese, Salvatore; Parolari, Anthony J.; Porporato, Amilcare

2017-10-01

Chemical weathering is one of the major processes interacting with climate and tectonics to form clays, supply nutrients to soil microorganisms and plants, and sequester atmospheric CO2. Hydrology and dissolution kinetics have been emphasized as factors controlling chemical weathering rates. However, the interaction between hydrology and transport of dissolved inorganic carbon (DIC) in controlling weathering has received less attention. In this paper, we present an analytical model that couples subsurface water and chemical molar balance equations to analyze the roles of hydrology and DIC transport on chemical weathering. The balance equations form a dynamical system that fully determines the dynamics of the weathering zone chemistry as forced by the transport of DIC. The model is formulated specifically for the silicate mineral albite, but it can be extended to other minerals, and is studied as a function of percolation rate and water transit time. Three weathering regimes are elucidated. For very small or large values of transit time, the weathering is limited by reaction kinetics or transport, respectively. For intermediate values, the system is transport controlled and is sensitive to transit time. We apply the model to a series of watersheds for which we estimate transit times and identify the type of weathering regime. The results suggest that hydrologic transport of DIC may be as important as reaction kinetics and dilution in determining chemical weathering rates.

Factors affecting stress assisted corrosion cracking of carbon steel under industrial boiler conditions

NASA Astrophysics Data System (ADS)

Yang, Dong

Failure of carbon steel boiler tubes from waterside has been reported in the utility boilers and industrial boilers for a long time. In industrial boilers, most waterside tube cracks are found near heavy attachment welds on the outer surface and are typically blunt, with multiple bulbous features indicating a discontinuous growth. These types of tube failures are typically referred to as stress assisted corrosion (SAC). For recovery boilers in the pulp and paper industry, these failures are particularly important as any water leak inside the furnace can potentially lead to smelt-water explosion. Metal properties, environmental variables, and stress conditions are the major factors influencing SAC crack initation and propagation in carbon steel boiler tubes. Slow strain rate tests (SSRT) were conducted under boiler water conditions to study the effect of temperature, oxygen level, and stress conditions on crack initation and propagation on SA-210 carbon steel samples machined out of boiler tubes. Heat treatments were also performed to develop various grain size and carbon content on carbon steel samples, and SSRTs were conducted on these samples to examine the effect of microstructure features on SAC cracking. Mechanisms of SAC crack initation and propagation were proposed and validated based on interrupted slow strain tests (ISSRT). Water chemistry guidelines are provided to prevent SAC and fracture mechanics model is developed to predict SAC failure on industrial boiler tubes.

Controlling the Pore Size of Mesoporous Carbon Thin Films through Thermal and Solvent Annealing.

PubMed

Zhou, Zhengping; Liu, Guoliang

2017-04-01

Herein an approach to controlling the pore size of mesoporous carbon thin films from metal-free polyacrylonitrile-containing block copolymers is described. A high-molecular-weight poly(acrylonitrile-block-methyl methacrylate) (PAN-b-PMMA) is synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. The authors systematically investigate the self-assembly behavior of PAN-b-PMMA thin films during thermal and solvent annealing, as well as the pore size of mesoporous carbon thin films after pyrolysis. The as-spin-coated PAN-b-PMMA is microphase-separated into uniformly spaced globular nanostructures, and these globular nanostructures evolve into various morphologies after thermal or solvent annealing. Surprisingly, through thermal annealing and subsequent pyrolysis of PAN-b-PMMA into mesoporous carbon thin films, the pore size and center-to-center spacing increase significantly with thermal annealing temperature, different from most block copolymers. In addition, the choice of solvent in solvent annealing strongly influences the block copolymer nanostructure and the pore size of mesoporous carbon thin films. The discoveries herein provide a simple strategy to control the pore size of mesoporous carbon thin films by tuning thermal or solvent annealing conditions, instead of synthesizing a series of block copolymers of various molecular weights and compositions. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Controls Over Mesopelagic Interior Carbon Storage

NASA Astrophysics Data System (ADS)

Sanders, R.

2016-02-01

Ocean biological processes play a central role in controlling atmospheric CO2 levels with the size of this effect being largely dependent on the depth at which sinking organic carbon (C) is recycled in the ocean's mesopelagic, between 100 and 1000m. Until recently our understanding was so poor that we were unable to even create and close a budget for the processes involved in supplying and consuming organic C in the mesopelagic, let alone model them explicitly with our best estimates of C sources and sinks being an order of magnitude apart. In 2014 however we published the first balanced mesopelagic C budget, in the Northeast Atlantic. Large scale data syntheses suggest that a wide range of factors can influence remineralisation depth including surface biogeochemical processes, dissolved oxygen (DO), and temperature (T). However such correlation analyses cannot provide a mechanistic understanding of mesopelagic remineralisation. In light of this, we have proposed to the UK NERC a focussed project known as COMICS with this mechanistic understanding as its aim. We will use targeted fieldwork to develop new parameterisations of particle flux and implement them in an IPCC class global biogeochemical model. Cruises in the Southern Ocean and in the Benguela Upwelling will exploit strong local gradients in surface biogeochemistry, T and DO. We will compile 1-d C budgets and make intensive measurements of interior C cycling and ecosystem structure. We will synthesise the observations to determine which processes are key, create new parameterisations for interior remineralisation and evaluate them by their ability to reproduce global biogeochemical distributions. Finally we will use these tools to provide a new estimate of ocean C storage using the UK Earth System Model's ocean component. This poster will introduce the project and describe the major challenges we face in delivering it.

Carbon Sequestration and Peat Accretion Processes in Peatland Systems: A North-South Comparison

NASA Astrophysics Data System (ADS)

Richardson, C. J.; Wang, H.; Bridgham, S. D.

2012-12-01

Millions of hectares of peatlands exist in the U.S. and Canada but few comparisons have been made on the process controlling peat accretion, carbon sequestration and GHG losses across latitudinal gradients. Historic threats to carbon sequestration for these areas have been drainage and conversion to agriculture and forestry, which promotes the decomposition of the organic matter in the soil, leading to accelerated soil subsidence, severe carbon losses, and accelerated transport of C and nutrients to adjoining ecosystems. A more recent and insidious threat to the survival of peatlands worldwide is the increased temperature and drought conditions projected for many areas of global peatlands (IPCC 2007). A comparison of carbon sequestration rates and controlling processes for southeastern shrub bogs, the Florida Everglades and selected peatlands of the northern US and Canada under current climatic conditions reveals several major differences in controlling factors and rates of sequestration and carbon flux. Numerous studies have shown that drought or drainage can unlock historically stored carbon, thus releasing more CO2 ¬ and dissolved organic carbon (Blodau et al. 2004; Furukawa et al. 2005; Von Arnold et al. 2005; Hirano et al. 2007), and such effects might last for decades (Fenner & Freeman 2011). The main driver of this process is the O2 introduced by drought or drainage, which will increase the activity of phenol oxidase, then accelerate the decomposition of phenol compounds, which is generally considered the "enzymatic latch" for carbon storage in peatlands (Freeman et al. 2001). However, our recent studies in southeastern peatlands along the coast of North Carolina have found that drought or drainage does not affect CO2 emission in some southern peatlands where the initial water level is below the ground surface (unsaturated peats), as polyphenol increases rather than decreases. Our results suggest that additional controlling factors, rather than anoxia exist

Thermodynamic Cconstraints on Coupled Carbonate-Pyrite Weathering Dynamics and Carbon Fluxes

NASA Astrophysics Data System (ADS)

Winnick, M.; Maher, K.

2017-12-01

Chemical weathering within the critical zone regulates global biogeochemical cycles, atmospheric composition, and the supply of key nutrients to terrestrial and aquatic ecosystems. Recent studies suggest that thermodynamic limits on solute production act as a first-order control on global chemical weathering rates; however, few studies have addressed the factors that set these thermodynamic limits in natural systems. In this presentation, we investigate the effects of soil CO2 concentrations and pyrite oxidation rates on carbonate dissolution and associated carbon fluxes in the East River watershed in Colorado, using concentration-discharge relationships and thermodynamic constraints. Within the shallow subsurface, soil respiration rates and moisture content determine the extent of carbonic acid-promoted carbonate dissolution through their modulation of soil pCO2 and the balance of open- v. closed-system weathering processes. At greater depths, pyrite oxidation generates sulfuric acid, which alters the approach to equilibrium of infiltrating waters. Through comparisons of concentration-discharge data and reactive transport model simulations, we explore the conditions that determine whether sulfuric acid reacts to dissolve additional carbonate mineral or instead reacts with alkalinity already in solution - the balance of which determines watershed carbon flux budgets. Our study highlights the importance of interactions between the chemical structure of the critical zone and the hydrologic regulation of flowpaths in determining concentration-discharge relationships and overall carbon fluxes.

Controllable Synthesis of Functional Hollow Carbon Nanostructures with Dopamine As Precursor for Supercapacitors.

PubMed

Liu, Chao; Wang, Jing; Li, Jiansheng; Luo, Rui; Shen, Jinyou; Sun, Xiuyun; Han, Weiqing; Wang, Lianjun

2015-08-26

N-doped hollow carbon spheres (N-HCSs) are promising candidates as electrode material for supercapacitor application. In this work, we report a facile one-step synthesis of discrete and highly dispersible N-HCSs with dopamine (DA) as a carbon precursor and TEOS as a structure-assistant agent in a mixture containing water, ethanol, and ammonia. The architectures of resultant N-HCSs, including yolk-shell hollow carbon spheres (YS-HCSs), single-shell hollow carbon spheres (SS-HCSs), and double-shells hollow carbon spheres (DS-HCSs), can be efficiently controlled through the adjustment of the amount of ammonia. To explain the relation and formation mechanism of these hollow carbon structures, the samples during the different synthetic steps, including polymer/silica spheres, carbon/silica spheres and silica spheres by combustion in air, were characterized by TEM. Electrochemical measurements performed on YS-HCSs, SS-HCSs, and DS-HCSs showed high capacitance with 215, 280, and 381 F g(-1), respectively. Moreover, all the nitrogen-doped hollow carbon nanospheres showed a good cycling stability 97.0% capacitive retention after 3000 cycles. Notably, the highest capacitance of DS-HCSs up to 381 F g(-1) is higher than the capacitance reported so far for many carbon-based materials, which may be attributed to the high surface area, hollow structure, nitrogen functionalization, and double-shell architecture. These kinds of N-doped hollow-structured carbon spheres may show promising prospects as advanced energy storage materials and catalyst supports.

Carbonate buffering and metabolic controls on carbon dioxide in rivers

USGS Publications Warehouse

Stets, Edward; Butman, David; McDonald, Cory P.; Stackpoole, Sarah M.; DeGrandpre, Michael D.; Striegl, Robert G.

2017-01-01

Multiple processes support the significant efflux of carbon dioxide (CO2) from rivers and streams. Attribution of CO2 oversaturation will lead to better quantification of the freshwater carbon cycle and provide insights into the net cycling of nutrients and pollutants. CO2 production is closely related to O2consumption because of the metabolic linkage of these gases. However, this relationship can be weakened due to dissolved inorganic carbon inputs from groundwater, carbonate buffering, calcification, and anaerobic metabolism. CO2and O2 concentrations and other water quality parameters were analyzed in two data sets: a synoptic field study and nationwide water quality monitoring data. CO2 and O2 concentrations were strongly negatively correlated in both data sets (ρ = −0.67 and ρ = −0.63, respectively), although the correlations were weaker in high-alkalinity environments. In nearly all samples, the molar oversaturation of CO2 was a larger magnitude than molar O2 undersaturation. We used a dynamically coupled O2CO2 model to show that lags in CO2 air-water equilibration are a likely cause of this phenomenon. Lags in CO2 equilibration also impart landscape-scale differences in the behavior of CO2 between high- and low-alkalinity watersheds. Although the concept of carbonate buffering and how it creates lags in CO2 equilibration with the atmosphere is well understood, it has not been sufficiently integrated into our understanding of CO2 dynamics in freshwaters. We argue that the consideration of carbonate equilibria and its effects on CO2 dynamics are primary steps in understanding the sources and magnitude of CO2 oversaturation in rivers and streams.

Organic carbon, and not copper, controls denitrification in oxygen minimum zones of the ocean

NASA Astrophysics Data System (ADS)

Ward, Bess B.; Tuit, Caroline B.; Jayakumar, Amal; Rich, Jeremy J.; Moffett, James; Naqvi, S. Wajih A.

2008-12-01

Incubation experiments under trace metal clean conditions and ambient oxygen concentrations were used to investigate the response of microbial assemblages in oxygen minimum zones (OMZs) to additions of organic carbon and copper, two factors that might be expected to limit denitrification in the ocean. In the OMZs of the Eastern Tropical North and South Pacific, denitrification appeared to be limited by organic carbon; exponential cell growth and rapid nitrate and nitrite depletion occurred upon the addition of small amounts of carbon, but copper had no effect. In the OMZ of the Arabian Sea, neither carbon nor copper appeared to be limiting. We hypothesize that denitrification is variable in time and space in the OMZs in ways that may be predictable based on links to the episodic supply of organic substrates from overlying productive surface waters.

Controlled alignment of carbon nanofibers in a large-scale synthesis process

NASA Astrophysics Data System (ADS)

Merkulov, Vladimir I.; Melechko, A. V.; Guillorn, M. A.; Simpson, M. L.; Lowndes, D. H.; Whealton, J. H.; Raridon, R. J.

2002-06-01

Controlled alignment of catalytically grown carbon nanofibers (CNFs) at a variable angle to the substrate during a plasma-enhanced chemical vapor deposition process is achieved. The CNF alignment is controlled by the direction of the electric field lines during the synthesis process. Off normal CNF orientations are achieved by positioning the sample in the vicinity of geometrical features of the sample holder, where bending of the electric field lines occurs. The controlled growth of kinked CNFs that consist of two parts aligned at different angles to the substrate normal also is demonstrated.

Power Factor Controller

NASA Technical Reports Server (NTRS)

1997-01-01

Frank Nola invented the Power Factor Controller (PFC) at Marshall Space Flight Center more than a decade ago. Nola came up with a way to curb power wastage in AC induction motors. The PFC matches voltage with the motor's actual need by continuously sensing shifts between voltage and current. When it senses a light load it cuts the voltage to the minimum needed. Potential energy savings range from 8 to 65 percent.

Particulate matter and black carbon optical properties and emission factors from prescribed fires in the southeastern United States

EPA Pesticide Factsheets

This dataset provides all data used to generate the figures and tables in the article entitled Particulate matter and black carbon optical properties and emission factors from prescribed fires in the southeastern United States published in the Journal of Geophysical Research: AtmospheresThis dataset is associated with the following publication:Holder , A., G. Hagler , J. Aurell, M. Hays , and B. Gullett. Particulate matter and black carbon optical properties and emission factors from prescribed fires in the southeastern United States. JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES. American Geophysical Union, Washington, DC, USA, 121(7): 3465-3483, (2016).

Identification of the driving factors' influences on regional energy-related carbon emissions in China based on geographical detector method.

PubMed

Zhang, Xinlin; Zhao, Yuan

2018-04-01

To investigate the influences of different factors on spatial heterogeneity of regional carbon emissions, we firstly studied the spatial-temporal dynamics of regional energy-related carbon emissions using global Moran's I and Getis-Ord Gi and applied geographical detector model to explain the spatial heterogeneity of regional carbon emissions. Some conclusions were drawn. Regional carbon emissions showed significant global and local spatial autocorrelation. The carbon emissions were greater in eastern and northern regions than in western and southern regions. Fixed assets investment and economic output had been the main contributing factors over the study period, and economic output had been decreasing its influence. Industrial structure's influence showed a decrease trend and became smaller in 2015. The results of the interaction detections in 2015 can be divided into two types: enhance and nonlinear, and enhance and bivariate. The interactive influences between technological level and fixed assets investment, economic output and technological level, population size and technological level, and economic output and economic development were greater than others. Some policy recommendations were proposed.

Factors affecting distribution patterns of organic carbon in sediments at regional and national scales in China.

PubMed

Cao, Qingqing; Wang, Hui; Zhang, Yiran; Lal, Rattan; Wang, Renqing; Ge, Xiuli; Liu, Jian

2017-07-14

Wetlands are an important carbon reservoir pool in terrestrial ecosystems. Light fraction organic carbon (LFOC), heavy fraction organic carbon (HFOC), and dissolved organic carbon (DOC) were fractionated in sediment samples from the four wetlands (ZR: Zhaoniu River; ZRCW: Zhaoniu River Constructed Wetland; XR: Xinxue River; XRCW: Xinxue River Constructed Wetland). Organic carbon (OC) from rivers and coasts of China were retrieved and statistically analyzed. At regional scale, HFOC stably dominates the deposition of OC (95.4%), whereas DOC and LFOC in ZR is significantly higher than in ZRCW. Concentration of DOC is significantly higher in XRCW (30.37 mg/l) than that in XR (13.59 mg/l). DOC and HFOC notably distinguish between two sampling campaigns, and the deposition of carbon fractions are limited by low nitrogen input. At the national scale, OC attains the maximum of 2.29% at precipitation of 800 mm. OC has no significant difference among the three climate zones but significantly higher in river sediments than in coasts. Coastal OC increases from Bohai Sea (0.52%) to South Sea (0.70%) with a decrease in latitude. This study summarizes the factors affecting organic carbon storage in regional and national scale, and have constructive implications for carbon assessment, modelling, and management.

Controlling the Electrochemically Active Area of Carbon Fiber Microelectrodes by the Electrodeposition and Selective Removal of an Insulating Photoresist

PubMed Central

Lambie, Bradley A.; Orwar, Owe; Weber, Stephen G.

2008-01-01

A new and simple method permits control of the electrochemically active area of a carbon fiber microelectrode. An electrophoretic photoresist insulates the 10 μm diameter carbon fiber microelectrodes. Photolysis of the photoresist followed by immersion of the exposed area into a developing solution reveals electroactive carbon fiber surface. The electroactive surface area exposed can be controlled with a good degree of reproducibility. PMID:16841943

Targeted Control of Permeability Using Carbonate Dissolution/Precipitation Reactions

NASA Astrophysics Data System (ADS)

Clarens, A. F.; Tao, Z.; Plattenberger, D.

2016-12-01

Targeted mineral precipitation reactions are a promising approach for controlling fluid flow in the deep subsurface. Here we studied the potential to use calcium and magnesium bearing silicates as cation donors that would react with aqueous phase CO2 under reservoir conditions to form solid carbonate precipitates. Preliminary experiments in high pressure and temperature columns suggest that these reactions can effectively lower the permeability of a porous media. Wollastonite (CaSiO3) was used as the model silicate, injected as solid particles into the pore space of a packed column, which was then subsequently flooded with CO2(aq). The reactions occur spontaneously, leveraging the favorable kinetics that occur at the high temperature and pressure conditions characteristic of the deep subsurface, to form solid phase calcium carbonate (CaCO3) and amorphous silica (SiO2) within the pore space. Both x-ray tomography imaging of reacted columns and electron microscopy imaging of thin sections were used to characterize where dissolution/precipitation occurred within the porous media. The spatial distribution of the products was closely tied to the flow rate and the duration of the experiment. The SiO2 product precipitated in close spatial proximity to the CaSiO3 reactant. The CaCO3 product, which is sensitive to the low pH and high pCO2 brine, precipitated out of solution further down the column as Ca2+ ions moved with the brine. The permeability of the columns decreased by several orders of magnitude after injecting the CaSiO3 particles. Following carbonation, the permeability decreased even further as precipitates filled flow paths within the pore network. A pore network model was developed to help understand the interplay between precipitation kinetics and flow in altering the permeability of the porous media. The effect of particle concentration and size, pore size, reaction time, and pCO2, are explored on pore/fracture aperture and reaction extent. To provide better

Seasonal and event-scale controls on dissolved organic carbon and nitrate flushing from catchments

NASA Astrophysics Data System (ADS)

Sebestyen, S. D.; Boyer, E. W.; Shanley, J. B.; Doctor, D. H.

2005-05-01

To explore terrestrial and aquatic linkages controlling nutrient dynamics in forested catchments, we collected high-frequency samples from 2002 to 2004 at the Sleepers River Research Watershed in northeastern Vermont USA. We measured DOC (dissolved organic carbon), SUVA (specific UV absorbance), nitrate, and major ion concentrations over a wide range of flow conditions. In addition, weekly samples since 1991 provide a longer term record of stream nutrient fluxes. During events, DOC concentrations increased with flow consistent with the flushing of a large reservoir of mobile organic carbon from forest soils. Higher concentrations of DOC and SUVA in the growing versus dormant season illustrated seasonal variation in sources, characteristics (i.e. reactivity), availability, and controls on the flushing response of organic matter from the landscape to streams. In contrast, stream nitrate concentrations increased with flow but only when catchments "wetted-up" after baseflow periods. Growing season stream nitrate responses were dependent on short-term antecedent moisture conditions indicating rapid depletion of the soil nitrate reservoir when source areas became hydrologically connected to streams. While the different response patterns emphasized variable source and biogeochemical controls in relation to flow patterns, coupled carbon and nitrogen biogeochemical processes were also important controls on stream nutrient fluxes. In particular, leaf fall was a critical time when reactive DOC from freshly decomposing litter fueled in-stream consumption of nitrate leading to sharp declines of stream nitrate concentrations. Our measurements highlight the importance of "hot spots" and "hot moments" of biogeochemical and hydrological processes that control stream responses. Furthermore, our work illustrates how carbon, nitrogen, and water cycles are coupled in catchments, and provides a conceptual model for future work aimed at modeling forest stream hydrochemistry at the

GENOME-ENABLED DISCOVERY OF CARBON SEQUESTRATION GENES IN POPLAR

DOE Office of Scientific and Technical Information (OSTI.GOV)

DAVIS J M

2007-10-11

Plants utilize carbon by partitioning the reduced carbon obtained through photosynthesis into different compartments and into different chemistries within a cell and subsequently allocating such carbon to sink tissues throughout the plant. Since the phytohormones auxin and cytokinin are known to influence sink strength in tissues such as roots (Skoog & Miller 1957, Nordstrom et al. 2004), we hypothesized that altering the expression of genes that regulate auxin-mediated (e.g., AUX/IAA or ARF transcription factors) or cytokinin-mediated (e.g., RR transcription factors) control of root growth and development would impact carbon allocation and partitioning belowground (Fig. 1 - Renewal Proposal). Specifically, themore » ARF, AUX/IAA and RR transcription factor gene families mediate the effects of the growth regulators auxin and cytokinin on cell expansion, cell division and differentiation into root primordia. Invertases (IVR), whose transcript abundance is enhanced by both auxin and cytokinin, are critical components of carbon movement and therefore of carbon allocation. Thus, we initiated comparative genomic studies to identify the AUX/IAA, ARF, RR and IVR gene families in the Populus genome that could impact carbon allocation and partitioning. Bioinformatics searches using Arabidopsis gene sequences as queries identified regions with high degrees of sequence similarities in the Populus genome. These Populus sequences formed the basis of our transgenic experiments. Transgenic modification of gene expression involving members of these gene families was hypothesized to have profound effects on carbon allocation and partitioning.« less

Factors influencing warfarin control in Australia and Singapore.

PubMed

Bernaitis, Nijole; Ching, Chi Keong; Teo, Siew Chong; Chen, Liping; Badrick, Tony; Davey, Andrew K; Crilly, Julia; Anoopkumar-Dukie, Shailendra

2017-09-01

Warfarin is widely used for patients with non-valvular atrial fibrillation (NVAF). Variations in warfarin control, as measured by time in therapeutic range (TTR), have been reported across different regions and ethnicities, particularly between Western and Asian countries. However, there is limited data on comparative factors influencing warfarin control in Caucasian and Asian patients. Therefore, the aim of this study was to determine warfarin control and potential factors influencing this in patients with NVAF in Australia and Singapore. Retrospective data was collected for patients receiving warfarin for January to June 2014 in Australia and Singapore. TTR was calculated for individuals with mean patient TTR used for analysis. Possible influential factors on TTR were analysed including age, gender, concurrent co-morbidities, and concurrent medication. The mean TTR was significantly higher in Australia (82%) than Singapore (58%). At both sites, chronic kidney disease significantly lowered this TTR. Further factors influencing control were anaemia and age<60years in Australia, and vascular disease, CHA 2 DS 2 -VASc score of 6, and concurrent platelet inhibitor therapy in Singapore. Warfarin control was significantly higher in Australia compared to Singapore, however chronic kidney disease reduced control at both sites. The different levels of control in these two countries, together with patient factors further reducing control may impact on anticoagulant choice in these countries with better outcomes from warfarin in Australia compared to Singapore. Copyright © 2017 Elsevier Ltd. All rights reserved.

40 CFR Table N-1 to Subpart N of... - CO2 Emission Factors for Carbonate-Based Raw Materials

Code of Federal Regulations, 2011 CFR

2011-07-01

...-Based Raw Materials N Table N-1 to Subpart N of Part 98 Protection of Environment ENVIRONMENTAL... Raw Materials Carbonate-basedraw material—mineral CO2 emission factor a Limestone—CaCO3 0.440 Dolomite... in units of metric tons of CO2 emitted per metric ton of carbonate-based raw material charged to the...

Factors controlling spatial distribution patterns of biocrusts in a heterogeneous and topographically complex semiarid area

NASA Astrophysics Data System (ADS)

Chamizo, Sonia; Rodríguez-Caballero, Emilio; Roncero, Beatriz; Raúl Román, José; Cantón, Yolanda

2016-04-01

Biocrusts are widespread soil components in drylands all over the world. They are known to play key roles in the functioning of these regions by fixing carbon and nitrogen, regulating hydrological processes, and preventing from water and wind erosion, thus reducing the loss of soil resources and increasing soil fertility. The rate and magnitude of services provided by biocrusts greatly depend on their composition and developmental stage. Late-successional biocrusts such as lichens and mosses have higher carbon and nitrogen fixation rates, and confer greater protection against erosion and the loss of sediments and nutrients than early-successional algae and cyanobacteria biocrusts. Knowledge of spatial distribution patterns of different biocrust types and the factors that control their distribution is important to assess ecosystem services provided by biocrusts at large spatial scales and to improve modelling of biogeochemical processes and water and carbon balance in drylands. Some of the factors that condition biocrust cover and composition are incoming solar radiation, terrain attributes, vegetation distribution patterns, microclimatic variables and soil properties such as soil pH, texture, soil organic matter, soil nutrients and gypsum and CaCO3 content. However, the factors that govern biocrust distribution may vary from one site to another depending on site characteristics. In this study, we examined the influence of abiotic attributes on the spatial distribution of biocrust types in a complex heterogeneous badland system (Tabernas, SE Spain) where biocrust cover up to 50% of the soil surface. From the analysis of relationships between terrain attributes and proportional abundance of biocrust types, it was found that topography exerted a main control on the spatial distribution of biocrust types in this area. SW-facing slopes were dominated by physical soil crusts and were practically devoid of vegetation and biocrusts. Biocrusts mainly occupied the pediments

Nitrogen Losses in Sediments of the East China Sea: Spatiotemporal Variations, Controlling Factors, and Environmental Implications

NASA Astrophysics Data System (ADS)

Lin, Xianbiao; Liu, Min; Hou, Lijun; Gao, Dengzhou; Li, Xiaofei; Lu, Kaijun; Gao, Juan

2017-10-01

Global reactive nitrogen (N) has increased dramatically in coastal marine ecosystems over the past decades and caused numerous eco-environmental problems. Coastal marine sediment plays a critical role in N losses via denitrification and anaerobic ammonium oxidation (anammox) and release of nitrous oxide (N2O). However, both the magnitude and contributions of denitrification, anammox, and N2O production in sediments still remain unclear, causing uncertainty in defining the N budget for coastal marine ecosystems. Here potential rates of N losses, and their contributions and controlling factors, were investigated in surface sediments during six cruises from 429 sites of the East China Sea. The potential rates of denitrification, anammox, and N2O production varied both spatially and seasonally, but the contribution of anammmox to total N2 production (%anammox) and N2O:N2 ratio only varied spatially. Both organic carbon and nitrate (NO3-) were important factors controlling N losses, N2O:N2 ratio, and %anammox. Our results also showed that marine organic carbon induced by eutrophication plays an important role in stimulating reactive N removal and increasing N2O production in warm seasons. The sediment N loss caused by denitrification, anammox, and N2O production in the study area were estimated at 2.2 × 106 t N yr-1, 4.6 × 105 t N yr-1, and 8 × 103 t N yr-1, respectively. Although sediments remove large quantities of reactive N, they act as an important source of N2O in this region influenced by NO3--laden rivers.

Key Factors Controlling the Growth of Biological Soil Crusts: Towards a Protocol to Produce Biocrusts in Greenhouse Facilities

NASA Astrophysics Data System (ADS)

Velasco Ayuso, Sergio; María Giraldo Silva, Ana; Nelson, Corey; Barger, Nichole; Antoninka, Anita; Bowker, Matthew; Garcia-Pichel, Ferran

2016-04-01

Biological soil crusts (= biocrusts) are topsoil communities comprise of, but not limited to, cyanobacteria, algae, lichens, and mosses that grow intimately associated with soil particles in drylands. Biocrusts have central ecological roles in these areas as sources of carbon and nutrients, and efficiently retain water and prevent soil erosion, which improves soil structure and promotes soil fertility. However, human activities, such as cattle grazing, hiking or military training, are rapidly striking biocrusts. Although it is well known that the inoculation with cyanobacteria or lichens can enhance the recovery of biocrusts in degraded soils, little is known about the factors that control their growth rates. Using soil and inocula from four different sites located in one cold desert (Utah) and in one hot desert (New Mexico), we performed a fractional factorial experiment involving seven factors (water, light, P, N, calcium carbonate, trace metals and type of inoculum) to screen their effects on the growth of biocrusts. After four months, we measured the concentration of chlorophyll a, and we discovered that water, light and P, N or P+N were the most important factors controlling the growth of biocrusts. In the experimental treatments involving these three factors we measured a similar concentration of chlorophyll a (or even higher) to this found in the field locations. Amplification of the 16S rRNA gene segment using universal bacteria primers revealed a microbial community composition in the biocrusts grown that closely corresponds to initial measurements made on inocula. In summary, based on our success in obtaining biocrust biomass from natural communities in greenhouse facilities, without significantly changing its community composition at the phylum and cyanobacterial level, we are paving the road to propose a protocol to produce a high quality-nursed inoculum aiming to assist restoration of arid and semi-arid ecosystems affected by large-scale disturbances.

Controlled Synthesis of Ultralong Carbon Nanotubes with Perfect Structures and Extraordinary Properties.

PubMed

Zhang, Rufan; Zhang, Yingying; Wei, Fei

2017-02-21

Carbon nanotubes (CNTs) have drawn intensive research interest in the past 25 years due to their excellent properties and wide applications. Ultralong CNTs refers to the horizontally aligned CNT arrays which are usually grown on flat substrates, parallel with each other with large intertube distances. They usually have perfect structures, excellent properties, and lengths up to centimeters, even decimeters. Ultralong CNTs are promising candidates as building blocks for transparent displays, nanoelectronics, superstrong tethers, aeronautics and aerospace materials, etc. The controlled synthesis of ultralong CNTs with perfect structures is the key to fully exploit the extraordinary properties of CNTs. CNTs are typical one-dimensional single-crystal nanomaterials. It has always been a great challenge how to grow macroscale single-crystals with no defects. Thus, the synthesis of ultralong CNTs with no defect is of significant importance from both fundamental and industrial aspects. In this Account, we focus on our progress on the controlled synthesis of ultralong CNTs with perfect structures and excellent properties. A deep understanding of the CNT growth mechanism is the first step for the controlled synthesis of ultralong CNTs with high quality. We first introduce the growth mechanism for ultralong CNTs and the main factor affecting their structures. We then discuss the strategies to control the defects in the as-grown ultralong CNTs. With these approaches, ultralong high-quality CNTs with different structures can be obtained. By completely eliminating the factors which may induce defects in the CNT walls, ultralong CNTs with perfect structures can be obtained. Their chiral indices keep unchanged for several centimeters long along the axial direction of the CNTs. The defect-free structures render the ultralong CNTs with excellent electrical, mechanical and thermal properties. The as-grown ultralong CNTs exhibit superhigh mechanical strength (>100 GPa) and their

Stable Carbon Fractionation In Size Segregated Aerosol Particles Produced By Controlled Biomass Burning

NASA Astrophysics Data System (ADS)

Masalaite, Agne; Garbaras, Andrius; Garbariene, Inga; Ceburnis, Darius; Martuzevicius, Dainius; Puida, Egidijus; Kvietkus, Kestutis; Remeikis, Vidmantas

2014-05-01

Biomass burning is the largest source of primary fine fraction carbonaceous particles and the second largest source of trace gases in the global atmosphere with a strong effect not only on the regional scale but also in areas distant from the source . Many studies have often assumed no significant carbon isotope fractionation occurring between black carbon and the original vegetation during combustion. However, other studies suggested that stable carbon isotope ratios of char or BC may not reliably reflect carbon isotopic signatures of the source vegetation. Overall, the apparently conflicting results throughout the literature regarding the observed fractionation suggest that combustion conditions may be responsible for the observed effects. The purpose of the present study was to gather more quantitative information on carbonaceous aerosols produced in controlled biomass burning, thereby having a potential impact on interpreting ambient atmospheric observations. Seven different biomass fuel types were burned under controlled conditions to determine the effect of the biomass type on the emitted particulate matter mass and stable carbon isotope composition of bulk and size segregated particles. Size segregated aerosol particles were collected using the total suspended particle (TSP) sampler and a micro-orifice uniform deposit impactor (MOUDI). The results demonstrated that particle emissions were dominated by the submicron particles in all biomass types. However, significant differences in emissions of submicron particles and their dominant sizes were found between different biomass fuels. The largest negative fractionation was obtained for the wood pellet fuel type while the largest positive isotopic fractionation was observed during the buckwheat shells combustion. The carbon isotope composition of MOUDI samples compared very well with isotope composition of TSP samples indicating consistency of the results. The measurements of the stable carbon isotope ratio in

The CARBONATE project: Mid-latitude Carbonate Systems - Complete Sequences from Cold-Water Coral Carbonate Mounds in the Northeast Atlantic

NASA Astrophysics Data System (ADS)

Wheeler, A.; Freiwald, A.; Hebbeln, D.; Swennen, R.; van Weering, T.; de Haas, H.; Dorschel, B.

2007-12-01

Up to now the carbonate stored in carbonate mounds has not been considered in any global carbonate budget or linked to any global carbon budget involving greenhouse gases. A major challenge exists to quantify the amount and flux of carbon stored by these newly discovered areas of enhanced carbonate accumulation in intermediate water depth. Furthermore, investigations so far reveal that all mounds possess different growth histories depending on the environmental setting and the involved faunal associations. Unfortunately, existing cores only penetrated the upper few meters of the mounds thus limiting mound research to the very late stage of mound development. Access to the longer sequences preserved in giant carbonate mounds was overcome in May 2005 when the IODP Expedition 307 (Porcupine Mound Drilling) recovered complete sedimentary records from one 155 m high "Challenger Mound" in the Porcupine Seabight west off Ireland. Furthermore, EU-FP projects have revealed late stage history of giant mounds in different settings showing that different mounds respond in different ways to environmental forcing factors with no one mound being typical of all. CARBONATE will drill complete sequences through a number of mounds in differing environmental settings using the portable drill rig MeBo (University of Bremen). By understanding how biogeochemical processes control the development of these carbonate mounds and their response to climate change, we will make an important step in quantifying their role as mid-latitude carbonate sinks. In the end, a better understanding of the processes involved in mound formation and development may also result in new views on fossil analogues many of which are less accessible hydrocarbon reservoirs.

Proximate and ultimate controls on carbon and nutrient dynamics of small agricultural catchments

NASA Astrophysics Data System (ADS)

Thomas, Zahra; Abbott, Benjamin W.; Troccaz, Olivier; Baudry, Jacques; Pinay, Gilles

2016-03-01

Direct and indirect effects from human activity have dramatically increased nutrient loading to aquatic inland and estuarine ecosystems. Despite an abundance of studies investigating the impact of agricultural activity on water quality, our understanding of what determines the capacity of a watershed to remove or retain nutrients remains limited. The goal of this study was to identify proximate and ultimate controls on dissolved organic carbon and nutrient dynamics in small agricultural catchments by investigating the relationship between catchment characteristics, stream discharge, and water chemistry. We analyzed a 5-year, high-frequency water chemistry data set from three catchments in western France ranging from 2.3 to 10.8 km2. The relationship between hydrology and solute concentrations differed between the three catchments and was associated with hedgerow density, agricultural activity, and geology. The catchment with thicker soil and higher surface roughness had relatively invariant carbon and nutrient chemistry across hydrologic conditions, indicating high resilience to human disturbance. Conversely, the catchments with smoother, thinner soils responded to both intra- and interannual hydrologic variation with high concentrations of phosphate (PO43-) and ammonium (NH4+) in streams during low flow conditions and strong increases in dissolved organic carbon (DOC), sediment, and particulate organic matter during high flows. Despite contrasting agricultural activity between catchments, the physical context (geology, topography, and land-use configuration) appeared to be the most important determinant of catchment solute dynamics based on principle components analysis. The influence of geology and accompanying topographic and geomorphological factors on water quality was both direct and indirect because the distribution of agricultural activity in these catchments is largely a consequence of the geologic and topographic context. This link between inherent

Carbon fluxes, evapotranspiration, and water use efficiency of terrestrial ecosystems in China

Treesearch

Jingfeng Xiao; Ge Sun; Jiquan Chen; Hui Chen; Shiping Chen; Gang Dong

2013-01-01

The magnitude, spatial patterns, and controlling factors of the carbon and water fluxes of terrestrial ecosystems in China are not well understood due to the lack of ecosystem-level flux observations. We synthesized flux and micrometeorological observations from 22 eddy covariance flux sites across China,and examined the carbon fluxes, evapotranspiration (ET), and...

Controlled growth of well-aligned carbon nanotubes with large diameters

NASA Astrophysics Data System (ADS)

Wang, Xianbao; Liu, Yunqi; Zhu, Daoben

2001-06-01

Well-aligned carbon nanotubes (CNTs) with large diameters (25-200 nm) were synthesized by pyrolysis of iron(II) phthalocyanine. The outer diameter up to 218.5 nm and the length of the well-aligned CNTs can be systematically controlled by varying the growth time. A tube-in-tube nano-structure with large and small diameters of 176 and 16.7 nm, respectively, was found. The grain sizes of the iron catalyst play an important role in controlling the CNT diameters. These results are of great importance to design new aligned CNT-based electron field emitters in the potential application of panel displays.

Plant diversity drives soil microbial biomass carbon in grasslands irrespective of global environmental change factors.

PubMed

Thakur, Madhav Prakash; Milcu, Alexandru; Manning, Pete; Niklaus, Pascal A; Roscher, Christiane; Power, Sally; Reich, Peter B; Scheu, Stefan; Tilman, David; Ai, Fuxun; Guo, Hongyan; Ji, Rong; Pierce, Sarah; Ramirez, Nathaly Guerrero; Richter, Annabell Nicola; Steinauer, Katja; Strecker, Tanja; Vogel, Anja; Eisenhauer, Nico

2015-11-01

Soil microbial biomass is a key determinant of carbon dynamics in the soil. Several studies have shown that soil microbial biomass significantly increases with plant species diversity, but it remains unclear whether plant species diversity can also stabilize soil microbial biomass in a changing environment. This question is particularly relevant as many global environmental change (GEC) factors, such as drought and nutrient enrichment, have been shown to reduce soil microbial biomass. Experiments with orthogonal manipulations of plant diversity and GEC factors can provide insights whether plant diversity can attenuate such detrimental effects on soil microbial biomass. Here, we present the analysis of 12 different studies with 14 unique orthogonal plant diversity × GEC manipulations in grasslands, where plant diversity and at least one GEC factor (elevated CO2 , nutrient enrichment, drought, earthworm presence, or warming) were manipulated. Our results show that higher plant diversity significantly enhances soil microbial biomass with the strongest effects in long-term field experiments. In contrast, GEC factors had inconsistent effects with only drought having a significant negative effect. Importantly, we report consistent non-significant effects for all 14 interactions between plant diversity and GEC factors, which indicates a limited potential of plant diversity to attenuate the effects of GEC factors on soil microbial biomass. We highlight that plant diversity is a major determinant of soil microbial biomass in experimental grasslands that can influence soil carbon dynamics irrespective of GEC. © 2015 John Wiley & Sons Ltd.

Structure and Electromagnetic Properties of Cellular Glassy Carbon Monoliths with Controlled Cell Size

PubMed Central

Szczurek, Andrzej; Plyushch, Artyom; Macutkevic, Jan

2018-01-01

Electromagnetic shielding is a topic of high importance for which lightweight materials are highly sought. Porous carbon materials can meet this goal, but their structure needs to be controlled as much as possible. In this work, cellular carbon monoliths of well-defined porosity and cell size were prepared by a template method, using sacrificial paraffin spheres as the porogen and resorcinol-formaldehyde (RF) resin as the carbon precursor. Physicochemical studies were carried out for investigating the conversion of RF resin into carbon, and the final cellular monoliths were investigated in terms of elemental composition, total porosity, surface area, micropore volumes, and micro/macropore size distributions. Electrical and electromagnetic (EM) properties were investigated in the static regime and in the Ka-band, respectively. Due to the phenolic nature of the resin, the resultant carbon was glasslike, and the special preparation protocol that was used led to cellular materials whose cell size increased with density. The materials were shown to be relevant for EM shielding, and the relationships between those properties and the density/cell size of those cellular monoliths were elucidated. PMID:29723961

Oxidative Attack of Carbon/Carbon Substrates through Coating Pinholes

NASA Technical Reports Server (NTRS)

Jacobson, Nathan S.; Leonhardt, Todd; Curry, Donald; Rapp, Robert A.

1998-01-01

A critical issue with oxidation protected carbon/carbon composites used for spacecraft thermal protection is the formation of coating pinholes. In laboratory experiments, artificial pinholes were drilled through SiC-coatings on a carbon/carbon material and the material was oxidized at 600, 1000, and 1400 C at reduced pressures of air. The attack of the carbon/carbon was quantified by both weight loss and a novel cross-sectioning technique. A two-zone, one dimensional diffusion control model was adapted to analyze this problem. Agreement of the model with experiment was reasonable at 1000 and 1400 C; however results at lower temperatures show clear deviations from the theory suggesting that surface reaction control plays a role.

Controls of streamwater dissolved inorganic carbon dynamics in a forested watershed

USGS Publications Warehouse

Finlay, J.C.

2003-01-01

I investigated controls of stream dissolved inorganic carbon (DIC) sources and cycling along a stream size and productivity gradient in a temperate forested watershed in northern California. Dissolved CO2 (CO2 (aq)) dynamics in heavily shaded streams contrasted strongly with those of larger, open canopied sites. In streams with canopy cover > 97%, CO2 (aq) was highest during baseflow periods (up to 540 ??M) and was negatively related to discharge. Effects of algal photosynthesis on CO2 (aq) were minimal and stream CO2 (aq) was primarily controlled by groundwater CO2 (aq) inputs and degassing losses to the atmosphere. In contrast to the small streams. CO2 (aq) in larger, open-canopied streams was often below atmospheric levels at midday during baseflow and was positively related to discharge. Here, stream CO2 (aq) was strongly influenced by the balance between autotrophic and heterotrophic processes. Dynamics of HCO3- were less complex. HCO3- and Ca2+ were positively correlated, negatively related to discharge, and showed no pattern with stream size. Stable carbon isotope ratios of DIC (i.e. ??13C DIC) increased with stream size and discharge, indicating contrasting sources of DIC to streams and rivers. During summer baseflows, ??13C DIC were 13C-depleted in the smallest streams (minimum of -17.7???) due to the influence of CO2 (aq) derived from microbial respiration and HCO3- derived from carbonate weathering. ??13C DIC were higher (up to -6.6???) in the larger streams and rivers due to invasion of atmospheric CO2 enhanced by algal CO2 (aq) uptake. While small streams were influenced by groundwater inputs, patterns in CO2 (aq) and evidence from stable isotopes demonstrate the strong influence of stream metabolism and CO2 exchange with the atmosphere on stream and river carbon cycles.

Control of Photoluminescence of Carbon Nanodots via Surface Functionalization using Para-substituted Anilines

NASA Astrophysics Data System (ADS)

Kwon, Woosung; Do, Sungan; Kim, Ji-Hee; Seok Jeong, Mun; Rhee, Shi-Woo

2015-07-01

Carbon nanodots (C-dots) are a kind of fluorescent carbon nanomaterials, composed of polyaromatic carbon domains surrounded by amorphous carbon frames, and have attracted a great deal of attention because of their interesting properties. There are still, however, challenges ahead such as blue-biased photoluminescence, spectral broadness, undefined energy gaps and etc. In this report, we chemically modify the surface of C-dots with a series of para-substituted anilines to control their photoluminescence. Our surface functionalization endows our C-dots with new energy levels, exhibiting long-wavelength (up to 650 nm) photoluminescence of very narrow spectral widths. The roles of para-substituted anilines and their substituents in developing such energy levels are thoroughly studied by using transient absorption spectroscopy. We finally demonstrate light-emitting devices exploiting our C-dots as a phosphor, converting UV light to a variety of colors with internal quantum yields of ca. 20%.

Easily degradable carbon - an indicator of microbial hotspots and soil degradation

NASA Astrophysics Data System (ADS)

Wolińska, Agnieszka; Banach, Artur; Szafranek-Nakonieczna, Anna; Stępniewska, Zofia; Błaszczyk, Mieczysław

2018-01-01

The effect of arable soil was quantified against non-cultivated soil on easily degradable carbon and other selected microbiological factors, i.e. soil microbial biomass, respiration activity, and dehydrogenase activity. The intent was to ascertain whether easily degradable carbo can be useful as a sensitive indicator of both soil biological degradation and microbial hot-spots indication. As a result, it was found that soil respiration activity was significantly higher (p <0.0001) in all controls, ranging between 30-60 vs. 11.5-23.7 μmol CO2 kg d.m.-1 h-1 for the arable soils. Dehydrogenase activity was significantly lower in the arable soil (down to 35-40% of the control values, p <0.001) varying depending on the soil type. The microbial biomass was also significantly higher at the non-cultivated soil (512-2807 vs. 416-1429 µg g-1 d.m., p <0.001), while easily degradable carbon ranged between 620-1209 mg kg-1 non-cultivated soil and 497-877 mg kg-1 arable soil (p <0.0001). It was demonstrated that agricultural practices affected soil properties by significantly reducing the levels of the studied parameters in relation to the control soils. The significant correlations of easily degradable carbon-respiration activity (ρ = 0.77*), easily degradable carbon-dehydrogenase activity (ρ = 0.42*), and easily degradable carbon-microbial biomass (ρ = 0.53*) reveal that easily degradable carbon is a novel, suitable factor indicative of soil biological degradation. It, therefore, could be used for evaluating the degree of soil degradation and for choosing a proper management procedure.

Terrestrial carbon turnover time constraints on future carbon cycle-climate feedback

NASA Astrophysics Data System (ADS)

Fan, N.; Carvalhais, N.; Reichstein, M.

2017-12-01

Understanding the terrestrial carbon cycle-climate feedback is essential to reduce the uncertainties resulting from the between model spread in prognostic simulations (Friedlingstein et al., 2006). One perspective is to investigate which factors control the variability of the mean residence times of carbon in the land surface, and how these may change in the future, consequently affecting the response of the terrestrial ecosystems to changes in climate as well as other environmental conditions. Carbon turnover time of the whole ecosystem is a dynamic parameter that represents how fast the carbon cycle circulates. Turnover time τ is an essential property for understanding the carbon exchange between the land and the atmosphere. Although current Earth System Models (ESMs), supported by GVMs for the description of the land surface, show a strong convergence in GPP estimates, but tend to show a wide range of simulated turnover times (Carvalhais, 2014). Thus, there is an emergent need of constraints on the projected response of the balance between terrestrial carbon fluxes and carbon stock which will give us more certainty in response of carbon cycle to climate change. However, the difficulty of obtaining such a constraint is partly due to lack of observational data on temporal change of terrestrial carbon stock. Since more new datasets of carbon stocks such as SoilGrid (Hengl, et al., 2017) and fluxes such as GPP (Jung, et al., 2017) are available, improvement in estimating turnover time can be achieved. In addition, previous study ignored certain aspects such as the relationship between τ and nutrients, fires, etc. We would like to investigate τ and its role in carbon cycle by combining observatinoal derived datasets and state-of-the-art model simulations.

Differential stimulation of neurotrophin release by the biocompatible nano-material (carbon nanotube) in primary cultured neurons.

PubMed

Kim, Yun Gi; Kim, Jong Wan; Pyeon, Hee Jang; Hyun, Jung Keun; Hwang, Ji-Young; Choi, Seong-Jun; Lee, Ja-Yeon; Deák, Ferenc; Kim, Hae-Won; Lee, Young Il

2014-01-01

In order to develop novel, effective therapies for central nervous system regeneration, it is essential to better understand the role of neurotrophic factors and to design, accordingly, better artificial scaffolds to support both neurite outgrowth and synapse formation. Both nerve growth factor and brain-derived neurotrophic factor are major factors in neural survival, development, synaptogenesis, and synaptic connectivity of primary cultured neurons. As a prime candidate coating material for such neural cultures, carbon nanotubes offer unique structural, mechanical, and electrical properties. In this study, carbon nanotubes coated glass-coverslips were used as the matrix of a primary neural culture system used to investigate the effects of carbon nanotubes on neurite outgrowth and nerve growth factor/brain-derived neurotrophic factor release and expression. For these purposes, we performed comparative analyses of primary cultured neurons on carbon nanotubes coated, non-coated, and Matrigel-coated coverslips. The morphological findings showed definite carbon nanotubes effects on the neurite outgrowths and synaptogenic figures in both cortical and hippocampal neurons when compared with the non-coated negative control. Although the carbon nanotubes did not change neurotrophin expression levels, it stimulated brain-derived neurotrophic factor release into the media from both types of neurons. Accordingly, we suggest a different mechanism of action between carbon nanotubes and Matrigel in relation to the specific neurotrophic factors. Since carbon nanotubes supply long-term extracellular molecular cues for the survival and neurite outgrowths of cultured neurons, the results from this study will contribute to an understanding of carbon nanotubes biological effects and provide new insight into their role in the secretion of neurotrophic factors.

Motor power factor controller with a reduced voltage starter

NASA Technical Reports Server (NTRS)

Nola, F. J. (Inventor)

1981-01-01

A power factor type motor controller is disclosed in which the conventional power factor constant voltage command signal is replaced during a starting interval with a graduated control voltage. This continuation-impart of a pending patent application (Serial No. 199, 765: Three Phase Factor Controller) provides a means for modifying the operation of the system for a motor start-up interval of 5 to 30 second. Using a ramp generators, an initial ramp-like signal replaces a constant power factor signal supplied by a potentiometer. The ramp-like signal is applied to a 15 terminal where it is summed with an operating power factor signal from phase detectors in order to obtain a control signal for ultimately controlling SCR devices. The SCR devices are turned on at an advancing rate with time responsive to the combination signal described rather than simply a function of a ramp-like signal alone.

Hydroclimatic Controls over Global Variations in Phenology and Carbon Flux

NASA Technical Reports Server (NTRS)

Koster, Randal; Walker, G.; Thornton, Patti; Collatz, G. J.

2012-01-01

The connection between phenological and hydroclimatological variations are quantified through joint analyses of global NDVI, LAI, and precipitation datasets. The global distributions of both NDVI and LAI in the warm season are strongly controlled by three quantities: mean annual precipitation, the standard deviation of annual precipitation, and Budyko's index of dryness. Upon demonstrating that these same basic (if biased) relationships are produced by a dynamic vegetation model (the dynamic vegetation and carbon storage components of the NCAR Community Land Model version 4 combined with the water and energy balance framework of the Catchment Land Surface Model of the NASA Global Modeling and Assimilation Office), we use the model to perform a sensitivity study focusing on how phenology and carbon flux might respond to climatic change. The offline (decoupled from the atmosphere) simulations show us, for example, where on the globe a given small increment in precipitation mean or variability would have the greatest impact on carbon uptake. The analysis framework allows us in addition to quantify the degree to which climatic biases in a free-running GCM are manifested as biases in simulated phenology.

Hydroclimatic Controls over Global Variations in Phenology and Carbon Flux

NASA Astrophysics Data System (ADS)

Koster, R. D.; Walker, G.; Thornton, P. E.; Collatz, G. J.

2012-12-01

The connection between phenological and hydroclimatological variations are quantified through joint analyses of global NDVI, LAI, and precipitation datasets. The global distributions of both NDVI and LAI in the warm season are strongly controlled by three quantities: mean annual precipitation, the standard deviation of annual precipitation, and Budyko's index of dryness. Upon demonstrating that these same basic (if somewhat biased) relationships are produced by a dynamic vegetation model (the dynamic vegetation and carbon storage components of the NCAR Community Land Model version 4 combined with the water and energy balance framework of the Catchment Land Surface Model of the NASA Global Modeling and Assimilation Office), we use the model to perform a sensitivity study focusing on how phenology and carbon flux might respond to climatic change. The offline (decoupled from the atmosphere) simulations show us, for example, where on the globe a given small increment in precipitation mean or variability would have the greatest impact on carbon uptake. The analysis framework allows us in addition to quantify the degree to which climatic biases in a free-running GCM are manifested as biases in simulated phenology.

Soil Carbon Decomposition: "Quality control" or logistic challenge?

NASA Astrophysics Data System (ADS)

Kleber, M.

2011-12-01

A long tradition of soil organic matter research has generated the belief that there is "stable" soil organic carbon, thought to be recalcitrant because molecular compounds such as aromatic rings and aliphatic chains are joined to polymeric macromolecules by processes of secondary syntheses. The Carbon-Quality Temperature (CQT) theory posits that such materials should be considered "low quality" substrates, because they would require large Arrhenius activation energies for full conversion to CO2. This, in turn, has generated the notion that recalcitrant organic matter should be more temperature sensitive to elevated temperatures than less complex, more "labile" soil organic matter. Yet the molecular properties of stable carbon are elusive - so far, it has not been possible to parameterize molecular recalcitrance in a context -independent fashion. Classic humic substances and even charcoal are readily broken down when placed in an environment where microorganisms with a suitable catabolic toolbox can resort to a plentiful supply of cometabolites and oxygen. At the same time we find labile substrates such as glucose to survive for decades when enclosed within soil aggregates. What then determines the temperature sensitivity of decomposition? Should the scientific community continue to hunt for some molecular proxy for organic matter quality (such as degree of polymerization, aromaticity, aqueous solubility etc) to predict the fate of soil organic carbon in a changing world? This contribution proposes a fundamentally different approach by treating soils as reaction vessels analogous to an industrial bioreactor. Soils are considered as capable of processing dead plant material in all its molecular variations. Decomposition is seen as constrained by environmental drivers, microbial ecology and community composition, and the physical structure of the soil environment. The hypotheses is put forward that, compared to variations in the logistic status of the soil reactor

Coupled Climate-Economy-Biosphere (CoCEB) model - Part 2: Deforestation control and investment in carbon capture and storage technologies

NASA Astrophysics Data System (ADS)

Ogutu, K. B. Z.; D'Andrea, F.; Ghil, M.; Nyandwi, C.; Manene, M. M.; Muthama, J. N.

2015-04-01

This study uses the global climate-economy-biosphere (CoCEB) model developed in Part 1 to investigate economic aspects of deforestation control and carbon sequestration in forests, as well as the efficiency of carbon capture and storage (CCS) technologies as policy measures for climate change mitigation. We assume - as in Part 1 - that replacement of one technology with another occurs in terms of a logistic law, so that the same law also governs the dynamics of reduction in carbon dioxide emission using CCS technologies. In order to take into account the effect of deforestation control, a slightly more complex description of the carbon cycle than in Part 1 is needed. Consequently, we add a biomass equation into the CoCEB model and analyze the ensuing feedbacks and their effects on per capita gross domestic product (GDP) growth. Integrating biomass into the CoCEB and applying deforestation control as well as CCS technologies has the following results: (i) low investment in CCS contributes to reducing industrial carbon emissions and to increasing GDP, but further investment leads to a smaller reduction in emissions, as well as in the incremental GDP growth; and (ii) enhanced deforestation control contributes to a reduction in both deforestation emissions and in atmospheric carbon dioxide concentration, thus reducing the impacts of climate change and contributing to a slight appreciation of GDP growth. This effect is however very small compared to that of low-carbon technologies or CCS. We also find that the result in (i) is very sensitive to the formulation of CCS costs, while to the contrary, the results for deforestation control are less sensitive.

Controllable Synthesis of Ordered Mesoporous Mo2C@Graphitic Carbon Core-Shell Nanowire Arrays for Efficient Electrocatalytic Hydrogen Evolution.

PubMed

Zhu, Jiahui; Yao, Yan; Chen, Zhi; Zhang, Aijian; Zhou, Mengyuan; Guo, Jun; Wu, Winston Duo; Chen, Xiao Dong; Li, Yanguang; Wu, Zhangxiong

2018-06-06

Mo 2 C is a possible substitute to Pt-group metals for electrocatalytic hydrogen evolution reaction (HER). Both support-free and carbon-supported Mo 2 C nanomaterials with improved HER performance have been developed. Herein, distinct from prior research, novel ordered mesoporous core-shell nanowires with Mo 2 C cores and ultrathin graphitic carbon (GC) shells are rationally synthesized and demonstrated to be excellent for HER. The synthesis is fulfilled via a hard-templating approach combining in situ carburization and localized carbon deposition. Phosphomolybdic acid confined in the SBA-15 template is first converted to MoO 2 , which is then in situ carburized to Mo 2 C nanowires with abundant surface defects. Simultaneously, GC layer (the thickness is down to ∼1.0 nm in most areas) is controlled to be locally deposited on the Mo 2 C surface because of its strong affinity with carbon and catalytic effect on graphitization. Removal of the template results in the Mo 2 C@GC core-shell nanowire arrays with the structural properties well-characterized. They exhibit excellent performance for HER with a low overpotential of 125 mV at 10 mA cm -2 , a small Tafel slope of 66 mV dec -1 , and an excellent stability in acidic electrolytes. The influences of several factors, especially the spatial configuration and relative contents of the GC and Mo 2 C components, on HER performance are elucidated with control experiments. The excellent HER performance of the mesoporous Mo 2 C@GC core-shell nanowire arrays originates from the rough Mo 2 C nanowires with diverse active sites and short charge-transfer paths and the ultrathin GC shells with improved surface area, electronic conductivity, and stabilizing effect on Mo 2 C.

Revised methane emissions factors and spatially distributed annual carbon fluxes for global livestock

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wolf, Julie; Asrar, Ghassem R.; West, Tristram O.

Background: Livestock play an important role in carbon cycling through consumption of biomass and emissions of methane. Recent research suggests that existing bottom-up inventories of livestock methane emissions in the US, such as those made using 2006 IPCC Tier 1 livestock emissions factors, are too low. This may be due to outdated information used to develop these emissions factors. In this study, we update information for cattle and swine by region, based on reported recent changes in animal body mass, feed quality and quantity, milk productivity, and management of animals and manure. We then use this updated information to calculatemore » new livestock methane emissions factors for enteric fermentation in cattle, and for manure management in cattle and swine.« less

Controls on the Origin and Cycling of Riverine Dissolved Inorganic Carbon in the Brazos River, Texas

NASA Astrophysics Data System (ADS)

Zeng, F.; Masiello, C. A.; Hockaday, W. C.

2008-12-01

Rivers are generally supersaturated in CO2 with respect to the atmosphere. However, there is little agreement on the sources and turnover times of excess CO2 in river waters. This is likely due to varying dominant controls on carbon sources (e.g. geologic setting, climate, land use, or human activities). In this study, we measured carbon isotopic signatures (δ13C and Δ14C) of riverine dissolved inorganic carbon (DIC), as well as solid state cross polarization/magic angle spinning (CP/MAS) 13C nuclear magnetic resonance (NMR) of particulate organic carbon (POC), to determine carbon sources fuelling respiration of the Brazos River in Texas. We found that sources of riverine CO2 varied significantly along the length of the Brazos. In the middle Brazos (between Graham and Waco), which is partially underlain by limestone, riverine DIC had average Δ14C of 74 ‰ and δ13C of -7.5 ‰, suggesting that riverine CO2 is derived almost entirely from contemporary carbon (less than 5 years old) with little evidence of carbonate input, probably due to the damming upstream of Waco. In the lower Brazos (downstream of Bryan), riverine DIC was highly depleted in 14C (average Δ14C = -148.5 ‰) and enriched in 13C (average δ13C= -9.32 ‰), indicative of the presence of old carbonate. Since there is no carbonate bedrock in contact with the river in this area, the most likely source of old carbonate is the shell used in road and building construction throughout the 19th century. Our results suggest that the effect of human activities superimposes and even surpasses the effect of natural controls (e.g. geologic setting and climate) on C cycling in the Brazos.

Characteristics of organic carbon accumulation in subtropical seagrass meadows

NASA Astrophysics Data System (ADS)

Tanaya, T.; Watanabe, K.; Yamamoto, S.; Hongo, C.; Kayanne, H.; Kuwae, T.

2016-02-01

The carbon sequestrated in marine ecosystems has been termed "blue carbon", and seagrass meadows are one of the most dominant blue carbon stocks. Globally, the major distribution sites of seagrass meadows are coral reef flats, where it is technically difficult to quantify organic carbon in carbonate sediments. Since blue carbon stocks have been estimated to date based on seagrass biomass and fine sediments (<1 mm), no studies have measured total carbon stocks, including coarse sediments (1> mm) in seagrass meadows. To solve this problem, we developed a new box corer which can facilitate to obtain the intact cores structured by both sediments and seagrass bodies. Using the core samples taken in subtropical seagrass meadows, located off Ishigaki Island, Japan, we measured total organic carbon mass (TOCmass) and stable isotope ratios (δ13C) of total sedimentary organic matter (SOM) and estimated their sources and controlling factors. The averaged TOCmass of top 15 cm SOM including living seagrasses was 940±480 gC/m2. The live seagrass biomass accounted for only 14±14wt%, whereas the dead biomass (>2 mm), coarse sediments (>1 mm except for dead plant structures >2 mm) and fine sediments (<1 mm) accounted for 3±4wt%, 19±13wt%, and 63±14wt%, respectively. The dead biomass and coarse sediments, which have not yet been included in the past estimations, accounted for about 22wt% of the averaged TOCmass. Total organic carbon content (TOC%) of mixture of the dead biomass, coarse sediments and fine sediments increased with increasing the live seagrass biomass (R = 0.66, n = 13, p = 0.014). The live seagrass biomass was one of the controlling factors of blue carbon stocks at the sites. Using a Bayesian isotopic mixing model, we estimated that the contribution of seagrass-derived carbon to total sedimentary organic carbon was about 70%. The enrichment of sediment organic carbon with increasing the live seagrass biomass was mainly due to the increase of seagrass

Analyzing the impact of climate and management factors on the productivity and soil carbon sequestration of poplar plantations.

PubMed

Wang, Dan; Fan, Jiazhi; Jing, Panpan; Cheng, Yong; Ruan, Honghua

2016-01-01

It is crucial to investigate how climate and management factors impact poplar plantation production and soil carbon sequestration interactively. We extracted above-ground net primary production (ANPP), climate and management factors from peer-reviewed journal articles and analyzed impact of management factor and climate on the mean annual increment (MAI) of poplar ANPP statistically. Previously validated mechanistic model (ED) is used to perform case simulations for managed poplar plantations under different harvesting rotations. The meta-analysis indicate that the dry matter MAI was 6.3 Mg ha(-1) yr(-1) (n=641, sd=4.9) globally, and 5.1 (n=292, sd=4.0), 8.1 (n=224, sd=4.7) and 4.4 Mg ha(-1) yr(-1) (n=125, sd=3.2) in Europe, the US and China, respectively. Poplar MAI showed a significant response to GDD, precipitation and planting density and formed a quadratic relationship with stand age. The low annual production for poplar globally was probably caused by suboptimal water availability, rotation length and planting density. SEM attributes the variance of poplar growth rate more to climate than to management effects. Case simulations indicated that longer rotation cycle significantly increased soil carbon storage. Findings of this work suggests that management factor of rotation cycle alone could have dramatic impact on the above ground growth, as well as on the soil carbon sequestration of poplar plantations and will be helpful to quantify the long-term carbon sequestration through short rotation plantation. The findings of this study are useful in guiding further research, policy and management decisions towards sustainable poplar plantations. Copyright © 2015 Elsevier Inc. All rights reserved.

Enhanced graphitization of carbon around carbon nanotubes during the formation of carbon nanotube/graphite composites by pyrolysis of carbon nanotube/polyaniline composites.

PubMed

Nam, Dong Hoon; Cha, Seung Il; Jeong, Yong Jin; Hong, Soon Hyung

2013-11-01

The carbon nanotubes (CNTs) are actively applied to the reinforcements for composite materials during last decade. One of the attempts is development of CNT/Carbon composites. Although there are some reports on the enhancement of mechanical properties by addition of CNTs in carbon or carbon fiber, it is far below the expectation. Considering the microstructure of carbon materials such as carbon fiber, the properties of them can be modified and enhanced by control of graphitization and alignment of graphene planes. In this study, enhanced graphitization of carbon has been observed the vicinity of CNTs during the pyrolysis of CNT/Polyaniline composites. As a result, novel types of composite, consisting of treading CNTs and coated graphite, can be fabricated. High-resolution transmission electron microscopy revealed a specific orientation relationship between the graphene layers and the CNTs, with an angle of 110 degrees between the layers and the CNT axis. The possibility of graphene alignment control in the carbon by the addition of CNTs is demonstrated.

Enhanced selectivity of zeolites by controlled carbon deposition

DOEpatents

Nenoff, Tina M.; Thoma, Steven G.; Kartin, Mutlu

2006-05-09

A method for carbonizing a zeolite comprises depositing a carbon coating on the zeolite pores by flowing an inert carrier gas stream containing isoprene through a regenerated zeolite at elevated temperature. The carbonized zeolite is useful for the separation of light hydrocarbon mixtures due to size exclusion and the differential adsorption properties of the carbonized zeolite.

Thermodynamically controlled preservation of organic carbon in floodplains

NASA Astrophysics Data System (ADS)

Boye, Kristin; Noël, Vincent; Tfaily, Malak M.; Bone, Sharon E.; Williams, Kenneth H.; Bargar, John R.; Fendorf, Scott

2017-06-01

Organic matter decomposition in soils and terrestrial sediments has a prominent role in the global carbon cycle. Carbon stocks in anoxic environments, such as wetlands and the subsurface of floodplains, are large and presumed to decompose slowly. The degree of microbial respiration in anoxic environments is typically thought to depend on the energetics of available terminal electron acceptors such as nitrate or sulfate; microbes couple the reduction of these compounds to the oxidation of organic carbon. However, it is also possible that the energetics of the organic carbon itself can determine whether it is decomposed. Here we examined water-soluble organic carbon by Fourier-transform ion-cyclotron-resonance mass spectrometry to compare the chemical composition and average nominal oxidation state of carbon--a metric reflecting whether microbial oxidation of organic matter is thermodynamically favourable--in anoxic (sulfidic) and oxic (non-sulfidic) floodplain sediments. We observed distinct minima in the average nominal oxidation state of water-soluble carbon in sediments exhibiting anoxic, sulfate-reducing conditions, suggesting preservation of carbon compounds with nominal oxidation states below the threshold that makes microbial sulfate reduction thermodynamically favourable. We conclude that thermodynamic limitations constitute an important complement to other mechanisms of carbon preservation, such as enzymatic restrictions and mineral association, within anaerobic environments.

EMISSION TEST REPORT, OMSS FIELD TEST ON CARBON INJECTION FOR MERCURY CONTROL

EPA Science Inventory

The report discusses results of a parametric evaluation of powdered activated carbon for control of mercury (Hg) emission from a municipal waste cornbustor (MWC) equipped with a lime spray dryer absorber/fabric filter (SD/FF). The primary test objectives were to evaluate the effe...

One ligand, two regulators and three binding sites: How KDPG controls primary carbon metabolism in Pseudomonas

PubMed Central

Fung, Rowena K. Y.; Grenga, Lucia; Trampari, Eleftheria; Pepe, Simona

2017-01-01

Effective regulation of primary carbon metabolism is critically important for bacteria to successfully adapt to different environments. We have identified an uncharacterised transcriptional regulator; RccR, that controls this process in response to carbon source availability. Disruption of rccR in the plant-associated microbe Pseudomonas fluorescens inhibits growth in defined media, and compromises its ability to colonise the wheat rhizosphere. Structurally, RccR is almost identical to the Entner-Doudoroff (ED) pathway regulator HexR, and both proteins are controlled by the same ED-intermediate; 2-keto-3-deoxy-6-phosphogluconate (KDPG). Despite these similarities, HexR and RccR control entirely different aspects of primary metabolism, with RccR regulating pyruvate metabolism (aceEF), the glyoxylate shunt (aceA, glcB, pntAA) and gluconeogenesis (pckA, gap). RccR displays complex and unusual regulatory behaviour; switching repression between the pyruvate metabolism and glyoxylate shunt/gluconeogenesis loci depending on the available carbon source. This regulatory complexity is enabled by two distinct pseudo-palindromic binding sites, differing only in the length of their linker regions, with KDPG binding increasing affinity for the 28 bp aceA binding site but decreasing affinity for the 15 bp aceE site. Thus, RccR is able to simultaneously suppress and activate gene expression in response to carbon source availability. Together, the RccR and HexR regulators enable the rapid coordination of multiple aspects of primary carbon metabolism, in response to levels of a single key intermediate. PMID:28658302

METHODOLOGIES FOR QUANTIFYING POLLUTION PREVENTION BENEFITS FROM LANDFILL GAS CONTROL AND UTILIZATION

EPA Science Inventory

The report describes developing emission factors for controlled primary pollutants (e.g., nonmethane organic compounds) and secondary air pollutants (e.g., carbon monoxide). The report addresses the following criteria air pollutants and greenhouse gases: carbon dioxide, carbon mo...

Emission factors of fine particulate matter, organic and elemental carbon, carbon monoxide, and carbon dioxide for four solid fuels commonly used in residential heating by the U.S. Navajo Nation.

PubMed

Champion, Wyatt M; Connors, Lea; Montoya, Lupita D

2017-09-01

Most homes in the Navajo Nation use wood as their primary heating fuel, often in combination with locally mined coal. Previous studies observed health effects linked to this solid-fuel use in several Navajo communities. Emission factors (EFs) for common fuels used by the Navajo have not been reported using a relevant stove type. In this study, two softwoods (ponderosa pine and Utah juniper) and two high-volatile bituminous coals (Black Mesa and Fruitland) were tested with an in-use residential conventional wood stove (homestove) using a modified American Society for Testing and Materials/U.S. Environmental Protection Agency (ASTM/EPA) protocol. Filter sampling quantified PM 2.5 (particulate matter with an aerodynamic diameter ≤2.5 μm) and organic (OC) and elemental (EC) carbon in the emissions. Real-time monitoring quantified carbon monoxide (CO), carbon dioxide (CO 2 ), and total suspended particles (TSP). EFs for these air pollutants were developed and normalized to both fuel mass and energy consumed. In general, coal had significantly higher mass EFs than wood for all pollutants studied. In particular, coal emitted, on average, 10 times more PM 2.5 than wood on a mass basis, and 2.4 times more on an energy basis. The EFs developed here were based on fuel types, stove design, and operating protocols relevant to the Navajo Nation, but they could be useful to other Native Nations with similar practices, such as the nearby Hopi Nation. Indoor wood and coal combustion is an important contributor to public health burdens in the Navajo Nation. Currently, there exist no emission factors representative of Navajo homestoves, fuels, and practices. This study developed emission factors for PM 2.5 , OC, EC, CO, and CO 2 using a representative Navajo homestove. These emission factors may be utilized in regional-, national-, and global-scale health and environmental models. Additionally, the protocols developed and results presented here may inform on-going stove design of

State and Regional Control of Geological Carbon Sequestration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reitze, Arnold; Durrant, Marie

2011-03-01

The United States has economically recoverable coal reserves of about 261 billion tons, which is in excess of a 250-­year supply based on 2009 consumption rates. However, in the near future the use of coal may be legally restricted because of concerns over the effects of its combustion on atmospheric carbon dioxide concentrations. Carbon capture and geologic sequestration offer one method to reduce carbon emissions from coal and other hydrocarbon energy production. While the federal government is providing increased funding for carbon capture and sequestration, recent congressional legislative efforts to create a framework for regulating carbon emissions have failed. However,more » regional and state bodies have taken significant actions both to regulate carbon and facilitate its capture and sequestration. This article explores how regional bodies and state government are addressing the technical and legal problems that must be resolved in order to have a viable carbon sequestration program. Several regional bodies have formed regulations and model laws that affect carbon capture and storage, and three bodies comprising twenty-three states—the Regional Greenhouse Gas Initiative, the Midwest Regional Greenhouse Gas Reduction Accord, and the Western Climate initiative—have cap-­and-trade programs in various stages of development. State property, land use and environmental laws affect the development and implementation of carbon capture and sequestration projects, and unless federal standards are imposed, state laws on torts and renewable portfolio requirements will directly affect the liability and viability of these projects. This paper examines current state laws and legislative efforts addressing carbon capture and sequestration.« less

Ultra-thin carbon-fiber paper fabrication and carbon-fiber distribution homogeneity evaluation method

NASA Astrophysics Data System (ADS)

Zhang, L. F.; Chen, D. Y.; Wang, Q.; Li, H.; Zhao, Z. G.

2018-01-01

A preparation technology of ultra-thin Carbon-fiber paper is reported. Carbon fiber distribution homogeneity has a great influence on the properties of ultra-thin Carbon-fiber paper. In this paper, a self-developed homogeneity analysis system is introduced to assist users to evaluate the distribution homogeneity of Carbon fiber among two or more two-value images of carbon-fiber paper. A relative-uniformity factor W/H is introduced. The experimental results show that the smaller the W/H factor, the higher uniformity of the distribution of Carbon fiber is. The new uniformity-evaluation method provides a practical and reliable tool for analyzing homogeneity of materials.

Factors influencing organic-horizon carbon pools in mixed-species stands of central Maine, USA

Treesearch

Joshua J. Puhlick; Shawn Fraver; Ivan J. Fernandez; Aaron R. Weiskittel; Laura S. Kenefic; Randy Kolka; Marie-Cecile Gruselle

2016-01-01

The overall goal of this study was to evaluate the correlation of multiple abiotic and biotic factors with organic-horizon (O-horizon) carbon (C) content on the Penobscot Experimental Forest in central Maine, USA. O-horizon samples were collected and their associated depths were recorded from stands managed with a range of silvicultural and harvesting treatments (i.e...

Anthropogenic and geomorphic controls on peatland dynamics in contrasting floodplain environments during the Holocene and its impact on carbon storage

NASA Astrophysics Data System (ADS)

Verstraeten, Gert; Broothaerts, Nils; Notebaert, Bastiaan

2016-04-01

Peatlands are an important store of carbon in terrestrial environments, and scientific interest in peatlands has increased strongly in the light of the recent global climatic changes. Much attention has been paid to peatland dynamics in extensive arctic and boreal wetlands or to blanket peat in temperate regions. Nevertheless, long-term dynamics of peat in alluvial wetlands in temperate regions remains largely underresearched. In this study, data from three contrasting environments were used to provide more insights in the anthropogenic and geomorphic controls on peatland dynamics. The results show a high variability in alluvial peatland dynamics between the different study sites. In the central Belgian Loess Belt, alluvial peatlands developed during the early Holocene but gradually disappeared from the Mid-Holocene onwards due to the gradual intensification of agricultural activities in the catchment and consequent higher sedimentation rates in the floodplain system. The end of peat growth is shown to be diachronous at catchment scale, ranging between 6500 and 500 cal a BP. The disappearance of the alluvial peatlands has important implications since it potentially reduces the storage of locally produced C. Nevertheless, it was shown that this reduced production of local C but was outbalanced by the burial of hillslope derived C. Also within the sandy catchments of the Belgian Campine region alluvial peatlands initiated in the early Holocene but, here, they abruptly disappeared in the Mid-Holocene before the onset of intense agricultural activities in the catchment. This suggests that for the sandy regions, anthropogenic impact on peatland dynamics is less important compared to natural factors. For these regions, the disappearance of alluvial peatland formation resulted in a sharp decline in alluvial carbon storage as there is no compensation through hillslope derived C input. For the upper Dee catchment in NE Scotland, Holocene carbon floodplain storage varies

Control of Effluent Gases from Solid Waste Processing using Impregnated Carbon Nanotubes

NASA Technical Reports Server (NTRS)

Li, Jing; Fisher, John; Wignarajah, Kanapathipillai

2005-01-01

One of the major problems associated with solid waste processing technologies is effluent contaminants that are released in gaseous forms from the processes. This is a concern in both biological as well as physicochemical solid waste processing. Carbon dioxide (CO2), the major gas released, does not present a serious problem and there are currently in place a number of flight-qualified technologies for CO2 removal. However, a number of other gases, in particular NOx, SO2, NH3, and various hydrocarbons (e.g. CH4) do present health hazards to the crew members in space habitats. In the present configuration of solid waste processing in the International Space Station (ISS), some of these gases are removed by the Trace Contaminant Control System (TCCS), demands a major resupply. Reduction of the resupply can be effective by using catalyst impregnated carbon nanotubes. For example, NO decomposition to N2 and O2 is thermodynamically favored. Data showing decomposition of NO on metal impregnated carbon nanotubes is presented. Comparisons are made of the existing TCCS systems with the carbon nanotube based technology for removing NOx based on mass/energy penalties.

Three approaches for estimating recovery factors in carbon dioxide enhanced oil recovery

USGS Publications Warehouse

Verma, Mahendra K.

2017-07-17

PrefaceThe Energy Independence and Security Act of 2007 authorized the U.S. Geological Survey (USGS) to conduct a national assessment of geologic storage resources for carbon dioxide (CO2) and requested the USGS to estimate the “potential volumes of oil and gas recoverable by injection and sequestration of industrial carbon dioxide in potential sequestration formations” (42 U.S.C. 17271(b)(4)). Geologic CO2 sequestration associated with enhanced oil recovery (EOR) using CO2 in existing hydrocarbon reservoirs has the potential to increase the U.S. hydrocarbon recoverable resource. The objective of this report is to provide detailed information on three approaches that can be used to calculate the incremental recovery factors for CO2-EOR. Therefore, the contents of this report could form an integral part of an assessment methodology that can be used to assess the sedimentary basins of the United States for the hydrocarbon recovery potential using CO2-EOR methods in conventional oil reservoirs.

A fungal transcription factor essential for starch degradation affects integration of carbon and nitrogen metabolism

DOE PAGES

Xiong, Yi; Wu, Vincent W.; Lubbe, Andrea; ...

2017-05-03

In Neurospora crassa, the transcription factor COL-26 functions as a regulator of glucose signaling and metabolism. Its loss leads to resistance to carbon catabolite repression. Here, we report that COL-26 is necessary for the expression of amylolytic genes in N. crassa and is required for the utilization of maltose and starch. Additionally, the Δcol-26 mutant shows growth defects on preferred carbon sources, such as glucose, an effect that was alleviated if glutamine replaced ammonium as the primary nitrogen source. This rescue did not occur when maltose was used as a sole carbon source. Transcriptome and metabolic analyses of the Δcol-26more » mutant relative to its wild type parental strain revealed that amino acid and nitrogen metabolism, the TCA cycle and GABA shunt were adversely affected. Phylogenetic analysis showed a single col-26 homolog in Sordariales, Ophilostomatales, and the Magnaporthales, but an expanded number of col-26 homologs in other filamentous fungal species. Deletion of the closest homolog of col-26 in Trichoderma reesei, bglR, resulted in a mutant with similar preferred carbon source growth deficiency, and which was alleviated if glutamine was the sole nitrogen source, suggesting conservation of COL-26 and BglR function. Our finding provides novel insight into the role of COL-26 for utilization of starch and in integrating carbon and nitrogen metabolism for balanced metabolic activities for optimal carbon and nitrogen distribution.« less

A fungal transcription factor essential for starch degradation affects integration of carbon and nitrogen metabolism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xiong, Yi; Wu, Vincent W.; Lubbe, Andrea

In Neurospora crassa, the transcription factor COL-26 functions as a regulator of glucose signaling and metabolism. Its loss leads to resistance to carbon catabolite repression. Here, we report that COL-26 is necessary for the expression of amylolytic genes in N. crassa and is required for the utilization of maltose and starch. Additionally, the Δcol-26 mutant shows growth defects on preferred carbon sources, such as glucose, an effect that was alleviated if glutamine replaced ammonium as the primary nitrogen source. This rescue did not occur when maltose was used as a sole carbon source. Transcriptome and metabolic analyses of the Δcol-26more » mutant relative to its wild type parental strain revealed that amino acid and nitrogen metabolism, the TCA cycle and GABA shunt were adversely affected. Phylogenetic analysis showed a single col-26 homolog in Sordariales, Ophilostomatales, and the Magnaporthales, but an expanded number of col-26 homologs in other filamentous fungal species. Deletion of the closest homolog of col-26 in Trichoderma reesei, bglR, resulted in a mutant with similar preferred carbon source growth deficiency, and which was alleviated if glutamine was the sole nitrogen source, suggesting conservation of COL-26 and BglR function. Our finding provides novel insight into the role of COL-26 for utilization of starch and in integrating carbon and nitrogen metabolism for balanced metabolic activities for optimal carbon and nitrogen distribution.« less

A fungal transcription factor essential for starch degradation affects integration of carbon and nitrogen metabolism

PubMed Central

Xiong, Yi; Qin, Lina; Kennedy, Megan; Bauer, Diane; Barry, Kerrie; Northen, Trent R.; Grigoriev, Igor V.

2017-01-01

In Neurospora crassa, the transcription factor COL-26 functions as a regulator of glucose signaling and metabolism. Its loss leads to resistance to carbon catabolite repression. Here, we report that COL-26 is necessary for the expression of amylolytic genes in N. crassa and is required for the utilization of maltose and starch. Additionally, the Δcol-26 mutant shows growth defects on preferred carbon sources, such as glucose, an effect that was alleviated if glutamine replaced ammonium as the primary nitrogen source. This rescue did not occur when maltose was used as a sole carbon source. Transcriptome and metabolic analyses of the Δcol-26 mutant relative to its wild type parental strain revealed that amino acid and nitrogen metabolism, the TCA cycle and GABA shunt were adversely affected. Phylogenetic analysis showed a single col-26 homolog in Sordariales, Ophilostomatales, and the Magnaporthales, but an expanded number of col-26 homologs in other filamentous fungal species. Deletion of the closest homolog of col-26 in Trichoderma reesei, bglR, resulted in a mutant with similar preferred carbon source growth deficiency, and which was alleviated if glutamine was the sole nitrogen source, suggesting conservation of COL-26 and BglR function. Our finding provides novel insight into the role of COL-26 for utilization of starch and in integrating carbon and nitrogen metabolism for balanced metabolic activities for optimal carbon and nitrogen distribution. PMID:28467421

40 CFR 721.2084 - Carbon oxyfluoride (Carbonic difluoride).

Code of Federal Regulations, 2011 CFR

2011-07-01

... and significant new use subject to reporting. (1) The chemical substance carbon oxyfluoride (CAS No... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Carbon oxyfluoride (Carbonic...) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for...

Landform position and charring conditions control decomposition of soil organic matter and pyrogenic carbon

NASA Astrophysics Data System (ADS)

Abney, R.; Jin, L.; Berhe, A. A.

2017-12-01

Wildfire is a significant global control on both ecosystem properties and biogeochemical cycling, and wildfires are projected to increase in both size and severity with continued climate change. Post-fire, charred biomass, or pyrogenic carbon, is left behind as a significant, relatively slow-cycling component of the soil organic matter pool. Pyrogenic carbon has a turnover time on the centennial scale, and previous research has demonstrated that it is highly susceptible to erosion. However, the interaction of the roles of landform position and combustion temperature remains unexplored. We collected live Pinus jeffreyi bark and charred it under combustion conditions at three temperatures (200°C, 350°C, and 500°C). The charred bark was mixed with soil collected from both eroding and depositional landform positions and incubated for six months. Throughout this incubation, microbial respiration was monitored via collection of CO2, and cumulative respiration was fitted using both single- and multi-pool exponential models. Overall, respiration was highest in soil and char mixtures in the depositional landform positions. Pyrogenic carbon concentrations, as determined by the Kurth Mackenzie Deluca method, declined only slightly in the 200°C char mixed with the depositional soil. Scanning electron microscopy images of the chars before and after incubation illustrate some incorporation of soil organic matter into the structures of the char, and some breakdown of the physical structures of the char. Altogether, the lower temperature chars mixed with the soil from the depositional landform position had the highest decomposition rates, which suggests the role that landform position may play on the stability of pyrogenic carbon at the landscape scale. Furthermore, this implies that the post-fire erosional re-distribution of pyrogenic carbon may act as a significant control of its long-term stabilization in soil and landscape-scale soil carbon stocks.

Fabrication of thickness controllable free-standing sandwich-structured hybrid carbon film for high-rate and high-power supercapacitor

PubMed Central

Wei, Helin; Wei, Sihang; Tian, Weifeng; Zhu, Daming; Liu, Yuhao; Yuan, Lili; Li, Xin

2014-01-01

Hybrid carbon films composed of graphene film and porous carbon film may give full play to the advantages of both carbon materials, and have great potential for application in energy storage and conversion devices. Unfortunately, there are very few reports on fabrication of hybrid carbon films. Here we demonstrate a simple approach to fabricate free-standing sandwich-structured hybrid carbon film composed of porous amorphous carbon film and multilayer graphene film by chemical vapor deposition in a controllable and scalable way. Hybrid carbon films reveal good electrical conductivity, excellent flexibility, and good compatibility with substrate. Supercapacitors assembled by hybrid carbon films exhibit ultrahigh rate capability, wide frequency range, good capacitance performance, and high-power density. Moreover, this approach may provide a general path for fabrication of hybrid carbon materials with different structures by using different metals with high carbon solubility, and greatly expands the application scope of carbon materials. PMID:25394410

Semi-coke briquettes: towards reducing emissions of primary PM2.5, particulate carbon, and carbon monoxide from household coal combustion in China

NASA Astrophysics Data System (ADS)

Li, Qing; Li, Xinghua; Jiang, Jingkun; Duan, Lei; Ge, Su; Zhang, Qi; Deng, Jianguo; Wang, Shuxiao; Hao, Jiming

2016-01-01

Direct household use of unprocessed raw coals for cooking and heating without any air pollution control device has caused serious indoor and outdoor environment problems by emitting particulate matter (PM) and gaseous pollutants. This study examined household emission reduction by switching from unprocessed bituminous and anthracite coals to processed semi-coke briquettes. Two typical stoves were used to test emission characteristics when burning 20 raw coal samples commonly used in residential heating activities and 15 semi-coke briquette samples which were made from bituminous coals by industrial carbonization treatment. The carbonization treatment removes volatile compounds from raw coals which are the major precursors for PM formation and carbon emission. The average emission factors of primary PM2.5, elemental carbon, organic carbon, and carbon monoxide for the tested semi-coke briquettes are much lower than those of the tested raw coals. Based on the current coal consumption data in China, switching to semi-coke briquettes can reduce average emission factors of these species by about 92%, 98%, 91%, and 34%, respectively. Additionally, semi-coke briquette has relatively lower price and higher burnout ratio. The replacement of raw coals with semi-coke briquettes is a feasible path to reduce pollution emissions from household activities.

Semi-coke briquettes: towards reducing emissions of primary PM2.5, particulate carbon, and carbon monoxide from household coal combustion in China

PubMed Central

Li, Qing; Li, Xinghua; Jiang, Jingkun; Duan, Lei; Ge, Su; Zhang, Qi; Deng, Jianguo; Wang, Shuxiao; Hao, Jiming

2016-01-01

Direct household use of unprocessed raw coals for cooking and heating without any air pollution control device has caused serious indoor and outdoor environment problems by emitting particulate matter (PM) and gaseous pollutants. This study examined household emission reduction by switching from unprocessed bituminous and anthracite coals to processed semi-coke briquettes. Two typical stoves were used to test emission characteristics when burning 20 raw coal samples commonly used in residential heating activities and 15 semi-coke briquette samples which were made from bituminous coals by industrial carbonization treatment. The carbonization treatment removes volatile compounds from raw coals which are the major precursors for PM formation and carbon emission. The average emission factors of primary PM2.5, elemental carbon, organic carbon, and carbon monoxide for the tested semi-coke briquettes are much lower than those of the tested raw coals. Based on the current coal consumption data in China, switching to semi-coke briquettes can reduce average emission factors of these species by about 92%, 98%, 91%, and 34%, respectively. Additionally, semi-coke briquette has relatively lower price and higher burnout ratio. The replacement of raw coals with semi-coke briquettes is a feasible path to reduce pollution emissions from household activities. PMID:26782059

Viscosity controlled magma-carbonate interaction: a comparison of Mt. Vesuvius (Italy) and Mt. Merapi (Indonesia).

NASA Astrophysics Data System (ADS)

Blythe, L. S.; Misiti, V.; Masotta, M.; Taddeucci, J.; Freda, C.; Troll, V. R.; Deegan, F. M.; Jolis, E. M.

2012-04-01

Magma-carbonate interaction is increasingly seen as a viable and extremely important cause of magma contamination, and the generation of a crustally sourced CO2 phase (Goff et al., 2001; Freda et al., 2010). Even though the process is well recognized at certain volcanoes e.g. Popocatépetl, (Mexico); Merapi, (Indonesia); and Colli Albani, (Italy) (Goff et al., 2001; Deegan et al., 2010; Freda et al., 2010), neither the kinetics of carbonate assimilation nor its consequences for controlling the explosivity of eruptions have been constrained. Here we show the results of magma-carbonate interaction experiments conducted at 1200 °C and 0.5 GPa for varying durations (0 s, 60 s, 90 s and 300 s) for the Mt. Merapi (Indonesia) and Mt. Vesuvius (Italy) volcanic systems. We performed experiments using glassy starting materials specific to each volcano (shoshonite for Mt. Vesuvius, basaltic-andesite for Mt. Merapi) with different degrees of hydration (anhydrous vs hydration with ~ 2 wt % water) and using carbonate fragments of local origin; see Deegan et al., (2010) and Jolis et al., (2011). Experimental products include a gas phase (CO2-rich) and two melt phases, one pristine (Ca-normal) and one contaminated (Ca-rich) separated by a 'contamination front' which propagates outwards from the carbonate clast. Vesicles appear to nucleate in the contaminated glass and then migrate into the pristine one. Both contamination front propagation and bubble migration away from the carbonate are slower in anhydrous basaltic-andesite (Merapi anhydrous series) than in hydrated basaltic-andesite and shoshonite (Merapi and Vesuvius hydrated series), suggesting that assimilation speed is strongly controlled by the degree of hydration and the SiO2 content, both of which influence melt viscosity and hence diffusivity. As the carbonate dissolution proceeds in our experiments, initially dissolved and eventually exsolved CO2 builds up in the contaminated Ca-rich melt phase. Once melt volatile

FULL SCALE BIOREACTOR LANDFILL FOR CARBON SEQUESTRATION AND GREENHOUSE EMISSION CONTROL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ramin Yazdani; Jeff Kieffer; Heather Akau

2003-08-01

The Yolo County Department of Planning and Public Works is constructing a full-scale bioreactor landfill as a part of the Environmental Protection Agency's (EPA) Project XL program to develop innovative approaches for carbon sequestration and greenhouse emission control. The overall objective is to manage landfill solid waste for rapid waste decomposition and maximum landfill gas generation and capture for carbon sequestration and greenhouse emission control. Waste decomposition is accelerated by improving conditions for either the aerobic or anaerobic biological processes and involves circulating controlled quantities of liquid (leachate, groundwater, gray water, etc.), and, in the aerobic process, large volumes ofmore » air. The first phase of the project entails the construction of a 12-acre module that contains a 6-acre anaerobic cell, a 3.5-acre anaerobic cell, and a 2.5-acre aerobic cell at the Yolo County Central Landfill near Davis, California. The cells are highly instrumented to monitor bioreactor performance. Liquid addition has commenced in the 3.5-acre anaerobic cell and the 6-acre anaerobic cell. Construction of the 2.5-acre aerobic cell is nearly complete with only the biofilter remaining and is scheduled to be complete by the end of August 2003. The current project status and preliminary monitoring results are summarized in this report.« less

FULL SCALE BIOREACTOR LANDFILL FOR CARBON SEQUESTRATION AND GREENHOUSE EMISSION CONTROL

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ramin Yazdani; Jeff Kieffer; Heather Akau

2003-12-01

The Yolo County Department of Planning and Public Works is constructing a full-scale bioreactor landfill as a part of the Environmental Protection Agency's (EPA) Project XL program to develop innovative approaches for carbon sequestration and greenhouse emission control. The overall objective is to manage landfill solid waste for rapid waste decomposition and maximum landfill gas generation and capture for carbon sequestration and greenhouse emission control. Waste decomposition is accelerated by improving conditions for either the aerobic or anaerobic biological processes and involves circulating controlled quantities of liquid (leachate, groundwater, gray water, etc.), and, in the aerobic process, large volumes ofmore » air. The first phase of the project entails the construction of a 12-acre module that contains a 6-acre anaerobic cell, a 3.5-acre anaerobic cell, and a 2.5-acre aerobic cell at the Yolo County Central Landfill near Davis, California. The cells are highly instrumented to monitor bioreactor performance. Liquid addition has commenced in the 3.5-acre anaerobic cell and the 6-acre anaerobic cell. Construction of the 2.5-acre aerobic cell and biofilter has been completed. The remaining task to be completed is to test the biofilter prior to operation, which is currently anticipated to begin in January 2004. The current project status and preliminary monitoring results are summarized in this report.« less

Ecosystem Carbon Storage in Alpine Grassland on the Qinghai Plateau

PubMed Central

Liu, Shuli; Zhang, Fawei; Du, Yangong; Guo, Xiaowei; Lin, Li; Li, Yikang; Li, Qian; Cao, Guangmin

2016-01-01

The alpine grassland ecosystem can sequester a large quantity of carbon, yet its significance remains controversial owing to large uncertainties in the relative contributions of climate factors and grazing intensity. In this study we surveyed 115 sites to measure ecosystem carbon storage (both biomass and soil) in alpine grassland over the Qinghai Plateau during the peak growing season in 2011 and 2012. Our results revealed three key findings. (1) Total biomass carbon density ranged from 0.04 for alpine steppe to 2.80 kg C m-2 for alpine meadow. Median soil organic carbon (SOC) density was estimated to be 16.43 kg C m-2 in alpine grassland. Total ecosystem carbon density varied across sites and grassland types, from 1.95 to 28.56 kg C m-2. (2) Based on the median estimate, the total carbon storage of alpine grassland on the Qinghai Plateau was 5.14 Pg, of which 94% (4.85 Pg) was soil organic carbon. (3) Overall, we found that ecosystem carbon density was affected by both climate and grazing, but to different extents. Temperature and precipitation interaction significantly affected AGB carbon density in winter pasture, BGB carbon density in alpine meadow, and SOC density in alpine steppe. On the other hand, grazing intensity affected AGB carbon density in summer pasture, SOC density in alpine meadow and ecosystem carbon density in alpine grassland. Our results indicate that grazing intensity was the primary contributing factor controlling carbon storage at the sites tested and should be the primary consideration when accurately estimating the carbon storage in alpine grassland. PMID:27494253

Ecosystem Carbon Storage in Alpine Grassland on the Qinghai Plateau.

PubMed

Liu, Shuli; Zhang, Fawei; Du, Yangong; Guo, Xiaowei; Lin, Li; Li, Yikang; Li, Qian; Cao, Guangmin

2016-01-01

The alpine grassland ecosystem can sequester a large quantity of carbon, yet its significance remains controversial owing to large uncertainties in the relative contributions of climate factors and grazing intensity. In this study we surveyed 115 sites to measure ecosystem carbon storage (both biomass and soil) in alpine grassland over the Qinghai Plateau during the peak growing season in 2011 and 2012. Our results revealed three key findings. (1) Total biomass carbon density ranged from 0.04 for alpine steppe to 2.80 kg C m-2 for alpine meadow. Median soil organic carbon (SOC) density was estimated to be 16.43 kg C m-2 in alpine grassland. Total ecosystem carbon density varied across sites and grassland types, from 1.95 to 28.56 kg C m-2. (2) Based on the median estimate, the total carbon storage of alpine grassland on the Qinghai Plateau was 5.14 Pg, of which 94% (4.85 Pg) was soil organic carbon. (3) Overall, we found that ecosystem carbon density was affected by both climate and grazing, but to different extents. Temperature and precipitation interaction significantly affected AGB carbon density in winter pasture, BGB carbon density in alpine meadow, and SOC density in alpine steppe. On the other hand, grazing intensity affected AGB carbon density in summer pasture, SOC density in alpine meadow and ecosystem carbon density in alpine grassland. Our results indicate that grazing intensity was the primary contributing factor controlling carbon storage at the sites tested and should be the primary consideration when accurately estimating the carbon storage in alpine grassland.

C isotope fractionation during heterotrophic activity driven carbonate precipitation

NASA Astrophysics Data System (ADS)

Balci, Nurgul; Demirel, Cansu

2016-04-01

Stable carbon isotopic fractionation during carbonate precipitation induced by environmentally enriched heterotrophic halophilic microorganims was experimentally investigated under various salinity (% 4.5, %8, %15) conditions at 30 °C. Halophilic heterotrophic microorganims were enriched from a hypersaline Lake Acigöl located in SW Turkey (Balci et al.,2015) and later used for the precipitation experiments (solid and liquid medium). The carbonate precipitates had relatively high δ13C values (-4.3 to -16.9 ‰) compared to the δ13C values of the organic compounds that ranged from -27.5 to -25.4 ‰. At salinity of 4.5 % δ13C values of carbonate ranged from -4.9 ‰ to -10.9 ‰ with a 13C-enrichment factor of +20 to +16 ‰ higher than the δ13C values of the associated DOC (-27.5) . At salinity 8 % δ13C values of carbonate ranged from -16.3 ‰ to -11.7 ‰ with a 13C-enrichment factor of+11.3 to+15.9 ‰ higher than the δ13C values of the associated DOC. The respected values for 15 % salinity ranged from -12.3 ‰ to -9.7 ‰ with a 13C-enrichment factor of +15.2 to+16.8 ‰ higher than the δ13C values of the associated DOC. The carbonate precipitates produced in the solid medium are more enriched in 13C relative to liquid culture experiments. These results suggest that the carbon in the solid was derived from both the bacterial oxidation of organic compounds in the medium and from the atmospheric CO2. A solid medium used in the experiments may have suppressed convective and advective mass transport favouring diffusion-controlled system. This determination suggests that the rate and equilibration of CO2 exchange with the atmosphere is the major control on C isotope composition of carbonate minerals precipitated in the experiments. Key words: Lake Acıgöl, halophilic bacteria, carbonate biomineralization, C isotopes References Nurgul Balci, Meryem Menekşe, Nevin Gül Karagüler, M. Şeref Sönmez,Patrick Meister 2015.Reproducing authigenic carbonate

Associated factors of tooth wear among Malaysian 16-year-olds: a case-control study in Kota Bharu, Kelantan.

PubMed

Saerah, N B; Mastura, N; bin Ismail, A R; Sadiq, M A

2012-03-01

To determine the associated factors of tooth wear (TW) among 16-year-old school children. A random selection of secondary school children from 8 government secondary schools in Kota Bharu, Kelantan, Malaysia, participated in this case-control study. The Smith and Knight Tooth Wear Index and WHO criteria were used to chart tooth wear and dental caries respectively. Saliva analyses used standards recommended by GC Asia Dental. Self-administered questionnaire provided socio-demographic profile of the family, general knowledge of tooth wear, oral hygiene, food and drinks practices and other associated variables for tooth wear. Analysis using multiple logistic regression was performed. Of the 576 children sampled, 40% of the 460 controls were male as were 57% of the 116 in the case group. Multivariate analysis showed gender, monthly household income, carbonated drinks, caries experience, pool swimming, duration of intake of orange juice and hydration rate and viscosity were significantly associated with wear. The factors associated with tooth wear were similar to those encountered in other studies. Oral health promotion activities should emphasise those factors which can be changed. The erosive potential of some foods and drinks require further investigation.

Environmental controls on soil organic carbon and nitrogen stocks in the high-altitude arid western Qinghai-Tibetan Plateau permafrost region

NASA Astrophysics Data System (ADS)

Wu, Xiaodong; Zhao, Lin; Fang, Hongbing; Zhao, Yuguo; Smoak, Joseph M.; Pang, Qiangqiang; Ding, Yongjian

2016-01-01

While permafrost in the circum-Artic has great influence on soil organic carbon (SOC) and total nitrogen (TN) stocks, this might not be the case in low-latitude arid permafrost regions. We test this hypothesis in the western Qinghai-Tibetan Plateau (QTP) permafrost region. Fifty-nine soil profiles were analyzed to examine the SOC and TN distribution and the controlling factors in western QTP, which is a desert steppe ecoregion. Mean stocks of SOC (5.29 kg m-2) and TN (0.56 kg m-2) for the top 200 cm in this area were lower than those of the east QTP and circum-Arctic regions. The SOC and TN stocks under vegetative cover with permafrost conditions were significantly higher than those of desert conditions. The SOC and TN stocks for the layers of different depths were related to the content of clay, silt, and moisture. Although the active layer thickness (ALT) had a significant negative correlation to soil moisture, the ALT explained little or no variance in the SOC and TN stocks. The results showed that in the vast permafrost regions of the western QTP, the SOC and TN stocks are very low, and the main controlling factors for the SOC and TN are soil texture, moisture, and vegetation type. The SOC pool in this area may not be as vulnerable to degradation associated with climate warming and thus not emit greenhouse gases at the same rate as other permafrost regions. The different response of the SOC in this region should be considered in carbon cycling models.

Controllable synthesis of nitrogen-doped hollow mesoporous carbon spheres using ionic liquids as template for supercapacitors

NASA Astrophysics Data System (ADS)

Chen, Aibing; Li, Yunqian; Liu, Lei; Yu, Yifeng; Xia, Kechan; Wang, Yuying; Li, Shuhui

2017-01-01

We have demonstrated a facile and controllable synthesis of monodispersed nitrogen-doped hollow mesoporous carbon spheres (N-HMCSs) using resorcinol/formaldehyde resin as a carbon precursor, tetraethyl orthosilicate as a structure-assistant agent, ionic liquids (ILs) as soft template, partial carbon sources, and nitrogen sources. The sizes and the architectures including hollow and yolk-shell of resultant carbon spheres can be efficiently controlled through the adjustment of the content of ILs. Alkyl chain length of the ILs also has an important effect on the formation of N-HMCSs. With proper alkyl chain length and content of ILs, the resultant N-HMCSs show monodispersed hollow spheres with high surface areas (up to 1158 m2 g-1), large pore volumes (up to 1.70 cm3 g-1), and uniform mesopore size (5.0 nm). Combining the hollow mesoporous structure, high porosity, large surface area, and nitrogen functionality, the as-synthesized N-HMCSs have good supercapacitor performance with good capacitance (up to 159 F g-1) and favorable capacitance retention (88% capacitive retention after 5000 cycles).

Wood phenology, not carbon input, controls the interannual variability of wood growth in a temperate oak forest.

PubMed

Delpierre, Nicolas; Berveiller, Daniel; Granda, Elena; Dufrêne, Eric

2016-04-01

Although the analysis of flux data has increased our understanding of the interannual variability of carbon inputs into forest ecosystems, we still know little about the determinants of wood growth. Here, we aimed to identify which drivers control the interannual variability of wood growth in a mesic temperate deciduous forest. We analysed a 9-yr time series of carbon fluxes and aboveground wood growth (AWG), reconstructed at a weekly time-scale through the combination of dendrometer and wood density data. Carbon inputs and AWG anomalies appeared to be uncorrelated from the seasonal to interannual scales. More than 90% of the interannual variability of AWG was explained by a combination of the growth intensity during a first 'critical period' of the wood growing season, occurring close to the seasonal maximum, and the timing of the first summer growth halt. Both atmospheric and soil water stress exerted a strong control on the interannual variability of AWG at the study site, despite its mesic conditions, whilst not affecting carbon inputs. Carbon sink activity, not carbon inputs, determined the interannual variations in wood growth at the study site. Our results provide a functional understanding of the dependence of radial growth on precipitation observed in dendrological studies. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

Steady- and non-steady-state carbonate-silicate controls on atmospheric CO2

USGS Publications Warehouse

Sundquist, E.T.

1991-01-01

Two contrasting hypotheses have recently been proposed for the past long-term relation between atmospheric CO2 and the carbonate-silicate geochemical cycle. One approach (Berner, 1990) suggests that CO2 levels have varied in a manner that has maintained chemical weathering and carbonate sedimentation at a steady state with respect to tectonically controlled decarbonation reactions. A second approach (Raymo et al., 1988), applied specificlly to the late Cenozoic, suggests a decrease in CO2 caused by an uplift-induced increase in chemical weathering, without regard to the rate of decarbonation. According to the steady-state (first) hypothesis, increased weathering and carbonate sedimentation are generally associated with increasing atmospheric CO2, whereas the uplift (second) hypothesis implies decreasing CO2 under the same conditions. An ocean-atmosphere-sediment model has been used to assess the response of atmospheric CO2 and carbonate sedimentation to global perturbations in chemical weathering and decarbonation reactions. Although this assessment is theoretical and cannot yet be related to the geologic record, the model simulations compare steady-state and non-steady-state carbonate-silicate cycle response. The e-fold response time of the 'CO2-weathering' feedback mechanism is between 300 and 400 ka. The response of carbonate sedimentation is much more rapid. These response times provide a measure of the strength of steady-state assumptions, and imply that certain systematic relations are sustained throughout steady-state and non-steady-state scenarios for the carbonate-silicate cycle. The simulations suggest that feedbacks can maintain the system near a steady state, but that non-steady-state effects may contribute to long-term trends. The steady-state and uplift hypotheses are not necessarily incompatible over time scales of a few million years. ?? 1991.

Nanoscale hybrid systems based on carbon nanotubes for biological sensing and control

PubMed Central

Cho, Youngtak; Shin, Narae; Kim, Daesan; Park, Jae Yeol

2017-01-01

This paper provides a concise review on the recent development of nanoscale hybrid systems based on carbon nanotubes (CNTs) for biological sensing and control. CNT-based hybrid systems have been intensively studied for versatile applications of biological interfaces such as sensing, cell therapy and tissue regeneration. Recent advances in nanobiotechnology not only enable the fabrication of highly sensitive biosensors at nanoscale but also allow the applications in the controls of cell growth and differentiation. This review describes the fabrication methods of such CNT-based hybrid systems and their applications in biosensing and cell controls. PMID:28188158

Evaluation of statistical protocols for quality control of ecosystem carbon dioxide fluxes

Treesearch

Jorge F. Perez-Quezada; Nicanor Z. Saliendra; William E. Emmerich; Emilio A. Laca

2007-01-01

The process of quality control of micrometeorological and carbon dioxide (CO2) flux data can be subjective and may lack repeatability, which would undermine the results of many studies. Multivariate statistical methods and time series analysis were used together and independently to detect and replace outliers in CO2 flux...

Development of a Model of Geophysical and Geochemical Controls on Abiotic Carbon Cycling on Earth-Like Planets

NASA Astrophysics Data System (ADS)

Neveu, M.; Felton, R.; Domagal-Goldman, S. D.; Desch, S. J.; Arney, G. N.

2017-12-01

About 20 Earth-sized planets (0.6-1.6 Earth masses and radii) have now been discovered beyond our solar system [1]. Although such planets are prime targets in the upcoming search for atmospheric biosignatures, their composition, geology, and climate are essentially unconstrained. Yet, developing an understanding of how these factors influence planetary evolution through time and space is essential to establishing abiotic backgrounds against which any deviations can provide evidence for biological activity. To this end, we are building coupled geophysical-geochemical models of abiotic carbon cycling on such planets. Our models are controlled by atmospheric factors such as temperature and composition, and compute interior inputs to atmospheric species. They account for crustal weathering, ocean-atmosphere equilibria, and exchange with the deep interior as a function of planet composition and size (and, eventually, age).Planets in other solar systems differ from the Earth not only in their bulk physical properties, but also likely in their bulk chemical composition [2], which influences key parameters such as the vigor of mantle convection and the near-surface redox state. Therefore, simulating how variations in such parameters affect carbon cycling requires us to simulate the above processes from first principles, rather than by using arbitrary parameterizations derived from observations as is often done with models of carbon cycling on Earth [3] or extrapolations thereof [4]. As a first step, we have developed a kinetic model of crustal weathering using the PHREEQC code [5] and kinetic data from [6]. We will present the ability of such a model to replicate Earth's carbon cycle using, for the time being, parameterizations for surface-interior-atmosphere exchange processes such as volcanism (e.g., [7]).[1] exoplanet.eu, 7/28/2017.[2] Young et al. (2014) Astrobiology 14, 603-626.[3] Lerman & Wu (2008) Kinetics of Global Geochemical Cycles. In Kinetics of Water

The LysR-type transcription factor PacR is a global regulator of photosynthetic carbon assimilation in Anabaena.

PubMed

Picossi, Silvia; Flores, Enrique; Herrero, Antonia

2015-09-01

Cyanobacteria perform water-splitting photosynthesis and are important primary producers impacting the carbon and nitrogen cycles at global scale. They fix CO2 through ribulose-bisphosphate carboxylase/oxygenase (RuBisCo) and have evolved a distinct CO2 concentrating mechanism (CCM) that builds high CO2 concentrations in the vicinity of RuBisCo favouring its carboxylase activity. Filamentous cyanobacteria such as Anabaena fix CO2 in photosynthetic vegetative cells, which donate photosynthate to heterocysts that rely on a heterotrophic metabolism to fix N2 . CCM elements are induced in response to inorganic carbon limitation, a cue that exposes the photosynthetic apparatus to photodamage by over-reduction. An Anabaena mutant lacking the LysR-type transcription factor All3953 grew poorly and dies under high light. The rbcL operon encoding RuBisCo was induced upon carbon limitation in the wild type but not in the mutant. ChIP-Seq analysis was used to globally identify All3953 targets under carbon limitation. Targets include, besides rbcL, genes encoding CCM elements, photorespiratory pathway- photosystem- and electron transport-related components, and factors, including flavodiiron proteins, with a demonstrated or putative function in photoprotection. Quantitative reverse transcription polymerase chain reaction analysis of selected All3953 targets showed regulation in the wild type but not in the mutant. All3953 (PacR) is a global regulator of carbon assimilation in an oxygenic photoautotroph. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

Discrimination factors of carbon and nitrogen stable isotopes from diet to hair and scat in captive tigers (Panthera tigris) and snow leopards (Uncia uncia).

PubMed

Montanari, Shaena; Amato, George

2015-06-15

In order to use stable isotope ratio values obtained from wild animal tissues, we must accurately calculate the differences in isotope ratios between diet and consumer (δtissue - δdiet). These values, called trophic discrimination factors (TDFs, denoted with ∆), are necessary for stable isotope ecology studies and are best calculated in controlled environments. Scat, hair, and diet samples were collected from captive tigers (n = 8) and snow leopards (n = 10) at the Bronx Zoo. The isotope ratios of carbon and nitrogen, the two most commonly used in ecological studies, of the samples were measured by continuous-flow isotope ratio mass spectrometry. The trophic discrimination factors were calculated for both carbon (δ(13)C values) and nitrogen (δ(15)N values). It was found that the only significant TDFs in this study were diet-hair, ∆(13)CHair, for snow leopards (5.97 ± 1.25‰) and tigers (6.45 ± 0.54‰), and diet-scat, ∆(15)NScat, in snow leopards (2.49 ± 1.30‰). The other mean isotope ratios were not significantly different from that of the premixed feline diet. The ∆(15)NHair values for both species were unusually low, potentially due to the protein content and quality of the feline diet. The discrimination factors of the stable isotopes of carbon and nitrogen calculated in this study can be applied to ecological studies of wild, non-captive terrestrial mammals. The effect of protein quality in isotope discrimination is also worthy of further investigation to better understand variation in TDFs. Carnivore scat is shown to be a valuable material for isotopic analysis. Copyright © 2015 John Wiley & Sons, Ltd.

Hydro-climatic control of stream dissolved organic carbon in headwater catchment

NASA Astrophysics Data System (ADS)

Humbert, Guillaume; Jaffrezic, Anne; Fovet, Ophélie; Gruau, Gérard; Durand, Patrick

2014-05-01

Dissolved organic matter (DOM) is a key form of the organic matter linking together the water and the carbon cycles and interconnecting the biosphere (terrestrial and marine) and the soil. At the landscape scale, land use and hydrology are the main factors controlling the amount of DOM transferred from soils to the stream. In an intensively cultivated catchment, a recent work using isotopic composition of DOM as a marker has identified two different sources of DOM. The uppermost soil horizons of the riparian wetland appear as a quasi-infinite source while the topsoil of the hillslope forms a limited one mobilized by water-table rise and exported to the stream across the upland-riparian wetland-stream continuum. In addition to the exportation of DOM via water fluxes, climatic factors like temperature and precipitation regulate the DOM production by influencing microbial activity and soil organic matter degradation. The small headwater catchment (5 km²) of Kervidy-Naizin located in Brittany is part of the Environment Research Observatory (ORE) AgrHys. Weather and the hydro-chemistry of the stream, and the groundwater levels are daily recorded since 1993, 2000 and 2001 respectively. Over 13 contrasted hydrological years, the annual flow weighted mean concentration of dissolved organic carbon (DOC) is 5.6 mg.L-1 (sd = 0.7) for annual precipitation varying from 488mm to 1327mm and annual mean temperatures of 11°C (sd = 0.6). Based on this considerable dataset and this annual variability, we tried to understand how the hydro-climatic conditions determinate the stream DOC concentrations along the year. From the fluctuations of water table depth, each hydrologic year has been divided into three main period: i) progressive rewetting of the riparian wetland soils, ii) rising and holding high of the water table in the hillslope, iii) drawdown of the water-table, with less and less topsoil connected to the stream. Within each period base flow and storm flow data were first

Martian Cryogenic Carbonate Formation: Stable Isotope Variations Observed in Laboratory Studies

NASA Technical Reports Server (NTRS)

Socki, Richard A.; Niles, Paul B.; Sun, Tao; Fu, Qi; Romanek, Christopher S.; Gibson, Everett K. Jr.

2014-01-01

The history of water on Mars is tied to the formation of carbonates through atmospheric CO2 and its control of the climate history of the planet. Carbonate mineral formation under modern martian atmospheric conditions could be a critical factor in controlling the martian climate in a means similar to the rock weathering cycle on Earth. The combination of evidence for liquid water on the martian surface and cold surface conditions suggest fluid freezing could be very common on the surface of Mars. Cryogenic calcite forms easily from freezing solutions when carbon dioxide degasses quickly from Ca-bicarbonate-rich water, a process that has been observed in some terrestrial settings such as arctic permafrost cave deposits, lake beds of the Dry Valleys of Antarctica, and in aufeis (river icings) from rivers of N.E. Alaska. A series of laboratory experiments were conducted that simulated cryogenic carbonate formation on Mars in order to understand their isotopic systematics. The results indicate that carbonates grown under martian conditions show variable enrichments from starting bicarbonate fluids in both carbon and oxygen isotopes beyond equilibrium values.

Factors Controlling Black Carbon Deposition in Snow in the Arctic

NASA Astrophysics Data System (ADS)

Qi, L.; Li, Q.; He, C.; Li, Y.

2015-12-01

This study evaluates the sensitivity of black carbon (BC) concentration in snow in the Arctic to BC emissions, dry deposition and wet scavenging efficiency using a 3D global chemical transport model GEOS-Chem driven by meteorological field GEOS-5. With all improvements, simulated median BC concentration in snow agrees with observation (19.2 ng g-1) within 10%, down from -40% in the default GEOS-Chem. When the previously missed gas flaring emissions (mainly located in Russia) are included, the total BC emission in the Arctic increases by 70%. The simulated BC in snow increases by 1-7 ng g-1, with the largest improvement in Russia. The discrepancy of median BC in snow in the whole Arctic reduces from -40% to -20%. In addition, recent measurements of BC dry deposition velocity suggest that the constant deposition velocity of 0.03 cm s-1 over snow and ice used in the GEOS-Chem is too low. So we apply resistance-in-series method to calculate the dry deposition velocity over snow and ice and the resulted dry deposition velocity ranges from 0.03 to 0.24 cm s-1. However, the simulated total BC deposition flux in the Arctic and BC in snow does not change, because the increased dry deposition flux has been compensated by decreased wet deposition flux. However, the fraction of dry deposition to total deposition increases from 16% to 25%. This may affect the mixing of BC and snow particles and further affect the radative forcing of BC deposited in snow. Finally, we reduced the scavenging efficiency of BC in mixed-phase clouds to account for the effect of Wegener-Bergeron-Findeisen (WBF) process based on recent observations. The simulated BC concentration in snow increases by 10-100%, with the largest increase in Greenland (100%), Tromsø (50%), Alaska (40%), and Canadian Arctic (30%). Annual BC loading in the Arctic increases from 0.25 to 0.43 mg m-2 and the lifetime of BC increases from 9.2 to 16.3 days. This indicates that BC simulation in the Arctic is really sensitive to

40 CFR 721.2084 - Carbon oxyfluoride (Carbonic difluoride).

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Carbon oxyfluoride (Carbonic difluoride). 721.2084 Section 721.2084 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.2084 Carbon...

40 CFR 721.2084 - Carbon oxyfluoride (Carbonic difluoride).

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Carbon oxyfluoride (Carbonic difluoride). 721.2084 Section 721.2084 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT SIGNIFICANT NEW USES OF CHEMICAL SUBSTANCES Significant New Uses for Specific Chemical Substances § 721.2084 Carbon...

Optically controlled dielectric properties of single-walled carbon nanotubes for terahertz wave applications.

PubMed

Smirnov, Serguei; Anoshkin, Ilya V; Demchenko, Petr; Gomon, Daniel; Lioubtchenko, Dmitri V; Khodzitsky, Mikhail; Oberhammer, Joachim

2018-06-21

Materials with tunable dielectric properties are valuable for a wide range of electronic devices, but are often lossy at terahertz frequencies. Here we experimentally report the tuning of the dielectric properties of single-walled carbon nanotubes under light illumination. The effect is demonstrated by measurements of impedance variations at low frequency as well as complex dielectric constant variations in the wide frequency range of 0.1-1 THz by time domain spectroscopy. We show that the dielectric constant is significantly modified for varying light intensities. The effect is also practically applied to phase shifters based on dielectric rod waveguides, loaded with carbon nanotube layers. The carbon nanotubes are used as tunable impedance surface controlled by light illumination, in the frequency range of 75-500 GHz. These results suggest that the effect of dielectric constant tuning with light, accompanied by low transmission losses of the carbon nanotube layer in such an ultra-wide band, may open up new directions for the design and fabrication of novel Terahertz and optoelectronic devices.